СВАРОЧНОЕ ПРОИЗВОДСТВО Rjashhina M.je

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ФЕДЕРАЛЬНОЕ АГЕНТСТВО ПО ОБРАЗОВАНИЮ АСТРАХАНСКИЙ ГОСУДАРСТВЕННЫЙ УНИВЕРСИТЕТ

Автор-составитель: М.Э. Рящина

СВАРОЧНОЕ ПРОИЗВОДСТВО (на английском языке)

Учебно-методическое пособие для студентов, обучающихся по специальности:

031202 Перевод и переводоведение

Издательский дом «Астраханский университет» 2010

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УДК 81'255.2:6 ББК 81.07

Р98

Рекомендовано к печати редакционно-издательским советом Астраханского государственного университета

Ре ц е нз е н т ы: доктор филологических наук,

заведующий кафедрой иностранных языков Астраханского государственного технического университета

Т.В. Дроздова; доктор филологических наук,

директор Астраханского филиала Южно-Российского гуманитарного института

А.А. Баранец Сварочное производство (на английском языке) [Текст] : учебно-

методическое пособие / М. Э. Рящина. – Астрахань : Астраханский госу-дарственный университет, Издательский дом «Астраханский универси-тет», 2010. – 178 с.

Содержит тексты по сварочным технологиям на английском и русском языках,

предназначенные для перевода. Тексты снабжены списком слов, подлежащих усвое-нию, либо представляющих трудности для перевода, рядом упражнений и заданий, на-правленных на расширение словарного запаса студентов и решение переводческих проблем.

Предназначено для студентов III–V курсов переводческого отделения факультета иностранных языков специализации «Переводчик в сфере сварочного производства». Может быть использовано на занятиях по английскому языку студентами физико-математического факультета, изучающих сварочное производство.

ISBN 978-5-9926-03120-5

© Астраханский государственный университет, Издательский дом «Астраханский университет», 2010

© М. Э. Рящина, 2010 © В. Б. Свиридов, дизайн обложки, 2010

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ОГЛАВЛЕНИЕ

ПРЕДИСЛОВИЕ....................................................................................................5 PART 1 ......................................................................................................................6 Unit 1. Welding and cutting......................................................................................6 Unit 2. Gas tungsten arc welding..............................................................................9 Unit 3. Gas tungsten arc welding (GTAW) equipment.........................................13 Unit 4. Submerged arc welding ..............................................................................15 Unit 5. Safety ...........................................................................................................18 Unit 6. Shielded metal arc welding ........................................................................20 Unit 7. SMA welding equipment............................................................................23 Unit 8. Plasma arc welding .....................................................................................27 Unit 9. Gas metal arc welding ................................................................................29 Unit 10. Ultrasonic welding....................................................................................32 Unit 11. Underwater welding..................................................................................35 Unit 12. Что такое сварка? ...................................................................................37 Unit 13. Сварочное оборудование.......................................................................38 Unit 14. Виды сварки.............................................................................................40 ДОПОЛНИТЕЛЬНЫЕ ТЕКСТЫ ...................................................................42 Text 1. Flux-cored arc welding...............................................................................42 Text 2. GTAW weld area ........................................................................................42 Text 3. Safety in GTAW .........................................................................................43 Text 4. Oxy-fuel welding and cutting ....................................................................43 Text 5. Electron beam welding...............................................................................44 Text 6. Laser beam welding....................................................................................45 Text 7. Resistance welding .....................................................................................46 Text 8. Shielding gases............................................................................................47 PART II...................................................................................................................48 Unit 15. Welding defects.........................................................................................48 Unit 16. Avoiding welding defects.........................................................................51 Unit 17. Detection of welding defects....................................................................53 Unit 18. Spot welding..............................................................................................55 Unit 19. Oxy-gas torches (regulators) ....................................................................57 Unit 20. Gas hoses and valves ................................................................................60 Unit 21. Fuels in oxy-fuel welding.........................................................................62 Unit 22. Hazards in oxy-acetylele welding............................................................64 Unit 23. Oxy-acetylene welding (preheating)........................................................66 Unit 24. Torch practice............................................................................................69 Unit 25. Welding ferrous metals.............................................................................73 Unit 26. Welding non-ferrous metals .....................................................................76

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Unit 27. Cold welding .............................................................................................78 Unit 28. General requirements for steel fabrication ..............................................81 Unit 29. Repairs, inspection and tolerances...........................................................83 Unit 30. Fundamentals of resistance method.........................................................85 Unit 31. Applications of resistance welding..........................................................88 Unit 32. Troubles and remedies..............................................................................91 Unit 33. Electric arc welding ..................................................................................94 Unit 34. Soldering....................................................................................................97 Unit 35. Brazing.....................................................................................................101 Unit 36. Thermit welding......................................................................................106 Unit 37. Requirements for welding hulls .............................................................109 Unit 38. Types of connections and preparation ...................................................112 Unit 39. Types of welding in making hulls..........................................................114 Unit 40. Workmanship in making hulls ...............................................................116 Unit 41. Modifications, repairs and testing during construction ........................118 Unit 42. Special requirements...............................................................................120 Unit 43. Weld testing.............................................................................................122 Unit 44. Personnel requirements ..........................................................................124 Unit 45. Welding procedure specifications in ship building...............................126 Unit 46. Safety precautions with acetylene cylinders .........................................128 Unit 47. Oxy-acetylene welding equipment ........................................................130 Unit 48. Oxygen and its production .....................................................................133 Unit 49. Arc welding equipment and accessories................................................137 Unit 50. Gas metal arc welding (GMAW) equipment ........................................141 Unit 51. Electrodes and their use ..........................................................................144 Unit 52. Tungsten electrodes ................................................................................147 Unit 53. Electrodes and their use in AC/DC welding .........................................149 Unit 54. Сварные соединения и швы ................................................................151 Unit 55. Подготовка деталей к сварке ..............................................................153 Unit 56. Газовая сварка .......................................................................................155 Unit 57. Контактная точечная сварка ...............................................................158 Unit 58. Дефекты сварки.....................................................................................161 Unit 59. Автоматическая дуговая сварка .........................................................164 Unit 60. Дуговой автомат....................................................................................167 Unit 61. Сварочные флюсы ................................................................................169 Unit 62. Защитные газы.......................................................................................171 Unit 63. Сварочные горелки ...............................................................................173 БИБЛИОГРАФИЧЕСКИЙ СПИСОК.........................................................176

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ПРЕДИСЛОВИЕ Настоящее учебное пособие предназначено для студентов переводче-

ского отделения факультета иностранных языков, специализирующихся в области перевода текстов по сварочному производству на III–V курсах.

В соответствии с программой специализации, студентам на III курсе предлагается короткий практический курс общетехнического перевода. На этих занятиях на материале общетехнических текстов студентов обучают умению решать проблемы, возникающие при переводе технических текстов. В следующем семестре, когда студенты выбрали одну из предлагаемых спе-циализаций, специалист по сварочному производству на русском языке чита-ет курс «Введение в основы сварочного производства», чтобы познакомить их с основами сварочных процессов и терминологией. Параллельно начина-ется курс специального перевода, рассчитанный на 5 семестров.

В пособии представлены тексты для перевода с английского и русско-го языков. Все тексты являются аутентичными и заимствованы из англий-ских, американских и российских учебников и пособий по сварочному производству, опубликованных в последние два десятилетия.

Каждый текст имеет перечень словарных единиц с переводом и уп-ражнения. Все упражнения разработаны автором-составителем. Сначала количество упражнений достаточно велико, они ориентированы на обога-щение словарного запаса и запоминание терминов, а на старших курсах, по мере расширения специального словаря, количество упражнений умень-шается; они направлены на решение переводческих проблем. Необходи-мость словарных списков обусловлена отсутствием специализированных словарей по сварочному производству.

Тексты по переводу с русского языка на английский повторяют тема-тику ряда текстов на английском языке, однако не дублируют их.

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PART I

Unit 1. WELDING AND CUTTING Welding is the most common way of permanently joining metal parts. In

this process heat is applied to metal pieces, melting and fusing them to form a permanent bond. Because of its strength, welding is used in shipbuilding, auto-mobile manufacturing and repair, aerospace applications, and thousands of other manufacturing activities. Welding is used to join beams when constructing buildings, bridges and other structures, to join pipes in pipelines, power plants, and refineries.

Welders use many types of welding equipment set up in a variety of posi-tions, such as flat, vertical, horizontal and overhead. They may perform manual welding, in which the work is entirely controlled by the welder, or semiauto-matic welding, in which the welder uses machinery, such as a wire feeder, to perform welding tasks.

There are about 100 different types of welding. Arc welding is the most common type. Standard arc welding involves two large alligator clips that carry a strong electrical current. One clip is attached to any part of the workpiece be-ing welded. The second clip is connected to a thin welding rod. When the rod touches the workpiece, a powerful electrical circuit is created. The massive heat produced by the electrical current causes both the workpiece and the steel core of the rod to melt together, cooling quickly to form a solid bond. During weld-ing, the flux that surrounds the rod’s core, vaporizes, forming an inert gas, that serves to protect the weld from atmospheric elements that might weaken it. Welding speed is important. Variations in speed can change the amount of flux applied, weakening the weld, or weakening the surrounding metal by increasing heat exposure.

Two common but advanced types of arc welding are Tungsten Inert Gas (TIG) and Metal Inert Gas (MIG) welding. TIG welding is often used with stainless steel or aluminum. While TIG uses welding rods, MIG uses a spool of continuously fed wire, which allows the welder to join longer stretches of metal without stopping to replace the rod. In TIG welding, the welder holds the weld-ing rod in one hand and an electric torch in the other hand. The torch is used to simultaneously melt the rod and the workpiece. In MIG welding the welder holds the wire feeder, which functions like the alligator clip in arc welding. In-stead of using gas flux surrounding the rod, TIG and MIG protect the initial weld from the environment by blowing inert gas onto the weld.

Like arc welding, soldering and brazing use molten metal to join two pieces of metal. However, the metal added during the process has a melting point lower than that of the work-piece, so only the added metal is melted, not the work-piece. Soldering uses metals with a melting point below 800 oF (about 426 oC); brazing uses metals with a higher melting point. Because soldering and brazing

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do not melt the work-piece, these processes normally do not create the distor-tions or weaknesses in the work-piece that can occur with welding. Soldering is commonly used to join electrical, electronic and other small metal parts. Brazing produces a stronger joint than soldering does, and it is often used to join metals other than steel, such as brass. Brazing can also be used to apply coating to parts to reduce wear and protect against corrosion.

Skilled welding, soldering and brazing workers usually plan work from drawings or specifications or use their knowledge of fluxes and base metals to analyze the parts to be joined. These workers can select and set up welding equipment, execute the planned welds, and examine welds to ensure that they meet standards or specifications. They are even examining the weld while they are welding. By observing problems with the weld, they compensate by adjust-ing the speed, voltage, amperage, or feed of the rod. Highly skilled welders are often trained to work with a wide variety of materials in addition to steel, such as titanium, aluminum, or plastics. Some welders have more limited duties, however. They perform routine jobs that already have been planned and laid out and do not require extensive knowledge of welding techniques.

Automated welding is used in an increasing number of production proc-esses. In these instances, a machine or robot performs welding tasks while moni-tored by a welding machine operator. Welding, soldering and brazing machine setters, operators, and tenders follow specified layouts, work orders or blue-prints. Operators must load parts correctly and constantly monitor the machine to ensure that it produces the desired bond.

The work of arc, plasma and oxy-gas cutters is closely related to that of welders. However, instead of joining metals, cutters use heat from an electric arc, a stream of ionized gas (plasma), or burning gases to cut and trim metal ob-jects to specific dimensions. Cutters also dismantle large objects, such as ships, railroad cars, automobiles, buildings, or aircraft. Some operate and monitor cut-ting machines similar to those used by welding machine operators. Plasma cut-ting has been increasing in popularity because, unlike other methods, it can cut a wide variety of metals, including stainless steel, aluminum, and titanium.

Welding, soldering and brazing workers are often exposed to a number of hazards, including the intense light created by the arc, poisonous fumes, and very hot materials. They wear safety shoes, goggles, hoods with protective lenses and other devices designed to prevent burns and eye injuries and to pro-tect them from falling objects. They normally work in well-ventilated areas to limit their exposure to fumes. Automated welding, soldering and brazing ma-chine operators are not exposed to as many dangers, however, and a face shield or goggles usually provide adequate protection for these workers.

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VOCABULARY welding – сварка weld – (сварной) шов to weld – сваривать, варить to melt – плавить(ся) to fuse – сплавлять(ся) to form a solid bond – образовать прочное / сплошное соединение strength – прочность workpiece – (обрабатываемое) из-делие arc welding – дуговая сварка alligator clips – зажим «крокодил» electrical current – электрический ток welding rod – электрод, стержень flux – флюс Tungsten Inert Gas Welding (TIG) – сварка вольфрамовым электродом в инертном газе Metal Inert Gas Welding (MIG) – сварка металлическим электродом в инертном газе heat exposure – воздействие высо-ких температур, тепла electric torch – сварочная горелка gas flux welding – сварка под флюсом soldering – пайка (мягким припоем) brazing – пайка (твердым припоем) molten metal – расплав, расплав-ленный металл

melting point – точка / температура плавления brass – латунь to apply coating – нанести покрытие to reduce wear – уменьшить износ specifications – технические усло-вия, спецификация base metal – основной металл voltage – напряжение amperage – сила тока automated welding – автоматиче-ская сварка to monitor – наблюдать, контроли-ровать machine setter – наладчик machine tender – механик, оператор specified – соответствующий тех-ническим условиям work order – наряд (на выполнение работы) arc / plasma / oxy-gas cutter – дуго-вой / плазменный / кислородный резак cutter – резчик, резак burning gas – горючий газ to trim – доводить, выравнивать, снимать заусенцы to dismantle – разбирать, демонти-ровать safety shoes – защитная обувь goggles – очки protective lenses – защитные стекла

Упражнения. I. Найдите в тексте английские эквиваленты следующих слов и

словосочетаний: 1) потолочное положение; 2) дуговая сварка; 3) благода-ря своей прочности; 4) стержень электрода; 5) нержавеющая сталь; 6) элек-трогорелка; 7) температура плавления; 8) наносить покрытие; 9) умень-шить износ; 10) устанавливать / налаживать сварочное оборудование; 11) отвечать техническим условиям; 12) ручная сварка, 13) обрабатывае-мое изделие; 14) подача электрода; 15) квалифицированный сварщик;

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16) размечать, наносить разметку; 17) кислородный резак; 18) демонтиро-вать, разбирать; 19) защитные очки; 20) снимать заусенцы, выравнивать.

II. Переведите на русский язык (далее – РЯ) следующие слова и

выражения: 1) to adjust the amperage; 2) routine job; 3) circuit; 4) heat expo-sure; 5) to fuse; 6) welding rod; 7) to form a permanent bond; 8) beam; 9) alliga-tor clip; 10) massive heat; 11) TIG; 12) MIG; 13) to meet standards; 14) over-head position; 15) specifications; 16) welding technique; 17) to monitor; 18) sol-dering; 19) machine setter; 20) electrical current.

III. Охарактеризуйте различие в семантике следующих синонимов:

to melt – to fuse, constant – steady – stable, strength – force – power, standard – normal – usual, clip – clamp, welding rod – electrode, soldering – brazing, tech-nique – technology, to join – to weld – to bind, MIG – TIG, hazard – dander, fume – smoke.

Unit 2. GAS TUNGSTEN ARC WELDING Gas Tungsten Arc Welding (GTAW), also known as Tungsten Inert Gas

welding (TIG), is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area is protected from atmospheric con-tamination by a shielding gas (usually an inert gas such as argon), and a filler metal is normally used, though some welds, known as autogenous welds, do not require it. A constant-current welding power supply produces energy which is conducted across the arc through a column of highly ionized gas and metal va-pours known as plasma.

GTAW is most commonly used to weld thin sections of stainless steel and light metals such as aluminum, magnesium, and copper alloys. The process grants the operator greater control over the weld than competing procedures such as shielded metal arc welding and gas metal arc welding, allowing for stronger, higher quality welds. However, GTAW is comparatively more com-plex and difficult to master, and furthermore, it is significantly slower than most other welding techniques. A related process, plasma arc welding, uses a slightly different welding torch to create a more focused welding arc and as a result it is often automated.

After the discovery of arc in 1800, arc welding developed slowly. C.L. Coffin had the idea of welding in an inert gas atmosphere in 1890, but even in the early 1900s welding non-ferrous materials like aluminum and magnesium remained difficult, because these metals reacted rapidly with the air, resulting in porous and dross-filled welds. Processes using flux covered electrodes did not satisfactorily protect the weld area from contamination. To solve the problem, bottled inert gases were used in the beginning of the 1930s. A few years later, a

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direct current gas-shielded welding process emerged in the aircraft industry for welding magnesium. The process was perfected in 1941 and became known as heliarc or tungsten inert gas welding, because it utilized a tungsten electrode and helium as a shielding gas. Initially, the electrode overheated quickly, and in spite of tungsten’s high melting temperature, particles of tungsten were transferred to the weld. To address the problem the polarity of the electrode was changed from positive to negative, but this made it unsuitable for welding many non-ferrous materials. Finally, the development of alternating current units made it possible to stabilize the arc and produce high quality aluminum and magnesium welds.

Development continued during the following decades. “Linde Air Prod-ucts” developed water-cooled torches that helped to prevent overheating when welding with high currents. Additionally, during 1950s, as the process continued to gain popularity, some users turned to carbon dioxide as an alternative to more expensive welding atmospheres consisting of argon and helium. However, this proved unacceptable for welding aluminum and magnesium because it reduced weld quality, and as a result, it is rarely used with GTAW today.

In 1953, a new process based on GTAW was developed, called plasma arc welding. It affords greater control and improves weld quality by using a nozzle to focus the electric arc, but it is largely limited to automated systems, whereas GTAW remains primarily a manual, hand-held method. Development within the GTAW process has continued as well, and today a number of variations exist.

For GTA welding of carbon and stainless steels, the selection of a filler ma-terial is important to prevent excessive porosity. Oxides on the filler material and workpieces must be removed before welding to prevent contamination, and immediately prior to welding, alcohol or acetone should be used to clean the sur-face. Preheating is generally not necessary for mild steels less than one inch thick, but low alloy steels may require preheating to slow the cooling process and prevent the formation of martensite in the heat-affected zone. Tool steels should also be preheated to prevent cracking in the heat-affected zone. Austen-itic stainless steels do not require preheating, but martensitic and ferritic chro-mium stainless steels do. A DCEN power source is normally used, and thoriated electrodes, tapered to a sharp point, are recommended. Pure argon is used for thin workpieces, but helium can be introduced as thickness increases.

TIG welding of copper and some of its alloys is possible, but in order to get a weld free of oxidation and porosities, shielding gas needs to be provided on the root side of the weld. Alternatively, a special backing tape, consisting of a fiberglass weave on heat-resistant aluminum tape can be used, to prevent air reaching the molten metal.

Welding dissimilar metals often introduces new difficulties to GTA weld-ing, because most materials do not easily fuse to form a strong bond. However, welds of dissimilar materials have numerous applications in manufacturing, re-pair work and the prevention of corrosion and oxidation. In some joints, a com-patible filler material is chosen to help form the bond, and this filler metal can

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be the same as one of the base materials (for example, using a stainless steel filler metal with stainless steel and carbon steel as base materials), or a different metal (such as the use of a nickel filler metal for joining steel and cast iron). Very different materials may be coated with a material compatible with a par-ticular filler material, and then welded. In addition, GTAW can be used in clad-ding or overlaying dissimilar materials.

When welding dissimilar metals, the joint must have an accurate fit, with proper gap dimensions and bevel angles. Care should be taken to avoid exces-sive melting base material. Pulsed current is particularly useful for those appli-cations, as it helps limit the heat input. The filler metal should be added quickly, and a large weld pool should be avoided to prevent dilution of the base material.

VOCABULARY

gas tungsten arc welding (GRAW) – сварка вольфрамовым углеродом в газовой среде TIG – tungsten inert gas welding – сварка вольфрамовым электродом в среде инертного газа non-consumable electrode – непла-вящийся электрод shielding gas – защитный газ filler metal – наполнитель autogenous – автогенный power supply – источник тока column – зд. – струя vapours – пары magnesium – магний alloy – сплав shielded (metal) arc welding – дуго-вая сварка в защитной среде ме-таллическим электродом gas metal arc welding – газовая ду-говая сварка металлическим элек-тродом a more focused weld – зд. – более ровный шов non-ferrous metals – цветные ме-таллы to react – реагировать dross – окалина bottled gas – баллонный газ direct current – постоянный ток

heliarc welding – дуговая сварка в гелиевой среде polarity – полярность alternating current – переменный ток water-cooled torches – водоохлаж-даемая горелка welding atmosphere – зд. – защит-ная среда при сварке process – зд. – технология nozzle – наконечник, мундштук increased penetration – более глу-бокое проникновение mild steel – низкоуглеродистая, мягкая сталь low alloy – низколегированный сплав martensite – мартенсит, кристалли-зация твердого тела cracking – растрескивание austenitic – аустенитный, содер-жащий твердый раствор углерода и легирующих элементов ferritic – ферритный, содержащий железо DCEN – direct current with a nega-tively charged electrode DCEP – direct current with a posi-tively charged electrode

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thoriated – торированный, покры-тый торием tapered – конусообразный root side – основание шва fiberglass – стекловолокно heat resistant – жароупорный, жа-ростойкий dissimilar – разнородный carbon steel – углеродистая сталь cast iron – чугун cladding – плакирование, покрытие

to coat – покрывать overlaying – покрытие слоем крас-ки, лака и др. to have an accurate fit – плотно прилегать gap dimensions – размеры зазора bevel angle – угол скоса pulsed current – импульсный ток weld pool – зона расплава dilution – разжижение wire – проволочный электрод


словосочетаний: 1) неплавящийся электрод; 2) источник тока; 3) цветные металлы; 4) баллонный газ; 5) переменный ток; 6) постоянный ток; 7) сплав; 8) защитная среда при сварке; 9) (отрицательное) воздействие ок-ружающей среды; 10) источник тока постоянной величины; 11) шов, за-грязненный окалиной; 12) решить проблему; 13) двуокись углерода; 14) прогревание; 15) жаростойкий; 16) плотно прилегать; 17) зона распла-ва, сварочная ванна; 18) чугун; 19) размеры зазора; 20) заостренный, кону-сообразный.

II. Расшифруйте следующие аббревиатуры и дайте перевод их

полных форм: GTAW, TIG, MIG, DCEN, DCEP, DC, AC. III. Переведите на РЯ следующие слова и словосочетания: 1) filler

metal; 2) copper alloys; 3) shielded metal arc welding; 4) atmospheric contami-nation; 5) heliarc inert gas welding; 6) polarity of the electrode; 7) to produce high quality welds; 8) water-cooled torch; 9) to reduce weld quality; 10) carbon steel; 11) to prevent contamination; 12) tool steel; 13) root side of the weld; 14) dissimilar metals; 15) to form a bond; 16) compatible material; 17) weld pool; 18) dilution;19) base material; 20) to utilize tungsten electrodes.

IV. Охарактеризуйте различия в семантике синонимов: contamina-

tion – pollution, to use – to utilize – to employ, seam – weld, respond – react, application – use.

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Unit 3. GAS TUNGSTEN ARC WELDING (GTAW) EQUIPMENT In tungsten inert gas (TIG) welding, (also known as GTAW), an arc is

struck between a virtually non-consumable tungsten electrode and the work-piece. The heat of the arc causes the edges of the work to melt and flow to-gether. Filler rod is often required to fill the joint. During the welding operation, the weld area is shielded from the atmosphere by a blanket of inert argon gas. A steady stream of argon passes through the torch, which pushes the air away from the welding area and prevents oxidation of the electrode, weld puddle, and heat affected zone.

The basic equipment requirements for manual TIG welding are as follows. The equipment consists of the welding torch plus additional apparatus to

supply electrical power, shielding gas, and a water inlet and outlet. Also, per-sonal protective equipment should be worn to protect the operator from the arc rays during welding operations.

Different types of TIG welding equipment are available through normal supply channels. Water-cooled torches and air-cooled torches are both available. Each type carries different amperage ratings. Consult the appropriate manual covering the type of the torch used.

Argon is supplied in steel cylinders containing approximately 330 cu ft at a pressure to 2000 psi (13,790 kPa). A single or two stage regulator may be used to control the gas flow. A specially designed regulator containing a flowmeter may be used. The flowmeter provides better adjustment via flow control than the single or two stage regulator and is calibrated in cubic feet per hour (cfh). The correct flow of argon to the torch is set by turning the adjusting screw on the regulator. The rate of flow depends on the kind and thickness of the metal to be welded.

Blanketing of the weld area is provided by a steady flow of argon gas, di-rected through the welding torch. Since argon is slightly more than 1–1/3 times as heavy as air, it pushes the lighter air molecules aside, effectively preventing oxidation of the welding electrode, the molten weld puddle, and the heat af-fected zone adjacent to the weld bead.

The tremendous heat of the arc and the high current often used usually ne-cessitate water cooling of the torch and power cable. The cooling water must be clean; otherwise, restricted or blocked passages may cause excessive overheat-ing and damage to the equipment. It is advisable to use a suitable water strainer or filter at the water supply source. If a self-contained unit is used, such as the one used in the field (surge tank) where the cooling water is recirculated through a pump, antifreeze is required if the unit is to be used outdoors during the winter months or freezing weather. Some TIG welding torches require less than 55 psi (379 kPa) water pressure and will require a water regulator of some type. Check the operating manual for this information.

Nomenclature of a Torch:

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1) a cap prevents the escape of gas from the top of the torch and locks the electrode in place;

2) a collet is made of copper; the electrode fits inside and when the cap is tightened, it squeezes against the electrode and keeps it in place;

3) a gas orifice nut allows the gas to escape; 4) a gas nozzle directs the flow of shielding gas onto the weld puddle. Two

types of nozzles are used; the one for light duty welding is made of a ceramic material, and the one for heavy duty welding is a copper water-cooled nozzle;

5) there are three plastic hoses, connected inside the torch handle, carrying water, gas, and the electrode power cable.

VOCABULARY

water inlet – подвод воды normal supply channels – обычная торговая сеть water-cooled torch – водоохлаж-даемая горелка amperage rating – номинальная си-ла тока flowmeter – расходомер, газомер adjusting screw – регулировочный винт passage – канал, рукав для подачи воды water strainer – фильтр self-contained unit – автономная установка

surge tank – уравнительный резер-вуар to recirculate – циркулировать в замкнутом цикле antifreeze – антифриз (вещество, предупреждающее замерзание жидкостей) collet – конусная втулка gas orifice nut – гайка на выходном отверстии для газа light duty welding – сварка с не-большой нагрузкой nomenclature – перечень (частей комплекта), комплектность gas nozzle – газовое сопло


словосочетаний: 1) двухкамерный редуктор; 2) градуировать шкалу; 3) аргон на 1/3 тяжелее воздуха; 4) утечка газа; 5) фиксировать электрод; 6) присадочный пруток; 7) расходомер; 8) находящийся рядом, прилегаю-щий; 9) засорение канала; 10) конусная втулка.

II. Переведите следующие слова и словосочетания: 1) a blanket of

inert gas; 2) weld puddle; 3) heat affected zone; 4) a manual, covering the type of the torch used; 5) to push the air away; 6) additional apparatus; 7) nomencla-ture; 8) to calibrate; 9) the water is recirculated through the pump; 10) heavy duty welding.

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III. Переведите на английский язык (далее – АЯ) следующие предложения.

1. Дуговую сварку в среде защитного газа применяют для снижения вредного воздействия атмосферных газов на сварочную ванну. 2. При сварке неплавящимся электродом инертный газ подается на шов через го-релку и вытесняет воздух из зоны сварки. 3. Дуговая сварка неплавящимся электродом в среде защитного газа известна также, как сварка вольфрамо-вым электродом, который практически не плавится. 4. Инертный газ хра-нится в баллонах под давлением примерно 2000 psi. 5. Использование га-зомера обеспечивает лучшее регулирование потока газа, чем редуктор. 6. Так как аргон тяжелее воздуха, он вытесняет воздух из зоны сварки и предупреждает процессы окисления в ней. 7. При работе в полевых усло-виях воду можно использовать в замкнутом цикле с помощью насоса. 8. Сопло направляет струю защитного газа на сварочную ванну. 9. Сопло изготавливают из керамики или из меди. 10. Комплект оборудования для дуговой сварки неплавящимся электродом в защитной среде включает го-релку и дополнительные устройства для подачи электропитания, защитно-го газа, подвода и отвода воды.

Unit 4. SUBMERGED ARC WELDING Submerged arc welding (SAW) is a common arc welding process. It re-

quires a continuously fed consumable solid or tubular (metal cored) electrode. The molten weld and the arc zone are protected from atmospheric contamination by being “submerged” under a blanket of granular fusible flux. When molten, the flux becomes conductive and provides a current path between the electrode and the work. SAW is normally operated in the automatic or mechanized mode, however, semi-automatic (hand-held) SAW guns with pressurized or gravity flux feed delivery are available. Deposition rates approaching 100 lb/h (45 kg/h) have been reported – this compares to 10 lb/h (5kg/h) (max) for shielded metal arc welding. Currents ranging from 200 to 1500 A are commonly used; currents of up to 5000 A have been used (multiple arcs). Single or multiple (2 to 5) elec-trode wire variations of the process exist. DC or AC power can be utilized, and combinations of DC and AC are common in multiple electrode systems. Con-stant voltage welding power supplies are most commonly used, however con-stant current systems in combination with a voltage sensing wire feeder are available.

Material applications are carbon steels, low alloy steels, stainless steels, nickel-based alloys, surfacing applications are wear-facing, build-up, and corro-sion resistant overlay of steels.

Advantages of SAW: 1) high deposition rates (over 100 lb/h (45 kg/h) have been reported; 2) high operating factors in mechanized applications; 3) deep

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weld penetration; 4) sound welds are readily made (with good process design and control); 5) high speed welding of thin sheet steels at over 100 in/min (2,5 m/min) is possible; 6) minimal welding fume or arc light is emitted.

Limitations of SAW: 1) limited to ferrous (steel or stainless steels) and some nickel based alloys; 2) normally limited to long straight welds or rotated pipes or vessels; 3) it requires relatively troublesome flux handling systems; 4) flux and slag residue can present a health and safety issue; 5) requires inter-pass and post-weld slag removal.

Key SAW process variables: 1) wire-feed speed (main factor in welding current control); 2)arc voltage; 3) travel speed; 4) electrode stick-out (ESO) or contact tip to work (CTTW); 5) polarity and current type (AC or DC).

Other factors: 1) flux depth / width; 2) flux and electrode classification and type; 3) electrode wire diameter; 4) multiple electrode configuration.

VOCABULARY Submerged arc welding – (дуговая) сварка под флюсом consumable – расходуемый solid electrode – сплошной электрод tubular – трубчатый granular – гранулированный mode – режим semi-automatic SAW gun – пистолет для полуавтоматической сварки feed delivery – подача pressurized – герметичный, под давлением gravity – сила тяжести A (amper) – ампер multiple arc welding – многоточеч-ная сварка single electrode – одиночный элек-трод multiple electrode – множествен-ный электрод strip electrode – ленточный электрод DC / AC – постоянный / перемен-ный ток

voltage sensing – чувствительный к напряжению material application – использова-ние материала low-alloy steel – низколегирован-ная сталь corrosion-resistant – антикоррозий-ный, устойчивый к коррозии deposition rate – производитель-ность / скорость наплавки operating factor – эксплуатация deep weld penetration – глубокое проплавление sound weld – прочный, качествен-ный шов limited to – не выходящий за пределы slag – шлак residue – осадок, остаток post weld slag removal – удаление шлака после сварки, зачистка variable – переменная


словосочетаний: 1) дуговая сварка под флюсом; 2) плавкий флюс; 3) пис-толет для полуавтоматической сварки; 4) глубокое проплавление; 5) про-

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изводительность / скорость наплавки; 6) электропроводный; 7) в автомати-ческом режиме; 8) источник питания; 9) низколегированная сталь; 10) гер-метичный; 11) ленточный электрод; 12) вредный дым; 13) сила тяжести; 14) шлак; 15) удаление шлака; 16) многоточечная сварка; 17) прочный шов; 18) переменная (величина); 19) плавкий, расходуемый; 20) вредное действие атмосферы.

II. Переведите на РЯ следующие слова и словосочетания: 1) carbon

steel; 2) stainless steel; 3) build-up; 4) wearfacing; 5) molten weld; 6) granular flux; 7) to range; 8) wire-feeder; 9) constant current; 10) consumable electrode; 11) solid electrode; 12) application; 13) ferrous alloys; 14) residue; 15) design; 16) operating factors; 17) polarity; 18) to emit; 19) process control; 20) key vari-ables.

III. Охарактеризуйте различия в семантике синонимов: rate –

speed – velocity, to feel – to sense, application – use – usage, coal – carbon, guard – shield – protect – defend

IV. Вставьте нужное слово или словосочетание, используя содер-

жание текста. 1. High deposition … is one of SAW advantages. 2. This process requires continuously fed … electrode. 3. SAW is normally … in the automatic or semiautomatic mode. 4. Currents … from 200 to 1500A are commonly used. 5. … current is current flowing in one direction only. 6. … current does not change its quantity. 7. Wearfacing and build-up are referred to surfacing … of SAW. 8. One of SAW advantages is that minimal welding fume or arc light is … . 9. This process is normally limited … long straight welds. 10. The molten weld and the arc zone are … from atmospheric contamination. V. Переведите на АЯ следующие предложения. 1. При дуговой сварке под флюсом требуется плавкий сплошной или

трубчатый электрод. 2. Шов защищен от вредного действия атмосферы флюсом. 3. Расплавленный флюс становится электропроводным. 4. Чаще всего используются источники тока с постоянным напряжением. 5. Этот метод применим лишь для сварки сплавов железа. 6. К самым важным пе-ременным процесса относятся полярность и ток – переменный или посто-янный. 7. Дуговая сварка под флюсом применяется для сварки низколеги-рованных и нержавеющих сталей. 8. При правильном расчете и контроле за процессом получают прочные швы. 9. Результаты сварки могут зависеть от типа используемых флюса и электрода.

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Unit 5. SAFETY Users of our company’s welding equipment have the ultimate responsibility

for ensuring that anyone who works on or near the equipment observes all the relevant safety precautions. Safety precautions must meet requirements that ap-ply to this type of welding equipment. The following recommendations should be observed in addition to standard regulations that apply to the work-place.

All work must be carried out by trained personnel, well acquainted with the operation of the welding equipment, incorrect operation of the equipment may lead to hazardous situations which can result in injury to the operator and dam-age to the equipment.

1. Anyone who uses this welding equipment must be familiar with: its operation; location of energy stops; its function; relevant safety precautions. 2. The operator must ensure that: no unauthorized person is stationed within the working area of the

equipment when it is started up; no-one is unprotected when the arc is struck. 3. The workplace must: be suitable for the purpose; be free from draughts. 4. Personal safety equipment: always wear recommended personal safety equipment, such as safety

glasses, flame-proof clothing, safety gloves; do not wear loose- fitting items, such as scarves, bracelets, rings, etc.,

which could become trapped or cause burns. 5. General precautions: make sure the return cable is connected securely; work on high voltage equipment may be carried out only by a qualified

electrician; appropriate fire extinguishing equipment must be clearly marked and

close at hand; lubrication and maintenance must not be carried out on the equipment

during operation. Warning. Arc welding and cutting can be injurious to yourself and others. Take pre-

cautions when welding. Ask for your employer’s safety practices which should be based on manufacturer’s hazard data.

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Electric shock can kill: install and earth the welding unit in accordance with applicable stan-

dards; do not touch live electrical parts with bare skin, wet gloves or wet clothing; insulate yourself from earth and the workpiece; ensure your working stance is safe. Fumes and gases can be dangerous to health: keep your head out of the fumes; use ventilation, extraction at the arc, or both, to take fumes and gases

away from your breathing zone and the general area. Arc rays – can injure eyes and burn skin: protect your eyes and body. Use the correct welding screen and filter

lens and wear protective clothing; protect by-standers with suitable screens or curtains. Fire hazard: sparks (spatter) can cause fire. Make sure therefore that there are no in-

flammable materials nearby. Noise: protect your ears. Use earmuffs or other hearing protection; warn by-standers of the risk. Malfunction: call for expert assistance in the event of malfunction.

VOCABULARY safety precautions – меры техники безопасности emergency stop – аварийный вы-ключатель unauthorized person – посторонний safety glasses – защитные очки (из безосколочного стекла) flame-proof – негорючий return cable – обратный провод fire-extinguishing – противопожар-ный lubrication – смазка maintenance – техническое обслу-живание

safety practices – меры безопасно-сти hazard data – сведения об авариях to earth – заземлять live electrical parts – части или де-тали под напряжением to insulate – изолировать working stance – рабочее место filter lens – светофильтр spatter – брызги (металла) inflammable – горючий, легко вос-пламеняющийся earmuff – беруши (приспособле-ние для защиты от шума) manual – руководство, инструкция

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Unit 6. SHIELDED METAL ARC WELDING Shielded metal arc welding (SMAW), also known as manual metal arc

welding (MMA) is a manual arc welding process that uses a consumable elec-trode coated in flux to lay the weld. An electric current, in the form of either al-ternating current or direct current from a welding power supply, is used to form an electric arc between the electrode and the metals to be joined. As the weld is laid, the flux coating of the electrode disintegrates giving off vapors that serve as a shielding gas and providing a layer of slag, both of which protect the weld area from atmospheric contamination.

Because of versatility of the process and simplicity of its equipment and operation, shielded metal arc welding is one of the world’s most popular weld-ing processes. It dominates other welding processes in the maintenance and re-pair industry. And though flux-covered arc welding is growing in popularity, SMAW continues to be used extensively in the construction of steel structures and in industrial fabrication. The process is used primarily to weld iron and steels, including stainless steel, but aluminum, nickel and copper alloys can also be welded with this method.

To strike the electric arc the electrode is brought into contact with the workpiece in a short sweeping motion and then pulled away slightly. This initi-ates the arc and thus melting of the workpiece and the consumable electrode, and causes droplets of the electrode to be passed from the electrode to the weld-ing pool. As the electrode melts, the flux disintegrates and its vapors protect the weld area from oxygen and other atmospheric gases. In addition, the flux pro-vides molten slag which covers the filler metal as it travels from the electrode to the weld pool. Once part of the weld pool, the slag floats to the surface and pro-tects the weld from contamination as it solidifies. Once hardened, it must be chipped away to reveal the finished weld. As welding progresses and the elec-trode melts, the welder must periodically stop welding to remove the remaining electrode stub and insert a new electrode into the electrode holder. This activity, combined with chipping away the slag, reduce the amount of time that the welder could spend laying the weld, making SMAW one of the least efficient welding processes. In general, the operator factor, or the percentage of opera-tor’s time spent laying weld, is approximately 25 %.

The actual welding technique utilized depends on the electrode, the compo-sition of the work-piece, and the position of the joint being welded. The choice of electrode and welding position also determines the welding speed. Flat welds require the least operator skill, and can be done with electrodes that melt quickly but solidify slowly. This permits higher welding speeds. Sloped, vertical or up-side-down welding requires more operator skill, and often necessitates the use of an electrode that solidifies quickly to prevent the molten metal from flowing out of the weld pool. However, this generally means that the electrode melts less quickly, thus increasing the time required to lay the weld.

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The most common quality problems associated with SMAW include weld spatter, porosity, poor fusion, shallow penetration and cracking. Weld spatter, while not affecting the integrity of the weld, damages its appearance and in-creases cleaning costs. It can be caused by excessively high current, a long arc, or arc blow, a condition associated with direct current characterized by the elec-tric arc being deflected away from the weld pool by magnetic forces. Arc blow can also cause porosity in the weld, as can joint contamination, high welding speed, and a long welding arc, especially when low-hydrogen electrodes are used. Porosity, often not visible without the use of advanced non-destructive testing methods, is a serious concern because it can potentially weaken the weld. Another defect affecting the strength of the weld is poor fusion, though it is of-ten easily visible. It is caused by low current, contaminated joint surfaces, or the use of an improper electrode. Shallow penetration, another detriment to weld strength, can be addressed by decreasing welding speed, increasing the current or using a smaller electrode. Any of these weld-strength-related defects can make the weld prone to cracking, but other factors are involved as well. High carbon or sulfur content in the base material can lead to cracking, especially if low-hydrogen electrodes and preheating are not employed. Furthermore, the workpieces should not be excessively restrained, as this introduces residual stresses into the weld and can cause cracking as the weld cools.

SMA welding, like other welding methods, can be a dangerous and un-healthy practice if proper precautions are not taken. The process uses an open electric arc, presenting a risk of burns which is prevented by personal protective equipment in the form of heavy leather gloves and long sleeve jackets. Addi-tionally, the brightness of the weld area can lead to a condition called arc eye, in which ultraviolet light causes the inflammation of the cornea and can burn the retinas of the eyes. Welding helmets with dark face plates are worn to prevent this exposure, and in recent years, new helmet models have been produced fea-turing a face plate that self-darkens upon exposure to high amounts of UV light. To protect by-standers, especially in industrial environments, transparent weld-ing curtains often surround the welding area. These curtains, made of polyvinyl chloride plastic film, shield nearby workers from exposure to the UV light from the electric arc, but should not be used to replace the filter glass used in helmets.

In addition, the vaporizing metal and flux materials expose welders to dan-gerous gases and particulate matter. The smoke produced contains particles of various types of oxides. The size of the particles in question tends to influence the toxicity of the fumes, with smaller particles presenting a greater danger. Ad-ditionally, gases like carbon dioxide and ozone can form, which can prove dan-gerous if ventilation is inadequate.

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VOCABULARY SMAW – shielded metal arc welding – дуговая сварка металлическим электродом в защитной среде consumable electrode – плавящийся электрод to disintegrate – разлагаться, рас-падаться to give off – зд. – выделять versatility – зд. – многофункцио-нальность maintenance – техническое обслу-живание flux-cored electrode – фитильный электрод с флюсом to strike the arc – включить, зажечь дугу molten slag – расплавленный шлак to solidify – застывать to chip away – скалывать stub – огарок электрода industrial fabrication – промыш-ленное производство to initiate – вызывать, начинать filler metal – наплавочный металл electrode holder – держатель электрода

composition – состав weld spatter – брызги (металла при сварке) penetration – глубина проплавления high current – ток большой вели-чины arc blow – уход, сдвиг дуги to deflect – отклоняться, уходить в сторону restrain – зажимать residual stress – остаточное напря-жение arc eye – ослепление от света дуги, «сварки нахвататься» cornea – роговица глаза retina – сетчатка (глаза) filter glass - светофильтр welding helmet – маска, шлем (сварщика) particulate matter – мелкие частицы clamp – зажим welding lead – питающий провод arc distance / length – расстояние / длина дуги fluctuations – отклонения, колебания


выражений: 1) обслуживание техники; 2) сварка металлическим электро-дом в защитной среде; 3) ручная дуговая сварка; 4) переменный ток; 5) прокладывать шов; 6) слой шлака; 7) дуговая сварка; 8) фитильный элек-трод; 9) привести электрод в контакт, дотронуться; 10) сварочная ванна; 11) наплавочный металл; 12) застывать; 13) ток высокого напряжения; 14) остаточное напряжение; 15) колебания; 16) хрупкость; 17) растягиваю-щее напряжение; 18) стыковой шов; 19) угловой шов; 20) предпоследний.

II. Переведите на РЯ следующие слова и словосочетания: 1) coated

in flux; 2) direct current; 3) industrial fabrication; 4) copper alloys; 5) to initiate the arc; 6) to disintegrate; 7) atmospheric gases; 8) to chip the slag away; 9) electrode stub; 10) electrode holder; 11) efficient process; 12) sloped weld-

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ing; 13) upside-down welding; 14) weld spatter; 15) porosity; 16) to deflect away; 17) non-destructive testing methods; 18) precautions; 19) inflammation of the cornea; 20) exposure to the ultraviolet light.

III. Охарактеризуйте различие в семантике синонимов: coated –

covered, efficient – effective, solidify – harden, last – ultimate – final, to float – to swim, transparent – translucent, influence – affect – impact.

IV. Вставьте нужное слово, используя содержание текста. 1. An electric current in the form of either … or … current is used to form

an electric arc. 2. As the weld is laid, the flux coating of the electrode … . 3. Flux vapours serve as a … gas. 4. To strike the electric arc, the electrode is … with the workpiece. 5. If electrodes … quickly but … slowly this permits higher welding speeds. 6. Droplets of molten metal are called … . 7. Porosity, often not visible, can be detected by … methods. 8. Poor fusion is another … affecting the strength of the weld. 9. High carbon or sulfur … in the base material can lead to cracking. 10. Proper … should be taken to avoid hazards.

Unit 7. SMA WELDING EQUIPMENT SMAW equipment usually consists of a constant current welding power

supply and an electrode, with an electrode holder, a work clamp, and welding cables, also known as welding leads. The power supply has constant current output, ensuring that the current (and thus the heat) remains relatively constant, even if the arc distance and voltage change. This is important because most ap-plications of SMAW are manual, requiring that an operator hold the torch. Maintaining a suitably steady arc distance is difficult if a constant voltage power source is used instead, since it can cause dramatic heat variations and make welding more difficult. However, because the current is not maintained abso-lutely constant, skilled welders performing complicated welds can vary the arc length to cause minor fluctuations in the current.

The preferred polarity of the SMAW system depends primarily upon the electrode being used and the desired properties of the weld. Direct current with a negatively charged electrode (DCEN) causes heat to build up on the electrode, increasing the electrode melting rate and decreasing the depth of the weld. Re-versing the polarity so that the electrode is positively charged and the workpiece negatively charged increases the weld penetration. With alternating current, the polarity changes over 100 times per second, creating an even heat distribution and providing a balance between electrode melting rate and penetration.

The choice of electrode for SMAW depends on a number of factors, includ-ing the weld material, welding position and desired weld properties. The elec-trode is coated in a metal mixture called flux, which gives off gases as it decom-

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poses to prevent weld contamination, introduces deoxidizers to purify the weld, causes weld-protecting slag to form, improves the arc stability, and provides al-loying elements to improve the weld quality. Electrodes can be divided into three groups – those designed to melt quickly are called fast-fill electrodes, those designed to solidify quickly are called fast-freeze electrodes and intermediate electrodes go by the name fill-freeze or fast-follow electrodes. Fast-fill elec-trodes are designed to melt quickly so that the welding speed can be maximized, while fast-freeze electrodes supply filler metal that solidifies quickly, making welding in a variety of positions possible by preventing the weld pool from shifting significantly before solidifying.

The composition of the electrode core is generally similar and sometimes identical to that of the base material. But even though a number of feasible op-tions exist, a slight difference in the alloy composition can strongly impact the properties of the resulting weld. This is especially true of alloy steels such as HSLA steels. Likewise, electrodes of compositions similar to those of base ma-terials are often used for welding non-ferrous materials such as aluminum and copper. However, sometimes it is desirable to use electrodes with core materials significantly different from the base material. For example, stainless steel elec-trodes are sometimes used to weld two pieces of carbon steel.

Electrode coatings can consist of a number of different compounds, includ-ing rutile, calcium fluoride, cellulose, and iron powder. Rutile electrodes, made of 25–45 % TiO2, are characterized by ease of use and good appearance of the resulting weld. However, they create welds with high hydrogen content, encour-aging embrittlement and cracking. Electrodes, containing calcium fluoride (CaF2), sometimes known as basic low-hydrogen electrodes, are hydroscopic and must be stored in dry conditions. They produce strong welds, but with a coarse and convex-shaped joint surface. Electrodes made of cellulose, especially when combined with rutile, provide deep weld penetration, but because of their high moisture content, special procedures must be used to prevent excessive risk of cracking. Finally iron powder is a common coating additive, as it improves the productivity of the electrode, sometimes as much as doubling the yield.

To identify different electrodes, the American Welding Society established a system that assigns electrodes with a four- or five-digit number. Covered elec-trodes made of mild or low-alloy steel carry the prefix E-, followed by their number. The first two or three digits of the number specify the tensile stress of the weld metal, in thousand pounds per square inch (psi). The penultimate digit generally identifies the welding positions permissible with the electrode, typi-cally using the values 1 (normally fast-freeze electrodes, implying all position welding) and 2 (normally fast-fill electrodes, implying horizontal welding only). The welding current and type of electrode covering are specified by the last two digits together. When applicable, a suffix is used to denote the alloying element being contributed by the electrode. Common electrodes include the E6010, a fast-freeze, all-position electrode with minimum tensile strength of 60 psi which

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is operated using DCEP. Its cousin E6011 is similar except that it is used with alternating current. E7024 is a fast-fill electrode, used primarily to make flat or horizontal welds using AC, DCEN, or DCEP. Examples of fill-freeze electrodes are the E6012, E6013 and E7014, all of which provide a compromise between fast welding speeds and all-position welding.

Though SMAW is almost exclusively a manual arc welding process, one notable process variation exists, known as gravity welding or gravity arc weld-ing. It serves as an automated version of the traditional shielded metal arc weld-ing process, employing an electrode holder attached to an inclined bar along the length of the weld. Once started, the process continues until the electrode is spent, allowing the operator to manage multiple gravity welding systems. The electrodes employed (often 6027 or 7024) are coated heavily in flux, and are typically 0,8 m in length and about 6 mm thick. As in manual SMAW, a con-stant current welding power supply is used, with either negative polarity direct current or alternating current.

Due to a rise in the use of semi-automatic welding processes such as flux-cored arc welding, the popularity of gravity welding has fallen as its economic advantage over such methods is often minimal. Other SMAW-related methods that are even less frequently used include fire-cracker welding, an automatic method of making butt and fillet welds, and massive electrode welding, a proc-ess for welding large components or structures that can deposit up to 27 kg of weld metal per hour.

VOCABULARY

clamp – зажим cable = welding lead – кабель, пи-тающий провод arc distance / length – длина дуги fluctuations – колебания deoxidizer – деоксидант fast-freeze – быстро примерзаю-щий fast-fill – быстро плавящийся filler metal – присадочный металл coating – обмазка, покрытие rutile – рутил, двуокись титана + железо calcium fluoride – фтористый кальций embrittlement – хрупкость convex – выпуклый

tensile strength – прочность на рас-тяжение penultimate – предпоследний DCEN = direct current, electrode negative DCEP = direct current, electrode positive HSLA = high strength low alloy Pa = pascal – паскаль, единица давления и механического напря-жения gravity arc welding – гравитацион-ная дуговая сварка flux-cored electrode – фитильный электрод fire-cracker – сварка-фейерверк butt weld – стыковой шов fillet weld – угловой шов

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словосочетаний: 1) питающий провод; 2) источник тока постоянной вели-чины; 3) горелка; 4) небольшие колебания; 5) накапливаться на электроде; 6) изменять полярность на противоположную; 7) положительно / отрица-тельно заряженный электрод; 8) сердцевина электрода; 9) состав электро-да; 10) влиять на свойства; 11) фтористый кальций; 12) хрупкость; 13) вы-сокое содержание влаги; 14) добавка, присадка; 15) предпоследняя цифра; 16) низколегированная сталь; 17) полуавтоматический процесс; 18) удво-ить результат; 19) угловой шов; 20) стыковой шов.

II. Переведите на РЯ следующие слова и словосочетания: 1) a

steady arc distance; 2) constant voltage; 3) dramatic heat variations; 4) to main-tain constant current; 5) fluctuations in the current; 6) weld penetration; 7) melt-ing rate; 8) to purify the weld; 9) fast-fill electrodes; 10) fast-freeze electrodes; 11) fill-freeze electrodes; 12) low hydrogen electrodes; 13) calcium fluoride; 14) feasible options; 15) composition of the electrode core; 16) non-ferrous ma-terials; 17) electrode coating; 18) to encourage cracking; 19) hygroscopic; 20) to assign electrodes with a number.

III. Вставьте нужное слово или словосочетание. 1. The power supply used in SMAW has constant current … . 2. Most

SMAW applications are … . 3. Maintaining a steady … is difficult. 4. The pre-ferred … of the SMAW system depends primarily upon the electrode used and the desired properties of the weld. 5. With … the polarity changes over 100 times per second. 6. The … of the electrode core is sometimes identical to that of the base material. 7. Rutile electrodes create welds with high hydrogen content, … embrittlement and cracking. 8. Electrodes containing CaF2 are … and must be stored in dry conditions. 9. The first two or three digits of the num-ber … the tensile stress of the weld metal. 10. The welding current and type of electrode coating are specified by the last two … together.

IV. Охарактеризуйте различие в семантике синонимов: to decom-

pose – to disintegrate, to influence – to impact – to affect, to purify – to clean, figure – digit, manual – hand-made.

V. Соотнесите термин и его определение. 1. Electrodes designed to melt quickly so that the welding speed can be

maximized. 2. Electrodes designed to supply filler metal that solidifies quickly. 3. Electrodes intermediate in the speed of melting and solidifying.

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4. Welding process employing consumable electrodes coated in flux which, while disintegrating, gives off a shielding gas.

5. Current which does not change its amperage or voltage. 6. Positive or negative charge of the electrode. 7. Negative impact that gases making air get upon the weld. 8. Materials easily absorbing moisture from the environment. 9. The process or property of being easily broken or cracked. 10. One of the elements that combine to form numbers in a numeric system.

Unit 8. PLASMA ARC WELDING Plasma arc welding (PAW) is an arc welding process similar to gas tung-

sten arc welding (GTAW). The electric arc is formed between an electrode, which is usually but not always made of sintered tungsten and the work-piece. The key difference from GTAW is that in PAW, by positioning the electrode within the body of the torch, the plasma arc can be separated from the shielding gas envelope. The plasma is then forced through a fine-bore copper nozzle which connects the arc and the plasma exits the orifice at high velocities, ap-proaching the speed of sound, and temperature approaching 20 000 ºC.

Plasma arc welding is an advancement over the GTAW process. It can be used to join all metals that are weldable with GTAW, i.e. most commercial metals and alloys. Several basic PAW variations are possible by varying the current, plasma gas flow rate, and the orifice diameter, including: micro-plasma (< 15 Am-peres); melt-in mode (15–400 Amperes); key-hole mode (100 Amperes). Plasma arc welding has a greater energy concentration as compared to GTAW. A deep nar-row penetration is achievable, reducing distortion and allowing square-butt joints in material up to 12 mm thick. Greater arc stability allows a much longer arc length and much greater tolerance to arc length changes. Its limitation is that PAW re-quires relatively expensive and complex equipment as compared to GTAW.

At least two separate (and possibly three) gas flows are used in PAW: plasma gas which flows through the orifice and becomes ionized; shielding gas, which flows through the outer nozzle and shields the molten weld from the at-mosphere; back-purge gas, required for certain materials and applications. These gases can be the same, or of differing composition.

Key process variables are: current type and polarity; usually DCEN from a CC source; AC square wave, common on aluminum and magnesium. Current can vary from 0,5 to 1200 A; current can be constant or pulsed at frequencies up to 20 kHz. Gas flow rate is a critical variable and must be carefully controlled based upon the current, orifice diameter and shape, gas mixture, and the base material and thickness.

Depending upon the design of the torch, e.g. orifice diameter, electrode de-sign, gas type and velocities, and the current levels, several variations of the

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plasma process are achievable, including plasma arc welding, plasma arc cut-ting, plasma arc gouging, plasma arc surfacing and plasma arc spraying.

VOCABULARY

GTAW – gas tungsten arc welding – дуговая сварка вольфрамовым электродом в среде защитного газа sintered – зд. – металлокерамиче-ский gas envelope – зд. – газовый пузырь fine bore – отверстие малого раз-мера to constrict – сжимать orifice – отверстие velocity – скорость commercial metals – металлы про-мышленного значения plasma gas flow rate – скорость по-тока плазмы arc stability – устойчивость, ста-бильность горения дуги

tolerance – зд. – допуск, допусти-мое отклонение от заданных па-раметров arc length – длина дуги outer nozzle – наружный мунд-штук back-purge gas – газ, очищающий обратную сторону шва square wave – прямоугольный им-пульс constant current – ток постоянной величины gourging – строжка, поверхностная резка surfacing – нанесение покрытия, обработка поверхности arc spraying – электрометаллиза-ция, нанесение металлического покрытия


словосочетаний: 1) основное различие; 2) корпус горелки; 3) газовый пу-зырь; 4) отверстие; 5) скорость; 6) скорость звука; 7) скорость потока плаз-мы; 8) металлы промышленного значения; 9) деформация; 10) квадратное стыковое соединение; 11) допустимое отклонение (от заданных парамет-ров); 12) газ, очищающий обратную сторону шва; 13) прямоугольный им-пульс; 14) магний; 15) конструкция электрода.

II. Переведите на РЯ следующие слова и словосочетания: 1) sin-

tered tungsten; 2) forced through; 3) fine-bore nozzle; 4) high velocity; 5) ad-vancement; 6) orifice diameter; 7) to vary the current; 8) arc stability; 9) square butt; 10) outer nozzle; 11) pulsed current; 12) gouging; 13) surfacing; 14) arc spraying; 15) current levels.

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III. Вставьте нужное слово или словосочетание. 1. Plasma arc welding is … to gas tungsten arc welding. 2. In PAW the

plasma arc is separated from the … . 3. The plasma is … through a fine-bore copper nozzle. 4. The plasma exits the orifice at … . 5. PAW has a greater … as compared to GTAW. 6. PAW reduces distortion and allows … in thick materi-als. 7. Greater arc stability allows much greater … to arc length changes. 8. Paw requires relatively … and … equipment. 9. Plasma gas flows through the … and becomes highly ionized. 10. Shielding gas protects the … from the atmospheric contamination.

IV. Переведите на АЯ следующие предложения. 1. Плазма – это поток сильно ионизированного газа. 2. Плазменная ду-

га может быть отделена от защитного газового пузыря. 3. При плазменной сварке электрод размещен в корпусе горелки. 4. Плазменная сварка пред-ставляет собой шаг вперед по сравнению с газовольфрамовой. 5. Варианты плазменной сварки различаются по силе тока, скорости потока плазмы и диаметра отверстия. 6. При плазменной сварке возможно проплавление большой глубины и малой ширины. 7. Защитный газ проходит через на-ружный мундштук. 8. Используемые при плазменной сварке газы могут быть как одинаковыми, так и разными по составу. 9. Обычно используют отрицательный электрод при источнике тока постоянной величины, не за-висящей от напряжения дуги. 10. При сварке алюминия и магния обычно используется переменный ток с прямоугольным импульсом.

Unit 9. GAS METAL ARC WELDING Gas metal arc welding (GMAW), sometimes referred to by its subtypes,

metal inert gas (MIG) and metal active gas (MAG) welding, is a semi-automatic or auto-matic arc welding process in which a continuous and consumable wire electrode and a shielding gas are fed through a welding gun. A constant voltage, direct current power source is most commonly used with GMAW, but constant current systems, as well as alternating current, can be used.

Originally developed for welding aluminum and other non-ferrous metals in the 1940s, GMAW was soon applied to steels because it allowed for lower welding time compared to other welding processes. The cost of inert gas limited its use in steels until several years later, when the use of semi-inert gases such as carbon dioxide became common. Further developments during 1950s and 1960s gave the process more versatility and as a result, it became a highly used indus-trial process. Today, GMAW is commonly used in industries such as the auto-mobile industry, where it is preferred for its versatility and speed. Unlike weld-ing processes that do not employ a shielding gas, such as shielded metal arc welding, it is rarely used outdoors or in other areas of air volatility. A related

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process, flux-cored arc welding, often does not utilize a shielding gas, instead employing a hollow electrode wire that is filled with flux on the inside.

The method is often used to do arc spot welding, thereby replacing riveting or resistance spot welding. It is also popular in robot welding, in which robots handle the work-pieces and the welding gun to quicken the manufacturing proc-ess. Generally, it is unsuitable for welding outdoors, because the movement of the surrounding atmosphere can cause the dissipation of the shielding gas and thus makes welding more difficult, while also decreasing the quality of the weld, so the use of GMAW in the construction industry is rather limited. The problem can be alleviated to some extent by increasing the shielding gas output, but this can be expensive. The use of a shielding gas makes GMAW an unpopular un-derwater welding process, and for the same reason it is rarely used in space ap-plications.

To perform gas metal arc welding, the basic necessary equipment is a welding gun, a wire feed unit, a welding power supply, an electrode wire, and a shielding gas supply. The typical welding gun has a number of key parts – a control switch, a contact tip, a power cable, a gas nozzle, an electrode conduit and liner, and a gas hose. The control switch or trigger, when pressed by the operator, initiates the wire feed, electric power and the shielding gas flow, causing an electric arc to be struck. The contact tip, normally made of copper and sometimes chemically treated to reduce spatter, is connected to the weld-ing power supply source through the power cable and transmits the electrical energy to the electrode while directing it to the weld area. It must be firmly se-cured and properly sized since it must allow the passage of the electrode while maintaining an electrical contact. Before arriving at the contact tip, the wire is protected and guided by the electrode conduit and liner, which help prevent buckling and maintain an uninterrupted wire feed. The gas nozzle is used to evenly direct the shielding gas into the welding zone – if the flow is inconsis-tent, it may not provide adequate protection of the weld area. Larger nozzles provide greater shielding gas flow, which is useful for high current welding operations, in which the size of the molten weld pool is increased. The gas is supplied to the nozzle through a gas hose, which is connected to tanks of shielding gas. Sometimes a water hose is also built into the welding gun, cool-ing the gun in high heat operations.

The wire unit supplies the electrode to the work, driving it through the con-duit and on to the contact tip. Most models provide the wire at constant feed rate, but more advanced machines can vary the feed rate in response to the arc length and voltage. Some wire feeders can reach feed rates as high as 30,5 m/min, but feed rates for semi-automatic GMAW typically range from 2 to 10 m/min.

Most applications of gas metal arc welding use a constant voltage power supply. As a result, any change in arc length, which is directly related to voltage, results in a large change in heat input and current. A shorter arc length will

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cause a much greater heat input, which will make the wire electrode melt more quickly and thereby restore the original arc length. This helps operators keep the arc length consistent even when manually welding with hand-held welding guns. To achieve a similar effect, sometimes a constant current power source is used in combination with an arc voltage-controlled wire feed unit. In this case, a change in arc length makes the wire feed rate adjust in order to maintain a rela-tively constant arc length. In rare circumstances, a constant current power source and a constant wire feed rate unit might be coupled, especially for the welding of metals with high thermal conductivity, such as aluminum. This grants the op-erator additional control over the heat input into the weld, but requires signifi-cant skill to perform successively.

VOCABULARY

gas metal arc welding (GMAW) – дуговая сварка плавящимся элек-тродом в среде защитного газа metal inert gas (MIG) welding – ду-говая сварка плавящимся электро-дом в среде инертного газа metal active gas (MAG) welding – дуговая сварка плавящимся элек-тродом в среде активного газа welding gun – сварочный пистолет versatility – многосторонность, разнообразие spot welding – точечная сварка riveting welding – сварка электро-заклепками resistance spot welding – контакт-ная точечная сварка

robot welding – сварка с помощью робота dissipation – рассеяние wire feed unit – устройство для по-дачи сварочной проволоки control switch – включатель contact tip – контактный конец электрода conduit – желоб liner – выравниватель, направ-ляющее устройство gas hose – газовый шланг buckling – искривление, выпучи-вание to couple – соединить thermal conductivity – теплопро-водность anode – анод


словосочетаний: 1) дуговая сварка плавящимся электродом в среде инертного газа; 2) дуговая сварка плавящимся электродом в среде защит-ного газа; 3) дуговая сварка плавящимся электродом в среде активного га-за; 4) источник постоянного тока; 5) цветные металлы; 6) полуинертный газ; 7) двуокись углерода; 8) разнообразие, многосторонность применения; 9) дуговая сварка под флюсом; 10) защитный газ; 11) сварка порошковой проволокой (трубчатым электродом); 12) точечная сварка; 13) сварка элек-трозаклепками; 14) подключать, соединять; 15) включатель.

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II. Переведите на РЯ следующие слова и словосочетания: 1) wire feed unit; 2) welding gun; 3) non-ferrous metals; 4) resistance spot welding; 5) dissipation; 6) conduit; 7) gas hose; 8) air volatility; 9) to alleviate a problem; 10) key parts; 11) to initiate the wire feed; 12) to strike the arc; 13) the conduit tip; 14) to reduce spatter; 15) to be firmly secured; 16) gas nozzle; 17) tanks of gas; 18) high heat operation; 19) to drive (the electrode) through the conduit; 20) thermal conductiveness.

III. Найдите в тексте синонимичны данным слова и выражения:

to decrease, control switch, welder, to employ a gas, widely, medium ot atmos-phere, to start the wire feed, to initiate an arc, metal droplets, wire-feed unit.

IV. Вставьте нужное слово или словосочетание. 1. Aluminum and copper are … metals. 2. Gas protecting the weld area is

called a … gas. 3. GMAW is given preference for its speed and … . 4. The movement of the surrounding atmosphere can cause … of the shielding gas. 5. The problem can be … by increasing the shielding gas output. 6. The … initi-ates the wire feed. 7. The contact tip, made of copper, … the electrical energy to the electrode. 8. Before arriving at the contact tip, the wire is protected and guided by the … . 9. The … is used to evenly direct the shielding gas into the welding area.

V. Дайте полную форму следующих аббревиатур: GMAW, MAG,

MIG, DCEN, DCEP, PAW.

Unit 10. ULTRASONIC WELDING Ultrasonic welding is an industrial technique whereby high-frequency ul-

trasonic acoustic vibrations are used to weld objects together, usually plastics, and especially for joining dissimilar materials. This type of welding is used to build assemblies that are too small, too complex or too delicate for more com-mon welding techniques. In ultrasonic welding there are no connecting bolts, nails, soldering materials or adhesives necessary to bind the materials together.

For joining complex injection-molded thermoplastic parts, ultrasonic equipment can be easily customized to fit the exact specifications of parts being welded. The parts are sandwiched between a fixed shaped nest (anvil) and a sonotrode (horn) connected to a transducer which is lowered down, and a 20 kHz low-amplitude acoustic vibration is emitted. Common frequencies used in ultrasonic welding of thermoplastics are 15 kHz, 30 kHz, and 40 kHz. When welding plastics, the interface of the two parts is specially designed to concen-trate the melting process. One of the materials traditionally has a spiked energy director which contacts the second plastic part. The ultrasonic energy melts the

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point of contact between the parts, creating a joint. This process is a good auto-mated alternative to glue, screws or snap-fit designs. It is typically used with small parts, e.g. cell phones, consumer electronics, disposable medical tools, toys etc., but it can be used on parts as large as a small automobile instrument cluster. Ultrasonics can also be used to weld metals, but they are typically lim-ited to small welds of thin, malleable metals, e.g. aluminum, copper, nickel. Ul-trasonics would not be used in welding the chassis of an automobile or in weld-ing pieces of a bicycle together, because of the power levels required.

Ultrasonic welding of thermoplastics causes local melting of the plastic due to absorption of vibration energy. The vibrations are introduced across the joint to be welded. Ultrasonic welding of metals is not due to heating, but instead oc-curs due to high-pressure dispersion of surface oxides and local motion of the materials. Although there is heating, it is not enough to melt the base materials. Vibrations are introduced along the joint being welded.

Ultrasonic welding appeared in mid-1960s and is rapidly developing. In its infancy only hard plastics could be welded because they were acoustically con-ductive and had a low melting point. Today ultrasonic welding machines have much more power, enough to weld less rigid, less acoustically conductive mate-rials such as semi-crystalline plastics, as well as higher melting point materials. The patent for the ultrasonic method for welding rigid thermoplastic parts was awarded to R. Soloff in 1965.

An inevitable by-product of ultrasonic welding is a blast of ultrasonic sound. The lower frequencies of 15 kHz and 20 kHz typically emit a squeal that can be heard by operators. In many cases the noise level will exceed 80 dBa and therefore hearing protection is recommended when personnel are in close prox-imity to an ultrasonic welder. Welders using frequencies of 30 kHz and above do not normally emit a squeal audible to people in close proximity to the welder. It is widely accepted that most humans can hear ultrasonic noise as children but lose this ability around the late teens. A device known as “The Mosquito” which emits ultrasonic noise and is intended to break up groups of loiterers is being tested in the UK, mostly outside shops and other places where youths gather. However not all humans lose this ability so early and some never do. Persons who can hear ultrasonic sound would not be comfortable working in a factory or other environment where it is used without using hearing protection.

VOCABULARY

ultrasonic – ультразвуковой connective – соединительный to customize – доукомплектовать в соответствии с требованиями за-казчика thermoplastic – термопластик anvil – наковальня

sonotrode – сонотрод horn – рог (разрядник) transducer – преобразователь spiked energy director – заострен-ный директор энергии glue – клей

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adhesive – связующее, клейкое вещество snap-fit design – защелка cell phone – мобильный телефон consumer electronics – бытовая электроника disposable – одноразовый cluster – набор, комплект malleable – ковкий, пластичный, тянущийся

automotive – передвижной power level – уровень мощности dispersion – дисперсия, рассеивание melting point – точка плавления dB – децибел, единица измерения шума dBa / dBA – децибел А (превы-шающий определенный уровень шума)


словосочетаний: 1) промышленная технология; 2) звуковые колебания; 3) припой; 4) приводить в соответствие с (индивидуальными требованиями); 5) наковальня; 6) преобразователь; 7) частота; 8) образовать соединение; 9) защелка; 10) одноразовый; 11) бытовая электроника; 12) поглощение; 13) нагревание; 14) низкая температура плавления; 15) уровень мощности.

II. Переведите на РЯ следующие слова и словосочетания: 1) dis-

similar materials; 2) assembly; 3) connective bolts; 4) adhesives; 5) to sandwich; 6) interface; 7) a spiked energy director; 8) cell phone; 9) malleable materials; 10) dispersion of surface oxides; 11) be acoustically conductive; 12) in its in-fancy; 13) rigid; 14) to introduce vibrations; 15) semi-crystalline plastics.

III. Вставьте нужное слово или словосочетание. 1. Ultrasonics are usually limited to small welds of thin … metals. 2. Ultra-

sonic welding employs … acoustic vibrations. 3. Ultrasonic welding equipment can be easily … to fit specifications of the parts being welded. 4. In ultrasonic welding the parts being welded are … between a fixed shaped nest and a sonotrode. 5. … is connected to the sonotrode, emitting high-frequency vibra-tions. 6. When welding plastics, the … of the two parts is specially designed. 7. Ultrasonics is used in manufacturing … medical tools. 8. Ultrasonics causes local melting of the plastic due to … of the vibration energy. 9. While welding thermoplastics, vibrations should be introduced … the joint to be welded. 10. Ultrasonic welding of metals occurs due to … of surface oxides and local motion of the materials.

IV. Переведите на АЯ следующие предложения. 1. Сварка ультразвуком часто используется для соединения разнород-

ных материалов. 2. Оборудование для ультразвуковой сварки можно легко привести в соответствие с техническими требованиями. 3. При сварке

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ультразвуком используются акустические колебания высокой частоты. 4. Энергия ультразвука плавит место контакта свариваемых деталей. 5. Алюминий, медь, никель относят к пластичным металлам. 6. При ульт-развуковой сварке термопластиков пластик плавится за счет поглощения энергии вибрации. 7. На заре метода ультразвуковой сварки ее могли ис-пользовать только для соединения твердых пластиков, проводящих звук. 8. Неизбежным следствием ультразвуковой сварки является выброс ульт-развука. 9. Во многих случаях уровень шума превышает 80 децибел А. 10. Работникам, находящимся поблизости от места ультразвуковой сварки, необходимо защищать органы слуха.

V. Назовите слово по его определению. 1. Material capable of softening or fusing when heated and of hardening

again when cooled. 2. Having a frequency above human ear’s audibility limit of about 20 000 hertz. 3. Manufactured parts fitted together into a complete structure or unit. 4. To build, fit or alter according to individual specifications. 5. Interception of radiant energy or sound waves. 6. The process of uniformly distributing small particles in a fluid or divid-

ing white light into its coloured constituents. 7. (of metals) that can be hammered or pressed out of shape without ten-

dency to return to it or to fracture. 8. Having the property of transmitting heat or electricity by conduct. 9. Nearness in space, time etc. 10. Incidental or secondary product of manufacture. 11. A device that converts variations of one quantity into those of another. 12. A device for reducing or increasing voltage and current. 13. A unit used in comparison of power levels in sound intensity. 14. A unit of frequency equal to one cycle per second. 15. To go through the process of testing qualities of a thing or method.

Unit 11. UNDERWATER WELDING Underwater welding refers to a number of distinct processes that are per-

formed underwater. The two main categories of this techniques are wet under-water welding and dry underwater welding, both classified as hyperbaric weld-ing. In wet underwater welding, a variation of shielded metal arc welding is commonly used, employing a waterproof electrode. Other processes that are used include flux-cored welding and friction welding. In each of these cases, the welding power supply is connected to the welding equipment through cables and hoses. The process is generally limited to low carbon equivalent steels, espe-cially at greater depths, because of hydrogen-caused cracking. In dry underwater

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welding the weld is performed at the prevailing pressure in a chamber filled with a gas mixture sealed around the structure being welded. For this process, gas tungsten arc welding is often used, and the resulting welds are of high integrity.

The applications of underwater welding are diverse – it is often used to re-pair ships, offshore oil platforms and pipelines. Steel is the most common mate-rial welded. For deep water welds and other applications where high strength is necessary, dry underwater welding in most commonly used. Research into using dry underwater welding at depths of up to 1000 meters is ongoing. In general, assuring the integrity of underwater welds can be difficult, but it is possible us-ing non-destructive testing applications, especially for wet underwater welds, because defects are difficult to detect if they are beneath the surface of the weld.

For the structures being welded by wet underwater welding, inspection fol-lowing welding and assuring the integrity of such welds may be more difficult than for welds deposited in air. There is a risk that defects may remain unde-tected.

The risks of underwater welding include the risk of electric shock to the welder. To prevent this, the welding equipment must be adaptable to a marine environment, properly insulated and the welding current must be controlled. Underwater welders must also consider safety issues that normally divers face; most notably, the risk of decomposition sickness due to the increased pressure of inhaled breathing gases. Another risk, generally limited to wet underwater weld-ing, is the build-up of hydrogen and oxygen pockets, because these are poten-tially explosive.

VOCABULARY

wet underwater welding – влажная подводная сварка dry underwater welding – сухая подводная сварка hyperbaric – гипербарический, пре-вышающий нормальное давление waterproof – водонепроницаемый, водоотталкивающий friction welding – сварка трением chamber – камера

sealed – герметичный integrity – цельность to assure – гарантировать non-destructive testing method – не-разрушающий метод контроля insulated – изолированный (электр.) decomposition sickness – кессонная болезнь pocket – зд. – пузырь


словосочетаний: 1) дуговая сварка в защитной среде; 2) водоотталкиваю-щий, водонепроницаемый; 3) сварка фитильным электродом; 4) сварка тре-нием; 5) сталь с низким содержанием углерода; 6) растрескивание, вызван-ное водородом; 7) газовольфрамовая сварка; 8) нефтяные платформы;

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9) высокая прочность; 10) целостность шва; 11) неразрушающие методы исследования; 12) обнаружить дефект; 13) удар электротоком; 14) изоли-ровать; 15) кессонная болезнь.

II. Переведите на РЯ следующие слова и словосочетания: 1) hyper-

baric welding; 2) dry underwater welding; 3) wet underwater welding; 4) a sealed chamber; 5) gas mixture; 6) prevailing pressure; 7) diverse applications; 8) high strength; 9) adaptable to marine environment; 10) properly insulated; 11) safety issue; 12) breathing gases; 13) to inhale; 14) build-up of hydrogen pocket; 15) potentially explosive.

III. Переведите на АЯ следующие предложения. 1. Сварка под давлением имеет две основные разновидности – влаж-

ная и сухая подводная сварка. 2. Влажная подводная сварка является раз-новидностью сварки под флюсом. 3. Подводная сварка обычно использу-ется лишь для низкоуглеродистых сталей. 4. Водород, содержащийся в на-плавленном металле, снижает его пластичность и вызывает растрескива-ние. 5. При подводной сварке используется водонепроницаемый электрод. 6. При сухой подводной сварке шов выполняется в герметичной камере, заполненной газовой смесью. 7. Сухая подводная сварка обеспечивает бо-лее прочный и надежный шов. 8. Для проверки подводных швов исполь-зуются различные неразрушающие методы контроля. 9. При подводной сварке сварщик может получить удар электротока. 10. Сварочное оборудо-вание должно быть приспособлено для работы в морской среде.

Unit 12. ЧТО ТАКОЕ СВАРКА? Сварка – это сложный технологический процесс, который позволяет

соединить две детали или два материала неразъемным соединением. Су-ществует множество способов сварки. Современные технологии позволя-ют соединять в единое целое даже такие разные по структуре материалы, как стекло и пластик. Развитие техники привело к появлению новых видов сварочного оборудования. Всего за сто лет технологии обработки металлов пополнились такими методами, как роликовая и точечная контактная свар-ка, которые используют металлические и угольные электроды. Сегодня сварочные процессы используются во всех сферах производства и народ-ного хозяйства. Современные технологии позволяют соединять любые ме-таллы и сплавы. Более того, в промышленности применяется сварка пла-стмасс, стекла, различных огнеупорных материалов.

Сварочный электрод – изделие из электропроводного материала, он предназначен для подвода тока к сварочной дуге. Электроды подразделя-ются на плавящиеся (проволока) и неплавящиеся (электродные стержни).

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Горелка – устройство для образования смесей газообразного или жид-кого топлива с воздухом или кислородом и подачи их к месту сварки.

Сварочные материалы предназначены для сварки и пайки металлов и сплавов. К сварочным материалам относятся электроды, сварочная прово-лока, флюсы и припои.

Сварочная (электрическая) дуга образуется в зоне сварки при прохо-ждении электрического тока через газ между электродами.

Флюс – химическое вещество, применяемое для улучшения растека-ния жидкого припоя при паянии. Припой – это металл или сплав, который имеет более низкую температуру плавления, чем соединяемые металлы, он служит также для очистки места пайки. Во многих видах сварки исполь-зуемые флюсы имеют сложный состав.

Легированные металлы включают различные добавки, которые при-дают металлу особые свойства.

Переменный ток течет в одном направлении, затем – в другом, посто-янно меняя направление. Постоянный ток всегда течет в одном направле-нии, но может увеличиваться или уменьшаться.

Сварочный аппарат – источник питания для сварочной дуги. Газосва-рочное оборудование используется для сварки и резки металлов. Для сварки используется энергия горючего газа в смеси с кислородом или воздухом.

VOCABULARY

неразъемное соединение – a solid bond технология – process, technology угольный электрод – carbon elec-trode точечная сварка – spot welding роликовая сварка – roller welding контактная сварка – resistance welding

припой – solder переменный ток – alternating cur-rent постоянный ток – direct current легированный – alloyed добавка – additive увеличиваться / уменьшаться (о токе) – to amplify / to attenuate

Unit 13. СВАРОЧНОЕ ОБОРУДОВАНИЕ Сварочное оборудование – это аппараты, устройства и приспособле-

ния, которые используются для изготовления сварных изделий. Другие термины – сварочный пост – комплекс сварочного оборудования, несколь-ко таких постов образуют сварочную линию. К сварочному оборудованию относятся также сварочные автоматы, которые производят сварку; приспо-собления для быстрой сборки деталей для сварки; оборудование для пере-мещения деталей; крепления для сварочных аппаратов. При сварке исполь-зуются также и другие вспомогательные инструменты.

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Существуют 4 основные группы сварочного оборудования. 1. Сварочные генераторы. Это электромеханические приборы, состоя-

щие из двигателя и мощного генератора. Энергия сгорания топлива в двигателе передается в генератор, где она преобразуется в электрический ток. Если гене-ратор поддерживает постоянство сварочной дуги, его называют сварочным аг-регатом. Если двигатель является однофазным или трехфазным, то получаем сварочный преобразователь. Сварочные агрегаты имеют уникальную особен-ность: они не требуют подключения к электросети, поэтому их можно исполь-зовать в любом месте автономно. Но из-за автономности они получаются большими и тяжелыми, и их применяют в основном в строительстве.

2. Сварочные трансформаторы. Это простые, дешевые, широко ис-пользуемые сварочные аппараты для ручной дуговой сварки. На контакты трансформатора подается переменный ток. Он вызывает переменный магнит-ный поток, который, в свою очередь, вызывает переменный ток с понижен-ным напряжением. Это напряжение приводит к нагреву свариваемых поверх-ностей. Трансформаторы получили широкое распространение из-за простоты конструкции, невысокой цены и высокой надежности. Конечно, у них есть и минусы: это большие габариты и то, что переменный ток не может создать ровный шов. У новичков могут возникнуть сложности в начале работы с трансформатором.

3. Сварочные выпрямители. Это трансформатор, источник питания и блок полупроводниковых выпрямителей. Аппарат вырабатывает постоянный ток, дуга не прерывается и отличается стабильностью. Данная особенность позволяет качественно использовать выпрямители даже непрофессионалам. При применении дополнительных приборов выпрямители могут сваривать цветные металлы и чугун.

4. Сварочные инверторы. Это аппараты, обладающие повышенной частотой, которая позволяет при меньшем весе и габаритах производить бо-лее мощную сварку. Такая сварка обеспечивает ровный аккуратный сварной шов и устойчивую дугу.

VOCABULARY

сварочный пост – welding station сварочный автомат – welding auto-matic machine сборка – assembly крепление – clip, fix двигатель – engine генератор – generator поддерживать постоянство дуги – to support stability of arc одно/трехфазный – mono-uni-phase – three-phase преобразователь – converter

электросеть – mains магнитный поток – magnetic induction напряжение – voltage нагрев – heating конструкция – design минус, недостаток – defect, draw-back ровный шов – uniform weld сплав – alloy источник питания – power source полупроводниковый выпрямитель – semi-conductor rectifier

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Unit 14. ВИДЫ СВАРКИ Первый в истории вид сварки – кузнечная. Соединение металлов осу-

ществляется за счет возникновения межатомных связей при пластическом деформировании инструментом – ковочным молотом. В настоящее время в промышленности практически не используется.

Существует 3 основных промышленных вида сварки: термическая, термомеханическая и механическая, каждая из которых имеет ряд разно-видностей.

Термическая сварка. 1. Электродуговая сварка. Сваривание двух материалов происходит

за счет теплоты, выделяемой электрической дугой. При выделении тепла происходит расплавление свариваемых поверхностей и получается жидкий металл. После застывания металла свариваемые части становятся единым целым. У нее есть ряд разновидностей:

ручная дуговая сварка. Используется специальный электрод, по-крытый флюсом. Флюс защищает шов от внешнего воздействия;

сварка неплавящимся электродом. Используется электрод в виде графитового или вольфрамового стержня. Эти материалы используются потому, что их температура плавления выше температуры, при которой ведется сварка;

сварка плавящимся электродом. В качестве электрода используется проволока из металла. Электрическая дуга плавит проволоку, и постоянно подается новая партия проволоки. Для защиты шва от действия атмосферы сварщики используют инертные газы – гелий, аргон, а также углекислый газ;

сварка под флюсом. Электрод представлен также металлической проволокой, на конец которой подается слой флюса. Плавление происхо-дит в газовом пузыре между слоем флюса и металлом, характеристики проплавления металла улучшаются.

2. Газопламенная сварка. Теплота выделяется за счет сгорания го-рючего газа – бутана, водорода, ацетилена. Это тепло расплавляет поверх-ности и обеспечивает их сварку.

3. Электрошлаковая сварка. Источник теплоты – флюс, который расположен между свариваемыми поверхностями. Ток, проходящий через него, разогревает флюс и сваривает изделие.

4. Плазменная сварка. Электрический ток нагревает электроды, ко-торые, в свою очередь, нагревают газ между ними. Результатом является плазменная струя горящего газа. Специальный электромагнит сжимает эту струю и придает ускорение. Горячая струя плазмы сваривает поверхности.

5. Электронно-лучевая сварка. Этот сложный процесс осуществля-ется только в промышленных условиях, в вакуумных камерах. Сварка про-изводится благодаря термоэлектронной эмиссии с катода электронно-лучевой пушки.

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6. Лазерная сварка. Элементом, который выделяет тепло и расплав-ляет металл, является луч лазера. Использование этого метода также воз-можно лишь в промышленных условиях.

Термомеханическая сварка – это сварка посредством нагревания. Ее

подвиды: контактная сварка. При такой сварке одновременно нагреваются

изделия и происходит их деформация, обеспечивая взаимное проникнове-ние металлов. Детали зажимаются в сварочных клещах, и по электродам пускают ток высокого напряжения, который плавит детали. Затем проис-ходит выключение тока и сильное сжатие клещей, в результате металл кристаллизуется, образуя сварной шов;

диффузионная сварка. За счет очень высокой температуры проис-ходит взаимное проникновение и соединение атомов;

сварка токами высокой частоты. Изделия располагают вплотную друг к другу и пропускают через них ток высокой частоты, который дефор-мирует их. Затем изделиям дают остыть и получают сварное соединение.

Механическая сварка – это сварка взрывом. Этот вид сварки осуще-

ствляют за счет сближения атомов изделий благодаря энергии, выделяемой при взрыве.

VOCABULARY

межатомная связь – inter-atomic bond / link термическая сварка – thermal welding сварка взрывом – explosion welding твердеть – solidify испускать, излучать – to emit покрытие – coating действие воздуха – atmospheric contamination графит – graphite подавать проволоку – to feed wire пузырь – envelope газопламенная сварка – gas flame welding

ацетилен – acetylene электрошлаковая сварка – electro-slag welding плазменная сварка – plasma welding струя – jet, stream ускорение – acceleration электронно-лучевая сварка – elec-tron beam welding контактная сварка – resistance welding диффузионная сварка – diffusion welding кузнечная сварка – forge welding сварка токами высокой частоты – high frequency welding

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ДОПОЛНИТЕЛЬНЫЕ ТЕКСТЫ Text 1. Flux-cored arc welding. Flux-cored arc welding (FCAW) is a semi-automatic or automatic arc

welding process. FCAW requires a continuously fed consumable tubular elec-trode containing a flux and constant voltage or, less commonly, a constant elec-tric current welding power supply. An externally supplied shielding gas is some-times used, but often the flux itself is relied upon to generate the necessary pro-tection from the atmosphere. The process is widely used in construction because of its high welding speed and portability.

FCAW was first developed in the early 1950s as an alternative to shielded metal arc welding (SMAW). The advantage of FCAW versus SMAW is that the use of stick electrodes, like those used in SMAW, was unnecessary. This helped FCAW to overcome many of the restrictions associated with SMAW.

There are two types of FCAW. The first type requires no shielding gas. This is made possible by the flux core in the tubular consumable electrode. However, this core contains more than just flux; it also contains various ingredi-ents that when exposed to high temperatures of welding generate a shielding gas for protecting the arc. This type of FCAW is preferable because it is portable and has excellent penetration into the base metal. Also, the conditions of air flow do not need to be considered.

The second type of FCAW actually uses a shielding gas that must be sup-plied by an external device. This type of FCAW was developed primarily for welding steels. In fact, since it uses both a flux-cored electrode and an external shielding gas, one might say that it is a combination of gas metal (GMAW) and flux-cored arc welding. This particular style of FCAW is preferable for welding thicker metals. The slag created by the flux is also easier to remove. However, it cannot be used in a windy environment as the loss of the shielding gas from air flow will produce visible porosity on the surface of the weld.

Text 2. GTAW weld area. Manual gas tungsten arc welding is often considered the most difficult of

all the welding processes commonly used in industry. Because the welder must maintain a short arc length, great care and skill are required to prevent contact between the electrode and the workpiece. Unlike other welding processes, GTAW normally requires two hands, since most applications require that the welder manually feed a filler metal into the weld area with one hand, while ma-nipulating the welding torch in the other. However, some welds combining thin materials can be accomplished without filler metal; most notably edge, corner and butt joints.

To strike the welding arc, a high frequency generator provides a path for the welding current through the shielding gas, allowing the arc to be struck when the separation between the electrode and the workpiece is approximately 1.5–3 mm.

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Bringing the two into contact also serves to strike an arc, but this can cause con-tamination of the weld and electrode. Once the arc is struck, the welder moves the torch in a small circle to create a welding pool, the size of which depends on the size of the electrode and the current. While maintaining a constant separation between the electrode and the workpiece, the operator then moves the torch back slightly and tilts it backward about 10–15 degrees from the vertical. Filler metal is added manually to the front end of the weld pool as it is needed.

Welders often develop a technique of rapidly alternating between moving the torch forward, to advance the weld pool, and adding filler metal. The filler rod is withdrawn from the weld pool each time the electrode advances, but it is never removed from the gas shield to prevent oxidation of its surface and con-tamination of the weld. Filler rods composed of metals with low melting tem-perature, such as aluminum, require that the operator maintain some distance from the arc while staying inside the gas shield. If held too close to the arc, the filler rod can melt before it makes contact with the weld pool. As the weld nears completion, the arc current is often gradually reduces to prevent the formation of a crater at the end of the weld.

Text 3. Safety in GTAW. Like other welding processes, GTAW can be dangerous if proper precau-

tions are not taken. The process produces intense ultraviolet radiation, which can cause a form of sunburn an, in a few cases, trigger the development of skin can-cer. Flying sparks and droplets of molten metal can cause severe burns and start a fire, if flammable material is nearby.

It essential that the welder wear suitable protective clothing, including heavy leather gloves, a closed shirt collar to protect the neck and especially the throat, a protective long sleeve jacket and a suitable helmet to prevent arc eye. Due to the absence of smoke in GTAW, the electric arc can seem brighter than in shielded metal arc welding. Transparent welding curtains, made of a polyvinyl chloride plastic film, are often used to shield nearby personnel from exposure.

Welders are also often exposed to dangerous gases and particulate matter. Shielding gases can displace oxygen and lead to asphyxiation, and while smoke is not produced, the brightness of the arc in GTAW can cause surrounding air to break down and form ozone. Similarly, the brightness and heat can cause poi-sonous fumes to form from cleaning and degreasing materials. Cleaning opera-tions using these agents should not be performed near the site of welding, and proper ventilation is necessary to protect the welder.

Text 4. Oxy-fuel welding and cutting. Oxy-fuel welding of metal is commonly called oxyacetylene welding, since

acetylene is the predominant choice for a fuel, or often simply oxy welding, or in America gas welding. In gas welding and cutting, the heat needed to melt the metal, comes from a fuel gas burning with oxygen in a torch.

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Oxy-fuel cutting of metal is a similar process, using a different type of gas torch, called a cutting torch. Here the metal is heated until it glows orange (about 980 ºC), and then a lever on the torch is pressed to pass a stream of oxy-gen through the workpiece, to burn the steel away where the cut is desired. The iron-oxide product of this combustion process falls to the floor as a dust. Once the process is started properly, there should be no globs of melted steel under the work-piece.

Sometimes a metal-cutting blowtorch is colloquially called a gas-axe, smoke wrench, hot wrench or hot-blue spanner. Many people mistakenly call a welding torch a blowtorch.

Torches that do not use pure oxygen with the fuel inside the torch, but burn it with atmosphere air, are not oxy-fuel torches and can be identified by their single gas tank. Oxy-fuel welding needs two tanks, fuel and oxygen. Most met-als cannot be melted with such single tank torches, so they can only be used for soldering and brazing, not welding.

The apparatus used in gas welding consists basically of an oxygen source and a fuel gas source, usually cylinders, two pressure regulators and two flexible hoses – one for each cylinder, and a torch. The cylinders are usually carried in a special wheeled trolley. Vocabulary combustion – горение glob – капля, шарик blowlamp – паяльная лампа spanner – гаечный ключ wrench – гаечный ключ

Text 5. Electron beam welding. Electron beam welding (EBW) is a fusion welding process, in which a

beam of high velocity electrons is applied to the materials being joined. The workpieces melts as the kinetic energy of electrons is transformed into heat upon impact, and the filler metal, if used, also melts to form part of the weld. Pressure is not applied, and a shielding gas is not used, though the welding is often done in conditions of vacuum to prevent dispersion of the electron beam.

As the electrons strike the workpiece, their energy is converted into heat, instantly vaporizing the metal under temperatures near 25 000 ºC. The heat penetrates deeply, making it possible to weld much thicker workpieces than it is possible with most other welding processes. However, because the electron beam is tightly focused, the total heat input is actually much lower than that of any arc welding processes. As a result, the effect of welding on the surrounding material is minimal, and the heat-affected zone is small. Distortion is slight, and the work-piece cools rapidly, and while normally an advantage, this can lead to cracking in high-carbon steel. Almost all metals can be welded by the process,

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but the most commonly welded are stainless steels, super-alloys and reactive and refractory metals. The process is also widely used to perform welds of a variety of dissimilar metals combinations. However, attempting to weld plain carbon steel in a vacuum causes the metal to emit gases as it melts, so deoxidizers must be used to prevent weld porosity. The amount of heat input, and thus the pene-tration, depends on several variables, most notably the number and speed of electrons impacting the workpiece, the diameter of the electron beam, the travel speed. Greater beam current causes an increase in heat output and penetration, while higher travel speed decreases the amount of heat input and reduces pene-tration. The diameter of the beam can be varied by moving the focal point with respect to the workpiece – focusing the beam below the surface of the workpiece increases the penetration, while placing the focal point above the surface in-creases the width of the weld.

Text 6. Laser beam welding. Laser beam welding (LBW) is a welding technique used to join multiple

pieces of metal through the use of laser. The beam provides a concentrated heat source, allowing for narrow, deep welds and high welding rates. The process is frequently used in high volume applications, such as in the automotive industry.

Like electron beam welding, laser beam welding has high density (about 1 MW/cm 2) resulting in small heat affected zones and high heating and cooling rates. The spot size of the laser can vary between 0.2 mm and 13 mm, though only smaller sizes are used for welding. The depth of penetration is proportional to the amount of power supplied, but is also dependent on the location of the fo-cal point: penetration is maximized when the focal point is slightly below the surface of the workpiece.

LBW is a versatile process, capable of welding carbon steels, HSLA steels, stainless steel, aluminum, and titanium. Due to high cooling rates, cracking is a concern when welding high carbon steels. The weld quality is high, similar to that of electron beam welding. The speed of welding is proportional to the amount of the power supplied but also depends on the type and thickness of the workpieces.

A derivative of LBW, laser-hybrid welding, combines the laser of LBW with the arc welding method such as gas metal arc welding. This combination allows for greater poisoning flexibility, since GMAW supplies molten metal to fill the point, and due to the use of a laser, increases the welding speed over what is normally possible with GMAW. Wels quality tends to be higher as well, since the potential for undercutting is reduced.

The two types of lasers commonly used in metalworking are solid-state la-sers and gas lasers, especially carbon dioxide lasers. The first uses only one of several solid media, including synthetic ruby and chromium in aluminum diox-ide, neodimium in glass and the most common type, crystal composed of yt-trium, aluminum and nitrogen, and carbon dioxide as a medium. Regardless of

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the type, however, when the medium is exited, it emits photons and forms the laser beam. Vocabulary HSLA steel – high strength low alloy steel

Text 7. Resistance welding. Resistance welding refers to a group of welding processes that produce

coalescence of surfaces where heat to form the weld is generated by the resis-tance of the welding current through the workpieces. Some factors influencing heat or welding temperature are the proportions of the workpieces, the electrode material, electrode geometry, electrode pressing force, weld current and weld time etc. Small pools of molten metal are formed at the point of most electrical resistance (the connecting surfaces) as a high current (100–100 000 A) is passed through the metal. In general resistance welding methods are efficient and cause little pollution, but their applications are limited to relatively thin materials and the equipment cost can be high.

Spot welding is a popular resistance welding method used to join two to four overlapping metal sheets which are up to 3 mm thick each. In some applica-tions with only two overlapping metal sheets, the sheet thickness may be up to 6 mm. Two copper electrodes are simultaneously used to clamp the metal sheets together and to pass current through the sheets. When the current is passed through the electrodes to the sheets, heat is generated in the air gap at the contact points. At the contact points between electrodes and workpiece the heat dissi-pates throughout the copper electrodes quickly, since the copper is an excellent conductor. However at the air gap between metal sheets the heat has nowhere to go, as the metal is a comparatively poor conductor. Therefore the heat remains in the one location, which melts the metal at the spot. As the heat dissipates throughout the workpiece over a second or so, it cools the spot weld, causing the metal to solidify.

The advantages of the method include efficient energy use, limited work-piece deformation, high production rates, easy automation, and no required filler materials. When high strength in the shear is needed, spot welding is used in preference to more costly mechanical fastening, such as riveting. While the shear strength of each weld is high, the fact that the weld spots do not form a continuous seam means that the overall strength is often significantly lower than with other welding methods. This limits the usefulness of the process. It is used extensively in the automotive industry – ordinary cars can have several thousand spot welds. A specialized process, called shot welding, can be used to spot weld stainless steels.

Vocabulary shear – кромка, срез

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Text 8. Shielding gases. Shielding gases are inert or semi-inert gases that are commonly used in

several welding processes, most notably gas metal arc welding and gas tungsten arc welding. Their purpose is to protect the weld area from atmospheric gases, such as oxygen, nitrogen, carbon dioxide and water vapor. Depending on the materials being welded, these atmospheric gases can reduce the quality of the weld or make the welding process more difficult to use. Other arc welding proc-esses use other methods of protecting the weld from the atmosphere as well – shielded metal arc welding, for example, uses an electrode covered in a flux that produces carbon dioxide when consumed, a semi-inert gas that is an acceptable shielding gas for welding steel.

Shielding gases fall into two categories – inert or semi-inert. Only two of the noble gases, helium and argon, are cost-effective enough to be used in weld-ing. These inert gases are used in gas tungsten arc welding, and also in gas metal arc welding for the welding of non-ferrous materials. Semi-inert shielding gases, or active shield gases, include carbon dioxide, nitrogen and hydrogen. Most of them in large quantities, would damage the weld, but when used in small, con-trolled quantities, can improve weld characteristics.

The applications of shielding gases are limited primarily by the cost of the gas, cost of the equipment and by the location of the welding. Some shielding gases, like argon, are expensive which limits their use. The equipment used for the delivery of the gas is also an added cost, and as a result, processes like shielded metal arc welding which require less expensive equipment, might be preferred in certain situations. Finally, because atmospheric movements can cause the dispersion of the shielding gas around the weld, welding processes that require shielding gases are only done indoors, where the environment is stable and atmospheric gases can be effectively prevented from entering the weld area.

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PART II

Unit I5. WELDING DEFECTS Common welding defects include lack of fusion, lack of penetration or ex-

cess penetration, porosity, inclusions, cracking, undercut, lamellar tearing. Any of these defects are potentially disastrous as they can give rise to high stress in-tensities which may result in sudden unexpected failure below the design load.

To achieve a good quality joint it is essential that the fusion zone extends to the full thickness of the sheets being joined. Thin sheet material can be joined with a single pass and a clean square edge will be a satisfactory basis for a joint. How-ever, thicker material will normally need edges cut at a V-angle and may need several passes to fill the V with weld metal. Where both sides are accessi-ble one or more passes may be made along the reverse side to ensure the joint extends to the full thickness of the metal. Lack of fusion results from too little heat input and / or too rapid traverse of the welding torch (gas or electric). Ex-cess penetration or burning through arises from too high a heat input and / or too slow traverse of the welding torch. It is more of a problem with thin sheet as a higher level of skill is needed to balance heat input and torch traverse when welding thin metal.

Porosity occurs when gases are trapped in the solidifying weld metal. These may arise from damp consumables or metal, or from dirt, particularly oil or grease, on the metal in the vicinity of the weld. This can be avoided by ensur-ing all consumables are stored in dry conditions and the workpiece is carefully cleaned and degreased prior to welding.

Inclusions occur when several runs are made along a V-joint when joining thick plate using flux cored or flux coated rods and the slag covering a run is not totally removed after every run before the following run.

Cracking can occur due to thermal shrinkage or due to a combination of strain accompanying phase change and thermal shrinkage. In case of welded stiff frames, a combination of poor design and inappropriate procedure may re-sult in high residual stresses and cracking. Where alloy steels or steels with a carbon content greater than 0.2 % are being welded, self-cooling may be rapid enough to cause some brittle martensite to form. This will easily develop cracks. To prevent these problems a process of pre-heating may be needed, and after welding a slow controlled post-cooling in stages will be required. This can greatly increase the cost of welded joints, but for high strength steels, such as those used in petrochemical plants piping, there may well be no alternative.

Solidifying cracking is also called centerline or hot cracking. They are called hot cracks because they occur immediately after welds are completed and sometimes while the welds are being made. These defects, which are often caused by sulfur and phosphorus, are more likely to occur in higher carbon steels. Solidification cracks are normally distinguishable from other types of

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cracks by the following features: 1) they occur only in the weld metal – although the parent metal is almost always the source of the low melting point contami-nants associated with the cracking; 2) they normally appear in straight lines along the centerline of the weld bead, but may occasionally appear as transverse cracking; 3) solidification cracks in the final crater may have a branching ap-pearance; 4) as the cracks are open they are visible to the naked eye.

On breaking open the weld the crack surface may have a blue appearance, showing the cracks formed while the metal was still hot. The cracks form at the solidification boundaries. There may be evidence of segregation associated with the solidification boundary. The main cause of solidification cracking is that the weld bead in the final stage of solidification has insufficient strength to with-stand the contraction stresses as the weld pool solidifies. Factors which increase the risk include insufficient weld bead size or inappropriate form, welding under excessive restraint, material properties, such as a high impurity content or a rela-tively large shrinkage on solidification.

Joint design can have an influence on the level of residual stresses. Large gaps between components will increase the strain on the solidifying weld metal, especially if the depth of penetration is small. Hence weld beads with a small depth to width ratio, such as is formed when bridging a large wide gap with a thin bead, will be more susceptible to solidification cracking. In steels, cracking is associated with impurities, particularly sulphur and phosphorus and is pro-moted by carbon, whereas manganese can help to reduce the risk. To minimize the risk of cracking, fillers with low carbon and impurity levels and a relatively high manganese content are preferred. As general rule, for carbon manganese steels, the total sulphur and phosphorus content should be no greater than 0.06 %. However when welding a highly restrained joint using high strength steels, a combined level below 0.03 might be needed.

VOCABULARY

lack of fusion – непровар (шва) lack of penetration – недостаточная глубина провара undercut – подрез lamellar tearing – расслаивание, образование продольных трещин single pass / run – однократный / единичный проход edge cutting – срез кромки heat input – эффективная тепловая мощность, погонная энергия transverse – пересечение, (попе-речное) движение

torch weld – шов, полученный при газовой сварке rapid traverse – быстрый ход, фор-сированная продольная подача burn through – проплавление, прожог core rod – сердцевина электрода flux cored rod – электрод / стер-жень с флюсовой сердцевиной flux coating – электрод / стержень с минеральным / флюсовым по-крытием shrinkage – усадка stiff frame – жесткая рама

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residual stress – остаточное напря-жение segregation – расслоение, сегрегация hot crack – горячая трещина, горя-чий крекинг parent metal – основной металл weld bead – наплавленный валик (металла) transverse cracking – поперечное растрескивание

open weld – шов с зазором между кромками solidification cracking – образова-ние усадочных трещин to withstand – выдерживать, про-тивостоять contraction – напряжение сжатия ratio – коэффициент, соотношение impurity – примесь, постороннее включение

Упражнения. I. Найдите в тексте английские эквиваленты данных слов и сло-

восочетаний: 1) подрез; 2) расслаивание; 3) растрескивание; 4) прожог; 5) смазка; 6) расчетная нагрузка; 7) однократный проход (горелкой); 8) об-ратная сторона шва; 9) включение; 10) эффективная тепловая мощность; 11) стержень с флюсовой сердцевиной; 12) стержень с флюсовым покры-тием; 13) основной металл; 14) наплавленный валик; 15) остаточное на-пряжение; 16) термическая усадка; 17) охлаждение после сварки; 18) неф-техимический завод; 19) усадочная трещина; 20) поперечная трещина.

II. Переведите на РЯ следующие слова и словосочетания из тек-

ста: 1) fusion zone; 2) V-angle; 3) torch traverse; 4) heat input; 5) to trap gases; 6) to degrease; 7) transverse; 8) weld bead; 9) a branching appearance; 10) by the naked eye; 11) solidification boundaries; 12) segregation; 13) inappropriate shape; 14) excessive restraint; 15) shrinkage; 16) joint design; 17) ratio; 18) depth to width ratio; 19) depth of penetration; 20) metal composition.

III. Вставьте нужное слово или словосочетание. 1. These defects can give rise to … intensities. 2. Thin sheet material can be

joined by a … pass. 3. Two or more passes may be made when both sides are …. 4. Lack of fusion may result from too rapid … of the welding torch. 5. Higher skill is needed to … heat input and torch traverse. 6. To avoid porosity the work-piece should be … prior to welding. 7. Cracking occurs due to … shrinkage. 8. A combination of poor design and inappropriate procedure may result in high … stresses and cracking. 9. To prevent cracking … in stages may be needed. 10. Hot cracks are often caused by … .

IV. Переведите на АЯ следующие предложения. 1. Зона сплавления должна охватывать всю толщину свариваемых

листов. 2. Пористость возникает, когда в застывающем металле задержи-ваются газы. 3. К непровару приводит недостаток тепловой мощности и

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слишком высокая скорость движения горелки. 4. Для предотвращения рас-трескивания необходим поэтапный прогрев до начала сварки. 5. Так как пористость может быть следствием использования влажных электродов, их нужно хранить в сухом месте. 6. При быстром охлаждении деталей из ста-ли с высоким содержанием углерода могут появиться трещины. 7. Усадоч-ные трещины иногда появляются в ходе сварки. 8. Усадочные трещины от-личаются от других видов трещин. 9. Усадочные трещины видны невоо-руженным глазом. 10. Высокое содержание примесей увеличивает риск появления трещин.

Unit 16. AVOIDING WELDING DEFECTS Apart from choice of material and filler, the main techniques for avoiding

solidification cracking are: control the joints fit up to reduce the gaps; clean off all contaminants before welding; ensure that the welding sequence will not lead to a buildup of thermally

induced stresses; choose welding parameters to produce a weld bead with adequate depth

to width ratio to ensure the bead has sufficient resistance to solidification stresses. Recommended minimum depth to width ratio is 0.5:1;

avoid producing too large a depth to width ratio which will encourage segregation and expressive transverse strains. As a rule, well beads with a depth to width ratio exceeding 2:1 will be prone to solidification cracking;

avoid high welding speeds (at high current level) which increase segre-gation and stress levels across the weld bead;

at the run stop, ensure adequate filling of the crater to avoid an unfa-vourable concave shape.

Hydrogen induced cracking (HIC), also referred to as hydrogen cracking or hydrogen assisted cracking, can occur in steels during manufacture, fabrication or service. When HIC occurs as a result of welding, the cracks are in the heat af-fected zone (HAZ) or in the weld metal itself. Four factors for HIC to occur are:

hydrogen be present, this may come from moisture in any flux or from other sources. It is absorbed by the weld pool and diffuses into the HAZ;

a HAZ microstructure susceptible to hydrogen cracking; tensile stresses act on the weld; the assembly has cooled to less than 150 ºC. In case of undercutting the thickness of one or both sheets is reduced at the

toe of the weld due to incorrect settings procedure. There is already a stress con-centration at the toe of the weld and any undercut will reduce the strength of the joint.

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Lamellar tearing is mainly a problem with low quality steels. It occurs in a plate that has a low ductility in the through-thickness direction, which is caused by non-metallic inclusions, such as sulphides and oxides. These inclusions mean that the plate cannot tolerate the contraction stresses in the short transverse di-rection. Lamellar tearing can occur in both fillet and butt welds, but the most vulnerable joints are T and corner joints, where the fusion boundary is parallel to the rolling plane. These problems can be overcome by using better quality steel, “buttering” the weld area with a ductile material and possibly by redesigning the joint.

VOCABULARY

bridge a gap – ликвидировать, за-полнить разрыв, зазор filler – наполнитель, присадочный металл straight edge – прямя кромка, по-верочная линейка welding sequence – последователь-ность сварки, порядок наложения швов induced stress – индуктированное, наведенное напряжение segregation – расслоение fillet weld – угловой шов through thickness – толщина шва transverse strain – деформация в поперечном направлении

to be prone – быть склонным ductility – пластичность, вязкость butt weld – стыковой шов stress concentration – концентрация напряжения settings – установочные параметры steel plate – толстолистовая сталь rolling plane – плоскость прокатки rolling process – прокат (металла) redesign – изменить конструкцию ambient – окружающая среда weld toe – граница наружной по-верхности шва weld root – корень шва, вершина разделки кромок

Упражнения. I. Найдите в тексте английские эквиваленты: 1) загрязнение; 2) ва-

лик шва; 3) соотношение; 4) способствовать расслоению; 5) вогнутый; 6) поглощать, впитывать; 7) чувствительный; 8) конструкция; 9) подрезка; 10) растягивающее напряжение; 11) пластичность; 12) прочность соедине-ния; 13) напряжение сжатия; 14) выравнивать; 15) уязвимый.


ста: 1) welding sequence; 2) segregation; 3) to be prone; 4) transverse strain; 5) hydrogen induced cracking; 6) fabrication; 7) to diffuse; 8) tensile stress; 9) the toe of the; 10) lamellar tearing; 11) transverse direction; 12) butt weld; 13) fillet weld; 14) fusion boundary; 15) ductile material.

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III. Переведите на РЯ следующие предложения. 1. Уменьшение зазоров между деталями помогает избежать образова-

ния усадочных трещин. 2. Рекомендуемое соотношение глубины и ширины шва равно 0.5–1. 3. Слишком большое соотношение глубины и ширины шва может привести к расслоению и избыточной поперечной напряженно-сти. 4. Недостаточное заполнение кратера приведет к появлению вогнутой формы шва. 5. Некоторые материалы склонны к усадочному растрескива-нию больше, чем другие. 6. Индуцированный гидрокрекинг возникает при варке металла или производстве изделия. 7. Водород поглощается свароч-ной ванной и проникает в горячую зону. 8. Гидрокрекинг может быть вы-зван действием на шов растягивающего напряжения. 9. Подрезка умень-шает прочность соединения. 10. Расслоение обычно имеет место в низко-качественной стали.

Unit 17. DETECTION OF WELDING DEFECTS Visual inspection. Prior to any welding, the material should be visually inspected to see that

they are clean, aligned correctly; that machine setting and filler selection are checked etc.

At the first stage of inspection of all completed welds, visual inspection under good lighting should be carried out. A magnifying glass and a straight edge may be used as a part of this process. Undercutting can be detected with the naked eye and, provided there is access to the reverse side, excess penetra-tion can often be visually detected.

Liquid penetrant inspection. Serious cases of surface cracking can be detected by the naked eye but for

most cases some type of aid is needed and the use of dye penetrant methods is quite efficient when used by a trained operator. This procedure is as follows:

clean the surface of the weld and the weld vicinity; spray the surface with a liquid dye that has good penetrating properties; carefully wipe all the dye off the surface; spray the surface with a white powder; any cracks will have trapped some dye which will weep out and colour

the white coating and be clearly visible. X-ray inspection. Sub-surface cracks and inclusions can be detected by X-ray examination.

This is expensive, but for safety critical points e.g. in submarines and nuclear power plants – 100 % X-ray examination of welded joints will normally be car-ried out.

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Ultrasonic inspection. Surface and sub-surface defects can also be detected by ultrasonic inspection.

This involves directing a high frequency sound beam through the base material and weld on a predictable path. When the beam strikes a discontinuity some of it is re-flected back. This reflected beam is received, amplified and processed and from the time delay the location of the flaw is estimated. Porosity, however, in the form of numerous gas bubbles causes a lot of low amplitude reflections which are difficult to distinguish from the background noise. Results of any ultrasonic inspection re-quire skilled interpretation.

Magnetic particle inspection. This process can be used to detect surface and slightly sub-surface cracks in

ferro-magnetic materials. It can not therefore be used with austenitic stainless steels. The process involves placing a probe on each side of the area to be inspected and passing a high current between them. This produces a magnetic flux at right angles to the flow of the current. When these lines of force meet a discontinuity, such as a longitudinal crack, they are diverted and leak through the surface, creat-ing magnetic poles or points of attraction. A magnetic powder dusted onto the sur-face will cling to the leakage area more than elsewhere, indicating the location of any discontinuities. This process may be carried out wet or dry, the wet process is more sensitive as finer particles may be used which can detect very small defects. Fluorescent powders can also be used to enhance sensitivity when used in combina-tion with ultraviolet illumination.

Repair. Any detected cracks must be ground out and the area re-welded to give the re-

quired profile and then the joint must be inspected again.

VOCABULARY visual inspection – внешний осмотр with the naked eye – невооружен-ным глазом liquid penetrant inspection – капил-лярная дефектоскопия, дефекто-скопия методом проникающих жидкостей dye penetrant inspection – цветная дефектоскопия dye – краска, краситель, красящее вещество sub-surface defect – внутренний, подповерхностный дефект ultrasonic inspection – ультразвуко-вая дефектоскопия X-ray inspection – рентгеноскопия discontinuity – разрыв, нарушение однородности

amplify – усиливать, увеличивать time delay – задержка во времени amplitude – амплитуда probe – щуп, пробник magnetic particle inspection – магни-топорошковая дефектоскопия longitudinal crack – продольная трещина divert – отклонять, отводить cling – прилипать fine – тонкий, мелкий predictable path – заданная траекто-рия background noise – фоновые помехи magnifying glass – увеличительное стекло straight edge – поверочная линейка

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Упражнения. I. Найдите в тексте английские эквиваленты слов и словосочета-

ний: 1) невооруженным глазом; 2) доступ; 3) обнаруживать; 4) цветная дефектоскопия; 5) разбрызгивать; 6) краска; 7) рентгеноскопия; 8) по за-данной траектории; 9) усиливать; 10) пузырьки газа; 11) амплитуда; 12) фоновые помехи; 13) магнитный поток; 14) прямой угол; 15) магнит-ный полюс.

II. Переведите на РЯ следующие слова и выражения из текста:

1) undercutting; 2) reverse side; 3) excess penetration; 4) liquid penetrant in-spection; 5) surface cracking; 6) the weld vicinity; 7) penetrating properties; 8) sub-surface crack; 9) critical joints; 10) flaw; 11) discontinuity; 12) ferro-magnetic material; 13) magnetic flux; 14) longitudinal crack; 15) leakage area.

III. Переведите на РЯ следующие предложения. 1. На начальном этапе выявления дефектов проводится внешний ос-

мотр. 2. Некоторые дефекты можно обнаружить невооруженным глазом. 3. Для цветной дефектоскопии используется жидкий краситель с хорошей проницаемостью. 4. Рентгеноскопия – дорогой, но эффективный метод вы-явления трещин. 5. Звуковой луч высокой частоты направляют на изделие. 6. Место дефекта определяют по задержке времени отражения луча. 7. Не-опытный оператор может спутать отражение луча от незначительного де-фекта и фоновые помехи. 8. Когда силовые линии магнита достигают тре-щины, они отклоняются и уходят через поверхность. 9. Намагниченный порошок обозначает место разрыва. 10. Магнитный поток проходит под прямым углом к направлению движения тока.

Unit 18. SPOT WELDING Spot welding is a type of resistance welding used to weld various sheet

metals. Typically the sheets are in the 0.5–3.0 mm thickness range. The process uses two shaped copper alloy electrodes to concentrate welding current and force between the materials to be welded. The result is a small spot that is quickly heated to the melting point, thus forming a nugget of welded metal after the current is removed. The amount of heat released in the spot is determined by the amplitude and duration of the current. The current and duration are chosen to match the material, the sheet thickness and type of electrodes. Applying the cur-rent for too long can result in molten metal being expelled as weld splash, or can even burn a hole right through the materials being welded.

Spot welding is normally used when welding particular types of metal steel sheet. Thicker stock is difficult to heat up from a single spot, as the heat can

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flow into the surrounding metal too easily. Spot welding can be easily identified on many sheet metal goods, such as metal pails, (buckets). Aluminum alloys can be spot-welded too. However, their much higher thermal and electrical conduc-tivity mean that up to three times higher welding currents are needed. This re-quires larger, more powerful and more expensive welding transformers..

Due to changes in the resistance of the metal as it starts to liquefy, the welding process can be monitored in real time to ensure a perfect weld every time, using the most recent advances in monitoring / feedback control equip-ment. The resistance is measured indirectly, by measuring the voltage and cur-rent through the electrodes.

The voltage needed for the welding depends on the resistance of the mate-rial to be welded, the sheet thickness and desired size of the nugget. When weld-ing a common combination like 1.0 + 1.0 mm sheet steel, the voltage between the electrodes is only 1.5 V at the start of the weld but can fall as low as 1.0 V at the end of the weld this drop in voltage stems from the resistance reduction caused by the steel melting. The open circuit voltage from the transformer is much higher than this, typically in the 5–10 V range, but there is a very large voltage drop in the electrodes and secondary side of the transformer when the circuit is closed.

Perhaps the most common application of spot welding is in the automobile / car manufacturing industry, where it is used almost universally to weld the sheet metal to form a car. Spot welders can also be completely automated, and many of the industrial robots found on the assembly lines are spot welders, the other major use for robots painting. A further place where spot welding is used is in the orthodontist’s clinic, where small scale spot welding equipment is em-ployed when resizing metal “molar bands” used in dentistry.

VOCABULARY

resistance welding – электрическая контактная сварка sheet metal – (тонко)листовой металл shaped electrode – электрод особо-го профиля nugget – ядро сварной точки amplitude – амплитуда weld splash – выплеск металла stock – сырье

thermal conductivity – теплопро-водность electrical conductivity – электро-проводность transformer – трансформатор liquefy – разжижаться control equipment – контрольно-измерительное оборудование / приборы feedback – обратная связь

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словосочетаний: 1) электроды из медных сплавов; 2) температура плавле-ния; 3) длительность воздействия электротока; 4) прожечь сквозное отвер-стие в материале; 5) тепло легко проникает в окружающий металл; 6) ли-тое ядро сварной точки; 7) необходим ток почти в три раза большей мощ-ности; 8) за процессом сварки можно следить в реальном времени; 9) ток, проходящий через электроды; 10) падение напряжения происходит из-за снижения сопротивления.

II. Переведите на АЯ следующие слова и словосочетания: 1) in the

0.5–3.0 mm thickness range; 2) a nugget of welded metal; 3) the amount of heat released; 4) expelled as weld splash; 5) particular types of metal steel sheets; 6) desired size of the nugget; 7) a very large voltage drop; 8) car manufacturing industry; 9) orthodontist’s clinic; 10) small scale welding equipment.

III. Переведите на АЯ следующие предложения. 1. Тепло для контактной сварки получают при прохождении тока че-

рез контактную часть электродов. 2. Точечная сварка – это разновидность контактной сварки. 3. Контактная сварка легко поддается автоматизации и механизации. 4. Точечная сварка широко применяется в автомобилестрое-нии. 5. Прохождение тока вызывает разогрев и расплавление металла в зо-не сварки, в результате чего создается ядро сварной точки. 6. Точечная сварка представляет собой особый процесс, в котором расплавление ме-талла сочетается с использованием значительного давления. 7. Диаметр сварного ядра определяет прочность точки. 8. Диаметр ядра зависит от диаметра рабочей поверхности электрода, толщины свариваемых листов, давления, силы тока и длительности его воздействия. 9. Слишком длитель-ное воздействие тока может привести к выплеску металла. 10. Напряжение для точечной сварки зависит от сопротивления свариваемых материалов.

Unit 19. OXY-GAS TORCHES (REGULATORS) The torch is the part that the welder holds and manipulates to make the

weld. It has a connection and a valve for the fuel gas and a connection and a valve for the oxygen, a handle for the welder to grasp, a mixing chamber, set at an angle, where the fuel gas and oxygen mix, with a tip where the flame forms.

There are different types of torches. A cutting torch is used to cut metal. It is similar to a welding torch. The most common fuel used for cutting torches is acetylene. Oxygen is mixed with the acetylene in the torch which produces a

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high temperature flame. The differences between a cutting torch and a welding torch are:

1. The mixing chamber with flame nozzle is more heavily built and set at 90º. 2. There is a third tube from the torch valves to the mixing chamber. It car-

ries high-pressure oxygen, controlled by a large trigger lever on the torch. In most torches the two gases merely mix: this is an equal-pressure torch.

But in some torches, called injector torches, inside the torch head the oxygen comes out of a small nozzle under pressure so it drags the fuel gas along with it.

The regulators are attached one each to the fuel source and to the oxygen source. The oxygen regulator is attached to the oxygen tank and drops the pres-sure from about 21000 kPa (200 atmospheres) to a lower pressure for the torch. This pressure can be adjusted to suit the job at hand by turning a knob on the regulator and can be set from 0 to about 700 to 1400 kPa. Likewise the fuel regulator is attached to the fuel source and drops the pressure to a level for the torch to use. Most regulators have two gauges: one indicates the cylinder pres-sure when the valve is opened; the other indicates the pressure of the gas coming out of the regulator when the regulator is opened. This is the delivery pressure of the gas, which must be set for the current job. The gauges are calibrated to read correctly at 21 ºC.

These regulators can be single-stage and double-stage. A single-stage regu-lator mechanism consists of a nozzle that the gas passes through, a valve seat to close off the nozzle, a diaphragm and balancing springs. These mechanisms are all enclosed in a suitable housing. Fuel gas regulators and oxygen regulators are basically of the same design, but fuel gas regulators, except for hydrogen, are not made to withstand the high pressure that oxygen regulators are subjected to.

In the oxygen regulator the oxygen enters through the high pressure inlet connection and passes through a glass wool filter that removes dust and dirt. Turning the adjusting screw in (clockwise) increases the oxygen flow. The ma-jor disadvantage of single-stage regulators is that you must constantly monitor and reset the regulator if you need a fixed pressure and a flow rate.

The double-stage regulator is similar in principle, the main difference being that the total pressure drop takes place in two stages instead of one. In the high pressure stage, the cylinder pressure is reduced to an intermediate pressure that was predetermined by the manufacturer. In the low-pressure stage, the pressure is again reduced from the intermediate pressure to the working pressure you have chosen.

Regulators are precise and complicated pieces of equipment. Carelessness can do more to ruin a regulator than any other gas-using equipment. One can easily damage a regulator by simply forgetting to wipe clean the cylinder, regu-lator or hose connections. When you open a high pressure cylinder, the gas can rush into the regulator at the speed of sound. If there is any dirt in the connec-tions, it will be blasted into the precision-fitted valve seats, making them leak. This results in a condition known as creep, which occurs when the regulator is

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shut off but not the cylinder, and gas pressure is still being delivered to the low-pressure side.

Oil or other petroleum products of fat or biological origin must never be used around oxygen regulators because these products may cause a regulator explosion or a fire.

VOCABULARY regulator – редуктор, регулятор valve – вентиль fuel gas – горючий газ connection – штуцер, соединение mixing chamber – смесительная камера tip – конец cutting torch – резак acetylene – ацетилен trigger lever – пусковой рычаг equal pressure torch – безинжек-торная горелка injector torch – инжекторная го-релка gauge – манометр delivery pressure – рабочее давление

one-stage torch – однокамерный редуктор double stage regulator – двухкамер-ный редуктор nozzle – наконечник, мундштук balancing spring – балансировоч-ная / уравнительная пружина diaphragm – диафрагма housing – корпус inlet connection – входной штуцер adjusting screw – регулировочный вентиль hose connection – шланговое со-единение, ниппель leak – нарушение герметичности, утечка creep – утечка, разгерметизация

Упражнения.

I. Найдите в тексте английские эквиваленты данных слов и сло-восочетаний: 1) редуктор; 2) горючий газ; 3) резак; 4) вентиль горелки; 5) безинжекторная горелка; 6) мундштук; 7) газовый баллон; 8) манометр; 9) давление в баллоне; 10) однокамерный редуктор; 11) корпус; 12) вход-ной штуцер; 13) шланговое соединение; 14) регулировочный вентиль; 15) разгерметизация.

II. Вставьте нужное слово. 1. The main disadvantage of single-stage regulators is that you must con-

stantly … the regulator. 2. Fuel gas regulators are basically of the same … . 3. … shows the level of pressure in the gas cylinder. 4. The most common … used for cutting torches is acetylene. 5. In … the oxygen comes out of a small nozzle under pressure and drags the fuel gas along with. 6. The mixing chamber with … is set at 90º. 7. The double stage regulator is similar … to the one stage one. 8. The total pressure … takes place in two stages. 9. Dirt in the connections may be … into the valve seats and damage them. 10. Mechanisms of a regulator are enclosed in a suitable … .

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III. Переведите на АЯ следующие предложения. 1. Горючий газ и кислород смешиваются в смесительной камере.

2. Ацетилен в смеси с кислородом дает пламя высокой температуры. 3. В инжекторной горелке кислород подается под давлением и увлекает за со-бой горючий газ. 4. Смесительная камера устанавливается под углом 90º к корпусу горелки. 5. Если в смесительной камере горелки газы просто сме-шиваются, ее называют однокамерной. 6. Редукторы устанавливают на баллоны с горючим газом и кислородом. 7. Редуктор снижает давление га-за, выходящего из баллона, в соответствии с необходимостью для выпол-няемой работы. 8. Давление регулируется вручную поворотом регулирую-щего вентиля. 9. Манометр показывает давление в баллоне, когда вентиль открыт. 10. Детали редуктора помещены в соответствующий корпус.

Unit 20. GAS HOSES AND VALVES Flexible hoses that connect from the regulators to the torch and carry the fuel

gas and oxygen must be strong, non-porous, light and flexible enough to make the torch movement easy. They must be made to withstand internal pressures that can reach as high as 100 psig. The rubber used to make these hoses is specially treated to remove sulfur that could cause spontaneous combustion.

Welding hose is available in single-hose and double hose lengths. Size is de-termined by the inside diameter, and the proper size to use depends on the type of work for which it is intended. Hose used for light work has a 3/16 or 1/4 inch inside diameter and one or two plies of fabric. For heavy-duty welding and cutting opera-tions, use a hose with an inside diameter of 5/16 inch and three to five plies of fab-ric. Single hose is available in standard sizes as well as1/2-inch, 3/4 inch, and 1-inch sizes. These larger sizes are for heavy-duty heating and for use on large cut-ting machines. The most common type of cutting and welding hose is the twin or double hose which is the fuel hose and the oxygen hose joined together side by side either by a special rib or by clamps. Because they are joined, the hoses are less likely to become tangled and are easier to move from place to place.

The length of the hose is important. The delivery pressure at the torch varies with the length of the hose. A 20-foot 3/16 inch hose may be adequate for a job, but if the same hose was 50 feet long, the pressure drop would result in too little gas flow to the torch. Longer hoses must be wider inside to ensure the correct flow of gas to the torch.

The hoses for fuel gas and oxygen are typically identical in construction, but they differ in colour. The oxygen hose cover is black (in the USA it is green), and the fuel gas cover is red. This colour coding aids to prevent mishaps that could lead to dangerous accidents. The fuel gas connections have left-hand threads and the oxygen connectors have right-hand threads so that the two cannot be interchanged, to help to prevent accidents. The basic hose connection is a nut and gland. The nut has threads on the inside that match up with the inlet and outlet on the torch and

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regulator. The gland slides inside the hose and is held in place by a crumpled fer-rule. The nut is loose and can be turned by hand or a wrench to tighten the threaded nut onto the equipment.

Hoses may be made of different materials and may or may not be suitable for all fuel gases. In the USA fuel gas hoses graded R and RM are only suitable for acetylene, as other gases may break down the rubber in the hose. Grade T hoses are suitable for all fuel gases.

Between the regulator and the hose, and ideally between hose and torch on both oxygen and fuel lines, a flash-back arrestor and / or a non-return valve should be installed to prevent flame or oxygen-fuel mixture being pushed back into either cylinder and damaging the equipment or making a cylinder explode.

The flashback arrestor (not to be confused with a check valve) prevents shockwaves from downstream coming back up the hoses and entering the cylinder, as there are quantities of fuel / oxygen mixtures inside parts of the equipment that may explode if the equipment is incorrectly shut down, acetylene decomposes at excessive pressures or temperatures. The flashback arrestor will remain switched off until someone resets it, in case the pressure wave created a leak downstream of the arrestor.

A check valve lets gas flow in one direction only. Do not confuse it with a flashback arrestor, as check valves are not designed to block a shock wave. A check valve is usually a chamber containing a ball that is pressed against one end by a spring: gas flow one way pushes the ball out of the way, and no flow or flow the other way lets the spring push the ball into the inlet, blocking it. A pressure wave could occur while the ball is so far from the inlet that the pressure wave gets past before the ball reaches its off position.

VOCABULARY

heavy-duty work – работа, требую-щая больших усилий psi – pounds per square inch ply of fabric – слой оплетки rib – ребро жесткости delivery pressure – подаваемое дав-ление left / right-handed thread – левая / правая резьба nut – гайка gland – сальник inlet – вход, впуск

outlet – выход, выпуск crumped – гофрированный ferrule – ободок, манжета loose nut – незатянутая гайка wrench – гаечный ключ flashback arrester – предохранитель-ный затвор, арретир non-return valve – обратный клапан check valve – стопорный / кон-трольный клапан shock wave – ударная волна

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Unit 21. FUELS IN OXY-FUEL WELDING There is not a single gas called oxy-acetylene. The most commonly used

fuel is acetylene, other gases used are propylene, liquefied petroleum gas (LPG), propane, natural gas, hydrogen and MAPP gas. Acetylene and gases that liquefy under cylinder pressure should only be used where it can be relied on that the gas cylinder containing it will always be vertical with its valve on top.

Acetylene is the fuel first used for oxy-fuel welding and remains the fuel of choice for repair work and general cutting and welding. Acetylene gas is shipped in special cylinders designed to keep the gas dissolved. The cylinders are packed with various porous materials, e.g. asbestos, then filled about half way with acetone. The acetylene dissolves in acetone. This method is necessary because above 207 kPa acetylene is unstable and may explode. Acetylene when burned with oxygen gives a temperature of 3200 to 3500 ºC which is the highest temperature of any of the commonly used gaseous fuels. Its main disadvantage is its comparatively high cost.

Oxy-gasoline (oxy-petrol) torches have been found to perform very well, especially where bottled gas fuel is not available or difficult to transport to the worksite. Test showed that an oxy-gasoline torch cut steel plate up to 0.5 inch thick as well as oxy-acetylene. The gasoline is fed from a pressure tank whose pressure can be hand-pumped or fed from a gas cylinder.

Hydrogen has a clean flame and is good for use on aluminum. It can be used at a higher pressure that acetylene and is therefore useful for underwater welding and cutting. It is a good type of flame to use when heating much mate-rial. The flame temperature is high, about 2,000 ºC at atmospheric pressure. For some oxy-hydro-gen torches the oxygen and hydrogen are produced by elec-trolysis of water in an apparatus which is connected directly to the torch.

MAPP gas is a registered product of the Dow Chemical Company. It is liquefied petroleum gas mixed with some chemicals. It has the storage and ship-ping characteristics of LPG and has a heat value a little less than acetylene. Be-cause it can be shipped in small containers for sale at retail stores, it is used by hobbyists, and large industrial companies and shipyards because it is much less dangerous than acetylene. MAPP gas can be used at much higher pressures than acetylene and the torch can cut up to 12 inch thick steel. Other welding gases that develop comparable temperatures need special procedures for safe shipping and handling. A MAPP gas leak is easy to identify because of its particularly terrible odor.

Propane does not burn as hot as acetylene and so cannot be used for weld-ing. Propane, however, with the right torch can make a faster and cleaner cut than acetylene, and is much more useful for heating and bending than acetylene. It is also cheaper than acetylene and easier to transport.. Like propylene, most propane tips are of a two-piece design. Propane often gets unfair criticism be-cause it really needs changing your torch (from an equal pressure torch to an in-

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jector torch) and not just changing your tip to get the best performance. Most torches are equal pressure and designed for gases such as which are lighter than oxygen. Propane is a great deal heavier and runs much better through a low-pressure injector torch.

Propylene is used in production welding and cutting. It cuts faster and cleaner than propane. When propylene is used, the torch rarely needs tip cleaning.

Oxygen is not a fuel. It is chemically combined with the fuel to produce the heat for welding. This is called oxidation, but the more general and more com-monly used term is combustion. In the case of hydrogen, the product of combus-tion is simply water. For the other hydrocarbon fuels, water and carbon dioxide are produced. The heat is released because the molecules of the products of combustion have a lower energy state than the molecules of the fuel and oxygen. Oxygen is shortened to oxy-, as in the term oxy-acetylene torch.

Oxygen is usually produced elsewhere by distillation of liquefied air and shipped to the welding site in high pressure vessels, commonly called tanks or cylinders at a pressure of about 200 atmospheres.

VOCABULARY

propylene – пропилен liquefied petroleum gas (LPG) – сжиженный нефтяной газ propane – пропан MAPP gas (methylacetylene prop-adiene) – МАПП газ to liquefy – сжижать oxygasolene torch – бензорез

gasoline – бензин hobbyist – любитель, непрофес-сионал oxidation – окисление combustion – горение distillate – дистиллировать, пере-гонять

Упражнения. I. Найдите в тексте английские эквиваленты данных слов и вы-

ражений: 1) растворяться; 2) горючий газ; 3) баллон; 4) сжиженный газ; 5) бензин; 6) баллонный газ; 7) нефть; 8) горение; 9) конструкция; 10) теп-лотворная способность.

II. Вставьте нужное слово или словосочетание. 1. Common fuel gases are used for cutting and welding … state. 2. The gas

… should be kept vertical with its valve on top. 3. Acetylene is transported in special cylinders designed to keep the gas … . 4. The acetylene … into acetone. 5. At a high pressure acetylene may … . 6. Acetylene gives the highest … of any commonly used gaseous fuels. 7. The gasoline is … from a pressure tank. 8. … is good for underwater welding and cutting. 9. MAPP gas can be used at much higher … than acetylene. 10. Most propane tips are of … design.

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III. Переведите на АЯ следующие предложения. 1. Кислород химическим способом соединяют с горючим газом, чтобы

получить высокую температуру горения. 2. Кислород можно получать из сжиженного воздуха. 3. Пропан обеспечивает быструю и чистую резку при использовании инжекторной горелки. 4. При использовании пропана при-ходится менять не только наконечник, но и горелку, чтобы получить хо-рошее качество работы. 5. При использовании пропилена практически не нужно очищать наконечник горелки. 6. Процесс окисления обычно назы-вают горением. 7. Продукт окисления водорода – вода. 8. Кислородно-бензиновые горелки обеспечивают хорошее качество работы, особенно там, где нет баллонного газа. 9. Водород обеспечивает высокую темпера-туру пламени при нагревании большой массы материала. 10. При сжига-нии в кислороде ацетилен дает температуру до 3500 ºС.

IV. Найдите синонимы к следующим словам: burning, nozzle, hous-

ing, adjust, tank.

Unit 22. HAZARDS IN OXY-ACETYLELE WELDING Oxy-acetylene welding can be dangerous: severe and fatal burns, violent

building destroying explosions can result from inattention and carelessness. Be-fore using an oxyacetylene set, ensure that flammable materials such as grease, oil, paint, sawdust etc are cleared from the area and workpieces. Oil and grease can spontaneously ignite and burn violently in the presence of pure oxygen. It is important to wear clean clothing free from oil and grease. Do not roll up sleeves or trouser legs as the rolled cuffs could catch sparks. Many operators use a weld-ing cap or a baseball cap put on backwards to stop sparks from lodging in hair or going down the neck of the shirt. Wear shaded goggles with enclosed sides or a shield with a minimum № 4 shaded lens to protect your eyes from glare, flying sparks and splatter. Sunglasses are not adequate. Wear leather gloves to protect your hands from burns.

Fluxes, filler rods and base metals heated during welding and brazing re-lease toxic fumes, acetylene gas is highly explosive, so ensure adequate ventila-tion before welding. Acetylene is often described as having a sweet garlic-like smell. If you can smell it in the air and do not know where it is coming from, evacuate the area immediately. Call the fire department outside of the area as a phone call may start a fire or explosion in vapors. Fuel gases heavier than air, such as Propane, Propylene, MAPP and Butane can pool in lower areas if al-lowed to escape. In confined spaces respirator masks designed for welding can be used. Never weld on containers that have previously had toxic or inflamma-ble substances. Do not weld inside enclosed spaces or in tanks where the only

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ventilation comes from above – you might suffocate. Some fuel gases have an anaesthetic-type effect when breathed in.

Before using an oxyacetylene setup, ensure that a fire extinguisher in good working order is present. Water does not work on oil and grease, but a bucket of water can be handy for putting out small wood fires. Sand can also be used to quench fires. It is also generally handy to have at least one pair of heavy pliers around for moving hot things if necessary. Be sure your workpiece is well or-ganized before starting. Have tools laid out where they can be easily reached and make sure there is nothing that you can trip up on. A fireproof surface should be used for welding: steel table tops and firebricks are commonly used. Avoid dis-tractions such as trying to have a conversation or listen to a radio sports com-mentary as you work.

When using fuel and oxygen tanks they should be fastened securely upright to a wall or a post or a portable cart. An oxygen tank is especially dangerous for the reason that the oxygen is at a pressure of 200 atmospheres when full, and if the tank falls over and its valve strikes something and is knocked off, the tank will become an extremely deadly flying missile propelled by the compressed oxygen. For this reason never move an oxygen tank around without its valve cap screwed in place.

On your oxyacetylene torch system there will be three types of valves: the tank valve, the regulator valve and the torch valve. There will be one of them for each gas. The gas in the tanks or cylinders is at high pressure. Oxygen cylinders are generally filled to something like 2200 psi. The regulator converts the high pressure gas to a low pressure stream suitable for welding.

Never lay an acetylene tank on its side while being used. It contains ace-tone in which the acetylene is dissolved. If the tank was laid down while being transported, it must be set upright, valve on top, and given enough time ( 30 minutes) for the acetone to settle back into the sorbent. If these precautions are not followed, acetone may be drawn into the gas lines, thus creating a space in the top of the acetylene tank devoid of sorbent and the gaseous acetone in this void space may explosively decompose inside the tank causing damage to life and property.

VOCABULARY

ignite – воспламеняться regulator (valve) – редуктор газовый tank / cylinder valve – вентиль бал-лона pool – накапливаться suffocate – задушить fire-extinguisher огнетушитель garlic – чеснок

pliers – клещи, щипцы missile – ракета quench – тушить, гасить fireproof – огнеупорный firebrick – огнеупорный кирпич sorbent – сорбент, впитывающее, поглощающее вещество void space – пустое пространство

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словосочетаний: 1) смертельный ожог; 2) горючие вещества; 3) самопро-извольно возгораться; 4) линза с четырехкратной защитой; 5) покинуть зо-ну; 6) накапливаться; 7) в замкнутом пространстве; 8) газосварочное обо-рудование; 9) проверить подготовку изделия к работе; 10) привести к гибе-ли людей.

II. Переведите на АЯ следующие слова и словосочетания: 1) violent

explosion; 2) to result from carelessness; 3) to result in an explosion; 4) to catch sparks; 5) adequate ventilation; 6) to quench a fire; 7) a fire extinguisher; 8) to fasten securely upright; 9) to screw the cap in place; 10) acetone may be drawn into the gas line.

III. Вставьте нужное слово или словосочетание. 1. Violent explosion can result … inattention. 2. Grease, oil and paint are

… materials. 3. A welding cap may stop sparks from … in the hair. 4. Acetylene gas is highly … . 5. Special … … are designed for welding. 6. Be sure your workpiece is well … . 7. Fuel tanks should be fastened … upright. 8. If the valve is knocked off, the tank becomes a deadly … . 9. The gas in cylinders is … high pressure. 10. Gaseous acetone may explosively … inside the tank.

Unit 23. OXY-ACETYLENE WELDING (PREHEATING) The practice of heating the metal around the weld before applying the torch

flame is desirable one for two reasons. First, it makes the whole process more economical; second, it avoids the danger of breakage through expansion and contraction of the work as it is heated and as it cools.

When it is desired to join two surfaces by welding them, it is, of course, necessary to raise the metal from the temperature of the surrounding air to its melting point, i.e. an increase in temperature up to one thousand – three thou-sand degrees. To obtain this entire increase of temperature with the torch flame is very wasteful of fuel and of the operator’s time. The total amount of heat nec-essary to put into metal is increased by the conductivity of that metal because the heat applied at the weld is carried to other parts of the piece being handled until the whole mass is considerably raised in temperature. To secure this in-crease various methods of preheating are adopted.

As to the second reason for preliminary heating, it is understood that the metal added to the joint is molten at the time it flows into place. All the metals used in welding contract as they cool and occupy a much smaller space than when molten. If additional metal is run between two adjoining surfaces which

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are parts of a surrounding body of cool metal, this added metal will cool while the surfaces themselves are held stationary in the position they originally occu-pied. The inevitable result is that the added metal will crack under the strain, or, if the weld is exceptionally strong, the main body of the work will be broken by the force of contraction. To overcome these difficulties is the second and most important reason for preheating and also for slow cooling following the comple-tion of the weld.

There are many ways of securing this preheating. The work may be brought to a red heat in the forge if it is cast iron or steel; it may be heated in special ov-ens built for the purpose; it may be placed in a bed of charcoal while suitably supported; it may be heated by gas or gasoline preheating torches, and with very small work the outer flame of the welding torch automatically provides means to this end.

The temperature of the parts heated should be gradually raised in all cases, giving the entire mass of metal a chance to expand equally and to adjust itself to the strain imposed by the preheating. After the region around the weld has been brought to a proper temperature the opening to be filled is exposed so that the torch flame can reach it.

One of the commonest methods and one of the best for handling work of rather large size is to place the piece to be welded on a bed of fire brick and build a loose wall around it with other fire brick placed in rows, one on top of the other, with air spaces left between adjacent bricks in each row. The space be-tween the brick wall and the work is filled with charcoal, which is lighted from below. The top opening of the temporary oven is then covered with asbestos and the fire kept until the work has been uniformly raised in temperature to the de-sired point.

When much work of the same general character and size is to be handled, a permanent oven may be constructed of the fire brick, leaving a large opening through the top and also through one side. Charcoal may be used in this form of oven as with the temporary arrangement, or the heat may be secured from any form of burner or torch giving a large volume of flame. In any method employ-ing flame to do the heating, the work itself must be protected from the direct blast of the fire. Baffles of brick or metal should be placed between the mouth of the torch and the nearest surface of the work so that the flame will be deflected to either side and around the piece being heated.

The heat should be applied to bring the point of welding to the highest temperature desired. The heat should gradually shade off from this point to the other parts of the piece. In the case of cast iron and steel the temperature at the point to be welded should be great enough to produce a dull red heat. This will make the whole operation much easier, because there will be no surrounding cool metal to reduce the temperature of the molten material from the welding rod below the point at which it will join the work. From this red heat the mass of metal should grow cooler as the distance from the weld becomes greater, so that

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no great strain is placed upon any one part. With work of a very irregular shape it is always best to heat entire piece so that the strains will be so evenly distrib-uted that they can cause no distortion or breakage under any conditions.

The melting point of the work which is being preheated should be kept in mind and care exercised not to approach it too closely. Special care is necessary with aluminum in this respect, because of its low melting temperature and the sudden weakening and flowing without warning. Workmen have carelessly overheated aluminum castings and, upon uncovering the piece to make the weld, have been astonished to find that it had disappeared. Six hundred degrees is about the safe limit for this metal. It is possible to gauge the exact temperature of the work with a pyrometer, but when this instrument cannot be procured, it might be well to secure a number of temperature cones from a chemical or labo-ratory supply house. These cones are made from material that will soften at a certain heat and in form they are long and pointed. Placed in position on the part being heated, the point may be watched, and when it bends over it is sure that the metal itself has reached a temperature considerably in excess of the tempera-ture at which that particular cone was designed to soften.

VOCABULARY

preheating – прогрев, предвари-тельный нагрев breakage – зд. – деформация, разлом to raise the temperature – подни-мать температуру, нагревать wasteful – неэкономичный, расто-чительный conductivity – проводимость preliminary – предварительный contract – сжиматься adjoining – соседний, находящийся рядом adjacent – соседний, прилегающий stationary – постоянное положение under the strain – под напряжением body of the work – корпус изделия, изделие forge – горн oven – печь для обжига

a bed of charcoal – слой, подушка древесного угля loose – свободный, незакрепленный asbestos – асбест temporary arrangement – временное устройство burner – форсунка blast of fire – пламя, струя пламени deflect – отклоняться shade off – плавно, незаметно спа-дать, меняться weakening – зд. – потеря формы, деформация casting – отливка cone – конус procure – получать, доставать gauge – регулировать pyrometer – пирометр

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Упражнения. I. Найдите в тексте английские эквиваленты данных слов и сло-

восочетаний: 1) проводимость металла; 2) деформация; 3) металлы сжи-маются; 4) сохранять неизменное положение; 5) под напряжением; 6) сила сжатия; 7) чугун; 8) угольная подушка; 9) форсунка; 10) огнеупорный кир-пич; 11) печь для обжига; 12) равномерно; 13) раскалить докрасна; 14) рас-плавленный металл; 15) иметь неправильную форму.

II. Переведите на РЯ следующие слова и словосочетания из текста: 1) to put heat into metal; 2) preliminary heating; 3) the heat applied at the weld; 4) a loose wall; 5) temporary arrangement; 6) a baffle of brick; 7) to deflect; 8) the heat should gradually shade off; 9) wasteful procedure; 10) alu-minum casting; 11) to gauge the temperature; 12) to be in excess of the tempera-ture; 13) to distribute evenly; 14) to procure some material; 15) to expand.

III. Подберите синонимы к следующим словам и выражениям: ad-joining, evenly, preliminary heating, to deform, to obtain, to provide the desired increase, methods are applied.

IV. Укажите «ложных друзей» переводчика: напряжение, непра-

вильный; contract, original. V. Вставьте нужное слово. 1. Preheating avoids the danger of … through expansion. 2. The total

amount of heat necessary to put into metal is increased by the … of the metal. 3. All the metals used in welding … as they cool. 4. While cooling the added metal will … under the strain. 5. The workpiece may be preheated in special … . 6. The temperature of the parts heated should be … raised to avoid cracking. 7. The oven for preheating may be temporary or … . 8. In the process of pre-heating the workpiece must be protected from the … … of fire. 9. The heat should gradually … … from the highest temperature desired. 10. The strains should be evenly … to avoid distortion or breakage.

Unit 24. TORCH PRACTICE The weld is made by bringing the tip of the welding flame to the edges of

the metals to be joined. The torch should be held in the right hand and moved slowly along the crack with a rotating motion, traveling in small circles, so that the welding flame touches first on one side of the crack and then on the other. On large work the motion may be simply back and forth across the crack, ad-vancing regularly as the metal unites. It is usually best to weld toward the opera-tor rather than from him, although this rule is governed by circumstances. The

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head of the torch should be inclined at an angle of about 60º to the surface of the work. The torch handle should extend in the same line with the break and not across it except when welding very light plates.

If the metal is 1/16 inch or less in thickness it is only necessary to circle along the crack, the metal itself furnishing enough material to complete the weld without additions. Materials thicker than the above requires the addition of more metal of the same or different kind from the welding rod, this rod being held by the left hand. The proper size rod for cast iron is one having a diameter equal to the thickness of metal being welded up, i.e. a one-half inch rod, which is the largest used. For steel the rod should be one-half the thickness of the metal be-ing joined up, i.e. one-fourth inch rod. As a general rule, better results will be obtained by the use of smaller rods, the very small sizes being twisted together to furnish enough material while retaining the melting qualities.

The tip of the rod must at all times be held in contact with the pieces being welded and the flame must be so directed that the two sides of the crack and the end of the rod are melted at the same time. The molten metal may be directed as to where it should go by the tip of the welding flame, which has considerable force, but care must be taken not to blow melted metal on to cooler surfaces which it cannot join. If, while welding, a spot appears which does not unite with the weld, it may be handled by heating all around it to a white heat and then immediately welding the bad place. Never stop in the middle of a weld, as it is extremely difficult to continue smoothly when resuming work.

The welding flame must have exactly the right proportions of each gas. If there is too much oxygen, the metal will be burned or oxidized. The presence of too much acetylene carbonizes the metal; that is to say, it adds carbon and makes the work harder. Just the right mixture will neither burn nor carbonize and is said to be a neutral flame. The neutral flame, if of the correct size for the work, reduces the metal to a melted condition, not too fluid, and for a width about the same as the thickness of the metal being welded.

When ready to light the torch, after attaching the right tip or head as di-rected in accordance with the thickness of metal to be handled, it will be neces-sary to regulate the pressure of gases to secure the neutral flame. Next, open the valve from the generator, or on the acetylene tank, and carefully note whether there is any odor of escaping gas. Any leakage of this gas must be stopped be-fore going on with the work.

The hand wheel controlling the oxygen cylinder valve should now be turned very slowly to the left as far as it will go, which opens the valve, and, it should be borne in mind, the pressure that is being released. Turn in the hand screw on the oxygen regulator until the small pressure gauge shows a reading according to the requirements of the nozzle being used. This oxygen regulator adjustment should be made with the cock on the torch open, and after the regula-tor is thus being adjusted the torch cock may be closed. Then open the acetylene cock on the torch and screw in on the acetylene regulator hand-screw until gas

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commences to come through the torch. Light this flow of acetylene and adjust the regulator screw to the pressure desired, or, if there is no gauge, so that there is a good full flame. With the pressure of acetylene controlled by the type of generator it will only be necessary to open the torch cock.

With the acetylene burning, slowly open the oxygen cock on the torch and allow this gas to join the flame. The flame will turn intensely bright and then blue white. There will be an outer flame from four to eight inches long and from one to three inches thick. Inside of the flame will be two more rather distinctly defined flames. The inner one at the torch tip is very small, and the intermediate one is long and pointed. The oxygen should be turned on until the two flames unite into one blue-white cone from 1/4 to 1/2 inch long and 1/8 to 1/4 in diame-ter. If this single, clearly defined cone does not appear when the oxygen torch cock has been fully opened, turn off some of the acetylene until it does appear.

When welding, test the correctness of the flame adjustment occasionally by turning on more acetylene or by turning off some oxygen until two flames or cones appear. Then regulate as before to secure the single distinct cone. Too much oxygen is not usually so harmful as too much acetylene, except with alu-minum. An excessive amount of sparks coming from the weld denotes that there is too much oxygen in the flame. Should the opening in the tip become partly clogged, it will be difficult to secure a neutral flame and the tip should be cleaned with a brass or copper wire – never with iron or steel tools or wire of any kind. While the torch is doing its work, the tip may become excessively hot due to the heat radiated from the molten metal. The tip may be cooled by turning off the acetylene and dipping in water with a slight flow of oxygen through the nozzle to prevent water from finding way into the mixing chamber.

VOCABULARY edges of metals – кромки металла a rotating motion – движение по спирали head of the torch – наконечник го-релки to extend – зд. – выходить за, рас-полагаться crack – трещина, зазор unite – зд. – схватываться, начи-нать застывать torch handle – ствол горелки inch – дюйм, 2, 54 см furnish – поставлять, снабжать welding rod – присадочный пруток welding flame – пламя горелки the bad place – зд. – брак

resume – возобновить, продолжить после остановки carbonize – карбонизировать, вно-сить углерод compressed gas – сжатый газ hand screw – винт spring – пружина thread – резьба regulator – редуктор odor – запах leakage – утечка pressure gauge – манометр reading – показания (прибора) cock on the torch – кран cone – конус, язык brass – латунь

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словосочетаний: 1) регулировка пламени; 2) слишком много искр; 3) за-сориться; 4) кромки металла; 5) перемещаться по спирали; 6) металл схва-тывается; 7) наконечник горелки; 8) нагревать равномерно; 9) присадоч-ный пруток; 10) раскаленный добела; 11) расплавить металл, перевести в расплавленное состояние; 12) баллон с ацетиленом; 13) утечка; 14) мано-метр; 15) редуктор.

II. Переведите на РЯ следующие слова и словосочетания из

текста: 1) gas leakage; 2) torch handle; 3) to resume welding; 4) tip of the rod; 5) compressed gas; 6) thread; 7) odor; 8) reading on the gauge; 9) cock on the torch; 10) the tip becomes clogged.

III. Вставьте нужное слово или словосочетание. 1. The welding flame touches first … one side of the crack. 2. The torch

should be moved slowly with a … … . 3. The torch should advance regularly as the metal … 4. The torch handle should … in the line with the break. 5. Better results are generally … by the use of smaller rods. 6. The two sides of the crack and the end of the rod should be … at the same time. 7. The melting rod … metal for the weld. 8. To secure the neutral flame the pressure should not … re-quired values. 9. Pressure is shown on a device called the … 10. The regulator screw should be … to the pressure desired.

IV. Переведите в сантиметры следующие величины: 1/2 дюйма,

1/4 дюйма, 1/16 дюйма. V. Дайте синонимы к следующим словам, укажите различия в

значении: cock, begin, continue, rotate, head (of a torch). VI. Переведите на РЯ следующие предложения. 1. Горелку следует держать в правой руке. 2. Сварщик должен равно-

мерно продвигать горелку по мере того, как металл схватывается. 3. Нако-нечник горелки должен находиться под углом примерно 60º к поверхности изделия. 4. Диаметр присадочного прутка зависит от толщины свариваемо-го металла. 5. Если используются прутки малого размера, их скручивают, чтобы получить достаточное количество расплава. 6. В пламени горелки должно содержаться необходимое соотношение каждого газа. 7. Чтобы по-лучить нейтральное пламя, нужно отрегулировать давление газов. 8. Утеч-ку ацетилена необходимо устранить до возобновления работы. 9. Откройте кран подачи ацетилена на горелке. 10. Пламя горелки имеет внешний и внутренний конусы.

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Unit 25. WELDING FERROUS METALS Because of varying melting points, rates of expansion and contraction and

other peculiarities of different metals, it is necessary to give detailed considera-tion to the most important ones. A metal melting at a low temperature should have more careful treatment to avoid undesired flow than one which melts at a temperature which is relatively high. When two dissimilar metals are to be joined, the one which melts at a higher temperature must be acted upon by the flame first and when it is in a molten condition the heat contained in it will in many cases be sufficient to cause fusion of the lower melting metal and allow them to unite without playing the flame on the lower metal to any great extent.

The heat conductivity bears a very important relation to welding, inasmuch as a metal with a high rate of conductance requires more protection from cooling air currents and heat radiation than one not having this quality to such a marked extent. A metal which conducts heat rapidly will require a larger volume of flame, a larger nozzle, than otherwise, this being necessary to supply the addi-tional heat taken away from the welding point by this conductance.

The relative rates of expansion of various metals under heat should be un-derstood so that parts made of such metals may have proper preparation to com-pensate for this expansion and contraction, otherwise breakage is sure to occur.

While welding cast iron, all spoiled metal should be cut away and if the work is more than 1/8 inch in thickness the sides of the crack should be beveled to a 45º angle, leaving a number of points touching at the bottom of the bevel so that the work may be joined in its original relation.

The entire piece should be preheated in a bricked-up oven or with charcoal placed on the forge, when size does not warrant building a temporary oven. The entire piece should be slowly heated and the portion immediately surrounding the weld should be brought to a dull red. Care should be taken that the heat does not warp the metal through application to one part more than the others. After welding, the work should be slowly cooled by covering with ashes, slaked lime, asbestos fibre or some other non-conductor of heat. These precautions are abso-lutely essential in the case of cast iron.

A neutral flame, from a nozzle proportioned to the thickness of the work, should be held with the point of blue-white cone about 1/8 inch from the surface of the iron. A cast iron rod of correct diameter, usually made with an excess of silicon, is used by keeping its end in contact with molten metal and flowing it into the puddle formed at the point of fusion. The metal should be added so that the weld stands about 1/8 inch above the surrounding surface of the work.

Various forms of flux may be used and they are applied by dipping the end of the welding rod into the powder at intervals. These powders may contain bo-rax or salt, and to prevent a hard brittle weld, graphite or ferro-silicon may be added. Flux should be added. Flux should be added only after the iron is molten

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and as little as possible should be used. No flux should be used just before com-pletion of the work.

The welding flame should be played on the work around the crack and gradually brought to the work. The bottom of the bevel should be joined first and it will be noted that the cast iron tends to run towards the flame, but does not stick together easily. A hard completion of the work welded surface should be scraped with a file, while still red hot, in order to remove the surface scale.

Malleable iron should be beveled in the same way that cast iron is handled, and preheating and slow cooling are equally desirable. The flame used is the same as for cast iron and so is the flux. The welding rod may be of cast iron, al-though better results are secured with Norway iron wire or a mild steel wire wrapped with a coil of copper wire. It should be remembered that malleable iron turns to ordinary cast iron when melted and cooled. Welds in malleable iron are usually far from satisfactory and a better joint is secured by brazing the edges together with bronze. The edges to be joined are brought to a heat just a little be-low the point at which they will flow and the opening is then quickly filled from a rod of manganese bronze, a brass or bronze flux being used at this work.

Wrought iron should be beveled and heated at the same way as described for cast iron. The flame should be neutral, of the same size as for steel, and used with the tip of the blue-white cone just touching the work. The welding rod should be of mild steel or, if wrought iron is to be welded to steel, a cast iron rod may be used. A cast iron flux is well suited for this work. It should be noted that wrought iron turns to ordinary cast iron if kept heated for any length of time.

Steel should be beveled if more than 1/8 inch in thickness. It requires only a local preheating around the point to be welded. The welding flame should be absolutely neutral, without excess of either gas. If the metal is 1/16 inch or less in thickness, the tip of the blue-white cone must be held a short distance from the surface of the work; in all other cases the tip of this cone touches the metal being welded. The welding rod may be of mild, low carbon steel. Nickel steel rods may be used for parts requiring great strength, but vanadium alloys are very difficult to handle. A very satisfactory rod is made by twisting together two wires of the required material. The rod must be kept constantly in contact with the work and should not be added until the edges are thoroughly melted. The flux may or may not be used. If one is wanted, it may be made from three parts iron filings, six parts borax and one part sal ammoniac. The steel runs from the flame, but tends to hold together. Should flaming commence in the molten metal, it shows an excess of oxygen and that the metal is being burned.

High carbon steels are very difficult to handle. It is claimed that a drop or two of copper added to the weld will assist the flow, but will also harden the work. An excess of oxygen reduces the amount of carbon and softens the steel, while an excess of acetylene increases the proportion of carbon and hardens the metal.

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VOCABULARY flow – текучесть, растекание to play the flame on – водить пла-менем по … conductivity = conductance heat conductivity – теплопровод-ность inasmuch as – так как, ввиду того что… heat radiation – тепловое излуче-ние to conduct heat – проводить тепло to compensate – уравнивать, воз-мещать to allow for – принимать во внимание breakage – трещина, разлом to warrant – оправдывать, давать основание для to warp – деформировать, коро-бить slaked lime – гашеная известь non-conductor of heat – теплоизо-лирующий материал silicon – силикон to flow into – стекать

puddle – сварочная ванна to stand above – выступать за пре-делы (изделия) at intervals – периодически to dip – окунать, погружать, макать borax – бура graphite – графит ferro-silicon – ферросилиций stick together – схватываться, сли-паться scrape with a file – обработать на-пильником scale – окалина malleable iron – ковкий чугун mils steel – мягкая / малоуглероди-стая сталь coil – обмотка manganese bronze – марганцови-стая бронза wrought iron – пудлинговая сталь, сварочное железо iron filings – железные опилки sal ammoniac – аммиачная соль


словосочетаний: 1) нежелательное растекание; 2) различные металлы; 3) быть достаточным; 4) обработать металл пламенем; 5) теплопровод-ность; 6) излучение, потеря тепла; 7) коэффициент расширения; 8) под действием тепла; 9) скосить стороны трещины; 10) деформировать металл; 11) гашеная известь; 12) касаться концом прутка; 13) бура; 14) дно, нижняя часть скоса; 15) напильник.

II. Переведите на РЯ следующие слова и словосочетания: 1) non-

conductor of heat; 2) to dip the end of the rod; 3) to scrape with a file; 4) to re-move the surface scale; 5) malleable iron; 6) neutral flame; 7) the size doesn’t warrant building an oven; 8) relative rates of expansion; 9) wrought iron; 10) one- second inch; 11) sal ammoniac; 12) to play the flame on … ; 13) to such a marked extent; 14) rate of contraction; 15) to bear a relation to … .

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III. Вставьте нужно слово или словосочетание. 1. Metals differ in rates of expansion and … . 2. A metal with a low …

should have careful treatment to avoid flow. 3. A metal which … heat rapidly requires a large volume of flame. 4. Parts made from metals with widely differ-ing rates of expansion must have special treatment … this quality. 5. Sides of deep cracks should be … to 45º angle. 6. The small size of a workpiece does not … building an oven. 7. Unequal application of heat to parts of the workpiece may … the metal. 8. Slaked lime and asbestos are … of heat. 9. While welding cast iron … may contain borax or salt. 10. The welding flame should be … on the work around the crack.

IV. Подберите в тексте синонимы к следующим словам и выраже-

ниям: enough, too much, conductivity, degree, dross.

Unit 26. WELDING NON-FERROUS METALS Aluminum is the most difficult of the commonly found metals to weld. This

is caused by its high rate of expansion and contraction and its liability to melt and fall away from under the flame. The aluminum seems to melt on its inside first, and without previous warning, a portion of the work will simply vanish from in front of the operator’s eyes. The metal tends to run from the flame and separate at the same time. To keep the metal in shape and free from oxide, it is worked or puddled while in a plastic condition by an iron rod which has been flattened at one end. Several of these rods should be at hand and may be kept in a jar of salt water while not being used. These rods must not become coated with aluminum and they must not get red hot while in the weld.

The surfaces to be joined, together with the adjacent parts, should be cleaned thoroughly and then washed with a 25 % solution of nitric acid in hot water, used on a swab. The parts should then be rinsed in clean water and dried with sawdust.

Aluminum must invariably be preheated to above 600 degrees, and the whole piece being handled should be well covered with sheet asbestos to prevent excessive heat radiation.

The flame is formed with an excess of acetylene so that the second cone ex-tends about an inch, or slightly more, beyond the small blue-white point. The torch should be held so that the end of this second cone is in contact with the work, the small cone ordinarily used being kept an inch or an inch and a half from the surface of the work. Welding rods of special aluminum are used and must be handled with their end submerged in the molten metal of the weld at all times.

When aluminum is melted it forms alumina, an oxide of the metal. This alumina surrounds small masses of the metal, and as it does not melt at tempera-tures below 5000 degrees (while aluminum melts at about 1200 degrees), it pre-

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vents a weld from being made. The formation of this oxide is retarded and the oxide itself is dissolved by a suitable flux, which usually contains phosphorus to break down the alumina.

Copper. The whole piece should be preheated and kept well covered while welding. The flame must be much larger than for the same thickness of steel and neutral in character. A slight excess of acetylene would be preferable to an excess of oxygen, and in all cases the molten metal should be kept enveloped with the flame. The welding rod is of copper which contains phosphorus; and a flux, also containing phosphorus, should be spread for about an inch each side of the joint. These assist in preventing oxidation, which is sure to occur with heated cop-per.Copper breaks very easily at a heat slightly under the welding temperature.

It is necessary to preheat brass and bronze, although not to a very high tem-perature. They must be kept well covered at all times to prevent undue radiation. The flame should be produced with a nozzle one size larger that that for the same thickness of steel and the small blue-white cone should be held from 1/4 to 1/2 inch of above the surface of the work. The flame should be neutral in character.

A rod or wire of soft brass containing a large percentage of zinc is suitable for adding to brass, while copper requires the use of copper or manganese bronze rods. Special flux or borax may be used to assist the flow. The emission of white smoke indicates that the zinc contained in these alloys is being burned away and the heat should immediately be turned away or reduced. The fumes from brass and bronze are very poisonous and should not be breathed.

VOCABULARY

contraction – усадка liability – склонность, способность to puddle – перемешивать (металл в сварочной ванне) cone – конус, ядро пламени flattened – сплющенный jar – сосуд, емкость nitric acid – азотная кислота sawdust – опилки swab – помазок

sheet asbestos – листовой асбест alumina – глинозем, окись алюми-ния to dissolve – растворять brass – латунь bronze – бронза undue radiation – ненужная тепло-отдача manganese – марганцевый


словосочетаний: 1) высокий коэффициент расширения; 2) металл склонен уходить от пламени; 3) пока он сохраняет пластичность; 4) запасные прут-ки; 5) Обязательно прогреть; 6) небольшие порции металла; 7) сама окись растворяется в соответствующем флюсе; 8) охвачен пламенем; 9) ненуж-ное излучение тепла; 10) нормальное пламя.

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II. Подберите в тексте синонимы к следующим словам: normally, shrinkage, to mix, ductile, to cover, in touch with, fume.

III. Переведите на АЯ следующие предложения. 1. Цветные металлы и их сплавы при нагреве вступают во взаимодей-

ствие с окружающим воздухом гораздо сильнее, чем черные металлы. 2. Большинство цветных металлов имеют большую теплопроводность, чем сталь. 3. Чистая медь пластична и легко поддается деформации даже в хо-лодном состоянии. 4. Алюминий легко вступает в реакцию с атмосферны-ми газами. 5. Сплавы меди (бронза, латунь) резко меняют физико-механические свойства. 6. Окись алюминия, быстро появляющаяся на его поверхности, защищает металл от атмосферного воздействия, но мешает прокладке шва. 7. Свариваемости алюминия мешают пыль, жир и другие загрязнители на кромках свариваемых деталей. 8. Введение в медь приме-сей и легирующих элементов определяет физико-химические свойства сплава. 9. Сварку меди и ее сплавов выполняют в среде защитного газа, в качестве которого служат азот, аргон, гелий, а также их смеси. 10. При ду-говой сварке меди наибольший эффект достигается при использовании азота в качестве защитного газа.

Unit 27. COLD WELDING Cold welding is a process performed at room temperature that uses me-

chanical force or pressure to bring two metallic surfaces in intimate contact until inter-atom-ic forces are developed to complete the weld, while considerable plastic deformation is taking place. The need for metal distortion and flow to perform cold welding excludes that brittle materials could be joined by this process. However, many combinations of ductile dissimilar metals can be joined by cold welding, even those that could never be joined by fusion welding. There is no fusion of either metal, so that cold welding is included into the class of solid state welding processes.

To be successful cold welding must provide for the disruption of surface oxides if they are present, reducing them to separate tiny particles that do not in-terfere with the process. Shattering of the oxides during material flow is due to their brittle nature. Microscopic observations confirm that the interface becomes a phase boundary and that oxides are not interfering with the soundness of the bond.

Many varieties of the basic cold welding process are known to have been implemented. Deformation can be made in lap or butt configuration and can in-volve press forming, drawing and extrusion. Roll welding is a variant that should be dealt with separately.

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Lap cold welding could be explained as a variant of resistance spot welding where two overlapping sheets are joined at separate spots, except that no current and no heating is involved, and there is no fusion. Instead considerable deforma-tion is generated in the transversal direction to that of the applied pressure.

Cleaning should be performed just before cold welding, especially with easily oxidized materials like aluminum, because it is a critical requirement.

Various thicknesses can be joined, from 0.1 to 15 mm, provided sufficient striking force is available. Cold welding is performed by clamping the sheets to be joined between two dies and by striking a powerful blow that deforms a defi-nite region of the material. The meeting protrusions that appear in the interface result welded together by the pressure. Different shapes of dies generate a round spot or a circular ring or a linear joint, depending on requirements.

Butt cold welding is done on bars of compatible materials by upsetting jointly both of their ends. The bars are clamped in suitable fixtures to be moved axially one against the other. The lining force will cause buckling of the bar ex-tension. If an acceptable weld is not achieved with that force in a single strike, it is possible to perform the weld in steps, moving the clamp position accordingly between steps. The pressure generated in the drawn materials between the die and the mandrel (or the solid bar) produces the metallurgical weld, provided the surfaces are clean as required.

One of the quality problems affecting this and other pressure welding proc-esses is the lack of reliable non-destructive tests for evaluating production. The suggested procedure consists of performing destructive tests on suitable test pieces, and that in assuring process control by striking to the parameters devel-oped and recorded.

Cold welding can occur also as an unwanted casual accident when two sur-faces come into contact in the absence of a lubricant and stick locally together. Such an event, capable of substantial destructive damage, can be the source or the consequence of mechanical failures. Examples of failures due to destructive cold welding are found in ball or roller bearing running dry, although substantial heat can be generated by friction.

VOCABULARY

cold welding – холодная сварка interatomic forces – межатомные связи upsetting – осадка plastic deformation – пластическая деформация metal distortion – деформация ме-талла metal flow – пластичность металла ductile – ковкий, пластичный

disruption, shattering – разрушение interface – поверхность контакта свариваемых деталей phase boundary – межфазная гра-ница soundness – плотность шва, отсут-ствие дефектов lap configuration – соединение внахлест

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butt configuration – стыковое со-единение, соединение встык press forming – прессовка drawing – прокатка extrusion – экструзионная прес-совка (выдавливание) roll welding – сварка прокаткой transversal direction – перпендику-лярно / поперек welding die – контактная колодка protrusion – выступ fixture – зажимное приспособление

clamp position – место, положение зажима drawn materials – свариваемые части / материалы mandrel – оправка solid bar – неподвижный брусок non-destructive tests – неразру-шающие методы контроля test piece – образец для испытаний ball / roller bearing – шарико- / ро-ликоподшипник


словосочетаний: 1) хрупкие материалы; 2) создавать условия для разру-шения поверхностных окислов; 3) исследования под микроскопом; 4) не-смотря на отсутствие тока, нагрева и плавления; 5) перемещаться относи-тельно друг друга; 6) достаточная сила удара; 7) пошаговое выполнение шва; 8) металлургический шов; 9) испытания для оценки качества швов; 10) трущиеся несмазанные поверхности.

II. Переведите на АЯ следующие слова и словосочетания: 1) to in-

terfere with the power; 2) the interface becomes a phase boundary; 3) critical re-quirement; 4) in a single strike; 5) provided the surfaces are clean; 6) casual ac-cident; 7) substantial destructive damage; 8) mechanical failures; 9) running dry; 10) the meeting profusions.

III. Найдите в тексте синонимы следующих слов: deformation, plas-

tic, disruption, on condition; to decrease; border, connection. IV. Переведите на АЯ следующие предложения. 1. Холодная сварка или сварка давлением является разновидностью

контактной сварки. 2. При холодной сварке свариваемые поверхности под-вергаются давлению, которое позволяет получить соединение без сопутст-вующего подогрева. 3. Свариваемые поверхности тесно сближаются до возникновения межатомных связей. 4. Металлургические связи получают путем пластической деформации металла. 5. Оксидные пленки на поверх-ности разрушаются и выдавливаются из зоны контакта. 6. Качество свар-ного соединения, полученного давлением, зависит от подготовки поверх-ности, от способности металла подвергаться пластической деформации, от приложенных усилий.

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Unit 28. GENERAL REQUIREMENTS FOR STEEL FABRICATION This section specifies general requirements for steel fabrication processes,

including variables, which shall be maintained and controlled by ship builders. A material identification system which ensures correct installation and

documentation of the material grades shall be established. Shop primer applied over areas which will subsequently be welded, shall be of approved type as hav-ing no detrimental effect on the finished weld. Approved shop primers or thin coatings of linseed oil may be applied to welds subject to tightness test in agreement with the manufacturer’s recommendations. In general, the approved film thickness on welds shall not exceed 50 microns.

Welding work shall not be carried out in environmental conditions that may have a detrimental effect such as wind, damp and cold. Welding processes sensi-tive to draughts shall be adequately protected. The grooves shall be dry by the time of welding. Preheating temperature, whenever required, shall in any case be within the limit of essential variables. The welding interpass temperature shall not drop below the minimum required preheated temperature.

Cut edges are to be accurate and uniform in order to provide a shape com-patible with the weld joint design. Deviation of cut edges shall generally be within the standard specified by the Shipbuilding and Repair Standard. Attention shall be paid to avoid excessive local hardening and carbon contamination by thermal cutting. The effect of work hardening and risk of cracked edges shall be considered if shearing is used for cutting of the material. Correction by welding as compensation for improper cutting shall be in accordance with procedures for repairs.

Forming and straightening of materials shall be performed according to procedures which outline the succession of the controlled steps. The degree of cold forming for steels in structural members shall be carried out within the de-formation range recommended by the manufacturer. Should, however, such documentation not be available, the deformation rate for carbon manganese steels shall be less than 10 %, respectively 20 % for austenitic and ferritic-austenitic steels. If the deformation exceeds 10 %, respectively 20 %, either heat treatment or strain ageing test shall be carried out in accordance with an agreed procedure as stipulated in Rules for Classification of Ships. Forming of steels at high temperatures shall be effectuated with due regard to adverse effects of the material properties. Forming of steels above 650 ºC shall be subject to agree-ment with the Society.

Members to be welded shall be brought into correct alignment and held in position by clamps, tack welds, or other suitable devices, until welding has been completed or progressed to a stage where in control of the process. Such ar-rangements shall be suitably arranged to minimize distortion and build-in stresses. Fit-up shall be checked for dimensional accuracy before welding. Spe-cial attention shall be drawn to assure correct fit-up of areas, of which direct

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visual inspection is impossible. Surfaces to be welded shall be free from mill scale, slag, rust, paint or other contaminating substances. Grooves shall be within the groove profile particulars given by the welding procedure specifica-tions (WPS). Grooves shall be slag-free. All welding, including tack welding, seal welding, welding of lifting lugs and repair welding, shall be performed within the limits of essential variables of the welding procedure specifications (WPS). Preheating, when required, shall be applied in accordance with agreed procedures. Special attention shall be paid to temperature control during the welding process such that the preheat temperature is kept uniformly in affected part of the welded object. The welded sequence shall be such that the amount of shrinkage, distortions and residual stresses are minimized. Welds shall be termi-nated in a manner such that all welds are sound and without end craters. Run-off plates shall be used, where practicable, and be removed upon completion and cooling of the weld. Cut welds shall be made smooth and flush with the edges of the abutting parts.

Tack welding shall be carried out in accordance with approved WPS, speci-fying the applied minimum welding length. Tack welds used for assembly shall be removed before leaving the effected area free from defects. Tack welds, if re-tained as part of the welding process, shall be free from defects and provide adequate conditions for pass welding.

Storage and handling of welding consumables shall be in accordance with the manufacturer’s recommendations, and in accordance with procedures giving details regarding conditions and temperature in storage rooms, length of expo-sure and conditions, as applicable. Consumables which have been contaminated by moisture, rust, oil, grease, dirt or other deleterious materials, shall be dis-carded unless properly reconditioned. Recycling of fluxes for submerged weld-ing (SAW) shall be performed in a manner that ensures a mixture of new and used flux with continually homogeneous properties.

VOCABULARY

shop primer – заводская грунтовка (покрытие) для сварки welding variables – параметры сва-рочного режима detrimental effect – вредное, небла-гоприятное воздействие tightness test – тест на герметич-ность interpass temperature – температура промежуточного слоя cut edges – срезанные кромки shearing – резка (ножницами)

deformation rate – предел, граница деформации strain ageing test – тест на дефор-мационное старение to effectuate – осуществлять, вы-полнять tack weld – прихваточный шов fit-up – сборка, соединение под сварку, пригонка dimensional accuracy – точность размеров (зд. – погрешность) mill scale – прокатная окалина groove – паз, выемка

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forming – штамповка built-in stress – напряжение при монтаже to groove – разделка кромок под сварку wsp – welding procedure specifica-tions seal welding – уплотняющая сварка lifting lug – монтажная петля end crater – кратер в конце шва

run-off plate – сливная пластина, выходная планка flush – вровень, заподлицо abutting part – торцевая, примы-кающая часть pass welding – наложение поверх-ностных швов deleterious – вредный, загрязняющий to recondition – восстанавливать


словосочетаний: 1) оказывать неблагоприятное воздействие; 2) тонкий слой льняного масла; 3) основные параметры режима сварки; 4) форма, со-ответствующая конструкции сварного шва; 5) загрязнение углеродом, на-углероживание; 6) правка сваркой; 7) пределы деформации; 8) с обязатель-ным учетом неблагоприятного воздействия; 9) проверить точность сборки по размерам; 10) пазы должны соответствовать особенностям профиля; 11) продолжительность и условия использования; 12) применяются только в случае восстановления их свойств.

II. Переведите на РЯ следующие слова и словосочетания: 1) docu-

mentation of material grades; 2) minimum required preheated temperature; 3) accurate and uniform; 4) thermal cutting; 5) to outline the succession of steps; 6) to carry out strain ageing test; 7) in accordance with an agreed procedure, 8) to bring into correct alignment; 9) welding of lifting lugs; 10) to terminate a weld; 11) run-off plate; 12) conditions and temperature in storage rooms; 13) as applicable.

Unit 29. REPAIRS, INSPECTION AND TOLERANCES Defects in welds may be repaired by grinding, machining and / or welding.

In order to verify complete removal of defects, effected areas shall be examined with suitable NDT methods.

Repairs by welding shall be carried out in accordance with approved weld-ing procedure specifications (WSP). Mechanical properties shall satisfy the minimum requirements of the material in question. Defects shall be completely removed before necessary repairs are carried out. Repairs with arc-air gouging shall be followed by grinding. Repair welding in the same area may be carried out twice. Further repairs shall be subject to agreement with the Society. All

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weld repairs shall at least be re-inspected with the same NDT methods as origi-nally applied. Members distorted by welding may be straightened by mechanical means or by a limited amount of located heat. Corrective measures relating to flame straightening shall be carried out with due regard to possible degradation of the material properties.

Inspection shall be carried out in accordance with inspection and test plans to confirm that the work agrees with the established project procedures and plans such that all project requirements are complied with to the satisfaction of the Society. Due consideration shall be given to the access and the time required for adequate inspection during fabrication. High non-conformance rates in execution of the work or in the product itself shall call for special consideration in agreement with the So-ciety. Such special considerations may include, but not be limited to, increased in-spection, re-qualification of personnel or other agreed remedial actions.

Allowable acceptable alignment shall be established on the criticality of the design. Special requirements relating to special type and service are given in point 5. In general fabrication tolerances shall be in compliance with Shipbuilding and Repair Quality Standard, part A. Special building tolerances and\or weld finish as a result of operation in hard environment and / or vessels with increased target design life, shall be included in the fabrication instructions and procedures.

The Society may require weld production tests to be carried out. The extent and type of testing shall be agreed with the Society. When production weld tests are required the test assembly and test requirements shall comply with the relevant re-quirements of sec. 5. If the achieved test results do not comply with the require-ments of sec. 5, the results may be submitted for consideration. The production weld test may be accepted subject to acceptable results from additional test pre-scribed by the Society.

VOCABULARY

grinding – шлифовка machining – механическая обра-ботка NDT – non-destructive tests WSP – welding procedure specifica-tions arc-air gouging – воздушно-дуговая строжка flame straightening – правка газо-вым пламенем degradation – ухудшение, сниже-ние качества non-conformance rates – степень несоответствия

alignment – выравнивание criticality of the design – критиче-ское состояние конструкции fabrication tolerances – погрешно-сти при изготовлении weld finish – окончательная отдел-ка шва Shipbuilding and Repair Quality Standard – стандарт качества в ко-раблестроении и ремонтных работах vessels with the increased target de-sign life – суда, рассчитанные / спроектированные на длительный срок эксплуатации

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словосочетаний: 1) устранять / исправлять дефекты; 2) ремонтная сварка; 3) после воздушно-дуговой строжки производится шлифовка; 4) с помо-щью тех же методов контроля, что и первоначально; 5) с помощью локали-зованного тепла; 6) планы осмотра и испытаний; 7) к полному удовлетво-рению компании; 8) высокая степень несоответствия при выполнении ра-бот; 9) но не ограничиваться; 10) повторная аттестация персонала; 11) экс-плуатация в неблагоприятных погодных условиях; 12) рассчитанный на долгий срок службы.

II. Переведите на РЯ следующие слова и словосочетания: 1) to ver-

ify removal of defects; 2) member distorted by welding; 3) by mechanical means; 4) possible degradation of the material properties; 5) project requirements; 6) due consideration; 7) remedial action; 8) to call for special consideration; 9) criticality of the design; 10) fabrication tolerances; 11) increased inspection.

Unit 30. FUNDAMENTALS OF RESISTANCE METHOD Two distinct forms of electric apparatus are in use, one producing heat by

the resistance of the metal being treated to the passage of electric current, the other using the heat of the electric arc.

The resistance process is of the greatest use in manufacturing lines where there is a large quantity of one kind of work to do, many thousand pieces of one kind, for instance. The arc method may be applied in practically any case where any other form of weld may be made. The resistance process will be described first.

It is a well known fact that a poor conductor of electricity will offer so much resistance to the flow of electricity that it will heat. Copper is a good con-ductor, and a bar of iron, a comparatively poor conductor, when placed between heavy copper conductors of a welder, becomes heated in attempting to carry the large volume of current. The degree of heat depends on the amount of current and the resistance of the conductor. In an electric circuit the ends of two pieces of metal brought together form the point of greatest resistance in it, and the abut-ting ends instantly begin to heat. The hotter this metal becomes, the greater the resistance to the flow of current; consequently, as the edges of the abutting ends heat, the current is forced into the adjacent cooler parts, until there is a uniform heat throughout the entire mass. The heat is first developed in the interior of the metal so that it is welded there as perfectly as at the surface.

The electric welder is built to hold the parts to be joined between two heavy copper dies or contacts. A current of three to five volts, but of very great volume (amperage), is allowed to pass across these dies, and in going through

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the metal to be welded, heats the edges to a welding temperature. It may be ex-plained that the voltage of an electric current measures the pressure or force with which it is being sent through circuit and has nothing to do with the quantity or volume passing. Amperes measure the rate at which the current is passing through the circuit and consequently give a measure of the quantity which passes in any given time. Volts correspond to water pressure measured by pounds to the square inch; amperes represent the flow in gallons per minute. The low voltage used avoids all danger to the operator, this pressure not being suffi-cient to be felt even with the hand resting on the copper contacts.

Current is supplied to the welding machine at a higher voltage and lower amperage than is usually used between the dies, the low voltage and high am-perage being produced by a transformer incorporated in the machine itself. By means of windings of suitable size wire, the outside current may be received at voltages ranging from 110 to 550 and converted to the low pressure needed.

The source of current for the resistance welder must be alternating, i.e. the current must first be negative in value and then positive, passing from one ex-treme to the other at rates varying from 25 to 133 times a second. This form is known as alternating current, as opposed to direct current, in which there is no changing of positive and negative.

The current must also be what is known as single phase, i.e. a current which rises from zero in value to the highest point as a positive current and then recedes to zero before going to the lowest point of negative value. Two-phase or three-phase currents would give 2 or 3 positive impulses during this time. As long as the current is single phase alternating, the voltage and cycles (number of alternations per second) may be anything convenient. Various voltages and cy-cles are taken care of by specifying all three points when designing the trans-former which is to handle the current.

Direct current is not used because there is no way of reducing the voltage conveniently without placing resistance wires in the circuit and this uses power without producing useful work. Direct current may be changed to alternating by having a direct current motor running an alternating current dynamo, or the change may be made by a rotary converter, although this last method is not so satisfactory as the first.

The voltage used in welding being so low to start with, it is absolutely nec-essary that it be maintained at the correct point. If the source of current supply is not of ample capacity for the welder being used, it will be very hard to avoid a fall of voltage when the current is forced to pass through the high resistance of the weld. The current voltage for various work is calculated accurately, and the efficiency of the outfit depends to a great extent on the voltage being constant. In order to hold the voltage constant, the Toledo Electric Welder Company has devised connections which include a rheostat to insert a variable resistance in the field windings of the dynamo so that the voltage may be increased by cutting this resistance out at the proper time. An auxiliary switch is connected to the

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welder switch so that both switches act together. When the welder switch is closed in making a weld, that portion of the rheostat resistance between two arms determining the voltage is short-circuited. This lowers the resistance and the field magnets of the dynamo are made stronger so that additional voltage is provided to care for the resistance in the metal being welded.

In a typical machine on top of the welder there are two jaws for holding the ends of the pieces to be welded. The lower part of the jaws is rigid, while the top is brought down on top of the work, acting as a clamp. These jaws carry the copper dies through which the current enters the work being handled. After the work is clamped between the jaws, the upper set is forced closer to the lower set by a long compression layer. The current being turned on with the surfaces of the work in contact, they immediately heat to the welding point when added pressure on the lever forces them together and completes the weld.

The transformer is carried in the base of the machine and on the left-hand side is a regulator for controlling the voltage for various kinds of work. The clamps are applied by treadles convenient to the foot of the operator. A treadle instantly releases both jaws upon the completion of the weld. One or both of the copper dies may be cooled by a stream of water circulating through it from the city water mains. The regulator and switch give the operator control of the heat, anything from a dull red to the melting point being easily obtained by movement of the lever.

VOCABULARY

manufacturing line – производст-венная линия, конвейер flow of current – ток electric circuit – электрическая цепь abutting ends – торцевые, смежные концы die / contact – контакт, контактная колодка electric welder – сварочный аппа-рат, агрегат winding – виток (обмотки) single phase – однофазный direct current motor – двигатель по-стоянного тока alternating current dynamo – гене-ратор переменного тока connection – зд. – схема подключения field winding – обмотка возбуждения upset – осадка

setting – режим (сварки) cycles – зд. – частота rotary converter – одноякорный / вращающийся преобразователь ample capacity – полная емкость outfit – оборудование, установка gauge – зд. – профиль upset – осадка setting – режим rheostat – реостат to cut resistance out – отключить сопротивление auxiliary switch – вспомогательный переключатель arm – консоль сварочного аппарата to short-circuit – замкнуть нако-ротко (сompression) lever – рычаг (меха-нический) treadle – педаль

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словосочетаний: 1) контактная сварка; 2) оказывать сопротивление; 3) си-ла тока; 4) сопротивление току; 5) ток вынужден идти; 6) ток проходит по контактной колодке; 7) с которой он проходит по цепи; 8) даже если мед-ных контактов коснуться рукой; 9) витка проволоки соответствующего диаметра; 10) снизить напряжение до нужного; 11) уменьшается до нуля; 12) любые нужные; 13) при однофазном переменном токе; 14) разработать схему; 15) магниты катушки возбуждения генератора.

II. Переведите на РЯ следующие слова и словосочетания: 1) elec-

tric apparatus; 2) one kind of work to do; 3) copper conductors of the welder; 4) large volume of current; 5) in the interior of the metal; 6) in any other given time; 7) incorporated in the machine itself; 8) to handle the current; 9) to run al-ternating current dynamo; 10) to calculate accurately; 11) the efficiency of the outfit; 12) a rheostat to insert a variable resistance; 13) the lower part of the jaw is rigid; 14) the transformer is carried in the base; 15) regulator for controlling the voltage.

Unit 31. APPLICATIONS OF RESISTANCE WELDING Using resistance welding it is not necessary to give the metal to be welded

any special preparation, although when very rusty and covered with scale, the rust and scale should be removed sufficiently to allow good contact of clean metal on the copper dies. The cleaner and better the stock, the less current it takes, and there is less wear on the dies. The dies should be kept firm and tight in their holders to make a good contact. All bolts and nuts fastening the electri-cal contacts should be clean and tight at all times. The scale may be removed from forgings by immersing them in a pickling solution in a wood, stone or lead-lined tank.

The solution is made of 5 gallons of commercial sulphuric acid in 150 gal-lons of water. To get the quickest and best results from this method, the solution should be kept as near the boiling point as possible by having a coil of extra heavy lead pipe running inside the tank and carrying live steam. A very few minutes in this bath will remove the scale and the parts should then be washed in running water. After the washing they should be dipped into a bath of 50 pounds of unslaked lime in 150 gallons of water to neutralize any trace of acid.

Cast iron cannot be commercially welded, as it is high in carbon and sili-con, and passes suddenly from a crystalline to a fluid state when brought to the welding temperature. With steel and wrought iron the temperature must be kept below the melting point to avoid injury to the metal.

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High carbon steel can be welded, but must be annealed after welding to overcome the strain set up by the heat being applied at one place. Good results are hard to obtain when the carbon runs as high as 75 points, and steel of this class can only be handled by an experienced operator. If the steel is below 25 points in carbon content, good welds will always be the result. To weld high carbon to low carbon steel, the stock should be clamped in the dies with the low carbon stock sticking considerably further out from the die than the high carbon stock. Nickel steel welds readily, the nickel increasing the strength of the weld.

Iron and copper may be welded together by reducing the size of the copper end where it comes in contact with the iron. When welding copper and brass, the pressure must be less than when welding iron. The metal is allowed to actually fuse or melt at the juncture and the pressure must be sufficient to force the burnt metal out. The current is cut off the instant the metal begins to soften, this being done by means of an automatic switch which opens when the softening of the metal allows the ends come together. The pressure is applied to the weld by hav-ing the sliding jaw moved by a welder on the end of an arm.

Copper and brass require a larger volume of current at a lower voltage than for steel and iron. The die faces are set apart three times the diameter of the stock for brass and four times the diameter for copper.

Light gauges of sheet steel can be welded to heavy gauges or to solid bars of steel by spot welding. Galvanized iron can be welded, but the zinc coating will be burned off. Sheet steel can be welded to cast iron, but will pull apart, tearing out particles of the iron. Sheet copper and sheet brass may be welded, although this work requires more experience than with iron and steel. Some grades of sheet aluminum can be spot-welded if the slight roughness left on the surface under the die is not objectionable.

Butt welding is the process which joins the ends of two pieces of metal. The ends are in plain sight of the operator at all times and it can easily be seen when the metal reaches the welding heat and begins to soften It is at this point that the pressure must be applied with the lever and the ends forced together in the weld. The parts are placed in the clamping jaws with 1/8 to 1/2 inch of metal extending beyond the jaw. The ends of the metal touch each other and the cur-rent is turned on by means of a switch. To raise the ends to the proper heat re-quires from 3 seconds for 1/4 inch rods to 35 seconds for a 1/2 inch bar. This method is applicable to metals having practically the same area of metal to be brought into contact on each end. When such parts are forced together, a slight projection will be left in the form of a fin, or an enlarged portion called an upset. The degree of heat required for any work is found by moving the handle of the regulator one way or the other while testing several parts. When this setting is right, the work can continue as long as the same sizes are being handled.

Copper, brass, tool steel and all other metals that are harmed by high tem-peratures must be heated quickly and pressed together with sufficient force to get all burned metal out of the weld. In case it is desired to make a weld in the

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form of a capital letter T, it is necessary to heat the part corresponding to the top bar of the T to a bright red, then bring the lower bar to the pre-heated one and again turn on the current, when a weld can be quickly made.

Spot welding is a method of joining metal sheets together at any desired point by a welded spot about the size of a rivet. It is done on a spot welder by fusing the metal at the point desired and at the same instant applying sufficient pressure to force the particles of molten metal together. The dies are usually placed one above the other so that the work may rest on the lower one while the upper one is brought down on top of the upper sheet to be welded. One of the dies is usually pointed slightly, the opposing one being left flat. The pointed die leaves a slight indentation on one side of the metal, while the other side is left smooth. The dies may be reversed so that the outside surface of any work may be left smooth. The current is allowed to flow through the dies by a switch which is closed after pressure is applied to the work.

There is a limit to the thickness of sheet metal that can be welded by this process because of the fact that the copper rods can only carry a certain quantity of current without becoming unduly heated themselves. Another reason is that it is difficult to make heavy sections of metal touch at the welding point without excessive pressure.

Lap welding is the process used when two pieces of metal are caused to overlap and when brought to a welding heat are forced together by passing through rollers, or under a press, thus leaving the welded joint practically the same thickness as the balance of the work. Where it is desirable to make a con-tinuous seam, a special machine is required or an attachment for one of the other types. In this form of work the stock must be thoroughly cleaned and then passed between copper rollers which act in the same capacity as the copper dies.

Other applications. Hardening and tempering can be done by clamping the work in the welding dies and setting the control and time to bring the metal to the proper colour, then it is cooled in the usual manner. Brazing is done by clamping the work in the jaws and heating until the flux, then the spelter has melted and run into the joint. Riveting and heading of rivets can be done by bringing the dies down on opposite ends of the rivet after it has been inserted in the hole, and dies being shaped to form the heads properly. Hardened steel may be softened and annealed so that it can be machined by connecting the dies of the welder to each side of the point to be softened. The current is then applied until the work has reached a point at which it will soften when cooled.

VOCABULARY

wear on the dies – износ контактов pickling solution – травитель, рас-твор для травления lead-lined – освинцованный, по-крытый свинцом

commercial acid – заводская, про-мышленная кислота coil – спираль live steam – острый пар to anneal – отжигать

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junction – соединение galvanized iron – оцинкованное железо fin – зд. – ребро, выступ upset – осадка (при стыковой сварке) rivet – заклепка gauge – зд. – сорт heading – высадка головки

to machine – обрабатывать меха-ническим способом indentation – углубление. вмятина lap welding – сварка внахлест overlap – перекрывать, лежать внахлест roller – роликовый электрод, ролик tempering – закалка spelter – твердый припой (напр. медно-цинковый)


словосочетаний: 1) особая подготовка свариваемого металла может не по-требоваться; 2) тем меньше расход энергии; 3) окалина с поковок; 4) ос-винцованная емкость с травителем; 5) в промышленных масштабах; 6) вы-сокое содержание углерода и кремния; 7) металл доводят практически до плавления; 8) давление на шов скользящим зажимом; 9) будет отходить / отделяться; 10) довести до нужней температуры; 11) температурный ре-жим; 12) когда режим выбран правильно; 13) если нужно получить тавро-вое соединение; 14) колодки можно поменять метами.

II. Переведите на РЯ следующие слова и словосочетания: 1) to

carry live steam; 2) should be washed in running water; 3) to neutralize any trace of acid; 4) when welding copper and brass; 5) to force the burnt metal out; 6) to move on the end of the arm; 7) is not objectionable; 8) in plain sight of the operator; 9) having practically the same area of metal to be brought into contact; 10) to get all the burnt metal out of the weld; 11) is slightly pointed; 12) in this form of work.

Unit 32. TROUBLES AND REMEDIES Various troubles may occur in the course of resistance welding. The fol-

lowing methods are recommended. To locate grounds in the primary or high voltage side of the circuit, connect incandescent lamps in series by means of a long piece of lamp cord. For 110 volts use one lamp, for 220 volts use two lamps and for 440 volts use four lamps. Attach one end of the lamp cord to one side of the switch, and close the switch. Take the other end of the cord in the hand and press it against some part of the welder frame where the metal is clean and bright. Paint, grease and dirt act as insulators and prevent electrical contact. If the lamp lights, the circuit is in electrical contact with the frame; in other

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words, grounded. If the lamp does not light, connect the wire to a terminal block, die or slide. If the lamp then lights, the circuit, coils or leads are in elec-trical contact with the large coil in the transformer or its connections.

If, however, the lamps do not light in either case, the lamp cord should be dis-connected from the switch and connected to the other side, and the operations of connecting to welder frame, dies, terminal blocks etc., as explained above, should be repeated. If the lamps light in any of these connections, a ground is indicated. “Grounds” can usually be found by carefully tracing the primary circuit until a place is found where the insulation is defective. Re-insulate it and make the above tests again to make sure everything is clear. If the ground can not be located by ob-servation, the various parts of the primary circuit should be disconnected, and the transformer, switch, regulator etc. tested separately.

To locate a ground in the regulator or other part, disconnect the lines running to the welder from the switch. The test lamps used in the previous tests are con-nected, one end of the lamp cord to the switch, the other to a binding post of the regulator. Connect the other side of the switch to some part of the regulator hous-ing. This must be a clean connection to a bolt head, the paint should be scraped off. Close the switch. If the lamps light, the regulator winding or some part of the switch are grounded to the iron base or to the core of the regulator. If the lamps do not light, this part of the apparatus is clear. An AC voltmeter can, of course, be substituted for the lamps, or a DC voltmeter with DC current can be used in making the tests.

A short circuit in the primary is caused by the insulation of the coils becoming defective and allowing the bare copper wires to touch each other. This may result in a burn out of one or more of the transformer coils, if the trouble is in the trans-former, or in the continued blowing off the fuses in the line. Feel each coil sepa-rately. If a short circuit exists in a coil it will heat excessively. Examine all the wires; the insulation may have worn through and two of them may cross, or be in contact with the frame or other part of the welder. A short circuit in the regulator winding is indicated by failure of the apparatus to regulate properly, and some-times, though not always, by the heating of the regulator coils. The remedy for a short-circuit is to re-insulate the defective parts. It is a good plan to prevent the trouble by examining the wiring occasionally, and see that the insulation is perfect.

To locate grounds and short circuit in the secondary or low voltage side the following steps are necessary. The trouble of this kind is indicated by the machine acting sluggish or, perhaps, refusing to operate. To make a test, it will be necessary to first ascertain the existing current of your particular transformer. This is the cur-rent the transformer draws on open circuit, or when supplied with current from the line with no stock in the welder dies.

Remove the fuses from the wall switch and substitute fuses just large enough to carry the exciting current. If no suitable fuses are at hand, fine strands of copper from an ordinary lamp cord may be used. These strands are usually N 30 gauge wire and will fuse at about 10 amperes. One or more strands should be used, de-pending on the amount of exciting current, and they are connected across the fuse

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clips of fuse wire. Place a piece of wood between the welding dies in the welder as though you were going to weld them. See that the regulator is on the highest point and close the welder switch. If the secondary circuit is badly grounded, current will flow through the ground, and the small fuses or strands of wire will burn out. This is an indication that both sides of the secondary circuit are grounded or that a short circuit exists in a primary coil. In either case the welder should not be operated un-til the trouble is found and removed.

To deal with the trouble, clean the slides, dies and terminal blocks thoroughly and dry out the fibre insulation if it is damp. See that no scale or metal has worked under the sliding parts, and that the secondary leads do not touch the frame. If the ground is very heavy it may be necessary to remove the slides in order to facilitate the examination and removal of the ground. Insulation, where torn or worn through, must be carefully replaced or taped. If the transformer coils are grounded to the iron core of the transformer, it may be necessary to remove the coils and reinsulate them at the points of contact. A short-circuited coil will heat excessively and even-tually burn out. This may mean a new coil if you are unable to repair the old one. In all cases the transformer windings should be protected from mechanical injury or dampness. Unless excessively overloaded, transformers will last for years without giving a moment’s trouble, if they are not exposed to moisture or are not injured mechanically.

The most common trouble arises from poor electrical contacts, and they are the cause of endless trouble and annoyance. See that all connections are clean and bright. Take out the dies every day or two and see that there is no scale, grease or dirt between them and the holders. Clean them thoroughly before replacing. Tighten the bolts running from the transformer leads to the work jaws.

VOCABULARY

trouble – неисправность, повреж-дение grounds – заземление incandescent lamp – лампа накали-вания terminal block – клеммная доска / колодка die – контактная колодка reinsulate – провести повторную изоляцию test lamp – контрольная лампа binding post – клемма, зажим exciting current – ток возбуждения core – сердечник strand – нитка, жилка провода across – параллельно (в эл.)

fibre insulation – стекловолоконная изоляция clear – зд. – без напряжения, не под током clean connection – хорошее, на-дежное соединение primary – первичная обмотка трансформатора to cross – замкнуть short-circuit – короткое замыкание winding – обмотка exciting current – ток возбуждения strand – нитка проволоки slide – ползунок, скользящий контакт to tape – заизолировать, обернуть изолентой

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Упражнения. I. Найдите в тексте английские эквиваленты следующих слово и

словосочетаний: 1) выявить утечку тока; 2) подключить последовательно; 3) станина агрегата; 4) заземление в стабилизаторе; 5) частое / неоднократ-ное перегорание предохранителей; 6) в качестве профилактической меры; 7) о неполадке такого рода свидетельствует … ; 8) отказ (агрегата); 9) про-волока 30 калибра; 10) без перегрузки.

II. Переведите на РЯ следующие слова и словосочетания: 1) close

the switch; 2) insulator; 3) connect the wire to a terminal block; 4) carefully tracing the primary circuit; 5) this must be a clean connection; 6) a binding post of the regulator; 7) the remedy for a short circuit; 8) to draw an open circuit; 9) with no stock in the welder dies; 10) without giving a moment’s trouble.

Unit 33. ELECTRIC ARC WELDING This method bears no relation to the resistance welding, except that the

source of heat is the same in both cases. Arc welding makes use of the flame produced by the voltaic arc in practically the same way that oxy-acetylene weld-ing uses the flame from the gases.

If the ends of two pieces of carbon, through which a current of electricity is flowing while they are in contact, are separated from each other quite slowly, a brilliant arc of flame which consists mainly of carbon vapor is formed between them. The carbons are consumed by combination with the oxygen in the air and through being turned to a gas under the intense heat. The most intense action takes place at the center of the carbon which carries the positive current and this is the point of greatest heat. The temperature at this point in the arc is greater than can be produced by any other means under human control.

An arc may be formed between pieces of metal, called electrodes, in the same way as between carbon. The metallic arc is called a flaming arc and as the metal of the electrode burns with the heat, it gives the flame a color characteris-tic of the material being used. The metallic arc may be drawn out to a much greater length than one formed between carbon electrodes.

Arc welding is carried out by drawing a piece of carbon which is of nega-tive polarity away from the pieces of metal to be welded while the metal is made positive in polarity. The negative wire is fastened to the carbon electrode and the work is laid on a table made of cast or wrought iron to which the positive wire is made fast. The direction of the flame is then from the metal being welded to the carbon and the work is thus prevented from being saturated with carbon, which would prove very detrimental to its strength. A secondary advantage is found in

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the fact that the greatest heat is at the metal being welded because of its being the positive electrode.

The carbon electrode is usually made from one quarter to one and a half inches in diameter and from six to twelve inches in length. The length of the arc may be anywhere from one inch to four inches, depending on the size of the work being handled.

While the parts are carefully insulated to avoid danger of shock, it is neces-sary for the operator to wear rubber gloves as a further protection, and to wear some form of hood over the head to shield him against the extreme heat liber-ated. This hood may be made from metal, although some material that does not conduct electricity is to be preferred. The work is watched through pieces of glass formed with one sheet, which is either blue or green, placed over another which is red. Screens of glass are sometimes used without the head protector. Some protection for the eyes is absolutely necessary because of the intense white light.

It is seldom necessary to preheat the work as with the gas processes, be-cause the heat is localized at the point of welding and the action is so rapid that the expansion is not so great. The necessity of preheating, however, depends en-tirely on the material, form and size of the work being handled. The same advice applies to arc welding as to the gas flame method but in a lesser degree. Filling rods are used in the same way as with any other flame process.

In a great many places the use of the arc cuts the cost of welding to a very small fraction of what it would be by any other method, so that the importance of this method may be well understood.

Any two metals which are brought to the melting temperature and applied to each other will adhere so that they are no more apt to break at the weld than at any other point outside of the weld. It is the property of all metals to stick to-gether under these conditions. The electric arc is used in this connection merely as a heating agent. This is its only function in the process.

It has advantages in its ease of application and the cheapness with which heat can be liberated at any given point by its use. There is nothing in connec-tion with arc welding that the above principles will not answer; that is, that met-als at the melting point will weld and that the electric arc will furnish the heat to bring them to this point. As to the first question, what metals can be welded, all metals can be welded. The difficulties which are encountered are as follows: In the case of brass or zinc, the metals will be covered with a coat of zinc oxide be-fore they reach a welding heat. This zinc oxide makes it impossible for two clean surfaces to come together and some method has to be used for eliminating this possibility and allowing the two surfaces to join without the possibility of the oxide intervening. The same is true of aluminum, in which the oxide, alu-mina, will be formed, and with several other alloys comprising elements of dif-ferent melting points.

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VOCABULARY to bear no relation to … – не иметь отношения к … voltaic arc – вольтова дуга carbon vapor – пары углерода to be consumed – расходоваться with the heat – под действием тепла carbon arc – угольная дуга carbon electrode – угольный элек-трод to make fast – закрепить. подвести to saturate – насыщать detrimental – вредный, вредоносный

to adhere – слипаться, соединяться to puddle the weld – зд. – заливать шов gauge – зд. – калибр casting – отливка rolling – прокат to insulate – изолировать screen – экран head protector – защитный голов-ной уборr to conduct electricity – проводить электричество

Упражнения. I. Переведите на АЯ следующие словосочетания: 1) источник теп-

ла; 2) пары углерода; 3) превратиться в газ; 4) пламенная дуга; 5) отрица-тельная полярность; 6) насыщать углеродом; 7) изолировать; 8) выделять тепло; 9) снизить себестоимость сварки; 10) избежать опасности удара то-ком.

II. Переведите на РЯ следующие слова и словосочетания из

текста: 1) сarbon vapor; 2) metallic arc; 3) flaming arc; 4) wrought iron; 5) det-rimental to the strength; 6) head protector; 7) to adhere; 8) to bring to a tempera-ture; 9) heating agent; 10) to liberate heat.

III. Найдите в тексте синонимы к следующим словам и словосоче-

таниям: 1) to protect; 2) harmful; 3) to stick together; 4) to gasify; 5) to fill completely with; 6) to separate from conducting bodies; 7) very bright light; 8) to be concentrated at a point; 9) to stick to; 10) to get rid of, to remove.

IV. Вставьте предлоги. 1. The carbons turn to a gas … the intense heat. 2. There are few means …

human control to provide such intense heat. 3. The metal of the electrode burns … the heat. 4. During arc welding the work is laid … a table made of cast or wrought iron. 5. The operator should wear some form of good … his head. 6. The work should be watched … pieces of coloured glass … . 7. Some protec-tion … the eyes is absolutely necessary. 8. The heat is localized … the point of welding. 9. The necessity of preheating depends … some factors. 10. This is true … aluminum and some alloys.

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V. Переведите на АЯ следующие предложения. 1. Самый интенсивный процесс происходит в центре электрода.

2. Металлическая дуга может иметь большую длину между электродами, чем угольная. 3. Пламя направлено от свариваемого металла к угольному электроду. 4. В этом случае металл изделия не насыщается углеродом. 5. Это может нанести вред прочности металла. 6. Части свариваемого из-делия должны быть тщательно изолированы, чтобы избежать опасности удара электротоком. 7. Тепло оказывает действие очень быстро, поэтому не успевает распространиться на другие части изделия. 8. Металл нужно довести до температуры плавления. 9. Этот метод значительно удешевляет стоимость сварочных работ. 10. Металлы слипаются, если нагреть их до температуры плавления и сжать.

Unit 34. SOLDERING Common solder is an alloy of one-half lead with one-half tin, and is called

“half and half”. Hard solder is made with two-thirds tin and one-third lead. These alloys, when heated, are used to join surfaces of the same or dissimilar metals such as copper, brass, lead, galvanized iron, zinc, tinned plate, etc. These metals are easily joined, but the action of solder with iron, steel and aluminum is not so satisfactory and requires greater care and skill.

The solder is caused to make a perfect union with the surfaces treated with the help of heat from a soldering iron. The soldering iron is made from a piece of copper, pointed at one end and with the other end attached to an iron rod and wooden handle. A flux is used to remove impurities from the joint and allow the solder to secure a firm union with the metal surface. The iron, and in many cases the work, is heated with a gasoline blow torch, a small gas furnace, an electric heater or an acetylene and air torch.

The gasoline torch which is most commonly used should be filled two-thirds full of gasoline through the hole in the bottom, which is closed by a screw plug. After working the small hand pump for 10 to 20 strokes, hold the palm of your hand over the end of the large iron tube on top of the torch and open the gasoline needle valve about a half turn. Hold the torch so that the liquid runs down into the cup below the tube and fills it. Shut the gasoline needle valve, wipe the hands dry, and set fire to the fuel in the cup. Just as the gasoline fire goes out, open the gasoline needle valve about a half turn and hold a lighted match at the end of the iron tube to ignite the mixture of vaporized gasoline and air. Open or close the needle valve to secure a flame about 4 inches long.

There is a rest for supporting the soldering iron with the copper part in the flame on top of the iron tube from which the flame issues. Place the iron in the flame and allow it to remain until the copper becomes very hot, not quite red, but almost so.

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A new soldering iron or one that has been misused will have to be “tinned” before using. To do this, take the iron from the fire while very hot and rub the tip on some flux or dip it into soldering acid. Then rub the tip of the iron on a stick of solder or rub the solder on the iron. If the solder melts off the stick with-out coating the end of the iron, allow a few drops to fall on a piece of tin plate, then nil the end of the iron on the tin plate with considerable force. Alternately rub the iron on the solder and dip into flux until the tip has a coating of bright solder for about half an inch from the end. If the iron is in very bad shape, it may be necessary to scrape or file the end before dipping in the flux for the first time. After the end of the iron is tinned in this way, replace it on the rest of the torch so that the tinned point is not directly in the flame, turning the flame down to accomplish this.

Flux. The commonest flux, which is called “soldering acid”, is made by placing pieces of zinc in muriatic (hydrochloric) acid contained in a heavy glass or porcelain dish. There will be bubbles and considerable heat evolved and zinc should be added until this action ceases and the zinc remains in the liquid, which is now chloride of zinc. This soldering acid may be used on any metal to be sol-dered by applying with a brush or swab. For electrical work, this acid should be made neutral by the addition of one part ammonia and one part water to each three parts of the acid. This neutralized flux will not corrode metal as will the ordinary acid.

Powdered resin makes a good flux for lead, tin plate, galvanized iron and aluminum. Tallow, olive oil, beeswax and vaseline are also used for this pur-pose. Muriatic acid may be used for zinc or galvanized iron without the addition of the zinc, as described in making zinc chloride. The addition of two heaping teaspoonfuls of sal ammoniac to each pint of the chloride of zinc is sometimes found to improve its action.

Soldering Metal Parts. All surfaces to be joined should be fitted to each other as accurately as possible and then thoroughly cleaned with a file, emery cloth, or by dipping in lye. The work may be cleaned by dipping it into nitric acid which has been diluted with an equal volume of water. The work should be heated as hot as possible without danger of melting, as this causes the solder to flow better and secure a much better hold on the surfaces. Hard solder gives bet-ter results than half and half, but is more difficult to work. It is very important that the soldering iron be kept at a high heat during all work, otherwise the sol-der will only stick to the surfaces and will not join with them.

Sweating is a form of soldering in which the surfaces of the work are first covered with a thin layer of solder by rubbing them with the hot iron after it has been dipped in or touched to the soldering stick. These surfaces are then placed in contact and heated to a point at which the solder melts and unites. Sweating is much to be preferred to ordinary soldering where the form of the work permits it. This is the only method which should ever be used when a fitting is to be placed over the end of a length of tube.

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Soldering Holes. Clean the surfaces for some distance around the hole until they are bright, and apply flux while holding the hot iron near the hole. Touch the tip of the iron to some solder until the solder is picked up on the iron, and then place this solder, which was just picked up, around the edge of the hole. It will leave the soldering iron and stick to the metal. Keep adding solder in this way until the hole has been closed up by working from the edges and building toward the center. After the hole is closed, apply more flux to the job and smooth over with the hot iron until there are no rough spots. Should the solder refuse to flow smoothly, the iron is not hot enough.

Soldering Seams. Clean back from the seam or split for at least half an inch all around and then build up the solder in the same way as was done with the hole. After closing the opening, apply more flux to the work and run the hot iron lengthwise to smooth the job.

Soldering Wires. Clean all insulation from the ends to be soldered and scrape the ends bright. Lay the ends parallel to each other and, starting at the middle of the cleaned portion, wrap the ends around each other, one being wrapped to the right, the other to the left. Hold the hot iron under the twisted joint and apply flux to the wire. Then dip the iron in the solder and apply to the twisted portion until the spaces between the wires are filled with solder. Finish by smoothing the joint and cleaning away all excess metal by rubbing the hot iron lengthwise. The joint should now be covered with a layer of rubber tape and this covered with a layer of ordinary friction tape.

Steel and Iron. Steel surfaces should be cleaned, then covered with clear muriatic acid. While the acid is on the metal, rub with a stick of zinc and then tin the surfaces with the hot iron as directed. Cast iron should be cleaned and dipped in strong lye to remove grease. Wash the lye away with clean water and cover with muriatic acid as with steel. Then rub with a piece of zinc and tin the surfaces by using resin as a flux.

It is very difficult to solder aluminum with ordinary solder. A special alu-minum solder should be secured, which is easily applied and makes a strong joint. Zinc or phosphor tin may be used in place of ordinary solder to tin the sur-faces or to fill small holes or cracks. The aluminum must be thoroughly heated before attempting to solder and the flux may be either resin or soldering acid. The aluminum must be thoroughly cleaned with dilute nitric acid and kept hot while the solder is applied by forcible rubbing with the hot iron.

VOCABULARY

solder – мягкий припой half and half – «половинник» tin – олово lead – свинец galvanized iron – оцинкованная сталь / железо

tinned plate – белая жесть soldering iron – паяльник tip – жало (паяльника) to secure a firm union – обеспечить прочное соединение

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gasoline blow torch – бензиновая паяльная лампа screw plug – завинчивающаяся пробка hand pump – ручной насос to work a pump – покачать насос to ignite – зажечь needle valve – игольчатый клапан cup – колпачок a rest – опора, упор soldering acid – паяльная кислота, водный раствор хлористого цинка stick of solder – брусок припоя muriatic acid – соляная кислота chloride of zinс – хлорид цинка swab – помазок ammonia – нашатырь, аммиак to corrode – вызывать коррозию, подвергаться коррозии

resin – канифоль tallow – сало, свечной жир sal ammoniac – нашатырь emery cloth – шкурка, наждачная бумага lye – щелок to secure a hold on – обеспечить схватывание sweating – оплавка fitting – устройство, приспособление rough spots – шершавость, шерша-вые места lengthwise – на всю длину to scrape the ends – зачистить концы excess metal – избыток металла rubber tape – резиновая лента adhesive / friction tape – липкая изолента


словосочетаний: 1) белая жесть; 2) латунь; 3) паяльник; 4) удалить приме-си; 5) бензин; 6) поджечь смесь; 7) нашатырный спирт; 8) обмакнуть в флюс; 9) обработать напильником; 10) соляная кислота; 11) канифоль; 12) щелок; 13) убавить пламя; 14) изоляция; 15) помазок.

II. Переведите на АЯ следующие слова и словосочетания: 1) оцин-

кованное железо; 2) прочное соединение; 3) паяльная лампа; 4) лудить; 5) нашатырный спирт; 6) полная чайная ложка; 7) шкурка; 8) хорошо схва-титься на поверхности; 9) оплавка; 10) изолента; 11) азотная кислота; 12) чугун; 13) твердый припой; 14) с силой проводить, тереть; 15) порош-ковая канифоль.

III. Вставьте предлоги, где необходимо. 1. The action of the solder … iron, steel and aluminum requires greater

skill. 2. Open the gasoline needle valve … a half turn. 3. The solder picks up … the heated tip of the iron. 4. While soldering a hole, work … the edges … the centre. 5. This soldering acid may be used … any metal to be soldered. 6. This flux will not corrode … the metal. 7. The surfaces to be soldered are heated … a point at which the solder melts and unites. 8. Sweating is preferred … ordinary

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soldering. 9. After closing the opening, apply more flux … the work. 10. Wash the lye … with clean water.

IV. Переведите на АЯ следующие предложения. 1. Опора для паяльника находится сверху трубки паяльной лампы, из

которой выходит пламя. 2. Припой образует надежное соединение с обра-батываемой поверхностью. 3. Флюс используется для удаления примесей из шва. 4. Для нагрева места пайки используют бензиновую паяльную лам-пу. 5. Прежде чем разжигать паяльную лампу, нужно немного покачать ручной насос лампы, чтобы бензин стек в чашечку под трубкой. 6. Новый или давно не использованный паяльник нужно сначала залудить. 7. Если паяльник в плохом состоянии, нужно поскрести или обработать напильни-ком его жало, прежде чем макать во флюс первый раз. 8. Паяльную кисло-ту наносят на металл кисточкой или помазком. 9. Паяльную кислоту полу-чают, растворяя цинк в соляной кислоте, налитой в сосуд из прочного стекла или фарфора. 10. Твердый припой обеспечивает более прочное со-единение, чем половинник, но с ним трудно работать.

Unit 35. BRAZING Brazing is a process for joining metal parts, very similar to soldering, ex-

cept that brass is used to make the joint instead of lead and zinc alloys which form solder. Brazing must not be attempted on metals whose melting point is less than that of sheet brass.

Two pieces of brass to be brazed together are heated to a temperature at which the brass used in the process will melt and flow between the surfaces. The brass amalgamates with the surfaces and makes a very strong and perfect joint, which is far more superior to any form of soldering where the work allows this process to be used, and in many cases is the equal of welding for the particular field in which it applies.

Brazing Heat and Tools. The metal commonly used for brazing will melt at the heat between 1350 and 1650 ºF. To bring the parts to this temperature, vari-ous methods are employed, using solid, liquid or gaseous fuels. While brazing may be accomplished with the fire of the blacksmith forge, this method is sel-dom satisfactory because of the difficulty of making a sufficiently clean fire with smithing coal, and it should not be used when anything else is available. Large jobs of brazing may be handled with a charcoal fire built in the forge, as this fuel produces a very satisfactory and clean fire. The only objection is in the difficulty of confining the heat to the desired parts of the work.

The most satisfactory fire is that from a fuel gas torch built for this work. These torches are simply forms of Bunsen burners, mixing the proper quantity of air with the gas to bring about a perfect combustion. Hose lines lead to the

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mixing tube of the gas torch, one line carrying the gas and the other air under a moderate pressure. The air line is often dispensed with, allowing the gas to draw air into the burner on the injector principle. Valves are provided with which the operator may regulate the amount of both gas and air, and ordinarily the quality and intensity of the flame.

When gas is not available, recourse may be had to the gasoline torch made for brazing. This torch is built in the same way as the small portable gasoline torches for soldering operations, with the exception that two regulating needle valves are incorporated in place of only one. The torches are carried on a frame-work, which also supports the work being handled. Fuel is forced to the torch from a large tank of gasoline into which air pressure is pumped by hand. The torches are regulated to give the desired flame by means of the needle valves in much the same way as with any other form of pressure torch using liquid fuel.

Another very satisfactory form of torch for brazing is the acetylene-air combination. This torch gives the correct degree of heat and may be regulated to give a clean and easily controlled flame.

Regardless of the source of heat, the fire or flame must be adjusted so that no soot is deposited on the metal surfaces of the work. This can only be accom-plished by supplying the exact amounts of gas and air that will produce a com-plete burning of the fuel. With the brazing torches in common use two heads are furnished, being supplied from the same source of fuel, but with separate regu-lating devices. The torches are adjustably mounted in such a way that the flames may be directed toward each other, heating two sides of the work at the same time and allowing the pieces to be completely surrounded with the flame.

The tool required for ordinary brazing operations is a spatula formed by flattening one end of a quarter-inch steel rod. The spatula is used for placing the brazing metal on the work and for handling the flux that is required in this work as in all other similar operations

Spelter is a metal that is melted into the joint. While this name was origi-nally applied to but one particular grade or composition of metal, common use has extended the meaning until it is generally applied to all grades. Spelter is variously composed of alloys containing copper, zinc, tin and antimony, the mixture employed depending on the work to be done. The different grades are of varying hardness, the harder kinds melting at higher temperatures than the soft ones and producing a stronger joint when used. The reason for not using hard spelter in all cases is the increased difficulty of working it and the fact that its melting point is so near to some of the metals brazed that there is great danger of melting the work as well as the spelter.

The hardest grade of spelter is made from three-fourths copper with one-fourth zinc and is used for working on malleable and cast iron and for steel. This hard spelter melts at about 1650º and is correspondingly difficult to handle. A spelter suitable for working with copper is made from equal parts of copper and zinc, melting at about 1400 ºF, 500º below the melting point of the copper itself.

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A still softer brazing metal is composed of half copper, three-eighths zinc and one-eighth tin. This grade is used for fastening brass to iron and copper and for working with large pieces of brass to brass. For brazing thin sheet brass and light brass castings a metal is used which contains two-thirds tin and one-third antimony. The low melting point of this composition makes it very easy to work with and the danger of melting the work is very slight. However, as might be expected, a comparatively weak joint is secured, which will not stand any great strain.

All of the above brazing metals are used in the powder form so that they may be applied with the spatula where the joint is exposed on the outside of the work. In case it is necessary to braze on the inside of a tube or any deep recess, the spelter may be placed on a flat rod long enough to reach to the farthest point. By distributing the spelter at the proper points along the rod it may be placed at the right points by turning the rod over after inserting it into the recess.

Flux. In order to remove the oxides produced under brazing heat and to al-low the brazing metal to flow freely into place, a flux of some kind must be used. The commonest flux is simply a pure calcined borax powder, that is, a bo-rax powder that has been heated until practically all the water has been driven off. Calcined borax may also be mixed with about 15 per cent of sal ammoniac to make a satisfactory fluxing powder. It is absolutely necessary to use flux of some kind and a part of whatever is used should be made into a paste with water so that it can be applied to the joint to be brazed before heating. The remainder of the powder should be kept dry for use during the operation and after the heat has been applied.

Preparing the Work. The surfaces to be brazed are first thoroughly cleaned with files, emery cloth or sand paper. If the work is greasy, it should be dipped into a bath of lye or hot soda water so that all trace of oil is removed. The parts are then placed in the relation to each other that they are to occupy when the work has been completed. The edges to be joined should make a secure and tight fit, and should match each other at all points so that the smallest possible space is left between them. This fit should not be so tight that it is necessary to force the work into place, neither should it be loose enough to allow any considerable space between the surfaces.

The work is placed on the surface of the brazing table in such a position that the flame from the torches will strike the parts to be heated, and with the joint in such a position that the melted spelter will flow down through it and fill every possible part of the space between the surfaces under the action of gravity. That means that the edge of the joint must be uppermost and the crack to be filled must not lie horizontal, but at the greatest slant possible. Better than any degree of slant would be to have the line of the joint vertical.

The work is braced up or clamped in the proper position before commenc-ing to braze, and it is best to place fire brick in such positions that it will be im-possible for cooling draughts of air to reach the heated metal, should the flame

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be removed temporarily during the process. In case there is a large body of iron, steel or copper to be handled, it is often advisable to place charcoal around the work, igniting this with the flame of the torch before starting to braze so that the metal will be maintained at the correct heat without depending entirely on the torch.

When handling brass pieces having thin sections there is danger of melting the brass and causing it to flow away from under the flame, with the result that the work is ruined. If, in the judgment of the workman, this may happen with the particular job in hand, it is well to build up a mould of fire clay back of the thin parts or preferably back of the whole piece, so that the metal will have the nec-essary support. This mould may be made by mixing the fire clay into a stiff paste with water and then packing it against the piece to be supported tightly enough so that the form will be retained even if the metal softens.

Brazing. When the work is in place, it should be well covered with the paste of flux and water, then heated until this flux boils up and runs over the sur-faces. Spelter is then placed in such a position that it will run into the joint and the heat is continued or increased until the spelter melts and flows in between the two surfaces. The flame should surround the work during the heating so that outside air is excluded as far as it is possible to prevent excessive oxidization.

When handling brass or copper, the flame should not be directed so that its center strikes the metal squarely, but so that it glances from one side or the other. Directing the flame straight against the work is often the cause of melting the pieces before the operation is completed. When brazing two different metals, the flame should play only on the one that melts at the higher temperature, the lower melting part receiving its heat from the other. This avoids the danger of melting one before the other reaches the brazing point.

The heat should be continued only long enough to cause the spelter to flow into place and no longer. Prolonged heating of any metal can do nothing but oxidize and weaken it, and this practice should be avoided as much as possible. If the spelter melts into small globules in place of flowing, it may be caused to spread and run into the joint by lightly tapping the work. More dry flux may be added with the spatula if the tapping does not produce the desired result.

Excessive use of flux, especially toward the end of the work, will result in a very hard surface, which will be extremely difficult to finish properly. This trou-ble will be present to a certain extent anyway, but it may be lessened by a vigor-ous scraping with a wire brush just as soon as the work is removed from the fire. If allowed to cool before cleaning, the final appearance will not be as good as with the surplus metal and scale removed immediately upon completing the job. After the work has been cleaned with the brush it may be allowed to cool and finished to the desired shape, size and surface by filing and polishing.

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VOCABULARY sheet brass – листовая латунь brazing – пайка твердым припоем brazing torch – паяльная лампа to amalgamate – сливаться, соеди-няться smithing coal – кузнечный уголь charcoal – древесный уголь to confine – ограничить bunsen burner – бунзеновская го-релка to be dispensed with – обойтись без to have recourse – найти выход, за-менить, обойтись

pressure torch – безынжекторная горелка soot – сажа spatula – лопаточка spelter – припой antimony – сурьма recess – углубление, выемка calcined borax – прокаленная бура uppermost – самое верхнее поло-жение slant – наклон mould – форма (литейная) fire clay – огнеупорная глина globule – шарик


I. Найдите в тексте английские эквиваленты следующих слов и словосочетаний: 1) быть равным чему-либо; 2) довести до температуры; 3) чистое пламя; 4) обойтись без чего-либо; 5) поднять давление ручным насосом; 6) регулируемое пламя; 7) сажа; 8) сурьма; 9) различная степень твердости; 10) состоять из; 11) легкие латунные отливки; 12) в виде по-рошка; 13) распределять, размещать; 14) под действием тепла от пайки; 15) подгонка.

II. Переведите на АЯ следующие слова и словосочетания: 1) zinc alloy; 2) to amalgamate; 3) fuel gas torch; 4) framework; 5) needle valve; 6) a tank of gasoline; 7) to accomplish; 8) to furnish two heads; 9) spatula; 10) spel-ter; 11) to be exposed to … ; 12) recess; 13) calcined borax; 14) emery cloth; 15) to make a secure and tight fit.

III. Переведите на АЯ следующие предложения. 1. Латунь соединяется с поверхностью пайки и образует надежное и

прочное соединение. 2. Пайка твердым припоем гораздо эффективнее лю-бых видов пайки мягким припоем. 3. Единственный недостаток этого ме-тода в том, что трудно ограничить распространение тепла только на нуж-ные части изделия. 4. В газовой горелке нужный объем воздуха смешива-ется с газом, чтобы обеспечить почти полное его сгорание. 5. Изделие нужно покрыть пастой из флюса и воды, затем нагревать, пока флюс не за-кипит и не растечется по поверхности. 6. Часто обходятся без воздушного шланга, поток газа сам втягивает воздух в горелку по инжекторному прин-ципу. 7. Когда нет газа, можно обойтись паяльной лампой. 8. Независимо от источника тепла, огонь или пламя нужно отрегулировать так, чтобы на поверхности изделия не образовывалась сажа. 9. Лопаточку для нанесения

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припоя и флюса делают из стального прута диаметром 1/4 дюйма, рас-плющив его конец. 10. Первоначально слово “spelter” обозначало только один особый сорт или состав припоя, но в обычном употреблении его зна-чение расширилось.

Unit 36. THERMIT WELDING The process of welding which makes use of great heat produced by oxygen

combining with aluminum is known as the Thermit process and was perfected by Dr. Hans Goldschmidt. The process makes use of a mixture of finely pow-dered aluminum with an oxide of iron called by the trade name, Thermit. The reaction is started with a special ignition powder, such as barium superoxide and aluminum, and the oxygen from the iron oxide combining with the aluminum, producing a mass of superheated steel at about 5000 degrees Fahrenheit. After the reaction, which takes from 30 seconds to a minute, the molten metal is drawn from the crucible on to the surfaces to be joined. Its extreme heat fuses the metal and a perfect joint is the result. This process is suited for welding iron or steel parts of comparatively large size.

Preparation. The parts to be joined are thoroughly cleaned on the surfaces and for several inches back from the joint, after which they are supported in place. The surfaces between which the metal will flow are separated from 1/4 to 1 inch, depending on the size of the parts, but cutting or drilling a part of the metal away. After this separation is made for allowing the entrance of new metal, the effects of contraction of the molten steel are cared for by preheating adjacent parts or by forcing the ends apart with wedges and jacks. The amount of this last separation must be determined by the shape and proportions of the parts in the same way as it would be done for any other class of welding which heats the parts to a melting point.

Yellow wax, which has been warmed until plastic, is then placed around the joint to form a collar, the wax completely filling the space between the ends and being provided with vent holes by imbedding a piece of stout cord, which is pulled out after the wax cools. A retaining mould made from sheet steel or fire brick is then placed around the parts. This mould is then filled with a mixture of one part fire clay, one part ground fire brick and one part fire sand. These materi-als are well mixed and moistened with enough water so that they will pack. This mixture is then placed in the mould, filling the space between the walls and the wax, and is packed hard with a rammer so that the material forms a wall several inches thick between any point of the mould and the wax. The mixture must be placed in the mould in small quantities and packed tight as the filling progresses.

Three or more openings are provided through this moulding material by the insertion of wood or pipe forms. One of these openings will lead from the lowest point of the wax pattern and is used for the introduction of the preheating flame.

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Another opening leads from the top of the mould into this preheating gate, open-ing into the preheating gate at a point about one inch from the wax pattern. Openings, called risers, are then provided from each of the high points of the wax pattern to the top of the mould, these risers ending at the top in a shallow basin. The molten metal comes up into these risers and cares for contraction of the casting, as well as avoiding defects in the collar of the weld. After the moulding material is well packed, these gate patterns are tapped lightly and withdrawn, except in the case of the metal pipes which are placed at points at which it would be impossible to withdraw a pattern.

Preheating. The ends to be welded are brought to a bright red heat by in-troducing the flame from a torch through the preheating gate. The torch must use either gasoline or kerosene, and not crude oil, as the crude oil deposits too much carbon on the parts. Preheating of other adjacent parts to care for contraction is done at this time by an additional torch burner. The heating flame is started gen-tly at first and gradually increased. The wax will melt and may be allowed to run out of the preheating gate by removing the flame at intervals for a few seconds. The heat is continued until the mould is thoroughly dried and the parts to be joined are brought to the red heat required. This leaves a mould just the shape of the wax pattern. The heating gate should then be plugged with an iron plug or a piece of fitted fire brick, and backed up with several shovels full of the mould-ing mixture, well packed.

Thermit Metal. The reaction takes place in a special crucible lined with magnesia tar, which is baked at a red heat until the tar is driven off and the mag-nesia left. This lining should last from twelve to fifteen reactions. This magnesia lining ends at the bottom of the crucible in a ring of magnesia stone and this ring carries a magnesia thimble through which the molten steel passes on its way to the mould. It will usually be necessary to renew this thimble after each reaction. This lower opening is closed before filling the crucible with thermit by means of a small disc or iron carrying a stem, which is called a tapping pin. This pin is placed in the thimble with the stem extending down through the opening and exposing about two inches. The top of this pin is covered with an asbestos washer, then with another iron disc and finally with a layer of refractory sand. The crucible is tapped by knocking the stem of the pin upwards with a spade or piece of flat iron about four feet long.

The charge of thermit is added by placing a few handfuls over the refrac-tory sand and then pouring in the balance required. The amount of thermit re-quired is calculated from the wax used. The wax is weighed before and after fill-ing the entire space that the thermit will occupy. This does not mean only the wax collar, but the space of the mould with all gates filled with wax. The num-ber of pounds of wax required for this filling multiplied by 25 will give the number of pounds of thermit to be used. To this quantity of thermit should be added 1 % of pure manganese, 1 % nickel thermit and 15 % of steel punchings. It is necessary, when more than 10 pounds of thermit will be used, to mix steel

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punchings not exceeding 3/8 inch diameter by 1/8 inch thick with the powder in order to sufficiently retard the intensity of the reaction.

Half a teaspoonful of ignition powder is placed on top of the thermit charge and ignited with a storm match or piece of red hot iron. The cover should be immediately closed on the top of the crucible and the operator should get away to a safe distance because of the metal that may be thrown out of the crucible. After allowing about 30 seconds to a minute for the reaction to take place and the slag to rise to the top of the crucible, the tapping pin is struck from below and the molten metal allowed to run into the mould. The mould should be al-lowed to remain in place as long as possible, preferably over night, so as to an-neal the steel in the weld, but in no case should it be disturbed for several hours after pouring. After removing the mould, drill through the metal left in the riser and gates and knock these sections off. No part of the collar should be removed unless absolutely necessary.

VOCABULARY

thermit – термит trade name – торговая марка ignition powder – порошок для поджигания термита barium superoxide – перекись бария crucible – тигель to force the ends apart – раздвинуть, развести концы wedge – клин jack – рычаг yellow wax – воск vent holes – отдушины retaining mould – форма вокруг стыка ground fire brick – молотый огне-упорный кирпич to pack – уплотнять(ся), заполнять, стать плотной массой rammer – трамбовка to care for – компенсировать collar of the weld – наплыв вокруг термитного шва heating gate – отверстие в форме pattern – шаблон moulding mixture – формовочная смесь

crude oil – нефть-сырец, сырая нефть to plug – затыкать magnesia – окись магния core – стержень magnesia tar – мастика с окисью магния thimble – зд. – канал, выпускное отверстие tapping pin – пробка (в выпускном отверстии) asbestos washer – асбестовая шайба refractory sand – огнеупорный песок to tap – открывать punchings – обрезки, высечки при штамповке storm match – штормовая спичка lining – футеровка this ring carries a magnesia thimble – в этом кольце есть выпускное от-верстие to carry a stem – иметь стержень to retard – отставать to anneal the steel – отжигать сталь

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словосочетаний: 1) усовершенствовать; 2) затравка, специальный поро-шок для зажигания; 3) установить в нужное положение; 4) компенсировать последствия усадки; 5) расстояние, на которое раздвигают детали; 6) огне-упорный песок; 7) по мере заполнения; 8) восковой шаблон; 9) выпор; 10) отводить пламя; 11) подбросить несколько полных лопат формовочной смеси; 12) покрытый изнутри; 13) асбестовая шайба; 14) стальные обрезки; 15) замедлить интенсивность реакции.


ста: 1) ground fire brick; 2) the mixture is packed hard with a rammer; 3) pre-heating gate; 4) the collar of the weld; 5) to withdraw a pattern; 6) to bring to a bright red heat; 7) to be thoroughly dried; 8) to plug with an iron plug; 9) well-packed mixture; 10) a ring of magnesia stone; 11) the charge of thermit; 12) multiplied by; 13) pure manganese; 14) tea-spoonful of; 15) to anneal the steel.

Unit 37. REQUIREMENTS FOR WELDING HULLS In making ship hulls weld connections are to be executed according to the

approved plans. A detail not specifically represented in the plans is, if any, to comply with the applicable requirements. Welding various types of steel is to be carried out by means of welding procedures approved for the purpose, even though an explicit indication to this effect may not appear on the approved plans.

The quality standard adopted by the shipyard is to be submitted to the Soci-ety and applies to all constructions unless otherwise specified on a case by case basis.

The service temperature is intended to be the ambient temperature, unless otherwise stated.

Welding consumables and procedures. Welding consumables and welding procedures adopted are to be approved

by the Society. The approval of the welding procedure is not required in the case of manual metal arc welding with approved covered electrodes, except in the case of one side welding on refractory backing (ceramic).

Consumables used for manual or semi-automatic welding (covered elec-trodes, flux-cored and flux-coated wires) of higher strength hull structural steels are to be at least of hydrogen-controlled grade H15 (H). Where the carbon equivalent is not more than 0.41 % and the thickness is below 30 mm, any type of approved higher strength consumables may be used at the discretion of the

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Society. Especially, welding consumables with hydrogen-controlled grade H15 (H) and H10 (HH) shall be used for welding hull steel forgings and castings of respectively ordinary strength level and higher strength level. Welding consum-ables approved for welding higher strength steels (Y) may be used in lieu of those approved for welding normal strength steels having the same or a lower grade. In case of welded connections between two hull structural steels of dif-ferent grades, as regards strength or notch toughness, welding consumables ap-propriate to one or the other steel are to be adopted.

Manual and semi-automatic welding is to be performed by welders certi-fied by the Society as specified in the “Guide for the certification of welders and welding inspectors”; the welders are to be employed within the limits of their respective approval. Personnel manning automatic welding machines and equip-ment are to be competent and sufficiently trained.

The internal organization of the shipyard is to be such as to ensure compli-ance with the requirements and to provide for assistance and inspection of weld-ing personnel, as necessary, by means of a suitable number of competent super-visors.

Non-destructive tests are to be carried out by qualified personnel, certified by the Society, or by recognized bodies in compliance with appropriate stan-dards. The qualifications are to be appropriate to the specific applications.

Technical equipment and facilities. The welding equipment is to be appropriate to the adopted welding proce-

dures, of adequate output power and such as to provide for stability of the arc in different welding positions. In particular, the welding equipment for special welding procedures is to be provided with adequate and duly calibrated measur-ing instruments, enabling easy and accurate reading, and adequate devices for easy regulation and regular feed.

Manual electrodes, wires and fluxes are to be stored in suitable locations so as to ensure their preservation in proper condition. Especially, where consum-ables with hydrogen-controlled grade are to be used, proper precautions are to be taken to ensure that manufacturer’s instructions are followed to obtain (dry-ing) and maintain (storage, maximum time exposed, re-backing) hydrogen-controlled grade.

For various structural details typical of welded construction in shipbuilding and not dealt with in this Section, the rules of good practice, recognized stan-dards and past experience are to apply as agreed by the Society.

The plates of the shell and strength deck are generally to be arranged with their length in the fore-aft direction. Possible exceptions to the above will be considered by the Society on a case-by-case basis; tests as deemed necessary (for example, transverse impact tests) may be required by the Society. Particular consideration is to be given to the overall arrangement and structural details of highly stressed parts of the hull.

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Prefabrication sequences are to be arranged so as to facilitate positioning and assembling as far as possible.

The amount of welding to be performed on board is to be limited to a minimum and restricted to easily accessible connections.

Welds located too close to one another are to be avoided. The minimum distance between two adjacent welds is considered on a case by case basis, tak-ing into account the level of stresses acting on the connected elements. In gen-eral, the distance between two adjacent butts in the same strake of shell or deck plating is to be greater than two frame spaces.

VOCABULARY

ship hull – корпус судна approved (plan) – утвержденный план Society – зд. – компания-заказчик on case-by-case basis – в каждом отдельном случае ambient temperature – температура окружающей среды on refractory backing – на огне-упорной подкладке at the discretion of Society – на ус-мотрение заказчика in lieu of – вместо appropriate – соответствующий, надлежащий

calibrate – проверять strake – лист, пластина plating – листовая обшивка frame – шпангоут notch – выемка, бороздка shell – обшивка strength deck – палуба fore – нос aft – корма transverse impact test – испытание на удар в поперечной плоскости prefabricated sequences – готовые, сборные фрагменты


I. Найдите в тексте английские эквиваленты следующих слов и словосочетаний: 1) соответствовать чему-либо; 2) в каждом отдельном случае; 3) односторонняя сварка на огнеупорной подкладке; 4) порошковая проволока; 5) электроды с контролируемым содержанием водорода; 6) обычная прочность; 7) жесткость выемки; 8) подходящий, надлежащий; 9) по усмотрению компании; 10) грамотный инспектор-контролер; 11) не-разрушающие методы контроля; 12) признанный орган; 13) своевременно проверенный; 14) точные показания; 15) указания производителя.

II. Переведите на РЯ следующие слова и словосочетания из тек-ста: 1) explicit indication; 2) to this effect; 3) unless otherwise specified; 4) ambient temperature; 5) covered electrodes; 6) flux-coated electrodes; 7) cer-tified welder; 8) to man a welding machine; 9) in compliance with; 10) measur-ing instruments; 11) regular feed; 12) grade; 13) the rules of good practice; 14) recognized standards; 15) to facilitate positioning and assembly.

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Unit 38. TYPES OF CONNECTIONS AND PREPARATION The type of connection and the edge preparation are to be appropriate to the

welding procedure adopted, the structural elements to be connected and the stresses to which they are subjected.

In general, butt connections of plating are to be full penetration, welded on both sides except where special procedures or specific techniques are adopted. Connections different from the above may be accepted by the Society on a case-by-case basis; in such cases, the relevant detail and workmanship specifications are to be approved. In case of welding plates with a difference in gross thickness equal to or greater than 3.00 or 4.00 mm, if the thinner plate has a gross thick-ness equal to or less than 10 mm, a taper having a length of not less than 4 times the difference in gross thickness is to be adopted for connections of plating per-pendicular to the direction of main stresses. For connections of plating parallel to the direction of main stresses, the taper length may be reduced to 3 times the difference in gross thickness. When the difference in thickness is less than the above values, it may be accommodated in the weld transition between plates. The acceptable root gap is to be in accordance with the adopted welding proce-dure and relevant bevel preparation.

Butt welding on permanent backing, i.e. butt welding assembly of two plates backed by the flange or the face plate of a stiffener, may be accepted where back welding is not feasible or in specific cases deemed acceptable by the Society. The type of bevel and the gap between the members to be assembled are to be such as to ensure a proper penetration of the weld on its backing and an adequate connection to the stiffener as required.

When lengths of longitudinals of the shell plating within 0,6 L amidships, or elements in general, subject to high stresses, are to be connected together by butt joints, these are to be full penetration. Other solutions may be adopted if deemed acceptable by the Society on a case-by-case basis.

The work is to be done in accordance with an approved procedure; in par-ticular, this requirement applies to work done on board or in conditions of diffi-cult access to the welded connection.

In general, ordinary fillet welding (without bevel) may be adopted for T connections of the various simple and composite structural elements, where they are subjected to low stresses (in general not exceeding 30 N/mm2) and adequate

precautions are taken to prevent the possibility of local laminations of the element against which the T web is welded. Where this is not the case, partial or full T penetration welding is to be adopted. This applies particularly to members over than 12 mm thick constituting the whole or part of the engine seatings.

Fillet welding may be of the following types: continuous fillet welding, where the weld is constituted by a continuous

fillet on each side of the abutting plate;

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intermittent fillet welding, which may be subdivided into chain welding, scallop welding, staggered welding.

Continuous fillet welding is to be adopted for watertight connections, for connections of brackets, lugs and scallops, at the ends of connections for a length of at least 75 mm, where intermittent welding is not allowed. Continuous fillet welding may also be adopted in lieu of intermittent welding wherever deemed suitable, and it is recommended where the spacing is low.

In case of automatic or semi-automatic deep penetration weld, the throat thickness may be reduced. It may be required by the Society to be increased, de-pending on the results of structural analyses. The leg length of fillet weld T con-nections is to be not less than 1.4 times the required throat thickness.

The throat thickness of the welds between the cut-outs in primary support-ing member webs for the passage of ordinary stiffeners is to be not less than the value obtained, in mm, from the special formula. The throat thickness of fillet welds connecting ordinary stiffeners and collar plates, if any, to the web of pri-mary supporting members is to be not less than 0,35 tW, where tW is the web gross thickness, in mm.

When fillet welding is carried out with automatic welding procedures, the throat thickness may be reduced up to 15 %, depending on the properties of the electrodes and consumables. However, this reduction may not be greater than 1,5 mm. The same reduction applies also for semi-automatic procedures where the welding is carried out in the downhand position.

VOCABULARY

plating – листовая обшивка workmanship – качество работы to approve – утверждать, разре-шать gross thickness – общая толщина taper – конус weld transition – 145 переходный участок (шва) root gap – зазор между сваривае-мыми кромками backing – подкладка flange – фланец, выступ stiffener – ребро / элемент жесткости feasible – исполнимый longitudinal – продольный брус T-connection – тавровое / Т-образ-ное соединение lamination – слоистость, расслаи-вание

engine seating – место установки двигателя abutting plate – торцевая, стыкуе-мая плита scallop weld – зубчатый, волни-стый шов staggered weld – шахматный шов chain welding – цепная сварка bracket – скоба, консоль lug – зажим, кронштейн scallop – зубчатый край throat thickness – толщина шва web – перегородка, балка leg of (fillet) – катет (углового шва) downhand / downward position – нижнее положение шва

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словосочетаний: 1) конструктивные детали; 2) выполняться с полным проплавлением; 3) при сварке листов обшивки; 4) перегородки опорных элементов; 5) основные нагрузки; 6) длину скоса можно уменьшить в 3 раза; 7) вышеуказанные величины; 8) разделка; 9) постоянная подкладка; 10) лицевая плита ребра жесткости; 11) нецелесообразный; 12) обеспечить необходимое проплавление; 13) продольные брусья обшивки; 14) тавровые соединения; 15) обычное ребро жесткости.

II. Переведите на АЯ следующие слова и выражения из текста:

1) edge preparation; 2) butt connections; 3) workmanship specifications; 4) gross thickness; 5) to accommodate ; 6) root gap; 7) butt welding assembly; 8) in conditions of difficult access; 9) ordinary fillet welding; 10) local lamina-tions; 11) continuous fillet welding; 12) intermittent fillet welding; 13) chain welding; 14) scallop weld; 15) staggered weld.

Unit 39. TYPES OF WELDING IN MAKING HULLS Partial or full T penetration welding is to be adopted for connections sub-

jected to high stresses for which fillet welding is considered unacceptable by the Society. Back gouging is generally required for full penetration welds.

Precautions are to be taken in order to avoid lamellar tears, which may be associated with:

cold cracking when performing T connections between plates of consid-erable thickness or high restraint;

large fillet welding and full penetration welding on higher strength steels.

Lap-joint welding may be adopted for: peripheral connection of doublers; internal structural elements subjected to very low stresses. Elsewhere, lap-joint welding may be allowed by the Society on a case by

case basis, if deemed necessary under specific conditions. Continuous welding is generally to be adopted. The surfaces of lap-joints are to be in sufficiently close contact. The dimensions of the lap-joint are to be specified.

Slot welding may be adopted in very specific cases. In general, slot weld-ing of doublers on the outer shell is not permitted within 0,6 L amidships. Slot welding is, in general, permitted only where stresses act in a predominant direc-tion. Slot welds are, as far as possible, to be aligned in this direction. Slot welds are to be of appropriate shape (in general oval) and dimensions, depending on the plate thickness, and may not be completely filled by the weld. The distance

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between two consecutive slot welds is to be not greater than a value which is de-fined on a case by case basis taking into account: 1) the transverse spacing be-tween adjacent slot weld lines; 2) the stresses acting in the connected plates; 3) the structural arrangement below the connected plates.

Corner joint welding, as adopted in some cases at the corners of tanks, per-formed with ordinary fillet welds, is permitted provided the welds are continu-ous and of the required size for the whole length on both sides of the joint.

The intermediate flat, through which the bilge keel is connected to the shell is to be welded as a shell doubler by continuous fillet welds. The butt welds of the doubler and bilge keel are to be full penetration and shifted from the shell butts.

The butt welds of the bilge plating and those of the doublers are to be flush in way of crossing, respectively, with the doubler and with the bilge keel. Butt welds of the intermediate flat are to be made to avoid direct connection with the shell plating, in order that they do not alter the shell plating, by using, for exam-ple, a copper or a ceramic backing.

In case of a strut connected by lap joint to the ordinary stiffener, the throat thickness of the weld is to be obtained, in mm, from a special formula. Fabri-cated propeller posts are to be welded with full penetration welding to the pro-peller shaft bossing.

VOCABULARY

gourging – строжка lamellar tears – расслаивание restraint – сжатие, сжимание doubler – дублер, удвоитель lap joint – нахлесточное соединение fillet weld – угловой шов slot weld – прорезной шов intermediate flat – прилегающий плоский участок corner joint – угловое соединение

bilge – днище (судна) shell doubler – вторая, дублирую-щая обшивка to be flush – быть вровень, утоп-ленный strut – стойка, распорка propeller – гребной винт post – опора shaft – вал bossing – выступ, насечка


словосочетаний: 1) холодные трещины; 2) нахлесточный шов; 3) оговари-вать размеры нахлесточных соединений; 4) внешняя обшивка; 5) главное направление; 6) выравнивать прорезные швы; 7) для каждого отдельного случая; 8) расстояние по косой; 9) расположение конструктивных элемен-тов; 10) угловое соединение; 11) угловой шов; 12) при условии; 13) непре-рывный шов; 14) быть вровень с чем-либо; 15) готовые опоры винта.

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II. Переведите на АЯ следующие слова и словосочетания: 1) back gourging; 2) high restraint; 3) higher strength steels; 4) slot welding; 5) consecu-tive slot welds; 6) transverse spacing; 7) structural elements below the con-nected parts; 8) to deem necessary; 9) throat thickness of the weld; 10) adjacent welds; 11) corner joint; 12) fillet welds; 13) intermediate flat; 14) shell doubler; 15) propeller shaft bossing.

III. Переведите на АЯ следующие предложения. 1. Угловое соединение – это сварное соединение двух элементов, рас-

положенных под углом друг к другу. 2. В нахлесточном соединении один элемент наложен на другой в одной плоскости, так что они частично пере-крывают друг друга. 3. В тавровом соединении плоскость одного элемента приложена к торцу другого под определенным углом. 4. Сварные соедине-ния могут быть стыковыми, угловыми, нахлесточными и тавровыми. 5. В стыковом соединении свариваемые детали соединены торцами, располо-женными в одной плоскости. 6. Сварочные швы различают по количеству слоев, ориентации в пространстве, длине и другим признакам. 7. Сплош-ной / непрерывный шов полностью охватывает все соединение. 8. Преры-вистый шов имеет разрывы в пределах одного соединения. 9. Прихваточ-ный шов используют для фиксации свариваемых элементов до начала сварки.

Unit 40. WORKMANSHIP IN MAKING HULLS Various welding procedures and consumables are to be used within the lim-

its of their approval and in accordance with the conditions of use specified in the respective approval documents.

Adequate protection from the weather is to be provided to parts being welded; in any event, such parts are to be dry. In welding procedures using bare, cored or coated wires with gas shielding, the welding is to be carried out in weather protected conditions, so as to ensure that the gas outflow from the noz-zle is not disturbed by winds and draughts.

The edge preparation is to be of the required geometry and correctly per-formed. In particular, if edge preparation is carried out by flame, it is to be free from cracks or other detrimental notches. The surfaces to be welded are to be free from rust, moisture and other substances, such as mill scale, slag caused by oxygen cutting, grease or paint, which may produce defects in the welds. Effec-tive means of cleaning are to be adopted particularly in connections with special welding procedures; flame or mechanical cleaning may be required. The pres-ence of a shop primer may be accepted. Setting appliances and systems to be used for positioning are to ensure adequate tightening adjustment and an appro-priate gap of the parts to be welded, while allowing maximum freedom for

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shrinkage to prevent cracks or other defects due to excessive restraint. The gap between the edges is to comply with the required tolerances or, when not speci-fied, it is to be in accordance with normal good practice. The misalignment be-tween plates with the same gross thickness is to be less than 0.15 t, without ex-ceeding 3 mm. The misalignment m in cruciform connections, measured on the median lines is to be less than half the gross thickness of the thinner abutting plate.

When welding aluminum alloy parts, particular care is to be taken so as to reduce as far as possible restraint from welding shrinkage, by adopting assem-bling and tack welding procedures suitable for this purpose, to keep possible de-formations within the allowable limits. Suitable preheating, to be maintained during welding, and slow cooling may be required.

Welding sequences and direction of welding are to be determined so as to minimize deformations and prevent defects in the welded connection. All main connections are generally to be completed before the ship is afloat. After each run, the slag is to be removed by means of a chipping hammer and a metal brush; the same precaution is to be taken when an interrupted weld is resumed or two welds are to be connected.

It is recommended and in some cases it may be required that special struc-tures subject to high stresses, having complex shapes and involving welding of elements of considerable thickness (such as rudder spades and stern frames), are prefabricated in parts of adequate size and stress-relieved in the furnace, before final assembly, at a temperature within the range 550–620 °C, as appropriate for the type of steel. In case of T-crossing of structural elements (one element con-tinuous, the other physically interrupted at the crossing) when it is essential to achieve structural continuity through the continuous element (continuity ob-tained by means of the welded connections at the crossing), particular care is to be devoted to obtaining the correspondence of the interrupted elements on both sides of the continuous element. Suitable systems for checking such correspon-dence are to be adopted.

VOCABULARY

gas shielding – среда защитного газа notch – выемка, углубление shop primer – заводская грунтовка setting appliance – регулировочное устройство tolerance – допуск misalignment – смещение осей, не-правильное расположение cruciform connection – крестооб-разное соединение

tack welding – прихваточная сварка chipping hammer – молоток для удаления шлака metal brush – металлическая щет-ка, скребок rudder spades – лопатки руля stern frames – каркас кормы median line – средняя линия prefabricated – заводского изготов-ления, сборный

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словосочетаний: 1) в защищенном месте; 2) быть нужной формы; 3) газо-пламенная очистка; 4) заводская грунтовка; 5) установка в удобное для сварки положение; 6) регулировка необходимой посадки; 7) зазор между деталями; 8) чрезмерное сжатие; 9) крестообразное соединение; 10) при-мыкающая пластина; 11) усадка при сварке; 12) технология монтажа; 13) предупредить появление дефектов; 14) после каждого прохода; 15) окончательная сборка.

II. Переведите на АЯ следующие слова и словосочетания: 1) cored

electrodes; 2) coated electrodes; 3) detrimental notches; 4) mill scale; 5) setting appliances; 6) required tolerances; 7) misalignment; 8) allowable limits; 9) free-dom for shrinkage; 10) interrupted weld; 11) oxygen cutting; 12) as appropriate for the type of steel; 13) at the crossing; 14) interrupted elements; 15) continuity.

Unit 41. MODIFICATIONS, REPAIRS AND TESTING DURING CONSTRUCTION

Deviations in the joint preparation and other specified requirements, in ex-

cess of the permitted tolerances and found during construction, are to be re-paired.

Welding by building up of gaps exceeding the required values and repairs of weld deformations may be accepted by the Society upon special examination. Defects and imperfections on the materials and welded connections found dur-ing construction are to be evaluated for possible acceptance on the basis of the applicable requirements of the Society. Where the limits of acceptance are ex-ceeded, the defective material and welds are to be discarded or repaired. If it is deemed appropriate by the Surveyor. When any serious or systematic defect is detected either in the welded connections or in the base material, the manufac-turer is required to promptly inform the Surveyor and submit the repair proposal. The Surveyor may require destructive or non-destructive examinations to be car-ried out for initial identification of the defects found and, in the event that re-pairs are undertaken, for verification of their satisfactory completion. In case of repairs involving the replacement of material already welded on the hull, the procedures to be adopted are to be agreed with the Society.

Materials, workmanship, structures and welded connections are to be sub-jected, at the beginning of the work, during construction and after completion, to inspections by the Shipyard suitable to check compliance with the applicable re-quirements, approved plans and standards. The manufacturer is to make avail-able to the Surveyor a list of the manual welders and welding operators and their

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respective qualifications. The manufacturer’s internal organization is responsible for ensuring that welders and operators are not employed under improper condi-tions or beyond the limits of their respective qualifications and that welding pro-cedures are adopted within the approved limits and under the appropriate operat-ing conditions.

The manufacturer is responsible for ensuring that the operating conditions, welding procedures and work schedule are in accordance with the applicable re-quirements, approved plans and recognized good welding practice. After comple-tion of the welding operation and workshop inspection, the structure is to be pre-sented to the Surveyor for visual examination at a suitable stage of fabrication.

As far as possible, the results on non-destructive examinations are to be submitted. Non-destructive examinations are to be carried out with appropriate methods and techniques suitable for the individual applications. Radiographic examinations are to be carried out on the welded connections of the hull. The Surveyor is to be informed when these examinations are performed. Radio-graphic examinations may be replaced by ultrasonic examinations.

When the visual or non-destructive examinations reveal the presence of un-acceptable indications, the relevant connection is to be repaired to sound metal for an extent and according to a procedure agreed with the Surveyor. The re-paired zone is then to be submitted to nondestructive examination, using a method deemed suitable by the Surveyor to verify that the repair is satisfactory. Ultrasonic and magnetic particle examinations may also be required to verify the quality of the base material.

A radiographic inspection is to be carried out on the welded butts of shell plating, strength deck plating as well as of members contributing to the longitu-dinal strength. This inspection may also be required for the joints of members subject to heavy stresses. The number of radiographs may be increased where requested by the Surveyor, mainly where visual inspection or radiographic soundings have revealed major defects.

As far as automatic welding of the panels butt welds during the pre-manufacturing stage is concerned, the shipyard is to carry out random non-destructive testing of the welds (radiographic or ultrasonic inspection) in order to ascertain the regularity and the constancy of the welding inspection. In the mid-ship area, radiographies are to be taken at the joining of panels. Each radi-ography device is situated in a butt joint at a cross-shaped welding. This re-quirement remains applicable where panel butts are shifted or where some strakes are built independently from the panels. It is recommended to take most of these radiographies at the intersections of butt and panel seams.

Where radiography is rejected and where it is decided to carry out a repair, the shipyard is to determine the length of the defective part, then a set of inspec-tion radiographies of the repaired joint and of adjacent parts is to be taken. Where the repair has been decided by the inspection office of the shipyard, the

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film showing the initial defect is to be submitted to the Surveyor together with the film taken after repair of the joint.

VOCABULARY

imperfections – зд. – отступления от стандарта to discard – отказаться от исполь-зования surveyor – инспектор systematic defect – серьезный кон-структивный дефект pre-manufacturing = prefabrication

random testing – выборочный кон-троль mid-ship area – внутренняя часть корабля radiography – рентгенография strake – планка, пояс наружной обшивки корабля inspection office – отдел техниче-ского контроля


словосочетаний: 1) исправлять, устранять недостатки; 2) наплавка зазо-ров; 3) если дефекты недопустимы; 4) для решения вопроса о приемлемо-сти; 5) серьезные конструктивные дефекты; 6) предложить план; 7) перво-начальное выявление; 8) подтверждение; 9) проверить соответствие; 10) контроль на уровне цеха; 11) неразрушающие методы контроля; 12) до доброкачественного металла; 13) отвечающие за прочность по длине; 14) радиографическое / рентгенологическое исследование; 15) правиль-ность результатов контроля.

II. Переведите на АЯ следующие слова и словосочетания: 1) in ex-

cess of the permitted tolerances; 2) upon special examination; 3) defects and im-perfections; 4) applicable requirements; 5) to discard; 6) appropriate; 7) the re-placement of the material; 8) beyond the limits of their respective qualifications; 9) work schedule; 10) visual examination; 11) unacceptable indications; 12) magnetic particle examination; 13) radiograph; 14) inspection office; 15) cross-shaped welding.

Unit 42. SPECIAL REQUIREMENTS

Special structural details are those characterized by complex geometry, possibly associated with high or alternate stresses. For special structural details, specific requirements are to be fulfilled during their design, construction, selec-tion of materials, welding and survey.

Special structural details are listed together with the specific requirements which are to be fulfilled. Other structural details may be considered by the Soci-ety as special details, when deemed necessary.

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Design requirements specify the local geometry, dimensions and scantlings of the structural elements which constitute the detail, any local strengthening, cases where a fatigue check is to be carried out. Then the design requirements specify locations (hot spots) where the stresses are to be calculated and the fa-tigue check performed, the direction in which the normal stresses are to be cal-culated, stress concentration factors to be used for calculating the hot spot stress range.

Constructional requirements specify the allowable misalignment and toler-ances, depending on the detail arrangement and any local strengthening.

Material requirements specify the material quality to be used for specific elements which constitute the detail, depending on their manufacturing proce-dure, the type of stresses they are subjected to, and the importance of the detail with respect to the ship operation and overall safety. In addition, these require-ments specify where material inspections are to be carried out.

Welding requirements specify where partial or full T penetration welding or any particular welding type or sequence is to be adopted. In addition, these requirements specify when welding procedures are to be approved. Since weld shape and undercuts are influencing factors on fatigue behaviour, fillet welds are to be elongated in the direction of the highest stresses and care is to be taken to avoid undercuts, in particular at the hot spots.

Survey requirements specify where non-destructive examinations of welds are to be carried out and, where this is the case, which type is to be adopted.

VOCABULARY to specify – уточнять survey – осматривать, инспектиро-вать special structural details – особые элементы конструкции geometry – форма и размеры, кон-фигурация

scantlings – набор элементов fatigue check – испытание на уста-лость (металла) misalignment – смещение, несоос-ность strengthening – усиление, укрепле-ние


I. Найдите в тексте английские эквиваленты следующих слов и словосочетаний: 1) сложная конфигурация; 2) проводить испытания на усталость металла; 3) укрепление; 4) рассчитывать напряжения; 5) допус-тимое смещение; 6) концентрация напряжений; 7) эксплуатация судна; 8) проявление усталости металла; 9) удлинить швы; 10) в отношении чего-либо, для … .

II. Переведите на АЯ следующие слова и словосочетания: 1) alter-nate stresses; 2) design; 3) construction; 4) scantlings; 5) to specify require-ments; 6) hot spots; 7) hot spots stress range; 8) manufacturing process; 9) un-dercut; 10) survey requirements.

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Unit 43. WELD TESTING The following requirements determine the testing conditions for gravity

tanks, including independent tanks of 5 m3 or more in capacity, watertight or weather-tight structures. The purpose of these tests is to check the tightness and / or the strength of structural elements. Tests are to be carried out in the presence of the Surveyor at a stage sufficiently close to completion so that any subsequent work would not impair the strength and tightness of the structure.

IR InI particular, tests are to be carried out after air vents and sounding pipes are fitted. The Society may accept that structural testing of a sister ship is limited to a single tank for each type of structural arrangement. However, if the Surveyor detects anomalies, he may require the number of tests to be increased or the same number of tests to be provided as for the first ship in a series.

Shop primer is a thin coating applied after surface preparation and prior to fabrication as a protection against corrosion during fabrication. Protective coat-ing is a final coating protecting the structure from corrosion. Structural testing is a hydrostatic test carried out to demonstrate the tightness of the tanks and the structural adequacy of the design. Where practical limitations prevail, and hy-drostatic testing is not feasible (for example, when it is difficult, in practice, to apply the required head at the top of the tank), hydro-pneumatic testing may be carried out instead. Hydro-pneumatic testing is a combination of hydrostatic and air testing, consisting in filling the tank to the top with water and applying an additional air pressure. Leak testing is an air or other medium test carried out to demonstrate the tightness of the structure. Hose testing is carried out to demon-strate the tightness of structural items not subjected to hydrostatic or leak testing and of other components which contribute to the watertight or weather-tight in-tegrity of the hull.

A sister ship is a ship having the same main dimensions, general arrange-ment, capacity plan and structural design as those of the first ship in a series. Structural testing may be carried out before or after launching, after application of the shop primer or of the protective coating, provided that one of the follow-ing two conditions is satisfied: 1) all the welds are completed and carefully in-spected visually to the satisfaction of the Surveyor prior to the application of the protective coating and 2) leak testing is carried out prior to the application of the protective coating. In the absence of leak testing, protective coating is to be ap-plied after the structural testing of all erection welds, both manual and auto-matic, i all manual fillet weld connections on tank boundaries and manual pene-tration welds.

When hydro-pneumatic testing is performed, the conditions are to simulate, as far as practicable, the actual loading of the tank. The value of the additional air pressure is at the discretion of the Society, but it is to be at least as defined for leak testing. The same safety precautions as for leak testing are to be adopted.

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An efficient indicating liquid, such as a soapy water solution, is to be applied to the welds. Where leak testing is carried out, an air pressure of 0,15.105 Pa is to be applied during t the test. Prior to inspection it is recommended that the air e pressure in the tank should be raised to 0,2.105 Pa and kept at this level for ap-proximately 1 hour to reach a stabilized state, with a minimum number of person-nel in the vicinity of the tank, and then lowered to the test pressure.

The test may be conducted after the pressure has reached a stabilized state at 0,2.105 Pa, without lowering the pressure provided the Society is satisfied of the safety of the personnel involved in the test. A U-tube filled with water up to a height corresponding to the test pressure is to be fitted to avoid overpressure of the com-partment tested and to verify the test pressure. 14.2.2 / RINA B-I, 23.1.2 / BV 3.042.

The U-tube is to have a cross-section larger than that of the pipe supplying air. In addition, the test pressure is also to be verified by means of one master pressure gauge. Alternative means which are considered to be equivalently reli-able may be accepted at the discretion of the Surveyor.

Leak testing is to be carried out, prior to the application of a protective coating, on all fillet weld connections on tank boundaries, and penetration and erection welds on tank boundaries excepting welds made by automatic proc-esses. Selected locations of automatic erection welds and pre-erection manual or automatic welds may be required to be similarly tested to the satisfaction of the Surveyor, taking account of the quality control procedures operating in the ship-yard. When hose testing is required to verify the tightness of the structures, the minimum pressure in the hose, at least equal to 2,0.105 Pa, is to be applied at a maximum distance of 1,5 m. The nozzle diameter is to be not less than 12 mm. Other testing methods may be accepted, at the discretion of the Society, based upon equivalency considerations.

VOCABULARY

water-tight – герметичный, водо-непроницаемый weather tight – погодостойкий, за-щищающий от атмосферного воз-действия capacity – вместимость, грузо-подъемность air vent – воздуховод, вентиляци-онное отверстие sounding pipe – трубка эхолота

sister ship – однотипное судно gravity tank – бак подачи топлива самотеком erection weld – монтажный шов at the discretion of – на усмотрение leak testing – испытание на герме-тичность master pressure gauge – главный манометр hose testing – испытание наливом

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словосочетаний: 1) вместимость, объем; 2) бак подачи топлива самотеком; 3) проверить герметичность; 4) нарушить прочность; 5) заводская грунтов-ка; 6) герметичность танков; 7) защитное покрытие; 8) испытания, проводи-мые с помощью других средств; 9) целостность корпуса; 10) монтажные швы; 11) действительная загрузка танка; 12) на усмотрение; 13) стабилизи-роваться; 14) поблизости; 15) избегать излишне высокого давления.

II. Переведите на АЯ следующие слова и словосочетания: 1) sister

ship; 2) to detect anomalies; 3) prior to fabrication; 4) the structural adequacy of the design; 5) hydrostatic testing; 6) hydropneumatic testing; 7) air testing; 8) hose testing; 9) capacity plan; 10) to the satisfaction of the Surveyor; 11) tank boundaries; 12) indicating liquid; 13) test pressure; 14) cross-section; 15) quality control procedures.

Unit 44. PERSONNEL REQUIREMENTS Welding of important structures such as hulls and hull equipment, superstruc-

ture, taking part in the overall strength, stern frames, rudders, etc. shall be carried out only by certified welders, with approved welding procedures and welding con-sumables and at builders and subcontractors recognized by the Society.

Builders and subcontractors will have to prove their abilities for the weld-ing operations in question. It is assumed that the builders and subcontractors make use of the necessary equipment for carrying out inspection of the welding operations in a satisfactory manner. Important welding operations shall be car-ried out under daily supervision of an inspector, who has the experience and qualifications enabling him to judge the work. Builders and subcontractors shall keep a card index or register of certified workers. The register shall give infor-mation on their training and date and results of qualification tests. Information about the base metal, type of welding consumables, joint design and welding po-sitions shall be stated in the event of re-qualification tests. The surveyor shall be allowed to examine the register at any time.

The following terms are used in connection with fabrication of ship struc-tures:

pWPS – preliminary welding procedure specification. A tentative weld-ing procedure specification, which is assumed adequate by the builder as basis for approval by the Society;

WPS – welding procedure specification: a specification of material, de-tailed methods, practices and parameters employed in the welding of a particular joint, and which have to be approved by the Society;

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WPQR- welding procedure qualification record: the record of actual pa-rameters employed during welding of the qualification test piece, and results of non-destructive and mechanical testing;

WPQT – welding procedure qualification test: a test carried out to dem-onstrate that the weld performed according to pWPS meets the specified re-quirements;

WPT – weld production test: a test carried out to demonstrate that actual production welding meets the specified requirements;

NDT – non-destructive testing: visual inspection, radiographic testing, magnetic particle testing, penetrant testing and other non-destructive methods for revealing defects and irregularities;

Manual welding – welding where the electrode holder, welding hand gun torch or blowpipe are manipulated by hand;

Partly mechanized welding – manual welding where the wire feed is mechanized;

Fully mechanized welding – welding where all main operations (exclud-ing the handling of the workpiece) are mechanized;

Fully automatic processes – welding where all operations are mecha-nized. Welding operators using fully mechanized or fully automatic processes shall be required to have records of proficiency, which provide evidence that the operators have received adequate regular training in setting, programming and operating the equipment. Welding and testing of weld assemblies shall be car-ried out in the presence of the Society’s representative. Upon successful comple-tion, and on the client’s request, the Society will certify that the welder has passed the approval testing.

VOCABULARY

hull – корпус судна hull equipment – оснащение корпуса superstructure – судовые надстройки stern frames – кормовые шпангоуты rudder – руль certified – аттестованный at builder’s – на стройплощадке строителя subcontractor – подрядчик card index – картотека register – реестр mechanized – автоматизированный

pWPS – пСПС – предварительная спецификация процедуры сварки WPQR – ПАПС – протокол атте-стации процедуры сварки WPQT – КИПС – квалификацион-ное испытание процедуры сварки WPT – ПИПС – производственное испытание процедуры сварки NDT – НК – неразрушающий кон-троль actual production – зд. – отдельно взятый участок заводской сварки irregularities – неровности

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словосочетаний: 1) значимые для общей прочности; 2) аттестованный сварщик; 3) осуществлять контроль сварочных работ; 4) повторное квали-фикационное испытание; 5) конкретное соединение; 6) выполняться вруч-ную; 7) автоматическая подача проволоки; 8) наружный осмотр; 9) налад-ка, программирование и эксплуатация; 10) сварные узлы.

II. Переведите на АЯ следующие слова и словосочетания: 1) sub-

contractor; 2) under daily supervision; 3) qualification test; 4) joint design; 5) tentative; 6) test piece; 7) penetrant testing; 8) blowpipe; 9) records of profi-ciency; 10) adequate regular training.

Unit 45. WELDING PROCEDURE SPECIFICATIONS IN SHIP BUILDING

This section specifies requirements for welding procedure specifications

and welding procedure qualification tests for C-Mn and low alloy steels, alumi-num, austenitic stainless steel and ferritic-austenitic (duplex) stainless steels. C-Mn and low alloy steels are in this context referred to as “steels”. Welding may be performed with the following processes:

manual metal arc welding ( metal arc welding with covered electrode); self-shielded tubular –cored arc welding; submerged arc welding with one wire electrode (SAW); submerged arc welding with strip electrode; metal active gas welding (MAG); tubular-cored metal arc welding with active gas shield; tubular-cored metal arc welding with inert gas shield; tungsten inert gas arc welding (TIG); plasma arc welding. A welding procedure specification shall contain as a minimum the follow-

ing information relevant for welding operations: material: standard, grade and modification; nominal thickness or diameter range (dimensions); welding process; joint or groove designs with tolerances; welding position(s) and direction of progression; welding consumables, trade name, electrode or wire diameter, shielding

gas, flux and recognized classification; welding sequence: number and order of passes or layers;

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electrical parameters: voltage range, current range, polarity; travel speed and heat input ranges; preheat temperatures; post weld heat treatment parameters; details of cleaning processes employed and restrictions, if any. The welding procedure specification is compiled on the basis of other ap-

proved welding procedures. For the following types of services the approval of welding procedure specifications is necessary:

butt welds used in cargo tanks, process pressure vessels, and\or piping systems for liquefied gases;

all welds in aluminum; butt welds and essential fillet welds used in cargo tanks; hull structure, process pressure vessels and / or piping systems in fer-

ritic-austenitic stainless steels; butt welds in plate thickness above 50 mm; butt welds in material grade E and F single-side butt welds with and

without backing in the vertical down position, welded connections between cast-ings / forgings and rolled material, such as stern frames, rudder, welding of highly stressed butt welds and cruciform joints located at large hatch openings;

when welding consumables are not the type approved. When a welding procedure qualification test is required, the tests must be

performed in the environment applicable to the actual production and meet the specified minimum requirements.

VOCABULARY

self-shielded – без дополнительной газовой защиты tubular-cored arc welding – сварка трубчатой порошковой проволо-кой strip electrode – ленточный элек-трод heat input – погонная энергия process pressure vessel – сосуд под давлением

cruciform – крестообразный C-Mn steel – углеродисто-марганцевая сталь nominal thickness – условная тол-щина groove – паз, выемка vertical down position – положение вертикальной сварки сверху вниз rolled material – прокат hatch – люк


словосочетаний: 1) квалификационные испытания; 2) сварка без дополни-тельной защиты; 3) дуговая сварка под флюсом; 4) сварка металлическим электродом в среде активного газа; 5) трубчатая порошковая проволока;

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6) принятая классификация; 7) скорость прохода; 8) сварка без подкладки; 9) литые и кованые детали; 10) стыковые швы, испытывающие большие напряжения.

II. Переведите на АЯ следующие слова и словосочетания: 1) strip

electrode; 2) are referred to; 3) inert gas shielding; 4) nominal thickness; 5) groove design; 6) heat input; 7) types of services; 8) cargo tank; 9) process pressure vessel; 10) vertical down position.

Unit 46. SAFETY PRECAUTIONS WITH ACETYLENE CYLINDERS

In oxy-fuel welding operations many safety precautions must be observed.

There must be a clear space between the gas cylinder and the work so that cylin-der valves could be reached easily and quickly. If acetylene cylinders have been stored or transported horizontally, (on their sides), stand cylinders vertically (up-right) for 45 minutes prior to their use.

A. Always refer to acetylene by its full name and not by the word “gas” alone. Acetylene is very different from city or furnace gas. Acetylene is a compound of carbon and hydrogen, produced by the reaction of water and calcium carbide.

B. Acetylene cylinders must be handled with care to avoid damage to the valves or to the safety fuse plug. The cylinders must be stored upright in a well ventilated, well protected, dry location at least 20 ft from highly combustible materials, such as oil, paint, or excelsior. Valve protection caps must always be in place, hand-tight, except when cylinders are in use. Do not store the cylinders near radiators, furnaces, or in any place with above normal temperatures. In tropical climates, care must be taken not to store acetylene in areas where the temperature is in excess of 137 ºF (58 ºC). Heat will increase the pressure, which may cause the safety fuse plug in the cylinder to blow out. Storage areas should be located away from elevators, gangways, or other places where there is a danger of cylinders being knocked over or damaged by falling objects.

C. Before attaching the pressure regulators, open each acetylene cylinder valve for an instant to blow dirt out of the nozzles. Wipe off the connection seat with a clean cloth. Do not stand in front of valves when opening them.

D. Outlet valves which have become clogged with ice should be thawed with warm water. Do not use scalding water or an open flame.

E. Be sure the regulator tension screw is released before opening the cylin-der valve. Always open the valve slowly to avoid strain on the regulator gauge which records the cylinder pressure. Do not open the valve more than one and one-half turns. Usually, one-half turn is sufficient. Always use the special T-wrench pro-vided for the acetylene cylinder valve. Leave this wrench on the

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stem of the valve till the cylinder is in use so the acetylene can be quickly turned off in an emergency.

F. Acetylene is a highly combustible fuel gas and great care should be taken to keep sparks, flames, and heat away from the cylinders. Never open an acetylene cylinder valve near other welding or cutting work.

G. Never test for an acetylene leak with an open flame. Test all joints with soapy water. Should a leak occur around the valve stem of the cylinder, close the valve and tighten the packing nut. Cylinders leaking around the safety fuse plug should be taken outdoors, away from all fires and sparks, and the valve opened slightly to permit the contents to escape.

H. If an acetylene cylinder should catch fire, it can usually be extinguished with a wet blanket. A burlap bag wet with calcium chloride solution is effective for such an emergency. If these fail, spray a stream of water on the cylinder to keep it cool.

I. Never interchange acetylene regulators, hose, or other apparatus with simi-lar equipment intended for oxygen.

J. Always turn the acetylene cylinder so the valve outlet will point away from the oxygen cylinder.

K. When returning empty cylinders, see that the valves are closed to prevent escape of residual acetylene or acetone solvent. Screw on protecting caps.

L. Handle all compressed gas with extreme care. Keep cylinder caps on when not in use.

M. Make sure that all compressed gas cylinders are secured to the wall or other structural supports. Keep acetylene cylinders in the vertical condition.

O. Store compressed gas cylinders in a safe place with good ventilation. Acetylene cylinders and oxygen cylinders should be kept apart.

N. Never use acetylene at a pressure in excess of 15 psi (103.4 kPa). Higher pressure can cause an explosion.

O. Acetylene is nontoxic; however, it is an asphyxiant and can cause asphyxa-tion in big enough concentrations.

VOCABULARY

furnace gas – топочный газ calcium carbide – карбид кальция safety fuse plug – плавкий предо-хранитель excelsior – древесные стружки hand-tight – плотно закрытый gangway – трап, сходня connection seat – соединительное седло outlet valve – выпускной клапан regulator tension screw – натяжной винт

regulator gauge – манометр T-wrench – гаечный ключ stem of the valve – стержень кла-пана acetylene leak – утечка ацетилена packing nut – герметизирующая гайка burlap bag – джутовый мешок asphyxiant – удушающий отрав-ляющий газ

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Упражнения. I. Найдите в тексте эквиваленты следующих слов и словосочета-

ний: 1) furnace gas; 2) safety fuse plug; 3) excelsior; 4) storage areas; 5) con-nection seat; 6) tension screw; 7) regulator gauge; 8) combustible gas; 9) puck-ing nut; 10) to extinguish flame.

II. Переведите на АЯ следующие слова и словосочетания: 1) меры

техники безопасности; 2) до использования; 3) баллон с ацетиленом; 4) хранить вертикально; 5) горючие материалы; 6) превышать что-либо; 7) показывать давление в баллоне; 8) пол-оборота; 9) проверять наличие утечки; 10) сжатый газ.

III. Переведите на АЯ следующие предложения. 1. Ацетилен – химическое соединение углерода и водорода, в нор-

мальном состоянии представляющее собой бесцветный горючий газ с рез-ким запахом. 2. Ацетилен взрывоопасен при соединении с кислородом. 3. Сгорание ацетилена в смеси с техническим кислородом обеспечивает высокую температуру, достигающую 3200 оС. 4. Технический ацетилен получают из карбида кальция, действуя на него водой в специальных аце-тиленовых генераторах. 5. Газообразный ацетилен может растворяться в воде, бензине, но обычно его растворяют в ацетоне. 6. Баллоны с газом, включая ацетилен, следует хранить в вертикальном положении в сухом, хорошо проветриваемом помещении. 7. Чтобы продуть мундштук, до на-чала работы с ацетиленом нужно на мгновение открыть клапаны. 8. Клапа-ны нужно открывать медленно, чтобы избежать скачка давления на мано-метре, регистрирующем давление в баллоне. 9. Герметичность соединений проверяют с помощью мыльного раствора, который наносится кисточкой или тампоном. 10. При возврате пустых баллонов, чтобы не допустить вы-броса остатков ацетилена, нужно убедиться, что все клапаны закрыты.

Unit 47. OXY-ACETYLENE WELDING EQUIPMENT The equipment used for oxyacetylene welding consists of a source of oxy-

gen and a source of acetylene from a portable or stationary outfit, along with a cutting attachment or a separate cutting torch. Other equipment requirements in-clude suitable goggles for eye protection, gloves to protect the hands, a method to light the torch, and wrenches to operate the various connections on the cylin-ders, regulators, and torches.

Stationary welding equipment is installed where welding operations are conducted in a fixed location. Oxygen and acetylene are generally provided in the welding area. Oxygen is obtained from a number of cylinders manifolded

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and equipped with a master regulator. The regulator and manifold control the pressure and the flow together. The oxygen is supplied to the welding stations through a pipe line equipped with station outlets.

Acetylene is obtained either from acetylene cylinders or an acetylene gen-erator It is supplied to the welding stations through a pipe line equipped with station outlets.

The portable oxyacetylene welding outfit consists of an oxygen cylinder and an acetylene cylinder with attached valves, regulators, gauges, and hoses. This equipment may be temporarily secured on the floor or mounted on an all welded steel truck. The trucks are equipped with a platform to support two large size cylinders. The cylinders are secured by chains attached to the truck frame. A metal toolbox, welded to the frame, provides storage space for torch tips, gloves, fluxes, goggles, and necessary wrenches.

Acetylene is a fuel gas composed of carbon and hydrogen. It is generated by the action of calcium carbide, a gray stone-like substance, and water in a generating unit. Acetylene is colorless, but it has a distinctive odor that can be easily detected. Mixtures of acetylene and air, containing from 2 to 80 % acety-lene by volume, will explode when ignited. However, with suitable welding equipment and proper precautions, acetylene can be safely burned with oxygen for heating, welding, and cutting purposes.

Acetylene, when burned with oxygen, produces an oxyacetylene flame with inner cone tip temperatures of approximately 6300 ºF (3482 ºC) for an oxidizing flame; 5850 ºF (3232 ºC) for a neutral flame; and 5700 ºF (3149 ºC) for a car-burizing flame.

A commonly used commercial generator uses 300 lb of calcium carbide and 300 gal. of water. This amount of material will generate 4.5 cu ft of acety-lene per pound; the output for this load is approximately 300 cu ft per hour for 4.5 hours.

Since considerable heat is given off during the reaction, precautions must be taken to prevent excessive pressures in the generator which might cause fires or explosions.

In the operation of the generator, the calcium carbide is added to the water through a hopper mechanism at a rate which will maintain a working pressure of the equipment. A sludge, consisting of hydrated or slaked lime, settles in the bottom approximately 15 psi (103.4 kPa). A pressure regulator is a built-in part of this generator and is removed by means of a sludge outlet.

Although acetylene is stable under low pressure, if compressed to 15 psi (103.4 kPa), it becomes unstable. Heat or shock can cause acetylene under pres-sure to explode. Avoid exposing filled cylinders to heat, furnaces, radiators, open fires, or sparks (from a torch). Avoid striking the cylinder against other ob-jects and creating sparks. To avoid shock when transporting cylinders, do not drag, roll, or slide them on their sides. Acetylene can be compressed into cylin-ders when dissolved in acetone at pressures up to 250 psi (1724 kPa).

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For welding purposes, acetylene is contained in three common cylinders with capacities of 60, 100, and 300 cu ft. Acetylene must not be drawn off in volumes greater than 1/7 of the cylinder’s rated capacity.

Acetylene cylinders are equipped with safety plugs which have a small hole through the center. This hole is filled with a metal alloy which melts at ap-proximately 212 ºF (100 ºC), or releases at 500 psi (3448 kPa). When a cylinder is overheated, the plug will melt and permit the acetylene to escape before dan-gerous pressures can be developed. The plug hole is too small to permit a flame to burn back into the cylinder if escaping acetylene is ignited.

Brass acetylene cylinder valves have squared stainless steel valve stems. These stems can be fitted with a cylinder wrench and opened or closed when the cylinder is in use. The outlet of the valve is threaded for connection to an acety-lene pressure regulator by means of a union nut. The regulator inlet connection gland fits against the face of the threaded cylinder connection, and the union nut draws the two surfaces together. Whenever the threads on the valve connections are damaged to a degree that will prevent proper assembly to the regulator, the cylinder should be marked and set aside for return to the manufacturer.

WARNING. Acetylene which may accumulate in a storage room or in a confined

space is a fire arid explosion hazard. All acetylene cylinders should be checked, using a soap solution, for leakage at the valves and safety fuse plugs.

VOCABULARY

stationary outfit – стационарное оборудование portable outfit – переносное обору-дование cutting attachment – насадка для резания manifold – коллектор, разветвлен-ный трубопровод to manifold – соединить между со-бой в единую систему master regulator – главный редуктор outlet – выходное отверстие welding station – сварочный пост work station – рабочее место cylinder truck – тележка для пере-возки газовых баллонов

carburizing flame – науглерожен-ное пламя inner flame tip – ядро пламени oxidizing flame – окислительное пламя sludge – ил (в ацетиленовом гене-раторе) valve stem – стержень клапана pressure regulator – газовый редуктор union nut – соединительная гайка connection gland – соединитель-ный сальник thread – резьба threaded – нарезной, с нарезкой

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словосочетаний: 1) установить сварочное оборудование; 2) науглерожен-ное пламя; 3) комплект переносного оборудования; 4) тележка для пере-возки газовых баллонов; 5) регулировать давление; 6) специфический за-пах; 7) зажигать, воспламеняться; 8) загрузочный механизм; 9) плавкий предохранитель; 10) соединительная гайка.

II. Дайте русские эквиваленты следующих слов и словосочетаний:

1) oxyacetylene welding; 2) to secure the equipment; 3) fixed location; 4) master regulator; 5) toolbox; 6) generating unit; 7) proper precautions; 8) inner cone tip; 9) to prevent excessive pressure; 10) a built-in part of the generator.

III. Переведите на АЯ следующие предложения. 1. В комплект оборудования входит набор гаечных ключей для регу-

лирования разных соединений, имеющихся на баллонах, редукторах и го-релках. 2. Избыток ацетилена в науглероженном пламени приводит к его разложению на углерод и водород. 3. Кислород подается к месту сварки по трубопроводу с выходами для каждого рабочего места. 4. Баллоны крепят-ся к тележке цепями. 5. В ходе реакции получения ацетилена выделяется большое количество тепла. 6. Ацетилен находится в баллонах в виде рас-твора в ацетоне под давлением 254 psi. 7. Плавкий предохранитель – это отверстие, заполненное сплавом металла с температурой плавления при-мерно 100º. 8. Сварочное пламя имеет сложную структуру, и качество сварки во многом зависит от правильности его регулирования. 9. Для по-лучения ацетилена карбид кальция добавляют к воде через загрузочный бункер со скоростью, которая поддерживает рабочее давление оборудова-ния. 10. Окислительное пламя получается при избытке кислорода, а науг-лероженное – при его недостатке.

Unit 48. OXYGEN AND ITS PRODUCTION Oxygen is a colorless, tasteless, odorless gas that is slightly heavier than

air. It is nonflammable but will support combustion with other elements. In its free state, oxygen is one of the most common elements. The atmosphere is made up of approximately 21 parts of oxygen and 78 parts of nitrogen, the remainder being rare gases. Rusting of ferrous metals, discoloration of copper, and the cor-rosion of aluminum are all due to the action of atmospheric oxygen, known as oxidation.

Oxygen is obtained commercially either by the liquid air process or by the electrolytic process. In the liquid air process, air is compressed and cooled to a

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point where the gases become liquid. As the temperature of the liquid air rises, nitrogen in a gaseous form is given off first, since its boiling point is lower than that of liquid oxygen. These gases, having been separated, are then further puri-fied and compressed into cylinders for use. The liquid air process is by far the most widely used to produce oxygen. In the electrolytic process, water is broken down into hydrogen and oxygen by the passage of an electric current. The oxy-gen collects at the positive terminal and the hydrogen at the negative terminal. Each gas is collected and compressed into cylinders for use.

Always refer to oxygen as oxygen, never as air. Combustibles should be kept away from oxygen, including the cylinder, valves, regulators, and other hose apparatus. Oxygen cylinders and apparatus should not be handled with oily hands or oily gloves. Pure oxygen will support and accelerate combustion of al-most any material, and is especially dangerous in the presence of oil and grease. Oil and grease in the presence of oxygen may spontaneously ignite and burn violently or explode. Oxygen should never be used in any air tools or for any of the purposes for which compressed air is normally used.

A typical oxygen cylinder is made of steel and has a capacity of 220 cu ft at a pressure of 2000 psi (13,790 kPa) and a temperature of 70 ºF (21 ºC). At-tached equipment provided by the oxygen supplier consists of an outlet valve, a removable metal cap for the protection of the valve, and a low melting point safety fuse plug and disk. The cylinder is fabricated from a single plate of high grade steel so that it will have no seams and is heat treated to achieve maximum strength. Because of their high pressure, oxygen cylinders undergo extensive testing prior to their release for work, and must be periodically tested thereafter.

The gases compressed in oxygen and acetylene cylinders are held at pres-sures too high for oxyacetylene welding. Regulators reduce pressure and control the flow of gases from the cylinders. The pressure in an oxygen cylinder can be as high as 2200 psi (15,169 kPa), which must be reduced to a working pressure of 1 to 25 psi (6.90 to 172.38 kPa). The pressure of acetylene in an acetylene cylinder can be as high as 250 psi (1724 kPa) and must be reduced to a working pressure from 1 to 12 psi (6.90 to 82.74 kPa). A gas pressure regulator will automatically deliver a constant volume of gas to the torch at the adjusted work-ing pressure.

The regulators for oxygen, acetylene, and liquid petroleum fuel gases are of different construction. They must be used only for the gas for which they were designed. Most regulators in use are either the single stage or the two stage type. Check valves must be installed between the torch hoses and the regulator to pre-vent flashback through the regulator. The single stage oxygen regulator reduces the cylinder pressure of a gas to a working pressure in one step. The single stage oxygen regulator mechanism has a nozzle through which the high pressure gas passes, a valve seat to close off the nozzle, and balancing springs. Some types have a relief valve and an inlet filter to exclude dust and dirt. Pressure gauges

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are provided to show the pressure in the cylinder or pipe line and the working pressure.

In operation, the working pressure falls as the cylinder pressure falls, which occurs gradually as gas is withdrawn. For this reason, the working pressure must be adjusted at intervals during welding operations when using a single stage oxygen regulator.

The oxygen regulator controls and reduces the oxygen pressure from any standard commercial oxygen cylinder containing pressures up to 3000 psi. The high pressure gauge, which is on the inlet side of the regulator, is graduated from 0 to 3000 psi. The low or working pressure gauge, which is on the outlet side of the regulator, is graduated from 0 to 500 psi.

A single stage oxygen regulator consists of a flexible diaphragm, which controls a needle valve between the high pressure zone and the working zone, a compression spring, and an adjusting screw, which compensates for the pressure of the gas against the diaphragm. The needle valve is on the side of the dia-phragm exposed to high gas pressure while the compression spring and adjust-ing screw are on the opposite side in a zone vented to the atmosphere.

The oxygen enters the regulator through the high pressure inlet connection and passes through a glass wool filter, which removes dust and dirt. The seat, which closes off the nozzle, is not raised until the adjusting screw is turned in. Pressure is applied to the adjusting spring by turning the adjusting screw, which bears down on the rubber diaphragm. The diaphragm presses downward on the stirrup and overcomes the pressure on the compensating spring. When the stir-rup is forced downward, the passage through the nozzle is open. Oxygen is then allowed to flow into the low pressure chamber of the regulator. The oxygen then passes through the regulator outlet and the hose to the torch. A certain set pres-sure must be maintained in the low pressure chamber of the regulator so that oxygen will continue to be forced through the orifices of the torch, even if the torch needle valve is open. This pressure is indicated on the working pressure gauge of the regulator, and depends on the position of the regulator adjusting screw. Pressure is increased by turning the adjusting screw to the right and de-creased by turning this screw to the left.

Regulators used at stations to which gases are piped from an oxygen mani-fold, acetylene manifold, or acetylene generator have only one low pressure gauge because the pipe line pressures are usually set at 15 psi (103.4 kPa) for acetylene and approximately 200 psi (1379 kPa) for oxygen. The two stage oxy-gen regulator is similar in operation to the one stage regulator, but reduces pres-sure in two steps. On the high pressure side, the pressure is reduced from cylin-der pressure to intermediate pressure. On the low pressure side the pressure is reduced from intermediate pressure to work pressure. Because of the two stage pressure control, the working pressure is held constant, and pressure adjustment during welding operations is not required.

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VOCABULARY nonflammable – невоспламеняю-щийся, негорючий discoloration – обесцвечивание, потеря цвета liquid air process – сжижение воз-духа electrolytic process = electrolysis – электролиз combustibles – горючие вещества air tools – пневматический инст-рументы removable metal cap – съемный ме-таллический колпачок plate of steel – стальной лист to heat-treat – закаливать, подвер-гать тепловой обработке extensive testing – усиленный / многосторонний контроль regulator – редуктор

single/two-stage regulator – одно / двухкамерный редуктор flashback – обратный удар пламе-ни (в шланг или баллон) to close off – перекрыть, отклю-чить diaphragm – мембрана balancing / compensating spring – уравновешивающая пружина (ре-дуктора) relief valve – предохранительный / разгрузочный клапан compression spring – нажимная пружина vented – имеющий выход glass wool filter – фильтр из стек-ловолокна to bear down – передаваться stirrup – хомут, скоба set pressure – заданное давление


словосочетаний: 1) газ без вкуса и запаха; 2) в промышленных масшта-бах; 3) сжижение воздуха; 4) очищать газ; 5) самопроизвольно воспламе-няться; 6) пневматические инструменты; 7) емкость; 8) плавкий предохра-нитель; 9) однокамерный редуктор; 10) подавать на горелку постоянный объем газа.

II. Дайте русские эквиваленты следующих слов и словосочетаний:

1) to support combustion; 2) positive terminal; 3) to compress gas; 4) hose appa-ratus; 5) grease; 6) relief valve; 7) to adjust working pressure at intervals; 8) high pressure gauge; 9) to graduate the pressure gauge; 10) to compensate for the pressure.

III. Переведите на АЯ следующие предложения. 1. При электролизе вода под действием проходящего через нее элек-

трического тока распадается на кислород и водород. 2. Редукторы снижают давление до рабочего и регулируют поступление газа на выходе из балло-на. 3. Редуктор автоматически подает на горелку постоянный объем газа при установленном рабочем давлении. 4. Газ, поступающий в редуктор,

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поддерживает постоянное рабочее давление, независимо от давления в баллонах. 5. Редуктор имеет клапан, управляющий гибкой мембраной, на которую с одной стороны действует сила пружины, а с другой – давление газа. 6. В однокамерном редукторе снижение давления газа до рабочего происходит в один этап, когда газ проходит через зазор между седлом и клапаном. 7. Фильтр из стекловолокна очищает газ от пыли и грязи. 8. Мембрана давит вниз на хомут, сопротивляясь давлению уравновеши-вающей пружины. 9. Давление увеличивают поворотом регулирующего винта вправо, а уменьшают поворотом влево. 10. У редукторов на постах, к которым все газы подаются по разветвленным трубопроводам, есть только один манометр низкого давления.

Unit 49. ARC WELDING EQUIPMENT AND ACCESSORIES In electric welding processes, an arc is produced between an electrode and

the work piece (base metal). The arc is formed by passing a current between the electrode and the workpiece across the gap. The current melts the base metal and the electrode (if the electrode is a consumable type), creating a molten pool. On solidifying, the weld is formed. An alternate method employs a nonconsumable electrode, such as a tungsten rod. In this case, the weld is formed by melting and solidifying the base metal at the joint. In some instances, additional metal is re-quired and is added to the molten pool from a filler rod.

Electrical equipment required for arc welding depends on the source from which the electric power is obtained. If the power is obtained from public utility lines, one or more of the following devices are required: transformers (of which there are several types), rectifiers, motor generators, and control equipment. If public utility power is not available, portable generators driven by gasoline or diesel engines are used.

The direct current welding machine has a heavy duty direct current genera-tor. The generators are made in six standardized ratings for general purposes:

1) the machines rated 150 and 200 amperes, 30 volts, are used for light shielded metal-arc welding and for gas metal-arc welding. They are also used for general purpose job shop work;

2) the machines rated 200, 300, and 400 amperes, 40 volts, used for general welding purposes by machine or manual application;

3) machines rated 600 amperes, 40 volts, are used for submerged arc weld-ing and for carbon-arc welding.

The electric motors most commonly used to drive the welding generators are 220/440 volts, 3 phase, 60 cycle. The gasoline and diesel engines should have a rated horsepower in excess of the rated output of the generator. This will allow for the rated overload capacity of the generator and for the power required to operate the accessories of the engine. The simple equation HP = 1.25P/746

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can be used; HP is the engine horsepower and P is the generator rating in watts. For example, a 20 horsepower engine would be used to drive a welding genera-tor with a rated 12 kilowatt output.

In most direct current welding machines, the generator is of the variable voltage type, and is arranged so that the voltage is automatically adjusted to the demands of the arc. However, the voltage may be set manually with a rheostat. The welding current amperage is also manually adjustable, and is set by means of a selector switch or series of plug receptacles. In either case, the desired am-perage is obtained by tapping into the generator field coils. When both voltage and amperage of the welding machine are adjustable, the machine is known as dual control type. Welding machines are also manufactured in which current controls are maintained by movement of the brush assembly.

A maintenance schedule should be set up to keep the welding machine in good operating condition. The machine should be thoroughly inspected every 3 months and blown free of dust with clean, dry, compressed air. At least once each year, the contacts of the motor starter switches and the rheostat should be cleaned and replaced if necessary. Brushes should be inspected frequently to see if they are making proper contact on the commutator, and that they move freely in the brush holders. Clean the commutator with sandpaper if it is burned or roughened. Check the bearings twice a year. Remove all the old grease and re-place it with new grease.

Direct current rectifier type welding machines have been designed with copper oxide, silicon, or selenium dry plates. These machines usually consist of a transformer to reduce the power line voltage to the required 220/440 volts, 3 phase, 60 cycle input current; a reactor for adjustment of the current; and a recti-fier to change the alternating current to direct current. Sometimes another reac-tor is used to reduce ripple in the output current.

Most of the alternating current arc welding machines in use are of the sin-gle operator, static transformer type. For manual operation in industrial applica-tions, machines having 200, 300, and 400 ampere ratings are in general use. Ma-chines with 150 ampere ratings are sometimes used in light industrial, garage and job shop welding.

The transformers are generally equipped with arc stabilizing capacitors. Current control is provided in several ways. One such method is by means of an adjustable reactor in the output circuit of the transformer. In other types, internal reactions of the transformer are adjustable. A hand-wheel, usually installed on the front or the top of the machine, makes continuous adjustment of the output current, without steps, possible.

The screws and bearings on machines with screw type adjustments should be lubricated every 3 months. The same lubrication schedule applies to chain drives.

Contacts, switches, relays, and plug and jack connections should be in-spected every 3 months and cleaned or replaced as required. The primary input

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current at no load should be measured and checked once a year to ensure the power factor connecting capacitors are working, and that input current is as specified on the nameplate or in the manufacturer’s instruction book.

VOCABULARY

public utility line – сеть общего пользования, коммунальные ли-нии to be driven by – работать на, при-водиться в действие heavy duty – рассчитанный на большие нагрузки welding machine – сварочный ав-томат 3-phase – трехфазный standardized rating – стандартная производительность, мощность 60 cycle – с частотой колебаний 60 герц rated output – номинальная мощ-ность rated horsepower – мощность в ло-шадиных силах overload capacity – способность выдерживать перегрузку accessories – приспособления, до-полнительное оборудование rheostat – реостат, устройство для регулирования напряжения и тока в цепи amperage – сила тока selector switch – селекторный пе-реключатель plug receptacle – штепсельная ро-зетка

to tap into – подключаться к field coils – катушка электромаг-нита dual control type – с двойным регу-лированием current control – регулятор / кон-троллер тока brush assembly – комплект щеток to blow free – продувать motor starter switch – переключа-тель стартера двигателя commutator – коммутатор, пере-ключатель to check bearings – проверять пока-зания direct current rectifier type welding machine – сварочный автомат с выпрямителем dry plate – обкладка конденсатора input current – ток на входе, под-водимая мощность reactor – дроссель, стабилизатор ripple – небольшая пульсация arc stabilizing capacitor – конденса-тор стабилизации дуги screw type adjustment – регулиров-ка с помощью винта chain drive – цепной привод primary input current – ток, пода-ваемый на входную катушку


словосочетаний: 1) образовать сварочную ванну; 2) выпрямитель; 3) ра-ботать на бензине; 4) стандартная производительность; 5) рассчитанный на напряжение 220 вольт; 6) номинальная мощность; 7) использовать допол-нительные приспособления; 8) регулируемое напряжение; 9) регулировать

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вручную; 10) подключить к катушке электромагнита генератора; 11) гра-фик техосмотра; 12) контакт с переключателем; 13) проверять / снимать показания; 14) смазывать; 15) реле.

II. Переведите на АЯ следующие слова и словосочетания: 1) to em-

ploy non-consumable electrodes; 2) filler rod; 3) public utility line; 4) general purpose shop work; 5) shielded metal arc welding; 6) submerged arc welding; 7) rated overload capacity; 8) direct current welding machine; 9) demands of the arc; 10) dual control type; 11) alternating current arc welding machine; 12) stabi-lizing capacitor; 13) internal reactions; jack connection; 14) screws and bearings.

III. Переведите на АЯ следующие предложения. 1. Электрическая дуга возникает за счет дугового разряда в зазоре ме-

жду электродом и свариваемым металлом. 2. Дуговая сварка выполняется как плавящимися, так и неплавящимися электродами. 3. Для обеспечения устойчивой дуги используют различные трансформаторы, выпрямители и генераторы. 4. Регулирование дуги при ее случайных отклонениях дости-гается за счет изменения скорости плавления электрода: при уменьшении длины дуги ток автоматически повышается и скорость плавления электро-да возрастает. 5. Сварочный трансформатор предназначен для создания ус-тойчивой электрической дуги. 6. Проходя через первичную обмотку трансформатора, переменный ток намагничивает сердечник и создает в нем переменный магнитный поток. 7. Используемые сварочные автоматы, работающие на переменном токе, относятся к стационарному типу и пред-назначены для работы одного сварщика. 8. Если сварочное оборудование получает энергию от сети общего назначения, необходимо использовать трансформаторы, выпрямители и другое оборудование. 9. Сварочные вы-прямители могут использоваться как при ручной дуговой сварке, так и при дуговой сварке плавящимся электродом в защитной среде. 10. Сварочное оборудование подключают к электрической сети только через коммутаци-онные аппараты, обеспечивающие необходимую степень защиты. 11. В комплект сварочного оборудования входят необходимые принадлежности: электродержатель, зажим для присоединения провода к изделию, свароч-ные провода необходимой длины, рассчитанные на всю зону обслужива-ния, защитный щиток и др. 12. В большинстве сварочных автоматов, рабо-тающих на постоянном токе, генератор имеет регулируемое напряжение, которое автоматически настраивается в соответствии с изменением дуги.

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Unit 50. GAS METAL ARC WELDING (GMAW) EQUIPMENT GMAW is most commonly referred to as “MIG” welding, and the follow-

ing text will use “MIG” or “MIG welding” when referring to GMAW. MIG welding is a process in which a consumable, bare wire electrode is fed into a weld at a controlled rate of speed, while a blanket of inert argon gas shields the weld zone from atmospheric contamination. In addition to the three basic types of metal transfer which characterize the GMAW process, there are several varia-tions of significance.

(1) Pulsed spray welding. Pulsed spray welding is a variation of the MIG welding process that is capable of all–position welding at higher energy levels than short circuiting arc welding. The power source provides two current levels; a steady “background” level, which is too low to produce spray transfer; and a “pulsed peak” current, which is superimposed upon the background current at a regulated interval. The pulse peak is well above the transition current, and usu-ally one drop is transferred during each pulse. The combination of the two levels of current produces a steady arc with axial spray transfer at effective welding currents below those required for conventional spray arc welding. Because the heat input is lower, this variation in operation is capable of welding thinner sec-tions than are practical with the conventional spray transfer.

(2) Arc spot welding. Gas metal arc spot welding is a method of joining similar to resistance spot welding and riveting. A variation of continuous gas metal arc welding, the process fuses two pieces of sheet metal together by pene-trating entirely through one piece into the other. No joint preparation is required other than cleaning of the overlap areas. The welding gun remains stationary while a spot weld is being made. Mild steel, stainless steel, and aluminum are commonly joined by this method.

(3) Electrogas welding. The electrogas (EG) variation of the MIG welding process is a fully automatic, high deposition rate method for the welding of butt, corner, and T-joints in the vertical position. The electrogas variation essentially combines the mechanical features of electroslag welding (ESW) with the MIG welding process. Water-cooled copper shoes span the gap between the pieces being welded to form a cavity for the molten metal. A carriage is mounted on a vertical column; this combination provides both vertical and horizontal move-ment. Welding head, controls, and electrode spools are mounted on the carriage. Both the carriage and the copper shoes move vertically upwards as welding pro-gresses. The welding head may also be oscillated to provide uniform distribution of heat and filler metal. This method is capable of welding metal sections of from 1/2 in. (13 mm) to more than 2 in. in thickness in a single pass.

Different types of MIG welding equipment are available through normal supply channels. Manuals for each type must be consulted prior to welding op-erations.

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The MIG welding unit is designed for manual welding with small diameter wire electrodes, using a Spool-on-gun torch. The unit consists of a torch, a voltage control box, and a welding contractor. The torch handle contains a device that pulls the welding wire electrode from a 4 in. (102 mm) diameter spool containing 1 lb (0.5 kg) of wire electrode mounted in the rear of the torch.

Three basic sizes of wire electrode may be used: 3/32 in. (2.38 mm), 3/64 in. (1.19 mm), and 1/16 in. (1.59 mm). Many types of metal may be welded provided the welding wire electrode is of the same composition as the base metal.

The unit is designed for use with an ac-dc conventional, constant-current welding power supply. Gasoline engine-driven arc welding machines issued to field units may be used as both a power source and a welding source.

Nomenclature of a torch 1. A contact tube is made of copper and has a hole in the center of the tube

that is from 0.01 to 0.02 in. (0.25 to 0.51 mm) larger than the size of the wire elec-trode being used. The contact tube and the inlet and outlet guide bushings must be changed when the size of the wire electrode is changed . The contact tube transfers power from the electrode cable to the welding wire electrode. An insulated lock screw is provided which secures the contact tube in the torch.

2. The nozzle is made of copper to dissipate heat and is chrome-plated to re-flect the heat. The holder is made of stainless steel and is connected to an insulating material which prevents an arc from being drawn between the nozzle and the ground in case the gun comes in contact with the work.

3. Inlet and outlet guide bushings. They must be changed to suit the wire elec-trode size. Pressure roll assembly is a smooth roller, under spring tension, which pushes the wire electrode against the feed roll and allows the wire to be pulled from the spool. A thumbscrew applies tension as required.

4. Motor. When the inch button is depressed, the current for running the motor comes from the 110 V ac-dc source, and the rotor pulls the wire electrode from the spool before starting the welding operation. When the trigger is depressed, the ac-tual welding operation starts and the motor pulls the electrode from the spool at the required rate of feed. The current for this rotor is supplied by the welding genera-tor.

5. Spool enclosure assembly is made of plastic. It prevents arc spatter from jamming the wire electrode on the spool. A small window allows the operator to visually check the amount of wire electrode remaining on the spool. If for any rea-son the wire electrode stops feeding, a burn-back will result. With the trigger de-pressed, the welding contactor is closed, thereby allowing the welding current to flow through the contact tube. As long as the wire electrode advances through the tube, an arc will be drawn at the end of the wire electrode. Should the wire elec-trode stop feeding while the trigger is still being depressed, the arc will then form at the end of the contact tube, causing it to melt off. This is called burn-back.

6. Welding contactor. The positive cable from the dc welding generator is connected to a cable coming out of the welding contactor, and the ground cable is connected to the workpiece. The electrode cable and the welding contactor cable are connected between the welding contactor and voltage control box.

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7. Argon gas hose is connected from the voltage control box to the argon gas regulator on the argon cylinder.

8. The electrode cable enters through the welding current relay and connects into the argon supply line. Both then go out of the voltage control box and into the torch in one line.

9. Voltage pickup cable (this cable must be attached to the ground cable at the workpiece. It supplies the current to the motor during welding when the trigger is depressed.

10. Torch switch and grounding cables. The torch switch cable is connected into the voltage control box, and the torch grounding cable is connected to the case of the voltage control box.

VOCABULARY

pulsed spray welding – импульсная сварка распылением background level current – базовый ток pulsed peak current – ток при наи-большей величине импульса pulse – импульс transition current – ток, при котором осуществляется перенос conventional spray arc welding – тра-диционная дуговая сварка распы-лением axial spray transfer – аксиальный струйный перенос effective welding current – эффек-тивное значение сварочного тока riveting – клепка joint preparation – разделка, подго-товка соединения под сварку welding gun – сварочный пистолет electrogas welding – электрогазовая сварка high deposition rate method – метод, обеспечивающий высокую ско-рость наплавки electroslag welding – электрошлако-вая сварка copper shoes – медные ползуны carriage – рама, несущая конструкция

oscillate – отклоняться, колебаться spool-on-the-gun torch – горелка с закрепленной на ней катушкой a voltage control box – пульт регу-лирования напряжения welding contactor – сварочный замы-катель, контактор сварочной цепи field unit – автономная установка guide bushing – направляющая втулка insulated lock screw – изолирован-ный стопорный винт, винт-ограничитель pressure roll assembly – узел при-жимного ролика feed roll – подающий ролик contact tube – трубчатый токоподвод thumbscrew – винт-барашек, винт с накатанной головкой inch button – кнопка управления импульсным продвижением trigger – пускатель spool enclosure assembly – узел ог-раждения катушки arc spatter – брызги металла burn-back – переход дуги с электро-да на токоподвод мундштука voltage pick up cable – кабель под-держки напряжения

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выражений: 1) регулируемая скорость; 2) вредное воздействие газов ат-мосферы; 3) сварка во всех положениях; 4) традиционная дуговая сварка; 5) оставаться неподвижным; 6) электрошлаковая сварка; 7) заполнять за-зор; 8) двигатель, работающий на бензине; 9) перечень деталей горелки; 10) стопорный винт, покрытый изоляцией; 11) направляющая втулка; 12) отклоняться к мундштуку; 13) затор проволочного электрода; 14) при нажатом пускателе; 15) сварочный генератор постоянного тока

II. Переведите на АЯ следующие слова и словосочетания: 1) a blan-

ket of inert gas; 2) metal transfer; 3) pulsed spray welding; 4) to superimpose; 5) effective current; 6) resistance welding; 7) butt joint; 8) a voltage control box; 9) ac-dc conventional, constant current welding power supply; 10) field unit; 11) under spring tension; 12) when the inch button is depressed; 13) spool enclo-sure assembly; 14) the welding contactor cable; 15) the welding current relay.

Unit 51. ELECTRODES AND THEIR USE When molten metal is exposed to air, it absorbs oxygen and nitrogen, and

becomes brittle or is otherwise adversely affected. A slag cover is needed to pro-tect molten or solidifying weld metal from the atmosphere. This cover can be obtained from the electrode coating, which protects the metal from damage, sta-bilizes the arc, and improves the weld in many ways.

The metal-arc electrodes may be grouped and classified as bare electrodes, light coated electrodes, and shielding arc or heavy coated electrodes. The type used depends on the specific properties required in the weld deposited. These include corrosion resistance, ductility, high tensile strength, the type of base metal to be welded; the position of the weld (i.e., flat, horizontal, vertical, or overhead); and the type of current and polarity required.

Bare electrodes are made of wire compositions required for specific appli-cations. These electrodes have no coatings other than those required in wire drawing. These wire drawing coatings have some slight stabilizing effect on the arc but are otherwise of no consequence. Bare electrodes are used for welding manganese steel and other purposes where a coated electrode is not required or is undesirable.

Light coated electrodes have a definite composition. A light coating has been applied on the surface by washing, dipping, brushing, spraying, tumbling, or wiping to improve the stability and characteristics of the arc stream. The coat-ing generally serves the following functions:

a) it dissolves or reduces impurities such as oxides, sulfur, and phosphorus;

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b) it changes the surface tension of the molten metal so that the globules of metal leaving the end of the electrode are smaller and more frequent, making the flow of molten metal more uniform;

c) it increases the arc stability by introducing materials readily ionized (i.e., changed into small particles with an electric charge) into the arc stream.

Some of the light coatings may produce a slag, but it is quite thin and does not act in the same manner as the shielded arc electrode type slag.

Shielded arc or heavy coated electrodes have a definite composition on which a coating has been applied by dipping or extrusion. The electrodes are manufactured in three general types: those with cellulose coatings; those with mineral coatings; and those with coatings of combinations of mineral and cellu-lose. The cellulose coatings are composed of soluble cotton or other forms of cellulose with small amounts of potassium, sodium, or titanium, and in some cases added minerals. The mineral coatings consist of sodium silicate, metallic oxides, clay, and other inorganic substances or combinations thereof. Cellulose coated electrodes protect the molten metal with a gaseous zone around the arc as well as slag deposit over the weld zone. The mineral coated electrode forms a slag deposit only. The shielded arc or heavy coated electrodes are used for weld-ing steels, cast iron, and hard surfacing.

Functions of Shielded Arc or Heavy Coated Electrodes. (1) These electrodes produce a reducing gas shield around the arc which

prevents atmospheric oxygen or nitrogen from contaminating the weld metal. The oxygen would readily combine with the molten metal, removing alloying elements and causing porosity. The nitrogen would cause brittleness, low ductil-ity, and in some cases, low strength and poor resistance to corrosion.

(2) The electrodes reduce impurities such as oxides, sulfur, and phosphorus so that these impurities will not impair the weld deposit.

(3) They provide substances to the arc which increase its stability and eliminate wide fluctuations in the voltage so that the arc can be maintained without excessive spattering.

(4) By reducing the attractive force between the molten metal and the end of the electrode, or by reducing the surface tension of the molten metal, the va-porized and melted coating causes the molten metal at the end of the electrode to break up into fine, small particles.

(5) The coatings contain silicates which will form a slag over the molten weld and base metal. Since the slag solidifies at a relatively slow rate, it holds the heat and allows the underlying metal to cool and slowly solidify. This slow solidification of the metal eliminates the entrapment of gases within the weld and permits solid impurities to float to the surface. Slow cooling also has an an-nealing effect on the weld deposit.

(6) The physical characteristics of the weld deposit are modified by incor-porating alloying materials in the electrode coating. The fluxing action of the

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slag will also produce weld metal of better quality and permit welding at higher speeds.

(7) The coating insulates the sides of the electrode so that the arc is concen-trated into a confined area. This facilitates welding in a deep U or V groove.

(8) The coating acts as a shield, concentrates and directs the arc, reduces heat losses and increases the temperature at the end of the electrode.

Electrodes must be kept dry. Moisture destroys the desirable characteristics of the coating, may cause excessive spattering and lead to the formation of cracks in the welded area. Electrodes exposed to damp air for more than two or three hours should be dried by heating in a suitable oven for two hours at 500 оF (260 оC). After they have dried, they should be stored in a moisture proof con-tainer. Bending the electrode can cause the coating to break loose from the core wire. Electrodes should not be used if the core wire is exposed.

VOCABULARY

shielded arc electrode – электрод с толстым защитным покрытием bare electrode – голый электрод, электрод без покрытия light-coated electrode – электрод с тонким покрытием ductility – пластичность dipping – окунание, нанесение по-крытия способом окунания

wire drawing – волочение прово-локи tumbling – очистка в барабане, галтование globule – шарик, глобула extrusion – нанесение покрытия методом опрессовки reducing gas shield – восстанавли-вающая газовая защита entrapment – удерживание (газов)


словосочетаний: 1) устойчивость к коррозии; 2) электрод с толстым по-крытием; 3) потолочное положение (шва); 4) наносить покрытие; 5) про-мывка; 6) поверхностное натяжение; 7) структура электрода; 8) углекис-лый калий, поташ; 9) слой шлака; 10) низкая прочность; 11) сила притяже-ния; 12) добавлять / включать присадки; 13) благодаря тому, что шлак дей-ствует как флюс; 14) изолировать; 15) разделка со скосом двух кромок.

II. Переведите на АЯ следующие слова и словосочетания: 1) to af-

fect adversely; 2) metal arc electrode; 3) high tensile stress; 4) wire drawing coating; 5) materials readily ionized; 6) soluble cotton cellulose; 7) sodium; 8) reducing gas shield; 9) resistance to corrosion; 10) to impair the weld deposit; 11) annealing effect; 12) weld deposit; 13) oven; 14) moisture-proof container; 15) if the core wire is exposed.

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Unit 52. TUNGSTEN ELECTRODES

Nonconsumable electrodes for gas tungsten-arc (TIG) welding are of three types: pure tungsten, tungsten containing 1 or 2 percent thorium, and tungsten con-taining 0.3 to 0.5 percent zirconium.

Tungsten electrodes can be identified by painted end marks as follows: a) green – pure tungsten; b) yellow – 1 percent thorium; c) red – 2 percent thorium; d) brown – 0.3 to 0.5 percent zirconium. Pure tungsten (99.5 percent tungsten) electrodes are generally used on less

critical welding operations than the tungstens which are alloyed. This type of elec-trode has a relatively low current-carrying capacity and a low resistance to con-tamination.

Thoriated tungsten electrodes (1 or 2 percent thorium) are superior to pure tungsten electrodes because of their higher electron output, better arc-starting and arc stability, high current-carrying capacity, longer life, and greater resistance to contamination.

Tungsten electrodes, containing 0.3 to 0.5 percent zirconium, generally fall between pure tungsten electrodes and thoriated tungsten electrodes in terms of per-formance. There is, however, some indication of better performance in certain types of welding using ac power.

Finer arc control can be obtained if the tungsten alloyed electrode is ground to a point. When electrodes are not ground, they must be operated at maximum current density to obtain reasonable arc stability. Tungsten electrode points are difficult to maintain if standard direct current equipment is used as a power source and touch-starting of the arc is standard practice. Maintenance of electrode shape and the reduc-tion of tungsten inclusions in the weld can best be accomplished by superimposing a high-frequency current on the regular welding current. Tungsten electrodes alloyed with thorium and zirconium retain their shape longer when touch-starting is used.

The electrode extension beyond the gas cup is determined by the type of the joint being welded. For example, an extension beyond the gas cup of 1/8 in. (3.2 mm) might be used for butt joints in light gauge material, while an extension of ap-proximately 1/4 to 1/2 in. (6.4 to 12.7 mm) might be necessary on some fillet welds. The tungsten electrode of torch should be inclined slightly and the filler metal added carefully to avoid contact with the tungsten. This will prevent con-tamination of the electrode. If contamination does occur, the electrode must be re-moved, reground, and replaced in the torch.

In direct current welding, the welding current circuit may be hooked up as ei-ther straight polarity (dcsp) or reverse polarity (dcrp). The polarity recommended for use with a specific type of electrode is established by the manufacturer.

For dcsp, the welding machine connections are electrode negative and work-piece positive (the electron flow is from electrode to workpiece). For dcrp, the welding machine connections are electrode-positive and workpiece-negative; the electron flow is from workpiece to electrode.

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For both current polarities, the greatest part of the heating effect occurs at the positive side of the arc. Thus, for any given welding current, dcrp requires a larger diameter electrode than does dcsp. For example, a l/16-in. (1.6-mm) diameter pure tungsten electrode can handle 125 amperes of welding current under straight polar-ity conditions. If the polarity were reversed, however, this amount of current would melt off the electrode and contaminate the weld metal. Hence, a 1/4-in. (6.4-mm) diameter pure tungsten electrode is required to handle 125 amperes dcrp satisfacto-rily and safely. However, when heavy coated electrodes are used, the composition of the coating and the gases it produces may alter the heat conditions. This will produce greater heat on the negative side of the arc. One type of coating may pro-vide the most desirable heat balance with straight polarity, while another type of coating on the same electrode may provide a more desirable heat balance with re-verse polarity.

The different heating effects influence not only the welding action, but also the shape of the weld obtained. DCSP welding will produce a wide, relatively shal-low weld. DCRP welding, because of the larger electrode diameter and lower cur-rents generally employed, gives a narrow, deep weld.

One other effect of dcrp welding is the so-called plate cleaning effect. This surface cleaning action is caused either by the electrons leaving the plate or by the impact of the gas ions striking the plate, which tends to break up the surface oxides and dirt usually present.

In general, straight polarity is used with all mild steel, bare, or light coated electrodes. Reverse polarity is used in the welding of non-ferrous metals such as aluminum, bronze, monel, and nickel. Reverse polarity is also used with some types of electrodes for making vertical and overhead welds.

The proper polarity for a given electrode can be recognized by the sharp, cracking sound of the arc. The wrong polarity will cause the arc to emit a hissing sound, and the welding bead will be difficult to control.

VOCABULARY current-carrying capacity – допусти-мая нагрузка electron output – выработка элек-тронов gas cup – газовая «шапочка» less critical operations – менее ответ-ственные операции performance – рабочие характери-стики current density – плотность тока touch starting – возбуждение дуги light gauge material – легко соеди-няемые материалы superimpose – налагать, наклады-вать, перекрывать

electrode extension – вылет электро-да dcsp – direct current straight polarity – постоянный ток и прямая поляр-ность dcrp – direct current reverse polarity – постоянный ток и обратная поляр-ность gauge – зд. – сортамент (проволоки) (по маркам, размерам и др.) to hook up – включать в цепь monel – монель-металл (медно-никелевый сплав) plate cleaning effect – очищающее действие

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словосочетаний: 1) иметь больший срок эксплуатации; 2) переносить вы-сокую допустимую нагрузку; 3) иметь преимущества; 4) более точный кон-троль (регулирование) дуги; 5) попадание частиц вольфрама в шов; 6) на-ложение тока высокой частоты; 7) газовый пузырь; 8) загрязнение элек-трода; 9) схема сварочной цепи может иметь прямую полярность; 10) обычно занимают место между … ; 11) поддержание формы электрода; 12) влиять на процесс сварки; 13) разрушать поверхностные окислы; 14) потрескивание дуги.

II. Переведите на АЯ следующие слова и словосочетания: 1) resis-

tance to contamination; 2) in terms of performance; 3) touch starting; 4) elec-trode points are difficult to maintain; 5) the welding machine connections are electrode negative; 6) thoriated tungsten electrodes; 7) to grind to a point; 8) at maximum current density; 9) to superimpose a high frequency current on the regular welding current; 10) electrode extension; 11) plate cleaning effect; 12) to emit a hissing sound.

Unit 53. ELECTRODES AND THEIR USE IN AC/DC WELDING

Alternating current welding, theoretically, is a combination of dcsp and dcrp

welding: half of each complete alternating current (ac) cycle is dcsp, the other half is dcrp.

Moisture, oxides, scale, etc., on the surface of the plate tend, partially or com-pletely, to prevent the flow of current in the reverse polarity direction. This is called rectification. To prevent rectification from occurring, it is common practice to introduce into the welding current an additional high-voltage, high-frequency, low-power current. This high-frequency current jumps the gap between the elec-trode and the workpiece and pierces the oxide film, thereby forming a path for the welding current to follow. Superimposing this high-voltage, high-frequency current on the welding current gives a number of advantages: the arc may be started with-out touching the electrode to the workpiece; better arc stability is obtained; a longer arc is possible which is particularly useful in surfacing operations; welding elec-trodes have longer life; the use of wider current range for a specific diameter elec-trode is possible.

Direct Current Arc Welding Electrodes. The manufacturer’s recommendations should be followed when a specific

type of electrode is being used. In general, direct current shielded arc electrodes are designed either for reverse polarity (electrode positive) or for straight polarity (electrode negative), or both. Many, but not all, of the direct current electrodes can be used with alternating current. Direct current is preferred for many types of cov-

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ered, nonferrous, bare and alloy steel electrodes. Recommendations from the manu-facturer also include the type of base metal for which given electrodes are suited, corrections for poor fit-ups, and other specific conditions.

In most cases, straight polarity electrodes will provide less penetration than reverse polarity electrodes, and for this reason they will permit greater welding speed. Good penetration can be obtained from either proper welding conditions or arc manipulation.

Coated electrodes which can be used with either direct or alternating current are available. Alternating current is more desirable while welding in restricted areas or when using the high currents required for thick sections because it reduces arc blow. Arc blow causes blowholes, slag inclusions, and lack of fusion in the weld.

Alternating current is used in atomic hydrogen welding and in those carbon arc processes that require the use of two carbon electrodes. It permits a uniform rate of welding and electrode consumption. In carbon-arc processes where one carbon electrode is used, direct current straight polarity is recommended, because the elec-trode will be consumed at a lower rate.

If certain elements or oxides are present in electrode coatings, the arc stability will be affected. In bare electrodes, the composition and uniformity of the wire is an important factor in the control of arc stability. Thin or heavy coatings on the electrodes will completely remove the effects of defective wire.

Aluminum or aluminum oxide (even when present in 0.01 percent), silicon, silicon dioxide, and iron sulphate cause the arc to be unstable. Iron oxide, manga-nese oxide, calcium oxide, and iron sulphate tend to stabilize the arc.

When phosphorus or sulfur is present in the electrode in excess of 0.04 per-cent, they will impair the weld metal because they are transferred from the elec-trode to the molten metal with very little loss. Phosphorus causes grain growth, brittleness and “cold shortness” (i.e., brittle when below red heat) in the weld.

These defects increase in magnitude as the carbon content of the steel in-creases.

Sulfur acts as a slag, breaks up the soundness of the weld metal, and causes “hot shortness” (i.e., brittle when above red heat). Sulfur is particularly harmful to bare, low-carbon steel electrodes with a low manganese content. Manganese pro-motes formation of sound welds.

VOCABULARY

scale – окалина, окисная пленка rectification – выпрямление тока poor fit-up – плохая сборка (соеди-нения под сварку) arc manipulation – управление дугой high current – ток большой величины blowhole – раковина, газовый пузырь atomic hydrogen welding – атомно-водородная сварка

lack of fusion – непровар grain growth – зернистость surfacing – нанесение покрытия, ме-таллизация cold shortness – хладоломкость to jump the gap – преодолеть зазор сarbon arc welding – дуговая сварка угольным электродом

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словосочетаний: 1) полный цикл переменного тока; 2) ток высокого на-пряжения; 3) наложить ток на … ; 4) обеспечить устойчивость дуги; 5) электрод определенного диаметра; 6) обратная полярность; 7) электрод с покрытием; 8) электрод из цветного металла; 9) шлаковые включения; 10) обеспечивать равномерную скорость сварки; 11) полностью устраняют воздействие дефектов сварки; 12) вызывают нестабильность дуги; 13) поч-ти полностью; 14) нарушать плотность шва.

II. Переведите на АЯ следующие слова и словосочетания: 1) to

jump the gap between the electrodes; 2) to form a path for the welding current; 3) surfacing operations; 4) welding electrodes have longer life; 5) the use of wider current range; 6) direct current shielded arc electrodes; 7) corrections for poor fit-ups; 8) straight polarity electrodes; 9) to permit greater welding speed; 10) in carbon arc processes; 11) the arc stability will be affected; 12) to impair the weld metal; 13) these defects increase in magnitude; 14) bare low carbon steel electrodes.

Unit 54. СВАРНЫЕ СОЕДИНЕНИЯ И ШВЫ Сварными называют неразъемные соединения, выполненные при по-

мощи сварки. Они могут быть стыковыми, угловыми, нахлесточными, тав-ровыми.

Угловое соединение состоит из двух элементов, расположенных под углом относительно друг друга и сваренных в месте примыкания их краев. Такие сварные соединения нашли широкое применение в строительной практике.

Нахлесточное соединение предусматривает наложение одного эле-мента на другой в одной плоскости с частичным перекрытием друг друга. Такие соединения чаще всего встречаются в строительно-монтажных ра-ботах, при сооружении ферм, резервуаров и др.

Тавровым называют соединение, в котором к плоскости одного эле-мента приложен торец другого соединения под определенным углом.

В сварное соединение входят сварной шов, зона термического влия-ния, то есть прилегающая к шву зона основного металла, в которой в ре-зультате термического действия сварки произошли изменения, и примы-кающие к ней участки основного металла.

Сварной шов представляет собой закристаллизовавшийся металл, ко-торый в процессе сварки находился в расплавленном состоянии.

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Необходимо разделение понятий сварной шов и сварное соединение, так как их роль в процессе сварки различна. Сварной шов как связующая часть соединяемых элементов определяет геометрическую форму, сплош-ность, прочность и другие свойства металла непосредственно в месте свар-ки. Свойства сварного соединения зависят от свойств металла самого шва и зоны термического влияния. Необходимо учитывать и некоторую часть ос-новного металла, прилегающую к зоне термического влияния и определяю-щую концентрацию напряжений в месте перехода от металла шва к основ-ному металлу и пластических деформаций в зоне термического влияния.

В отличие от соединений, сварные швы бывают стыковыми и угловы-ми. Стыковой – это сварной шов стыкового соединения, угловой – сварной шов углового, нахлесточного и таврового соединения.

Сварочные швы различают по количеству слоев наложения, ориента-ции их в пространстве, по длине и др. Если шов полностью охватывает со-единение, его называют сплошным. Если в пределах одного соединения шов разрывается, его называют прерывистым. Разновидностью прерыви-стого шва является прихваточный шов, который применяют для фиксации элементов относительно друг друга перед сваркой. Если сварочные швы накладывают один на другой, он называется многослойным.

По форме наружной поверхности сварочные швы могут быть плоски-ми, вогнутыми или выпуклыми. Форма сварочного шва оказывает влияние на его физико-механические свойства и на расход электродного металла, связанный с его формированием. Наиболее экономичны плоские и вогну-тые швы, которые к тому же лучше работают при динамических нагрузках, так как отсутствует резкий переход от основного металла к сварному шву. Чрезмерный наплыв выпуклых швов приводит к перерасходу электродного металла, а резкий переход от основного металла к сварному шву при кон-центрированных напряжениях может вызвать разрушение соединения. По-этому выпуклость на швах снимают механическим способом – фрезами, абразивными кругами и т.д.

Различают такие сварочные швы по их положению в пространстве, как нижние, горизонтальные, вертикальные и потолочные швы. Выполне-ние сварного шва в каждом из положений имеет свои особенности.

VOCABULARY

конструкция – assembly зона термическое влияние – heat affected zone / area сплошность – continuity связующая часть – a binding part непосредственно примыкающий – immediate

пластическая деформация – plastic distortion угловое соединение – corner joint стыковое соединение – butt joint нахлесточное соединение – over-lap joint тавровое соединение – T-joint торец – end face, butt

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располагаться – to be positioned размещать, выравнивать – to align плоскость – plane примыкать – adjoin под углом – at an angle монтаж – assembly угловой шов – fillet weld количество слоев наложения – number of layers сплошной шов – continuous weld прерывистый шов – intermittent weld прихваточный шов – tack weld относительно друг друга – in rela-tion to

многослойный шов – multi-bead weld расход металла – metal consump-tion чрезмерный наплыв – excessive roll вызывать разрушение – to cause fracture фрезерование – milling шлифовка абразивными кругами – grinding потолочное положение – overhead нижнее положение – downhand выпуклость – bulge

Упражнения. I. Найдите в тексте русские эквиваленты следующих слов и сло-

восочетаний: 1) a part of an assembly; 2) a heat affected zone; 3) adjacent; 4) heat effect of welding; 5) crystallized metal; 6) weld joint; 7) metal proper-ties; 8) immediate to … ; 9) concentration of tensions; 10) number of layers; 11) to partially overlap; 12) sharp transition; 13) to cover a joint; 14) continuous weld; 15) multi-bead weld.

II. Переведите на АЯ следующие слова и словосочетания: 1) плос-

кость; 2) относительно друг друга; 3) резервуар; 4) угловое соединение; 5) примыкать; 6) строительство; 7) располагаться; 8) угловой шов; 9) при-хваточный шов; 10) динамическая нагрузка; 11) выпуклый шов; 12) вогну-тый шов; 13) вызывать разрушения; 14) выполнять шов; 14) выпуклость; 15) пластические деформации.

Unit 55. ПОДГОТОВКА ДЕТАЛЕЙ К СВАРКЕ Детали, предназначенные для сварки, должны быть очищены от грязи,

масляных пятен и др. Особенно тщательную очистку следует выполнять в околошовной зоне, то есть любые посторонние частицы, загрязняющие сварочную ванну, могут отрицательно сказаться на качестве сварного со-единения. Кромки деталей стачивают под углом шлифовальной машинкой или напильником. Тип и угол разделки кромок определяют количество не-обходимого для заполнения разделки электродного металла, а зазор между ними зависит от толщины свариваемых деталей, марки материала, способа сварки и др. Минимальную величину зазора выдерживают при сварке без

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присадочного материала, то есть неплавящимся электродом. При сварке плавящимся электродом зазор обычно устанавливают в пределах 0–5 мм. Чем больше зазор, тем глубже проплавление свариваемых кромок.

Тип и угол разделки свариваемых кромок определяют количество не-обходимого для заполнения разделки электродного материала, а, следова-тельно, и производительность сварки. Наилучшее формирование сварочно-го шва обеспечивает Х-образная разделка кромок, которая позволяет уменьшить объем наплавленного металла в 1,6–1,7 раз. Такая разделка обеспечивает наименьшую деформацию после сварки и достаточную прочность шва. Для предотвращения образования прожогов и правильного формирования шва кромки после разделки притупляют.

Свариваемые детали совмещают между собой и плотно сжимают лю-бым доступным механическим способом. Чаще всего пользуются различ-ными тисков, струбцин, систем пазов и т.д. Сварка серийных деталей вы-полняется в приспособлениях, изготовленных по индивидуальным черте-жам. При автоматической сварке часто применяют манипуляторы, обеспе-чивающие высокую точность предварительной сборки.

Детали сборки располагают так, чтобы место сварочного шва было наиболее доступно для электрода. Небольшие по размеру детали следует надежно закрепить. Объемные металлические конструкции перед сваркой собирают согласно чертежу, временно закрепляют сопряжения и оконча-тельно совмещают соединяемые элементы. Детали листовых конструкций устанавливают в требуемое положение и фиксируют временными (жестки-ми и полужесткими) креплениями. Жесткие крепления – это прихватки, вы-полняемые дуговой сваркой длиной 50–100 мм через каждые 400–500 мм. Прихватки целесообразно накладывать с противоположной основному шву стороны, тогда они в процессе обработки корня шва будут удалены. При-хватки, накладываемые со стороны основного шва, следует перед сваркой тщательно зачистить и проверить, нет ли трещин и других дефектов.

После этого вновь собирают электрическую схему сварочного ком-плекса. Для этого к свариваемым деталям прикрепляют заземляющий за-жим, подсоединенный к отрицательной клемме сварочного аппарата. Ве-личину сварочного тока подбирают в соответствии с применяемым элек-тродом и устанавливают его в режиме холостого хода. После этого встав-ляют электрод в держатель и зажигают дугу.

VOCABULARY

околошовная зона – heat affected zone отрицательно сказаться – weaken кромка – edge стачивать напильником – file off

стачивать шлифовальной машин-кой – grind off разделка кромок – grooving наплавленный металл – added metal

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электродный металл для заполне-ния разделки – filler / added metal зазор – opening марка (материала) – brand количество электродного металла, необходимого для заполнения раз-делки – the quantity of the filler metal производительность сварки weld-ing output Х-образная разделка – double groove preparation деформация после сварки – post-weld distortion

притупление кромки – root facing прожог – burning through совмещать (детали) – to align тиски – vice струбцина – cramp по чертежам – from drawings манипулятор – positioner предварительная сборка – pre-welding fit-up жесткое крепление – rigid fixture прихватка – tack основной шов – principal weld корень шва – weld root зачистить шов – to dress the weld


восочетаний: 1) in the heat affected area; 2) to take off by a grinder; 3) the an-gle of grooving; 4) the opening; 5) the quantity of welding output; 6) to com-press tightly; 7) the least post welding distortion; 8) to root face the edges; 9) half rigid fixture; 10) principal weld.

II. Переведите на АЯ следующие слова и словосочетания: 1) под

углом; 2) металл для заполнения разделки; 3) неплавящийся электрод; 4) проплавление; 5) серийные детали; 6) прочность шва; 7) предотвратить образование прожогов; 8) совмещать детали между собой; 9) прихваточ-ный шов; 10) тщательно зачистить.

Unit 56. ГАЗОВАЯ СВАРКА Газовая, или газоплавильная сварка, относится к группе способов

сварки плавлением. Для осуществления процесса сварки применяют раз-ное горючее, соответственно различают сварку водородно-кислородную, бензино-кислородную и т.д. Преобладающее значение имеет ацетилено-кислородная сварка; другие виды имеют ограниченное применение. Суще-ственное отличие газовой сварки от дуговой сварки – более плавный и медленный нагрев металла. Это отличие сварочного газового пламени от сварочной дуги является в одних случаях недостатком, в других – пре-имуществом газового пламени. Газовая сварка применяется в основном для: 1) сталей малых толщин (0,2–5 мм); 2) цветных металлов; 3) металлов, требующих при сварке постепенного мягкого нагрева и замедленного ох-

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лаждения, например, многих инструментальных сталей; 4) металлов, тре-бующих подогрева при сварке, например, чугуна и некоторых сортов спе-циальных сталей; 5) для твердой пайки; 6) для некоторых видов наплавоч-ных работ.

Благодаря универсальности, сравнительной простоте и портативности оборудования газовая сварка весьма целесообразна для многих видов ре-монтных работ. Сравнительно медленный нагрев металла газовым пламе-нем быстро снижает производительность газовой сварки с увеличением толщины металла, и при толщине стали выше 8–10 мм газовая сварка обычно экономически невыгодна, хотя технически возможна сварка стали толщиной 30–40 мм. При замедленном нагреве разогревается большой объем основного металла, прилегающего к сварочной ванне, что, в свою очередь, вызывает значительные деформации (коробление) свариваемых изделий. Поэтому газовая сварка технически и экономически нецелесооб-разна для таких объектов, как строительные металлоконструкции, мосты, вагоны, корпуса судов, станины крупных машин и т.п.

Значительные деформации металла, возникающие при газовой варке, ограничивают возможности выбора рациональных форм сварных соедине-ний, поэтому при газовой сварке пользуются, как правило, лишь простей-шим стыковым соединением. Угловые швы и соединения нахлесточные и тавровые при газовой сварке используются лишь в случаях необходимости из-за затруднений, создаваемых значительными деформациями металла, свойственными этому виду сварки. Применяются стыковые соединения как без скоса кромок, без отбортовки и с отбортовкой кромок (особо удоб-ное соединение для газовой сварки), так и с одно- и двусторонним скосом кромок.

Горелку обычно регулируют для работы на нормальном пламени. Те-пловое воздействие пламени на металл зависит не только от мощности пламени, но и от угла наклона оси пламени к поверхности металла. Наибо-лее интенсивно действует пламя, когда его ось нормальна к поверхности металла. С уменьшением угла наклона тепловое действие пламени ослабе-вает и распределяется по большей площади. Таким образом, сварщик мо-жет плавно регулировать тепловое действие пламени на металл, делать пламя более мягким или жестким, меняя угол наклона пламени к поверх-ности изделия. С увеличением толщины металла увеличивают угол накло-на пламени и уменьшают его с уменьшением толщины металла.

Газовая сварка может производиться в нижнем, вертикальном и пото-лочном положениях. Используемые присадочные прутки имеют различный состав, соответственно характеру основного металла. Диаметр прутка вы-бирается в соответствии с толщиной основного металла.

Присадочная проволока для газовой сварки сталей применяется та же, что и для электродов при дуговой сварке.

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VOCABULARY газовая сварка – gas welding ацетилено-кислородная сварка – oxy-acetylene welding газовая сварка плавлением – gas fusion welding мягкий нагрев – mild heating инструментальная сталь – instru-mental steel подогрев при сварке – additional heating наплавка – building up универсальность – versatility целесообразный – expedient коробление, деформация – defor-mation, distortion технически возможный – techni-cally feasible невыгодный – uneconomical металлоконструкция – metal work, metal assembly станина машины – (big) machine frame

замедленный – slow перегрев – overheat, superheat зерно – grain укрупнение зерна – the rise of grain снижение – deterioration рациональный – efficient, rational скос кромок – bevel односторонний скос – single bevel двусторонний скос – double bevel без скоса – square bevel отбортовка – raised edge угол наклона пламени – flame angle тепловое воздействие пламени – heat effect of the flame нормальное пламя – balanced / normal flame плавно регулировать – smoothly adjust мягкое / жесткое пламя – soft / harsh flame присадочный пруток – filler stick


восочетаний: 1) various fuels can be used; 2) limited application; 3) metal heating; 4) versatility; 5) technically feasible; 6) inadvisable, inexpedient; 7) uneconomical; 8) construction metal works; 9) machine frame; 10) rise of coarse grain; 11) fillet weld; 12) flame power; 13) square joint; 14) to adjust the torch; 15) to get balanced flame.

II. Переведите на АЯ следующие слова и словосочетания: 1) пре-

обладающее значение; 2) недостаток; 3) цветные металлы; 4) подогрев; 5) неплавочные работы; 6) портативное оборудование; 7) производитель-ность; 8) вагон; 9) влечет за собой; 10) рациональные формы; 11) стыковое соединение; 12) нахлесточное соединение; 13) тавровое соединение; 14) плавно регулировать; 15) нижнее положение.

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Unit 57. КОНТАКТНАЯ ТОЧЕЧНАЯ СВАРКА Точечная сварка представляет собой процесс, в котором сочетается

расплавление металла и получение литой структуры сварного соединения с использованием значительного осадочного давления. После включения ток проходит от одного электрода к другому через металл деталей и разо-гревает металл больше всего в месте соприкосновения деталей. Разогрев поверхности металла под электродами при правильно проводимом процес-се незначителен, так как контакт «электрод – изделие» имеет сравнительно небольшое сопротивление вследствие мягкости и высокой электропровод-ности электродного металла, а сам электрод интенсивно охлаждается про-точной водой. Прохождение тока вызывает разогрев и расплавление ме-талла в зоне сварки, создающее ядро сварной точки, имеющее чечевицеоб-разную форму. Диаметр ядра сварной точки в обычных случаях имеет ве-личину 4–12 мм.

Давление должно быть достаточным для преодоления жесткости из-делия и осуществления необходимой пластической деформации, обеспечи-вающей соответствующую прочность сварной точки. Необходимое давле-ние быстро возрастает с увеличением толщины свариваемого металла. Давление осадки полностью передается электродами, имеющими неболь-шую рабочую поверхность, несущую значительную тепловую и электри-ческую нагрузку. При значительной толщине основного металла нагрузка электродов настолько велика, что срок их службы быстро сокращается. Поэтому точечная сварка применяется главным образом для металла не-большой толщины, не свыше 5–6 мм.

Диаметр ядра определяет прочность точки и зависит от диаметра ра-бочей поверхности электрода, толщины листов, давления, силы тока и времени его прохождения. При неправильно подобранном режиме сварки может не произойти достаточного плавления металла, и точка получится непроваренной. Когда ядро расплавляется, прилегающая к нему по окруж-ности зона металла находится в пластическом состоянии, ее плотно сжи-мает давление электродов. Давление создает уплотняющее кольцо пла-стичного металла, удерживающее жидкий металл ядра. При недостаточном давлении уплотняющее кольцо не может удержать жидкий металл ядра, и происходит внутренний выплеск металла в зазор между листами. С увели-чением времени прохождения тока диаметр и высота ядра растут. Чрез-мерное увеличение размеров ядра ослабляет его оболочку из нагретого твердого металла, и происходит сильное вмятие металла под электродами, ведущее к наружному выплеску жидкого металла и снижению прочности точки. После выключения тока начинается охлаждение и затвердевание расплавленного ядра точки. Кристаллизация жидкого металла происходит от поверхности ядра к его середине. При охлаждении и затвердевании объ-ем расплавленного металла ядра уменьшается. В результате в центральной

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части ядра может образоваться усадочная раковина, пористость и рыхлость металла. Чем толще металл, тем сильнее неблагоприятное влияние усадки и тем больше вероятность образования дефектов. Наиболее надежным спо-собом борьбы с ними является повышение рабочего давления, а также пе-реход на циклы сварки с проковкой.

Для точечной сварки загрязнения поверхности металла в зоне сварки должны быть предварительно тщательно удалены щетками, травлением в кислотах, опескоструиванием и т.д. Сборка под точечную сварку должна как можно точнее обеспечивать плотное прилегание деталей до сварки. Наличие зазора между деталями поглощает значительную часть давления электродов на деформацию деталей до плотного соприкосновения, дейст-вительное осадочное давление на точку становится недостаточным и полу-чается разброс прочности точек. Требования к точности сборки повыша-ются с увеличением толщины листов.

Различают так называемые мягкие и жесткие режимы точечной сварки. При мягких режимах пользуются умеренными силами тока, плотность тока на рабочей поверхности электрода обычно не превышает 100 а/мм. Для же-стких режимов плотности тока доходят при сварке стали до 120–300 а/мм2.

Мягкие режимы характеризуются большей продолжительностью вре-мени сварки, более плавным нагревом, уменьшенной мощностью сварки. К преимуществам мягких режимов относятся уменьшение мощности, по-требляемой из сети, уменьшение нагрузки сети, понижение мощности и стоимости необходимых контактных машин, уменьшение закалки зоны сварки. Жесткие режимы требуют машин повышенной мощности, увели-чивают максимальную загрузку сети. К преимуществам жестких режимов сварки относятся уменьшение времени сварки, повышение производитель-ности. Давление электродов обычно принимают в пределах 3–8 кГ/мм2.

Неправильно установленный режим сварки или нарушение техноло-гических требований может привести к разнообразным дефектам точечной сварки. Наиболее опасным дефектом является непровар, характеризую-щийся отсутствием литого ядра точки или малыми его размерами. Опас-ность непровара увеличивается тем, что он не всегда надежно обнаружива-ется внешним осмотром изделий при приемке. Могут встречаться также такие дефекты, как подплавление поверхности и прожог металла, глубокие вмятины на поверхности металла, раковины и пористость литого ядра.

VOCABULARY

высокая электропроводность – high electro-conductivity проточная вода – running water ядро сварной точки – button чечевицеобразная форма – lens-shaped, lentil-shaped

точечная сварка – spot welding свариваемость – weldability сварная точка – welded spot осадка – upsetting пластичный – plastic, ductile пластичность – plasticity, ductility

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прочность – strength контактная / рабочая поверхность электрода – electrode tip area срок службы (оборудования) – working / service life уплотняющее кольцо – sealing ring проковка – forging, post-welding upsetting внутренний выплеск металла – metal inside expulsion внешний выплеск металла – metal outside expulsion раковина, пора – inclusion, pore, air pocket усадочная раковина – shrink hole рыхлость металла – porosity борьба с дефектами – avoiding defects

осадочное давление – upsetting pressure утечка тока – current leakage / leak шунтировать – to by-pass полезное давление – effective pres-sure сварной узел – welded assembly травление – chemical cleaning опескоструивание – sand-blasting сборка под сварку – welding fit-up поглощать давление – absorb pres-sure закалка – hardening подплавление – slight surface melting отпуск – tempering термообработка для снятия на-пряжения – heat treatment to relieve stress


восочетаний: 1) cooled by running water; 2) make a lens / lentil-shaped but-ton; 3) at a considerable upsetting pressure; 4) secure appropriate strength of the welded spot; 5) electrodes with a small tip area; 6) the button lacks fusion; 7) a sealing ring of ductile metal; 8) too big button; 9) to recede the shell of heated hard metal; 10) alternation of welding and post welding upsetting cycles; 11) current leak; 12) to secure tight contact; 13) effective upsetting pressure; 14) it results in spots of various strength; 15) pressure ranges from 3 to 8.

II. Переведите на АЯ следующие слова и словосочетания: 1) в мес-

те соприкосновения; 2) правильно проводимый процесс; 3) проточная во-да; 4) плохая свариваемость; 5) диаметр ядра свариваемой точки; 6) полу-чить литую структуру; 7) необходимая пластическая деформация; 8) нахо-дится в пластическом состоянии; 9) жидкий металл; 10) происходит внут-ренний выплеск металла; 11) сильное вмятие металла; 12) усадочная рако-вина; 13) полезное давление; 14) сборка под точечную сварку; 15) непра-вильно установленный режим сварки.

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Unit 58. ДЕФЕКТЫ СВАРКИ Каждый производственный процесс предполагает определенные от-

клонения от требований технический норм. Если такие отклонения выхо-дят за пределы установленных допусков для конкретного изделия, это брак, дефект, который должен быть устранен. Если устранение дефекта невозможно, изделие не может быть принято к эксплуатации. В сварочном производстве результатом является правильно сваренное изделие, узел, конструкция. В изделиях, выполненных сваркой, дефекты различаются по месту их расположения и по причинам возникновения.

Причины возникновения дефектов связаны с неправильной подготов-кой и сборкой элементов, нарушением режима сварки, неисправностью оборудования, небрежностью и низкой квалификацией сварщика и други-ми нарушениями технологического процесса. К дефектам этой группы от-носятся:

несоответствие швов расчетным размерам; непровары; подрезы; прожоги; наплывы; незаваренные кратеры. Дефекты по причинам их возникновения связаны также с явлениями,

происходящими в процессе кристаллизации и формирования самой сва-рочной ванны и окончательного формирования шва. Это трещины в самом шве и в околошовной зоне, шлаковые включения, поры.

Дефекты по месту их расположения – это трещины и поры, выходя-щие на поверхность металла, непровары, прожоги, подрезы, наплывы. Они относятся к наружным дефектам и могут быть обнаружены внешним ос-мотром К внутренним дефектам относятся те же трещины, непровары, включения и поры, но находящиеся внутри шва и не выходящие на по-верхность. Их обнаруживают только методами неразрушающего контроля.

Следующая разновидность дефекта – неравномерность шва. Она по-является из-за неустойчивого режима сварки, неточного направления элек-трода. При автоматизированной сварке причиной дефектов являются коле-бания напряжения в сети, проскальзывание проволоки в подающих роли-ках, протекание жидкого металла в зазоры, неправильный угол наклона электрода.

Подрезы – это углубления в основном металле. Причина их возникно-вения – большой сварочный ток и длинная дуга. При выполнении угловых швов основной причиной возникновения подреза будет смещение электро-да в сторону вертикальной стенки. Суть в том, что при таком смещении электрода возникает сильный разогрев вертикальной стенки, металл там плавится раньше и стекает на горизонтальную полку, образуя наплывы.

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Непровар. Возникновение этого дефекта кроется в малом угле скоса свариваемых кромок и небольшом зазоре между ними. Загрязнение кромок тоже может быть причиной непроваров. При самом процессе сварки не-провар может стать следствием недостаточного сварочного тока, завышен-ной скорости сварки, неточного направления электродной проволоки.

Прожог (сквозное проплавление) возникает из-за большого тока при малых скоростях сварки, из-за наличия большого зазора между кромками. Наиболее часто прожоги образуются при выполнении первого прохода многослойного шва и при сварке тонкого металла. Если под свариваемый шов плохо поджата флюсовая подушка или медная подкладка, тоже может возникнуть прожог.

Наплыв представляет собой затекание жидкого металла непосредст-венно из сварочной ванны на кромки холодного основного металла. Наи-более часто наплывы возникают при сварке горизонтальных швов на вер-тикальных плоскостях. Обычные причины наплывов – большой сварочный ток, неправильный наклон электрода, излишне длинная дуга.

Трещины – самые опасные дефекты, так как создают резкую концен-трацию напряжений. Трещины появляются при сварке высокоуглероди-стых и легированных сталей в результате слишком быстрого охлаждения. Часто трещины образуются в сварных соединениях жестко закрепленных конструкций. Иногда трещины возникают при охлаждении сварных конст-рукций на воздухе. Они могут располагаться вдоль и поперек сварного со-единения, а также в основном металле, в местах сосредоточения швов, и приводить к разрушению сварной конструкции. Причинами образования трещин являются большие напряжения, возникающие в сварных соедине-ниях при сварке. На образование трещин влияет повышенное содержание серы и фосфора. Сера увеличивает склонность металла шва к образованию горячих трещин, а фосфор – холодных. Горячие трещины возникают в процессе кристаллизации металла шва, то есть при высоких температурах, а холодные – при относительно низких температурах (ниже 100–300 °С).

Кратеры образуются при обрыве дуги в виде углублений в застыв-шей сварочной ванне. Место кратера должно быть заварено. При автома-тической сварке шов обычно заканчивают на выводной планке, где и появ-ляется кратер.

Поры появляются вследствие того, что газы, растворенные в жидком металле, при быстром охлаждении шва не успевают выйти наружу и оста-ются в нем в виде пузырьков. Размер пор колеблется от нескольких мик-рометров до нескольких миллиметров. Обычная форма возникающих пор – сферическая. Причины образования пор: масло, краска, окалина, ржавчина, всякие другие загрязнения. Причиной может быть и использование сырых непросушенных электродов. Это же относится и к сырым флюсам и к при-месям в защитных газах. Излишне большая скорость сварки нарушает га-зовую защиту сварочной ванны, что тоже ведет к появлению пор. Поры

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появляются и при неверном выборе сварочной проволоки, особенно в том случае, если сварка осуществляется в углекислом газе.

Включения шлака в сварочном шве. Речь идет о неметаллических включениях (несколько миллиметров) в линиях шва. Формы включений могут быть самые разные. Обычно такие включения располагаются на гра-нице соединения основного металла с наплавленным. Причины возникно-вения шлаковых включений – грязь на кромках, малый сварочный ток и большая скорость сварки.

Несплавления. Это означает, что металл сварного шва не сплавился с ранее наплавленным металлом или не сплавляется с основным металлом. Причины – плохая зачистка свариваемых кромок, грязь, большая длина ду-ги, недостаточная сила тока, большая скорость сварки.

VOCABULARY

отклонение от нормы – departure from standard установленный допуск – accepted tolerance сварочный узел – welding assembly место расположения – location сборка (под сварку) – fit-up нарушение режима сварки – inap-propriate welding procedure наплыв – roll расчетный размер – calculated di-mensions / size незаваренный кратер – unfilled crater околошовная зона – weld area / zone неравномерный шов – irregular weld колебания напряжения в сети – voltage fluctuations in the mains проскальзывание проволоки – wire slip подающий ролик – feeding roll протекание металла – penetration of metal угол наклона электрода – work / electrode angle углубление – recess горизонтальная полка – horizontal plane

вертикальная стенка – vertical plane угол скоса кромок – amgle of bevel неточное направление – inaccurate direction загрязнение кромок – edge con-tamination корень шва – weld root входная выходная планка – en-trance / exit slip многослойный шов – multi-layer weld / multi-bead deposit резкая концентрация напряжений – abrupt stress concentration горячие трещины – hot / solidifica-tion cracks- задерживаться в чем-либо – to be trapped in smth свищ – air hole окалина – dross ржавчина – rust шлаковые включения – entrapped slag линия шва – weld line линия сварки – welding line несплавление – faulty fusion, lack of fusion

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восочетаний: 1) departure from standards; 2) accepted tolerances; 3) location and cause; 4) violation of technology; 5) calculated size; 6) external defects; 7) NDT; 8) irregular weld; 9) voltage fluctuations; 10) to detect defects; 11) to make fillet welds; 12) edge contamination; 13) penetration of molten metal from the weld pool; 14) abrupt stress concentration; 15) to cause destruction of the weld.

II. Переведите на АЯ следующие слова и словосочетания: 1) при-

нять к эксплуатации; 2) причина возникновения; 3) неразрушающие мето-ды контроля; 4) не успевают выйти наружу; 5) шлак; 6) слишком большой зазор; 7) при выполнении горизонтальных швов на вертикальной поверх-ности; 8) большой сварочный ток; 9) высокоуглеродистая сталь; 10) жестко закрепленная конструкция; 11) в местах сосредоточения швов; 12) склон-ность металла; 13) газы, растворенные в жидком металле; 14) не успевают выйти наружу; 15) пузырьки газа.

Unit 59. АВТОМАТИЧЕСКАЯ ДУГОВАЯ СВАРКА Автоматизация и механизация процесса дуговой электросварки может

быть признана одной из важнейших задач современной сварочной техни-ки. Ручная дуговая сварка слишком трудоемка, требует большого количе-ства квалифицированных кадров, сравнительно дорога и, естественно, не может обеспечить однородность продукции, а так как последующий кон-троль качества сварки затруднителен, недостаточно надежен и не всегда выполним, то доверие к качеству сварки снижается, и заведомо уменьша-ются допускаемые напряжения для сварных швов.

В автоматизации дуговой электросварки за последние годы достигну-ты такие успехи, что уже сейчас этот процесс может считаться одним из наиболее передовых и прогрессивных технологических процессов метал-лообработки.

Автоматизации хорошо поддаются все основные виды дуговой свар-ки. По степени механизации процесса различают автоматы и полуавтома-ты; в последних еще сохраняется значительная доля ручного труда.

Для осуществления автоматической сварки требуется целый комплекс машин, механизмов и приспособлений, составляющих автоматическую ус-тановку для дуговой сварки. Устройство, производящее зажигание дуги, подачу электродов по мере их сгорания и обеспечивающее устойчивое го-рение дуги, называется автоматической головкой для дуговой сварки, или дуговым автоматом. Наиболее важное промышленное значение имеют ав-

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томаты для сварки плавким металлическим электродом. Вместо отдельных коротких электродов, применяемых в процессе ручной сварки, при автома-тической сварке используется электродная проволока большой длины, в мотках или бухтах, сматываемая механизмом автомата и подаваемая в зону дуги по мере ее плавления.

Проволока подается через передаточный механизм и ведущие ролики небольшим приводным электродвигателем автомата. Пройдя ведущие роли-ки, а также часто и правильный механизм, устраняющий кривизну и придаю-щий сматываемой с бухты проволоке прямолинейность, она поступает в мундштук или токоподвод автомата, где прижимается к токоведущим контак-там и скользит по ним, проводя сварочный ток, питающий дугу. Расстояние от токоподводящих контактов до дуги невелико (несколько сантиметров), по-этому автомат работает как бы коротким непрерывно возобновляемым элек-тродом. Это является важным преимуществом автомата, так как уменьшается нагрев проволоки и создается возможность применения очень высоких плот-ностей тока в электродной проволоке без ее перегрева. Подача проволоки производится автоматически со скоростью ее плавления, поэтому длина дуги при сгорании проволоки остается приблизительно постоянной. Многие авто-маты также автоматически производят зажигание дуги в начале сварки и по-вторное зажигание при случайном обрыве в процессе работы. Регулирование процесса сварки в автомате может быть осуществлено различными путями. Например, можно связать скорость подачи электродной проволоки с напря-жением дуги и ее длиной. При нормальной длине дуги и нормальном ее на-пряжении автомат подает проволоку со скоростью, равной примерно скоро-сти ее плавления; при уменьшении длины дуги скорость подачи проволоки уменьшается, вследствие чего длина дуги и ее напряжение возрастают и ус-танавливаются их нормальные значения.

При случайном увеличении длины дуги скорость подачи проволоки воз-растает и длина дуги, а вместе с тем и ее напряжение уменьшаются до нор-мальной заданной величины.

При коротком замыкании, когда напряжение дуги падает почти до нуля, направление подачи электродов меняется, то есть электрод не подается впе-ред к основному металлу, а отдергивается назад, и конец электрода удаляется от основного металла. После включения автомата, когда конец электрода еще не касался изделия и дуга отсутствует, напряжение между электродом и изде-лием равно полному напряжению холостого хода источника тока. Это напря-жение выше нормального напряжения дуги, и потому электрод подается впе-ред, к изделию. После зажигания дуги начинается подача электрода вперед к изделию с изменениями скорости подачи соответственно напряжению дуги. Таким образом, длина дуги поддерживается автоматически постоянной с точ-ностью, недоступной для ручной сварки. Современные автоматы поддержи-вают напряжение дуги с точностью до 0,5 В, что соответствует точности под-держания длины дуги ± 0,2–0,3 мм.

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VOCABULARY автоматизация и механизация – automation and mechanization трудоемкий – labour consuming обеспечить однородность – guar-antee uniform product заведомо – wittingly металлообработка – metal working полуавтомат – semi-automatic ma-chine сварочная установка – welding set-up зажечь дугу – to start / to initiate / to fire the arc по мере их сгорания – according to their consumption обеспечить устойчивое горение дуги – to provide stable arcing автоматическая головка для дуго-вой сварки – an automatic (arc welding) head моток – bundle бухта – coil подавать проволоку – to feed the wire

сматывать проволоку – to wind the wire передаточный механизм – trans-mission, transfer device ведущий ролик – drive roller приводной механизм – driving mechanism / device электродвигатель – electric motor правильный механизм – straighten-ing device / liner кривизна – curvature токоподвод – current lead мундштук (для проволоки) – wire nozzle джоулево тепло – joule heat плотность тока – current density случайный обрыв дуги – chance arc extinction короткое замыкание – shortening холостой ход источника питания – no load / idling of the power source промежуток дуги – arc gap


восочетаний: 1) welding set-up; 2) to provide stable arcing; 3) metal working; 4) current leading contacts; 5) wire in bundles or coils; 6) liner; 7) wire heating; 8) the rate of wire feed; 9) at a normal arc length; 10) a chance arc length in-crease.

II. Переведите на АЯ следующие слова и словосочетания: 1) тру-

доемкий; 2) однородность продукции; 3) выполнимый; 4) ручной труд; 5) в соответствии с … ; 6) повторно зажигать дугу; 7) по мере плавления; 8) зо-на дуги; 9) приводной электродвигатель; 10) устранить кривизну проволо-ки; 11) плотность тока; 12) подавать автоматически; 13) при коротком за-мыкании; 14) до нормальной установки величины; 15) отдергивать электрод.

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Unit 60. ДУГОВОЙ АВТОМАТ Дуговой автомат представляет собой автоматический регулятор, под-

держивающий постоянство режима дуговой сварки по возможности неза-висимо от воздействия внешних и случайных возмущающих факторов.

В основу регулирования работы дугового автомата с плавящимся ме-таллическим электродом могут быть положены различные принципы. В настоящее время существует два основных вида дуговых автоматов с пла-вящимся электродом, различных по принципу регулирования: 1) автоматы с регулированием электрических величин; 2) автоматы с постоянной ско-ростью подачи электрода. В автоматах первого типа регулируемой являет-ся какая-либо электрическая величина сварочной дуги, регулирующей ве-личиной – скорость подачи электрода. Регулируемой величиной могут служить напряжение, ток или мощность дуги и т.д. В современных автома-тах за регулируемую величину принимают обычно напряжение дуги. В сварочной дуге напряжение практически не зависит от силы тока, а только от длины дуги, изменяясь пропорционально изменениям длины. При нали-чии автомата, поддерживающего постоянство напряжения дуги, длина ду-ги останется постоянной, и процесс сварки сохранит нормальный характер. Таким образом, регулирование постоянства напряжения дуги эквивалентно регулированию постоянства ее длины. На протяжении десятков лет дуго-вые автоматы для плавящегося электрода строились только с автоматиче-ским регулированием постоянства напряжения дуги. В.И. Дятлов впервые предложил новый принцип устройства дуговых автоматов для подачи электрода с постоянной скоростью, не зависящей от напряжения дуги или каких-либо других факторов. Он впервые обратил внимание на саморегу-лирование дуги при сварке плавящимся электродом, исследовал это явле-ние и предложил использовать его в дуговых автоматах. В ряде случаев саморегулирование дуги протекает настолько интенсивно, что нет необхо-димости в применении довольно сложных схем автоматического регули-рования дуги, достаточно непрерывно подавать электрод в дугу с постоян-ной скоростью, равной скорости его плавления. Саморегулирование дуги вызывается тем, что скорость плавления электрода изменяется с изменени-ем длины дуги: с увеличением длины дуги уменьшается скорость плавле-ния, с уменьшением длины дуги эта скорость увеличивается. При постоян-ной скорости подачи электрода случайное изменение длины дуги вызывает изменение скорости плавления электрода, направленное на восстановление первоначальной длины дуги.

На интенсивность процесса саморегулирования, помимо других факто-ров, наиболее сильное влияние оказывают плотность сварочного тока в элек-троде и форма внешней характеристики источника сварочного тока. При не-достаточных плотностях тока саморегулирование протекает так медленно, что начавшееся случайное укорочение дуги часто приводило к короткому за-

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мыканию, а удлинение – к обрыву дуги раньше, чем в процессе саморегули-рования успевала восстановиться нормальная длина дуги. С увеличением плотности тока быстро возрастает скорость плавления электродной проволо-ки и интенсивность процесса саморегулирования.

Дуговой автомат поддерживает горение дуги и подает электродную про-волоку. Для получения сварного шва необходимо перемещать дугу по линии сварки. В зависимости от способа перемещения дуги различают подвесные автоматы, самоходные автоматы и сварочные тракторы. Подвесной автомат не имеет механизма перемещения, оно производится отдельным устройством. Перемещаться может изделие при неподвижном автомате (так обычно вы-полняются круговые швы) или же автомат, установленный на самоходную тележку, вдоль изделия, например, при сварке длинных прямолинейных швов. Возможно и одновременное перемещение автомата и изделия, удобное при выполнении некоторых криволинейных швов. У самоходных автоматов имеется механизм перемещения, конструктивно объединенный с автоматом. Самоходный автомат перемещается по специальному рельсовому пути.

Сварочным трактором называется легкий компактный самоходный ав-томат, перемещающийся непосредственно по поверхности свариваемого из-делия или по легкому переносному рельсовому пути, укладываемому на по-верхность изделия. Сварочные тракторы особенно удобны для сварки изде-лий больших размеров, таких, как корпусы судов, крупные резервуары и т.п.

VOCABULARY

дуговой автомат – automatic welding machine постоянный режим – constant oper-ating conditions / mode внешний фактор – external charac-teristic / factor случайный фактор – accidental char-acteristic возмущающий фактор – disturbing characteristic принцип регулирования – principle of adjustment / control скорость подачи электрода – wire feed speed / rate мощность дуги – arc power сила тока – current автоматическое регулирование – automatic control / adjustment саморегулирование – inherent regu-lation / self-adjustment

постоянное напряжение дуги – arc steady voltage плотность тока current density короткое замыкание – short-circuit режим работы – operating conditions пологие характеристики (источника тока) – quiet characteristics / curves возрастающие внешние характери-стики – rising external characteristics подвесной автомат – suspended head самоходный автомат – self-powered unit сварочный трактор – tractor head самоходная тележка – travel carriage прямолинейный шов – straight weld криволинейный шов – curved weld перемещение дуги – arc travel механизм перемещения – travel mechanism

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Упражнения. I. Найдите в тексте русские соответствия следующих слов и сло-

восочетаний: 1) automatic regulator; 2) irrespective of; 3) constant speed of wire feed; 4) in proportion of; 5) steady / constant arc voltage; 6) inherent regu-lation; 7) is most notably effected; 8) external characteristic; 9) accidental de-crease; 10) low current density; 11) automated welding conditions; 12) quiet curves of the current source; 13) to sustain the arc; 14) to travel along the weld-ing line; 15) suspended automatic welding head.

II. Переведите на АЯ следующие слова и словосочетания: 1) прин-

цип регулирования; 2) регулируемая величина; 3) регулирование электри-ческих величин; 4) напряжение дуги; 5) сила тока; 6) подача электрода с постоянной скоростью; 7) плавление электрода; 8) вызываться, быть след-ствием; 9) подавать электрод в дугу; 10) обрыв дуги; 11) целесообразно; 12) механизм перемещения; 13) самоходная тележка; 14) конструктивно объединенный; 15) переносной рельс.

Unit 61. СВАРОЧНЫЕ ФЛЮСЫ Флюсы для дуговой сварки используют для защиты от вредного воз-

действия атмосферных газов и для металлургической обработки сварочной ванны. Их введение обеспечивает хорошее качество шва за счет поддержа-ния устойчивого процесса сварки, формирования химического состава, ме-ханических свойств сварных соединений и легкой отделяемости шлаковой корки от поверхности. Швы получаются плотными и не склонными к обра-зованию трещин.

Флюсы вводят в сварочную ванну различными способами: наносят в виде паст на кромки свариваемых изделий, в виде порошков или газов, вводимых непосредственно в сварочную дугу или пламя и т.д. Основные требования к сварочным флюсам включают следующие:

температура плавления флюсов должна быть ниже температуры плавления основного и присадочного металла;

флюсы не должны оказывать вредного воздействия на металл во время сварки, а также после ее окончания;

плотность флюсов должна быть меньше плотности свариваемых металлов;

в расплавленном состоянии флюсы должны хорошо растекаться по поверхности металла и активно реагировать с образовавшимися окислами ванны;

образовавшиеся при сварке шлаки должны легко отделяться от по-верхности наплавленного металла.

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Сварочные флюсы могут быть кислыми и основными. Если в свароч-ной ванне преобладают основные окислы (обычно это окислы металлов), то должны применяться кислые флюсы. Если же в ней преобладают ки-слотные окислы (SiO2 и др.), то флюс должен быть основным.

Кислые флюсы применяют преимущественно для сварки цветных ме-таллов и сплавов на медной основе: это в основном бура, борная кислота или их смеси с различными добавками. Основные флюсы применяют чаще при сварке чугуна. Как правило, это смесь соды, поташа, и др. Для сварки чугуна в качестве флюса может применяться чистая бура. При сварке под флюсом его состав полностью определяет состав шлака и атмосферу дуги. Взаимодействие жидкого шлака с расплавленным металлом оказывает су-щественное влияние на химический состав и структуру сварочного шва.

Сварку низкоуглеродистых сталей выполняют преимущественно низ-коуглеродистой сварочной проволокой в сочетании с высокоуглеродистым марганцевым флюсом.

Перед употреблением флюсы обычно прокаливают, соблюдая режи-мы, указанные в ТУ или в паспортах, разработанных заводом-изготовителем.

VOCABULARY

флюс для дуговой сварки – arc flux химический состав – chemical composition отделение (флюса) – separation, stripping плотный шов – dense weld оказывать вредное воздействие – to cause harmful / detrimental effect присадочный металл – added metal растекаться по поверхности – spread / flow over the surface кислый флюс – acid flux основной флюс – basic flux кислый окисел – acid oxide

сплав на медной основе – copper alloy бура – borax борная кислота – boric acid сода – soda, sodium carbonate поташ – potash атмосфера дуги – arc atmosphere жидкий флюс – molten / liquid flux прокаливать флюс – to anneal / cal-cinate /temper the flux соблюдать режим – observe the condition of технические условия – specification паспорт завода-изготовителя – manufacturers’ certificate

Упражнения. I. Найдите в тексте русские соответствия следующих слов и сло-

восочетаний: 1) to treat the metal of the weld pool; 2) not inclined / liable to cracking; 3) to spread over the surface; 4) to be easily stripped off the metal sur-face; 5) basic oxides; 6) acid fluxes; 7) pure borax; 8) high carbon manganese flux; 9) specifications; 10) manufacturers’ certificate.

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II. Переведите на АЯ следующие слова и словосочетания: 1) защи-та от вредного воздействия газов атмосферы; 2) введение флюсов; 3) ус-тойчивый процесс сварки; 4) формирование химического состава; 5) не оказывать вредного воздействия; 6) атмосфера дуги; 7) сварка под флюсом; 8) цветные металлы; 9) структура сварного шва; 10) прокаливать флюс.

Unit 62. ЗАЩИТНЫЕ ГАЗЫ Защитные газы, используемые для снижения вредного воздействия

окружающей среды, могут применяться как в чистом виде, так и в смеси. В своей основе это инертные газы, к которым относятся аргон и гелий. Инертные газы химически не взаимодействуют с металлом и не растворя-ются в нем. Их применяют преимущественно для сварки химически актив-ных металлов, таких как титан, алюминий, магний и др. Кроме инертных газов, для защиты сварочной ванны могут применять активные газы, к ко-торым относятся углекислый газ и азот.

Аргон представляет собой бесцветный, негорючий неядовитый газ тяжелее воздуха, который не образует с ним взрывчатых соединений. Он хорошо обеспечивает защиту сварочной ванны, не вступая ни в какую ре-акцию. Он поставляется в баллонах емкостью 40 л под давлением.

Гелий значительно легче воздуха и аргона, поэтому расход гелия при сварке увеличивается в 1,5–2 раза. По своим качествам гелий не уступает аргону, а в некоторых случаях превосходит его. Так, при одном и том же токе дуга в среде гелия выделяет в 1,5–2 раза больше энергии, чем в арго-не. Это позволяет повысить скорость сварки, но гелий дороже аргона, по-этому применяется реже.

Азот – активный газ без цвета, запаха и вкуса. Соединяясь с металла-ми, он образует нитриды, снижающие механические свойства металлов. Его используют для сварки меди и ее сплавов, по отношению к которым азот является инертным газом.

Водород – горючий взрывоопасный газ, не имеющий запаха, цвета, вкуса. Он в 14,5 раз легче воздуха. Так как водород образует взрывоопасные смеси, особенно с кислородом, в чистом для сварки его не применяют. Смесь аргона с водородом значительно улучшает процесс формирования шва, повышает чистоту его поверхности, увеличивает глубину проплавле-ния. Такой смесью часто пользуются при сварке тонких металлов (до 1 мм).

Кислород – газ, активно поддерживающий горение и не имеющий цвета, запаха и вкуса. Его используют для газопламенной сварки металлов. Следует учитывать, что при соприкосновении сжатого кислорода с маслом происходит мгновенное окисление, сопровождающееся выделением тепла, что может привести к воспламенению масла и даже взрыву.

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Углекислый газ или двуокись углерода является активным защитным газом со слабым запахом и резко выраженными окислительными свойст-вами. Для сварки применяют сварочный углекислый газ чистотой 99,5 %. Двуокись углерода не токсична и не взрывоопасна. При содержании в ра-бочей зоне до 0,5 % не представляет опасности для здоровья. Более высо-кие концентрации (свыше 5 %) могут оказать вредное воздействие на орга-низм человека.

Использование смеси аргона и кислорода при сварке стали хорошо сказывается на металлургических процессах и технологических характери-стиках. Так, при содержании кислорода в аргоне до 5 % повышается ста-бильность сварочной дуги, увеличивается текучесть сварочной ванны, улучшается процесс формирования шва, перенос металла становится мел-кокапельным.

VOCABULARY

инертный газ – inert gas растворяться – to dissolve негорючий – non-combustible, non-flammable неядовитый – non-toxic дуга в среде гелия – helium-shielded arc нитриды – nitrides взрывоопасный – (dangerously) ex-plosive в чистом виде – when pure, in the pure state

чистота поверхности шва – weld surface finish, weld smoothness выделение тепла – heat release / generation воспламенение – ignition, inflam-mation резко выраженный – distinct, marked, pronounced металлургические процессы – metal treatment processes текучесть сварочной ванны – weld pool flow

Примечание. Нитраты (nitrates) – азотно-кислые соли и эфиры, производные азот-

ной кислоты HNO3

Нитриды (nitrides) – химические соединения азота с более электропо-ложительными элементами, прежде всего, с металлами. Нитриды алюми-ния, бора, кремния, титана, вольфрама – тугоплавкие, химически стойкие вещества, используются в жаропрочных сплавах.

Нитриты (nitrites) – азотнокислые соли и эфиры, производные азо-тисной кислоты HNO2.


I. Найдите в тексте русские эквиваленты следующих слов и сло-восочетаний: 1) undergo no reaction; 2) to be equal to argon; 3) to excel ar-gon; 4) to sustain combustion; 5) hazardous; 6) to be supplied in cylinders;

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7) helium shielded arc; 8) weld surface finish / smoothness; 9) contact with; 10) its consumption goes up by 1.5–2 times.

II. Переведите на АЯ следующие слова и словосочетания: 1) защит-

ный газ; 2) снизить вредное воздействие окружающей среды; 3) взаимодей-ствовать с металлом; 4) обеспечивать хорошую защиту; 5) поставлять в бал-лонах под давлением; 6) глубина проплавления; 7) газ без запаха; 8) снижать свойства металла; 9) химические соединения; 10) в чистом виде.

Unit 63. СВАРОЧНЫЕ ГОРЕЛКИ Сварочная горелка является рабочим инструментом газосварщика и

дает газосварочное пламя, нагревающее и расплавляющее металл. Совре-менная сварочная горелка должна отвечать многим строгим требованиям: давать устойчивое сварочное пламя требуемой формы, иметь точную регу-лировку, устойчиво поддерживать установленный режим пламени, иметь достаточную прочность, не требовать частого ремонта, быть простой, удобной и безопасной в эксплуатации, иметь минимально возможный вес и т.д. Этим требованиям в достаточной степени могут удовлетворять лишь хорошо сконструированные горелки, тщательно и точно изготовленные из качественных материалов. Основным материалом для изготовления горе-лок служит латунь, мундштук изготавливают из красной меди, иногда для уменьшения веса горелок применяются легкие алюминиевые сплавы. Сва-рочные горелки могут быть изготовлены для различных горючих газов, сжигаемых в смеси с кислородом или воздухом. В сварочной технике пре-обладают ацетилено-кислородные горелки.

Горелки имеют различную мощность, позволяющую сваривать сталь разной толщины – от 0,2 мм до 30 мм.

Сварочные горелки могут быть разделены на два основных типа: го-релки инжекторные, или низкого давления, и безынжекторные, или высоко-го давления. Принадлежность горелки к тому или другому типу определяет-ся наличием или отсутствием в ней инжектора для подсоса горючего газа.

Если горючий газ имеет достаточно высокое давление, не менее 0,5 атм, то он может поступать в горелку самотеком, и горелка может не иметь инжектора. Безынжекторная горелка может работать лишь при дос-таточно высоком давлении горючего газа, поэтому она называется горел-кой высокого давления. Если же давление горючего газа незначительно (менее 0,5 атм), то необходима принудительная подача или подсос горюче-го газа, что осуществляется специальным инжектором.

Ввиду того, что в горелке высокого давления (безынжекторной) от-сутствует инжектор, по конструкции она проще горелки низкого давления. Кислород поступает в горелку по резиновому шлангу и через приемный

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ниппель и регулировочный вентиль проходит в смеситель, где поток ки-слорода разбивается на тонкие струйки для лучшего смешивания с горю-чим газом, после чего проходит в сопло смешения. Совершенно аналогич-ный путь проходит горючий газ, поступающий в горелку через другой ре-гулировочный вентиль. Из смесителя смесь горючего газа с кислородом поступает в камеру смешения, где скорость газового потока уменьшается и заканчивается смешение кислорода с горючим газом. Из камеры смешения готовая смесь проходит по трубке наконечника и через калиброванный ка-нал мундштука выходит наружу, где и сгорает, образуя сварочное пламя. Для образования нормального сварочного пламени горючая газовая смесь должна вытекать из канала мундштука горелки с определенной скоростью, соответствующей скорости горения смеси. При увеличении скорости исте-чения газовой смеси сверх нормы пламя отрывается от мундштука и может потухнуть. При уменьшении скорости истечения газовой смеси из мунд-штука пламя проскакивает через канал мундштука внутрь горелки, проис-ходит воспламенение и взрыв горючей смеси внутри горелки.

Таким образом, сварочная горелка может нормально работать лишь при определенной постоянной скорости истечения газовой смеси из мунд-штука. Эта скорость зависит от состава газовой смеси, диаметра выходного канала и конструкции мундштука. Для ацетилено-кислородной смеси эта скорость для различных размеров горелок лежит в пределах 70–160 м/сек. Для создания такой скорости на выходе из мундштука и преодоления внут-ренних сопротивлений горелки требуется, как показывает опыт, давление газа на входе в горелку порядка 0,5–0,7 атм. Требующееся давление при-мерно одинаково как для кислорода, так и для ацетилена.

Безынжекторные горелки могут быть построены как для ацетилена, так и для других горючих газов – водорода, метана. Они сравнительно просты по устройству, хорошо поддерживают постоянство состава газовой смеси, дают устойчивое сварочное пламя. Несмотря на эти положительные качест-ва, горелки высокого давления в нашей промышленности применяются ре-же, потому что они могут работать лишь на ацетилене достаточного давле-ния, а промышленность широко пользуется ацетиленом низкого давления. Промышленное применение находят чаще инжекторные горелки.

VOCABULARY

газосварщик – gas welder газосварочное пламя – gas welding flame устойчивое сварочное пламя – sta-ble welding flame точная регулировка – precise / ac-curate regulation / balance красная медь – red copper

мундштук – nozzle мощность – heat output конструктивный признак – design feature инжекторная горелка – inhector / low pressure torch

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безынжекторная горелка – positive pressure / pressure / high pressure torch ацетилено-кислородная горелка – oxyacetylene torch подсос (горючего газа) – sucking in, dragging in самотеком – by gravity, by itself, of its own accord принудительный – forced, induced приемный ниппель – receiving / suction nipple регулировочный вентиль – fuel regulator, adjusting screw

смеситель – mixer сопло / мундштук смешения – mixing orifice камера смешения – mixing chamber скорость истечения газового по-тока – gas flow rate однородный – homogeneous, uni-form калиброванный канал – calibrated channel воспламенение – ignition, inflam-mation готовый – ready (for use)


восочетаний: 1) to be accurately regulated; 2) precisely and accurately made; 3) a higher heat output; 4) an injector to drag the fuel gas in; 5) pressure torch; 6) the gas should be forced into the torch; 7) mixer; 8) mixing chamber; 9) the gas flow cross section; 10) mixing orifice; 11) flow rate; 12) a homogeneous mixture; 13) rate of combustion; 14) a neutral flame; 15) to be used industrially.

II. Переведите на АЯ следующие слова и словосочетания: 1) отве-

чать требованиям; 2) удобный в эксплуатации; 3) хорошо сконструирован-ный; 4) не требовать частого ремонта; 5) самотеком; 6) резиновый шланг; 7) сопло смешения; 8) на выходе; 9) воспламенение; 10) в ограниченных пределах; 11) состав смеси; 12) внутреннее сопротивление; 13) поддержи-вать постоянство состава; 14) положительные качества; 15) диаметр вы-ходного канала.

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БИБЛИОГРАФИЧЕСКИЙ СПИСОК

1. Англо-русский словарь по сварочному производству / сост. В. Т. Зо-лотых. – М. : Советская энциклопедия, 1967.

2. Левадный, И. С. Сварочные работы / И. С. Левадный, А. П. Бурлака. – М. : Аделант, 2002.

3. Althouse, D. Modern Welding / D. Althouse, C. H. Turnquist, W. A. Bowditch. – London : The Goodheart-Willcox Co., 1990.

4. Cary, H. B. Modern Welding Technology / H. B. Cary, C. H. Scott. – Upper Saddle River, New Jersey : Pearson Education, 2005.

5. Manly, H. P. Oxy-Acetylene Welding and Cutting / H. P. Manly. – 2005. 6. Rules for classification of ships // High Speed, Light Craft and Naval

Service Craft : manual. – Oslo : Der Norske Veritas, 2005. 7. Welding Handbook / Ed. by R. L. O’Brien. – Miami : American Weld-

ing Society, 1991. – Vol. 2. 8. Weman, C. Welding Processes : handbook / C. Weman. – New York :

CRC Press LLC, 2003. 9. Режим доступа: http://www.philpem.me.uk/elec/welder, свободный. –

Заглавие с экрана. – Яз. англ. 10. Режим доступа: http://websvarka.ru, свободный. – Заглавие с экра-

на. – Яз. рус.

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Автор-составитель: Майя Энверовна Рящина

СВАРОЧНОЕ ПРОИЗВОДСТВО

(на английском языке)

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