POBOLJ[ANJE PERFORMANSI CERMET REZNOG ALATA POMO]U …mf.unze.ba/wp-content/uploads/2016/04/Masinstvo-num3-1998.pdf · ka i povr{ine substrata alata. Istro{eni rezni alati su se tako|e

1. UVOD

Upotreba prevu~enih reznih alata za obradurazli~itih materijala danas predstavlja vrhunskutehnologiju. Razvoj opreme i procesa za pre-vla~enje nam danas omogu}uju proizvodnju{irokog raspona razli~itih tvrdih nitridnih i oksidnihfilmova, te njihovo polaganje na razli~ite substratekao jednoslojnih ili vi{eslojnih obloga. Bez obzirana to da li se oblaù karbid, cermet ili HSS,osnovni problem je kontrola i optimizacija osobi-na kao {to su adhezija prevlake, struktura pre-vlake, debljina prevlake, itd., koje odre|uju per-

Ma{instvo 3(2), 107 - 114, (1998) M.Sokovi}: POBOLJ[ANJE PERFORMANSI...

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PPOOBBOOLLJJ[[AANNJJEE PPEERRFFOORRMMAANNSSII CCEERRMMEETT RREEZZNNOOGG AALLAATTAAPPOOMMOO]]UU TTVVRRDDIIHH PPVVDD PPRREEVVLLAAKKAA

Dr. Mirko Sokovi}, Dipl. Ing., Univerzitet u Ljubljani, Ma{inski fakultet,A{ker~eva 6, 1000 Ljubljana, Slovenija

REZIME

Posljednjih deset godina je karakteristi~no po uvo|enju reznih alata prevu~enih PVD-om, koji danaszauzimaju veliki dio trì{ta reznim alatima. PVD prevlake otporne na habanje (TiN, TiCN, TiAlN i TiZrN)se obi~no koriste za pobolj{anje HSS, ASP i HM alata u dana{njoj industrijskoj praksi. Prvi cermetsa PVD prevlakom se na trì{tu pojavio prije nekoliko godina. Kako veliki broj faktora uti~e na efikas-nost tvrdih prevlaka na reznim alatima, ovi faktori su se analizirali uglavnom s aspekta pobolj{anjakvaliteta proizvoda. Me|utim, efikasnost PVD prevlaka jako zavisi i od prianjanja na substrat i odotpornosti na habanje. Predlaè se novi na~in odre|ivanja performansi prevu~enih reznih alata: tj. CTE-indeks.Ovaj rad se bavi razvojem modela optimizacije kompleksnih performansi i osiguranja kvaliteta cermetalata sa PVD prevlakom s ciljem proizvodnje o~ekivanih ili zahtijevanih proizvoda visoke kvalitete.

Klju~ne rije~i: cermat alat, PVD prevlaka, pobolj{anje performansi

IIMMPPRROOVVEEMMEENNTT OOFF CCEERRMMEETT CCUUTTTTIINNGG TTOOOOLL PPEERRFFOORRMMAANNCCEE BBYY PPVVDD HHAARRDD CCOOAATTIINNGGSS

Dr. Mirko Sokovi}, Dipl. Ing., University of Ljubljana, Faculty of MechanicalEngineering, A{ker~eva 6, 1000 Ljubljana, Slovenia

SUMMARY

The last decade was characterised by the introduction of PVD-coated cutting tools, which presentlytake a large share of the cutting tool market. Wear resistant PVD coatings (TiN, TiCN, TiAlN andTiZrN) are regularly used to improve HSS, ASP and HM tools in industrial practice today. Few yearsago a first PVD-coated cermet appeared on the market. Since a large number of factors contributeto the efficiency of hard coatings on cutting tools, these factors were analysed mainly from theimprovement of product quality point of view. However the efficiency of PVD coatings depends strong-ly on the adhesion to the substrate and on the wear resistance. A new mode for estimation of per-formance of coated cutting tools is proposed: i.e. CTE-index. The present paper deals with the development of the model of complex performance optimisationand quality assurance of PVD-coated sermet tools in order to produce expected or requested highquality products.

Key words: cermet tool, PVD coatings, improvement of performance

1. INTRODUCTION

The use of coated cutting tools to machine variousmaterials now represents state-of-the-art technology.Developments in coating equipment and processesnow enable us to produce a wide range of differ-ent hard nitridic and oxidic films and to depositthem on various substrates as monolayer or multi-layer coatings. Irrespective of whether carbide, cer-met or HSS are being coated, the primary concernis to control and optimise properties such as coat-ing adhesion, coating structure, coating thickness,etc., which determine the performance of the com-

PPRREETTHHOODDNNOO SSAAOOPP[[TTEENNJJEE

PPRREELLIIMMIINNAARRYY NNOOTTEESS

formanse kompleksnog kompozita predstavljenogkao "obloèni rezni alat" [1].Ova ispitivanja su va`na sa dva stanovi{ta. Sjedne strane, smatra se da je za proizvodnjuvisoko pouzdanog alata vaàn materijal substrata(cermet baziran na TiC ili TiCN), dok s drugestrane, maksimum performansi (TiN ili TiZrN) PVDtvrde prevlake na cermet substratu zavisi samo odkarakteristika dodirne povr{ine. Dodirna povr{inase analizira obzirom na stanje povr{ine, ma{inskuobradu i hrapavost povr{ine. Koristila se tehnikadifuzije da bi se pokazalo da tvrde prevlake pred-stavljaju odli~nu barijeru za difuziju izme|u obrat-ka i povr{ine substrata alata. Istro{eni rezni alatisu se tako|e analizirali pomo}u SEM, EDS i AESs ciljem da se odrede dominanatni mehanizmihabanja [2,3]. Uprkos velikom napretku u analizi tankih filmova (slo-jeva), jo{ uvijek su potrebni testovi obradljivosti dabi se demonstrirao potencijal performansi tvrdih pre-vlaka na reznim alatima. Eksperimenti koji slijedeimaju namjeru da pomognu u izoliranju i inter-pretaciji karakteristika dodirne povr{ine izme|u tvrdeprevlake i substrata, te njihovog uticaja na parame-tre procesa rezanja i rezultuju}e oblike i uzroketro{enja alata.

2. CERMET ALATI SA PVD PREVLAKOM

Od po~etka 1980-ih, PVD prevlaka se koristila zavelikoserijsko industrijsko prevla~enje alata sloènegeometrije, kao {to su spiralne burgije, razvrta~i, glo-dala, mlinovi. profilni alati, itd. Prevla~enje, u po~etkusa TiN, je u najve}oj mjeri pove}avalo performansetih alata. Za razliku od brzoreznih ~elika, ~iji su radniuslovi uglavnom ograni~eni njihovom otporno{}u naotpu{tanje, tvrdo}i i otporno{}u na habanje u zagri-janom stanju, karbidi ili cermeti su uglavnomograni~eni pona{anjem njihove tvrdo}e i njihovomotporno{}u na abraziju, difuziju i oksidaciju.Glavne prednosti cermeta baziranih na TiC i TiCNnad konvencionalnim WC tvrdim metalima su nji-hova dobra otpornost na habanje pri visokim brz-inama rezanja, superiorna ~vrsto}a rezne ivice io{trina, te dobar kvalitet povr{ine obratka. Umnogim slu~ajevima obradak se moè obra|ivatibez upotrebe sredstava za hla|enje i podmazi-vanje. Mehani~ke osobine prvobitnih alata suzna~ajno unaprije|ene i danas se mogu poreditisa tvrdim metalima baziranim na WC. Pored ovihatraktivnih osobina, ve}i procenat Ti i Ni upore|enju sa W i Co je nesumnjivo va`na osobi-na koja podràva koncept intenzivnih istraìva~kihaktivnosti u polju cermeta baziranih na TiCN[4,5].


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plex composite represented by a "coated cuttingtool" [1].The present studies are of importance from twoviewpoints. On the one hand, it is considered thatthe substrate material (TiC or TiCN-based cermet) isimportant for the production of highly effective tool,on the other, the performance maximum of (TiN orTiZrN) PVD hard coating on the cermet substrate isdepended to precisely of the interface characteris-tic. The interface is analysed with regard to surfacestate, mechanical treatment and surface roughness.The diffusion couple technique was used to showthat hard coatings represent an excellent diffusionbarrier between workpiece and the tool substratesurface. The worn cutting tools also were analysedby SEM, EDS and AES in order to identify the dom-inant wear mechanisms [2,3].Despite great advanced in the analysis of thin films(layers), machinability tests are still needed todemonstrate the performance potential of hard coat-ings on cutting tools. The following experiments areintended to help isolate and interpret the interfacecharacteristics between hard coating and substrateand theirs influence on the parameters in themachining process, and resulting forms and causesof tool wear.

2. PVD COATED CERMET TOOLS

Since the beginning of the nineteen-eighties, PVDcoating has been used for large scale industrialcoating of geometrically complex tools such as twistdrills, reamers, taps, end mills, form tools, etc.Coating, initially with TiN, led to a major advance inthe performance of these tools. Unlike high speedsteels, whose operating conditions are primarilyrestricted by their annealing resistance, hot hardnessand hot wear resistance, carbides or cermets areessentially limited by their toughness behaviour andtheir resistance to abrasion, diffusion and oxidation. The main advantages of TiC and TiCN-based cermetsover conventional WC-hardmetals are their good wearresistance at high cutting speed, superior edgestrength and sharpness, and good surface quality ofmachined products. In many cases the workpiece canbe machined without the use of cooling lubricants.The mechanical properties of early developed gradeshave been significantly improved and are nowadayscompetitive with the properties of WC-based hardmet-als. Beside these attractive properties, the abundanceof Ti and Ni as compared to W and Co is undoubt-edly an important attribute which supports the con-cept of intensive research activity in the field of TiCN-based cermets [4,5].Coated carbides and cermets have achieved a high

quality standard, as evidenced by the fact that some80 % of all indexable tips used in turning are nowcoated. Use of coated carbides or cermets is muchless widespread in interrupted cut applications, atroughly 30 %. The causes are to be sought in theentry and exit impacts and the associated mechan-ical and thermal shocks, which impose much moreexacting demands on the toughness behaviour ofthe cutting material than on its wear resistance.

2.1 Analysis of tribological system incutting processes

Understanding of tribological problems, nature andcharacteristics of the cutting material, cooling agentand its application are of significant importance forthe predictability of the tool life for a reliable pro-duction in a given application. If all parameters ofthe tribo-system are mutually optimally combined, itcan be expected with high probability that theselected technological values with existing machin-ery will give an optimal product. The theory of resis-tance of tool is very complicated since it is nec-essary to know several scientific disciplines.Figure 1 shows an generalized system approach ofanalysis of the tribo-system during the cuttingprocess, i.e. turning, face milling, ...[6]. The tribo-system that develops when using coated tools canbe shown in a simplified way with a model (empha-sized in Fig. 1) representing the basis for anapproach in analyzing the substrate (cermet tool) -PVD coating - workpiece system. Substrate (3),which can be a different kind of tool, is coveredby a hard TiN (PVD) coating (2) and is in contactwith the workpiece (1). All the results of systemat-ic research show that for the efficiency of the wholesystem the so-cold adhesive joint (5) between TiNcoating and substrate (cermet tool) is of decisiveimportance. The quality of the joint directly definesthe efficiency of TiN coating in the tribological con-tact (4) with the workpiece. The definition of the parameters, description of theprocesses and optimization possibilities of both con-tact spots (4 and 5) have been the subject of exten-sive research. Besides the regularly observed wear,change of mechanical properties and machiningproblems, we now encounter as important parame-ters also adhesion, surface physics and chemistry,film growth and epitaxy and electron metallography.Therefore, every coated tool is also an interdiscipli-nary scientific problem.

2.2. Coated tool efficiency index

In all cases of testing tool wear, it is possible tonote a marked increase in tool life of the cermet

Prevu~eni karbidi i cermeti su dostigli standardvisokog kvaliteta, {to potkrepljuje ~injenica da se nekih80% zabu{iva~a danas izvode sa prevlakom. Upotrebaprevu~enih tvrdih metala ili cermeta je mnogo manjera{irena u prekidnim operacijama rezanja, sa pribli`no30%. Razlozi se mogu na}i u udarnim operacijamasprezanja i odvajanja koje su povezane sa mehani~kimi termalnim {okovima, koji postavljaju mnogo o{trijezahtjeve prema pona{anju tvrdo}e reznog materijalanego prema otpornosti na habanje.

2.1. Analiza tribolo{kog sistema u procesima rezanja

Razumijevanje tribolo{kih problema, prirode i karak-teristika reznog materijala, sredstva za hla|enje injegova primjena su od velike va`nosti za pred-vi|anje vijeka alata za pouzdanu proizvodnju udatoj aplikaciji. Ako su svi parametri tribo-sistemame|usobno optimalno kombinovani, moè se o~eki-vati s velikom vjerovatno}om da }e izabrane tehno-lo{ke veli~ine s postoje}im ma{inama dati opti-malan proizvod. Teorija otpornosti alata je veomasloèna jer je neophodno poznavanje nekolikonau~nih disciplina.Slika 1 prikazuje op{ti pristup sistemu analizetribo-sistema u toku procesa rezanja, tj. struga-nja, glodanja, ... [6]. Tribo-sistem koji se razvijekad se koriste prevu~eni alati se moè pojed-nostavljeno prikazati modelom (istaknutim na slici1) koji predstavlja osnovu za pristup analizi sis-tema susbstrat (cermet alat) - PVD prevlaka -obradak. Substrat (3), koji moè biti razli~ita vrstaalata, je prekriven tvrdom TiN (PVD) prevlakom(2) i u kontaktu je obratkom (1). Svi rezultati sis-tematskog istraìvanja pokazuju da je efikasnostcijelog sistema takozvana adhezivna veza (5)izme|u TiN prevlake i substrata (cermet alata) odesencijalne va`nosti. Kvalitet veze direktno defi-ni{e efikasnost TiN prevlake u tribolo{kom kon-taktu (4) sa obratkom.

Definisanje parametara, opis procesa i mogu}nostioptimizacije obje kontaktne ta~ke (4 i 5) su bilipredmet detaljnih istraìvanja. Osim uobi~ajeno pos-matranog habanja, promjene mehani~kih osobina iproblema u rezanju, sada u va`ne parametresvrstavamo i adheziju, fiziku i hemiju povr{ine, rastfilma i epitaksiju i elektronsku metalografiju. Stoga jesvaki prevu~eni alat tako|e i interdisciplinarni nau~niproblem.

2.2. Indeks efikasnosti alata sa prevlakom

U svim slu~ajevima ispitivanja tro{enja alata,


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moè se primijetiti zna~ajan porast vijeka cermetalata prevu~enog PVD oblogom, bez obzira navrstu procesa obrade, bilo da se radi o struganjuili glodanju. Da bi se ovaj efekat izrazionumeri~ki, uvodi se naziv za ovaj porast vijekaprevu~enog alata, tj. "indeks efikasnostiprevu~enog alata" (CTE-iindeks) [7]. On sedefini{e kao odnos izme|u vijeka trajanjaprevu~enog alata i alata bez prevlake.• U finoj obradi rezanjem, kriterij tro{enja se dajesa VB = 0.2 mm. U tom slu~aju bi se indeks efikas-nosti ozna~io kao CTE0.2.• Sli~no tome, u slu~aju normalne obrade rezanjemza koju je kriterij tro{enja definisan sa VB = 0.4mm, indeks efikasnosti bi se ozna~io kao CTE0.4.

U skladu sa ovom definicijom, dobili smo vrijednostiindeksa efikasnosti prevu~enog alata za razli~itesu~ajeve kao {to je prikazano u tabeli 1 [7,8]:Analiza niza primjera je pokazala da vrijednost indek-sa raste kod te{ko obradljivih materijala ili pri teìmradnim uslovima (posebno ve}i posmak). Uprkostome, ovaj ogroman porast CTE-indeksa nas ne bismio povesti pogre{nim putem: to }e se desiti kadje obrada reznim alatom bez prevlake te{ko izvodlji-va ili ~ak nemogu}a. Prednosti prevla~enja se moguiskoristiti kori{tenjem vi{ih parametara rezanja da bi


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tool coated with a PVD coating, irrespective of thekind of machining procedure, either turning ormilling. To be able to evaluate this effect numeri-cally, a name was introduced to denote thisincrease in the tool life of coated tools, i.e. "coat-ed tool efficiency index" (CTE - index) [7]. It wasdefined as a ratio between the coated tool life timeto the life time of an equal tool without coating:• In fine machining, the criterion of wear is givenby VB = 0.2 mm. Thus the coated tool efficiencyindex would be denoted as: CTE0.2. • Similarly, in the case of normal machining forwhich the wear criterion is defined by VB = 0.4mm, the efficiency index would be denoted: CTE0.4.

In accordance with this definition, we found thecoated tool efficiency indexes for the different casesas follows in Table 1 [7,8]:

The analysis of a series of examples has shown thatthe value of the index increases with materials dif-ficult to machine or in more difficult working con-ditions (especially higher feed rate). However, thisenormous increase in the CTE - index should notmislead us: it will occur when the machining withuncoated tool is fully inefficient or in certain caseseven impossible. The advantages of coatings can be

12

3

1

2

3

4

5

TiN

1 - workpiece2 - TiN (PVD) coating 3 - substrate (cermet tool)4 - tribo-contact area5 - interface between TiN (PVD) coating and substrate

1 - tool2 - workpiece3 - PVD hard coating4 - atmosphere

4vc

vch

F = f (x,s)iv ,a ,f, ...c p

{X} {Y}=f(X,S)S={A,P, R}

{Z}=f(x ,y)

iVB =f(x ,y)KT=f(x ,y)VB, KT...

{Z}

A - elements of system

P - properties of system elements

R - mutual influences of system elements

INPUTVALUES

OUTPUTVALUES

STRUCTUREOF SYSTEM

DISTURBANCEVALUES

Slika 1. Struktura tribolo{kog sistema u procesu rezanja alatima sa prevlakamaFig. 1. Structure of tribological system in cutting process by use of coated tools

CTE =(Tool life )

(Tool life )PVD-coated tool

uncoated toolCTE =

(Tool life )

(Tool life )PVD-coated tool

uncoated tool

se postigli ve}e koli~ine odno{enog materijala pojedinici vremena. Prevu~eni alati se ipak ~estokoriste sa parametrima rezanja identi~nim ili malodruga~ijim od onih koji se koriste kod njihovih ekvi-valenata bez prevlake. Pove}ane performanse setada transformi{u u ve}i stepen odno{enja materijalapo vijeku alata a ne po jedinici vremena, kao kodalata bez prevlake.

3. OPTIMIZACIJA PVD PREVLAKA NACERMET SUBSTRATU

Novi sistemi prevla~enja i sofisticirani procesi pre-vla~enja koji su nam danas na raspolaganjuomogu}uju nam da razumijemo donedavno neob-ja{njene fenomene u vezi sa performansamaprevu~enih reznih materijala. Sve vi{e je o~ito datermofizi~ke osobine prevlaka imaju zna~ajan uticajna njihove performanse i radne parametre. Kvalitetprevu~enih reznih alata ~esto zavisi od tri glavnaparametra, koji su prikazani na slici 2 [2,9].

Subbstrat (materiijall allata)). Uzroci loma tvr-dog metala ili cermeta nastavljaju postojanje potrebeza pobolj{anom tvrdo}om i otporno{}u na habanje.Jedna klju~na oblast interdisciplinarnog razvojnograda, koja se ovdje ne moè detaljnije razmatrati, jepobolj{anje substrata [10].

Prevllakka . Druga klju~na oblast interdiscipli-narnog rada, koja je vrlo sloèna je sofisticiranjeprevlaka. To uklju~uje veliki broj vanjskih iunutra{njih procesnih varijabli. Potrebno je odredi-ti vezu izme|u procesnih varijabli da bi se postiglareproduktivnost i visoki kvalitet prevu~enih alata.

Dodiirna povr{iina. Prou~avanje problemadodirne povr{ine kod prevla~enja naprednijih mate-rijala alata (tj. cermet baziran na TiCN) uklju~ujesljede}e parametre [3]:

- morfologija povr{ine i mikrostruktura substratai PVD prevlaka;

- raspodjela elemenata na dodirnoj povr{ini;- mogu}e relacije me|u elementima iz substrata i prevlake;


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exploited by using higher cutting parameters toachieve higher removal rates per unit time. Coatedtools are, however, frequently also used at cuttingparameters identical with or only slightly higher thanthose for their uncoated equivalents. Increased per-formance potential is then transformed into higherremoval rates per tool life and not per unit time, ascompared to uncoated tools.

3. OPTIMISATION OF PVD COATINGSON CERMET SUBSTRATE

The availability of new coating systems and sophis-ticated coating processes enables us to understandpreviously unexplained phenomena relating to theperformance of coated cutting materials. It isincreasingly apparent that thermophysical propertiesof the coatings have a substantial effect on theirperformance and operating parameters. The qualityof coated cutting tools often depends on threemain parameters, which are shown in Figure 2 [2,9].

Subbstrate (tooll materiiall)) . The causes ofcarbide or cermet failure continue to imply a needfor improved toughness and wear resistance. Onekey area of interdisciplinary development work,which cannot be discussed in greater detail here,is improvement of the substrates [10].

CCoatiing . A second key area of interdisciplinarywork, which is very complex is the sophistication ofthe coatings. There are a great many external andinternal process variables involved. Determining therelationship between both process variables is need-ed in order to achieve reproducibility and high qual-ity in coated tooling.

Interface. The study of interface problems incoating advanced tool material (i.e. TiCN-based cer-met) included the following parameters [3]:

- the surface morphology and microstructure of the substrate and the PVD coatings;

- the distribution of the elements at the interface;

- possible reactions between elements from the substrate and the coating;

fine turning alloysteel (280 HB)

fine turningsteel Ck 45

turning alloysteel C 60N

face millingsteel Ck 45

(Tool Life) uncoated tool (min) 15.5 30 5 8.5(Tool Life) PVD - coated tool (min) 23 50 15 11

CTE - index 1.48 1.67 3.00 1.32

Tabela 1. Performanse cermet alata sa TiN (PVD) prevlakom u razli~itim slu~ajevima obrade rezanjemTable 1. Performance potential of TiN (PVD) coated cermet tool in different cases of machining

- the PVD coatings as a diffusion barrier at theTiC or TiCN-based cermet couple with Armcoiron;

- the possible interaction between titanium andiron atoms at the interface.

For the characterisation of these parameters modernanalytical techniques are used.

Machhiinabbiilliity TTests. Despite great advancedin the analysis of thin films, machinability tests arestill needed to demonstrate the performance poten-tial of hard coatings on cutting tools. The followingexperiments are intended to help isolate and inter-pret the interface characteristics between hard coat-ing and substrate and theirs influence on the para-meters in the machining process, and resultingforms and causes of tool wear.

3.1. From machinability tests to qualitycoatings on the cermet tools

These tests encompass workpiece materials, cuttingtools, and the cutting operation and its characteri-zation. The considerations used in selecting andevaluating cutting tool performance and workpiecemachinability. In the continuation, discussion isfocused on machining tests which are still neededto demonstrate the performance potential of hardcoatings on cutting tools. The latter problems willbe given our full attention. The aims of this researchand development work were to establish the gener-al model of improvement of cermet tool performanceby PVD coating, and determine the strategy of the

- PVD prevlake kao barijera za difuziju kod cermet parova zasnovanih na TiC ili TiCN saArmco èljezom;

- mogu}e me|udejstvo izme|u atoma titanijumai èjeza na dodirnoj povr{ini

Za karakteriziranje ovih parametara se koriste mod-erne analiti~ke tehnike.

TTestovii obbradlljiivostii. Uprkos velikomnapretku u analizi tankih filmova, jo{ uvijek supotrebni testovi obradljivosti za demonstriranje per-formansi tvrdih prevlaka na reznim alatima.Predvi|eni eksperimenti treba da pomognu u izoli-ranju i interpretaciji karakteristika dodirne povr{ineizme|u tvrde prevlake i substrata i njihovog uticajana parametre procesa obrade rezanjem, te rezultira-ju}e oblike i uzroke tro{enja alata.

3.1. Od testova obradljivosti do kvali-tetnih prevlaka na cermet alatima

Ovi testovi zaokruùju materijale obratka, reznealate, te operaciju rezanja i njenu karakterizaci-ju. Uzeti su u obzir prilikom izbora i razvoja per-formansi reznog alata i obradljivosti obratka. Unastavku, diskusija se usmjerava na testoveobrade rezanjem koji su jo{ uvijek potrebni zademonstriranje performansi tvrdih prevlaka nareznim alatima. Potonjim problemima }emoposvetiti punu pa`nju. Ciljevi ovog ispitivanja irazvojnog rada su bili uspostavljanje op{tegmodela pobolj{anja performansi cermet alataPVD prevlakom, i odre|ivanje strategije


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Slika 2. Me|uzavisnost glavnih parametara kvaliteta prevu~enih cermet alataFig. 2. The interaction of main parameters on the quality of coated cermet tools

obradljivosti u finalnoj obradi (u polju tehnologi-je Oblik-kao-kod-vlakna). Slika 3 prikazujesredi{nji dio ovog modela.

Prvi korak upravljanja kvalitetom u ovom slu~ajuje izveden izborom metoda (PVD ili CVD) i opti-mizacijom parametara za procesiranje tvrde pre-vlake.

Drugi korak, odluka o izvo|enju testovaobradljivosti nudi popravku prvog koraka s jednestrane i omogu}uje ispravne podatke o vremenu itro{kovima obrade rezanjem s druge strane, uzima-ju}i u obzir izabrane parametre obrade rezanjem izahtijevani kvalitet proizvoda [2].

To zna~i da se performanse prevu~enih i alata bezprevlake mogu uporediti na sljede}e na~ine:


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machinability in finish machining (within the field ofthe Near-Net-Shape technology). Figure 3 shows thecentral part of this model.

The first step of quality management in this casewas carried out by the selection of the method (PVDor CVD) and optimization of parameters for hardcoating processing.

The second step, the decision for the machin-ability tests offers the correctness of the first stepon one hand and provides the correct dates aboutthe time and costs of machining on the other hand,considering the selected parameters of machiningand required product quality [2].

The performance potentials of coated an uncoatedtools can consequently be compared in the follow-ing ways:

Slika 3. Od testova obradljivosti do kvalitetnih prevlaka na cermet alatimaFig. 3. From machinability tests to quality coatings on the cermet tools

- alati bez prevlake sa razli~ito obloènim alati-ma (TiN; TiC,N; Ti,AlN; TiZrN; CrN, ...) - odre|uju}ivrijednost CTE-indeksa;

- razli~ito prevu~eni alati u istom procesu obraderezanjem;

- razli~ito prevu~eni alati u raznim procesimaobrade rezanjem (struganje, glodanje,...).

Neki rezultati takvih uporednih testiranja su dati udrugim publikacijama [1,2,5,7].

4. ZAKLJU^CI

Jedan od preduslova za uspje{nu proizvodnju jeupotreba kvalitetnih reznih alata sa definisanimmehani~kim i tehnolo{kim osobinama. Me|utim,za razvoj i uvo|enje nove vrste reznog alata(reznog materijala ili prevlaka), neophodno jeizvr{iti brojna ispitivanja s ciljem optimizacije sas-tava materijala (substrata), procedura za proizvod-nju, te rezultiraju}u obradljivost materijala obratka.

U ovom radu smo poku{ali pokazati va`nostpobolj{anja performansi cermet alata pomo}uPVD prevlaka. Poku{ao se primijeniti op{timodel osiguranja kvaliteta cermet prevu~enihalata, i odrediti strategiju obradljivosti u finalnojobradi rezanjem, gdje su od interesa glavniaspekti preciznost dimenzija, hrapavost povr{inei postojanost alata.

LITERATURA - REFERENCES

[1] W. König, R. Fritsch, D. Kammermeier, NewApproaches to Characterising the Performance ofCoated Cutting Tools, Annals of the CIRP, Vol.41/1,1992, pp. 49-54.

[2] M. Sokovi}, Structure and properties of the TiNand TiZrN PVD-coated tool sermets, Doctoral Thesis,Silesian Technical University, Gliwice, Poland, 1997.

[3] B. Navin{ek, S. Novak and D. Zalar, Interfaceproblems in metallurgical coatings, Materials Scienceand Engineering, A, 139, 1991, pp. 249-258.

[4] P. Ettmayer, H. Kolaska, K. Dreyer, Effect of sin-tering atmosphere on the properties of cermets,Powd. Met. Int., Vol. 23, 1991, pp. 224-227.

[5] S. Novak, M.S. Sokovi}, B. Navin{ek, M. Komac,B. Pracek, On the wear of TiN (PVD) coated cermetcutting tools, Vacuum, 48 (1997) 2, pp. 107-112.


- 111144 -

- uncoated with differently coated tools (TiN;TiC,N; Ti,AlN; TiZrN; CrN, ...) - determining the valueof the CTE-index;

- differently coated tools in the same machiningprocesses;

- differently coated tools in various machiningprocesses (turning, milling, ...).

Some results of such comparative testing are givenin another publications [1,2,5,7].

4. CONCLUSIONS

One of the pre-requisites for successful productionis the use of quality cutting tools with definedmechanical and technological properties. Therefore,for the development and introduction of new kind ofcutting tool (cutting material or coatings), it is nec-essary to carry out a number of studies with thepurpose to optimize the material (substrate) compo-sition, processing procedures, and the resultingworkpiece material machinability.

In this paper we try to show the importance ofimprovement of cermet tool performance by PVDcoatings. An attempt is made to apply the generalmodel of quality assurance of cermet coated tools,and determine the strategy of the machinability infinish machining, where the dimensional accuracy,surface roughness and tool life are the majoraspects of interest.

[6] F. û{, M. Sokovi}, J. Kopa~, J. Bali}, Modelof complex optimisation of cutting conditions,Journal of Materials Processing Technology, Vol.64/1-3, February 1997, pp. 41-52.

[7] M. Sokovi}, B. Navin{ek, Improvement of cermettool quality by TiN (PVD) coating, Proceedings ofthe Int. Conf. AMPT "93, Dublin, Ireland, Vol. II,1993, pp. 443-454.

[8] M. Sokovi}, Results of Investigation of the NewTools - Coated Cermets, Proceedings of theWorkshop - Project CEEPUS Network PL-013/9697,Silesian Technical University Gliwice, Wisla, Poland,Vol. 1, 1997, pp. 123-139.

[9] M. Sokovi}, Model of improvement of cermet toolperformance by TiN (PVD) coating, Strojni{ki vestnik,43 (1997) 3-4, pp. 129-136.

[10] S. Novak, M. Ceh, N. Cigrinova, S. Spaic andM. Komac, IX. Int. Pulvermetallurgische Tagung inder DDR, ZFW der Akademie der Wissenschaften,Dresden, Vol.3, 1989, pp. 135-140.

1. UVOD

Uvo|enje vakuumskog preciznog livenja i njegovrazvoj u pravcu direktnog o~vr{}avanja i dobijanjamonokristalnih dijelova, veoma doprinosi razvojuvisoko~vrsto~nih, visokotemperaturnih materijala kojise ne mogu kovati u sloène oblike.Tehnologija livenja usmjerene kristalne strukture ilivenja monokristala je od izuzetnog zna~aja kaobazna tehnologija za proizvodnju turbomlaznog moto-ra (TMM). Imaju}i u vidu ~injenicu da turbomlaznimotori od 1990. moraju imati lopatice turbineizra|ene sa usmjerenom i monokristalnom strukturom,moè se zaklju~iti da ova tehnologija ima perspek-tivnu budu}nost i da }e njena masovna primjenauslijediti krajem ovog i po~etkom sljede}eg stolje}a.

Ma{instvo 3(2), 115 - 124, (1998) Hara~i} N.: PRECIZNO LIVENE KOMPONENTE...

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PPRREECCIIZZNNOO LLIIVVEENNEE KKOOMMPPOONNEENNTTEE OODD SSUUPPEERRLLEEGGUURRAA NNAABBAAZZII NNIIKKLLAA

Mr. Hara~i} Na|ija, vi{i asistent, Ma{inski fakultet u Zenici, Fakultetska 1

REZIME

U ovom radu dat je kratak prikaz tehnologije vakuumskog preciznog livenja superlegura na bazi nikla,preko usmjerenog o~vr{}avanja ( DS ), do modernih monokristala ( SC ). Prikazane su metalografske razlike izme|u makro i mikrostrukture na tri originalna proizvoda (konven-cionalno livenom, DS i SC ), koje nastaju kao posljedica primjenjenih uslova livenja i kristalizacije.

Klju~ne rije~i: precizno livenje, usmjereno o~vr{}avanje, monokristalizacija, superlegure na bazinikla za usmjerenu i monokristalizaciju.

IINNVVEESSTTMMEENNTT CCAASSTTEEDD NNIICCKKEELL - BBAASSEE SSUUPPEERRAALLLLOOYYSSCCOOMMPPOONNEENNTTSS

Hara~i} Na|ija, B.Sc. Asisstant Senior, Faculty of Mechanical engineering in Zenica

SUMMARY

This text contains a short review of the nickel - base superalloys investment casting through thedirectionally solidification (DS) to the modern single - crystals(SC).The basic aspects of the metalographics differences between macro and microstructures on thethree originals products ( conventionally casted, DS and SC ) are given , as well as the influenceof the investment casting process conditions.

Key words: investment casting, directionally solidification, monocrystalisation, nickel - base superalloys for the directionally and monocrystalisation

1. INTRODUCTION

The use of investment vacuum casting and theprogress toward directional solidification and mono-crystalline products yield a great influence to theproduction of high-strength and high-temperatureresistant materials having no ability of being forgedinto the complex shapes.The technology of directional crystalline structurecasting as well as casting of mono-crystals has agreat importance as the basic technology for a tur-bojet engines production (TMM). In the light of thefact that since 1990 turbojet engine blades are pro-posed to be made of directional and mono-crys-talline structure, this technology has indisputablefuture. The massive use can be expected at the verybeginning of the next century.



2. PRECIZNO LIVENJE

Oblast preciznog livenja u ljevarstvu u posljednje vri-jeme je doìvjela veliki uspon, naro~ito u SjedinjenimAmeri~kim Dràvama i Engleskoj. Primjena proizvodapreciznog livenja veoma je {iroka i kre}e se od op{teprimjene preciznih odlivaka, preko proizvoda namije-njenih za avionsku industriju, u juvelirstvu, do pre-ciznih odlivaka za hirurgiju i dentalnu medicinu.Osvajanje tehnologije preciznog livenja povezano jesa mnogobrojnim faktorima kao {to su: specifi~naoprema za topljenje, livenje i o~vr{}avanje saprate}im ure|ajima za vo|enje i kontrolu cjelokupnogprocesa; modeliranje, materijali za precizno livenje ivatrostalni materijali za izradu kerami~kih {koljki; meta-lur{ki aspekti, problemi vezani za defekte i ispitivanjebez razaranja i kontrolu orjentacije kristala dobijenihodlivaka [5 i 10], kao i potrebna ogromna materijal-na sredstva i dobro obu~en tim stru~nog kadra [2].U ovom radu prikazana je ukratko tehnologija pre-ciznog livenja superlegura na bazi nikla. Ovdje seradi o visokoj tehnologiji koja se u svijetu drì podembargom, ali se na osnovu raspoloìvih literaturnihpodataka uo~ava da je pristup rje{enju problemanaro~ito osvajanja tehnologije proizvodnje lopatica sausmjerenom i monokristalnom strukturom, kod po-znatih svjetskih proizva|a~a sli~an [1] i [5].Unapre|enje oblikovanja superlegura spojeno je vi{esa radikalnim promjenama u procesnoj tehnolgijinego sa tradicionalnim razvojem legura.Variranjem hemijskog sastava do{lo se do savre-menih superlegura na bazi nikla obradivih samo donekog odre|enog stepena i to veoma skupomma{inskom obradom. Zbog toga se za proizvodnjukompleksnih oblika od ve}ine superlegura danasprimjenjuje postupak preciznog livenja u kerami~kekalupe nakon rastapanja vo{tanog modela [5].

Osnovne operacije ovoga postupka su: izrada vo{tanogmodela, izrada kalupa, odvo{tavanje, zagrijavanje kalupa,izrada i livenje legure, va|enje odlivka, finalna obrada.Da bi se zadovoljilo veoma visokim, metalur{kim idimenzionalnim zahtjevima propisanim za svaki tipodlivaka potrebno je kontrolisati veliki broj faktora popojedinim fazama postupka naro~ito prilikom izradealata i planiranja detalja tehnike koja }e biti primje-njena [7] i [8]. U protivnom na finalnom proizvodu,dolazi do pojave sljede}ih gre{aka: dimenzionalnegre{ke, poroznost usljed skupljanja volumena (lunker),liva~ke gre{ke usljed nedostatka materijala ili neod-govaraju}e temperature, toplotne pukotine, uklju~ci.

Na slici 1. dat je izgled makrostrukture jedne kon-vencionalno livene superlegure na bazi nikla iz vlasti-tih rezultata ispitivanja.


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2. INVESTMENT CASTING

The investment casting technology has becomemore intense in recent times, especially in the USAand England. The use of investment cast productsis very various, starting from the cast products of ageneral purpose to the products for airplane indus-try, dentistry, chirurgery, jewelry, and so on.The successful use of investment casting technolo-gy depends on many specific factors. Some ofthem are: specific molding, casting and solidifyingequipment and appropriate process control devices;modeling, materials for casting, high-temperatureresistant materials for ceramic molds; then metallur-gical aspects, problems concerning defects, thechoice of non-destructive quality testing, crystal ori-entation control (5,10), and so on. Also a lot ofmoney and well-skilled personnel are necessary pre-requisites.(2).This text gives a brief survey of the investment cast-ing technology of the nickel-base superalloys. Thistechnology represents one of the top secrets in theworld industry. The available literature data confirmthese statements. Conclusion is that the approachto this technology, especially concerning the pro-duction of blades with directional and mono-crys-talline structure is very similar (1, 5).The improvement in superalloy modeling is more theresult of radical changes in the process technologythan in classic development of superalloys.The variation in chemical composition led to theproduction of modern nickel-base superalloys butwith limited machinability, even under expensivemachining processes. In that reason, a complexlyshaped product of the modern superalloys is beingproduced by casting into a ceramic mold after thewax model is melted (5).

The basic operations in this technology are waxmold modeling, mold manufacturing, de-waxing, moldheating, melting, cast drawing, and final machining.In order to meet very high metallurgical and dimen-sional demands, it's necessary to control a greatvariety of influence factors during the process, espe-cially when the tool is being made and in planningall necessary details concerning the technique (7, 8).To the contrary, final product would have some ofthe following defects: dimensional errors, volumeshrinkage cavities, errors caused by casting care-lessness in a sense of insufficient material supply orbad temperature, thermal cavities, inclusions, and so.

Figure 1 shows the macrostructure of a conven-tionally cast nickel-base superalloy, by the authorsown investigation results.

All characteristic zonesof the cast macrostruc-ture are visible here(fine-grained equiaxialzone along the edge ofcast, zone of columnargrain structure and cen-tral zone with large-sizeequiaxial grains).

Figure 2 shows theinvestment cast gas-tur-bine rotor, which ismade of a nickel-basesuperalloy. Themacrostructure isshown on Figure 3(longitudinal section)and Figure 4 (crosssection). All results arebased on author's owninvestigations.

The investigation of themacrostructure showsthat the structure ofrotor central parts (Fig.3, 4) and thick bladeparts consists ofcolumnar dendriticgrains. The macrostruc-ture of the thinnestblade parts consists ofequiaxial, randomly dis-tributed crystals of thesame morphology.

Finally, the latestachievement in invest-ment vacuum castingtechnology is computersimulation of controlledheat flow during thesuperalloy cast solidifi-cation. The use of anappropriate computersoftware enables tosimulate the solidifica-tion of very complexforms, such as gas-tur-bine blade (10).

Na slici se jasno razli-kuju karakteristi~nezone livene makrostruk-ture (sitnozrna zonaekviaksnih kristala uzrub odlivka, zonastubastih-kolomnarnihkristala i centralnazona, krupnih ekviak-snih kristala).Na slici 2, prikazan jeizgled rotora turbomo-tora, dobijenog postup-kom vakuumskog pre-ciznog livenja od jednesuperlegure na bazinikla, sa izgledomdetalja makrostrukturepo njegovom uzdu`nom(Sl.3) i popre~nom(Sl.4) presjeku (primjeriz rezultata vlastitih ispi-tivanja).Ispitivanja makrostruk-ture su pokazala da sestruktura centralnogdijela rotora (Sl.3 i Sl.4)i debljih dijelova lopati-ca sastoji od stubastihdendritnih kristala.Makrostruktura najtanjihdijelova lopatica sastojise od ekviaksijalnih ,slu~ajno raspore|enihkristala iste morfologije.

Na kraju, kao najnovijedostignu}e utehnologiji vakuumskogpreciznog livenja, moèse navesti simuliranjekontroliranog toplotnogtoka za vrijemeo~vr{}avanja odlivakaod superlegura, uzprimjenu aplikacionihkompjuterskih programakoji omogu}avaju simu-liranje o~vr{}avanjaodlivaka kompleksnihoblika kao {to su naprimjer, turbinske lopat-ice [10].


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Slika 1. Makrostruktura jedne konvencionalno livenesuperlegure na bazi nikla

Figure 1. Macrostructure of some convetionallycasted Ni based superalloys

Slika 2 Rotor turbomotora dobijen postupkom vakuumskog preciznog livenja od super-legure na bazi nikla

Figure 2 Investment casted nickel-base superalloysaerogas turbine rotor

Slika 3. Makrostruktura uzdu`nog presjeka rotoraturbomotora od superlegure na bazi nikla

Figure 3. Longitudinal sectioned macrostructure ofnickel-base superalloys aerogas turbine rotor

3. USMJERENA I MONOKRISTALIZACIJA

3.1. Pojam i osnovne osobine usmjerenei monokristalne strukture

Usmjereno o~vr{}avanje je jedan od najva`nijih po-stupaka preciznog livenja superlegura kojim se dobi-ja stubasta (kolomnarna) i monokristalna strukturakoja se naj~e{}e primjenjuje za odlivke avionskihturbina od superlegura. Odsutnost popre~nih grani-ca zrna na glavnim i sporednim rubovima ovakodobijenih tankih dijelova elimini{e osnovni izvorgre{aka koje se javljaju na konvencionalno livenimproizvodima. Posljedica toga su pobolj{anje duktil-nosti i osobina termi~kog zamora usljed ~ega sepostiè zna~ajno smanjenje pucanja rubova turbin-skih lopatica [7] i [8].Primjeri izgleda makrostruktura popre~nih presjekapolikristalne, usmjereno o~vrsnute (dva kristala) imonokristalne lopatice dobijeni, pri vlastitim metalo-grafskim ispitivanjima konkretnih uzoraka lopaticarotora turbomotora od jedne superlegure na bazinikla dati su na slici 5 ( a, b i c ).

Dendritski rast je naj~e{}i mehanizam kristalizacijetehni~kih legura. Posljedica toga je nastajanjemikrosegregacija i uklju~aka koji zajedni~ki uti~u naosobine materijala. O morfologiji dendrita u razli~itimlegurama objavljeni su mnogi radovi prema kojimaje dendrit definisan primarnim, sekundarnim i grana-ma vi{ih redova [3] i [4].Bez obzira o kojoj se vrsti odlivaka radi kristalisuperlegura na bazi nikla pokazuju karakteristikedendritne morfologije.


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Slika 4. Makrostruktura popre~nog presjeka rotoraturbomotora od superlegure na bazi nikla

Figure 4. Cross sectioned macrostructure of nickel- base superalloys aerogas turbine rotor

3. DIRECTIONAL AND MONO-CRYSTALLIZATION

3.1. Definition and Main Characteristics

The directional solidification is one of the mostimportant procedures of superalloy investment cast-ing. The result is columnar and mono-crystallinestructure, mostly used in the production of aircraftgas-turbine superalloy casts. The absence of trans-verse grain boundaries at leading and trailingedges of airfoils eliminates the principal origin offailures, which commonly appears in conventional-ly cast products. The result is the improvement ofductility and thermal fatigue behavior, which rarelyinduces the boundary ruptures in gas-turbineblades (7,8). Three types of cross section macrostructure areshown on Figure 5 (polycrystalline blade - a, direc-tionally solidified (two crystals) - b, monocrystalline-c). It is the result of the author's own metallo-graphic investigation performed on the rotor bladesamples made of nickel-base superalloy.

The dendritic growth is the most frequent mecha-nism of technical alloy crystallization. It producesmicro-segregations and nonmetallic inclusions thathave a common influence on material properties.There is a numerous literature sources dealing withdendrite morphology of different alloys. Primary, sec-ondary and dendrite arms of higher levels define thedendrites here (3,4).The dendrite morphology always characterizes nickel-base superalloy crystals, regardless of the cast type.

Na slici 6 prikazan je op{ti izgled dendritne mikrostruk-ture {uplje monokristalne lopatice za rotor turbine tur-bomotora, ~iji je izgled makrostrukture prikazan nasl.5(c). Pri ve}em pove}anju na sl.7 prikazan je detaljmikrostrukture sa sl.6 (c), koji pokazuje prisustvo krup-nijih faza nepravilnog oblika u osnovnoj strukturi lopa-tice kao i prisustvo poroznosti, obaveznog pratiocalivene mikrostrukture superlegura na bazi nikla.Najnoviji objavljeni podaci [9] opisuju dobijanje anali-ti~ke zavisnosti koja povezuje disperznost dendritnestrukture i faza od kojih se sastoje legure sistemana bazi nikla sa uslovima formiranja odlivaka.

3.2. Stanje tehnologije

Dugotrajnim prou~avanjima pona{anja superlegura nabazi nikla, u laboratorijskim i eksperimentalnimuslovima, do{lo se do zaklju~ka da dalje pobolj{anjeosobina ovih legura nije isplatno postizavati krozrazvoj novih superlegura [7] i [8].

Sljede}i korak u pobolj{anju karakteristika lopaticarotora i statora, turbomlaznih motora, odnosno radnetemperature a time i potiska motora, je bio usmjerenu pravcu pobolj{anja uslova hla|enja ovih kompo-nenti {to je dovelo do razvoja tehnologije livenja{upljih lopatica [6]. Dalje povi{enje ulazne tempera-ture je bilo mogu}e jedino promjenom srukturelopatica, manje kroz promjenu hemijskog sastavasuperlegura, a vi{e kroz osvajanja novih tehnologijakoje su omogu}ile dobijanje lopatica sa usmjerenom(DS) i monokristalnom (SC) strukturom.


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Slika 5. Makrostruktura popre~nog presjeka lopatica rotora od superlegure na bazi nikla: (a) polikristalna; (b) usmjereno - o~vrsnuta ( DS ) lopatica; ( c ) monokristalna (SC) lopatica od superlegure na bazi NiFigure 5. Cross sectioned macrostructure nickel-base superalloys turbine (a) polycrystallin; (b) directionallysolidefied ( DS ) blade ; (c) single - crystal ( SC ) blade

Figure 6 gives the common layout of a dendritemicrostructure of monocrystalline turbine rotor blade,which macrostrycture was showed previously onFig.5c. The microstructure arrangement showed onFigure 7 represents the magnified detail of themicrostructure ( Fig.6). The presence of large irregu-larly shaped phases in the basic blade structure isobvious here as well as the porosity as a commonphenomenon in the cast nickel-base superalloy struc-tures. The recent data (9) give a possibility to estab-lish an analytical functional relationship of the den-drite structure dispersion and particular phases innickel-base superalloys with the casting conditions.

3.2. Present State of Technology

Laboratory and experimental investigations showedthat further improvement of nickel-base superalloyproperties was not possible to accomplish by devel-opment of new supperalloys (7,8).

The cooling condition improvement was the follow-ing path directed toward the progress of gas-turbinerotor and stator blade characteristics, i.e. the work-ing temperature and accordingly the engine pres-sure. This led to the development of hollow bladescasting technology (6). Further increase of the tur-bine-inlet temperature was possible only by changesin the blade structure. This implied the new tech-nologies development directed to the production ofblades with directional (DS) and monocrystaline (SC)structure, i.e. the changes in the chemical compo-sition of superalloys were neglectful.

In 1967, English com-pany "Rolls-Royce" start-ed to develop the tech-nology of producingblades with directionalstructure (DS) (5). Theypatented the new tech-nology in 1971, and thefirst industrial DS bladefoundry was built in1977. In addition, thedevelopment of technol-ogy for the productionof SC blades beganhere in 1975. USAstarted to develop thesame technology in thesixties. In 1982, "Rolls-Royce"performed the appro-priate tests on theexperimental work-bench. Although theproperties of SC bladeswere a little bit betterthan those of SC¢s, theproduction of the SCblades in USA wasstopped in the next tenyears. It was explainedby higher productioncosts comparing withthose of DS blades.After getting an expe-rience in the branchof DS blade produc-tion, the USA re-start-ed to develop the SCblade technology. Atthe same time, theproduction of new

superalloys appropriate to this technology startedto expand (5,7,8).

Nickel-base superalloys intended to directional andmono-crystallization have a similar microstructure. Itconsists of fine disperred particles in g - matrix,"islands"g-g¢¢ eutectic and a little bit of carbides(Fig.6 and 7, by author's own investigation on theoriginal casts). Characteristic chemical and phase compositionresults in very high working and technological per-formances of these superalloys. This is characterizedby lower complexity in refer to those of classicalcasts (7,8).

1967. godine uengleskoj firmi " Rolls-Royce" po~elo se saradom na razvoju lopa-tica sa usmjerenomstrukturom (DS) [5].Osvojena tehnologija jepatentirana 1971.godine, a 1977. godinepostavljeno je industrij-sko postrojenje za live-nje DS lopatica. Radovi na razvojumonokristalnih lopaticau istoj firmi zapo~eti su1975. godine, a u SADsredinom {ezdesetihgodina. U firmi "Rolls-Royce" ve} 1982. vr{enisu testovi na probnimstolovima, dok je u SADrad na osvajanjuproizvodnje lopatica samonokristalnom struk-turom zaustavljen dese-togodi{njim prekidomuz obja{njenje da suone mnogo skuplje odlopatica sa usmjerenomstrukturom uz neznatnobolje osobine.Nakon osvojenog pro-izvodnog iskustva nadobijanju lopatica sausmjerenom strukturomu SAD je ponovozapo~et rad na dobi-janju monokristalnihlopatica. Pri tome seuporedo razvija i radna osvajanju tehnologi-ja dobijanja novih superlegura pogodnih za ovutehnologiju [5], [7] i [8].

Superlegure na bazi nikla za usmjerenu imonokristalizaciju imaju sli~an strukturni sastav kojise odlikuje prisustvom fino dispergovanih ~estica uγ matriksu, "ostrvca" γ−γ′ eutektikuma i male koli~inekarbida (Sl.6 i 7, iz rezultata vlastitih ispitivanja naoriginalnim odlivcima). Visoke vrijednosti radnih itehnolo{kih karakteristika pomenutih superleguraobezbje|uje se karakteristi~nim hemijskim i faznimsastavom koji se odlikuje manjom sloèno{}u uodnosu na legure za klasi~ne odlivke [7] i [8].


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Slika 6. Op{ti izgled dendritne mikrostrukture {upljemonokristalne lopatice za rotor turbine turbomotora

Figure 6 Common view of dendritiques mictostruc-ture nickel-base superalloys turbine hollow single- crystal blade

Slila 7. Detalj sa slike 6Figure 7. Detail from the figure 6

Prema dostupnim podacima i u biv{em SSSR-u i Kinise proizvode lopatice usmjerene i monokristalne struk-ture o ~emu nema detaljnijih podataka. U Japanu setako|e radi na osvajanju tehnologija usmjerenog imonokristalnog o~vr{}avanja. U Bosni i Hercegovini ne postoji oprema zaizvo|enje postupka livenja usmjereno o~vrsnutih imonokristalnih odlivaka, ali su ste~ena zna~ajna zna-nja, naro~ito u oblasti ispitivanja osobina usmjerenoo~vrsnutih i monokristalnih lopatica od superlegurana bazi nikla.

3.3. Proces usmjerenog o~vr{}avanja

Da bi se proizvela èljena struktura kao prvo potreb-no je uspostaviti jak temperaturni gradient koji kaotakav prouzrokuje kretanje me|ufazne povr{ine~vrsto-te~nost, u jednom pravcu. Temperaturarastopa legure mora se odràvati iznad linijelikvidusa i ne smije biti nukleacije u talini ispredfrontalne povr{ine. Za proizvodnju lopatica sa usmje-renom i monokristalnom strukturom postoje dva tipaure|aja i to: stacionarni ure|aji za proizvodnjuusmjereno o~vrsnutih lopatica za turbine (obi~no la-boratorijski) i ure|aji za proizvodnju multi imonokristalnih odlivaka procesom izvla~enja kalupa(industrijska praksa).Na slici 8 {ematski je prikazan stacionarni labora-torijski ure|aj za proizvodnju usmjereno o~vrsnutihlopatica za turbine [1].


- 112211 -

According to the available but insufficient data, theformer SSSR and the Republic of China have pro-duced DS and SC blades too. Japan is also devel-oping the technology of directional and monocrys-taline solidification.Concerning the state of DS and SC technology inthe Republic Bosnia and Herzegovina, there aresome experiences, especially in testing of DS andSC solidified turbine blades of nickel-base superal-loys. Unfortunately, no appropriate casting equipmentexists here.

3.3. Directional Solidification

In order to produce the desired structure, two con-ditions must be met. Firstly, the heat flow gradientmust be strong causing the solid-liquid interface tomove unidirectionally. Secondly, the melt temperaturemust be hold above the liquid line and no nucle-ation in the melt must be ahead of the advancinginterface. There are two types of equipment for theproduction of DS and SC blades: resistance-heatedmold assembly for casting of directionally solidifiedturbine blades (for laboratory use commonly) andequipment for the production of multi and mono-crystaline casting mold drawing (for industrial pur-pose).A schematic view of a laboratory mold for the pro-duction of directionally solidified turbine blades ispresented in Figure 8 (1).

Slika 8. [ematski prikaz stacionarnog laboratorijskog ure|aja za proizvodnjuusmjereno o~vrsnutih lopatica za turbine [1]

Figure 8. Schematic view of resistance - heated mold assembly for castingdirectonally solidified turbine airfoils [1]

Ure|aj ima bakarno vodeno hladilo i molibdenskidvozonski, spiralni, elektro-otporni grija~. Kada selegura rastopi lopatice se liju u vakuumu.Temperaturni gradient, uspostavljen vodenimhladilom, kontroli{e se postepenim smanjivanjemstruje prvo od dna grija~a, a zatim od vrha, kakostubasta zrna rastu prema gore.Na Sl. 9 {ematski je prikazan ure|aj za dobijanjemulti i monokristalnih odlivaka postupkom izvla~enjakalupa, koji je zbog dobrog procesa kontrole, danasdominiraju}i [5].

Pri ovom procesu, pregrijana legura se ulijeva uprethodno zagrijan kerami~ki kalup smje{ten navodom hla|enu plo~u, a cio sklop se postavlja ugrafitni "suseptor" koji se indukciono zagrijava ( lit.).Zbog intenzivnog hla|enja donjeg dijela odlivkakristalizacija kre}e u aksijalnom smjeru ( odozdo nagore ). Radijalno odvo|enje toplote, odnosno krista-lizacija u tom smjeru onemogu}ena je intenzivnimgrijanjem grafitnog "suseptora".

Izvla~enje kalupa iz tople zone se nastavlja sve dokodlivak potpuno ne o~vrsne. Kod stacionarnemetode o~vr{}avanja vrijeme trajanja procesa zajednu lopaticu je znatno duè i iznosi nekoliko satiza razliku od metode sa izvla~enjem odlivka kojebrzina procesa o~vr{}avanja iznosi izme|u 15 i 50cm/h.


- 112222 -

Slika 9. Ure|aji za proizvodnju multi i monokristalnih odlivaka procesom izvlaèenjakalupa ( a ) usmjerena i ( b ) monokristalizacija [5]

Figure 9. Multi and monocrystalline castings mould drawing equipment : (a)directionally, (b) monocrystalline solidification [5]

The mold has a water-cooled copper-chill and isequipped with a two-zone winding molybdenumresistance-heater. When the superalloy is melted,the blades cast in vacuum. The temperature gra-dient established by the water-cooled copper-chillis controlled by gradually reducing the power, firstfrom the bottom winding, then from the top, asthe columnar grains grow upward.Figure 9 schematically shows the equipment for multiand mono-crystaline casting mold drawing. Thanksto the possibility of a good process controlling, thistype of equipment is predominant nowadays (5).

The over-heated superalloy is cast during the processinto the previously heated ceramic mold located onthe water-cooled plate. The whole assembly is mount-ed on inductively heated graphite suceptor (5). Dueto very intensive cooling of the bottom cast part, thecrystallization moves axially (from the bottom to thetop). Intensive heating of graphite suceptor preventsthe radial heat flow i.e. radial crystallization.

Mold drawing from the warm zone continuesuntil the cast is solidified. The characteristic ofthe resistance-heated solidification method isprolonged duration of the process for oneblade (several hours) referring to the molddrawing solidification method (about 15 to 50cm/h).

Kao i kod svakog usmjerenog o~vr{}avanja i kodmonokristalnog na~ina o~vr{}avanja, mora seodràvati pozitivni temperaturni gradijent u rastopulegure tokom cijelog procesa o~vr{}avanja. Da bi seostvario uslov rasta samo jednog zrna (monokrista-la), mogu}e je koristiti ili selektivnu metodu ili meto-du tzv. " klice" (prethodno dobijena klica samojednog kristala ) [7] i [8].Pri procesu monokristalnog o~vr{}avanja zahtjevi zakontrolu temperaturnog gradijenta, kao i zahtjevi zakvalitet materijala kerami~ke {koljke i uslova vaku-uma su mnogo o{triji nego kod kontrolisanog usmje-renog o~vr{}avanja. Proces ovog na~ina o~vr{}avan-ja traje duè (oko 15 cm/h) pa je i mogu}nostreakcije rastopa legure i materijala kerami~ke{koljke, mnogo ve}a.

4. ZAKLJU^CI

1. Uvo|enje vakuumskog preciznog livenja i nje-gov razvoj u pravcu direktnog o~vr{}avanja i dobi-janja monokristalnih dijelova, veoma doprinosirazvoju visoko~vrsto~nih, visokotemperaturnihmaterijala koji se ne mogu kovati u sloèneoblike.2. Oblast preciznog livenja u ljevarstvu u posljednjevrijeme je doìvjela veliki uspon, naro~ito u SAD iEngleskoj. Primjena proizvoda preciznog livenjaveoma je {iroka i kre}e se od op{te primjene pre-ciznih odlivaka, preko proizvoda namijenjenih zaavionsku industriju, u juvelirstvu, do preciznih odli-vaka za hirurgiju i dentalnu medicinu.3. U ovom radu dat je kratak prikaztehnologije vakuumskog preciznog livenjasuperlegura na bazi nikla, preko usmjerenogo~vr{}avanja (DS), do modernih monokristal-nih (SC) lopatica rotora turbomotora, sa rezul-tatima vlastitih ispitivanja originalnih odlivakaod superlegura na bazi nikla, proizvedenih poopisanim postupcima.4. Osvajanje tehnologije preciznog livenjapovezano je sa mnogobrojnim faktorima kao {tosu: specifi~na oprema za topljenje, livenje io~vr{}avanje sa prate}im ure|ajima za vo|enjei kontrolu cjelokupnog procesa; modeliranje,materijali za precizno livenje i vatrostalni mater-ijali za izradu kerami~kih {koljki; metalur{kiaspekti, problemi vezani za defekte i ispitivan-je bez razaranja i kontrolu orjentacije kristaladobijenih odlivaka, kao i potrebna ogromnamaterijalna sredstva i dobro obu~en timstru~nog kadra.


- 112233 -

As in directional solidification, the monocrystalizationalso needs a positive heat gradient of the melt tobe hold continually during the solidification. Toestablish prerequisites for just single grain growing(monocrystal), it's possible to use both, the selec-tive method and so-called nucleus method (i.e. apreviously formed crystal origin as the nucleus)(7,8).Temperature gradient control demands, as well asthose for ceramic mold material quality and vac-uum purity are stronger for the monocrystalinesolidification process than for the controlled direc-tional solidification. Monocrystaline solidificationprocess lasts longer (15 cm/h) so the possibilityof superalloy melt and ceramic mold reactions ishigher.

4. CONCLUSIONS

1. Investment vacuum casting and its developmenttoward the directional solidification and monocrystal-ization contribute at a great extent to the develop-ment of high-strength and high-temperature resistantmaterials having no ability of being forged into acomplex shapes.2. In the recent time, investment casting hasreached a great success, especially in the USAand England. The use of investment casting prod-ucts is widely spread, starting from the cast prod-ucts of a general purpose to the products for air-plane industry, dentistry, chirurgery, jewelry, andso on.3. This paper gave a survey on the technology ofnickel-base superalloy investment vacuum casting.There is also a brief description of directional solid-ification (DS) and modern monocrystalizytion (SC)widely used in the production of gas-turbine rotorblades. The original results based on the author'sown investigations on the original nickel-base super-alloy casts are made available.4. The development of investment casting technolo-gy requires many prerequisite factors. It's necessaryto posses a specific equipment for melting, castingand solidification, and appropriate process controldevices. Furthermore, there are problems concern-ing the act of modeling, appropriate materials forinvestment casting and ceramic mold heat-resistantmaterials, then metallurgical aspects, problems dueto the appearance of defects, non-destructive mate-rial testing and crystal orientation control. Finally,a lotof money and well-skilled personnel are necessarypresumptions.

5. Usmjereno o~vr{}avanje je jedan od najva`nijihpostupaka preciznog livenja superlegura kojim sedobija stubasta (kolomnarna) i monokristalna strukturakoja se naj~e{}e primjenjuje za odlivke avionskihturbina od superlegura. Odsutnost popre~nih granicazrna na glavnim i sporednim rubovima ovako dobi-jenih tankih dijelova elimini{e osnovni izvor gre{akakoje se javljaju na konvencionalno livenim proizvodi-ma. Posljedica toga su pobolj{anje duktilnosti i osobi-na termi~kog zamora usljed ~ega se postiè zna~ajnosmanjenje pucanja rubova turbinskih lopatica. 6. Kod monokristalnog na~ina o~v{}avanja kao ikod svakog usmjerenog o~vr{}avanja mora seodràvati pozitivni temperaturni gradijent u rastopulegure tokom cijelog procesa o~vr{}avanja, a da bise ostvario uslov rasta samo jednog zrna(monokristala), mogu}e je koristiti ili selektivnu meto-du ili metodu tzv. " klice" ( prethodno dobijena klicasamo jednog kristala ).7. Najnovije dostignu}e u tehnologiji vakuumskog pre-

ciznog livenja je simuliranje kontroliranog toplotnog tokaza vrijeme o~vr{}avanja odlivaka od superlegura, uzprimjenu aplikacionih kompjuterskih programa kojiomogu~avaju simuliranje o~vr{}avanja odlivaka komplek-snih oblika kao što su na primjer, turbinske lopatice.

5. LITERATURA - REFERENCES

[1]. Dunn R.G. , Sponceller D.L. , Daht J.M.: DyctilityImprovements in Superalloys, Kyoto InternationalConference Hall, October 1971., s. 319 - 340.

[2]. El Haik R. : Les reactions du metallurgiste faceau devellopement des " Materiaux Nouveaux" ,Memoires et Etudes Scientifiques Revue deMetallurgie, Octobre 1985., s. 525 - 536.

[3] Eremenko V.N. : Fizi~eskaja himija neorgani~eskihmaterialov, Tom 3, Kiev Naukova Dumka, 1988.

[4] Jacobi H., Schwerdtfeger K.: DendriteMorphology of Steady State Unidirectionally SolidifiedSteel, Metallurgical Transaction A, vol.7A, June1976., s. 811 - 819.

[5] PrattD.C.: Industrial Casting of Superalloys,Materials Science and Technology, May 1986. vol.2,s. 426-435.

[6] Khan T., Caron P.: Effect of processing condi-tions and heat treatments on mechanical propertiesof single- crystal superalloy CMSX-2, MaterialsScience and Technology , May 1986., vol.2.


- 112244 -

5. Directional solidification is one of the mostimportant investment casting practices, whichresults in columnar and monocrystaline structure ofthe cast superalloy, mostly used in aircraft turbineindustry. The absence of transverse grain bound-aries at leading and trailing edges of airfoils elim-inates the principal origin of failures, which com-monly appears in conventionally cast products. Theresult is the improvement of ductility and thermalfatigue behavior, so consequently the boundaryruptures in gas-turbine blades are rarely induced.6. Like in any practice of directional solidification,monocrystaline solidification also needs a positiveheat gradient in the melt to be continually holduntil the solidification process is finished. Theprocess of just single grain growing (monocrystal)can be performed by both, the selective methodand "nucleus" method (that is a crystal origin pre-viously born).7. The latest accomplishment in the investmentcasting technology is computer simulation ofthe controlled heat flow during the solidifica-tion in different, even very complex shapes ofsuperalloy casts (for instance, gas-turbineblades).

[7] Stoloff N.S., Nicoll A.R., Sims C.T:: TheSuperalloys : Their Metallurgy, Processing, SurfaceProtection, Repair and Their Alternatives, Part 1.,Industry - University Short Course Program, Utrecht- Netherlands , May 1986.

[8] Stoloff N.S., Nicoll A.R., Sims C.T:: TheSuperalloys : Their Metallurgy, Processing, SurfaceProtection, Repair and Their Alternatives, Part 2.,Industry - University Short Course Program, Utrecht- Netherlands , May 1986.

[9] Svetlov I.L., Kulešova E.A., Monastyrskij V.P. :Vlijanie napravlennoj kristallizacii na fazovijj sastavi disperznost struktury nikelevijh splavov, Metally1990.No.1, s.86-92.

[10] Whittaker G.A. : Precision casting of aero gasturbine components, Materials Science andTechnology, May 1986., vol 2., s. 436 - 441.

[11] * * * Metallography : Nondestructive Testing,Annual Book of ASTM Standards, Part 11, 1977.

U postupcima manevriranja tra~ni~kih vozila ~esti suslu~ajevi naleta jednog vozila na drugo ili na kom-poziciju, odnosno jedne kompozicije na drugu kojamiruje na kolosijeku.Za numeri~ka razmatranja takvih slu~ajeva potrebnoje napisati sustav diferencijalnih jednad`bi od ono-liko jednad`bi koliko, ukupno, sudjeluje vagona ume|usobnom naletu.

2. JEDNAD@BE GIBANJA

Ako jedno vozilo naleti na kompoziciju od tri vago-na koja miruju na kolosijeku (vidjeti sliku 1.) jed-nad`be koje opisuju dinami~ka pona{anja svih vago-na su:

Ma{instvo 3(2), 125 - 130, (1998) M.Stegi},...: RAZMATRANJE ME\USOBNOG NALETA...

- 112255 -

RRAAZZMMAATTRRAANNJJAA MMEE\\UUSSOOBBNNOOGG NNAALLEETTAA VVAAGGOONNAA KKOODD MMAANNEEVVRRIIRRAANNJJAA

Prof. dr.sc. Milenko Stegi}, Prof. dr. Dragutin [~ap, Prof. dr. Osman Mufti},Univerzitet u Zagrebu, Fakultet strojarstva i brodogradnje, Zagreb, Ivana Lu~i}a 5,e-mmail: [email protected]

REZIME

U radu je numeri~ki rje{avan problem me|usobnog naleta vagona kod manevriranja. Primjenjen jediskretan model u kojemu su karakteristike me|uvagonskih veza nelinearne funkcije. Pretpostavljeno jeda su teì{ta vagona na razini me|uvagonskih veza. Sustav nelinearnih diferencijalnih jednad`bi rje{enje u matemati~kom paketu "Mathematica". Na taj je na~in mogu}e, jednostavno, prou~avati dinami~kapona{anja kod me|usobnog naleta razli~ito sloènih kompozicija. Dijagramski su predo~eni rezultatidva jednostavna numeri~ka primjera.

Klju~ne rije~i: nalet vagona, manevriranje, dinami~ko pona{anje

CCOONNSSIIDDEERRAATTIIOONNSS RREEGGAARRDDIINNGG IIMMPPAACCTT BBEETTWWEEEENN RRAAIILL-CCAARRSS IINN MMAANNOOEEUUVVRRIINNGG OOPPEERRAATTIIOONNSS

Prof. dr.sc. Milenko Stegi}, Prof. dr.sc. Dragutin [~ap, Prof. dr.sc. OsmanMufti}, University of Zagreb, Faculty of Mechanical Engineering and NavalArchitecture, Zagreb, Ivana Lu~i}a 5, e-mmail: [email protected]

SUMMARY

The paper discusses numerical solving of the problem of impact between railcars in manoeuvringoperations. The discrete model has been applied in which the characteristics of inter-railcar couplingsare non-linear functions. It is assumed that the cars have their centres of gravity on the coupler cen-treline. The system of non-linear differential equations has been solved using the mathematical pack-et "Mathematica". This allows, in a simple way, the study of dynamic behaviour in the impact betweendifferently set compositions. The results of two simple numeric examples are given in the form of adiagram.

Key words: impact railcars, manoeuving operations, dinamic behaviour

1. UVOD 1. INTRODUCTION

In manoeuvring operations of track vehicles, thereoften comes to occurrences of one car running intoanother or into a composition, i.e. one compositionrunning into another, which rests on the tracks.For the numerical analysis of such cases it is nec-essary to write a system of differential equations,consisting of as many equations as the total num-ber of railcars involved in the impact.

2. EQUATIONS OF MOTION

If a car runs into a composition of three cars stand-ing still on the tracks (Figure 1), the equations thatdescribe the dynamic behaviour of all the cars are:



Veze izme|u vagona su neelasti~ne (npr. opru`no-tarni sklop), a jedna karakteristika takve vezepredo~ena je na slici 2. Sila u neelasti~noj vezi jerazli~ita pri optere}enju, odnosno rastere}enju, tj.ovisi o predznaku umno{ka deformacije i brzinedeformacije veze:


- 112266 -

0)(),( 212121111 =−−−+ xxxxxxcxm &&&&

0)(),()(),( 2121211323232222 =−−−−−−−+ xxxxxxcxxxxxxcxm &&&&&&

0)(),()(),( 3232322434343333 =−−−−−−−+ xxxxxxcxxxxxxcxm &&&&&&

0)(),( 434343344 =−−−+ xxxxxxcxm &&&&

Sustav (1) nelinearnih diferecijalnih jednad`bi jednakje i za slu~aj naleta dva vagona na druga dva kojamiruju na kolosijeku.

The system (1) of non-linear differential equations isthe same for the case of two cars running intoanother two standing still on the railway tracks.

v1x 2x 3x 4x

1m 2m 3m 4m

12c 12c 2c 3cSlika 1. Diskretan model naleta tra~ni~kog vozila na kompoziciju s tri vagonaFigure 1 - The discrete model of impact of a railway vehicleon the train composition

with three cars

Uvo|enjem novih nepoznanica: By introducing new unknown quantities:

q x x1 1 2= − q x x2 2 3= − q x x3 3 4= −

sustav (1) se svodi na: the system (1) is reduced to:

0),()11( 111121

1 =++ qqqcmm

q &&&

0),(1),()11( 11112

222232

2 =−++ qqqcm

qqqcmm

q &&&&

0),(1),()11( 22223

333343

3 =−++ qqqcm

qqqcmm

q &&&&

The couplings between the railcars are non-elastic(e.g. spring-friction assembly), and one characteris-tic of such coupling is presented in Figure 2. Theforce in a non-elastic coupling is different whenloaded, i.e. not loaded, and it depends on theproduct of coupling deformation and the couplingdeformation speed.

(1)

(2)


- 112277 -

),sign1( iiiiLi qqNN &ϕ+=

where NLi=cLiqi force of the linear elastic part ofthe coupling between the cars, and ϕ i=Ntri/NLi is therelation coefficient of the friction force and the lin-ear elastic coupling force. The non-linear functionsci(qi,qi) in the systems (1), i.e. (2) are:

gdje je NLi=cLiqi sila linearno elasti~nog dijela vezeizme|u vagona, a ϕ i=Ntri/NLi jest koeficijent odnosasile trenja i linearno elasti~ne sile veze. Nelinearnefunkcije ci(qi,qi) u sustavima (1), odnosno (2) su:

,3)1(1i,)sign1(),( iiiiLiii =+= qqNqqc && ϕ

a koeficijenti odnosa sila trenja i linearno elasti~nihsila veza su:

and the relation coefficients of the friction forcesand linear elastic coupling forces are:

.3)1(1i,2 iL

i2i1i =

−=

ccc

ϕ

iLN

iN

iq

itrN

itrN

Slika 2. Nelinearna karakteristika me|uvagonske veze Figure 2 - Non-linear characteristic of the coupling between cars

(3)

(4)

(5)

By solving the system (2) of non-linear differential equa-tions, the kinematic and dynamic values are obtained,caused by the impact of railcar during manoeuvring.

3. NUMERICAL EXAMPLES

The first numerical example refers to the impact ofone track vehicle (mass m1=85000 kg), at the veloc-ity of v=2 km/h, with a composition of three equalrailcars (m2=m3=m4=85000 kg) which stands still onthe railway tracks, and all the couplings between carsare equal and determined by:

Rje{avanjem sustav (2) nelinearnih diferencijalnih jed-nad`bi dobivaju se kinemati~ke i dinami~ke veli~inepri naletu vagona tijekom manevriranja.

3. NUMERI^KI PRIMJERI

Prvi numeri~ki primjer odnosi se na nalet jednogtra~ni~kog vozila (mase m1=85000 kg), s brzinom v=2km/h, na kompoziciju od tri jednaka vagona(m2=m3=m4=85000 kg) koja miruje na kolosijeku, asve me|uvagonske veze su jednake i odre|ene su sa:


- 112288 -

N/m1011 63L2L1L ⋅=== ccc ϕ ϕ ϕ1 2 3 0 55= = = ,

The initial conditions at the first moment are:Po~etni uvjeti u po~etnom trenutku su:

,0)0()0()0( 321 === qqq .0)0()0(,)0( 321 === qqvq &&&

Promjene kinemati~kih veli~ina kod naleta jednogvagona na kompoziciju sa tri jednaka vagonapredo~ene su na slikama 3, 4 i 5, a vremenskeovisnosti sila u me|uvagonskim vezama predo~enesu na slici 6. Iz slika 4, 5 i 6 o~ito je da se pri-jenos optere}enja pri naletu rasprostire du` kom-pozicije s vremenskim ka{njenjem [1] kao {to je topotvr|eno i mjerenjima. Slika 6. o~ito pokazuje daje najve}e optere}enje na onoj me|uvagonskoj vezina kojoj se ostvaruje sudar. Maksimalno optere}enjeu prvoj me|uvagonskoj vezi nastupa vrlo brzo, tj. zaoko 0,08 s. Sli~no je i s maksimalnim relativnimusporenjem vagona koje je ve}e od 3,5 g.Drugi numeri~ki primjer odnosi se na nalet dvavagona na jednaka takva dva vagona koja miruju nakolosijeku. Sve mase m1=m2=m3=m4=85000 kg isve me|uvagonske veze su jednake:cL1=cL2=cL3=cL4=11 106 N/m, ϕ1=ϕ2=ϕ3=ϕ4=0,55 ,a po~etni uvjeti su q1(0)=q2(0)=q3(0)=0 ,q1(0)=q2(0)=q3(0)=2 km/h. Ovdje se radi o sudarujednakih kompozicija, pa je simetri~no {irenjesudarnog vala du` kompozicija. Odgovaraju}e kine-mati~ke i dinami~ke veli~ine su jednake kao i uprethodnom primjeru jer su odgovaraju}i parametrimodela u oba primjera jednaki.

The changes of kinematic values during impact ofone railcar with a composition with three equal rail-cars are presented in Figures 3, 4, and 5, and thetime dependent forces in the couplings between carsare presented in Figure 6. The Figures 4, 5, and 6show that during impact the load is transferred alongthe composition with a time delay [1] as confirmedby measurements. Figure 6 shows that the maximumload is at the coupling between cars where theimpact occurs. The maximum load in the first inter-car coupling appears very quickly, i.e. in about 0.08s. Similarly happens with the maximum relative decel-eration of the car that is greater than 3.5 g.The second numerical example refers to the impactof two cars with two equal cars that stand still onthe railway tracks. All the massesm1=m2=m3=m4=85000 kg and all the couplingsbetween cars are equal: cL1=cL2=cL3=cL4=11 106

N/m , ϕ1=ϕ2=ϕ3=ϕ4=0,55 , and the initial conditionsare q1(0)=q2(0)=q3(0)=0, q1(0)=q2(0)=q3(0)=2 km/h.Here, the impact is between equal compositions, andthe impact wave expands symmetrically along thecompositions. The appropriate kinematic and dynam-ic values are the same as in the previous example,since the appropriate parameters of the model arethe same in both examples.

0.05 0.1 0.15 0.2 0.25 0.3- 0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

s

m

)(1 tq

)(2 tq)(3 tq

Slika 3. Ovisnosti relativnih pomaka o vremenu, tijekom 0,35 s od naleta jednog vagona na kompoziciju s tri jednaka vagona

Figure 3 - Dependence of relative time delays, during the period of 0.35 s from theimpact of one car into the composition with three equal cars


- 112299 -

0.05 0.1 0.15 0.2 0.25 0.3

- 0.5

0

0.5

1

1.5

2

sm

s

)(1 tq&

)(2 tq&)(3 tq&

Slika 4. Ovisnosti relativnih brzina o vremenu, tijekom 0,35 s od naleta jednog vagona nakompoziciju s tri jednaka vagona

Figure 4 - Dependence of relative velocities on time, during the period of 0.35 s fromthe impact of one car into the composition with three equal cars

0.05 0.1 0.15 0.2 0.25 0.3

- 30

- 20

- 10

0

10

20

2sm

s

)(1 tq&&

)(2 tq&&

)(3 tq&&

Slika 5. Ovisnosti relativnih ubrzanja o vremenu, tijekom 0,35 s od naleta jednog vagonana kompoziciju s tri jednaka vagona

Figure 5 - Dependence of relative accelerations on time, during the period of 0.35 s fromthe impact of one car into the composition with three equal cars

Za takav slu~aj svi dijagrami su isti kao i uprethodnom primjeru, samo su krivulje s indekom 3poklopljene s krivuljama s indeksom 2. Napominjemoda je numeri~ko rje{avanje sustava nelinearnih dife-rencijalnih jednad`bi provedeno s matemati~kimpaketom "Mathematica" [2].

4. ZAKLJUÂK

Nalet tra~ni~kog vozila na drugo takvo vozilo ili kom-poziciju, koja miruje na kolosijeku, moè se analiziratinumeri~ki. Za to, danas, postoje gotove rutine kaonpr. rutina "NDSolve" u matemati~kom paketu"Mathematica". Za modeliranje takvih problema dobrisu diskretni modeli s nelinearnim vezama koji seopisuju s nelinearnim sustavima diferencijalnih jed-nad`bi. Numeri~ka rje{enja pruàju konstruktoruoptere}enja va`na za dimenzioniranje sanduka, temogu}nost odabira najpovoljnijih me|uvagonskih veza.

LITERATURA

[1] Ver{inskij S. V., Danilov V. N., Husidov V. D.:Dinamika vagona, Transport, Moskva, 1991.

[2] Gunis S. G., Tack C. E.: Anthology of RailVehicle Dynamics, ASME, 1972

[3] Wolfram S.: The Mathematica book, 3rd ed.,Wolfram Media/Cambridge University Press, 1996.

[4] Stegi} M.: Teorija vibracija, Fakultet strojarstva ibrodogradnje, Zagreb, 1996.


- 113300 -

0.05 0.1 0.15 0.2 0.25 0.3

- 0.5

0

0.5

1

1.5

2

MN

s

)(1 tN)(2 tN

)(3 tN

Slika 6. Ovisnosti sila u me|uvagonskim vezama o vremenu, tijekom 0,35 s od naleta jednogvagona na kompoziciju s tri jednaka vagona

Figure 6 - Dependence of forces in couplings between cars on time, during the period of 0.35 s from the impact of one car into the composition with three equal cars

For such a case all the diagrams are the same asin the previous example, only that the curves with index3 coincide with the curves with index 2. It should benoted that the numerical solving of the system of non-linear differential equations has been performed usingthe mathematical packet "Mathematica" [2].

4. CONCLUSION

The impact of a track vehicle with another such vehi-cle or composition standing still on the railway trackscan be analysed numerically. There are ready-maderoutines today for this purpose, such as the routine"NDSolve" within the mathematical packet "Mathematica".Discrete models with non-linear relations described withnon-linear systems of differential equations are used formodelling such problems. Numerical solutions providethe designer with loads important for dimensioning thebody of the railcar, as well as the possibility of select-ing the best coupling between the cars.

LITERATURA

[1] Ver{inskij S. V., Danilov V. N., Husidov V. D.:Dinamika vagona, Transport, Moskva, 1991.

[2] Gunis S. G., Tack C. E.: Anthology of RailVehicle Dynamics, ASME, 1972

[3] Wolfram S.: The Mathematica book, 3rd Ed.,Wolfram Media/Cambridge University Press, 1996

[4] Stegi} M.: Teorija vibracija, Fakultet strojarstva ibrodogradnje, Zagreb, 1996.

1. UVOD

U procesu nastajanja nau~nog djela najobimnija inajdugotrajnija faza je prikupljanje informacija iz do-stupne literature. U svijetu su razvijeni brojni infor-macijski sistemi koji na komercijalnoj osnovi dis-tribuiraju informacije iz pojedinih podru~ja (ChemicalAbstracts, Biological Abstracts, MEDLARS, ISI, NTIS,METADEX, itd.). Postoje i me|unarodne institucije iudruènja koje se time bave, kao {to su: FID -me|unarodna federacija za dokumentaciju, IFLA -me|unarodna federacija bibliotekarskih dru{tava, ISO- me|unarodna organizacija za standardizaciju, UNI-SIST - projekat svjetskog sistema nau~nih i tehni~kihinformacija, INPADOC - me|unarodni zavod zapatente, itd. Izvori nau~nih i tehni~kih informacija se mogu podi-jeliti na primarne i sekundarne. Primarni izvori suknjige, ~asopisi i druga periodika, zbornici sa kon-gresa i konferencija, patenti, standardi, tehni~ki

Ma{instvo 3(2), 131 - 140, (1998) S.Leme{,...: INTERNET KAO IZVOR...

- 113311 -

IINNTTEERRNNEETT KKAAOO IIZZVVOORR NNAAUU^̂NNIIHH II TTEEHHNNII^̂KKIIHH IINNFFOORRMMAACCIIJJAA

Samir Leme{, dipl.in`.ma{, asistent, Ma{inski fakultet u ZeniciMr. Hara~i} Na|ija, dipl.in`.met., vi{i asistent, Ma{inski fakultet u Zenici

REZIME

Internet je postao nepresu{an izvor informacija inènjerima i nau~nicima za njihovu inènjersku i nau~nupraksu, te im omogu}io da budu u toku sa modernim tehnolo{kim dostignu}ima. Istraìvanje i razvoju industriji sve vi{e se oslanjaju na Internet kako bi do{li do svjeìh tehnolo{kih informacija. Cilj ovograda je da objasni upotrebu nekih pretraìva~kih servisa koji mogu pomo}i u brèm pristupu odre|eniminformacijama sa Interneta.

Klju~ne rije~i: Internet, pretraìvanje, informacije, nauka, inènjering

IINNTTEERRNNEETT AASS AA SSOOUURRCCEE OOFF SSCCIIEENNTTIIFFIICC AANNDD TTEECCHHNNIICCAALL IINNFFOORRMMAATTIIOONN

Samir Leme{, B.Sc. Mech. Eng., Assistant, Faculty of Mechanical Engineering in ZenicaM.Sc. Hara~i} Na|ija, B.Sc. Met. Eng., Assistant Senior, Faculty of MechanicalEngineering in Zenica

SUMMARY

The Internet has become an indispensable source for engineers and scientists to find information fortheir engineering and scientific practice and to keep abreast of rapid advances in technology.Research and development in industry increasingly relies on the Internet for acquiring the most up-to-date information on technology. This paper's aim is to show and explain use of some searchengines that can help in faster retrieval of particular information from the Internet.

Key words: Internet, searching, information, science, engineering

1. INTRODUCTION

During scientific work creation process, review ofavailable references information is the largest andlongest phase of operation. There are numerousinformation systems in the world that commerciallydistribute information from different areas [ChemicalAbstracts, Biological Abstracts, MEDLARS, ISI, NTIS,METADEX, etc.). There are also international institu-tions and associations dealing with it, such as: FID- International Federation for Documentation, IFLA -International Federation of Library Associations, ISO- International Standardising Organisation, UNISIST -Project of World System for Scientific and TechnicalInformation, INPADOC - International PatentAssociation, etc. Scientific and Technical sources are divided into pri-mary and secondary ones. Primary sources arebooks, journals and other periodicals, proceedingsfrom conferences, patents, standards, research cen-

RRAADD IIZZLLOO@@EENN NNAA NNAAUU^̂NNOOMM SSKKUUPPUU

CCOONNFFEERREENNCCEE PPAAPPEERR

izvje{taji istraìva~kih centara, slu`bene publikacijeorganizacija i institucija, i dr. Tako veliki broj izvoraje nemogu}e imati uvijek na raspolaganju, te suuvedeni sekundarni izvori, koji daju informacije o pri-marnim izvorima, kao {to su analiti~ki pregledi, bi-bliografije, katalozi biblioteka, i sl. Razvoj informati~ke djelatnosti, a posebnora~unarskih komunikacija i Internet, omogu}ili supristup primarnim i sekundarnim izvorima informacijaiz cijelog svijeta, prakti~no sa svakog ra~unara.

2. KRATAK PREGLED RAZVOJAINTERNETA

Tabela 1. Hronologija razvoja Interneta [4]


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tres technical reports, official publications fromorganisations and institutions, et al. It is impossibleto have such a great number of sources available,and because of that secondary sources are intro-duced, that give information about primary sources,such as, analytical reviews, bibliographies, librarycatalogues, etc.Development of information technology, especiallycomputer communications and Internet, made pri-mary and secondary sources from all over the worldavailable, practically from any computer.

2. A BRIEF CHRONICLE OF THE INTERNET

Table 1. A Brief Chronicle of the Internet [4]

Slika 1. Klasi~no i savremeno pretraìvanje informacija: Univerzitetska biblioteka u Cardiff-u, V. BritanijaFig. 1. Traditional and modern searching of information: University library in Cardiff, G. Britain

1960-teAmeri~ko ministarstvo odbrane pokre}eARPA (Advanced Research ProjectAgency)

1969êtiri institucije povezane u ARPANET;istraìva~ki institut Stanford, UCLA, UCSanta Barbara i Utah univerzitet

1971Formirana 23 servera za povezivanjeuniverziteta i vladinih istraìva~kih centarau SAD

1973Ostvarene prve me|unarodne veze saEngeskom i Norve{kom

1977Na univerzitetu u Wisconsin-u pokrenutTHEORYNET, prvi sistem elektronskepo{te

1982Prvi put se javlja naziv "Internet"; Uvodi seTCP/IP sistem komunikacijskih protokola

1992U Cernu, [vicarska, formiran World WideWeb

1996 Broj servera na Internetu prelazi 10 miliona

1960sUS Department of Defence started ARPA(Advanced Research Project Agency)

1969Four institutions connected into ARPANET;Stanford Research Institute, UCLA, UCSanta Barbara and Utah University

197123 hosts created connecting universities andgovernment research centres in USA

1973First international connections to Englandand Norway

1977THEORYNET created at University ofWisconsin providing first electronic mailsystem

1982First appearance of term "Internet"; TCP/IPsystem of communication protocolsintroduced

1992World Wide Web released in Cern,Switzerland

1996 Internet host number exceeds 10 millions

3. SEARCH ENGINES ONTHE INTERNET

Rapid development of the Internet, especially multi-media service called World Wide Web in a last cou-ple of years made enormous amounts of informationavailable, what gave as a consequence overload of,sometimes unneeded, information, that makes find-ing information relevant for some research or engi-neering problem hard to find. Because of that, it isnecessary to use some of search engines spe-cialised for searching for information by key words.Entering key word in a proper field on the formgives list of Internet addresses; hyperlinks for fastaccess to documents containing given word. Such level of searching is satisfied for most of usersand they do not know other possibilities that suchservices offer. This paper shows some techniquesfor advanced use of such services.

Beside keyword search, lists of addresses on searchengines are sorted by categories. It is possible tofind desired address in another way, by browsingparticular category and subcategory. For example:Science/Engineering/Metal Shaping/Forging/Tools.Search engines can be divided into catalogues (theircontent is refreshed manually) and crawls (tools thattravel through Web by themselves, collecting inter-esting addresses and saving them into database).Use of these services is free of charge (they arefinanced through marketing), and there are alsocommercial services, that charge their users.

3. PRETRA@IVA^KI SERVISI NAINTERNETU

Nagli razvoj Interneta, a posebno multimedijalnogservisa pod nazivom World Wide Web u posljednjihnekoliko godina je omogu}io pristup ogromnimkoli~inama informacija, a posljedica toga je pretr-panost mnogim, ~ak i nepotrebnim informacijama,{to oteàva pronalaènje informacije relevantne zaneko istraìvanje ili inènjerski problem. Stoga jeneophodno koristiti neki od servisa specijaliziranih zapronalaènje informacija po klju~nim rije~ima.Uno{enjem klju~ne rije~i u odgovaraju}e polje, dobi-je se spisak Internet adresa, odnosno hiperlinkovakoji sluè za brzi pristup dokumentima koji sadrètraènu rije~. Ve}ina korisnika je zadovoljna tim nivoompretraìvanja informacija i ne poznaje ostalemogu}nosti koje takvi servisi pruàju. U ovom radusu prikazane neke tehnike za napredno kori{tenje tihservisa.

Osim pretraìvanja po klju~noj rije~i, adrese na pre-traìva~ima su sortirane po kategorijama, tako da sedo traène adrese moè do}i i izborom odgovara-ju}e kategorije i podkategorije. Naprimjer:Nauka/Ma{instvo/Obrada metala/Kovanje/Alati.Pretraìva~i se mogu podijeliti na kataloge (njihov sesadràj obnavlja manuelno) i pauke (alati koji samiputuju Webom, prikupljaju zanimljive adrese ismje{taju ih u bazu podataka). Upotreba ovih servisaje besplatna (finansiraju se putem objavljenih rekla-ma), a postoje i komercijalni servisi, koji svojeusluge napla}uju.


- 113333 -

Slika 2. U polje za pretraìvanje se unese traèna rije~, klikne se na tipku "Search",a zatim se dobije spisak poznatih hiperlinkova sa adresama koje sadrè traènu rije~.Fig. 2. First enter desired word into appropriate field and click on "Search" button,

then you will receive the list of known hyperlinks to all addresses containing given word.

3. 1. AltaVista (http://www.altavista.com)

Jedan od najve}ih servisa za pretraìvanje jeAltavista. Prednost Altaviste je to {to sadrì ogromanbroj adresa, ali je to ujedno i nedostatak, jer sepretraìvanjem dobije veliki broj podataka koji su utom slu~aju neupotrebljivi. Zbog toga je neophodnokoristiti napredniju sintaksu pretraìvanja, kako bi serezultati sveli na one koji {to ta~nije opisuju traènurije~ ili vi{e rije~i.Ovom sintaksom se moè broj od 10.000 adresasvesti na par stotina onih koje zaista imaju veze satraènim tekstom.Altavista razlikuje rije~i i fraze. Rije~i su me|usobnorazdvojene praznim mjestima i ne moraju bitipovezane (pretraùje se po svakoj od rije~i pose-bno), a fraze sadrè nekoliko rije~i koje se morajupojaviti ta~no odre|enim redoslijedom (fraze senavode unutar navodnika). Naprimjer: CONFERENCE1998 }e kao rezultat prikazati adrese dokumenatakoji sadrè ili jednu ili drugu rije~, odnosno sve kon-ferencije i sve {to sadrì broj 1998, a ako se tedvije rije~i stave pod navodnike "CONFERENCE1998", dobi}e se samo spisak konferencija u 1998.


- 113344 -

3. 1. AltaVista (http://www.altavista.com)

One of largest search engines is Altavista. Altavistacontains large number of addresses, but this issometimes a handicap, because such a searchgives too many useless information in that case. Itis necessary to use advanced syntax for searching,to put number of results to a minimum thatdescribes desired word or words most accurate.Such syntax use can reduce number of 10.000addresses to a couple of hundreds, really related todesired text.Altavista distincts words and phrases. Words aredivided by a blank space and do not need to berelated (search is done by every word separately),and phrases contain several words that must appearin exact order (phrases must be under quotationmarks). For example: CONFERENCE 1998 will showas a result addresses of documents that containeither one or the other word, that is all conferencesand everything that contains number 1998, and ifthese two words are under quotations "CONFER-ENCE 1998", only list of conferences in 1998 willbe shown, where number 1998 is exactly after the

Slika 3. Naslovna strana pretraìva~kog servisa "Altavista"Fig. 3. Front page of "Altavista" search engine

godini kod kojih se broj 1998 javlja ta~no iza rije~iCONFERENCE. Ovakav na~in se koristi naj~e{}e kadse traè nazivi institucija, organizacija, kompanija,univerziteta i sl.Fraze se mogu kreirati i od brojeva, tako {to seme|usobno odvoje crticom a ne praznim mjestima(tj. razlikuje se 27 06 1968 i 27-06-1968; u prvomslu~aju se radi o nezavisnim brojevima 27, 06 i1968, a u drugom slu~aju o kombinaciji brojeva kojase traì kao cjelina).Da bi se neka rije~ u nizu rije~i sigurno pojavila,treba ispred nje staviti znak +. Isto tako, ako seispred rije~i stavi znak -, ne}e se prikazivati onirezultati koji sadrè tu rije~. Naprimjer: +CONFER-ENCE+1998-USA prikaza}e adrese svih dokumenatakoje sadrè rije~i CONFERENCE, broj 1998, a nesadrè rije~ USA.Na kraju traène rije~i se moè staviti znak *, kakobi se prikazale sve rije~i na ~ijem po~etku se nalazitraèna rije~. Naprimjer: ENGINE* }e prikazati rije~iENGINE, ENGINEER, ENGINEERING, itd.Altavista razlikuje velika i mala slova, kao {to jeprikazano u tabeli 2. Ako se tekst upi{e malim slovi-ma, rezultati }e sadràti i velika i mala slova, a akose upi{e velikim slovima, onda }e i rezultati bitiispisani samo velikim slovima, tj. dobi}e se manjerezultata.

Tabela 2. Upotreba velikih i malih slova

Mogu}e je kombinovati fraze i rije~i pomo}u logi~kihoperatora AND (I), OR (ILI) i NOT (NE), te opera-tora NEAR (PORED). Operator AND podrazumijevada su zadovoljena oba uslova, a operator OR da jezadovoljen barem jedan od uslova. Operatorom NOTse traì da dokument ne zadovoljava uslov navedeniza tog operatora, dok operator NEAR podrazumije-va da se dvije rije~i moraju obje nalaziti u doku-mentu jedna pored druge, nezavisno od njihovogredoslijeda.Operatori AND, OR, NOT i NEAR se moraju upisativelikim slovima. Fraze i rije~i se u ovako kreiranimizrazima mogu grupisati pomo}u zagrada.U naprednu sintaksu spadaju i prefiksi, ~ije jezna~enje dato u tabeli 3.

3.2. Yahoo (http://www.yahoo.com)

Yahoo je katalo{ki servis koji su pokrenuli studentisa Univerziteta Stanford u SAD, koji je kasnije pre-


- 113355 -

word CONFERENCE. This method is used mostly forsearching of institutions names, company or univer-sity names, etc.Phrases can also be formed from numbers, sepa-rating numbers with dashes instead of blank spaces(i.e. 27 06 1968 and 27-06-1968 are not the same;former takes independent numbers 27, 06 and 1968,and latter gives combination of numbers that issearched as one item).To make sure that specific word is always searched,put the plus + sign in front of it. The same, if youput the sign minus - in front of a word, it willexclude all results containing that word. For exam-ple: +CONFERENCE+1998-USA will show address-es of all documents containing word CONFERENCEand number 1998, and not containing word USA.At the end of desired word can be sign *, to showall words that begin with given word. For example:ENGINE* will show words ENGINE, ENGINEER,ENGINEERING, etc.

Altavista differs uppercase and lowercase, as it isshown in table 2. If text is entered using lowercase,result will be both in uppercase and lowercase, andif text is entered using only uppercase, than resultswill be only in uppercase - it will reduce numberof results.

Table 2. Use of uppercase and lowercase

It is possible to combine words and phrases withlogical operators AND, OR and NOT, and operatorNEAR. Operator AND assumes that both conditionsare true, and operator OR that at least one of con-ditions is true. Operator NOT assumes that docu-ment does not comply with condition named afterthat operator, and operator NEAR assumes that bothwords have to be contained in a document, next toeach other, independent of word order.

Operators AND, OR, NOT and NEAR have to beentered in uppercase. Phrases and words in suchqueries can be grouped with brackets. Advanced syntax contains also some prefixes, whosemeaning is given in table 3.

3.2. Yahoo (http://www.yahoo.com)

Yahoo is catalogue service started by students fromStanford University in USA, and later it became very

Traèni tekst Rezultatinauka nauka, Nauka, NAUKANAUKA NAUKANauka Nauka

Desired text Resultsscience science, Science, SCIENCESCIENCE SCIENCEScience Science

commercial company. As catalogue is maintainedmanually, according to request for publishing, it con-tains less information than Altavista. Yahoo query syntax is almost identical to one onAltavista. Prefixes are different (there are only twoprefixes t: and u:, analogue to prefixes text: and url:on Altavista.Interesting characteristics of Yahoo search engine ispossibility to redirect results from Altavista, if thereare not enough results in Yahoo catalogue com-prising with given conditions.

3.3. Cobiss (http://www.izum.si/cobiss)

As search Altavista and Yahoo engines are not spe-cialised only to scientific information sources, andthis paper's accent are scientific information. It isnecessary to mention COBISS information system,started in Slovenia. Also, some libraries from Bosniaand Herzegovina started to connect themselves intoCOBISS this year. It is interesting because it gives information about

rastao u izrazito komercijalnu kompaniju. Kako sekatalog aùrira ru~no, na osnovu zahtjeva za objavlji-vanje, ima manje podataka od Altaviste.Sintaksa na Yahoo pretraìva~u je skoro identi~naonoj na Altavisti. Razlikuju se prefiksi (postoje samoprefiksi t: i u:, ~ija je upotreba analogna prefiksimatext: i url: kod Altaviste.Interesantna osobina pretraìva~a Yahoo je to {toima mogu}nost usmjeravanja na Altavistu, ako se neprona|e dovoljan broj dokumenata koji zadovoljava-ju zadate uslove.

3.3. Cobiss (http://www.izum.si/cobiss)

Kako pretraìva~ki servisi Altavista i Yahoo nisuspecijalizirani samo na izvore nau~nih informacija uovom ~lanku naglasak je stavljen na te vrste infor-macija. Potrebno je pomenuti i COBISS informacionisistem biblioteka, koji je pokrenut u Sloveniji, a ukoji je ove godine po~elo uklju~ivanje i nekih bosan-skohercegova~kih biblioteka.Interesantan je utoliko {to daje informacije o rela-


- 113366 -

Prefiks Funkcijaanchor:tekst Pronalazi dokumente koji sadrè

navedenu rije~ ili frazu u tekstuhiperlinka. anchor:"Click here tovisit AltaVista" }e na}i dokumentekoji sadrè "Click here to visitAltaVista" kao hiperlink.

domain:domena Pronalazi dokumente unutarnavedene domene. Naprimjerdomain:ba nalazi dokumente izBosne i Hercegovine, ilidomain:org dokumenteorganizacija.

host:ime Pronalazi stranice na odre|enomra~unaru. host:utic.net.ba }e na}idokumente na UTIC serveru ahost:sava.miz.ba }e na}idokumente na ra~unaru sa imenomsava u mreì sa domenom miz.ba.

image:file Pronalazi dokumente sa slikamapohranjenim u fajl odre|enogimena. image:system pronalazidokumente sa slikama pohranjenimkao fajl naziva system (system.gif,system.bmp, system.jpg i sl.).

link:URL Pronalazi dokumente koji sadrèlink na odre|eni URL.link:altavista.com }e prona}i svedokumente koji sadrè link naAltaVistu.

text:tekst Pronalazi dokumente koji sadrènavedeni tekst u bilo kojem dijeludokumenta, osim naziva slike, linkaili URL-a.

title:tekst Pronalazi dokumente koji sadrètraèni tekst u naslovu dokumenta.

Prefix Functionanchor:text Finds pages that contain the

specified word or phrase in the textof a hyperlink. anchor:"Click hereto visit AltaVista" would findpages with "Click here to visitAltaVista" as a link.

domain:domain Finds pages within the specifieddomain. Use domain:ba to findpages from Bosnia andHerzegovina, or use domain:org tofind pages from organisations.

host:name Finds pages on a specific computer.The search host:utic.net.ba wouldfind pages on the UTIC computer,and host:sava.miz.ba would findpages on the computer called savaat miz.ba.

image:filename Finds pages with images having aspecific filename. Useimage:system to find pages withimages called system (system.gif,system.bmp, system.jpg etc.).

link:URLtext Finds pages with a link to a pagewith the specified URL text. Uselink:altavista.com to find all pageslinking to AltaVista.

text:text Finds pages that contain thespecified text in any part of thepage other than an image tag, link,or URL.

title:text Finds pages that contain thespecified word or phrase in the pagetitle.

Tabela 3. Neki od prefiksa za pretraìvanje Table 3. Some of search prefixes


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Slika 4. Naslovna strana pretraìva~kog servisa "Yahoo"Fig. 4. Front page of "Yahoo" search engine

Slika 5. Obrazac za upisivanje podataka za pretraìvanje na COBISS sistemuFig. 5. The data input form at the COBISS system

tivno lako dostupnim izvorima primarnih nau~nihinformacija u Sloveniji i Bosni i Hercegovini.Naime, radi se o sistemu koji nije direktno vezan zaInternet, nego posjeduje vlastitu infrastrukturu, aliizme|u ostalih na~ina povezivanja, koristi i Internetza uspostavljanje veze izme|u pojedinih centara. Dodanas je u ovaj sistem uklju~eno preko 200 bib-lioteka u Sloveniji, Nacionalna i univerzitetska bib-lioteka BiH, te gradske biblioteke Tuzle i Zenice.Interesantno je to {to se sistemu moè pristupitiputem Interneta, a podaci koji se dobiju su aktuel-ni jer se aùriraju svakodnevno.

Izgradnjom kantonalnih Soros Internet centara ipokretanjem projekta univerzitetske ra~unarske mreèBosne i Hercegovine ARBANET, stvorene su tehni~kemogu}nosti za povezivanje i drugih, gradskih i fakul-tetskih biblioteka u ovaj sistem, {to bi zna~ajnopove}alo dostupnost literature na na{em jezikukojom raspolaù na{e biblioteke.U obrazac za unos podataka koji se pretraùju moguse unijeti autor, naslov, godina izdavanja, jezik, rije~iiz naslova ili klju~ne rije~i, sa operatorima AND, ORi NOT.

3.4. Ostali servisi

Osim Altaviste i Yahoo-a, postoje jo{ mnogi pre-traìva~ki servisi koji rade na sli~an na~in. EXCITE (http://www.excite.com) je interesantan potome {to se pretraga vr{i po principu "Query ByExample", koji moè aktivirati niz me|usobnopovezanih pretraga bez potrebe da se svaki putunosi novi izraz za pretraìvanje.

HOTBOT (http://www.HotBot.com) je novijeg datuma.Nema posebnu sintaksu za pretraìvanje, tj. podacise upisuju u vi{e odvojenih polja koja se me|usob-no povezuju relacijama (OR, AND, i sl.).

INFOSEEK (http:www.infoseek.com) ima jednu odnajve}ih baza podataka na svijetu. Sintaksa za pre-traìvanje se ne{to razlikuje od one na Altavisti, tako{to se vi{e rije~i u nizu mora me|usobno odvojitizarezom, a umjesto navodnika, fraze se pi{u velikimpo~etnim slovom.

LYCOS (http://www.lycos.com) je tako|e zna~ajanpretraìva~ki servis, ~ija se baza podataka aùrirasvakodnevno. Omogu}uje pretragu zvu~nih islikovnih zapisa.

MAGELLAN (http://www.mckinley.com/magellan) osimogromnog broja adresa dokumenata na Internetu,ima i sistem rangiranja dokumenata. Dokumenti koji


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relatively easy accessible primary scientific sourcesin Slovenia and Bosnia and Herzegovina.It is system that is not directly involved in Internet,it has its own infrastructure, but it uses Internetamong other ways of connection to connect its cen-tres. Over 200 libraries from Slovenia are involvedinto this system up to now, as well as National andUniversity Library of Bosnia and Herzegovina, andcity libraries from Tuzla and Zenica.It is interesting that system can be accessedthrough Internet, and the information obtained isactual because it is updated daily.

Setting up of Canton Soros Internet centres and startof project for Bosnian university computer networkARBANET, prepared technical resources to connectother, city and faculty libraries into this system. Itwould significantly raised level of availability of liter-ature on our language from our libraries.Data input form contains fields for entering author,title, publication year, language, words from title andkeywords, all with logical operators AND, OR andNOT.

3.4. Other search engines

Except Altavista and Yahoo, there are numeroussearch engines that operate in similar way. EXCITE (http://www.excite.com) is interestingbecause search is performed through "Query ByExample", that can activate a series of relatedsearches without having to initiate new searchqueries every time.

HOTBOT (http://www.HotBot.com) is a newcomer. Ithas not its own search syntax: text is entered intoseveral separated fields, that can be optionally relat-ed (OR, AND, etc.).

INFOSEEK (http://www.infoseek.com) has one oflargest databases in the world. Search syntax isslightly different from Altavista's: words in listmust be separated with commas, and instead ofquotation marks, phrases are entered in with acapital.

LYCOS (http://www.lycos.com) is also significantsearch engine, whose database is updateddaily. It provides search for sound or picturerecords.

MAGELLAN (http://www.mckinley.com/magellan)besides large number of document addresses fromInternet, it has its own system for ranking of docu-

zadovoljavaju odre|ene kriterije kvaliteta dobijuposebnu kategoriju "Green Light".

WEBCRAWLER (http://webcrawler.com) nije katalog,nego "pauk" koji Internet pretraùje automatski, {toza posljedicu ima ogroman broj adresa koji se dobi-je pretraìvanjem. Moè se ograni~iti broj adresakoje èlite prikazati.

Od ostalih servisa potrebno je pomenuti AMAZON.Amazon (http://www.amazon.com) nije pretraìva~,nego je kompanija koja se bavi prodajom knjigaputem Interneta. U po~etni obrazac, sli~no kaokod pretraìva~a, upi{e se naslov knjige, autor,ISBN, jezik na kojem je napisana knjiga ili klju~nerije~i, a zatim se dobije spisak knjiga koje semogu poru~iti putem Amazona. Amazon ima si-gurno najve}u ponudu knjiga, ~asopisa i magazi-na na svijetu.

4. IZVORI NAU^NIH INFORMACIJANA WWW

Postoje pretraìva~ki servisi koji su specijalizirani zanau~ne i inènjerske informacije. Neki od njih sunabrojani ovdje.BUBL (http://link.bubl.ac.uk/engineering). Jedan odnajstarijih bibliote~kih servisa na Internetu.

TCE (http://www.clearinghouse.net/eng.html). Nizadresa dokumenata o nauci i praksi u inènjerstvu.

EEVL (http://www.eevl.ac.uk). Virtualna biblioteka izEdinburga, koja uklju~uje baze podataka, elektronske~asopise, ud`benike, reference, patente, software istandarde.

EELS (http:www.ub2.lu.se/eel/eelhome.html). Bazapodataka o inènjerskim i tehnolo{kim resursima naInternetu sa sjedi{tem u [vedskoj.

ICE (http://www.englib.cornell.edu/ice/ice-index).Katalog Internet resursa za inènjere, istraìva~e istudente tehni~kih fakulteta.

The World-Wide Web Virtual Library: Engineering(http://ariochgsfc.nasa.gov/wwwvl/engineering.html#spec). Baza podataka ameri~ke agencije NASA.


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ments. Documents, whose quality is beyond certaincriteria, are rated "Green Light", which gives themspecial attention.

WEBCRAWLER (http://webcrawler.com) is not cata-logue; it is "crawler" that searches through Internetautomatically. As a consequence, it has huge Internetdirectory with addresses. You can choose the num-ber and the format of displays after the search.

One of other services that have to be mentionedhere is AMAZON. Amazon (http://www.amazon.com)is not search engine, it is company that sells booksthrough Internet. You can enter book title, author'sname, ISBN, language or keywords into startingform, similar to search engine form, then youreceive a list of books that can be ordered fromAmazon. Amazon surely has biggest offer of books,journals and magazines in the whole world.

4. SOURCES OF SCIENTIFIC INFORMATION ON THE WWW

There are search engines specialised for scientificand engineering information. Some of them are list-ed below.BUBL (http://link.bubl.ac.uk/engineering). One of theoldest library services on the Internet.

TCE (http://www.clearinghouse.net/eng.html). List oftopics pertaining to the science, work or professionof engineers.

EEVL (http://www.eevl.ac.uk). Virtual library fromEdinburgh, that includes databases, electronic jour-nals, training materials, reference materials, patents,software and standards.

EELS (http://www.ub2.lu.se/eel/eelhome.html). Aninformation system from Sweden for engineering andtechnological resources on the Internet.

ICE (http://www.englib.cornell.edu/ice/ice-index).Internet resources catalogue for engineers,researchers and technical students.

The World-Wide Web Virtual Library: Engineering(http://ariochgsfc.nasa.gov/wwwvl/engineering.html#spec). NASA database.

5. ZAKLJUÂK

• More informacija koje nudi Internet nije od velikekoristi za nau~nika, istraìva~a ili inènjera, ako nepoznaje na~ine na koje moè prona}i one informa-cije koje su potrebne.

• Postoje pretraìva~ki servisi op{te namjene, ali iservisi specijalizirani za pojedine oblasti. U svakomslu~aju, nije dovoljno koristiti samo jedan servis zapretraìvanje, nego je bolje koristiti kombinaciju vi{epretraìva~kih servisa, kako bi se do{lo do rele-vantne informacije.

• Tako|e, ako se pretraìvanjem dobije nekolikodesetina hiljada adresa, to nije od velike pomo}i zakorisnika. U tom slu~aju se moraju koristiti sintakseza napredno pretraìvanje, kako bi se spisak adresasveo samo na one koje imaju veze sa traènomtemom.

LITERATURA - REFERENCES

[1] V. Ribarevi}: Informacije - za{to i kako?, "EGE"12, Zagreb, 1995 (112-113)

[2] M. [ami}: Kako nastaje nau~no djelo, Svjetlost,Sarajevo, 1984

[3] D. Susanj, D. Petric: Velika knjiga o World WideWebu, Znak, Zagreb, 1996

[4] J. He: Introduction of the Internet and WorldWide Web, Experimental Techniques 5, Ohio USA,1997 (31-33)

[5] J. He: Search Engines on the Internet,Experimental Techniques 1, Ohio USA, 1998 (34-37)


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5. CONCLUSION

• A waste of information on Internet is not usefulfor scientist, researcher or engineer, if they do notknow searching techniques for necessary informa-tion.

• There are general search engines, but also thereare services specialised for certain areas. Anyway, itis not enough to use only one search engine. It isbetter to use a combination of more search engines,to obtain relevant information.

• Also, if searching gives tens of thousands results,it is not useful for user. Because of that, advancedsearch syntaxes have to be used, to reduce list ofaddresses to those who really are related to topicthat is searched.

[6] D. Petric: Napredno pretraìvanje Weba, "BUG"67, Zagreb, 1998 (159-161)

[7] S. Leme{, M. Muji~i}: PC nije bauk II, Dom{tampe, Zenica, 1998

[8] Projekat ra~unarskog povezivanja biblioteka u BiHpreko Interneta (program tehni~ke pomo}i RepublikeSlovenije), IZUM, Maribor, 1997

[9] Tendencije u modernom bibliotekarstvu, semi-narski materijali, Tuzla, 24.11.-27.11.1997.

1. PP CILJEVI

U posljednjim decenijama su se na trì{tu, umjestonekada{njih ponu|a~a, koji su diktirali ponudu, sadau prvi plan nametnuli - kupci, diktiraju}i kvalitet,kvantitet, rok i cijenu te iste ponude. Tome mora dase prilagodi proizvodnja svake fabrike, sistemati~noprogramiraju}i svoju proizvodnju u smislu:

- kratkih rokova isporuke,- plitke tehnologije proizvodnje,- podno{ljive iskori{tenosti kapaciteta,- minimalnih materijalnih zaliha.

2. PP PROBLEMATIKA

Uo~i}emo ba{ onaj tip proizvodnje u kojemu sekriju elementi ostalih tipova (vi{estepena, kod kom-pleksnih proizvoda i pojedina~na proizvodnja) jer se

Ma{instvo 3(2), 141 - 149, (1998) A.Milo{: PROGRAMIRANJE FABRI^KE PROIZVODNJE

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PPRROOGGRRAAMMIIRRAANNJJEE FFAABBRRII^̂KKEE PPRROOIIZZVVOODDNNJJEE ((PPPP))((DDaa ssee ii{{ttaa bbiittnnoo nnee zzaabboorraavvii))

dr Anton Milo{, Nau~ni saradnik IOE Sarajevo

REZIME

Sistemati~no programiranje produkcije obuhvata proizvod i organizaciju proizvodnje, s tim da ovodrugo proizlazi iz prvog. Po{to se programira uvijek u okviru ukupne poslovne politike preduze}a,tehnolo{ki i ekonomski aspekt imaju podjednaku va`nost. Ovaj tekst predstavlja pregled glavnih tehno-lo{kih, organizacionih i ekonomskih problema i metoda za programiranje proizvodnje u jednoj fabrici.

Klju~ne rije~i: proizvodnja, planiranje, fabrika, organizacija, investicije, proizvesti ili kupiti

FFAACCTTOORRYY PPRROODDUUCCTTIIOONN PPLLAANNNNIINNGG ((PPPP))((IInn oorrddeerr nnoott ttoo ffoorrggeett aannyytthhiinngg iimmppoorrttaanntt))

Anton Milo{, Ph.D., IOE Sarajevo Scientific Associate

SUMMARY

A systematic production program includes the product and organization of production, understandingthat the second emerges from the first. Technologic and economic aspects are of the same rele-vance because the program is made always within the frame of the whole company business poli-cy. This text is a review of technologic, organization and economic problems and methods of pro-duction programming within a factory.

Key words: production, planning, factory, organization, investment, make or buy

1. PP GOALS

During last decades at the market, instead of formerbidders, who dictated supplies, the buyers have comeinto the first plan dictating quality, quantity, terms andprices of these particular supplies. Production of eachfactory should adjust to it now and it must systemat-ically programme its production in view of:

- short delivery terms,- low production technology,- acceptable utilisation of capacities,- minimal material stores.

2. PP PROBLEMS

We shall note the type of production in which ele-ments of other types are hidden (multi-stage, sinceproduction with complex products and single pro-

PPRREEGGLLEEDDNNII RRAADD

RREEVVIIEEWW PPAAPPEERR

sloènija problematika uvijek da razloìti na dijelove,koji su istovjetni sa ovdje opisanom problematikom,a jednostavnija naprosto moè biti rje{avana kaoderivat ovdje diskutovanog.

Veliki broj proizvoda se danas izra|uje po sortama(npr. elektri~ni ku}anski aparati, postrojenja za gri-janje, elektromotori, transmisije). Antipod takvojproizvodnji je pojedina~na proizvodnja (proizvodnjapo narud`bi jednog odre|enog kupca). Na osnovutoga je mogu}e napraviti velike serije izrade i boljeiskori{}enje kapaciteta. Produktne karakteristikesorte su:

- jednovrsnost proizvoda po jednostavnosti strukture i materijalu,

- razli~itost proizvoda po obliku, boji i kvalitetu,

a produkcione:

- sli~nost proizvodne tehnologije,- visoka serijnost.

Po{to je sortna izrada orijentirana na trì{te, nijepotreban konkretan nalog kupca da bi se pristupiloizradi. Izrada dakle puni Skladi{te, koje stoji izme|u nje iKupca. Sortna i serijska izrada se kao pojmovi brka-ju i treba po}i od toga da je sortna izrada samospecijalan slu~aj serijske.

Slijede}a karakteristika uo~ene produkcije jenjena jednostepenost. "Stepen izrade" je pojam,koji treba shvatiti {to obuhvatnije, obzirom nauklju~eni pojam "radni hod". Na primjer, pogonvisoke pe}i i ~eli~ana mogu da se shvate kao(jedinstveni) "metalur{ki stepen izrade (stepentopljenja), po principu prisilnog toka izrade. U PPvelikog zna~aja ima prekid produkcionog toka,nastao me|uskladi{tenjem. Taj princip je dobrakonvencija za razlikovanje pojedinih stepeniizrade. Po tome bi jednostepena izrada bila onakod koje nema skladi{tenja do gotovog proizvo-da. Princip moè biti i kori{tena ma{ina. Ali,tada:

- manuelni radni hodovi (npr. u Montaì) se nikako ili samo okoli{no uzimaju u obzir,

- kod vi{ekratne upotrebe iste ma{ine tokom izrade, ovaj princip nema smisla.

Napokon, kao tre}i atribut uo~enog proizvodnogtipa imamo pojam paralena izrada. Usvoji}emo daje to onaj tip proizvodnje koji obuhvata mogu}nost


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duction), since complex problems can be always splitinto divisions which are equivalent with the problemsdescribed here and simple problems can be resolvedas a derivative of the enclosed discussion.

A large number of products today are made bysorts (for instance, electrical household devices,heating units, electrical motors, transmissions). Anantipode to such production is a single production(production by order) for a certain buyer. Based onthis it is possible to make huge series of produc-tion and better utilisation of capacities. Product char-acteristics of a sort are:

- uniformity of products by uniform structure andmaterial,

- variety of products by form, colour and quality,

while production characteristics are:

- similarity of production technology,- high number of series.

Taking into account that sort production is orientedtowards market, a concrete work order by the buyeris not necessary to commence production. Thereforeproduction is filling the stores with products whichlies between the production and the buyer. Sort andserial productions are often mixed as notions andone should start from the fact that sort productionsis only a special phase of serial production.

The next characteristic of the production is its single-stage nature. "Stage of production" is a notion thatshould be understood with as much coverage aspossible, taking into account the included notion of"production run". For instance, blasts furnace andsteel factory can be understood as a (single) "metal-working stage of production" (stage of melting) bythe principle of forcible production course. In PP,interruption of production course created by inter-stage storing has great importance. This principle isa good convention for making difference among sin-gle stages of production. In this case, a single stageproduction would be the production which does nothave storing before the final product. The principlecan be applied to a machine too. But in this case:

- manual production runs (for instance at assemblyline) cannot be taken or can only evasively betaken into account,

- this principle has no sense in multiple utilisationof the same machine during production.

Finally, as the third attribute of the noted production

type we have a notion of parallel production. Weshall accept that this is a type of production whichincludes possibility of alternative execution of pro-duction runs at several machines. This definition isoriented towards arrangement of machines along theline of production. According to this, parallel, singleproduction is achieved when an input enters the Asystem of production and an output is a series ofproducts, and when the same (parallel) is also hap-pening at the B and C systems. Therefore, struc-tures A, B and C need not be the same and there-fore the costs of production need not be the same.

3. FIELD of PP PROBLEMS

In accordance with VDI (193, page 167) PP is " asystematic search and establishment of productiongoals, preparation of production tasks and definitionof terms for the sake of achieving these goals."Notion correspondence of goals, goal activities andregulation of this activity are as follows:

Goal Action RegulationComplex goal Process in Politicalof organisation structure of regulations

Goal of one Functions of Organizationalorganisational this sub-system regulationssub-system

Partial goal of Operations of Technologicalorganisational this function regulations

function

Process, roughly presented, is a sum of func-tions which is defined by the input, internal func-tions and output (complex goal output). We seeproduction and utilisation of activities of one fac-tory as an entire process which, buy closeobservation, can be shown as structured frommultitude of (partial) processes which are alsostructured.

Should we divide the global area of acting of com-ponents of a factory to material and non-material, wecan differ the relevant processes in this manner:

- production process, if detailed, is a sum ofoperations for conversion of real input into real output of a factory production,

- information process is a sum of operations for representing this production process.

When a factory begins to function, productionprocesses begin to develop within its structure and

alternativnog izvr{enja radnih hodova na vi{ema{ina. Ta se definicija orijentira prema rasporeduma{ina du` toka izrade. Po tome, paralelnu, jed-nostepenu izradu imamo u slu~aju kad input ulaziu sistem izrade A, a izlazi niz proizvoda te kad seto isto (paralelno) de{ava i na sistemima, recimo,B i C. Pri tome struktura A, B i C ne moraju dabudu iste, pa ni tro{kovi izrade ne moraju, zato,da budu isti.

3. PODRU^JE PP PROBLEMATIKE

Prema VDI (1983, str. 167) PP je "sistemati~notraènje i utvr|ivanje ciljeva produkcije, pripremanjezadataka produkcije i utvr|ivanje tokova radi dosti-zanja tih ciljeva".Pojmovna korespondencija cilja, ciljnog dejstva iregulacije tog dejstva je ovakva:

CILJ DEJSTVO REGULACIJAKompleksni Procesi u strukturi Politi~ke

cilj organizacije regulacije organizacije

Cilj jednog Funkcije tog Organizacione organizacijskog podsistema regulacijepodsistema

Parcijalni cilj Operacije te Tehnolo{keorganizacijske funkcije regulacijefunkcije

Proces je, grubo predstavljen, jedan skup funkcija,koji je odrediv ulazom (inputom), internim funkcija-ma i izlazom (kompleksnim ciljnim outputom).Proizvodnju i kori{}enje u~inaka jedne fabrikeshvatamo kao ukupni proces, koji se bliìm posma-tranjem pokazuje struktuiranim iz jednog mno{tva(parcijalnih) procesa, tako|e struktuiranih.

Podjelimo li globalni prostor djelovanja komponena-ta fabrike na materijalni i nematerijalni, moèmoodgovaraju}e procese ovako razlikovati:

- produkcioni proces je, detaljno predstavljen,skup operacija za konverziju realnog ulaza u realni izlaz fabri~ke produkcije,

- informacioni proces je skup operacija za predstavljanje tog produkcionog procesa.

Kad fabrika stupi u dejstvo, unutar njene strukturepo~inju da se odvijaju radni procesi koji zavise od


- 114433 -

uslova, - zavise od fabri~ke situacije. Procesi, svo-jom dinamikom, vode ka ostvarivanju cilja fabrike, aliunutar njih, uglavnom evolutivno, koli~ine svih deter-miniraju}ih uticaja vremenom proizvode novekvalitete.Po{to Konstrukcija i Inènjering proizvodnje proces-no dolaze ispred Izrade, isklju~i}emo ih iz pojma"procesa proizvodnje" u ovom kontekstu.Formiranju procesa proizvodnje prethode analizezadatka i rada. Te dvije analize su analogne.Analizom proizvodnog rada se obuhvataju aspektiobavljanja zadatka, obzirom na situaciju, u kojoj sezadatak obavlja. Rad razlaèmo na aktivnosti, koje,u aktuelnoj situaciji, treba da budu obavljene da bise izvr{io doti~ni parcijalni zadatak, tj. uspje{noobavila operacija. Osnova za razdvajanje strukturnih od procesnihproblema organizovanja jeste u stanovi{tu s kogaproblemu prilazimo:

# jednom je to cilj djelovanja odre|enog orga-nizovanog subjekta, - pa se bavimo produkcionimstrukturama,

# a drugi put je to na~in postizanja cilja djelo-vanjem pa se bavimo procesima proizvodnje.

Kriterijumi za razlaganje procesa su, po logici, istikao i kod razlaganja zadataka.

Ako po|emo po faznom kriteriju, npr. parcijalni pro-cesi rada bi mogli biti:

* programiranje,* izvr{avanje i* kontrolisanje.

Ako usvojimo kriterij ranga, razlikovanje me|u parci-jalnim procesima odvaja:

* nare|ivanje od* izvr{avanja.

Razlikovanje po kriteriju svrhe (ciljnog objekta) raz-dvaja, npr:

* administriranje od* produciranja

(recimo, poslovo|a ispunjava obavezne rubrikeslu`bene dokumentacije - administrira, a potompodu~ava - upu}uje saradnike u problematiku nji-hovih zadataka, postiù}i cilj svog zadatka.).

Analiza procesa ide slijede}im koracima:

(1) Razgrani~avanje proizvodnog podru~ja u kome


- 114444 -

they depend upon conditions, - depend upon thesituation at the factory. Processes, by its dynamics,lead towards achieving the factory goals, but withinthem, mainly evolutional, the quantities of determin-ing effects produce new qualities in due time.Since construction and engineering come before pro-duction in a process, we shall exclude them from thenotion of "production process" in this context.Forming a production process is preceded by analy-sis of a task and work. These two analyses are ana-logue. Analysis of production work includes aspectsof carrying the task out taking into account the sit-uation in which a task is carried out. We dividework into activities which, in actual situation, shouldbe performed in order to carry out a particular par-tial task, i.e. to successfully perform the operation.Basis for separation of structural from process prob-lems of organisation lies in a standpoint from whichwe approach the problem:

# once it is a goal of acting of a certain organ-isational subject - and therefore we deal with pro-duction structures,

# sometimes it a method of achieving a goalby acting and we deal with production process.

Criteria for division of process, logically, are thesame as with division of tasks.

If we start from phase criteria, the partial processof work, for example, could be:

* programming* performing* controling

If we accept criteria of ranks, then distinction amongpartial process separates:

* orders from* performance

Distinction by criteria of goal (objective) separates,for instance:

* administrating from* producing

(For instance, a foreman fills in the mandatory columnsof official documentations - he administers, and theninstructs - directs his associates into problems of theirtasks thus achieving the objective of its task)

Analysis of a process follows the following pattern:

(1) Separation of production area in which the

se odvija proces(2) Razlaganje na parcijalna dejstva (funkcije,

operacije, aktivnosti i pokrete - zavisno od stepena razloènosti, koji nas zanima).

(3) Ustanovljavanje redoslijeda parcijalnih dejstava(4) Procjena duìne trajanja parcijalnih dejstava.

Razgrani~enjem proizvodnog podru~ja, koje }e pred-stavljati organizat, konstituira se organizacioni pro-blem. Bitno je da se to izvla~enje pojedinih tokovashvati kao problem upravlja~kog sistema fabrike,problem odlu~ivanja u fabrici. Naime, ome|eno pro-cesno podru~je, koje se izdvaja kao organizat,mora biti tako apstrahirano iz cjeline da sve orga-nizacione intervencije na njemu, barem ne pogor{ajuukupnu efikasnost fabri~kog sistema.

Drugi korak je stvarni po~etak analize proizvodnogprocesa. I ovdje se mora odlu~iti o kriterijumimarazlaganja te o njegovoj dubini. Za ilustraciju,nave{}emo primjer dekompozicije procesa nabav-ljanja, na pojedina~na, fazno razli~ita, parcijalnadejstva:

Nabavljanje

1. Pripremanje1.1. Pripremanje zahtjeva za nabavu1.1.1. Ispitivanje saop{tenja o potrebama1.1.2. Prora~unavanje koli~ina za naru~ivanje1.1.3. Ispitivanje stanja na skladi{tu1.1.4. Davanje broja zahtjevu1.2. Pripremanje naru~ivanja1.2.1. Traènje ponuda1.2.2. Obra|ivanje ponuda1.2.3. Odabiranje isporu~ilaca2. Realizovanje narud`be2.1. Izra|ivanje narud`be2.2. Davanje broja narud`bi/-isporu~iocu2.3. Upore|ivanje zahtjeva za nabavu sa

narud`bom2.4. Oda{iljanje narud`be3. Provjeravanje 3.1. Upore|ivanje potvrde porud`bine sa

narud`bom3.2. Nadziranje termina3.3. Ispitivanje ulaza robe3.4. Ispitivanje faktura3.4.1. Formalno ispitivanje3.4.2. Materijalno provjeravanje3.4.2.1. Upore|ivanje narud`be sa izvje{tajem o

prispje}u robe3.4.2.2. Upore|ivanje narud`be sa ulaznom

fakturom3.4.2.3. Upore|ivanje izvje{taja o prispje}u robe


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process is carried out(2) Division into partial activities (functions, opera-

tions, effects and movements-depending ondegree or reasons which are of interests for us)(3) Establishment of sequence of partial activities(4) Estimate of duration of partial activities

By separation of production field, which will representan organizate, an organisational problem is constitut-ed. It is essential that extraction of individual coursesis understood as a problem of management systemof a factory, a problem of decision-making in a fac-tory. Namely, restricted process field which is sepa-rated as an organizate, must be so abstracted for anentity that all organizational interventions at it at leastdo not worsen the total efficiency of factory system.

The second step is a real start of analysis of pro-duction process. One must decide here about cri-teria of division and about its depth. As an exam-ple, we shall give an example of decomposition ofprocess of procurement into individual, partial activ-ities, which are different by phases:

Procurement:

1. Preparation1.1. Preparation of requests for procurement1.1.1. Testing reports on needs1.1.2. Calculation of quantities for orders1.1.3. Investigation of status at the stores1.1.4. Assigning a number to a request1.2. Preparation for ordering1.2.1. Requesting offers1.2.2. Selection of suppliers2. Realisation of an order2.1. Making an order2.2. Assigning a number to an order/supplier2.3. Comparison of a request for procurement

with an order2.4. Sending an order out3. Control3.1. Comparison of confirmation of order form

with the order3.2. Monitoring the delivery terms3.3. Inspection of entry of goods3.4. Control of invoices3.4.1. Formal testing3.4.2. Material checking3.4.2.1. Comparison of order with a report on

arrival of goods3.4.2.2. Comparison of order with entry invoice3.4.2.3. Comparison of report on entry of goods

with entry invoice4. Preparation and carrying out booking

4.1. Preparation of documentation4.2. Booking

Chronological sequence of partial activities shouldresolve the problem of structure of their networkwhich is a base for their allocation (planning).Different development methods are used for this pur-pose (listing, flow diagram, block tests, block dia-grammed, priority matrices, priority graphs).The fourth step is actual programming the processby synthesis of partial activities.

The PP is composed as follows:

Long-tterm process which in fact is definition of fieldof production (Festlegung der Productfelder).Middle-tterm process which includes the followingproblems:

i. Programming a product

Programming a product must run systematically.Process is carried out through organisational com-ponents related to individual partial tasks andthrough solutions which, as output information,these components direct, in form of their functions,through a system, to next components in the cours-es of process. Initial information speak about mar-ket and about the enterprise itself (factory).

The entire course is carried out at certain corre-spondence with analogue meta-course - planning byan enterprise. The main part of the process isincluded by projecting a product. Technology of aproduct is defined within this job. Above all, basedon potential of an enterprise, field of research isestablished within which it is supposed that thefuture product could be defined. Central task in pro-jecting a product is to find a product with an aimto outline a product. This is assigned to a teamcomposed of experts for particular field and teamof analysts of potential of an enterprise.

If a concept is accepted, a project organisation forrealization of a product is formed.

ii. Projecting a production investment

Projecting an investment is a techno-economic prob-lem. We shall deal here with economic calculationsof economy of investment for construction of a newor reconstruction (of a part) of existing production.The purpose of investment calculation is to compareeconomy of possible variants of achieving goal ofsuch an investment. For example, one workshop, in

sa ulaznom fakturom4. Pripremanje i izvr{avanje knjiènja4.1. Pripremanje dokumentacije4.2. Knjiènje

Hronolo{ki redoslijed parcijalnih dejstava treba darije{i problem strukture njihove mreè, koja je osnovza vremensku alokaciju (planiranje). Za to se koristerazli~ite razvijene tehnike (listinzi, dijagrami toka, bloktekstovi, blok dijagrami, matrice prioriteta, grafovi pri-oriteta).êtvrti korak je stvarno programiranje procesa, sin-tezom parcijalnih dejstava.

Proces PP je komponiran ovako:Dugoro~no, to je ustvari odredjivanje podru~japroizvoda (Festlegung der Produktfelder).Srednjero~no, {to obuhvata slijede}e probleme:

i. Programiranje proizvoda

Programiranje produkta mora te}i sistematizirano.Proces se odvija preko organizacionih komponenti,odgovornih za pojedine parcijalne zadatke, a krozrje{enja, koja, kao izlazne informacije, te kompo-nente proslje|uju, u vidu svojih funkcija, kroz sistem,slijede}im komponentama u procesnom toku.Polazne informacije govore o trì{tu i o samom pre-duze}u (fabrici).

îtav tok se odvija u odre|enoj korespondenciji saanalognim metatokom - planiranjem preduze}a.Glavni dio procesa je obuhva}en projektiranjemproizvoda. U okviru tog posla se defini{etehnologija proizvoda. Prije svega, se, na osnovupotencijala preduze}a, odre|uje podru~jeistraìvanja, u kojem se pretpostavlja da }e semo}i definirati budu}i produkt. Centralni zadatak uprojektiranju proizvoda jeste nalaènje proizvoda sciljem da se koncipira proizvod. To se povjeravatimu sastavljenom od eksperata za doti~nopodru~je i analiti~ara potencijala preduze}a.

Ako se koncept usvoji, formira se projektna organi-zacija za realiziranje produkta.

ii. Projektovanje proizvodne investicije

Projektovanje investicije je tehnoekonomski problem.Ovdje }emo se pozabaviti ekonomskom ra~unicomisplativosti namjeravane investicije u izgradnju noveili rekonstrukciju (dijela) postoje}e proizvodnje.Svrha investicijskog prora~una jeste da se uporediekonomi~nost mogu}ih varijanti potizanja cilja teinvesticije. Na primjer, moè jedna radionica, u kojoj


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se izvr{avaju nalozi obrade, planirati nabavku jednealatne ma{ine. Pri tome treba izabrati povoljniju oddvije varijante.

Na to pitanje moè da se odgovori samo puteminvesticionog prora~una.U tom prora~unu fungiraju slijede}e osnovneveli~ine:n: - trajanje iskori{tavanja, to zna~i broj godina, za

vrijeme kojih nabavljeni ure|aj stoji u upotrebi.Ei: - godi{nji prihodi, koji su omogu}eni upotrebom

ure|ajaAi: - godi{nji izdaci, obuhvataju}i investirane iznose

i teku}e pogonske izdatkep: - kamatna stopai: - indeks godine trajanja kori{tenja, od 1 do n.

Za veli~inu A treba primjetiti da je njen iznos vrlopromjenljiv iz godine u godinu trajanja kori{tenja. Napo~etku je to jedna velika nabavljena vrijednost, au kasnijim godinama bi bilo nu`no nju podvr}itro{kovnim revizijama. Teku}i pogonski izdacime|utim ~ine jedan pravilni, po iznosu manji, redveli~ine isplata.

Osnovna formula po~iva na slijede}em rezonu: Upo~etnom roku investicionog projekta preduzetnikinvestira iznos A0. Taj iznos }e njemu tokom traja-nja kori{tenja biti amortiziran i ukama}en i to krozgodi{nje diferencije Ei - Ai. [to su diferencijeve}e, kamatna stopa p, s kojom on ra~una, moèbiti ve}a. Kad su diferencije Ei - Ai dovoljnovelike, tada ne samo da se amortizira i ukamatiiznos A0, ve} rezultira jo{ i dodatna dobit, ~ijasada{nja vrijednost se ozna~ava kao vrijednostgotovine B. Za jasno razlikovanje od stati~nihinvesticijskih prora~una i od prora~una tro{kova,treba znati da ovdje u Ai vrijednostima nematro{kova za kamate i amortizaciju. Amortizacija iukama}ivanje se de{avaju u diferencijama Ei - Ai.Ai vrijednosti sadràvaju, pored investirane vri-jednosti A0, (izdaci za reviziju postrojenja, dopu-


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which orders for processes are carried out, can planprocurement of one machine tool. In that case oneshould choose more favourable solution out of two.

Only an investment calculation can answer thisquestion.The following basic values appear in this calcula-tion:n - : duration of experience, it means number of

years during which the procured machine isbeing used,

Ei: - annual income which is achieved by utilisation of a machine,

Ai: - annual expenditures including investmentamounts and current running costs,

p: - interest rate,i: - index of year of duration from 1 to n.

For the value A one should notice that it is veryvariable from year to a year of duration of utilisa-tion. At the beginning it was a great procurementvalue and later it would be necessary to subject itto expenditure revisions. Current production costs,however, represent one regular order of magnitudeof profit, by value.

The basic formula rests on the following reasons: Anentrepreneur invests an amount AO at the beginningperiod of investment project. This amount will bedepreciated and interest rated through annual differ-ence of Ei - Ai. The greater differences are, theinterest rate "p", which he is counting upon, can begreater. When differences Ei - Ai are big enough,then not only the value AO is depreciated and inter-est rated, but it yields additional profit the value ofwhich is designated as cash value B. For clear dis-tinction of static investment calculations from costcalculations, one should know that here in Ai expen-ditures the costs for interest rates and depreciationare not included. Interest rate and depreciation arehappening in differences Ei - Ai. The values Ai con-tain, beside invested values of AO (costs for revision

Varijanta 1 Varijanta 2Nabavljena vrijednost 300 000.- 350 000.-Prosje~ni godi{nji izdaci radionice 60 000.- 55 000.-Prosje~ni godi{nji prihod 120 000.- 130 000.-

Variant 1 Variant 2Procurement value 300 000.- 350 000.-Average annual expenditures ofthe workshop

60 000.- 55 000.-

Average annal income 120 000.- 130 000.-

njuju}e nabavke za postrojenja) i teku}i pogonskiizdaci (npr. plate za opsluìvanje i odràvanje,izdaci za sirovi materijal, potro{ni materijal, energi-ju itd).

iii. Make or Buy?

"Kupiti ili sam proizvoditi?", to je pitanje kojese postavlja uvijek tamo gdje jedna organizaci-ja nudi svoje u~inke drugoj. Organizaciono, radise podjeli rada izme|u internih i eksternihdobavlja~a.

Za odgovor postoje slijede}i dominantni argumenti:

1. za proizvodnju vam treba ne{to ~ega nemate, ane moète ga ni stvoriti jer vam nedostaju perso-nalne, materijalne i informacione podloge.2. psiholo{ki kompleks vas goni (1) da proizvoditeu domenu svoje nekompetentnosti ili (2) da se sma-trate nekompetentnim za proizvodnju pa to, ~eganemate, kupujete.3. pove}anje zaposlenosti ljudi.4. pove}anje zaposlenosti kapitala.5. prezaposlenost.

Prakti~ni zna~aj make-or-buy odluka zavisi (1) od{irine ponude roba i servisa i (2) od mogu}nostipreduze}a da apsorbira svoje fiksne tro{kove. Umodernoj trgovini je ponuda sve ve}a i postala jeglobalna.Ekonomski aspekt jedne make-or-buy odluke je prvo-razredno zna~ajan. On je izraèn kroz komponenteuvjetovane mjestom produkcije:

- tro{kovi plata,- potencijal radnika,- produktivnost,- mogu}nosti prostorne ekspanzije,- zakoni,- takse,- carine,- netarifne trgova~ke prepreke.

"Economy of scale" tako|e predstavlja obzir kodovog odlu~ivanja. To je osobito va`no malim i sred-njim fabrikama koje u oblasti specijalnih stvari (veli-ka proizvodna postrojenja, know-how, specijalniproizvod) ne mogu ekonomski pro}i bez pouzdanogeksternog partnera.

Finansiranje je slijede}i obzir. Uz to ide problemati-ka potrebnog vremena. Tu se ~esto de{ava da prvo-bitna labava kooperacija pre|e u Joint-venturesodnos.


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of machine, additional procurement for machine) andcurrent production expenditures (salaries for servic-ing and maintaining, expenditures for raw materials,consumable materials, energy and so on).

iii. Make or Buy?

"Buy or make it yourself?", this is a question whichis always raised where one organisation is supply-ing its outputs to other organization. Organisationally,one is dealing here with division of work amonginternal and external suppliers.

The answers exist for the following dominant argu-ments:1. One needs to produce something that one doesnot have and one cannot make it since one lackspersonnel, material and information basis. 2. Psychological complex forces you (1) to producewithin domain of your competencies or (2) to con-sider yourself incompetent for production and buywhat you do not have.3. Increase of employment of people.4. Increase of employment of capital.5. Over-employment.

Practical meaning of a make-or-buy decisiondepends upon (1) width of supply of goods andservices and (2) possibility of an enterprise toabsorb its fixed expenditures. In modern trade sup-ply is becoming greater and it has become global.An economic aspect of a make-or-buy decision hasthe first class importance. It is expressed throughcomponents which are conditioned by the place ofproduction:

- expenditure of salaries,- potential of workers,- productivity,- possibilities for space expansion,- laws,- taxes,- customs fees,- non-tariff trade obstacles.

"Economy of scale" also represents a considerationwith this type of decision. This is particularly impor-tant for small and medium-size factories which inthe domain of special articles (big production plants,know-how, special products) cannot run economi-cally without a reliable external partner.

Financing is the next consideration. It is followed bynecessary time. It happens often that the originalloose cooperation turns into a joint-venture relation.

U Inènjeringu proizvoda su mnogostruke buy-mogu}nosti. Kupovina je mogu}a kod istraìva~ko-razvojnih instituta te na visokim {kolama, a posred-nici mogu biti dràvni ili komorski organi. Pogotovoje zna~ajan problem konstrukcije proizvoda. Zbogsvog tehni~kog standarda industrijski proizvodi danaspokazuju zna~ajno manje signifikantnih razlika negoprije trideset godina. Nije samo standardizacijaproizvoda tome doprinijela, ve} i standardizacijaproizvodnih sredstava i proizvodnih metoda. Zbogtoga je funkcionlni dizajn proizvoda su{tinskizna~ajan za identitet proizvo|a~a.

U inènjeringu proizvodnje kupuje se sve ~e{}e odkonsultanata za tehnologiju proizvodnih sistema, jerje kompleksnost te tehnologije sve ve}a. Naravnoda najvi{e mogu}nosti za kupovinu leì u Izradi, sli-jede}im redom:

- sirovi materijal,- komponente, poluproizvodi- za standardnu ili katalo{ku proizvodnju- za proizvodnju specifi~nu prema kupcu- uslovljeno tehnikom postupaka- uslovljeno nekom specijalnom primjenom- sklopovi,- gotovi proizvodi,- lonposlovi/konfekcioniranje.

Napokon i u Marketingu je mogu}e kupovanje (odkonsultanata i reklamnih agencija do trgova~kemreè i skladi{ta drugih).

Kratkoro~no programiranje proizvodnog programa jeodre|ivanje proizvoda (uklju~ivo koli~ine) koje trebaproizvesti u sukcesivnim planskim periodima na, odInènjeringa odre|enim, fabri~kim sredstvima.

LITERATURA - REFERENCE

[1] Gillsen, E.: Integrierte Produktionsplanung.Springer Verlag, Berlin, 1988.

[2] Hess, W., Tschirky, H., Lang, P: Make or Buy,Verlag Industrielle Organisation, Zuerich, 1989.

[3] Milo{, A.: Organizacija, Svjetlost, Sarajevo, 1991.

[4] Sziver, P.: Dynamische Investition-srechnungsver-fahren, u: Technische Rundschau Nr. 15 od 10.aprila 1984.


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In engineering of a product there are multiple buy-possibilities. Buying is possible with research-devel-opment institutes and at high schools and mediatorscan be state or chamber of commerce organs.Problem of construction of a product is of specialimportance. Due to its technical standards, the indus-trial products today show meaningfully less significantdifferences than thirty years ago. Standardisation ofproduct does not contribute to it only, but also stan-dardisation of production means and productionmethods. That is why functional design of a productis essentially important for identity of a producer.

In engineering of production purchase from consul-tants for technology of production systems appearto be more frequent, since complexity of this tech-nology is becoming greater. Of course, the greatestpossibilities for purchases rest with production in thefollowing sequence:

- raw material,- components, semi-products- for standard or catalogue production- for production specified for a buyer- conditioned by technique of procedures- conditioned by some special application- assemblies- finished products- loan jobs/ready made clothes

Finally, it is possible to buy in Marketing (from con-sultants and advertising agencies to trading networksand stores of others)

Short-tterm programming a production programme meansdefinition of a product (including quantities) whichshould be produced in successive scheduled periodson factory equipment designated by the engineering.