QUY TRÌNH TÍNH TOÁN VÀ HƯỚNG DẪN SỬ DỤNG PHẦN MỀM LỰA CHỌN CHI (2)

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H THNG HA CC CHI TIT MY V CM CHI TIT MY TIU CHUN

QUY TRNH TNH TON V HNG DN S DNG PHN MM LA

CHN CHI TIT MY TIU CHUN MITCalc

Chng ny gii thiu quy trnh thit k la chn cc chi tit my tiu chun dng s v tnh trn MITCalc. Mi chi tit c tiu chun cc thng s khc nhau, tuy nhin, quy trnh la chn chi tit khc nhau trong mt s trng hp s tng t nhau. thc hin c phng php thit k la chn mt cch nhanh chng, hiu qu, ta c th kt hp vi phn mm ng dng v tra cu, tnh ton.

Hin nay, Vit Nam v Th gii c kh nhiu phn mm tnh ton, tra cu thng s chi tit my. V d: phn mm tra cu thp hnh (Vit Nam), phn mm tra cu ln (SKF), phn mm tnh ton chi tit my, MITCalc hoc phn tnh ton c t trong tin ch ca cc phn mm thit k nh Autodesk Inventor Trong , phn mm MITCalc tnh ton thit k c hu ht cc chi tit my thng dng, cc d liu ca phn mm cng da trn c s d liu ca cc tiu chun thng dng nh ISO, DIN, ASTM, ANSI, JIS,V vy, ta s xy dng quy trnh la chn cc chi tit my tiu chun da vo phn mm tnh ton chi tit my MITCalc 1.5.

MITCalc (Mechanical, Industrial and Technical Calculations) l mt h thng thit k m trong Microsoft Excel do cng ty Ing. Miroslav Petele, Cng ha Sc thc hin. MITCalc gm c tnh ton thit k v kim nghim cho nhiu chi tit my khc nhau nh: bnh rng, ai, xch, trc, chi tit ghp trc, cht Phn mm ny c tin cy, chnh xc cao v trn ht l ng dng hu ch cho qu trnh thit k chi tit, gii quyt mt v!n k" thut hoc tnh ton mt ni dung c kh m khng cn phi c kin thc chuyn su nh cc nh thit k thng thng.

Nguyn bn ci t ca MITCalc l ting Anh, v vy, chng ti Vit ha nh#m gip $ cng vic tham kho, s% dng c d& dng, nhanh chng hn.

Giao din la chn chc nng ca phn mm MITCalc 1.5.

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Quy trnh thit k la chn cc chi tit tiu chun c phn lm 2 phn:

Phn 1: S quy trnh v gii thch cc bc trong quy trnh

Phn 2: 'ng dng phn mm MITCalc thc hin cc bc thit k la chn

1 Quy trnh thit k la chn chi tit ghp

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Hnh 1 Chi tit ghp tiu chun trong MITCalc

1.1. Quy trnh la chn cc chi tit trong mi ghp ren

Cc chi tit trong mi ghp ren c mi lin h v hnh dng, kch thc ren, ng knh l(p ghp gia trc v l. V vy, cc chi tit ny c la chn trong mt quy trnh. Cc thng s c tiu chun ha trong nhm chi tit ny l: Dng ren, ng knh ren, bc ren.

Quy trnh la chn cc chi tit trong mi ghp ren c thc hin nh sau:

Bc 1: La chn loi bulng

Ngi thit k s da vo cc yu cu v hnh dng bn ngoi ca t!m ghp m quyt )nh s% dng bulng, vt hay vt c!y.

Theo tiu chun ISO 1891-2009 quy )nh hnh dng v tn loi cc loi bulng, v cc chi tit h tr, tiu chun ISO 225-2010 quy )nh cc k hiu ca thng s hnh hc cc loi bulng.

Bc 2: La chn vt liu(cp bn) ca bulng

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Sau khi la chn loi bulng/vt/ vt c!y, ngi thit k s xem xt la chn c!p bn cc chi tit ny da vo cc yu cu k" thut t ra. Trong tiu chun ISO 898-1:2009 (bulng b#ng thp), ISO 8839:1986 (Bulng b#ng kim loi mu) quy )nh v c tnh v l tnh ca cc chi tit ny. Trong qu trnh la chn, ngi thit k s la chn nhng chi tit c c tnh th*a mn yu cu t ra. Thng thng, ngi thit k s xc )nh vt liu ch to bulng v sau s tra c tnh theo tiu chun thch hp.

Gii thch thm v k hiu ca cc c!p bn bulng/ vt/ vt c!y: bn ca cc chi tit trn lm b#ng thp theo tiu chun ISO c th hin qua cc con s trn k hiu ca chng. K hiu bao gm hai ch s c cch nhau b#ng d!u ch!m. Ch s bn tri ca d!u ch!m khi nhn thm 100 chnh l gi tr) ca bn ko theo n v) MPa trong khi con s bn phi l 1/10 ca t+ s gia bn ko v gii hn chy .

Sau khi la chn kch thc ren, ngi thit k s xc )nh cc kch thc chi tit da vo cc tiu chun ca loi bulng/ vt/ vt c!y c chn.

Sau khi xc )nh chi tit c th, ngi thit k s phi tin hnh kim nghim li cc ng su!t sinh ra v so snh vi ng su!t cho php.

Trong bc ny, chng ta c th s% dng cc phn mm thit k chi tit my t ng tnh ton kim nghim.

Bc 5: La chn ai c

ai c l chi tit kt hp vi bulng l(p ghp mi ghp c )nh tho ri c. Vic

la chn ai c cng kh quan trng trong kt c!u ghp b#ng ren.

Thng thng, vic la chn ai c s c thc hin cng vi la chn bulng. ai c

v bulng c cng dng ren, ng knh ren, bc ren... mi l(p ghp vi nhau c.

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Hnh 2 Quy trnh la chn cc chi tit mi ghp bng ren

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Vic la chn ai c c th l hnh dng ca n, ty vo iu kin lm vic, hnh dng

b phn my sau khi ghp m ta c th chn hnh dng ai c thch hp. V d: ai c lc gic,

ai c vung, ai c c cnh...

thc hin vic la chn ai c tiu chun, ngi thit k tham kho tiu chun ISO

1891-2009 la chn ai c tiu chun ha.

ai c s ch)u lc xit khi l(p vi bulng, tiu chun ISO 2320-2008 qui )nh lc xit v

moment xo(n ng vi ng knh ren ca cc nhm ai c.

V c tnh, mi ghp t hiu qu, c tnh ca bulng v ai c phi tng ng

nhau. Bng sau cung c!p cho ngi thit k k hiu nhm ai c v s kt hp ca bulng v ai

c c c tnh tng ng.

K hiu nhm ai c l mt ch s b#ng 1/100 ca ti trng cho php.

V d: nhm 4 ngh,a l ti trng cho php l 4 x 100 = 400 MPa

Cc tnh ch!t c th ca tng loi ai c, ta c th tham kho tiu chun ISO 898-2:1992.

Bc 6: La chn vng m

Vng m l vng thp m*ng t gia ai c v chi tit ghp, dng . bo v b mt chi tit ghp, ng thi lm tng din tch tip xc ca b mt chi tit ghp vi ai c. Vng m c nhiu loi, ph/ng vnh hoc cc hnh dng khc Vic la chn vng m s ph thuc vo ng knh bulng v yu cu k" thut. Hin nay, ch0 c vng m ph/ng c t chc ISO tiu chun ha. V vy, trong phn ny s ch0 trnh by quy trnh la chn vng m ph/ng.

Bng 1 Hng d1n s kt hp bulng/vt/vt c!y vi ai c

K hiu nhm ai c lm b#ng thp

Nhm 4 5 6 8 10 12

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Ti trng cho php, MPa 400 500 600 800 1000 1200

Kt hp Bulng/ Vt/ vt c!y v ai c b#ng thp

Nhm Bulng 3.6 4.6 4.8 5.6 6.8 8.8 10.9 12.9 (14.9)

Nhm ai c khuyn dng 4 4 4 5 6 8 10 12 14

Ghi ch: C th s dng nhm ai c cao hn so vi nhm bulng

Theo tiu chun ISO 10644:2009, kch thc vng m l(p vi chi tit c ren s ph thuc vo ng knh ren. Sau khi la chn c chi tit ren (bulng, vt, ai c), ta s s% dng tiu chun trn la chn vng m cho thch hp.

QUY TRNH L2A CH3N CC CHI TI4T GHP B5NG REN (BULNG/VT/VT C6Y,

AI 7C, VNG 8M) TRN PH9N M:M MITCALC 1.5

Chn chc nng thit k mi ghp ren:

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Giao din ca mun thit k mi ghp bulng:

Bc 1: La chn loi chi tit ghp

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Ghi ch: + Mi ghp bulng khng c ai c : Vt c!y

+ Mi ghp bulng c ai c: Bulng hoc Vt

Vt c!y c 2 loi:

Bulng c 2 loi:

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Bc 2: La chn vt liu (Cp bn) ca chi tit ghp

Ghi ch: C 3 tiu chun vt liu l ISO, SAE v ASTM, ta chn ISO. Sau , ta chn

c!p bn ca bulng theo ISO:

Bc 3: La chn kch thc ca chi tit ghp

Chn kiu ren v bc ren:

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Chn ng knh ren:

Sau khi chn ng knh ren, phn mm s xc )nh cc kch thc cn li ca ren theo tiu

chun ISO

Bc 4:Tnh ton kim nghim iu kin bn

+ Nhp lc tc dng:

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+ Kt qu tnh ton:

Chi tit th*a mn iu kin bn khi cc gi tr) ca h s an ton ln hn h s an

ton cho php m ngi thit k yu cu. Trong phn mm MITCalc 1.5, gi tr) khng th*a s c

mu *.

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Bc 5, 6: La chn ai c v vng m cho mi ghp

Sau khi la chn cc thng s, ngi thit k c th bit c cc kch thc cn li

ca bulng/vt/vt c!y, ai c v vng m s% dng cng vi bulng/vt/vt c!y c chn b#ng

cch xu!t d liu CAD

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1.2 Quy trnh la chn inh tn

inh tn l mt loi chi tit dng ghp cc vt th vi nhau. Chng thng c s% dng trong xy dng v sn xu!t. m bo inh tn uc s% dng ng mc ch, vic la chn inh tn thch hp l quan trng trong qu trnh thit k. Ngi thit k s so snh cc loi inh tn da vo cc gi tr) v ln, kh nng chng n mn v vt liu lm inh tn.

i vi inh tn, cc thng s tiu chun gm c:

Hnh dng inh tn

ng knh inh tn

Chiu di inh tn

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Hnh 3 Quy trnh la chn chi tit ghp bng inh tn

Bc 1: La chn loi inh tn

Vic la chn loi inh tn ph thuc vo kh nng ch)u ti trng v yu cu b mt l(p ghp. Nu yu cu b mt ph/ng, ta chn inh tn u chm v nu khng yu cu v b mt, ta chn inh tn thng.

Bc 2: La chn vt liu cho inh tn

La chn inh tn c lm b#ng vt liu cng vi vt liu ca vt cn l(p ghp. V d, nu bn l(p ghp hai t!m thp vi nhau, bn hy dng mt inh tn b#ng thp. C g(ng tm mt

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inh tn lm b#ng hp kim tng t nu c th. Nu bn chn mt inh tn s% dng cho vt b#ng nhm, bn hy chn mt inh tn lm b#ng hp kim nhm.

Theo ISO, inh tn s% dng trong c kh v xy dng thng lm b#ng thp ccbon th!p.

i vi ng dng v trng lng, n mn hoc s thng nh!t vt liu, in tn c th lm b#ng

ng (+hp kim), nhm (+Hp kim),..

Bc 3: Chn chiu di cho inh tn

Theo tiu chun v inh tn, chiu di ca inh tn (k hiu l l) c o t cnh di

ca u n 0nh ca thn inh tn. V d: K hiu kch thc ca inh tn theo tiu chun ISO

15973:2000.

Hnh 4 Hnh dng inh tn

Chiu di ca inh tn nn b#ng chiu dy ca hai vt th bn s ghp cng 1.5 ln

ng knh ca thn inh tn. V d: Mt inh tn c ng knh 4mm s c s% dng ghp hai

t!m ph/ng dy 2mm s c chiu di l : l = 2x2+4x1.5 =10mm.

Bc 4: La chn ng knh ca inh tn

inh tn phi ghp kn vi l l(p ghp. Bi v cc l ny c khoan trc nn vic la

chn inh tn c cng ng knh vi l l quan trng. Mt inh tn qu ln s khng l(p ghp

c, trong khi mt inh tn qu nh* s khng l(p ghp an ton.

Theo tiu chun ISO 1051:1999, ng knh danh ngh,a tiu chun ca inh tn l:

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La chn 1: 1, 1.2, 1.6, 2, 2.5, 3, 4, 5, 6, 8, 10, 12, 16, 20, 24, 30,36

La chn 2: 1.4, 3.5, 7, 14, 18, 22, 27, 33

Bc 4: Tnh ton kim nghim inh tn theo iu kin bn

Kim nghim theo theo bn c(t v dp.

1.3 Quy trnh la chn cht nh v

Vic la chn cht )nh v) ph thuc vo cng dng, ng knh l, v) tr t cht. Ngi

thit k c th la chn loi cht, sau tham kho cc kch thc, k hiu, vt liu theo cc tiu

chun ISO tng ng.

Cc thng s tiu chun ca cht )nh v) gm c: Hnh dng cht, ng knh cht v

chiu di cht

Bc 1: La chn hnh dng cht

Ty vo iu kin lm vic v yu cu v b mt, ta chn loi cht thch hp. Theo ISO,

cc loi cht tiu chun gm c: cht tr, cht tr c vai, cht l xo, cht tr c ren, cht tr c

rnh, cht cn,...

Bc 2: La chn vt liu cho cht

Vic la chn vt liu cho cht ty thuc vo ti trng tc dng. Ty vo ln ca ti

trng, loi ti trng m ta chn loi vt liu c bn, cng cho thch hp.

Thng thng, vt liu lm cht l Thp kt c!u, thp hp kim, thp c, thp ti, gang,

hp kim nhm, hp kim ng,...

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Hnh 5 Quy trnh la chn cht

Bc 3: La chn kch thc cht

Kch thc tiu chun ca cht l ng knh cht v chiu di cht. Vic la chn kch

thc ty thuc vo ng knh trc hoc chiu dy chi tit ghp.

Bc 4: Tnh ton kim nghim bn cho cht

Sau khi xc )nh kch thc ca cht, ta tnh ton kim nghim bn cho cht theo la

c(t v moment xo(n.

QUY TRNH L2A CH3N CH7T NH V TRN PH9N M:M

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+ Chn chc nng tnh ton thit k cht )nh v):

+ Giao din ca phn tnh ton thit k cht:

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H TH NG HA C`C CHI TI T M`Y V C M CHI TI T M`Y TIU CHU N

B c 1: Ch n lo i ch t: Ta ch n lo i ch t theo tiu chu n ISO

B c 2: Ch n v t li u c a ch t

B c 3: Ch n kch th c ch t

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QUY TRÌNH TÍNH TOÁN VÀ HƯỚNG DẪN SỬ DỤNG PHẦN MỀM LỰA CHỌN CHI (2)