CC CH THIT K SN PHM TRONG CNG NGH P PHUN

CC CH THIT K SN PHM TRONG CNG NGH P PHUN

TRNG H S PHM K THUT HCMKHOA O TO CHT LNG CAO

CC CH THIT K SN PHM TRONG CNG NGH P PHUN

BO CO

GVHD:Ths. TRN MINH TH UYN SVTH : L VN TI MSSV:11144168

CC CH THIT K SN PHM TRONG CNG NGH P PHUN Trong qu trnh phn tch sn phm, nn p sut in y cao hay sut hin cc khuyt tt nh : sn phm khng in y, bavia, xut hin ng hn Th khng nn thay hnh hc sn phm m u tin thay i cc thng s gia cng hay chn li vt liu nha. Nu thay i cc thng s gia cng vn khng c ci thin c vn trn th nn thay i hnh hc ca chi tit.Thay i s nh hng n nhiu chi tit lp, tnh thm m, bn ca chi tit

GM C 8 VN CH N :1.GC THOT KHUN i vi sn phm c gn, vu li, rnh su hay c b mt vt ta nn thit k gc vt theo hng m ca khun sn phm c th thot khi khun 1 cch d dng.Chi tit khng gc vt Chi tit c gc vt

Saing

Saing

Saing

th gip thit k gc vt cho ph hp. Gi tr gc vt ph thuc vo c tnh co rt ca nha v chiu cao vt (thng t 0.25-30) . Khi khng thit k gc thot khun hay thit k khng ng th ma st gia b mt sn phm v mt khun s rt ln. khi sn phm s b kt li trong khun, hay nu y c ra ngoi th sn phm cng b li bi lc cht y qu ln lm thn b mt.

2.B DYa.Hiu qu thit k: Rt ngn thi gian chu k p phun v ch to khun Gim gi thnh sn phm v khun Tit kim vt liu m vn hiu qu Trnh cong vnh, l kh, vt lm, ng hn

y l cc khuyt tt thng gp khi thit k b dy sn phm khng ph hp

Nu phn vt liu bn trong li sn phm ngui chm hn vt liu bn trn b mt, s to ra s co rt khng ng u sn phm. S co rt ny s gy ra cng vnh sn phmSn phm b cng vnh

Khc phc s cong vnh cn thit k b dy ng nht, sau y l phng php gip thit k sn phm ng nht: to vng chuyn tip gia hai vng c b dy khc nhau

b.Mt s iu cn ch : Ty thuc vo tng loi sn phm m b dy s khc nhau. Tuy nhin trong mt s trng hp cn cch in, chu nhit, chng mi mn th c th dy hn. B mt ca sn phm lm cng mng khi c th v cng ng u cng tt gip vic in y lng khun v s co rt ca nha lng s tt nht, ng sut trong cng gim ng k. Khi nhn thy sn phm khng b dy th ta c th: Tng b dy Dng vt liu khc bn hn To cc gn tang cng hoc cc gc bo tang bn Vic m bo sn phm c b dy ng u l rt quan trng v thi gian ng cng ca sn phm l khc nhau ti nhng ni c b dy khc nhau. Khi khng m bo c u ny th cc khuyt tt rt d xy ra. Tuy nhin ta c th gim bt hng hc bng vic thit k cc on chuyn tip.

Cc cch thit k b dy ng nht

3.GC BOa.Hiu qu thit k: Sn phm c lm ngui ng u Gim kh nng sn phm b cong vnh Gim s cn dng Gim s tp trung ng sut Nha lng d in y lng khun b.Gii php thit k gc bo: Bn knh bo nm trong phm vi t 25% n 60% b dy sn phm, nhng tt nht l 50%. Bn knh ngoi nn bng bn knh trong cng thm b dy sn phm: R=r+T

Mt khi u ny khng c tha mn th sn phm d b cong vnh bi s ngui khng u, s co rt khng u. thm vo th ng sut tp trung cng tng ln. gi cho b dy sn phm ng nht th phi thit k bn knh cong c 2 gc.

Qu mngQu dy

Cc khuyt tt thng gp phi:

Hnh (a) l vt nt.Hnh(b) l vt kha hnh.Hnh (c) l np gp b mt.

4.GNa.Hiu qu thit k: Gip tng bn v tng kh nng chng un ca sn phm. b.cc loi sn phm cn gn tng bn:c.Thit k gn:Thit k sao cho b dy sn phm cng mng cng tt. ( cng vng tng khi khong cch gn gim li)B dy, gc cn, cao lin quan n nhau, nu b dy gn qu ln dn n vch lm v gc cn qu ln s kh khn in y khun nghing mi bn khong 10, b dy y gn max l 0.8 dy sn phm ni t gn (0.5-0.8)Gn tng bn phi nm thng hng vi hng m khun

d.Mt s yu cu cn ch : B dy ca gn khng vt qu b dy t gn nhng ch vt liu t co rt v khng nh hng n tnh thm m th c th dy hn 1 cht. B dy gn cn tc ng n s u tin dng chy trong qu trnh p phun (nguyn nhn a n cc khuyt tt ng hn v r kh).

Cc thng s hnh hc ca gnTrong : B dy gn: t Chiu cao gn: H Bn knh gc bo: r Gc nghing: Khong cch gia cc gn: S

Cc gn nn thit k song song, khong cc gia cc gn nn bng t nht 2 ln b dy. Gip gim bt cc rnh lm ngui v h thng thot kh trong khun. Cc gn nn t dc theo 1 hng t cng vng tt (nn t dc).

Cc kiu t gn Ngoi vic thit k gn tng bn, ta c th thay th gn bng cc np gp tng cng vng v tnh thm m.

Cc kiu np gp Khi thit k gn cho nhau th ch chuyn tip nn l 1 im m bo cng v kh nng chng li ng sut cho sn phm. Gn tng cng: dng tng cng cho cc gc, mt bn, vu li ca sn phm.

5.VU LICc vu li thng dng bt vt hay cc cht bt vt li vi nhau.B dy ca vu nn nh hn 75% b dy t vu, khi b dy vu vt qu 50% d a n cc vt lm trn b mt v ng sut tp trung tng.

Hnh trn l cc thng s thit k vu li

Bn knh ngoi chuyn tip nn bng 0.25% b dy t vu hay t nht cng bng 0.4mm gim ng sut. Mt khi ta tng chiu su vu nn lm bn knh chuyn tip gim bt s chuyn ng hn lon ca vt liu trong qu trnh p phun v gi ng sut mc nh nht. Tuy nhin, lm cho b mt i din d b khuyt tt. Cc gc cn ngoi mt bn nn nh nht l 0.50 gc cn trong nh nht nn l 0.250 m bo s thot khun. bn hn th cc vu li t xa thnh sn phm nn thit k thm cc gn tng cng. Cc vu ny nn t cch thnh t nht 3mm tit kim vt kiu v gim thi gian chu k. Khong cch gia 2 gn nn bng t nht 2 ln b dy thnh sn phm, v nu t qu gn s kh ngui.

sn phm khng b cc vt lm chn nm chng ta cn phi to 1 vng lm ngay chn nm trnh s tp trung vt liu.6.L TRN SN PHMa.L khng sut Chiu su ca l thng khng vt qu 3 ln ng knh l. i vi cc l c ng knh nh hn 5mm th t l ny l 2. B dy ca phn vt liu di cng nn ln hn 20% ng knh l loi tr khuyt tt cho mt i din. Mt thit k tt l b dy ca thnh l lun ng u v khng c cc gc sc cnh ni tp trung nhiu ng sut.

Cc thng s thit k l khng sut

b.L sut Khong cch gia 2 l hoc gia cc l vi mp ngoi ca sn phm nn bng 2 ln b dy hay bng 2 ln kch thc ln nht c o theo chu vi ca l.

Cc thng s thit k l sut Thit k hng ca dng chy dc xung theo l trnh ng hn. Nu ng hn mc khng th chp nhn c th ta khng nn thit k l m s khoan l cho sn phm sau khi p phun. Bn trong thnh l nn bng nhn tng kh nng in y.

K hiu b mt l

7.THIT K SN PHM C RENa.bin dng ren

Ren phi tiu chund.Mt s yu cu cn ch : Bn knh nh ren v chn ren nn rt ln nht c th trnh s tp trung ng sut. on cui ren nn lm trn trnh tun ren, h ren.

To ng trn cui cng ca ren

Trnh thit k on ren c bc ren nh hn hay bng 1mm trnh tun ren v d ch to khun. Khi thit k ren nha lp vi ren kim loi (trong ng nc) ta nn thit k ren ngoi cho sn phm nha v ren trong cho kim loi trnh ren kim loi lm hng ren nha. Ren cho sn phm nha i khi khng cn theo tiu chun d ch to khun. 8.UNDERCUT Undercut l phn trn sn phm gay ra kh khn khi tch khun, nh l ngang trn sn phm, hay l nhng l song song vi mt phn khun. to c nhng l nh th ny chng ta phi t li v khi tch khun ly sn phm ta phi rt li trc ri mi tch khun ly sn phm.

Mt s yu cu cn ch : Trnh thit k undercut khun bt phc tp ,tit kim c chi ph ch to. B dy Undercut khng ln hn 0.7 ln b dy sn phm ti ni dt Undercut Cch cnh ca Undercut nn c bo cung v nm nghing Phn tho Undercut khi tho ra phi nng c th ko gin v tr li bnh thng

V d: Ban u khng th tho sn phm ra khi khun

Sn phm sao khi thit k li c th tho sn phm ra khi khun

V d: Bin i l thnh ba ng bao i din nhau

GVHD: TRN MINH TH UYN Page 7