Ve KT Co Khi

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AI HOC QUOC GIA TP HO CH MINH

TRNG AI HOC BACH KHOA

Le Khanh ien & V Tin t

VE KY THUAT C KH

NHA XUAT BAN AI HOC QUOC GIA

TP HO CH MINH - 2007


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http://www.ebook.edu.vn 12

Chng 1

CAC LOI BN V CKH

1.1 KHAI NIMBan ve la mot phng tien truyen thong gia cac nha ky thuat.

Trong nganh ky thuat c kh tuy theo yeu cau, muc ch can truyen thongma ngi ta e ra cac loai ban ve khac nhau.

1.1.1 Ban ve hnh chieu phang va ban ve khong gian:-Ban ve hnh chieu phang hai chieu: la ket qua cua do phep chieu trcphng (Orthogonal Projection) tc chieu vuong goc vat thc trong khonggian xuong mat phang

-Ban ve truc o: la ban ve vat the trong khong gian 3 chieu dung phepchieu song song. Trong ky thuat khong dung phep chieu phoi canh(Perspective Projection) e bieu dien hnh khong gian nh trong kien truc.

Trc ay khoang 20 nam, ban ve phang c xem nh la ngon ngchnh trong san xuat c kh va ky s, cong nhan, cac nha ky thuat ch lamviec tren ban ve hnh chieu con ban ve ba chieu khong co gia tr ky thuatch dung e giai thch cho nhng ngi khong chuyen mon. Nhng trongnhng nam gan ay, do s bung no cua nganh khoa hoc may tnh, s phattrien va hien ai hoa cua nganh may cong cu ma ban ve ba chieu co motgia tr ky thuat tren cac may CNC. Ban ve ba chieu bay gi chang nhngdanh cho con ngi ma con danh cho may oc va gia cong chnh xac vidung sai yeu cau c ve tren ban ve ba chieu trong cac phan memchuyen mon nh Proengineer, Cimatron....

Trong pham vi ve ky thuat c kh chung toi ch tap trung vao cacban ve c kh chieu phang hai chieu co ien trong c kh e ren ky nangve tay va trnh bay ket cau c kh. Sau ay se ban chi tiet ve cac loai banve hai chieu nay.

Hien nay tren the gii co 2 nhom tieu chuan chnh la tieu chuanQuoc te ISO va tieu chuan My ANSI. Tieu chuan Viet Nam ve Ve kythuat c kh cua TCVN da theo tieu chuan quoc te ISO nen dung PhepChieu Goc Th Nhat (First Angle Projection) nh hnh 1.1 sau:


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CAC LOAI BAN VE C KH 13

Hnh 1.1 V tr 6 hnh chieu trong Phep chieu Goc th Nhat cua Quoc te

ISO va Viet Nam TCVN

Con Anh My dung phep chieu phan t th ba (Third Angle Projection).Theo cach nay quan sat vien ng tai cho va mot hnh hop lap phng


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CHNG 114

tng tng trong suot bao quanh vat ve, tren mat hop noi len cac hnhchieu. Hnh chieu nam gia quan sat vien va vat bieu dien. Theo cach nayth khi hop c khai trien phang th hnh chieu bang at tren, hnhchieu ng at ben di, hnh canh nhn t trai th at ben trai... nh hnh1.2

Hnh 1.2 Chieu trc phng Goc Th Ba kieu My

Tren mot so ban ve cua mot so nc tren the gii co ve ky hieu chieu kieu

Quoc te (Chieu goc th 1) hay chieu kieu My (Chieu goc th 3) nh sau:

Dau hieu chieu kieu TCVN- Quoc te Dau hieu chieu kieu My

Tren cac ban ve TCVN mac nhien dung phep chieu goc th 1 va khong ghiky hieu g ca.


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1.2 PHAN LOAI CAC BAN VE PHANG C KH

1.2.1 Ban ve s o (schema)Ban ve s o la ban ve phang bao gom nhng ky hieu n gian quy

c nham the hien nguyen ly hoat ong nh s o c cau nguyen ly may, s

o mach ien ong lc va ieu khien ong c, s o giai thuat cua chngtrnh tin hoc, ieu khien PLC. Th du s o mach ien nh hnh 1.3

Hnh 1.3a S o mach ien


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CHNG 116

Z =151

2Z =15

2Z '=30

3Z =60

3Z' =25

5Z' =1

6Z =100

1Z '=75

4Z =25

4Z'

n1

Z =20c

Z =205

Hnh 1.3b S o he thong banh rang

Khi trnh bay en cac bo truyen, chung toi se a ra s o ong ve oi tng

nghien cu. S o ong may rat quan trong va quyet nh kha nang lamviec, ket cau cua may sau nay. Trong s o may co the co bang thong baove ac tnh ong hoc, ong lc hoc cua he thong.1.2.2 Ban ve thao ri (explosive drawing)

Trong cac tai lieu ky thuat danh cho giai thch, quang cao, dung trnhbay cho nhng ngi khong chuyen ve ky thuat thng ve kieu khong gianba chieu vi cac chi tiet a thao ri va ang ung v tr san sang lap rap.


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Hnh 1.4 Ban ve thao ri

1.2.3 Ban ve lap rap (Assembly Drawing) hay ban ve ket cau (StructureDrawing)

Da theo s o truyen ong a trnh bay tren, nha ky thuat dung

nhng kien thc chuyen mon co lien quan e tnh toan sc ben chi tiet may,kinh nghiem cong nghe, dung sai lap rap, tham khao so tay ky thuat... e taonen ban ve lap rap hay ban ve ket cau.

Co the noi ban ve lap rap la s bieu hien mot cach cu the cac bo phanmay hay c cau, da tren kha nang cong nghe thc te, cua ban ve s o. Banve lap rap the hien toan bo ket cau cua may va co y ngha quan trong, coban ve lap la co the co chiec may trong y tng va co the hien thc thc strong tng lai. Tai lieu nay tap trung vao cac cach bieu dien mot ban ve lapva luyen ky nang oc ban ve lap cho sinh vien. Co nhieu bai tap ve ban velap e sinh vien t nghien cu ky nang lap rap trong ieu kien cong nghe tai

nc ta.1.2.4 Ban ve chi tiet (detail drawing,part drawing)

Ban ve chi tiet la ban ve rieng tng chi tiet trch ra t ban ve lap atrnh bay tren vi nhng yeu cau rieng ve cong nghe san sang em giacong thanh chi tiet that. Ban ve chi tiet la muc tieu th nh sau ban ve lapma sinh vien c kh can nam bat.

T chi tiet trong khong gian 3 chieu (hnh chieu truc o) ngi ta bieudien chi tiet 2 chieu nh hnh 1.5 nh sau:

Hnh 1.5 Hnh ve chi tiet 2 chieu

va hnh chieu truc o 3 chieu

Trong pham vi tai lieu nay, chung ta tap trung vao hai loai ban ve chi tietva ban ve lap.


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CHNG 118

1.2.5 T le xch : Tr cac ban ve s o, tach ri co muc ch gii thieu thkhong co t le chnh xac , cac ban ve lap rap va che tao ieu phai ghi t letrong o nho gan goc phai ben di cua khung ten. T le co the phong tohay thu nho nham tan dung triet e dien tch t giay ve en 80%- 85%.Khong the chap nhan mot hnh ve chiem cha ti 50% dien tch t giay vanh vay no co the c ve trong giay kho nho hn. Hoa vien can tuan theocac t le tieu chuan nham bao am s can oi cua hnh bieu dien. Hnh ve coghi t le xch con giup cho ngi oc co the o va tnh c mot so kchthc neu no khong c ghi trc tiep tren ban ve (thng la trong ban velap) Cac t le tieu chuan cho 2 loai ban ve nh sau:

Tuy nhien cac t le nh 1:2,5, 1:4, 1:15, 1:25. 1:40, 1:75

hay 2,5:1, 4:1, 15:1, 25:1, 40:1, 75:1

c khuyen nen han che dung. So 1 the hien kch thc that va t le la giatr cua phan so em nhan voi kch thc that se c kch thc tren ban ve.

Hnh 1.6 va 1.7 trang sau trnh bay ban ve lap va ban ve che tao.


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A

H8

k7

H8

k7

A

12J7

h6

H7k6

1

2

3

4 5 6 7

8

A-A

37

65

40

H8

k7

50

12K7h6

40

4321

Banh rangThen bangVong gangTruc

Stt Ky hieuNgi ve

Kiem tra

AI HOC BACH KHOAKHOA C KH

NgayKy

TEN BAN VE

TL:

S.lng

1111

ong thauGX15-32

C40

C45Vat lieu Ghi chu

8765

Than mayLot o thau diNap oLot o thau tren

Ten goi S.lg

1111

GX15-32ong thau

C45Thep lo xo

VAT LIEU

Hnh 1.6 Ban ve lap


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CHNG 120

A

15R5

R5

R5R5

f40

f193

f133

f70

218

244

-0,0

8

0,05

2 45 o

5 mep vatf4

5+0

,01

Rz10

Rz10

10+0,04

50+0,0

6

2,5

0,05 A

1 45 o

0,04A

4 14 14 6,5

8464

38o

8 12,7

Thng hoa trc khi thi cong

Rz40

Ngi ve

Kiem tra


Ngay

KyBANH AI THANG

TL: 1:1

S.lng: 2GX 15-32

Hnh 1.7 Ban ve che tao


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1.2.6 Cac giai oan trong qui trnh san xuat mot thiet b c kh:Nh ta a biet e thiet ke va che tao mot thiet b ta can phai qua nhieu

giai oan:

1- Giai oan thiet ke- Y tng ve san pham can thiet ke.- a ra cac phng an. Cac ban ve s o- La chon phng an tot nhat- Tnh toan ket cau, ve ban ve lap- Ve trch ra cac ban ve chi tiet e san sang em che tao.

2- Giao oan che tao

- Da vao ban ve che tao va ieu kien cong nghe, may dung cu macac nha che tao trong xng c kh co ke hoach chnh sa ban ve

chi tiet (co tham khao y kien cua nha thiet ke).- e ra quy trnh cong nghe che tao cho tng chi tiet (theo kieu nchiec che tao th).

- Che tao tng chi tiet theo cac ban ve chi tiet va quy trnh cong nghea e ra.

- Da vao ban ve lap e lap thanh may.- Chay th nghiem va chnh sa en khi may hoat ong on nh.

- Sa cha, hoan thien lai cac ban ve lap va chi tiet theo may che tha chay thanh cong.

-Neu che tao hang loat th can sa cha lai quy trnh cong nghe chophu hp vi qui mo san xuat .

Trong pham vi tai lieu nay, cac ban ve eu xuat hien trong giai oanthiet ke va xem nh san pham cua giai oan nay v ket qua cua viec tnhtoan trong giai oan thiet ke khong phai la cac con so ma phai hien thcthanh cac ban ve.

1.3 YEU CAU CUA BAN VE LAPCo ba yeu cau chnh cua ban ve lap.

1- Kch thc:Trong ban ve lap ngi ta khong ve chi tiet cac bo phan

tham gia lap ma ch chu trong bieu dien ket cau phan lap cang ro cang tot,luon can ve them cac mat cat e ghi c kch thc lap, cac kch thc utien a ra ngoai hnh ve, neu khong c th rat han che ghi kch thc bentrong hnh. Trong ban ve lap ch ghi ba loai kch thc sau:


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CHNG 122

- Kch thc bao: Cho biet khoang khong gian ma cac bo lap rapchiem cho, bao gom kch thc dai nhat, rong nhat va cao nhat. Kch thcbao khong co dung sai va thng co y niem phong chng khong can chnhxac lam dung bo tr khong gian cho may.

- Kch thc khoang cach truc: cho biet khoang cach truyen ong, cothe chnh xac co kem dung sai nh trong khoang cach truc cua banh rang,truc vt banh vt hay khong can chnh xac v co the tang giam nh trong botruyen xch, ai... th khong ghi dung sai. Khoang cach cac bu long nenthng khong can ghi dung sai. Dung sai khoang cach truc cua bo truyenbanh rang tra theo h7 trong chng 3 Moi ghep hnh tru trn.

- Kch thc lap rap (assembly dimension): bao gom kch thc danhngha va kieu dung sai. Kch thc lap rap c trnh bay ro chng 3 Moighep hnh tru trn.

2- anh so chi tiet: Trong ban ve lap co nhieu chi tiet may tham gia lap

rap v vay can anh so chi tiet e nh danh, nh vat lieu, so lng, ky hieutrong ban ke at pha tren khung ten.

- Ky so chi tiet phai co o ln t 22,5 lan so ghi trong kch thc, bendi phai c gach bang net c ban, ng thang noi ch vao chi tiet cve bang net manh, tan cung au ch vao chi tiet co moi cham tron cho ro, oln cham tron phu thuoc kch thc ban ve t 1 1,5mm trong cac ban ve tA3 en A0. Ky so phai c anh trat t theo vong cung hoac ngc chieukim ong ho e ngi oc ban ve e tra cu. Khoang cach cac so nen cacheu nhau va phan bo tren mot ng thang. Cac ng manh ch vao chi tietkhong nen cat nhau nhieu.

3- Ban ke: Liet ke lai mot cach chi tiet cac so chi tiet a c anhtren ban ve. Ban ke c anh so ngc t di len va noi dung gom so tht, ten chi tiet, so lng, vat lieu, ky hieu (danh cho o lan, ren vt) va mucchu thch co the noi tieu chuan hoac xuat x.

Nh ban ke ta co the anh gia gan ung c:- Khoi lng toan may hay c cau.- Gia thanh.

1.4 YEU CAU CUA BAN VE CHI TIET

Ban ve chi tiet (detail drawing, part drawing) hay con goi la ban veche tao c hnh thanh sau khi a co ban ve lap rap.

Do vay, ta thay ve ban ve chi tiet la bc sau cung cua giai oan thietke, cung nh ban ve lap ban ve thiet ke cung oi hoi co kinh nghiem ve


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cong nghe. Tuy nhien, mot ban ve che tao th co nhng yeu cau hoan toankhac vi ban ve lap:

Yeu cau cua ban ve chi tiet:

Co 5 yeu cau cua ban ve chi tiet:

1- Kch thc:Neu trong ban ve lap ch yeu cau co ba loai kch thc lakch thc lap rap vi kieu dung sai, kch thc khoang cach truc va kchthc bao th mot ban ve chi tiet phai co ay u tat cac cac kch thc mot

cach chi tiet nh ten goi sao cho ngi khac khi oc ban ve co the ve lai

c hay co the cat phoi c tren kim loai. Ngoai ra, cac kch thc quantrong thng la kch thc tham gia lap rap trong ban ve lap can phai co

dung sai cu the. V du, moi lap tru trn trong ban ve lap ghi7

830

k

H th khi

ve ban ve chi tiet lo ta phai tra dung sai cho kch thc lo 30H8 trong so taycong nghe che tao may va ghi 300,08. 0,08 la vung dung sai cua lo 30H8.

2- o nham be mat(Roughness)

e che tao mot chi tiet khong phai ch co kch thc la u ma con canphai co o nham be mat. o nham be mat c chon da tren:

- Che o lam viec: o nhan bong cang cao (cang bong) th ma sat canggiam nen be mat cac o trt khp tnh tien o nhan bong phai cang cao.

- o chnh xac: oan truc hay lo co cap chnh xac ve kch thc cangcao th tng ng vi o nham cang cao. V du, be mat tru lap o bi, lap vongpht (tieng Phap: Feurtre) th yeu cau o nham phai cao.

Tuy nhien o nhan bong cang cao th gia thanh san pham cang ln vphai qua nhieu cong oan gia cong tinh nh mai, lan ep ton kem. Do vayviec chon o nham phu hp phai co tnh hp ly, tnh cong nghe va phai phuhp tnh trang cong nghe thc s.

Ky hieu va cac cap o nham thng dung:

Ky hieu: co ba ky hieu o nham i kem vi gia tr c ghi pha tren,

mui nhon ch thang goc vao be mat gia cong nen ky hieu va tr o nham cothe xoay chuyen phu thuoc be mat ch nh.


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CHNG 124

Hnh 1.4 Cac ky hieu o nham be matKy hieu la hnh anh cua ch r, ky t au tien cua t roughnessGia tr o nham: c ghi pha tren ky hieu va bat au bang ky t R(Roughness) va co mc o nham la:

Rz: sai so trong 5 iem danh cho be mat tho hoac ban tinh (tien,phay...) hoac sieu tinh (ban ve Viet Nam khong dung mc sieu tinh).

Ra: o nhap nho trung bnh (average) danh cho be mat tinh qua mai, doa

Trong cac quy nh tieu chuan cua TCVN th co rat nhieu day gia tr,nhng thc te cac xng c kh ch thng dung cac cap o nham sau t rat

tho en rat tinh theo 8 tr pho bien nh sau:-RZ320: be mat rat tho khong gia cong, nh be mat thep can, vat uc.

- RZ160: be mat tho khong gia cong c, ch lam sach sau khi uc.Thng dung khi co anh sach bang cc.

-RZ80: co gia cong c nhng rat tho, nh bao, phay tho, t dung.

-RZ40: be mat gia cong gia cong ban tnh nh tien, phay ban tinh ratthng dung e ghi o nham chung goc phai ben tren ban ve chi tiet.

- RZ20: Gia cong tinh cao nhat co the co bang dao thep gio, hp kimcng bang phng phap tien phay, bao hay xoc.

Ke t sau RZ20, ta phai gia cong tinh bang phng phap doa, mai vadung tr chieu cao nhap nho trung bnhRa e anh gia:

-Ra2,5: Mai tho hay doa bang tay

-Ra1,25: Mai ban tinh, doa may

-Ra0,625: Mai tinh, doa, anh nham tinh

3- Sai so hnh hoc va v tr tng quang

Sai so hnh hoc: la sai so cua chnh ban than be mat o, thng la dungcho cac be mat tho. Tat ca n v eu tnh bang mm. Sai so hnh hoc baogom:

-o khong tron hay o oval: co ky hieu vi mui ten ch vao be mat trucan ch nh o oval toi a 2,5mm. V du, co the dung ongho so (Phap: Comparateur Anh: Dial Indicator) e kiem tra


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o oval, hoac tho hn co the dung thc cap o tm hieu ng knh ln nhatva ng knh be nhat, o oval ch dung cho mat tho khong gia cong nh vatuc, ren.

-o vat, o doc (Taper): v du, ky hieu 1:100 thng dung cho mat

nghieng va tnh bang tg cua goc nghieng, nhng c viet vi dang phantram, v du 10:100 tc tg goc nghieng la 0,1 goc nghieng khoang 5o45.

-o con: v du ky hieu 5:100 e ch tg cua goc con c viet di

dang phan tram ta co o con =L

dD = 2 lan o doc, o con thng bieu

dien cho be mat con tho hoac tinh.

Sai so v tr tng quan: la sai so so vi mot mat chuan chon trc,thng ay la chuan gia cong va c chon trc bang ky hieu ch A (neuco nhieu chuan khac co the then B, C) trong khung vuong va ch vao be mat,ng tam chon chuan bang mot dau delta.

Sai so v tr tng quan thng rat adang vi cac ky hieu cung dau mui ten chvuong goc vao be mat can ghi sai so tngquan so vi mat chuan. Ta co the ke mot sosai so tng quan thng gap trong c khnh:

-o ong tam:

Tr 0,5 la khoang cach tam cua be match nh so vi tam chuan ky hieu la A.

o ong tam thng dung cho be mattho va co tr thng ln hn 0,5mm.

- o ao hng knh: la hieu so banknh ln nhat va ban knh be nhat cua be mattru ch nh; thng dung cho cac vat quaynh banh rang, banh ai so vi tam hay mattru lo. Gia tr o ao hng knh thng ccho bang 1/4 en 1/2 dung sai ng knh va ch o cho cac be mat a giacong tinh. Co the dung ong ho so e o o ao hng knh khi at au ovao chu vi mat tru can o.

- o ao mat au: co cung ky hieu nh o ao hng knh nhng co doc truc va ta vao mat au chi tiet quay dung cho cac be mat a giacong tinh va rat thng dung cho cac vatquay nh banh rang, banh ai so vi tam hay


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CHNG 126

mat tru lo. Gia tr o ao mat au thng cung c cho bang 1/4 en 1/4dung sai ng knh va ch o cho cac be mat gia cong tinh. Cung co thedung ong ho so e o o ao mat au.

- o vuong goc: gia tr cua o lech so vi phap tuyen cua be mat tai

iem can o cho tnh bang mm tren 100mm chieu dai.-o song song: gia tr khoang cach lnnhat va be nhat emax - emin cho tnh bang mmtren 100mm chieu dai cua mat, ng chnh va chuan.

- o oi xng: la sai lech ln nhat sovi chuan ch nh A cua mat ch nh trenchieu dai 100mm doc truc oi xngA.

Thong thng th:

- Mat tho, khong gia cong: dung o sailenh hnh hoc nh o khong ong tam va o oval.

-Mat gia cong tinh: dung sai lech v tr tng quan ma o ao mat auva o ao hng knh la thng dung nhat. Con o con th dung ca cho haibe mat e tho va gia cong tinh.

4- Tnh chat c ly: thng ghi di yeu cau ky thuat. Tnh chat c ly bemat hay the tch thng x ly bang c luyen hay nhiet luyen.

- C luyen: thay oi c tnh be mat gia cong, tang ben be mat bang cacbien phap c hoc nh phun bi, lan nen, lan ep rung... hien ch mi cnghien cu cha co ng dung nhieu nen t gap trong cac ban ve, neu co se

ghi chu cac ac iem cua no.-Nhiet luyen: thay oi c tnh vat lieu bang cach thay oi nhiet o un

nong va lam nguoi theo mot quy trnh ky thuat nhat nh, co the ke en cacbien phap sau:

Toi ( Trui): la bien phap lam cng vat lieu bang cach nung len trennhiet o ti han roi lam nguoi nhanh (nhiet o ti han tm c bang cach trabang gian o Fe-C khi biet thanh phan carbon va cac nguyen to quy cua vatlieu) toc o lam nguoi cung phu thuoc vat lieu: Thep carbon lam nguoinhanh trong nc, thep hp kim lam nguoi cham hn trong dau. Can ghi o

cng (Hardness) sau khi toi. Thng toi la nguyen cong sau cung neu chi tietkhong qua mai sau nhiet luyen.

Co ba n v o o cng:


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- HB (Hardness of Brinelle): dung cho cac loai thep che tao may trongc kh do Brinelle ngi Phap e ra bang cach ep vien bi toi cng tren bemat can o. Dien tch lom cang be khi vat o cang ran cng. Thng thepsau khi toi co gia tr HB t 250300.

- HR (Hardness of Rockwell): co ba mc o khac nhau HRA, HRB,HRC o bang cach ep mui con tren be mat. HRC thng ch dung cho dungcu cat v gia tr o ran ln hn HB rat nhieu v du dao hp kim cng co theat o cng t 6065 HRC, ban ve c kh t dung o cng HR.

- HV (Hardness of Vikel): ep mui kim cng hnh thap len be mat cano ch dung cho cac vat that cng nh gang trang, kim cng.

U (luoc): la bien phap lam mem vat lieu bang cach nung len trennhiet o ti han roi lam nguoi cham ngoai khong kh hay cham hn cungnhiet o nguoi cua lo (nhiet o ti han tm c bang cach tra bang gian oFe-C khi biet thanh phan carbon va cac nguyen to quy cua vat lieu) toc o

lam nguoi cung phu thuoc vat lieu: Thep carbon lam nguoi nhanh ngoaikhong kh, thep hp kim lam nguoi cham hn cung vi lo. U hay luoc thngdung cho cac vat a toi cng can lam mem e gia cong sa cha lai hoaclam giam tnh don cac vat qua can nguoi nham tang tnh deo, thng luocc xem nh lam h chi tiet.

Ram: la bien phap lam du bt tnh cng cua vat lieu sau khi toi echong nt, tang tnh deo bang cach nung len di nhiet o ti han roi lamnguoi t t cung lo (nhiet o ti han tm c bang cach tra bang gian o Fe-C khi biet thanh phan carbon va cac nguyen to quy cua vat lieu) toc o lam

nguoi cung phu thuoc vat lieu: Thep carbon lam nguoi nhanh hn thep hpkim.

Thng hoa: nham giam ng suat d cha trong chi tiet may hayphoi sau khi tao e tranh dan n, thng nc ta khong nhiet luyen gangnhng phai thng hoa phoi gang trc khi gia cong neu chi tiet can chnhxac (v du: block may, bargue segment...) v neu khong thng hoa trc thsau khi gia cong gang co the t thanh oi kch thc va ch on nh saukhoang 1 nam tri. Co hai bien phap thng hoa:

- Thng hoa t nhien: e phoi gang trong kho hay ngoai tri khoang 1nam trc khi em gia cong c.

- Thng hoa nhan tao: ta thay thng hoa t nhien khong hien thc vphai ch i lau, khong ap ng c nhu cau san xuat nen ngi ta thng


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CHNG 128

dung thng hoa nhan tao cung tng t nh ram nhng danh cho phoi gang,cha tng qua toi. Cung co the thng hoa thep trc khi gia cong.

Noi chung nhiet luyen th ton kem tang gia thanh san pham va sinh ranhieu phe pham. Can co nhieu kinh nghiem, thiet b nen nc ta thng t

dung tr trng hp che tao thay the hay sa cha.5- Vat lieu va so lng

Vat lieu va so lng chi tiet gia cong thng phai ghi trong khung ten.So lng chi tiet xac nh loai hnh san suat la n chiec, che th hay hangloat nho ln hay hang khoi, no co the quyet nh phng phap gia cong vaanh hng rat nhieu en gia thanh san pham. Mot so vat lieu vi ten chuanthng dung trong cac ban ve ky thuat nh sau:

Thep carbon che tao may: C30, C35, C45, C50

Thep hp kim che tao may: thep Crom 40Cr, thep mangan 45Mn, thep

lo xo 40Si...Thep xay dng dung lam dan, khung, vo may: CT3,CT4, CT5.

Gang xam: GX 15-32.

Gang cau: GC.

Vat lieu phi kim loai nh cao su, da, amian...

1.5 QUY NH CHO BAN VE KY THUAT C KH TRONG TRNGBACH KHOA

Hien nay, TCVN cha co quy nh thong nhat ve khung ban ve nenmoi nganh, nha may co quy nh rieng. Trong pham vi mon hoc Ve ky thuat

c kh tai Khoa C kh trng ai hoc Bach khoa, chung toi a ra mot maukhung ten cho giay A4 ng co ong tap (chu y theo TCVN khong cho phepA4 ngang) va A3 ng hoac ngang e co tnh thong nhat dung trong trongmon hoc, tien cho bai tap ve nha va cac ky thi gia va cuoi hoc ky. Nhnchung quy nh khung ten nay khong khac lam so vi cac nganh khac.


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1.5.1 Tieu chuan khung ban ve lap rap(Ch danh cho cac bai tap ve c kh tren giay A4 trong khoa)

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TRNG AI HOC BACH KHOAKHOA C KH

TEN BAN VE TEN TOAN MAYhay

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Ky hieu - Ten bo phan

Hnh 1.8 Khung ten ban ve lap cho bai tap tren giay A4

1.5.2 Tieu chuan khung ban ve che tao

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Hnh 1.9 Khung ten ban ve che tao cho bai tap tren giay A4


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32 http://www.ebook.edu.vn

Chng2

CAC MOI GHEP CHAT: INH TAN - HAN VA DAN

2.1 KHAI NIEMGhep chat hay ghep cng la bien phap lien ket cac bo phan

lai vi nhau ma khong cho chung co chuyen ong tng oi vinhau na. Co hai loai ghep chat:

- Khong thao c nh inh tan, han, dan.- Thao c nh ren vt, then chot, vong gang.

Ghep cng cac chi tiet lai vi nhau nham cac muc ch sau:

- Tao mot khau ln hn, co hnh dang phc tap neu dung motchi tiet th kho gia cong hay khong gia cong c.

- De dang lap rap hn mot chi tiet.- Phoi hp s dung vat lieu hp ly.- Co the thay the mot phan neu h hong phan o, nen tiet kiem.

Tuy nhien, do co nhieu bo phan lap rap nen chi ph gia cong,cong lap rap ln do o co the lam gia thanh san pham cao. Th duvo case cua may vi tnh e ban tr 2 nap c ghep chat e khongthao c con bo cot gia gio ap pedal xe ap la mot v du ronhat cua viec ghep chat nhng thao c. Trong chng nay ta ch

tap trung vao cac chi tiet lap cng khong thao c hay thao crat kho khan.

2.2 INH TAN(RIVET)

2.2.1 Mo taCo le inh tan ra i rat lau, tren 1000 nam v vao thi

Trung Co (Middle Age) tai chau Au a thay inh tan xuat hientren cac bo ao giap, ca sat cong thanh, nha th... Ngay nay, inhtan van gi mot v tr quan trong trong cac moi ghep c kh mat

du dan dan c thay the bang cac moi han cao cap. Thap Eiffelsn mau en cao tren 300m tai Paris hien dung lam ai truyenhnh va phat thanh la mot niem t hao ve tao tac c kh cua Phapva the gii vao cuoi the ky 19 la mot cong trnh ghep hoan toan


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CAC MOI GHEP CHAT: INH TAN - HAN VA DAN 33

bang inh tan. Nam 1965, Nhat cung theo o che thap Tokyo caotren (500m) sn o va trang cung bang ket cau inh tan, nhngkhong noi tieng va co y ngha lch s bang thap Eiffel.

Hnh 2.1 Moi ghep inh tan thep

Hnh 2.1 the hien mot moi ghep inh tan. Hai bo phan laprap can khoan hay ot hai lo bang ng knh inh tan. inh tan

c che san mot au se c xo qua lo roi at khuon mu len vadung bua tay hay bua may ap cho bien dang uoi inh tan thanhmu au kia.

Hnh dang hnh hoc cua mot so loai inh tan sau:


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CHNG 234

Hnh 2.2 Thong so hnh hoc cua mot so loai inh tan

Bang 2.1 Thong so mot so inh tan mu tron thng dung

d 4 4,5 5 5,5 6 7 8 9 10 11 12 14 16

h 7 8 9 10 11 12 14 16 17 19 21 24 28

c 3 3,5 4 4 4,5 5 5,5 6 7 8 8 10 11

B 24 28 30 34

w 0,8 0,8 1 1

2.2.2 Tnh nangGhep bang inh tan la mot bien phap hu hieu va co o tin

cay cao nhat ch sau vat uc lien nguyen hnh. inh tan co the taos kn kht c dung trong noi hi (vao the ky trc). Nhng bophan can o on nh cao va khong thao lap cua cot cao the ngaynay c ghep bang inh tan. That ra moi ghep inh tan co thethao uc nhng rat kho khan, lau va ton kem neu ng knhinh tan ln (t 10mm tr len) ta phai mai bo mot au roi dunguc ot ra.

2.2.3 Phan loai va pham vi s dungCo nhieu loai inh tan va cac bien the dung rong rai trong

may moc, i song. Co the chia inh tan ra lam cac loai sau:

a- inh tan sat thep: la dang c ban nguyen thuy co le ra itrc tien, c che tao san mot au co hnh chom cau. Tuy theotai trong can ep hai mat lap ghep ma chom cau co the mong hayday. Loai tai nang nhat mu la 1/2 hnh cau. Co hai cach tan la tannguoi va tan nong.

- Tan nguoi: danh cho ng knh di hay bang 10mm.

- Tan nong: khi ng knh tren 10mm nung o inh tan lentrc khi a vao lo e tang tnh deo, giam lc tan nhng giathanh at hn. Moi ghep inh tan co gia tr s dung vnh vien, o


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on nh cao, chu c rung ong, khong can bao quan phc tapnhng co mot so nhc iem sau:

- Nang suat kem: Ton nhieu cong sc cho khoan lo tren tamghep, ot nong o inh tan, lc tan ln.

- Tieng on rat ln, gay tac hai thnh giac cho cong nhan haynhng ngi chung quanh khi tan.

- Khoi lng moi ghep ln, nang do au inh, phan chap haytap ghep them (trong lng co the tang them 30%). au inh loigay can tr neu dung ghep vo tau se can nc va lam giam taitrong chuyen ch cua tau. Tau Phap khi sang anh nc ta tai aNang eu la tau co vo ghep bang inh tan.

Hnh 2.3 Mot so loai inh tan


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CHNG 236

b- inh tan sat chm mot au: la mot cai tien cua inh tanchom cau nhng phai phay, loe hay doa lo con tren mot mat tamghep nen ton cong sc nhieu ma lc ep yeu hn loai chom cau. aucon lai co the tan hnh chom hay tru tuy theo khuon mu. Hnh 2.4the hien inh tan chm mot au. inh tan nay cho mot mat lapghep ep nh trong moi ghep moyeu va vanh rang cua banh rangth cap trong bo truyen nhong hu xe Honda.

Hnh 2.4 Ket cau mot so inh tan au chm, au co goc 90o

Bang 2.2 Thong so ket cau inh tan au chm

d 2 3 4 5 6 7 8 9 10 12 14 16 18 20

h 4 6 8 10 12 14 16 18 20 24 28 32 36 40

c 1 1,5 2 2,5 3 3,5 4 4,5 5 6 7 8 9 10

E 0,75 1 1,25 1,5 1,75 2 2,25 2,5 3 3.5 4 4,5 5

1,8 2,4 3 3,6 4,8 5

l 3 4 5 6 8 10

Ngoai ra con co loai au chm goc 60o.

c- inh tan rut bang nhom: dung ghep cac tam ton mong,nhom di 1mm co hieu qua va nang suat cao nhat trong cac loaiinh tan. Can dung mot dung cu at biet la kem tan rut. Hnh 2.5the hien cau tao cua mot inh tan rut ang lam viec. Kem xiet varut cay tige (bang thep mem) doc co au hnh cau lam ong nhombien dang, loe ra va ep lay hai be mat lap rap. Tan nhom rut tienli, nhanh chong, re nhng ch cho mot mat ngoai ep, mat trong


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ni au ong nhom bien dang rat xau, ch dung cho vat mong khongchu lc nh bang hieu cua may, khong dung ghep trong c khnang c.

Hnh 2.5 Ket cau inh tan rut nhom

d- inh tan da, simili, vai: la cac loai nut bang kim loai(thng la ong) e trang tr, ket noi hai mieng da, vai. a dangnhng tat ca eu phai ot lo thung tren mieng da, vai, hai phancua inh tan ghep hai mat c tan chat, gap m len nhau.

Vien cho cac lo tren tent, bat giup lo ben be mat, khong b xetet khi treo... Ket cau cac loai inh tan da, vai cho trong hnh 2.6.

1- Bat Da; 2- Khoen Nap Tan Tren; 3- ot Cone; 4- Khoen Di; 5- e

Hnh 2.6 Tan tao khuy ong cho lo tren bat da

e thao cac loai inh tan da nay, ta co mai t phan gap m

cua khoen di.


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CHNG 238

2.3 HAN (Phap: Soudure, My: Welding)

2.3.1 ac iem

Han la bien phap ghep kim loai ma khong the thao c.Han kh ra i t lau, con han ien mi khoang 100 nam nay va

a co nhng cai tien nhanh chong nham nang cao chat lng moihan, nang suat, an toan, o on nh va tin cay... Ngay nay hau nhhan co the thay the 90% cho moi ghep inh tan. Ghep bang han conhng ac iem sau:

u iem:

- Nang suat cao nhat, khong phai khoan, ot.

- Kinh te nhat, nhat la han ho quang ien.

- Co the cat lng kim loai day en tren 300mm vi nang

suat cao nhat va gia thanh re nhat ma khong phng phap giacong c kh nao sanh kp (cat bang gio a).

- Co the thc hien tai hien trng, tren may ma khong phai

van chuyen, ga vat len may.

Nhc iem:

- Do phai nung nong nen lam h to chc kim loai, nha toi chi

tiet c nhiet luyen tot, hay gay bien cng vat lap ghep do nguoinhanh, b nt v khi lam nguoi nhanh...

- Gay bien dang, h hong hnh dang be mat nen tranh dung

cho cac chi tiet a gia cong tinh roi.

- oc hai, do khoi thuoc han xong len mat, ht vao mui. Hoquang ien co nhieu tia X, tia am cc gay hai mat va lam bong da.

Nguy hiem khi lam viec tren cao.

- Han gio a neu bat can, chay ngc co the gay no bnh a,bnh oxy no gay ton hai ve ngui va tai san.

- Chat lng moi han co ien thng khong cao, co nhieu vetnt, lo bot nen ngay xa cac cong trnh quan trong nh noi hi aplc khong dam dung han, phai dung inh tan. Tuy nhien, ngay nay

nh cac phng phap han tien bo nen han la phng phap chu yeucho viec gia cong noi hi ap suat nh nhng bien phap kiem trahien ai bang sieu am....


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2.3.2 Phan loai va pham vi s dung

Muc ch cuon sach nay la nham vao cach bieu dien moi han

nen viec mo ta thiet b va cong nghe han la khong can thiet. Tuynhien, gii thieu qua mot so phng phap han va pham vi s dung

th can thiet.a- Han kh acetylen (han gio a) gom gio, oxy, a, kh a, at

en tao acetylen. Ch han vat mong, tole di 1mm bang gio a,

kim loai th ba a vao co the la sat hay ong. Ngon la gio a

cho nhiet o en 3000o trong khi nhiet o nong chay cua sat thep

khoang 1560o. e tranh oxit hoa moi han khi nhiet o cao, ta

thng nhung que kim loai vao bot han the e tay sach moi han

va ay khong kh ra khoi vung han. Mot u iem ac sac cua han

gio a la cat t kim loai day nhat, nang suat cao nhat nh a

trnh bay phan tren nh tan dung triet e tnh b oxid hoa khi

nhiet o cao cua thep.

b- Han ho quang ien: Do tnh c ma nam 1890 Elihu

Thomson, nha sang che noi tieng ngi My, a e cham mach cua

2 ban tu ien chai Leyden, sc nong lam dnh 2 day ien lai khong

tai nao thao ra c va nh vay han ho quang ien ra i vi vo

so ng dung lam thay oi bo mat the gii vao cuoi the ky 19.

Chuyen dung han vat day t 1mm tr len va co the han vat day

bat ky, cho moi han ben chac co the dungtrong che tao may. Tuynhien, chat lng be mat moi han (moi han co ngau khong) thng

phu thuoc tay nghe cong nhan hn la thiet b. Cac bien the cua ho

quang ien la han mig, mag, tig. Hien nay han vo tau, noi hi, cac

vat gia dung chu yeu la dung han ien. May han ien thc chat la

mot may bien the hieu the ra hai au mo han va vat han la 60V

e an toan, nhng cung o dong ien han rat ln toi thieu la 30A.

c- Han ap lc (ham bam) cho moi han ep nhat khong can

kim loai th ba, hai kim loai cua vat han t chay di nhiet o cao3000o va b nen di ap lc nen t dnh nhau. Han bam co nguon

goc t han thu cong goi la han ren.


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CHNG 240

d- Han vay ong: Dung han cac vat mong, chu lc cao va

nhan ep, dung han noi li ca go bang cach nung cac thanh sat

nong o ep hai au vat han co nhung han the gia la mieng ong,

di tac dung cua nhiet va ap lc mieng ong chay ra va lam dnh

hai kim loai.

e- Han ch (hoac han thiec, han antimone (Anh: Antimony)):

Han vat mong, Block may bang hp kim nhom... ac biet han ch

ch chu nhiet thap di 150o, co the thao ra sau nay de dang bang

cach thoi nong chay moi han ch ma khong lam h chi tiet. V du,

han moi noi day ien, thung giai nhiet oto (radiateur) han ch

c bieu dien giong dan se trnh bay phan sau.

2.3.3 Ve bieu dien moi han

ay la muc ch chnh cua chng nay. Hien nay, TCVN co

nhieu thay oi so vi tieu chuan trc ay cua ISO nen chung toi

trnh bay ca hai loai e sinh vien de tham khao.

Hnh 2.6 Chi tiet c ghep bang han

Khong co s phan biet phng phap han, neu muon ch ro

phng phap han co the ghi them trong yeu cau ky thuat hoac

trong chu thch cua ban ke chi tiet.

Theo ISO th:

- Vat mong di 5mm khong can vat mep, co the han trctiep sau khi kep chat hai vat can han bang eteau, km bam...


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- Vat day 10 en 20mm th moi chi tiet c vat mot ben vi

goc vat 30o nghieng vi ng ngang.

- Vat day tren 20mm th moi chi tiet c vat hai mep goc

30o mat tren va di

- Bat buoc hai vat phai ep sat nhau trc khi han e: Bao am

chnh xac kch thc mong muon, truyen c ien.... Be day moi

han cung toi thieu cung bang be day mong nhat cua mot trong hai

vat han.

Hnh 2.7 trnh bay ky hieu moi han theo TCVN trc ay

Hnh 2.7 Trnh bay tieu chuan cac qui cach bieu dien moi han

trong he ISO va he TCVN trc ay

Hnh 2.8 trnh bay tieu chuan ve moi han theo TCVN hien nay,

nhan xet ta thay khong qui nh ro rang ve ieu kien vat mep va o kht

cua 2 vat han. Hien nay han ho quang ien phap trien them phan kh

bao ve, day thuoc bao ve moi han va ien cc khong chay de dang cho t

ong hoa, ieu khien t ong bang robot cung nh bao ve cho cong nhan

han tot hn nh:

- Tig : ien cc khong mon vi lp kh Argon hay Helium bao ve.-Mig: ien cc an mon c may cap lien tuc vi lp kh Argon hay

Helium bao ve.


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CHNG 242

-Mag: ien cc an mon c may cap lien tuc vi lp kh CO2 baove.

- FCAW: Han day loi thuoc c cap lien tuc khong co kh bao ve,ong day thuoc han chay se bao ve moi han.

Hnh 2.8 Trnh bay tieu chuan cac quy cach bieu dien

moi han trong he TCVN hien tai


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2.4 DAN

2.4.1 Mo taDan la phng phap de dang ghep chac hai be mat ma khong

phai khoan lo hay lam thay oi to chc ben trong... Tuy nhien, moi

ghep khong the chu lc ln va ieu kien lam viec khac nghiet nhhai phng phap tren. Dan cung c xem nh moi ghep khongthao c

2.4.2 Phan loai va pham vi s dungDan kim loai bang keo dan sat. Keo nay la mot dang keo

epoxy tron san gia rat re tren th trng nhng mau ong cngnen thng phai dung het sau khi khui. Nen dung keo epoxy chapha gom 2 hu hay tube rieng A va B (keo AB). Moi dan thngch chu lc tnh, on nh va de b tach, t neu vat chu uon be

hay rung ong manh.ac biet dung keo dan ai det la mot bien phap cao cap va

chat lng nhat hien nay, nhng ay la bien phap dan vat phi kimloai: Day ai det c cat xien kho ngang e tang dien tch tiepxuc, cac th vai bo phai c tc ra va an vao nhau theo th tgia la lp keo. Bnh thng keo gom hai chat ng trong lo khacnhau ke t khi pha chung theo t le 1:1 th mi bat au ong cng.Toi k nhat la luc dan hai be mat lai cong venh tach ra nen phaico mot loai ga kep ac biet gom hai ma kep bang ren trai chieu,thi gian kep ep ai co the thay oi khoang 48 en 72 gi tuy loai

keo, ai va be day ai. ai dan nh vay th tiet dien dan hi dayhn cho bnh thng va neu co t th ai se t cho khac.

Han ch va dan co cung mot kieu bieu dien: ve bang net amgap hai lan net c ban (1,23,2mm) vien theo canh muon bieu dienmoi han.

Hnh 2.9 di ay trnh bay quy c ve moi dan hoac han chtheo TCVN.


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CHNG 244

Hnh 2.9 Moi dan bang keo hoac han ch theo TCVN

Khi han hay dan theo ng bao kn th ve mui ten ch vaomoi dan hoac han, phan uoi co ky hieu mot vong tron manh nhhnh 2.10.

Hnh 2.10 Moi han ch hoac dan kn (giap vong)


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Chng3

MOI GHEP HNH TRU TRNDUNG SAI CHE TAO VA LAP GHEP

3.1 KHAI NIEM MOI GHEP HNH TRU TRNMoi ghep hnh tru trn la moi ghep c ban c ban nhat trong

c kh co the cho cac che o lam viec khac nhau theo mot yeu caunhat nh. Trong c kh cac nha cong nghe chon hnh tru tron elap rap v nhng ly do sau:

- Cong nghe che tao mat tru truc va lo a hoan thien, co theat o chnh xac va o nham cao (bong loang). ng tron de chetao nhat v co nhieu bien phap gia cong tinh nh khoan, khoet,dao, mai tru ngoai, mai lo.

- ng tron n gian, co t thong so nhat (ch co kch thcng knh), con hnh vuong co nhieu thong so hn (kch thc 4canh, 4 goc...) do vay, ng tron de che tao va kiem tra hn cachnh khac.

Moi lap tru trn xuat hien hau het trong cac ket cau c kh

nh moi lap gia truc va lo banh rang, banh ai, truc vi vongtrong o lan, lo vi vong ngoai o lan. Then va ranh tren truc trenlo...

3.2 DUNG SAI CHE TAO VA LAP GHEPDung sai o lng la mot mon hoc quan trong trong chng

trnh c kh, chng nay khong co tham vong trnh bay ve van eln nay ma ch trnh bay nhng khai niem c ban va ng dungtrong ve ky thuat c kh giup sinh vien nam bat, ghi va oc ckch thc vi kieu dung sai trong ban ve lap va kch thc vi

dung sai trong ban ve che tao.Dung sai (Tolerance): ngha ngoai i song la s dung th.Trong ky thuat, dung sai la sai so cho phep cho mot kch thc


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CHNG 346

trong mot vung nao o luc che tao. Neu kch thc at c trongvung dung sai, ta noi kch thc nay at yeu cau. Tieu chuanTCVN quy nh dung sai che tao va lap rap nh sau:

Dung sai che tao: ch quy nh cho mot kch thc che tao

quan trong nao o, khong phai kch thc nao cung co dung sai vlam tang mc o phc tap va gia thanh chi tiet ma khong can thiet.

Dung sai che tao co the oi xng (symetrical) v du mot kchco dung sai ghi 1000,15 th cac kch thc nao trong khoang99,85 en kch thc 100,15 eu at yeu cau. Nhng a phancac kch thc trong c kh co dung sai bat oi xng (deviation)nh sau: 08,0 15,0100

+ vay cac kch thc ng knh nao trong

khoang 99,85100,08 eu at yeu cau.

Kch thc co dung sai bao gom hai yeu to:

- Kch thc danh ngha: theo v du tren th: 100 la gia trten goi e de nh vung kch thc, khong phai kch thc that.(Chu y: kch thc ng knh phai co trc).

- Vung dung sai (n v: mm) gom:

Sai lech gii han gia tr tren.

V du: tp = +0,08

Sai lech gii han gia tr di.

V du: tm = 0,15

Gia hai gii han tren va di la vung dung sai

t = tp tm = 0,08 (0,15) = 0,23

3.3 CAP CHNH XACTa thay vung dung sai cang hep ngha la sai lech gii han

tren va sai lech gii han di cang gan nhau th chi tiet cang khoche tao, o chnh xac cang cao. Do o, ta co khai niem ve capchnh xac che tao. TCVN quy nh co 15 cap chnh xac t cap caonhat la 0 en cap 14 la cap thap nhat. Cap chnh xac phu thuoctrnh o ky thuat cong nghe va thiet b gia cong cua tng quoc gia,

tng vung va hang san xuat. Hien nay, cong nghe Viet Nam co theat cap chnh xac cao nhat la 6 nh che tao trong phong thnghiem cac trung tam ky thuat cao, cac c s chuyen mai cot may,


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MOI GHEP HNH TRU TRN. DUNG SAI CHE TAO VA LAP GHEP 47

len code cylindre vi may chuyen dung... nhng thc te ngoai sanxuat thng ch at cap 7 hoac 8. Do truc co be mat ngoaithng de che tao hn lo co be mat tru trong nen trong cung motieu kien cong nghe (trong mot nha may, quoc gia...) th o chnhxac lo thng chon thap hn truc mot cap. Th du cap chnh xac lola 8 th cap chnh xac truc la 7.

3.4 PHAN BO VUNG DUNG SAITa thay vi hai chi tiet truc va lo c che tao vi cung mot

kch thc danh ngha, nhng dung sai va cap chnh xac khac nhauco the phoi hp e tao nen cac kieu lap ghep khac nhau ta goi ladung sai lap ghep vi cac che o lap ghep khac nhau.

Phan bo v tr cua vung dung sai so vi kch thc danh nghac TCVN chia lam 26 mien dung sai anh so t A en Z tuy

thuoc vao truc hay lo va cap chnh xac. Bang 3.1 gii thieu sphan bo mien dung sai cua truc va lo cap chnh xac 8. Mien dungsai lo c quy nh viet bang ch in A, B, ... Z, mien dung sai trucc quy nh viet bang ch thng a, b, c ... z. Con so ke ben lacap chnh xac.

Bang 3.1 Phan bo mien dung sai cua he truc

(truc c s: ch thng) va he lo (lo c s: ch in)

3.5 HE THONG LO VA HE THONG TRUC


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CHNG 348

Tieu chuan ve dung sai lap rap hnh tru trn cua TCVN cothay oi nhieu qua tng thi ky. Hien nay, TCVN da tren tieuchuan quoc te ISO. e de dang tao che o lap rap gia truc va lo,ta can chon mot trong hai yeu to truc hoac lo lam chuan, thay oidung sai cua yeu to kia ta co the at c che o lap rap mongmuon. Co hai he thong:

1- He thong lo

Thng c dung va chiem en 90%- 95% cac moi lap trongc kh v lo la mat tru trong, kho che tao chnh xac va at o bongcao nh truc nen khi chon lo lam chuan, ta co the thay oi dungsai truc de dang at che o lap rap mong muon. Trong he thongnay, mien dung sai cua lo luon la H co sai lech gii han di bang0 sai lech gii han tren luon dng va phu thuoc cap chnh xac. Vdu, vi kch thc 100H8 th kch thc lo chuan la 100+0,15. Lo

tieu chuan de dang thc hien nh doa ( li doa Phap: AlesoirAnh: Reamer) a dc tieu chuan hoa t lau.

2- He thong truc

t c dung hn va ch chiem khoang 5%- 10% cac moi laptrong c kh v ly do a neu tren. Trong he thong nay ta chontruc lam chuan, thay oi dung sai lo at che o lap rap mongmuon.

He thong truc ch c dung khi mot truc ong thi lap vihai chi tiet lo vi cac che o lap khac nhau.

V du 3.1 Chot piston (Axe) xe gan may 10 phai lap trung gian(cho xoay) vi lo thanh truyen (Phap: Bielle; Anh: Connection rod)va lap chat vi lo piston c trnh bay nh tren hnh 3.1 di ay:


37/127


1- Vong gang chan Axe (s. lg 2); 2- Piston; 3- Thanh truyen, 4: Axe

Hnh 3.1 Moi lap axe piston vi lo piston va lo thanh truyen

Axe piston c che tao co lo gia cho nhe.V du 3.2 Moi lap gi then bang va ranh tren truc va tren lo cungtheo he truc v ly do noi tren. Vi knh thc danh ngha be rongthen la 12 th then lap chat tren ranh truc vi kieu dung sai nh

sau:7

810

h

Hva lap trung gian chat vi ranh tren lo theo kieu

6

710

h

K. Ta thay ieu nay phu hp vi thc te v truc ( be nhang

B cua then) c che tao de dang vi cung mot kieu dung sai 10h7

tren may mai phang. Neu dung he thong lo th khong the che taomot kch thc then 10 vi hai vung dung sai khac nhau.

Trong he thong nay, mien dung sai cua truc luon la h co sailech gii han di am, sai lech gii han tren bang 0 va phu thuoccap chnh xac. V du, vi kch thc 100h6 th kch thc trucchuan la 0 022,0100 . Hnh 3.2, moi lap then bang 108 gia truc va

then vi ranh tren lo va ranh tren truc theo he truc.


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CHNG 350

Hnh 3.2 Moi lap then bang 108 gia truc va then

vi ranh tren lo va ranh tren truc theo he truc. kch thc 38 em ra

ngoai truc c ve nam ngang theo TVVN cu hay ISO xem ep va de oc.

3.6 CAC CHE O GHEP HNH TRU TRN

Do yeu cau s dung trong thc te ma co ba kieu lap ghephnh tru trn vi cac mc o phan bo cua cac vung dung sai khacnhau gia truc va lo .

1- Lap chat (lap co o doi)

Khi ng knh truc ln hn ng knh lo:- Trong he thong lo vi mien dung sai lo chuan la H (lo c s)

th khi lap chat mien dung sai cua truc se la k, l, m, n...z- Trong he thong truc vi mien dung sai truc chuan la h (truc

c s) th khi lap chat mien dung sai cua lo se la K, L, M,

N...Z2- Lap trung gian

Khi kch thc truc va lo gan tng ng nhau:- Trong he thong lo vi mien dung sai lo chuan la H (lo c s)

th khi lap trung gian mien dung sai cua truc se la g, h, i, j.- Trong he thong truc vi mien dung sai truc chuan la h (truc

c s)th khi lap trung gian mien dung sai cua lo se la G, H,I, J.

3- Lap long

Khi ng knh truc nho hn ng knh lo:


39/127


- Trong he thong lo vi mien dung sai lo chuan la H (lo c s)th vi che o lap long mien dung sai cua truc se la a, b, c,d, e, f.

- Trong he thong truc vi mien dung sai truc chuan la h (trucc s) th vi che o lap long mien dung sai cua lo se la A, B,C, D, E, F.

3.7 CACH GHI DUNG SAI TRONG BAN VE LAPTrong ban ve lap ch nhng kch thc lap rap gia hai bo

phan mi c cat rieng phan e bieu dien kch thc va ghi kieudung sai. Kch thc co kieu dung sai lap ghep trong ban ve lapgom ba phan: Kch thc danh ngha chung cua hai thanh phanlap rap, ke tiep la mot phan so ma t so ch vung phan bo dung

sai cua lo (ch in), theo sau la cap chnh xac cua lo con mau so chvung phan bo dung sai cua truc (ch thng) theo sau la cap chnhxac cua truc. Ta can chu y en mot so ac iem sau:

- Vung dung sai lo luon t so va ghi bang ch in.- Vung dung sai lo luon mau so va ghi bang ch thng.

- Thng vung nao co mien dung sai H la thuoc he thong o(H in tren t so: he lo, h thng di mau so: he truc). Phan lntheo he lo nen co H in tren t so.

- Neu dung sai lo (t so) khac H ma dung sai truc mau so la

h thng th chac chan kieu lap theo he truc.- Khi ca hai vung eu co ky hieu H va h ca th phai xem xet

cac kch thc lien quan va dung kinh nghiem cong nghe e xetxem la he truc hay he lo ma 90% trng hp la he lo.

- Cap chnh xac cua lo tren t so luon thap hn cap chnh xaccua truc di mau so mot n v v lo kho che tao at chnh xaccao bang truc nen ta phai ha xuong mot cap. V du:

7840

k

H la moi lap chat va vi kch thc danh ngha 40

trong he lo, cap chnh xac truc la 7 cao hn cap chnh xac lo la 8mot n v.


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CHNG 352

7840

f

H la moi lap long va vi kch thc danh ngha 40

trong he lo, cap chnh xac truc la 7 cao hn cap chnh xac lo la 8mot n v.

78

25h

M la moi lap chat vi kch thc danh ngha 25

trong he truc, cap chnh xac truc la 7 cao hn cap chnh xac lo la 8mot n v.

7845

h la moi lap trung gian vi kch thc danh ngha

25, cap chnh xac truc la 7 cao hn cap chnh xac lo la 8 mot nv, cha xac nh c he truc hay lo nhng xac xuat he lo cao hn.

7825

h

n , ghi kch thc sai (v sao?).

7825KH , ghi kch thc sai (v sao?).

7

825

h

n , ghi kch thc sai (v sao?).

8

725

k

H , ghi kch thc sai (v sao?).

7

825

n

K , ghi kch thc sai (v sao?).

7825

Kh , ghi kch thc sai (v sao?).

3.8 CACH GHI DUNG SAI TRONG BAN VE CHE TAODa vao kieu dung sai ghi tren ban ve lap ta tra so tay ky

thuat dung sai lap rap hay theo bang dung sai 3.3 phan cuoichng nay e xac nh dung sai cu the cua kch thc nay cuatruc hoac lo ghi tren ban ve chi tiet.

V du:6725

k

H la kieu dung sai ghi tren ban ve lap th tren

hai ban ve che tao truc va lo ta phai:- Trong ban ve lo: tra dung sai 25H7 trong bang dung sai

3.3 cho lo va ghi kch thc cu the la 021,025+ cho lo.


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- Trong ban ve truc: tra dung sai 25k6 trong bang dung saicho truc va ghi ghi kch thc cu the la 015,0 002,025

++ cho truc.

Hnh 3.3, trnh bay kch thc trong ban ve che tao cua cua

truc va lo cua moi lap tru

6

740k

H va ranh then B= 12 tren lo va

truc nh sau:

Hnh 3.3 Trnh bay kch thc trong ban ve che tao

cua truc va lo cua moi lap tru6740

k va then. Chu y theo TCVN mi

kch thc 40 em ra ngoai at nghieng theo ng kch thc th

khong c ep va kho oc.

Khi ghi dung sai vao kch thc ban ve che tao, ta t oi tn v m cho tren bang thanh mm.

Mot iem can chu y la cong nghe tai nc ta hien nay ochnh xac ch mi at en 0,01mm tc la tren 10m. Nen cac giatr dung sai cho di gia tr nay hoac ghi en le phan ngan co tnhchat tham khao. o chnh xac gia cong tai nc ta trong vong 50nam qua khong tang len ang ke nen thi iem hien nay, macdu co nhieu trung tam cong nghe cao nhng cha phat huy cnhan lc, cong nghe va thiet b.

Mot vai thuat ng thng dung trong san suat tai nc ta vatren the gii:

- Dem (Phap Dixieme: 1/10mm)

- Cong nghe Viet Nam TCVN at o chnh xac 0,01mm (tcla Centieme)


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CHNG 354

- ISO Cong nghe the gii (ai Loan, Trung Quoc, Singapore,An o...) o chnh xac 0,001mm cong nghe micron

- c, Nhat, mot so nc chau Au at o chnh xac0,000001mm = 109m cong nghe Nano

- My at 1012

m cong nghe Pico a can thiep vao noi tainguyen t v 1 Amstrong 1 = 1010m.

Bang 3.2 trnh bay dung sai lap ghep hnh tru trn cho motso kieu va kch thc thng dung trong pham vi trng hoc ctrnh bay sau ay:


43/127

Bang 3.2 Dung sai cho truc va lo cap chnh xac 6,7,8 cho cac knh t

trong he lo (Lo c s): Dung sai co n v m

TRUCKTDN Lo c sH7 c8 d8 e8 f7 g6 h6 j6 k6 m6

1-3 +100

-60-74

-20-34

-14-28

-6-16

-2-8

0 -6 +4-2

+60

+8+2

>3-6 +120

-70-88

-30-48

-20-38

-10-22

-14-12

0-8

+6-2

+9+1

+12+4

>6-10 +150

-80-102

-40-62

-25-47

-13-28

-5-14

0-9

+7-2

+10+1

+15+6

>10-18 +18+0

-95-122

-50-77

-32-59

-16-34

-6-17

0-11

+8-3

+12+1

+18+7

>18-24

>24-30

+210

-110-143

-65-96

-40-73

-20-41

-7-20

0-13

+9-4

+15+2

+21+8

>30-40 -120-159

>40-50

+250

-130-169

-80-119

-50-89

-25-50

-9-25

0-16

+11-5

+18+2

+25+9

>50-65 -140-186

>65-80

+300

-150-196

-100-146

-60-106

-30-60

-10-29

0-19

+12+7

+21+2

+30+11

>80-100 -170-224

>100-120

+350

-180-234

-120-174

-72-126

-36-71

-12-34

0-22

+13-9 +25+3

+35+13


44/127


>120-140

-200-263

>140-160

-210-273

>160-180

+400

-230-293

-145-208

-85-148

-43-83

-14-39

0-25

+14-11

+28+3

+40+15

>180-200

-240+312

>200-225

-260+332

>225-250

+46

0

-260+352

-170

-242

-100

-172

-50

-96

-15

-44

0

-29

+16

-13

+33

+4

+46

+17

>250-280

-300-381

>280-315

+52

0 -330-411

-190

-271

-110

-191

-56

-108

-17

-49

0

-32

+16

-16

+36

+4

+52

+20


>315-355

-360-440

>355-400

+57

0-400-489

-210

-299

-125

-214

-62

-119

-18

-54

0

-36

+18

-18

+46

+4

+57

+21

>400-450

-440-537

>450-500

+63

0-480-577

-230

-327

-135

-232

-68

-131

-20

-131

0

-40

+20

-20

+45

+5

+63

+23


45/127

Bang 3.3 Dung sai cho truc va lo cap chnh xac 6,7,8 cho cac kn

trong he truc (Truc c s): Dung sai co n v

LOKTDN

Truc cs h6 D8 E8 F8 G7 H7 J7 K7 M

1-3 0

-6

+34

+20

+28

+14

+20

+6

+12

+2

+10

0

+4

-6

0

-1

-2

-1

>3-6 0-8

+48+30

+38+20

+28+10

16+4

+120

+6-6

+3-9

0-1

>6-10 0

-9

+62

+40

+47

+25

+35

+13

+20

+5

+15

0

+8

-7

+5

-10

0

-1

>10-18 0

-11

+77

+50

+59

+32

+43

+16

+24

+6

+18

0

+10

-8

-6

-12

0

-1

>18-30 0

-13

+98

+65

+73

+40

+53

+20

+28

+7

+21

0

+12

-9

+6

-15

0

-2

>30-50 0

-16

+119

+80

+89

+50

+64

+25

+34

+9

+25

0

+14

-11

+7

-18

0

-2

>50-65

>65-80

0

-19

+146

+100

+106

+60

+76

+30

+40

+10

+30

0

+18

-12

+9

-21

0

-3


46/127

>80-100

>100-120

0

-22

+174

-120

+126

-72

+90

+36

+47

+12

+35

0

+22

-13

-10

-25

0

-3

LOKTDN

Truc cs h6 D8 E8 F8 G7 H7 J7 K7 M

>120-140

>140-160

0

-25

+208

+145

+148

+45

+106

+43

+54

+14

+40

0

+26

-14

+12

-28

0

-4

>160 -180

>180-200

>200-225

>225-250

0

-29

+242

+170

+172

+100

+122

+50

+61

+15

+46

0

+30

-16

+13

-33

0

-4

>250-280

>280-315

0

-32

+271

+190

+191

+110

+137

+56

+69

+17

+52

0

+36

-16

+16

-36

0

-5


47/127

>315-355

>355-400

0

-35

+299

+210

+214

+125

+151

+62

+75

+18

+50

0

+39

-18

+17

-40

0

-5

>400-450

>450-500

0

-40

+327

+230

+232

+135

+165

+68

+83

+20

+63

0

+43

-25

+18

-45

0

-6


48/127


Chng4

MOI GHEP THAO C: REN VT4.1 KHAI NIEM

Ren vt la mot moi ghep khong the thieu c trong cac ketcau c kh. Ra i cach nay tren 100 nam, ren vt c dung vihai muc ch chnh la kep chat va truyen ong. Ngoai ra, ngi tacon dung no cho viec ieu chnh, ieu khien... Trong pham vi monhoc, chung ta tap trung nhieu vao muc ch chnh la van e kepchat, truyen ong cung c ban mot t cuoi chng. so vi cacmoi ghep inh tan , han va dan th moi ghep ren vis co u the hn

ac iem co the thao c va dung c nhieu lan.

4.2 CAU TAO REN VTRen (tieng Phap: Filet, tieng Anh: Thread) c hnh thanh

khi mot tiet dien phang co chuyen ong ta tren ng xoan oc truhay ng xoan oc non, tiet dien nay phai cha truc cua mat tru haymat non va co the co hnh tam giac, thang, vuong, than khai, tronvi cac cong dung khac nhau, S hnh thanh ng xoan oc tru vanon c trnh bay nh hnh ve 4.1 sau ay:


49/127

MOI GHEP REN VT 59

Hnh 4.1 Hnh thanh ren tren mat tru va mat non

4.3 REN KEP CHATDung ren vt e kep chat co tac dung nh moi ghep inh tan

a ban chng trc. Moi ghep ren vt co o on nh cao tuykhong bang inh tan nhng co u iem la co the thao lap ra cva dung c nhieu lan. Tiet ien ren kep chat luon la hnh tamgiac e tang ma sat phong moi ghep t thao ra.


50/127

CHNG 460

4.4 HAI HE THONG RENTrong he thong o lng quoc te ISO va cac nc co co tieu

chuan da tren ISO nh TCVN cua Viet Nam, tiet dien ren la hnhtam giac eu, goc nh 60o, con trong he Anh (ANSI, GB...) tiet

dien ren la tam giac can goc nh 55

o

.- Ve sc ben th ren quoc te do co tiet dien ay ln hn nenben hn ren Anh.

- Ve s kn kht th ren Anh vt troi hn ren quoc te do gocnghieng nho hn nen c ac biet dung trong he thong ong hi,ong nc, dau. He quoc te khong co tieu chuan cho cac loai ren knkht va chu ap lc nh ren Anh.

4.5 BU LONG, VT, AI OC VA EMPhan nay ban sau ve mot so thuat ng hien nay ngi ta

thng lam lan ngoai thc te cung nh trong trng hoc. La sinhvien, c hoc chnh quy, ta nen phan biet ro cac ten goi nhamtranh nham lan va chnh sa cho th trong luc lam viec sau nay.

1- Vt (Phap: Vis; Anh: Screw)

Vt la t c Viet Nam hoa t tieng Phap

Vt bao gom bat c bo phan nao co ren ben ngoai, conhnh dang au vt khong quan trong. Cac chi tiet trong hnh 4.2di ay eu co ten chung la vt.

1- Vt cay (Phap: Goujon, Anh: Stud)

2- Vt au luc giac (Phap: Vis a tete prismatique, Anh Hexagonal head srew)

3- Vt chm au bang xe ranh (Phap: Vis a tete fendue, Anh: Slotted head screw)

4- Vt au tron chong xoay (Phap: Vis a tete Goutte du Suif, Round clocked head screw)

5- Vt chm au loi parker (Phap: Vis a tete fraisee bombee, Anh: Philips round head screw)

6- Vt luc giac chm (Phap Grover, Vis a six pans creux, Anh Hex screw)

Hnh 4.2 Mot so loai vt thng gap


51/127

MOI GHEP REN VT 61

That ra hnh dang vt rat a dang, cac dang au vt se trnhbay sau. Ta ch can da vao nh ngha e nh danh vt.

Hnh 4.3 a/-Vis: tru co ren ngoai,b/- ai oc: lo co ren trong2- ai oc (Phap:Ecrou; Anh:Nut)

Ngoai th trng con goi la oc hay tan la bat ky chitiet nao co ren ben trong. Hnh dang ngoai cua ai oc khongquan trong. Cac chi tiet trong hnh 4.4 di ay eu co ten chungla ai oc.

1- ai oc em canh; 2- ai oc luc giac; 3- ai oc tron

Hnh 4.4 Cac loai ai oc


52/127

CHNG 462

3- em(Phap:Rondelle; Anh: Washer)

em con goi la long en do tRondelle cua Phap, la mieng thepmong hnh vanh khan co the lam

bang thep thng. Hnh dang ai octh a dang:

- em thng (Flat Washer):tron trn.

- em venh (Lock Washer)lambang thep an hoi co xe ranh.

- em canh: vong ngoai co dapcanh cach eu hay don 1 pha, vongtrong lo co ca .

em la bo phan trung gian lot gia bemat lap ghep va au vt hoac ai oc dung che ch, bao ve be mattranh co sc, ma sat troc sn, xi hay lun nt khi mat lap ghep lago, nha. Trong mot so may hien ai em thng che tao gan dnhchung vi ai oc e tien dung, nhng mat i mot phan chc nangv theo nguyen tac em khong c quay theo vt hay ai oc khiang xiet hay thao moi ghep. Thng be day em khoang0,080,15 ng knh nh ren d va co ng knh ngoai khoang2,2d. Cac chi tiet trong hnh 4.4 la mot so t em thng gap.

Rieng em venh day nhat (0,10d - 0,15d) nhng ng knh ngoailai nho (1,8d). V sao?

4- Bu long (Phap:Boulon, Anh:Bolt)

Bu long la mot bo gom ca ba bo phan vt, ai oc va emnen khi mua bu long th phai oi t nhat la co u vt va ai oc(hien nay tren th trng Viet Nam em thng ban rieng). Bulong co the ket hp vt va nhieu ai oc va em khac nhau tuyyeu cau s dung.

4.6 HNH DANG AU VTDo phuc vu cho nhieu nhu cau khac nhau ma au vt co nhieu

hnh dang a dang e co cong dung khac nhau. Thng chieu caoau vt thng bang 0,7 ng knh nh ren.

1

2

3

1- em thng2- em venh; 3- em canh

Hnh 4.4 Cac loai em


53/127

MOI GHEP REN VT 63

Sau ay ta se giai thch cong dung va mot so dang au vtthong dung.

- Vt au tam giac eu: sc ben rat kem, loai nay khong dungtrong c kh ma ch dung cho cac tu ien e an toan tranh nhng

ngi khong chuyen mon thao m tuy tien v co u iem la khongco canh oi nao song song nen khong the dung cha khoa thongthng (Phap: Cle, Anh Wrench) hoac mo let (Phap: Molette, Cleanglais, Anh:Adjustablewrench) e m.

- Vt au vuong: ay la loai au co sc ben tot nhat, lc vanrat manh, kho b tuon tron, nhng goc xoay phai en 90o mi xoaycha khoa lai c ma trong may moc von chat choi nen rat tdung trong c kh ngoai tr nhng ni rong rai, can lc xiet lnnh vt xiet u dao tren may tien, tay van mam cap may tien, vtetau may phay... Vt au vuong c ac che dung trong cac ket

cau sn nha thep, dam cau, cot ien cao the, ni rong rai ngoaitri nen bulong khong c bao quan trong dau nht de b r set,khong thao rap thng xuyen, sau mot thi gian lau mi m. Tuynhien hien nay tren th trng Viet Nam loai nay thng hiemnen nhieu ket cau xay dng cung dung loai au luc giac pho thong.

- Vt au ngu giac eu: ay cung la dang ac biet khong cohai canh oi song song nen khong dung Cle hay mo let m maphai dung cha khoa ac biet. Hien nay, vt ngu giac ch dungrieng cho nganh thuy cuc trong cac tru nc cu hoa mau o gantren le ng (Anh: Hydrant). Cac vt nay phai lam bang ong

thau tranh r set, de m, con cac nap ay ong cu hoa bang gangcung co num ngu giac.

- Vt va ai oc luc giac eu: la loai pho bien thng dungtrong ky thuat hay i song.

- au vt xe ranh (Slot): hien nay t dung trong c kh cungnh go v lc xiet khong ln, de treo ranh.

- au vt Parker (Phap:Parker, MyPhilips): gom co hai ranhsau tren mat au vt. Loai nay dung tournevis (Anh: Screwdriver)au Parker e van. Mang tnh tham my va cho lc xiet tng oi

manh hien c dung thay the cho vt au xe ranh.-au vt luc giac chm (Phap: Grover; Anh My:Hex) cho lc

xiet ln ben hn ca loai au luc giac ngoai. V luc giac chm trong


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CHNG 464

lo nen thng b ong bui, dau m nen phai ve sinh trc khi van.Dung khoa van luc giac chm (Alen) nho gon, nhng de b that lac.

-au vt dang ac biet:Tors Pozidriv

Tors Tamper Proof ClutchReed-Prince

t thay dung nc ta, co trong mot so may moc ien t, tatca dang au vis c trnh bay nh tren hnh 4.5.

5- Slot, 6- Parker, Anh Philips; 7- luc giac chm; 8- torx; 9- pozidriv

10- clutch; 11- reed-prince; 12- torx-tamper-proof

Hnh 4.5 Hnh dang au vt

4.7 HNH DANG AI OCai oc t co hnh dang a dang nh au vt, thng co cackieu sau:

- ai oc luc giac: loai pho bien nhat thng ca hai au euc vat 3045o e tien dung, ng cong tren 6 mat ai oc hayau vt luc giac la ng hyperbol, nhng trong ve ky thuat ta thaybang cac cung tron e de ve. Chieu cao cua ai oc thng bang 0,8ng knh nh ren.

- ai oc 12 canh co bien dang ac biet cua vai hang oto cocle chuyen dung e m (v du ai oc cot cac tambour banh xe cuahang Toyota).

- ai oc em canh: ai oc tron xe 4 hoac 6 ranh vong mattru thng loai nay dung chung vi em cach dung khoa phong


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MOI GHEP REN VT 65

long moi ghep ren, mot canh cua ai oc c be vao ranh. Ngi taco the dung cle co co (hai loai au cng va loai co khp lac) evan.

- ai oc tron hai lo: cac lo tron nho tren mat au phai

dung cle ac biet co hai chot e xoay. ai oc nay thng dung chocac may, dung cu tuy ong nh may mai cam tay may ca li catfibe.....

- ai oc tron kha nham: khi lc xiet khong can ln lam cothe xiet bang tay hay kem nh trong bo o co xe ap.

-ai oc canh chuon hay bien the co lo xo cay quay: co thevan bang tay nh ai oc van cot banh xe ap ua, hay cot xiet yenxe..

4.8 REN QUOC TE VA REN ANH

Hien nay co hai he thong o lng tren the gii nen cung cohai he thong ren quoc te va Anh.

1- Ren quoc te dung kep chat: co tiet dien la tam giac eu,goc nh 60o. Trong he thong quoc te ren vt c ac trng bangng knh nh ren ghi sau ch M in (M: viet tat cua Metric lahe met) ke tiep la dau x, sau o la bc ren. Bc ren la khoangcach hai nh ren ke nhau. Rieng ren bc ln hay con goi ren tieuchuan th viec ghi bc khong bat buoc. Thong so ke tiep la chieudai vt c tnh t co vt en cuoi uoi vt (khong ke chieu dai auvt) nhng du co ren suot hay co ren mot phan cung tnh tron

chieu dai than vt. Neu vt quoc te ng knh la d = 20, bc renla p = 2,5 chieu dai la L = 80 th c ghi kch thc nh sau:M202,580. Chieu dai ren cung khong bat buoc phai ghi nhat laai oc hay cac vis ac biet. Gon nhat la M20.

2- Ren Anh dung kep chat: co tiet dien la tam giac can, gocnh 55o. Ren Anh ra i trc va co u iem nh trnh bay phantren. Trong he thong nay ren vt c ac trng bang ng knhnh ren theo he inch, thng dung dang phan so thc theo truyenthong cua Anh, ke tiep la dau x, sau o la con so ch so ren trong

1 inch. Ngi Anh khong o trc tiep bc ren ma ch tieu chuanso bc ren trong 1 = 25,4mm. Thong so ke tiep la chieu dai vtc tnh t co vt en cuoi uoi vt (khong ke chieu dai au vt)nhng du co ren suot hay co ren mot phan cung tnh tron chieu dai


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CHNG 466

than vt. Chieu dai vt cung dung he inch. Neu vt ren Anh ngknh la d = 6,35 = 1/4, so bc la 25, chieu dai la L = 2 th cghi kch thc nh sau: 1/4252, vt nay gan tng ng viM6150 trong he quoc te. Ren Anh xuat hien trong ve ban vetheo tieu chuan Anh My nh ANSI, GB ngay ca ngay nay Uc vontrong khoi Lien hiep Anh nhng tieu chuan AS lai dung he met.Trong c kh Viet Nam ren Anh thng dung trong cac he thongong dau va kh can kn kht ma ren Quoc te khong the thay thec

4.9 CACH VE QUI C REN VA GHI KCH THC RENQUOC TE

4.9.1 Cach ve qui c renDo ren co hnh dang phc tap, la ng xoan oc nen trong ve

ky thuat, theo TCVN ta ch ve qui c ren theo nguyen tac sau: oi vi vt- nh ren ve bang net c ban.- Chan ren bang net lien manh (mot so tieu chuan khac tren

the gii ve net manh t khuc)

- Khoang cach t chan ren en nh ren bang23 lan bc

ren tc 0,866p nhng rat kho nh nen TCVN quy nh ng knhchan ren bang 0,85d ng knh nh ren.

Hnh 4.6 Gia cong tien cac loai ren


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MOI GHEP REN VT 67

Hnh 4.7 Kch thc moi ghep bulong

Hnh 4.8 Kch thc moi ghep vis


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CHNG 468

oi vi ai oc neu ve ri mot mnh th ve net c ban chong knh trong (chan ren) va net manh cho ng knh ngoai(nh ren), vay:

- ng chan net c ban.- nh ren ve net manh.

Khi ve mot moi lap gia vt va ai oc th u tien cho vt- Tiet dien ma vt va ai oc bat au tiep xuc phai ve net c

ban t nh en chan ren.- Khi cat ai oc net gach vat lieu phai tron ven len en het

phan ren ai oc.

Ve ren tiet dien mat au ca vt va ai

Ren ve cung tron net manh ln hn 3/4 vong tron, cung bieuren thng khuyet phan t th 3.

ng knh nh ren va bc ren thng chon theo tieu

chuan e tien che tao. Ngoai cac dung cu cat ren nh hnh choren trong la taro (Phap: Taraud, Anh: Tap) va ren ngoai la fide,ban ren (Phap Fillere, Anh: Dice) dung cho cac ng knh nhohn 16, cac ren ng knh ln c che tao bang tien tinh hoactien tho sau o sa lai bang taro hay ban ren.

4.9.2 Cac kch thc ren quoc te thng dung

ng knh ren kep chat quoc te co bc tieu chuan (bc to)pho bien co kch thc t 430mm thng dung, c ghi trongbang 4.1 di ay:

Bang 4.1

ng knh

nh

Bc ren Ghi kch ay u Ghi tat

4 0,5 M4x0,5 M4

5 0,75 M5x0,75 M5

6 1 M6x1 M6

8 1,25 M8x1,25 M8

10 1,5 M10x1,5 M10

12 1,75 M12x1,75 M12

14 2 M14x2 M14

16 2 M16x2 M16

18 2,25 M18x2,25 M18


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MOI GHEP REN VT 69

20 2,5 M20x2,5 M20

22 2,75 M22x2,75 M22

24 3 M24x3 M24

27 3,25 M27x3,25 M27

30 3,5 M30x3,5 M30

Trong san xuat cong nhan va ky s eu thuoc long cac kchthc tren v vay ta can thuoc e tien dung trong ve ky thuat cungnh ap dung sau nay.

4.9.3 Cach ghi kch thc moi ghep renTheo cong thc:

MdpL

trong o:

M- the hien he met, he quoc ted- ng knh danh ngha nh renp- bc ren, neu ren bc ln thuoc ban tren co the bo qua

thong so nay, con cac loai ren quoc te co bc tuy cung tieuchuan nhng khac vi bc tren la eu phai ghi ay u.

L- chieu dai vt tnh t sau co vt en het phan tru than vt duvt co ren suot hay ren mot phan cung tnh nh nhau (H.4.2)

- Neu ren trai th co ghi them cc chu v du: M121,560 rentrai hoac chu vi au vt hoac ai oc co tien ranh nho (Hnh.4.8).

V du, ren bougie xe gan may M10 bc nho la 1mm, chieu

dai phan ren la 20mm phai ghi u M10120.Ren M8 bc 1,25, dai 60 co the ghi M81,2560 hay M860

eu c.

V du, ng knh nh ren cua vt la 16, bc vt la 2 th taghi kch thc theo ng knh nh nh sau M162 hoac M16eu c v ren M16 bc 2 la bc ln, tieu chuan. Ghi kchthc lo ren cung tng t va luon luon ghi tren ng knh nhren (ay ren tren lo). Khi the hien moi lap gia vt va ai ocphai u tien cho vt c trnh bay nh trong cac hnh cac

trang sau.


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CHNG 470

4.10 REN PHAI VA REN TRAI: CONG DUNG VA CACHPHAN BIET

a phan ren vt c che tao theo chieu thuan goi la renphai, khi che tao ren phai bang cach tien th truc phoi phai quay

theo chieu thuan (t tren xuong hay ngc chieu kim ong ho khinhn vao mat au mam cap, con ban xa dao chay thuan t phaisang trai. Tien ren trai th co mot chuyen ong ngc lai.

Phan biet:

e biet ren trai hay phai, ta at truc vt thang ng, nhnthay ng ren quan len theo chieu phai la ren phai con ng renlen theo chieu trai la ren trai.

Ren phai (thng gap) van xiet chat vao theo chieu kim ongho, con ren trai ngc lai.

e phan biet ren trai thng tren au vt ngi ta tien motranh vong thanh cac hnh qua tram nh tren hnh 4.9 hay ghi kchthc co phu chu:

V du: M101, 5 ren trai

Hnh 4.9 Phan biet ren phai, ren traim neu ch noi ren th macnhien la ren phai


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MOI GHEP REN VT 71

M12x1,75x50

Hnh 4.10 Bu long ren trai va em be

Cong dung:

Ren trai co the dung e tendeur trong bo tang giam lc cangday cap, kep ep (ban kep dung ep khi dan ai).

Cong dung chnh cua ren trai la phong long cho moi ghepren. Nguyen tac e moi ghep ren khong thao ra c la chieu quayvt hay ai oc khi lam viec phai ngc lai chieu ren. V vay rentrai c dung khi van tren vat phai quay theo chieu kim ong holuc lam viec. V du, cot pedal ben phai luon co ren trai v pedalphai quay theo chieu kim ong ho. Nap che lp (libre) xe ap cochieu ren trai, nap nha xiet au cot quat treo tng eu ren traiv quat quay cung chieu kim ong ho (v sao chon chieu nh vay?).

Tuy nhien, trong may mai cam tay v ta thng quen vi ren phai,lai can thao lap nhieu nen cac nha san suat luon thiet ke cho amai quay ngc chieu kim ong ho e co the dung ren phai khoaa. Nen han che dung ren trai v ngi s dung khong quen thaotac siet, m, de nham va viec che tao kho khan, hn na giathanh at do khong co dung cu cat che san nh taraud, ban rennh ren phai.

4.11 REN BC TO VA REN BC NHUYEN, PHAM VIS DUNG

Bnh thng cac bulong dung kep chat tren th trng eudung ren bc to tieu chuan theo bang 4.1 nen khi mua vt hoacbu long ch can noi ng knh va chieu dai, mac nhien la renbc to. Ren bc to ch dung cho cac ket cau tnh, khong the bao


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CHNG 472

am phong long khi rung ong. trng hp nay co the dung renbc nhuyen hay ren trai.

Phong long: Ren nhuyen bc nho (thng la bu long ngoai)dung e phong long cho cac thiet b chu rung nho khi lam viec.

Nang cao o an toan do phong long hieu qua.V du, ai oc tac ke (Taquet) dung xiet cac banh oto vao mamtruc xe eu dung ren nhuyen. Ly do ren nhuyenco goc nang ren(goc xoan) nho nen kho thao long theo nguyen ly o doc cangnghieng cang de t thao ra theo trnh bay nh trong Giao trnhNguyen ly may, ta co:

dptg

=

Ta thay khi bc p cang be th cang be, moi ghep khotuot ra.

Giam lc xiet: trong cac c cau cao eu dung ren tam giacbc nhuyen e giam nhe lc tac ong cua tay va tang lc thao,tat nhien co li lc th co hai cho quang ng v so vong quayphai nhieu. V du: cao da, cao volant xe gan may, kch oi oto euthng dung ren nhuyen v ly do giam lc.

Tuy nhien, ren nhuyen th sc ben kem hn ren to khi cungng knh danh ngha, nen khi dung ren bc nho can quan tamviec tnh ben sc chu cua ren: ngi ta dung vat lieu tot va be dayai oc ln co nhieu vong ren lam viec lam giam ng suat tren ren.

4.12 REN SA CHA - VT CAYQuan sat ng knh va bc ren quoc te pho thong cho tren

bang 4.1, ta co the nhan xet rang ng knh ren la so chan (M6,M8... tr M5, M27). Do khi thao m nhieu lan thng ren b mon,ng knh vt nho lai, con lo ai oc rong ra, moi ghep ren de blong tuot, do vay can phai co bien phap phong tranh hay sa cha.Vt mon co the de dang thay bang vt mi nhng lo ren trong mayma b mon th viec thay the nguyen vo may mi rat ton kem nenngi ta co the dung mot trong hai bien phap sau:

1- Vt cay (Phap: Goujon, Anh: Stud)La mot vt tru khong co au, hai au vt cay eu co ren phai,

co oan gia trn khong ren ngan cach (Hnh 4.11). Mot au sec van chat en het ren tren lo a c taraud tren vo may. Khi


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MOI GHEP REN VT 73

xiet van vt cay co the dung dung cu chuyen dung, mo lech rangdung van ong tron hay co the dung hai ai oc bloque chat vi nhaukhi van vt cay vao th van ai oc tren con thao ra van ai oc di.Do vt cay gan lien tren lo vnh vien nen phan ren tren vis moncon ren tren lo vo may v thong thao m nen con nguyen. Vt cothe che tao bang vat lieu tot, t mon va khi co mon th co thethay vt cay mi. Vt cay thng dung khi moi ghep ren thngthao m. V du, vt tac ke (taquet) banh oto, cac cay tige doc xietblock may, au culasse tren xe gan may, oto eu la vt cay. Ket cauvis cay c trnh bay nh trong hnh 4.11 va 4.12.

2- Ren sa cha

Ngoai ra khi lo ren tren vo hop a mon ta co the dung renac biet e sa cha thay v khoan lo lam lai ren khac ng knhto hn nhng bc khac hn. Ren sa cha c che tao va ban

tren th trng (khong pho bien, ch co cac ca hang ln co ngibiet dung) nham muc ch thay the cac lo ren a mon. Theonguyen tac ren sa cha co ng knh ln hn ren hien dung 1n v va phai co cung bc. V du, ren sa cha M71 dung e saM61, M91,25 dung e sa cho M81,25, nhng can phai muaung loai taraud sa cha.

Bang kch thc ren sa cha thng dung cho tren bang 4.2

Bang 4.2

ng knh

nh

Bc ren Ghi kch ay u

7 1 M71

9 1,25 M91,25

11 1,5 M111,5

13 1,75 M131,75

15 2 M152

17 2 M172

19 2,25 M192,25

21 2,5 M212,5

23 2,75 M232,75

25 3 M253

28 3,25 M283,25

31 3,5 M313,5


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CHNG 474

Hnh 4.11 Cau tao va qui trnh che tao, lap ghep vis cay.


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MOI GHEP REN VT 75

Hnh 4.12 Vt cay trong lo bt


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CHNG 476

4.13 CHE TAO REN VTCo hai cach che tao ren vt trong san suat la che tao nho th

nghiem hay sa cha va che tao ai tra hang loat ln.

4.13.1 San suat nho n chiec hoac sa cha

Neu ren bc ln, tieu chuan va ng knh nho hn 16mmta co the dung dung cu nh hnh san chuyen dung e che tao renbang phng phap cat got. o la Taraud dung tao ren trong lo vaban ren (Fillere) dung tao ren ngoai tren mat tru. Ket cauTareaud va ban ren ve tren hnh 4.13.

Hnh 4.13 Khoan, doa (Alesoir, Reamer), loe, Taraud va Fillere (ban

ren)

1- Taraud

Vi mot ng knh ren tieu chuan, hien nay taraud c chemot bo gom hai cay taraud: cay cat tho, co vat nhieu au catkhoang 70% va cay taraud tinh cat 30% con lai. Trc ay mot botaraud cua Phap co ti 3 cay. Taraud co uoi vuong, c quay

bang can taraud. Can co the ieu chnh lo kep hnh vuong motpham vi nhat nh e kep c uoi vuong cua mot so taro.


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MOI GHEP REN VT 77

2- Ban ren(Filiere)

Ngc lai, moi ng knh vt ch can co mot ban ren, nhngco the chnh chieu sau cat bang mot vt chnh. Ban ren c attrong o co can e xoay.

Khi cat ren bang taraud hay ban ren ta can tra dau nht chotrn va quay ti khoang hai vong th phai quay lui khoang 1/2vong e be t bt phoi ra cho nhe. Taraud va ban ren can atthang goc vi be mat lo.

Vi ng knh vt va ai oc ln hn 16mm kho lam ren trctiep bang taraud hay ban ren v ng knh ln, chieu sau cat to,lng cat ln, ngi ta thng tien tho ren tren truc hoac lo sau otaraud hay filliere sa lai cho chnh xac.

4.13.2 San xuat hang khoi

Ngay nay e nang cao nang suat, chat lng va ha gia thanhsan pham ngi ta san xuat bu long bang phng phap gia congkhong phoi, can rang vt bang ban can, taraud may ren ai oc. auvt luc giac va ai oc c dap, gia cong va xi ma tren mot daychuyen khep kn. ieu nay lam ha gia thanh san pham ca chuclan va san pham at o chnh xac va chat lng cao cho nen trongky nghe che tao may moc, bu long thng mua ve rap ch khongche tao ngoai tr co hnh dang at biet hay ren vt tren vo mayth mi che tao bang cat got bang tareaud va ban ren.

4.14 KET CAU REN LO SUOT VA REN LO BTDo mui tareaud luon b vat con e de a vao lo luc mi

tareaud nen khi ta van tareaud gan cham ay lo bt th ren concach ay mot oan khoang 0,8 lan ng knh danh ngha ren, quic ve ng va khi van vt vao th ay cua vt khong the sat khtay lo khoan ma phan gii han ren nay thng cach ay khoang0,8 lan ng knh danh ngha ren. Do o, ren tren lo bt thngkho che tao va at tien hn ren lo suot nhng mot so ket cau dovach thanh qua day hay tranh x hi, dau, ngi ta van dung renlo bt. Cac ket cau ren lo bt va suot va cac loai vis c trnh baytren cac hnh 4.14 va 4.15 trang sau.

Trong san xuat, do yeu cau nho gon hay vi ly do ac bietnao o, ren co the gia cong en sat ay lo bt vi ieu kien vat lieu


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CHNG 478

cua lo mem (thau, nhom nha hay oi khi gang - rat hiem) phaidung taraud ac biet c mai bo oan vat au.

Hnh 4.14 Mot so ket cau ren, lo ren


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MOI GHEP REN VT 79

Hnh 4.15 Mot so loai vis va ai oc


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CHNG 480

4.15 REN TREN MAT CON - VT CONCo hai dang ren con dung cho go va dung cho kim loai:

4.15.1 Ren con dung cho go nha va tole mongMui nhon c dung e am thang vao lo go, nha nh lc

xiet van cua tournevt ma khong can phai khoan lo trc e tiendung. Tuy nhien, neu dung e xiet tam tole kim loai mong th cankhoan trc lo nho (ch can ln hn mui vt) khi van vao vt se tnong lo ra va lam tao ranh ren tren lo.

Mot iem can lu y la goc nh ren vt van lo rat be (di 10 o) tietdien ren rat mong, phan ranh rat to do sc ben go kem hn kimloai cua vt. e tang nhanh nang suat lap rap, hien nay co loai vtvan tole au co san mui khoan ch khoan mot lan tren may khoancam tay co au kep vis at biet.

4.15.2 Ren con dung cho kim loai e bt kn hay xa gio:

Tiet dien ren van la tam giac can goc nh 55 o theo he ren Anhc dung vi hai ac iem: kn kht va thao lap nhanh. Tuy nhien,mat ren con rat kho che tao nen gia thanh cao, at tien, can cannhac ky khi dung phai co doa con va taraud ren cone khong thayban tren th trng Viet Nam . a phan trong san xuat hang khoi

mi dung loai ren con nay. Ren con dung trong cac nut xa au tuyhien nay rat hiem, ngi ta thng dung ren tru va an toan va retien, de che tao hn. Vis cone c dung trong mot so ket cau acbiet th du ro net nhat cua ren con la vt xa gio trnh bay nh tren

1

2

Hnh 4.16 Vt cone xa giodau thang


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MOI GHEP REN VT 81

hnh 4.16. Vt xa gio dung xa bo khong kh tron trong ng ongdau thang ma bat ky he thong thang (phanh) thuy lc nao cung co.Khi can xa khong kh trong ra, ta m nap nha che bui pha trenra, dung cle m au luc giac mot t, ong thi ap hay bop canthang e Piston ay ti, khi o khong kh va dau theo ranh vong lot

vao lo doc truc vt va thoat ra. Ch can xiet nhe co the khoa ngthoat lai. Vt xa gio tiep xuc vi dau thang nen phai lam bang vatlieu tot nh thep mangan tranh an mon va r set. Thng vis xa gioat tren cao nhat cua he thong dau.

Ta thng gap ren con tren cac vis cone dung van go va viscone au co li khoan ch dung mot lan e khoan xiet cac tam tolemong(

Ket cau vis con co au khoan ve tren hnh 4.17:

Hnh 4.17 Vt co au mui khoan

Ngoai ra do ly do tham my va lc xiet khong ln lam mot so da72uvis co the che cau co co nganh vuong e chong xoay khong can gikhi van ai oc c trnh bay nh tren hnh 4.18.


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CHNG 482

Hnh 4.18 Bu lon au tron chong xoay


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MOI GHEP REN VT 83

4.16 CAC BIEN PHAP PHONG THAO LONG MOI GHEPREN

u iem cua moi ghep ren vt la co the thao lap c dedang, nhng ay cung co the la nhc iem v no co the t thao

long ra trong luc hoat ong do nhieu nguyen nhan ma chnh yeu larung ong. V vay, phong long luon la moi quan tam cua cac nhaky thuat v khi ren t thao se tao nen nhng nguy hiem tramtrong luc lam viec nhat la trong oto, can cau va cac thiet b sanrung. Co nhieu bien phap phong long vi mc o t thap en caoc trnh bay trong mot so bien phap di ay:

4.16.1 em lo xo khoa (Locked Washer)Dung em venh la bien phap n gian, re tien nhat thay v

dung em thng, ta thay bang mot loai em an hoi lam bangthep lo xo e khi xiet ep xuong, em tao mot lc cang doc truc lamtang ap lc tren mat ren va v vay tang lc ma sat lam can vt khithao ra. Co ba loai em lo xo:

- em venh: lam bang thep silic co tnh an hoi cao, cxe t vi goc 60o hng trai giup ta de van ai oc vao va hnhthanh nem chan kho thao ra. e bnh thng em venh nh tengoi se venh len va khi xiet chat em mi phang. Chu y ng knhngoai cua em khoang 1,8 ng knh nh ren va b ai oc chekn tranh nguy hiem cho ngi van hanh khong b canh xe caoxc. Hnh dang em venh c trnh bay trong hnh 4.11. Ket cau

em venh va vt au tron c trnh bay tren hnh 4.18- em lo so da: em co dang con nh ve pha tren khi et nhien va se dep lai khi van chat e tao lc cang doc truc trenren.

- em canh nho co bong: Mat em c tao thanh nhngmau go va b ep xuong khi van chat vi chieu trai lai chieu thao racua ai oc. Tren xe Jeep lun dung rat nhieu em nay vi vt 1/4.

4.16.2 em be mepCo hai loai:

- em be co ca: dung cho mot ai oc n co ca cam vao lonho khoan tren mat lap ghep, loai nay t thay c trnh bay trencac hnh 4.19


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CHNG 484

- em be co the dung khoa mot ai oc n hay khoa hai haynhieu ai oc vi nhau tren mot em ln th du cap em khoa 2 aioc tren da xch sau vao um tren xe gan may.

4.16.3 Ren bc nhoRen bc nho co kha nang phong t thao do goc nghieng

nho co trnh bay phan tren. Thng ren kep chat ban pho bien

tren th trng la bc ln, ren bc nho dung trong cac thiet bchuyen biet nh oto, can cau. Thng loai ren nay at tien dokhong c che tao ai tra ma chuyen biet cho mot loai may naoo.

4.16.4 ai oc top auau vt co mot oan ngan trn, co phay ranh nho, con ai oc

cung co phan au tien mong lai va khong co ren. Khi xiet chat aioc roi dung uc, ap lom phan vanh mong au ai oc sau xuongranh phay tren truc. Khi thao ra cung dung uc doc nong phan bop

lom len trc khi van ra. Loai ai oc nay ch thay dung tren motso hang oto nh Peugeot, Deawoo, Kia... dung xiet chan mam banhxe tren truc. Ket cau ai oc top au va vt au tron t khoa ctrnh bay nh tren hnh 4.20.


75/127

MOI GHEP REN VT 85

M14x25

4

15

15

0,7d

1,75d

d

321

0,1

5d

0,3d

0,8d

62

4321

em beVis M14x2x50Thep tam

Stt Ky hieuNgi ve

Kiem tra


NgayKy

BU-LONG KHOABANG EM BE

TL: 2:1

S.lng

1111

Vat lieu Ghi chu

5 ai oc M14x2

Thep tamTen goi S.lg

CT3

CT3CT3

M14x2x50

Hnh 4.19 Boulon va em be co ca cam vao lo khoan san tren

mat nen e phong long.


76/127


77/127

MOI GHEP REN VT 87

4.16.5 Hai ai oc BlocqueThng dung trong san xuat th nghiem, loai ton khong gian

chieu truc va kong kenh khong tham my. Sau khi xiet chat ai octren ta gi chat no va co van ai oc di ra en mc nang tay. Luc

thao ra th gi ai oc di va m ai oc tren trc.4.16.6 ai oc chot che

Thng dung nhieu trong san xuat hang khoi ln, cho o antoan cao. Tren truc khoan mot lo nho va lap chot che (Phap:Groupille) (con goi la chot bi). Khi van ai oc co xe 6 ranh trenau (Phap: Anh: Castle nut) vao chat va van lo tren truc lot vaomot ranh tren au ai oc, ta xuyen chot.

V tr va lc xiet co the thay oi trong goc 600. Ket cau ai oc chotche cho tren hnh 4.15.

4.16.7 ai oc em canhDung nhieu trong cac ket cau can khoa ai oc ma khong co

khong gian e xuyen chot che, cho o an toan cao tng ng viai oc chot che. ai oc em canh dung nhieu trong may nh xietnoi ly hp ma sat trong xe gan may, trong o bi long cau hai dayloai co ong lot (Phap: manchon, Anh: Bush). Ket cau ai oc emcanh cho tren hnh 4.21.

- ai oc hnh tron, xung quanh co xe 4 en 6 ranh tuy kchthc ng knh ln hay nho. Co hai dang ai oc khac nhau, cobe day thng mong hn loai luc giac, be day khoang 0,50,6dng knh ren.

- em canh c dap bang thep thng co so canh ngoaibang so ranh tren ai oc cong 1, v du ai oc co 4 ranh th dungem co 5 canh cac canh co the phan bo eu tren chu vi hay taptrung trong mot goc. Lo em co 1 g loi ra e lot vao ranh nhophay san tren truc.

au tien a em vao trc v g em lot vao ranh phay trentruc nen em khong the xoay tng oi so vi truc. Van ai ocbang cle co co hay ong en khi chat va co mot canh cua em trung

mot ranh tren ai oc, ta dung uc hay tourvis be canh lot vao ranhv vay ai oc b khoa khong the xoay tng oi so vi truc.


78/127

CHNG 488

M

30x20

4321

Banh rangem canhai ocTruc

Stt Ky hieuNgi ve

Kiem tra


NgayKy

AI OC EM CANH

TL: 1:1

S.lng

1111

CT3

Thep 45Vat lieu

TCVN

TCVN

Ghi chu

35H8/k7

5

4

3

2

1

M30

Thep 45CT3CT3

1

S.lgTen goi

Then bang5

Hnh 4.21 Khoa bang ai oc em canh


79/127

MOI GHEP REN VT 89

4.16.8 Dung chieu ren trai vi chieu chuyen ongChieu ren trai vi chieu chuyen ong cua truc co tac dung

khoa hu hieu v neu khi ong lc quan tnh cung la lc xiet renthem. Khi ang quay, neu co vat ca sat len ai oc th chieu lc ma

sat cung co xu hng xiet them ai oc. Nh phan gii thieu rentrai co trnh bay: ren trai dung phong long trong moi ghep cotpedale ben phai xe ap, lp xe ap, ai oc nha xiet au canh quat,cao volant xe gan may... Dung ren trai v chieu quay cua truc cungchieu kim ong ho. Tuy nhien, cac nha ky thuat thng han cheviec dung ren trai v

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