AI HOC QUC GIA HA NITRNG AI HOC CNG NGH----

BI TIU LUNB Mn: C s Thit k mayMI GHP REN

GVHD: C Thuy AnhNhom sinh vin thc hin:Phan Minh Tn Vn Tai Vu Vn PhuL Hng QunPham c VitHa Ni, 03/2013I- NH NGHA Ghp bng ren l loi ghp c th tho c .Cc chi tit my c ghp li vi nhau nh cc chi tit co ren nh: bulong v ai c,vtTy thuc vo vt xit ta c:mi ghp bulong (hnh 1a),mi ghp bng vt (hnh 1b) v mi ghp bng vt cy(hnh 1c).

Hnh 1:cc dng mi ghp rena)mi ghp bulong ; b)mi ghp bng vt ; c)mi ghp bng vt cy Ghp bng ren c dng rt nhiu trong nghnh ch to my.Cc chi tit c ren chim trn 60% tng s chi tit trong cc my hin i bao gm:cc chi tit mi ghp ren(bulong ,ai c,vt) a s cc chi tit thn my cn xit bng vt,cc trc c ren c nh v iu chnh hoc chi tit quayMi ghp ren cn c dung nhiu trong cc cn trc v cc kt cu thp dung trong vic xy dng,v nh chng m kt cu c ch to v lp ghp d dng. Vt xit thuc vo loi c chi tit c ng sut cao,c nhiu trng hp hng my lien quan n cc chi tit mi ghp ren quan trng. m bo tin cy thch hp ta cn kim tra lc xit ban u v dng cc phng php lng ai c. Mi ghp ren c dng nhiu v c nhng u im: Cu to n gin C th to lc dc trc ln C th c nh cc chi tit ghp bt k v tr no nh kh nng t hm D tho lp Gi thnh tng i thp do c tiu chun ha v c ch to bng cc phng php c nng sut cao.Nhc im ch yu ca mi ghp ren l c tp trung ng sut ti chn ren,do lm gim bn mi ca mi ghp. Ren c hnh thnh trn c s ng xon c tr hoc cn.Cho mt hnh phng qut theo ng xon c v lun nm trong mt phng qua trc OO (hnh3),hnh phng s qut thnh mi ren.Hnh phng c th l tam gic,hnh vung ,hnh bn nguyts to nn ren tam gic ,ren vung,ren hnh thang,ren hnh bn nguyt

II- PHN LOI V CC THNG S HNH HC CA REN

1. Phn loi ren Nu ng xon c nm trn mt c s l mt tr,ta c ren hnh tr,nu ng xon c l mt cn ta c ren hnh cn.Ren hnh tr c dng ph bin hn,ren hnh cn thng ch c dng ghp cc ng ,cc bnh du,nt du Theo chiu xon ng ren th ren c chia thnh ren tri v ren phi.Ren phi c ng xon ng i ln bn phi,ren tri c ng xon ng i ln bn tri. Theo s u mi ren ta c ren mt mi,hai mi v ba mi,Ren mt mi thng c dng ph bin.Cc dang ren ch yu theo cng dng v theo hnh dng tit din ,c th phn loi nh sau:Ren ghp cht: dng ghp cht cc chi tit my li vi nhau.Ren ghp cht gm cc loi ren:ren h mt(hnh 2a) ren ng (hnh 2d) ren trn ,ren vt g.Ren ghp cht kn: ngoi dng ghp cht cc chi tit cn dng gi khng cho cht lng chy qua ren(ren ni ng ng v ph tng ni ng).Ren c dng tam gic nhng khng c khe h hng tm v nh c bo trn.Ren ca c cu vt:dng truyn chuyn ng hoc iu chnh.Ren ca c cu vt c cc loai:ren vung,ren hnh thang cn(hnh 2b) ren hnh rng ca (hnh 2c)Ren h mt: c tit din l tam gic u,gc nh =60. d gia cng cng nh gim bt tp trung ng sut chn ren v dp xc nh ren,nh ren v chn ren khng c ht bng hoc to gc ln v bo trn.Bn knh bo trn chn ren r=H/6=0,144p.Theo tiu chun quc t ISO th bn knh gc ln i vi ren ngnh hang khng v v tr r=(0,15)p. Chiu cao ren H tam gic ban u: Chiu cao lm vic ca ren h:

Bng 1.ng knh v bc ren h mt(xem trong sgk) Ren h Anh c tit din hnh tam gic,gc nh =55.ng knh c o bng h n v Anh (1inch=25,4mm) bc ren c c trng bi s ren trn chiu di 1inch. Ren ng dng ghp cc ng vi ng knh 1/16 n 6 (1,5875152,4mm).Ren ng l ren h anh c bc nh,c bin dng c bo trn v khng c khe h theo nh v y tng kn kht.Kch thc ch yu ca ren ny l ng knh trong ng ren. Ren trn c dng ch yu trong cc bulong,vt chu ti va p ln hoc trong cc chi tit my lm vic trong mi trng bn v cn thit phi ni.Ren trn c dng trong cc chi tit my c v mng hoc trong cc vt phm c bng gang hoc cht do.Bin dng ren trn l cc cung trn c ni vi nhau bng cc on thng ,gc nh 30.Do bn knh cung trn ln nn c t s tp trung ng sut. Ren vung c tit din l hnh vung,=0,nn hiu sut cao.Trc y loi ren ny c dng nhiu trong cc c cu vt,nhng hin nay t dng v c thay th bng ren hnh thang v kh ch to, bn khng cao,kh khc phc khe h dc trc sunh ra do mn. Ren hnh thang cn c bn cao hn ren vung.Ren ny c bn cao hn ran tam gic,thun tin ch to v c bn cao hn ren hnh vung.Ren hnh thang cn c gc nh =30,chiu cao lm vic h=0,5p khe h hng tm 0,151mm ph thuc vo ng knh ren.Ren hnh thang cn tiu chun ha c ng knh d1=8640mm,c th s dng vi ren bc ln,trung bnh v nh.Ren hnh thang cn c dng trong truyn ng chu ti theo hai chiu. Ren c dng trong truyn ng chu ti mt chiu (trong kch vt,my p).Gc ln chn ren ca vt c tng ln gim s tp trung ng sut.Chiu cao lm vic h=0,75p Ren cn m bo khng thm thu v khng cn dng thm vng m kn.Chng c s dng ni cc ng ng ,nt vt,nt tho du khng thm thu t c bng cch p st cc bin dng theo nh.Xit ren cn c th b tr mn v to di cn thit.Theo cn ta phn bit c ren cn c ba dng vi cn 1:16: - Ren mt vi gc nh 60 - Ren ng vi gc nh 55 - Ren h Anh vi gc nh 60Ren vt bt g hoc ghp cc vt liu c bn thp,c tit din tam gic,chiu rng rnh ln hn nhiu so vi chiu dy ren, m bo bn u(v ct) ca ren vt thp v ren ca vt liu c bt vt. Ren vt c vn vo cc chi tit c bn thp c bin dng tam gic,chiu dy ren theo ng knh trung bnh nh hn na bc ren mt cch ng k bn vi chi tit m n vn vo. Cp chnh xc ng knh ren c khe h:vt c cp chnh xc 3 v ai c 48,Tng ng min dung sai i vi vt h,g,f,e,d v i vi ai c H,G,F,E.Min dung sai ngh cho mi ghp ren cho trong bng:tra SGK Hnh 2.cc dng ren ch yu2. Cc thng s hnh hc

Hnh 3 cc thng s hnh hc ca mi ghp renRen (hnh tr) c c trng bi cc thng s hnh hc ch yu sau y(hnh 3)d- ng knh ngoi ca ren,l ng knh hnh tr bao nh ren ngoi(bulong,vt) ng knh ny l ng knh danh ngha ca ren.i vi ai c ng knh ngoi Dd1- ng knh trong ca ren, l ng knh tr bao nh ren trong. i vi ai c l D1 d2- ng knh trung bnh, l ng knh hnh tr phn i tit din ren, trn chiu rng ren bng chiu rng rnh. i vi cc ren tam gic c ng knh trong v ng knh ngoi cch u nh tam gic ca ren v rnh ren, v i vi ren vung: d2 = (d + d1 )/2h chiu cao tit din lm vic ca ren.P bc ren l khong cch gia 2 mt song song ca 2 den k nhau,o theo phng dc trc bu long hay vt. - bc ng xon c, i vi ren 1 mi = p , i vi ren c mi : = p -gc tit din ren(gc nh) gc nng ren ( tham kho chng trc vt ) l gc hp bi tip tuyn ca ng xon c ( trn hnh tr trung bnh) vi mt phng vung gc vi trc ca ren:

Cc thng s hnh hc v dung sai kch thc ca phn ln cc loi ren c tiu chun ha.III- CC TIU CHUN K THUT CA REN1. Vt liu ch tao:Cac vt liu thng dung ch tao ren la thep cacbon thng, cacbon cht lng cao, thep hp kim( C35, C45, 38CrA, 30CrMnCA, 40CrNiMnA, 18Cr2Ni4VA)

Bng cc ren tiu chun ch yuIV- CAC PHNG PHAP GIA CNG RENC 4 phng php ch to ren: tin, phay, cn v mi.

TIN: 1. Ct ren bng dao tina. Dao tin ren ( Hnh2.5):- Vt liu lm dao tin ren c th l thp gi hoc hp kim, gc gia cc li ct ( gc mi dao) phi ph hp vi gc nh ren (60o i vi ren h mt, 55o i vi ren h Anh). Trong qu trnh gia cng dao c th m rng gc rnh ren v th gc mi dao c th c mi nh i sovi l thuyt, ty theo vt liu lm dao ta c: Dao thp gi th mi gc mi dao nh i khong 10 20, dao hp kim th mi gc mi dao nh i khong 20 30.- Thng thng gc trc dao tin ren bng khng, gc sau c hai bn bng 3 5o.- Khi ct ren c bc xon ln th ngi ta thng mi gc sau pha tin dao ln hn mt lng bng gc nng ca ren.- tng nng sut ct, ngi ta c th dng dao ct ren rng lc, dao rng lc c th l dao lng tr hoc dao a.

Dao n.

Dao aDao lng tr.Hnh 2.5: Dao tin ren.

b. iu chnh my tin ren bng dao:- ct ren trn my tin c chnh xc th cn xc nh chnh xc xch truyn ng gia trc chnh v bn xe dao: Chi tit gia cng quay mt vng th dao phi dch chuyn mt on bng bc xon (vi ren mt u mi l bc ren). Dao dch chuyn nh vo c cu vt ai c. (Hnh 2.6)- Khi trc vt quay mt vng th dao dch chuyn mt on ( bc xon):S = Svm x nvmTrong :- S: bc xon gia cng (mm)- Svm : Bc ren ca trc vt ( mt u mi) (mm)- nvm : s vng quay ca trc vt trong mt pht.- c bc ren, bc xon chnh xcth ta phi c mi quan h gia trc chnh v trc vt :nvm = ntc . iTrong :

- ntc : s vng quay trong mt pht ca trc chnh (tc )-i : t s truyn ng gia trc chnh v trc vt. c th thay i t s truyn ng gia trc chnh v trc vt chnh xc, ngi ta chia lm nhiu cp t s truyn ng:i = i1 + i2 + i3Trong :

+ i1 : t s truyn ng b bnh rng o chiu. (Pha sau hp trc chnh)+ i2 : t s truyn ng b bnh rng thay th. ( Hp bnh rng thay th)+ i3 : t s truyn ng hp tin dao ( bc tin).+ Trn my tin thng thng i1 v i3 l c nh.+ i vi cc bc ren tiu chun th ngi ta c th tin c ng bc ren bng cch iu chnh cc tay gt theo bng tr s bc tin gn trn my.+ i vi ren khng tiu chun th tin c ng bc ren th ngi ta phi tnh ton v lp li cc bnh rng thay th sao cho ng t s truyn ng i.

Hnh 2.6: S ct ren bng dao tinc. Cc phng php ln dao khi ct ren ( Hnh 2.7):- Ln dao ngang: ct ht bin dng ren th ngi ta thc hin ln dao sau mi lt ct bng cch quay tay quay ca bn dao ngang mt lng bng chiu su ct (phng php ny d thc hin, thng dng ct ren tam gic c bc nh)- Ln dao theo sn ren: ct ht bin dng ren th ngi ta thc hin ln dao sau mi lt ct bng cch quay tay quay ca dao trn c xoay mt gc bng na gc nh ren (phng php ny cng d thc hin, thng dng ct ren c bc trung bnh).- Ln dao kt hp: ct ht bin dng ren th ngi ta thc hin ln dao sau mi lt ct bng cch lun phin quay tay quay ca bn dao ngang v dao trn (thc hin ln dao ngang v ln dao dc). Phng php ny kh thc hin, thng dng ct ren c bc ln hoc ren c bin dng c bit: ren thang, ren vung, ..

Hnh 2.7: cc phng php ln dao khi tin ren.

Hnh 2.8: Ln dao khi tin ren vung v ren thang.d. Cc phng php li dao khi ct ren.- Khi ct ren ngi ta phi thc hin nhiu lt ct mi dt c chiu su ren. Sau mi lt ct phi thc hin li dao v ct lt k tip. Ty theo mi quan h gia bc ren gia cng v bc ren ca trc vt me trn my m ta c hai phng php li dao:a) Li dao bng cch th ai c hai na v quay bn dao dc tr v. Phng php ny thc hin c khi quan h gia bc ren gia cng v bc ren ca trc vt me trn my l bi s hoc c s. Cch ny rt d thc hin, nhng ch phi li dao ra theo hng ngang trc khi li dao dc.b. Li dao bng cch o chiu quay ca my ( o chiu quay ca ng c).Phng php ny thc hin khi bc ren gia cng khng l c s hay bi s ca bc ren trc vt me ca my. Cch ny kh thc hin hn v khi thao tc phi canh thi im tt ng c cho hp l dao khng ln vo cc phn khc ca chi tit v ng thi phi li dao theo phng ngang.e. Ct ren nhiu u mi:- Trong mt s mi ghp ren cn tho xit nhanh m yu cu s ren tham gia trong mi ghp ln ngi ta dng ren nhiu u mi.- Ren nhiu u mi gm nhiu ng ren trin khai trn cc ng xon c cch u nhau trn mt c s. Lc ny ta c bc xon bng k ln bc ren ( k l s u mi).- ct ren nhiu u mi v k thut c bn th cng tng t nh ct ren mt u mi. Ngi ta tun t ct tng ng ren, cc ng ren ging nhau v cch u nhau. phn khi ct ren nhiu u mi ngi ta c nhiu cch:i. Phn bng cch ch chuyn dao dc trc.+ Nguyn l: Tun t ct tng ng ren sau mi ln dch chuyn dao dc trc mt lng bng bc ren nh vo tay quay dao trn.+ c im:- Phng php ny n gin, d thc hin.D sinh ra sai s, nht l ren c bc khng chn.- Dng trong gia cng chi tit n l.+ K thut:- Dao ren g thng.- Ct mt ng ren tng t nh ct ren mt u mi c bc l bc xon..- Quay tay quay dao trn cho dao ch chuyn dc trc mt on bng bc ren cn tin. ( dao trn c b tr dc theo hng chy dao, Gi tr dch chuyn c xc nh nh vo du xch trn tay quay dao trn). Ngi ta cng c th ch chuyn dao nh vo bn dao dc, lng dch chuyn c th xc nh bng du xch trn tay quay dao dc hoc bng cc dng c o nh : Thc cp, Panme, Cn mu, Cn l.- Thc hin ct ng ren th hai tng t nh ct ng ren u.- Thc hin chu trnh trn cho cc ng ren cn li.ii. Phn bng cch xoay v tr n khp ca bnh rng thay th.Nguyn l: Tun t ct tng ng ren sau mi ln xoay chi tit ( khng n khp vi trc vt me) mt gc bng cch thay i v tr n khp ca b bnh rng thay th.c im- Phng php ny c chnh xc cao vi mi bc ren.- Thc hin phng php ny phc tp, khng thc hin trong trng hp s rng ca c hai bnh rng trong hp bnh rng thay th khng l bi s ca s u mi.- Dng gia cng chi tit n l.K thut- Dao ren g thng.- Ct mt ng ren tng t nh ct ren mt u mi c bc l bc xon..- M np che hp bnh rng thay th, nh du v tr n khp ca b bnh rng thay th, tho mt bnh rng c s rng l bi s ca s u mi v xoay mt gc, lp li cho hai bnh rng n khp.- Tip tc tin ng ren k tip.C nh th thc hin tt c cc u mi.iii. Phn bng dng c phn .Nguyn l: Tun t ct tng ng ren sau mi ln xoay chi tit mt gc nh vo mt a chia g trn tc chnh.c im:- Phng php ny c chnh xc cao. D thc hin.- Qu trnh thc hin phc tp.- Dng trong ch to hng lot.K thut- Dao ren g thng.- Chi tit c g trn b phn kp chi tit ca a chia .- Ct mt ng ren tng t nh ct ren mt u mi c bc l bc xon..- Ni lng kp ca a chia , xoay b phn kp phi ca a chia mt gc da theo s l c trn a chia. Kp cht b phn kp chi tit li.- Tip tc tin ng ren k tip.C nh th thc hin tt c cc u mi.2. Ct ren bng dao nh hnhThng thng , ct ren tiu chun c kch thc nh ngi ta thng dng dao nh hnh, cc loi dao nh hnh thng dng l Ta r, bn ren, dao rng lc.a. Ct ren bng Bn ren: Ct ren trn trc bng mt dng c ct ren nh hnh c gi l bn ren. Bn ren thc ra l mt b gm nhiu dao ct ren c ghp ni tip dc trc v c v tr ngang gia cc dao cch nhau mt khong bng chiu su ct. Bn ren c kt cu nh l mt chic ai c lm bng thp dng c hoc thp gi, trn bn ren c khoan t 3 8 l to cc thng s ct cho cc li ct, li ct hai u c vt cn qu trnh ct c bt u d dng hn, phn tr cn li l phn sa ng gm 5 6 vng ren. Bn ren c s dng bng c hai mt nh nhau.Khi ct ren bng bn ren ngi ta c th g bn ren ln ng hoc daoi. G bn ren trn ng: Bn ren c kp cht trong mt gi kp bn ren c th trt dc trn mt thn c chui cn lp vo ng. Quay tay quay ng a bn ren vo bt u ct, sau khi bn ren ct c 2 3 vng ren th bn ren s t ng c ko vo m khng xoay theo chi tit nh vo mt cht trt. Cch g ny cho php ct ren c chiu di ren gii hn.ii. G bn ren trn dao: Bn ren c lp vo tay quay bn ren g trn mt gi c th trt trong mt thn kp cht trn dao. chng xoay cho bn ren ngi ta b tr mt thanh t chn vo mt u ca tay quay. Tng t nh khi g trn ng, ta quay tay quay ca bn xe dao a bn ren vo v tr ct, sau khi bn ren ct c 2 3 vng ren th bn ren s t ng c ko vo m khng cn phi tin bn xe dao. Cch g ny cho php ta ct ren di v tn.

Ch :- Cn vt cnh u phi bn ren c th bt u ct d hn.- Khi ct ren bng bn ren, chi tit c tin vi kch thc b hn kch thc danh ngha v khi ct ren bng tay, b tr s nn vt liu.b. Ct ren bng Ta r: Ct ren trong l bng mt dng c ct ren nh hnh c dng l mt con vt c gi l Ta r. Tng t nh bn ren, ta r thc s l mt b gm nhiu dao ct ren c ghp ni tip dc trc v c v tr ngang gia cc dao cch nhau mt khong bng chiu su ct. Trn thn Ta r c ghi k hiu mc vt liu lm ta r v loi ren. Ngoi ra, phn bit th t cc cy tao r trong b ngi ta k hiu bng s vch hoc s vng cnKhi ct ren bng ta r ngi ta c th dng tay quay ta r hoc trc g ta r.i. G ta r bng tay quay: Ta r c kp vo tay quay phn chui vung, Ta r c bng mi chng tm vo l tm cui chui ca ta r. Cn tay quay s c bng thanh t g trn dao. Khi ct, ngi ta quay tay quay ng cho mi tm lc no cng t nh ln chui ta r.ii. G ta r bng trc g: m bo ng trc gia ta r v l cn gia cng, ngi ta thng dng trc g t la( ta r c kh nng lc l) lp nng ng bng chui cn. Khi bt u ct, ta quay tay quay ng a ta r t t vo l gia cng. Sau khi ct c hai ba vng ren th ta r s t tin vo ct ht l ren.c. Ct ren bng dao rng lc: Dao rng lc thc ra l mt b gm nhiu dao ct ren c ghp ni tip dc trc, cc dao thnh phn cch nhau mt khong bng bc ren. n gin trong vic mi sc dao, ngi ta dng ph bin dao rng lc hnh lng tr v hnh a. Khi mi li, ch cn mi li mt trc ca dao.K thut gia cng ren bng dao rng lc tng t nh ct bng dao ct ren thng thng, nhng s lt ct s t i rt nhiu hoc ch mt lt ct l .

PHAY RENt chnh xc v nng sut cao. Gia cng hng lot trn my phay chuyn dng. Phay on ren c chiu di ngn: nh hn 2-3 ln ng knh ren. Phay on ren c chiu di ln: phay ren ngoi, ren trong, ren thang, vung v rng ca c chiu di ln.

CAN RENGia cng ren bng bin dng do kim loi c tnh tt, tui bn ren cao. Bn cn phng, 2 qu cn, bn cn hnh vng cung, 3 qu cn

MAI RENGia cng tinh, yu cu chnh xc cao v gia cng b mt ren qua nhit luyn.

V- CAC CHI TIT GHEP CO MI GHEP REN Bulong: thng la thanh kim loai hinh tru. Gm hai phn: phn thn c ren vn vi ai c v phn u bu lng hnh 6 cnh hay 4 cnh u ta cac chia vn xit bu lng. Ren trn bu lng c gia cng bng ban ren, tin ren ,hoc can ren .bu lng dc phn ra: bu long th, bu lng ban tinh, bu lng tinh , bu lng lp co khe h, bu lng lp khng co khe h. Bu lng co ren trai va bu lng co ren phai. Bu lng la chi tit may c tiu chun hoa cao

ai c: l chi tit dng vn vi bu lng hay vt cy. C cc loi: 4 cnh, 6 cnh, ai c x rnh, ai c trn

Vong m: L chi tit lt di ai c, khi vn cht ai c khng lm hng b mt ca chi tit b ghp v thng qua vng m, lc p ca ai c c phn b mt cch u n.

Vt cy: L chi tit hnh tr, hai u u c ren.Vt cy c dng lp ghp nhng chi tit c dy qu ln hay v l do no khng dng c bulng. Mt u ren ca vt cy vn vo l ren ca chi tit b ghp, u ren kia vn vi ai c.

Vt cy c hai kiu:- Kiu A: u vn vo chi tit khng c rnh thot dao- Kiu B: u vn vo chi tit c rnh thot dao Vt cy c 3 loi:- Loi I: Vn vo chi tit bng thp hay ng: chiu di on ren Cht ch: L chi tit c xu qua l ca bu lng v rnh ca ai c, sau b gp hai nhnh ca n li kha cht ai c, khng cho ai c lng ra v chn ng.

Vt: Dng ghp trc tip cc chi tit m khng cn dng n ai c.Vt dng cho kim loi c hai loi:- Vt lp ni: Dng ghp hai chi tit vi nhau.- Vt nh v: Dng xc nh v trTheo hnh dng ca u vt, c cc loi: Vt u hnh tr, vt u chm cu, vt u 6 cnh, vt u chm, vt u na chm.

VI- CC MI GHP BNG REN(BU LNG , VT CY ,VT)1. Mi ghp bu lng n gin, mi ghp bu lng c v theo qui c, cc cung hypebn ca u bu lng v ai c c thay th bng cung trn nh hnh 4.22 hng dn. Cc kch thc ca mi ghp cn c vo ng knh ngoi ca ren tra trong bng 4.43. di ca bu lng tnh theo cng thc.L = b1+ b2+ Hd+s + a + cSau khi tnh c L cn i chiu vi TCVN 1892 76 xc nh chnh thc L ng vi tiu chun qui nh (bng 4.43):Cng c th tnh cc kch thc ca mi ghp theo cc cng thc sau:d1= 0,85 d, R = 1,5d; r xc nh khi vd2= 1,1d, R1= d,D = 2d, C = 0,15d,Dv= 2,2d, Sv= 0,15d,H= 0,8d, L = (1,5 ( 2)d.Hb= 0,7d, a = (0,15 0,25)d,

Ghi ch: Du x l loi bulng c ren trn sut chiu di thn

Mi ghp vt cy Cc kch thc ca mi ghp vt cy cng c tnh theo ng kinh ngoi ca vt cy theo TCVN 3068 81. ai c v vng m tra trong bng 4.44 v bng 4.45 tng t trong mi ghp bu lng.Chiu di on ren cy vo chi tit ph thuc vo vt liu ch to chi tit b ghp chn cho thch hp. Chiu di vt cy tnh theo cng thc:L = b + s + Hd+ a + c Sau khi tnh song phi i chiu vi bng tiu chun xc nh chnh thc L ng tiu chun quy nh.Ghi ch: Khng nn dng nhng ai c c kch thc trong ngoc n.

2. Mi ghp bng vtDng cho cc mi ghp chu ti trng nh. inh vt c vn trc tip vo l c renca chi tit b ghp khng cn ai c. di ca vt c tnh theo cng thc:L > b + l1 HTrong :b: Chiu dy ca chi tit ghp c l trn; l1: Chiu di ca ren;H: Chiu cao ca rnh chm trn chi tit ghp c l trn (Nu u vt c vn chm vo chi tit ghp).

3. Ghp bng ng ni ni cc ng ng (dn hi, dn kh hoc cht lng...) vi nhau, ngi ta dng phn ni (Hoc gi l u ni) tiu chun c ch to bng gang rn theo quy nh trong TCVN 1286 85. c trng ca ng ng l "ng thng quy c": Kch thc thc t ca ng thng qui c l ng knh lng ng o bng milimt. K hiu ca ng ng gm c ng knh ng thng quy c: Dqv s hiu tiu chun qui nh ng ng.V d: ng 20 TCVN 1286 85 Hnh 4.38: Cc loi u ni bng gang rn

VII- QUY C REN TRN BAN VE KI THUT1. Net ve cho cac loai rena. Ren thy Ren ngoi (ren trc): Ren ngoi l ren c hnh thnh mt ngoi ca chi tit.

- Ren trong( ren l ) :Ren trong l ren hnh thnh mt trong ca l.

** Quy c net ve cho ren thy: ng nh ren c v bng nt lin m. ng chn ren c v bng nt lin manh.. Trn hinh biu din vung goc vi truc ren ,cung tron chn ren c ve h ng tron vi tri goc trn bn phai,ng nh ren c v ng kn bngnt lin m ng gii hn ren c v bng nt lin m Khi ve mt ct i vi ren trong, ng gach gach c ke n inh ren.b. Ren khut (ren bi che khut)Nu ren bi che khut thi trn ban ve, ttca cacng: ng nh ren, chn ren, gii hn ren u c v bng nt t.

c. Ren hinhcnChi ve ren mt ay gn mt ngi quan sat

2. Ghi ki hiu renKi hiu ren th hin y u cac yu t cua ren va c ghi trn ng kich thc ng kinh ngoai cua ren.

Ph P

Cngthctngquat ghi ki hiu ren:Profin, ngkinhBcxon (P Bcren), Hngxon

Trong o:-Profin c ki hiu bng cac ch cai: M ,MC,G, Tr, G, Rp, R,Rc,S,M: profin cua ren h met la tam giacuMC: profin cua ren la tam giac co goc inh bng 60 Tr: profin la hinh thang cn co goc inhbng 30 - Bc ren(P):l khong cchgia 2 inh ren k nhau theo chiut ruc- Bc xon (Ph):la khoang cach theo chiu truc gia im u va im cui cua vong xon-Hng xon phai khng cn phai ghi, nu hng xon trai thi ghi LH.VD: Tr202LH: Ren hinh thang, ng kinh danh nghia d=20mm, bc ren P=2mm, xon traiM253(P1)LH: ren tam giacu, ng kinh danh nghia d=25mm, bc xon Ph=3mm, bc ren P=1mm, xon trai.

**Ghi ki hiu choBulong:Bulong la chi tit co 2 phn: Phn thn co renva phn mu hinh 6 canhu hay 4 canhu.

Ki hiu:Tn goi M ng kinh Chiu dai S hiu tiu chun

VD:Bulong M2080 TCVN 1892-76: bulong ren h met,ng kinh danh nghia d= 20mm, dai 80mm.

QUY C VE MI GHEP RENKhi ghep ren ngoai vi ren trong, tai vi tri n khp, ta quy c ren ngoai e ln ren trong va che khut ren trong. Do o, khi ve mi ghep ren:- Tai vi tri co n khp: Ta xem nh ang ve ren truc-Tai vi tri khng co n khp: Ta xem nh ang ve ren l

Mi ghep bulongai c

VIII- CAC PHNG PHAP CHNG THAO LONG - BN MI GHEP REN1. Cc dng hng ca mi ghp ren Khi sit cht bulong v ai c, cc vng ren ca bulong v ai c tip xc vi nhau. Cc vng rn cu ai c chu lc sit V. Cc vng ren trn Bulong chu phn lc Ft. trn mi ghp ren c th xut hin cc dng hng sau: Thn bulong b ko t ti phn c ren, hoc ti tit din st m bulong. Hoc b xon t trong qu trnh sit ai c. Cc vng ren b hng do ct t ren, dp b mt tip xc, hoc b un gy. Nu tho lp nhiu ln, cc vng ren c th b mn. M bulong b hng do dp b mt tip xc, ct t, hoc b un gy. Ngoi lc tc dng gm c lc dc trc va lc ngang.Lc dc trc c tc dng ging nh khi sit cht bulong v ai c.Lc ngang c tc dng lm dp, ct t thn bulong, lm dp l lp bulong hoc ct t tm ghp.Kch thc ca mi ghp bulong c tiu chun ha, cc kch thc c tnh theo ng knh d vi mt t l nht nh trn c s m bo sc bn ca c dng hng. Do ch cn tnh ton hn ch mt dng hng l cc dng hng khc cng khng xy ra.

2. Cac phng php chng tho lngB phn hn gi vai tr rt quan trng trong mi ghp ren chu ti trng ng. mc d cc loi ren dng trong lp ghp u m bo khi chu ti trng tnh ( nu f=0,1-> =arctgf=60 , nu f=0,3->= arctgf=160 lun lun ln hn gc nng ren = 1,40 ..3,300) nhng do v p vo rung ng trong qu trnh my lm vic nn ma st gia ren bulon v ai c gim bt, nn xy ra hin tng ai c b tho lng. Ngoi ra mt s ai c iu chnh nh: ai c chnh lc p trn bi a cn, trn tit iu chnh mng ui n, ai chnh cng cn phi hm li. C nhiu bin php hm da theo cc nguyn tc sau: S dng hai ai c

Sau khi vn ai c th 2, gia 2 ai c xut hin lc cng ph, chnh lc cng ny to ln lc ma st ph gi cho ai c khng b ni lng khi bulon chu lc dc trc ( hnh a) Phng php s dng hai ai c lm tng thm khi lng , khi b rung mnh vn khng m bo cht cho nn hin nay t dng S dng ai c t hm: bng cch p do u ai c thnh hnh elip sau khi ct ren, tao thnh di hng tm ca ren (hnh b) hoc to cc rnh hng tm trn u ai c. mt phng php khc l cn ln hoc cun vng hm bng Poliamid vo rnh ai c. khi xiaeets s to thnh lc ma st ln chng tho lng ai c. ai c hm ng kp n hi dng cn: Dng vng m vnh: y l phng php ph bin nht. Ma st ph sinh ra do lc n hi ca vng m vnh tc dng ln ai c. ngoi ra, ming vng m vnh lun t vo ai c chng cho ai c tho lng ra ngoi. Nhc im ch yu l to ra lc lch tm. khc phc ngi ta dng vng m l xo.Ngoi c phng php trn, ngi ta cn hm ai c bng cc phng php nh vng m gp, m hm c ngnh, cht ch, chnh, nhng phng php ny rt chc chn nn ch dng trong mi ghp khng tho.

3. bn renTheo tinh toan, vi ren co 10 vong, ren du tin chiu khoang 1/3 tng lc tac dung ln vit, ren cui cung chiu 0 trong xc nh theo cng thc (17.8).kho st trng hp tho vt ch trn ren v khng tnh n ma st trn mt ai c,khi ta c tg( - )>0 hoc : > (17.9) i vi ren gp cht gi tr ca gc nng ren nm trong khong 3030,gc ma st thay i trong khong 6 ph thuc vo h s ma st f =0,1 0,3 nh th tt c ren gt cht u c kh nng t hm. Cc ren c cu vt c kh nng t hm hoc khng t hm.Cc gi tr h s ma st tng ng dn ra trn chng t rng mi gt ren c h s an ton t hm cao, tuy nhin ch l trong trng hp ti trng tnh. Khi ti trng thay i nht l khi c s rung ng do c cc dch chuyn t vi ln nhau gia cc b mt ma st ( v d theo kt qu bin dng n hi hng tm ca ai c v thn bu lng ) h s ma st gim ng k ( f gim n 0,02 v nh hn ) . iu kin t hm b ph v sy ra hin tng t tho ai c.

XI- Tnh bulong1. Bu-lng ghp lng chu lc dc trc bu-lngai c khng c xit cht, lc xit ban u khng c.Gi F l lc dc trc ta c: => vi 0 l ng sut ko cho php ca vt liu lm bulong. T gi tr ca ng knh thu c ta tm c loi bulong cn thit.

2Bu lng c xit cht, khng c ngoi lc tc dngThn bulong chu lc ko do lc xit gy nn v chu xon do momen ma st trn ren sinh ra khi xit ai c.Trong trng hp ny ta c th dng cng thc n gin tnh theo bn ko vi ng sut tng ng bng 1.3 ln ng sut ko do lc xit V gy nn. 30% ng sut tng thm l xt n ng sut xon do tc dng ca momen trn ren. T iu kin bn: 3Bu lng chu tc dng ca lc ngang (lc tc dng trong mt phng vung gc vi trc). Bu lng lp c khe h: t iu kin bn ta c Trong : k l h s ma st gia 2 b mt; i l s mt tip xc gia 2 mt; F l lc tc dng. Bu lng lp khng c khe h: t iu kin ct ta c Trong : d l ng knh thn bulong; i l s b mt chu ct ca thn bulongNgoi ra trong trng hp : ng knh bulong ln hn chiu dy tm ghp tng i nhiu ta cn kim nghim iu kin bn dp: 4Bu lng c xit cht, chu lc dc trc khng i H s ngoi lc : vi l mm cc chi tit ghp ; l mm bulong. mm ca bulong: vi l l chiu di bulong ; E l modun n hi ca bulong; A tit din bulong mm ca cc tm ghp : Tnh ton bulong: Lc ton phn tc dng ln bulong sau khi c ngoi lc F: Khi lc tc dng ln cc tm ghp: m bo cc b mt ghp khng b h, cn c iu kin V >0 => V > (1-)F.Gi k l h s an ton ta c th vit: V=k(1-)FTheo iu kin khng tch h mi ghp: k = 1,3-1,5 khi ti trong ngoi khng i; k= 2,5-4 khi ti trng ngoi thay i.Theo iu kin kn kht: ming lt mm k=1,3-2,5; ming lt kim loi nh hnh k=2,0-3,5; ming lt kim loi phng k=3-5.Trng hp bulong chu ti trng tnh: vi = 1,3V +F phi nhn thm 1,3 v c xt n tc dng ca momen ren lc xit cht c.ng knh bulong: Trong trng hp phi xit bulong ngay khi ang chu ngoi: =1,3(V +F)

XII- MI GHEP NHOM BULONGXin trinh bay vn : Xac inh tai trong tac dung ln bulng chiu tai ln nht trong mi ghep nhom bulng. Xac inh c tai trong ln nht.sau o xac inh lc keo hoc lc ct ln nht tac dung ln bulng. T o tinh toan tim ra kich thc bulng phu hp cho mi ghep.1.Tai trong tac dung doc truc bulng va i qua trong tm nhom bulng.

Tai trong F tac dung doc truc bulng va i qua trong tm nhom bulng.VD: Tai trong ln bulng lp binh kin Fi = F/z , vi z la s bulng cach u.T o tinh c ng kinh trong cua bu lng theo CT:2.Ti trng tc dng trong mt phng ghpNu ti trng F tc dng trong mt phng ghp (H.17.27). Th ta a ngoi lc F v trng tm nhm bulng. Lc mi ghp nhm bulng s chu tc dng ng thi ngoi lc F i qua trng tm nhm bulng v mmen M=FL. Do ta kho st c lp hai trng hp : mi ghp chu lc ngang F i qua trng tm nhm bulng v mi ghp chu tc dng mmen M nm trong b mt ghp.a. Mi ghp chu lc ngang F i qua trng tm ca nhm bulng Khi ngoi lc F phn b u cho tt c z bulng trong mi ghp. Ngoi lc FFi tc dng dng ln mt bulng c gi tr bng nhau v xc nh theo cng thc FFi = (17.32)

ng knh ca bu lng c tnh nh trong trng hp ca hnh 17.17a ( bu lng lp c khe h ) hoc hnh 17.17b ( bu lng lp khng khe h) s dng cng thc (17.20) v (17.22)b Mi ghp chu tc dng mmen M Thng thng ngi ta s dng phng php tnh gn ng , xem nh hp lc ma st do cc bu lng c xit cht gy nn, i qua trng tm ca mi bu lng . chng xoay mi ghp th m men cc lc ma st i vi trng tm nhm bu lng phi ln hn m men ngoi lc M. Trng hp s dng mi ghp bu lng c khe hTrong trng hp s dng mi ghp bu lng c khe h th lc xit bu lng V c th xc nh theo iu kin b mt ghp khng b xoay theo cng thc: Tms = fVi M hoc fVi = kMT y suy ra V= Sau xc nh ng knh bulng theo cng thc (17.20) Trng hp s dng mi ghp bulng khng c khe hu tin ta xc nh ti trng ln nht tc dng ln bulng:i vi cc mi ghp c cc bulng nm cc u trng tm nhm bulng ( H17.25a) FMi = (17.33)trong D- ng knh vng trn qua cc tm bulng z- s bu lng trong mi ghpkhi mi ghp c hnh ty , ti trng tc dng ln mi bulng t l thun vi khong cch t tm bulng n trng tm ca nhm bulng. Trong trng hp tng qut xc nh lc tc dng ln bulng mi ghp chu tc dng ca mmen M. gi FM1 l ti trng tc dng ln bu lng c khong cch r1 xa trng tm nht FM2l ti trng tc dng ln bu lng c khong cch r2 , FM3 ng vi r3.. ta c:

V ch n cc h thc lin h gia FMi trn , ta thu c ti trng FM1 tc dng ln bulng chu lc ln nht ( bulng xa trng tm nht):

Trong zi l s bulng c khong cch ri n trng tm nhm bulng bng nhauT y suy ra: FMi = ( 17.34b)

c. mi ghp chu lc ngang F khng i qua trng tm ca nhm bulng. Di chuyn song song lc F v trng tm nhm bu lng v thm vo mmen M. khi mi ghp xem nh l chu tc dng ng thi ti trng F i qua trng tm v mmen M. Di tc dng ca lc ny b mt ghp c th b xoay hoc trt ln nhau. Theo cng thc (17.32) (17.33) hoc (17.34b) ta xc nh lc FFi v FMi tc dng ln tng bulng th i v theo s lc ta xc nh ti trng ln nht Fmax tc dng ln mt bu lng trn nhm v tnh ton ti trng ln nht theo cng thc cosin. V d trn hnh 17.27 ti trng tc dng ln bulng 1 hoc 2 l ln nht:

sau khi tnh ton, v so snh v xc nh cc gi tr ti trng ln nht trn bu lng, ty vo mi ghp c khe h hoc khng c khe h ta xc nh lc xit v ng knh bu lng hoc kim nghim bu lng theo tiu ch

Mi ghp khng c khe h : ti trng ln nht tc dng trc tip ln thn bu lng . bn ca lng v b mt ghp tnh theo ng sut ct v dp ( cng thc 17.21- 17.23)Mi ghp c khe h : ti trng ngoi tip nhn bi lc ma st trn b mt ghp, to lc ma st ny ta cn phi xit bu lng. Gi s gn ng rng lc ma st t ti tm l lp bu lng. Mi ghp bn, nu nh lc ma st trn mi bu lng ln hn ti trng ngoitc dng bu lng Fi. V tt c bu lng u xit bi mt lc xit nh nhau cho nn lc xit bu lng xc nh theo ti trng ln nht tc dng ln bulng V = Sau s dng cng thc (17.20)( mi ghp c khe h) tnh ng knh bulng.3. Tai trong tac dung co phng bt kiGia s mi ghep chiu tai trong co phng bt ki nm trong mt phng i xng XY. Xem mi ghep u cng va bulng c phn b u.Ngoai lc F c phn ra 2 phn : Fv va Fh. a chung v trong tm moi ghep ta co momen:

Tai trong Fv va M co xu hng tach h b mt ghep, con Fh lam tm ghep bi trt. Mun cac chi tit may bi ghep khong bi tach h va trt cn xit bulng vi lc xit V.

a. Tinh toan mi ghep khng bi tach h.Khi cha co ngoai lc Fv, mi ghep chiu ng sut dp: Co Fv ng sut dp giam i mt lng: Khi chiu tac dung cua momen M, mi ghep co xu hng bi xoay quanh mt truc nao o trong mp phng ghep. ng sut do momen Mm tac dung ln cac chi tit ghep , trong o Wm la momen can un b mt ghep.ng sut tng ln nht va nho nht do cac lc xit va ngoai lc tac dung ln b mt ghep.:

Biu ng sut:

Wm ~ W , Am ~ A do din tich b mt ghep kha ln so vi din tich l ghep bulngFm ~ Fv , Mm ~ M do cac chi tit kha cng. mi ghep khng bi tach h thi: min >0 hay

Tinh c xit V cn thit: cho an toan: , vi k [1,3-2] : h s an toanb. Tinh toan mi ghep khng bi trtHin tng trt xay ra khi dung bulong lp co khe h gia l va thn bulng ma khng co cht giFH la lc gy trtFH bi can bi lc ma sat trn b mt ghepMi ghep khng bi trt khi: FH < Fms f(zV-Fms)> FH an toan : f(zV-Fms)> kFH , k [1,3-2] thao man iu kin trn thi lc xit vi mi bu lng phai at:

Khi FH qua ln, phai dung bu lng lp khng khe h, hoc dung thm cac chi tit nh then, cht can trt.c. Tinh toan chon bulng thich hpNgoai lc xit V, di tac dung cua ngoai lc, cac bulng con chiu thm cac lc Fb va Mb.Fb gy ra cho mi bu lng mt lc: Fb/zGoi FM1 ,FM2 ,FM3 do Mb gy ra tai cac bu lng cac truc XX cac oan Y1, Y2 Y3 ta co

iu kin cn bng:

Tng lc ln bulng chiu tai ln nht:

**Khi dung mi ghep bu lng co khe hTheo CT xac inh ng kinh trong: , ap dung vi F=Fmax Tim c loai bulng thich hp**Khi dung mi ghep bulng khng co khe hng sut phap cc tri:

ng sut tip cc tri:

Bin ng sut: , A1 la tit din bulngKim tra bn dp: , nu khng thoa man , tng kich thc b mt ghep.

XIII- MI GHP VNG KP1.Kt cu v ng dngMi ghp vng kp (H.17.29) l mi ghp ma st , trong p lc php tuyn cn thit c to bng lc xit bulng .Ngi ta s dng mi ghp vng kp bng vng kp c nh trn trc tm v trc chuyn, trn cc ct hnh tr, gi . Cc chi tit nh tay quay, bnh ai, cc vng v..

Mi ghp bng vng kp khng yu cu s dng then, do cho php lp chi tit bt k ti v tr bt k theo chiu di trc (c cng ng knh). Trc khng b yu i do khng c rnh then, tuy nhin mi ghp vng kp b mt cn bng v c knh thc ln khi ti trng ln. Theo kt cu ta phn bit hai dng ch yu ca mi ghp bng vng kp:a) Vi may tho c May tho c lm tng khi lng v lm tng gi thnh mi ghp, tuy nhin ta c th t vng kp ti v tr bt k trn trc .b) Vi may c rnh ( H 17.29b).Khi ghp cc chi tit bng cc vng kp nh vo lc ma st sinh ra do xit cc bulng . Nh vo lc ma st ny m chi tit ghp khng b trt di tc dng ca mmen M= Fl v lc dc trc F. Tuy nhin truyn ti trng nh lc ma st khng ng tin cy cho nn mi ghp bng vng kp s dng truyn cng sut nh.u im ca mi ghp bng vng kp l n gin tho lp, thay i v tr d dng.

2 Tnh Ton Theo BnMi ghp bng vng kp c thit k theo mmen xon T hoc ti trng dc trc F .Nngoi ra cn thit phi tnh bulng. Quy lut phn b p sut theo b mt ma st ph thuc vo cng may , khe h hoc di ban u.Ph thuc vo cng dng mi ghp khi tnh ton ta kho st hai trng hp gii hn.1- Trng hp 1: vng kp c cng cao. Lp cc chi tit thc hin vi khe h ln (H17.30a). khi cc chi tit tip xc theo ng thng song song trc. iu kin bn mi ghp biu din theo cng thc:Fmsd = FnfdT; 2FnfF ( 17.49a)Trong Fn l phn lc tip xc. f l h s ma st.iu kin cn bng ca na vng kp:Fn= 2Vz (17.49b)Trong V- l lc xit bulng, z sai s bulng mi pha vng kp. Thay th biu thc (17.49b) vo (17.40a) ta c:2Vzfd T ; 2zVf FSuy ra lc xit V = v V = 2 .Trng hp 2: cc vng kp mm, hnh dng b mt tip xc c dng tr, khe h trong mi ghp gn bng 0 (H.17.70b). Khi p lc trn b mt ghp ln nht c hng vung gc mt tho, v nh dn bng 0 ti v tr mt tho theo quy lut cosin p= cosTuy nhin thun tin tnh ton ta gi s p lc p phn b u trn b mt tip xc, iu kin bn mi ghp c th biu din theo cng thc :pfdb T ; pfdb FMt khc p lc trn b mt ghp xc nh theo cng thc:Fn = 2 bd = pdb;Tuy nhin phng trnh cn bng lc i vi na may (H17,30b): 2Vz = FnT y suy ra p = Sau khi thay th v rt gn ta thu c:Vfzd T; 2zVf F (17.51);Suy ra lc xit V xc nh theo cng thcV=; V= ( 17.52)Nh th kh nng ti trong hai trng hp gii hn chnh lch nhau l 2. Do tn ti khe h ln trong mi ghp dn n ph hy vng kp do ng sut un. Trong thc t mi ghp vi khe h ln gi l hng hc .Trong ch to my kch thc cc chi tit mi ghp vng kp thc hin dung sai H8/h8. Vi mi dung sai lp ghp ny m bo lp t do cc chi tit my khng c khe h tha.Trong thc t t cc phn tch trn c s cho vic xc nh lc xit mi ghp vng kp nm trong khong gia cc gi tr gii hn trn. 2,5Vzfd T ; 5zVf F (17.53)Tnh ton mi ghp trong vng kp phn b cc bulng v mt hng (H17.29a) c thc hin theo (17.51). Thc t nu bulng trn ca kt cu theo hnh 17.30a c hn vi cc chi tit khc nhau th iu kin kin lm vic trong vng kp v bulng khng thay i, khi kt cu biu din theo tng t kt cu hnh17.29b.T cng thc (17.53). ta suy ra cng thc xc nh lc xit nh sau:V= v V=; (17.55)Khi tc dng ng thi T v F th lc tc dng ln b mt ghp ng thi s l F v lc vng Ft=2T/d. Trong nhng trng hp ny:V=Trong z l s bulng phn b trn mt hng ca trc ; k=(1,3->1,8) h s an ton . h s ma st gia gang v thp khi lm vic khng c bi trn c gi tr f= 0,15->0.18.Sau khi xc nh lc xit V ta x nh ng knh bulng theo bn ko.

XIV- U-NHC IM CA MI GHP REN u im Cu to n gin Mi ghp bo m Cc kiu ren a dng C th c nh cc chi tit my bt k v tr no nh kh nng t hm D tho lp, c th tho lp nhiu ln C th chu c lc dc trc ln Gi thnh tng i thp do c tiu chun ha v c ch to bng cc phng php c nng sut cao nh cn ren. Nhc im C tp trung ng sut ti chn ren cho nn lm gim bn mi ca mi ghp.

1