1 TRNG I HC NHA TRANG KHOA C KH NG QUANG TRNG BI GING THIT K DNG C CT Nha Trang, 2011 2 Mc lc Mc lc .....................................................................................................................................1 VN 1.................................................................................................................................6 C S L THUYT THIT K DNG C CT..............................................................6 1.1C s l thuyt to hnh b mt: ..............................................................................6 1.2ng hc to hnh b mt chi tit ............................................................................7 1.2.1Nhm bc 0........................................................................................................8 1.2.2Nhm bc 1........................................................................................................8 1.2.3Nhm bc 2........................................................................................................9 1.2.4Nhm 3...............................................................................................................9 1.3Mt khi thy K ca dng c ct ...........................................................................10 1.4.1Phng php xc nh mt khi thy K ca dng c bng mt bao ca h mt chi tit C. ..................................................................................................................10 1.4.2Phng php gii tch xc nh mt khi thy K..........................................11 1.4.3Phng php ng hc xc nh mt khi thy K........................................11 1.4Nhng iu kin to hnh ng b mt chi tit ................................................13 1.4.1iu kin cn...................................................................................................13 1.4.2iu kin .....................................................................................................14 VN 2...............................................................................................................................16 DNG C CT N V DNG C CT TIU CHUN............................................16 2.1 Cng dng v phn loi ...............................................................................................16 2.2 Thng s hnh hc phn ct ca dng c....................................................................17 2.2.1 Cc chuyn ng khi ct .......................................................................................17 2.2.2 Cc mt phng ta v cc tit din..................................................................17 2.2.3 Cc gc phn ct ca dng c ..............................................................................18 2.3 Xc nh kch thc thn dao tin...............................................................................19 VN 3...............................................................................................................................21 THIT K DAO TIN NH HNH GIA CNG B MT TRN XOAY TRN MY TIN........................................................................................................................................21 3.1.Cng dng, phn loi v phm vi s dng ............................................................21 3.2.Mt trc, mt sau v kt cu dao tin..................................................................22 3.3.Thit k dao tin nh hnh hng knh.................................................................24 3.3.1.Gc trc, gc sau ti cc im ct nhau trn li ct dao tin nh hnh..24 3.3.2.Xc nh profin li ct dao tin nh hnh hng knh g thng ...............26 3.4.Sai s khi gia cng bng dao tin nh hnh..........................................................30 3.4.1.Kho st sai s khi gia cng chi tit bng dao tin nh hnh hnh lng tr:30 3.4.2.Kho st sai s khi gia cng chi tit bng dao tin nh hnh hnh trn: .....30 3.5.Chiu rng B ca dao tin nh hnh: ....................................................................31 3.6.Hnh dng v kch thc kt cu dao tin nh hnh: ...........................................32 VN 4...............................................................................................................................33 THIT K DAO PHAY RNG NHN..............................................................................33 4.1.Cc yu t kt cu chung ca dao phay:................................................................33 4.1.1.ng knh dao phay:.....................................................................................33 4.1.2.Kch thc lp ghp: .......................................................................................34 4.1.3.S rng: ............................................................................................................35 4.1.4.Cc gc rng v rnh rng: ..........................................................................36 4.1.5.Dng rng v rnh: ..........................................................................................36 3 4.2.Thng s hnh hc phn ct ca dao phay:............................................................37 4.2.1.Gc sau : ........................................................................................................37 4.2.2.Gc trc : .....................................................................................................38 4.2.3.Gc nghing chnh :......................................................................................38 4.2.4.Gc nghing ph 1:........................................................................................38 4.2.5.Gc nng ca li ct chnh : .......................................................................38 4.2.6.Gc nghing ca rnh xon : .......................................................................39 VN 5...............................................................................................................................41 THIT K DAO PHAY LNG...........................................................................................41 5.1.Cc yu t kt cu chung ca dao phay:................................................................41 5.2.ng cong ht lng dao phay:.............................................................................41 5.2.1.ng cong ht lng dao phay: .....................................................................41 5.2.2.Phng trnh ng cong ht lng l ng xon Acsimet: .......................42 5.2.3.Lng ht lng K v gc sau nh rng d................................................42 5.3.Thng s hnh hc phn ct ca dao phay ht lng..............................................43 VN 6...............................................................................................................................46 THIT K MI KHOAN.....................................................................................................46 6.1.Cng dng v phn loi ..........................................................................................46 6.2.Cc yu t kt cu ca mi khoan rnh xon........................................................46 6.2.1.Gc nh 2..................................................................................................46 6.2.2.Gc nghing ca rnh xon ............................................................................48 6.2.3.Cc gc ca li ct ........................................................................................49 6.3.Cc kiu mi khoan ................................................................................................51 6.3.1.Mi khoan c lm ngui t pha trong ......................................................51 6.3.2.Mi khoan gn mnh hp kim cng ..............................................................51 VN 7...............................................................................................................................53 THIT K MI KHOT ......................................................................................................53 7.1.Cng dng v phn loi ..........................................................................................53 7.2.Cc yu t kt cu ca mi khot ..........................................................................53 7.2.1.S rnh .............................................................................................................53 7.2.2.Phn ct ............................................................................................................53 7.2.3.Phn sa ng..................................................................................................54 7.2.4.Cc gc ct.......................................................................................................54 7.2.5.Gc nghing ca rnh .....................................................................................55 7.2.6.Bin dng rnh.................................................................................................55 7.2.7.Dung sai ng knh mi khot .....................................................................56 7.3.Cc kiu mi khot .................................................................................................57 7.3.1.Mi khot hai rng ..........................................................................................57 7.3.2.Mi khot l tr chm......................................................................................58 7.3.3.Mi khot l cn chm....................................................................................58 VN 8...............................................................................................................................60 THIT K MI DOA...........................................................................................................60 8.1.Cng dng v phn loi ..........................................................................................60 8.2.Cc yu t kt cu ca mi doa..............................................................................60 8.2.1.Phn ct ............................................................................................................60 8.2.2.Phn sa ng..................................................................................................61 8.2.3.S rng .............................................................................................................61 8.2.4.Hng ca rng ...............................................................................................61 4 8.2.5.Gc sau v gc trc ca phn ct.................................................................62 8.2.6.Cnh vin .........................................................................................................63 8.2.7.Dng rnh.........................................................................................................63 8.2.8.S phn b rng khng ng u...................................................................64 8.2.9.Phn kp cht...................................................................................................64 8.3.Cc kiu mi doa.....................................................................................................64 8.3.1.Mi doa tng....................................................................................................64 8.3.2.Mi doa hp kim cng....................................................................................65 8.3.3.Mi doa lp rng..............................................................................................65 8.3.4.Mi doa cn.....................................................................................................66 VN 9...............................................................................................................................68 THIT K DAO CHUT.....................................................................................................68 9.1.Cng dng v phn loi ..........................................................................................68 9.2.Cc b phn ca dao chut .....................................................................................68 9.2.1.Phn u kp dao.............................................................................................68 9.2.2.Phn c v phn cn chuyn tip ...................................................................69 9.2.3.Phn nh hng trc....................................................................................70 9.2.4.Phn nh hng sau.......................................................................................70 9.4.S ct v cc dng dao chut ............................................................................71 9.4.1.Dao chut ct n............................................................................................71 9.4.2.Dao chut ct nhm........................................................................................72 9.5.Phng php ch yu to b mt bng dao chut.................................................74 9.6.Phn lm vic ca dao chut ..................................................................................75 9.6.1.Rng ct th.....................................................................................................75 9.6.2.Rng ct tinh, rng sa ng v chiu di ca dao chut .............................82 9.6.3.Chiu di ton b dao chut ...........................................................................84 9.6.4.Dung sai kch thc dao chut .......................................................................85 VN 10 ............................................................................................................................87 THIT K DNG C GIA CNG REN............................................................................87 10.1.Dao tin ren v cc thng s hnh hc...............................................................87 10.1.1.Dao tin ren n ..............................................................................................87 10.1.2.Dao tin ren hnh thang...................................................................................89 10.2.Taro ren................................................................................................................91 10.2.1.Cng dng v phn loi ..................................................................................91 10.2.2.Cc thnh phn kt cu ca taro.....................................................................91 10.3.BN REN............................................................................................................96 10.3.1.Cng dng v phn loi ..................................................................................96 10.3.2.Kt cu bn ren trn........................................................................................97 10.3.3.Cc gc phn ct ........................................................................................ 100 10.3.4.Dung sai kch thc ren................................................................................ 100 10.4.GIA CNG REN BNG PHNG PHP BIN DNG DO.................. 101 10.4.1.Qu trnh cn ren........................................................................................... 101 10.4.2.Dng c cn ren............................................................................................. 101 VN 11 .......................................................................................................................... 104 THIT K DNG C GIA CNG RNG BNG PHNG PHP NH HNH .... 104 11.1.Dao phay vu m un ....................................................................................... 104 11.2.Dao phay a m un ........................................................................................ 104 11.3.Tnh ton profil dao phay a m un.............................................................. 104 5 11.4.B dao phay a mun .................................................................................... 105 VN 12 .......................................................................................................................... 107 THIT K DNG C GIA CNG RNG BNG PHNG PHP BAO HNH...... 107 12.1.Khi nim c bn .............................................................................................. 107 12.2.Thit k cc dng c ct rng theo nguyn l bao hnh c tm tch gia cng bnh rng tr thn khai..................................................................................................... 107 12.2.1.Cc loi mt xon vt dng trong thit k dng c ct................................ 107 12.3.Thit k dao phay ln rng ............................................................................... 110 12.3.1.Nguyn l lm vic ....................................................................................... 110 12.3.2.Kt cu dao phay ln rng............................................................................. 110 12.3.3.Thit k prfin dao phay ln rng ................................................................ 112 12.4.Thit k dao xc rng thn khai ....................................................................... 113 12.4.1.Nguyn l lm vic v kt cu ..................................................................... 113 12.4.2.Cc gc ct ca rng ..................................................................................... 114 12.4.3.Khong cch khi thy a ca dao xc ......................................................... 116 VN 13 .......................................................................................................................... 117 NG DNG TIN HC TRONG THIT K V CH TO DNG C CT............. 117 13.1.M u............................................................................................................... 117 13.2.M hnh khung dy ........................................................................................... 117 13.2.1.Biu din cc ng cong phn tch ............................................................ 117 13.2.2.Biu din cc ng cong t hp................................................................. 119 13.3.M hnh b mt.................................................................................................. 122 13.4.M hnh khi rn............................................................................................... 124 13.4.1.M hnh CSG (constructive solid geometry)............................................... 124 13.4.2.M hnh biu din bin B-rep....................................................................... 126 13.4.3.Biu din qut (sweep representation) ......................................................... 127 Ti liu tham kho:............................................................................................................... 127 6 VN 1 C S L THUYT THIT K DNG C CT 1.1 C s l thuyt to hnh b mt: Mt b mt s c hnh thnh do mt ng sinh no chuyn ng theo mt qui lut nht nh. Cc chuyn ng l ng hc hnh thnh b mt. Dng c ct c th ct gt cc chi tit khc nhau th li ct ca dng c ct phi n su vo vt liu ca phi v ct, tch cc phn kim loi d ra khi chi tit di dng phoi ct. Do , th hnh dng ca chi tit l yu t quyt nh n hnh dng ca li ct ca dng c ct, cng nh quyt nh n cc chuyn ng tng i ca dng c v chi tit. Khi li ct ca dng c hnh thnh c b mt gia cng, c ngha l li ct phi nm trn mt tip tuyn v tip xc vi b mt chi tit trong sut qu trnh gia cng. Mt tip xc c gi l mt khi thy ca dng c. Qu o chuyn ng tng i ti mi im ca li ct so vi phi l kt qu chuyn ng tng hp do dng c v chi tit thc hin trn my. Vy, cng c th ni rng, tp hp cc chuyn ng ca bmt dng c v chi tit trong qu trnh ct chnh l s ng hc to hnh ca qu trnh ct. S ng hc to hnh khi ct ni chung khc vi s ng hc ca my. Vd:khitinmttrngoi,snghctohnhchgmchuynngquay trncachitit,chuynngtnhtindctrccadao. Trongkhi,snghc ca my th cn phi m bo chuyn ng chy dao ngang l chuyn ng a dng c vo v tr cn thit t c ng knh cho ca chi tit. Vicnghincusnghctohnhcnghartquantrngtrongvicgia cngkimloiv ccthngshnhhcphnctcadngc,chct,nngsutlao ng,smimn,tuibncadngcngviphngphpgiacngchnph thuc rt nhiu vo n. n gin cc chuyn ng ca my ct, ngi ta thng dng s ng hc to hnhdatrnthphaichuynngcbncaphivdngcl:chuynngtnh tin v chuyn ng quay trn. phc tp ca s ng hc tohnh ph thuc vo s lng cc chuyn ng thnh phn v c trng t hp ca n. Ta c cc nhm nh sau: Nhm c 1 chuyn ng: - mt chuyn ng thng - mt chuyn ng quay Nhm c 2 chuyn ng: - hai chuyn ng thng - hai chuyn ng quay 7 - mt chuyn ng thng v mt chuyn ng quay Nhm c 3 chuyn ng: - hai chuyn ng thng v mt chuyn ng quay - hai chuyn ng quay v mt chuyn ng thng - ba chuyn ng quay Vmtnguynlcththpnhiuyutchuynnghn,nhngtrongthc tin ng dng th iu ny b gii hn bi phc tp ca t hp v kh khn trong vic ch to cc thit b tng ng. 1.2 ng hc to hnh b mt chi tit Khi to hnh b mt chi tit th cn phi nghin cu cc phng n khc nhau ca s phi hp cc chuyn ng ca chi tit i vi dng c. Bng 1.1 gii thiu cc s to hnh b mt vi chuyn ng chnh l tnh tin v quay trn. Cp b mt Loi s Kiu s Cc chuyn ng thnh phn ca chi tit gia cng v dng c khi to hnh Chuyn ng tng hp tc thi Chuyn ng tng i vi s tr gip ca cp b mt S v tr tng h ca cp b mtDng c Vt gia cng 1Tnh tinTnh tin ng thng ng thng 2QuayQuay-- I 3Xon vtXon vt -- 1Quayvtnhtinvi vntcvunggcvi trc quay QuaySdchchuyn catrtheomt phng Mt phng Tr 2Haichuynngquay quanh trc song song QuaySdchchuyn ca tr theo tr TrTr II 32chuynngquay quanh trc ct nhau QuaySdchchuyn camtcntheo mt phng Mt phng Mt cn 8 42chuynngquay quanh trc ct nhau QuaySdchchuyn camtcntheo mt cn CnCn 5B i quayTnh tin S trt ca vng theo vng Vng Vng Mt phng tr Tr1Quayvtnhtinvn tcchngtothnh gc vi trc quay Xon vt Sdchchuyn vistrtca trtheomt phng Mt phng CnMt phng 22chuynngquay quanhtrcchonhau (gchp thnhvi trc quayv trccang vt.Trccavttc thivtrcquayth2 l 2 ng cho nhau Xon vt Sdchchuyn vstrtca mtcntheomt phng Mt phng Cn III 32chuynngquay quanh trc cho nhau Xon vt Sdchchuyn vstrtca mthypecbolit vimt hypecboloit Hypecboloit hypecboloit 1.2.1Nhm bc 0 Tp hp cc s ng hc to hnh khi b mt khi thy ca dng c trng vi b mt nguyn gc chi tit. V d: khi ct ren bng tar, khi chut, khi t l, lc ny chuyn ng tng h gi lchuynngttrtvxcnhbmtkhithythkhngcnquantmn chuyn ng ny. 1.2.2Nhm bc 1 Nhmstohnhmchuynngtnghcadngcivichititl chuyn ng tnh tin, xoay hoc xon vt. S c c trng ch l khi cc cp b mt ca phn t quay v ng yn trng nhau v to thnh ng thng. 9 Kiuthnht:chachuynngthngu.Theosny,tohnhchocc loi dng c chut ngoi cc b mt trn xoay, tin bng dao tin nh hnh tip tuyn c phng chy dao thng. Kiu th hai: cha cc chuyn ng quay, to hnh cc loi dng c hoc cc loi bmt,vddaophaynhhnhphayccbmttr,bmtxonvthocbmt trn xoay. Kiu th ba: khi phay bnh rng c rng thng bng dao phay ln rng. Thc ra kiu th nht l trng hp c bit ca kiu th ba khi trc quay v cng. 1.2.3Nhm bc 2 Nhmsnghckhimchuynngtnghcadngcvchititl chuyn ng quay tc thi hay tnh tin thng. Cc cp ng hc ln theo nhau khng c s trt. Chuyn ng tnh tin tc thi l chuyn ng tng hp ca hai chuyn ng quay quanh hai trc song song c vn tc gc v hng ging nhau. Cc b mt lin kt c to thnh bi cc b mt sau: -Tr - phng; -Tr - tr; -Cn phng; -Cn cn. V d: gia cng bnh rng bng dao xc rng hoc dao rng lc cc s ng hc ny, cc cp b mt gia dng c v chi tit c th i ch cho nhau. chng hn nh s tr - mt phng, dng c c th l dao xc rng hnh a, chi tit l thanh rng v ngc li. nhm hai cha kiu s khi m chuyn ng tc thi l kt qu ca hai chuyn ng quay quanh cc trc song song nhau hay ngoi nhau. Chuyn ng tnh tin c th coi l trng hp c bit ca chuyn ng quay v c th xem mt phng l hnh tr c bn knh v cng ln. 1.2.4Nhm 3 Nhmchaccsmccchuynngtnghlchuynngxonvttc thi. Trong nhm ny th cc b mt t ln theo nhau c s trt. Cc b mt gm:-Tr - phng; -Cn phng; -Hai mt hypecboloit. 10 Chuynngxonvttnghptcthiltnghpcahaichuynngquay quanhcctrcngoinhauvcthhnhdungnnhlbmthypecboloittheo hypecboloit c gn s trt. y l trng hp tng qut nht, chng hn nh phay bnh rng bng dao phay ln rng. 1.3 Mt khi thy K ca dng c ct Dng c ct c th xem nh mt vt th b gii hn bi mt b mt, b mt gi l mt khi thy K ca dng c ct, trn phn b cc li ct c prfin thch hp trc tip hnh thnh b mt chi tit. Vd,vtthtrnxoaygiihnbimttrnxoayK,trongqutrnhgiacngn lun tip tuyn vi cc b mt gia cng ca chi tit. Sau khi to mt trc rnh thot phoi v mt sau th vt th tr thnh dng c ct, chnh l dao phay. Nh vy b mt khi thy K ca dng c ct lun phi tip xc vi b mt ca chi tit trong qu trnh gia cng. 1.4.1PhngphpxcnhmtkhithyKcadngcbngmtbaocah mt chi tit C. Trong qu trnh gia cng th b mt chi tit C thc hin cc chuyn ng tng i i vi dng c v hnh thnh tp hp cc v tr tip xc nhau c gi l h mt C. Mt khi thy K ca dng c l b mt tip xc vi h mt C trong qu trnh chuyn ng to hnh. Do mt khi thy K ca dng c chnh l mt bao ca h mt chi tit C. Hai mtCvKtipxcvinhautheomtngEgilngctnh. Nicchkhc, ng c tnh E l ng tip xc ca cp ng hc b mt C v K. V d: Hy tm b mt khi thy K ca dng c gia cng mt trn C. Ta c S gia cng l: -Chuyn ng quay ca chi tit quanh trc O1 -Chuyn ng tnh tin dc trc O1 Dng c quay quanh trc O2 vung gc vi trc O1. Mt khi thy K l mt bao ca hmtchititCkhinchuynngtngisovidngc.MtKslmtcong lm, c hnh thnh bng cch quay ng c tnh E quanh trc O2. Nu dng b mt khi thy nh th lm b mt dng c th vi s ct nh hnh 1.1 s gia cng c b mt tr trn xoay ca chi tit C. 11 Hnh 1.1 ng c tnh E v mt khi thy ca dng c 1.4.2Phng php gii tch xc nh mt khi thy K PhngphpitphngtrnhngcongphngC,tinnxcnhphng trnh ca h ng cong phng C, v t phng trnh ca h ng cong phng C i xc nh phng trnh ng bao ca h theo hnh hc gii tch. Nu h h ng cong phng C cho di dng tng qut F(x,y,z,t)=0, vi t l tham s chuyn ng ca h th phng trnh mt bao s l nghim ca phng trnh: ==0) , , , (0 ) , , , (tt z y x Ft z y x F Nu h ng cong cho di dng phng trnh thng s: ===) , , () , , () , , (321t v u f zt v u f yt v u f x Trong :u,v- Thng s b mt; t- Tham s ca h, th phng trnh mt bao s l nghim ca h: ====0. .. .. .) , , () , , () , , (321tztytxvzvyvxuzuyuxt v u f zt v u f yt v u f x 1.4.3Phng php ng hc xc nh mt khi thy K 12 Khi cho hai b mt bt k chuyn ng th ti cc im tip xc, vect tc chuyn ng tng i Vv vect php tuyn b mt Nphi vung gc vi nhau, v vect Vhng theo phng tip tuyn chung ca hai b mt. Nh vy, nu mt chi tit C chuyn ng trong khng gian th ng c tnh ca mt bao K s l ng tp hp ca tt c cc ng tip xc m ti vect vn tc Vthng gc vi vect php tuyn N . iu kin tip xc c biu th bng phng trnh: N .V= 0 Hnh 1.2 iu kin tip xc ng hc ca 2 b mt T iu kin tip xc ny, cho php tm c im tip xc ca cp b mt tip xc ti bt k thi im no. Tp hp ttc cc im tip xc , xt trong h ta gn vi chi tit, l b mt chi tit C. Tp hp tt c cc im tip xc , xt trong h ta gn vi dng c, l b mt khi thy ca dng c K. Khi xc nh mt khi thy K ca b mt chuyn ng C, chuyn ng ca C c th phntchthnhnhiuthnhphn,vvicphntchshplhnnucmttrong nhng thnh phn gy ra s trt ca bn thn C v nh vy s lm cho bi ton tr nn n gin. V d: xc nh ng c tnh ca mt mt phng c chuyn ng xon vt. Gc gia trc ca chuyn ng vtvmt phng P l . Chuyn ng xon vt ca mt phng P c phn tch thnh hai chuyn ng: chuyn ng tnh tin vi vn tc Vv chuyn ng quay vi vn tc gc . ChuynngVcphntchthnhhaithnhphn: V = 1V + 2V ,trong1Vhng thng gc vi V , cn2Vnm trong mt phng P. S chuyn ng theo vect2Vdn n s trt ca mt phng P, do khi xc nh ng c tnh khng cn ch n n. ln ca vect1Vc tnh theo cng thc: 1V =V .tg 13 Hnh 1.3 Xc nh ng c tnh khi mt phng c chuyn ng xon vt Chuyn ng theo vect1Vc th hnh dung l s quay ca h thng vi vect tc gc . Khong cch gia chng l:tg htg V Vr ..1= = =h: thng s ca chuyn ng xon vt. Nhvychuynngxonvtdnnmtchuynngquay.ngctnhE trong trng hp ny s thng gc vi hnh chiu ca trc quay trn mt phng P, ngha lnhngngthngcchhnhchiucatrcchuynngxonvtmtkhongrv lm vi n mt gc . Kt qu l chuyn ng xon vt ca nhng ng c tnh E to ra mt mt bao l b mt xon vt thn khai c bn knh hnh tr c s l r. 1.4 Nhng iu kin to hnh ng b mt chi tit 1.4.1iu kin cn iu kin cn to c b mt mong mun l tn ti b mt khi thy K ca dng c ct ng vi b mt chi tit cho. C ngha l, trong qu trnh gia cng, cc im trn b mt chi tit c t nht mt ln tip xc vi cc im ca b mt khi thy ca dng c, vy, cn tn ti cc im tip xc chung ca hai b mt. Ti cc im tip xc ny, php tuyn chung phi thng gc vi vect chuyn ng tng i, ngha l: N .V = 0. i vi b mt chi tit cho, vect php tuyn ti cc im ca b mt l hon ton xc nh, c ngha l khng th thay i v tr ca php tuyn Nnu khng thay i hnh dng ca chi tit. Do , ti mt s gia cng chn, nu ta bit cc chuyn ng ca chi tit v dng c th vic thay i hng v tc chuyn ng tng i gia cp b mt s m bo N .V =0. V d, kho st s gia cng mt phng P, nu cho mt C quay quanh trc c nh nmtrnmtphngP thkhitcquay camtimbtk camtctCquanh 14 trcsvunggcvimtphngP,tc V ssongsongviphptuyn N camt phngchitit.iukin N .V =0thamndokhngtntimtkhithyKca dngcvvicgiacngmtphngPtrongiukinnhtrnlkhngththchin c. Nu chntrcquaythnggcvimt phngPthngnhin tittcccim ca mt phng P vect php tuyn lun vung gc vi vect tc ct. iu c ngha l mt khi thy K tn ti v trng vi mt P. 1.4.2iu kin iu kin 1: s tip xc ca b mt khi thy K ca dng c v b mt chi tit gia cng khng xy ra hin tng ct lm. S tip xc trn c th l tip xc ngoi hoc tip xc trong. Khi tip xc ngoi, mt khithyKcadngc2nmngoithnchitit1,khikhngcsctlmca dng c vo thn chi tit. Khi tip xc trong, mt khi thy ca dng c 2 c bn knh cong ln hn bn knh cong ca chi tit 1, do c hin tng ct lm. Nh vy vic to ng hnh dng ca chi tit l khng th thc hin c.

Hnh 1.4 Cc dng tip xc Hy kho st qu trnh mi mt cn trong bng mi trn. S tip xc ca b mt to hnh K vi mt cn ca l C xy ra dc theo ng sinh ng c tnh. TititdinII-IIthnggcvi ngc tnhxyrastip xcgiahaibmt. Trongcctit din,bn knhcongca mitrnlunginguynkhngitrong lc bn knh cong camtcn chi tit gimdn khi tinv pha nh cn. Ti imm n nh cn, bn knh cong ca mi ln hn bn knh cong ca mt cn v do c sctlmnnvic gia cngvngbng mitrnnhtrn lkhngththchin c. Ti im gii hn M, bn knh cong ca mt cn bng bn knh cong ca mi. Nh vy, gia cng b mt chi tit t yu cu th b mt khi thy ca dng c K khng c ct lm vo b mt chi tit. iu kin 2: trn b mt ca chi tit khng c nhng mt chuyn tip. 15 Chi tit c th gm nhiu mt ni tip, do mt khi thy K ca dng c cng gm nhiumttngnghnhthnhccbmtcachitit.Ccphnlncncamt khi thy K ca dng c c th ct nhau, ni tip nhau hoc tch ri nhau. Khi cc phn ca mt khi thy ct nhau th chng khng th ct ht phn kim loi dnh cho tng phn c, do b mt chi tit c ct bng phn ca mt khi thy ct nhau s khng c thc hin v s c mt chuyn tip ni cc phn b mt ln cn ca chi tit. iucchngminhbngvdsau:dngdaophayngngiacngmttr quaygmmtphnhnhtrC1vmtuC2.khidaophayquay trnquanhtrcca n, cc li ct to ra mt khi thy K1 cn chi tit quay chm quanh trc ca n. Trc chi tit v trc dng c vung gc vi nhau v cch nhau mt khong k. Khi mt khi thy tip xc vi mt tr C1 l K1 vi ng c tnh E1 quay quanh trc dng c,cnphnmtkhithycamtphngC2lK2cngctnhE2cngquay quanh trc ca dng c. Cc mt K1 v K2 ct nhau theo vng trn A do khng th c phn ni tip gia hai phn c. Kt qu l trn thn chi tit s hnh thnh mt mt chuyn tip. ng c tnh E1 quay xung quanh trc ca chi tit ch hnh thnh mt r C1 trn on Me ca prfin, cn ng c tnh E2 ch to mt phng C2 n im C ca prfin. Gia hai im E v C c mt ng cong chuyn tip. chnhxccabmtchititgiacngphthucvochnhxccabmt khi thy, ngha l chnh xc ch to cc kch thc tng ng ca dng c. t chnh xc chi tit sau khi gia cng nm trong phm vi dung sai cho php ca n th dng c phi c dung sai ch to b hn. Thngthng,dungsaicckchthccadngctrctipnhhngnhnh dngvkchthcbmtgiacngnmtronggiihn1/3-1/4dungsaikchthc tng ng ca chi tit. 16 VN 2 DNG C CT N V DNG C CT TIU CHUN 2.1 Cng dng v phn loi Dng c ct hay cn gi l dao l b phn ca h thng cng ngh c nhim v trc tip tch phoi hnh thnh b mt gia cng. Dao c nh hng rt ln n qu trnh ct gt. N khng nhng tc ng trc tip ti cht lng chi tit m cn chi phi khng nh ti vn nng sut v gi thnh ch to sn phm. Dng c ct n c dng ph bin trong qu trnh gia cng ct gt trn my tin vn nng, my tin t ng, my bo, my xc v c th dng trn cc my chuyn dng khc. Do , dng c ct n c nhiu hnh dng v kt cu khc nhau ty theo cng dng ca chng, v c tiu chun ha, thng c chia thnh cc loi sau: -Theo loi my s dng: dao tin, dao bo, dao xc -Theo dng gia cng: dao tin ngoi, dao xn mt u, dao ct t, dao tin l, dao tin ren -Theo cch g dao: dao hng knh, dao tip tuyn -Theo tnh cht gia cng: dao ct th, dao ct tinh -Theo kt cu thn dao: hnh ch nht, hnh vung, hnh trn -Theo kt cu u dao: dao u thng, u cong -Theo hng chy dao: dao chy phi, dao chy tri -Theo loi vt liu dng c: dao thp gi, dao hp kim cng -Theo phng php ch to dao: dao u lin, dao hn mnh, dao kp mnh Dng c ct n c th coi nh mt vt th hnh hc bao gm hai phn:-Phnthndao:dngkpchtdaovngthikpchtdaovobndao. Chnhvvyihiphicngvng.Hnhdngvkchthcphnthn dao c ch to theo tiu chun.-Phn u dao: thc hin ct gt. Trong phn u dao c cc mt trc, mt sau chnh, mt sau ph, li ct chnh, li ct ph, mi dao. Hnh 2.1 Dao ct n 17 2.2 Thng s hnh hc phn ct ca dng c -Li ct chnh l giao tuyn ca mt trc v mt sau chnh. -Li ct ph l giao tuyn ca mt trc v mt sau ph. -Giao im ca li ct chnh v li ct ph l mi dao. 2.2.1 Cc chuyn ng khi ct Trong qu trnh ct dao v chi tit cn phi thc hin cc chuyn ng sau: -ChuynngctchnhMcvitcctchnhlVc,lchuynngcbn to ra phoi v chim hu ht nng lng ct. -Chuyn ng chy dao dc Mf vi tc Vf l chuyn ng ct ht ton b b mt chi tit. -Chuyn ng chy dao ngang vi tc Vn l chuyn ng tnh tin theo phng chiu su ct. -ChuynngtnghpMe,chuynngctvitc eVrlchuynngtng hpcachuynngctchnh cVrvchuynngchydaodc fVr,hocl chuynngtnghpcachuynngctchnh cVrvichuynngchydao ngang nVr. y chnh l chuyn ng to hnh mt tr ngoi ca chi tit. Thngshnhhcphnctcadngctrngthitnhcxcnhnhkhi khng c chuyn ng chy dao Mf (fVr=0) trong trng hp Ve c xc nh nh l chuyn ng ct chnh cVr (eVr =cVr). 2.2.2 Cc mt phng ta v cc tit din MtphngyPr:timtimtrnlictMlmtphngiquaimv vung gc vi vect tc ct eVr. Nu trng thi tnh fVr=0, th mt y vung gc vi cVr. Mt phng ct Ps: ti mt im trn li ct chnh M l mt phng i qua im v tip tuyn vi mt ang gia cng ca chi tit, tc l mt phng cha vect tc ct cVr v tip tuyn vi li ct ti im M. Do mt ct v mt y lun vung gc vi nhau. Tit din chnh N-N: l mt phng ct i qua mt im ca li ct chnh v vung gc vi hnh chiu li ct chnh trn mt y. TitdinphN1-N1:lmtphngctiquamtim trnlictphvvung gc vi hnh chiu ca li ct ph trn mt y. Tit din dc Y-Y: l mt phngct quamt im trn li ct chnh v vung gc vi phng chy dao dc. 18 TitdinngangX-X:lmtphngctiqua mtimtrnlictchnhvsong song vi phng chy dao dc. Hnh 2.1 mt phng ta v tit din 2.2.3 Cc gc phn ct ca dng c Gc trc : ti mt im trn li ct l gc hp bi mt trc v mt y o trong tit din kho st n, y, x Gc trc c th dng, m hoc bng khng. Gc sau : ti mt im trn li ct l gc hp bi mt ct v mt sau o trong tit din kho st (n, y, x).. Gc sau lun lun dng. Gc sc : ti mt im trn li ct l gc hp bimt trc v mt sau o trong tit din kho st (n, y, x). Gcct:timtimtrnlictlgchpbimttrcvmtctotrong tit din kho st (n, y, x). Gcnghingchnh:lgcgiahnhchiucalictchnhtrnmtyv phng chy dao. Gc nghing ph 1: l gc gia hnh chiu ca li ct ph trn mt y v phng chy dao. Gc mi dao : l gc gia hnh chiu ca li ct chnh v ph trn mt y. + 1 + = 1800 Gcnngcalict:lgcgialictchnhvhnhchiucantrnmt y. c th dng, m, hoc bng khng. 19 Hnh 2.2 cc tit din v cc gc 2.3 Xc nh kch thc thn dao tin Thng thng th phn thn dao v phn g t u dao c ch to cng loi vt liu. Theo kinh nghim th hu ht cc loi dao cn ch to phn ct v phn cn ring th vt liu phn cn c ch to bng thp 45 hoc thp hp kim 40X. Chnh v vy khi ni ti vt liu ch to dao c ngha l ni n vt liu ch to phn lm vic ca dao. Hnh 2.3 xc nh kch thc thn dao tin Kchthcthndaotincxcnhtitdinngangcathndaotheothnh phn lc ct chnh Pz v khong cch l t im t lc n mt ta. Lc ct chnh Pz c xc nh theo cng thc: Pz = p.f 20 Trong : p- lc ct n v, N/mm2 f- din tch ct, mm2 mboscbnthndao,mmenundolcPZgyraphinhhnmmen un cho php ca tit din thn dao: Mu [Mu] Pz.l W.[u] W: mmen chng un ca tit din thn dao, oThn dao hnh ch nht BxH: W=B.H2/6=> B.H2 = (6.f.p.l)/ [u] oThn dao hnh vung BxB: W=B3/6=> B3 = (6.f.p.l)/ [u] oThn dao hnh trn ng knh d: W=d3/10=> d3 = (10.f.p.l)/ [u] [u]: ng sut cho php ca vt liu thn dao. Trongthct,ngoilcPzcncccthnhphnlcPx,Pytcdnglnphnct ca dng c, tr s lc Px, Py c th c ly gn ng nh sau: Py = (0,4-0,5)Pz; Px = (0,3-0,4)Pz (vi =450 v =0) Bng 2.1 Chn tit din thn dao theo din tch lp ct Kch thc dao tinMnh dao hp kim cngMnh dao thp gi Ch nhtVungDin tch ct ln nht, mm Chiu su ct ln nht, mm Din tch ct ln nht, mm Chiu su ct ln nht, mm 10x1612--1,53 12x2016--2,54 16x25204645 20x302581066 25x4030181397 30x45402518168 40x605040252512 50x80656036-- S liu c p dng cho vt liu chi tit c cng trung bnh vi tb=750N/mm2, bng dao tin ngoi c gc =450 21 VN 3 THIT K DAO TIN NH HNH GIA CNG B MT TRN XOAY TRN MY TIN 3.1.Cng dng, phn loi v phm vi s dng Dao tin nh hnh dng gia cng cc b mt trn xoay nh hnh. Gia cng bng dao tin nh hnh c nhng u nhc im so vi cc dao tin n nh sau: -m bo ng nht prfin chi tit trong qu trnh gia cng v khng ph thuc vo tay ngh cng nhn m ch ph thuc vo chnh xc dao tin nh hnh. -Nng sut cao v gim c thi gian my, thi gian ph. -Tui th ca dao ln v mi c nhiu ln. -S lng ph phm t. -Mi sc li dao n gin v mi theo mt trc l mt phng. -Tuynhin,victhitkvch to daotinnhhnhphctphnnhiusovi daotinnthngthng,chonndaotinnhhnhcdngchyutrong sn xut hng lot ln, hng khi. Hnh 3.1 Cc loi dao tin Phn loi dao tin nh hnh:a-Theo hnh dng dao: -Dao a (hnh 3.1a) -Dao hnh lng tr (hnh3.1b) b-Theo cch g dao: -Dao hng knh (hnh3.1a,b); -Dao tip tuyn (hnh3.1c) 22 c-Theo v tr ca ng tm chi tit, tm l dao v chun kp: -Dao g thng (hnh 3.1d) -Dao g nghing (hnh 3.1) d-Theo v tr mt trc: -Dao mt trc khng nng =0 (hnh 3.1a,b) -Dao mt trc g nng >0 (hnh 3.1e) e-Theo dng b mt sau nh hnh: -Mt trn xoay (hnh 3.1a) -Mt sau xon (hnh 3.1g) Dao tin nh hnh lng tr: c kp cht bng mang c v vt gi dng tin cc bmtngoinhhnhtrnxoay.Ckhnngcngvnghndaotinhnhtrn,gc sau c th ln, gia cng chi tit t chnh xc cao hn so vi dao hnh trn. Daotinnhhnhtrn:cdnggiacngccbmtnhhnhtrnxoay ngoivtrong,clpvotrcgvchngxoaybngcckhamtuhocbng cht. D ch to hn dao tin hnh lng tr. Dao tin nh hnh hng knh: c g sao cho nh dao nm ngang tm chi tit m bo chy hng knh. Dao c phn li ct tham gia ct ln nn lc ct ln, v vy cn gim ch ct khi gia cng. Dao tin nh hnh tip tuyn: c g sao cho mt sau tip xc vi ng trn nh nhtcachitit,hngchydaotiptuynvib mtcachitit. Thngc dng gia cng cc chi tit c ng knh nh v di (chu un km) vi chiu su ct nh. Daotinnhhnhgnghing:cdngkhichititgiacngcphnprfinc bit v g nng khi chi tit c phn prfin yu cu chnh xc cao, c ch tnh ton c bit khi thit k. Hnh 3.2 Kp cht dao tin nh hnh 3.2.Mt trc, mt sau v kt cu dao tin cho qu trnh mi sc dao tin c n gin th mt trc ca dao tin nh hnh c chn l mt phng. Mt sau ca dao tin nh hnh hnh trn l mt trn xoay nh hnh, c prfin trong tit din hng knh. 23 Hnh 3.3 Kt cu dao tin nh hnh hnh trn Mtsaucadaotinnhhnhlngtrlmtkmngchuncxcnh da vo prfin chi tit, gc trc v gc sau ca dao. Kch thc ca dao tin nh hnh c xc nh da vo chiu su ln nht tmax v chiu di L ca prfin chi tit. Hnh 3.4 Kt cu dao tin nh hnh hnh lng tr i vi dao tin nh hnh hnh trn g thng, trc phi v trc dao s song song vi nhau, ng knh ca dao khi tin ngoi De=10-120mm, khi tin trong De0,75dct, dct l ng knh l chi tit gia cng. Daotinc ngknhnhhn30mm cchtocnlin, ngknhln hn 30mm c ch to cn ri. ng knh ngoi ca dao tin cho php nh nht c l g lp trc g: Demin1,5d0 + 2t + 6mm. Trong : d0 ng knh l g. t chiu su prfin dao. ng knh ngoi De v l d0 nn dng theo bng. De3040-5060-7590 d013162227 24 lp dao tin nh hnh hnh trn c d dng v nng cao cng vng kp cht thtrnmt ucadaocchtocccrngkhamtu,srngkhaZthng ly z=34 rng v theo phng hng knh. Hnh 3.5 Lp t dao tin nh hnh Chiu di ca dao hnh lng tr c ly khong 75-100mm; chiu rng B c ly ph thuc vo chiu di prfin chi tit. 3.3.Thit k dao tin nh hnh hng knh Cnhiuphngphp khcnhauxcnhprfinlictnh:giitch,th, th gii tch y ta p dng s gia cng tnh prfin li ct, s gia cng l s biu din v tr cui cng ca chi tit v dao ti im c s. im c s l im m bin dng cachititvbindngca licttrngnhauvnmtrongmtphngngangiqua trc ca chi tit. Thng thng, im c s c chn ti v tr c bin dng ca chi tit l nh nht r1=rmin. 3.3.1.Gc trc, gc sau ti cc im ct nhau trn li ct dao tin nh hnh S xc nh gc trc v gc sau ti cc im c s nh hnh v. Hnh 3.6 Dao nh hnh hnh trn 25 Hnh 3.7 Dao nh hnh hnh lng tr Gc sau : i vi dao tin nh hnh hnh trn, mun gc sau >0 th tm ca dao phi cao hn tm ca chi tit mt khong l h so vi mt phng nm ngang, h c gi l chiu cao g dao v c xc nh: h = R.sin. Trong : R- bn knh dao hnh trn ti im c s, nu im c s l nh nht th R l bn knh ln nht ca dao. ividaotinnhhnhhnhlngtr,gcsauctothnhdogtdao. x x = , + = . ividaotinhnhtrn, x x x + = , cos .sin .xxxRtg= , cos . cos . r rx x x = ((

= cos ) cos . cos . (sin ) cos . cos . (r r Rr rarctgx xx xx Gc trc : Quan h gia gc trc ti im c s v gc trc x ti im bt k nh sau: rx.sin x = r.sin x = |||

\| sin arcsinxrr Vy: -Gctrcvgcsauticcvtrkhcnhautrnlictdaotinnhhnhl khng bng nhau. -Ti cc im cng xa tm chi tit th gc sau x cng ln v gc trc x cng nh. - m bo gc sau khng qu nh th im c s khi thit k dao tin nh hnh nn trng vi im ca chi tit c bn knh nh nht. -Gcsautiimcsividaohnhtrn =100-120;ividao hnhlng tr c th chn ln hn =120-150. -Gc trc ph thuc ch yu vo vt liu gia cng, i vi gia cng nhm =250-300; i vi gia cng ng thau, ng =00-50; i vi gia cng gang =00-100. 26 3.3.2.Xc nh profin li ct dao tin nh hnh hng knh g thng a)Phng php th ividaotinnhhnhhnhlngtr,profinlictltitdin phptuynvi mt sau. i vi dao tin nh hnh hnh trn th profin li ct l giao tuyn ca mt sau vi mt phng i qua tm dao. Hnh 3.8 Phng php th Mtphngphpxcnhprofinlictdaotinnhhnhhnhlngtr:cho chi tit hnh nn ct vi bn knh ng trn y ln r2 v bn knh ng trn y nh r1. Mt phng T c xem l mt trc ca dao, mt trc ct y ln ti im 2* v ct y nh ti im 1. E v F c xem l mt lng tr v mt y, to vi bn knh c s gcsau.KbtkmtQvungcvingsinhlngtrthtitdinnychnhl profin li ct dao tin. b)Phng php tnh ton * i vi dao tin nh hnh hnh lng tr: Gi s chi tit c hnh dng v kch thc nh hnh 3.9. Chn im 1 lm im cs,kmtTlmttrccadaovhpviphngngangmtgc.MtTct vng trn bn knh r2, r3 ti cc im 2, 3 tng ng vi khong cch t im 1 n im 2, 3 l 2, 3. 27 Ti im 1 kmt sau hp vi phng ng mtgc . Ta i tmchiu cao profin dao bng cch t cc im 2,3 k vung gc vi mt sau ca dao, t ta c chiu cao profin dao hd2 v hd3. Hnh 3.9 S tnh ton bin dng dao lng tr D dng xc nh c: ) sin arcsin(cos . cos .) cos( .2121 2 2 22 2 rrr rhd= =+ = Tng ng vi im x bt k ti bn knh rx: ) sin arcsin(cos . cos .) cos( .11 xxx x xx dxrrr rh= =+ = Vy, ta s c c tit din vung gc vi mt sau nh sau: 28 * i vi dao tin nh hnh hnh trn tin ngoi: Gi thit chi tit nh hnh c cho nh hnh 3.10 l v tr gia cng xong ca chi tit, im 1 l im c s, gc trc v gc sau xc nh. Hnh 3.10 S tnh ton dao tin nh hnh hnh trn Bn knh Ri ti cc im ca dao c xc nh nh sau: 29 cos cos) cos( .sin) sin( .sini i i iiii iir rR EEHtgR HR =+ ==+= = Trong :H- Chiu cao mt trc dao; i- Chiu cao profin theo mt trc; r1- Bn knh chi tit ca im c s 1; ri- Bn knh chi tit ca im kho st i. SaukhixcnhcRi,tcchiucaoprofincalicttrongtitdinhng knh c xc nh. Chiu rng li cng c xc nh theo phng trc. * i vi dao tin nh hnh hnh trn tin trong: Githitchititcchonhhnh3.11lvtrgiacngxongcachitit. im 1 l im c s, gc trc v gc sau c chn ty theo vt liu gia cng. Bn knh dao c chn theo bn knh nh nht ca chi tit R=(0,75-0,8)rmin. Tng t, ta c th xc nh bn knh Ri ca dao nh sau: ) sin(sin + ==R HHRii i iiiB BBHtg ==

) cos(cos cos1 + = =R Br ri i i Hnh 3.11 S tnh profin dao tin nh hnh hnh trn tin trong 30 3.4.Sai s khi gia cng bng dao tin nh hnh Khi gia cng bng dao tin nh hnh, prfin chi tit b sai s do nhiu nguyn nhn gy ra. y ta xem xt 2 trng hp sai s khi gia cng chi tit bng dao tin nh hnh hnh lng tr; sai s khi gia cng chi tit bng dao tin nh hnh hnh trn. 3.4.1.Kho st sai s khi gia cng chi tit bng dao tin nh hnh hnh lng tr: B mt chi tit cn c l nn ct vi ng sinh l on 1-2. Li ct dao tin nh hnh s l on 1-2. Khi gia cng, chi tit quay quanh trc ca n v li ct 1-2 s to ra b mt chi tit. V dao c gc trc to bi mt trc T-T khng i qua trc chi tit, nn tit din ca on 1-2 s l on hypecbol v s ct chi tit thnh hnh hypecboloit vi sai s ca chiu cao hypecbol l on 1. Tr s 1 ph thuc vo kch thc chi tit v gc trc . Hnh 3.4 Sai s profin do tin bng dao hnh trn gy ra Sai s 1 c th khc phc bng cc bin php sau: -Lict1-2cthit kkhngphilonthngmlngconghypecbol theo giao tuyn camt T-T vimt cn chi tit. Vi bin php ny th vic ch to dao tr nn phc tp v kh thc hin. -Bin php th 2 l nng mt trc ln mt gc sao cho im 2 trng vi im 2. Tc mt trc ca dao i qua trc ca chi tit. 3.4.2.Kho st sai s khi gia cng chi tit bng dao tin nh hnh hnh trn: Khi thit k, prfin dao tin nh hnh c xc nh trong tit din hng knh, li ct 1-2 l on thng v chiu cao prfin trong tit din hng knh l hd2=R-R2. 31 MtsautrnxoaycchtolmtcncbnknhRvR2.Mttrclmt phngcchtrcdaomtkhongH=R.sin(+).Dolict1-2lgiaotuynca mt trc v mt sau khng phi l ng thng, m l ng hypecbol H2. Li ct gia cng bng ng H1 gy ra sai s 1. Li ct gia cng bng ng H2 s gy ra sai s 2. Do , khi tin bng dao hnh trn th chi tit c sai s gia cng = 1 + 2. Sai s 2 khng th trnh c, sai s 1 trnh c ging nh dao tin lng tr. Hnh 3.4 Sai s profin do tin bng dao hnh trn gy ra 3.5.Chiu rng B ca dao tin nh hnh: Chiu rng B ca dao tin nh hnh, ngoi phn gia cng ng chiu di prfin chi tit Lct cn tnh thm phn ph vt mp mt u v ct t. a=2-5mm,gcvtmp1=300-450,kchthcd=1-1,5mm.Nuchititkhngvt mp th 1=150-200 v c=1-3mm. Phntornhcttcxcnhtheocckchthcsau:b=3-8mm,t 60kG/mm2120-100 (-100)-(-150) Gang (ty theo cng)50-15050-(-50) 4.2.3.Gc nghing chnh : cxcnhgiatlchiudyvchiurnglpcttheochiusuvlng chy dao. Gim chiu dy ct gim v chiu rng ct tng ln, lm cho iu kin thot nhit vng ct tt hn, v vy gip tng tui bn dao v tng c lng chy dao. Tuy nhin, vic gim lm cho lc hng knh v lc chiu trc tng ln. -Nuchiusuctnhhn3mm,hthngcngnghcngvngthnnchn 200. -Khichiu suctln hn 6mm,nndnglict cgcchuyntipvi=40-600 v =200. -Khi dao ct hai mt thng gc th =900, tng bn nh rng nn vt nh gc 450 vi chiu di 0,5-1,5mm to ra li chuyn tip. 4.2.4.Gc nghing ph 1: Nu gim gc nghing ph th s lm tng bng b mt. Hnh 4.1 Gc nghing ph 4.2.5.Gc nng ca li ct chnh : 39 l gcgia vc t tc ct im angxt v phptuyn N vi li ct chnh cng chnh ti im trong mt phng ct. Cc dao phaymt u, dao phay a, dao phay 2 hoc3mt u c gc . i vi dao phay hnh tr rng xon th = . Gc lm tng bn ca dao. i vi dao phay gn mnh hp kim cng =12-150, i vi dao phay mt u bng thp gi 100. 4.2.6.Gc nghing ca rnh xon : Rngxongipchophoithotcddnghn,ngoirarngxoncsrng ng thi tham gia ct nhiu hn nn t b va p hn so vi rng thng nn lm cho b mtgiacngcnhnhn.Tuynhinrng xonstoralcctgttheo chiutrc, lc ny c chiu dc trc v c hng ty thuc vo hng xon ca dao. V trc chnh ca daoc cng vng theochiu hng trc lnhn so vi chiu ngc li, v vy nn chn chiu quay ca dao sao cho lc tc dng theo chiu hng v trc chnh. ivirngmtu,khilnthnhrngskmbn,lccnphivtmt gc m 30-50 trn chiu di 0,5-2mm. Khi ti nng th vt gc m, khi ti nh th vt gc dng. Hnggcnnthunchiuvihngct,nucsgiacngtrichiuthcn ch n hng thot phoi khng b kt phoi. Gccnhhnglnnbncadaophay,nudaophaycgcnghing cnglnthctnh hn,phoict thotddnghnnnchonngsutvtuibndao cao hn. Qua th nghim cho thy, nu gc nghing tng t 100-600 th tui bn dao tng 3-5 ln. Thc nghim ch ra rng, mc nh hng ca gc nghing i vi tui bn ca dao ln hn rt nhiu so vi cc yu t khc nh tc ct chng hn tui bn ca dao vn tng ln mc d tng tc ct nu c s tng gc nghing. Victnggcnghingcadaocngngnghalgctrcthctctng ln. Gc trc thc t c th thay i trong mt phng thot phoi m khng phi mt phngNNthnggcvilictchnhN.VictnggcnghingthvNbin thin rt ln theo bng sau: NNtg tgtg 2 2221. cossin sin+ ++ =Bng tr s gc trc thc t Gc nghing ca rng Khi N=5Khi N=10Khi N=15 50 50100150 40 1006030 1102016010 200110 1501019020 300 170502102024050 400 27029030320 500 3703039015410 600 490305003051030 Kt lun: -Khi tng gc nghing th gc trc thc t khng ngng tng ln; -Khi =40-600 th gc trc thc t thay i trong khong khng ln (2-50) v gc trc N thay i t (5-150). V th i vi nhng dao phay c ln c th chn N khng ln, iu ny gip cho dao bn hn, thot nhit tt hn.-C th dng cc tr s gc nghing sau cho cc kiu dao phay khc nhau: oDao phay hnh tr lp chui: 450-600; oDao phay tr dng chui: 300-600; oDao phay a 3 v 2 mt: 150-200; oDao phay hnh tr rng nh: 250-300; oDao phay mt u rng nh: 250-300; 41 VN 5 THIT K DAO PHAY LNG 5.1.Cc yu t kt cu chung ca dao phay: Daophayhtlngcdngrtphbin,nhtlkhigiacngccchititnh hnh. Mt s loi dao phay c tiu chun ha: dao phay rnh li-lm, dao phay a mun, dao phay ln rng, dao phay ln trc then hoa Dao phay ht lng c chia thnh 2 nhm: -Nhmkhngmihtlng:cprfinkhngminhdaophaya mdun -Nhm c mi ht lng: c mi prfin nh dao phay ln rng c im chung v kt cu: -m bo prfin li ct khng i v ng nht trong qu trnh s dng saukhimisclitheomttrc,docdngchyuchogiacngnh hnh. -i vi dao khngmi prfin th o tm nh ln (0,04-0,12mm) do khng c nguyn cng mi trn nh dao. S lng rng t nn khi phay khng cn bng, cng thm o tm ln nn cht lng b mt thp hn nhiu so vi dao phay rng nhn. 5.2.ng cong ht lng dao phay: 5.2.1.ng cong ht lng dao phay: Hnh 5.1 ng cong ht lng ngconghtlngdaophayphimbosaochochiucaoprfindaovgc sau khng i sau mi ln mi sc li theo mt trc. chnh l ng cong logarit, c phng trnh trong h ta cc l:mee R . = Trong :Re- bn knh tng ng vi nh rng; Cotg=m, l hng s; 42 - gc quay c cc; - bn knh c cc. Tuy nhin vic s dng ng cong ht lng l khng kh thi v kh ch to v mi mt ng knh dao cn c mt cam ring. Do trong thc t ng cong lgarit c thay th bng ng cong Acsimet. 5.2.2.Phng trnh ng cong ht lng l ng xon Acsimet: Phng trnh ng xon Acsimet nh rng dao phay c dng: 2aRd = Trong :R- bn knh ln nht ca dao phay; a = b.2; b- h s ca ng cong Acsimet. Vi gc sau ti im kho st A th cotg = . Hnh 5.2 ng cong ht lng l ng xon Acsimet 5.2.3.Lng ht lng K v gc sau nh rng d Ta c lng nng ca ng xon Acsimet: a = K.Z Trong : K-lngnngcangxonngvimtrngvcgillng ht lng. Z- s rng dao phay. Ta c tg = K.Z/2, nu ti nh rng c gc sau l d tng ng vi =Re th: tg d = K.Z/2 Re trong : Re- bn knh nh dao phay; 43 De- ng knh nh dao phay; d- gc sau nh rng; K-lnghtlng.TrongthctK=0,5-12mmvcghirtrncc cam ht lng. 5.3.Thng s hnh hc phn ct ca dao phay ht lng a) ng knh ngoi ca dao: D=D1 + 2H Trong :D1- ng knh vng trn y rng, thng khong 1,6-2 ln ng knh l g d. H- chiu cao rng. c xc nh nh sau: H = h + k + r Trong :h- chiu cao profin chi tit gia cng cng thm 1-2mm. k- lng ht lng. r- bn knh y rng. b) Phn ln trn chn rng:cung ln bt u t im ht lng cui cng M, c bn knh r nm gia cung c gc l . Trong r c xc nh theo cng thc: r = R2.sin /2 Hnh 5.3 Yu t kt cu ca dao Bn knh R i qua im M c tnh theo cng thc: R2 = 0,5D h K Trong :- h s tnh n tr s ht lng im dao tin thot ra khi lng rng, =4/5. c) ng knh l d: c chn trn c s m bo sc bn v cng vng ca trc g, ngoi ra cn ph thuc vo chiu cao profin. ng knh l d162227324050 ng knh dao phay D40-5055-6565-7070-130130-195195-230 Chiu di dao phay ht lng: c chn ph thuc vo chiu rng profin chi tit. 44 d) S rng Z: chn sao cho m bo sc bn rng dao, khng gian thot phoi v kh nng mi sc li nhiu ln.Bng s rng dao phay a modun Modun mChiu cao profin h, mm Chiu cao rng H, mm ng knh dao phay D, mm S rng ZT s D/hT s D/H 12,256,5501422,77,7 163638170104,74,5 Bng s rng dao phay khng mi S rng Z 18161412111098 ng knh dao phay, mm 4040-4550-5560-7580-105110-125130-140150-230 Hnh 5.3 Tr s gc dao e) Gc rnh gia cc rng:Gc rnh gia cc rng c xc nh theo cng thc: = + 45 m bo sc bn rng sau khi mi sc li nhiu ln th cn to ra gc = 150-200. iu ny m bo sc bn ca rng khi mi sc n ln cui. Cn c gc 1 v gc 2 p ng yu cu cng ngh trong qu trnh phay ch to, (1+ 2)=1030-20. Sau khi tnh ton, tr s c th c chn theo dy kch thc thng dng cho dao phay rnh, = 180, 220, 250, 300, trong trng hp c bit c th ly =450. Hnh 5.4 Tr s gc dao 46 VN 6 THIT K MI KHOAN 6.1.Cng dng v phn loi a- Cng dng: mi khoan thng dng - To l trn chi tit; - M rng l c sn; - To nhng l c b mt nh hnh nh l tm b- Phn loi: Cc loi mi khoan thng gp l: mi khoan xon vt, mi khoan tm, mi khoan l su,ukhoanvnh.Trongmikhoanxonthngdngrngrihnc.Nc dng khoan cc l c ng knh n 80mm, t cp chnh xc cp 4, cp 5, nhn b mt t Ra=12,5-0,8m vi cc trng hp sau: - Khng yu cu gia cng thm sau khi khoan; - Cn m rng sau khi khoan, khot, doa; - Cn to ren sau khi khoan. Theo tiu chun, mi khoan xon c chia ra cc nhm sau: - Mi khoan di chui tr; - Mi khoan ngn chui tr; - Mi khoan tri chui tr dng trn my t ng; - Mi khoan chui cn; - Mi khoan chui cn 4 cnh. 6.2.Cc yu t kt cu ca mi khoan rnh xon 6.2.1.Gc nh 2 Gc nghing chnh l thng s quan trng nht ca mi khoan, quyt nh n tui bn v nng sut khoan. nh hng n thnh phn lc ct, chiudi li ct, tit din phi ct. Hnh 6.1 Kt cu mi khoan tiu chun 47 Khi tng th lc chiu trc P0, Px tng, cn mmen xon Pz gim. Khi gim t 700 n 450 th lc chiu trc P0 gim 40-50%, cn mmen xon Pz tng ln 25-30%. Nu gc gim th nhn ca mi khoan tng, cho php mi khoan d dng i su vo chi tit khoan, tuy nhin bn ca n s gim xung. Cn c vo vt liu gia cng c th chn gi tr gc ca nh mi khoan nh sau: Vt liu gia cngGi tr () Thp b=400-1400N/mm258-60 Thp tm62 Thp khng r58-60 Thp mangan (Mn)58-60 Gang HB=130-22058-60 ng58-60 ng thau, ng thanh mm65 Nhm, ura, silumin, babit65-70 Nhm tm, tm ghp50-55 Cc hp kim nh58-65 Vt c bng kim loi mu58-60 Cthgimsmimntiphnctcngknhlnnhtcamikhoanbng cchtoralichuyntiptheohaigcv0.Gc0chntrongkhong350-370, chiu rng li chuyn tip B=0,18-0,22 ln ng knhmikhoan. Vi iu kin ny, lm cho nhit ct gim i, tng tui bn cami khoan v tng c tc ct khong 25-30%. 48 Hnh 6.2 Hnh ct mi khoan mi kp gc v 0 i vi cc mi khoan c ng knh nh hn 10mm th nn v trn li ct vi bn knhvngtrnkhong0,3-1,2mmvichiudit2-6mmtingknhlnnhtca mi khoan. 6.2.2.Gc nghing ca rnh xon Gc nghing ca rnh xon c tnh theo ng knh ngoi ca mi khoan, vi: kSDtg. = Trong : Sk- bc ca rnh xon; D- ng knh ngoi ca mi khoan. Khi gc tng th s bin dng ca phoi gim, lm cho qu trnh ct c d dng hn.Thcnghimchothy,khigctngn25-300,mmenxonvlcctgim nhanh. V nu tip tc tng gc thm na th s gim bin i khng ng k. Tnh cht ca phoi ph thuc rt nhiu vo gc nghing . Nu nh, phoi c dng di di v kh dch chuyn trong rnh, c th tc nghn lm gy mi khoan. Khi ln th phoi c dng dy, d thot theo rnh. nng cao bn ca mi khoan tiu chun trong qu trnh gia cng kim loi mu th nn chn gc 229 (i vi thp cacbon) 4. HB 197; 5. HB198-229; 6. HB > 229 (i vi thp hp kim)7. HB 180; 8. HB > 180; 9. Gang rn (i vi gang xm) 9.4.S ct v cc dng dao chut Hin nay, khi chut thng c 2 s ct ch yu sau: 1.S ct n: lng nng ca rng sau cao hn rng trc. 2.Sctnhm:c2haynhiurnglmthnhmtnhmccngng knh, trong chiu rng rng sau ln hn rng trc trong cng mt nhm.

Hnh 9.5 S lm vic ca dao chut ct n 9.4.1. Dao chut ct n 72 Khi chut, nu khng thc hin rnh chia phoi trn li ct th phoi s lin khi v dng hnh tr nn rt kh thot phoi. Nu thc hin rnh chia phoi trn li ct th phoi lc ny dng lt mng c chiu rng b, nn vic thot phoi c d dng hn. Vcrnhchiaphoinnccrngcadaochuthnhthnhlictphf-etham gia vo qu trnh ct. Rnh chia phoi sinh ra cc hin tng khng tt cho dao nh sau: -Lp kim loi ly i ti ch c rnh thot phoi s cao hn ch khc, do lm cho phoi c cnh g cng nn kh cun li. - mn ln nht ca dao ti ch chuyn tip gia li ct chnh v li ct ph. nngtuithcadaochut,trsgctichchuyntipkhngcnh hn 1000.Khngnndng rnhchiaphoicdngbnnguythaychnhtvnhvy th gc sau ca li ct ph bng 0 v gc b gim hn. Hnh 9.6 Kt cu rnh chia phoi Daochutcngknhnhhn100mmthchiurnglictnnl b=(13) d .ividaochutcngknhlnhn100mmthb=1012mm.Chiu rng lp ct c th n b=1,5 dnhng khng qu 1214mm. S rnh chia phoi phi l s chn c th o c ng knh ngoi. Tr s lng nng nn dng i vi dao chut ct n Kim loi gia cngTn dao chut ThpGang Chut trn0,0150,040,030,1 Chut l then hoa, l thn khai, l kha tam gic, chut rnh ngoi 0,030,010,050,12 Chut l vung v l 6 cnh0,030,150,050,2 Chut rnh then0,050,120,050,2 nng cao chnh xc v cht lng b mt th trn dao chut thng b tr mt hoc hai dao ct tinh cui cng c lng nng nh hn, khong 0,010,005mm v khng c rnh chia phoi. 9.4.2. Dao chut ct nhm Dao chut ct nhm c rng phn chia theo tng nhm hai n ba rng hoc nhiu hn.ngknhtrccarngth2nhhnrngth1khong0,020,04mmnhm 73 trongtrnghpvtliubindngnhithkhngthchincttonbsinhra phoi lin. Vi cng mt lc chut Pz th dao chut ct nhm c th ct mt din tch ln hn dao chut ct n. V vy lng nng ca dao chut ct n ti a l 0,04mm th lng nng ca dao chut ct nhm c th n 0,150,25mm. Hnh 9.7 S lm vic ca dao chut ct nhm Dng nhm 1: rng th 1 c vt rnh v ct mt phn chu vi l, rng th 2 khng c lng nng, li ct dng lin v ct phn cn li ca phoi. Nu trong nhm c nhiu hn 2 rng th rng cui cng vn l lin v cc rng trc c b tr so le. Dngnhm2: cngtng tnhvy,nhngcc rngcvtrnhthrng sauc chiu rng rng ln hn rng trc . Dng nhm 3: vic vt lm theo hnh trn bng mi, khi ng sinh ca mt cn lm vi trc dao chut gc = 460, kt cu ny c u im sau: -Loitrckhnnglmhngccrngbncnhkhigiacngccrnhchia phoi. -Trn cc li ct ph ca rng c gc sau t yu cu. -Li ct ph ni tip vi li ct chnh di mt gc ln gip thot nhit nhanh hn, tng tui bn dao. -Phoi c dng hp l nn cun cht hn v yu cu khng gian cha phoi tng i nh hn. Ngynay,daochutctnhmcrnhlmtrnvcnhiucnhcxeml nhng ktcu ph hp nhtcho gia cng l trn. Vic s dng dao chut ct n ngy cng hn ch. 74 Hnh 9.8 Kt cu rng dao chut ct nhm Hnh 9.9 S phn chia cha tt phoi bng lm ct trn 9.5.Phng php ch yu to b mt bng dao chut Kt cu dao chut c xcnhbng s ct lp phoi v phng php ch to bmtkhichut,baogm:phngphptheolpngdng,phngphpndn, phng php t hp. Hnh 9.10 Cc phng php to b mt bng nguyn cng chut 75 Phng php theo lp ng dng: cc rng dao chut c hnh dng ging prfil b mt chut, trong cc rng th tham gia bc tch phoi v cc rng sa ng thc hin vic hnh thnh b mt chut cui cng. Tuy vy, phng php ny tr nn kh khn khi l chut c hnh dng phc tp khc nhau. Phngphpndn:ccrngdaochutchnhdnggingnhprfilcatng onchititcgiacngxong.Vicchtodaolcnytrnnngimhn.Tuy nhin c nguy c hnh thnh cc vt dc theo b mt chut l do vic ch to dao khng chnh xc. Phngphpthp:ccdaoulmtheophngphpndn,cnkhong2-3 dao sau cng s dng phng php ng dng. 9.6.Phn lm vic ca dao chut Phn lm vic ca dao chut ngoi cc rng ct th, rng ct tinh v rng sa ng ra th i khi cn c phn p nhn. 9.6.1. Rng ct th Nhim v ch yu l ct i lng d, ch li ct tinh mt lng d ti thiu. S rng ct th c tnh theo cng thc:1 +=aA AZtinhth Trong :A- lng d tng cng cho mt bn ca nguyn cng chut, mm. Atinh- lng d mt bn li cho cc rng ct tinh, mm. a- lng nng ca mt rng, mm. 1- rng u tinkhng c lng nng v bng kch thc vi rangnh hng. i vi dao chut nhm, s rng th c tnh theo cng thc: ( )rrtinh rthZaA A ZZ 5 . 0 +=Trong :Zr - s rng trong nhm. ar- l lng nng ca nhm.a- Thng s hnh hc phn ct ca rng ct th: Gc trc : gi tr gc trc c chn theo tnh cht ca vt liu gia cng Vt liu gia cng cng HBGc trc () Thp 180 8 5 Gang rn-10 Nhm, ng , hp kim babit-25 Thcnghimchngt:khi50thlchutrachintngcolitcgim ng knh so vi rng cui cng ca dao, khi 150 th ng knh l sau chut tng ln i khi n 0,09mm. Vy, khi tng gc trc ca rng ct th th s lm tng tui bn ca dao chut. Hnh 9.11 Mi sc dao chut l Gc sau : gc sau thng b hn ch do: -Nu gc sau chn ln th khi mi sc li dao chng b mt kch thc; -Nu gcsauqunh slmtngma stgiamtsaucadaovibmtgia cng lm nhn gim v lc chut tng; theo kinh nghim th dao chut trong, = 30; dao chut ngoi = 30-40. -i vi dao chut ngoi, gc sau c th ly ln hn = 100; -Trn mt sau dao ct th c th c cnh vin vi = 00, f 0,05mm; sai lch gc sau cho php 30. b- Bc ca rng ct th: bc rng ca dao chut l khong cch gia 2 nh rng lin k theo chiu dc trc dao. Nu bc rng dao chut ln th dao di v nh hng n gi thnh, nu bc rng nhthnhhngntnhcngnghgiacngvrnhthotphoi.Ngoirayucu trong qu trnh gia cng phi c 4-5 rng dao cng tham gia ct cng lc. Thng thng nn chn bc rng cho dao chut ct n nh sau: L t ) 5 , 1 25 , 1 ( =i vi dao chut ct nhm: 77 L t ) 9 , 1 45 , 1 ( =Trong :L- chiu di l chut, mm. Tiu chun i vi bc rng dao chut: 4, 5, 6, 8, 10, 12, 14, 18, 20, 22, 25 mm. Sau khi tnh bc dao chut v ly trn theo tiu chun th s rng ng thi tham gia ct c tnh theotLZ=Trong :L- chiu di chi tit, mm. t- bc rng dao c chn, mm. c- Rnh thot phoi: Rnhthotphoiphimbosaochophoiccunchtvchaphoi,nh vy kch thc rnh thot phoi ph thuc vo bc dao chut v chiu dy phoi ct. Hnh 9.12 Cc dng rnh thot phoi Dng rnh thot phoi theo cc thng s sau: t- bc rng; C- chiu rng mt sau; - gc lng rng i vi dao chut rng thng; r- bn knh cung chuyn tip gia mt trc v lng rng. Bng kch thc rnh thot phoi thng gp Bc tChiu su rnh hChiurngmt sau C Bnknhy rnh r Bn knh lng R 4,521,512,5 216 2,5 2 1,25 78 2,51,258 3 3 1,5 5 31,510 4 4 2 7 31,5 42 12 5 4 2,5 8 31,5 42 52,5 14 6 4 3 10 42 52,5 63 16 7 4,5 3,5 12 52,5 63 18 7 6 3,5 12 63 73,5 20 9 6 4,5 14 63 73,5 22 9 6 4,5 16 251085 Cc kch thc ny c tnh gn ng theo cng thc: h = (0,450,38)t C = (0,350,3)t R = (0,650,7)t r = 0,5h 79 Kinh nghim cho thy rnh thot phoi c dng cung trn l tt nht v c s chuyn tipugiayrnhvlngrng.Khichutvtliugincthdngrnhthotc lng thng, i vi dao chut c bc ln nn s dng rnh c y l mt ng thng.Bng bn knh y rnh tng ng vi lng nng sao cho phoi cun ra bnh thng Lng nng rng gii hn (mm) ng vi chiu su rnh thot phoi h(mm)Chiurng lpctb (mm) 34567 30,150,20,250,30,4 n 1,2 d0,10,150,20,30,3 n 1,5 d0,050,10,150,20,25 Din tch rnh ch phoi trong tit din chiu trc ly gn ng bng din tch vng trn Fk vi bn knh r = h/2, do 42hFk=Din tch phoi ct ra trong tit din chiu trc: Fc = a.L Trong :a- chiu dy ct; L- chiu di ca chi tit chut. V cc vng ca phoi c khe h nn nu gi K l h s in y ca rnh th L ahaLhK.785 , 042 2= = Nu cho trc K v L th chiu cao ca rnh phoi lL a K h . . 13 , 1 Trong :L- chiu di rnh a- chiu rng rnh hoc L Kha.785 , 02i vi dao ct n h s in y K ln hn 25% so vi dao chut nhm. Bng h s in y rnh K ca dao chut ct nhm H s in y rnh K ng vi lng nng a ca rng (mm)Bc rng t(mm) 0,50,05-0,1>0,1 4,5-83,33,02,5 10-143,02,72,2 16-252,82,52,0 80 Tuy nhin chiu su rnh khng c vt qu tr s h = 0,17d Trong d- ng knh l chut. d- Tnh ton rng ct th ca dao chut: Cc thng s ban u cn thit cho tnh ton dao chut: -Kch thc v hnh dng ca chi tit gia cng, kch thc b mt cn chut; -Lng d chut v hnh dng lng d b tr trn chi tit; -Kch thc, dung sai, cht lng b mt sau khi gia cng; -Lc ko ca my chut, kiu u kp, kch thc l kp chi tit; i vi dao chut ct n: -T chiu di b mt cn chut, tnh bc rng ca dao chut, kim tra s rng ti thiu ng thi tham gia chut. Khi s rng khng th phi thay i bc rng cho ph hp. -ng vi kch thc chn, i tm kch thc rnh thot phoi vi chiu su h ln nht,sautheocngthch=0,17dkimtracngvngcadaochut. Nu khng tha mn th chn kch thc rnh lin k nh hn v kim tra li. -Tra bng chn lng nng ng vi kiu dao chut v vt liu gia cng. -Trabngchnhsin yrnhK vkimtrakchthcrnhccha phoi khng. (i vi dao chut ct n, h s K trong bng phi tng thm 25%) Da vo th, xc nh lc ct n v p, t xc nh Pz v so snh vi Pc ca my v lc bn Pn ca dao. Bng lc ko danh ngha Pc v chiu di hnh trnh ln nht ca my chut Kiu myLc ko danh ngha Pc, tnHnh trnh ln nht mm My chut ngang 7510M101400 7A510101250 7520,7A520201600 7530M301800 7540402000 7551702000 75521002000 81 My chut ng 7705, 7705A5600 7A705B5800 7710101350 7A710101200 7B710, 7710B101000 7720201600 7B720, 7720B201250 Dao chut ct nhm: -Chn s bbc rng v cckch thc ca rnh thot phoi c thc hin nh i vi dao chut ct n. -Xc nh s rng trong nhm Zr. i vi iu kin chut bnh thng th ly bng 2. -Lng nng rng i vi dao chut c vt lm trn ly ti a trong gii hn 0,1-0,2mm. Bng lc ct trn 1mm chiu di li ct dao chut (kG/mm) Vt liu gia cng Thp cacbonThp hp kimGang Gang xm Lng nng rng mm HB197HB 197-229 HB>229HB197HB 197-229 HB>229 HB180 Gang rn 0,029,510,512,512,613,615,88,18,97,3 0,0312,313,616,115,716,918,610,411,69,4 0,0414,315,818,718,419,821,812,113,410,9 0,0516,318,121,620,722,224,514,015,512,5 0,0617,719,523,223,825,5-15,116,613,4 0,0719,621,725,826,028,231,216,718,414,3 0,0821,323,528,028,030,233,518,020,016,4 0,0923,125,530,430,432,836,219,521,617,9 0,1024,727,332,532,835,439,020,723,619,2 0,1126,629,435,035,138,142,022,625,420,6 82 0,1228,531,537,537,840,745,024,326,822,0 0,1330,433,639,840,343,448,025,828,523,4 0,1432,435,742,542,345,750,527,330,325,0 0,1534,237,945,044,548,053,029,032,126,1 0,1636,039,847,247,151,056,030,533,627,6 0,1839,543,652,052,556,562,533,437,030,2 0,2042,747,356,257,660,268,536,040,232,6 0,2245,650,360,062,066,773,838,542,734,9 0,2448,053,163,266,270,978,641,045,136,8 0,2549,554,565,068,073,081,042,146,537,6 0,2651,056,166,670,675,383,442,947,739,0 0,2854,058,870,074,479,888,345,550,041,3 0,3056,461,573,078,584,593,347,652,243,1 9.6.2. Rng ct tinh, rng sa ng v chiu di ca dao chut a- Rng ct tinh Ccrngctth, saukhictthnglicckhuyt tttrnbmt,vvygia cc rng ct th v rng sa ng cn c rng ct tinh ct ht cc khuyt tt b mt do rng ct th li. on rng ct tinh ca dao chut nhm c th lmvic theo phng php ct n hoc ct nhm, cn dao chut n th ch theo phng php ct n. Lng d mt bn cho cc rng ct tinh v s rng ct tinh hay s nhm rng c chn theo bng nhn b mt gia cng Ra= 105mnhnbmtgiacngRa= 2,51,25m Daochut trn Daochut then hoa Daochut trn Daochut then hoa Lng nng phn on th Lng nng phn on bn tinh Lng dhai bn cho phn tinh, mm S phn on tinh S rng ngoi phn on S phn on tinh S phn on tinh Lng dhai bn cho phn tinh, mm S phn on tinh S rng ngoi phn on S phn on tinh S rng ngoi phn on n 0,1-----0,05-0,07 11-211-2 83 0,110,200,06-0,08 10-210-2 0,07-0,13 1-231-22-3 0,210,40,11-0,16 20-320-20,13-0,2 23-52-32-3 0,410,6 (0,40,6)2a 0,11-0,16 20-32-30-2 0,2-0,32 2-33-52-32-3 C mt on rng bn tinh trung gian gia on rng ct th v ct tinh, hoc l 1 n2nhmrngmclngnngbng0,4-0,6lngnngrngctth.Lngnng rng ct tinh c lm thay i gim dn t nhm ny n nhm khc 1,5-2 ln. gim chiu di dao chut v tng nhn b mt gia cng th bc ca cc rng sa ng cn lm nh li nu bc 10mm. Bng tr s bc gim nh ca rng tinh v rng sa ng Bc rng, mmBc rng, mm ThTinh v sa ng Chiu di b mt chut, mm ThTinh v sa ng Chiu di b mt chut, mm 108n 4512n 80 9 18 14Trn 8012 10 >45 2016n 110 106514Trn 11014 12 22 16n 110 1612 >65 2516Trn 110 (i vi chi tit gia cng t cp chnh xc 2-3 ly 5 rng sa ng, cp chnh xc 4 ly 3-4 rng v cp chnh xc 5 ly 2-3 rng) Gctrccarngcttinhvrngsangclynh rngctth. Hnh di y ch cho thy, nu gc trc cng ln th cng lm gim i kch thc ng knh rng lng R. Hnh 9.13 Gc trc ca rng ct tr v rng sa ng 84 Gc sau ca rng ct tinh thng c chn theo tr s sau: -i vi dao chut trn, then hoa, rnh then v dao chut ngoi khng iu chnh th =20, rng sa ng th =10. -i vi cc dao chut ngoi khc th rng ct v rng sa ng c gc sau =3-40. -C th c ng vin ti mt sau ca dao sa ng vi chiu rng 0,2-0,3mm. c th nhn c b mt nhn sng th i khi ngi ta cn lm thm cc rng c nhn, cc rng ny ch lm nhim v p cht, nhn b mt. Thng thng trong trng hp ny th ngoi bin dng d cn c bin dng n hi, do ng knh l nhn c trn chi tit s nh hn ng knh cc rng c nhn. Hnh 9.14 Prfin rng c nhn 9.6.3. Chiu di ton b dao chut Chiudidaochutbaogmchiudicaccthnhphn:phnchui,c,cn chuyn tip, phn nh hng trc, on rng ct th, on rng ct tinh, on rng sa ng v phn nh hng sau. Chiu di dao chut phi p ng c cc yu cu sau: -Khng c vt qu chiu di hnh trnh ti a ca my chut. -Phi ph hp vi bn my ca my gia cng. -p ng kh nng thun tin khi gia cng cng nh cc mi nguy v n nh, cng vng. i vi dao chut p, thng thng chiu di dao khng c vt qu 10d. Bng chiu di gii hn ca dao chut gia cng c trn cc mi tm ng knh dao chut T 12 -15T 15-20T 20-25T 25-30T 30-50 50 Chiu di dao chut 7008001000120013001500 Bng chiu di gii hn ca dao chut phng v rnh then 85 Kch thc nh nht ca tit din ngang dao chut 5T 5-8T 8-12T 12-18T 18-22 22 Chiu di dao chut 5007501000120013001500 Nu kt qu nhn c c chiu di ca dao qu ln th phi tnh ton li chiu ditckchthcgiihnchophp.Nukhngcnathphidngbdao chut vi 2, 3 hoc nhiu dao hn na. Tnh ton sao cho dao chut cui cng hoc nhng rng dao cui cng l chnh xc nht, c gi tr t nht v ngn nht c th. 9.6.4. Dung sai kch thc dao chut Tiu chun v kch thc c bn ca dao chut c cho nh sau: -Sai lch ln nht ca ng knh tnh ton rng th c xc nh ty thucvo lng nng ca rng v khng c vt tr s trong bng. -Dung sai ng knh rng sa ng v ng knh rng ct tinh khng c vt qu cc tr s cho trong bng. -Dungsaichiuditonbdaochutkhngcvtqu3mmivichiu di dao chut n 1000mm v 5mm i vi chiu di dao chut trn 1000mm. -ohngknhcarngcttinh,rngsangvphnnhhngsau khngcvtqugitrtuyticadungsaichongknhtngng, ngoi ra o tt c cc rng ch c th v mt pha. -Dungsaichiusurnhthotphoichophpkhngvtqu0,3mmivi chiu su rnh n 4mm v +0,5mm i vi chiu su nh ln hn 4mm. Bng dung sai ng knh tnh ton ca rng ct th Dung sai khi lng nng cc rng 2a (theo ng knh, mm)Kch thc danh ngha dao chut n 0,05Trn 0,05 n 0,08Trn 0,08 n 80-0,008-0,010-0,015 Trn 80-0,012-0,015-0,020 Bng dung sai ng knh rng sa ng Ad ca dao chut tr Cp chnh xc lng knh danh ngha dao chut, mm AA2a A3 86 Dung sai Ad (m) n 18578 Trn 18 n 305810 Trn 30-5071012 50-8081215 80-120101418 120-150121620 87 VN 10 THIT K DNG C GIA CNG REN 10.1. Dao tin ren v cc thng s hnh hc Chi tit ren l v cng quan trng trong vic lin kt cc chi tit my li vi nhau. Cnhiuphngphpgiacngrennhtinren,tarren,bnren,phayren,mi ren Hnh 10. 1 Dao tin ren n v dao tin ren hnh lc 10.1.1.Dao tin ren n Daotinrenncnggingnhdaotinnctrentrnmytinvnnng. Prfin dao ph hp vi prfin ren c ct. a- Gc sau Dao tin ren n c mt rng ct ren, prfil dao phi thit k ph hp vi prfil rencct.Daotinrennc2lictchnh,vkhictrencchuynngchy dao dc nn gi tr cc gc sau hai li ct tri v phi thay i khc nhau. Gc sau li ct tri: =t c t. Gc sau li ct phi: + =f c f . Trong :t.c- gc sau ca li ct bn tri khi ct. t- gc sau ca li ct bn tri trng thi tnh. f.c- gc sau ca li ct bn phi khi ct. f- gc sau ca li ct bn phi trng thi tnh. - i lng thay i gc sau. Gc c th c xc nh nh sau:2cos . tg tg =Trong :- gc nng ca ren. 88 - gc prfil ren. Hnh 10.2 Dao tin ren n b- Gc trc Gctrccchnphthucvovtliugiacngvcthcchnnh dao tin nh hnh. Hnh 10.3 S tnh ton prfin dao tin ren 89 Nu chn 0 th prfil dao tin ren phi c tnh li da vo prfin ren ca chi tit. Cch tnh th ging nh vi dao tin nh hnh. Thng s hnh hc ca ren v dao tin ren: - gc prfil ren trong tit din qua trc. - gc trc. S- bc ren. t- chiu su ren trn chi tit. p- gc prfil dao tin trong tit din vung gc vi mt sau. n- gc prfil dao tin trong tit din mt trc. tp- chiu cao prfil dao trong tit din vung gc vi mt sau. m bo ct c ren c gc profil chnh xc l th cn phi tnh chnh xc gc profil ca dao tin trong tit din vung gc vi mt sau ca dao nh sau: [ ] ( ) + =cos . cos . sin . 2212 212r r rStgop ) cos . sin . ( 2212 2120 r r rStgn =Trong trng hp =0 th: cos . . 2 2 tStgp=tStgn. 2 2= Vy dao tin ren n hnh lng tr hoc hnh trn cng c tnh ton nh dao tin nh hnh hnh lng tr hoc hnh trn. Dao tin hnh rng lc nh c nhiu li ct nn c th tng nng sut rt nhiu. 10.1.2.Dao tin ren hnh thang Khi tin ren hnh thang thli ct nh dao thng nm y rnh trng vi tit din y ca ren hoc vung gc vi ng knh trung bnh. 90 Hnh 10.4 Cc cch g t dao khi tin ren Trongtrnghpthnht,hailictbnlngthngvtrngvititdin ca b mt ren l ng xon vt Acsimet nn vic ch to l n gin. Tuy nhin, trong trng hp ny th gi tr gc sau trong trng thi ng ca hai mt bn l khc nhau bi lng thay i gc sau . Trong trng hp th hai th iu kin ct ca hai li ct bn l nh nhau, nhng li ct bn khng phi l ng thng, m l ng cong nn vic ch to dao gp kh khn. V vy, dao trong trng hp ny ch dng cho gia cng s b, v khng i hi chnh xc cao. Thng thng, lng d gia cng l 0,4-0,5mm cho nguyn cng cui. Hnh 10.5 S xc nh gc sau v chiu rng dao tin 91 Gcsaucadaophthucvogitrgcnngcaren,vgcnngrenthayi theo ng knh nn gi tr gc sau thay i dc theo li ct ca dao. 10.2. Taro ren 10.2.1.Cng dng v phn loi Ta r c dng ct hoc sa ng ren trong, ty theo cng dng v phn loi c th c phn thnh: -Tartaycdngctrenbngtay,cchtothnhbgm2hoc3 chic. -Tar my c dng ct ren trn my tin, my chuyn dng -Tar dng gia cng ren ng. Hnh 10.6 Cc loi tar 10.2.2.Cc thnh phn kt cu ca taro Kt cu v kch thc c bn ca tar c tiu chun ha, bao gm: phn ct, phn sa ng, s rnh, hng rnh Hnh 10.7 Thnh phn kt cu ca tar a)Phn ct Phn ct l1 l phn quan trng nht ca tar bi v thc hin ch yu ct ren v c gc cn . Chiu di phn ct c nh hng n nng sut, tui bn v chnh xc ca ren ct. 92 Hnh 10.8 Phn cn ct ca tar V gc cn l nh nn nu gi a l chiu dy lp ct theo phng vung gc trc tar th pha =cng chnh l chiu dy thc ca lp ct theo phng gc . Trong :p- s ren ct trn phn ct. h- chiu cao thc t ren. Gi tr chiu di phn cn l1 c xc nh nh sau: 20 cd dh= ;ntg Sa .= ;) 1 ( . 201f tgd dlc= Trong :d0- ng knh ngoi ca ren. dc- ng knh l khoan trc khi tar. n- s rng tar. S- bc ren. f = 0,30,18 i vi tar t 2 n 30mm i vi cc loi tarai c c ng knh t 2 n 30mm th gc c chn l 3030. Chiu dy ct a khng c nh hn bn knh v trn ca li ct. Tar ai c phn cn ct c chn bng 12 ln bc ren ct. Tarmy,lkhngthngthl1bnghairenct,lthngthl1bng6renct. Trong trng hp b hai tar th tar th ly bng 6 ren ct v tar tinh ly bng hai ren ct. Tar tay khi ct bng 1 tar th l1 bng 8 ren ct, bng 2 tar th l1 bng 6 i vi, bng 2 i vi tinh. Tar c phn cn ct ngn c dng ph bin hn v: 93 -Gim lc ct n v v ct mt tit din lp ct ln; -Gim m men xon trong tt c cc trng hp tr khi ct ai c ngn; -Gim lc ma st v chn phoi trnh b gy v; -Gim thi gian my; -Nhit luyn d hn. Phn ct ca tar cn c ch to chnh xc nhm m bo dn hng tt khi tar i vo l ren. b)Phn sa ng Phn sa ng l2 nhm sa ng ren v nh hng tar v ng thi cng nhm d tr khi mi li tar. Rng u tin s lm nhim v sa ng ren, cc phn ren cn li c tc dng nh hng khi tar i vo l ren. gim ma st, phn sa ng c ch to cn ngc v pha cn l 0,050,01mm trn 100mm chiu di. Trong qu trnh mi li, chiu di phn sa ng phi bo m: -i vi ren bc ln l2 0,5.d0. -i vi ren bc nh l2 (1,21).d0. -i vi tar ai c l2 0,6H. Trong :d0- ng knh ngoi tar; H- chiu cao ai c. Chiu di phn sa ng c th chn s b l2 = (612)S. c)S rnh v dng rnh S lng rnh ca tar nh hng n chiu dy lp ct v mmen xon khi ct. s rnh ca tar c chn ph thuc vo ng knh ca tar v vt liu gia cng. Bng s rnh ca tar chn theo ng knh ngoi Vt liu gia cng ng knh ngoi tar (mm) 2-68-1416-2022-2427-3033-3639-52 Kim loi en2-3333444-6 Kim loi mu22-333444-6 Cc thng s tit din rnh bao gm: ng knh li d, chiu rng p, gc trc . 94 Hnh 10.9 Prfin rnh tar v cc dng rnh xon Bng kch thc p v d theo s rnh tar S rnhK hiu 23456 ng knh li d(0,360,38)d0 (0,380,4)d0(0,420,45)d0(0,50,52)d0(0,520,55)d0 Chiu rn rng p(0,40,45)d0(0,30,32)d0(0,20,22)d0(0,170,2)d0(0,160,18)d0 d0- ng knh ngoi tar Hng ca rnh: dchtoththnglmrnhthng,khigiacngrencnchnhxccao hoc ren trong l su d thot phoi th lm rnh xon. Gc xon thng t 10-160. Khi ct kim loi mu c th chn = 25-250. hng phoi v pha u ca dao th cn vt gc = 7-100. d)Cc gc phn ct Gctrcclachnphthucvovtliugiacng.Giacnggang,ng, thpcngth=0-50;thpcngvath =8-100;thpdov dai th =12-150;hp kim nh th = 20-300. Gc sau thng c to thnh phn ct cn l1 bng cch ht lng theo ng knh ngoi. Tr s gc sau c th c chn ph thuc vo kiu ca tar v vt liu gia 95 cng. i vi tar my v tar ai c = 8-100, tar tay = 6-80, ct hp kim nh = 5-60. Gi tr lng ht lng K theo cng thc: tgndKT.=Trong :n- s rng; dT- ng knh u nh ca tar. e)Dung sai cc kch thc ca taro Theo tiu chun tar c ch to vi cc cp chnh xc C, D, E, H. Cp chnh xc C,Dcpdngchotarcmiprfinren,cpE,Hivitarkhngmiprfin ren. Dung sai ca tar ren c qui nh cho cc thng s ca ren, bao gm: -Gc prfin ren ; -Bc ren S; -ng knh ngoi d0; -ng knh trung bnh dtb; -ng knh trong d1. a- Dung sai gc prfin ren : - i vi cp chnh xc C, D: S=0,75;dung sai gc' 15 ' 352 = - i vi cp chnh xc E:S=0,25;dung sai gc' 20 ' 852 = - i vi cp chnh xc H:S=0,25;dung sai gc' 30 ' 1002 = b- Dung sai bc ren S- i vi cp chnh xc C:dung sai S=0,10mm trn 25mm chiu di. - i vi cp chnh xc D:dung sai S=0,05mm trn 25mm chiu di. - i vi cp chnh xc E:dung sai S=0,05mm trn 25mm chiu di. - i vi cp chnh xc H:dung sai S=0,07mm trn 25mm chiu di. c- Dung sai cc ng knh Dung sai cc ng knh ngoi v trong c qui nh da theo trng dung sai ca ren ai c. 96 Hnh 10.10 Phn b dung sai ren tar Trn s phn b dung sai th: -N l dung sai ch to tar. -j l lng d tr cho mn tar khi gia cng v lng gim ng knh khi mi li. -p l lng lay rng khi ct. Dungsaingknhtrungbnhquytnhnchnhxccarar.Dungsai ngknhtrungbnhcuaiclunnmtrnngknhdanhnghakhilpvo bulong khng b kt. Dungsaingknhngoicaaicnmtrnngknhdanhngha.Giihn trncangknhngoitarcchnsaochochiurngnhrenthctbng khong 0,6 chiu rng nh ren l thuyt. ng knh trong ca tar khng tham gia ct nngii hn trn ng knh trong ca tar phi nh hn gii hn di ng knh trong ca ren ai c. 10.3. BN REN 10.3.1.Cng dng v phn loi Bnrendngctrenngoi,bnrencnhiuloinhbnrentrn,bnren vung, bn ren ng, bn ren iu chnh 97 Hnh 10.11 Cc loi bn ren 10.3.2.Kt cu bn ren trn Kch thc bn ren trn c tiu chun ha. Bn ren trn l loi dng c ct ren khng chnh xc v sau khi nhit luyn khng mi li c prfin ren. Hnh 10.12 Kt cu bn ren trn a- ng knh ngoi D ng knh ngoi c chn ph thuc vo kch thc ca ren v l thot phoi. ng knh ren d0 (mm)ng knh ngoi Dng knh ren d0 (mm)ng knh ngoi D 98 (mm)(mm) 1-2,61620-2555 3-52027-3665 6-92539-4275 10-113045-5290 12-143856-60105 16-204562120 b- Chiu rng bn ren ChiurngbnrenBcbnhhngbibindngkhitivkhnngnh hngcabnrenkhilmvic.Chiu rngbnrenc chnsaocho svngren trnphnctvphnsang.ThngthngchiurngBchnsaochocc6-9 vng ren, trong 3-4 vng ren cho phn ct v 3-5 vng ren cho phn sa ng. i vi ren bc nh th phi bo m t 12 n 16 vng ren, mt u ca bn ren phi c khot lm. c- S l thot phoi S l thot phoi n c chn theo ng knh ren nh trong bng ng knh ren1-55,5-1618-2730-3336-4852-64 S l thot phoi n345678 d- Phn ct l1 ca bn ren Bn ren c ch to c phn ct c hai pha tng tui th v thun tin trong s dng.Gc nghing ca phn ct c chn ph thuc vo bc ren, gc nghing cng nh th cng c nhiu rng tham gia vo qu trnh ct v cng d dng ct vo chi tit gia cng. Bc ren cng ln th nn chn gc cng nh. S2 th 2=300; e- Chiu rng rng b v chiu rng l thot phoi c Chiurngbvccnhhngnscbnvcngvngcabnren.Khi chiu rng b tng th bn ren c nh hng v nh tm tt, nhng lc ma st li tng. Nu b ln th l thot phoi c gim v nh hng n kh nng thot phoi. 99 Miquanhgiabvctheo7 , 0 65 , 0 =cb,trongtrnghpcbitcthly n 0,8 nhng khng c bng 1. f- Kch thc v v tr l thot phoi L thot phoi c th hin qua ng knh ca l thot d v ng knh D ca tm ca l thot phoi. Chng ph thuc vo ng knh ngoi d0, ng knh trong d1 v gc trc . i vi mt trc cong D1=d1[cos+sin.cotg(-)] i vi mt trc phng ) cos() sin( .sin . 221 ++ +=xdd ) sin(2) cos( . cos2 21 1 + + + + =dxd D x = (1,21,3)S Sau khi tnh d v D1 cn kim tra li sc bn bn ren qua gi tr l 2 2 21d D Dl =Gi tr l phi ln hn (0,15-0,12)D i vi bn ren c 3-5 l thot phoi v ln hn (0,1-0,09)D i vi bn ren c 6-8 l thot phoi. 100 Hnh 10.13 Cc dng mt trc ca bn ren 10.3.3.Cc gc phn ct Gc trc c chn ph thuc vo vt liu gia cng. Khi ct vt liu cng =10-120, vt liu cng trung bnh =25-300, vt liu mm =20-250. Gc trc phn ct v phn sa ng thng c chn nh nhau, tuy nhin vic ct c d dng hn th gc trc phn ct c th c chn ln hn. Gc sau c gi tr khong 6-90. Gc sau phn ct c to thnh do ht lng, lng ht lng K sau mt rng c th c xc nh: tgndK1.= phn sa ng gc sau thng bng 0 v rt kh to ra gc sau ti phn sa ng. 10.3.4.Dung sai kch thc ren Vickimtratrctipchnhxccarenlrtkhdothngkimtraqua mu th c ct bi bn ren. Sai lch kch thc ca bn ren c chn vi cp chnh xc cp 2. Sai lch bc ren S=0,01mm trn chiu di 10 vng ren. Bng sai lch na gc ph thuc vo bc ren Bc ren S(mm) 0,350,50,751,01,25-1,51,75 /2 (pht) 5535272720- 101 10.4. GIA CNG REN BNG PHNG PHP BIN DNG DO 10.4.1.Qu trnh cn ren Cn ren l phng php gia cng ren bng bin dng do c dng trong sn xut hng lot ln. B mt gia cng ren bng phng php ny c cng v bn cao do cu trc ca th kim loi c lin tc. Haiphngphpcnrenthnggplcnrenbngbncnrenphngvbng con ln cn. Hnh 10.14 Cu trc kim loi bn trong ren v cc phng php cn ren 10.4.2.Dng c cn ren a- Bn cn ren Kt cu bn cn ren gm c: -Phn ct l1. -Phn thot l3. -Phn sa ng l2. Phn ct l1 thng c chn l1=1,1..dtb. Trong dtb- ng knh trung bnh ca ren cn. 102 Hng ren ca bn cn c nh v di ng ngc nhau, cc ng ren trn bn cn c gc nghing bng gc nghing ca ren. tbdStg. =Trong S l bc ren. Sai lch ca gc nghing khng vt qu 10. Chiu di L ca bn cn di ng ln hn chiu di ca bn cn c nh khong 15-25mm chi tit d ri khi bn cn sau khi gia cng. Khi cn th ren ca hai bn cn lch nhau bc S/2. Hnh 10.15 Bn cn ren phng Chiu rng bn cn B=2.l0 + (23)S. Trong l0 l chiu di phn ren cn cn ca chi tit. b- Con ln cn Cnrenbng conlncnhiuuimhnbncnv plclnchitit cnnh hn nn c th cn cc chi tit thnh mng, vic g t v iu chnh c d dng hn. Cn ren bng con ln c hai phng php chnh: cn ren bng chy dao tip tuyn v hng knh. Hnh 10.16 Cn ren bng con ln chy dao hng knh 103 trnhhintngttrtcaphi,tccahaiconlnphibngnhau. trnhvicphibylnkhicnthtmcaphictcaohntmcachitit lng (0,1-0,5)mm. Hnh 10.17 Cn ren bng con ln chy dao tip tuyn iu kin phi i qua c gia hai con ln cn l: 25 , 1 1 , 121 =VV Trong :V1- tc di im tip xc phi vi con ln 1. V2- tc di im tip xc ca phi vi con ln 2. iu kin c bn gia cng ngren chi tit l gc nng ca rencon ln v ca chi tit phi bng nhau. 104 VN 11 THIT K DNG C GIA CNG RNG BNG PHNG PHP NH HNH 11.1. Dao phay vu m un Daophayvumundngctbnhrngcmunlnm>50mm.Ccbnh rng ny thng kh c th gia cng bng cc loi dng c ct khc. Prfilcadaophayvumuntrngviprofilcarnhbnhrnggiacng. Dao phay vu c th dng gia cng bnh rng nghing, trong trng hp ny dao phay vu lm vic theo phng php bao hnh khng tm tch,mun cchn lmun trong tit din php tuyn vi bnh rng. Hnh 11.1 Dao phay vu mun v dao phay a mun 11.2. Dao phay a m un Dao phay a mun l dao phay nh hnh ht lng c gc trc =0. Do profil li ct trng vi profil rnh rng bnh rng.Prfil ca rnh bnh rng c xc nh theo s liu ban u l mun m, s rng Z v gc n khp , trn c s , cc thng s ca bnh rng tiu chun c xc nh: -Bc rng: t = .m -Bn knh vng chia: 2.Z mrc=-Chiu dy rng: 2.mS=11.3. Tnh ton profil dao phay a m un S tnh ton prfin dao phay a mun trong h ta cc nh sau: 105 -r0- bn knh vng c s. -rc- bn knh vng chia. -rx- bn knh ng vi im M bt k trn prfin. -Re- bn knh nh rng. -Ri- bn knh chn rng. Hnh 11.2 Prfin thn khai dao phay a mun im M(x,y) bt k trn on thn khai c bn knh rx c xc nh nh sau: + = =+ = =) cos( . cos .) sin( . sin .00x x x xx x x xr r yr r x ivibnhrnghiuchnhdnghocmthvnpdngcngthctrn, khi : Zc. 2 =th Z mSZtgZcc.. . 2. 2'+ = Trong :- h s dch chnh dng hoc m Sc-lnggimchiudyrngtrnvngchiatonnkhehsn rng khi n khp. Khi gia cng bnh rng tr thn khai xon th c th dng dao phay a mun nh khi phay bnh rng thng, tuy nhin s rng lc ny l: 3cosZZt=Trong :Z- s rng ca bnh rng xon c gia cng. - gc nghing ca rnh xon. m- mun php tuyn. 11.4. B dao phay a mun 106 Trongtnhtonprfindaophayamunthtaimprfinphthucvo mun m, gc n khp v s rng Z ca bnh rng gia cng. iu ny c ngha l nu s rng Z l khc nhau th prfin rng s khc nhau. Nh vy, nu cn gia cng cc bnh rngcsrngkhcnhauthihiphicsdaolkhcnhau.iunylkhng thc t, kh thc hin. Vy i hi mt dao phay c cng mun m v gc n khp th cthgiacngccbnhrngcsrnglkhcnhautrongmtkhongnhtnh. Thng thng th thit k mt b dao 8 dao hoc 15 dao, mi dao c s rng nht nh. S rng bnh rng gia cngS hiu dao N B 15 daoB 8 dao 1121213 112 13 2141416 212 15,16 317,181720 312 19,20 421,222125 412 2325 526292634 512 3034 635413554 6124254 7557953134 712 79134 8135135 107 VN 12 THIT K DNG C GIA CNG RNG BNG PHNG PHP BAO HNH 12.1. Khi nim c bn Nguyn l c bn khi gia cng cc chi tit rng theo phng php bao hnh c tm tchlchitittrongqutrnhgiacngcchocchuynngn khpvidng c. Khi s c mt im tip xc chung m c cng tip tuyn v php tuyn chung. im tip xc chung s c vn tc tng i V quanh mt tm quay tc thi P no . Tp hp tm quay tc thi P c gi l tm tch ca hai chi tit phi v dng c. V cng t tp hp cc im tip xc chung s cho ra ng n khp, cn gi l ng to hnh. Trongqutrnhgiacngchititluncsquaytrnnntmtchcachititl vng trn tm tch. Dng c c th quay trn hoc tnh tin, v khi gi l ng thng tm tch hay vng trn tm tch. Hnh 12.1 Nguyn l gia cng theo phng php bao hnh 12.2. Thitkccdngcctrngtheonguynlbaohnhctmtchgiacng bnh rng tr thn khai 12.2.1. Cc loi mt xon vt dng trong thit k dng c ct Dngmtxonvtthngcdngkhithitkdngcctrngtheophng php bao hnh c tm tch. Mt xon vt k l mt xon vt m ng sinh l mt ng thng chuyn ng to thnh. 108

Hnh 12.2 Dng c ct rng theo nguyn l bao hnh vS mt xon vt k Xt h ta Oxyz, xt mt tr trn xoay c trc Oz v bn knh ro l mt tr c s. C ng thng AB to vi trc Oz gc khng i v tip tuyn vi mt tr ti im N, chuyn ng xon vt to nn ng GL c bc xon h, khi : g r hocot . . . 2 =Chuyn ng ca ng thng AB theo trc Z c vn tc V v vn tc trn , th khi : PVh= = . 2 Pcgilthngscamtxonvt.imM(x,y,z)trnngthngABc phng trnh tham s nh sau: + =+ = = cos . .cos . sin . cos .sin . sin . cos .t P zt r yt r xoo y l phng trnh tng qut ca mt xon vt k. a- Mt vt Convoluyt Phngtrnhtngqut trncnglphngtrnh mtxonvthConvoluyt.Mt xon vt Convoluyt c c im l giao tuyn ca mt xon vt vi mt phng vung gc trc Oz l ng thn khai c phng trnh: 109 2 2 2 20. . tg P r + =b- Mt xon vt Acsimet Tphngtrnhtngquttrn.Nuchor0=0thphngtrnhlcnytrthnh dng mt xon vt Acsimet: + === cos . .cos . sin .sin . sin .t P zt yt x GiaotuyncamtxonvtAcsimetvimtphngvunggcvitrcOzl ng cong Acsimet: . .tg P =Trongtrnghpgc=0thtacdngxonvtHelicoitvingthngAB vung gc vi trc Oz. c- Mt xon vt thn khai Ta c phng trnh mt xon vt thn khai c dng: + =+ = = cos . .cos . sin . cos .sin . sin . cos .t P zt r yt r xoo Trong c xc nh theo cng thc g r hocot . . . 2 =Mt phng vung gc vi trc Oz ct mt thn khai theo ng thn khai c dng cos0r= ;2 2 2y x + = Hnh 12. 3 Mt xon vt Convoluyt v mt xon vt Acsimet 110 Hnh 12.4Mt xon vt Hlicoit v mt xon vt thn khai 12.3. Thit k dao phay ln rng 12.3.1. Nguyn l lm vic Dao phay ln rng c thit k da theo nguyn l n khp ca trc vt vi bnh vttrongqutrnhlmvic,trongtrcvtldngc,bnhvtlbnhrngcngia cng. Chuyn ng quay ca trc vt v bnh vt c quan h l trc vt quay mt vng th bnh vt quay 1/Z1 vng, trong Z1 l s rng ca bnh cn gia cng. Chuyn ng quay ca dao quanh trc cng ng thi l chuyn ng ct chnh. c th n khp ng th cc kch thc c bn ca rng bnh vt v trc vt trong tit din php tuyn vi hng rng phi bng nhau. tn = t1;d = 1;md = m1 cosnott =tboDttg. =Trong :-gcnngcangvtngvihnhtrchiatrungbnhcng knh Dtb. => cos . .tvnDttg =tb tbnDmDt= =.sin 12.3.2. Kt cu dao phay ln rng Dao phay c ng knh ngoi cng ln th cng gia tng chnh xc prfin rng v nng sut ct gt, ci thin c iu kin ct. Tuy nhin s gia tng chi ph. ng knh dao phay c tiu chun ha, do vy dao phi c chn li theo tiu chun. 111 Cc iu kin i vi ng knh dao Dc: d p H Dk e+ + . 2 . 2)2( 21 k eH pdt D + + Trong :t1- kch thc rnh then. d- ng knh l g. Thng thng d = (0,20,45)De. Hnh 12.5 Kt cu dao phay ln rng Hnh 12.6 S n khp ca dao phay ln rng vi bnh rng Chiu di dao L v chiu di phn lm vic l sau khi tnh ton cng c chn theo tiu chun. Khigiacngnkhp,ccimtipxccahaiprfinphinmtrnngto hnh,vtrgiihncaccimtohnhcxcnhbigiaoimcangto hnh vi vng nh rng. Chiu di lm vic l c xc nh: 112 = cos .sinsin .22 2h rr R lo el Trong :Rel- bn knh ngoi ca bnh rng gia cng. ro- bn knh vng trn c s bnh rng gia cng. 1 r - bn knh vng trn chia bnh rng. Hd- chiu cao u rng ca thanh rng khi thy ca dng c. - gc prfin rng. 12.3.3. Thit k prfin dao phay ln rng a- Trc vt c bn Bnh rng thn khai ch n khp ng v chnh xc vi trc vt thn khai, cc dng trc vt khc khng n khp c vi bnh rng thn khai. Trc vt m dng thit k dao phay ln rng gi l trc vt c bn. Trc vt c bn c mt vt c bn 1, li ct 3, mttrc2vmtsau4.Vcnphicgcsaunnmtsau4chnhthnhdi dng ht lng hng knh. Chnh v vy khi mi sc li mt 2 th li ct 3 s khng cn nggitrbanu,tckhngnmtivtrthnkhaina.Vvy,cthnitrcvt thn khai l kh ch to, cho nn dao phai ln rng khng thit k ng nh dng trc vt thn khai, m c thit k theo dng gn ng. Hnh 12.7 Trc vt c bn v rng dao phay ln rng b- Cc phng php gn ng khi thit k dao phay ln rng Phng php 1: prfin thng trong tit din qua trc phngphpny,prfincongcatitdiniquatrcvtthnkhaicthay bng prfin thng.Giao tuyn ca trc vt thn khai vi mt phng i qua trc l ng cong. Ta im bt k trn ng cong giao tuyn c xc nh theo hm inv() nh sau: k kinv p x . =Trong :cosk = r0/yk. p = t0 / 2. = m/2.cos : l thng s ca mt vt. Phng php 2: prfin thng trong tit din php tuyn vi rnh rng 113 Phng php ny thc hin bng cch thay th trcvt thn khai c bn bngtrc vtcprfinthngtrongtitdinphptuynvirnhcatrcvt.Prfincatrcvt cxcnhtheohaiphngphp:prfinthngtitdin phptuyncchnbng vi prfin dng sinh ca bnh rng gia cng; gc prfin ca rng dao phay trong tit din php tuyn c chnkhc vi gc prfin dng sinh ca bnh rng gia cngmt lng . 12.4. Thit k dao xc rng thn khai Daoxcrngthnkhaidngctbnhrngtrrngthng,rngnghing,bnh rng bc, bnh rng ch V, bao gm dao xc rnghnh a, dao xc rng hnh cc, dao xc rng cn lin, dao xc rng nghing ct rng nghing v rng ch V. 12.4.1. Nguyn l lm vic v kt cu Cng tng t nh trong qu trnh n khp ca hai bnh rng, trong mt bn l chi tit cn gia cng v mt bn l dao xc. tothnhgc sau lictnhv gcsaubhaili ctbnth prfin rng dao trong tit din vung gc vi trc dao phi c lng dch chnh x = m. Hnh 12.8 Kt cu xc rng cho mt bn l mt vt thn khai Ti tit din BB th khong dch chnh ca dao bng 0, bnh rng tng ng tit din BB l bnh rng tiu chun khng dch chnh. Ti tit din AA l mt trc ca dao c lng dch chnh ln nht x = + m, v ti tit din CC c lng dch chnh nh nht x = - m. Vy, lng dch chnh ca thanh rng khi thy gim dn t mt AA n mt CC v chnh s gim dn ny to nn gc sau ca rng dao xc. 114 Mtsaunhrngcadaoxclmtcn,mtbntrivmtbnphilmt xon vt thn khai. Vic gia cng rng dao xc c th thc hin c bng cch phay ln rngtrnmyphaylnrngviskthpcachydaotheophngthngngv chy dao theo phng ngang, sao cho phng chy dao tng hp to vi trc dao xc gc d. a- Ti tit din khi thy BB Ti tit din ny, kch thc ca rng dao xc bng kch thc ca thanh rng khi thy ca dao xc, v c: Bc rng:t = .m; ng knh vng chia:dc = m.Zd; ng knh vng c s:d0 = dc.cosd. Chiu dy Sc o theo cung vng chia: 2.2m tSc= =Chiu cao u rng hd1 = 1,25m Chiu cao chn rng hh = 1,25m Trong :d gc prfin rng dao xc Zd s rng dao xc b- Ti tit din AA tit din ny tng ng vi bnh rng dch chnh dng. Lng dch chnhx = +d m. Khong cch khi thy ddtgmtgxa.= =Chiu dy rng trn vng chia Sc= Sc + 2.a.tgb b gc sau li ct bn ti giao im ca mt tr chia vi li ct nm trn mt bn ca dao xc, tgb = tg . tgd =>||

\|+ =d d ctg m S . . 22 Chiu cao rng hd = m(f + c) + a.tg Chiu cao chn rng hd2 = m(f+c)-a.tg Trong f v c l h s chiu cao u rng v khe h hng knh. 12.4.2. Cc gc ct ca rng a- Gc prfin ca rng dao xc Nu tng s rng dao xc ln v cng th dao xc tr thnh thanh rng. 115 Nu dao xc c gc trc v gc sau bng 0 th gc prfin dao xc trong tit din vung gc vi trc dao bng gc prfin ca bnh rng c ct bi dao xc. Vgctrcvgcsaukhc0nncnphixcnhligcprfingiacng ng bnh rng c gc prfin rng l dx. Nu dao xc c 0 th hnh chiu ca li ct ln mt u khng trng vi prfin dao trong tit din vung gc vi trc, hay ni cch khc bin dng rng khi gia cng s khc. Hnh 12.9 Xc nh gc prfin dao xc Ta c ) . 1 ( Ndtg tg hehetg = =M dxtghe = => dxdtg tgtgtg . 1=Vy, ct bnh rng c gc prfin cho l dxth dao xc phi c ch to vi gc prfin trong tit din vung gc vi trc phi l d. ng knh hnh tr rng c s ca dao xc c th c tnh theo cng thc: d0 = ddx.cosd = m.Zd.cosd Trong :ddx- ng knh hnh tr chia ca dao xc. b- Gc ct ca rng dao xc Mi rng ca dao xc c mt li ct nh v hai li ct bn, v vy cn phn bit gc trc v gc sau ti li ct nh v li ct bn. Theo tiu chun, gim sai s prfin th li ct trc gc nh v gc sau nn l d = 50 v d = 60 o trong tit din i qua trc dao. 116 Gcsaulictbncxcnhtigiaoimcahnhtrchiavilict dao xc. 12.4.3. Khong cch khi thy a ca dao xc Tcngthc dtgma .max= ,xc nhkhongcchkhithyacn phixcnh hsdchdaolnnhtcadaoxcdmax.Nuchnaqulnthlmchobrngca nh dao qu hp, do cn chn dmax theo chiu rng nh dao nh nht cho php [Sed]: 0375 , 0 2594 , 0 = m Sed 117 VN 13 NG DNG TIN HC TRONG THIT K V CH TO DNG C CT 13.1.M u Ngynay,vicngdngtinhctrnnphbinchottcccngnhvlnh vc. i vi vic thit k dng c ct th vic ng dng tin hc s gii quyt nhiu vn k thut phc tp cng nh gip cho vic thit k, ch to tr nn linh hot hn. 13.2.M hnh khung dy Mhnhkhungdylmhnhnginnht,baogm:im,ngthng,cung trn,ngcongccthcthtrncchialm2loilngcongphntchv ngcongthp.Ccngcongcngcthbiudinbng2dngphngtrnh ton hc l phng trnh tham s v phng trnh tng minh. u im: -Vic xy dng m hnh kh n gin. -Khng tn nhiu thi gian v b nh tnh ton. Nhc im: -Thi gian chun b d liu u vo l kh nhiu. -M hnh ch nu cc cnh to nn c