Chng 2: THIT K QUY TRNH CNG NGH GIA CNG CHI TIT.7Hnh anh so be mat chi tiet4.1/ Chn chun gia cng chi tit :Mcchchnchun:chnchunrtquantrngtrongvicthitkquy trnh cng ngh, chn chun hp l cn tha mn 2 yu cu sau:- m bo cht lng ca chi tit trong sut qu trnh gia cng.- m bo nng sut cao, gi thnh h.T 2 nguyn tt trn ta c cc phng php chn chun sau:Khi chn chun phi sut pht t nguyn tt 6 im nh v chi tit khng chhtsbctdocnthitcachititmtcchhplnhttuyti trnh thiu v siu nh v, trong mt strng hp cn trnh tha nh v khng cn thit.518624 3Chnchunsaochokhngblcct,lckplmbindngchititqu nhiu, ng thi lc kp phi nh gim bt sc lao ng cho ngi cng nhn.Chn chun sao cho kt cu g phi n gin, s dng thun li nht v thch hp vi tng loi hnh sn xut.4.1a/ Chon chun th:Chnchunthcnghaquytnhnquytrnhcngngh,nnh hng n cc nguyn cng sau v chnh xc ti cc chi tit gia cng.4.1b Yu cu khi chn chun th:m bo chnh xc v v tr tng quan gia cc b mt gia cng v b mt khng gia cng.m bo phn b lng d cho cc b mt s gia cng.4.1c Cn ch khi chn chun th:Theo mt phng kch thc nht nh, nu trn kch thc gia cng c mt b mt gia cng, th nn chn b mt lm chun th.Theomtphngkchthcnhtnh,nutrnchititgiacngcmt haynhiubmtgiacng,thnnchnbmtnocyucuv chnh xc tng quan so vi b mt gia cng l cao nht lm chun th.Theomtphng kch thc nht nh, nu trn chi tit gia cngc tt c cc b mt gia cng th ta nn chn b mt phi no c yu cu lng d nh v ng u nht lm chun th.ngvimt bctdocnthitthchcphpchnv sdngchun th khng qu mt ln, nu mt ny l mt chun th. Nu phm chun th s gy nn v tr tng quan gia cc b mt gia cng vi nhau. 4.2a / Chon chun tinh:Yu cu khi chn chun tinh:m bo phn b lng d cho cc b mt gia cng.mbochnhxcvvtrtngquangiaccbmtgiacngvi nhau.Nguyn tt khi chn chun tinh:C gng chn chun tinh l chun tinh chnh, nu nh vy th chi tit c v tr khi gia cng ging nh khi lm vic, chnh xc t c mt cch trc tipnnddnghn,ngthinginhaqutrnhlprpvphi gia cng thm cc chun tinh ph.C gn chn chun tinh sao cho tnh trng chun cng cao cng tt. Nu nh vy s gim sai s gia cng v khi chun c s trng vi chun khi sut th sai s chun cc=0.C gn chn chun tinh thng nht cho c qu trnh gia cng. Nu nh vy th chng loi ca g s gim bt. Do gim bt c chi ph thit k, tnh ton v ch to g nn gi thnh gim. 4.3/ CC PHNG N GIA CNG CHI TIT:4.3.1/ phng n 1: - Nguyn cng 1:Phay kha mt u v khoan l tm .- Nguyn cng 2: Mt u kp vo mm cp, mt u chng tm.tin th mt tr |60, |65, |75- Nguyn cng 3: Mt u kp vo mm cp, mt u chng tm.Tin th mt tr |60, |80.Nguyn cng 4: chng tm 2 u.Tin bn tinh cc mt tr |60, |65, |75,|80Nguyn cng 5: chng tm 2 u.Mt tr B lm chunVt mp mt 1, mt 7: 2x450Tin tinh mt cc mt tr |60, |65, |75, |80- Nguyn cng 6: phay rnh then.- Nguyn cng 7: nhit luynNguyn cng 8: mi c trcC trc |60, |65, |75Nguyn cng 9: tng kim tra4.3.2/ phng n 2: - Nguyn cng 1: Mt tr B lm chun.Tin mt u v khoan l tm 1.- Nguyn cng 2: Mt tr B lm chuntin th mt 2, mt 3, mt 4, mt 5, hoc ( |60, |65, |75, |80)- Nguyn cng 3: Mt tr A lm chun.Vat mt, khoan l tm 7.- Nguyn cng 4: Mt tr A lm chun.Tin th mt 6 : |60Nguyn cng 5: phay mt 8: rnh then.Nguyn cng 6: Mt tr A lm chun.Vt mp 2x450 Tin tinh mt tr 7, mt tr 2, hoc ( |60, |80 )Nguyn cng 7:Mt tr B lm chunVt mp 2x450Tin tinh cc b mt tr |60, |65, |75Nguyn cng 7: mi th C trc |60, |65 Nguyn cng 8: mi tinhC trc |60, |654.3.2/ phng n 3: - Nguyn cng 1:Tin kha mt u v khoan l tm .- Nguyn cng 2: chng tm2 u.tin th |60, |65, |75, |80- Nguyn cng 3: chng tm2 u.Tin th: |60, |65- Nguyn cng 4: phay mt 8: rnh then.- Nguyn cng 5: chng tm2 u.Vt mp 2x450Tin tinh mt tr 7, mt tr 2, hoc ( |60, |80 )Nguyn cng 6: Chng tm2 u. Vt mp 2x450Tin tinh :|60, |65, |75Nguyn cng 7: mi th C trc |60, |65, |75 Nguyn cng 8: mi tinhC trc: |60, |65, |754.4) PHN TCH CC NGUYN CNG:phng n 1:u im l phn tn nguyn cng u ph hp vi sn xut hng khi, hp vi quy trnh cng ngh, gim s ln g t, nh v chi tit, nn m bo song song, vung gc, ng tm, nn bng, chnh cao.phng n 2:Mt nhiu thi gian g t, nh v, nn lm sai s v kch thc, ng tm cho chi tit. V vy khng ph hp vi sn xut hng khi.phng n 3:Chng tm 2 u trong gia cng th m bo chnh xc, thch hp cho sn xut hng hng khi, nhng chiu su ct th thp, nu chiu su ct t ln s khng m bo cng vng, dn n sai s cho sn phm, nn d gy ra ph phm.Kt lun: V th ta chn phng n 1 lp quy trnh cng ngh gia cng chi tit.4.5) LP QUY TRNH CNG NGH GIA CNG CHI TIT:Vic lp quy trnh cng ngh gia cng chi tit phi hp l nht, rt ngn thi gian phc v v thi m bo nng sut hiu qu kinh t cao. ng thi vic sp xp cc nguyn cng hp l s trnh c hin tng gia cng c nhng phi b ph phm nguyn cng trc.Khi thit k phi da vo 2 nguyn tt sau:Cn c vo trng thi cui cng ca b mt gia cng lp phng n th t hp l nht.C gn b tr cc nguyn cng d hy ph phm ln trc, tr trnh thi gian gia cng phi ph phm. lp quy trnh cng ngh gia cng chi tit, trc tin ta phi xt cc yu cu k thut, t a ra bin php cng ngh gia cng.1) Nguyn cng 1:Kha mt u v khoan l tm. +nhv:chitietcnhvtrn2khivngnnhv4bctdo, ngoi ra chng s dch chuyn theo chiu dc trc ta dng mt cht ty nh v bc t do th 5.+ Kep chat: nh hnh v.+ Chon may: ta chn my gia cng l my phay c k hiu MP-71M c cc thng s sau:ng knh gia cng 25 125 mm.Chiu di chi tit gia cng 200 500 mm.Gii hn chy ca dao phay 20 400 mm/ph.S cp tc ca dao phay: 6Gii hn s vng quay ca dao khoan 20 300 mm/ph.Cng sut ca ng c phay khoan: 7.5 2.2 kw.Cc bc cng ngh:Bc 1: phay th mt u.+ Chon dao: Dao phay mt u T15K6, c cc thng s D = 80(mm); z = 5 rngGia cng rnh then ta chn chiu su ct t =2mm.Bng 5-153 ta chn bc tin dao Sz =0,12mm/rng.Lng chy dao vng S0 = 0,12. 5 =0,6 mm/vngPhi c: B =60mmBng 5-154 ta chn tc ct Vb = 33,5 m/phH s hiu chnh:He so phu thuoc vao o cng cua chi tiet gia cong K1=0,86He so phu thuoc vao chiu su ct t:K2=0,88He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao dung dch trn ngui: K4=1 Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =33,5. 0,86. 0,88 .1. =25,4 m/phut.So vong quay cua truc chnh theo tnh toan la: 10180 . 14 , 34 , 25 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 475 vong/phut. Nh vay, toc o cat thc te se la: 3 , 1191000475 . 80 . 14 , 31000.= = =MttDnV (m/phut).Lc ct gt:KPn DZ B S t CPp pp p pqu YzXpz... . . .=(kg)Trong : Cv = 825; Xp =1; Yp = 0,75; up = 1,1;2 , 0 =p ; qp =1,3( sch ch ct gia cng c kh bng 3 5)Theo bng(12-1)77 , 07532753 , 0 3 , 0=|.|
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\|= =bm ppK KThay vo cng thc:= =2 . 0 3 , 11 , 1 75 , 0 1475 . 20130 . 12 , 0 . 2 . 825zP 211 kg PZ < [P]M = 360 kg m bo iu kin lm vic an ton.Cng sut ct gt:KWV PNtt Zcg1 , 460 . 1023 , 119 . 21160 . 102.= = =Ncg < NM. m bo cng sut ct gt.Thi gian gia cng th:04 , 04754 12 5 , 22 10=+ +=+ +=MthSL L LTpht5 , 22165 1702===d DL mm12 2 ) 20 20 20 .( 5 , 02 21= + = Lmm) 6 1 (2 = L mm; chn L2 = 4 mmBc 2: Phay tinh:Chieu sau cat t= 0,5mm; Bc tin: Stb =0,25 (bng 5-125 STCNCTM tp 2)Chn SM =0,2 mm/vng.Bng 5-153 ta chn bc tin dao Sz =0,12mm/rng.Lng chy dao vng S0 = 0,12. 5 =0,6 mm/vngPhi c: B =60mmBng 5-154 ta chn tc ct Vb = 33,5 m/phH s hiu chnh:He so phu thuoc vao o cng cua chi tiet gia cong K1=0,86He so phu thuoc vao chiu su ct t:K2=0,88He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao dung dch trn ngui: K4=1 Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =33,5. 0,86. 0,88 .1. =25,4 m/phut.So vong quay cua truc chnh theo tnh toan la: 10180 . 14 , 34 , 25 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 600 vong/phut. Nh vay, toc o cat thc te se la: 7 , 1501000600 . 80 . 14 , 31000.= = =MttDnV (m/phut).Lc ct gt:KPn DZ B S t CPp pp p pqu YzXpz... . . .=(kg)Trong : Cv = 825; Xp =1; Yp = 0,75; up = 1,1;2 , 0 =p ; qp =1,3( sch ch ct gia cng c kh bng 3 5)Theo bng(12-1)77 , 07532753 , 0 3 , 0=|.|
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\|= =bm ppK KThay vo cng thc:1 , 7600 . 8060 . 12 , 0 . 5 , 0 . 8252 . 0 3 , 11 , 1 75 , 0 1= =zP(kg) PZ < [P]M = 360 (kg); m bo iu kin lm vic an ton.Cng sut ct gt:KWV PNtt Zcg2 , 060 . 1027 , 150 . 1 , 760 . 102.= = =Ncg < NM. m bo cng sut ct gt.Thi gian gia cng tinh:07 , 06004 5 , 15 5 , 22 10=+ +=+ +=MtinhSL L LTpht5 , 22165 1702===d DL mm5 , 15 2 ) 60 80 80 .( 5 , 02 21= + = Lmm) 6 1 (2 = L mm; chn L2 = 4 mmBc 3: khoan tmChn mi khoan tm la mi khoan ui tr lm bng vt liu T15K6, c cc kch thc nh sau: D = 5mm; L = 132mm; l = 87mm_Chieu sau cat t= 2,5mm.Bc tin: Stb = 0,2Chn SM =0,2 mm/vng._Toc o cat Vb=55 m/phut.( 5-86, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=0,9H s ph thuc vo chiu su l K2 = 0,7He so phu thuoc vao tuoi ben cua dao K3=1 H s ph thuc vo chu k bn ca dao K4 = 1Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =55. 0,9. 0,7 .1.1 =34,65 m/phut.So vong quay cua truc chnh theo tnh toan la: 22075 . 14 , 365 , 34 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1200 vong/phut. Nh vay, toc o cat thc te se la: 8 , 1810001200 . 5 . 14 , 3= =ttV(m/phut).Lc ct gt:PZ = CPZ . tXPZ . SYPZ . VNZ . KPZTrong : CPZ = 300; xpz =1; ypz = 0,75; nz = -0,15( sch ch ct gia cng c kh bng 11 1)H s hiu chnh:KPZ =KMP . K PZ . K PZ .K PZ .KrPZTrong:KMP =1; K PZ =0,94; K PZ =1; K PZ = 1; KrPZ =0,93 KPZ =1. 0,94 . 1 . 1 . 0,93 = 0,87 PZ =300 . 2,51 .0,20,75 . 18,8-0,15 .0,87 = 125,6 kg. PZ < [P]M = 350 kg m bo iu kin lm vic an ton.Cng sut ct gt:KWV PNtt Zcg4 , 060 . 1028 , 18 . 6 , 12560 . 102.= = =Ncg < NM. m bo cng sut ct gt.Thi gian gia cng:14 , 01200 . 2 , 044 , 3 30.10=+=+=Mn SL LTphtmm g L 44 , 3 2 60 cot .2501= + =2) Nguyn cng 2: tin th: 60, 65, 75S1S2S3S4S5S6S7600.05650.05750.02460.05310.051090.1+ nh v: chi tiet c nh v trn mt u trn mm cp v mt u chng tm nh v 5 bc t do, m bo cng vng khi gia cng.+ Kep chat: nh hnh v.+ Chon may: ta chn my gia cng l my tin c k hiu 1K62 c cc thng s sau:Chiu cao ca tm:200mmKhong cch gia 2 tm n 1400mmTit din ln nht ca dao tin( mm) 2550Lc ko ln nht ca c cu chy dao (N) :Dao dc: 3600Dao ngang 5500Cng sut ng c: N = 10 kwHiu sut my n= 0,75ng knh l sut trc chnh 45mmLc cho php PZ =360 kgCc bc cng ngh:Bc 1: tin th60 Kch thc cn t1 , 0 68 ; l= 46mm+ Chon dao: chn dao tin ngoi thn cong c gc nghing 900, vt liu T15K6, theo bng 5 -11 STCNCTM tp 2 ta chn kch thc dao nh sau H = 16(mm); B = 25; L = 100; 060 = ; r = 0,5+ Che o cat: Chieu sau cat t=1,5mm.Bc tin: Stb =0,54 (bng 5-64 STCNCTM tp 2)Chn SM =0,5 mm/vng._Toc o cat Vb=144 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92 Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =144. 1. 1 .1. 0,92 =132,5 m/phut.So vong quay cua truc chnh theo tnh toan la: 3 , 70360 . 14 , 35 , 132 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1000 vong/phut. Nh vay, toc o cat thc te se la: 4 , 18810001000 . 60 . 14 , 31000.= = =MttDnV (m/phut).Lc ct gt:PZ = CPZ . tXPZ . SYPZ . VNZ . KPZTrong : CPZ = 300; xpz =1; ypz = 0,75; nz = -0,15( sch ch ct gia cng c kh bng 11 1)H s hiu chnh:KPZ =KMP . K PZ . K PZ .K PZ .KrPZTrong:KMP =1; K PZ =0,94; K PZ =1; K PZ = 1; KrPZ =0,93 KPZ =1. 0,94 . 1 . 1 . 0,93 = 0,87 PZ =300 . 1,51 .0,50,75 . 188,4-0,15 .0,87 = 106 kg. PZ < [P]M = 360 kg m bo iu kin lm vic an ton.Cng sut ct gt:KWV PNtt Zcg26 , 360 . 1024 , 188 . 10660 . 102.= = =Ncg < NM. m bo cng sut ct gt.Thi gian gia cng th:264 , 01000 . 5 , 087 , 2 46.2 10=+=+ +=Mthn SL L LTpht87 , 2 2605 , 101= + =tgL mm02 = LBc 2: tin th65 Kch thc cn t1 , 0 70 + Che o cat: Chieu sau cat t=1,5mm.Bc tin: Stb =0,54 (bng 5-64 STCNCTM tp 2)Chn SM =0,5 mm/vng._Toc o cat Vb=144 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92 Vay toc o cat tnh toan la Vt:Vt=Vb.K1 .K2 .K3 . K4 =144. 1. 1 .1. 0,92 =303,6 m/phut.So vong quay cua truc chnh theo tnh toan la: 64965 . 14 , 35 , 132 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1000 vong/phut. Nh vay, toc o cat thc te se la: 20410001000 . 65 . 14 , 31000.= = =MttDnV (m/phut).Lc ct gt:PZ = CPZ . tXPZ . SYPZ . VNZ . KPZTrong : CPZ = 300; xpz =1; ypz = 0,75; nz = -0,15( sch ch ct gia cng c kh bng 11 1)H s hiu chnh:KPZ =KMP . K PZ . K PZ .K PZ .KrPZTrong:KMP =1; K PZ =0,94; K PZ =1; K PZ = 1; KrPZ =0,93 KPZ=1. 0,94 . 1 . 1 . 0,93 = 0,87 PZ =300 . 1,51 .0,50,75 . 204-0,15 .0,87 = 104,8 kg. PZ < [P]M = 360 kg m bo iu kin lm vic an ton.Cng sut ct gt:KWV PNtt Zcg5 , 360 . 102204 . 8 , 10460 . 102.= = =Ncg < NM. m bo cng sut ct gt.Thi gian gia cng th:07 , 01000 . 5 , 087 , 2 31.2 10=+=+ +=Mthn SL L LTpht87 , 2 2605 , 101= + =tgL mm02 = LBc 3: tin th75 Kch thc cn t1 , 0 80 + Che o cat: Chieu sau cat t=1,5mm.Bc tin: Stb =0,54 (bng 5-64 STCNCTM tp 2)Chn SM =0,5 mm/vng._Toc o cat Vb=144 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92 Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 = 144. 1. 1 .1. 0,92 =132,5 m/phut.So vong quay cua truc chnh theo tnh toan la: 6 , 56275 . 14 , 35 , 132 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1000 vong/phut. Nh vay, toc o cat thc te se la: 5 , 23510001000 . 75 . 14 , 31000.= = =MttDnV (m/phut).Lc ct gt:PZ = CPZ . tXPZ . SYPZ . VNZ . KPZTrong : CPZ = 300; xpz =1; ypz = 0,75; nz = -0,15( sch ch ct gia cng c kh bng 11 1)H s hiu chnh:KPZ =KMP . K PZ . K PZ .K PZ .KrPZTrong:KMP =1; K PZ =0,94; K PZ =1; K PZ = 1; KrPZ =0,93 KPZ =1. 0,94 . 1 . 1 . 0,93 = 0,87 PZ =300 . 1,51 .0,50,75 . 235,5-0,15 .0,87 = 102,6 kg. PZ < [P]M = 360 kg m bo iu kin lm vic an ton.Cng sut ct gt:KWV PNtt Zcg95 , 360 . 1025 , 235 . 6 , 10260 . 102.= = =Ncg < NM. m bo cng sut ct gt.Thi gian gia cng th:23 , 01000 . 5 , 087 , 2 109.2 10=+=+ +=Mthn SL L LTpht87 , 2 2605 , 101= + =tgL mm02 = LNguyn cng 3: tin th:80 , 60 + nh v: chi tiet c nh v trn mm cp, 1 u chng tm nh v 5 bc t do.+ Kep chat: nh hnh v.+ Chon may: ta chn my gia cng l my tin c k hiu 1K62 c cc thng s sau:Chiu cao ca tm:200mmKhong cch gia 2 tm n 1400mmTit din ln nht ca dao tin( mm) 2550Lc ko ln nht ca c cu chy dao (N) :Dao dc: 3600Dao ngang 5500Cng sut ng c: N = 10 kwHiu sut my n= 0,75ng knh l sut trc chnh 45mm608046Lc cho php PZ =360 kgCn mooc s 5.Cc bc cng ngh:Bc 1: tin th: 60Gia cng th phn trc c ng knh60 ; di 46mmKch thc cn t1 , 0 68 + Chon dao: chn dao tin ngoi thn cong c gc nghing 900, vt liu T15K6, theo bng 5 -11 STCNCTM tp 2 ta chn kch thc dao nh sau H = 16(mm); B = 25; L = 100; 060 = ; r = 0,5+ Che o cat: Chieu sau cat t=1,5mm.Bc tin: Stb =0,54 (bng 5-64 STCNCTM tp 2)Chn SM =0,5 mm/vng._Toc o cat Vb=144 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92 Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =144. 1. 1 .1. 0,92 =132,5 m/phut.So vong quay cua truc chnh theo tnh toan la: 70360 . 14 , 35 , 132 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1000 vong/phut. Nh vay, toc o cat thc te se la: 4 , 18810001000 . 60 . 14 , 31000.= = =MttDnV (m/phut).Lc ct gt:PZ = CPZ . tXPZ . SYPZ . VNZ . KPZTrong : CPZ = 300; xpz =1; ypz = 0,75; nz = -0,15( sch ch ct gia cng c kh bng 11 1)H s hiu chnh:KPZ =KMP . K PZ . K PZ .K PZ .KrPZTrong:KMP =1; K PZ =0,94; K PZ =1; K PZ = 1; KrPZ =0,93 KPZ =1. 0,94 . 1 . 1 . 0,93 = 0,87 PZ =300 . 1,51 .0,50,75 . 188,4-0,15 .0,87 = 106 kg. PZ < [P]M = 360 kg m bo iu kin lm vic an ton.Cng sut ct gt:KWV PNtt Zcg26 , 360 . 1024 , 188 . 10660 . 102.= = =Ncg < NM. m bo cng sut ct gt.Thi gian gia cng th:63 , 01000 . 5 , 087 , 2 46.2 10=+=+ +=Mthn SL L LTpht87 , 2 2605 , 101= + =tgL mm02 = LBc 2: tin th:80 Gia cng th phn trc c ng knh80 ; di 29mmKch thc cn t1 , 0 82 + Che o cat: Chieu sau cat t=1,5mm.Bc tin: Stb =0,54 (bng 5-64 STCNCTM tp 2)Chn SM =0,5 mm/vng._Toc o cat Vb=144 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92 Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2.K3 . K4 =144. 1. 1 .1. 0,92 =132,5 m/phut.So vong quay cua truc chnh theo tnh toan la: 5 , 52780 . 14 , 35 , 132 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1000 vong/phut. Nh vay, toc o cat thc te se la: 2 , 25110001000 . 80 . 14 , 31000.= = =MttDnV (m/phut).Lc ct gt:PZ = CPZ . tXPZ . SYPZ . VNZ . KPZTrong : CPZ = 300; xpz =1; ypz = 0,75; nz = -0,15( sch ch ct gia cng c kh bng 11 1)H s hiu chnh:KPZ =KMP . K PZ . K PZ .K PZ .KrPZTrong:KMP =1; K PZ =0,94; K PZ =1; K PZ = 1; KrPZ =0,93 KPZ =1. 0,94 . 1 . 1 . 0,93 = 0,87 PZ =300 . 1,51 .0,50,75 . 251,2-0,15 .0,87 = 101 kg. PZ < [P]M = 360 kg m bo iu kin lm vic an ton.Cng sut ct gt:KWV PNtt Zcg2 , 460 . 1022 , 251 . 10160 . 102.= = =Ncg < NM. m bo cng sut ct gt.Thi gian gia cng th:064 , 01000 . 5 , 087 , 2 29.2 10=+=+ +=Mthn SL L LTpht87 , 2 2605 , 101= + =tgL mm02 = LNguyn cng 4: tin bn tinh: 60, 65, 75.Bc 1: tin bn tinh: 60 Gia cng tinh phn trc c ng knh60 ; di 46mm Kch thc cn t05 , 0 5 , 60 + Chon dao: chn dao tin ngoi thn cong c gc nghing 900, vt liu T15K6, theo bng 5 -11 STCNCTM tp 2 ta chn kch thc dao nh sau H = 16(mm); B = 25; L = 100; 060 = ; r = 2,0+ Che o cat: Chieu sau cat t = 0,8 mm.Bc tin: Stb = 1,2 mm/vng (bng 5-64 STCNCTM tp 2)Chn SM =0,7 mm/vng._Toc o cat Vb= 182 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =182 . 1. 1 .1. 0,92 =167,4 m/phut.6065754631109 So vong quay cua truc chnh theo tnh toan la: 5 , 88860 . 14 , 34 , 167 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1250 vong/phut. Nh vay, toc o cat thc te se la: 5 , 23510001250 . 60 . 14 , 31000.= = =MttDnV (m/phut).Thi gian gia cng bn tinh:06 , 01250 . 7 , 046 , 2 46.2 10=+=+ +=Mtinhn SL L LTpht46 , 2 2608 , 00 1= + =tgL mm02 = LBc 2: tin bn tinh: 80 Gia cng tinh phn trc c ng knh80 ; l =29mmKch thc cn t05 , 0 5 , 81 + Chon dao: chn dao tin ngoi thn cong c gc nghing 900, vt liu T15K6, theo bng 5 -11 STCNCTM tp 2 ta chn kch thc dao nh sau H = 16(mm); B = 25; L = 100; 060 = ; r = 0,5+ Che o cat: Chieu sau cat t = 0,8 mm.Bc tin: Stb = 1,2 mm/vng (bng 5-64 STCNCTM tp 2)Chn SM =0,7 mm/vng._Toc o cat Vb= 182 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =182 . 1. 1 .1. 0,92 =167,4 m/phut. So vong quay cua truc chnh theo tnh toan la: 4 , 66680 . 14 , 34 , 167 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1250 vong/phut. Nh vay, toc o cat thc te se la: 31410001250 . 80 . 14 , 31000.= = =MttDnV (m/phut).Thi gian gia cng bn tinh:035 , 01250 . 7 , 046 , 2 29.2 10=+=+ +=Mtinhn SL L LTpht46 , 2 2608 , 00 1= + =tgL mm02 = LBc 3: tin bn tinh: 60 Gia cng tinh phn trc c ng knh60 ; di 46mm Kch thc cn t05 , 0 5 , 62 + Chon dao: chn dao tin ngoi thn cong c gc nghing 900, vt liu T15K6, theo bng 5 -11 STCNCTM tp 2 ta chn kch thc dao nh sau H = 16(mm); B = 25; L = 100; 060 = ; r = 2,0+ Che o cat: Chieu sau cat t = 0,8 mm.Bc tin: Stb = 1,27 mm/vng (bng 5-64 STCNCTM tp 2)Chn SM =0,7 mm/vng._Toc o cat Vb= 182 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =182 . 1. 1 .1. 0,92 =167,4 m/phut. So vong quay cua truc chnh theo tnh toan la: 5 , 88860 . 14 , 34 , 167 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1250 vong/phut. Nh vay, toc o cat thc te se la: 5 , 23510001250 . 60 . 14 , 31000.= = =MttDnV (m/phut).Thi gian gia cng bn tinh:06 , 01250 . 7 , 046 , 2 46.2 10=+=+ +=Mtinhn SL L LTpht46 , 2 2608 , 00 1= + =tgL mm02 = LBc 4: tin bn tinh: 65Gia cng tinh phn trc c ng knh60 ; di 31mm Kch thc cn t05 , 0 5 , 67 + Che o cat: Chieu sau cat t=0,8mm.Bc tin: Stb =1,2 mm/vng (bng 5-64 STCNCTM tp 2)Chn SM = 0,7 mm/vng._Toc o cat Vb= 182 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92Vay toc o cat tnh toan la Vt :Vt=Vb .K1 .K2 .K3 . K4 = 182. 1. 1 .1. 0,92 =167,4 m/phut. So vong quay cua truc chnh theo tnh toan la: 82065 . 14 , 34 , 167 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1250 vong/phut. Nh vay, toc o cat thc te se la: 25510001250 . 65 . 14 , 31000.= = =MttDnV (m/phut).Thi gian gia cng bn tinh:038 , 01250 . 7 , 046 , 2 31.2 10=+=+ +=Mthn SL L LTpht46 , 2 2608 , 00 1= + =tgL mm02 = LBc 5: tin bn tinh: 75Gia cng tinh phn trc c ng knh60 ; l =31mm Kch thc cn t05 , 0 5 , 77 + Che o cat: Chieu sau cat t=0,8mm.Bc tin: Stb =1,2 mm/vng (bng 5-64 STCNCTM tp 2)Chn SM =0,7 mm/vng. Toc o cat Vb=182 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92 Vay toc o cat tnh toan la Vt :Vt=Vb .K1 .K2 .K3 . K4 =182. 1. 1 .1. 0,92 = 167,4 m/phut.So vong quay cua truc chnh theo tnh toan la: 71075 . 14 , 34 , 167 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1250 vong/phut. Nh vay, toc o cat thc te se la: 29410001250 . 75 . 14 , 31000.= = =MttDnV (m/phut).Lc ct gt:PZ = CPZ . tXPZ . SYPZ . VNZ . KPZTrong : CPZ = 300; xpz =1; ypz = 0,75; nz = -0,15( sch ch ct gia cng c kh bng 11 1)H s hiu chnh:KPZ =KMP . K PZ . K PZ .K PZ .KrPZTrong:KMP =1; K PZ =0,94; K PZ =1; K PZ = 1; KrPZ =0,93 KPZ =1. 0,94 . 1 . 1 . 0,93 = 0,87 PZ =300 . 0,81 .0,70,75 . 294-0,15 .0,87 = 68 kg. PZ < [P]M = 360 kg m bo iu kin lm vic an ton.Cng sut ct gt:KWV PNtt Zcg2 , 360 . 102294 . 3 , 6760 . 102.= = =Ncg < NM. m bo cng sut ct gt.Thi gian gia cng bn tinh:127 , 01250 . 7 , 046 , 2 109.2 10=+=+ +=Mthn SL L LT pht46 , 2 2608 , 00 1= + =tgL mm02 = LNguyn cng 5: tin tinh: 60, 65, 75.Bc 1: tin tinh: 60 Gia cng tinh phn trc c ng knh60 ; di 46mm Kch thc cn t05 , 0 5 , 60 + Chon dao: chn dao tin ngoi thn cong c gc nghing 900, vt liu T15K6, theo bng 5 -11 STCNCTM tp 2 ta chn kch thc dao nh sau H = 16(mm); B = 25; L = 100; 060 = ; r = 2+ Che o cat: Chieu sau cat t=0,5mm.Bc tin: Stb =0,25 mm/vng (bng 5-64 STCNCTM tp 2)Chn SM =0,21 mm/vng._Toc o cat Vb=231 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =231. 1. 1 .1. 0,92 = 212,5 m/phut. So vong quay cua truc chnh theo tnh toan la: 112860 . 14 , 35 , 212 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1250 vong/phut. Nh vay, toc o cat thc te se la: 5 , 23510001250 . 60 . 14 , 31000.= = =MttDnV (m/phut).Thi gian gia cng tinh:18 , 01250 . 21 , 029 , 2 46.2 10=+=+ +=Mtinhn SL L LTpht29 , 2 2605 , 00 1= + =tgL mm02 = LBc 2: tin tinh: 80 Gia cng tinh phn trc c ng knh80 ; l =29mmKch thc cn t05 , 0 5 , 80 + Che o cat: Chieu sau cat t=0,5mm.Bc tin: Stb =0,25 mm/vng (bng 5-64 STCNCTM tp 2)Chn SM =0,21 mm/vng._Toc o cat Vb=231 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =231. 1. 1 .1. 0,92 =212,5 m/phut. So vong quay cua truc chnh theo tnh toan la: 84680 . 14 , 35 , 212 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1250 vong/phut. Nh vay, toc o cat thc te se la: 31410001250 . 80 . 14 , 31000.= = =MttDnV (m/phut).Thi gian gia cng tinh:002 , 01250 . 21 , 029 , 2 29.2 10=+=+ +=Mtinhn SL L LTpht29 , 2 2605 , 10 1= + =tgL mm02 = LBc 3: tin tinh: 60 Gia cng tinh phn trc c ng knh60 ; di 46mmKch thc cn t05 , 0 5 , 60 + Chon dao: chn dao tin ngoi thn cong c gc nghing 900, vt liu T15K6, theo bng 5 -11 STCNCTM tp 2 ta chn kch thc dao nh sau H = 16(mm); B = 25; L = 100; 060 = ; r = 2+ Che o cat: Chieu sau cat t=0,5mm.Bc tin: Stb =0,25 mm/vng (bng 5-64 STCNCTM tp 2)Chn SM =0,21 mm/vng._Toc o cat Vb=231 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =231. 1. 1 .1. 0,92 =212,5 m/phut. So vong quay cua truc chnh theo tnh toan la: 112860 . 14 , 35 , 212 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1250 vong/phut. Nh vay, toc o cat thc te se la: 5 , 23510001250 . 60 . 14 , 31000.= = =MttDnV (m/phut).Thi gian gia cng tinh:18 , 01250 . 21 , 029 , 2 46.2 10=+=+ +=Mtinhn SL L LTpht18 , 2 2605 , 10 1= + =tgL mm02 = LBc 4: tin tinh: 65Gia cng tinh phn trc c ng knh60 ; di 31mm Kch thc cn t05 , 0 5 , 65 + Che o cat: Chieu sau cat t=0,5mm.Bc tin: Stb =0,25 mm/vng (bng 5-64 STCNCTM tp 2)Chn SM =0,21 mm/vng._Toc o cat Vb=231 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92Vay toc o cat tnh toan la Vt :Vt=Vb .K1 .K2 .K3 . K4 =231. 1. 1 .1. 0,92 =212,5 m/phut. So vong quay cua truc chnh theo tnh toan la: 104165 . 14 , 35 , 212 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 1250 vong/phut. Nh vay, toc o cat thc te se la: 25510001250 . 65 . 14 , 31000.= = =MttDnV (m/phut).Thi gian gia cng tinh:13 , 01250 . 21 , 029 , 2 31.2 10=+=+ +=Mthn SL L LTpht29 , 2 2605 , 10 1= + =tgL mm02 = LBc 3: tin tinh: 75Gia cng tinh phn trc c ng knh60 ; l =31mm Kch thc cn t05 , 0 5 , 75 + Che o cat: Chieu sau cat t=0,5mm.Bc tin: Stb =0,25 mm/vng (bng 5-64 STCNCTM tp 2)Chn SM =0,21 mm/vng. Toc o cat Vb=231 m/phut.(bang 5-64, so tay CNCTM tap 2)He so phu thuoc vao o cng cua chi tiet gia cong K1=1He so phu thuoc vao trang thai be matgia cong K2=1He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao gc nging chnh : K4=0,92 Vay toc o cat tnh toan la Vt :Vt=Vb .K1 .K2 .K3 . K4 =231. 1. 1 .1. 0,92 = 212,5 m/phut.So vong quay cua truc chnh theo tnh toan la: 3 , 90275 . 14 , 35 , 212 . 1000.. 1000= = =DVn(vong/phut). Ta chon so vong quay theo may nm= 1250 vong/phut. Nh vay, toc o cat thc te se la: 29410001250 . 75 . 14 , 31000.= = =MttDnV (m/phut).Lc ct gt:PZ = CPZ . tXPZ . SYPZ . VNZ . KPZTrong : CPZ = 300; xpz =1; ypz = 0,75; nz = -0,15( sch ch ct gia cng c kh bng 11 1)H s hiu chnh:KPZ =KMP . K PZ . K PZ .K PZ .KrPZTrong:KMP =1; K PZ =0,94; K PZ =1; K PZ = 1; KrPZ =0,93 KPZ =1. 0,94 . 1 . 1 . 0,93 = 0,87 PZ =300 . 0,51 .0,210,75 . 294-0,15 .0,87 = 17,3 kg. PZ < [P]M = 360 kg m bo iu kin lm vic an ton.Cng sut ct gt:KWV PNtt Zcg83 , 060 . 102294 . 3 , 1760 . 102.= = =Ncg < NM. m bo cng sut ct gt.Thi gian gia cng tinh:42 , 01250 . 21 , 029 , 2 109.2 10=+=+ +=Mthn SL L LTpht29 , 2 2605 , 10 1= + =tgL mm02 = LNguyn cng 6:phay rnh then: l =100 mm; d = 20mm- nh v: chi tit gia cng c nh v trn 2 khi V ngn, nh v 4 bc t do, ngoi ra chng s dch chuyn theo chiu dc trc, ta dng mt cht nh v bc t do th 5.- Chn my phay: My c k hiu 6H13- B mt lm vic ca bn my 400 x1600 mm2- Cng sut ca ng c 10 KW- Hiu sut ca my 0,75- Lc ln nht cho php theo c cu tin ca my 200 KG- S vng quay cua trc chnh(v/ph): 30-37, 5-4, 75-60-75-95-118-150-190-235-300-375-475-600-753-950-1180-1500.- Bc tin ca bn my(mm/ph ): 23-30-37-47-60-75-95-120-150-190-240-300-370-470-600-750-1200.Cc bc cng ngh:Kch thc cn t: 20x100x11Chn dng c ct:Ta chn dao phay ngn ui tr c kch thc nh sau:D =20 mm ; B = 20 mm; L = 100mm ; Z = 5 rng.Ch ct:Gia cng rnh then ta chn chiu su ct t =2mm.Bng 5-153 ta chn bc tin dao Sz =0,12mm/rng.Lng chay dao vng S0 = 0,12. 5 =0,6 mm/vngPhi c B =20mmBng 5-154 ta chn tc ct Vb = 33,5 m/phH s hiu chnh:He so phu thuoc vao o cng cua chi tiet gia cong K1=0,86He so phu thuoc vao chiu su ct t:K2=0,88He so phu thuoc vao tuoi ben cua dao K3=1He so phu thuoc vao dung dch trn ngui: K4=1 Vay toc o cat tnh toan la Vt:Vt=Vb .K1 .K2 .K3 . K4 =33,5. 0,86. 0,88 .1. =25,4 m/phut.So vong quay cua truc chnh theo tnh toan la: 5 , 40420 . 14 , 34 , 25 . 1000.. 1000= = =DVn (vong/phut). Ta chon so vong quay theo may nm= 475 vong/phut. Nh vay, toc o cat thc te se la: 83 , 291000475 . 20 . 14 , 31000.= = =MttDnV (m/phut).Lc ct gt:KPn DZ B S t CPp pp p pqu YzXpz... . . .=(kg)Trong : Cv = 825; Xp =1; Yp = 0,75; up = 1,1;2 , 0 =p ; qp =1,3( sch ch ct gia cng c kh bng 3 5)Theo bng(12-1)77 , 07532753 , 0 3 , 0=|.|
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\|= =bm ppK KThay vo cng thc:kg Pz53475 . 2020 . 12 , 0 . 2 . 8252 . 0 3 , 11 , 1 75 , 0 1= = PZ < [P]M = 360 kg m bo iu kin lm vic an ton.Cng sut ct gt:KWV PNtt Zcg2 , 060 . 10283 , 29 . 5360 . 102.= = =Ncg < NM. m bo cng sut ct gt.Thi gian gia cng th:24 , 04754 12 1002 10=+ +=+ +=MthSL L LTpht12 2 ) 20 20 20 .( 5 , 02 21= + = Lmm) 6 1 (2 = L mm; chn L2 = 4 mmNguyn cng 7: nhit luyn cng sau khi nhit luyn tHB 260 210 Chn phng n ti ramTi nung nng chi tit n 0840gi trong0 6 'Ram cao v nung nng chi tit T0 =6400 . Sau gi nhit v lm ngui trong khng kh.Nguyn cng 8: mi c trc 75 , 65 , 60 - Chi tit c nh v trn 2 mi tm mm. Mi tm trc khng ch 2 bc t do, mi tm sau khng ch 2 bc t do. Mi tm sau c th di chuyn dc trc mt cch d dng nh mt l xo tho lp chi tit c thun tin.- Kp cht: chi tit c kp ct bng lc dc trc ca 2 mi chng tm trc v sau.- Chn my mi 2A130 c cng sut ng c trc chnh l:Nc = 4 KW. S cp tc mm cp trc: v cp. ng knh ln nht ca mi 350 mm. Tc mi 1880; 2110 (v/ph)Chn dng c o: dng PanmeChn ch gia cng:Mi c trc :Tnh vn tc :) / (60 . 1000. .ph mn Dvdd=D: ng knh : chn D = 250 mmn : s vng quay ca chn n =1880 v/ph ) / ( 6 , 2460 . 10001880 . 250 . 14 , 3ph m vd= =Tnh vn tc (m/ph) v s vng quay ca chi tit:(Tra bng 3-9 sch ch ct gia cng c kh), chn Vct = 20 m/phTnh s vng quay ca trc chnh:) / ( 10660 . 14 , 320 . 1000.. 1000ph vgd vn = = =Chn n = 200 v/phTnh vn tc ct thc t: ) / ( 68 , 371000200 . 60 . 14 , 31000. .ph mn dv = = = Tnh chn bc tin dao ngang Sm (mm/ph)Chu trnh bng tay: ly theo cng thc trong STGCCSm = Sm(b) K1 .K2 .K3Trong : K1 : h s ph thuc vo vt liu gia cng.K2 : h s ph thuc vo tui bn dng c.K3 : h s ph thuc vo t s chiu di ct vi dng knh.Tra bng 2.196 ta tra c Sm(b) = 0,6 (m/ph) vi ng knh miD = 250 (mm) >160 v b rng mi b = 19 (mm)Tra bng 2.198 STGCC c K1 = 1,1 vi vn t v = 24,6 (m/ph)Tra bng 2.199 STGCC c : K2 = 0,7 vi vn t chnh xc gia cng l o = 0,01 (mm) v lng d mt bn a = 0,25 (mm)Tra bng 2.200 STGCC c K3 =0,8 do ng knh D =250 (mm), tnh cht b mt gia cng l trn v s lng l 1.Nh vy thay vo cng thc ta c: Sm =Sm(b) . K1 .K2 .K3 = 0,6 .1,1 .0,7 .0,8 = 0,4 (mm/ph)Xc nh thi gian sa tinh tt (pht) tra bng 2.201.B rng mi b = 19 mm ng knh c trc d = 75 mm, chnh xc gia cng o
