T^P CHi KHOA HQC & C6NG NGHp CAC TRl/dNG D^l HQC K* THUAT 4 S6 91 -2012
NGHIEN ctru ANH HirdNC CUA ufc CAT D E N BQ
CHINH XAC GIA C 6 N G T R £ N MAY TlfN MAXXTURN65 RESEARCH THE INFLUENCE OF CUTTING FORCE TO MACHINING ACCURACY ON TURNING MACHINE MAXXTURN65
Li Hieu Giang, Huynh Bd Song Todn Dai hgc Su Phgm Ky Thugt TPHCM Din T6a soan 27-7-20 i 2, chip nh9n dang 21 -9-2012
T6IVI TAT
Trdn thi gi&i dd c6 nhiiu cdng trinh nghidn ciru vi li/c cdt Tuy nhidn nghidn cuv vi dnh hu>img cua lgc cdt din dd chlnh xdc gia cdng trong timg truing hgp cy thS vin cin thiit di tii uv hda chi <X) cdt got. ldng ndng suit gta cdng.
Trdn ca s& liin hdnh cdc thi nghidm do Ig-c, mil lidn h$ giira li/c cdt vd dd chlnh xdc kich thutic duxyc xdc dinh. Di diiu khiin duvc luc cit theo cdc thdng si chi dd cdt (v$n tic cM n. luvng ch^y dao s. chiiu sdu cdt t). cdng thuc llnh li/c cdt dga vdo cdc thdng si ndy duvc xdc dinh theo dang da thiK bdc hai. Muc dd dnh hu&ng ciia cdc thdnh phin Igx; cdt din phirong sal kich thu&c du&ng kinh chl tiit hay dd chlnh xdc diroc du^ ra phdn tich.
ABSTRACT
There are many reaseaches on cutting forces in the wodd; however, researching on the influence of cutting force to machining accuracy Is still necessary for optimizing cutting condition, increasing machining productivity.
Basing on performing mullifactor experiments, the relationship between cutting force and dimension accuracy was specified. To control the cutting force via cutting condition parameters (n, s, t), the formula for calculating cuttting force has been defined in the form of second order polynomial based on three input factors n, s, t Levels of influence of three components of cutting force to vanances of machining dimensions have been analysed.
Keywords: turning, cutting force, design of experiments. ANOVA, Taguchi, regression.
. GIOI T H I f U V A G U THIET
Hinh 1. Cdc thdnh phdn luc cdt [lj.
Tren the g6i da co nliieu c6ng trinh nghien curu ve lire cat, xay dung mo hinh li,rc cat bang nhiSu phuang phap khic nhau [2]-[6]
nhung chua co nhieu cong trinh nghien ciru ve moi lien he giaa do chinh xac gia cong v^ luc
cat tren miy tien miy CNC MAXXTURN65 bang thuc nghiem.
De CO the bifiu diin phuang trinh l\rc <M chju anh huong ciia timg thong s6 (chifiu sSu cat t, lucmg chay dao s va van toe cat n), m^t cdch doc lap, phuang trinh gia thiet can c6 d?ng sau[l],[7].[8]:
5 = ao + ai*Px + ai*Py + a3*Pz 6 : la phuang sai kich thuoc du6ng kinh
Phuang trinh biSu diSn cdc thanh phan cua l\rc cat Px, Py, Pz (hinh I) theo n, s, t c6 dang nhu sau:
Px = 00+ ai(n) + aj(t) + aj(s) + a > t ) + as(ns) + aj(ts) + 0,(0^) + ag(t^) + a^(s^) Fy = po+ |i,(D) + pj(t) + p3(s) + p,(nt) + U^) + P,(ts) + p > ^ ) + P,(t^) + P,(s^)
T^P CHi KHOA HQC & C 6 N G NGHf CAC TRl/dNG D*I HQC KV T H U A T * S 6 91 - 2012
P z = 7 o + Y , ( n ) + Yi(t) + Y3(s) + Y^Cnt) + Ys(ns) + y,(ts) + 7,(n^)+YB(t')+Y9(s')
Trong d6 cdc he s6 a , p , y sS phu thugc vao v§t lieu lam dao, vat lieu gia c6ng, g6c dp dao. Dan vj do luc Id N .
Phuang trinh bSc 2 a tren thfi hifn dnh huong cua su tuong tdc giija cdc thdng so ch£
do cat din luc cat qua tich nt, ns vd st Nghien cim chi xdc dinh sir tuang tdc ciia ba th6ng s6 trong vung khao sdt: n=^300-^900 vg/ph, s=0,12-K),24 mm/ph, 1=0,4-^1,6 mm va xem nhu thong s6 ciia dao la khong d6i trong qud trinh thi nghiem.
2. THi N G H I f M (8]
Tiln hdnh thi nghiem tr€n mdy tifen Maxxtum65. Dung cu cat got Id m i i n g Insert hang ATORN ( C C M T 09T302 - PY HC66I0).
Vat lifu gia cong th^p C45. Phoi hinh tru tr6n 045mm, ddi 50mm, gd kep 20 mm, khong dung dung dich lam ngupl.
Thiet bi thi nghiem la bo dung cu do TelC, phan m i m mo phong XKM.
Chi do do chinh xdc kich thu6c duong kinh chi tifit. Moi tnrong thi nghiem: nhiet do phong 25-30 °C.
Ldn luat tien hanh 16 thi nghiem theo bang b6 tri thi nghiem Taguchi [2,7].
Sau d6 ti€n hanh them 9 thi nghiem, m6i thi nghiem lap lai 5 ldn voi bang bo tri khac de lay s6 lieu ve kich thudc.
,^^
l/inh 3 Kit LJIUI 16 mau ihi ivjjuim
Hinh 4. Ket qud 9 ihi nghiem lap 5 ldn 3. X C LY K E T QUA
Phan tich cdc thong so dnh huang den lire Px nhu sau:
Bdng 1. Tong hgp cdc thdnh phdn dnh hu&ng den lite Px
n t s nt ns ts nn tt SS
558.763 -75.4088 149.1085 225.0003 501.606 -29.5955 471.5992 111.6471 254.3752
-0.31832 443.1813 1214.8 0.2379 -1.2392 2207.6 -0.00025 213.4379 3296.432
0.3238 0.9018 0.2472 0.3933 0.2785 0.9466 0.3126 0.8824 0.2426
Hinh 2. Dung cu do lire cdt trin MaxxTurn
Theo nhu Bdng 1 ta thay he so tuang quan R ciia ts (0.9466) Id 16n nhdt, n h u vdy ts CO anh h u a n g nhieu nhat den luc Px (Hinh 5).
T i l p theo Id he s6 R ciia t (0.9018), t co anh h u a n g ldn thir hai den Px.
m s6 R cua ss(0.2426) vd s(0.2472) nho nhat nSn ss va s co dnh h u a n g thap nhat.
TAP CHI KHOA HQC & CONG NGHf CAC TRITONG DAI HQC Kt" THU^T • S6 91 -2012
Hinh 5. Bieu do quan h^ giua Px, tvds Phdn tich tuang tvr d6i vdi lgc Py ta c6:
Bdng 2. Tong hop cdc thdnh phdn dnh hir&ng den lire Py
n t s nt ns ts nn tt ss
199.5275 209.9088 20.582 210.2792 131.623 155.8552 161.6909 172.312 68.15795
-0.13539 -91.6138 542.85 -0.15331 -0.12341 -208.668 -0.00011 -45.0142 1457.472
0.4996 0.6762 0.4007 0.9193 0.1006 0.3245 0.4739 0.6751 0.3892 Tir Bang 2 co he so tuong quan R cua nt (0.9193^ Id Ion nhat nen nt co anh hudng ldn nhdt din Py. (Hinh 6)
He s6 R ciia t (0.6762) ldn thir hai nen t CO dnh hudng ldn thu hai din Py. Tuy nhien, so vdi muc do anh hudng cua t din Px thi nho han.
He s6 R ciia ns(0.1006) nhd nhdt, tilp theo Id ts(0,3245) n6n ns va ts It co anh hudng den Py nhat.
Hinh 7. Bieu do quan he giira Pz, tvds Phdn tich tuang tir doi vdi lire Pz ta c6:
Bdng 3. Tong hop cdc thdnh phdn dnh hir&ng den lire Pz
•C^^^B^^^^^^^^^^B
n t s nt DS ts nn tt ss
695.0506 91.8625 136.7173 393.0594 595.1097 99.35284 621.4278 280.8871 326.4192
-0.26779 442.5119 2209.206 0.235525 -0.56236 2416.786 -0.00021 211.2394 6045.207
0.2593 0.8571 0.4279 0.3706 0.1203 0.9863 0.2494 0.8313 0.4236
Hinh 6. Bieu do quan he giira Py, nval
He so tuong quan R cua ts (0.9863) la ldn nhdt nen ts co anh huong nhi^u nhit d6n Pz(Hinh7).
Tilp din la he s6 R ciia 1(0.8571) nen t c(3 anh huong Ion thii hai dgn.
He s6 R ciia ns(0.1203) va nn(0.2494) nho nhdt nen anh huong it nhdt din Pz.
Phuong trinh h6i quy da biln cho luc Px, Py va Pz nhu sau:
Px= -285.62-O.lX, + 673.94X2-1- 1951.55X, - 0.42X,Xj - O.eX.Xj +521.46XiX, + 0.0003Xi'-41.34X2M602.34X,' (1)
R'= 0.9981
Py = - 197.5 -I- 0.02X, + 168.32X2 + 3588.68X3-0.15X1X2-1.81X1X3-9O8.88X2X, + 0.0002X,^ - 20.24X2' - 3650X3' (2)
R'= 0.9827
Pz = - 198.72-0.23X, -1-560.49X2-1- 2314.09X3 -0.19X,X2-0.57X,X,+ 1052.31X2X3-1- 0.0003X,'- 101.78Xj'-3216.8Xj' (3)
TAP CHi KHOA HQC & C6NG NGHf CAC TRt/dNG DAI HQC KV THUAT • SO 91 - 2012 R' = 0.9983
Trong do X| Id n, Xj la t va Xj Id s Binh phucmg h$ so tuang quan cua phuang trinh Pz la l&n nhdt 0.9983. tiep theo Id R^ ciia Px la 0.9981 vd nho nhdt la cita Py 0.9827. Cd ba phucmg irinh deu ddng tin cgy.
Dudi day la cac bang phan tich cdc thdnh ph^n lire cat vd phuang sai:
Bdng 4 He sd ttrang quan giua lire Fx vd phuang sai
Regression Statistics Multiple R
R Square Adjusted R Square
Standard Error Observadons
0.879978815 0.774362715 0.742128817 0.000122616
9 Bdng 5 He so tucmg quan giira lire Py va phucmg sai
Regression Statistics Multiple R
R Square Adjusted R Square Standard Error Observations
0.0877546 0.00770087 -0.134056149 0.000257135 9 Bdng 6. He sd lucmg guan giira lire Px vd phuong sai
Recession Stallstlcs Muhiple R
R Square Adjusted R Square Standard Error Observations
0.822824238 0.677039726 0.630902544 0.000146695 9 De nhan thay he so tuang quan cua ba luc vdi phuang sai kich thirdc dgu khac 0 vd cd ddu ducmg, nen co mdi lien he tuyen tinh giu'a ba luc vd phuang sai kich thudc.
He sd tucmg quan cua I*x co gia tri ldn nhit Id 0.879978815 nen lire Px cd dnh hudng ldn nhat. Hf so tuang quan ciia Pz ldn thir hai Id 0.822824238 n6n Pz cd dnh hudng ldn thir hai. Con he sd tucmg quan ciia Py cd gid tri nhd nhdt 0.0877546 (nhd hon he sd ciia Px 10 ldn).
Ta ed phuang trinh hdi quy tuyen tinh ciia phuang sai kich thudc so vdi cdc thdnh phan cua lire cat la:
6 = I0-^*(1127 - 5.2PX- 2Py + 2.4Pz) (4) R^ = 0.83
He sd R^ = 0,83 cd nghia Id phuang trinh hdi quy tuyen tinh gidi thich 83% cdc khdc biet ve dp chinh xdc ddi vdi luc cat.
Bieu do phuang sai va cdc thdnh phan
6 0 0 I - -L-
Hmh 8. Bieu do col phtrong sai vd Px, Py, Pz Hinh 8 cho thdy rang phuang sai nho di hay dp chinh xdc gia cong co xu hudng tang khi Px vd Pz cimg cd xu hudng tang, Gia tri Py khdng anh hudng nhieu d^n phuong sai kich thudc hay dp chinh xac gia cong. Do chinh xac gia cdng cd xu hudng giam tiic phuang sai tang khi Px va Pz ciing giam di.
4. KET LUAN
Bai bdo da trinh bay qud trinh nghien ciru dnh hudng cdc thong sd cong nghe den cdc thdnh phan ciia luc cat va anh hudng ciia luc cat den phuang sai kich thudc hay dp chinh xac gia cdng tren mdy tien MAXXTURN65.
Trong bdi bdo nay, cac phuang trinh thuc nghiem lien quan den cdc thanh phan ciia lire cat vd cdc thdng sd cdng nghe da duac xac dinh theo cdng thirc (1), (2), va (3), Do cd ba phuang trinh nay c6 he sd tuang quan cao nen ket qud la ddng tin cay.
Tir kit q^ua thuc nghiem, phuang trinh thuc nghiem the hien su dnh hudng ciia luc cdt
TAP CHi KHOA HQC & C6NG NGHf CAC TRl/dNG DAI HQC KS! THUAT * S6 91 -2012 din phuang sai kich thudc hay dp chlnh xdc gia nhdt din d^ chinh xdc gia cdng. Khi hai thoi^
cdng cung da dupc xdc djnh theo phuong trinh sd Px vd Pz ciing tdng trong pham vi khdo sdt (4). thi do chlnh xdc gia cdng tang len.
Bilu d6 Hinh 8 cho ta th4y Py khdng dnh Kit qud ndy cd thi dupc sir dung dl tinh hudng nhilu din dO chlnh xdc gia cdng bdng Px todn cdc thdnh phdn cua lgc cdt vd dir bdo do vd Pz; trong dd biln t vd vd Is cd dnh hudng ldn chinh xdc gia cdng khi chpn trudc chl dd gia nhat din Px vd Pz, c6 nghTa Id dnli hudng Idn cdng tren mdy tien MAXXTURN65.
TAI LIEU THAM KHAO
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^ Davim, J. P., "Study of drilling metal-matrix composites based on the Taguchi techniques", J. Materials Processing Technology, Vol. 132, p. 250-254, 2003.
3. Noordin, M.Y. et al., "Application of response surface methodology in describing the performance of coated carbide tools when turning AISI 1045 steel", J. Materials Processing Technology, Vol. 145, p. 46-58, 2004.
4. Polini, W. and Prisco, U., "The estimation of the diameter error in bar turning: a comparison among three cutting force models". Int. J. Advanced Manufacturing Technolo^, VoJ. 22, pp. 465- 474, 2003.
5. Luo, T. et al., "A neural network approach for force and contour error control in multi- dimensional end milling operations", Int. J. Machine Tools and Manufacture, Vol. 38, pp. 1343- 1359, 1998
6. Suresh, P. V. S. , Rao, P.V. and Deshmukh, S. G., "A genetic algorithm approach for optimisation of surface roughness prediction model", Int, J. Machine Tools and Manufacture, Vol.
42, pp. 675-680, 2002.
7. Ross, P., Taguchi Techniques for Quality Engineering, McGraw-Hill, New York, 1988.
8. Huynh Dd Song Toan, Luan vdn thac sT: "Nghien cuu dnh hudng cua luc cat din dp chinh xdc gia cdng tren mdy tien Maxxtum65", DHSPKT-TPHCM, 2012.
Dia chi lien he- Le Hieu Giang - Tel: 0938308141, email: [email protected] Khoa Co khi, Trudng Dai hpc Su pham Ky thuat thanh phd Hd Chi Minh.
