NGHIEN CUfU - TRAO DOI s/ym DUNG PHU'aNG PHAP T I U U HOA FEEDRATE SLF DUNG PHAN MEM VERICUT DE N DjNH LlfC CAT KHI PHAY CMC APPLICATION OF FEEDRATE OPTIMIZATION METHOD TO STABILIZE CUTTING FORCE IN CNC MILLING BY USING VERICUT SOFTWARE TS Do Tien Lap\ KS Dong Van Kien^ 'Hpc vien Ky thuat Quan sfl ^Tong cue Cong nghiep Quoc phong TOM TAT Bdi bdo trinh bdy nghien ciiu ve van de on dinh lUc cat phay CNC cdc nguyen cdn thien nhiing be mat khdng gian chieu phitc tap bang toi Uu hoa lUdngtien dao (feedrate) Ben c bdi bdo ciing gidi thieu ve viec xay dUng mo hinh vd cdch thiic xdc dinh, khao sdt lUc cat ph Ung dung phUdng phdp tdi Uu hda feedrate Tfl khoa: Tdi Uu hda lUdng tien dao, on dinh lUc cat This paper presents a study of stability of cutting force in the finish milling operations of th 3D complicated free-form surfaces by feedrate optimization Besides that, the article also introdu construction of a measured model and the way of identifying, surveying the cutting force in CNC m when applying feedrate optimization Keywords: Feedrate optimization, stability of cutting force CO s d LY THUYET Thanh phan lflc cat chinh phay cho mpi loai dao phay (trfl dao phay dinh hinh) dflcfc Khi phay hoan thien cac be mat khong tinh theo cong thflc sau [3]: gian chieu phflc tEip, lflc cat thay doi la mpt nhflng nguyen nhan chinh gay hien tflpng rung />,= Cp^.B"".t^''^.S^".D~''".Z.n^f'.Kp2 (N) (1) dpng anh hfldng den dp chinh xac gia cong (do md rpng vung dung sai), sinh song be mat, Trong : P^ - Thanh phan lflc tiep tuyen nhap nho be mat va lam cho dung cu nhanh mon (hay gpi la lflc vong) Lflc la Iflc cat chinh B6i vay, viec on dinh lflc cat phay (lflc cat toi CP^ - he s6 dieu chinh anh hfldng cua tinh flu) la het sflc can thiet, mang lai nhieu lpi ich ve ky thuat va kinh te chat ca ly cua nhom vat lieu gia cong t6i lflc P^ !> I Q TAP CHI CO KHi VIET NAM, S6 12 nam 2013 NGHIEN CIJfU-TRAODOl KP^ - h^ so dieu chinh anh hflcfng cua cac yeu to lai kh6ng co mat cong thflc (vat lieu gia cong, thong so hinh hpc phan cat cua dung cu ) tcfi lflc cat P B - chi^u rpng phay; n - so vong quay cua dao, vong/ph; S^ - Iflpng chay dao rang, mm/rang; D - dfldng kinh dao phay; Z - so rang dao phay; t„ - chieu sau cat Sfl phu thupc cua P^ vao cac yeu to tren cung khac nhau, Cu the: the hien sfl thay doi cua chieu sau cat t qua trmh phay tinh cac be mat dinh hmh Hinh Su thay ddi cua chieu sau cat t - Lflc cat tang gan nhfl ti le thuan vdi chieu rpng phay B va s6 rang dao Z Khi chieu sau cat t^ thay doi, cac yeu to khac la D, B va Z cung thay ddi theo Cu the, dfldng kinh D thflc te ciia dao cau phay tinh ti - Lflc cat P^ phu thupc vao t^ theo quan he le thuan vdi chieu sau cat t^, chieu sau cat Idn thi gSn nhfl tuyen tinh (vdi dao phay mat dau xp = dfldng kinh thflc te cua dao tham gia cat cung Idn va ngflpc lai (hinh 2) D ma tang thi sd rang dao 1,1 ~ 1.14) Z cung tham gia cit se giam cdn chieu rpng B lai - Lflpng chay dao rang S^ tang thi lflc cat se tang (hinh 3) tang Tuy nhien, mflc dp tang cua P^ cham hdn S^ (yp = 0,65 ~ 0,8) - Anh hfldng cua so vong quay n den lflc cit khdng Idn lam (Wp = ~ 0,2) - Tang dfldng kinh dao D thi lflc cat P^ se gidm vi dfldng kinh dao tang thi s6 rang d6ng thdi tham gia cat se giam Trong cac yeu to tren thi toe dp true chinh n anh hfldng khdng dang ke tdi lflc cat; Cp va Kp la cac he so Vay, lflc cat P^ chi phia thupc chu yeu Vtio cac y^u to cdn l^i la t^, D, B, Z va S^ Cac yeu to n^y thay d6i se lam cho lflc cat bien doi theo Doi vdi qua trinh phay, sfl thay doi cua cac y^u to tren diln nhfl sau: + Chieu sau c^t t^: Day la yeu to thay doi liSn tuc qua trinh phay Iflpng dfl gia cdng khdng deu nhau, d§c biet la d cac gdc Iflpn phay tinh va ban tinh cac be mat khdng gian chi^u phflc tap B6n c?nh dd, be mat cua ban san ph^m sau phay thd bang dao phay tru cung khdng tron deu ma cd dang bac thang Hinh Hinh Su thay doi ciia dudng kinh dao cat theo chiiu sau cat t„ Hinh SUphu thuoc ciia chiiu rdng phay B vdo dUdng kinh dao D Nhfl vay, cd the ndi rang P^ la mpt ham cua t„ va S : '^ TAP CHf CO KHf V I £ T NAM Sd 12 nam 2013 NGHIEN cflu - TRAO edi P, = f ( V S ) (2) + Md h m h the tich, feedrate ti le vdi ca toe dp bdc tach vat Ueu (MRR) tflc thdi va trung binh + Lilong chay dao rang S^: Vi Ivfcing chay dao phut S ^ (feedrate) co y nghia thtfc te hdn + Md hinh vector lflc, feedrate nen ta se nghien ciiu stf thay doi cua S ^ thay vi S^ dflpc thiet lap mpt gia tri de gifl cho lflc cat trung thong qua cong thiic sau : binh va lflc cat tflc thdi theo mot gia tri mong (3) mudn Til (2) va (3) suy ra: (4) Theo (4), n6u f = constant thi P^ se thay doi theo ty Dieu thfldng xay thflc te phay phay CNC theo chflcfng trinh NC dflpc sinh bdi mot phan mem CAD/CAM thdng thfldng hoac dflpc lap trinh bang tay Ndi each khac, de P^ khong ddi thi feedrate phai thay doi de bu lai sfl thay ddi t^^ gay Feedrate thay doi theo chieu sau cat de tri Ifl cat khdng doi gpi la feedrate toi flu Vay, bien phap de on dinh lflc c&t chinh la sfl dung toi flu hda feedrate VAN DE TOI UtJ HOA FEEDRATE Tdi flu hda feedrate da dflpc nghien cflu nhieu nhflng viec ap dung nd vao thflc te san xuat tai cac xfldng gia cdng co la vd cung khd khan Trfldc cdng nghe CNC ddi thi dieu gan nhfl la khdng the thflc hien dflpc Ngay ca cdng nghe CNC da phat trien thi viec gia cdng vdi feedrate toi flu cung rat han che Cac chflpng trinh NC lap trinh bang tay hay dflpc tao tfl cac phan mem CAM thong thfldng deu co feedrate = constant Mac du nd cd the thay doi dflpc qua trinh gia cong nhd sfl dieu chinh trflc tiep cua cac thp dflng may Nhflng hieu qua cua sfl thay doi khdng cao vi nd khdng kip thdi va phu thupc nhieu vao tay nghe cua ngfldi thp Trong khoang 10 nam trd lai day, vdi sfl ddi va phat trien manh me cua cac phan mem CAM cao cap nhfl Vericut, Master CAM, Dellcam Powermill viec toi flu hda feedrate da dt dang hpn De xac dinh feedrate toi flu ta dfla vao hai md hinh sau [7,8]: Trong md hinh tren, mo hinh vector lflc cd dp chinh xac cao nhflng cung khd thflc hien hpn Bdi vay hau het cac nghien cflu va cac phan mem tdi flu hda deu dflpc tien hanh dfla tren m6 hinh the tich Viec ap dung toi flu hda feedrate vao thflc te san xuat cd the thflc hien theo hai phflpng phap: + Toi flu hda trflc tiep (on-line optimization); Feedrate dflpc tinh toan va dieu chinh trflc t i ^ qua trinh gia cdng theo dieu kien cat d tflng thdi diem cu the thdng qua bp dieu khien thich nghi (Adaptive Controller) cai dat cung vdi may CNC [4,5,8]: + Tdi flu hda gian tiep (off-line optimization): Feedrate dflpc xac dinh trfldc va ghi vao chfldng trinh NC de chay may Viec tinh toan feedrate ti^n hanh theo md hinh nhfl da ndi d tren Ngay nay, no dflpc thflc hien nhd nhflng phan mem CAM cao cap Mdt nhflng phan mem la Vericut Trong hai phfldng phap thi phflpng phap toi flu hda on-line khd thflc hien hon vi chi phi ton kem, lap dat va hieu chinh phflc tap Hfln nfla, viec xac dinh feedrate toi flu khdng phdi bao gid CLuig kip thdi, chinh xac Bdi vay, phfldng phip toi flu hda gian dflpc flng dung thdng qua viec sfl dung modul Optipath cua phan mem Vericut Modul OptiPath se tfl dpng thay doi gia tri feedrate cho phu hpp tai mdi thdi diim cat khac thay vi gia tri feedrate khdng doi chfldng trinh NC sfl dung phan mem CAM thong thfldng Toi flu hda feedrate cho phep giim thdi gian gia cdng thflc, keo dai tuoi thp Ifldi ck, tranh pha huy diing cu va chi tiet, tang dp chinh xac giam dp lech dung cy va nang cao chat Iflpng be mat nhd on dinh dflpc lflc cat TAP CHf C O KHf VIET NAM, Sd 12 nam 2013 NGHIEN C I A J - TRAO D6i M O HiNH VA CAC K f T KHAO SAT LU'C CAT 3.1 Md hinh khao sat lijc cat - Thiet bi lflc cat Cd nhieu phflpng phap de xac dinh lflc cat nhfl phflpng phap trflc tiep, phflpng phap xac dinh thdng qua cdng suat cat, phfldng phap bing va hiiu do, .Mpt nhiing phfldng phap phd bi^n nhat hien la trflc tiep bang lflc k^ ban dang ap dien (nhfl cua hang Kistler) Tuy nhien, gia cua nd rat cao khdng phu hpp vdi dilu kien kinh te cua nfldc ta Vi vay, viec xac dinh lflc cat dfldc thflc hien bang thiet bi cam bien lflc chieu sfl dung tern bien dang Thiet hi lflc da dflpc Vien Ten Lfla - Trung tam Khoa hpc Cdng nghe Quan sfl thiet ke, che tao cdng va da dfla vao sfl dung nhieu nghien cflu Sd dd nguyen ly cua he thong lflc dflpc the hien tren hinh THlfiTBIDOLVC Dao phay Lire tac dcing Chi tiet gia cong Phan tu-dan hoi Bieo dang Tem dien tra Thay doi dien ' tro Thietbi hieo tlii (may tinh) B o tbu nhan v a chuyen doi tin hieu Dien ap da duoc KD Khuyech dai Dien ap cku Wheatstone Hinh Sd nguyen ly he thdng lUc chieu phay - May phay CNC: Trung tam gia cdng VMC-1060 - Dung cu cat: Dao phay cau 010 - Chi tiet gia cdng: Cdi dap udn - Vat lieu chi tiet gia cdng: Thep 45 Bp p h | n quan trpng nhat thiet bi lflc chinh la phan tfl dan hdi (phan tfl bien dang) Dfla tren nhflng tham khao ve phan tfl bien dang tfl cac tai li$u va ngoai nfldc md hinh phan tfl bien dang theo nguyen ly dam udn cd cau true va vi tri ddn tem nhfl nhfl hinh da dflpc xay dflng Md hinh khao sat lflc thflc te dflpc lap dat nhfl tren hinh Hinh Kit cdu phdn tU biin dang vd vf tri ddn tem Hinh So lap ddt he thong lUc phay TAP CHf CO KHi V I £ T NAM Sd 12 nam 2013 NGHIEN CtfU-TRAO DOI 3.2 Ket qua khao sat lflc cat Trong nghien cflu nay, tien hanh phay hoan thien hai chi tiet gidng nhfl tren hinh bang hai phflpng phap, mdt cd sfl dung va mdt khdng sfl dung bien phap on dmh lflc cat Hinh Chi tiit coi dap udn Ket qua khao sat dflpc chi cac bieu sau (hinh 8, 9): ypmm^^ -~— Hinh Biiu lUc cat theo cdc phUdng x,y,z phay cd sU dungphUdngphdp Sn dinh lUccat Nhan xet: + Gia tri lflc cat c^c dai tdi flu hda nhfi hdn so vdi chfla toi flu + Gia tri lflc cat cflc tieu tdi flu hoa Idn hdn so vdi tdi flu hda nhflng lflc cat trung binh thi lai nhd hpn , + Khi tdi flu hda, lflc cat on dinh hdn nhieu so vdi chfla toi flu Dieu cd thi thJy qua hinh dang cua bieu cung nhfl la gid Iri Hinh Biiu lUc cat theo cdc phUdng x,y,z phay min, max cua lflc cat khdng sii dungphUdngphdp on dinh lUc cat TAP C H i C O KHf VIET NAM, Sd 12 nam 2013 NGHIEN CUfU-TRAODOl - Ket qua dp nham tren san pham: De kiem tra danh gia anh hfldng cua viec on dinh lflc cat din dp nham chi tiet gia cdng, ta tien hanh dp nham d vi tri I, II, III nhfl da chi tren hinh tren hai mau (Mau gia cdng bdng chfldng trinh NC chfla tdi flu hda feedrate, mau gia cdng bdng chfldng trmh cd tdi flu hda feedrate) Ket qua dflpc chi bang 1: Bdng Kit qud do nhdm tren cdc m&u gia cong Ket qua ^ ^ — ^ " " " ^ — ^ Vitri Mdu MSu2 Ra (tim) Rz(nm) Ra (jira) RzCum) I 1,35 6,2 1,13 5,2 II 1,96 7,6 1,76 7,3 III 1,56 6,9 1,2 5,1 Nhan xet: Tai ca vi tri do, mau dflpc gia cdng vdi chfldng trinh NC cd tdi flu hda feedrate (Mau 2) deu cd Ra va Rz nhd hdn so vdi mau gia cdng vdi chflpng trinh NC chfla tdi flu hda Ket qua hoan toan phu hpp vdi ly thuyet KET L U A N Bai bao da phan tich anh hfldng cua viec khdng on dinh lflc cat den chat Iflpng gia cdng De tao sfl on dinh lflc cat cd nhieu phfldng phap, dd cd phfldng phap tdi flu hoa Iflpng tien dao (feedrate) Viec tdi flu hda Iflpng tien dao dflpc thflc hien tren cd sd flng dung phan mem Vericut Trong bdi cung da trinh bay md hinh khao sat lflc cdt phay CNC sfl dung thiet hi lflc lflc chieu sfl dung tem bi^n d^ng Ddng thdi danh gia chat Iflpng gia cdng (d day la dp nham be mat) thong qua viec ki^m tra mau gia cdng Cd th^ khang dinh: - On dinh lflc cat phay CNC bang tdi flu hda feedrate rat hieu qua - Chdt Iflpng be mat gia cong dfldc cai thien dang ke Qua ket qua nghien cflu nay, cd the khang dinh viec flng dung phan mem Vericut vao gia cdng phay CNC vdi cac b^ mat cd bien dang phflc tap mang lai hieu qua kinh te va ky thuat Idn, dac biet thflc hien vdi cdc nguyen cdng gia cdng tinh • Ngay nhan bai: 03/11/2013 Ngdy phan bien: 05/12/2013 Ngfldi phan bi^n: TS Lai Anh Tuan nguyen Chu nhiem Bd mdn Che tao may, Khoa Co khi, Hpc vi^n Ky thuat Quan sfl Tdi li^u tham khao: [ 1) Phan Ba, Dao Mpng Lara (2001) Do lUdng -Senxd NXB QDND |21 Nguyen DSc L^c (2007), So tay Cong nghe che tao mdy CKp I, II), NXB Khoa hgc va Ky thuat Ha Noi 131 Vu Hifu Nam, LUu Van B6ng, NguySn Van Hoii L91 Anh Tuan, Diiong Quoc Dung (2002), Cong nghe Kim loai phdn !!: Gia cong cat g(ft, Hpc vi§n Ky thuJt Quan sU, Hk N$i \4].EyupBa^cH20\l),'Momtormgand analysis of mrr-based feedrate optimization approach and epcts of culthigconditions using a^^^^^ Stic sound pressure level in free-form surface milling" Scientific Research and Essays, Voi 6(2), pp 256-277 (5] Franc Cus, Joze Balic (2010), "combined system for off-line optimization and adaptive cutting force control" Journal of Machine Engj neenng Vol 10, (No 2) f u T [6], H Erdim, I Lazoglu', B Ozturk (2006), "feedrate scheduling strategies far free-form surfaces" International [ournai of Machine Tools fit Manufacture 46 Page 747-757 [7) M Sedighi & M Noorani Azad (2008) "classification of the feed-rate optimization techniques a case study m mimmizing cue machining lime" lUST International Journal of Engineering Science, Vol 19, (Na5-I) Page 83-87 18] Robert B Jerard Barry K Fussell Mustafa T Ercan (2001) 'onlme optimization of cutting conditions for nc machining 2001 NSF Design, Manufacturing & Industrial Innovation Research Conference, (Jan 7-10,2001) TAP CHi CO KHf VIET NAM Sd 12 nam 2013 ... thfldng xay thflc te phay phay CNC theo chflcfng trinh NC dflpc sinh bdi mot phan mem CAD/CAM thdng thfldng hoac dflpc lap trinh bang tay Ndi each khac, de P^ khong ddi thi feedrate phai thay doi... t^^ gay Feedrate thay doi theo chieu sau cat de tri Ifl cat khdng doi gpi la feedrate toi flu Vay, bien phap de on dinh lflc c&t chinh la sfl dung toi flu hda feedrate VAN DE TOI UtJ HOA FEEDRATE. .. dai Dien ap cku Wheatstone Hinh Sd nguyen ly he thdng lUc chieu phay - May phay CNC: Trung tam gia cdng VMC-1060 - Dung cu cat: Dao phay cau 010 - Chi tiet gia cdng: Cdi dap udn - Vat lieu chi tiet