Nghiên cứu tính toán, mô phỏng trường nhiệt độ trong quá trình cắt gọt kim loại bằng phương pháp phần tử hữu hạn

NGHIEN COfU-TRAODOl NGHIEN CUtJ TiNH TOAN, M C PHONG TRl/CJNG NHIET D O TRONG QUA TRINH CAT GOT KIM LOAI BANG PHUONG PHAP PHAN Ttf HUtJ HAN CALCULATION AND SIMULATION OF CUTTING TEMPERATURE FIELD IN METAL CUTTING PROCESS BY FINITE ELEMENT METHOD Nguyin Trpng Hieu, Le Van Tuan, Le Quang Trung Trfldng Dai hpe Bach Khoa Ha Npi Nhiet cat phdt sinh cat ggt kim loai dnh hUdng rdt ldn den tuoi ben cua dung cu cat vd chdt lugng sdn phdm sau gia cong Do vdy, cd nhieu nghien cdu ve nhiet qud trinh cdt ggt kim loai Bdi bdo ndy sd dungphUdngphdp phdn td hdu hgn (FEM) [1,4,5] dUa tren mo hinh phd huy vat lieu Johnson-Cook [2] ciing vdi phdn mem Ansys Autodyn [3] de tinh todn vd mo phong nhiet qud trinh cat ggt kim loai Ket qud mo phong cho thdy phdn bo cua nhiet d vung cat, nhiet cao nhdt tap trung d vung tiep xuc gida phoi vd dung cu cdt Mo phong trUdng nhiet gia cong phay bang phUOng phdp phdn td hdu hgn cho phep dU dodn phdn bo cua trUdng nhiet vd ket qud mo phong ndy phuc vu tot cho viec tinh todn thiet ke dung cu cat, toi Uu hoa qud trinh cat ggt, toi Uu qud trinh boi trdn ldm nguoi Tttkhda: Nhiet cat, ph Udng phdp phdn tdhUu hgn, cat ggt kim logi ABSTRACT The cutting temperature generated in metal cutting process has great influences to tool life and product quality Therefore, there are many researches focusing on cutting temperature in metal cutting process This paper calculates and simulates the cutting temperature in metal cutting process by using the finite element method (FEM) [1,4,5], basing on the Jonhson-Coook [2] material constitutive law with Ansys Autodyn [3] software The simulation result shows the distribution of cutting temperature in cutting area, the highest temperature in the contact area between chip and tool Simulation of cutting temperature field in milling process by using finite element method allows to predict the distribution of cutting temperature field and this result is useful for the calculation and design of cutting tool, optimization of cutting process and optimization of cooling lubrication process Keywords: Cutting temperature, FEM, metal cutting TAP CHf CO KHf VIET NAM V Sd (Thang nam 2013) NGHIEN CUfU-TRAO DOI l.GldlTHlfiU Khi cat kim loai, nang Iflpng cdt d^iac diing de tao phoi va thdng lflc ma sat gifla dung cu va phoi Gan nhfl toan bp nang Iflpng deu chuyen thdnh nhiet, gay n^n nhi^t dp cao d vflng bien dang vd nhflng vung lan can Cd nhieu md hinh dflpc nghien cflu de dfl doan nhiet phdt sinh qud trinh gia cdng Nhflng deu di den thdng nhat cd ngudn nhiet: Nhiet phat sinh qud trinh bien dang deo cua phdi (Q^); nhiet phat sinh ma sdt gifla phoi va mat trfldc dung cu (Q^) vd nhiet phat sinh gifla phdi vd mat sau dung cu (Q^, (hinh 1) gia cdng, phflong phdp dflng hdng ngoai, phflpng phdp flng dung nguyen ly quang hpe, phflpng phdp dung te bdo quang, phflong phdp gidn tiep qua nhiet Iflpng phoi cdt, phflpng phdp luyen kim [1] Tuy nhien, cdc phflpng phdp dd thflOng khdng chinh xdc hodc rat khd dp dung, nhdt Id nghien cflu qua trinh cat gidn doan Gan ddy, vdi sfl phdt trien manh cua cdng nghe thdng tin, phflcfng phap phan tfl hflu ban dd dflpc sfl dung rdng rai de tinh toan vd md phdng hieu qua cdc qua trinh cdt got kim loai PHUONG PHAP PHAN TU" H C U HAN MO PHONG QUA TRiNH C A T GOT KIM LOAI Phflong phap phdn tfl hflu ban la phflpng phap sd rat quan trpng de tinh toan va phdng dodn cdc thdng sd nhfl lflc cat, flng suat, nhiet dp, hinh dang phoi _DJ Phoi A 2.1 Thiet lap md hinh \ Cd ba md hinh chinh dflpc sfl dung viec md phong qua trinh gia cdng cdt gpt bang Hinh Phdn bo cdc viing nhiet qud trinh phflpng phdp phan tfl hflu ban dd la: md hinh Lagrangian, md binb Euler va mo hinh ket hpp cdt ggt kim logi Lagrangian-Eulerian (ALE) [6] Md hinh ALE Id Vung phdt sinh nhiet ldn nhat la tren mat sfl ket hpp cac dac tinh tdi flu cua cdc md hinh trUdc cua dao tiep xflc vdi phoi, nd cung anh rieng biet Lagrangian va Eulerian Trong md hinh hudng nhieu den tudi thp cfla dung cii Khi nhiet ALE, cdc Ifldi phan tfl hflu ban khdng cd dinh dp viing ndy tang len, dung cu gidm ben vd mdn khdng gian vd cung khdng rang bupc vdi nhanh, mdt sd trfldng hpp, cdc phan vat lieu cua phdi Cac Ifldi phdn tfl theo ddng vat vatli^u cua dung cu khuech tdn vdo phoi hodc tac lieu va viec gidi quyet cho van de hfldng di dyng vdi dung djch ldm mat, vdi phoi gay hdng chuyen md hinh Lagragian Mat khac, cdc dyng cu Vl nhiet cat tdng cung vdi toe dp cat, Ifldi phan tfl xac dinh lai vi tri gidi quyet van de d6, nd gidi han tdc dp cdt tdi da cho cdc cap vat van toe md hinh Eulerian li?u dung cu - phdi Nhiet cat tren mat sau cua Md hinh ALE viec md phong cdt gpt dyng cv anh hfldng den bfldc gia cdng tinh vd tdi luy^n be mat, gdy flng suat dfl hoac cd the de lai kim loai sfl dung tiep can Eulerian cho md hinh v-ung xung quay ddu mui dao nPi xdy qud cdc v^t chdy hodc gdy chai cflng be mat gia cdng trinh cat Do dd, sfl bien dang khde liet cdc phan Do Ifldng nhiet cdt rat khd vi nd Id dai tfl dfloc loai trfl md khdng sfl dung tai tao Ifldi lil'jng vd hfldng thay ddi, khdng the dflpc md td Cdch tiep can Lagrangian dflpc sfl dyng cho cdc bdi mpt gid trj nhat tai mot vai diem Cd the ddng vat lieu khdng lien quan d cdc dieu ki?n bien nSu mgt sd phflpng phdp Ifldng nhiet nhfl: tfl Them nfla, su bien dang cua phoi sfl dunjj phflong phdp cap nhiet ngau dpng cu - chi tiet cdc ham bien dang deo cua vat lieu TAP CHf CO KHf VIET NAM Sd4 (Thang4njn NGHIEN CUfU - TRAO Dpi ldm Ifldi bang cdch phan b6 lai cac ndt Dieu ndy giup cung cap tot hdn hinh dang cac phan tfl Ifldi (hmh 4) Dong phoi L Dong Phoi Dong ^ *—- ^ Hinh Bieu kien bien Lagrangian vd Eulerian mo phong ALE 2.2 Chia Ifldi Trong phdn tich phan tfl hflu ban, cdc vung lien tue dflpc chia thdnh cdc vung rieng biet dflpc gpi la cdc phan tfl Thu tue gpi Id rdi rac hoa hodc chia Ifldi Cdc dang Ifldi phan tfl hflu han ban dau khdng the gifl dflpc hinh dang cua nd ma bi bop meo bien dang deo rat ldn qua trinh cat gpt kim loai Nd la nguyen nhan gay cdc loi ve tdc dp hdi tu va so hoc De khac phuc hien tflpng nay, mdt Ifldi phan tfl hflu ban mdi phdi dflpc tao thdnh de thay doi kich thflde va phdn bd lai Ifldi Dieu gpi la phflpng phdp Ifldi thich nghi Mpt ky thuat phflpng phap Ifldi thich nghi la ky thudt tdi tao Ifldi, nd tao mdt Ifldi phan tfl hflu ban hoan todn mdi khdng lien quan den Ifldi meo da ton tai Ky thudt thfl hai la ky thuat lam tinh Ifldi dfla tren viec tang mat dp Ifldi bdng each giam kich cd Ifldi dflpc minh hpa nhfl hinh Hinh Ldm lu6i (a); LUdi ban ddu (b); Phdn bo lgi cdc not Phflong phap Ifldi thich nghi ldm gidm sai sd qud trinh tinh todn vd vay ldm tang dp chinh xdc cua mo phdng 2.3 Md hinh cau triic vat lieu Mdt nhflng van de quan trpng md phong cat gpt kim loai Id viec chpn md hinh ddng flng suat cua vdt lieu phdi mdt each dung ddn de cd ket qua mo phdng chinh xdc Ddng flng suat la gia tri iing suat tflc thdi phu thudc vdo bien dang, ti le bien dang, nhiet dp va dflpc bieu dien bdng cong thflc todn hoc Cd nhieu md hinh md ta van de nhfl md hinh Oxiey, md hinh Zerilli-Armstrong, md hinh Johnson-Cook Trong bdi bao nay, sfl dung md hinh Johnson-Cook Johnson-Cook (1993) da phdt trien mpt md hinh vat lieu dfla tren viec kiem tra sfl xoan va dpng lflc hpe cua mpt Hopkinson mpt ddi rpng nhiet vd bien dang Phflpng trinh cau true vat lieu dflOc viet nhfl sau: a= {A + BE")! Hinh Ldm lUdi (a); LUdi ban ddu (b); Gidm kich thudc phdn td Mdt ky thudt quan trpng nfla la ky thudt H R l TAP CHf CO KHf VIET NAM +Cin—] /T-T, '€) (1) Trong dd: A, B, C, n vd m cdc hang so vat lieu dflpc xdc dinh bdng thflc nghiem; T nhiet tflc thdi; T nhiet dp phdng vd T^ nhiet dp chay cua kim loai dflpc cho Md hinh Johnson-Cook gid thiet rang ddng flng suat bi anh hfldng bdi bien dang, ti le bien dang va nhiet dp 2.4 Mo hinh ma sat Sd (Thang nam 2013) NGHIEN CUfU - TRAO 061 Md hinh ma sdt cd vai trd quan trpng doi 3.2 Mo phong mpt so trfldng hc(p vA cac kit qua cua thong so lUc cdt, nhiet dp, mdn dung cu mo phdng cdt gpt kim loai Vi vdy chpn dfldc md hinh ma sdt tdt giflp bieu dien thflc hem cdc hien tflPng xay Md hinh lflc ma sat cfla Coulomb dflpc sii dung nhieu vd dat dfldc cdc chl tieu dang tin cdy Md hinh lflc ma sat cua Coulomb dili?c sfl dung todn bd vung tiep xuc vdi mdt h^ so ma sat khdng ddi: ; - ^ (2) t = p a^ Hinh Van tdc cdt v^-341m/phut, chieu sdu cat l,=0,5mm, T ^933'K d day: t ling suat ma sat; on iing suat thong thudng va |i he so ma sat MO P H N G VCfl PHAN MEM ANSYS 3.1 Cac biiclc life hanh Qua trinh mo phong ditqc so hoa nhu hinh De thuan tien qua trinh mo phong, phu hpp vcJi kha nang tinh toan cua may tinh, mo hinh CAD duoc thiet lap cho qua trinh cdt dOn gian [7] Dao co goc trUcic a=3°, goc sau Hinh Van tdc cdt v^=401m/phut chieu sdu cdt t=lmm, T =1126'K tzz I IliSl lip m6Ll N I P mi hmh v U Lim C"l V I hmh(CADl||| Ihillljpluoi him Ihl luoi I PhidTiS Thiel Ijp va hien flu Hinh Van tdc cit v=1000m/phut chieu sdu cii t,=lmm, T =J170'K Hinh So qud trinh mo phong vat h?u sti dung cho phoi mo phong 14 thep toi AISI 1045, v6i cac thong so mo hinh lohnson-Cook nhu sau [7]: filing I Cdc Ihong so Jonhson-Cook cua vgt lieu thep AISI 1045 A (Mp.) PS B (Mpa) C n m Tmelt CK) To ("K) 552 0.002 0,457 1.4 1660 293 Hinh Van ldc cit v=W0Om/phut chieu sdu cdt TAP CHl C O KHi VIET N \M • S6 ( T h a n g n a m : i ) l l l ^ Q NGHIEN CUfU - TRAO DpI Nhdn xet: Nhiet cat phdn bo xung quang vung cat, nhiet dp cao nhat d viong tiep xuc gifla dao vd phoi Khi tdc dp cat tang len thi nhiet dp tang theo Tflpng tfl, chieii sdu cat tang, nhiet dp cung tang So sanh ket qua md phdng va so lieu thu dflpc tfl cac thi nghiem vd mot sd nghien cflu khac ta thay cd nhieu diem tflpng dong KET LUAN Sfl dung phflong phdp md phdng de dfl dodn sfl phdn bo nhiet dp qud trinh cdt gpt kim loai la hodn toan khd thi va cd the flng dung tot nghien cflu ve trfldng nhiet dp vd giup gidm chi phi, thdi gian cho viec xdy dflng cdc thi nghiem Nghien cflu phan bo nhiet cat se giup cd nhieu dfl heu cho viec tinh todn thiet ke cdc thdng sd cfla dung cu cat, toi flu hda qua trinh cdt, tdi flu qua trinh bdi trpn lam mat