SCIENCETECHNOLOGYL NGHIEN ClJU ANH Hl/dNG CUA CHE DO CAT DEN DO NHAM BE MAT KHI GIA CONG TREN MAY PHAY CNC INFLUENCES OF CUTTING MODE ON SURFACE ROUGHNESS WHEN PROCESSING BY CNC MILLING MACHINE Nguyen Huy Kien, Pham Van D o n g , Pham Van Bong, Tran Van Dich Tom tat Bai bao trinh bay ket qua nghien ciiu anh hifcmg cua che c3t den nham be mat gia cong tren may phay CNC Ket qua nghien ctiu la cd sd cho cac nha cong nghe lua chgn che cat toi tfu nhim nang cao chat \\Jonq be mat, chi'nh xac va nang suit gia cong gia tong tren may phay CNC Tiikh6a:Ched6cat,d5nham Abstract The article presents influences of cutting mode on surfece roughness when milling by CNC milling machine Tlie research result is the basis for technologists to select optimum cutting mode to raise the surface quality, accuracy and processing capacity of the parts when processing by CNC milling machine Keywords: Cutting mode, roughness ThS Nguyen Huy Kien, TS Pham Vanfl6ng,TS.Pham Van Bong TrutlngDai hgc Cong nghiep Ha Noi GS.TS Tran Van Bich - Trifcmgflaihoc Bach khoa Ha Noi EmaiL nguyenhuykienl981@gmaiLcam 1.DATVANOE Chat luong be mat chi tiet sau gia cong tren may phay CNC phu thupc vao nhieu yeu to, nhU: vat heu gia cong, phaong phap gia cong, dyng cu cat, luc cat, nhiet cat, he thong cong nghe, che cat Khi dieu kien va thiet bi gia cong khong doi, de nang cao nang Ngaynhanbai: 06/01/2014 Ngay chap nhan dang: 20/3/2014 suat, chat lUong be mat chi tiet va chinh xac sau gia cong thi viec lua chpn che cat la het sUc can thiet Cac nghien ciiu da chi moi quan he giCra nham be mat (RJ v6i che dp cat (V, S, t) la quan he ham luy thi/a [4]: R^-Cp.V'.S^t= (1) Trong do: C la hang sd; a, b, c la cac so mu Hang so C^, va cac so mij a, b, c duoc xac djnh bang thuc nghiem Doi vd\ dieu kien gia cong chi tiet cy the thi viec xac djnh cac gia tri C , a, b, c se giup nha cong nghe tinh toan, lUa chon duoc che cat hop ly tiiy theo yeu cau ve chinh xac gia cong THLTC NGHIEM 2.1 Vat lieu va thiet b| thuTc nghiem 2.1.1 Mdy gia cong va dung cu cdt - May gia cong: SCf dung may phay CNC nhan hieu DOOSAN DNM400 (hinh 1) Han Quoc san xuat - Dung cu cat: Dao phay ngon, so rang 1-2, dUdng kinh D - 26 mm, ludi cat gan manh hap kim cLfng nhom cac bit ky hieu 490R-08T308-PM cua hang Sandvik (Thuy Dien) 2.7.2 Vat lieu gia cong va che tudi nguoi ' Vat lieu gia cong la thep 40Cr, thep hoa tot, dUOc sif dyng rong rai che tao may Kich thude mau thi nghiem: 50x30x25 mm - Lam mat: Dung dung djch Emunxy 4%, luu luong 20 lit/phut 2.7.3 Tbiet bi do nhdm - May do nham Mitutoyo SJ - 400 (hinh 2) - Thong so do: chi tieu danh gia nham R^, theo tieu chuan ISO; chieu dai chuan: 0,8 mm, tren ichoang; loai dau kim cuong (R = mm) tiep xuc;aplUcdo:0,75N;t6cdg:0,05mm/s Hinhl.MaypliayDOOSAMDfJM-iOO Hinh May do nham iVIitutoyo SJ - 400 So , TapdiiKHOAHOC&CONGNGHE iaili:^ESc6NGNGHL 2.2 Phuong phap thiTc nghiem Nghien cCru dUOc thuc hien tren 11 mau, vat lieu 40Cr Sau cac mau duoc xac dmh mac thep bang phUOng phap quang pho, tien hanh phay tho, phay ban tmh, kiem tra cac thong so hinh hoc va phay tmh; sii dung phuong phap quy hoach thuc nghiem, chon dang phUOng trinh hoi quy, xac dmh thong so thi nghiem va tien hanh thuc nghiem Do, kiem tra danh gia nham; xay dung cong thiJc xac dinh moi quan he giCra cac thong so che dp cat vdi dp nham be mat chi tiet sau gia cong 2.3 Co sd danh gia so lieu thUc nghiem 2.3.1 Chpn dgngt^wang binh hoi quy De nghien ciJu moi quan he giCa cac thong so che c§t vdi nham be mat chi tiet sau gia cdng, tac gia sCr dung phuong phap binh phaong nho nhat (BPNN) vdi bien sdkvadang ham hoi quy thuc nghiem: Bang - Thong so che cat thifc nghiem Van toe cat V (m/pW 163 212 261 Thong so Gia tri Gia Iri trung binti Gia tri max Toe c3t n Birdc tien dao S (v/ph) (mm/ph) 400 600 800 2000 2600 3200 Ctiieusaucat(mm) 0,1 0,2 0,3 Bang Ket q attiircngliiem Bien ma lida T S 10 11 Ttiongsd cong nghe Tdc cat 0 0 0 1 -1 1 +1 0 (m/ph) (»/ph) 63 61 63 61 63 61 63 61 12 12 12 000 200 000 200 Birdc tien S (mm/ph) 2000 200 000 200 600 600 600 - So thi nghiem duoc xac dinh [3] theo cong thCfc: N = 2" - y-a^j + a^ X| + a^ x^+ + a^X|^ (2) Vdi bien dau vao k - ta co so thi 2.3.2 So thi nghiem va thong so nghiem chinh N - 8, de nang cao thi nghiem chinh xac tac gia them thi nghiem d • So thi nghiem: tam Tong so thi nghiem N - + - 11 - Moi quan he giQa cac t h o n g so * Thong so thi nghiem: duoc mo ta theo so d o (hinh 3): Can cLf vao thong so ky thuat cua may, pham vi cho phep sCf dung cua dung cu cat cua nha san xuat, cac thong so che cSt duoc chon vung sau: 400 400 800 800 400 400 800 300 600 600 600 06 nham Chieu sau cat t theoR, (mm) (pm) 0,1 0,1 0,1 0,1 0,3 0,3 0,3 0,3 0,2 0,2 0,2 0,45 0,53 1.31 0,81 0,42 0,29 1,24 0,57 0,55 0,59 0,60 a^ - c; X, - ln(V); x^ ^ ln(S); x^ = ln(t) Ta duoc: y - a^ + a^x^ + a^x^ + a^j MLTC tren la x"' ta cd: x'" = Inx Mu'c dudi la x"*: x''" = lnx,^j MiJccdsdlax™: , ,10) + lnx,_^) Khoang bien thien ta p, ta co: p, = —(in x,^^,-Inx,^,^) 2.4 Ket qua thiTc nghiem Chuyen cac bien tif tu nhien sang cac bien ma hda khdng thiJ nguydn, + Van toe cat V; 163 - 261 m/ph (n - Vdi thuc nghiem bien dau vao thay 2000-3200 v/ph) doi, tien hanh lam thi nghiem tai cac + Budc tien S: 400 - 800 mm/ph dinh don hinh deu va thi nghiem cl + Chieu sau cat t: 0,1 - 0,3mm tam; sau gia cdng xong cac mau, Hinh So moi qjan he giiJa thong so dau vao Thong sd che dp c§t thUc nghiem tien hanh do nham tren may do va dau nham Mitutoyo SJ - 400 Ket qua thuc the hien bang + Cac bien dau vao x dieu khien Moi quan he giQa nham va che nghiem (bang 2) duoc: dp cat the hien qua cdng thtfc (1), la: 2.4.1 Quy hogch so lieu tht/c nghiem x,:Vant6ccatV(m/ph) R^-Cp.V\S^t= Theo phUdng phap BPNN ta co ham x^: BUdc tien dao S(mm/ph} Logarit co sd e phuong trinh (1) ta hoi quy thiic nghiem tong quat: x^: Chieu sau cat t (mm) y - a g + a, X| +a^Xj+ +W duoc: + Bien dau bi dieu khien: Xac djnh ap,a|,aj a^ cho Sdat ln(R; - In(C^) + a.ln(V) + b.in{S) + y:DpnhambematR^{(jm) c.ln{t) (3) giatn nhd nhat; + Bien khong dieu khien duoc: Bat y ln(R ); a.^ ln(C 1; a, a; a = b; ^: Bien ngau nhien TapdiiKHOAHOC&CONGNGHE S o SCIENCnECHNOLMj Cac gia tri a^, tran [A]: , dj a^ la cac he so tUOng ufng cua ma [A] = a^ - - 4,52911 — C^ - e -*•"'" ^ 0,01079 a, = -0,77396; a^ = 1,20887 -.a^^- 0,28811 Ta c6 phuong trinh hdi quy thuc nghiem: y = - 4,52911 - 0,77396 x, + 1,20887 x2 - 0,2881 IXj (7) Phuong trinh quan he giQa dp nham R^ va cac thdng so che catR^ = , V * ' " « S'rM687_ (-0.28811 Vdi:[X].[A]-[Y] (5) - Ma tran thong so dau vao [X] la logarit co so e cac gia tri V, S, t dung thi nghiem - Ma tran thong so dau [Y] cd cac he so la logarit co sd e cac gia tri dp nham duoc tr^n cac mau thi nghiem Nhan hai ve cua (5) vdi ma tran chuyen vi X"^ cua ma tran X; [Xr.[X].[A]-[Xr.[Y] Bat [M] = [XY [X] ta cd: [M] [A] = [X]^.[Y] (8) 2.4.2 Odnh gid dp tin cay cda ham hoi quy thi/c nghiem • Danh gia tin cay Dp tin cay dUpc danh gia theo [5] cdng thifc: (9) Trong do: a^ Gia SLT det(M) ^ thi [M] la ma tran kha nghich Ta cd: [A] = [M]-'.[xr.[Y] (6) Logarit cd so e cac gia trj V, S, t va R^ ta dUOc ket qua bang TCf bang va phuong trinh hoi quy thUc nghiem (2) ta cd: '1 5.09375 5.99146 5.56452 x„ x,i X, 6.68461 5.56452 6.68461 5.09375 5.99146 -1.20397 1= ^