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 do c3t den do nham be mat khi gia cong tren may phay CNC. Ket qua nghien ctiu la cd sd cho cac nha cong nghe lua chgn che do cat toi tfu nhim nang cao chat \\Jonq be mat, do chi'nh xac va nang suit gia cong khi 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 Van fl6ng,TS. Pham Van Bong TrutlngDai hgc Cong nghiep Ha Noi
GS.TS. Tran Van Bich - Trifcmg flai hoc Bach khoa Ha Noi EmaiL nguyenhuykienl981@gmaiLcam
Ngaynhanbai: 06/01/2014 Ngay chap nhan dang: 20/3/2014
1.DATVANOE
Chat luong be mat chi tiet sau khi 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 do cat... Khi dieu kien va thiet bi gia cong khong doi, de nang cao nang
suat, chat lUong be mat chi tiet va do chinh xac sau khi gia cong thi viec lua chpn che do cat la het sUc can thiet.
Cac nghien ciiu da chi ra moi quan he giCra do 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 do cat hop ly tiiy theo yeu cau ve do chinh xac gia cong.
2. 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) do 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 3 cac bit ky hieu 490R-08T308-PM cua hang Sandvik (Thuy Dien).
2.7.2. Vat lieu gia cong va che do tudi nguoi
' Vat lieu gia cong la thep 40Cr, thep hoa tot, dUOc sif dyng rong rai trong 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 do nhdm - May do do nham Mitutoyo SJ - 400 (hinh 2).
- Thong so do: chi tieu danh gia do nham R^, theo tieu chuan ISO; chieu dai chuan: 0,8 mm, do tren 5 ichoang; loai dau do. kim cuong (R = 2 mm) do tiep xuc;aplUcdo:0,75N;t6cdg:0,05mm/s.
Hinhl.MaypliayDOOSAMDfJM-iOO Hinh 2 May do do nham iVIitutoyo SJ - 400
iaili:^ESc6NGNGHL
2.2. Phuong phap thiTc nghiem Nghien cCru dUOc thuc hien tren 11 mau, vat lieu 40Cr. Sau khi 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 do 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 khi 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 do c§t vdi do 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:
y-a^j + a^ X| + a^ x^+ + a^X|^ (2) 2.3.2. So thi nghiem va thong so thi nghiem
• So thi nghiem:
- Moi quan he giQa cac t h o n g so duoc mo ta theo so d o (hinh 3):
Bang 1 - Thong so che do cat thifc nghiem
Hinh 3. So do moi qjan he giiJa thong so dau vao va dau ra
+ Cac bien dau vao x dieu khien duoc:
x , : V a n t 6 c c a t V ( m / p h ) x^: BUdc tien dao S(mm/ph}
x^: Chieu sau cat t (mm) + Bien dau ra bi dieu khien:
y : D p n h a m b e m a t R ^ { ( j m ) + Bien khong dieu khien duoc:
^: Bien ngau nhien
Thong so Gia tri min Gia Iri trung binti
Gia tri max
Van toe cat V (m/pW
163 212 261
Toe do c3t n (v/ph) 2000 2600 3200
Birdc tien dao S (mm/ph)
400 600 800
Ctiieusaucat(mm) 0,1 0,2 0,3 Bang 2. Ket q
T 1 2 3 4 S 6 7 8 9 10 11
attiircngliiem Bien ma lida
0 0 0
0 0 0
1 1 -1 1 1 1 +1 1 0 0 0
Ttiongsd cong nghe Tdc do cat
(m/ph) 63 61 63 61 63 61 63 61 12 12 12
(»/ph) 000 200 000 200 2000 200 000 200 600 600 600
Birdc tien S (mm/ph) 400 400 800 800 400 400 800 300 600 600 600
Chieu sau cat t (mm)
0,1 0,1 0,1 0,1 0,3 0,3 0,3 0,3 0,2 0,2 0,2
06 nham theoR, (pm) 0,45 0,53 1.31 0,81 0,42 0,29 1,24 0,57 0,55 0,59 0,60 - So thi nghiem duoc xac dinh [3]
theo cong thCfc:
N = 2" - 8
Vdi bien dau vao k - 3 ta co so thi nghiem chinh N - 8, de nang cao do chinh xac tac gia them 3 thi nghiem d tam. Tong so thi nghiem N - 8 + 3 - 11
* Thong so thi nghiem:
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 do cSt duoc chon trong vung sau:
+ Van toe cat V; 163 - 261 m/ph (n - 2000-3200 v/ph).
+ Budc tien S: 400 - 800 mm/ph.
+ Chieu sau cat t: 0,1 - 0,3mm.
Thong sd che dp c§t thUc nghiem the hien trong bang 1.
Moi quan he giQa do nham va che dp cat the hien qua cdng thtfc (1), do la:
R^-Cp.V\S^t=
Logarit co sd e phuong trinh (1) ta duoc:
ln(R; - In(C^) + a.ln(V) + b.in{S) +
c.ln{t) (3) Bat y - ln(R ); a.^ ln(C 1; a, - a; a = b;
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™:
, 1 0 ) 1 ,
+ lnx,_^) Khoang bien thien ta p, ta co:
p, = —(in x,^^,-Inx,^,^) 2.4. Ket qua thiTc nghiem Chuyen cac bien tif t u nhien sang cac bien ma hda khdng thiJ nguydn, Vdi thuc nghiem 3 bien dau vao thay doi, tien hanh lam 8 thi nghiem tai cac dinh don hinh deu va 3 thi nghiem cl tam; sau khi gia cdng xong cac mau, tien hanh do do nham tren may do do nham Mitutoyo SJ - 400. Ket qua thuc nghiem (bang 2).
2.4.1. Quy hogch so lieu tht/c nghiem Theo phUdng phap BPNN ta co ham hoi quy thiic nghiem tong quat:
y - a g + a, X| +a^Xj+... +W Xac djnh ap,a|,aj... a^ sao cho Sdat giatn nhd nhat;
2 0 TapdiiKHOAHOC&CONGNGHE. S o 2 1 . 2 0 1 4
SCIENCnECHNOLMj
Cac gia tri a^, tran [A]:
[A] =
, dj... a^ la cac he so tUOng ufng cua ma
V d i : [ X ] . [ A ] - [ Y ] (5) - Ma tran thong so dau vao [X] la logarit co so e cac gia tri
V, S, t dung trong thi nghiem.
- Ma tran thong so dau ra [Y] cd cac he so la logarit co sd e cac gia tri dp nham do duoc tr^n cac mau thi nghiem.
Nhan hai ve cua (5) vdi ma tran chuyen vi X"^ cua ma tran X;
[ X r . [ X ] . [ A ] - [ X r . [ Y ] Bat [M] = [XY . [X] ta cd:
[M]. [A] = [X]^.[Y].
Gia SLT det(M) ^ 0 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 trong
bang 3.
TCf bang 3 va phuong trinh hoi quy thUc nghiem (2) ta cd:
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 do cat-
R^ = 0 , 0 1 0 7 9 . V * ' " « . S'rM687_ (-0.28811 (8) 2.4.2. Odnh gid dp tin cay cda ham hoi quy thi/c nghiem
• Danh gia do tin cay
Dp tin cay dUpc danh gia theo [5] cdng thifc:
(9)
Trong do: a^
1=
1 x„ x,i X,
' <» "a '•
^ [xl=
-
'1 5.09375 5.99146 1 5.56452 5.99146 1 5.09375 6.68461 1 5.56452 6.68461 1 5.09375 5.99146 1 5.56452 5.99146 1 5.09375 6.68461 1 5.56452 6.68461 1 5.35659 6.39693 1 5.35659 6.39693 1 5.35659 6.39693 SiJ dung phan mem Excel tinh toan ta di/ac ma tran [A]
Veil [Y] =
Q c h e SO
•-0.79851"
- 0.63488 0.32208 -0.12783 -0.86750 -1.23787 0.21511 -0.56212 - 0 59784 -0.52763 -0.51083 -ua phi/on
^M=
-4529111 -0.77396
1.20887 -0.28811^
=
a, a^3 trinh h )iqL ythl^c ng lien n:
Vdi: y^ - la logarit ca sd e gia trj do nham R^ thuc nghiem do dupc (y = InR^,);
y^^^ - gia tri trung binh logarit co sd e do nham R^ theo thuc nghiem do duoc;
y^' - la logarit dp nham R^ theo ham hoi quy thuc nghiem;
N - s d t h i nghiem.
SCf dung phan mem Excel ta tinh dUOc ket qua dp tin cay the hien trong bang 4.
-2.30259 -2,30259 -2.30259 - 2.30259 -1.20397 -1.20397 -1.20397 -1.20397 -1.60944 -1.60944 -1 60944
T-Siy,-
1 1 - 11
•2.50455 = 0.25046
= — ^ . y C y - / ) ' = — ^ " 0 . 2 5 3 8 6 = 0.0253 N - 1 V 11-1
0 . 2 5 0 4 6 - 0 . 0 2 5 3 9
0 6 tin cay: r = 90,5%
* Kiem dinli cac he so a^
- Xac dmh phaong sai du S^^
si =
N - k - 1 S'(A) (10)Trong do: N la so thi nghiem {N = 11);
it la so thong so can xac djnh trCr a^;
S'(A) = ([Y]-[X1.[A])'. ([Y)-[X1.[A])
Dung phan mem Excel giai cac bai toan ma tran ta tinh diroc: S'(A) = 0,25386
Sj. = S-iA) 0 25386 N-k-l 1 1 - 3 - 1 Xac dmh sUton tai cua cac he sd a
= 0.036265813 => S, = 0,19043585
raaBCTnaacoNG NGHE
Bang 3. Ket qua tinh logarit cac thong so thi nghiem
TT
1 2 3 4 5 6 7 8 9 10 11
Van toe V (m/ph)
163 261 163 261 163 261 163 261 212 212 212
Budc tien 5 (mm/ph)
400 400 800 800 400 400 800 800 600 600 600
Chieu sau catt (mm)
0.1 0.1 0.1 0.1 0.3 0.3 03 0.3 0.2 0.2 0.2
06 nham theo R, (pm) 0 45 0.53 1.38 0.88 0.42 0.29 1.24 0.57 0.5S 0.59 0.60
ln(Vlx,
5.09375 5.56452 5.09375 5 56452 5.0937S 5.56452 5.09375 5 56452 5.35659 5.35659 5.35659
ln(S)x,
5.99146 5.99146 6.68461 6.68461 5.99146 5.99146 6.68461 6.68461 6.39693 6 39693 6 39693
ln(t)Xj
-2.30259 -2.30259 -2.30259 -2.30259 -1.20397 -1.20397 -1.20397 -1.20397 -1.60944 -1.60944 -1.60944
.:
lnR,(/) , -0.79851 -0.S3488 032208 -0.12783 -0.86750 -1.23787 0.21511 -0 56212 -0.59784 -052763 -051083 Bang 4. Ket qua tinh toan 36 tin cay
TT 1 2 3 4 5 6 7 8 9 10 11
X, 5.09375 5.56452 5.09375 556452 S.09375 5.S64S2 5.09375 556452 535659 5 35659 5.35659
XI 5.99146 5.99146 6.68461 6.68461 5.99146 5.99146 6 68461 6 68461 6.39693 6 39693 639693
X, -2 30259 -2 30259 2.30259 2.30259 1 20397 1 20397 1.20397 1.20397 1.60944 1.60944 1.60944 Tong
Trung binh
y.
-0 799 -0.635 0.322 -0.128 -0.868 -1.238 0215 -0562 -0598 -0.528 -0511 -5.328
y, -0.56517 -0.92953 0 27276 -0.09160 -0.88169 -1.24605 -0.04377 -0.40812 -0.47814 -0.47814 -0.47814
y,ib. -0.484
»i-yi -0.23334 0.29465 0.04933 -0.03623 0.01419 0.00817 0.25888 -0.15400 -011970 -0.04949 -0 03268
( y . - y . ) ' 0.098697 0.403070 0.650330 0.127102 0.146807 0.567804 0.489242 0.006049 0.012880 0.001874 0.000701 2.50455
(yi-»,)' 0 054447 0.086817 0.002433 0001313 0.000201 0.000067 0.067018 0.023714 0.014327 0.002449 0001068 0.25386
Cac he so a^ tdn tai [5] xac djnh theo cdng thiJc:
Trong do: m^^ la so hang thcril (dudng cheo chinh) cua ma tran M ' v d i : [M] = [X]7 [Xl;
406.76821 -11.95875 -6.53236 0.78803"
H,-, ^ -11.95875 2.24794 -0.00804 -0.00782 -6.53236 -0.00804 1.03272 -0.00773 0.78803 -0.00782 -0.00773 0.40674
-4.52911
^auv'm,, ' |O.19043585.v'lO6.76821 = 1-2.301671=2.30167
2 2 TapdiiKHOAHOC&CONGNGHE. S 6 2 1 . 2 0 1 4
SCIENCETECHNOLOGYi
Hinh 4. Bo thi quan he giiia R^ v6i V va S Hinh S. 66 thi quan he giffa R^ vdi V va t Hinh 5 Bothiquan hegitiaR^vdiSvat
- 0.77396
P d u V ^ I |0.19043585. V Z 2 4 7 9 4 l
I a^ I I 1.20887 I
" " P d u V f ^ l |0.19043585,Vl.03272|
3 I I a? I I 1.20887
- 2 . 7 1 0 6 8 - 2 . 7 1 0 6 8
6 . 2 4 6 5 3 U 6.24653
-2.372191-2.37219 l ^ d u V W I |0.19043585.V0.40674!
Theo bang phan bd Student [3] vdi t^^^^ ( N - k - 1 ; r): t,,^^ =1,943.
Nhan thay: J>t^^„g(N - k - l , r ) v d i i - 0 - 3 ' " " " " ' | W " i i ,
Do dd cac he so a^ thUc sd ton tai, phuong trinh hdi quy thuc nghiem (7) ton tai, nen tdn tai moi quan he giUa do nham be mat vdi che dp cat nhu sau:
R^ = 0,01079 . V ^ " " * . S ' ^ ' ^ * ' . t'"'^^'"'
2.4.3. Do thi quan he gi&a dp nhdm vdi thong so che dp c6t
Dung phan mem MatLab ve do thi bieu dien moi quan he giCfa dp nham R^ vdi 2 gia tri cilia t h d n g so che dp cat. Od thj moi quan he gida R^ vdi V va S (hinh 4), do thi moi quan he giCra R^ vdi V va t (hinh 5); do thj mdi quan he giUa R^ vdi S v a t (hinh 6).
3 . K E T L U A N
K e t q u a n g h i e n cUu, t h U c n g h i e m v a xCr ly s o l i e u t h u c n g h i e m &a x a c d i n h d u p c m o i q u a n h e t o a n h p c giQa d p n h a m b e m a t c h i t i e t s a u g i a c d n g ( R J v d i cac t h d n g s d c d n g n g h e v e c h e d o c a t (V, S, t ) k h i g i a c d n g c h i t i e t v a t l i e u 4 0 C r t r e n m a y p h a y D O O S A N D N M 4 0 0 '
R^ = 0 , 0 1 0 7 9 . V ^ " " ^ . S ' ' ^ ' ' ^ " . t - " " « "
JU k e t q u a n g h i e n c d u n a y se g i u p c h o v i e c t i n h t o a n , l u a c h p n c h e d o c a t h o p ly, n a n g c a o dUOc n a n g s u a t , c h a t l u o n g b e m a t v a d d c h i n h x a c g i a c o n g .
Phan bien khoa hoc: TS. Hoang Van 8ien
TAI LIEU THAM KHAO
[1]. Nguyen Trang Binh, Nguyen The Bat, Tran Van Bich, Cong nghe che tao may, NXB Khoa hgc va Ky thuat, Ha Npi, 2002,
[2]. Pham Van Bong, Luan an tien sfky thuat, 2007
[3]. Tran Van Bich, Cac phuong phap xac dinh do chi'nh xac gia cong, NXB Khoa hoc vaKy thuat. Ha Noi, 2010.
[4]. Tran Sy Tiiy, Nguyen Duy, Trinh Van Ti/, Nguyen ly cat got kim loai, NXB Khoa hoc vaKythuat, Ha NOI, 1997.
[5], Nguyen Doan Y, Quy hoach thirc nghiem, NXB Khoa hgc va Ky thuat. Ha Noi, 2003.
[6] PA.Barobasup, Ngucii dich Tran Van Bich, Ky thuat phay, NXB Cong nhan ky thuat. Ha Noi,1984.
[7] Mike S. Lou, Joseph C. Chen, Caleb M. Li, Surface Roughness prediction techniqueforCNC End Milling, Journal of industnal technology, 1999.
[8]. M Alauddin, IVI. A. El Baradie v M. S. J. Hashml, Optimization of surface finish in end milling Inconel, Joumal of Materials Pmcessing Technology, 2005.
19]. M. 0 flKc6coH, TexHonorHfl CiaHKOCTpoeHnji, ll3flaTenbCTB0
"MaoiUHOCTpoeHHe" MocKsa, 1996.
[10], A. r, KocwnoBOii H P K MeuiepriKOBa, CnpaBOHHii TexHonora - MaiiiMHocTpoHTena, H3flaTejibCTBo"MaiiJiiHOCTpoeHne", MocKBa 2001.
