NGt:ilE?3 CUfU-TRAOeOl
MO limn HOA RUNG DONG KHI MAI THEP HOP KIM TREN MAY MAI TRON NGOAI
I40DELING VIBRATION WHEN GRIND ALLOY STEEL ON EXTERNAL CYLINDRICAL GRINDING MACHINE
Nguyin Tu3n Linh', Tran Van Dich^
'Truong Dai hoc Cong nghiep Ha Noi
^Truong Dai hoc Bach Khoa Ha Npi
A - I ng la thong so trung gian trong qud trinh gia cong, nhtmg no lai true tiep anh huang den did! lirang cua san pham. Rung dong trong qua trinh mai tron rat phlrc tap va chiing phu thupc vao nhieu yeu Id nhu do cimg vimg cua he thong cong nghe, che do gia cong, vat lieu gia cong, che do boi tjon lam nguoi,... Noi dung cita bai bao trinh bayphuffngphdp Taguchi de thiet ke thuc nghiem vd ddnh •,/.id muc do dnh huong cua cdc thong so che do cat vd thong so vat lieu den rung dong khi gia cong mot so loai thep hap kim tren mdy mai tron ngoai. Tie do co thi diiu khiSn rung dong thong qua che do cat vd vat lieu gia cong nham kiem soat chat luong be mat ciia san phdm.
Tir khoa: Che do cat; Vat lieu. Rung dong; Thep hap kim; Mdi Iron ngoai.
ABSTRACT
To sum up, vibration is an intermediate parameter on machining operation; However, it directly affects quality of product. Indeed, vibration on cylindrical grinding is very complex, depending on various factors such as rigidity of technology system, cut condition, material machining, grease condition, cool, etc. The article's content presents Taguchi method to design experiment and lo evaluate the influence of technology parameters and material parameter on vibration when machining some kinds of alloy steel on external cylindrical grinding. As the resuh, vibration can be controlled hy cut condition and material machining, for the purpose of mastering quality of product's surface.
Keywords: Cut condition, material, vibration, alloy steel, external cylindrical grinding.
NGHIEN COfU-TRAOeOl
1. RUNG DONG TRONG QUA TRINH MAI Rung dpng trong qua trinh gia cong la mot mpt yeu to phuc tap, rung dpng vdi cuong dp thdp anh hudng khong nhi^u din qua trmh gia cong.
Tuy nhiSn, rung dpng voi cuong dp cao co thS anh huong den mot vai phucmg di^n cua qua trinh cat gpt nhu:
- Hinh thanh dp song tren b^ mat gia cong va giam dp chinh xac ciia chi ti8t gia cong;
- Tang dp nham bk mat;
- Tang mon dung cu dt;
- Tang tieng on va giam tu6i thp cua may.
dpng va cai thi6n mo hinh dpng luc hpc trong qua tiinh mai tron xet d8n dieu kien phu thupc cau true dpng lye hpc.
Tuy nhien, miic dp anh huong ciia cac thong s6 ch6 dp dt va vat lieu gia cong den rung dpng ciia qua trinh cat nhu the nao chua duoc de cap. Nhu vay, vin de can dupe dua ra giai quyet 6 day la giai bai toan thuc nghiem ve miic dp anh huong cua cac dieu kien mai den rung dpng trong qua trinh gia cong tren may mai tron ngoai.
2. THIET KE THI NGHIEM TAGUCHI VA DANH GIA Mirc DO ANH HU*6NG CUA CAC THONG SO [31
Co hai dang rung dpng trong qua trinh
mai: Rung dpng cuong biirc va rung dpng tu kich 2.1. Thiet bi thi nghiem thich.
Dp lech tam va sy khong dong deu tren be mat cua da mai la nguyen nhan chinh gay ra hmh thanh rung dpng cuong buc. Khi khSc phuc duac nhirng anh huong tren se dh\ den hinh thanh rung dpng tu kich thich. Chuyen dpng quay cua da mai va phoi hinh thanh dp song tren be mat da mai va do do anh huang d§n su hinh thanh dp song tren bS mat chi tiet. Dp song hinh thanh phu thupc vao kich CO hat mai va sy gia tang luc mai. Bai vi hinh dang cua da mai khong on dinh (khong ben) do do bien dp cua rung dpng ty kich thich tang va da mai tra nen mon. Rung dpng ty kich thich anh huong bai di^u kien dt, thuoc tinh ciia da mai va vat lieu gia cong [1]-
Rung dpng quy§t djnh d6n chdt lupng be mat va do chinh xac ciia qua trinh mai, day la hai ySu t6 chinh cua qua trinh mai. Qua trinh mai la mot qua trinh rdt nhay vai rung dpng. Chinh vi vay, khi bik dupe bien do rung dpng, co the thigt ke duoc mot qua trinh mai voi muc dich han che t6i da rung dong.
May mai tron: MEG - 1120 MAGNUM CUT, toe dp quay true da: 2000v/p, toe dp quay chi tiet: 0 - 650v/p, toe dp dich chuyen cua ban may: V6 cap tir 0,1- 5m/p, cong suat dpng co:
4kW.
- Da mai: Kich thuoc da 400x50x203.
- Dung cu sua da: Dau sua da kim cuong loai 3 hat CO kich thuoc: 8,5x40.
- Chi riet gia cong: Duong kinh 30mm, vat lieu gia cong thep 40X, 65r, 9XC va thep gio P18 nhiet luyen dat cac dp ciing 40, 50 va 60HRC.
- Phuong phap mai: Mai co tam chay dao doc.
- Thiet bi do rung: Thiet bi do rung cua hang Bruel&Kjaer Dan Mach:
+ Mo dun thu thap dii lieu LAN-XI co 4 dau vao va 2 dau ra tan so toi 51,2kHz.
+ Mo dun phan tich PULSE FFT 7770, 1-3 kenh, PULSE FFT Analysis.
+ Cam bi^n gia toe 3 phuong Triaxial Delta- Tron Accelerometer with TEDS Type 4525-B- 001.
2.2. Thi^t k^ thi nghifm Taguchi va d^nh gia mirc dp anh hiring cua cac thong s6 Diiu kien mai phu thupc vao cau tnic Trong truong hop chay khong tai, dSu do dpng luc hpc ciia da mai - phoi, trong cong trinh dupe gan a hai vj tri la true da va mui tam. Muc nghiSn cuu cua Hongqi Li va Yung C.Shin [2] da dich la dy doan tan s6 dao dpng rieng cua true dua ra nghien cmi thuc nghiem ve dac tinh rung da va mui tam dua vao t6c dp quay cua true. ^
TAP CHi CO KHi VIET NAM, S6 5 nam 2014 www.cokhivietnam.vn
NGHIEN CUfU - TRAO D O I
- AuliKpEctrum(X) - File [Real) '.. FFT Qjraar values
X: 1.3!33h Hi Y: 1.112m n i / s ' Z: t.ODQ 3
Hinh 2 1: Biiu A6 rung tong dangphd trong trucmg hap chay khong
TiSn hanh thi nghiem do rung dpng khi mai thep 9XC, cac thong s6 dau vao dugc dieu khiSn la luong chay dao doc S^ (m/p), toe do quay cua chi life n^, (v/p), chita sau cat t (mm) va dp cung cua vat lieu chi tiSt gia cong (HRC). Cac thong s6 khac khong diSu khiSn dupe coi la cac thong so nhieu.
Thong s6 dSu ra la bien dp rung dpng Ion nhSt A (A la bien dp gia t6c, m/sj) duac xac dinh trpng khoang miSn tan s6 cua da mai va mui tam. Muc dich cua phin danh gia nay nhSm loai bo nhiing thong s6 it anh huong d6n rung dong trong qua trinh mai.
Thay doi S^ (m/p) voi 3 cip: 0,3 ; 0,4 ; 0,5. Thay d6i n^, (v/p) voi 3 cap: 100; 150; 200. Thay dai t (mm) voi 3 cap: 0,005; 0,01; 0,02. Thay d6i dp ciing (HRC) voi 3 cSp: 40; 50; 60.
Bdng 2.1. Bdng true giao Taguchi L9 vai cdc thong so thi nghiem Thi
nghiem 1 2 3 4 5 6 7 8 9
(m/p) 0.3 0.3 0.3 0.4 0.4 0.4 0.5 0.5 0.5
"„ (v/p) 100 150 200 100 150 200 100 150 200
t (mm) 0.005 0.01 0.02 0.01 0.02 0.005
0.02 0.005
0.02
Do cung (HRC)
30 40 50 50 30 40 40 50 30
Lan do 1 A(m/s^)
0.765 0.854 1.046 0.904 1.185 1.026 1.120 0.988 1.239
L^n do 2 A(m/s')
0.773 0.912 1.002 0.912 1.201 1.101 1.139 1.013 1.225
Lan do 3 A(m/s=) 0.768 0.886 1.032 0.924 1.176 1.112 1.147 1.001 1.234
NGHIEN ClJfU - TRAO D 6 I
Phan tich he so tin hieu SN ta co ket qua nhu sau:
Bdng 2.2. Muc do dnh hudng ciia cdc thong s6 thi nghiem
Muc dp 1 2 3 R
A He so SN ciia S^
1.0410 -0.4586 -0.9753 2.0164
He so SN ciia n^, 0.6565 -0.1434 -0.9060 1.5625
He so SN cua t 0.5359 0.0126 -0.9416 1.4775
He s6 SN ciia HRC -0.3412 -0.2354 0.1836 0.5248 Voi dai R nhu bang 2.2 co the thay rang miic dp anh huong ciia luong chay dao dpc, t6c dp quay ciia chi tiet va chieu sau cat den rung dpng kha Ion. Anh hucmg ciia dp cung vat lieu gia cong tuong doi nho so voi miic dp anh huang ciia cac thong s6 ch6 dp cit. Nhu vay, thong s6 nay se dupe coi la yen to nhieu, khong dieu khien.
Ti8n hanh thi nghiem vdi cac loai vat lieu khac la 40X, 65r, P18 cho k6t qua phii hpp voi vat lieu 9XC.
3. XAY DyNG MO HINH TOAN HOC Chpn mo hinh toan hpc bac I nit gpn la:
y = b, + b,x,+b,x^ + b3X3 (3.1) Hoac CO the viet duoi dang ma tran nhu sau: [X].[B]^[Y] (3.2)
Bdng 3.2: Bdng quy hogch cdc thong so thuc nghiem vdi thep 9XC
STT 1 2 3 4 5 6 7 8
Thong so dSu vao Bien mS hoa
\
+1 +1 +1 +1 +1 +1 + 1 + 1
X, -1 +\
-1 + 1 -1 + 1 -I +1
X,
•1
-1 +1 +1 -1 -1 +1
-n
X, -1
•1
-I -1 +1 +1 +1 +1
Bien thuc nghiem S,
(m/p) 0 3 0.5 0.3 0.5 0.3 0.5 0 3 0.5
(v/p) 100 100 200 200 100 100 200 200
t (mm)
0.00 5 0.00
5 0.00
5 0.00
5 0.02
5 0.02
5 0.02
5 0.02
5 A (mis')
0.769 0.865 0.878 0.964 0.902 1.112 1.098 1.325
Ln
-1.203 -0.693 -1.203 -0.693 -1.203 -0.693 -1.203 -0.693
Ln
4.605 4.605 5.298 5.298 4.605 4.605 5.298 5.298
Ln (t) -5.298 -5.298 -5.298 -5.298 -3.912 -3.912 -3.912 -3.912
Ln (A) -0.263 -0.145 -0.130 -0.037 -0.103 0.106 0.093 0.281
TAP CHi CO KHi VIET NAM, S6 5 nam 2014 www.coldiivietnam.vn
NGHIEN CUfU-TRAODOl
Giai he (3.2) bang phSn mem Matlab ta co:
y = -0.0446 + 0.2980X, + 0.2208X3+ O . n H X j Hoac CO th6 vi8t duoi dang ham so mii nhu sau:
A - 0 . 9 5 6 4 S d " ^ ' « ° n / ^ ^ ' ' ¥ ' ' ' '
(3.3)
(3.4)
Hinh 3.1-Dd thi quan hi gOta A vdi S^ vd t khi «^, = 100, 200 vd 300v/p
4. KET LUAN
Rung dpng trong qua trinh mai tron ngoai bao gom rung dpng cuong biic va rung dpng tir kich thich. Rung dpng cu&ng biic la ban ch4t cua may, rung dpng tu kich thich la ban chat ciia qua trinh cit.
Xet trong vung thuc nghiem, rung dpng cua qua trinh cat it phu thupc vao vat lieu chi tiet gia cong ma chii yeu phu thupc vao che do cat.
Cac thong so che dp cat co anh huong ty le thuan voi rung dpng, nhu vay de giam rung dpng trong qua trinh cat can giam cac thong so che dp cat nhung neu giam cac thong so nay se dan toi nang suat giam.
Mo hinh toan hpc (3.4) cho phep di6u khien rung dpng theo cac thong s6 S^, n^^, t. K i t qua nay se giiip mo hinh hoa qua trinh mai tron ngoai cac loai thep hop kim n h i m dat dp chinh xac va nang cao nang suat gia cong, cho phep lua chpn mot che dp cat hop ly khi gia cong cac loai thep hpp kim tren may mai tron ngoai.*!*
Ngay nhan bai: 12/4/2014 Ngay phan bien: 05/5/2014 Tai lieu tham khao:
[1 ]. Nemeth Stephan - Nesllusan Mirosla, Vibration in grinding operations, 7th International Multidisciplinary Conference, Baia Mare, Romania, 2007.
[2]. Hongqi Li va Yung C.Shin, A study on chatter boundaries of cylindrical plunge grinding with process con- dition-dependent dynamics, Intemational Journal of Machine Tools & Manufacture 47 (2007) 1563-1572.
[3]. Roy, Ranjit K, John Wiley & Sons, Design of Experiments Using the Taguchi Approach, 16 Steps to Prod- uct and Process Improvement, Inc. (US).
