NGHIEN Cljru - TRAO D 6 I
^ G H I E N CLPU. THI^T K^ VA C H ^ TAO HE T H 6 N G DO NHIET C A T TRONG QUA T R I N H MAI PHANG
RESEARCH, DESIGN AND MANUFACTURE OF A CUTTING TEMPERATURE MEASURING SYSTEM IN THE PLANE GRINDING PROCESS
Nguyen Minh Quan', Nguyen Trpng Hieu^
'Hpc vien cao hgc, Trfldng Dai hpc Bdch Khoa Ha Ndi
^\^n phdng Hdi dong Chinh sach Khoa hpc va Cdng nghe Quoc gia
TOM TAT
He thong do nhiet cat trong qud trinh mdi phdng dUdc nghien ciiu, thiet kevd che tao nham thUc hien viec do nhiet dp tai be mat phoi khi gia cdng. He thong co nhiem vu giti tin hieu do dUdc (tin hieu so) tii cam bien dat tren phoi ve may tinh. Tai ddy mdy tinh se xii ly so lieu vd hien thi nhiet dp tren mdn hinh thong qua phan mem. He thong do nhiet nay se giup nhan biet dUdc qud trinh thay doi nhiet dp tren be mat phoi trong thdi gian gia cong, tii do cd nhUng bien phap thich hdp nham kiem sodt nhiet dp theoy muon.
Tfl khoa: Mdi phang, cap nhiet ngdu, truyen thong noi tiep.
A cutting temperature measuring system in the plane grinding process has been studied, designed and manufactured in order to take temperature measurements right on the workpiece's surface in the grinding process. This system sends signals (digitized temperature) from sensor mounted on the workpiece to a laptop. Here the laptop processes the signals and then displays temperatures on the screen through a software. This system is used to help realize the temperature changing process on the workpiece's surface;
as a result, suitable solutions will be taken to control the temperature.
Keywords: Grinding plane, thermocouple, serial communication.
TAP CHf CO KHI VIET NAM, Sd 12 nam 2013
NGHIEN CUfUTRAODdl
I.DATVANDE
Nhfl chung ta da bilt, trong qua trinh mai phang, hau h i t nang Ifldng dung de cat deu chuyen thanh nhiet, gay ra nhiet dp cao tai mdt so khu vUc t r i n b l mat phoi va da mai. Dac biet hdn nfla, nhiet dp cao cdn cd the dan den hien tfldng chay be mat phoi, anh hfldng den chat Iflpng san pham. Nhfl vay, nhiet cat neu nhfl khdng kiem sodt chat che se gay anh hfldng trflc tilp den chat Ifldng gia cdng chi tiet, lam giam nang suat lad ddng cung nhfl tang chi phi san xuat, gay anh hfldng d i n qua trinh san xuat. Chinh vi the, viec thiet k l mdt he thdng do nhiet cat trong qua trinh mai phang nham:
+ Giup nhan bilt dflpc mdt cdch tfldng ddi chinh xdc sU thay doi ve nhiet dp tai be mat gia cdng, tfl do cd the dfla ra nhflng bien phdp nham han che anh hfldng cua nhiet cat mdt each thich hdp.
+ Xay dflng moi quan he gifla cdc thdng sd che dp cat vdi nhiet dp.
2. GIAI QUYET VAN DE 2.1. PhUdng phap do nhiet cat
Hien nay, cd mdt sd phfldng phap do nhiet cat nhfl sfl dung md hinh ly thuyet, md hinh thflc te, do khdng tilp xuc nhd ky thuat quang hpc va do tilp xuc sfl dung ky thuat sdn hay cap nhiet dien. Trong dd, phfldng phap sfl dung cap nhiet dien cUc kep cho ket qua tUdng doi chinh xac va de dang lap dat.
2.1.1. Nguyen ly cau tao
Cau tao gom hai thanh kim loai a, b dfldc ban vdi nhau tai mdt dau la dau lam viec t^. Hai dau cdn lai t„ la dau tfl do.
2.1.2. Nguyen ly Idm viec i Khi cd sU chenh lech nhiet dp gifla hai
diem t, va t^ thi tai hai dau cdn lai cua hai thanh kim loai se xuat hien mdt suat dien ddng:
E J t , , g = E.,{t,)-EJt„) N l u gifl cho nhiet dp t^ khdng thay doi va t phu thupc vao mdi trUdng do nhiet dp thi ta cd:
E^^(t,, t^) = Ejt^) - C = f(tj)vdi C la hang sd Suat dien ddng E^^^ phu thupc vac nhiet dp t, va tp cung nhu phu thupc vao vat Heu de che tao cac thanh kim loai a, b.
Hinh 2: Vi tri cap nhiet ngdu trong qud trinh mdi.
Cap nhiet dien sfl dung la cap nhiet loai K.
Hinh 3: Cap nhiet loai K.
Hinh I Cdu tao cap nhiet dien cUc kip.
- Cau tao cua cap nhiet loai K gdm co hai day kim loai:
+ Cue dfldng: Chromel (80%Ni + 10%Cr + 10%Fe).
+ Cue am: Alumel (95%Ni + 5%(Mn + Cr + Si)).
Cap nhiet lo^i K cd dai do Idn: 0 - nOO^C, nhiet dp lam vile ngan ban khoang UOO^C, nhiet dp lam viec dai han Id dUdi 900 "C.
2.2. Cau tao va nguyin ly hoat dong ciia h^ th6ng
TAP CHi CO KHi VIET NAM, So 12 nam 2013
NGHIEN C f l u - T R A O D O I
Hinh 4: So do nguyen ly hoat dong.
H I thong gom 3 phan chinh: Sensor - cam biln (cap nhiet ngau), bd phan chuyen doi tin hi^u (gom card AD/DA va bd chuyen doi kit ndi RS485 - RS232) va may tinh.
Cdm bien dUdc gan chat vao phoi cd nhiem vu chuyen doi gia tri nhiet dp thdnh mdt gia tri dien thi. Gia tri diln t h i nay sau khi di qua card AD/DA se dfldc bien ddi thanh mdt tin hieu sd. Sau dd tin hieu sd se di vdd mdy tinh qua bd chuyin doi RS485 - RS232. Luc nay, phan m i m tren may tinh se phan tich tin hieu nhan dUpc rdi tinh toan trd v l gia tri nhiet dp do dupe vd hien thi len man hinh.
De tai sfl dung thilt bi ADAM 4019+
nham chuyin nhiet dd do dflpc sang tin hieu sd, thiet bi 1-7520 d l chuyin doi giao tilp RS-485 sang giao tiep RS-232.
2.3. Kit qua do thvT
Thfl nghiem dfldc tien hanh trIn mdy mdi HP-SUPEMEC-BP42-91260 cua Dflc sfl dung dd mai cd dfldng kinh 250mm. Sau khi cap nhiet dfldc lap trIn phoi thi phoi dflpc gd len mdy bdng nam cham dien (hinh 9) rdi tiln hdnh mai. Tdc dp cua dd mai trong suot qua trinh Id 35m/s vdi chieu sau sau cat lan lupt la 0,005mm; 0,01 mm va 0,012 mm.
ns I
Hinh 5: ADAM 4919+
B^ffii*:^
Hinh 7: Giao dien phan mem
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Hinh 8: Cap nhiet gd tren phoi.
Hinh 9: Phoigd tren mdy.
Hinh 8: Giao dien do thi nhiet da Hinh 10: Do thj gia tang nhiet do trong qud trinh nuiL
TAP CHI CO K H i VIET NAM. Sd 12 nam 2013 R I
NGHIEN cflu - TRAO OpI
3. KET LUAN
Nghien ciiu da dat dUOc mot so ket qua sau:
Che tao thanh cong mot hS thong do nhiet cat trong/qua trinh mM phang sCl dung cap nhiet dien loai K. Qua do ta co the theo doi qua trinh gia tang nhiet dp tren be mat phoi.
Tii ket qua cua bai bao ket hdp v6i viec tien hanh phuong phap quy hoach t h a c nghiem, ta co the tim ra m6i quan he giQa nhiet do be mat phoi va cac thong so che dp cat (V, S_, T). Til do co the dung lam dieu kien cho bai toan toi liu hoa qua trinh mai phang.
Hildng phat trien cuade tai: t h i e t ke va che tao he thong do nhiSt sfl dung mpt s6 loai cap nhiet khac nhU: J, B, Pt, .. .cung nhu tich hpp dtipc vdi bp dieu khien PLC de tao thanh mpt he thong dieu khien khep kin. •
Ngay nhan bai: 10/11/2013 Ngay phan bien: 4/12/2013
Ngildi phan bi|n: GS.TS. Tran Van Dich, Vien Co khi, Tnldng Dai hpc Bach Khoa Ha Noi.
Tai lieu tham khao:
[1]. Nguyen Trong Binh, Gia cong cd khi, NXB. Dai hoc SU pham (2005).
[2]. Phan Quoc Pho, Nguyen Dilc Chien, Giao trinh cam hien, NXB. Khoa hoc va Ky thuat (2009).
[3]. Tran Van Dich, Gia cong tinh be mat chi tiet, NXB. Khoa hoc va Ky thuat (2004).
[4]. Hoang Minh Cong, Cdm hien cong nghiep, NXB. Dai hoc Bach Khoa Da Nang (2004).
[5]. Pham Van Tuan, Han Trong Thanh, D6 Quang Ngpc, Pham Van Bien, Ky thuat do lUdng tU dangdiiu khien, NXB. Bach Khoa, Ha Noi (2008).
[6]. Mark Nelson, Serial Communications Developer's Guide, Second Edition, IDG Boolis Worldwide. Inc.
(2000).
[7]. D. Anderson. A. Warkentin, R. Bauer, Experimental validation of numerical thermal models for dry grinding.
Journal of Materials Processing Techonology 204 (2008) 269-278.
[8]. A.D. Batako, W.B. Rowe, M.N. Morgan, Temperature measurement in high efficiency deep grinding.
International Journal of Machine Tools & Manufacture 45 (2005) 1231-1245.
[9]. Xipeng Xu, Experimental study on temperatures and energy partition at the diamond-granite interface in grinding, Tribology International 34 (2001) 419-426.
TAP CHl CO KHi VIET NAM, S6 12 nam 2013
