NGHIEN CUfU-TRAO DOI DANH GIA K H A NANG CAT CUA DA MAI CO BE MAT LAM VIEC GIAN DOAN THONG QUA DAI LU'ONG HIEU SUAT MAI KHI M A I T H E P 45 NHIET LUYEN EVALUATION OF THE CUTTING CAPABILITY OF WORK SEGMENTED GRINDING WHEEL BY THE PRODUCTIVITY OF HARDENED C45 STEEL GRINDING PROCESS Nguyen Tien Dong*, Nguyen Thi PhUdng Giang', Trinh Van CUdng^ Nguyin Thi PhUdng' 'Vien Co khi, TrUdng Dai hpc Bach Khoa Ha Npi -TrUdng Dai hpc Sao Dd 'Tong cue Hau can, Bd Cdng an TOM TAT Dd mdi xe ranh dUdc nghien cdu vd phdt trien gan day tai Viet Nam dUa tren nguyen ly gia cong gian doan dUdc sii dung nham muc dich nang cao hieu qua gia cong cua hat mdi Hien tUdngphoi mdi chiem vd bdm dinh vao khoang khonggiUa cdc hat mdi, khien dd bi "cun", dUdc giam di Trong bdi bdo nay, mot tieu chi danh gid dd mdi cd be mat lam viec gian doan dUdc dUa tren hieu sudt gia cong }x, dUdc dinh nghia Id ty le giUa lUdng kim loai hdt di thUc te Q^^ vd lUdng kim loai hdt di theo ly thuyet Q,^ mot ddn vi thdi gian, doi vdi loai thep C45 dd nhiet luyen Nam vien dd mdi xe ranh co so ranh lan lUdt la 12,18, 20, 22, 24 vd mot vien dd mdi thong thiidng khong xe ranh, dUdc sii dung de mdi thep C45 da nhiet luyen Ket qua cho thay lUdng kim loai Q^^ dUdc hdt di mot giay mdi thep C45 nhiet luyen vdi phUdngphap mdi phang sii dung vien dd mdi co so ranh 18 Idn hdn nhieu so vdidd mdi lien tuc thong thudng Hieu sudt mdi doi vdi loai da mdi co so ranh ndy cho hieu sudt cao nhat Tii khoa: Thep nhiet luyen C45; Dd mdi gian doan; Hat mdi ABSTRACT Recently developed in Vietnam segmented grinding wheels base on the fundamental of discontinuous machining is used to enhance the grindability of abrasive grains The phenomenon of grinding chips adhesived to space between grains, that make the wheels became "dull", was reduce In this paper, the evalution of segmented grinding wheel is based on the cutting performance ^, is defined as the ratio between the real volume of removed material Q and the theory volume of removed material Q^^ in unit time, in machining hardened C45 steel There are five segmented grinding wheels with number of segment is 12, 18, 20, 22, 24 alternately, and a conventional grinding wheel Results showed that when grinding hardened C45 steel by segmented wheel with 18 segments is considerably higher than the result of conventional wheels The 18 segments wheel provides the highest processing performance comparing to the other wheels Keywords: Hardened C45 steel; Segmented grinding wheel Abrasive grain TAP CHi CO KHi VIET NAM, Sd nam 2014 www.cokhivietnam.vn ~^ N G H I E N CUfU - TRAO D | I G I O I THIEU CHUNG Mai la qua trinh xuat hien sU tach mdt Idp vat lieu khdi vat gia cdng d dang phoi Dung cu mai cd nhflng tinh chat dae trUng nhat dinh nhU: Vat lieu hat mai, dd hat, dp cUng, dd rong, chat dinh ket Kich thude va hinh dang hat mai lai bi thay doi sudt qua trinh mai SU thay doi lam thay doi kha nang cat cua nd, thay ddi tinh chat ban dau cua da mai gay sU mdn dung cu Khai niem "kha nang gia cdng" dupe nhieu nha nghien euus quan tam De xac dinh dupe kha nang cat cua da mai phai dUa tren dac diem dac trUng cua qua trinh mai, tfle la vat lieu dupc tach bIng mdt lUpng Idn cac hat mai dUOc bo tri ngau nhien tren be mat da vdi cac thdng sd hinh hpc khdng xac djnh Vi vay, kha nang eat cua da mai la kha nang tao phoi tU vat lieu gia cdng tren co sd mdt nang lUpng tieu bao nhat dinh va vdi lupng hao mdn cho phep cua da [ 1,2,3] dp cflng vUng cua he thong cdng nghe Tac gia Armarego [6] da de xuat mot tieu chuan mdi ve kha nang eat cua da xuat phat tfl viec danh gia giai doan phat tia Ifla cua qua trinh mai DANH GlA KHA N A N G CAT CUA DA M A I THONG QUA HIEU SUAT M A I Tac gia R.Snoes, J.Peters [6,7] da ehi tich so: h.VydO.Vj, dUpc trinh bay nhU hinh 1, la dai lupng cd quan he vdi hau het cac dai lUpng khac qua trinh mai Dai lUpng dUpe gpi la chieu day edt tUOng dUOng, heq, y nghia ciia dai lupng cho rang the tich Idp vat lieu dupe bdc bdi da mai d toe dp Vd bang vdi the tich Idp vat lieu dupc bdc khdi vat gia cdng sau mot don vi thdi gian -'i M O T S O C O S D A N H GIA KHA NANG CAT CUA DA MAI r • C/ip,\,^,-l~:r'^—^—r-— th,, v^i I'l Hinh 1: Chieu day cat tUdng duong mai phang De danh gia kha nang cat cua da, ed the Tren nguyen tic bao toan lugng vat lieu di sfl dung mdt hay mdt sd chi tieu vdi dieu kien vao va di khoi vung cat ta co: gia cdng da dinh, dd la ty le giUa: LUpng bdc vat lieu va lUpng mdn cUa da, hay gifla cdng suat mai t.b.V, =h,,.b.V| (1) va Iflc cat mai, dp nhap nhd be mat sau (2) mai Da mai ed kha nang cat tot ed lUc eat nhd, cdng suat mai nhd, lUpng mdn cua da mai it Trong do: nhUng cd kha nang tri kha nang bdc vat Heu va chat lUpng be mat chi tiet gia cdng eao b: Chieu rong tiep xiic giiia da va chi tiet; V,: Toe chi tiet; Nhieu tac gia da quan tam den kha nang V^: Toe dp da (m/s); cat cua da va dUa phUpng phap danh gia khae t: La chieu sau cat (mm) Cach danh gia cd the tien hanh tren co sd cua mdt sd hien tUpng co, ly thich hpp dupe chpn The tich vat lieu hoc mot ddn vi nhU: Mat dp Idp vat lieu gia cdng, dp Idn cua lUc, thdi gian theo ly thuyet: Q„ = b.t.V ^ (3) sdng va chat lUpng be mat gia cdng [2,4,5], Mot vai tieu chuan khac lien quan den thdng sd co ban The tich vat lieu dupc hoc mot cua cdng nghe mai: Tudi ben da, tdc dp mai, tdc don vi thdi gian doi vdi don vi chieu rpng lam dp chi tiet, tdc dp tien dao, phUPng phap mai va viec cua da mai la: Q^ = t.V ^ = h^ V^ (4) S m • TAP C H i CO KHi VIET NAM, S6 niim 2014 www.cokhivietnam.vn N G H I E N CUfU-TRAO DCI HieusuatmaidUpcMaxiop[8]danhgiabang ty le ^1 = Q,, /Qj^