l a p cm Khoa noc
Nghien cmi tinh di hwong cua ma sat be mat khi mai tinh thep C45
Study o n Anisotropy of Surface Friction of Steel C45 C o n d u c t e d b y Fine-Grinding Method
Nguyin Thuy Dieffng^*Phgm Vdn Hung', Nguyen Van Canh^, Nguyin Trwdng Sinn ' Trudng Dai hoc Bdch khoa Hd Npi. SS I.Dai Co Viet, Quan Hai Ba Trung. HdNgi
^ TrudngDaihoc Cong nghiep Hd Noi, Phudng Mnh Khai. Qugn Bdc TuLiem. Thdnh phd Ha J^Qi
^ Hoc Vien ky thudt Qudn su, 236 Hodng QuSc Viet. C6 NhuS, Bdc Tir Liem, Hd Noi Din Toa sogn- 18-6-2018; chdp nhgn dang: 18-01-2019
Tom tat
Bi m$t chuyen dgng cda cac cap ma sat diu dagc gia cong bing cac phaang phap cong ngh^^phu hop nhim giam thiiu ma sat. mon va nang cao tuii tho khi lam viec. Doi va/ cac cap ma sat co yeu cau cao ve chit lagng bi mat va lip ghep thong thaang daac gia cong lin cu6l bing phaang phap mal tinh.^ Chuyen ddng tao hinh cua may cong cu noi chung va chuyen dgng tao hinh cua may mai noi rieng di gia cong dagc hit cac be mat luon tin tai lagng chay dao dgc va lagng chay dao ngang. Hal lagng chay dao nay thaang khde nhau vi gia tri din tai chit lagng be mat ma sat theo phaang chay dao ngang va phaang chay dao dpc la khong ding nhit. Bai bao nay trinh bay ket qua nghien cim tinh di hoang ma sat be mat dagc gia cong bing phaang phap mai tinh. Kit qua nghien cau cho thay co thi dieu khiin dagc tlnh dt hoang cda ma sat bi mat thong qua cac thong so cong nghe khi mai tmh nhim giam thiiu ma sat va nang cao hieu suit lam vi$c.
Tif khda: Tgo hinh be mat mai, ma sat be mat, tinh di hudng be mat Abstract
The moving sudaces of the friction pairs are usually machined using appropriate technological methods to minimize the friction, wear and to improve the longevity. For the friction pairs that require a high surface quality are usually hnished by the fine-grinding. The working motions of machine tools in general - and grinding machine in padicular - for machining a whole surface always create a longitudinal and horizontal feed rates. These two feed rates are often different so that results in a different quality of horizontal and longitudinal friction surface. This paper presents the study results of anisotropy of the surface friction which is conducted by fine-ghnding method. The results show that the anisotropy of surface friction can be controlled through the fine-grinding technological parameters to minimize the friction and to improve the operation efficiency.
Keywords' Surface grinding, surface fnction, anisotropy of surface
Chat lugng be mat ciia chi det sau khi gia cdng CO la mdt ySu td quan frgng, anh hudng true tigp dSn kha nang lam viec va quyet dinh mdt thp ciia chi tidt.
Hien nay, dd dam bdo chdt lugng be mat chi tiet dap ling yeu cdu lam viec ngay cang cao, cd nhieu phuong phdp gia cdng de ndng cao chat luong be mat: Mai tinh, khdn, ngbien, phun bi, lan bi ...Trong dd, mdi la phuong phdp gia cdng tinh lan cudi dugc sir dung kha pho bien ddi vdi chi tiet may cd chuyen dgng va dam bao che do lap ghep. Phucmg phdp mdi tinh cd thd dat dugc cdp do bdng 9-10[l,2].
Do chdt Iugng be raat chi tiet dugc q^uyet dinh bdi cdng nghe gia cdng, vi vay da cd nhieu nghien
• Dia chi lien he: Tel.: (+84) 904447096 Email: [email protected] vn
ciiu ve anh hudng chg dd gia cdng tdi chdt lugng bk mat ciia chi tiet thudng duoc ddnh gia qua gia tri do nhara bd mat Ra, Rz. Cdc kdt qua nghien ciru da cho thay cac thong so cdng nghe gia cdng cg cd anh hudng phi tuydn tdi chat lugng bd mat ndi ehung vd nhdm be mat ndi rieng [3,4], Vd nguyen tjc, d i ddnh gid chinh xdc cac anh hudng ciia gia cdng ca d i n ch5t lugng be mat vdn cdn phai tien iiar]-i thirc nghiem dm ra quy luat cho cdc trudng hgp cu LJIC, Tuy nhidn chdt lugng be mat ndi ehung vd nhdm bd mat ndi rieng chua ldm ro dugc bdn chdt dnh hudng nay tdi chit lugng va hieu sudt ldm viec ciia chi ti6t, Trong khi do, luc ma sal be rnat ndi chung va he sd ma sdt ndi rieng Id mdt thdng so dnh hudng true hip d6n khd nang lam viec vd hieu sudt lara viec cua ma s?,i
Trong qua frmh gia cdng ch hit mav cd su phdi hgp cac chuyen ddng tao hinh • •- nay ^^^^^ '^^ ^ the la chuyen ddng quay true ^^ ^ac chu'ylo
dpng chay dao [5]. Tren thyc te, cdc chuyen dgng chay dao cua may cdng cu thudng khac nhau. Chinh vi vdy, chat lugng be mat ndi chung, do nhdm ndi rieng ciing nhu ban kinh cong dinh nhap nhd theo hai phuang chay dao (dgc va ngang) cd gia fri khac nhau.
Bay ia nguyen nhan c o ban dan den chat lugng be mat va nham theo cac phuang la khac nhau. Su khde nhau do cd dnh hudng true tiep den vecta lire raa sat so vdl vecto tdc do khi van banh lam xuat hien tinh di hudng ciia raa sat [6] gdy dao dgng va Idra radn cap ma sat. Dieu ndy rat nguy hiem vi nd khdng dugc ke den trong qua trinh thiet ke chi tiet cung nhu van hanh vd bdo dudng. Viec nghien cuu dnh hudng true ti6p cua che dd gia cdng tinh tdi tinh di hudng eua lire raa sat la rdt can thiet vd se giai thich dugc nhiing hu hdng be mat khdng dugc ke den frong qud trinh tinh toan thiet ke nhung lai xuat hien frong qua trinh lam viec theo cdc phucmg khac nhau.
2. NghiSn cuu thirc nghieni xdc dinh tinh di hndng cua ma sat be mat
Muc tieu thuc nghiem: Khao sat danh gia tiidi di hudng cua ma sat be mat chi tiet sau khi mai tinh vdi cdc dak dd chay dao dgc khac nhau.
2.1 Thiet bi thir nghiem
Khdo sdt tinh di hudng ma sat be mat, sii dung thiet hi do ma sat da nang UMT do hang CETR ciia My che tao. Thi6t bi cd kha nang do dugc luc raa sat, do lugng radn, thir nghiem co tinh, thir nghiem bdi tron.., cd so dd nguyen ly nhu Hinh 1.
(6D), lyc cd the dugc do chinh xac tit itiN tdi kN vdi do phdn gidi 0,00003% cua thang do,
Thiet bi dugc ket ndi va dieu khidn bdng mdy tinh vdi 16 kenh thu thdp dil lieu cd dg chirdi xac va phdn giai cao. Xii ly vd hien thi ket c}ua bdng phdn mem CETR. Phan mem cho phep hien thi radt hay nhieu do thi ket qud do o cac che do khde nhau, Hinh 2 the hien giao dien man hinh hidn thi kit qua do va xu ly sd lieu gdm: Dd thi tai frgng; Dd thi mdn; Dd thi lyc raa sdt; Dd thi he sd ma sat; Yung eho phep chgn loai do thi hien thi; Gia fri trung binh ciia tung ddthi.
Hinh 2. Giao dien man hinh iuen thj ket qud do vd xu ly sd lieu
2.2 Sff dS do
Khao sdt tinh di hudng ma sdt dugc tien hdnh vdi vien bi fren t i m phang theo tieu chudn ASTM G 133. Luc ma sat di budng se xudt hien khi cd sy tuang tac ma sdt cua bi va be mat nham Tdi trong dugc dat len vien bi tdc dgng len mdu phia dudi la tdm phdng cd chuyen dgng tinh tien. So dd do dugc truih bay tren Hinh 3.
^ Hinh 1. So dd nguyen Iy thiet bi UMT
; _ Thiet bi sir dung cdm bien do sieu chinh xac, do li d6ng thdi tai trgng va raomen tir 2 true (2D) tdi 6 true
H a n h trinh HIL nahidm
Hinh 3. So dd do raa sdt 2.3 Mail thi nghietn
Mdu thi nghiera dugc lam tir thep C45 cd kich thudc 50x30xlOmm dugc radi tinh vdi ba che dd chay dao khac nhau, dat cdp dd nhan bdng 9-10 nhu fren Hinh 4.
Cac thdng sd cdng nghe co bdn cua qua trinh raai tinh mdu thep C45.
- Thiet bi chd tao: May raai 3E 71 IE:
- Da raai: Ct 60 - TBIG. D250xd75xB40mm;
- Van tdc cdt: V^ 35Tn/s;
- Chieu sdu cdt: f = 0.03rara;
- Lugng chay dao ngang: S„ = 0,3m/ph;
- Luong chay dao dpc: S^y=15,4ni/ph Sd2 19,2m/ph,5'jj-23m/ph,
Mlul f H Mlu 2 ^M Mill 3 Hinh 4. Mdu sau khi mai tmh 3. Ket qua va thao luan
Thyc nghiera dugc tien hanh nhu sau: Cdc mau dugc che tao phdi ban ddu gidng nhau. Sau do dugc mdi tinh vdi 3 che do gia cdng tmh khde nhau cd Sji - 15,4ra/ph, Sd2 = 19,2ra/ph, Sji - 23m/ph. Cdc mlu sau khi mdi tinh dugc tien hanh do luc raa sdt fren thiet bl do UMT. theo hai phuang tuong iing chay dao doc vd chay dao ngang de xdc dinh tinh dj hudng raa sdt vdi cac thdng sd mdy co ban nhu sau:
- Tai tdc dung: P = 20N;
- Thdi gian thir 300s , - Hanh trinh tinh tien 10mm.
Vdi moi radu thi nghiera se xac dinh tinh di hudng raa sat theo 2 phuang chay dao (doc hudng gia cdng va ngang hudng gia cdng) nhu Hinh 5.
Hinh 6. Dd thi luc raa sat di hudng mdu 1 Sdi /S„
15,4/0,3
Cac gia fri do ma sat tren Hinh 6 cbo thdy hai thdnh phan cua luc ma sat cd gia tri tmng binh la:
Theo phuang chay dao dgc F,=- 4.268N, theo phirong chay dao ngang Fy = 1,744N.
Dd dli luc ma sat Fx theo thdi gian cd dang dd thj nguyen tdc bi^n ddi chung lyc ma sat gdm 3 giai doan: Giai doan dich chuydn ban ddu, giai doan gidn doan vd giai doan trugt hoan toan [3,4].
Thanh phdn lyc ma sat di hudng Fy cd phuong vudng gdc phuong chuyen dgng do X (triing vdi phuong chay dao ngang). Gia tri Fy nhd hon so vdi Fx. dao ddng quanh gid tri tmng birdi 1,744N va Fy ^ 40% F..
Tuong ty vdi mau 2 cd lugng chay dao Sdi /Sn = 19,2/0,3 va mdu 3 cd lugng chay dao Sds /Sn = 23/0,3 cd dd thi bien thien cua lyc ma sat Fx va luc ma sdt dj hudng Fy nliu fren Hinh 7.
a/Mdu 2, 5'fl'y5„= 19,2/0,3
a/Theo phuong chay dao b/Theo phuong chay dao dgc ngang Hinh 5. Phuong chuyen dgng ciia mau do
3.1 Kit qud thuc nghiem tinh di hudng ma sdt theo phuffng chay dao doc
Kdt qua thyc nghiera khdo sdt vdi SJS„ = 15,4/0,3 dugc thd hien fren Hinh 6.
,l>i|mi|iij/ ^^m^m^wm\tm^m
b / M d u 3, S'rfj/Sn = 23/0,3 Hinh 7. D6 thj luc raa sat di hudng raau 2 va mau 3
Tir dd thi Hinh 6, 7 cho thdy cd sy xudt hien luc ma sdt theo 2 phuong X va Y mac dii m l u chuyin dong theo phuong X, dieu nay the hicn su t6n tai ciia tinh dl hudng ma sdt be mat. ;j,a m duac tdng hap frong Bang I. * ^
ir^is rt^llii Khoa hgc va Cdng nghe 132 (2019) 046-050 Jang 1: Gia fri luc ma sat theo cac phuang khi thay
loi lugng chay dao dgc Cac thong s6 U c F . O T LiicF,<N)
F..m
Mau 1 15,4m/ph 4,268 1,744 4,61
Mlu 2 Sdi — 19,2m/pli
4,962 0,653 5,0
Mau 3 Sd3 = 23m/ph
5,64 0,077 5,64 Tir Bang 1 cho thay cd su phu thugc ciia lyc ma sat bd mat vao lugng chay dao dgc. Khi lugng chay dao tang tir 15,4m/ph den 23m/ph thi luc ma sat Fx tangtu 16,3% - 32,1% nhung lyc ma sdt di hudng i ^ gidm tir 6 2 , 5 6 % - 9 5 , 6 % .
3.2 Kel qud thuc nghiem tinh di hir&ng ma sdt theo phuffng ngang hu&ng gia cong
K6t qud thyc nghiera khao sat ma sat be mat vdi SAn = 15,4/0,3 dugc did hien tren Hudi 8.
Cac gia fri do ma sdt fren Hinh 8 cho thdy hai thanh phdn ciia lyc ma sat cd gia fri trung binh Id: F^
= 6,371N, Fy = 6,05N vd dd thi lyc ma sat dieo thai gian tudn theo nguyen tac chung.
Van tdn tai thanh phan lyc ma sat di hudng Fy cd phucmg vudng gdc phuong chuydn ddng do X (nhimg Fy lai triing phucmg chay dao dgc), Gia tri Fy kha nhd, dao ddng quanh gid fri 0,05N vd Fy = 0.78%
Fx.
Tucmg ty vdi mdu 2 co lugng chay dao Sj2 /S„ = 19,2/0,3 (m/ph) va mdu 3 cd luong chay dao Sd3 /S„ = 23/0,3 cd do thi bien thien eua lyc ma sdt Fx va lyc ma sat di hudng Fy nhu tren Hinh 9.
Til' cdc dd thi Hinh 8, 9 cho thay sy xuat hien lye ma sdt theo hat phuang X, Y the hien tinh di hudng raa sdt be raat. Gia tri lyc ma sat Fy nhd tir 0,78% - 32,9% Fx dugc thd hien fren Bang 2.
Tir Bdng 2 cho thdy khi mau do chuyen ddng ngang hudng chay dao dgc, liic raa sdt bien thien theo lugng chay dao. Gid tri lyc ma sat tdng tai lugng chay dao Sd2 Id nhd nhdt Fm« = 77% - 85%. cua gid fri luc raa sat tdng d hai lugng chay dao cdn lai mac dii gia tri di hudng Fy la ldn nhat.
Bang 2: Gid tri luc raa sat theo hai phuang khi mdu chuyen dgng ngang hudng chay dao dgc.
Hinh 8. Do thi luc raa sdt di hudng mau 1 Sdi /Sn = 15,4/0,3.
Cic thong so
Fxm
F-yfN) i^™,(N)
Mau 1 Sdi = ]5,4ni/ph
6,371 0,05 6,371
Mau 2 Sd2^
19,2m/ph 4,665 1,534 4,91
Man 3 Sil3 = 23 m/ph
5,756 0,382 5,769 Tinh di hudng ma sat be mat khi cd chuyen ddng tuong ddi dugc the hien thdng qua dac tnrag di hudng adh nhu fren Hinh 10.
b/ Mdu 3, Sds/Sn - 23/0,3 Hiiih 9. Dd thi luc ma sat di hudng raau 2 va mau 3
Hinh 10. Dac trung di hudng bd raat adh Tren Hinh 10 cho thdy khi mau do chuydn ddng vdi van tdc v dudi tac dyng ciia tdi frgng P, xudt hien lyc raa sdt Fmsi co phuong ngugc chieu v vdi gdc lech adh (tfl iPdfe = Z^)- ^^ ~ ^^^ ™^ ^^^ ^^^° phuang ngugc chidu chuyen ddng (phuong chay dao dgc hoac ngang). Fy - Luc ma sat theo phuang vudng gdc chieu chuyen dgng.
Nliu vay, tinh di hudng ma sat be mat dugc xdc djnh thdng qua sy tdn tai gdc adi, (dac tiung ciia dj hudng ma sdt bd raat) hgp bdi phuong chuydn dgng va luc raa sdt tdng (luc ma sat thyc tg). Dac tinh dj huong cua raa sat bd mat cua mau thep C45 dugc raai linh the hien trong Bang 3.
Tap chi Khoa hi
Bang 3: Ddc tinh di hudng Odh cua raa sat be raat theo hai phuong chay dao
CCdl, adi: doc adh n,an^
Mau 1 22,2"
0.45'=
Mau 2 7,41"
18 22°
Mau 3 0.570 3.78«
Hinh 11 the hien dac tinh di hudng raa sat be raat khi lugng chay dao dpc thay ddi
Tir Bang 3 va dd thi Huih 11 cho thdy, chuyen dgng raau thir theo phuong chay dao dgc tinh di hudng giam tir 22° - 1" khi tang lugng chay dao, Khi chuyen ddng theo phuang chay dao ngang dac tinh di hudng ttdh cd tirdi phi tuyen cao va gid fri (%/,_„ga„g Idn n h i t ddn 18".
Hinh 11. Dd thi dac tinh di hudng be mat theo hai phuang chay dao
4. Ket luan
Be mat tiep xiic cua cac cap raa sat dugc gia cdng bang cdc phuong phap cdt ggt ndi chung vd phuang phuong mdi tinh ndi rieng, khi chuySn ddng tuong ddi, xudt hien hien tugng ma sat di hudng. Gid fri di hudng cua luc ma sdt phu thugc vao cac thdng sd cdng nghe gia cdng va duac dac trung qua gdc adh (dac tinh di hudng).
Thay ddi lugng chay dao dgc trong pham vi thyc te tir 15,4m/ph - 23m/ph khi mdi tinh bg mat ma sat thi luc ma sat tdng thay ddi tir 8% - 22,3% theo phuang chay dao dgc va 17,5% - 30%. theo phuang chay dao ngang,
Trong pham vi thay ddi ciia lugng chay dao nghien cim ciing nhu phuong chay dao, lyc raa sdt di hudng Fy cd gid tri thay ddi trong khoang 0,78% - 40,86 % cua lyc ma sat chinh Fx.
Dd tang hieu sudt lam viec (.: cap ma sat trong didu kien gia cdng thuc td cdn lun chon chuyen dgng tao hinh, phuong chay dao va gi^i tn luang chay dao phii hap khi gia cdng chg tao b l raai ma sat, dac biet khi raai tinh chi tidt ak cd gia tn lyc ma sat va oai, theo yen cau.
Nhu vay, sy tdn tai tinh di hudng cua ma sat be mat Id thyc ta. Tinh di huong nay phu thudc vao che do gia cdng va hudng gia cdng. Ma sat di hudng se gay mdt on djnh ciia chi tidt theo phuong vudng gdc vdi chuyen ddng, gay rung dgng ddng thdi gay radn eho cho cac chi tidt ddra nhiem chirc nang han che chuygn ddng ngang nhu vai true, vai va gd chuydn ddng quay idng khdng, cac phanh ham Id xo...Trong qud frinh lam viec, viec mdn va gdy cac phanh ham.
Id xo thudng xdy ra va la sy cd nghiem ttgng can phai franh va can duac quan tam khi bdo duong va thay the.
Ldd cam on
Nghien ciiu nay dugc tai fra bdi Trudng Dai hpc Bach khoa Ha Ndi frong dd tai ma sd T2017-PC-049.
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[2] Nguyin Anh TuSn, Nguyen Van Them, ky thudt raa sat va k^ thuat nang cao tuSi tho thiSt bi, NXB khoa hoc & kythuat, 1990
[3] Mr. Kamlesh Pal! and Vaibhav Shivhare, The Influence of Cutting Parameter of Surface Gnnder on the Surface Finishing and Surface Hardness of Structural Stee, Volume 1, Number 1, December, 2014, pp 11-14
[4] Amandeep Singh Padda, Sadsh Kumar, Aishna Mahajan, Effect of Varying Surface Grinding Parameters on the Surface Roughness of Stainless Steel, bitemational Journal of Engineering Research and General Science Volume 3, Issue 6, November - December, 2015.
[5] Pham Van Hiing, Nguyin Phuong, Co s cu, NXB khoa hoc ky thuat, 2006
I may cong [6] Nguyin Trirong Sinh, Nguyin Huu Thanh, Tap chi
cakhi.so l+2,2018,pp 40-46
