NGHIEN CUfU-TRAO D 6 I
NGHIEN c u t ; D O BEN BAM DINH CUA L O P PHUN PHUC HOI VOII KIM LOAI NEN CHI TIET TRUC BANG P H C O N G PHAP PHUN NO
STUDY OF BOND STRENGTH OF THE COATINGS ON THE SURFACE OF THE WORKPIECE CAMSHAST BY DETONATION SPRAYING METHODE
TS. Dinh Van C h i ^ n \ ThS. Pham Van Lieu^
'TrUcfng Dai hoc Mo Dia ehat
^TrUdng Dai hpe Cong nghiep Sao Do
TOM TAT
Phun no Id mdt phUdng phdp phun phuc hoi chi tiet rdt co hieu qud do tinh bdm dinh cua ldp phun vdi ldp nen. Bdi bdo trinh bdy ket qud nghien cdu do ben bdm dinh cua ldp phu hot Cr20Ni tren mdu vd tren chi tiet true cam xe tdi. Bd nghien cdu thiet ke che tgo dogd sung phun bdo ddm cdc thdng so tdc do dich chuyen cho ddu phun vd khodng cdc phun. Dd tie'n hdnh phun vd xdc dfnh do ben bdm dinh cua ldp phu. Ket qud khang dinh do ben bdm dinh ddp dng yeu cdu chdt ludngphuc hoi chi tiet. Sdn phdm phuc hoi da dUdc dng dung tren xe tdi ldm viec tgi Cong ty Than Qudng Ninh.
Detonation spraying is an effective methodefor restore machine parts dimention, that is because of the bond strenghs of the coatings on the surface of a workpiece. This paper present the study results of the coating layers Cr20Ni5 powder on the Camshaft. The fixture is designed and produced for control of velocity and distance among detonation gun and surface of workpiece. The study was determined effects of conditional technology on adhesion in the coating layers. The project suggested that it has been applied for mechanical manufacturing companies in VINACOMIN Quangninh.
1. Gl6l THIEU PHUN N O
Phun no, mot dang eiia phun nhiet khi oxy - khi chiy toe do cao (High Velocity Oxy-Fuel-HVOF), la c6ng ngh^ phun phu be m^t chi tiet vdi nhieu muc dieh khic nhau, trong do, dung de phuc hoi cac be m?t chi tiet mon hong.
P h u o n g p h a p p h u n n o .
Bdng 1. Ddc tinit ky thudt cua phun no.
Nguon nhiel Chieu day phun phii, mm Do xop, % Do bam dinh, MPa Vat li?u phun Toe dp hat phun, m/s Nhi?I dp khi chay, "C Khoang each phun. ni Toe dp dong khi phun m/s Nhi?t dp tren be m^t, "C Chl phi
I'hun nhiei - No Su no hon hop oxy- nhien lieu 0,01-2
<I~0.5 Rat lot >70 Cac v?t li?u bpl 700-1200 2800-4000 2,00 3000 200 Trung binh
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dupe sd dung rgng rai trong tat ca cae nganh eong nghiep; Che tao may, hang khong, ten Ida, dong tiu, dau khi, luyen kim w... Phun no co cie Uu diem (bang 1): Gia thanh ha, nang suit lao dpng eao, to ehdc min d i e it xop, dp ben b i m dinh tot, CO the cho ldp phu diy.
Mpt trong cie yeu cau ehat lUpng eua eong nghe phun phu la ldp phu phai diipc bam dinh chat vdi be mat kim loai nen. De dat dupe dieu do, ap suat cua cie hat phun tai thdi diem tiep xue vcfi be mat vat dupe phun phai du ldn, nhd nang
lupng va dap, lam nong chiy be mat ti^p xuc v i tii dd tao sU lien ket ben vdng giCta vat lieu phun va vat lieu nen.
Dau phim no (hinh I) gom cac bp phan chinh sau: Mot buong dot, dUpc dan cie khi oxy va khi chiy l i m ngudn nang lUpng, bugi kich Ida, cac binh ehda bot phun, he thong van dieu khien, cac binh ehda khi, he thong dieu khien dien va thuy lUc. Dau phun no dUPe d i t tren mpt gii dd CO k h i n i n g dieu ehinh dUpc 3 chieu, phu hpp vdi vi tri phun eua ehi tiet can phun.
Hmh L Sd do ket cdu ddu phun no vd qud trinh phun.
2. CO SO HINH THANH LOP PHU
Hinh 2. Sd do hinh thdnh ldp phu.
Nguyen ly hinh t h i n h ldp phun phu no:
Khi oxy v i axetylen dupe trpn vdi mpt ty le nhat dinh, du tao hien tUpng no, dupe bugi kich boat, hdn hpp khi bi chay dot ngpt, gay hien tUpng no.
San pham cua p h i n dng chay la khi co ap suat cao v i nhiet do cao. Khi ehay dan nd nhiet trong nong, keo theo khi tro va bpt phun. Bpt phun dupe gia tdc va gia nhiet den nhiet dp nong chiy.
ehung bay ra khdi nong va den b i m vao mat chi tiet. Toe dp dau nong cang ldn, toe dp bay eua bpt phu cang eao, toe dp va dap vdi be mat vat pbii cang cao. Khi cac gipt kim loai long va dap len be mat chi tiet, ehung se bam vao v i dong die. Toe dp va dap vdi ehi tiet phu thupc vao khoing cich td dau sung phun den chi tiet.
Hinh 3. Hinh to chiic tevi Idpphu.
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Ldp phii dupc hinh thanh tii tdng khoi nho kim loai phu, dupc dap sit nhau va chong chat len nhau, hinh thanh I ldp phu (hinh 3). Chi tiet phai dupe quay v i dau phun phii dich chuyen, ldp phu CO d^ng xoan xep chong len nhau. De tang dp b i m dinh, hi mat chi tiet phii dupe lam saeh v i cd the lam n h i m . Khi kim loai phu b i m dinh d tren be mat chi tiet d nhiet dp cao, se ed hien tUPng khuech t i n eua cic nguyen td chat phd vio kim logii nen. Q u i trinh khuech tan cang lam ting dp bam dinh gida 2 ldp kim loai va giCta cac ldp phu vdi nhau.
Ngoai ra dp ben b i m dinh con phu thupc
hinh d i n g hinh hoc ehi tiet phun. Dp bam dinh eon phu thupc vao hinh dang be mat chi tiet. Cae ehi tiet phang cho khoang cich tUPng doi dong deu trong qua trinh phu, cdn chi tiettron xoay tao nen khoang each td dau phun den diem va d i p k h i c nhau, dUdng kinh ehi tiet cang nhd, sU khie biet khoing each tUPng doi cang ldn, nen can khong ehe de tao sU bam dinh ddng deu. NhU vay, dp hpi tu chat phun phu thupc vao b i n kinh eong chi tiet phun. Che dp phun phai phdi hpp sU dieh ehuyen eua dau phun va ehi tiet phun. Tde dp quay cua chi tiet va tdc dp dieh chuyen eua sung phun phai b i o dam cac vung dUpc phun chong len nhau, khong dUpc co khoang each.
(3) Hinh 4. Quy dgo phun vd sUphdn b6 chat phu
Do cac phan td chat phun mang nang khdi bot phu, A^- tiet dien ngang trung binh eua lupng eao va dap vao mat chi tiet can phun, nen khoi bpt phu.
tdc dp va dap cd tinh quyet dinh den dp b i m dinh
vat chat tren be mat, biet rang E = l/2mV^ Ap lue eua khdi bpt tie dung tai vung tiep xue dupc tinh (5]:
Tdc dp va dap cua cae phan td chat phun p c, cd the tinh theo eong thdc sau [3]: ^ " Pp^.?^'p(^ + - ^ )
Trong do: c v i r ; = 9 y C ^ ( r , - f i ) + 5 (1) c^^ la toe dp am thanh
cua vit lieu phu va vat Trong do: V - tdc dp eua phan td va dap, Heu nen.
m/s, C - ty nhiet, eal.g' "C '; t, - nhiet dp phan td tai thdi diem va dap, "C; t^ - nhiet dp ndng chay cua kim loai, "C; S - enthalpy, cal.g '.
Dpng lupng cua khoi bpt phun dUpc xic djnh theo [4]:
dv dv uo - — - = w-v- — - - —
" dt " " dx
CnAM^'V^
Hinh 5. M&u thit do hen bdm dinh.
(2) 3. P H i r O N G P H A P T H l J C N G H I E M
Trong do: m - khoi luong trung binh cua a. Vat lieu phun: ThUc nghiem sC( dung vat's
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lieu bgt hgp kim Cr20Ni3, co thanh phan 20%Cr, 2,5-3,0%Ni, con lai la Fe. Do hat trung binh 40|im
< 6 < lOO^im.
b. Mau vat lieu phun thfi nghiein: Muc dich phun phuc hoi true cam, nen thanh phan mau tuong duong v6i thep 40Cr.
c. Cach xac dinh do ben bam dinh giiifa Idfp phu vofi kim loai nen: Sif dung phuong phap keo chot
(Hinh 5). Sau khi lap rap chft va ao ngoai, ngUdi ta phun len be mat chung. Ti^p sau dUa len thiet bi de keo chot ra khoi ao ngoai. Do ben lien ket dugc tinh theo cong thiic:
4P (4)
Trong do:
P - LUc keo p h i buy, MPa;
dien 16 O,
d - Dudng kinh tiet
Htnh 5. Chl tiet cdn phuc hoi vd thiet bf phun no.
d. Thiet ke che tao do ga: do ga sung phun va do ga Chi tiet phun phai dUpe ga len do g i , chi tiet chi tiet. dupc quay vdi mpt tdc dp nhat dinh.
Sung phun dupe dieu chinh 3 chieu: Chieu Toe dp quay cua chi tiet va toe dp dich eao tam sung n i m tren cung mat phang ngang cua chuyen ngang eua sung dUpe khong ehe theo dddng tam true ehi tiet va true tam sung vuong goc vdi true kinh chi tiet. Vdi chi tiet true cam, c6 the dieu ehinh chi tiet; dieu ehinh khoang each td dau mieng siing so vong quay td 70-90vg/ph, toe dp dich ehuyen den be mat chi tiet va eo the dich chuyen ngang. ngang cua sungl,7mm/vg.
" ' > .
Hinh 6. Dogd sungphun vd dogd chi tiet phun.
Cong nghe phun phu thUc hien nhU so do hinh 7.
Che do phun dugc thuc hien tren co sd vung toi Uu cong nghe da riit ra tU nghien ciiu:
- Toe dp phun tai dau nong dieu chinh trong khoang 800~1200m/s;
- LUu lugng bgt phun : 400-500g/s;
- Khoang tii dau nong den chi tiet: 100~300mm.
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Kiem tra chi tie't trudc khi phun (Vat li6u, kich thu6c va trang thai bd mat
JTinh toan, lua chon che do c6ng|
I Kiem tra h$ thong thie't bi phun | i Thuc hien phun n6 \
' T
I Gia c6ng nhiet j I Gia cOng ca khi'^
I Lam sach j I Ki^m tra cha't luong \6p phu |
Htnh 7. Sd do cong nghe phun phd phuc hoi true cam.
4. Kf T QUA NGHIEN CUtJ
Da lip ke hoach nghien cdu thd nghiem xac dinh dp ben bam dinh theo pbUong phap quy hoach thUc nghiem, tien hinh do va xd ly so lieu. Ket qua xac dinh dupc ham tdi Uu gifla dp ben bam dinh a vdi lUu lUpng phun x va khoing each phun y:
= 14.561-0.0925.Y-0,0239)'-3,411,10"'.Y'-7,9556.10"'xv-3,411.10V (5) Tii so lieu do vi ham do ben toi Uu (5) da xay dUng eae bieu dd 3D va 2D (hinh 7-12) thiet lip quan he gifla dp ben bim dinh vdi cac thong so cdng nghe. Cd the sd dung cic bieu do do de xac dinh vung thong so cong nghe toi Uu cho eac trUdng hpp phun phu khac nhau.
Nhu v?y, dp bim dinh chiu inh hUdng rat ldn cua lUu lUpng va tdc do phun. Doi vdi vit lieu phun Cr20Ni5, ehpn lUu lUpng phun tren 500g/s vdi tde dp phun td 1000 den 1250m/s cd the cho dp bim dinh tot til 65 ~70MPa dap dng yeu cau doi vdi dp ben ldp phu. Tai vung thong so nhu vay, vdi toe dp phun tao nang lupng va dap de vit lieu phun bam vio mat chi tiet, mat khae, dong tbdi.do nang lupng va dap, nhiet dp khoi kim loai phun tang ed the dat den nhiet dp ndng chay, nhd vay cing lam
tang dp bam dinh gifla vat li?u phun va vat lieu nen. ^
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Hinh 7. Quan he do ben bdm dinh vdi khodng cdch vd lUu lUdngphun.
Hinh 8 Vitng phdn bd toi Uu do ben bam dinh lot toe do phun
va khoang cach phun.
Hinh 9. Phdn vitng thong so toi Uu do ben bdm dinh vdi lUu lUdngphun
vd tdc do phun.
Hinh 10. Phdn viing thong so toi Uu do ben bdm dinh vdi khodng cdch
phun vd lUu lUdngphun.
W''' W//
P:X
JO 300 i j o ]'i(i 3511 3aD
' ,/
/ ,.
'X
...
/ / /
MO 4!0
Xy
0 180 500 i
• >««>
• (MOD Z^<iooo _ | < 1000
" • < 2000
Hmh 1L Phdn vitng thong s6 toi Uu do bin bdm dinh vdi do xop vdi do xop
vd tdc do phun.
Hinh 12. Phdn vitng thong so toi Uu do ben bdm dinh vdi lUu lUdng vd toe do phun.
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Tren co sd thUc nghiem tren mau, cie tie dUdi 360g/s.
gii da tien hinh phun phu tren true cam xe tai cua Md Than Quang Ninh vdi cie thong so eong nghe da dupe xic dinh. Ket q u i thd nghiem da dUpc ep sd sin xuat xac dinh, cd dp ben b i m dinh tdt, tuoi thp true cam tUPng dUPng true cam mdi eua Trung Quoc v i gii thanh ha.
D i thiet ke v i che tao dupe do ga phun d i p dng yeu cau cua cong nghe phun no.
5. KET LUAN
Dp ben b i m dinh cua ldp phu vdi vat lieu nen phu thupc ehinh v i o toe dp va dap eua eac hat phu vdi be mat chi tiet, thong qua toe dp dau phun va khoing cich phun; vdi toe dp phun tren l.IOOm/s, anh hUdng khoing cich phun khong ldn; nhUng anh hUdng eua lUu lUpng ban che
Cd the sd dung eac do thi de tra cdu thong so cong nghe toi Uu eho phun hot Cr20Ni5 tren eac true khac nhau, cd the sd dung phUPng phap cua bai bao de xic dinh thong so cong nghe tdi Uu cho phun nd phuc hdi eac ehi tiet khie vdi eac vat lieu khic. •
Ngay nhan bai: 15/12/2012 Ngay phan bien: 10/01/2013
NgUdi phan bien: PGS, TS. Dinh B i Tru, Hpe vien Ky thuat Quan sU
Tai lieu tham khao:
[l].Dinh Van Chien, Le Van Long, Nguyen ManhTue (2010), Nghien cdu anh hudng toe do phun den sU hinh thanh, dp ben bam dinh va dp xop ldp phu trong cong nghe phun no, Tuyen tap Hoi nghj Khoa hoc toan quoc, Co hoc Vat ran bien dang lan thd miidi. Thai Nguyen, 12-14/11/2010.
[2] Hoang Tiing (2006), Cong nghe phun phii va ilng dung, NXB. Khoa hoc & Ky thuat. Ha Noi.
[3]. E. A. Astakhov, (2008), Controlling the properties of detonation-sprayed coatings' Major aspects, Journal Powder Metallurgy and Metal Ceramics, Volume 47, Numbers 1-2 / January, 2008.
[4]. J.R. Davis Davis & Associates, (2004), Handbook of Thermal Spray Technology, ASM Thermal Spray Soci- ety.
[5j. Sulzer Metco, (2006), Thermal Spray Materials Guide.
[6], M.Grujicic, C.L.Zhao .C.Tong .W.S.DeRosset, D.Helfritch, 2003, Analysis of
theimpact velocity of powder particles in the cold-gas dynamic-spray process, Department of Mechanical En- gineering, Clemson University, USA, Army Research Laboratory.
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