Bai bdo nay gidi thieu nghien Clhi vd dnh hudng cua nong dp bpt titan trong dung djch dien moi ddn lugng mdn cua dien cue TWR, ndng suit bdc taeh vgt liduMRR vd nhdp nho bd mat gia cong
Trang 1K H A O SAT A N H H l T d N G CUA NONG D Q B Q T TITAN T R O N G DUNG DICH DIEN M O I D E N NANG SUAT VA C H A T L l / O N G B E M A T GIA C O N G T H E P SKD61 BANG PHU'ONG PHAP TIA Ll^A DIEN V d l DIEN ClTC D O N G
Bdnh Tiln Long', Ngd Cud^g^ Nguyin Hiru Phdn*', Tr^n Quang Cong^
'Trudng Dgt hoc Bach Ichoa Ha Npi 'Truang Cao dang Kinh te - Ky thudt - DH Thdi Nguyen
^Truang Cao dang Ca Ichi Luyen lam Thdt Nguyen
TOM TAT
Phuang phdp gia cong bang tia Ida didn (EDM) dugc img dyng rdt phd bidn trong cdng nghiSp ehd tao dyng cy, khuon mlu va hang khong Nghien ciiu ndng cao nang sudt va chdt lugng gia cong
bang phuang phdp tia lua dien vi vdy co •} nghia thuc tien to Imi Bai bdo nay gidi thieu nghien
Clhi vd dnh hudng cua nong dp bpt titan trong dung djch dien moi ddn lugng mdn cua dien cue (TWR), ndng suit bdc taeh vgt lidu(MRR) vd nhdp nho bd mat gia cong (RJ khi gia cong thep SKD6I bang phucmg phdp tia lira dien vdi di?n cyc ddng phan cue ngugc Kdt qua cho thdy, khi trpn hot titan vao dung dich dien mdi da lam giam lugng mon dien cue va tri s6 nhdp nho bd rngt, tang ndng suat boc taeh vgt lieu
Tir khda: EDM, MRR TWR thepSKD61 bpt titan
DAT VAN DE
Gia cdng bang tia lua dien (EDM) id phuong
phdp gia cdng khdng truydn thdng dugc sii
dung phd bidn de gia cdng cac logi vgt lieu
ddn dien khd gia cdng hoac cd hinh dgng bd
mat phurc tap Mac dii cd nhidu uu didm
(khdng gay ra bien dang tren chi tidt gia cdng;
rung ddng, dng suat co hoc, tidng dn khdng
xuat hien trong sudt qua trinh gia cdng )
nhung phuang phdp nay lgi tdn tai mgt sd
nhugc diem ca bdn lam han ehd khd ndng ling
dyng ciia nd nhu: ndng suat gia cdng thap,
chat lugng be mat sau gia cdng khdng cao [4]
Mgt sd kdt qua nghien ciru gan day cho thay,
vide trdn bgt kim loai hodc hgp kim vao trong
dung djch dien mdi ciia qua trinh gia cdng tia
Ilia didn Id mgt giai phap kha thi de khde phuc
nhiing han ehd tren
Trong cdng nghg EDM viec su dung bdt kim
logi thich hgp trdn vao dung djch dien mdi se
lam giam dg ben each dien cua dung dich
di^n mdi va lam tang khe hd phdng didn giu"a
dyng cy - phdi [9], tu dd cdi thien ndng suat
bdc taeh vat lieu vd chdt lugng bd mgt gia
cdng: ndng suat bdc taeh vat lieu tang, tri sd
nham va cac vdt nut te vi tren bd mat gia cdng
' Tel: 09S3 7S3844 Email- Phankicn@gmall.com
giam, giam chieu day ldp vat lieu be mat chi tiet bj dnh hudng do nhiet [2], [5] Viec trgn cdc logi bdt Cu, Fe, Al va C vao dung dich dien mdi dd gia cdng thep vdi dien cue Id Cu
da nang cao kha ndng danh thiing dien mdi, khi tdng ndng do bgt thi nang sudt bdc tdeh tdng [5] Khi trgn bgt graphit vao dung djch dien mdi vdi ndng do 4g/l da Iam khe hd phdng dien tdng trong khi didn dp phdng dien Igi giam, do dn djnh ciia qua trinh gia cdng dugc ndng cao vd nang suat gia cdng tang 60%, lugng mdn didn cyc gidm 28% [6] Trdn bdt Si vao dung djch dien mdi de gia cdng thep SKD61 da nang cao dugc chdt lugng bd mat gia cdng [7] Khao sat vide trgn bpt Al vd bdt SiC vao dung djch dien mdi de gia cdng thep SKDI1 vd hgp kim Ti-AI-4V da cho kdt qua Id nang suat bdc tdeh vat lieu tdng va trj
sd nham be mat gidm [8J Luc tdc ddng len be mat phdi giam dugc cho la nguyen nhan ddn ddn tri sd nhap nhd giam va lam tang do bdng
bd mat gia cdng khi trgn bgt Si vao dung djch dien mdi [11] Anh hudng ciia viec sii dung bdt kim loai trong cdng nghe EDM ddn chat lugng be mat gia cdng cdn phu thudc vdo loai vgt lieu gia cdng: trgn bdt AI cd kich thudc trung binh vdo dung dich didn mdi khi gia cdng thep SKH-51 da cho do bdng bd mgt cao nhung khi gia cdng thep SKH-54 lgi nhan
Trang 2dugc dp bdng bd mat thdp [7] Khdo sat chat
lugng bd mgt cua thep SKDll khi gia cdng
bdng EDM cd n-gn cdc logi bdt Al, Cu, Cr va
SiC vdo dung dich dien mdi cho thay: chat
lugng gia cdng bj dnh hudng dang ke bdi
ndng dg, kich thudc, khoi lugng rieng, dien
trd vd do ddn nhidt ciia bdt; vdi ndng dg bgt
khdng ddi thi nang suat bdc tdeh vat lieu se
dat cao nhdt khi kich thudc bdt nhd nhdt Trj
sd nhdp nhd be mat gia cdng cdn phu thudc
vao di?n tich vd thiri gian gia cdng: Ra thay
ddi tu 0,09 pm den 0,57 fim khi dien tich gia
cdng thay ddi tu 1 cm^ den 64 cm" [9]
Nhiing ket qud nghien ciiu trdn cho thdy rdng
viec su dyng bgt kim loai thich hgp trgn vdo
dung djch didn mdi trong gia cdng tia liia dien
Id cdng nghe day hua hen Tuy nhien, can cd
them nhidu nghien riiu, khao sat ve ITnh vyc
nay de hodn thien cdng ngh^ va cd thd dugc
chap nhga iing dyng trong thuc tien sdn xudt
Trong nghien cdu nay, cac thi nghidm dugc
tidn hanh vdi su thay ddi ndng dp bdt titan
trong dung djch dien mdi Id dau khi gia cdng
thdp SKD61 bang phuang phap EDM sir
dung dien cue ddng dd phan cue ngugc
Nang suat vd chat lugng ciia qua trinh gia
cdng dugc danh gid thdng qua cdc dgi lugng:
ndng suat bdc taeh vat lidu, lugng mdn dien
cue vd dg nhdm be mat gia cdng
THIET KE THI NGH1$M
So do thi nghiem dugc trinh bay d Hinh 1,
qua trinh phan cue dii gia cdng Id phan cue
ngugc (didn cue (-»-), phdi (-)) nhdm khao sat
su thay ddi cua MRR, TWR vd R, trong
trudng hgp gia cdng cd bdt trdn trong dung
djch dien mdi Thi nghiem trdn may xung
dien CNC- AG40L (Hang Sodick, Inc USA)
cua Trung tam thi nghiem Trudng Dgi hge Ky
Bdng 1 Cdc thong
thuat Cdng nghiep Thai Nguyen Vat lidu mdu thi nghiem la thep SKD61 (TC JIS - Nhgt Ban) nhiet luygn dgt do ciimg HRC = (48-^52), mau cd kich thudc 45x27x5mm Vgt !i?u didn cyc dyng cu la dong Cl 100 (99,9%) cd dudng kinh 25mm, sd lugng 10 chiec Bgt titan cd kich thudc cd hgt 45 pm dugc lya chgn dd trgn trong dung djch dien mdi Dung djch dien mdi Id dau bien the HD-1 ciia Hdng ELECTROL Duy tri sy ddng ddu vd khdng
bj Idng dong ciia bgt titan trong dung djch dien mdi bang co cau khuay gdm: dgng co khi nen cd tdc dg quay 500 vdng/phiit, canh quat khuay cd dudng kinh 105mm Dung moi dugc cung cap vao viing gia cdng bdng bom A303 cua Trung Qude cd cdng sudt 600 lit/gid, dudng kinh vdi phun 08mm Cac thdng sd dugc lya chgn de nghien cdu (Bdng 1) dua tren ca sd mdt sd nghien cdu tii trudc
Do khdi lugng ciia phdi trudc vd sau khi gia cdng bang can dien tu AJ 203 (Hang Shinko Denshi Co LTD - Japan), khdi lugng Idn nhat
ma can cd the cdn dugc Id 200g, do chfnh xac 0.001 g Trj sd nhdm be mat gia cdng (Ra) dugc do bang may do bien dgng kidu dau do tidp xiic SJ-301 (Hang MITUTOYO - JAPAN), chidu dai chuan do Id 5mm, thyc hien 3 lan do tren mdi mau thi nghiem vd ket qud dp nhdm la gia trj trung binh ciia mdi lan do
Hinh I Scr do Ihl nghi?m
so cong nghe gia cong
1 Cuong dp ddng dien xung (A)
2 Thai gian xung (^is)
3 Thai gian ngimg xung (^s)
5 Phan cyc
6 Thdi gian gia cong ( ph)
7 Dien dp (V)
15
50 +
15
150
Trang 3KET QUA VA THAO LUAN
Anh hudng den nang suat bdc taeh vat lieu
(MRR)
Ndng sudt boc taeh vgt lieu (MRR) dugc xac
djnh bdi ty sd giiia hidu khdi lugng vat lieu
phdi trudc va sau gia cdng vdi thdi gian gia
cdng:
W,-MRR =
pi -^.\Q00mm^ 1 phut
(1) Trong dd:
W, - Khdi lugng mlu trudc gia cdng (g)
Wf- Khdi lugng mdu sau gia cdng (g)
T - Thdi gian gia cdng cho mdi ldn chay thu (t
= 15 phut)
p - Khdi lugng ridng ciia vdt lieu mdu (p =
7.81g/cm^)
MRR la dgi lugng lien quan tryc tidp ddn thdi
gian che tgo san pham, tang MRR se giiip riit
ngdn dugc thdi gian gia cdng chi tidt Xdc
djnh gid trj MRR cho 5 thi nghidm, mdi thi
nghidm Igp 2 ldn Kdt qud (Bdng 2 vd Hinh 2)
cho thay vide trdn bdt titan trong dung djch
dien mdi da lam tang MRR so vdi gia cdng
Bdng 2, Ket qud ndng
khdng cd bdt Nguydn nhan tdng MRR cd the gidi thich nhu sau:
- Khi bdt titan xuat hidn trong dung dich dien mdi da tgo them rat nhidu cau ndi phdng tia lua dien lam tang mat do tia lua didn cung tham gia cdt dan den MRR tang
- Bdt titan cd kha ndng dan dien tdt dugc trgn vdo dung dich didn mdi se iam giam do ben each didn cua dung dich didn mdi tii do ldm giam tieu hao ndng lucmg danh thiing dien mdi Dieu ndy ldm tang nang lugng gia cdng dan den lam tang MRR
- Khi ndng do bpt tang se dan ddn sd lugng cdc hat bgt xuat hien trong khe hd phdng tia lira didn tang ldm sd lugng tia liia didn sinh ra trong mgt lan phat xung ciing tang len va do bdn each dien cua dung djch dien mdi bi giam
di nen nang lugng dimg cho danh thung dung dich dien mdi ciing giam theo Khi ndng do hot Idn nhat 20g/l thi MRR cao nhat Wffi?n,ax= 1.699mmVphut (tdng 146,75% so vdi khdng cd bgt), tuy nhien khi ndng dp bdt qud cao cd thd xay ra hien tugng ngan mgch xuat hien trong qua trinh gia cdng gay tieu hao nang lugng gia cdng
sudt boc tdeh vdf lieu
TN
1
2
3
5
6
7
8
9
10
Wi
(S)
31.463
32.671
32.002
31.756
31.973
32.906
31.578
w,
(S)
31 365 32.594 31.89 31.658 31.798 31.71 32.702 31.388 31.027
MRR ( m m ^ h u t ) 0.837 0.657 0.956 0.837 1.383 1.494 1.579 1.741
1 622 1.776
MRIZ
(mm'/pliiit) 0.747 0.896 1.438 1.660 1.699
N ^ n g d S b6t(s/l) KJiong bot
5
10
15
20
v4d»iWWTi(fli
Trang 4Anh birdng din lirgng mon dien cue
Lu^g mdn diin cue (TWR) la dai lugng dugc
xac djnh bdi ty sd giira hieu khdi lugng vat
lieu dien cue trudc va sau gia cdng vdi thdi
gian gia cong:
T-T,
.\000mm^ /phut (2)
Trong dd:
T, - khdi lugng ban dau ciia dien cyc (g)
Tf- Khdi lugng dien cyc sau gia cdng (g)
t - Thdi gian gia cdng cho mdi ldn chay thu (t
= 15phut)
PT - Khoi lucmg ridng cua vgt lieu dien cue
(pT=8.94g/cm^)
Mdn didn cue xdy ra trong sudt qud trinh gia
cdng ldm dnh hudng ddn dp chinh xac thdng sd
hinh hge ciia chi tiet gia cdng TWR tang cdn
ldm tang chi phi san xuat do phai thay the dien
cue bj mdn
Kdt qua xdc djnh lugng mdn dien cyc (Bang 3
va Hinh 3) cho thdy:
Bang 3 Kit qud
- Khi dung dich dien mdi khdng cd hot thi
TWR la Idn nhat Nguyen nhan la cdc dien tir dugc hinh thdnh trong qua trinh ion hda chat dien mdi cd dgng lugng va ndng lugng cao se tac dyng len bd mat dien cyc gay ra xdi mon dien cyc ldn
- Khi trgn bdt titan vao trong dung djch dien mdi da lam TWR gidm Dd la do cdc hat bpt
di vao viing khe hd phdng tia lira dien cat ngang dudng di chuyen cua cac electron ve phia be mat dign eye Dieu ndy ldm giam ddng lugng ciia cac electron, cdc electron co nang lugng thdp hon tac dung ldn bd mat dien cue lam dien cue it bi xdi mdn hon
- TWR dgt gia trj nhd nhat khi ndng dd bgt la lOg/1, d didu kien nay kha nang ngdn can sir
di chuyen ciia cac electron la Idn nhat nen cdc electron se cd nang lugng nhd nhat khi tac dung len bd mat dien cyc
- Khi cac hgt titan xudt hien vdi ndng dp Idn hon cd thd tao thuan lgi dd mdt sd electron va cac hat bgt ciing tac dyng len be mgt didn cue ldm cho mdn dien cyc xay ra manh han vi thd TWR tdng nhe khi ndng do ldn hon I Og/I
lucmg mon dien cue
TN
1
2
3
4
5
7
8
10
Ti
(g)
136.867
138.549
138.549
139.831
141.197
138.976
138.198
135.893
131.259
T, (g) 136.726 138.411 138.457
139 738
137 095
1 4 1 1 1 3
138.875
138 098 135.795 131.155
TWR /phit) 1.051
1.029 0.686 0.694 0.619 0.626 0.753 0.746 0.731 0.776
1.040 0.690 0.623 0.749 0.753
Nong dO b$t (g/l)
Khong b$t
5
10
15
20
Trang 5Anh hudng den dg nham be mat gia cdng
Bang 4 Ket qud dg nhdm be mat gia cong
1 6.03 Khong bot
2 4.73 5
3 4.38 10
4 4.30 15
5 4.01 20
Nong i(/ b$t Ti (g\)
Hinh 4 Anh hu&ng cUa nong do bot den dp nhdm
be mgt gia cong '"
Kdt qua d Bang 4 va Hinh 4 cho thay dg
nham be mat gia cdng gidm khd ldn khi trgn
bgt titan vdo trong dung djch dien mdi (dd thj
cd do ddc Idn khi chuyen td gia cdng khdng
cd bdt sang gia cdng cd bdt trong dung djch
didn mdi) ddng thdi Igi gidm mgt lugng tuong
ddi nhd va ddu khi tidp tuc tang ndng dQ bgt
Cd thd giai thich nguyen nhan nhu sau:
- Khi hot xuat hien trong dung djch didn mdi
da ldm tang kfch thudc va md rgng vung
phdng tia liia dien va tgo didu kien thu§n lgi
cho qua trinh van chuyen phoi ra khdi vung ra
cdng [4] Cac hat bdt tdn tai trong khe hd
phdng didn lam tia lira didn bi phan chia
thanh nhidu tia lua didn cd nang lugng nhd
hon nhidu khi tham gia gia cdng [6] Didu ndy
da tgo ra cdc vdt ldm tren be mat gia cdng cd
dudng kinh vd chidu sau nhd hon dan ddn do
nhdm giam
- Ndng do bgt titan tang thi sd lugng hgt bdt
tdn tai trong viing khe hd phdng tia liia dien
cung tdng len, sd lugng cac tia lira dien dugc
tgo ra trong mgt lan phdt xung cung tdng ldn
lam i^'c "^"8 l^dng cua nidi tia giam xudng
ndn trj nhap nhd be mat cung giam theo [II]
Do nham Ra nhd nhat khi ndng do bdt titan la 20g/l, ndu tidp tuc tang ndng do bdt thi cd thd viec phdng didn bj can trd, hi$n tugng ngdn mach cd thd sd xudt hien nhidu hon lam cho qua trinh gia cdng khdng dn djnh vd do nham
bd mat gia cdng cd the iai tdng
KET LUAN Mpt sd ket luan nhan dugc tir ket qua khdo sdt anh hudng ciia ndng do bdt titan den nang sudt vd chat lugng gia cdng thep SKD61 bdng phucmg phdp tia lua dien vdi dien cyc ddng phan cyc ngugc:
- Ndng dg bgt titan trong dung djch dien mdi
Id thdng sd cdng nghd cd anh hudng khd ldn den hieu qua gia cdng ciia phuong phap tia Ida dien
- Ndng suat bdc tdeh vat lidu(MRR) tang khi tdng ndng do bdt titan: khi ndng do bgt tang
tir 0 len 20g/l thi WRR tang 146,75%
- Khi tang ndng do bdt trong dung djch dien mdi thi mdi ddu lugng mdn di?n cue (TWR) giam kha mgnh nhung sau dd cd xu hudng tang nhe Lugng mdn didn cue dat gid trj nhd
nhat TWRmm~ 0,623mmVphut vdi ndng dp
bdtlOg/1,
- Dp nhdm be mat gia cdng (Ra) gidm khi ndng dp bdt tdng: khi khdng cd bgt thi Ra -6,03pm, khi ndng dd bgt la 20g/l thi Ra=4,01pm
- Cac kdt qud nghien ciiu vdi mdt sd logi hot khde nhu: W, Si, Al, da cho thdy rdng ngodi dnh hudng ti'ch cyc den MRR, TWR, R, thi vide trdn bgt vao trong dung djch dien mdi cdn cd thd cho mgt sd kdt qua khac nhu: do cung td vi bd mat gia cdng tdng, cdu true vd hinh dang Idp bd mat cd chat lugng tdt Vi vgy can cd them nhirng nghidn ciru theo hudng nay ddi vdi bgt titan
- Ngoai ra cung cdn nghidn cuu dd lam rd cac van de nhu: do bdn va su phan bd deu ciia bdt trong dung djch dien mdi khi gia cdng
Trang 6T A I LIEU T H A M K H A O
1 W.S Zhao, Q.G Meng, Z.L Wang, The
application of research on powder mixed EDM tn
rough machining Joumal of Materials Processing
Technology, 129(2002), P 3 0 - 3 3
2 P Pecas, E Henriques, Influence of silicon
powder-mixed dielectric on con-ventional
electrical discharge machining International
Joumal ofMachine Tools& Manufacture,
43(2003), P 1465-1471
3 K.H Ho, S.T Newman, Slate of the art
electrical discharge machining Inter national
Joumal of Machine Tools & Manufacture,
43(2003), P,I287-1300
4 Fuller, E John, Electrical Discharge
Machining ASM Machining Handbook,
16(1996), P 557-564
5 A Erden, S Bilgin, Role of impurities in
electric discharge machining, Proc Of 2 P '
intemational machine tool design and research
conference,(1980), P.345-350
6 M.L Jeswani, Effect ofthe addition of graphite
powder to kerosene used as the dielectric fluid in
P.I33-I39
7 K Kobayashi, T Magara, Y Ozaki, T Yatomi,
The present and future developments of electrical discharge machining In proceeding of 2"''
intemational conference on Die and Mould technology, (1992), P 35-47
8 B.H Yan, S.L Chen, Characteristics ofSKDlI
by complex process of electric discharge machining using liquid suspended with aluminum powder, J Jpn Inst Light Met., 58(2004), P
1067-1072
9 P Pecas, c Henriques, Electrical discharge machining using simple and powder-mixed dielectric: The effect of the electrode area in the surface roughness and topography, Joumal of
materials processing technology 200(2008), P.250-258
10 Y.S Wong, U C Lim, 1 Rahuman, W.M Tee,
Near mirror-finish phenomenon in EDM using powder-mixed dielectric Joumal ofMaterials
Processing Technology, 79(1998), P.30-40
11.P Pecas, E Henriques, Influence of silicon powder-mixed dielectric on con-ventional electrical discharge machining, Intemational
Journal of Machine Tools& Manufacture, 43(2003), P 1465-1471
S U M M A R Y
E F F E C T O F M I X I N G T I T A N I U M P O W D E R C O N C E N T R A T I O N S
I N T O D I E L E C T R I C F L U I D O N T H E M A C H I N I N G E F F I C I E N C Y A N D
P E R F O R M A N C E I N D I E - S I N K I N G E L E C T R I C A L D I S C H A R G E M A C H I N I N G
O F S K D 6 1 S T E E L
Banh Tien Long', Ngo C u o n g ^ Nguyen Huu Phan^', T r a n Quang Cong"*
'Hanoi University of Science and Tecltnology, Hanoi Vietnam 'College of Economics and Technology - TNU,
^The college ofmachanics and melallury - Thai Nguyen
Electrical discharge machining (EDM) has found widespread applications in tool and mold industries, and aerospace industries Therefore, enhancement o f t h e quality o f t h e EDM process has become a major research concern In this paper, the effect of various titanium powder concenUations on the Material Removal Rate (MRR), tool wear rate (TWR), surface roughness (SR) in following powder - mixed electrical discharge machining (PMEDM) have been caried out The hot work steel SKD6I and electrode made from copper with reverse polarity were used in • experimental study The results showed that titanium powder mixed into the dielectric fluid of EDM can enhance MRR without increasing TWR, and improve the SR
Keys word; EDM PMEDM, MRR TWR powder mixed
Ngdy nhdn bdi:26/lO/20I4 Ngdy phdn bien: 12/11/2014; Ngdy duyet ddng: 31/5/2015
Phdn bien khoa hoc: PGS TS Nguyin Qude Tudn - Dgi hpc Thdi Nguyen
Tel 0983 783844: Email: Phanklcn@gmaiLci