i>i^mt:ii u u u PC irien Knai
Gia cong cao toe va anh hudng cua no den do nham be mat khi gia cong
tren niay CNC 4 true VCP600
TS. NGUYEN HUY NINH - TrUdng DH Bach khoa Ha Noi
THS. N G U Y I N TIEN DUNG - TrUdng DH Kinh te- Ky thuat Cong nghiep
Gia cdng cao tde (High Speed Machining - HSM) la mdt trong nhOtig cdng nghe gia cdng hien dai. So vdi phUPng phip cat gpt truyen thdng, thi gia cdng cao tde cd kha nang nang cao nang suat, dp ehinh xic, chat IUdng chi tiet gia cdng, giam chi phi san xuat v i thdi gian gia cdng.
1 . G I 6 I T H I E U V E G I A C O N G CAO T O C ( H S M ) .
1 . 1 . Ljch suT cua gia cong cao toe
Ojnh nghTa dau tiin ve HSM dugc dUa ra bdi Carl Salomon, vio nim 1931.
0 «00 1200 liOO 241 cutting speed Vc >
Hinh 1.1: Nhiet dd gia cdng khi phay cao tde (theo dudoin cua Salomon)
Nghiin ciru cd bin ciia Salomon cho thay ring cd mdt pham vi nhat djnh eit tde dp, ndi khdng the gia cdng thUe hiin do qua mu'c nhlit dd cao. Vdi kiin thu'c hiin dai, Viin PTW (The Institute of Production Engineering and Machine Tools - OLTC) xic djnh tde dp cao gia cdng nhU I i eit vdi tde dd vUdt q u i tde dp thdng thUdng tir 5 d i n 10 lan.
Gia cdng cao tde thUe chat I i biin phip gia cdng thay the mpt quy trinh bao gdm chieu sau eit t Idn v i lUqJng ch?y dao t h i p bing mdt quy trinh gdm nhieu dUdng eit hdn (chiiu siu eit t nhd) v i IUdng ch?y dao cao. Phdi dUdc tgo ra nhd hdn nhutig dUde bdc tich nhanh hdn. Nguyin nhan chinh glOp cho sy gia cdng cao tde dat hiiu q u i chinh \a chiiu siu cSt t nhd. Chiiu siu eit t nhd ddng nghTa vdi vlfc cing ft nhl$t tda ra trong q u i trinh eit. Khi do vdng quay ti-ong 1 phiit c6 t h l ting lin ding kg.
Trong thyc t i , co nhieu cich khic nhau d l djnh nghTa gia cdng cao tde dya v i o eic y i u td sau:
• Gia cdng vdi tde d$ cSt cao (High speed cutting - HSC).
• Gia cdng vdi tde d$ quay ciia tn^c chfnh cao (High spin- dle speed machining).
• Gia cdng vdi IUpng an dao cao (High feed machining).
• Gia cdng vdi tde dp cat cao va IUdng an dao cao (High feed and speed machining).
• Gia cdng vdi nang suat cao (High productivity machining).
Tdm lai, viic djnh nghTa ve HSM khdng ddn giin, nd phu thudc vio vat lieu gia cdng, phUdng phap gia cdng, dao cat... Vi vay, viic djnh nghTa ve HSM phu thudc vio ky thuat hiin hinh.
Tiiy theo loai vat lieu ma dii (viing) tde dp gia cdng cao tde khie nhau (Hinh 1.2).
H Vung chuyen tiep Chat deo co soi t i n g cudng
Nhom DSng Gang Thep Titaniuin HopldmNkkd
ep • Vtmg gia cong cao toe
ig 100 1.000 10,00
Vjn toe cat (n/phut)
Hinh 1.2: Viing toe do gia cdng cao toe mdtsSio^i v$t ii^u
NtafmilcitpM Chii kmif tii • «
vtnlieeil(MpMQ
Hinh 1.3: Tdng quan cua gia cdng cao tde
Xem xet m$t cich toin diin thi HSM hiTa hen mpt thj trUdng mdi vi gia cdng cao tde khdng chl lim glim lyc eit, m i cdn ting chit
\ugng b i m|t. Tuy nhiin, tuoi bin ciia dao lai glim dl khi ting tde dp eit (Hinh 1.3), vi viy can phii nghiin culi de phit triln ve dgng cu diing trong eit cao tde.
1.2. Dyng c ^ c&t
Trong gia cdng cao tde tiii sy mdn ciia dgng eg eit Ii vin d i r i t can 6U<fc lUU t i m , nd quyit djnh d i n tuSl bin ciia dao (Hlnh 1.4). Dya vio iitig dgng, v i t ll|u v i I6p phii, ngUdl ta phin lo^l v$t ll|u dgng eg eit diing cho gia cdng cao tde nhU sau:
(Sd 7 -9/2011) < KHOA HOC & CONG NGH$ |37
rsghien cuii ^^MBKaa^mi
vdi dung eg gia cdng cd dp cutig nhd hdn 42 HRC thi diing vat lieu cac bit phii TIN (Titanium nitride) v i TICN (Titanium earbonitride).
- Vdi dgng eg gia cdng cd dp eutig Idn hdn 42 HRC thi diing vat lieu cie bit phii TIAIN (Titanium aluminum nitride).
- Nhijtig utig dgng die blit khi gia cdng khd khin t r i n tiin (60-^65) HRC thi diing PCBN (Polyerystalline cubic Ni trite borom).
- CBN (Cubic boron nitrite) va su' diing de gia cdng gang.
- PCD (Poly crystalline diamond) v i gdm kim loai diing de gia cdng nhdm.
a MA
'8
,«S w- A
TICN
TM
no coating T1AM
-s.
Vfn t6c eit (m/phnt)
Hinh 1.4: Anh hUdng cua de Idp phu vat lieu dung cu khie nhau ddi vdi tudi bin dao.
1 . 3 . LiTc cat.
Oau tiin IUc eit se ting khi ting van tde eit, nhutig d i n mdt gii trj Idn nhat, nd se bit dau giam khi tiip tgc ting van tde eit (Hinh 1.5). Nhd viy, trong gia cdng cao tde, ngUdI ta ed the gia cdng dUdc cie ehi tiit ed thinh nhd, gin mdng.
0 soc 1000 1S0O 2000 2500
Hlnh 1.5: Anh hUdng cua vin toe cSt den life dt
3000 Vclm/miil
1.4. Mot so kinh nghiem cho gia cong cao toe
Oe tdi Uu hoa van tde eat eung nhU IUdng ehay dao thi CO the ndi rang khdng eo loai miy gia cdng cao tde nao co the dUdc sir dgng mdt cich tdng quit. Cd the dgla tren Hinh1.6 va Bing 1.1 sau de lim du' lieu tham khio khi gia cong cao tde.
: Nhdm, tfong U: Caig, tMp in:CUtiUoc6ifltiag
CDdBg
XOO UOO ^000 m^im mO V^n tic eit (m/pkit) a ^ *
Hinh 1.6: Vung ky thuat toi UU cho gia cong cao toe.
2. T H I NGHIEM DANH GIA ANH HUOfNG
CUA CHE OO C A T K H I PHAY CAO TOC DEN DO NHAI^ BE MAT C H I T I E T GIA CONG 2.1. May gia cong:
Miy CNC 4 trge MIkron VCP 600 eiia hang Agle Charmilles (Thgy Sy).
2.2. Dung cu cat:
Dao phay mit dau 080 ASX440 gan chip SEMT13T3AGSN- JM F5020 eiia hang Mitsubishi, sd rang 1 = 6.
2.3. Mau thl nghiem:
Vat lieu: thep lim khudn S55C theo tieu chuan Nhat Ban (JIS) cd tdi cii thiin dat 30 HRC trUdc khi gia cdng.
2.4. Ket qua:
Sau khi gia cdng mau do lay k i t q u i va tien hanh quy hoach thUc nghiim, chiing tdi dUde k i t q u i nhU sau:
Bang 1.1: V$n tSc e i t du'^c su* dyng trong HSM theo kinh nghifm vc (m/phut)
V$t lieu
Steel 01.2 ll 02.1/2 Steel 03.11
pr03.11 Steel 04
1 AI/Kirkslte
ik'wii 120
Do cu'ng
150 HB 330 HB 300 HB 9-r48 HR 84-58 HR 180 HB 60^75 HB
100 HB
Gia cdng truyen HSM HSM thong Vc ( m / p h u t ) Vc (tho) ( m / p h u t ) Vc (tinh) (m/phut)
<300
<200
< 100
<80
<40
<300
< 1000
<300
330 HB300 HB 39-r48 HRc 484-58 HRc 180 HB
<200
< 100
< 8 0
< 4 0
<300
>250
>200
>150
> 100
>500
! •
: H I ^ W .
< 600 U p
<400
<350 H
<250
< 3000 H
>400
>250
>200
>150
> 100
>500
> 2000
> 1000
<900
<600
<400
<350
<250
<3000
<5000
<2000 1
38| KHOA HQC & C 6 N G N G H | • (S6 7 9/2011)
Nghien ci^i &^HBKniai^
Bang.
STT
1 2 3 4 5 6 7 8
2.1. Ket qua thu'c nghiem Ra Bi^n thifc
V(m/ph) 401,9 502,4 401,9 502,4 401,9 502,4 401,9 502,4
F(in/ph) 0,5 0,5 0,6 0,6 0,5 0,5 0,6 0,6
((mm) 0,2 0,2 0,2 0,2 0,3 0,3 0,3 0,3
Bi^n ma
X |
-1 +1 -1 +1 -1 +1 -1 +1
« 2
-1 -1 +1 +1 -1 -1 +1 + 1
5t3
-1 -1 -1 -1 +1 + 1 +1 +1
K^t qui d$ nhim bl mit R.(|in») R.1
0,29 0,27 0,5 0,39 0,31 0,28 0,5 0,45
R.2 0,29
0,3 0,4 0,38 0,33 0,28 0,6 0,45
R.3 0,28 0,265
0,48 0,37 0,35 0,27 0,54 0,43
R«b 0,2867 0,2783 0,46 0,38 0,33 0,2767 0,5467 0,4433
> Md hinh hoi quy ham bac nhat thUe nghiem ddi vdi Rg
S^Qxunj'rang)
Hinh 2.1: Anh hUdng cua V, Sz len Ra khi t = 0,2 mm.
V ( n i / p h u t )
Hinh 2.2: Hinh anh thf nghlim tren miy VCP600.
> Minh hpa bang do thj anh hUdng ciia V, Sz len Rg
3. KET LUAN
HSM khdng chi ddn thuan la gia cdng vdi tde dp cat cao, nd la mdt qua trinh ddi hdi phUdng phap gia cdng va thiet bj cu the. Tuy nhiin, nhieu utig dung HSM (ke ca thi nghiem neu tren) chi can diing vdi tde dp cat vira phai vdi dUdng kinh dao Idn.
Trong thi nghiem ve anh hUdng cua HSM den dp nham be mat neu trin, khi tang IUpng ehay dao Sz va chieu sau cat t thi chieu cao nhap nhd te vi be mat Ra, Rz tang. Tuy nhien, anh hUdng ciia chieu sau cat t den dp nham be mat khdng dang ke. Cdn khi tang van tde cat thi dp nham be mat giam di. Dieu nay cung phii hpp vdi ly thuyet khi ta tang van tde cat len thi thdi gian tie ddng ngan, IUc cat nhd (giam di khi tang v), viing bien dang it. Day chinh la Uu diem ciia gia cdng cao tde, khi tang v vira tang dUde nang suift cat va lai tang dUpe dp bong be mat. Dieu nay cd y nghTa rat Idn vi gia cdng cao tde dat dUde dp bdng be mat rat cao.
a dai HSM, ma nhdm tac gia khao sat thi dp nhim be mat xap xi bang dp nham be mat khi gia cdng bang phUdng phap mil. Tien tdi nhCTng dai HSM cao hdn nQa thi hoan toan ed the la phUdng phip gia cdng tinh hull hieu.
Tdm lai, mac dii HSM da dUde biet den trong thdi gian dai thi viec nghiin cull van dang phat trien hdn nCi'a ve chat IUpng va tdi Uu hda viic chi phi khi gia cdng HSM.
TAI LIEU THAM KHAO:
1. P.Failbohmer, CA.Rodriguez, T.Ozei, TAItan (2000) High-speed machining of cast iron and alloy steels for die and moid manu- facturing. Journal of Materials processing technology.
2. Dr. Mosche Goldberg (March, 2010), The key to higher productivity, Asia pacific metal- working equipment news.
3. J.Kopac (2007), High precision machin- ing on high speed machines. Journal of Achievements in Materials and Manufacturing Engineering.
4. Herbert Schuiz (1999). The history of High speed machining, Darmstadt University of Technology, Germany.
5. HerbertSchuIz, ToshimichiMor'iwaki(1992) High-speed machining. Annals of the CIRP.
6. Metalworking world, HSM-High speed machining.
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