Cng ngh ct kim loi bng laser. Phn ln cc my ct laser trn th trng
hin nay u s dng laser CO2 hoc laser Nd:YAG vi nguyn l tng t
nhau.
Nguyn l ct Phn ln cc my ct laser trn th trng hin nay u s dng
laser CO2 hoc laser Nd:YAG vi nguyn l tng t nhau. Nguyn l c bn ca
qu trnh ct bng tia laser c th c tm tt nh sau:
Hnh 1. S nguyn l ct bng tia laser. Mt chm tia nng lng cao c sinh
ra bi my pht laser s c tp trung ln b mt chi tit gia cng nh h thng
thu knh. Chm tia ny t nng vt liu v to nn mt vng vt liu nng chy cc
b, thng c ng knh nh hn 0,5mm). Phn vt liu nng chy b y ra khi vng
gia cng bi mt dng kh c p lc cao, ng trc vi chm tia laser. i vi mt s
loi vt liu th dng kh ny lm tng tc qu trnh ct bi tc ng ha hc v l hc.
Vng vt liu b nng chy cc b c di chuyn dc theo b mt chi tit theo mt
qu o v v th sinh ra vt ct. Chuyn ng ny c thc hin bng cch di chuyn
chm tia laser hi t nh h thng gng CNC hoc chuyn ng c kh
tm vt liu theo hai phng X-Ytrn bn my CNC. Cng c my thit k c hai
loi chuyn ng ny, khi chm tia laser c di chuyn theo mt phng v chi
tit gia cng c di chuyn theo phng cn li. Cc h thng t ng ha hon ton
cho php ct c cc hnh dng 3D. Ct kim loi Laser c th ct mt di rng cc
loi vt liu nhng phn ln cc h thng ct laser thng mi hin nay c thc hin
vi kim loi. Ct kim loi bng laser i hi chm laser mt nng lng cao
truyn nng lng vo vng ct nhanh hn lng nhit truyn ra ngoi. Km theo l
dng kh h tr s y kim loi nng chy ra khi vng ct. Thp cc bon l loi vt
liu kim loi d ct nht bng laser. Cc loi thp hp kim thp nh AISI 4140,
8620, c iu kin ct tng t nh thp cc bon. Hm lng hp kim trong thp tng
th qu trnh ct tr nn kh khn hn. Vi thp dng c c hm lng vonfram cao th
tc ct rt chm v c x. Bng 1. Cc tc ct kim loi khng cha st ca laser
CO2 v Nd:YAG
Nhm rt kh ct bng laser v nhm lm phn x mt lng ln tia laser v lng
nhit truyn vo chi tit ln v nhanh. Nu iu chnh tiu c tia laser khng
ng th c th chm tia b phn x tr li h thng phun gy h hng cc b phn
quang hc. Trong khi ng nguyn cht cn kh gia cng hn so vi nhm.
Hnh 2. L mt s chi tit dng trong y khoa c ct bng laser CO2 (bn
tri) v laser Nd: YAG (bn phi). Hnh 4, 5: L ba cc tng c ct v rch bng
tia laser.
Cc hp kim ng cng c nhng ng x tng t nh nhm. Cc hp kim nn co-ban c
cng rt cao, c tnh chu nhit cao v tnh chng mi mn tt. Tuy vy chng li
rt d c ct bi laser. Tuy nhin cn phi xem xt cc vt nt t vi sinh ra
trn b mt chi tit khi ct bng laser. Titan v hp kim ca n c phn ng vi
xy v nit to thnh cc thnh phn gin trn cnh ct. iu kin ny ni chung l
khng th chp nhn c i vi cc chi tit trong hng khng v y hc lm bng ti
tan. Nu cn thit th c th dng cc loi kh tr nh argon c vt ct cht lng
tt hn. Dng kh nn thi vo thng l xy. Nh dng kh ny m h s phn x ca b mt
kim loi gim xung. Hn na, khi b mt t n trng thi nhit cao, xy sinh ra
phn ng ta nhit, thc y qu trnh ct. Kh nn thi phn kim loi bc hi v
ngay c plasma Bng 1 Cc tc ct kim loi khng cha st ca laser CO2 v Nd:
YAG. ra khi khu vc ct gt, to iu kin cho qu trnh ct xy ra d dng, b
mt vt ct sch. cho qu trnh ct gt t hiu qu cao th dng kh thi vo phi
to thnh dng ln khu vc gia cng vi kch thc ln hn vt chm tia laser mt
t. Dng oxy p sut thp to ra phn ng t chy gy nh hng xu n cht lng vt
ct. Trong mt s trng hp, ty thuc vo vt liu chi tit gia cng m ngi ta
s dng kh tr thay cho xy. Kh ny khng to phn ng chy gia nhit cho cho
qu trnh nhng vn c cc chc nng nh cp trn. Thng thng ngi ta s dng xy,
nit, argon ct tm mng. Dng kh heli ct titan, kh tr p sut cao ct thp
khng r v nhm. B rng ca vt ct, cht lng ca cnh ct, cc ph phm (nh x)
tp trung ph thuc vo s la chn tia, cht lng tia, nng lng phn b v kiu
di chuyn khi gia cng (tia di chuyn, phi di chuyn, hay kt hp s di
chuyn ca c hai). Mt iu d thy l su ct t l thun vi nng lng ct v t l
nghch vi tc ct. Nh vy nng lng ct gp i s to ra chiu su ct gp i. Do
vy b dy ct ln nht l hm ca nng lng ct, tc ct v yu cu ca cht lng ct.
Hin nay b dy 25 mm c xem l b dy ln nht ca cc loi thp hp kim m ngi
ta c th ct c. Khong b dy ct c hiu qu kinh t cao nht ln ti 12,5 mm
cc kim loi phn x nh sng laser vi phn trm gia tng tng ng khi bc sng
ca tia tng vi mt nng lng cao c to bi cc tia laser CO2 nng lng cao s
khc phc c nhng nh hng ca phn x ny. Cc tia laser bc sng ngn hn nh
Nd: YAG s khng phi chu nhng nh hng ny do bc sng ngn nn phn ln nng
lng ca chng b hp th. Khi ct bng laser, mt thng s quan trng l b rng
vt ct thng thng bng hoc ln hn tia laser mt cht, nn vic iu khin tia
laser rt quan trng. B rng ng ct l hm s ca cc yu t nh cht lng tia,
tiu im, v tr tiu im, p sut kh n khng gian v tc ct. B rng vt ct in
hnh l 0,2mm trong khi ct bng oxy-axtylen l 3mm.
ng vi cc chiu dy khc nhau th ct vi tc khc nhau. Ty theo chiu dy
m khong cch tp trung ca tia laser phi c iu chnh t hiu sut cao nht.
Ct phi kim Cc loi vt liu v c phi kim loi c p sut bay hi thp v tnh
dn nhit km. Bn cnh chng cn c tnh cht hp thu nh sng mnh. Nhng tnh
cht ny tng nh l nhng iu kin tt cho ct bng laser nhng thc ra mt s vt
liu v c nh gm, thy tinh li c im nng chy rt cao v tnh khng nhit km
nn ct chng bng laser li kh hn so vi ct kim loi. Bng 2 Tc ct vt liu
phi kim loi ca laser CO2.
Khi chu tc ng nhit ca tia laser, giy, g v cc vt liu xenlul phi
tri qua mt qu trnh bc hi c gy ra bi s chy. Tc ct ph thuc vo nng lng
aser, b dy vt liu, cc thnh phn kh, nc trong vt liu cc vt liu polime
nhit do c ct bi s nng chy v y cc vt liu nng chy ra khi vng ct. Tc
ct cng ph thuc vo nng lng laser, b dy vt liu, p sut kh c dng thi.
Cc polime c th c ct bng s t chy hay phn r ho hc bao gm cc cht nhit
do chu nhit, poxi, phenol tc ct c quyt nh bi nng lng laser. Tc ct
cho cc loi chu nhit cao hn so vi cc loi polime khc do s thay i pha
bc hi. Cc vt liu composit c th d dng ct, nhng vt ct to ra c cht lng
cao hay khng cn ph thuc vo tnh nhy v nhit ca loi vt liu kt hp. Ni
chung thc nghim cho thy vic ct vt liu composit bng qu trnh ct khc c
dng cht lng p sut cao c hiu qu hn l ct bng laser. Cc qu trnh ct phi
kim bng laser ch i hi mt nng lng va phi. V th gii hn duy nht n chiu
su ct l yu cu cht lng ca vt ct. Trong thc t, phn ln cc ng dng ct
bng laser dng cho vt liu c b dy b hn 12 mm.
Vt liu gm c ct bng phng php thng thng bng ca kim cng. Mc d cht
lng b mt vt ct cao nhng tc ct rt thp, in hnh khong 20mm/ ph. Ct bng
tia laser cho php t tc ct n 1.200mm/ph m cht lng vt ct vn m bo. Cng
ngh hn bng tia laser: Khi hn bng tia laser khng c vt liu tip xc vi
chi tit hn nn mi hn khng b bn. Phng php hn ny hn vt liu trong mi
trng khng kh, trong kh hn bng tia in t phi thc hin trong mi trng
chn khng. Vng nh hng nhit khi hn bng tia laser rt nh. y l c tnh rt
quan trng khi hn nhng ch gn cc yu t nhy v nhit.
Hn bng tia laser c p dng ph bin trong cng ngh ch to vi mch. Nh
phng php ny c th ni cc u ni vi tm mch in. Hn bng tia laser cn c p
dng trong cng ngh lm kn v trong cc mch tch hp. Phng php ny cng c th
ni cc kim loi c tnh cht l ha khc nhau, ni kim loi vi phi kim loi.
Mi loi vt liu c kh nng hn bng tia laser khc nhau. Bng 1 so snh kh
nng hn ca hai loi laser CO2 v Nd:YAG i vi nhiu loi vt liu khc nhau.
Thp, hp kim nickel v hp kim titan rt d hn bng laser CO2 hoc laser
Nd:YAG. Nhm v hp kim ziriconi (zirconium) th d hn vi laser Nd:YAG.
Nhng vt liu c phn chiu cao nh ng, vng v bc c v kh c hn bng laser
CO2. S d nh vy l v sng bc di hn ca laser CO2 phn chiu
mt cch hiu qu do b mt vt liu c hp th b v phn chiu cao. Sng laser
Nd:YAG c bc ngn hn th h b hp thu bi cc vt liu k trn. S chuyn nng
lng laser c chuyn thnh nhit khin cho kim loi phi tri qua mt s thay
i pha t rn sang lng v khi nng lng khng cn na, kim loi tr v trng thi
rn. Qu trnh hn chy kim loi ny c dng to ra mi hn im hay lp hn lin
tc. Chiu su ngu khi hn bng tia laser kh nh v n ph thuc vo tc truyn
nhit t nng lng trn b mt chi tit. Tuy nhin i vi hn laser nng lng cao
th chm tia to mt l trn vt liu v nng lng laser tp trung vo y l, cho
php t c chiu su ngu ln hn. Hnh 3 th hin mi quan h gia cng sut v
chiu su ngu khi hn thp 304 bng laser CO2vi cc tc hn khc nhau. Phng
php hn bng tia laze khi nim v ng dng nh ngha hn laze: Laser beam
welding (LBW) l dng c bit thuc nhm hn nng chy, trong kim loi ch ni
c nung chy bng tia laze tp trung cng sut ln do my pht lng t quang
hc to ra. LBW thng dng ni cc chi tit lp nhng ch kh chm ti, hn cc
chi tit rt nh, hn vt liu c chy cao (nh gm).
S cu to v nguyn l hot ng laze s dng hng ngc
1: B cung cp v iu khin in 2: Bung phn x nh sng. 3: n pht xung.
4: Thanh hng ngc. 5: Gng phn x ton phn. 6: Gng phn x bn phn. 7: Thu
knh hi t. 8: Chi tit. 9: Bn G. 10: T bo quang in. Nguyn tc cu to ca
my hn v my ct laze l gn nh nhau, tuy nhin my hn c th c b sung thm b
cp kh bo v, cng nh h thng cp kim loi ph ty thuc theo yu cu mi
hn.
+ My hn laze cu to bao gm mt tinh th hng ngc hnh tr. Hng ngc l
hp kim nhm oxit ( AlO2 ) c cha hp cht tch cc Crom. Hng ngc c s dng
thng l sn phm nhn to. + Hai u ca tinh th hng ngc l 2 gng phn x mt
gng phn x ton phn, mt gng phn x bn ton phn c mt l nh cho vic pht
tia laze. + Tinh th hng ngc c bao quang hoc nm trong li ca n xon
Xenon. n Xenon ng vai tr l ngun cp xung. C h thng n li hng ngc c
cha trong bung phn x nh sng nhm phn x ti a nh sng vo tinh th hng
ngc. n Xenon c tc dng chuyn ha nng lng in thnh nng lng nh sng. + Mt
h thng lm mt s dng kh hoc cht lng bo v thanh hng ngc khng b ph hng
bi nhit sinh ra. + Khi n xenon pht sng ton b nng lng s tp trung vo
thanh hng ngc nhng Ion Cr+3 cha trong thanh hng ngc b kch thch ln
mc nng lng cao, khi tt xung chng s pht ra nhng lng t. + Hai h thng
gng phn x lng t lm chng i li nhiu ln trong thanh hng ngc v kch thch
cc Ion Cr+3 khc ri phng ra cc chm tia in t khc. + Chm tia lng t sau
khi c tp trung s c pht ra qua gng phn x bn phn 6. Chm tia s c tp
trung li qua h thng thu knh v tp trung ln chi tit gia cng v chuyn
thnh nhit nng. + Nhit lng lm vt liu hn tan chy trn mt din tch nh kh
ngui cc lin kt hn tr ln ng nht. + Hn laze ty tng vt liu, tnh cht mi
hn yu cu m yu cu kh bo v cng nh kim loi b. u im ca hn laze + c th
hn laze cho cc mi hn cng hoc khc cht liu. + Tia laze c th kim sot c
chnh xc cao, im hn cng c th t c chnh xc. + Tc nung nng cng nh lm
ngui cao, vng nh hng nhit l nh do hn laze tt cho cc v tr hn c lin
kt vi cc b phn d nh hng bi nhit. + Quy trnh hn thu c mi hn sch v
thng t phi lm sch mi hn. Nhc im ca hn laze + Tc hn chm ( t
25->250mm/pht ). + Tc ngui nhanh c th gy ra cc vn vi mi hn thp
cacbon cao + Gi thnh trong thit b l cao so vi cc phng php hn
khc
ng dng ca hn laze Hn laze c s dng trong cng nghip in t, hn cc
thit b y t, trang sc, trong cc h thng t ng sn xut t. My Hn Laser
HT
Xut X: Trung Quc Bo hnh: 18 thng Thng s k thut: - in p vo: 380V,
3pha, 50/60 Hz. - Dng in vo nh mc: 40A. - Bc sng Laser: 1064 nm. -
Cng sut: 200 W. - Phm vi iu chnh nh sng im: 0.1 - 3.0 mm. - Kch thc
nh sng im: 0.2 - 3.0 mm. - rng xung: 20 ms. - Tn s xung: 50 Hz. -
Tinh th Laser: xung YAG. - H thng iu khin: PLC. - Hnh trnh bn thao
tc: 200 x 200 mm. - Kh nng nh v chnh xc: 0.02 mm. - Kh nng lp li
chnh xc v tr: 0.01 mm. - Kh nng chu ti ca bn lm vic: 200 kg. - My
lm mt nc.
Ph kin ng b gm: - Ngun hn Laser 200W. - Bng n: 01 ci. - Thu knh
IR: 01 ci. - Gng bo v: 01 ci. - Cng tc p chn: 01 ci
Phng Php Gia Cng Bng Plasma
1: khai niem co ban - V phng din Vt l, Plasma l cht khi phn hy v
ion ha mnh, tc l hn hp ca phn t, nguyn t, ion v in t theo mt t l
nht nh. - Plasma l mt trng thi vt cht trong cc cht b ion ha mnh. i
b phn phn t hay nguyn t ch cn li ht nhn; cc electron chuyn ng tng i
t do gia cc ht nhn. 2. c im v kh nng cng ngh a. Nguyn l hot ng - L
PP gc dng dng Plasma c nhit t 11000 28000oC ct kiem loi bng cch lm
cho n nng chy cc b ti v tr gc v dng p lc ca dng kh y phn kim loi
nng chy ra khi v tr . Qu trnh ct ny c chia lm 2 giai on: - u tin
dng kh nng lm chy v xuyn thng vt liu. - Sau dng Plasma c dch chuyn
theo ng dn c vch sn ct vt liu. - Dng Plasma l 1 hn hp kh ca cc
electrong t do, cc ion dng, nguyn t v phn t. Cc loi kh thng dng to
Plasma l Nito, Argon, hidro hay hn hp cc kh ny. Dng Plasma c pht
sinh gia cc in cc Catod bn trong vi phun (thng l Tungsten) v chi
tit gia cng (anod). - Dng Plasma i qua dng nc lm ngui u vi phun v n
c thu hp li thnh tia tc ng trc tip vo v tr yu cu. Tia Plasma n chi
tit gia cng
c vn tc cao v nhit cc nng ti tm ca n, nhit ny ct t ming kim loi
dy 155,4 mm. b. c im, kh nng cng ngh - C th gia cng bt c kim loi
no, v k cc cc vt liu rt kh gia cng giothangmuoi.info vi cc PP khc
nh : thp khng g v hp kim nhm. - Vi ngun nng lng ln, PP ny c th gia
cng hp kim nhm vi chiu dy khong 15cm, v 10 cm vi thp khng g. 3. Phm
vi ng dng - Gia cng bng h quang Plasma ch yu dng ct tm kim loi. - t
l hay gia cng ct dc theo nhng ng dn xc nh. - C th gia cng bng tay
hoc bng iu khin CNC (kh nng TH cao). 4. u phun plasma: u vi phun
dng Plasma (Nozzel) c lm t Vonfram (tungsten) (bn trong vi) c th kt
hp vi cc nguyn t khc nh Cacbon tng tnh chu nhit ca n, BKMetalx cng
mt s bin php x l tng kh nng chu nhit, kt hp vi ch lm ngui bng nc u
vi phun khi Plasma c sinh ra. u vi phun y ng vai tr l Catot cn chi
tit gia cng l Anot. Nh vy Plasma c sinh ra trong khong cch gia u
voi phun v chi tit gia cng. N khng hon ton nm trong vi phun. Vi hnh
nh v u phun cho cng ngh ny:
