NGHIEN COfU - TRAO eOl
PHlfaNG TRiNH H 6 | QUY XAC 0!NH KJCH THU'aC VUNG A N H H U ' ^ N G NHIET COA TAM THEP TRONG GIA NHIET CAM UNG
REGRESSION EQUATIONS OF HEAT AFFECTED ZONE IN STEEL INDUCTION HEATING
NCS. Tran Thi Thuy Nga", TS. Nguyen Trfldng ThinhS PGS.TS. Train Thu Ha^
'Trfldng Cao dang Ky thuat Cao Thing
^TrUdng Dai hpc SU pham Ky thuat Thinh phd Hd Chi Minh
De tao hinh bien dang cua tdm thep bang nguon nhiet, phUdng phdp gia nhiit cdm Ung dUde sU dung dethay thi cho ngudn nhiet khi Oxy-axetylen, vdn khdng ed nhieu Uu diem trong Ung dung tao hinh thep tdm. Tuy nhien, trong edc nghien cUu dd dUdc cdng bo, chUa the hien rd moi quan hegiUa kich thUdc viing dnh hUdng nhiet cua tdm thep vdi cdc thdng sd nhiet lien quan trong suot qud trinh gia nhiet cdm Ung, md dieu ndy Iqi tao nen bien dang khdc nhau cua tam thep. Trong nghien cdu ndy, thdng lUdng nhiet phdn bd tren tdm thep trong suot qud trinh gia nhiet cdm Ung dUdc phdn tich ddu tien bdi phUdng phdp so, dudi gid dinh rdng qud trinh Id mdt trang thdi dUng vd cdng dUdc xem xet rang, thdng lUdng nhiet phu thudc vdo nhiet do vd cdc tinh chdt cua phdi. Vdi thdng lUdng nhiet dUdc phdn tich, viec phdn tich ddng nhiet vd bien dang nhiet cua tdm thep dUdc thUc hiin vdi mdt chUdng trinh FEM, vdi cdc thdng sd gia nhiet tUdng Ung. Kich thUdc vung dnh hUdng nhiet vd cdc thdng sd nhiet ddu vdo dUde tong hdp vdi phUdngphdp thdng ke de xdc dinh mdt edng thUc the hien moi quan he giUa kich thude vung dnh hUdng nhiet vdi cdc thdng so nhiet ddu vdo. Kit qud dUdc suy ra tiiphUdng trinh hdi quy tot so vdi ket qud md phdng.
ABSTRACT
To control the deformation of plate in the steel forming process with heating, the electro-magnetic induction process has been used as the substitute of the flame heating process. However, in these studies have been published, haven't clear the relationship between the size of heat affected zone of steel plate with heating parameters related during the heating process in induction heatingyet, which this makes a different deformation of the steel plate. In this study, the heat flux distribution over a steel plate during the induction process is firstly analyzed by a numerical method under the assumption that the process is in a quasi-stationary state around the inductor and also with the consideration that the heat flux itself greatly depends on the temperature of the workpiece. With the heat flux analyzed, heat flow and thermo-meehanical analyses on the plate are then performed with a commercial FEM program with heating parameters, respectively. The size of the heat affected zone and the input heating parameters are then synthesized with a statistical method to produce simplified formulas, which can easily provide the relation between the heating parameters and the size of the heat affected zone. The results obtained from the formulas are in good agreement with results of simulation.
Tfl khda: Steel forming. Electro-magnetic induction. Heat flux analysis, Thermo-meehanical
analysis. Finite element method, Simplifiled formula. Heat flow. Heat area zone (HAZ). ^
CO KHi VlfiT NAM • Sd 7 (Thing 7 nam 2012) ^ 9
NGHIEN CtfU-TRAODCl
I.GICJI THIEU
Viec tao hinh bien dang lam ih^p vd liu trflde khi lap ghep vao eae phan cua than tiu la mpt khiu quan trpng trong nginh ddng liu, tao nen chat Iflpng eua mpt chiec liu vi ning cao khi nang canh tranh tren thi iruniig Qui trinh tao hinh bien dang thep lam vd liu liicn nay chu yeu sfl dyng cae phfldng phip truyen thdng, vdn khdng linh boat vi kem hi^u qui kinh te. Dac bi^t la phfldng phip tao hinh bien dang vd tiu bing ngudn nhiet, sfl dyng dau dot khi Oxy-axetylen ll]. Chat lupng tao hinh be mat cung nhU bien dang ciia tam thep phy thupc i-il nhieu vio tay nghe ngfldi thp, khd kiem soat ngudn nhi?t diu vao trong sudt qua trinh gia nhi^t mi dieu niy lim giim hi^u qua eua phfldng phap.
Gia nhiet cam flng li phfldng phip dupe sfl dung de thay the cho ngudn nhi?t khi Oxy-axetylen, vdn khdng cd nhieu flu diem trong viec tao hinh bien dang tam thep. Khi gia nhiet cam Ung dUde ip dung cung vdi viec tich hdp robot cho viec tU ddng, qui trinh udn bien dang tam thep se trd nen de dang dieu khien vi kinh te hdn cac phUdng phip eu Die biet, ddi vdi cic tam thep bien dang vd tau ed bien dang phfle tap, phfldng phip gia nhiet cim flng the hi^n rd khi nang toi flu. Cic de tii nghien cflu ve phfldng phip gia nhiet cam flng trong bien dang thep tam da dflpc cdng bo, phan bd nhiet hai chieu trong sudt qui trinh gia nhiet cam Ung vdi tan sd gia nhiet cao li nhflng chu de chinh trong hau het eae nghien cflu [2-^7] vi trang thii bien dang ba chieu cua tam thep dfldc md hinh hda bdi phin tich [8]. Tuy nhien, trong cic nghien cflu di dflpc edng bd, chfla the hien rd mdi quan he gifla kich thfldc vung inh hfldng nhiet cua tam thep vdi eae thdng sd gia nhiet lien quan trong sudt qua trinh qua trinh gia nhiet cim flng ma dieu niy, nd tao nen bien dang khae nhau cua tam thep.
Trong nghien cflu nay, hai cdng thflc ddn gian dfldc de xuat de xic dinh kich thUdc cua vung anh hfldng nhiet cua tam thep vdi cic thdng sd gia nhiet lien quan trong sudt qui trinh gia nhiet cam flng vdi tan so cao. Cdng thflc cd
th^' rit hflu ich trong vi?c phat trien dfl doan quy d?io di chuyen cua dau tU, dfla vio edng thflc xac djnh biefn dang theo phUdng vudng gdc cCia tam da dupe cdng bd [9], cho van de tUdng lai.
I )e xic dinh edng thflc Ai xuat, vi^c phin tich thdng Iflpng nhi^t. ddng nhiet va phin tich bi^n dang nhi?t dflpc thflc hi$n vdi cic thdng s6 nhiii diu vio. Phfldng phap phan tfl hflu han (FEM) dflpc sfl dyng trong phin tich bdi vi cac die tinh phi luyen trong gia nhi^t cam flng. Tuy nhien, khi ngudn nhiet gay nen bdi dau cim flng tU di ehuyen tren be mat tim thep vdi van toe khdng ddi, mdt mien giii phip bao gdm tim thep, cupn diy vi khdng khi trong dd vi tri cupn day va phan khdng khi thay ddi lien tuc vi nhflng thay ddi nay giy nen khd khin cho phan tich ddng thdng Iflpng tfl, ddng dien xoay va thdng lUpng nhi?t sinh ra tren tam thep trong sudt qui trinh gia nhipt cim flng khi chi sfl dung mpt chfldng trinh FEM. Bdi vay, mpt chfldng trinh FEM cho phin tich trfldng dien tfl cua qui trinh gia nhiet cam Ung dfldc phat trien dfldi gia dinh ring qua trinh nay la mpt qui trinh trang thai dflng vdi mdt he tpa dp di chuyen, COMSOL 3.4. Chfldng trinh FEM tinh toin thdng Ifldng nhiet tfl dau gia nhiet den chi tiet trong sudt qui trinh niy. Phan tieh ddng nhiet vi bien dang nhiet cho tam thep sau dd, dfldc thflc hien vdi chfldng trinh FEM Abaqus 6.5, sfl dpng thdng Iflpng nhiet dUpc suy ra tfl phin tich trUdng dien tfl nhU la mpt nguon nhi^t dau vio. De xiy dUng mpt cdng thflc ddn giin xic dinh kich thfldc vung inh hfldng nhiet cua tam thep vdi thdng so gia nhi^t bat ky, phan tich thdng Ifldng nhiet vi bien dang nhiet dflpc thpc hi^n vdi nhflng thdng so gia nhiet nhfl be diy tam thep, tdc dp di chuyen dau tfl vi cU6ng dp ddng dien trpng cupn day. Mdi quan he gifla kich thfldc vung anh hfldng nhiet va cic thong sd gia nhi?t bdi thUe nghiem sau dd dfldc tong hdp vi phin tich bdi phfldng phip thdng ke de xac dinh mpt cdng thflc tfldng flng. Mdt loat cac phin tich md phdng gia nhiet cim flng dflOC thflc hipn sau dd, de chflng minh tinh kha thi cua cdng thflc.
TAP CHi CO KHi V I £ T NAM • Sd 7 (Thang 7 nam 2012)
NGHIEN COfU-TRAODOl
2. PHAN TICH THONG LUONG NHlfiT SINH hpp veetd. Khi phfldng trinh (1), dfldc giii bang RA TRONG GIA N H I £ T CAM TTNG phfldng phip phan tfl hflu han, nd dUpe viet nhU 2.1. Phan tich trUdng dien tfl cho thdng Ifldng
nhiet
Khi cho ddng dien xoay chieu, cd tan sd cao chay qua mdt cudn diy, dUdc dat tren mpt tam thep, nhfl hinh 1, mdt chum tfl thdng xuyen qua be mat cua tam thep m i nd ddng tryc vdi cudn day. Vi vay, ddng dien xoay dflpc sinh ra tai be mat cua tam thep. Ddng dien cam flng sinh ra nhi^t dien trd tren tam th^p theo hieu Ung Joule v i dieu niy cd the dung de udn tam thep.
[KM'IJ]
\B!J w \eN\\m\
[j]=jj.[N]'da
(2) iat,«,llnil«\Jn(3)
(4) Vdi vecto dien tich dUpc rut ra tfl phfldng trinh (2), nhiet dien trd ed the dflpc tinh.
(5) PhUdng trinh can bing cho ddng dien (^ d.ky J, = a{-dA! dl) la mat dp cua ddng xoiy phan bo trong q u i trinh gia nhiet cam Ung ^j^j^ j^^^y
ed the dflpc suy ra tfl he phfldng trinh Maxwell
trong vung tan sd cho phep 110]. -jl^^ng Ifldng nhiet trung binh trong mien I „ ' , . , tan sd cd the dfldc tinh.
— V A^}Q}uA-J, / i \
^ - 1 C^ l i t \
CSday:V- gpi l i toin tfl Laplace, A l i veetd
dien the tfl, J^ mat dp ddng dien eua nguon trong O day /C la lien hpp phfle eua A eudn day, n l i dp tfl tham, w la van toe gdc v i a
l i dp d i n dien. 2.2. Phan tich ddng nhiet cho trfldng dien tfl Truong difn lit
lh<i\ doi Dongdi^n \o.n chieu
Nhiv't Joule
Hmh I. Mo hinh tong qudt trong gia nhit cdm dng
Khi veetd dien tich cua phUdng trinh (1) dUdc phan tich, ddng dien xoay va thdng Ifldng nhiet phan bd tren tam thep cd the dfldc tinh toan. Phfldng trinh (1) ed the dfldc tach ra v i ap dung cho mdi true. Dau tien, tinh dien the tren mdi true x v i y, sau dd edng chung lai bang td
Phan tieh trfldng dien tfl de md ta thdng Iflpng nhiet phan phdi tren tam thep, yeu cau cac tinh chat vat lieu chinh xac nhU dp tfl t h i m , dp dan dien, ... cua mien giii p h i p . Bdi vi, nhflng thudc tinh n i y nd phu thupc d i n g ke vao nhiet dp cua vat lieu. Bdi vay, viec p h i n tich ed the giai quyet vdi hai van de gifla dien tfl v i ddng nhiet trong giai p h i p tai cung mdt thdi di^m. Trong nghien cflu niy, de giii quyet van de nay, xin dfla ra giai p h i p : dau tien, phan tich trfldng dien tfl vdi tinh chat cua vit lieu tai nhiet dp ban dau de xem xet phan bd thdng Iflpng nhiet. Sau dd, phan tich ddng nhiet qua tam thep de tim ra phan bd nhiet dp cua tam m i nd dfldc dung de xac dinh tinh chat eua vat lieu cho phan tieh cua trUdng dien tfl de tim ra p h i n bd thdng lUdng nhiet cho bUdc tiep thed.
Q u i trinh lap lai den khi hdi tu den ldi giai
trong gidi han chap n h i n dUdc. '^
T ' " ^ " ' ^ ^ ^ i^w^ ^ a £ T NAM Sd 7 (Thing 7 nam 2012)
NGHIEN Cflu - TRAO D O I
Klioang / Vuny kliony V
' IhrJngdi cliiiycn cilii I lim llitip
Hinh 2. NUa mo hinh ba chieu cho phdn tich phdn tU hdu han tronggia nliiet cdm Ung.
phdng ludn cd sU h o i n ddi vi tri. D^ di^u khien q u i trinh thay ddi khdng ddi nay, mpt trang thai dflng tren hfldng di chuyen cua cupn day dflpc gii djnh cho phan tich thdng lUpng nhiet vi d6ng nliiC'l. Trong trfldng hpp trang thii dflng, hi?n tflpng phit sinh thdng Ifldng nhi?t trong sudt qua trinh gia nhipt cam flng ed the dflpc md hinh hoa m i khdng can xem xet thdi gian chay m i y Sau d6, thdng Iflpng nhi?t phat sinh va ddng nhi?t cd the dupe md hinh hda vdi mpt h? tpa dp di chuyen, m i gde Ipa dp tai vi tri cua cupn diy, nhfl hinh 3!
Ddng nhi^t trong tam thep cd the dflpc bieu tin nhfl sau.
He tpa do
H? Ipa dp di chuyen
Z
Hinh 3. He tga do di chuyen.
d-T r + — r dy' cz'
m = pA'
•i)
(7)ft Id.
dTli-
Vdi moi quan he cua c =x-vt,
= l,rc/<"/ = - i ' , ( T ,'x = uT Ci-nCz'cx),
= ieT'cl)„ +icJ r^nC4ldl) = -v(ST r'JI
PhUdng trinh (7) dUiJc bien doi tai he tpa De thuc hien phan tich trUdng dien til do di chuyen n h a sau | 1 1 | .
va dong nhiet, xac dinh thong lUdng nhiet tren tam thep vdi phUdng phap phan tii hiiu han. mot mien giai phap bao gom tam thep, moi trudng khdng khi va cuon day duoc md hinh hda nhu hinh 2. Khi cupn day di chuyen tren tam thep, vi tri cua cupn day trong mien ludn ludn thay doi.
Gifla cupn day va phan khong khi trong mien md
C-T] -
1-9 = cT]
(8)
Khi phuong trinh (8), dupc de ra cho phUdng phap phan til hflu han khi xet den sil d6i luu nhiet, nd dupc viet nhfl sau.
I-
r[N]'df *jh.T,dr
^^^([tI[fHf]'[f-B^I[f])"-^Ii"n^K]ri
Phuong trinh (9), sau do dflpc thitc hien 3.1. Phan tich dong nhiet va bien dang nhi^t vdi chflong trinh FORTRAN 77, de cd duoc nhiet
dp phan bo tren tam thep trong supt qua trinh gia nhiet cam ling.
3. DONG NHIET VA BIEN DANG CUA TAM THEP TRONG GIA NHIET CAM C N G
De phan tich bien dang nhiet ciia tam thep trong gia nhiet cam ling, mpt thdng Ifldng nhiet tflc thdi dflpc phan tich dau tien. Bang vi|c sfl dung mpt thong Iflpng nhiet dflpc suy ra trong phan tich trUdng di?n tfl nhfl la mpt ngupn nhi^
TAP CHi C O KHf VIET NAM S6 7 (Thang 7 nam 2012) t
NGHIEN cdu - TRAO B6\
dau vao trong p h i n tich bien dang tam thep.
h" • 5 0 0 m m
Nhi^t dp tflc thdi phan bd tren tam thep trong sudt q u i trinh gia nhiet cim Ung thu dflpc bang eich phan tich ddng nhi^t truyen qua tam thep theo thdi gian, nhfl Iflu dd hinh 7.
Hinh 4. Miin gidiphdp trong phdn tich cua tdm thip.
Phan tich ddng nhiet va bien dang cua tam thep dupe sfl dung vdi chupng trinh FEM Abaqus 6.5 va chUPng trinh FORTRAN 77. Dp Idn cua ngudn nhiet dau v i o tren tam thep phu thudc vio khoing each tU cudn diy den be mat tam thep, ddng dien trong cudn day, be day tam thep trong gia nhiet v i tinh chat vat lieu tam thep. Tam thep dfldc sfl dung trong md phdng cd kich thfldc hai chieu: chieu d i i 500 mm, chieu rdng 250 mm v i vat lieu thep AH32.
Trong p h i n tich, tam thep dfldc nung ndng dpc theo mdt dfldng t i m vdi van tde khdng ddi theo mpt hfldng. Bdi vi, dieu kien ddi xflng true cua md hinh ngudn nhiet, nen mdt nfla tam thep dflpc chpn lim giai phap cho p h i n tich, hinh 4. Thdng sd gia nhiet dfldc chpn trdng di^u kien lam viec cua thiet bi thflc nghiem: Tdc dp di ehuyen dau tfl l i 5 -s- 22 mm/s, be day t i m thep 12 -H 22 mm, khoang cich tfl cudn day den be mat tam thep la 3 m m va ddng dien 720A vdi tan sd khdng ddi la 45KHz. Tam thep dfldc chia thanh 12000 phan tfl, kieu khdi 8 nut, kich thfldc phan tfl trong vung phan tich i n h hfldng nhiet la 2.5 x 5 X 1 mm, nhflng vung ma phan tfl d each xa ngudn nhi^t dfldc chia Ifldi Idn hdn, nhfl hinh 5. Nhi^t dp ban dau cua tam thep tfldng flng vdi nhiet dp phdng 20"C. Di^u kien bien cua tam thep: Chuyen vi theo phfldng x v i y cua canh trong mat phang ddi xflng dfldc co dinh v i ehuyen vi theo phfldng dflng dflpc cd dinh tai 4 diem trong mien Vi cua tam, nhfl hinh 6.
Hinh 5. l.ii'o'i phihi lu lioiii^ phuii ticli gin iiliicl cdm i(ng.
Hinh 6. Dieu kien bien cua tdm thep trongphdn tich.
Chfldng trinh chu dao cua md hinh dfldc xay dflng tren ed sd FEM va thflc hien vdi chfldng trinh FORTRAN 77 de tinh thdng Ifldng nhiet va ddng nhiet tren tam thep trong sudt qui trinh gia nhiet cim flng. Trong p h i n tich, lap lai mdi bfldc vdi cic dac tinh vat lieu cap nhat den gidi ban hdi tu. Kich thfldc vung anh hfldng nhiet sau phan tieh nhu hinh 8.
Magnelic Field
Tempctamre Field
T,
Updaled prapeilies
Hinh 7. LUu do phdn tich vd tinh todn thdng lUdng nhiet. '
T i n r i T t f - r i i r u f x n g x N A M V Sd 7 ( T h i n g 7 nam2012)
NGHIEN C U T U - T R A O D O I
H(?i/i 8. Vi'ing dnh hUdng nhicl ct'ui h'lni tiiep.
3.2. Thuc nghiem gia nhi^t cam flng De xiy dUng edng thUe tinh toan vung i n h hudng nhi^t va kiem nghiem vi?e phin tich, md phdng bien dang vi bien dang vung i n h hUdng nhiet cua tam thep trong gia nhi?t cim Ung, de tii tien h i n h thflc nghiem tren md hinh may d phdng thi nghiem md cua trfldng, vdi ngudn 3 pha 380V, ddng 18A. Trong suot q u i trinh gia nhiet cam flng, vung i n h hfldng nhiet cua tam thep dflpc nung ndng tfl nhiet dp phdng len den nhiet dp tfl 723"C ^ 2000"C, ndi ma kim loai d trang thii bien dang deo.
vung vung i n h hfldng nhi^t dflpc do tai mat cit ngang eua tam thep, mat p h i n g vudng gdc v6i hfldng dl chuy^i eua d i u tfl, nhfl hinh 9 va kich thudc vung i n h hUdng nhiet dflpc do d Trung Tim Kiem nghi?m C h i t Iflpng 3.
4. KET QUA P H A N TfCH VA T H I / C NGHI$M 'Ihdng Iflpng nhipt p h i n bd tflc thdi tren tam thep dflpc suy ra tfl p h i n tieh trUdng d i ^ tfl ehi dupe sfl dung cho thdng lUpng nhiet dau vio trong phan tich ddng nhict va bien dang ciia tam thep v i nd dfldc so s i n h vdi phan tich dong nhiet thay ddi tren tam thep, nhfl hinh 10. Ket qua so s i n h thay rang, thdng Iflpng nhi?t phan phdi tr^n tain thep vdi nhiet dp thay ddi li khong ddi xflng xung quanh cudn diy, dp Idn cua thong Iflpng nhiet Iji mat sau cua cupn day Idn hdn thdng Ifldng nhiet d phia trfldc cudn diy. Dieu n i y l i do ddng dien xoiy it dflpc sinh ra tren be mat tam thep, tai vung dflpc l i m ndng mi nhiet dp cao tren diem Curie, ndi ma dp dan di?n ciia vit lieu trd nen han che.
Hinh 9. Bien dang viing dnh hUdng nhiet tronggia nhiet cdm Ung.
Bien dang vung anh hfldng nhiet niy phu thupc vio efldng dp ddng dien ngudn eung cap, khoang each tfl vdng day den be mat tam thep, van tdc di ehuyen cua dau tfl, anh hfldng cfla ddi Iflu nhiet,... De xem xet bien dang vung i n h hfldng nhiet niy, de tai sfl dung 4 mau thep AH32 cho mdi lo^i kleh thfldc tfldng flng: 200 x 300 x 12 mm, 200 x 300 x 16 mm v i 200 x 300 x 22 m m va tdc dp di chuyen dau tfl l i 5-^l 1 mm/s. Bien dang
Hhih 10. TrUdng nhiet do phdn bo tren tdm thep:
(a) vdi trang thdi ddu; (b) vdi trang thdi thay doi.
Nhiet dp p h i n bd tflc thdi tren tam thef trong sudt q u i trinh gia nhiet c i m flng co thf dfldc suy ra bdi phan tieh ddng nhiet. Kich t h # HAZ trong p h i n tich dflpc do n g i u nhien tai vi tri bat ky trong sudt qua trinh gia nhiet v i kich thiJA vung i n h hfldng nhiet cfla tam thep trong thiJ(
nghiem dfldc dd tai m | t cat ngang cua tam thep mat phing vudng gdc vdi dfldng gia nhiet.
TAD rui rn w i \ntTj^A\ji •t* <;A 7 CThane 7 nam2012'i
NGHIEN CUfU-TRAOeOl
Hinh 11, the hien bien dang vung anh hfldng nhiet eua tam thep trong p h i n tich va thflc nghiem cua tam ed be d i y 16 m m , van toe di chuyen cua dau tfl 9 mm/s, khoang eich tfl vdng day den be mat tam thep 3 mm v i efldng dp ddng dien trong eudn day 720 A cho md phdng v i thflc nghiem.
Ket qui the hien tdt gifla phan tich vi thfle nghiem. Chieu sau HAZ trong phin tieh bang 5.83 mm va thflc nghiem bang 6.48 mm v i be rdng HAZ trong p h i n tich bang 49.35 mm v i trong thfle nghiem bang 47.7 mm. Sai so gifla hai ket qua do chieu sau HAZ bing 10,03 % va 3 46%
cho sai sd be rdng HAZ. Sai sd nay l i do sfl khdng ddng deu CLia vit lieu, tam thep thflc nghiem cd bien dang ban dau nen khoing cich tfl cudn diy den be mat tam thep cd sai leeh va do bfle xa nhiet trong thflc nghiem.
So lieu bang 1 the hien ket qui phan tieh kich thudc HAZ cua tam thep trong gia nhiet cim flng vdi cac thdng sd be diy tam thay doi va van tdc di chuyen eua dau tfl thay ddi tUdng flng. Sd lieu bang 2 the hien ket qua thfle nghiem kich thfldc vflng i n h hfldng nhiet cua tam thep trong gia nhiet cam flng vdi cac thdng sd be diy tam thay ddi va van tdc di chuyen cua dau tfl thay ddi tUdng Ung.
i
Hmh 11. Kit qud phdn tich:
(a) bdi phdn tich; (b) bdi thUc nghiem.
5. PHl/ONG TRINH HOI DINH KlCH T H l / O C VUNG QUY XAC ANH H l / d N G NHlfiT
Trong sudt qui trinh gia nhiet cam flng, vung kim loai chiu anh hfldng nhiet cua tam thep se dflpc nung ndng tfl nhiet dp phdng den vung nhiet dp tfl 723''C ^ 2000''C, ndi ma kim loai se d trang thii bien dang deo. Kich thfldc vung anh hfldng nhiet nay se li mdt ham phu thudc vio van tde di chuyen dau tfl (mm/s) va be diy eua tam thep dupe gia nhiet t (mm), khi khoing each tfl vdng d i y den be mat tam thep la khdng ddi (k = 3 mm), ddng dien trong cudn diy l i khdng doi (I = 720A) v i tan sd ddng dien khdng ddi (f = 45 KHz).
Bdngl. ThdngsoHAZ trong mo phong Abaqus.
t (Qim) 12 12 12 12 12 12 12
\' (mm/s) 5 7 9 11 15 18 22 16 ? 16 7 16
16 16 16 16 22 22 22 22 22 22 22
9 1 1 15 IS 22 5
"
9 11 15 IS 22
Nfta br i^ng H A Z (b m m )
26 955 25 81 24.855 23 59 21 78 19 06 16 57 25 76 26 12 24 6"^
23 6 20 505 IS 3 55 16 065 26 14 2< 0J5 12 615 22 435 19 565 16 2i5 14.355
Chtiu Sau H A Z 11i_mm)
10.19 S 71 7.4S 5-49 J.4 6 2 96 2 06
S 34 5 S3 4 5 2.96 2.21 i.4S 9 51 8 54 6 39 3 57 1.91 1.89 0.57
TAP CHl CO KHl VIET NAM V S6 7 (Thang 7 nam 2012)
NGHIEN cflu-TRAO ePi
g 2. Thong so HAZ trong thUc nghiem i^ui nhict cdm Ung.
b luc niy cd th^' dUpc viet lai dfldi dang tdng qudt
(mm) 12 12 12
16 16 16 16
--
22 22
(mm s) 5
-
9 11
5
-
9 11 5
9 11
b (mm) 2b (mm) j
54.0.t 10.IS .^2 03 8.91 J8 S.t •'.86 4",02 6 40 5.1 5.' 9.87
52.2 8.85 4^ f 6 48 4^ 1>) ^ 6
?.< 5 9.9 52.3 - 2 42.9 6.3 42.9 4.8
Tit so lieu bang 2. kich thiidc nila be rong ctia viing anh hil6ng nhiet la mpt ham phu thupc vao van toe va be day tam thep nhii sau:
b = av-t'' (10)
(!J day: a, a, |3 la nhiing he so, la van toe di chuyen dau tit, t la be day tam thep va b la nifa be rpng ciia viing anh hu6ng nhiet. Khi lay logarit hai ve, phuong trinh (10) CO the dupc viet lai nhu
+",(- : T > * ° . ( - ™ ^)'^°,(.,«„,.i»,l'* (13) Kft q u i do the hien gia tri niia be rpng HAZ \h inpt du6ng cong bac hai. Sit dyng phein m^m Statgraphics plus 5 va so li^u bSng 2, cdc h^ s6 <...u, v4 Uj dupc tinh:
„„ =-103.804,0, =502.672.0. =-482.816.
VSy phuong trinh t6ng quat nfla be rgngb dupc tim vdi h? s6 tflong quan R = 0.89.
* = -103,«O4t502,(i72(- -482.81«-; (14) Hinh 12, the hi?n moi quan he gifla van toe di chuyen cua dau tfl vdi nfla be rpng HAZ bdi mo phong, thflc nghiem va phflPng trinh hoi quy cua tam day 22 mm khi khoang each tfl cu$n day den tam thep la 3mm va efldng dp dong dl?n 720A, tflong flng.
Tflong tfl, tfl so lieu bang 2, kich thfldc chieu sau cita HAZ cung la mpt ham phy thuQC vao v^n toe va be day tam thep nhfl sau:
/i = a,v'''r (15)
log(6) = log(a) + a log(v) + p log(0 (11) Dat B = log(*), A = log(o), V = log(v), T = log((). Phuong trinh (11) co the dflpc viet l?i.
B=A+aV+pT (12) Tfl so li?u bang 2 v4 sfl dung phan mem Statgraphics plus 5, cac h? so a va [3 co the dflpc tinh toan: a = - 0.244215, (5 = .0.100563. Bdi vay, mia b^' rpng vung anh hfldng nhiet la mpt ham cua v""""" va / - » " « . Khi do, v""*"" va ,-»•«»'"
dflpc xem la nhflng bien dpc l | p va b la mot bi^n phij thupc. Phfldng trinh ham dang tong quat ciia
6 day: a.,a.,fi. la nhflng he so, (nunys) la van toe di chuyen dau tfl, t (mm) la be day tim thep va h (mm) la chieu sau cua vung anh hfldng nhift.
Khi lay logarit hai ve, phfldng trinh (15) CO the dflpc viet lai nhu sau:
log(A) = log(a) + a, log(v) + p, log(0 (1*) Djt W = log(A), 4 = l o g ( a , ) , K = log(v), r = log(/). PhflOng trinh (16) ed the dflpc vift Iji
H = A,+a/ + p,T („)
TAP C H l C O K H l VIET NAM s a 7 (Thang 7 nam 2012)
N G H I E N ClifU - TRAO DPi
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Hinh 12. Mdi quan he giUa bi rdng HAZ vdi van tdc di chuyen cda ddu td tronggia nhiet cdm Ung.
Tfl sd lieu bang 2 vi sfl dung phan mem Statgraphics plus 5, cac he sd a l va p 1 ed the dUde tinh toin: a l = - 0.734497, (3l = -0.322719. Bdi vay, chieu sau vflng i n h hudng nhiet l i mdt ham eua v"""'"'' v i / "'--"'^ Khi dd, v "''•'•'"'vi ,"''-"'"' duac xem l i nhflng bien ddc lap v i h l i mdt bien phu thude. PhUcfng trinh h i m dang tdng quit cua h luc nay cd the dUde viet lai dudi dang tdng quit sau:
^'-'„^-^|loJ,..-,J-'':il,„-.J„.:-,j'-".' „-J„i..J-- (18)
Tfl ket q u i do dUcfe d sd lieu bing 2, ta thay gii tri chieu siu HAZ l i mdt dUdng cong bae hai. Sfl dung phan mem Statgraphics plus 5 va sd lieu bing 2, cic he sd a,^,,a^,va a,, dUcfc tinh: UQ, =-7 00105,<j,,-235.756,a,, =-795.042. Vay phuong trinh tdng quit chieu sau dUdc tim, vdi he sd tuong quan R = 0.97.
- r ( i 9 )
h - -7.00105 + 235.756( , , ^ „ , ; „ „ J - 795 0 4 2 ( -
Hinh 13, the hien moi quan he gifla vin tde di chuyen cua dau tfl vdi chieu sau HAZ bdi md phdng, thUc nghiem v i phUdng trinh hdi quy cua tam day 22mm khi khoang cich tfl cudn day den tam thep l i 3mm v i cUdng dp ddng dien 1720A, tuong flng.
Hinh 13. Moi quan he giUa chieu sdu HAZ vdi van toe di chuyen cua ddu tU tronggia nhiet cdm Ung.
Khi ket qui td phUong trinh hdi quy dUOc so sinh vdi thUc nghiem, sai sd ti le phan trim cua nfla be rdng vung anh hUdng nhiet dUpc tinh toin la 11% v i 3% cho sai sd kich thude chieu siu vung anh hudng nhiet.
Khi ket qua tfl phUOng trinh hdi quy dUoe so sinh vdi ket qua md phdng, ta thay sai sd nfla be rdng vung anh hUdng nhiet dUpc tinh toan la 13.35% va 26.12% cho sai sd kich thUdc chieu sau vflng anh hudng nhiet. Ket qua ed sai sd niy l i do:
sfl khdng ddng deu eua vat lieu, tam cd sfl bien dang ban dau nen khoang eich tfl vdng diy den be mat tam thep cd sai lech trong sudt q u i trinh gia nhiet vi i n h hUdng cua bfle xa nhiet.
Ket qui phan tich the hien rang phuong trinh hdi quy ed the tinh toin tdt kich thUde vflng i n h hudng nhiet cua tam thep trong flng gia nhiet cam flng. Vdi nfla be rdng (b) v i chieu siu vung i n h hudng nhiet (h) dUpc tim, ket q u i niy cd the dupe ap dung cho phuong trinh (15) [9] (vdi h = d, t = ho), chuyen vi theo phuong vudng gdc vdi mat phang tam thep se dUpe tinh toan.
6. KET L U A N
Trong viee tao hinh bien dang tam thep bang phuong phap gia nhiet, sfl dung tan sd cao, cdng thUc don gian xac dinh moi quan he gifla kich thudc vung i n h hudng nhiet vdi cae tham sd"^
Txvmirn KHl VIET NAM Sd 7 (Thing 7 nam 2012)
NGHIEN ClJfU-TRAOD(!)l
gia nhi?t dupc de ra. De thUe hi^n myc dich niy, thdng lupng nhi^t dupc phan tich dau tien bdi mdt chfldng trinh FEM vdi gii dinh ring qui trinh la mpt trang thil ddng vi cung xem x^t ring tlnhchat cua vat li^u phy thudc vionhi?tdd. ViC^e phin tieh ddng nhi^t vi bie^n dang nhi^t sau dd dupe thflc hi?n vdi mpt chUdng trinh FEM vdi thdng Iflpng nhi^t dupc suy ra Iruoe dd vdi cae thdng sd gia nhi?t lien quan. Phin tich md hinh the hien ring, khi giim vgn loe di chuyen cua dau tfl va be day tam thep thi kich thUde vung inh hudng nhi^t tang tUdng flng. khi ket qui phin tieb dflpc tdng hpp vdi pbUPng phip thdng ke, cdng thfle ddn giin xic dinh mdi quan h^ gifla kich thude vflng inh hUdng nhi?t vdi cac tham sd gia nhiet lien quan ed the dflpe suy ra. Cdng thflc dupe suy ra, cho thay ring kich thUdc be idng vflng anh hudng nhiet la mdt ham eua v""^"^"
va i~° ""**' chieu siu vung anh hUdng nhiet la mdt him cua v""''^" vi ;-"""", tUPng flng. Mdt loat cic phan tich md phdng dUpc so sinh the hien ring, phUdng trinh hoi quy cd the tinh toan tdt kich thudc vung inh hUdng nhiet vdi eic tham so gia nhiet lien quan trong gia nhiet cim flng vdi sai sd dUpc so sinh 13.35%, cho kich thUde nfla be rdng viing anh hUdng nhi?t va 26.12%
cho kich thudc chieu sau vung inh hUdng nhi^t tUPng flng. <•
Ngiy nhin bii: 26/5/2012 Ngay phan bien: 02/6/2012 NgUdi phan bien:
1. PGS, TS. Nguyen Ngoc Phfldng, 2. TS. Trfldng Nguyen Vu
fied mathematical formulas for the prediction of deforim- lions in ihe plale bending process using an oxy-propane gas name, JHM1264 _ IMechE 2008.
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|3]. A. Boadi, Y. Tsuchida, T. Todaka, M, Enokizono, De- signing of suitable construction of high-frequency induc- tion heating coil by using finite-element method, IEEE Transaclions on Magnetics 41 (10) (2005) 4048-4050. ' [4]. ,S,(., Chen, H.S. Peng. J.A. Chang. W.R. Jong, Simula, lionsand verifications of induction heating on a mold plate, International Communications in Heat and Mass Transfer 31 (7)(2004)971-980.
I5|. J. Nerg, Numerical solution of 2D and 3D induction heating problems with non-linear material properties taken into account, IEEE Transactions of Magnetics 36 (5) (2000)
3119-3121. 1 [6|. V Cingoski, n.. Namera. K. Kaneda, H. Yaniasliil|,
Analysis of magneto-thermal coupled problem mvolvii^
moving eddy-current conductions, IEEE Transactions of Magnetics 32 (3) (1996) 1042-1045.
17]. Kang-Yul Bae a, Young-Soo Yang b,_, Chung-MlnfiTO c, Si-Hun Cho c, Derivation of simplified formulas to pre- dict deformations of plate in steel forming process with in- duction heating, InternaUonal Journal of Machine Tools &
Manufacture (2008).
[8|. C.-D. Jang, M.-K. Kim, V.-S. Ha, Prediction of plate bending by high-frequency induction heating. Journal rf Ship Production 18 (4) (2002) 226-236.
I9]. Truong-Ttiinh Nguyen, Young-Soo Yang, Kang-Tful Bae, The development of an artificial neural network m o ^ to predict heating-line positions for plate forming in induc- tion heating process, Internation Journal of Machine To<|s 8t Manufacture, Volume 37, Aprd-June 2009.
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Tai lieu tham khao:
II]. K-Y Bae, Y-S Yang, C-M Hyun, and S-H Cho, Simpli-
TAP CHi CO KHf V I £ T NAJVI • Sd 7 (Thing 7 nam 2012)
