NGHIEN CUfU-TRAODd
PHONG VA T H V C NGHIEM T R U O N G D I £ N T 0 V A THONG LUONG NHIET P H A N B 6 T R £ N T A M T H E P TRONG GIA N H I E T CAM U>^G
: M U L A T I 0 N S A N D E X P E R I M E N T S O F ELECTROMAGNETIC FIELD AND HEAT FLUX DISTRIBUTION ON THE STEEL PLATE IN INDUCTION HEATING
NCS. Tran Thi Thiiy Nga', TS. Nguyen Trfldng Thinh^ PGS, TS. Tran Thu Hi^
'Trfldng Cao dang Ky thuat Cao Ihang
^TrUdng Dai hpe SU pham Ky thuat Tlianh ph6 Hd Chi Minh
I T A T
Detao hinh bien dang cua thep tam bdng nguon nhiet, phUdng phdp gia nhiet cdm dngdUdcsii I de thay the cho nguon nhiet khi Oxy-axetylen, von khong cd nhieu Uu diem trong viec tao hinh bien J thep tdm vd tau. Gia nhiet cdm dng Id phUdng phdp dUa tren hien tUdng cdm dng dien tii, khi cho I dien tdn so cao chay trong cuon ddy, ddng dien ndy se sinh ra xung quanh nd mot tii trUdng hien 1 theo thdi gian, cd tdn so ciing vdi tdn so ci^a ddng dien trong cudn ddy. Khi ta dat ben dUdi eudn ddy,
^ vung dnh hUdng ciia tii trUdng mot tdm thep, thi trUdng dien td ndy se tao nen mgt ddng dien khep ren be mat tdm thep vd nung ndng tdm thep theo hieu dng Joule-lenz. Tren cd sdphdn tich FEM, mdt I gidi phdp cho phdn tich bao gom cuon ddy dang dia vdi mgt niia vdng ddy doi xiing true dUde ldm
; vat lieu dong, tdm thep vdi vdt lieu AH-32 vd vung khdng khi cho phdn tich. Khi tdn so dong dien ig doi, mat do trUdng dien tii vd thdng lUdng nhiet phdn ho tde thdi tren tdm thep thay doi khi edc 1 so gia nhiet thay doi nhU: be ddy tdm thep, khodng edeh tii vdng ddy den be mat tdm thep vd eUdng dng dien trong cudn ddy. Sd thay doi ndy tao nen mgt vung dnh hUdng nhiet tdc thdi, tUdng dng md Udc sd dung nhu mot nguon nhiet ddu vdo trongphdn tieh ddng nhiet vd bien dang cua tdm thep ', phUdngphdp gia nhiet cdm dng.
TRACT
To control the deformation of plate in the steel forming process with heating, the electro-magnetic uction process has been used as the substitute of the flame heating process, which did not have many vantages in deforming the steel hull plates. Induction heating, a method based on the phenomenon of ztromagnetic induction, when the high-frequency current flows through an inductor that is located zr the conductor of a steel plate. This current generates a magnetic field around it varies over time, with quency the same the frequency of electric current in the inductor. This electromagnetic field generate on teel plate surface an eddy current and steel plate heated by Joule-Lenz effect. On the basis of FEM analy- . an analytical solution domain consists of a disk coil with a hafl symmetrical axis are made of copper, el plate with the material properties of the AH32 steel and air With frequency is constant, electric field d density of heat flux distribution on steel plate are change when heating parameters changes, such as ckness of steel plate, distance from the coil to steel plate surface and current in the coil. This changes ate an instantaneous heat affected zone, respectively, which it is used as source of the heat input for heat w and thermal-mechanical deformation of steel plate in induction heating method.
Keywords: Finite element method. Induction heating, Numerical analysis. Electro-magnetic in- iction, Heatfiux analysis, HAZ.
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NGHIEN CUfU - TRAO D O I
l.GICflTHlfiU
Vi^c tao bien dang ta'in thep vd tiu trUdc khi lap gh^p vio eac phan cua than tiu li mpt khau quan trpng trong nginh ddng tiu, tao nen chat Iflpng eua mdt chiec tiu vi ning cao khi nang canh tranh tren thi trfldng. Qui trinh lao hinh bien dang thep tam vd tiu hi^n nay chu yeu sU dyng cic phUPng phip truyin thdng, vdn khdng linh hoat va kim hi|u qui kinh tl. Die biet li phUdng phap tao hinh bien dgng vd tiu bing ngudn nhi?t sfl dung diu ddt khi Oxy-axetylen [1], chat lupng tao hinh bl mat eung nhfl biln dang cua tim thep phy thupc rat nhieu vio tay nghe ngUdi thp vi khd kiem soat ngudn nhi?t dau vio trong sudt qui trinh gia nhiet, dieu niy lim giim hilu qua eua phflpng phap.
Gia nhiet earn flng li phUdng phap dUde sfl dung de thay the cho ngudn nhiet khi Oxy- axetylen, vdn khdng cd nhieu Uu diem trong vile tao hinh bien dang tam thep. Khi gia nhiet cim flng dupe ap dung eung vdi vile tich hpp robot cho vile tfl ddng, qui trinh udn biln dang tam thep se trd nin de dang dieu khien va kinh te hdn cie phfldng phip cu. Die biet, doi vdi cic tam thip vd tau ed bien dang phfle tap, phUdng phip gia nhiit cam flng the hiln rd kha nang toi flu.
Cic de tii nghien cflu ve phfldng phap gia nhiet cim Ung trong bien dang tam thep da dupe cdng bd, phan bd nhiet hai chieu 12.3] trong sudt qui trinh gia nhiet cam flng vdi tan sd gia nhiet cao li nhflng chu de chinh trong hau het cic nghien cflu vi trang thii bien dgng ba chieu cua tam thep dflpe md hinh hda bdi phan tich. Tuy nhien, trong cae nghiln cflu da dflpc cdng bd, chfla the hi^n rd mdi quan he gifla kich thfldc viing inh hfldng nhiet cua tam thep vdi cic thdng sd lien quan trong sudt qui trinh qua trinh gia nhiet cam flng mi dilu nay nd tao nen bien dang khic nhau cua tam thep.
Trong nghien cflu nay, mdt thdng Iflpng nhiet tfle thdi phan bd trin tam thep mi nd dflpc xem la mdt ngudn nhi^t dau vao trong phan tich ddng nhiet va bien dang tam thep se dflpc phan tich trin cp sd FEM [4]. Trfldng di?n tfl vi thdng
lupng nhi?t phan bd tflc thdi tren tam thep dUi?
phin tieh vdi cic tham sd gia nhi^t thay doi, t^
nen vung inh hfldng nhi?t khic nhau trin cdsi phin mem COMSOL 3 4 [5]. Mpt loat cac thilt nghiem sau dd se kiem chflng ket qua dat dii^Jc trong phan tich.
2. PHAN TfCH TRUOiNG DlfeN TlT CHO
T H O N G Ll/ONG N H I £ T
Khi cho ddng di|n xoay chieu, cd tan so cao chay qua mpt cupn diy. dflpe dit tren mgt tim thep, nhu hinh 1, mdt chum tfl thdng xuy^n qua bl mat cua tim thep ma nd ddng true m cudn diy. Vi viy, ddng dien xoay dflpe sinh ra tai bl mat cua tam th^p. Ddng di?n cam flng sinh ra nhi?t di|n trd trin tam thep theo hieu flng Joule vi dieu niy cd the dung de udn tam thep.
1 ruinii! iticn Us
thiw tli'i Wt;^ Jicn \ i u \ chicu
Hinh } . Mo hinh tdng qudt cua gia nhiet cdm Ung.
Phfldng trinh can bing cho ddng dien xoiy phan bd trong qua trinh gia nhiet cam ling cd the dupc suy ra tfl h? phflpng trinh Maxwell trong vung tan sd cho phep [6],
-V'A-t-j(oaA = J^ (11 6 diy: gpi la toan tU Laplace, la vecto di?n the tfl , mat dp ddng di^n ciia ngu6n trong cupn day, la dp tfl tham, li van tdc gdc \^ la ^^
dan di^n. Khi veetd di^n tieh cua phUdng trinh (1) dflpc phan tich ddng dien xoay va thong lupng nhiet phan bd tren tam thep cd the diif^
tinh toan. Khi phfldng trinh (1), dflpe giai bang phflpng phap phin tfl hflu han, nd dUdc viet nhil
TAP CHf CO KHf V I £ T NAM S6 7 (Thing 7 nam 20I2J__
NGHIEN Cflu-TRAO 061
•[K][AMJ] (2)
, i rik
+jaic7|[A']' [N]da (3)
[j]=ljMdn (4)
. 1 i Mill); cua L'uyii day Mivii 1116 pliniit!
'^ 1.5 mm j ^ \ '
Tam ihcp il
Vfli vecto dien tich diJoc riit la tiJ phiiang ' trinh (2), nhiet dien trd co the duoc tinh.
I' , ' (5)
(a)
Hrnh 2 Mo hinh tong qudt cua cudn day vh tdm thip trong mo phdng trudng dien td.
- & day J^=ai-dA/di) la mat dO CLia dong j
;d.enxo., ^ j O O P
Thdng lupng nhiet trung binh trong mien ' tan sd cd the dUpc tinh.
q = -fqdl^~(<i> 'AX+a> ^A^A\) (6) ' ®
1 doi xvtng true
2,3vii4. cdch dien vdt moi trUdng ngodi.
O d i y A' l i Uln hpp phfle cua A Hinh 3. LUdiphdn tdvd dieu kien hien trongphdn tich.
3. TRU'CfNG DIEN T C VA THONG LUONG NHIET P H A N B 6 T0C THOil TRONG GIA I NHIET CAM LTNG
Ddng dien cd tan sd cao chay trong eudn diy, gay nin tfl trfldng xung quanh nd, neu dit trong tfl trfldng nay mdt vit mdt tam thep thi tfl trudng nay se gay nin mdt ddng dien khep kin tren tim thep vi dot ndng tam thep theo hilu Ung Joule. Hinh dang va kich thUde vung inh hfldng cua tfl trfldng tren be m^t tam thep phu thude vao hinh dang cudn diy, efldng dp ddng dien ngudn trong cupn day, vat lieu lam cudn diy, khoang each tfl vdng day den be mat tam thep, tinh chat cua vat lieu tam thep vi be diy tam thep. Cfldng dp trfldng dien tfl dflpc phan tich tfl phflpng trinh (1) va md phdng vdi phan mem COMSOL 3.4.
Hinh 2, the hien md hinh dupe sfl dung cho phin tich. Cudn day bang dong, dflpc thiet ke dang dia va doi xflng true nin dupe md hinh hda vi md phdng mdt nfla dfldi dang 2D gdm 3 vdng day, dfldng kinh mdi vdng diy la 6 mm, ban kinh cua cudn day li 30 mm, khoing each gifla hai vdng diy bang 1.5 mm. Tam thep trong md phdng bang vat lieu thep AH_32. Be diy tam thep (d) thay ddi:
10 mm, 15 mm, 20 mm, 25 mm vi 30 mm. Khoang cich tfl vdng day den be mat tam thep trong md phdng thay ddi tfl 1.5 -;• 5 mm. Dp din dien cua thep AH_32:6.02e4 [S/m]. Dp dan dien cua vat lieu cudn day: 7.40e7 [S/m]. Tan sd ddng dien khdng ddi, f = 45 KHZ vi ddng dien thay ddi tU 500 A -^
1000 A, cho mdi trfldng hpp md phdng. Mien md phdng dflpc chia Ifldi kieu tam giac vdi 7072 phan tfl vi dieu kiln bien cho giii phap nhfl hinh 3. ^
TAP CHf CO KHf V I E T NAM • Sd 7 (Thing 7 nam 2012)
NGHIEN CIJfU-TRAOD6l
4. THUC N G H I £ M T H O N G L U ^ N G N H I £ T T C C THCJI P H A N B O T R £ N T A M T H £ P
De thUc nghiem phin tich trfldng di^n tfl vi thdng Iflpng nhi^t phan bd tflc thdi I ren lam thep trong gia nhi^t cim flng, de tii sfl dyng thep tam AH32 cho phan tieh, tam thep dflpc dit ngay ben dfldi cupn day. Ddng di?n eh?iy trong cupn diy, sinh ra tU trUdng xung quanh nd vi tao ra mpt dong dien khep kin trin bl mat tim thip vi nung ndng tim thep theo hi|u flng Joule-Lenz.
7. Thdng Iflpng nhi?t tflc thdi dflpc suy ra tfl phi lich trUdng di?n tfl phin bd tren tam thep thei hi?u flng Joule-Lenz, Iflu do hinh 8 va be r^nj vung dnh hfldng nhi?t tflc thdi trin tam thq dflpc phin tieh, hinh 9.
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Hmh ('. Mill dd tiuongdicn lu ^iiih w vn plumb trai U'lin Ihcp.
Hinh 4. Md hinh mdy gia nhiet cdm dng.
Hinh 4 the hiln dau gia nhiet dflpc sfl dung trong thflc nghiem. Tan sd ddng dien ngudn 45 KHz, ddng dien trong cudn day thay ddi tfl 500 A den 800A, tam cd be diy thay ddi tfl 12 mm den 22 mm vi khoang cich tfl vdng diy den be mat tam thep li 3 mm. Ket qui phan tich dflpc do tai mat cat ngang cua tam thep, mat phang vudng gde vdi hfldng di ehuyen cua dau tfl, hinh 5.
bl
Hinh 7. Tdng mat do ddng dien phdn bd tren tdm thep [A/m'l..
0 = — jJ.l'*20°C >• -
Hinh 5. Bien dang vung dnh hUdng nhiet tdc thdi '" ' tronggia nhi^t cdm dng.
5. KET QUA PHAN TfCH VA THlTC N G H I £ M
Trfldng dien tfl sinh ra xung quanh cupn ~ T diy va phin bd trin be mat tam thep, tai vung anh ' ""^
hfldng cua tU trfldng, hinh 6. Tdng mat dp ddng Hinh 8. LUu do tinh nhiit ciia viing dnh hUdng tt dien sinh ra va phan bd tren tam thep nhfl hinh tdc thdi tren tdm thip
TAP CHf CO KHf VIET NAM • Sd 7 (Thing 7 nam 2012)_
NGHIEN Cflu - TRAO D 6 |
b^- BS rdng viing dnh hitdng nhiit /i|, Chilu sdu vdng dnh hUdng nhi(t
Hinh 9. Kich thUdc vitng dnh hUdng nhiet tdc tiidi tronggia nhiet cdm dug.
Kich thfldc vung i n h hfldng nhiet d trang thai p h i n tich tUc thdi phu thupc vio b l diy tam thip, khoang cich tfl vdng day den b l mat tam thep vi efldng dp ddng dien ngudn eung ci'p, khi tan sd gia nhiet khdng ddi, f = 45 KHz.
Dieu niy l i do, khi khoing each tfl vdng day den be mat tam thep li nhd nhat (1.5 mm) thi flng vdi ddng dien cd gia tri efldng dp tflpng flng, tU trfldng CLia ddng dien sinh ra xung quanh cudn diy vi thim siu hdn tren be mat tam thep so vdi khi lam thep de cich xa vong day hdn theo hilu Ung be mat, nin be rpng vung i n h hfldng nhiet tflc thdi sinh ra tren tam thep cung ed gia tri khae nhau, tflpng flng.
Khi khoing cich tfl vdng diy den be mat tam thip thay doi, flng vdi cae gia tri ddng dien tfldng Ung thi cung nhU be rdng vflng i n h hfldng nhiet, chieu siu vung i n h hfldng nhiet eung se thay ddi tfldng flng. Hinh 11. the hien mdi quan he gifla chieu siu vung anh hfldng nhiet vdi khoing eich tfl vong day den b l mat tam thep khi eUdng dp ddng dien la khdng ddi cua tam day 10 mm.
1
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Hinh 10. Mdi quan he giUa he rdng HAZ vdi khodng cdch, khi ddng dien khong doi.
Hinh 10, the h i l n mdi quan he gifla be rdng vung anh hfldng nhiet tUc thdi trin tam thep vdi khoing each tfl vdng day d i n be mat tam thep khi eUdng dp ddng dien thay ddi eua tam thep day 10 mm. Ta thay, khi khoang each tU vdng day den be mat tam thip l i nhd nhat (1.5 mm) thi be rpng vung anh hUdng nhiet tflc thdi t r i n tam thep la Idn nhat flng vdi cic gii tri cUdng dp ddng dien tuong flng va ngUdc lai, khi khoang each tfl vdng day den be mat tam thep Idn 3 m m thi be rdng vung anh hfldng nhiet tfle thdi tren tam thep la 'nhd nhat flng vdi cic gia tri ddng dien tflPng flng.
Htnh 11. Mil quan he giUa chieu sdu HAZ vdi khodng cdch, khi cUdng do ddng diin khdng doi.
.-.^
^^
Ciirvni Deatitv i
Hinh 12. Moi quan hi gida be rong HAZ vdi cUdng do ddng diin, khi khodng cdch khong ddi. '"
C 0 KHf V I £ T NAM V Sd 7 (Thing 7 nam 2012)
NGHIEN c f l u - TRAO D O I
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••I
Hinh i3. Moi quan he gida chi^u sdu HAZ vdi cUdng dd ddng dien, khi khodng cdch khdng ddi.
Ta thiy, khi khoang cich tfl vdng diy den b l mat tam thep (> 3.5 mm) thi chieu siu vung i n h hfldng nhiet tUe thdi trin tim thep li nhd nhit. Dieu niy l i do, khi khoing each tfl vdng diy den be mat tam thep li nhd nhat (1.5 mm) thi flng vdi ddng dien cd gii tri cfldng dp tflpng Ung, tU trudng eua ddng dien sinh ra xung quanh cupn diy va tham siu hPn tren be mat tam thep so vdi khi tam thep de each xa vdng day hpn theo hilu flng be mat, n i n be rdng vflng i n h hfldng nhiet tflc thdi sinh ra trin tim thep cung cd gii tri khic nhau tfldng Ung.
Khi khoing cich tfl vdng diy den be mat tam thep l i khdng doi va be diy tam thep thay ddi. Kich thude HAZ tUc thdi trin tam thep thay ddi khdng dang ke. Hinh 12 v i hinh 13, the h i | n mdi quan he gifla be rdng v i chieu siu vung anh hudng nhiet tflc thdi tren tam thep cua cic t i m diy 10 -^ 30 mm, khi khoang cich tfl vdng diy den be mat tam thep l i 3 mm tfldng flng.
Ta thay, khi khoang each tU vdng day den be mat tam thep li khdng ddi nhflng be d i y tam thep l i thay ddi thi kich thfldc HAZ tflc thdi tren tam thep thay ddi khdng ding ke. Dieu niy li do, khi khoing each tfl vdng day den be mat tam thep la khdng ddi, cfldng dp tU trUdng xung quanh cupn day sinh ra bdi ddng dien ed gia tri tUPng flng l i khdng doi thi vung anh hfldng cua tfl trfldng t r i n
be m i l cae t h i m thep cd kich thfldc khic nhaul khdng ddi. Vdi cic tam thep cd eung tinh chit,i^
li?u dupc xem li ddng nhat thi b l rpng va chlft sau cua vung i n h hUdng tfl trfldng tren tamth^
li nhfl nhau n i n vung i n h hfldng nhi?t tflc thifi sinh ra bdi hi^u flng Joule-Lenz tren cac timth^
l i nhfl nhau.
Tfl dd thi cic hinh 10 den hinh 13, ta thiy be rpng v i chilu siu vung i n h hfldng nhiet tflc thdi se thay ddi khi khoang cich tfl v6ngday den b l m i l tim thep thay ddi, cfldng dp ding d i | n trong cupn diy thay ddi v i khi b l diy tam thep thay ddi. Die biet. 6 hinh 10 vi hinh 11,1a thay: Khi khoing each tfl cupn diy den be mat tain thep Idn hdn hoac bing 3.5 mm thi viinganli hfldng nhi|t tflc thdi tren tam thep khdng dang ke, t h i m chi bang khdng. \'i viy. can chii y din khoing cich tfl vdng day den be mat ehi tiet troi^
tat ca cic flng dung gia nhiet cam flng. Khoang cich tdi Uu tfl 1.5 mm den 3 mm.
I
Hinh 14. HAZ tdc thdi tronggia nhiet cdmj (a) trongphdn tich; (b) trong thUc nghiim^
Hinh 14, md t i vung anh hfldng nhietliJc thdi trin tam thep dflpc suy ra tfl phan tich^'a thflc nghi?m khi khoing cich tfl vdng day d&i«
mat tam thip bing 3 m m , tan sd ddng di^n 45 KHz v i ddng di^n trong cudn day 800A cuatSm thep day 16 mm.
TAP CHf CO KHf V I £ T NAM • Sd 7 (Thing 7 nam 2012)
NGHIEN Cflu - TRAO Ddi
Ket qua gifla phan tich va thflc nghiem the hi^n tdt kich thUdc vung i n h hfldng nhiet tUc thdi j h i n bd tren tam thep. Sai sd 4.03% gifla b l rpng HAZ tUc thdi trong phin tich va thUc nghiem va 15.3% cho chieu sau HAZ tUc thdi trong p h i n tieh vi thflc nghiem. Dilu niy la do sfl khdng ddng d i u tua vit li^u cua eudn day cung nhfl vat lieu tam thep.
S. KET LUAN
Gia nhiet c i m flng dfla tren hien tflpng cim Ung di^n tU. Khi cho mdt ddng dien cd tan sd cao :hay trong eudn diy, ddng dien niy se sinh ra xung quanh nd mdt tfl trfldng bien thiln theo thdi gian, :d tan sd cung vdi tan sd cua ddng diln ngudn. Cfldng dp eua tU trfldng phu thudc vao vit lieu lim zudn day va mat dp ddng dien trong cudn day. Vdi tinh chat tam thip dflpc xic dinh, khi khoing each tfl vdng day d i n be mat tam thep thay ddi, b l diy tam thep thay ddi v i cfldng dp ddng di^n trong cupn day thay ddi thi trUdng dien tU p h i n bd tren tam thep eung thay ddi tUdng flng, m i dilu niy tao nen vung anh hfldng nhiet tUe thdi khic nhau tren tam thep m i nd dupe dung nhU mpt ngudn nhiet dau
"vio trong phan tich bien dang tam thep trong gia nhi|t cam flng. •
iNgiy nhan bii: 26/5/2012 Ngiy phan biln: 02/6/2012 -Ngfldi phan bien:
.1. PGS. TS. Nguyen Nggc Phfldng 2. TS. Trfldng Nguyin Vu
Tai lilu tham khao:
[1]. K-Y Bae, Y-S Yang, C M Hyun, and S-H Cho, Simplified mathematical formulas for the prediction of defor- mations in the plate bending process using an oxy-propane gas flame, JEM1264 _ IMechE 2008.
[2]. 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.
[3]. V. Cingoski, A. Namera, K. Kaneda, H. Yamashita, Analysis of magneto-thermal coupled problem involving jnoving eddy-current conductions, IEEE Transactions of Magnetics 32 (3) (1996) 1042-1045.
.[4]. E Bay, V. Labbe, Y. Favennec, J.L. Chenot, A numerical model for induction heating processes coupling electromagnetism and thermomechanics, Int. J. Numer. Meth, Eng. 58 (2003) 839-867.
15]. Matej Kranjc, Anze Zupanic *, Damijan Miklavcic, Tomaz Jarm, Numerical analysis and thermographic investigation of induction heating. International Journal of Heat and Mass Transfer 53 (2010) 3585-3591 [6]. K. Sadeghipour, J.A. Dopkin, K. Li, A computer aided finite element experimental analysis of induction heating process of steel. Computers in Industry 28 (1996) 195-205.
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