Calculation of Solidification Process of Continuous Cast Bar

Journal of Harbin Institute of Technology ( New Series)，Vol.21, No.5, 2014Calculation of Solidification Process of Continuous Cast BarA I Golodnov, R K Mysik, A V Sulitsin, S V Brusnitsyn, I A Gruzdeva( Ural Federal University, Russia, Ekaterinburg)Abstract: In this paper, it presents the results of calculation of solidification process of copper continuous castbar by cross section size 120 mmx 70 mm with application of ProCast 2010 software. The estimation of moulddesign effect on solidifcation process of continuos copper cast bar is completed at various speeds of casting.Profiles of liquid metal cavities and temperature allocations in the cast bar at various casting speeds are defined.The analysis of received liquid metal cavity profiles shows that a new mold construction allows significantlydecrease of the length of the liquid metal cavity during continuous copper casting at HAZELETT8 castingmachine and the increase of maximum casting speed from 10 to 11 m/ min. Adequacy of the results of coppercontinuous cast bar solidification process calculation is confirmned by the experimental data.Keywords: continuous casting; copper cast bar; water cooling mold; liquid metal cavity; heat enmissioncofficient ; calculation of solidification processCLC number: TG29Document code: AArticle ID: 105-9113( 2014)05-0112-07HAZELETTA twin-belt continuous casting machine belt1 Introductionmold of which is situated with small angle of slope( about 15 degrees ) after which fourteenth standsAt present time CONTIROD line can be used forrolling mill is installed with coiler at the endproduction of copper rod. The line consists of(Fig.1).，310, 14F--1617; 19~181- - Cathodes charging device ( skip hoist), 2- -Melting shaft furmace, 3- Holding fumace, 4- Launder, 5- -Twin-belt continuous casting machine, 6-Slag removing vessel, 7- -Control panel, 8- -Pinch roll No.1, 9- -Pendulum shear, 10一Edge scalping or milling machine, 11- THyuue pinch roll N2, 12- 14-th Stands rlling mill, 13- -Pickling and cooling line, 14- Pinch roll No.3, 15- Wax application unit, 16, 17- Coiler, 18- -Coils lifingtable, 19- Rolling tableFig.1 Scheme of CONTIROD copper rod production lineThe main features of the HAZELETT@ twin-beltapplied for steel belts which are uniformly cooled downcontinuous casting machine are designed with mold andalong the mold via nozzles. W ater consumption isare complex cooling water circulation systems. V ertical600 m'/h.mold walls are presented by bronze dam blocks withDam blocks chains has more complicated cooling50 mm thickness. Horizontal mold walls are in the formsystem. In the mold， there are steel water coolingof steel belts with the thickness 1. 2 mm. Having suchguides，preventing horizontal moving of the dammold design, their walls are moving together with theblocks- Dam blocks cooling is taking place by thcast bar with equal speeds 9-11 m/ min.cont中国煤化工s, which has13.7 mmHAZELETT⑧continuous casting machine hascylin|YHC N M H G water circulation. Tcomplicated walls cooling schemes. Water cooling isdecrease tricuon, the 1ron bar is installed in betweenReceived 2013-06- 18.Corresponding author: A I Golodnov. E-mail: kafedralp@ mail.ru.●112●Journal of Harbin Institute of Technology ( New Series)，Vol.21, No.5, 2014guides and dam blocks. Water consumption in the guidesToday new types of water cooled guides appear,is 50 m'/h. After coming out from mold dam blockswhich provide uniform cooling of the dam blocks chainschains go through water cooling chamber to cool down tillin the mold. There are two 11.2 mm cylindricaltemperature appropriate to start casting 100 土10 C.channels in the new type construction of the steelCurrentlyHAZELETT continuouscastingguides. Using such type of guides, there is no need inmachine allows producing continuously cast copper barusing of iron bar to decrease friction. In addition newwith cross-section 120 mmx70 mm with casting speedtype of guides pressed to dam blocks by special springs10 m/ min. The efforts to increase the casting speed tillwhich allow eliminating the gap between dam blocks .11 m/min will result in cracking of the cast bar andand cast bar. Consequently new type of guides allowsbreakthrough of the molten metal at the exit from theimproving heat removal conditions from the moldmold.considerably.Probability of such defects forming in the cast barduring continuous casting first of all defined by2 Experimentaltemperature distribution on the cross-section of the barat the exit from the mold. It is necessary to provideIn view of aforesaid, the task was assigned tocomplete solidification of the cast bar in the limits ofevaluate the influence of mold construction on theprimary cooling zone and prevent the cavity coming outsolidification process of continuously cast bar atfrom the mold limits. Thereby it is necessary todifferent casting speeds by ProCast 2010 software. Tcintensify heat exchange in the mold to increaseconduct the 3D model calculation of the cast barproductivity of the HAZELETT@ continuous castingsurrounded by steel belts and dam blocks chains wasmachine and decrease probability of the incidentsbuilt, on the basis of which the volumetric net was .occurrence during casting.generated ( Fig.2).Fig.2 Cross-section of the elements’volumetric net, for carrying out heat calculations in the ProCast 2010 softwareSince heat exchange process between solidifyingcoolingmedia temperature to determinecast bar and mold during continuous casting is veryconditions in the ProCast 2010 software. To determinecomplicated tfollowing assumptions has beenthe convective heat transfer coefficient, it is possible toaccepted for theoretical description of the heatuse similarity theory to convective heat transfer study.exchange process' 2-41 :Heat transfer coefficient at convective heat exchange isAxis heat conductivity is neglected;determined by Nusselt 's similarity criterion-Nu5l. At .Casting temperature of the molten metal isturbulent mode of liquid flow, Nusselt' s criterion canconstant and amounts 1120 C .be calculated by the following criterion relation:To solve the assigned task in ProCast 2010, it is0.0396●Re+●Prnecessary to define boundary conditions ，determine中国煤化工，+ .(Pr- 1)]- (1cooling of the mold walls,and set heat emissioncoefficients on the metal-mold boundary.wher.MYHC N M H Grity criterion; Re is theSteel belts contact with water flow from theReinolds similarity criterion; Pr is the Prandtlopposite to cast bar side， that is why it will besimilarity criterion.sufficient to set convective heat transfer coefficient andIt was determined by experience that at steel belts.113●Journal of Harbin Institute of Technology ( New Series)，Vol.21, No.5, 2014cooling, water temperature at the entrance to the moldzones.The first zone is situated in the cast bar surfacewastp=20Cbutattheexit-tp2=22C.Onthe.temperature range from 1120 to 1080 C. In this zonebasis of well-known physical properties of water andmold walls are in contact with molten metal. Sincemold construction， the value of Nusselt similaritymolten metal enters into the mold by streamline flowcriterion was determined Nu = 2. 297x10*. On the basethe heat emission coefficient in this case is determinedof data received， it was determined, that convectivefor free melt convection in the closed space. In theheat transfer coefficient from mold steel belts side is a|second zone the cast bar surface temperature is belowW1080 C，starts formation of solid sinter skin, which= 5. 487x10*-m2. K'starts to move away from mold walls gradually becauseBoundary conditions for dam blocks were definedof shrinkage of the metal. As a result, the heat fromas the distribution of heat flow density on the length ofcast bar surface to mold walls is transferred by radiationmold. In accordance with the data‘ 。 ”considering thisand heat conductivity over air gap. The size of the gaptask, one can admit, that the heat flow density throughwas determined on the basis of mold adjustments andall mold elements is a constant value. Thereby， forlinear dimensions of the cast bar at room temperaturedetermining boundary conditions it is sufficient tctaking into account the thermal expansion coefficient ofestimate heat flow density from guides to cooling water.copper'The calculation results are presented inFigs.4 and 5.The heat flow density is estimated by:During the calculations of cast bar cooling usingx2●(12 -t1)new type guides， it was assumed that heat exchangeSbetween cast bar and dam blocks occur in tight contactwhere Q2 is the convective heat emission coefficient ，conditions on the whole length of mold. Therefore, inm2. K; t2 is the average mass water temperature, C;this case the heat emission cofficient was set constanton the whole length of the mold.1| is the guide temperature, C; S is the guide squarein contact with water, M2.800Convective heat emission coefficient a2 was-<>-1determined by technique presented above. Guides 67:-0- 2temperature t; was determined byt| =Q50 ta2where Q。is the average heat flow from steel guides towater, W.Q。=c.m. (t4 -t3|) , where c is the coolingliquid specific heat capacity,一. gr; m is the cooling300liquid consumption， kg/s; 13 is the cooling liquid1000200030004000temperature at the entrance to the mold, C; ts is theDistance from the beginning of the crystallizer(mm)cooling liquid temperature at the exit from the mold ,1 - - Standard guides; 2一New type guides .C.Fig.3 Heat flow density change in steel guides by moldSpecific heat capacity of water is well known andlengthis 4188'kg ●Jat 20 C. Consumption of water in the40HAZELETT9 continuous casting machine guides is,3413.889 kg/s. Experience has shown that, at cooling，28down guides the water temperature at the entrance to22themoldwast3=18.6C，andattheexit-t4=1620.1 C.10Using received data, the distribution of heat flowdensity in the steel guides by mold length can be中国煤化工11001200determined. The calculation results are presented inre(C)Fig.3.YHCNMHGHeat emission coefficients on the metal-moldFig.4 Heat emission coefficient change on the cast bar-steelboundary were determined by temperature functions ofbelts boundary depending on cast bar surfacecast bar surface. Heat exchange process between casttemperaturebar and mold sides could be divided into two main●114●Journal of Harbin Institute of Technology ( New Series)，Vol.21, No.5, 20141200-✧7 mhrin-0- 8mhnrin个9mhnin815.01100-0- 10 m/mnin11 m/min12.5 t100010.0 t.5-9005.08002.59500 600 700 800 900 1000 1100 1200700Temperature(C)Fig.5 Heat emission coefficient change on the cast bar-dam600blocks boundary depending on cast bar surface)71421.28354249566370temperatureDistance from top surface of cast bar(mm)Fig.6 Temperature allocation in the cast bar cross-ectionThe results received were used for calculation inat the exit from the mold at different casting speedsProCast 2010 sofware. As a result temperaturewith standard guidesallocation in the cross-section of the cast bar moving inthe mold at different speeds ( 7，8，9，10 and✧7 mhmin11 m/min) anddifferent-。8mhrindepending on mold construction change were9 m/min-。10mhrincalculated. Temperature allocation in the cast bar at the* 11 m/min .exit from the mold at different casting speeds are shownin Figs. 6 and 7. It is visible that with the growth ofcasting speed at use of both guides type, the cast bartemperature at the exit from crystallizer and the thermalgradient between cast bar centre and its surfaceincreases. It is fixed that at use of the new guides type,the cast bar temperature at the exit from crystallizerdecreases. However in this case, the thermal gradientbetween cast bar centre and its surface increases.To study the mold construction influence on0 20406080 100 120possible maximum casting speed having data receivedDistance from lateral surface of cast bar(mm)in ProCast 2010 sofware profiles of liquid metalcavities depending on casting speed and different castbar cooling conditions in the mold were built which are-0 8 mrinpresented in Figs.8- 13.一9min。10 mmin- *- 11 m/min-o- 7 mhninl-0- 8 m/min心9 mnin-。10 mmin* 11 m/min2 80000个i 800; 4249566370中国煤化工o.。MYHCNMHGFig.7 Temperature allocation in the cast bar cross-ection20100120with new type guides.115●Journal of Harbin Institute of Technology ( New Series)，Vol.21, No.5, 201450010001500. 200020002500营3000吾300003000035004000,0→745004500.r.mm120070Width of the cast bar(mm)Thickness of the cast bar(mm)Fig.8 Form of liquid metal cavity in the HAZELETT国continuous casting machine at 9 m/ min casting speed0T500个1500-百2000告30008 300030004000.,(4000....W idth of the cast bar(mm)Fig.9 Form of liquid metal cavity in the HAZELETT国continuous casting machine with new type guides at 9 m/ min castingspeed, 2000中国煤化工W idth of the cast bar(nMYHCNMHGFig.10 Form of liquid metal cavity in the HAZELETT continuous casting machine at 10 m/ min casting speedJournal of Harbin Institute of Technology ( New Series)，Vol.21, No.5, 20140500500 4500 t10001500200025002500.300035003500.4000.70400045004500.120Width of the cast bar(mm)Thickness of the cast bar(mm)Fig.11 Form of liquid metal cavity in the HAZELETT国continuous casting machine with new type guides at 10 m/ mincasting speed500-500 :1500-，2000E 20002500-国2500-3000./o-704500 I4500..4500mL..Fig.12 Form of liquid metal cavity in the HAZELETT国continuous casting machine at 11 m/ min casting speed1000-冒2000美2500A 30004000-7 704004500rrm中国煤化工W idth of the cast barYHCNMH Guar/mFig.13 Form of liquid metal cavity in the HAZELETT& continuous casting machine with new type guides at 11 m/ min.117●Journal of Harbin Institute of Technology ( New Series)，Vol.21, No.5, 2014Analysis of received liquid metal cavity profilesdecrease of the length of molten metal cavity.showed that a newmold construction allowsConsequently，the molten metal cavity is situatedsignificantly decrease of the length of the liquid metalwithin the mold at 11 m/ min casting speed , which willcavity duringcontinuouscoppercasting alallow the increase of the productivity of theHAZELETT@ casting machine. So using a new guideHAZELETT⑧continuous casting machine.type at 9 m/ min casting speed allows the decrease ofThe results of theoretical calculationallowthe length of the liquid metal cavity from 3519 mm torecommending for industrial to use new guides type3291 mm, at 10 m/min casting speed - from 3910within the following continuous casting mode of castmm to 3657 mm, at casting speed 11 m/min - frombars with cross-section 120 mmX 70 mm from copper4498 mm to 3998 mm. .grade M0O in accordance with GOST 859- 2001 ( UNSFor the verification of simulation results adequacyC11000 ( electrolytic tough pitch copper ( ETP)) forexperiment on temperature pattern detection along castcopper rod production: casting temperature 1120 C,bar cross-section during of foundry machine starting up11 m/ min casting speed, cooling water temperaturefor the speed of 7 m/min has been made. The depth ofdifference at the entrance and exit from the caster fromthe liquid metal cavity defined on cooling temperaturesteel belts side - 20 C，water temperature at thecurves has been equal to 2750 mmDuring .entrance to the casting machine -20 C，cooling watermathematical simulation of cast bar by size 120x70 mmtemperature difference at the entrance and exit from thesolidification process in the conditions of continuouscaster from dam blocks side - 1.5 C，watercasting in the belt water-cooled crystallizer at the sametemperature at the entrance to the casting machinetechnological parameters of casting, it is fixed that the-19 9C.depth of the liquid metal cavity is equal to 2970 mm.ReferencesThe difference in depth of liquid metal cavities sizesmetal is equal to 8%. This difference is associated with[1] Mortier R E. Continuous casting and rlling of copper rodassumptions which are accepted at mathematicalby the Contirod ⑧System. Nonferrous Wire Handbook.Volume 3: Principles and Practice. Guilford, USA: Thesimulation of copper solidification process and testifiesWire Association Intermational, 1995. 183- 192.to adequacy of simulation results.[2] Samarsky A A，Mikhailov A P. Mathematical Simulation:Ideas, Methods, Samples. Moscow: Science, 1997. 320.3 Conclusions[3] Shvydky V S, Ladygichev M G, Shavrin V S. MathematicalMethods of Thermal Physics: Textbook for Universities.Thereby using standard guides and at castingMoscow: Machine Building, 2001. 232temperature 1120 C，the liquid metal cavity is[4] Shvydky V S，Spirin N A，Ladygichev M G, et al.situated within the mold at 9 and 10 m/ min castingElements of Systems Theory and Numerical SimulationMethods of Heat and Mass Transfer Process: Textbook forspeeds，and at 11 m/ min casting speed the liquidUniversites. Moscow: Intermet Engineering, 1999. 520.metal cavity goes out from the limits of the mold on 498[5] Telegin A s, Shvydkiy V s, Yaroshenko Y G. Heat-and-nm. This fact explains the occurrence of molten metalMass Transfer. IKC Akademkniga. 2002. 455.breakthroughs during the efforts to increase the casting[6] Isaev S I, Koglikov I A, Kodakov V I, et al. Theory ofspeed till 11 m/ min at unchanged mold construction.Heat-Mass Exchange: Textbook for Technical Univrsities.The change of the cast bar cooling conditions dueMoscow: Publisher of MSTU, 1997. 683.to the changing mold construction allows significantly中国煤化工MHCNMHG