汽车B柱热成形模具型腔式冷却系统设计和仿真

硕士学位论文汽车B柱热成形模具型腔式冷却系统设计和仿真THEDESIGNANDSIMULATIONGOFCAVITYPATTERNCOOLINGSYSTEMOFHOTSTAMPINGMOLDINBPILLAR陈功哈尔滨工业大学2012年7月国内图书分类号：TG305学校代码：10213国际图书分类号：621.7密级：公开工程硕士学位论文汽车B柱热成形模具型腔式冷却系统设计和仿真硕士研究生：陈功导师：邢忠文教授申请学位：工程硕士学科：机械制造及其自动化所在单位：机电工程学院答辩日期：2012年7月授予学位单位：哈尔滨工业大学ClassifiedIndex:TG305U.D.C:621.7DissertationfortheMasterDegreeinEngineeringTHEDESIGNANDSIMULATIONGOFCAVITYPATTERNCOOLINGSYSTEMOFHOTSTAMPINGMOLDINBPILLARCandidate：ChenGongSupervisor：Prof.XingZhongwenAcademicDegreeAppliedfor：MasterofEngineeringSpeciality：MechatronicsEngineeringAffiliation：SchoolofMechatronicsEngineeringDateofDefence：July,2012Degree-Conferring-Institution：HarbinInstituteofTechnology哈尔滨工业大学工程硕士学位论文-I-摘要减轻车重一直是汽车节能减排的重要手段，高强度钢板可以在保证车身强度的情况下，极大的减轻汽车零件的重量。热冲压技术是加热钢板到奥氏体化温度后成形并同时冷却淬火获得高强度钢板的方法。冷却系统作为热成形技术的关键部分，决定着热冲压件的质量。型腔式冷却系统是在模具中加工出冷却水槽的方法对板料实施冷却，有良好的冷却效果和冷却均匀性。汽车B柱作为汽车车身防止侧向撞击、支撑车顶与车底板的重要结构一直是热成形重点研究的部件。结合传热学和计算流体力学的的基本原理设计了汽车B柱的型腔式冷却系统的模具，提出了支撑柱式、纵向沟槽式、纵横沟槽式冷却结构，并针对不同的冷却系统的冷却水流动情况、强度、加工性等进行了比较。利用CFX软件对不同冷却系统进行了冷却效果的仿真，优化模具的结构参数，并对其冷却速率、冷却均匀性、模具强度和加工性进行了对比，选择纵向沟槽式为合理方案。仿真分析了影响板料冷却效果的因素以及规律，得出了保压力20MPa、冷却水速度3m/s为合理的工艺参数。以BR1500HS为材料，通过试验，研究了保压力、水流速对成形件冷却效果的影响规律，验证数值模拟的正确性。关键词：热成形；B柱；型腔式冷却系统；数值模拟哈尔滨工业大学工程硕士学位论文-II-AbstractWeightreductionhasbeenanimportantwayofautoenergysaving,highstrengthsteelcangreatlyreducetheweightofthemotorvehiclepartsintheconditionofensuringthebodystrength.Hotstampingtechnologyisanimportantmethodofprocessingofhighstrengthsteelsheetwhichmaketheblankformedandquenchedafteritsaustenitizingitsstampingmakinguseofthecoolingsystemtoproducemartensiteinordertoimprovethestrengthoftheblank.Thecoolingsystemdeterminesthequalityofthehotstampingasakeypartofthehotformingtechnology,domesticandforeignenterprisesanduniversityhavedonealotofresearchonit.ManyresearchhavefocusedonB-pillarwhichworktopreventlateralimpactandsupportthecarroofandthefloor.ThreecoolingstructureofthecoolingsystemofB-pillar“supportingpillarstyle,verticaltrenchstyleandverticalandhorizontaltrenchstyle”andotherworkingpartsandrelatedparametersaredesignedwiththehelpofthebasicknowledgeofheattransfer.Establish3DmodelusingCATIAsoftwaretodesignamodelofthemold,andcheckthestrengthofthemold.Heatconductionaswellascomputationalfluiddynamicsinvolvedintheprocessofcoolingsystemisintroducedanditlaysatheoreticalfoundationforthesimulation.ImportCATIAmodelintoCFXsoftware,settherelevantparameters,simulatethecoolingeffectofthe“supportingpillarandverticaltrenchstyle”tooptimizethestructuralparametersofthemold.Comparethecoolingrate,thecoolinguniformity,moldstrengthandeaseofprocessingofthethreestructurestoselectthefinaloptimizedstructure.Thesimulationresultsrevealthefactorsandlawsofthecoolingeffectofthesheet.DoexperimentusingthesimplifiedmodelandBR1500HStostudytherelationshipbetweenpressure,presstime,flowvelocityandthecoolingeffectofthesheettoverifythevalidityofthenumericalsimulation.Keywords:hotforming,Bpillar,“cavitypattern”coolingsystem,numericalsimulation哈尔滨工业大学工程硕士学位论文-III-目录摘要..........................................................................................................................IABSTRACT................................................................................................................II第1章绪论..............................................................................................................11.1引言..................................................................................................................11.2热冲压成形技术...............................................................................................21.2.1热冲压成形术的原理和分类......................................................................21.2.2热成形的组织转变......................................................................................31.2.3热成形技术的市场价值..............................................................................31.3热冲压技术国内外研究现状............................................................................31.4冷却技术的研究现状.......................................................................................41.5本课题主要研究的内容....................................................................................6第2章型腔式模具冷却系统的共轭传热的理论分析..............................................82.1引言..................................................................................................................82.2热传导原理.......................................................................................................82.2.1热传导实质.................................................................................................82.2.2热传导模型的分类......................................................................................82.2.3导热问题的求解.........................................................................................92.3热成形中热对流分析.......................................................................................92.4热成形中的热辐射现象..................................................................................112.5湍流模型..........................................................................