简介:ProblemsaboutsurfacemountingprocessforfinepitchdevicesandreasonsonsolderbridgingofLtypeleaddevicesweldedaredepicted.Bridgingmechanismandinfluencefactorsareanalyzedwithtwo-dimensionalgeometricmodel.Basedonthis,high-densitysurfacemounttechnology(SMT)forfinepitchLtypeleaddevicesheatedbyscan-ninglaserisraised.SurfacemountprocessforQFP208onprintedcircuitboard(PCB)isstudied.Theresultsoftestsarethatitisquitepossibletosolvethesolderbridgingofsurfacemountingforpitchdeviceswithscanninglaser-heat-ingmethod.
简介:ThemicrostructuralevolutionandVickershardnessmeasurementintheweldingheat-affectedzone(HAZ)ofHD15Ni1MnMoNbCusteelfornuclearpowerstationwereinvestigatedbyGleeble-3180thermalmechanicalsimulator,andthesimulatedHAZcontinuouscoolingtransformationcurves(SH-CCT)weremeasuredsimultaneously.Witht_(8/5)increasingfrom3.75sto15000s,theproductwasobtainedmartensite,bainite,ferriteandpearlite,successively.TheresultofmicrostructureandVickershardnessintheheat-affectedzonewasingoodagreementwiththosemeasuredbySH-CCTdiagramwiththeheatinput16.2kJ/cmasanexampletoweldtheHD15Ni1MnMoNbCusteelpipeusingTIG/SMAW/SAWweldingmethods.
简介:Intheacceleratordrivensub-criticalsystem(ADS)cooledbyliquidPbBialloy,theausteniticstainlesssteel316Lisoneofthecandidatesofstructuralmaterials.However,thecorrosionandwearbehaviorof316Lsteelinthehigh-velocitystreamofliquidPbBiisthemostessentialissue,whichisurgenttobepaidcloseattention.Inordertoacquirethemorphologyandmechanicalpropertiesof316Lsteelintheconditionsofdifferentrelativeflowingvelocity(RFV),respectively2.62m/s,3.69m/s,4.77m/s,theexperimentwascarriedoutindynamicliquidPbBiat550℃,uptoabout1500h.Accordingtotheresults,thesurfaceof316LhasbeencorrodedbadlyandtheelementsofNi,Cr,etc.werefoundtodissolvealot.WiththeincreaseoftheRFV,thefeatureof316Lsurfacechangedfromthesurfacewithmuchdeeperpitsandlooserstructurestotherelativeplanarone,andthethicknessoftheouteroxidelayerdecreasedgraduallywhilethatoftheinneroxidelayerdiminishedalittle,andthemicrohardnessoftheoutermostsubstratealsodeclinedincreasingly,inaddition,thedomainofthepartialsubstratewithitsmicrohardnessbeingaltereddeepenedfurther.Theseexperimentaldatawouldoffertheoreticalbasisandpracticalvaluestostudycorrosionconditionof316LsteelinliquidPbBiwithhigh-velocity.
简介:本文利用嵌入式系统技术和图像检测技术设计了一种应用于工业自动化焊缝检测器的新方案。与基于PC机和图像检测技术相结合的模式相比,该焊缝检测器具有功耗低、稳定性好、专用性强和体积小等优点。系统硬件采用DSP+ARM双核处理器架构,选用专用数字图像处理器TMS320DM6437作为图像算法处理的核心,S3C2440工业级ARM9内核芯片作为系统的主控制单元。操作系统平台采用源代码开放的Linux作为嵌入式操作系统;焊缝检测图像处理算法采用滤波处理、阈值分割和小面积删除法作为图像的预处理,采用边缘检测与边界坐标扫描法获得焊缝的中心线,进而用领域坐标扫描法准确地获取焊缝中心点,较好地完成焊缝的检测。