激光焊接原理及实践应用.ppt

激光焊接LasersWelding,GirishP.Kelkar,Ph.D.,激光LASER,受激辐射式光频放大器的英文第一个字母的缩写LightAmplificationbyStimulationofEmittedRadiation,参考资料References,激光的工业应用-J.F.ReadyIndustrialApplicationsofLasers,J.F.Ready激光焊接，W.W.DuleyLaserWelding,W.W.Duley激光加工，W.M.SteenLaserMaterialsProcessing,W.M.SteenAWS焊接手册，1-4AWSWeldingHandbooks,1-4激光加工手册-美国激光协会出版HandbookofLaserMaterialsProcessingPublishedbytheLaserInstituteofAmerica公开的相关文献Publishedliterature,请记住.Remember.,学习需要积极的参与Learningrequiresactiveparticipation不耻下问Feelfreetoaskquestions无所顾及地提出个人不同见解Donothesitatetopresentdifferentviewpoints,光Light,光是一种电磁辐射Lightiselectro-magneticradiation我们听不到.Wavesthatyoucannothear可见光的波长在0.4-0.7微米之间。Visiblefrom0.4-0.7micronwavelength波长小于0.4微米是紫外线和X光Below0.4ultraviolettox-rays波长大于700nm的光为红外线和微波。Above0.7infra-redtomicrowaves,1m,光的吸收和颜色AbsorptionandColor,物体的颜色来源于它反射的光的波长Colorofanobject(wavelengththatitreflects),颜色和光的波长是相关联的。Colorisassociatedwithparticularwavelength黑色和白色代表着什么？Whatisthemeaningofblackorwhitecolor?黑色表面吸收了YAG光，而白色在反射了大部分光。BlacksurfacewillabsorbYAGlightwhilewhitewillreflectmostofit,我们为什么需要激光？WhydoweneedLasers?,材料加工需要吸收很强的光。Absorptionformaterialsprocessingrequiresveryintenselight高强度的光可以通过激光聚焦成光束获得。Intensitycanbegeneratedbyfocusingabeamoflaserlight普通光不能聚焦成很高的能量密度（或足够小的点）Ordinarylightdoesnotfocusdowntoahighenoughpowerdensity(orsmallenoughspotsize)手持放大镜可以把太阳光聚焦让纸燃烧但是不能把金属融化Hand-heldlenscanfocussunlighttosetfiretopaperbutnotenoughtomeltmetal,LightandLasers,单频的（单波长）Monochromatic(singlewavelength)校准的（平行光）Collimated(parallel),激光LaserLight普通光OrdinaryLight,很多波长Manywavelengths不平行Notparallel,LightandLasers,激光LaserLight普通光OrdinaryLight,激光的聚焦FocusingofLasers,激光LaserLight普通光OrdinaryLight,单频（单波长）和校准（平行）的光可以聚焦成很小的焦点Monochromatic(singlewavelength)andCollimated(parallel)lightcanbefocusedtoaverysmallspot,激光的种类TypesofLasers,激光能量传输LaserPowerDelivery连续波ContinuousWave(CW)脉冲PulsedQ-开关Q-switched激光频率LaserFrequencies基频和倍频Fundamentalandmultiples,连续光纤激光ContinuousWaveFiberLasers,激光在光纤中产生Laserlightiscreatedinthefiber可在连续波和脉冲波中使用CanbeusedinpulsedmodeaswellasCW可以被用于焊接和切割Canbeusedforweldingandcutting,激光二极管光LaserDiodeLight,激光二极管光LaserDiodeLight,光纤Fiber,脉冲YAG激光（焊接）PulsedYAGLasers(Welding),闪光灯开关产生脉冲Flashlampturnsonandofftocreatepulses光纤用于传送激光Fiberisusedtotransmitlaserlight,闪光灯（光泵）FlashLamp(OpticalPump),全反镜100%mirror,90%反镜90%mirror,光纤Fiber,激光棒LaserRod,脉冲打标激光PulsedMarkingLasers,Q-switchingproducesveryshortpulses,10-100nano-secCannotbeusedforweldingLaserlightdelivereddirectly;nofiberFrequencycanbedoubledortripledtogetgreenorUVlight,Rod,Mirrors,Q-switch,GalvoMirrors,FocusLens,FrequencyMultiplier(notpresentinallmarkers),Galvo-光学器件Galvo-Optics,经常用于打标。Oftenusedformarkingapplications逐渐受到焊接应用的青睐。Isgainingpopularityforweldingapplications,Nutfield,Inc.,激光频率LaserFrequencies,上表只包括了大部分常用的和商业化的激光器。Tableincludesonlythemostcommonandcommercializedlasers。,脉冲YAG激光焊接典型示意图TypicalLayoutforPulsedYAGWeldingLasers,镀膜反光镜CoatedMirrors,激光Laser,光纤OpticalFiber,聚光头FocusHead,工件Workpiece,透镜Lens,注：某些激光不通过光纤直接传输。Note:Somelasersaredelivereddirectwithoutfiber,聚焦高度和焦点尺寸Focusheightandspotsize,短焦距透镜将光束聚焦成更小的点。Shortfocallengthlens(ofgivendiameter)willfocusthebeamtoasmallerspot高的能量密度。HigherenergydensityFocusheightiscriticalduetoshallowdepthoffocusLensprotectionfromworkpiecespatterisimportant,短焦距ShortFocalLength长焦距LongFocalLength,TimeShare,Asinglelasercanbeusedformultipleapplicationsonatimesharedbasis基于同一个理论,单雷射可以一次性用于多种应用.Mostconvenientwithtransmissionthroughopticalfiber通过可见纤维的转换是最方便的.Processingstationscanbeindifferentrooms工作台可以放在不同的房间.,Mirrors(100%Reflective)全反镜,EnergyShare,Laserenergysplitintomultiplefragments雷射能量分成多个部分Typicallythreeoutputsforcircumferentialspotwelding典型的是圆周点焊接的3份输出量,Mirrors(PartiallyReflective)反光镜(部分反光),33%50%100%,30W,10W10W10W,TotalInternalReflection完全内反射,Lightpropagationthroughfibersdependsontotalinternalreflection通过光纤的光线传播完全取决于完全内反射,Air空气,Glass玻璃,Core核,Cladding覆层,ProtectiveSheath接地屏蔽,OpticalFibers光学纤维,Singlemodehasverysmallcorediameter,10microns单模式只有很小的直径10微米Usedfortelecommunicationsandnowforfiberlasers用于电讯,现用于光纤激光SIandGIhavecoresfrom0.1mmto1mm单模式和分级模式的核从0.1mm到1mmHigherdiameterforhigherpowerlevel能量级别越高直径越大,SteppedIndex(SI)步长指数,SingleMode单模式,GradedIndex(GI)分级模式,IndexProfiles剖面指数,SIvs.GI单模式vs分级模式,SIandGImostfrequentlyusedinmaterialsprocessing单模式和分级模式多用于材料加工过程.SIoutputis“top-hat”independentofinput单模式的输出独立于输入呈大礼帽状morerobust更有活力GIoutputmorefaithfulrepresentationofinput分级模式的输出与输入呈保持靠近,Cancreateproblemsifinputbeamqualitychanges如果输入光束的质量改变可能会产生问题.Canmakedeeperwelds/cuts可能焊接/切的更深.Weldprofilescouldchangebasedonfocusheight焦点高度可能产生焊接侧面的变化,SIGI,0.6AspectRatio纵横比1.5,“TopHat大礼帽状”,WeldProfiles焊接剖面,FiberInputAlignment光纤输入排列,GoodAlignment好的排列,Couldburnfiberinputend可能烧焦光线输入莫端,Couldcreateplasmaatfocus在焦点产生等离子体,Couldburncladding可能烧伤覆层,SpotSizewithFiber光点直径带光纤,Spotsizeisanimageoftheoutputcorediameterofthefiber从光点的大小可以反应出光纤核直径的大小Sizedependsonmagnificationofthetwolensesinthefocushead其大小是由镜头前的两个透镜来决定的.,OpticalFiber光纤,CoreDiameter核直径,SpotSize光点直径,LaserSafety,CommonSense常识Doyounotputyourhandindirectpathofalaserbeam不要把手的头放在雷射光束的路径中.Donotlookdirectlyatalaserbeam不要直视雷射光束evenatthoselaserpointersbeams!不要看雷射点.Donotlookatanylaserprocesswithanakedeye不要用不防护的肉眼看任何的激光过程.useplasticsafetyglassesforCO2lasers用塑料防护眼镜来防护CO2雷射.useYAGsafeglassesforYAGoperations在钇铝石榴石操作中用钇铝石榴石安全眼镜,EyeDamage,NearUVfromweldingplasmaandUVlasersIfyouseebluishwhiteduringmaterialprocessing,youneedUVprotection;ordinaryplasticsafetyglassesarenotsufficient!如果你在材料加工的过程中看见蓝白的光,你需要UV保护,一般的塑料防护眼镜是不起作用的.VisibleandNearIRfromYAGandfrequencydoubledlasers,Cornea角膜,Lens透镜子,Retina视网膜,FarUVandFarIRNearUV接近UVVisibleandNearIR,CollateralDamage,Fumes烟Solvents,grease,etc.fromtheworkpiece溶剂,油脂等,Metaldustcouldbetoxic金属颗粒可能有毒.Decompositionproductsofplasticsprocessing(marking,welding,ordrilling)couldalsobetoxic在朔料加工的规程中的分解产品,(打表,焊接,或者钻孔)也是有毒的.Installvacuumpumpsandappropriatefilters安装真空泵和合适的过滤器.NeedspecialTidustcollectorswhenweldingTiinagloveboxformedicaldeviceapplications当在用于医疗器械的手套盒子中焊接钛的时候,需要特殊的吸钛器.,FireHazard火灾,LaserBeamscanhavebeenknowntocausefires镭射激光能够引起火灾.Breaksinopticalfiber光纤削弱Makesureopticalfiberisnotwoundtootightly确保光学纤维不会太击伤.LeakageinCO2directopticsLaserbeamwalkingoffworktableontoplasticcoversLaserbeaminteractionwithglovesinaglovebox,Laser-MaterialInteraction,Forlensandwindows,AandRhavetobesmall对于透镜和窗户,A和R应该是小的.Formirrors,Rhastohigh对于镜子,R应该高一些ForLaser-basedmaterialsprocessing,AhastobehighandRshouldbelow对于以雷射原理为基础的材料加工,A要高一些,R应该要低一些.,IncidentEnergy入射能,Reflection反射,Absorption吸收,Transmission转播,I=A+R+T,InitialReflectivityofMetals金属的初始反射率,Greymetals(AgandAl)arereflectivetoallcolorsinvisiblespectrum灰色金属(AgandAl)对所有的有色光谱中的颜色都有反射作用.Copperreflectsnearredwavelengthsandabsorbsothers铜在红色波长附近反射,在其他中吸收.,0.0,0.2,0.4,0.6,0.8,1.0,0.2,0.4,0.7,1.0,10,Wavelength(mm),Reflectivity,Ag,CarbonSteel碳钢,Ni,Cu,Al,Nd:YAG,CO2,Source:IndustrialLaserApplications-JohnReady,LaserAngle雷射角落,Forallweldingapplications,thelasershouldbeangledoffverticaltopreventlaserenergyfromgoingbackintothelasercavityandcausingdamage对于所有的焊接应用,雷射应该与角落垂直以防雷射能量回到激光腔,引起损失.,5degrees,AbsorptivityofMaterials材料的吸收率,Reflectivityisalsoaffectedbysurfaceroughness,surfaceoxides,partgeometry,andweldpoolshape反射率也是由表面光滑度,表面氧化度,;零件几何,以及焊接池的形状.,LaserWelding镭射焊接,Configurations结构,Gapdimensionsbecomemorecriticalaspartsgetsmaller由于零件尺寸变小,缝隙的尺寸变得更重要,ButtWeld对接焊接Gap0.1t,t,Cap盖子,Can罐子,t,Configurations,Gapdimensionsbecomemorecriticalaspartsgetsmaller由于零件尺寸变小,缝隙的尺寸变得更重要Canweldmultiplelayers罐子多层焊接,LapWeldGap0.15t,Configurations,Preferconfigurationswherethemoltenmaterialflowsintotheweldinsteadofpullingawayfromit最好的形状是融化的物质是流入到焊接而不是脱离焊接.,LapWeld,LapFillet,LapEdge,AnnularWelds,Fitupisimportant移动的台面很重要.Ifgapispresent,stresseswilldeveloptowardstheendoftheweld如果有缝隙,应力会随着焊接而增大Press-fitpreferred最好有压配合.,SmallVolumeWelds,Air/gasintheenclosedvolumeduringfinalweldheatsupandtriestoescape空气在有限的空间里会随着焊接的热量膨胀,并试图逸出.Cancauseporositytowardstheendoftheweld可能会在焊接的最后引起多孔.,AirPressureIncreasesDuringWelding在焊接饿过程中空气的压力增加,PressureRelief卸压,Allowpressurereliefonenclosedvolumes如下情况需要泄压Reducecrack-likefeatureswhichmaybecausedbyhighpressuretrappedinside泄压可以减少像这种由于内部压力过大而引起的类似裂纹的缺陷.,ShieldGas,Mainfunctionofshieldinggasistoprotectthemoltenmetalfromreactingwithoxygen保护气体的保护作用主要是保护融化的金属不与氧气反应.Shieldinggasalsohelpsto:保护气体也有助于Protectlens/lenscoverfromweldsplatter保护透镜,透镜盖不受焊接泼溅Controlplasmacloudformation控制等离子雾形成.Washawaymetalvaporsintheplume吹散等离子体中的金属蒸汽.,ShieldGas,Whatisplasma?什么是等离子体Plasmaisionizedgas等离子是离子化气体Electronsareseparatedfromatoms(metalaswellasshieldinggas)电子与原子分离(金属和屏蔽气体)Plasmaisthefourthstateofmatter;otherthreearesolid,liquid,andgas(等离子体是事物的第四种状态,其他的三种是固体,液体和气体)Whatisplume?什么是等离子体?Plumeisamixtureofplasmaandmetalvapors等离子体是等离子以及金属气体的混合体.,Plume,ShieldGasesforYAGLasers,Heliumisidealbutveryexpensive氦很理想,但是很昂贵Argongasismostcommonlyused氩气是最常用的Nitrogencanbeusedforsomealloys氮可以用于一些合金.Someweldsaremadeinair(noshieldinggas)buttheweldsurfaceisnotverysmooth有些焊接在空气中做(没有保护气体)但是焊接表面不是太顺滑Maystillproduceacceptableweldquality可能仍旧能够产生有效的焊接质量.,Soot,Sootisblackcoloreddust,typicallyreferredtoas“soot”thoughitisnotcomposedofcarbon烟是黑色的灰尘,虽然叫煤烟但它不是由碳组成的.“Soot”isafinedustofmetalpowderthatisdepositedfromtheplume煤烟是一种从等离子中沉淀下来的金属粉末.,Chemicalanalysisof“soot”fromInconel600,ShieldGasConfiguration,Coaxial共轴Toohighdestabilizestheweldpool,increasedporosity太高-动摇焊接溶池,引起多孔.Toolowcancausenegativepressureandpulluptheweldmetal太低-会引起负压力,使融化的金属突起.Betterforshielding最好屏蔽SideFlow侧流Usefulforsweepingawaytheionizationproducts用于清理等离子体.,PulsedYAG脉冲钇铝石榴石,ImportantParameters重要的参数Pulse脉冲Width宽度Energy能量Power能量Shape形状PulseOverlap脉冲交迭SpotSizeandFocus光点和焦点,PulsedYAG脉冲钇铝石榴石,Energy(J)能量=Power(kW)力xWidth宽度(msec)Initialenergypeakhelpsthelaserenergytocouplewiththematerial初始的高能量可以使激光能量与金属耦合.,ProgrammedPulse程序脉冲,PeakPower,PulseEnergy脉冲能量,PulseWidth脉冲宽度,ActualOutput实际输出,PulsedYAG脉冲钇铝石榴石,Shortpulseofhighpeakpowercancauseexpulsion高的峰值能量的短脉冲能引起坑.Longpulseoflowpeakpowerwillproduceawiderandshallowerweldbead低顶点能量的长脉冲会产生更宽和更浅的焊缝.,Power,PulseWidth,DeeperPenetration更深穿透GreaterPorosity更多多孔MoreExpulsion/Spatter更多飞溅,ShallowerPenetration更浅穿透LessPorosity更少多孔Cleanerweldswithnoporosity更干净焊接没有飞溅,Effectofpulsetimeonweldsize脉冲时间对焊接尺寸的影响,Weldspotdiameterincreasesrapidlyinthefirstfewmilli-seconds;rateofgrowthreduceswithtime焊斑直径在最初的千分之一秒期间迅速变大,增长的速度随着时间的增长而降低.,Time,WeldSize,Effectofpulsetimeonpenetration脉冲时间对焊接尺寸的影响,Foragivenpeakpower,weldpenetrationstabilizesafteracertainthresholdweldtime对于指定的能量高峰,焊接深度在一定的焊接时间后变得稳定.Maximumpenetrationisdirectlyproportionaltopeakpower最大的深度是与能量高峰成直接正比的关系.Aboveacertainthresholdofpower,thelaserwillendupdrilling/cutting/gouginginsteadofwelding在一定能量的之上,雷射将钻孔,切断,咆削而不是焊接.,Time,Penetration,PeakPower1,PeakPower2,PulseShaping脉冲形状,Singlepulseorthreesectorpulseofferedbycapacitorbasedpowersupplies由电源电容器产生的单脉冲和三个脉冲Newermachinesofferinvertertechnologywithcontinuouspulseshaping更新的提出的能够提供无间断的脉冲形状.,Time(msec),PeakPower,Energy(J)能量=Power(kW)力xTime时间(msec),Single单个Three-sector三部分Multi-sector多部分,WeldCracking焊接破裂,Canisanchoredinthecapwhilecansurfacehasleverage罐子被锚在夹具中,而罐子的表面有杠杆作用.Weldcoolingalwaysintroducesresidualstresses焊接冷却往往引起残余压力.Combinationoflargeweldvolumeandrapidcoolingcanintroduceexcessiveresidualstressesthatcausecracking大量焊接加之迅速冷却能产生过量的残余压力从而引起破裂.,LaserFeatures:PulseShape雷射特征:脉冲形状,MeltingandPenetrationPulse溶解渗透脉冲(CouplingPulse偶合脉冲),StabilizationPulse稳定脉冲(controlledcoolingtoreduceexpulsionandresidualstresses控制冷却减少残余应力.),6.0kW,0.50.51.02.0m-sec,50%,30%,0.2,PulseShaping脉冲形状,Modifiedpulsegavetimefortheweldtocoolslowlyandallowtheporetoriseabovetheweldinterface改良脉冲使焊接冷却的时间变慢,而且使得气孔有时间从熔融的金属中上升到表面,FocusHeight焦点高度,Atfocus,spotsizenotsensitivetofocusheight在焦点,点大小与焦点高度不相互影响.Atfocus,plumeistallestandsoundishighestpitch在焦点,等离子体是最高的,而且声音也是最高调的.usedtofindfocusheight用于找出焦点高度.Focususuallysetatthesurfaceforpulsedwelding焦点通常设在表面为脉冲焊接.Focussetbelowsurfacefordeeperpenetrationandkeyholemodewelding焦点射在表面以下为更深的穿透和缩定焊接,PulseOverlap脉冲交叠,Dependsonthicknessofcomponentontopandshapeofweldbead取决于零件上端的厚度和焊缝的形状.Overlapshouldbegreaterbyasafemargin在一定安全范围之内,交叠会大一些.Note:Excessiveoverlapisexcessunwantedheatintotheweld注意:过量的交叠是过度的热量在焊接中出现.,Non-hermeticOverlap不密封交叠,HermeticOverlap密封交叠,PulseOverlap脉冲重叠,Lapweldsrequirehigheroverlap重叠焊接要求更高的重叠Buttweldscanbehermeticevenat50%overlap对接焊接可以被密封,即便是50%的重叠,ButtWeld对接焊接,LapWeld重叠焊接,ButtWeld对接焊接,LaserWeldQuality雷射焊接质量,WeldSurfaceInspection焊接表面检测Weldsurfaceshouldbecleanandfreeofspatter焊接表面需干净,没有滴溅Novisiblecracksorholes没有可见的裂缝和孔.,Good,NotGood,LaserWeldQuality雷射焊接质量,MechanicalTesting机械测试BurstStrength爆发力量PulltestorShearTest拉力测试和剪切测试LeakTest测漏测试StrengthAnalysis;力量分析Itisveryimportanttokeeptrackofwhereandwhenthefailuresoccurredduringtesting在测试中,记录在那里和什么时候失败是十分重要的Marklocationsoffailureforfurtheranalysis在失败的地方做标识是以便将来进一步分析,WeldSectionAnalysis焊接部分分析,CrackedWeld焊接破裂,SmallPressureBubble?小压力泡沫,GoodWeld好焊接,X-rayAnalysisX-RAY分析,Cracksgrowatanangleandappearasstraightlinesinthex-ray(shallowweldonright)破裂在一个角中扩大,在X-RAY中显示为一条直线Smallporositiesmaybedifficulttoseeinsuchimages在这样的图片中很难看到小孔.Checkforalignment查看齐边.,WeldCrack焊接破裂,ShallowWeld焊接阴影,Alignment,X-rayimagesofgoodweldsX-RAY中好的焊接,LaserMaintenance雷射维护,Feedbackmonitoronlycheckslasercavityperformancedoesnotcheckpoweratweld反馈器只查看激光腔的性能-不会查看焊接时候的能量,LaserCavity激光腔,FocusHead焦点头,EnergyMeter,BurnMarks,Plexiglas,etc.能量剂,火刺,树脂玻璃,Lens透镜,FeedbackMonitor监视器反馈,EnergyMeters能量计,JouleMeters焦耳Setforsinglepulseoraverageovermultiplepulses定为单脉冲或者平均大于多脉冲Shouldbeusedperiodicallytoconfirmenergyattheweld在焊接的时候周期性的确认能量Automationsystemcanbesetformeasurementatwarmupandaftersetnumberofpulsewelds在启动的时候或者确定脉冲焊接的时候用自动化系统.来确定量度.,Spotsizeandshape黑点的大小和形状,Burnpaperandburnplates烧纸Firelaserspotsatlowenergyandobserveburnmarkpatternforsymmetryanduniformity用低能量去烧雷射黑点观察出来的标记是均匀对称的.Ifspotisnotroundinshape,beamisbeingcut/clipped如果黑点不是圆形的,光束就正被切断.Makingspotsonactualmaterialatlowenergyandobservespotsunderamicroscope在具体的材料上用低能量下做黑点,并且在显微镜下观察.Canbeusedforsettingspotsizeandfocus用来设定黑点的大小和焦距.,Fiber,Lens,andLensCover光纤,透镜和透镜盖,Makesuretofollowalignmentinstructionsprovidedbymanufacturer确保能够按照厂商提供的对齐要求来操作.Periodicallyinspectfocuslensfordamage周期性地检测焦点透镜是否受损Cleanverygentlywithlenscleaningcloth/paperonly只用干净的擦镜布轻轻的擦透镜Alllenseshavespecialcoatingthatcannotbeseenandisveryeasilydamaged所有的透镜都有一层看不见的特殊涂层而且比较容易受损.Inspectlenscoveratbeginningofeveryshiftandcleancarefully观测透镜在每一次的切换开始的时候,并且要仔细擦干净.Ifexcessiveweldsplattercheckshieldgasflowrate如果有过多的焊接泼溅检查保护气体的流率,MachineAlignment机齐边器,Laserpathandseammaynotbewellalignedduetomachineoffset雷射路径和焊蜂可能会不齐由于机器骗移Runspotweldpatterntocheckalignment启动焊接模式检查齐边Runoutshouldbelessthan0.1mm偏移应该要低于0.1MM,LaserPath,WeldSeam,Summary总结,Laserlightismonochromaticandparallelmakingitpossibletofocusdowntoverysmallspot雷射光是单频率和平行的使得它能够在很小的黑点上聚焦Laserweldingisanon-contacthigh-powerprocessthatcanproducespotweldsandseamwelds,andcanalsobeusedformarkingandcutting雷射焊接是一种能产生黑点焊接和接缝焊接不可以接触的高能量工序,可以用来打标和切割Importantfactorsincludepulsetime,focus,peakpower,andoverlap(forseamwelds)重要因素包括脉冲时间,顶点能量和交叠(接缝焊接)Laserweldpowershouldbemonitoredwithanenergymeterandweldqualitycanbeinspectedwithmechanicaltesting,x-ray,andcross-sections雷射能量应该用能量计监控.焊接质量可以用一些机械测试来检测X-RAY,