激光焊接原理及實踐應(yīng)用最新版本

.,激光焊接LasersWelding,GirishP.Kelkar,Ph.D.,.,激光LASER,受激輻射式光頻放大器的英文第一個字母的縮寫LightAmplificationbyStimulationofEmittedRadiation,.,參考資料References,激光的工業(yè)應(yīng)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焊接手冊，1-4AWSWeldingHandbooks,1-4激光加工手冊-美國激光協(xié)會出版HandbookofLaserMaterialsProcessingPublishedbytheLaserInstituteofAmerica公開的相關(guān)文獻(xiàn)Publishedliterature,.,請記住.Remember.,學(xué)習(xí)需要積極的參與Learningrequiresactiveparticipation不恥下問Feelfreetoaskquestions無所顧及地提出個人不同見解Donothesitatetopresentdifferentviewpoints,.,光Light,光是一種電磁輻射Lightiselectro-magneticradiation我們聽不到.Wavesthatyoucannothear可見光的波長在0.4-0.7微米之間。Visiblefrom0.4-0.7micronwavelength波長小于0.4微米是紫外線和X光Below0.4ultraviolettox-rays波長大于700nm的光為紅外線和微波。Above0.7infra-redtomicrowaves,1m,.,光的吸收和顏色AbsorptionandColor,物體的顏色來源于它反射的光的波長Colorofanobject(wavelengththatitreflects),顏色和光的波長是相關(guān)聯(lián)的。Colorisassociatedwithparticularwavelength黑色和白色代表著什么？Whatisthemeaningofblackorwhitecolor?黑色表面吸收了YAG光，而白色在反射了大部分光。BlacksurfacewillabsorbYAGlightwhilewhitewillreflectmostofit,.,我們?yōu)槭裁葱枰す猓縒hydoweneedLasers?,材料加工需要吸收很強的光。Absorptionformaterialsprocessingrequiresveryintenselight高強度的光可以通過激光聚焦成光束獲得。Intensitycanbegeneratedbyfocusingabeamoflaserlight普通光不能聚焦成很高的能量密度（或足夠小的點）Ordinarylightdoesnotfocusdowntoahighenoughpowerdensity(orsmallenoughspotsize)手持放大鏡可以把太陽光聚焦讓紙燃燒但是不能把金屬融化Hand-heldlenscanfocussunlighttosetfiretopaperbutnotenoughtomeltmetal,.,LightandLasers,單頻的（單波長）Monochromatic(singlewavelength)校準(zhǔn)的（平行光）Collimated(parallel),激光LaserLight普通光OrdinaryLight,很多波長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,單頻（單波長）和校準(zhǔn)（平行）的光可以聚焦成很小的焦點Monochromatic(singlewavelength)andCollimated(parallel)lightcanbefocusedtoaverysmallspot,.,激光的種類TypesofLasers,激光能量傳輸LaserPowerDelivery連續(xù)波ContinuousWave(CW)脈沖PulsedQ-開關(guān)Q-switched激光頻率LaserFrequencies基頻和倍頻Fundamentalandmultiples,.,連續(xù)光纖激光ContinuousWaveFiberLasers,激光在光纖中產(chǎn)生Laserlightiscreatedinthefiber可在連續(xù)波和脈沖波中使用CanbeusedinpulsedmodeaswellasCW可以被用于焊接和切割Canbeusedforweldingandcutting,激光二極管光LaserDiodeLight,激光二極管光LaserDiodeLight,光纖Fiber,.,脈沖YAG激光（焊接）PulsedYAGLasers(Welding),閃光燈開關(guān)產(chǎn)生脈沖Flashlampturnsonandofftocreatepulses光纖用于傳送激光Fiberisusedtotransmitlaserlight,閃光燈（光泵）FlashLamp(OpticalPump),全反鏡100%mirror,90%反鏡90%mirror,光纖Fiber,激光棒LaserRod,.,脈沖打標(biāo)激光PulsedMarkingLasers,Q-switchingproducesveryshortpulses,10-100nano-secCannotbeusedforweldingLaserlightdelivereddirectly;nofiberFrequencycanbedoubledortripledtogetgreenorUVlight,Rod,Mirrors,Q-switch,GalvoMirrors,FocusLens,FrequencyMultiplier(notpresentinallmarkers),.,Galvo-光學(xué)器件Galvo-Optics,經(jīng)常用于打標(biāo)。Oftenusedformarkingapplications逐漸受到焊接應(yīng)用的青睞。Isgainingpopularityforweldingapplications,Nutfield,Inc.,.,激光頻率LaserFrequencies,上表只包括了大部分常用的和商業(yè)化的激光器。Tableincludesonlythemostcommonandcommercializedlasers。,.,脈沖YAG激光焊接典型示意圖TypicalLayoutforPulsedYAGWeldingLasers,鍍膜反光鏡CoatedMirrors,激光Laser,光纖OpticalFiber,聚光頭FocusHead,工件Workpiece,透鏡Lens,注：某些激光不通過光纖直接傳輸。Note:Somelasersaredelivereddirectwithoutfiber,.,聚焦高度和焦點尺寸Focusheightandspotsize,短焦距透鏡將光束聚焦成更小的點。Shortfocallengthlens(ofgivendiameter)willfocusthebeamtoasmallerspot高的能量密度。HigherenergydensityFocusheightiscriticalduetoshallowdepthoffocusLensprotectionfromworkpiecespatterisimportant,短焦距ShortFocalLength長焦距LongFocalLength,.,TimeShare,Asinglelasercanbeusedformultipleapplicationsonatimesharedbasis基于同一個理論,單雷射可以一次性用于多種應(yīng)用.Mostconvenientwithtransmissionthroughopticalfiber通過可見纖維的轉(zhuǎn)換是最方便的.Processingstationscanbeindifferentrooms工作臺可以放在不同的房間.,Mirrors(100%Reflective)全反鏡,.,EnergyShare,Laserenergysplitintomultiplefragments雷射能量分成多個部分Typicallythreeoutputsforcircumferentialspotwelding典型的是圓周點焊接的3份輸出量,Mirrors(PartiallyReflective)反光鏡(部分反光),33%50%100%,30W,10W10W10W,.,TotalInternalReflection完全內(nèi)反射,Lightpropagationthroughfibersdependsontotalinternalreflection通過光纖的光線傳播完全取決于完全內(nèi)反射,Air空氣,Glass玻璃,Core核,Cladding覆層,ProtectiveSheath接地屏蔽,.,OpticalFibers光學(xué)纖維,Singlemodehasverysmallcorediameter,10microns單模式只有很小的直徑10微米Usedfortelecommunicationsandnowforfiberlasers用于電訊,現(xiàn)用于光纖激光SIandGIhavecoresfrom0.1mmto1mm單模式和分級模式的核從0.1mm到1mmHigherdiameterforhigherpowerlevel能量級別越高直徑越大,SteppedIndex(SI)步長指數(shù),SingleMode單模式,GradedIndex(GI)分級模式,IndexProfiles剖面指數(shù),.,SIvs.GI單模式vs分級模式,SIandGImostfrequentlyusedinmaterialsprocessing單模式和分級模式多用于材料加工過程.SIoutputis“top-hat”independentofinput單模式的輸出獨立于輸入呈大禮帽狀morerobust更有活力GIoutputmorefaithfulrepresentationofinput分級模式的輸出與輸入呈保持靠近,Cancreateproblemsifinputbeamqualitychanges如果輸入光束的質(zhì)量改變可能會產(chǎn)生問題.Canmakedeeperwelds/cuts可能焊接/切的更深.Weldprofilescouldchangebasedonfocusheight焦點高度可能產(chǎn)生焊接側(cè)面的變化,SIGI,0.6AspectRatio縱橫比1.5,“TopHat大禮帽狀”,WeldProfiles焊接剖面,.,FiberInputAlignment光纖輸入排列,GoodAlignment好的排列,Couldburnfiberinputend可能燒焦光線輸入莫端,Couldcreateplasmaatfocus在焦點產(chǎn)生等離子體,Couldburncladding可能燒傷覆層,.,SpotSizewithFiber光點直徑帶光纖,Spotsizeisanimageoftheoutputcorediameterofthefiber從光點的大小可以反應(yīng)出光纖核直徑的大小Sizedependsonmagnificationofthetwolensesinthefocushead其大小是由鏡頭前的兩個透鏡來決定的.,OpticalFiber光纖,CoreDiameter核直徑,SpotSize光點直徑,.,LaserSafety,CommonSense常識Doyounotputyourhandindirectpathofalaserbeam不要把手的頭放在雷射光束的路徑中.Donotlookdirectlyatalaserbeam不要直視雷射光束evenatthoselaserpointersbeams!不要看雷射點.Donotlookatanylaserprocesswithanakedeye不要用不防護(hù)的肉眼看任何的激光過程.useplasticsafetyglassesforCO2lasers用塑料防護(hù)眼鏡來防護(hù)CO2雷射.useYAGsafeglassesforYAGoperations在釔鋁石榴石操作中用釔鋁石榴石安全眼鏡,.,EyeDamage,NearUVfromweldingplasmaandUVlasersIfyouseebluishwhiteduringmaterialprocessing,youneedUVprotection;ordinaryplasticsafetyglassesarenotsufficient!如果你在材料加工的過程中看見藍(lán)白的光,你需要UV保護(hù),一般的塑料防護(hù)眼鏡是不起作用的.VisibleandNearIRfromYAGandfrequencydoubledlasers,Cornea角膜,Lens透鏡子,Retina視網(wǎng)膜,FarUVandFarIRNearUV接近UVVisibleandNearIR,.,CollateralDamage,Fumes煙Solvents,grease,etc.fromtheworkpiece溶劑,油脂等,Metaldustcouldbetoxic金屬顆?？赡苡卸?Decompositionproductsofplasticsprocessing(marking,welding,ordrilling)couldalsobetoxic在朔料加工的規(guī)程中的分解產(chǎn)品,(打表,焊接,或者鉆孔)也是有毒的.Installvacuumpumpsandappropriatefilters安裝真空泵和合適的過濾器.NeedspecialTidustcollectorswhenweldingTiinagloveboxformedicaldeviceapplications當(dāng)在用于醫(yī)療器械的手套盒子中焊接鈦的時候,需要特殊的吸鈦器.,.,FireHazard火災(zāi),LaserBeamscanhavebeenknowntocausefires鐳射激光能夠引起火災(zāi).Breaksinopticalfiber光纖削弱Makesureopticalfiberisnotwoundtootightly確保光學(xué)纖維不會太擊傷.LeakageinCO2directopticsLaserbeamwalkingoffworktableontoplasticcoversLaserbeaminteractionwithglovesinaglovebox,.,Laser-MaterialInteraction,Forlensandwindows,AandRhavetobesmall對于透鏡和窗戶,A和R應(yīng)該是小的.Formirrors,Rhastohigh對于鏡子,R應(yīng)該高一些ForLaser-basedmaterialsprocessing,AhastobehighandRshouldbelow對于以雷射原理為基礎(chǔ)的材料加工,A要高一些,R應(yīng)該要低一些.,IncidentEnergy入射能,Reflection反射,Absorption吸收,Transmission轉(zhuǎn)播,I=A+R+T,.,InitialReflectivityofMetals金屬的初始反射率,Greymetals(AgandAl)arereflectivetoallcolorsinvisiblespectrum灰色金屬(AgandAl)對所有的有色光譜中的顏色都有反射作用.Copperreflectsnearredwavelengthsandabsorbsothers銅在紅色波長附近反射,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碳鋼,Ni,Cu,Al,Nd:YAG,CO2,Source:IndustrialLaserApplications-JohnReady,.,LaserAngle雷射角落,Forallweldingapplications,thelasershouldbeangledoffverticaltopreventlaserenergyfromgoingbackintothelasercavityandcausingdamage對于所有的焊接應(yīng)用,雷射應(yīng)該與角落垂直以防雷射能量回到激光腔,引起損失.,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,;零件幾何,以及焊接池的形狀.,.,LaserWelding鐳射焊接,.,Configurations結(jié)構(gòu),Gapdimensionsbecomemorecriticalaspartsgetsmaller由于零件尺寸變小,縫隙的尺寸變得更重要,ButtWeld對接焊接Gap0.1t,t,Cap蓋子,Can罐子,t,.,Configurations,Gapdimensionsbecomemorecriticalaspartsgetsmaller由于零件尺寸變小,縫隙的尺寸變得更重要Canweldmultiplelayers罐子多層焊接,LapWeldGap0.15t,.,Configurations,Preferconfigurationswherethemoltenmaterialflowsintotheweldinsteadofpullingawayfromit最好的形狀是融化的物質(zhì)是流入到焊接而不是脫離焊接.,LapWeld,LapFillet,LapEdge,.,AnnularWelds,Fitupisimportant移動的臺面很重要.Ifgapispresent,stresseswilldeveloptowardstheendoftheweld如果有縫隙,應(yīng)力會隨著焊接而增大Press-fitpreferred最好有壓配合.,.,SmallVolumeWelds,Air/gasintheenclosedvolumeduringfinalweldheatsupandtriestoescape空氣在有限的空間里會隨著焊接的熱量膨脹,并試圖逸出.Cancauseporositytowardstheendoftheweld可能會在焊接的最后引起多孔.,AirPressureIncreasesDuringWelding在焊接餓過程中空氣的壓力增加,.,PressureRelief卸壓,Allowpressurereliefonenclosedvolumes如下情況需要泄壓Reducecrack-likefeatureswhichmaybecausedbyhighpressuretrappedinside泄壓可以減少像這種由于內(nèi)部壓力過大而引起的類似裂紋的缺陷.,.,ShieldGas,Mainfunctionofshieldinggasistoprotectthemoltenmetalfromreactingwithoxygen保護(hù)氣體的保護(hù)作用主要是保護(hù)融化的金屬不與氧氣反應(yīng).Shieldinggasalsohelpsto:保護(hù)氣體也有助于Protectlens/lenscoverfromweldsplatter保護(hù)透鏡,透鏡蓋不受焊接潑濺Controlplasmacloudformation控制等離子霧形成.Washawaymetalvaporsintheplume吹散等離子體中的金屬蒸汽.,.,ShieldGas,Whatisplasma?什么是等離子體Plasmaisionizedgas等離子是離子化氣體Electronsareseparatedfromatoms(metalaswellasshieldinggas)電子與原子分離(金屬和屏蔽氣體)Plasmaisthefourthstateofmatter;otherthreearesolid,liquid,andgas(等離子體是事物的第四種狀態(tài),其他的三種是固體,液體和氣體)Whatisplume?什么是等離子體?Plumeisamixtureofplasmaandmetalvapors等離子體是等離子以及金屬氣體的混合體.,Plume,.,ShieldGasesforYAGLasers,Heliumisidealbutveryexpensive氦很理想,但是很昂貴Argongasismostcommonlyused氬氣是最常用的Nitrogencanbeusedforsomealloys氮可以用于一些合金.Someweldsaremadeinair(noshieldinggas)buttheweldsurfaceisnotverysmooth有些焊接在空氣中做(沒有保護(hù)氣體)但是焊接表面不是太順滑Maystillproduceacceptableweldquality可能仍舊能夠產(chǎn)生有效的焊接質(zhì)量.,.,Soot,Sootisblackcoloreddust,typicallyreferredtoas“soot”thoughitisnotcomposedofcarbon煙是黑色的灰塵,雖然叫煤煙但它不是由碳組成的.“Soot”isafinedustofmetalpowderthatisdepositedfromtheplume煤煙是一種從等離子中沉淀下來的金屬粉末.,Chemicalanalysisof“soot”fromInconel600,.,ShieldGasConfiguration,Coaxial共軸Toohighdestabilizestheweldpool,increasedporosity太高-動搖焊接溶池,引起多孔.Toolowcancausenegativepressureandpulluptheweldmetal太低-會引起負(fù)壓力,使融化的金屬突起.Betterforshielding最好屏蔽SideFlow側(cè)流Usefulforsweepingawaytheionizationproducts用于清理等離子體.,.,PulsedYAG脈沖釔鋁石榴石,ImportantParameters重要的參數(shù)Pulse脈沖Width寬度Energy能量Power能量Shape形狀PulseOverlap脈沖交迭SpotSizeandFocus光點和焦點,.,PulsedYAG脈沖釔鋁石榴石,Energy(J)能量=Power(kW)力xWidth寬度(msec)Initialenergypeakhelpsthelaserenergytocouplewiththematerial初始的高能量可以使激光能量與金屬耦合.,ProgrammedPulse程序脈沖,PeakPower,PulseEnergy脈沖能量,PulseWidth脈沖寬度,ActualOutput實際輸出,.,PulsedYAG脈沖釔鋁石榴石,Shortpulseofhighpeakpowercancauseexpulsion高的峰值能量的短脈沖能引起坑.Longpulseoflowpeakpowerwillproduceawiderandshallowerweldbead低頂點能量的長脈沖會產(chǎn)生更寬和更淺的焊縫.,Power,PulseWidth,DeeperPenetration更深穿透GreaterPorosity更多多孔MoreExpulsion/Spatter更多飛濺,ShallowerPenetration更淺穿透LessPorosity更少多孔Cleanerweldswithnoporosity更干凈焊接沒有飛濺,.,Effectofpulsetimeonweldsize脈沖時間對焊接尺寸的影響,Weldspotdiameterincreasesrapidlyinthefirstfewmilli-seconds;rateofgrowthreduceswithtime焊斑直徑在最初的千分之一秒期間迅速變大,增長的速度隨著時間的增長而降低.,Time,WeldSize,.,Effectofpulsetimeonpenetration脈沖時間對焊接尺寸的影響,Foragivenpeakpower,weldpenetrationstabilizesafteracertainthresholdweldtime對于指定的能量高峰,焊接深度在一定的焊接時間后變得穩(wěn)定.Maximumpenetrationisdirectlyproportionaltopeakpower最大的深度是與能量高峰成直接正比的關(guān)系.Aboveacertainthresholdofpower,thelaserwillendupdrilling/cutting/gouginginsteadofwelding在一定能量的之上,雷射將鉆孔,切斷,咆削而不是焊接.,Time,Penetration,PeakPower1,PeakPower2,.,PulseShaping脈沖形狀,Singlepulseorthreesectorpulseofferedbycapacitorbasedpowersupplies由電源電容器產(chǎn)生的單脈沖和三個脈沖Newermachinesofferinvertertechnologywithcontinuouspulseshaping更新的提出的能夠提供無間斷的脈沖形狀.,Time(msec),PeakPower,Energy(J)能量=Power(kW)力xTime時間(msec),Single單個Three-sector三部分Multi-sector多部分,.,WeldCracking焊接破裂,Canisanchoredinthecapwhilecansurfacehasleverage罐子被錨在夾具中,而罐子的表面有杠桿作用.Weldcoolingalwaysintroducesresidualstresses焊接冷卻往往引起殘余壓力.Combinationoflargeweldvolumeandrapidcoolingcanintroduceexcessiveresidualstressesthatcausecracking大量焊接加之迅速冷卻能產(chǎn)生過量的殘余壓力從而引起破裂.,.,LaserFeatures:PulseShape雷射特征:脈沖形狀,MeltingandPenetrationPulse溶解滲透脈沖(CouplingPulse偶合脈沖),StabilizationPulse穩(wěn)定脈沖(controlledcoolingtoreduceexpulsionandresidualstresses控制冷卻減少殘余應(yīng)力.),6.0kW,2.0m-sec,50%,30%,0.2,.,PulseShaping脈沖形狀,Modifiedpulsegavetimefortheweldtocoolslowlyandallowtheporetoriseabovetheweldinterface改良脈沖使焊接冷卻的時間變慢,而且使得氣孔有時間從熔融的金屬中上升到表面,.,FocusHeight焦點高度,Atfocus,spotsizenotsensitivetofocusheight在焦點,點大小與焦點高度不相互影響.Atfocus,plumeistallestandsoundishighestpitch在焦點,等離子體是最高的,而且聲音也是最高調(diào)的.usedtofindfocusheight用于找出焦點高度.Focususuallysetatthesurfaceforpulsedwelding焦點通常設(shè)在表面為脈沖焊接.Focussetbelowsurfacefordeeperpenetrationandkeyholemodewelding焦點射在表面以下為更深的穿透和縮定焊接,.,PulseOverlap脈沖交疊,Dependsonthicknessofcomponentontopandshapeofweldbead取決于零件上端的厚度和焊縫的形狀.Overlapshouldbegreaterbyasafemargin在一定安全范圍之內(nèi),交疊會大一些.Note:Excessiveoverlapisexcessunwantedheatintotheweld注意:過量的交疊是過度的熱量在焊接中出現(xiàn).,Non-hermeticOverlap不密封交疊,HermeticOverlap密封交疊,.,PulseOverlap脈沖重疊,Lapweldsrequirehigheroverlap重疊焊接要求更高的重疊Buttweldscanbehermeticevenat50%overlap對接焊接可以被密封,即便是50%的重疊,ButtWeld對接焊接,LapWeld重疊焊接,ButtWeld對接焊接,.,LaserWeldQuality雷射焊接質(zhì)量,WeldSurfaceInspection焊接表面檢測Weldsurfaceshouldbecleanandfreeofspatter焊接表面需干凈,沒有滴濺Novisiblecracksorholes沒有可見的裂縫和孔.,Good,NotGood,.,LaserWeldQuality雷射焊接質(zhì)量,MechanicalTesting機械測試BurstStrength爆發(fā)力量PulltestorShearTest拉力測試和剪切測試LeakTest測漏測試StrengthAnalysis;力量分析Itisveryimportanttokeeptrackofwhereandwhenthefailuresoccurredduringtesting在測試中,記錄在那里和什么時候失敗是十分重要的Marklocationsoffailureforfurtheranalysis在失敗的地方做標(biāo)識是以便將來進(jìn)一步分析,.,WeldSectionAnalysis焊接部分分析,CrackedWeld焊接破裂,SmallPressureBubble?小壓力泡沫,GoodWeld好焊接,.,X-rayAnalysisX-RAY分析,Cracksgrowatanangleandappearasstraightlinesinthex-ray(shallowweldonright)破裂在一個角中擴大,在X-RAY中顯示為一條直線Smallporositiesmaybedifficulttoseeinsuchimages在這樣的圖片中很難看到小孔.Checkforalignment查看齊邊.,WeldCrack焊接破裂,ShallowWeld焊接陰影,Alignment,.,X-rayimagesofgoodweldsX-RAY中好的焊接,.,LaserMaintenance雷射維護(hù),Feedbackmonitoronlycheckslasercavityperformancedoesnotcheckpoweratweld反饋器只查看激光腔的性能-不會查看焊接時候的能量,LaserCavity激光腔,FocusHead焦點頭,EnergyMeter,BurnMarks,Plexiglas,etc.能量劑,火刺,樹脂玻璃,Lens透鏡,FeedbackMonitor監(jiān)視器反饋,.,EnergyMeters能量計,JouleMeters焦耳Setforsinglepulseoraverageovermultiplepulses定為單脈沖或者平均大于多脈沖Shouldbeusedperiodicallytoconfirmenergyattheweld在焊接的時候周期性的確認(rèn)能量Automationsystemcanbesetformeasurementatwarmupandaftersetnumberofpulsewelds在啟動的時候或者確定脈沖焊接的時候用自動化系統(tǒng).來確定量度.,.,Spotsizeandshape黑點的大小和形狀,Bur