Технология на лазерно заваряване

Basicinformation

Exciteelectronsormoleculestogenerateconcentratedandphase-identicallightbeamsduringtheconversionintoenergy.LasercomesfromthefirstletterofLightAmplificationbyStimulatedEmissionRadiation.composition.

Itiscomposedofanopticaloscillatorandamediumplacedbetweenthemirrorsatbothendsofthecavityoftheoscillator.Whenthemediumisexcitedtoahigh-energystate,itstartstogeneratelightwavesofthesamephaseandreflectbackandforthbetweenthemirrorsatbothends,formingaphotoelectricstringjunctioneffect,amplifyingthelightwaves,andobtainingsufficientenergytostartemittinglaserlight.Lasercanalsobeinterpretedasadevicethatconvertsprimitiveenergysuchaselectricenergy,chemicalenergy,heat,lightornuclearenergyintocertainspecificlightfrequencies(electromagneticradiationbeamsofultravioletlight,visiblelightorinfraredlight.)TheconversionformisinsomeItiseasytocarryoutinsolid,liquidorgaseousmedia.Whenthesemediaareexcitedintheformofatomsormolecules,theyproducelightbeamswithalmostthesamephaseandnearlyasinglewavelength—laser.Becauseofthesamephaseandsinglewavelength,thedifferenceangleisverysmall,andthedistancethatcanbetransmittedisquitelongbeforebeinghighlyconcentratedtoprovidefunctionssuchaswelding,cutting,andheattreatment.

Thefirstlaserbeamintheworldwasproducedbyusingaflashbulbtoexciteruby​​crystalgrainsin1960.Duetothethermalcapacityofthecrystal,itcanonlyproduceaveryshortpulsebeamwithaverylowfrequency.Althoughtheinstantaneouspulsepeakenergycanbeashighas10^6watts,itisstillalowenergyoutput.Theuseofneodymium(ND)astheexcitationelementofyttriumaluminumgarnetcrystalrods(Nd:YAG)canproduceacontinuoussingle-wavelengthbeamof1-8KW.YAGlaser,withawavelengthof1.06uM,canbeconnectedtothelaserprocessingheadthroughaflexibleopticalfiber,theequipmentlayoutisflexible,andthesuitableweldingthicknessis0.5-6mm.UsingCO2laser(wavelength10.6uM)withCO2astheexciter,theoutputenergycanreach25KW,anditcanmake2mmplatethicknesssinglepassfullpenetrationwelding.Ithasbeenwidelyusedintheindustryformetalprocessing.

Mostoftheearlylaserweldingresearchexperimentsusedruby​​pulsedlasers.Althoughhigherpulseenergycouldbeobtainedatthattime,theaverageoutputpoweroftheselaserswasquitelow,whichwasmainlycausedbytheverylowworkofthelasers.Determinedbytheefficiencyandtheexcitabilityoftheluminescentmaterial.LaserweldingmainlyusesCO2lasersandYAGlasers.YAGlasershavebecomethepreferredequipmentforlaserspotweldingandlaserseamweldingbecauseoftheirhighaveragepower.Thesignificantdifferencebetweenlaserweldingandelectronbeamweldingisthatlaserradiationcannotproduceperforationwelding.Infact,whenthelaserpulseenergydensityreaches10tothe6thpowerW/CM2,aweldholewillbeformedontheweldinginterfaceoftheweldedmetalmaterial,andtheformationconditionsofthesmallholewillbemet,sothatthelaserbeamcanbeusedfordeepening.Fusionwelding.

Beforethe1970s,becausehigh-powercontinuouswaveformlasershadnotyetbeendeveloped,researchfocusedonpulsedlaserwelding.Mostearlylaserweldingresearchexperimentsusedruby​​pulsedlasers.TheweldingprocessofYAGlasersiscarriedoutbyweldingjoints.Afterthebirthofcontinuouspowerwaveformlasersabove1KW,thereallaserseamweldingcanberealized.

Withthesuccessofthekilowatt-levelcontinuousCO2laserweldingtest,laserweldingtechnologymadeabreakthroughintheearly1970s.CO2laserweldingwascarriedoutonalargethicknessstainlesssteelspecimen,andapenetrationweldwasformed,whichclearlymarkedtheformationofsmallholes,andthedeeppenetrationweldproducedbylaserweldingwassimilartoelectronbeamwelding.TheseearlyworkusingCO2lasersformetalweldingprovedthegreatpotentialofhigh-powercontinuouslaserwelding.Intheaerospaceindustryandmanyotherapplications,laserweldingcanrealizetheconnectionofmanytypesofmaterials,andlaserweldingusuallyhasmanyadvantagesthatotherfusionweldingprocessescannotmatch,especiallylaserweldingcanconnectthemoredifficulttoweldintheaviationandautomotiveindustriesThin-platealloymaterials,suchasaluminumalloy,etc.,andthedeformationofthecomponentsissmall,andthejointqualityishigh.Anotherattractiveapplicationoflaserprocessingistheuseoflaserstoachievelocalandsmall-scaleheatingcharacteristics.Thishotspotoflasersmakesthemverysuitableforweldingelectronicdevicessuchasprintedcircuitboards.Laserscanbeusedinelectronicdevices.Averysmallareaonthedeviceproducesahighaveragetemperature,whiletheareaoutsidethejointisbasicallyunaffected.

Itbelongstofusionwelding,whichuseslaserbeamasenergysourcetoimpactontheweldmentjoint.Thelaserbeamcanbeguidedbyaflatopticalelement(suchasamirror),andthenareflectivefocusingelementorlensisusedtoprojectthebeamontheweld.Laserweldingisnon-contactwelding.Nopressureisrequiredduringtheoperation,butinertgasisrequiredtopreventoxidationofthemoltenpool.Fillermetalisoccasionallyused.LaserweldingcanbecombinedwithMIGweldingtoformlaser-MIGhybridweldingtoachievelargepenetrationwelding,andatthesametime,theheatinputisgreatlyreducedcomparedwithMIGwelding.

Featuresoflaserwelding

Firstofall,laserweldingcanreducetheamountofheatinputtotheminimum,themetallographicchangerangeoftheheat-affectedzoneissmall,andthedeformationcausedbyheatconductionisalsolowest.Thereisnoneedtouseelectrodes,andthereisnoconcernaboutelectrodecontaminationordamage.Andbecauseitisnotacontactweldingprocess,thewearanddeformationoftheequipmentcanbeminimized.Thelaserbeamiseasytofocus,alignandbeguidedbyopticalinstruments.Itcanbeplacedatanappropriatedistancefromtheworkpiece,andcanbeguidedbetweentoolsorobstaclesaroundtheworkpiece.Otherweldingmethodscannotbeusedduetotheabove-mentionedspacelimitations..Secondly,theworkpiececanbeplacedinaclosedspace(vacuumedortheinternalgasenvironmentisundercontrol).Thelaserbeamcanbefocusedonasmallarea,canweldsmallandcloselyspacedparts,canweldawiderangeofmaterials,andcanalsojoinvariousheterogeneousmaterials.Inaddition,itiseasytoautomatehigh-speedwelding,anditcanalsobecontrolledbydigitalorcomputer.Whenweldingthinmaterialsorthin-diameterwires,itisnotaseasytobetroubledasarcwelding.

Предимства на лазерното заваряване

(1)Полагането на топлина може да бъде намалено до минимално необходимата сума, металографската промяна на зоната на топлинно въздействие е малка, а деформацията, причинена от топлопроводимостта, също е най-ниска.

(2)Theweldingprocessparametersof32mmplatethicknesssinglepassweldinghavebeenverifiedandqualified,whichcanreducethetimerequiredforthickplateweldingandevensavetheuseoffillermetal.

(3)Thereisnoneedtouseelectrodes,andthereisnoconcernaboutelectrodecontaminationordamage.Andbecauseitisnotacontactweldingprocess,thewearanddeformationoftheequipmentcanbeminimized.

(4)Thelaserbeamiseasytofocus,alignandbeguidedbyopticalinstruments,canbeplacedatanappropriatedistancefromtheworkpiece,andcanbere-guidedbetweentoolsorobstaclesaroundtheworkpiece,otherweldingThelawcannotbeexertedduetotheabove-mentionedspaceconstraints.

(5) Заготовката може да бъде поставена в затворено пространство (под вакуум или във вътрешна газова среда под контрол).

(6) Лазерният лъч може да бъде фокусиран върху малка площ и да заварява малки и тясно разположени части.

(7) Гамата от заваряеми материали е широка и те също могат да се съединяват помежду си. Всички видове хетерогенни материали.

(8) Лесно е да се автоматизира високоскоростно заваряване и също така може да се управлява от цифров или компютър.

(9) Когато заварявате тънък материал или телове с тънък диаметър, няма да е лесно да създавате проблеми като заваряване.

(10)Не се влияе от магнитното поле (дъговото заваряване и заваряването с електронен лъч са лесни) и може точно да подравнява заваръчния материал.

(11) Могат да бъдат заварени два метала с различни физични свойства (като различни съпротивления)

(12)Необходима е нова защита срещу рентгенови лъчи.

(13) С перфорационно заваряване, съотношението дълбочина към ширина на заваръчния ръб може да достигне 10:1

(14)Устройството може да бъде превключвано за предаване на лазерния лъч към множество работни станции.

Параметри на процеса

Параметри на процеса на непрекъснато лазерно заваряване с CO2

Основните параметри на процеса на лазерно заваряване с дълбоко проникване

Laserpower

Thereisalaserenergydensitythresholdinlaserwelding.Belowthisvalue,thepenetrationdepthisveryshallow.Oncethisvalueisreachedorexceeded,thepenetrationdepthwillbegreatlyincreased.Onlywhenthelaserpowerdensityontheworkpieceexceedsthethreshold(relatedtothematerial),plasmawillbegenerated,whichmarkstheprogressofstabledeeppenetrationwelding.Ifthelaserpowerislowerthanthisthreshold,onlysurfacemeltingoftheworkpieceoccurs,thatis,weldingisperformedinastablethermalconductivitytype.Whenthelaserpowerdensityisnearthecriticalconditionfortheformationofsmallholes,deeppenetrationweldingandconductionweldingalternatelybecomeanunstableweldingprocess,resultinginlargefluctuationsinpenetration.Duringlaserdeeppenetrationwelding,thelaserpowercontrolsthepenetrationdepthandweldingspeedatthesametime.Theweldingpenetrationisdirectlyrelatedtothebeampowerdensity,andisafunctionoftheincidentbeampowerandthebeamfocalspot.Generallyspeaking,foralaserbeamwithacertaindiameter,thepenetrationdepthincreasesasthebeampowerincreases.

Фокална точка на лъча

Размерът на точката на лъча е една от най-важните променливи в лазерното заваряване, тъй като определя плътността на мощността. Но за високомощните лазери измерването му е труден проблем, въпреки че има много техники за индиректно измерване.

Thediffraction-limitedspotsizeofthebeamfocuscanbecalculatedaccordingtothetheoryoflightdiffraction,butduetotheaberrationofthefocusinglens,theactualspotislargerthanthecalculatedvalue.Thesimplestactualmeasurementmethodistheisothermalprofilemethod,whichistomeasurethefocalspotandperforationdiameterafterscorchingthickpaperandpenetratingthepolypropyleneplate.Thismethodshouldbepracticedthroughmeasurementtomasterthesizeofthelaserpowerandthetimeofbeamaction.

Стойност на поглъщане на материала

Поглъщането на лазерна светлина от материала зависи от някои важни свойства на материала, като поглъщаемост, отразяваща способност, топлопроводимост, температура на топене, температура на изпаряване и т.н., сред които най-важното е степента на поглъщане.

Thefactorsaffectingtheabsorptivityofthelaserbeamincludetwoaspects:thefirstistheresistivityofthematerial.Aftermeasuringtheabsorptivityofthepolishedsurfaceofthematerial,itisfoundthattheabsorptivityofthematerialisproportionaltothesquarerootoftheresistivity.,Andtheresistivitychangeswithtemperature;secondly,thesurfacestate(orsmoothness)ofthematerialhasamoreimportantinfluenceonthebeamabsorptionrate,whichhasasignificanteffectontheweldingeffect.

TheoutputwavelengthofCO2laserisusually10.6μm.Theabsorptionrateofceramics,glass,rubber,plasticsandothernon-metalsisveryhighatroomtemperature,whiletheabsorptionofmetalmaterialsisverypooratroomtemperature.,Untilthematerialmeltsandevenvaporizes,itsabsorptionincreasessharply.Themethodofusingsurfacecoatingorgeneratingoxidefilmonthesurfaceisveryeffectiveinimprovingtheabsorptionofthelightbeambythematerial.

Weldingspeed

Weldingspeedhasagreatinfluenceonpenetration.Increasingthespeedwillmakethepenetrationshallower,butifthespeedistoolow,itwillcauseexcessivemeltingofthematerialandweldpenetrationoftheworkpiece.Therefore,thereisasuitableweldingspeedrangeforacertainlaserpowerandacertainthicknessofacertainmaterial,andthemaximumpenetrationdepthcanbeobtainedatthecorrespondingspeedvalue.

Shieldinggas

Thelaserweldingprocessoftenusesinertgastoprotectthemoltenpool.Whensomematerialsarewelded,thesurfaceoxidationmaynotbeconsidered,buttheprotectionmaynotbeconsidered,butformostapplicationsGasessuchashelium,argon,andnitrogenareoftenusedforprotectiontopreventtheworkpiecefrombeingoxidizedduringtheweldingprocess.

Heliumisnoteasytoionize(highionizationenergy),whichallowsthelasertopasssmoothly,andthebeamenergyreachesthesurfaceoftheworkpiecewithouthindrance.Thisisthemosteffectiveshieldinggasusedinlaserwelding,butitismoreexpensive.

Argonischeaperanddenser,sotheprotectioneffectisbetter.However,itissusceptibletohigh-temperaturemetalplasmaionization,whichshieldspartofthebeamfromreachingtheworkpiece,reducestheeffectivelaserpowerforwelding,andalsodamagestheweldingspeedandpenetration.Thesurfaceoftheweldmentprotectedbyargonissmootherthanwhenprotectedbyhelium.

Nitrogenisthecheapestshieldinggas,butitisnotsuitableforweldingcertaintypesofstainlesssteel,mainlyduetometallurgicalproblems,suchasabsorption,whichsometimescreatesporesintheoverlaparea.

Thesecondfunctionofusingshieldinggasistoprotectthefocusinglensfrommetalvaporcontaminationandliquiddropletssplashing.Especiallyinhigh-powerlaserwelding,becausetheejectionbecomesverypowerful,itismorenecessarytoprotectthelensatthistime.

Thethirdfunctionoftheshieldinggasistodissipatetheplasmashieldingproducedbyhigh-powerlaserwelding.Themetalvaporabsorbsthelaserbeamandionizesintoaplasmacloud,andtheshieldinggasaroundthemetalvaporisalsoionizedbyheating.Ifthereistoomuchplasma,thelaserbeamisconsumedbytheplasmatosomeextent.Plasmaexistsasthesecondkindofenergyontheworkingsurface,whichmakesthepenetrationdepthbecomeshallowerandtheweldpoolsurfacebecomeswider.Increasetheelectronrecombinationratebyincreasingthethree-bodycollisionofelectronswithionsandneutralatomstoreducetheelectrondensityintheplasma.Thelightertheneutralatom,thehigherthecollisionfrequency,andthehighertherecombinationrate.Ontheotherhand,onlytheshieldinggaswithhighionizationenergywillnotincreasetheelectrondensityduetotheionizationofthegasitself.

Атомно (молекулно) тегло и йонизираща енергия на често използвани газове и метали

Материал хелий, аргон, азот, алуминий, магнезий, желязо

Атомно (молекулно) тегло 44028272456

Енергия на йонизация (eV)24,4615,6814,55,967,617,83

Fromthetable,thesizeoftheplasmacloudvarieswiththeprotectivegasused.HeliumisthesmallestandnitrogenSecond,thelargestwhenusingargon.Thelargertheplasmasize,theshallowerthepenetrationdepth.Thereasonforthisdifferenceisfirstlyduetothedifferenceinthedegreeofionizationofgasmolecules,andalsoduetothedifferenceinmetalvapordiffusionduetothedifferentdensityoftheprotectivegas.

Heliumhasthesmallestionizationandthesmallestdensity.Itcanquicklydriveouttherisingmetalvaporgeneratedfromthemoltenmetalpool.Therefore,usingheliumasashieldinggascansuppresstheplasmatothegreatestextent,therebyincreasingthepenetrationdepthandincreasingtheweldingspeed;becauseofitslightweight,itcanescape,anditisnoteasytocausepores.Ofcourse,judgingfromouractualweldingeffect,theeffectofargonprotectionisnotbad.

Theinfluenceofplasmacloudonpenetrationismostobviousinthelowweldingspeedarea.Whentheweldingspeedincreases,itsinfluencewillbeweakened.

Theshieldinggasisejectedthroughthenozzleopeningatacertainpressuretoreachthesurfaceoftheworkpiece.Thehydrodynamicshapeofthenozzleandthediameteroftheoutletareveryimportant.Itmustbelargeenoughtodrivethesprayedshieldinggastocovertheweldingsurface,butinordertoeffectivelyprotectthelensandpreventmetalvaporcontaminationormetalsplashfromdamagingthelens,thesizeofthenozzlemustalsobelimited.Theflowrateshouldalsobecontrolled,otherwisethelaminarflowoftheshieldinggaswillbecometurbulent,andtheatmospherewillbedrawnintothemoltenpoolandeventuallyformpores.

Inordertoimprovetheprotectioneffect,anadditionalsideblowingmethodcanbeused,thatis,theshieldinggasisdirectlyinjectedintothedeeppenetrationweldingholeatacertainanglethroughasmallerdiameternozzle.Theshieldinggasnotonlysuppressestheplasmacloudonthesurfaceoftheworkpiece,butalsoexertsaninfluenceontheformationofplasmaandsmallholesinthehole,andthepenetrationdepthisfurtherincreased,andaweldwithanidealdepthandwidthisobtained.However,thismethodrequiresprecisecontrolofthesizeanddirectionoftheairflow,otherwiseitiseasytoproduceturbulentflowanddestroythemoltenpool,makingtheweldingprocessdifficulttostabilize.

Lensfocallength

Whenwelding,focusisusuallyusedtoconvergethelaser.Generally,alenswithafocallengthof63~254mm(2.5”~10”)isused.Thefocalspotsizeisproportionaltothefocallength,theshorterthefocallength,thesmallerthespot.However,thefocallengthalsoaffectsthefocaldepth,thatis,thefocaldepthincreasessynchronouslywiththefocallength,soashortfocallengthcanincreasethepowerdensity,butbecausethefocaldepthissmall,thedistancebetweenthelensandtheworkpiecemustbeaccuratelymaintained,andthepenetrationdepthisnotlarge.Duetotheinfluenceofspatterandlasermodeduringwelding,theshortestfocaldepthusedinactualweldingismostlyfocallength126mm(5").Whentheseamislargeorthespotsizeneedstobeincreasedtoincreasetheweldseam,Choosealenswithafocallengthof254mm(10").Inthiscase,inordertoachievethedeeppenetrationpinholeeffect,ahigherlaseroutputpower(powerdensity)isrequired.

Whenthelaserpowerexceeds2kW,especiallyforthe10.6μmCO2laserbeam,duetotheuseofspecialopticalmaterialstoformtheopticalsystem,inordertoavoidtheriskofopticaldamagetothefocusinglens,thereflectivefocusingmethodisoftenused.Apolishedcoppermirrorisusedasareflector.Becauseofitseffectivecooling,itisoftenrecommendedforhigh-powerlaserbeamfocusing.

Focusposition

Whenwelding,inordertomaintainsufficientpowerdensity,thefocuspositionisveryimportant.Thechangeoftherelativepositionofthefocusandthesurfaceoftheworkpiecedirectlyaffectsthewidthanddepthoftheweld.

Inmostlaserweldingapplications,thefocalpointisusuallysetatabout1/4oftherequiredpenetrationdepthbelowthesurfaceoftheworkpiece.

Laserbeamposition

Whenlaserweldingdifferentmaterials,thelaserbeampositioncontrolsthefinalqualityoftheweld,especiallyinthecaseofbuttjointsthanlapjointsMoresensitivetothis.Forexample,whenahardenedsteelgearisweldedtoalow-carbonsteeldrum,thecorrectcontrolofthelaserbeampositionwillhelptoproduceaweldmainlycomposedoflow-carboncomponents,whichhasbettercrackresistance.Insomeapplications,thegeometryoftheweldedworkpiecerequiresthelaserbeamtobedeflectedbyanangle.Whenthedeflectionanglebetweenthebeamaxisandthejointplaneiswithin100degrees,theworkpiece'sabsorptionoflaserenergywillnotbeaffected.

Контрол на мощността

Мощността на лазера в началната и крайната точка на заваряването постепенно се увеличава и намалява.

Duringlaserdeeppenetrationwelding,nomatterthedepthoftheweld,smallTheholephenomenonalwaysexists.Whentheweldingprocessisterminatedandthepowerswitchisturnedoff,pitswillappearattheendoftheweld.Inaddition,whenthelaserweldinglayercoverstheoriginalweld,excessiveabsorptionofthelaserbeamwilloccur,causingtheweldmenttooverheatorproducepores.

Inordertopreventtheoccurrenceoftheabovephenomenon,thepowerstartandendpointscanbeprogrammedtomakethepowerstartandendtimeadjustable,thatis,thestartpowerrisesfromzerotozeroinashortperiodoftimeusingelectronicmethods.Setthepowervalueandadjusttheweldingtime.Finally,whentheweldingisterminated,thepowerisgraduallyreducedfromthesetpowertozero.

Предимства и недостатъци

(1) Позицията на заваръчния елемент трябва да бъде много прецизна и трябва да бъде във фокусния диапазон на лазерния лъч.

(2)Whentheweldmentneedstouseajig,itmustbeensuredthatthefinalpositionoftheweldmentisalignedwiththeweldingpointthatthelaserbeamwillimpact.

(3)Themaximumweldablethicknessisrestrictedtopenetratetheworkpiecewithathicknessfarexceeding19mm,andlaserweldingisnotsuitablefortheproductionline.

(4) За материали с висока отразяваща способност и висока топлопроводимост, като алуминий, мед и техните сплави, заваряемостта ще бъде променена от лазер.

(5)Whenperformingmediumtohighenergylaserbeamwelding,aplasmacontrollermustbeusedtodriveouttheionizedgasaroundthemoltenpooltoensurethereappearanceoftheweldbead.

(6) Ефективността на преобразуване на енергия е много ниска, обикновено по-малка от 10%.

(7) Заваръчните плочи се втвърдяват бързо и може да има опасения за порьозност и крехкост.

(8)Оборудването е скъпо.

Inordertoeliminateorreducethedefectsoflaserweldingandmakebetteruseofthisexcellentweldingmethod,someotherheatsourceandlaserhybridweldingprocesseshavebeenproposed,mainlylaserandarc,laserandplasmaArc,laserandinductionheatsourcehybridwelding,duallaserbeamweldingandmulti-beamlaserwelding,etc.Inaddition,variousauxiliaryprocessmeasureshavebeenproposed,suchaslaserfillerwirewelding(whichcanbesubdividedintocoldwireweldingandhotwirewelding),externalmagneticfieldassistedenhancedlaserwelding,shieldinggascontrolledmoltenpooldepthlaserwelding,andlaserassistedfrictionstirweldingWait.

(1)Powerdensity.Powerdensityisoneofthemostcriticalparametersinlaserprocessing.Withahigherpowerdensity,thesurfacelayercanbeheatedtotheboilingpointwithinamicrosecondtimerange,resultinginalargeamountofvaporization.Therefore,highpowerdensityisbeneficialformaterialremovalprocessing,suchaspunching,cutting,andengraving.Forlowerpowerdensities,ittakesseveralmillisecondsforthesurfacetemperaturetoreachtheboilingpoint.Beforethesurfacelayervaporizes,thebottomlayerreachesthemeltingpoint,whichmakesiteasytoformagoodfusionweld.Therefore,inconductivelaserwelding,thepowerdensityisintherangeof10^4~10^6W/CM^2.

(2)Laserpulsewaveform.Thelaserpulsewaveformisanimportantissueinlaserwelding,especiallyforsheetwelding.Whenahigh-intensitylaserbeamhitsthesurfaceofthematerial,60~98%ofthelaserenergywillbereflectedandlostonthemetalsurface,andthereflectivitychangeswiththesurfacetemperature.Duringalaserpulse,thereflectivityofthemetalchangesgreatly.

(3)Laserpulsewidth.Pulsewidthisoneoftheimportantparametersofpulselaserwelding.Itisnotonlyanimportantparameterdifferentfrommaterialremovalandmaterialmelting,butalsoakeyparameterthatdeterminesthecostandvolumeofprocessingequipment.

(4)Theeffectofdefocusingamountonweldingquality.Laserweldingusuallyrequiresacertaindegreeofseparation,becausethepowerdensityinthecenterofthespotatthelaserfocalpointistoohighanditiseasytoevaporateintoahole.Oneachplaneawayfromthelaserfocus,thepowerdensitydistributionisrelativelyuniform.Therearetwodefocusingmethods:positivedefocusandnegativedefocus.Ifthefocalplaneisabovetheworkpiece,itisapositivedefocus,otherwiseitisanegativedefocus.Accordingtothegeometricopticstheory,whenthedistancebetweenthepositiveandnegativedefocusplanesandtheweldingplaneisequal,thepowerdensityonthecorrespondingplanesisapproximatelythesame,buttheshapeofthemoltenpoolobtainedisactuallydifferent.Whenthedefocusisnegative,agreaterpenetrationdepthcanbeobtained,whichisrelatedtotheformationprocessofthemoltenpool.Experimentsshowthatthematerialstartstomeltwhenthelaserisheatedfor50~200us,formingliquidmetalandvaporizing,formingcitypressuresteam,whichissprayedataveryhighspeedandemitsdazzlingwhitelight.Atthesametime,thehighconcentrationofvaporcausestheliquidmetaltomovetotheedgeofthemoltenpool,formingadepressioninthecenterofthemoltenpool.Whenthedefocusisnegative,theinternalpowerdensityofthematerialishigherthanthatofthesurface,anditiseasytoformstrongermeltingandvaporization,sothatthelightenergycanbetransmittedtothedeeperpartofthematerial.Therefore,inpracticalapplications,whenthepenetrationdepthisrequiredtobelarge,thenegativedefocusisused;whenthethinmaterialiswelded,thepositivedefocusshouldbeused.

Приложение

Технологията на машината за лазерно заваряване се използва широко във високопрецизни производствени области като автомобили, кораби, самолети, високоскоростни железопътни линии и т.н., което е довело до значително подобрение на качеството на живот на хората и е довело до навлизането на индустрията за домашни уреди в ерата на Seiko.

Especiallyafterthe42-meterseamlessweldingtechnologycreatedbyVolkswagen,whichgreatlyimprovedtheintegrityandstabilityofthebody,HaierGroup,aleadinghomeappliancecompany,grandlylaunchedthefirstwashingmachineproducedbylaserseamlessweldingtechnology.,Thehomeappliancecherishestheadvancementofscienceandtechnologyforthepeople,andadvancedlasertechnologycanbringhugechangestopeople'slives.Withthecontinuousconsolidationoftheglobalbrandstatusofwashingmachines,itsleadershipintheindustryhasbeguntobefullydemonstrated.However,withthesupportoflaserweldingmachinetechnology,itwillalsohaveadeeperreformofthehomeapplianceindustry.AccordingtoHaier'sR&Dpersonnel,mostofthemanufacturingtechnologyoftheinnertuboffullyautomaticwashingmachinesonthemarketadopts"snap-and-loop"technology.Therewillbegapsorunevennessinthejointsoftheinnertub,resultinginlowstrengthofthetubandunnecessarywearandtearontheclothes.Inordertofurtherimprovethereliabilityandrefinementoftheinnertub,Haierwashingmachinetakestheautomobileandshipbuildingindustriesasthereferencebase,andappliesthelaserseamlessweldingtechnologytothenewuniformpowerwashingmachine,avoidingthegapandunevennessoftheinnertub,andimprovingtheoverallperformance.Improvethereliabilityoftheproductwhiletakingcareoftheclothes.Duetotheincreaseinthestrengthoftheinnertub,themaximumspeedoftheuniformpowerwashingmachineduringthedehydrationprocessisalsoincreasedby25%comparedwiththeordinaryfullyautomaticwashingmachine,thedehydrationefficiencyisgreatlyimproved,andthepowerconsumptionislessandthetimeissaved.

Inaddition,Ialsolearnedthatthe"high-powerlaserweldingmachinetechnology"jointlydevelopedbytheSino-Germanshipbuildingindustryensuresthesafetyofshipsandfurtherstrengthensthehullstructure;intheaviationfield,laserseamlessWeldingtechnologyhasalsobeenwidelyusedinthemanufactureofaircraftengines.Atthesametime,thelaserseamlessweldingtechnologyofaluminumalloyfuselagecanreplacerivets,therebyreducingtheweightofthefuselageby20%;China'shigh-speedrailtrackhasalsointroducedlaserseamlesswelding.Technology,whileimprovingsafetyperformance,alsogreatlyreducesnoise,bringingpassengersaquietandcomfortableridingenvironment.

Withtheall-rounddevelopmentofscienceandtechnology,thecontinuousconsolidationandapplicationoflaserweldingmachinetechnologyhasalsoledtheglobalhomeapplianceindustryintoanewera.Thenewprocessisnotonlyanupgradeofproducts,butalsomoretechnologyDisplayandapplication.

1.ManufacturingindustryapplicationTailoredBlandLaserWeldingtechnologyhasbeenwidelyusedinforeigncarmanufacturing.Accordingtostatistics,in2000,thereweremorethan100lasertailoredweldingproductionlinesforcuttingblanksworldwide,withanannualoutputThereare70milliontailor-weldedblanksforcarcomponents,anditcontinuestogrowatarelativelyhighrate.ThedomesticallyproducedimportedmodelsPassat,Buick,Audi,etc.alsousesomecutblankstructures.JapanusesCO2laserweldinginsteadofflashbuttweldingfortheconnectionofrolledsteelcoilsinthesteelindustry.Intheresearchofultra-thinplatewelding,suchasfoilswithathicknessoflessthan100microns,theycannotbewelded,buttheyhavespecialoutputpowerwaveforms.ThesuccessofYAGlaserweldingshowsthebrightfutureoflaserwelding.JapanhasalsosuccessfullydevelopedtheuseofYAGlaserweldingforthemaintenanceofsteamgeneratorthintubesinnuclearreactorsforthefirsttimeintheworld.InChina,SuBaorongandothershavealsocarriedoutlaserweldingtechnologyforgears.

2.ThefieldofpowdermetallurgyWiththecontinuousdevelopmentofscienceandtechnology,manyindustrialtechnologieshavespecialrequirementsformaterials,andmaterialsmadebysmeltingandcastingmethodscannolongermeettheneeds.Becausepowdermetallurgymaterialshavespecialpropertiesandmanufacturingadvantages,theyarereplacingtraditionalsmeltingmaterialsincertainfieldssuchasautomobiles,airplanes,andtoolandcuttingtoolmanufacturing.Withtheincreasingdevelopmentofpowdermetallurgymaterials,thereareproblemswiththeconnectionbetweenthemandotherparts.Appearsincreasinglyprominent,sothattheapplicationofpowdermetallurgymaterialsisrestricted.Intheearly1980s,laserweldingenteredthefieldofpowdermetallurgymaterialprocessingwithitsuniqueadvantages,openingupnewprospectsfortheapplicationofpowdermetallurgymaterials,suchastheuseofbrazingmethodscommonlyusedinpowdermetallurgyLowstrength,wideheat-affectedzone,especiallyincapableofadaptingtohightemperatureandhighstrengthrequirements,causingthesoldertomeltandfalloff.Theuseoflaserweldingcanimprovetheweldingstrengthandhightemperatureresistance.

3.AutomobileindustryInthelate1980s,kilowatt-levellasersweresuccessfullyappliedtoindustrialproduction.Nowadays,laserweldingproductionlineshaveemergedfrommodernautomobilemanufacturingonalargescaleandbecomeoneoftheoutstandingachievementsofautomobilemanufacturing.EuropeanautomobilemanufacturerssuchasAudi,Mercedes-Benz,Volkswagen,andVolvoofSwedentooktheleadinadoptinglaserweldingforroof,body,sideframesandothersheetmetalweldingasearlyasthe1980s.Inthe1990s,GM,FordandChryslercompetedintheUnitedStates.Theintroductionoflaserweldingintoautomobilemanufacturing,despiteitslatestart,hasdevelopedrapidly.ItalianFiatuseslaserweldingintheweldingandassemblyofmoststeelplatecomponents.Japan'sNissan,Honda,andToyotaMotorCorporationuselaserweldingandcuttingprocessesinthemanufactureofbodypanels.High-strengthsteellaserweldingassemblypartsareduetotheirexcellentperformance.Itisusedmoreandmoreinautomobilebodymanufacturing.AccordingtothestatisticsoftheUSmetalmarket,bytheendof2002,theconsumptionoflaserweldedsteelstructureswillreach70,000tons,whichisthreetimesmorethanin1998.Accordingtothecharacteristicsoflargebatchesandhighdegreeofautomationintheautomotiveindustry,laserweldingequipmentisdevelopinginthedirectionofhigh-powerandmulti-channel.Intermsoftechnology,SandiaNationalLaboratoryoftheUnitedStatesandPrattWitneyhavejointlyconductedresearchonaddingpowdermetalandmetalwireinthelaserweldingprocess.TheInstituteofAppliedBeamTechnologyinBremen,Germanyhasconductedalotofresearchontheuseoflaserweldingofaluminumalloybodyframes.Itisbelievedthataddingfillerresiduesintheweldwillhelpeliminatehotcracks,increaseweldingspeed,andsolvetoleranceproblems.ThedevelopedproductionlinehasbeenputintoproductionattheMercedes-Benzfactory.

4.ElectronicsindustryLaserweldinghasbeenwidelyusedintheelectronicsindustry,especiallyinthemicroelectronicsindustry.Duetothesmallheat-affectedzoneoflaserwelding,theheatingconcentrationisrapidandthethermalstressislow.Therefore,itisshowinguniqueadvantagesinthepackagingofintegratedcircuitsandsemiconductordeviceshells.Inthedevelopmentofvacuumdevices,laserweldinghasalsobeenapplied,suchasmolybdenumFocusingelectrodeandstainlesssteelsupportring,fasthotcathodefilamentassembly,etc.Thethicknessoftheelasticthin-walledcorrugatedsheetinthesensororthermostatis0.05-0.1mm,whichisdifficulttosolvebytraditionalweldingmethods.TIGweldingiseasytoweldthrough,theplasmastabilityispoor,andtherearemanyinfluencingfactors.Thelaserweldingeffectisverygood,anditiswidelyused.Applications.

5.Laserweldingofbiomedicalbiologicaltissuesbeganinthe1970s.Klinketal.andJain[13]usedlaserweldingtoweldfallopiantubesandbloodvesselssuccessfullyanddemonstratedsuperiority,whichledtomoreresearchTheauthorstrytoweldvariousbiologicaltissuesandpromotetheweldingofothertissues.Theresearchonlaserweldingnerveathomeandabroadmainlyfocusesonthelaserwavelength,doseanditsfunctionrecoveryandtheselectionoflasersolder.OnthebasisofbasicresearchonlaserweldingofsmallbloodvesselsandskinThecommonbileductoftheratwaswelded.Comparedwiththetraditionalsuturemethod,laserweldinghastheadvantagesoffastanastomosis,noforeignbodyreactionduringthehealingprocess,maintainingthemechanicalpropertiesoftheweldedpart,andthegrowthoftherepairedtissueaccordingtoitsoriginalbiomechanicalproperties.Itwillbeusedinfuturebiomedicine.Getawiderrangeofapplications.

6.Otherfields.Inotherindustries,laserweldingisalsograduallyincreasing,especiallyinspecialmaterialswelding.Manydomesticresearcheshavebeencarriedout,suchaslaserweldingofBT20titaniumalloy,Hel30alloy,Li-ionbattery,etc.,GermanglassmachinerymanufacturerGlamacoCoswigandIFWJointTechnologyandMaterialsExperimentalResearchInstitutehavedevelopedanewlaserweldingtechnologyforflatglass.

Advantagesofhybridwelding

Laserhybridweldingtechnologyhassignificantadvantages.Forlasermixing,theadvantagesaremainlyreflectedintoday's:largerpenetration/largergapweldingability;bettertoughnessoftheweld,theadditionofauxiliarymaterialscanaffecttheweldlatticestructure;thebackoftheweldwithoutburn-throughThephenomenonofsagging;thescopeofapplicationiswider;withthehelpoflaserreplacementtechnology,theinvestmentisless.ForthehybridlaserMIGinertgasshieldedwelding,theadvantagesaremainlyreflectedintoday's:higherweldingspeed;largefusionweldingdepth;lessweldingheatgenerated;highweldstrength;smallweldwidth;smallweldprotrusion.Thereby,theproductionprocessofthewholesystemisstableandtheequipmentavailabilityisgood;theworkloadofweldingseampreparationandweldingseamprocessingafterweldingissmall;theweldingproductiontimeisshort,thecostislow,andtheproductionefficiencyishigh;ithasgoodopticalequipmentconfigurationperformance.

However,theinvestmentcostoflaserhybridweldinginpowerequipmentisrelativelyhigh.Withthefurtherexpansionofthemarket,thepriceofpowerequipmentwillalsodrop,andlaserhybridweldingtechnologywillbeappliedinmorefields.Atleastthelaserhybridweldingtechnologyisaverysuitableweldingprocessintheweldingofaluminumalloymaterials,andwillbecomethemainweldingproductiontoolinalongperiodoftime.

Developmentstatus

Foreignlasertechnologyandmanufacturingarerelativelydeveloped.Theyhavealreadybeguntostudyhowtoapplymodernlasertechnologytotraditionalmanufacturingasearlyasthe1980s.WesterncountriessuchastheEuropeanUnion,theUnitedStates,andJapaninAsiarelyontheirowndevelopedscientificandtechnologicalstrengthandagoodmanufacturingfoundation,underthereasonableguidanceandfinancialsupportofthegovernment,thedevelopmentoflaserweldingtechnologyisveryrapid,especiallyafterenteringthenewcentury.Theapplicationoflaserweldingtechnologycanbeseeninmanymanufacturingandotherindustries,includingtheelectronicsindustry,shipbuildingindustry,automobileindustry,etc.,andtheapplicationofmodernlaserweldingtechnologycanbeseen.Andtheindustrystandardofweldingtechnologyhasbeenpreliminarilyformed,sothatitcanbeappliedinareasonableandcontrollablerange.Atthesametime,inordertofurtherimproveweldingefficiencyandenablelaserweldingtechnologytobebetterappliedtomodernlarge-scaleproduction,especiallylarge-scalemanufacturingandconstructionindustries,Westerndevelopedcountrieshavebeenactivelystudyinghowtoimprovetheefficiencyoflaserweldinginrecentyears.Theresearchofpowerlasersfurtherpromotesandrealizestherealizationofhigh-powerlaserweldingtechnology,thustrulyapplyingittolarge-scalemanufacturing,construction,andevenmilitaryfieldsforthemanufacturingofsubmarinesandwarships.

In2016,theHarbinWeldingResearchInstitutewastheleaderinlaserweldingtechnologyresearchinChina.Inrecentyears,inadditiontofurtherbroadeninganddevelopingnewtypesoflaserweldingandequipment,itisalsoactivelyimitatingandreferringtothelatesttrendsinforeignresearch,andconstantlyseekingbreakthroughsanddevelopmentsinhigh-powerlaserweldingtechnology.Thelatestresearchresultsshowthattheysuccessfullyovercometheweldingproblemsofdomesticlarge-scalecomponents,whichundoubtedlymarksamajorbreakthroughinthefieldoflaserweldingtechnologyinmycountry,andalsolaysthefoundationformajorapplicationsinlarge-scaleprojectsinthefuture.Inaddition,thedomesticlaserweldingtechnologyresearchin2016wasalsoconcentratedinthefieldsoflaserhotwirewelding,dissimilarmetalwelding,etc.,whicharethelatesttopicsofmodernlaserweldingtechnologyresearch.Andforeigncountrieshavemadebreakthroughsinrelatedresearchfields,especiallyGermanyhasinitiallymasteredthetechniquesandmethodsofdissimilarmetalwelding.Inthefuture,ourcountrymustbetrulyproficientintheapplicationandmasteryoflaserweldingtechnology,andapplyittomorefieldsandIntheindustry,itisundoubtedlynecessarytoovercometheabove-mentionedissuesandtofurtherimproveandoptimizethelaserweldingtechnology.

Prospects

Laserweldingisacombinationofmoderntechnologyandtraditionaltechnology.Comparedwithtraditionalweldingtechnology,laserweldingisespeciallyuniqueanditsapplicationfieldsandapplicationlevelsaremoreextensive.,Cangreatlyimprovetheefficiencyandaccuracyofwelding.Itshighpowerdensityandfastenergyreleasecanbetterimproveworkefficiency.Atthesametime,itsownfocuspointissmaller,whichundoubtedlymakestheadhesionbetweenstitchedmaterialsbetter,andwillnotcausematerialdamageanddeformation.Theemergenceoflaserweldingtechnologyhasrealizedthefieldsthattraditionalweldingtechnologycannotapply.Itcansimplyachievevariousweldingrequirementsofdifferentmaterials,metalsandnon-metals,andbecauseofthepenetrationandrefractionofthelaseritself,itcanbebasedonThetrajectoryofthespeedoflightitselfcanachieverandomfocuswithin360degrees,whichisundoubtedlyunimaginableunderthedevelopmentoftraditionalweldingtechnology.Inaddition,becauselaserweldingcanreleasealargeamountofheatinashortperiodoftimetoachieverapidwelding,ithaslowerenvironmentalrequirementsandcanbeperformedundergeneralroomtemperatureconditions,withouttheneedforvacuumorgasprotection.Afterdecadesofdevelopment,peoplehavethehighestlevelofunderstandingandrecognitionoflasertechnology,andithasgraduallyexpandedfromtheinitialmilitaryfieldtothemoderncivilianfield,andtheemergenceoflaserweldingtechnologyhasfurtherexpandedtheapplicationrangeoflasertechnology.Inthefuture,laserweldingtechnologycannotonlybeusedinfieldssuchasautomobiles,steel,andinstrumentmanufacturing,butalsoinmilitary,medical,andotherfields,especiallyinthemedicalfield,withthehelpofitsownhighheatandhightemperature.Thecharacteristicsofintegrationandhygienecanbebetterappliedinclinicaldiagnosisandtreatmentsuchasneuromedicineandreproductivemedicine.Anditsownprecisionadvantageswillalsobeappliedinmoreprecisioninstrumentmanufacturingindustries,whichwillcontinuetobenefitthedevelopmentofmankindandsociety.