Numerical analysis of the dynamic growth of droplets in gas metal arc welding

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1、1247NumericalanalysisofthedynamicgrowthofdropletsingasmetalarcweldingYMZhang*andELiguoWeldingResearchLaboratory,CenterforRoboticsandManufacturingSystemsandDepartmentofElectricalEngineering,UniversityofKentucky,Lexington,Kentucky,USAAbstract:Feedbackcontrolofdroplettransferispursuedasasolu

2、tiontoproducesoundweldsingasmetalarcwelding.Inpreviouswork,areal-timevisualsystemhasbeendevelopedtomonitoronlinethedropletsizeandgeometry.Torealizefeedbackcontrolofmetaltransfer,thisstudyaddressesthedynamicprocessofdropletgrowthanddetachment.Thedropletissubjectedtogravitationalforce,elect

3、romagneticforce,plasmadragforceandsurfacetensionforce.Thegeometryofthedropletisdeterminedbytheseforcesthroughthestaticforcebalance.However,theforcesactingonthedropletcontinuouslychangeasthemeltingelectrodewirechangesthedropletgeometry.Becauseofthisinterdependencebetweenthedropletgeometrya

4、ndtheforces,themodelmustbesolveddy-namicallyanditeratively.Anumericalprogramhasbeendevelopedtoacquireitsdynamicnumericalsolution.Hence,thedynamicsofthemetaltransferprocesscanbeunderstoodandsimulated.Cur-rently,thismodelisbeingusedtosimulatetheclosed-loopcontrolledmetaltransferprocessusing

5、dierentadvancedcontroltechnologies.Keywords:gasmetalarcwelding,droplets,numericalanalysis,dynamicsNOTATIONPageometricalcoecientforelectromagneticforcecalculationAcross-sectionalareaofelectrodewire(m2)rwradiusofelectrodewire(m)ApprojectedareaofdropletontheplaneRmaximumradiusofthecross-sect

6、ionperpendiculartogas¯ow(m2)perpendiculartothependentdropletaxis(m)bradiusofcurvatureofpendentdropletatR1;R2principalradiiofcurvatureondropletpro®lezz0(m)(m)Cddragcoecientttime(s)pendentdropletvolume(m3)Fdplasmadragforce(N)Fgravitationalforce(N)_volumetricmeltingrateofelectrodewire(m3/s)g

7、Fmelectromagneticforce(N)dvelocityofgas¯ow(m/s)Fssurfacetensionforce(N)x;zcoordinates(m)ggravitationalacceleration(m/s2)02anglebetweenthenormalandsymmetricaxisgeectiveacceleration(m/s)ofdropletIelectriccurrent(A)acoecientofdropletgeometryLelectrodeextension(m)surfac