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Themaincomponentoftheelectricweldingmachineisastep-downtransformer,andthetwoendsofthesecondarycoilareWeldtheworkpieceandtheelectrode,ignitethearcwhenworking,andweldtheelectrodeinthegapoftheworkpieceinthehightemperatureofthearc.Becausetheironcoreoftheelectricweldingtransformerhasitsowncharacteristics,ithasthecharacteristicofasharpdropinvoltage,thatis,thevoltagedropsaftertheelectrodeisignited;whentheelectrodeisshort-circuitedbyadhesion,thevoltagedropssharply.
Duringtheweldingoperation,althoughthecurrentinthecircuitisthesameeverywhere,becausetheresistanceisdifferenteverywhere,theresistanceattheunfixedcontactisthelargest(thisresistanceiscalledthecontactresistance),accordingtothelawofthermaleffectofthecurrent(AlsocalledJoule'slaw),thatis,Q=IR.tcanbeseen:whenthecurrentisequal,thegreatertheresistance,thehighertheheat.Therefore,duringwelding,thecontactresistanceoftheelectrodecontact,thatis,thecontactoftheconnectedmetalbody,isthelargest,andtheelectricheatgeneratedinthispartisnaturallyInaddition,theweldingrodisanalloywithalowermeltingpoint,whichisnaturallyeasytomelt.Themoltenalloyelectrodecoreisbondedtotheobjecttobewelded,andaftercooling,theweldingobjectisbondedtogether.
Generally,thepaneloftheDCinverterweldingmachineisequippedwithanoutputDCcurrentadjustmentknob.InverterDCweldingmachinefirstbridgerectificationandfilteringofsingle-phaseAC220Vvoltageorthree-phaseAC380Vvoltage,andthensupplypowerswitchingdevicesforinverterprocessing.