电焊小知识Little knowledge of welding.docx

电焊小知识Little knowledge of welding.docx

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电焊小知识Littleknowledgeofwelding

电焊小知识（Littleknowledgeofwelding）

OnesideddoublesidedformingweldingprocessforCO2gasshieldedweldingofweldedpipe

Abstract:

ThispapermainlyintroducestheShiHankeyweldingtechnology,pipeCO2weldingofweldingspecification,andthenecessarytestdata,theweldingprocessisfeasible,economicandreliable,forthefuturesimilarweldingprovidesreference.

Keywords:

CO2gasshieldedwelding;single-sidedwelding;doublesidedforming;weldingprocess

0Introduction

Onesideweldingdoublesidedformingweldingprocessofweldedpipeistorealizesinglesideweldingatthegapofthejointbycontrollingtheoperationofmoltenpoolmetal.Whenweldingwitharcstabilityofliquidmetalpoolalongthefrontlinealongthelineaftermelting,crystallization,hightemperaturemoltenpoolinasuspendedstate.

100%CO2gasshieldedweldingisadopted.Theweldingseamisdeepandtheweldingseamisbeautiful.Itiseasytoweldononesideanddoublesided.

Theweldingprocessofsinglesidedweldingofweldedpipeisofgoodquality,fastweldingspeed,savingweldingmaterial,andthequalityofweldsiseasytoreachtherequirementofqualityofflawdetection.

1processcharacteristics

Themainfactorsthataffectthetimeoftheweldpoolandthegeometryoftheweldpoolarethethermophysicalproperties,grooveangle,size,weldingmethodandweldingspecificationsofthemetaltobewelded.Assumingthethermophysicalpropertiesofthebasicmetal,theangleandsizeofthegroovearefixed,thetimeoftheweldpoolandthegeometryoftheweldpoolcanbeexpressedinalowerform:

T=M/V=UIJS/V

ThetimeoftheT-moltenpool,s;

S-coefficientofheatdissipation;

V-weldingspeed,mm/s;

U-arcvoltage,V;

I-weldingcurrent,A;

J-geometrycoefficientofmoltenpool,mm;

M-weldpoolgeometryequivalentouterdiameter,mm.

Ascanbeseenfromtheabove,CO2gasshieldedweldinghastheadvantagesofsinglesideweldinganddoublesidedforming.

ThearcheatconcentrationofCO2gasshieldedweldingissmaller,theheatingareaissmaller,andthemoltenpoolgeometryissmallerthanthatofmanualarcweldingandsubmergedarcwelding,whichisbeneficialtothecontrolofmoltenpoolwelding.

CO2gasshieldedweldinghasalargecurrentdensityandcanreachasufficientpenetrationdepth.Becauseofthesmallervolumeandfasterweldingspeed,

UnderthecoolingofCO2airflow,theresidencetimeofmoltenpoolisshort,soitisbeneficialtocontroltheweldingpoolnottodropandtoweld.

CO2gasshieldedweldingslagisless,thevisibilityofthemoltenpoolisgood,easytodirectlyobservetheshapeofthemoltenpool,theweldercanaccordingtothesizeoftheholetocontroltheweldtoensureweldweldingspeedandswing,easyoperationandhighefficiency.

2processpreparation

2.1grooveformandassembly

CO2gasshieldedweldinghasstrictrequirementsongrooveformandassembly.Thegroovetypeanddimensionofthebuttweldincludeangle,bluntedgeandassemblygap.

Theangleofthegroovemainlyaffectswhetherthearccanpenetrateintotherootoftheweld,andtherootiswellwelded.Thus,betterweldformingandweldingqualitycanbeobtained.Toensurethatthearccanpenetrateintotherootoftheweld,theangleofthegrooveshouldbeminimized.

Thesizeofthebluntedgecandirectlyaffectthepenetrationdepthoftheroot,andthegreaterthebluntedge,thelesslikelyitistoweldthrough.Bluntedge,smallorwithoutbluntedge,easytoweldthrough,buttheassemblygapislarge,itiseasytoburnthrough.

Theassemblygapisthekeyparameterfortheformationofthebackweld.Thegapistoolargetoburnthrough.Thegapistoosmalltobewelded.

AH08Mn2Siwirewithadiameterof1.2mmisused.Backweldformingonesideweldingdroplettransferformforshortcircuiting,usuallywithasmallerbluntedgecannotevenleaveabluntedge,theassemblyclearanceis2~4mm,thegrooveangleonthebasisofGB9851988"gaswelding,manualarcweldingandgasweldingseambasedontheformandsize."thestandardVgroove,grooveangleat60degrees-5degreestoimprovetheprecisionandqualityofweldinggroove,playedaverygoodrole.

Attentiontotheweatherduringwelding,especiallyprecautionsmustbedoneinplace.

2.2selectionofweldingcurrent

Theweldingcurrentisthemainfactortodeterminethepenetrationdepth,whentheweldingcurrentistoolarge,itiseasytoburn,backweldundercut,andevencauseseriousspatterandporosityandotherdefects;smallcurrent,pronetoincompletefusion,lackofpenetration,slagandotherdefectsformingisnotgood.Thetestshowsthatwhenthediameteris1.2mmwire,theweldingcurrentofonefaceweldingdoublefaceformingis85~100A,whichissuitable.Therefore,theweldingcurrent