河南科技大学焊接专业英语试卷范围.doc

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1、ShieldedMetalArcWelding(SMAW)屏蔽金属电弧焊接(SMAW)Shieldedmetalarcweldingprocessshowninfigure3.3Jsalsoknownasmanualmetalarcwelding(MMA)inEurope.Ithasformanyyearsbeenoneofthemostcommontechniquesappliedtothefabricationofsteels.theprocessusesanarcastheheatsourceandshieldingisprovidedbygasesgeneratedbyth

2、edecompositionoftheelectrodecoatingmaterialandbytheslagproducedbythemeltingofmineralconstituentsofthecoating.InadditiontoheatingandmeltingtheparentmaterialthearcalsomeltsthecoreoftheelectrodeandtherebyprovidesfillermaterialforthejointTheelectrodecoatingmayalsobeusesasasourceofalloyingelementsa

3、ndadditionalfillermaterial.Thefluxandelectrodechemistrymaybeformulatedtodepositwearandcorrosion-resistantlayersforsurfaceprotect!on。Significantfeaturesoftheprocessare:1equipmentrequirementsaresimple2alargerangeofconsumablesareavailable3theprocessisextremelyportable4theoperatingefficiencyislow5

4、itislabourintensiveForthesereasonstheprocesshasbeentraditionallyusedinstructuralsteelfabrication,shipbuildingandheavyengineeringaswellasforsmallbatchproduct!onandmaintenance・)屏蔽金属电弧焊接过程如图33所示在欧洲也称为手工电弧焊，它作为一种最常见的技术在钢的制造中应用很多年。在焊接过程中工，电弧提供热源，焊条表面涂层(即药皮)和焊渣中的矿物质分解产生的气体提供保护。除了使焊芯融化外，电弧也使母材融化。从而为结

5、头提供填充金属，药皮也可以作为合金元素和填充物的来源。焊剂在焊件表面发生电化学反应形成耐腐蚀的沉淀层。焊接过程的显著特征1设备要求简单。2焊接范围广，3焊接过程简单。4操作效率低。5劳动力用量大。由于这些原因，这种焊接过程用于钢结构制造，造船，重型工程，小批量生产和维护方面。3・1.2.5Flux-coredWireWelding(FCAW)Flux-corewiresconsistofametaloutersheathfilledwithacombinationofmineralfluxtrndmetcilpowders,asshowninFigure3.10.theECAWpr

6、ocessisoperatedinasimilarmannertoGMAWweldingandtheprincipleisillustratedinFigure3・11.lhemostcommonproductiontechniqueusedtoproducethewireinvoIvesfoldingathinmetalstriplechniqueusedtoproducethewireinvolvesfoldingathinmetalstripintoaUshape,fillingitwiththefluxconstituents,closin呂theUtoformacircu

7、larsectionandreducingthediameterofthetubebydrawingorrollinyAlternativeconfigurations,showninFigure3・12,maybeproducedbylappingorfoldingthestriportheconsumablemtiybemadebyfillingatubewithfluxfollowedbyadrtiwingoperationtoreducethediameter