焊接和清洗.焊接外文翻译Word文件下载.docx

焊接和清洗.焊接外文翻译Word文件下载.docx

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impossibletonameanindustry, 

largeorsmall, 

thatdoesnotemployistypeofwelding.Industryhasfoundthatwelding 

isanefficient, 

dependable, 

andeconomicalmeansofjoiningmetalinpracticallyallmetalfabricatingoperationsandinmostconstruction.

WhereWeldingIsUsed

Intooling-upforanewmodelautomobile,amanufacturermayspendupwardofamilliondollarsonweldingequipment. 

Manybuildings,bridges,andshipsarefabricatedbywelding.Whereconstructionnoisemustbekeptataminimum,suchasinthebuildingofhospitaladditions,thevalueofweldingasthechiefmeansofjoiningsteelsectionsisparticularlysignificant.

Withoutwelding,theaircraftindustrieswouldneverbeabletomeettheenormousdemandsforplanes,rockets,andmissiles.Rapidprogressinthespaceprogram,hasbeenmadepossiblebynewmethodsandknowledgeofweldingmetallurgy.

Probablythemostsizablecontributionweldinghasmadetosocietyisthemanufactureofspecialproductsforhouseholduse.Weldingprocessesareemployedintheconstructionofsuchitemsastelevisionsets,refrigerators,kitchencabinets,dishwashers,andothersimilarproducts.

Asameansoffabrication,weldinghasprovedfast,dependable,andflexible.Itlowersproductioncostsbysimplifyingdesignandeliminatescostlypatternsandmachiningoperations.

Weldingisusedextensivelyforthemanufactureandrepairoffarmequipment,miningandoilmachinery,machinetools,jigsandfixtures,andintheconstructionofboilers,furnaces,andrailwaycars.Withimprovedtechniquesforaddingnewmetaltowornparts,weldinghasalsoresultedineconomyforhighlycompetitiveindustries.

TypesofWeldingProcesses

Ofthemanyprocessesofweldinginusetoday,oxy-fuelgaswelding,arc,andresistancedominatethefield.Theseprocessesarebestexplainedformthestandpointoftheoperator’sduties.

Theskillsrequiredforthisjobareadjustmentoftheregulators,selectionofpropertipsrodmanipulation.Thegasweldermayalsobecalledupontodoflamecuttingwithacuttingattachmentandextraoxygenpressure.Flameoroxygencuttingisemployedtocutvariousmetalstoadesiredsizeorshape,ortoremoveexcessmetalfromcastings.

Thetreemaintypesofarcweldingprocessesusedtodayareshieldedmetal-arcwelding,gastungsten-arcwelding,andgasmetal-arcwelding.Shieldingmetal-arcweldersperformtheirskillbyfirststrikinganarcatthestartingpointofaweldandmaintainingthiselectricarctofusethemetaljoints.Themoltenmetalfromthetipoftheelectrodeisthendepositedinthejoint,togetherwiththemoltenmetaloftheedges,andsolidifiestoformasoundanduniformconnection.Thearcweldingoperatoris 

expected 

toselecttheproperelectrodesforthejoborbeabletofollowinstructionsasstatedinthejobspecifications,toreadweldingsymbols,andtoweldanytypeofjointusingthetechniquerequired.

Gas-shieldedarcprocesseshavegainedrecognitionasbeingsuperiortothemetalarcprocess.Withgas-shieldedarcboththearcandmoltenpuddlearecoveredbyashieldofinertgas.Theshieldofinertgaspreventsatmosphericcontamination,therebyproducingawelding,sometimescalledTIGandMIG,areeithermanuallyorautomaticallyoperated.

Resistanceweldingoperatorsareresponsibleforthecontrolofmachineswhichfusemetalstogetherbyheatandpressure.Iftwopiecesofmetalareplacedbetweenelectrodesbecauseoftheirownresistance,willbecomeheatedtoaplasticstate.Tocompletetheweld,thecurrentis 

interrupted 

beforepressureisreleased,therebyallowingtheweldmetaltocoolforsolidstrength.

Theoperator’sdutyistoproperlyadjustthemachinecurrent,pressure,andfeedsettingssuitableforthematerialtobewelded.Thewelderusuallywillberesponsibleforthealignmentofpartstobeassembledandforcontrollingthepassageofpartsthroughtheweldingmachine.

SelectionoftheProperWeldingProcess

Therearenohardandfastruleswhichgovernthetypeofweldingthatistobeusedforaparticularjob.Ingeneral,thecontrollingfactorsarekindofmetalstobejoined,costsinvolved,natureofproductstobefabricated,andproductiontechniques.Someweldingjobsarebestcompletedusingtheoxyfuelweldingprocessascomparedtoshieldedmetalarcweldingprocess.

Oxyacetylenewelding,themostpopularoxy-fuelgasweldingprocess,isusedinallmetalworkingindustriesandinthefieldaswellasforplantmaintenance.Becauseofitsflexibilityandmobility,itiswidelyusedinmaintenanceandrepairwork.Theweldingunitcanbemovedonatwo-wheeledcartor 

transported 

bytrucktoanyfieldjobwherebreakdownsoccur