制造工程与技术(热加工)英文版joining-processes-and-equipment(1)

成型技术基础ManufacturingEngineeringandTechnology--HotProcesses制造工程与技术(热加工)•制造•冷加工与热加工特点•热加工：Casting铸、Forming锻、Welding焊、HeatProcessing热处理张大童、曹彪、黄珍媛PartⅤJoiningProcessesandEquipmentJoining:Connectpartstogether.Joiningisanall-inclusiveterm(总称），coveringprocessessuchaswelding,brazing,soldering,adhesivebonding（胶接）,andmechanicalfastening.GivesomeexamplesofJoiningProcessesyouknown.Whyjoiningprocesses?Withoutjoining,therewouldnotbemodernindustry.BecauseproductsorpartswouldbeImpossibletomanufactureExpensiveDifficulttomaintenanceHardtogetdifferentpropertiesDifficulttotransportationjoiningprocessesclassificationSeeFig.V.3Whatdifferencebetweenweldingandadhesivebonding,ormechanicalfastening?AdhesivebondingMechanicalfasteningJoiningProcessesweldingFusionBrazingandsolderingSolidstateChemicalElectricalElectricalChemicalMechanicalProcessselection:which’spreferred,whichnot?TABLEV.1MethodStrengthDesignVariabilitySmallPartsLargePartsTolerancesReliabilityEaseofmaintenanceVisualinspectionCostArcWelding123131222ResistanceWelding121133331Brazing111131323BoltsandNuts123121113Riveting123111312Fasteners233122213Seaming,Crimping221331311AdhesiveBonding311232332Note:1,Verygood;2,good;3.Poor长征二号丙火箭8月发射卫星失利故障原因：二级飞行段二级游机Ⅲ分机与伺服机构连接部位失效造成，因为连接部位的可靠性存在薄弱环节。ThechoiceofajoiningprocessdependsonTheapplicationThejointdesignThematerialsinvolvedTheshapesofthecomponentstobejoined,theirthicknesses,andtheirsizesOthers:thelocationofthejointwithintheproduct,componentnumbers,theoperatorskillrequired,costsandsoon.吴林教授：1.制造技术的三个基本功能：成形、连接、改性；2.古代焊接起源于中国，现代焊接发展于西方；3.焊接已经逐渐从技术走向科学。三种焊接原理还没有形成一个统一的科学理论；宏观、细观、界观、微观；还有若干自然现象：太空环境下材料的粘连，冰和肌肉的粘连等；各种新材料的连接，特别是陶瓷、高温材料、碳纤维、复合材料、异种材料等的连接问题有待于实现和发展。——焊接的问题基本上是一个材料界面的科学问题手艺技术科学§27Fusion-WeldingProcesses熔焊weldingFusionBrazingandsolderingSolidstateChemicalElectricalElectricalChemicalMechanicalShieldedMetal-ArcSubmergedArcPlasmaArcGasMetal-ArcFlux-CoredArcGasTungsten-ArcElectron-BeamLaser-BeamElectro-gasElectro-slagAtomicHydrogenetalTopicstoDiscuss•Introduction•OxyfuelGaswelding•Arc-WeldingProcesses:Consumableelectrode•Electrodes•Arc-WeldingProcesses:NonConsumableProcess•ThermitWelding•ElectronBeamWelding•LaserBeamWelding•Cutting•WeldingSafety27.1IntroductionFusionwelding:Itisdefinedasthemeltingtogetherandcoalescingofmaterialsbymeansofheat.Heat(energy)isusuallysuppliedbychemicalorelectricalmeans.Fillermetals（填充金属）mayormaynotbeused.Fillermetals:Metalsaddedtotheweldareaduringwelding.Autogenousweld（自熔焊缝）:FusionweldsmadewithouttheadditionoffillermetalsBasicprinciplesofeachprocessEquipmentAdvantagesandlimitationsCapabilitiesGeneralCharacteristicsofFusionWeldingProcessesTABLE27.1JoiningprocessOperationAdvantageSkilllevelrequiredWeldingpositionCurrenttypeDistortion*CostofequipmentShieldedmetal-arcManualPortableandflexibleHighAllac,dc1to2LowSubmergedarcAutomaticHighdepositionLowtomediumFlatandhorizontalac,dc1to2MediumGasmetal-arcSemiautomaticorautomaticMostmetalsLowtohighAlldc2to3MediumtohighGastungsten-arcManualorautomaticMostmetalsLowtohighAllac,dc2to3MediumFlux-coredarcSemiautomaticorautomaticHighdepositionLowtohighAlldc1to3MediumOxyfuelManualPortableandflexibleHighAll—2to4LowElectron-beam,Laser-beamSemiautomaticorautomaticMostmetalsMediumtohighAll—3to5High*1,highest;5,lowest.27.2OxyfuelGasWelding—OFW气焊，氧乙炔焊weldingFusionBrazingandsolderingSolidstateChemicalElectricalElectricalChemicalMechanicalOxyfuelgasThermit1.OxyfuelGasWelding（氧燃气焊接，气焊）:Ageneraltermusedtodescribeanyweldingprocessthatusesafuelgascombinedwithoxygentoproduceaflame,whichisthesourceoftheheatthatisusedtomeltthemetalsatthejoint.2.Oxyacetylenewelding（氧乙炔焊）:Theprocessutilizestheheatgeneratedbythecombustionofacetylenegas(C2H2)inamixturewithoxygen.C2H2+O2→2CO+H2+heat(1/3ofthetotal)2CO+H2+1.5O2→2CO2+H2O+heat(2/3)Otherfuelgases??27.2.1TypesofflamesNeutralflame(中性焰）:Theratioofacetyleneandoxygenis1:1.It’swidelyusedforOFWofmostmaterials.Oxidizingflame（氧化焰）:Theratioissmallerthan1.It’sharmfulforsteelwelding,itcanbeusedfortheweldingofcopperandcopper-basedalloys.Reducingorcarburizingflame（还原焰或碳化焰）:Theratioisbiggerthan1.It’sforbrazing,soldering,andflame-hardeningbecauseofitslowertemperature27.2.2FillerMetals(填充金属）andFlux（焊剂）Fillermetalsareusedtosupplyadditionalmaterialtotheweldzoneduringwelding.Theyareavailableasrodorwiremadeofmetalscompatiblewiththosetobewelded.Theseconsumablefillerrodsmaybebare,ortheymaybecoatedwithflux.Thepurposeoftheflux:①toremoveoxidesfromthesurfaces②togenerategaseousandslagshield③totakepartinthemetallurgicalreactions27.2.3WeldingpracticeandEquipmentWeldingTorch（焊炬）EquipmentOperation①Preparetheedgestobejoined,andestablishandmaintaintheirproperpositionbytheuseofclampsandfixtures;②Opentheacetylenevalve,andignitethegasatthetipofthetorch.Opentheoxygenvalve,andadjusttheflamefortheparticularoperation;③Position:Holdthetorchatabout450fromtheplaneoftheworkpiece,withtheinnerflameneartheworkpieceandthefillerrodatabout300-400;④Speed:Touchthefillerrodtothejointandcontrolitsmovementalongthejointlengthbyobservingtherateofmeltingandfillingofthejoint.Safety①Co