Metal-casting-铸造ppt课件

1.Metalcasting,1.1Conceptofcasting1.2Castingprocess1.3Fluidflow1.4Castingdefects1.5Sandcasting1.6Investmentcasting1.7Foundryandautomation,Pleaserefertochapters10and11,Metalcasting-keywords,CastingMoldGrainFluiditySandcasting/diecastingInvestmentcastingFoundryPattern/core/porosity/shrinkage,1.1Conceptofcasting,Casting:processwhichinvolvespouringmoltenmetalintoamoldcavity,thenobtainstheshapeofthecavity.,1.1Conceptofcasting,Advantages:ComplexshapeswithinternalcavitiesorhollowsectionsVerylargepartsAlmostallmetals,suitableforworkpiecematerialsdifficulttoprocessbyothermeansCompetitivewithotherprocesses,1.1Conceptofcasting,Applications:Manypartsandcomponents,forexamples,1.1Conceptofcasting,Trends:MechanizationandautomationofthecastingprocessIncreasingdemandforhigh-qualitycastingswithclosedimensionaltolerancesandnodefects,1.2Castingprocess,Castingprocess:Pouringmoltenmetalintoamoldpatternedaftertheparttobemanufactured;Allowingittocool;Removingthemetalfromthemold.,1.2Castingprocess,Solidificationsofmetals:PuremetalsAlloys,1.2Castingprocess,Influenceofgrainsizeoncastingproperties:Strengthductilitymicro-porositytendencyforthecastingtocrack.,1.3Fluidflow,Castingsystem,1.3Fluidflow,Fluidity:thecapabilityofthemoltenmetaltofillmoldcavities.Influencefactorsoffluidity（1）Characteristicsofthemoltenmetal（2）Castingparameterspage249fordetailCastability:theeasewithametalcanbecasttoobtainapartwithgoodquality.Testmethodforcastability：,1.4Castingdefects,Maininfluencefactors:Materials,partdesign,processingtechniquesSevencategories:（1）metallicprojections（2）cavities-porosity（3）discontinuities(4)defectivesurface(5)Incompletecasting(6)Incorrectdimensionorshape(7)Inclusions,1.4Castingdefects,SeeFig.10.11,1.4Castingdefects,Porosity:maybecausedbyshrinkageorgasesorboth.Methodstoreduceoreliminateporosityavoidcavitiesbyshrinkage(1)Adequateliquidmetal(2)Internalorexternalchills,1.4Castingdefects,Readingprogram:P.256,example.,1.5Sandcasting,Advantagesandlimitations:-SeeTable11.1,(P.8);Table11.2,(P.9)Processofsandcasting:(1)Placeapatternhavingtheshapeofthedesiredcastinginsandtomakeanimprint;(2)Incorporatingagatingsystem(3)Fillingtheresultingcavitywithmoltenmetal(4)Allowingthemetaltocooluntilitsolidifies(5)Breakingawaythesandmold(6)Removethecasting,1.5Sandcasting,1.5Sandcasting,Whysandisusedforcasting?readingSeeP.264Componentsofsandmoldsandtheirfunctions:(1)Flask-copeanddrag;(2)Pouringbasin(3)Sprue(4)Runningsystem(5)Riser(6)Core(7)Vent,1.5Sandcasting,Patterns:areusedtomoldthesandmixtureintotheshapeofthecasting.patternmaterials:Table11.3,SeeP.267,1.5Sandcasting,Cores:Forcastingwithinternalcavitiesorpassages,coresareused.Coreareplacedinthemoldcavitybeforecastingtoformtheinteriorsurfacesofthecastingandremovalfromthefinishedpartduringshakeoutandfurtherprocessing.,1.5Sandcasting,Sand-operation:p.271,1.6Investmentcasting,Homework-questions：Statethesequencesofinvestmentcastingoperation.Explainthemeaningof“investment”.Intheoperationof“patternmeltout”,moldisfiredto650-1050Cfor4hours,why?Describetheadvantagesandlimitationsofinvestmentcasting,1.7Foundryandautomation,Advantagesoffoundryautomation:Widevarietyandsizesofcastingathighproduction,atlowcost,andwithgoodqualitycontrol.Twogroupsofcastingactivities:1.Patternandmoldmaking-CAD,CAM,RPM2.Meltingtheme