铸造的概念及特点

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1、FundamentalofMaterialsForming-CastingbasicconceptMaincontents1、铸造的概念及特点、铸造技术的发展；FundamentalsofMetal-Casting2、金属铸造工艺Metal-CastingProcesses砂型铸造及其工艺设计；特种铸造及其工艺；3、铸件的结构设计、材料及经济性MetalCasting:Design,Materials,andEconomics5、先进铸造技术。AdvancedCastingSandCastingSandCastingprocessTheconceptforCastingSchematicil

2、lustrationofatypicalriser-gatedcasting.Risersserveasreservoirs,supplyingmoltenmetaltothecastingasitshrinksduringsolidification.SeealsoFig.11.4Source:AmericanFoundrymen’sSociety.WhySandCasting?Inmetalcastingwork,aswithalmosteverykindofmanufacture,highprecisionmeanshighcost.Inacasewearemakingasmallnu

3、mberofobjectssowecan'treallyaffordtomakeasophisticatedmetalmold(i.e.wecan'tdodiecasting).Theusualapproachinthiscaseistomakedisposablemoldsoutofsandorplaster.Thekindofdisposablemold,andthetechniquesusedtomakethemold,areagaindeterminedbyquestionsofcostandquality.Foraveryintricate,preciseresult,lostw

4、axorlostpolystyrenefoamcastingisused.Forlessintricateworkpieces,orlowerprecisionrequirements,directsandcastingcanbeadequate.WhatisSandCasting?Allcasting,notjustsandcasting,isaboutpouringorsquirtingamoltensubstanceintoacavity.Allcastingmethodsrequiretwobasicthings:Acavitywhichistheshapeofthedesired

5、finalobject,andAwaytoputmoltensubstanceintothecavity.Inthesandcastingprocess,thecavityismadeofsandwhichisheldtogetherbyabinder(asubstancethatholdsthesandgrainstogether).Sandcastingisusedtoproduceawidevarietyofmetalcomponentswithcomplexgeometries.Thesepartscanvarygreatlyinsizeandweight,rangingfroma

6、coupleouncestoseveraltons.Somesmallersandcastpartsincludecomponentsasgears,pulleys,crankshafts,connectingrods,andpropellers.Largerapplicationsincludehousingsforlargeequipmentandheavymachinebases.Sandcastingisalsocommoninproducingautomobilecomponents,suchasengineblocks,enginemanifolds,cylinderheads,

7、andtransmissioncases.Die-CastingExamples(a)(b)Figure11.1(a)ThePolaroidPDC-2000digitalcamerawithaAZ91Ddie-cast,highpuritymagnesiumcase.(b)Two-piecePolaroidcameracasemadebythehot-chamberdiecastingprocess.Sour