材料成型铸造专业毕业设计英文文献原文

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1、Castinganditsprocesses1.1IntroductionManufacturingprocesscanbeclassifiedintotwogeneralgroupsknownasprimaryandsecondaryprocesses.Theprimaryprocesses,namely,casting,forging,coldheading,coldextruding,brakeforming，andsoon，arethosethatconvertrawmaterialintoshapes.Thesef

2、ormingmethodsincludebothhotandcoldworkingprocessesand，ingeneral，willstillrequirefurtherfinishingoperationsinordertoobtainanendproduct.Thesecondaryprocessesarethosethatbringtheparttothedimensionsandsurfacefinishspecified.Onemayalsoincludeinthesecondaryprocessessucho

3、perationsasheattreatingandsurfacetreatmentsforcorrosionresistance,hardness，andappearance.Secondaryprocessesareplanning，turning，milling，drilling，boring，reaming，broaching，grinding，honingJapping，polishing，andspecialmethodsofmetalremovalsuchaselectrochemicalmachining.O

4、perationslikescrewcutting,tapping，threadmilling,gearcutting，andsoon，aresecondaryprocessesthataremerelyadaptationsofoneoftheaforementionedprocessesthataremerelyadaptionofoneoftheaforementionedprocesses.Acompletediscussionoftheseproceduresisbeyondthescopeofthistext.T

5、herefore，wewillconfineourselvestosuccinctdescriptionsofthemostprominenttechniques.1.2CastingsCastingsareidentifiedbythetypeofmoldortheforcerequiredtoyfillthemold.Moldsareeitherpermanentorexpendable.Thepatternofsand，shell,andplastermolds，however，canbeusedrepeatedlyf

6、ormakingnewmolds.Asthemetalcools，ittakestheshapeofthecavity.Thebasiccastingmethodsaredescribedbelow.Sandcastings，LThegreensandprocessisoneinwhichmost,bondedsandspackedaroundawoodormetalpattern.Thepatternisthenremovedandmoltenmetalispouredintothecavity.Whenthemetals

7、olidifies，themoldisbrokenandthecastingisremoved.Almostanymetalcanbeused，withvirtuallynolimitastothesizeorshapeofthepart.Themethodpermitscastingcomplexcomponentsatalowtoolingcostandisthemostdirectroutefrompatterntocasting.Somemachiningisalwaysnecessarywiththegreensa

8、ndprocess，andlargecastingshaveroughsurfacefinish.Closetolerancesaredifficulttoachieve,andlong,thinprojectionsshouldnotbecast.Itispossible，however