中英文翻譯--銑削.doc

本科畢業(yè)論文（設計）相關中英文翻譯資料資料題目：銑削學生姓名：所在院系：機電學院所學專業(yè)：機電技術教育MILLINGMillingisabasicmachiningprocessinwhichthesurfaceisgeneratedbytheprogressiveformationandremovalofchipsofmaterialfromtheworkpieceasitisfedtoarotatingcutterinadirectionperpendiculartotheaxisofthecutter.Insomecasestheworkpieceisstationaryandthecutterisfedtothework.Inmostinstancesamultiple-toothcutterisusedsothatthemetalremovalrateishigh,andfrequentlythedesiredsurfaceisobtainedinasinglepassofthework.Thetoolusedinmillingisknownasamillingcutter.Itusuallyconsistsofacylindricalbodywhichrotatesonitsaxisandcontainsequallyspacedperipheralteeththatintermittentlyengageandcuttheworkpiece.1InsomecasestheteethextendpartwayacrossoneorbothEndsofthecylinder.Becausethemillingprincipleprovidesrapidmetalremovalandcanproducegoodsurfacefinish,itisparticularlywell-suitedformass-productionwork,andexcellentmillingmachineshavebeendevelopedforthispurpose.However,veryaccurateandversatilemillingMachinesofageneral-purposenaturealsohavebeendevelopedthatarewidelyusedinjobshopandtoolanddiework.Ashopthatisequippedwithamillingmachineandanenginelathecanmachinealmostanytypeofproductofsuitablesize.TypesofMillingOperations.Millingoperationscanbeclassifiedintotwobroadcategories,eachofwhichhasseveralvariations:1.Inperipheralmillingasurfaceisgeneratedbyteethlocatedintheperipheryofthecutterbody；thesurfaceisparallelwiththeaxisofrotationofthecutter.Bothflatandformedsurfacescanbeproducedbythismethod.Thecrosssectionoftheresultingsurfacecorrespondstotheaxialcontourofthecutter.Thisprocedureofteniscalledslabmilling.2.Infacemillingthegeneratedflatsurfaceisatrightanglestothecutteraxisandisthecombinedresultoftheactionsoftheportionsoftheteethlocatedonboththeperipheryandthefaceofthecutter.2Themajorportionofthecuttingisdonebytheperipheralportionsoftheteethwiththefaceportionsprovidingafinishingaction.ThebasicconceptsofperipheralandfacemillingareillustratedinFig.16-1.Peripheralmillingoperationsusuallyareperformedonmachineshavinghorizontalspindles,whereasfacemillingisdoneonbothhorizontal-andvertical-spindlemachines.SurfaceGenerationinMimng.SurfacescanbegeneratedinmillingbytwodistinctlydifferentmethodsdepictedinFig.16-2.Notethatinupmillingthecutterrotatesagainsithedirectionoffeedtheworkpiece,whereasindownmillingtherotationisinthesamedirectionasthefeed.AsshowninFig.16-2,themethodofchipformationisquitedifferentinthetwocases.Inupmillingthechipisverythinatthebeginning,wherethetoothfirstcontactsthework,andincreasesinthickness,becomingamaximumwherethetoothleavesthework.ThecuttertendstopushtheworkalongandliftitupwardfromTool-workrelationshiosinperipheralandfacemillingthetable.Thisactiontendstoeliminateanyeffectofloosenessinthefeedscrewandnutofthemillingmachinetableandresultsinasmoothcut.However,theactionalsotendstoloosentheworkfromtheclampingdevicesothatgreaterclampingforcersmustbeemployed.Inaddition,thesmoothnessofthegeneratedsurfacedependsgreatlyonthesharpnessofthecuttingedges.Indownmilling,maximumchipthicknesscecumclosetothepointatwhichthetoothcontactsthework.Becausetherelativemotiontendstopulltheworkpieceintothecutter,allpossibilityofloosenessinthetablefeedscrewmustbeeliminatedifdownmillingistobeused.Itshouldneverbeattemptedonmachinesthatarenotdesignedforthistypeofmilling.Inasmushasthematerialyieldsinapproximatelyatangentialdirectionattheendofthetoothengagement,thereismuchlesstendencyforthemachinedsurfacetoshowtoothmarksthanwhenupmillingisused.Anotherconsiderableadvantageofdownmillingisthatthecuttingforcetendstoholdtheworkagainstthemachinetable,permittinglowerclampingforcetobeemployed.3Thisisparticularlyadvantageouswhenmillingthinworkpieceorwhentakingheavycuts.Sometimesadisadvantageofdownmillingisthatthecutterteethstrikeagainstthesurfaceoftheworkatthebeginningofeachchip.Whentheworkpiecehasahardsurface,suchascastingsdo,thismaycausetheteethtodullrapidly.MillingCutters.Millingcutterscanbeclassifiedseveralways.Onemethodistogroupthemintotwobroadclasses,basedontoothrelief,asfollows:1.Profile-cuttershavereliefprovidedoneachtoothbygrindingasmalllandbackofthecuttingedge.Thecuttingedgemaybestraightorcurved.2.Informorcam-rehevedcuttersthecrosssectionofeachtoothisaneccentriccurvebehindthecuttingedge,thusprovidingrelief.Allsectionsoftheeccentricrelief,parallelwiththecuttingedge,musthavethesamecontourasthecuttingedge.Cuttersofthistypearesharpenedbygrindingonlythefaceoftheteeth,withthecontourofthecuttingedgethusremainingunchanged.Anotherusefulmethodofclassificationisaccordingtothemethodofmountingthecutter.Arborcuttersarethosethathaveacenterholesotheycanbemountedonanarbor.Shankcuttershaveeithertaperedorstraightintegralshank.Thosewithtaperedshankscanbemounteddirectlyinthemillingmachinespindle,whereasstraight-shankcuttersareheldinachuck.Facingcuttersusuallyareboltedtotheendofastubarbor.Thecommontypesofmillingcutters,classifiedbythissystemareasfollows:TypesofMillingCutters.Hainmillingcuttersarecylindricalordisk-shaped,havingstraightorhelicalteethontheperiphery.Theyareusedformillingflatsurfaces.Thistypeofoperationiscalledplainorslabmilling.Eachtoothinahelicalcutterengagestheworkgradually,andusuallymorethanonetoothcutsatagiventime.Thisreducesshockandchatteringtendenciesandpromotesasmoothersurface.Consequently,thistypeofcutterusuallyispreferredoveronewithstraightteeth.Sidemillingcuttersaresimilartoplainmillingcuttersexceptthattheteethextendradiallypartwayacrossoneorbothendsofthecylindertowardthe:center.Theteethmaybeeitherstraightorhelical.Frequentlythesecuttersarerelativelynarrow,beingdisklikeinshape.Twoormoresidemillingcuttersoftenarespacedonanarbortomakesimultaneous,parallelcuts,inanoperationcalledstraddlemilling.Interlockingslottingcuttersconsistoftwocutterssimilartosidemills,butmadetooperateasaunitformillingslots.Thetwocuttersareadjust