精品机床加工外文文献翻译.docx
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精品机床加工外文文献翻译.docx
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精品机床加工外文文献翻译
【关键字】精品
机床加工外文文献翻译
(含:
英文原文及中文译文)
文献出处:
ShunmugamM.BasicMachiningOperationsandCuttingTechnology[J].JournaloftheInstitutionofEngineers,2014,1
(2):
22-32.
英文原文
BasicMachiningOperationsandCuttingTechnology
ShunmugamM
BasicMachiningOperations
MachinewasdevelopedfromtheearlyEgyptianpedalcarandJohnWilkinson'strampoline.Theyproviderigidsupportforworkpiecesandtoolsandcanpreciselycontroltheirrelativepositionandrelativespeed.Basically,metalcuttingreferstoasharpenedprytoolthatremovesaverynarrowmetalfromthesurfaceofatoughworkpiece.Chipsarediscardedproducts.Comparedwithotherworkpieces,thechipsareshorter,butthereisacertainincreaseinthethicknessoftheuncutparts.Thegeometryoftheworkpiecesurfacedependsontheshapeofthetoolandthepathofthetoolduringmachiningoperations.
Mostmachiningprocessesproducepartsofdifferentgeometries.Ifaroughworkpiecerotatesonthecentralaxisandthetoolcutsintotheworkpiecesurfaceparalleltothecenterofrotation,arotatingsurfaceiscreated.Thisoperationiscalledturning.Ifahollowtubeismachinedontheinnersurfaceinthesameway,thisoperationiscalledboring.Whenthediameterisevenlychanged,aconicaloutersurfaceisproduced,whichiscalledtaperturning.Ifthetoolcontactpointmovesinawaythatchangestheradius,thenaworkpiecewithacontourlikeaballisproduced;oriftheworkpieceisshortenoughandthesupportisveryrigid,thentheformingtoolnormallyfeedsoneoutsidetheaxisofrotation.Surfacescanbeproduced,andshorttaperedorcylindricalsurfacescanalsobeformed.
Flatsurfacesareoftenrequiredandtheycanbeproducedbyradialturningoftoolcontactpointswithrespecttotheaxisofrotation.Itiseasiertofixthetoolandplacetheworkpieceunderthetoolforlargerworkpieceswhileplaning.Thetoolcanfeedreciprocally.Theformingsurfacecanbeproducedbyaformingtool.
Multi-bladecutterscanalsobeused.Usingadouble-edgedgroovedrillingdepthis5-10timestheholediameter.Regardlessofwhetherthedrillrotatesortheworkpiecerotates,therelativemotionbetweenthecuttingedgeandtheworkpieceisanimportantfactor.Duringmilling,arotatingtoolwithmanycuttingedgescomesintocontactwiththeworkpieceandtheworkpieceslowlymovesrelativetothetool.Flatorshapedsurfacesmayoccurdependingonthetoolgeometryandfeedmethod.Ahorizontalorverticalaxisrotationcanbegeneratedandcanbefedinanyofthreecoordinatedirections.
Basicmachine
Themachinetoolproducespartswithspecialgeometryandprecisedimensionsbyremovingchipsfromplasticmaterial.Thelatteriswaste,whichisachangefromthelongcontinuousstripofplasticmaterialsuchassteel,whichisuselessfromaprocessingpointofview.Itiseasytohandlecrackedchipsproducedfromcastiron.Themachineperformsfivebasicmetalremovalprocesses:
turning,planing,drilling,andmilling.Allothermetalremovalprocessesaremodifiedfromthesefivebasicprocedures.Forexample,boringisinternalturning;reaming,tappingandcounterboringarefurthermachiningofdrilledholes;gearmachiningisbasedonMillingoperation.Polishingandsandingaredeformationsthatgrindandremovetheabrasiveprocess.Therefore,thereareonlyfourbasictypesofmachinetoolsthatusespeciallycontrollablecuttingtools:
1.Lathes,2.Drillingmachines,3.Millingmachines,4.Grindingmachines.Thegrindingprocessformschips,butthegeometryoftheabrasiveparticlesisuncontrollable.
Theamountandspeedofmaterialremovalthroughvariousprocessingstepsisenormous,justashighfacetsareremovedinlargeturningoperations,orinextremelysmallgrindingandultra-precisionmachining.Amachinetoolfulfillsthreemajorfunctions:
1.Itsupportsworkpiecesorfixturesandtools2.Itprovidesrelativemotiontoworkpiecesandtools3.Ineachcaseprovidesarangeoffeedsandgenerallyupto4-32speciesSpeedchoices.
Processingspeedandfeed
Speed,feed,anddepthofcutarethreemajorvariablesineconomicprocessing.Theotherquantitiesaretappingandtoolmaterial,coolantandtoolgeometry.Thespeedofthemetalremovalandthepowerrequiredaredependentonthesevariables.
Depthofcut,feed,andcuttingspeedarethemechanicalparametersthatmustbeestablishedinanymetalworkingprocess.Theyallaffecttheforce,speedandspeedofmetalremoval.Thecuttingspeedcanbedefinedastheradiusofthevelocityrecordingsurfacethatspreadsradiallyatanyinstantduringonerevolution,orthedistancebetweentwoadjacentgrooves.Thedepthofcutisthedepthofentryandthedepthofthetrench.
Turninginthecenterofthelathe
Basicoperationscompletedonamotorizedbedhavebeenintroduced.Thoseoperationsthatuseasinglepointtoolontheoutsidesurfacearecalledturning.Inadditiontodrilling,reaming,andgrindingofinternalsurfaces,theoperationisdonebyasinglepointtool.Allmachiningoperations,includingturning,canbecategorizedasroughing,finishingorsemi-finishing.Finishingremovesalargeamountofmaterialasquicklyandefficientlyaspossible,whileasmallpartofthematerialleftontheworkpieceisusedforfinishing.Finishingis
Theworkpiecegetsthefinalsize,shapeandsurfaceaccuracy.Sometimessemi-finishingleavesapredeterminedamountofmaterialforfinishing,whichispriortofinishing.
Ingeneral,longerworkpiecesaresimultaneouslysupportedbyoneortwolathecenters.Conicalholes,so-calledcenterholes,aredrilledatbothendsforthecenterofthelathe-usuallyalongtheaxisofthecylindricalworkpiece.Theendoftheworkpieceneartheframeisusuallysupportedbythecenterofthetailstock.Attheendnearthemainbearingisthecenterofthemainbearingorclampedbythejawplate.Thismethodcanfirmlytightentheworkpieceandcansmoothlytransmittheforcetotheworkpiece.Theauxiliarysupportprovidedbythechucktotheworkpiecereducesthechatteringtendencyduringcutting.Ifthechuckcanbecarefullyandaccuratelyusedtosupporttheworkpiece,thenAccurateresultscanbeobtained.
Supportingtheworkpiecebetweentwocenterscangiveveryaccurateresults.Oneendoftheworkpiecehasbeenmachined,thentheworkpiececanbeturned.Theotherendismachinedonalathe,andthecenterholeservesasaprecisepositioningsurfaceandasupportingsurfaceforcarryingtheweightoftheworkpieceandresistingthecuttingforce.Whentheworkpieceisremovedfromthelatheforanyreason,thecenterholewillaccuratelyreturntheworkpiecetothislatheoranotherlatheoracylindricalgrinder.Workpiecesarenotallowedtobeclampedonthemainbearingbythechuckandlathecenter.However,thefirstthingthatcomestomindisamethodofquicklyadjustingtheworkpieceonthechuck,butthisisnotallowedbecauseitisimpossibletoholdthecenterofthelathewhileholdingitbythechuck.Theadjustmentprovidedbythecenterofthelathewillnotcontinueandtheclawplatepressurewilldamagethecenterholeandlathecenter,andeventhelathespindle.Thefloatingclawplateprovidesanexceptiontotheabovestatement.Itisusedalmostexclusivelyforhighproductionwork.Thesechucksarerealjobdriversandarenotusedforthesamepurposeasordinarythree-jaw,four-jawchucks.
Whilelarge-diameterworkpiecesarefashionedintwocenters,theyarepreferablyheldbythepanelatthetailofthemainbearingforsmoothenergyconversion;manylathechucksdonotprovidesufficientenergyconversion,althoughtheycanbeusedasspecialenergyconversions.
Mechanicalprocessingintroduction
Asamethodofproducingashape,machiningisthemostcommonlyusedandthemostimportantmethodinallmanufacturingprocesses.Themachiningprocessisaprocessofproducingashapeinwhichthedrivedeviceremovessomeofthematerialontheworkpieceaschips.Althoughinsomecases,theworkpieceissupportedusingmobileequipmentwithoutsupport,mostmachiningoperationsareperformedbyequipmentthatsupportsboththeworkpieceandthetool.
Smallbatch,lowcost.Machininghastwoapplicationsinthemanufacturingindustry.Casting,forging,andpressureworkproduceeachspecialshape,evenonepart,almostalwayswithahighermoldcost.Theshapeofthewelddependslargelyontherawmaterial.Byusingequipmentthathasahighoverallcostbutdoesnothaveaspecialmold,machiningispossible;startingfromalmostanykindofrawmaterial,theshapeisdesignedfromanymaterialaslongastheexternaldimensionsarelargeenough.Processingisthereforethepreferredmethod.Whenproducingoneorseveralpartsoreveninmassproduction,thedesignofthepartslogicallyleadstothecasting,forgingorstampingoftheproduct.Highprecision,surfaceaccuracy.Thesecondapplicationofmechanicalmachiningisbasedonthepossiblehighprecisionandsurfaceaccuracy.Ifmassproductionoccursinotherprocesses,manylow-volumecomponentswillproducelowbutacceptabletolerances.Ontheotherhand,manypartsproducegeneralshapesfromsomelargedeformationprocessesandareonlymachinedonselectedsurfaceswithveryhighaccuracy.Forexample,theinsideprocessisseldomproducedbyanyothermachiningmethodandtheholeonthepartmaybeprocessedimmediatelyafterthepressureoperation.
Themaincuttingparameters
Therearefourfactorsthatfullydescribetherelationshipbetweenthebasictoolingworkduringcutting:
toolgeometry,cuttingspeedanddepthofcut.Thetoolmustbemadeofasuitablematerial;itmusthaveacertainstrength,roughness,hardnessandfatigu
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