外文翻譯--牛頭刨床鉆床和銑削.doc

機械設計制造及自動化專業(yè)畢業(yè)設計（論文）1文獻翻譯1.英文Shapers,DrillingandMillingMachinesAshapersutilizesasingle-pointtoolonatoolholdermountedontheendoftheram.Cuttingisgenerallydoneontheforwardstroke.Thetoolisliftedslightlybytheclapperboxtopreventexcessivedragacrossthework,whichisfedunderthetoolduringthereturnstrokeinpreparationforthenextcut.Thecolumnhousestheoperatingmechanismsoftheshaperandalsoservesasamountingunitforthework-supportingtable.Thetablecanbemovedintwodirectionsmutuallyperpendiculartotheram.Thetoolslideisusedtocontrolthedepthofcutandismanuallyfed.Itcanberotatedthrough90deg,oneithersideofitsnormalverticalposition,whichallowsfeedingthetoolatanangletothesurfaceofthetable.TwotypesofdrivingmechanismsforshapersareamodifiedWhitworthquick-returnmechanismandahydraulicdrive.FortheWhitworthmechanism,themotordrivesthebullgear,whichdrivesacrankarmwithanadjustablecrankpintocontrolthelengthofstroke.Asthebullgearrotates,therockerarmisforcedtoreciprocate,impartingthismotiontotheshaperram.Themotoronahydraulicshaperisusedonlytodrivethehydraulicpump.Theremainderoftheshapermotionsarecontrolledbythedirectionoftheflowofthehydraulicoil.Thecuttingstrokeofthemechanicallydrivenshaperuses220deg.Ofrotationofthebullgear,whilethereturnstrokeuses140deg.Thisgivesacuttingstroketoreturnstrokeratioof1.6to1.Thevelocitydiagramforahydraulicshapershowsthatformostofthetoolduringcuttingstrokeisneverconstant,whilethevelocitydiagramforahydraulicshapershowsthatformostofthecuttingstrokethecuttingspeedisconstant.Thehydraulicshaperhasanaddedadvantageofinfinitelyvariablecuttingspeeds.Theprincipaldisadvantageofthistypeofmachineisthelackofadefinitelimitattheendoftheramstroke,whichmayallowafewthousandthsofaninchvariationinstrokelength.機械設計制造及自動化專業(yè)畢業(yè)設計（論文）2Aduplicatingdevicethatmakespossiblethereproductionofcontoursfromasheet-metaltemplateisavailable.Thesheetmetaltemplateisusedinconjunctionwithhydrauliccontrol.Uprightdrillingmachinesordrillpressesareavailableinavarietyofsizesandtypes,andareequippedwithasufficientrangeofapindlespeedsandautomaticfeedstofitthenedsofmostindustries.Speedrangesonatypicalmachinearefrom76to2025rpm.,withdrillfeedfrom0.002to0.020in.perrevolutionofthespindle.Radialdrillingmachinesareusedtodrillworkpiecesthataretoolargeorcumbersometoconvenientlymove.Thespindlewiththespeedandfeedchangingmechanismismountedontheradialarm；bycombiningthemovementoftheradialarmaroundcolumnandthemovementofthespindleassemblyalongthearm,itispossibletoalignthespindleandthedrilltoanypositionwithinreachofthemachine.Forworkthatistoolargetoconvenientlysupportonthebase,thespindleassemblycanbeswungoutoverthefloorandtheworkpiecesetonthebesidethemachine.Plainradialdrillingmachinesprovideonlyforverticalmovementofthespindle；universalmachinesallowthespindletoswivelaboutanaxisnormaltotheradialarmandtheradialarmtorotateaboutahorizontalaxis,thuspermittingdrillingatanyangle.Amultispindledrillingmachinehasoneormoreheadsthatdrivethespindlesthroughuniversaljointsandtelescopingsplinedshafts.Allspindlesareusuallydrivenbythesamemotorandfedsimultaneouslytodrillthedesirednumberofholes.Inmostmachineseachspindleisheldinanadjustableplatesothatitcanbemovedrelativetotheothers.Theareacoveredbyadjacentspindlesoverlapsothatthemachinecanbesettodrillholesatanylocationwithinitsrange.Themillingoperationinvolvesmetalremovalwitharotatingcutter.Itincludesremovalofmetalfromthesurfaceofaworkspiece,enlargingholes,andformcutting,suchasthreadsandgearteeth.Withinankneeandcolumntypeofmillingmachinethecolumnisthemainsupportingmemberfortheothercomponents,andincludesthebasecontainingthedrivemotor,thespindle,andthecutters.Thecutterismountedonanarborheldinthespindle,andsupportedonitsouterextremitybyabearingintheoverarm.Thekneeisheldonthecolumnin機械設計制造及自動化專業(yè)畢業(yè)設計（論文）3dovetailslots,thesaddleisfastenedtothekneeindovetailslots,andthetableisattachedtothesaddle.Thus,thebuild-upthekneeandcolumnmachineprovidesthreemotionsrelativetothecutter.Afourmotionmaybeprovidedbyswivelingthetablearoundaverticalaxisprovidedonthesaddle.Fixed-bedmillingmachinesaredesignedtoprovidemorerigiditythanthekneeandcolumntype.Thetableismounteddirectlyonthemachinebase,whichprovidestherigiditynecessaryforabsorbingheavycuttingload,andallowsonlylongitudinalmotiontothetable.Verticalmotionisobtainedbymovingtheentirecuttinghead.Tracermillingischaracterizedbycoordinatedorsynchronizedmovementsofeitherthepathsofthecutterandtracingelements,orthepathsoftheworkpieceandmodel.Inatypicaltracermillthetracingfingerfollowtheshapeofthemasterpattern,andthecutterheadsduplicatethetracermotion.Thefollowingaregeneraldesignconsiderationsformilling:1.Whereverpossible,thepartshouldbedesignedsothatamaximumnumberofsurfacescanbemilledfromonesetting.2.Designfortheuseofmultiplecutterstomillseveralsurfacessimultaneously.3.Thelargestflatsurfacewillbemilledfirst,sothatalldimensionsarebestreferredtosuchsurface.4.Squareinsidecornersarenotpossible,sincethecutterrotates.GrindingMachinesandSpecialMetal-removalProcessRandompoint-cuttingtoolsincludeabrasivesintheshapeofawheel,bondedtoabelt,astick,orsimplysuspendedinliquid.Thegrindingprocessisofextremeimportanceinproductionworkforseveralreasons.1.Itismostcommonmethodforcuttinghardenedtoolsteelorotherheat-treatedsteel.Partsarefirstmachinedintheun-heat-treatedcondition,andthengroundtothedesireddimensionsandsurfacefinish.2.Itcanprovidesurfacefinishto0.5mwithoutextremecost.3.Thegrindingoperationcanassureaccuratedimensionsinarelativelyshorttime,sincemachinesarebuilttoprovidemotionsinincrementsoften-thousandthsofaninch,insteadofthousandthsasis機械設計制造及自動化專業(yè)畢業(yè)設計（論文）4commoninothermachines.4.Extremelysmallandthinpartscanbefinishedbythismethod,sincelightpressureisusedandthetendencyfortheparttodeflectawayfromthecutterisminimized.Onacylindricalgrindingmachinethegrindingwheelrotatesbetween5500and6500rpm.,whiletheworkrotatesbetween60and125rpm.Thedepthofcutiscontrolledbymovingthewheelhead,whichincludesboththewheelanditsdrivemotor.Coolantsareprovidedtoreduceheatdistortionandtoremovechipsandabrasivedust.Materialremovalfromductilematerialscanbeaccomplishedbyusingatoolwhichisharderthantheworkpiece.HoweverduringWordWarthewidespreaduseofmaterialswhichwereashardorharderthancuttingtoolscreatedademandfornewmaterial-removalmethods.Sincethenanumberofprocesseshavebeendevelopedwhich,althoughrelativelyslowandcostly,caneffectivelyremoveexcessmaterialinapreciseandrepeatablefashion.Therearetwotypesofprocesses.Thefirsttypeisbasedonelectricalphenomenaandisusedprimarilyforhardmaterials；theseconddependsuponchemicaldissolution.Chemicalmillingiscontrolledetchingprocessusingstrongalkalineoracidetchants.Aluminum,titanium,magnesium,andsteelaretheprincipalmetalsprocessedbythismethod.Theareatoremainuntouchedbytheetchantaremaskedw