牛头刨床钻床和铣削机床夹具外文文献翻译中英文翻译外文翻译.docx

牛头刨床钻床和铣削机床夹具外文文献翻译中英文翻译外文翻译.docx

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牛头刨床钻床和铣削机床夹具外文文献翻译中英文翻译外文翻译

中国地质大学长城学院

本科毕业设计外文资料翻译

系别：

工程技术系

专业：

机械设计制造及其自动化

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学号：

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2015年4月1日

Shapers,DrillingandMillingMachines

Ashapersutilizesasingle-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.

Aduplicatingdevicethatmakespossiblethereproductionofcontoursfromasheet-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.Thekneeisheldonthecolumnindovetailslots,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-removalProcess

Randompoint-cuttingtoolsincludeabrasivesintheshapeofawheel,bondedtoabelt,astick,orsimplysuspendedinliquid.Thegrindingprocessisofextremeimportanceinproductionworkforseveralreasons.

1.Itismostcommonmethodforcuttinghardenedtoolsteelorotherheat-treatedsteel.Partsarefirstmachinedintheun-heat-treatedcondition,andthengroundtothedesireddimensionsandsurfacefinish.

2.Itcanprovidesurfacefinishto0.5µmwithoutextremecost.

3.Thegrindingoperationcanassureaccuratedimensionsinarelativelyshorttime,sincemachinesarebuilttoprovidemotionsinincrementsoften-thousandthsofaninch,insteadofthousandthsasiscommoninothermachines.

4.Extremelysmallandthinpartscanbefinishedbythismethod,sincelightpressureisusedandthetendencyfortheparttodeflectawayfromthecutterisminimized.

Onacylindricalgrindingmachinethegrindingwheelrotatesbetween5500and6500rpm.,whiletheworkrotatesbetween60and125rpm...Thedepthofcutiscontrolledbymovingthewheelhead,whichincludesboththewheelanditsdrivemotor.Coolantsareprovidedtoreduceheatdistortionandtoremovechipsandabrasivedust.

Materialremovalfromductilematerialscanbeaccomplishedbyusingatoolwhichisharderthantheworkpiece.HoweverduringWordWarⅡthewidespreaduseofmaterialswhichwereashardorharderthancuttingtoolscreatedademandfornewmaterial-removalmethods.Sincethenanumberofprocesseshavebeendevelopedwhich,althoughrelativelyslowandcostly,caneffectivelyremoveexcessmaterialinapreciseandrepeatablefashion.Therearetwotypesofprocesses.Thefirsttypeisbasedonelectricalphenomenaandisusedprimarilyforhardmaterials;theseconddependsuponchemicaldissolution.

Chemicalmillingiscontrolledetchingprocessusingstrongalkalineoracidetchants.Aluminum,titanium,magnesium,andsteelaretheprincipalmetalsprocessedbythismethod.Theareatoremainuntouchedbytheetchantaremaskedwithaprotectivecoating.Forexample,theentirepartmaybedippedinthemaskingmaterialandthemaskremovedfromthoseareastobeetched,orachemicallyresistantprescribedtime,afterwhichthepartisrinsedincoldwater,themaskingremoved,thepartinspected,andthoroughlycleaned.

Therearecertaindisadvantagestoconsider.Metalwillerodeequallyinalldirections,sothatwallsoftheetchedsectionwillhavearadiusequaltothedepthofetch.Aseconddisadvantageisthatabetterfinishisobtainedonsurfacesparalleltothedirectionofrollingofasheetthanonsurfaceperpendiculartothedirectionofrolling.Thiscanbecomparedtothesurfaceobtainedwhenworkingwoodparallelto,oracrossthegrain.Athirddisadvantage,notuniquewiththisprocess,isthewarpagethatwilloccurinthin,previouslystressedsectionsetchedonjustoneside.

Chemicalmilling,however,hasmanyadvantagesoverconventionalmetal-removalmethods.Thereisnowarpageofheavysectionssuchasforgingsorextrusionswhentheetchantisappliedsimultaneouslytoallsidesforreductionofsectionthickness.Inconventionalmillingonlyonesidecanbeworkedatatime,andfrequentturningofapartisnecessarytopreventwarpage.Chemicalmillingcanbeappliedtopartsofirregularshapewhereconventionalmillingmaybeverydifficult.Light-weightconstructioncanbeobtainedwithchemicalmillingbytheeliminationofwelding,riveting,andstiffeners;partscanbecontouredtodistributetheloadinthemostsuitablemanner.Asanexampleofthepotentialsavingsofthisprocess,ascomparedtomachinemilling,onecompanyreportsthatthecostofremovingaluminumbychem.-millingis$0.27perpoundascomparedto$1.00perpoundbyconventionalmilling.Therateofmetalremovalforchem.-millingis0.001in.foraluminum