机械加工钻床中英文对照外文翻译文献.docx

机械加工钻床中英文对照外文翻译文献.docx

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机械加工钻床中英文对照外文翻译文献

中英文对照外文翻译文献

（文档含英文原文和中文翻译）

原文：

DrillingandMillingMachines

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.

Electric-dischargemachiningisaprocessinwhichanelectricalpotentialisimpressedbetweentheworkpieceandthetool,andthecurrent,emanatingfromapointsourceontheworkpoiece,flowstothetoolintheformofaspark.Theforcesthataccomplishthemetalremovalarewithintheworkpieceproperand,asaresult,itisnotnecessarytoconstructtheunittowithstandtheheavypressuresandloadsprevalentwithconventionalmachiningmethods.

Thefrequencyoftheelectricaldischargerangesfrom20,00cps（cyclespersecond）forroughmachining,to50,000cpsforfinishingsuchitemsashardenedtoolsanddies.Thecurrentmayvaryfrom50amp,duringroughmachining,toaslowas0.5amp,duringfinishing.Theprocessiscurrentlyappliedtothemachiningofsingle-pointtools,formtools,millingcutters,broaches,anddiecavities.Itisalsoapplicabletotheremovalofbrokendrills,taps,andstudswithoutdamagingtheworkpieceinwhichthebrokentoolisimbedded.Otherusesarethemachiningofoilholesinahardenedpart,andthemachiningofsmallsafety-wireholesintheheadsofspecialalloybolts,suchastitanium.

Theultrasonicmachiningprocessisappliedtobothconductingandnon-conductingmaterial,andreliesentirelyuponabrasiveactionformetalremoval.Theworkpieceissubmergedinslurryoffinelyfividedabrasiveparticlesinavehiclesuchaswater.Thetooliscoupledtoanoscillatorandvibratesatfrequenciesbetween15,000and30,000cps.Thevibratingtoolcavitatestheliquid,andtheforcedrivestheabrasiveintothesurfaceoftheworkpiecetoremovemetalchipswhicharecarriedawaybytheliquid.Theaccelerationgiventheabrasivegrainsisasmuchas100,000timestheaccelerationofgravity,providingasmoothandrapidcuttingforce.

IntroductionofMachining

Machiningasashape-producingmethodisthemostuniversallyusedandthemostimportantofallmanufacturingprocesses.Machiningisashape-producingprocessinwhichapower-drivendevicecausesmaterialtoberemovedinchipform.Mostmachiningisdonewithequipmentthatsupportsboththeworkpieceandcuttingtoolalthoughinsomecasesportableequipmentisusedwithunsupportedworkpiece.

Lowsetupcostforsmallquantities.M