機(jī)械加工及其加工工具中英文翻譯、外文文獻(xiàn)翻譯、外文翻譯

MachiningTechniquesAndToolDrillingandDrillsDrillinginvolvesproducingthroughorblindholesinaworkpiecebyforcingatool,whichrotatesarounditsaxis,againsttheworkpiece.Consequently,therangeofcuttingfromthataxisofrotationisequaltotheradiusoftherequiredhole.Inpractice,twosymmetricalcuttingedgesthatrotateaboutthesameaxisareemployed.Drillingoperationscanbecarriedoutbyusingeitherhanddrillsordrillingmachines.Thelatterdifferinsizeandconstruction.Nevertheless,thetoolalwaysrotatesarounditsaxiswhiletheworkpieceiskeptfirmlyfixed.Thisiscontrarytodrillingonalathe.CuttingToolforDrillingOperationIndrillingoperations,acylindricalrotary-endcuttingtool,calledadrill,isemployed.Thedrillcanhaveeitheroneormorecuttingedgesandcorrespondingflutes,whichcanbestraightorhelical.Thefunctionoftheflutesistoprovideoutletpassagesforthechipsgeneratedduringthedrillingoperationandalsotoallowlubricantsandcoolantstoreachthecuttingedgesandthesurfacebeingmachined.Followingisasurveyofthecommonlyuseddrills.Twistdrill.Thetwistdrillisthemostcommontypeofdrill.Ithastwocuttingedgesandtwohelicalflutesthatcontinueoverthelengthofthedrillbody,.Thedrillalsoconsistsofaneckandashankthatcanbeeitherstraightortapered.Inthelattercase,theshankisfittedbythewedgeactionintothetaperedsocketofthespindleandhasatang,whichgoesintoaslotinthespindlesocket,thusactingasasolidmeansfortransmittingrotation.Ontheotherhand,straight-shankdrillsareheldinadrillchuckthatis,inturn,fittedintothespindlesocketinthesamewayastaperedshankdrills.Thetwocuttingedgesarereferredtoasthelips,andareconnectedtogetherbyawedge,whichisachisel-likeedge.Thetwistdrillalsohastwomargins,whichenableproperguidanceandlocatingofthedrillwhileitisinoperation.Thetoolpointangle(TPA)isformedbythetwolipsandischosenbasedonthepropertiesofthematerialtobecut.TheusualTPAforcommercialdrillsis118°,whichisappropriatefordrillinglow-carbonsteelsandcastirons.Forharderandtoughermetals,suchashardenedsteel,brassandbronze,largerTPAs(130°or140°)givebetterperformance.Thehelixangleoftheflutesofthecommonlyusedtwistdrillsrangesbetween24°and30°.Whendrillingcopperorsoftplastics,highervaluesforthehelixanglearerecommended(between35°and45°).Twistdrillsareusuallymadeofhigh-speedsteel,althoughcarbide-tippeddrillsarealsoavailable.Thesizesoftwistdrillsusedinindustrialpracticerangefrom0.01upto3.25in.(i.e.,0.25upto80mm).Coredrills.Acoredrillconsistsofthechamfer,body,neck,andshank.Thistypeofdrillmayhaveeitherthreeorfourflutesandequalnumberofmargins,whichensuresuperiorguidance,thusresultinginhighmachiningaccuracy.thatacoredrillhasflatend.Thechamfercanhavethreeorfourcuttingedgesorlips,andthelipanglemayvarybetween90°and120°.Coredrillsareemployedforenlargingpreviouslymadeholesandnotfororiginatingholes.Thistypeofdrillischaracterizedbygreaterproductivity,highmachiningaccuracy,andsuperiorqualityofthedrilledsurfaces.Gundrills.Gundrillsareusedfordrillingdeepholes.Allgundrillsarestraight-fluted,andeachhasasinglecuttingedge.Aholeinthebodyactsasaconduittotransmitcoolantunderconsiderablepressuretothetipofthedrill.Therearetwokindsofgundrills,namely,thecenter-cutgundrillusedfordrillingblindholesandthetrepanningdrill.Thelatterhasacylindricalgrooveatitscenter,thusgeneratingasolidcore,whichguidesthetoolasitproceedsduringthedrillingoperation.Spadedrills.Spadedrillsareusedfordrillinglargeholesof3.5in.(90mm)ormore.Theirdesignresultsinamarkedsavingincostofthetoolaswellasatangiblereductioninitsweight,whichfacilitatesitshandling.Moreover,thistypeofdrilliseasytogrind.MillingandMillingCutterMillingisamachiningprocessthatiscarriedoutbymeansofamultiedgerotatingtoolknownasamillingcutter.Inthisprocess,metalremovalisachievedthroughcombiningtherotarymotionofthemillingcutterandlinearmotionsoftheworkpiecesimultaneously.Millingoperationsareemployedinproducingflat,contouredandhelicalsurfacesaswellasforthread-andgear-cuttingoperation.Eachofthecuttingedgesofamillingcutteractsasanindividualsingle-pointcutterwhenitengageswiththeworkpiecemetal.Therefore,eachofthosecuttingedgeshasappropriaterakeandreliefangles.Sinceonlyafewofthecuttingedgesareengagedwiththeworkpieceatatime,heavycutscanbetakenwithoutadverselyaffectingthetoollife.Infact,thepermissiblecuttingspeedsandfeedsformillingarethreetofourtimeshigherthanthoseforturningordrilling.Moreover,thequalityofthesurfacesmachinedbymillingisgenerallysuperiortothequalityofsurfacesmachinedbytrning,shaping,ordrilling.Awidevarietyofmillingcuttersisavailableinindustry.This,togetherwiththefactthatamillingmachineisaveryversatilemachinetool,makesthemillingmachinethebackboneofamachiningworkshop.Asfarasthedirectionofcutterrotationandworkpiecefeedareconcerned,millingisperformedbyeitherofthefollowingtwomethods.Upmilling(conventionalmilling).Inupmillingtheworkpieceisfedagainstthedirectionofcutterrotation.Aswecanseeinthatfigure,thedepthofcut(andconsequentlytheload)graduallyincreasesonthesuccessivelyengagedcuttingedges.Therefore,themachiningprocessinvolvesnoimpactloading,thusensuringsmootheroperationofthemachinetoolandlongertoollife.Thequalityofthemachinedsurfaceobtainedbyupmillingisnotveryhigh.Nevertheless,upmillingiscommonlyusedinindustry,especiallyforroughcuts.Downmilling(climbmilling).Indownmillingthecutterrotationcoincideswiththedirectionoffeedatthecontactpointbetweenthetoolandtheworkpiece.Itcanalsobeseenthatthemaximumdepthofcutisachieveddirectlyasthecutterengageswiththeworkpiece.Thisresultsinakindofimpact,orsuddenloading.Therefore,thismethodcannotbeusedunlessthemillingmachineisequippedwithabacklasheliminatoronthefeedscrew.Theadvantagesofthismethodincludehigherqualityofthemachinedsurfaceandeasierclampingofworkpieces,sincethecuttingforcesactdownward.TypesofMillingCuttersThereisawidevarietyofmillingcuttershapes.Eachofthemisdesignedtoperformeffectivelyaspecificmillingoperation.Generally,amillingcuttercanbedescribedasamultiedgecuttingtoolhavingtheshapeofasolidofrevolution,withthecuttingteetharrangedeitherontheperipheryoronanendfaceoronboth.Followingisaquicksurveyofthecommonlyusedtypesofmillingcutters.Plainmillingcutter.Aplainmillingcutterisadisk-shapedcuttingtoolthatmayhaveeitherstraightorhelicalteeth.Thistypeisalwaysmountedonhorizontalmillingmachinesandisusedformachiningflatsurfaces.Facemillingcutter.Afacemillingcutterisalsousedformachiningflatsurfaces.Itisboltedattheendofashortarbor,whichisinturnmountedonaverticalmillingmachine.Plainmetalslittingsawcutter.Indicatesaplainmetalslittingsawcutter.wecanseethatitactuallyinvolvesaverythinplainmillingcutter.Sidemillingcutter.Asidemillingcutterisusedforcuttingslots,grooves,andsplines.Itisquitesimilartotheplainmillingcutter,thedifferencebeingthatthistypehasteethonthesides.Asisthecasewiththeplaincutter,thecuttingteethcanbestraightorhelical.Anglemillingcutter.Ananglemillingcutterisemployedincuttingdovetailgrooves,ratchetwheels.T-slotcutter.AT-slotcutterinvolvesaplainmillingcutterwithanintegralshaftnormaltoit.Asthenamesuggests,thistypeisusedformillingT-slots.Endmillcutter.Endmillcuttersfindcommonapplicationsincuttingslots,grooves,flutes,splines,pocketingwork,andthelike.Indicatesanendmillcutter.Thelatterisalwaysmountedonaverticalmillingmachineandcanhavetwoorfourflutes,whichmaybeeitherstraightorhelical.Formmillingcutter.Theteethofaformmillingcutterhaveacertainshape,whichisidenticaltothesectionofthemetaltoberemovedduringthemillingoperation.Examplesofthistypeincludegearcutters,gearhobs,convexandconcavecutters,andthelike.Frommillingcuttersaremountedonhorizontalmillingmachines.MaterialsofMillingCuttersThecommonlyusedmillingcuttersaremadeofhigh-speedsteel,whichisgenerallyadequateformostjobs.Millingcutterstippedwithsinteredcarbidesorcastnonferrousalloysascuttingteethareusuallyemployedformassproduction,whereheaviercutsand/orhighcuttingspeedsarerequired.Ithasalreadybeenstatedthattheworkpiecemustbelocatedrelativetothecuttingtool,andbesecuredinthatposition.Aftertheworkpiecehasbeenmarkedout,itisstillnecessarytopositionitwithrespecttothemachinemovements,andtoclampitinthatpositionbeforemachiningisstarted.Whenseveralidenticalworkpiecesaretobeproducedtheneedtomarkouteachpartiseliminatedbytheuseofjigsandfixtures,butifacastingorforgingisinvolved,atrialworkpieceismarkedout,toensurethattheworkpiececanbeproducedfromit,andtoensurethatribs,cores,etc.havenotbecomemisplaced.Jigsandfixturesarealikeinthattheybothincorporatedevicestoensurethattheworkpieceiscorrectlylocatedandclamped,buttheydifferinthatjigsincorporatemeansoftoolguidingduringtheactualcuttingoperation,andfixturesdonot.Inpractice,theonlycuttingtoolsthatcanbeguidedwhileactuallycuttingaredrills,reamers,andsimilarcutters;andsojigsareassociatedwithdrillingoperations,andfixtureswithallotheroperations.Fixturesmayincorporatemeansofsettingthecuttingtoolsrelativetothelocationsystem.Theadvantagesofjigsandfixturescanbesummarisedasfollows:1)Markingoutandothermeasuringandsettingoutmethodsareeliminated;2)Unskilledworkersmayproceedconfidentlyandquicklyinknowledgethattheworkpiececanbepositionedcorrectly,andthetoolsguidedorset;3)theassemblyofpartsisfacilitated,sinceallcomponentswillbeidenticalwithinsmalllimits,and“trying”andfilingofworkiseliminated;4)Thepartswillbeinterchangeable,andiftheproductsoldoverawidearea,theproblemofsparepartswillbesimplified.Boltholesoftenhave1.5mmoreven3.0mmclearanceforthebolt,andthereadermaydoubtthenecessityofmakingprecisionjigsforsuchwork.Itmustberememberedthatthejigs,oncemade,willbeusedonmanycomponents,andtheextracostofanaccuratelymadejigisspreadoveralargeoutput.Furthermore,itissurprisinghowsmallerrorsaccumulateinamechanismduringitsassembly.Whenaclearanceisspecified,itisbettertoensureitsobservance,ratherthantoallowcarelessmarkingoutandmachiningtoencroachuponit．1)Thelocationofworkpiece.Representsabodythatiscompletelyfreeinspace.Inthisconditionithassixdegreesoffreedom.ConsiderthesefreedomswithrespecttothethreemutuallyperpendicularaxesXX,YY,andZZ.Thebodycanmovealonganyoftheseaxes;itthereforehasthreefreedomsoftranslation.Itcanalsorotateaboutanyofthethreeaxes;itthereforehasthreefreedomsofrotation.Thetotalnumberoffreedomsissix.Whenworkislocated,asmanyofthesefreedomsaspossiblemustbeeliminated,toensurethattheoperationisperformedwiththerequiredaccuracy.Accuracyisensuredbymachiningsuitablelocationfeaturesasearlyaspossible,andusingthemforalllocation,unlessotherconsiderationsmeanthatotherlocationfeaturesmustbeused.Ifitisnecessary,thenewlocationfeaturesmustbemachinedasaresultoflocationfromtheformerlocationfeatures.2)Theclampingoftheworkpiece.Theclampingsystemmustbesuchthattheworkpieceisheldagainstthecuttingforces,andtheclampingforcesmustnotbesogreatastocausetheworkpiecetobecomedistortedordamaged.Theworkpiecemustbesupportedbeneaththepointofclamping,toensurethattheforcesaretakenbythemainframeofthejigorfixture,andontothemachinetableandbed.Whenjigsandfixturesaredesigned,theclampingsystemisdesignedtoensurethatthecorrectclampingforceisapplied,andthattheclampscanbeoperatedquicklybutwithsafety.DefinitionofaDrillJigAdrilljigisadeviceforensuringthataholetobedrilled,tapped,orreamedinaworkpiecewillbemachinedintheproperplace.Basicallyitconsistsofaclampingdevicetoholdthepartinpositionunderhardened-steelbushingsthroughwhichthedrillpassesduringthedrillingoperation.Thedrillisguidedbythebushings.Iftheworkpieceisofsimpleconstruction,thejigmaybeclampedontheworkpiece.Inmostcases,however,theworkpieceisheldbythejig,andthejigisarrangedsothattheworkpiececanbequicklyinsertedandasquicklyremovedafterthemachiningoperationisperformed.Jigsmakeitpossibletodrill,ream,andtapholesatmuchgreaterspeedsandwithgreateraccuracythanwhentheholesareproducedbyconventionalhandmethods.Anotheradvantageisthatskilledworkersarenotrequiredwhenjigsareused.Responsibilityfortheaccuracyofholelocationistakenfromtheoperatorandgiventothejig.Thetermjigshouldbeusedonlyfordevicesemployedwhiledrilling,reaming,ortappingholes.Itisnotfastenedtothemachineonwhichitisusedandmaybemovedaroundonthetableofthedrillingmachinetobringeachbushingdirectlyunderthedrill.Jigsphysicallylimitandcontrolthepathofthecuttingtool.Iftheoperationincludesmachiningoperationslikemilling,planing,shaping,turning,etc.,thetermfixtureshouldbeused.Afixtureholdstheworkduringmachiningoperationsbutdoesnotcontainspecialarrangementsforguidingthecuttingtool,asdrilljigsdo.TypicalJigsandFixturesTypicaldrilljig.Illustratesadrillingjigfordrillingfourholesintheflangeofaworkpiecethathasbeencompletedexceptforthefourholes.Theworkpiecehasanaccuratelymachinedbore,andislocatedfromtheboreandtheendface,fromacylindricalpost.Thereisnoneedtocontroltherotationalpositionabouttheaxisofthebore,becauseuptothetimewhentheholesaredrilled,itissymmetricalaboutthataxisThefourbushesusedtocontrolthedrillareheldinthedrillplate,which,withthehandnut,isusedtoclamptheworkpieceagainstthebaseofthefixture.Typicalmillingfixture.Figure13.3illustratesasimplemillingfixtureformillingtheslotintheotherwisecompletedworkpieceshown.Theworkpieceislocatedfromtwoofthefourholesinitsbase,andfromtheundersideofthebase.Theworkpieceisclampedinposition,andcutterislocatedagainstthesettingblock,whichprovidessettingorcutterpositionanddepthofcut.Thefixturemustbepositionedrelativetothemachinetable,ThefixtureissecuredtothemachinetablewithT-bolts,alsoengagingintheslotsinthetable.機(jī)械加工及其加工工具鉆削和鉆頭鉆削就是通過(guò)迫使繞自身軸線旋轉(zhuǎn)的切削刀具進(jìn)入工件而在其上生成通孔或盲孔。因此，從旋轉(zhuǎn)軸線開始的切削范圍等于所需孔的半徑。實(shí)際上，使用的是兩條圍繞相同軸線旋轉(zhuǎn)的對(duì)稱切削刃。鉆削作業(yè)既能采用手鉆也能采用鉆床來(lái)實(shí)現(xiàn)。鉆床在尺寸和結(jié)構(gòu)上雖有差別，然而始終都是切削刀具圍繞自身軸線旋轉(zhuǎn)、工件穩(wěn)固定位的形式。這正好與在車床上鉆孔相反。用于鉆削作業(yè)的切削刀具在鉆削作業(yè)中，要用到被稱為鉆頭的圓柱形回轉(zhuǎn)端切削刀具。鉆頭可以有一條或多條直的或是螺旋狀的切削刃以及相應(yīng)的出屑槽。出屑槽的功能是給鉆削作業(yè)中產(chǎn)生的切屑提供排出通道，并允許潤(rùn)滑劑和冷卻液到達(dá)切削刃和正在被加工的表面。下面是常用鉆頭的概述。麻花鉆：麻花鉆是最常用的鉆頭類型。它有兩條切削刃和兩條沿鉆頭體全長(zhǎng)連續(xù)的螺旋狀出屑槽。麻花鉆還包括鉆頸和鉆柄，鉆柄可以是直的也可以是錐形的。錐形鉆柄通過(guò)楔入動(dòng)作安裝在主軸的錐形軸孔中，鉆柄上還有柄舌插入主軸軸孔中的插槽，從而作為傳遞轉(zhuǎn)動(dòng)的可靠方法。另一方面，直柄鉆頭用鉆頭卡盤夾住，接下來(lái)鉆頭卡盤則象錐形鉆柄鉆頭一樣安裝在主軸軸孔內(nèi)。兩條切削刃就是鉆唇，通過(guò)鑿子狀邊緣的楔形體連在一起。麻花鉆還有兩條導(dǎo)向邊，用于作業(yè)中鉆頭的正確導(dǎo)向和定位。兩條鉆唇形成鉆頂角，并根據(jù)被鉆削材料的性能來(lái)選取其大小。商品化鉆頭的鉆頂角一般為118°，這適用于鉆削低碳鋼和鑄鐵。對(duì)于更硬更韌的金屬，諸如淬火鋼、黃銅和青銅，更大的鉆頂角(130°或140°)才能有更好的效果。麻花鉆常用的出屑槽螺旋角范圍為24°到30°。鉆削紫銅或軟塑料時(shí)，推薦采用更大的螺旋角(35°到45°)。雖然也有硬質(zhì)合金刀尖的鉆頭，麻花鉆一般用高速鋼制成。工業(yè)實(shí)際中使用的麻花鉆尺寸范圍為0.01到3.25英寸(即0.25到80毫米)?？招你@：空心鉆包括斜面、鉆頭體、鉆頸和鉆柄。這類鉆頭可以有三條或四條出屑槽及相同數(shù)量的保證良好導(dǎo)向的導(dǎo)向邊，這樣使得加工有高精度。在中同樣能看到，空心鉆具有平坦的端部。斜面可以有三或四條切削刃或鉆唇，并且鉆唇角可以在90°到120°之間變化?？招你@用于擴(kuò)大已有的孔而不是打孔。這類鉆頭具有較大生產(chǎn)率、高加工精度和優(yōu)良鉆削表面質(zhì)量的特性。深孔鉆：深孔鉆用于鉆深孔。所有深孔鉆都是直出屑槽的，并且均為單切削刃。鉆頭體中有個(gè)孔作為導(dǎo)管在相當(dāng)大的壓力下將冷卻液傳送到鉆頭頂端。深孔鉆有兩種類型，即用于鉆盲孔的中心切削深孔鉆和套孔鉆。后者在其中心有一圓柱形溝槽，這樣能生成整體芯在鉆孔作業(yè)過(guò)程中引導(dǎo)鉆頭。扁平鉆：扁平鉆用于鉆削3.5英寸(90毫米)或更大的大孔。其設(shè)計(jì)使得鉆頭成本明顯節(jié)省、重量切實(shí)減輕，重量輕又使操作更方便。此外這種鉆頭容易磨利。銑削和銑刀銑削是采用被稱為銑刀的多刃旋轉(zhuǎn)刀具完成的機(jī)加工作業(yè)。在此工藝中，金屬去除是通過(guò)銑刀的旋轉(zhuǎn)運(yùn)動(dòng)和工件的直線運(yùn)動(dòng)的組合實(shí)現(xiàn)的。銑削作業(yè)既可用于生成平面、輪廓面和螺旋面，也可用于切削螺紋和齒輪。在銑刀切削工件金屬時(shí)，銑刀的每條切削刃都象一單獨(dú)的單刃刀具一樣作用。所以每條切削刃都適當(dāng)?shù)那昂蠼恰Ｓ捎谕粫r(shí)間只有部分切削刃切削工件，因此可以在對(duì)刀具壽命沒(méi)有不利影響的情況下承擔(dān)重型切削。事實(shí)上，銑削允許的切削速度和進(jìn)給比車削或鉆削高三到四倍。此外，由銑削加工的表面質(zhì)量通常優(yōu)于車削、刨削或鉆削加工的表面質(zhì)量。工業(yè)上可采用的銑刀類型眾多。連同銑床是極通用機(jī)床的事實(shí)，使得銑床成為機(jī)加工車間的支柱。至于涉及到銑刀轉(zhuǎn)動(dòng)的方向和工件的進(jìn)給，銑削可以通過(guò)下列兩種方法之一進(jìn)行。逆銑(傳統(tǒng)銑削)：在逆銑中，工件逆著銑刀轉(zhuǎn)動(dòng)的方向進(jìn)給，如圖12.3a所示。就像在此圖中能看到的那樣，切削深度(及作為結(jié)果的載荷)隨著切削刃持續(xù)進(jìn)入切削而逐漸增加。所以，這種工藝沒(méi)有沖擊載荷，從而保證了機(jī)床的較平穩(wěn)運(yùn)行和較長(zhǎng)壽命。通過(guò)逆銑所得機(jī)加工表面質(zhì)量不是很高。然而逆銑仍經(jīng)常被用在工業(yè)上，尤其是粗切削時(shí)。順銑(同向銑削)：在順銑時(shí)刀具與工件之間接觸點(diǎn)上銑刀旋轉(zhuǎn)與進(jìn)給方向一致。還可以看到當(dāng)?shù)毒哌M(jìn)入工件切削時(shí)直接達(dá)到最大切削深度。這會(huì)導(dǎo)致一種沖擊，或突然加載。因此，這種方法只有當(dāng)銑床在進(jìn)給螺栓上配備間隙消除器時(shí)才采用。這種方法的優(yōu)點(diǎn)包括機(jī)加工表面質(zhì)量較高和工件由于切削力向下作用而較容易夾緊。銑刀的類型銑刀的形狀類型很多。其中每種都是為有效進(jìn)行特定的銑削作業(yè)而設(shè)計(jì)的。通常，銑刀可以被描述為具有旋轉(zhuǎn)實(shí)體形狀并將切削齒安裝在周邊或一到兩個(gè)端面上的多刃切削刀具。下面是常用銑刀類型的快速綜覽。平面銑刀：平面銑刀是一種盤狀切削刀具，它可以具有直齒或螺旋齒。這類銑刀總是安裝在臥式銑床上，用于機(jī)加工平面。端面銑刀：端面銑刀也可用于機(jī)加工平面。它用螺栓固定在短刀桿的端部，而短刀桿則依次安裝于立式銑床上。顯示了這類銑刀。平面金屬開槽鋸刃銑刀：顯示了一種平面金屬開槽鋸刃銑刀?？梢钥吹剿鋵?shí)是一種很薄的平面銑刀。側(cè)銑刀：側(cè)銑刀用于切削狹槽、凹槽和花鍵槽。它與平面銑刀十分相似，差別在于此類銑刀齒在側(cè)面。象平面銑刀的情況一樣，切削齒既可以是直的也可以是螺旋的。傾斜銑刀：傾斜銑刀用于切削燕尾槽、棘輪之類的。顯示了這類銑刀。T型槽銑刀:T型槽銑刀包括了一個(gè)平面銑刀和一根