第8次課UNIT-11-Lathe-and-Turning-車床和車削

第8次課LatheandTurning車床和車削

Unit11LatheandTurning

1.Thelatheanditsconstruction2.LatheCuttingTools3.LatheOperations4.CuttingSpeedandFeed1.ThelatheanditsconstructionTheLatheandItsConstruction車床及其結(jié)構(gòu)Alatheisamachinetoolusedprimarilyforproducingsurfacesofrevolutionandflatedges.車床是主要用于生成旋轉(zhuǎn)表面和平整邊緣的機床。Basedontheirpurpose,construction,numberoftoolsthatcansimultaneouslybemounted,anddegreeofautomation,lathes-or,moreaccurately,lathe-typemachinetoolscanbeclassifiedasfollows:根據(jù)它們的使用目的、結(jié)構(gòu)、能同時被安裝刀具的數(shù)量和自動化的程度，車床—或更確切地說是車床類的機床，可以被分成以下幾類：

1.Thelatheanditsconstruction1.Thelatheanditsconstruction(1)Enginelathes普通車床(2)Toolroomlathes萬能車床(3)Turretlathes轉(zhuǎn)塔車床(4)Verticalturningandboringmills立式車削和鏜床(5)Automaticlathes自動車床(6)Special-purposelathes特殊車床1.ThelatheanditsconstructionInspiteofthatdiversityoflathe-typemachinetools,theyallhavecommonfeatureswithrespecttoconstructionandprincipleofoperation.Thesefeaturescanbestbeillustratedbyconsideringthecommonlyusedrepresentativetype,theenginelathe.Followingisadescriptionofeachofthemainelementsofanenginelathe,whichisshowninFig.11.1.雖然車床類的機床多種多樣，但它們在結(jié)構(gòu)和操作原理上具有共同特性。這些特性可以通過普通車床這一最常用的代表性類型來最好地說明。下面是關(guān)于圖11.1所示普通車床的主要部分的描述。1.ThelatheanditsconstructionLathebed.Thelathebedisthemainframe,involvingahorizontalbeamontwoverticalsupports.Itisusuallymadeofgreyornodularcastirontodampvibrationsandismadebycasting.車床床身：車床床身是包含了在兩個垂直支柱上水平橫梁的主骨架。為減振它一般由灰鑄鐵或球墨鑄鐵鑄造而成。Ithasguidewaystoallowthecarriagetoslideeasilylengthwise.Theheightofthelathebedshouldbeappropriatetoenablethetechniciantodohisorherjobeasilyandcomfortably.它上面有能讓溜板輕易縱向滑動的導軌。車床床身的高度應(yīng)適當以讓技師容易而舒適地工作。1.ThelatheanditsconstructionHeadstock.Theheadstockisfixedatthelefthandsideofthelathebedandincludesthespindlewhoseaxisisparalleltotheguideways(theslidesurfaceofthebed).Thespindleisdriventhroughthegearbox,whichishousedwithintheheadstock.主軸箱：主軸箱固定在車床床身的左側(cè)，它包括軸線平行于導軌的主軸。主軸通過裝在主軸箱內(nèi)的齒輪箱驅(qū)動。1.ThelatheanditsconstructionThefunctionofthegearboxistoprovideanumberofdifferentspindlespeeds(usually6upto18speeds).Somemodernlatheshaveheadstockswithinfinitelyvariablespindlespeeds,whichemployfrictional,electrical,orhydraulicdrives.齒輪箱的功能是給主軸提供若干不同的速度(通常是6到18速)。有些現(xiàn)代車床具有采用摩擦、電力或液壓驅(qū)動的無級調(diào)速主軸箱。1.ThelatheanditsconstructionThespindleisalwayshollow,i.e.,ithasathroughholeextendinglengthwise.Barstockcanbefedthroughthatholeifcontinuousproductionisadopted.主軸往往是中空的，即縱向有一通孔。如果采取連續(xù)生產(chǎn)，棒料能通過此孔進給。Also,thatholehasataperedsurfacetoallowmountingaplainlathecenter.Theoutersurfaceofthespindleisthreadedtoallowmountingofachuck,afaceplate,orthelike.同時，此孔為錐形表面可以安裝普通車床頂尖。主軸外表面是螺紋可以安裝卡盤、花盤或類似的裝置。1.ThelatheanditsconstructionTailstock.Thetailstockassemblyconsistsbasicallyofthreeparts,itslowerbase,anintermediatepart,andthequill.Thelowerbaseisacastingthatcanslideonthelathebedalongtheguideways,andithasaclampingdevicetoenablelockingtheentiretailstockatanydesiredlocation,dependinguponthelengthoftheworkpiece.尾架：尾架總成基本包括三部分，底座、尾架體和套筒軸。底座是能在車床床身上沿導軌滑動的鑄件，它有一定位裝置能讓整個尾架根據(jù)工件長度鎖定在任何需要位置。1.ThelatheanditsconstructionTheintermediatepartisacastingthatcanbemovedtransverselytoenablealignmentoftheaxisofthetailstockwiththatoftheheadstock.Thethirdpart,thequill,isahardenedsteeltube,whichcanbemovedlongitudinallyinandoutoftheintermediatepartasrequired.尾架體為一能橫向運動的鑄件，它可以調(diào)整尾架軸線與主軸箱軸線成一直線。第三部分，套筒軸是一淬硬鋼管，它能根據(jù)需要在尾架體中縱向進出移動。1.ThelatheanditsconstructionThisisachievedthroughtheuseofahandwheelandascrew,aroundwhichanutfixedtothequillisengaged.Theholeintheopensideofthequillistaperedtoenablemountingoflathecentersorothertoolsliketwistdrillsorboringbars.Thequillcanbelockedatanypointalongitstravelpathbymeansofaclampingdevice（夾持機構(gòu)）.這通過使用手輪和螺桿來達到，與螺桿嚙合的是一固接在套筒軸上的螺母。套筒軸開口端的孔是錐形的，能安裝車床頂尖或諸如麻花鉆和鏜桿之類的工具。套筒軸通過定位裝置能沿著它的移動路徑被鎖定在任何點。1.ThelatheanditsconstructionThecarriage.Themainfunctionofthecarriageismountingofthecuttingtoolsandgeneratinglongitudinaland/orcrossfeeds.ItisactuallyanH-shapedblockthatslidesonthelathebedbetweentheheadstockandtailstockwhilebeingguidedbytheV-shapedguidewaysofthebed.大拖板：大拖板的主要功能是安裝刀具和產(chǎn)生縱向和/或橫向進給。它實際上是一由車床床身V形導軌引導的、能在車床床身主軸箱和尾架之間滑動的H形滑塊。1.ThelatheanditsconstructionThecarriagecanbemovedeithermanuallyormechanicallybymeansoftheapronandeitherthefeedrodortheleadscrew.大拖板能手動或者通過溜板箱和光桿(進給桿)或絲桿(引導螺桿)機動。1.ThelatheanditsconstructionWhencuttingscrewthreads,powerisprovidedtothegearboxoftheapronbytheleadscrew.Inallotherturningoperations,itisthefeedrodthatdrivesthecarriage.Theleadscrewgoesthroughapairofhalfnuts,whicharefixedtotherearoftheapron.在切削螺旋時，動力通過絲桿提供給溜板箱上的齒輪箱。在其余車削作業(yè)中，都由光桿驅(qū)動大拖板。絲桿穿過一對固定在溜板箱后部的剖分螺母。1.ThelatheanditsconstructionWhenactuatingacertainlever,thehalfnutsareclamped

togetherandengagewiththerotatingleadscrewasasinglenut,whichisfed,togetherwiththecarriage,alongthebed.Whentheleverisdisengaged,thehalfnutsarereleasedandthecarriagestops.當開動特定操作桿時，剖分螺母夾在一起作為單個螺母與旋轉(zhuǎn)的絲桿嚙合，并帶動拖板沿著床身提供進給。當操作桿脫離時，剖分螺母釋放同時大拖板停止運動。1.ThelatheanditsconstructionOntheotherhand,whenthefeedrodisused,itsuppliespowertotheapronthroughawormgear.Thelatteriskeyedtothefeedrodandtravelswiththeapronalongthefeedrod,whichhasakeywayextendingtocoveritswholelength.另一方面，當使用光桿時則通過蝸輪給溜板箱提供動力。蝸輪用鍵連接在光桿上，并與溜板箱一起沿光桿運動，光桿全長范圍開有鍵槽。1.ThelatheanditsconstructionAmodernlatheusuallyhasaquick-changegearboxlocatedundertheheadstockanddrivenfromthespindlethroughatrainofgears.Itisconnectedtoboththefeedrodandtheleadscrewandenablesselectingavarietyoffeedseasilyandrapidlybysimplyshiftingtheappropriatelevers.現(xiàn)代車床一般在主軸箱下裝備快速變換齒輪箱，通過一系列齒輪由主軸驅(qū)動。它與光桿和絲桿連接，能容易并快速地通過簡單轉(zhuǎn)換適當?shù)牟僮鳁U選擇各種進給。1.ThelatheanditsconstructionThequick-changegearboxisemployedinplainturning,facingandthreadcuttingoperations.Sincethatgearboxislinkedtothespindle,thedistancethattheapron(andthecuttingtool)travelsforeachrevolutionofthespindlecanbecontrolledandisreferredtoasthefeed.快速變換齒輪箱可用于普通車削、端面切削和螺旋切削作業(yè)中。由于這種齒輪箱與主軸相連，主軸每轉(zhuǎn)一圈溜板箱(和切削刀具)運動的距離能被控制，這距離就可以被認為是進給。

Unit11LatheandTurning

1.Thelatheanditsconstruction2.LatheCuttingTools3.LatheOperations4.CuttingSpeedandFeed2.LatheCuttingToolsLatheCuttingTools車床切削刀具Theshapeandgeometryofthelathetoolsdependuponthepurposeforwhichtheyareemployed.車床刀具的形狀和幾何參數(shù)取決于它們的使用目的。Turningtoolscanbeclassifiedintotwomaingroups,namely,externalcuttingtoolsandinternalcuttingtools.Eachofthesetwogroupsincludethefollowingtypesoftools:車削刀具可以分為兩個主要組別，即外部切削刀具和內(nèi)部切削刀具。這兩組中的每一組都包括以下類型刀具：2.LatheCuttingToolsCommonCuttingtools2.LatheCuttingToolsTurningtools.Turningtoolscanbeeitherfinishingorroughturningtools.Roughturningtoolshavesmallnoseradiusandareemployedwhendeepcutsaremade.車削刀具：車削刀具可以是精車刀具或粗車刀具。粗車刀具刀尖半徑較小，用于深切削。2.LatheCuttingToolsOntheotherhand,finishingtoolshavelargernoseradiusandareusedforobtainingthefinalrequireddimensionswithgoodsurfacefinishbymakingslightdepthsofcut.Roughturningtoolscanberight-handorleft-handtypes,dependinguponthedirectionoffeed.Theycanhavestraight,bent,oroffsetshanks.而精車刀具刀尖半徑較大，用于通過微量進刀深度來獲得具有較好表面光潔度的最終所需尺寸。粗車刀具按其進給方向可以是右手型的或是左手型的。它們可以有直的、彎的或偏置的刀桿。2.LatheCuttingToolsFacingtools.Facingtoolsareemployedinfacingoperationsformachiningplanesideorendsurfaces.Therearetoolsformachiningleft-hand-sidesurfacesandtoolsforright-hand-sidesurfaces.Thosesidesurfacesaregeneratedthroughtheuseofthecrossfeed,contrarytoturningoperations,wheretheusuallongitudinalfeedisused.端面刀具：端面刀具用在端面作業(yè)中加工平板側(cè)面或端部表面，也有加工左右側(cè)表面之分。與一般采用縱向進給的車削作業(yè)相反，那些側(cè)表面通過采用橫向進給產(chǎn)生。2.LatheCuttingToolsCutofftools.Cutofftools,whicharesometimescalledpartingtools,servetoseparatetheworkpieceintopartsand/ormachineexternalannulargrooves.切斷刀具：切斷刀具，有時也稱為分割刀具，用于將工件分割成若干部分和/或加工外部環(huán)形槽。2.LatheCuttingToolsThread-cuttingtools.Thread-cuttingtoolshaveeithertriangular,square,ortrapezoidalcuttingedges,dependinguponthecrosssectionofthedesiredthread.Also,theplaneanglesofthesetoolsmustalwaysbeidenticaltothoseofthethreadforms.螺紋切削刀具：螺紋切削刀具根據(jù)所需螺紋的橫截面，有三角形的、矩形的或梯形的切削刃。同時，這些刀具的平面角必須始終與螺紋形狀的平面角保持一致。2.LatheCuttingToolsThread-cuttingtoolshavestraightshanksforexternalthreadcuttingandareofthebent-shanktypewhencuttinginternalthreads.車外螺紋的螺紋切削刀具為直刀桿，而車內(nèi)螺紋的螺紋切削刀具則是彎刀桿。2.LatheCuttingToolsFormtools.Formtoolshaveedgesespeciallymanufacturedtotakeacertainform,whichisoppositetothedesiredshapeofthemachinedworkpiece.成形刀具：成形刀具有專門制成特定形狀的刀刃，這種刀刃形狀與被加工工件所需外形正好相反。2.LatheCuttingToolsAnHSS(High-Speed-Steel)toolisusuallymadeintheformofasinglepiece,contrarytocementedcarbidesorceramic,whicharemadeintheformoftips.Thelatterarebrazedormechanicallyfastenedtosteelshanks．高速鋼刀具通常以單件形式制造，而硬質(zhì)合金或陶瓷刀具則以刀尖形式制造。后者用銅焊或機械方法固定于鋼質(zhì)刀桿上。2.LatheCuttingToolsFig.11.2indicatesanarrangementofthislattertype,whichincludesthecarbidetip,thechipbreaker,thepad,theclampingscrew(withawasherandanut),andtheshank.圖11.2所示為機械式固定布置方式，它包括了硬質(zhì)合金刀尖、斷屑槽、襯墊、卡裝螺桿(帶有墊圈和螺母)及刀桿。2.LatheCuttingToolsAsthenamesuggests,thefunctionofthechipbreakeristobreaklongchipseverynowandthen,thuspreventingtheformationofverylongtwistedribbonsthatmaycauseproblemsduringthemachiningoperation.顧名思義，斷屑槽的功能就是不時地折斷長切屑，以防形成很長的可能會在機加工操作中引起問題的纏繞切屑條。2.LatheCuttingToolsThecarbidetips(orceramictips)canhavedifferentshapes,dependinguponthemachiningoperationsforwhichtheyaretobeemployed.Thetipscaneitherbesolidorwithacentralthroughhole,dependingonwhetherbrazingormechanicalclampingisemployedformountingthetipontheshank.硬質(zhì)合金刀尖(或陶瓷刀尖)根據(jù)采用它們的機加工操作，可以有不同的形狀。根據(jù)將刀尖裝配在刀桿上是通過用銅焊還是機械卡裝，刀尖可以是實心的或是帶有中心通孔的。

Unit11LatheandTurning

1.Thelatheanditsconstruction2.LatheCuttingTools3.LatheOperations4.CuttingSpeedandFeed3.LatheOperationsLatheOperations車床操作Inthefollowingsection,wediscussthevariousmachiningoperationsthatcanbeperformedonaconventionalenginelathe.在下面這節(jié)中，要討論的是能在傳統(tǒng)普通車床上進行的各種機加工作業(yè)。3.LatheOperationsItmustbeborneinmind,however,thatmoderncomputerizednumericallycontrolledlatheshavemorecapabilitiesandcandootheroperations,suchascontouring,forexample.Followingareconventionallatheoperations.然而，必須記住現(xiàn)代計算機數(shù)控車床具有更多的功能并且可以進行其它操作，例如仿型。下面是傳統(tǒng)車床的操作。仿形車床是指能仿照樣板或樣件的形狀尺寸，自動完成工件的加工循環(huán)的數(shù)控車床，適用于形狀較復雜的工件的小批和成批生產(chǎn)，生產(chǎn)率比普通車床高10～15倍。有多刀架、多軸、卡盤式、立式等類型。3.LatheOperations

Cylindricalturning.Cylindricalturningisthesimplestandthemostcommonofalllatheoperations.Asinglefullturnoftheworkpiecegeneratesacirclewhosecenterfallsonthelatheaxis;thismotionisthenreproducednumeroustimesasaresultoftheaxialfeedmotionofthetool.圓柱面車削：圓柱面車削是所有車床操作中最簡單也是最普通的。工件旋轉(zhuǎn)一整圈產(chǎn)生一個圓心落在車床主軸上的圓；由于刀具的軸向進給運動這種動作重復許多次。3.LatheOperationsTheresultingmachiningmarksare,therefore,ahelixhavingaverysmallpitch,whichisequaltothefeed.Consequently,themachinedsurfaceisalwayscylindrical.所以，由此產(chǎn)生的機加工痕跡是一條具有很小節(jié)距的螺旋線，該節(jié)距等于進給。因此機加工表面始終是圓柱形的。3.LatheOperationsTheaxialfeedisprovidedbythecarriageorthecompoundrest,eithermanuallyorautomatically,whereasthedepthofcutiscontrolledbythecrossslide.軸向進給通過大拖板或復式刀架手動或自動提供，然而切削深度則由橫向滑動控制。3.LatheOperationsInroughingcuts,itisrecommendedthatlargedepthsofcuts(upto0.25in.or6mm,dependingupontheworkpiecematerial)andsmallerfeedswouldbeused.Ontheotherhand,veryfinefeeds,smallerdepthsofcut(lessthan0.05in,or0.4mm),andhighcuttingspeedsarepreferredforfinishingcuts.粗車中，推薦使用較大切削深度(根據(jù)工件材料可達0.25英寸或6毫米)和較小進給。另一方面，精車則最好采用很小的進給、較小的切削深度(小于0.05英寸或0.4毫米)和較高的切削速度。3.LatheOperationsFacing.Theresultofafacingoperationisaflatsurfacethatiseitherthewholeendsurfaceoftheworkpieceoranannular

intermediatesurfacelikeashoulder.Duringafacingoperation,feedisprovidedbythecrossslide,whereasthedepthofcutiscontrolledbythecarriageorcompoundrest.端面車削：端面車削操作的結(jié)果是將工件整個端部表面或者像軸肩之類的中間環(huán)形表面加工平整。在端面車削操作中，進給由橫向滑板提供，而切削深度則通過大拖板或復式刀架控制。3.LatheOperationsFacingcanbecarriedouteitherfromtheperipheryinwardorfromthecenteroftheworkpieceoutward.Itisobviousthatthemachiningmarksinbothcasestaketheformofaspiral.端面車削既可以從外表面向內(nèi)切削也可以從工件中心往外切削。很明顯在這兩種情況下機加工痕跡都是螺線形式。3.LatheOperationsUsually,itispreferredtoclampthecarriageduringafacingoperation,sincethecuttingforcetendstopushthetool(and,ofcourse,thewholecarriage)awayfromtheworkpiece.Inmostfacingoperations,theworkpieceisheldinacrackoronafaceplate.通常在端面車削作業(yè)時習慣于采用夾住大拖板，這是因為切削力傾向于將刀具(當然包括整個大拖板)推離工件。在大多數(shù)端面車削作業(yè)中，工件被支撐在卡盤或花盤上。3.LatheOperationsGroovecutting.Incut-offandgroove-cuttingoperations,onlycrossfeedofthetoolisemployed.Thecut-offandgroovingtools,whichwerepreviouslydiscussed,areemployed.開槽：在切斷和開槽操作中，刀具只有橫向進給。要采用前面已經(jīng)討論過的切斷和開槽刀具。3.LatheOperationsBoringandinternalturning.Boringandinternalturningareperformedontheinternalsurfacesbyaboringbarorsuitableinternalcuttingtools.Iftheinitialworkpieceissolid,adrillingoperationmustbeperformedfirst.Thedrillingtoolisheldinthetailstock,andthelatteristhenfedagainsttheworkpiece.鏜孔和內(nèi)部車削：鏜孔和內(nèi)部車削通過鏜桿或合適的內(nèi)部切削刀具在內(nèi)表面進行。如果初始工件是實心的，則必須首先進行鉆孔作業(yè)。鉆孔刀具安裝在尾架上，然后對著工件進給。3.LatheOperationsTaperturning.Taperturningisachievedbydrivingthetoolinadirectionthatisnotparalleltothelatheaxisbutinclinedtoitwithananglethatisequaltothedesiredangleofthetaper.Followingarethedifferentmethodsusedintaper-turningpractice:錐面車削：錐面車削通過沿著與車床主軸不平行而傾斜成一個等于錐面所需角度的方向進刀來實現(xiàn)。下面是在實際錐面車削中采用的不同方法：3.LatheOperations(1)Rotatingthediscofthecompoundrestwithanangleequaltohalftheapexangleofthecone.Feedismanuallyprovidedbycrankingthehandleofthecompoundrest.Thismethodisrecommendedfortaperturningofexternalandinternalsurfaceswhenthetaperangleisrelativelylarge.將復式刀架盤旋轉(zhuǎn)一個等于圓錐體頂角一半的角度。通過搖動復式刀架操縱柄手動提供進給。當錐角相對較大時切削外錐面和內(nèi)錐面推薦使用這種方法。3.LatheOperations(2)Employingspecialformtoolsforexternal,veryshort,conicalsurfaces.Thewidthoftheworkpiecemustbeslightlysmallerthanthatofthetool,andtheworkpieceisusuallyheldinachuckorclampedonafaceplate.Inthiscase,onlythecrossfeedisusedduringthemachiningprocessandthecarriageisclampedtothemachinebed.對很短的外錐面采用特殊的成型刀具。工件的寬度必須略小于刀具的寬度，并且工件通常由卡盤支撐或夾緊在花盤上。在這種情況下，機加工作業(yè)時只有橫向進給而大拖板則夾緊在床身上。3.LatheOperations(3)Offsettingthetailstockcenter.Thismethodisemployedforexternaltaperturningoflongworkpiecesthatarerequiredtohavesmalltaperangles(lessthan8°).Theworkpieceismountedbetweenthetwocenters;thenthetailstockcenterisshiftedadistanceSinthedirectionnormaltothelatheaxis.偏移尾架頂尖。對需要較小錐角(小于8°)的較長工件外錐面車削采用這種方法。工件安裝于兩頂尖之間；然后將尾架頂尖朝垂直于車床主軸方向移動一距離S。3.LatheOperations(4)Usingthetaper-turningattachment.Thismethodisusedforturningverylongworkpieces,whenthelengthislargerthanthewholestrokeofthecompoundrest.Theprocedurefollowedinsuchcasesinvolvescompletedisengagementofthecrossslidefromthecarriage,whichisthenguidedbythetaper-turningattachment.采用錐面車削附加裝置。這種方法用于車削很長的工件，其長度大于復式刀架的整個行程。在這種場合下要遵循的步驟是將橫向滑板完全脫離大拖板，然后通過錐面車削附加裝置進行引導。3.LatheOperationsDuringthisprocess,theautomaticaxialfeedcanbeusedasusual.Thismethodisrecommendedforverylongworkpieceswithasmallconeangle,i.e.,8°through10°.在此作業(yè)中，能照常使用自動軸向進給。對具有較小錐角(即8°到10°)的很長工件推薦采用這種方法。3.LatheOperationsThreadcutting.Whenperformingthreadcutting,theaxialfeedmustbekeptataconstantrate,whichisdependentupontherotationalspeed(rpm)oftheworkpiece.Therelationshipbetweenbothisdeterminedprimarilybythedesiredpitchofthethreadtobecut.螺紋切削：在螺紋切削作業(yè)時，軸向進給必須保持恒定速率，這取決于工件的轉(zhuǎn)速(rpm)。兩者之間的關(guān)系基本上由被切削螺紋所需的節(jié)距決定。3.LatheOperationsAspreviouslymentioned,theaxialfeedisautomaticallygeneratedwhencuttingathreadbymeansoftheleadscrew,whichdrivesthecarriage.Whentheleadscrewrotatesasinglerevolution,thecarriagetravelsadistanceequaltothepitchoftheleadscrew.如前所述，當依靠驅(qū)動大拖板的絲桿切削螺紋時軸向進給是自動產(chǎn)生的。絲桿旋轉(zhuǎn)一圈，大拖板就行進等于絲桿節(jié)距的一段距離。3.LatheOperationsConsequently,iftherotationalspeedoftheleadscrewisequaltothatofthespindle(i.e.,thatoftheworkpiece),thepitchoftheresultingcutthreadisexactlyequaltothatoftheleadscrew(絲桿).因此如果絲桿的旋轉(zhuǎn)速度等于心軸的轉(zhuǎn)速(即工件的轉(zhuǎn)速)，生成切削螺紋的節(jié)距就正好等于絲桿的節(jié)距。3.LatheOperationsThepitchoftheresultingthreadbeingcutthereforealwaysdependsupontheratiooftherotationalspeedsoftheleadscrewandthespindle:Pitchoftheleadscrew/Desiredpitchofworkpiece=rpmoftheworkpiece/rpmofleadscrew=spindle-to-carriagegearingratio.所以被切削生成螺紋的節(jié)距總是取決于絲桿和心軸的轉(zhuǎn)速比：絲桿的節(jié)距/工件所需節(jié)距=工件轉(zhuǎn)速/絲桿轉(zhuǎn)速=心軸到大拖板的傳動比。3.LatheOperationsThisequationisusefulindeterminingthekinematiclinkagebetweenthelathespindleandtheleadscrewandenablesproperselectionofthegeartrain(輪系)betweenthem.這公式在決定車床心軸和絲桿之間的運動學關(guān)系時很有用，并且提供了正確挑選它們之間輪系的方法。3.LatheOperationsInthreadcuttingoperations,theworkpiececaneitherbeheldinthechuckormountedbetweenthetwolathecentersforrelativelylongworkpieces.Theformofthetoolusedmustexactlycoincidewiththeprofileofthethreadtobecut,i.e.,triangulartoolsmustbeusedfortriangularthreads,andsoon.在螺紋切削作業(yè)中，工件既能支撐于卡盤中，對相對較長的工件也能安裝在兩個車床頂尖之間。使用的刀具外形必須正好與要切削螺紋的輪廓一致，即三角形刀具必須用于三角形螺紋等等。3.LatheOperationsKnurling.Knurlingismainlyaformingoperationinwhichnochipsareproduced.Itinvolvespressingtwohardenedrollswithroughfilelikesurfacesagainsttherotatingworkpiecetocauseplasticdeformationoftheworkpiecemetal.滾花：滾花主要是一種不產(chǎn)生切屑的成型操作。它使用兩個帶有粗銼式表面的淬火滾輪壓在旋轉(zhuǎn)的工件上使工件金屬產(chǎn)生塑性變形。3.LatheOperationsKnurlingiscarriedouttoproducerough,cylindrical(orconical)surfaces,whichareusuallyusedashandles.Sometimes,surfacesareknurledjustforthesakeofdecoration;therearedifferenttypesofpatternsofknurlsfromwhichtochoose.滾花用于生成粗糙的圓柱(或圓錐)面，通常用來作手柄。有時表面滾花只為裝飾之故；有不同的滾花圖案類型可供選擇。

Unit11LatheandTurning

1.Thelatheanditsconstruction2.LatheCuttingTools3.LatheOperations4.CuttingSpeedandFeed4.CuttingSpeedandFeedCuttingSpeedsandFeed切削速度和進給Thecuttingspeed,whichisusuallygiveninsurfacefeetperminute(SFM),isthenumberoffeettraveledinthecircumferentialdirectionbyagivenpointonthesurface(beingcut)oftheworkpiecein1m