第8-9次課UNIT11LatheandTurning市公開課一等獎(jiǎng)省賽課微課金獎(jiǎng)?wù)n件

第8次課LatheandTurning車床和車削1/74

Unit11LatheandTurning

1.Thelatheanditsconstruction2.LatheCuttingTools3.LatheOperations4.CuttingSpeedandFeed2/741.ThelatheanditsconstructionTheLatheandItsConstruction車床及其結(jié)構(gòu)Alatheisamachinetoolusedprimarilyforproducingsurfacesofrevolutionandflatedges.車床是主要用于生成旋轉(zhuǎn)表面和平整邊緣機(jī)床。Basedontheirpurpose,construction,numberoftoolsthatcansimultaneouslybemounted,anddegreeofautomation,lathes-or,moreaccurately,lathe-typemachinetoolscanbeclassifiedasfollows:依據(jù)它們使用目標(biāo)、結(jié)構(gòu)、能同時(shí)被安裝刀具數(shù)量和自動(dòng)化程度，車床—或更確切地說是車床類機(jī)床，能夠被分成以下幾類：

3/741.Thelatheanditsconstruction4/741.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(dòng)車床(6)Special-purposelathes特殊車床5/746/747/748/749/741.ThelatheanditsconstructionInspiteofthatdiversityoflathe-typemachinetools,theyallhavecommonfeatureswithrespecttoconstructionandprincipleofoperation.Thesefeaturescanbestbeillustratedbyconsideringthecommonlyusedrepresentativetype,theenginelathe.Followingisadescriptionofeachofthemainelementsofanenginelathe,whichisshowninFig.11.1.即使車床類機(jī)床各種多樣，但它們?cè)诮Y(jié)構(gòu)和操作原理上含有共同特征。這些特征能夠經(jīng)過普通車床這一最慣用代表性類型來最好地說明。下面是關(guān)于圖11.1所表示普通車床主要部分描述。10/7411/7412/741.ThelatheanditsconstructionLathebed.Thelathebedisthemainframe,involvingahorizontalbeamontwoverticalsupports.Itisusuallymadeofgreyornodularcastirontodampvibrationsandismadebycasting.車床床身：車床床身是包含了在兩個(gè)垂直支柱上水平橫梁主骨架。為減振它普通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(dòng)導(dǎo)軌。車床床身高度應(yīng)適當(dāng)以讓技師輕易而舒適地工作。13/741.ThelatheanditsconstructionHeadstock.Theheadstockisfixedatthelefthandsideofthelathebedandincludesthespindlewhoseaxisisparalleltotheguideways(theslidesurfaceofthebed).Thespindleisdriventhroughthegearbox,whichishousedwithintheheadstock.主軸箱：主軸箱固定在車床床身左側(cè)，它包含軸線平行于導(dǎo)軌主軸。主軸經(jīng)過裝在主軸箱內(nèi)齒輪箱驅(qū)動(dòng)。14/741.ThelatheanditsconstructionThefunctionofthegearboxistoprovideanumberofdifferentspindlespeeds(usually6upto18speeds).Somemodernlatheshaveheadstockswithinfinitelyvariablespindlespeeds,whichemployfrictional,electrical,orhydraulicdrives.齒輪箱功效是給主軸提供若干不一樣速度(通常是6到18速)。有些當(dāng)代車床含有采取摩擦、電力或液壓驅(qū)動(dòng)無級(jí)調(diào)速主軸箱。15/741.ThelatheanditsconstructionThespindleisalwayshollow,i.e.,ithasathroughholeextendinglengthwise.Barstockcanbefedthroughthatholeifcontinuousproductionisadopted.主軸往往是中空，即縱向有一通孔。假如采取連續(xù)生產(chǎn)，棒料能經(jīng)過此孔進(jìn)給。Also,thatholehasataperedsurfacetoallowmountingaplainlathecenter.Theoutersurfaceofthespindleisthreadedtoallowmountingofachuck,afaceplate,orthelike.同時(shí)，此孔為錐形表面能夠安裝普通車床頂尖。主軸外表面是螺紋能夠安裝卡盤、花盤或類似裝置。16/741.ThelatheanditsconstructionTailstock.Thetailstockassemblyconsistsbasicallyofthreeparts,itslowerbase,anintermediatepart,andthequill.Thelowerbaseisacastingthatcanslideonthelathebedalongtheguideways,andithasaclampingdevicetoenablelockingtheentiretailstockatanydesiredlocation,dependinguponthelengthoftheworkpiece.尾架：尾架總成基本包含三部分，底座、尾架體和套筒軸。底座是能在車床床身上沿導(dǎo)軌滑動(dòng)鑄件，它有一定位裝置能讓整個(gè)尾架依據(jù)工件長(zhǎng)度鎖定在任何需要位置。17/741.ThelatheanditsconstructionTheintermediatepartisacastingthatcanbemovedtransverselytoenablealignmentoftheaxisofthetailstockwiththatoftheheadstock.Thethirdpart,thequill,isahardenedsteeltube,whichcanbemovedlongitudinallyinandoutoftheintermediatepartasrequired.尾架體為一能橫向運(yùn)動(dòng)鑄件，它能夠調(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，它能依據(jù)需要在尾架體中縱向進(jìn)出移動(dòng)。18/741.ThelatheanditsconstructionThisisachievedthroughtheuseofahandwheelandascrew,aroundwhichanutfixedtothequillisengaged.Theholeintheopensideofthequillistaperedtoenablemountingoflathecentersorothertoolsliketwistdrillsorboringbars.Thequillcanbelockedatanypointalongitstravelpathbymeansofaclampingdevice（夾持機(jī)構(gòu)）.這經(jīng)過使用手輪和螺桿來到達(dá)，與螺桿嚙合是一固接在套筒軸上螺母。套筒軸開口端孔是錐形，能安裝車床頂尖或諸如麻花鉆和鏜桿之類工具。套筒軸經(jīng)過定位裝置能沿著它移動(dòng)路徑被鎖定在任何點(diǎn)。19/741.ThelatheanditsconstructionThecarriage.Themainfunctionofthecarriageismountingofthecuttingtoolsandgeneratinglongitudinaland/orcrossfeeds.ItisactuallyanH-shapedblockthatslidesonthelathebedbetweentheheadstockandtailstockwhilebeingguidedbytheV-shapedguidewaysofthebed.大拖板：大拖板主要功效是安裝刀具和產(chǎn)生縱向和/或橫向進(jìn)給。它實(shí)際上是一由車床床身V形導(dǎo)軌引導(dǎo)、能在車床床身主軸箱和尾架之間滑動(dòng)H形滑塊。20/741.ThelatheanditsconstructionThecarriagecanbemovedeithermanuallyormechanicallybymeansoftheapronandeitherthefeedrodortheleadscrew.大拖板能手動(dòng)或者經(jīng)過溜板箱和光桿(進(jìn)給桿)或絲桿(引導(dǎo)螺桿)機(jī)動(dòng)。21/741.ThelatheanditsconstructionWhencuttingscrewthreads,powerisprovidedtothegearboxoftheapronbytheleadscrew.Inallotherturningoperations,itisthefeedrodthatdrivesthecarriage.Theleadscrewgoesthroughapairofhalfnuts,whicharefixedtotherearoftheapron.在切削螺旋時(shí)，動(dòng)力經(jīng)過絲桿提供給溜板箱上齒輪箱。在其余車削作業(yè)中，都由光桿驅(qū)動(dòng)大拖板。絲桿穿過一對(duì)固定在溜板箱后部剖分螺母。22/741.ThelatheanditsconstructionWhenactuatingacertainlever,thehalfnutsareclamped

togetherandengagewiththerotatingleadscrewasasinglenut,whichisfed,togetherwiththecarriage,alongthebed.Whentheleverisdisengaged,thehalfnutsarereleasedandthecarriagestops.當(dāng)開動(dòng)特定操作桿時(shí)，剖分螺母夾在一起作為單個(gè)螺母與旋轉(zhuǎn)絲桿嚙合，并帶動(dòng)拖板沿著床身提供進(jìn)給。當(dāng)操作桿脫離時(shí)，剖分螺母釋放同時(shí)大拖板停頓運(yùn)動(dòng)。23/741.ThelatheanditsconstructionOntheotherhand,whenthefeedrodisused,itsuppliespowertotheapronthroughawormgear.Thelatteriskeyedtothefeedrodandtravelswiththeapronalongthefeedrod,whichhasakeywayextendingtocoveritswholelength.另首先，當(dāng)使用光桿時(shí)則經(jīng)過蝸輪給溜板箱提供動(dòng)力。蝸輪用鍵連接在光桿上，并與溜板箱一起沿光桿運(yùn)動(dòng)，光桿全長(zhǎng)范圍開有鍵槽。24/741.ThelatheanditsconstructionAmodernlatheusuallyhasaquick-changegearboxlocatedundertheheadstockanddrivenfromthespindlethroughatrainofgears.Itisconnectedtoboththefeedrodandtheleadscrewandenablesselectingavarietyoffeedseasilyandrapidlybysimplyshiftingtheappropriatelevers.當(dāng)代車床普通在主軸箱下裝備快速變換齒輪箱，經(jīng)過一系列齒輪由主軸驅(qū)動(dòng)。它與光桿和絲桿連接，能輕易并快速地經(jīng)過簡(jiǎn)單轉(zhuǎn)換適當(dāng)操作桿選擇各種進(jìn)給。25/741.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。因?yàn)檫@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(yùn)動(dòng)距離能被控制，這距離就能夠被認(rèn)為是進(jìn)給。26/74

Unit11LatheandTurning

1.Thelatheanditsconstruction2.LatheCuttingTools3.LatheOperations4.CuttingSpeedandFeed27/742.LatheCuttingToolsLatheCuttingTools車床切削刀具Theshapeandgeometryofthelathetoolsdependuponthepurposeforwhichtheyareemployed.車床刀具形狀和幾何參數(shù)取決于它們使用目標(biāo)。Turningtoolscanbeclassifiedintotwomaingroups,namely,externalcuttingtoolsandinternalcuttingtools.Eachofthesetwogroupsincludethefollowingtypesoftools:車削刀具能夠分為兩個(gè)主要組別，即外部切削刀具和內(nèi)部切削刀具。這兩組中每一組都包含以下類型刀具：28/742.LatheCuttingToolsCommonCuttingtools29/742.LatheCuttingToolsTurningtools.Turningtoolscanbeeitherfinishingorroughturningtools.Roughturningtoolshavesmallnoseradiusandareemployedwhendeepcutsaremade.車削刀具：車削刀具能夠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。30/742.LatheCuttingToolsOntheotherhand,finishingtoolshavelargernoseradiusandareusedforobtainingthefinalrequireddimensionswithgoodsurfacefinishbymakingslightdepthsofcut.Roughturningtoolscanberight-handorleft-handtypes,dependinguponthedirectionoffeed.Theycanhavestraight,bent,oroffsetshanks.而精車刀具刀尖半徑較大，用于經(jīng)過微量進(jìn)刀深度來取得含有很好表面光潔度最終所需尺寸。粗車刀具按其進(jìn)給方向能夠是右手型或是左手型。它們能夠有直、彎或偏置刀桿。31/742.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。與普通采取縱向進(jìn)給車削作業(yè)相反，那些側(cè)表面經(jīng)過采取橫向進(jìn)給產(chǎn)生。32/742.LatheCuttingToolsCutofftools.Cutofftools,whicharesometimescalledpartingtools,servetoseparatetheworkpieceintopartsand/ormachineexternalannulargrooves.切斷刀具：切斷刀具，有時(shí)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。33/742.LatheCuttingToolsThread-cuttingtools.Thread-cuttingtoolshaveeithertriangular,square,ortrapezoidalcuttingedges,dependinguponthecrosssectionofthedesiredthread.Also,theplaneanglesofthesetoolsmustalwaysbeidenticaltothoseofthethreadforms.螺紋切削刀具：螺紋切削刀具依據(jù)所需螺紋橫截面，有三角形、矩形或梯形切削刃。同時(shí)，這些刀具平面角必須一直與螺紋形狀平面角保持一致。34/742.LatheCuttingToolsThread-cuttingtoolshavestraightshanksforexternalthreadcuttingandareofthebent-shanktypewhencuttinginternalthreads.車外螺紋螺紋切削刀具為直刀桿，而車內(nèi)螺紋螺紋切削刀具則是彎刀桿。35/742.LatheCuttingToolsFormtools.Formtoolshaveedgesespeciallymanufacturedtotakeacertainform,whichisoppositetothedesiredshapeofthemachinedworkpiece.成形刀具：成形刀含有專門制成特定形狀刀刃，這種刀刃形狀與被加工工件所需外形恰好相反。36/742.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(jī)械方法固定于鋼質(zhì)刀桿上。37/742.LatheCuttingToolsFig.11.2indicatesanarrangementofthislattertype,whichincludesthecarbidetip,thechipbreaker,thepad,theclampingscrew(withawasherandanut),andtheshank.圖11.2所表示為機(jī)械式固定布置方式，它包含了硬質(zhì)合金刀尖、斷屑槽、襯墊、卡裝螺桿(帶有墊圈和螺母)及刀桿。38/742.LatheCuttingToolsAsthenamesuggests,thefunctionofthechipbreakeristobreaklongchipseverynowandthen,thuspreventingtheformationofverylongtwistedribbonsthatmaycauseproblemsduringthemachiningoperation.顧名思義，斷屑槽功效就是不時(shí)地折斷長(zhǎng)切屑，以防形成很長(zhǎng)可能會(huì)在機(jī)加工操作中引發(fā)問題纏繞切屑條。39/742.LatheCuttingToolsThecarbidetips(orceramictips)canhavedifferentshapes,dependinguponthemachiningoperationsforwhichtheyaretobeemployed.Thetipscaneitherbesolidorwithacentralthroughhole,dependingonwhetherbrazingormechanicalclampingisemployedformountingthetipontheshank.硬質(zhì)合金刀尖(或陶瓷刀尖)依據(jù)采取它們機(jī)加工操作，能夠有不一樣形狀。依據(jù)將刀尖裝配在刀桿上是經(jīng)過用銅焊還是機(jī)械卡裝，刀尖能夠是實(shí)心或是帶有中心通孔。40/74

Unit11LatheandTurning

1.Thelatheanditsconstruction2.LatheCuttingTools3.LatheOperations4.CuttingSpeedandFeed41/743.LatheOperationsLatheOperations車床操作Inthefollowingsection,wediscussthevariousmachiningoperationsthatcanbeperformedonaconventionalenginelathe.在下面這節(jié)中，要討論是能在傳統(tǒng)普通車床上進(jìn)行各種機(jī)加工作業(yè)。42/743.LatheOperationsItmustbeborneinmind,however,thatmoderncomputerizednumericallycontrolledlatheshavemorecapabilitiesandcandootheroperations,suchascontouring,forexample.Followingareconventionallatheoperations.然而，必須記住當(dāng)代計(jì)算機(jī)數(shù)控車床含有更多功效而且能夠進(jìn)行其它操作，比如仿型。下面是傳統(tǒng)車床操作。43/743.LatheOperations

Cylindricalturning.Cylindricalturningisthesimplestandthemostcommonofalllatheoperations.Asinglefullturnoftheworkpiecegeneratesacirclewhosecenterfallsonthelatheaxis;thismotionisthenreproducednumeroustimesasaresultoftheaxialfeedmotionofthetool.圓柱面車削：圓柱面車削是全部車床操作中最簡(jiǎn)單也是最普通。工件旋轉(zhuǎn)一整圈產(chǎn)生一個(gè)圓心落在車床主軸上圓；因?yàn)榈毒咻S向進(jìn)給運(yùn)動(dòng)這種動(dòng)作重復(fù)許屢次。44/743.LatheOperationsTheresultingmachiningmarksare,therefore,ahelixhavingaverysmallpitch,whichisequaltothefeed.Consequently,themachinedsurfaceisalwayscylindrical.所以，由此產(chǎn)生機(jī)加工痕跡是一條含有很小節(jié)距螺旋線，該節(jié)距等于進(jìn)給。所以機(jī)加工表面一直是圓柱形。45/743.LatheOperationsTheaxialfeedisprovidedbythecarriageorthecompoundrest,eithermanuallyorautomatically,whereasthedepthofcutiscontrolledbythecrossslide.軸向進(jìn)給經(jīng)過大拖板或復(fù)式刀架手動(dòng)或自動(dòng)提供，然而切削深度則由橫向滑板控制。46/743.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(依據(jù)工件材料可達(dá)0.25英寸或6毫米)和較小進(jìn)給。另首先，精車則最好采取很小進(jìn)給、較小切削深度(小于0.05英寸或0.4毫米)和較高切削速度。47/743.LatheOperationsFacing.Theresultofafacingoperationisaflatsurfacethatiseitherthewholeendsurfaceoftheworkpieceoranannularintermediatesurfacelikeashoulder.Duringafacingoperation,feedisprovidedbythecrossslide,whereasthedepthofcutiscontrolledbythecarriageorcompoundrest.端面車削：端面車削操作結(jié)果是將工件整個(gè)端部表面或者像軸肩之類中間環(huán)形表面加工平整。在端面車削操作中，進(jìn)給由橫向滑板提供，而切削深度則經(jīng)過大拖板或復(fù)式刀架控制。48/743.LatheOperationsFacingcanbecarriedouteitherfromtheperipheryinwardorfromthecenteroftheworkpieceoutward.Itisobviousthatthemachiningmarksinbothcasestaketheformofaspiral.端面車削既能夠從外表面向內(nèi)切削也能夠從工件中心往外切削。很顯著在這兩種情況下機(jī)加工痕跡都是螺線形式。49/743.LatheOperationsUsually,itispreferredtoclampthecarriageduringafacingoperation,sincethecuttingforcetendstopushthetool(and,ofcourse,thewholecarriage)awayfromtheworkpiece.Inmostfacingoperations,theworkpieceisheldinacTckoronafaceplate.通常在端面車削作業(yè)時(shí)習(xí)慣于采取夾住大拖板，這是因?yàn)榍邢髁A向于將刀具(當(dāng)然包含整個(gè)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。50/743.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(jìn)給。要采取前面已經(jīng)討論過切斷和開槽刀具。51/743.LatheOperationsBoringandinternalturning.Boringandinternalturningareperformedontheinternalsurfacesbyaboringbarorsuitableinternalcuttingtools.Iftheinitialworkpieceissolid,adrillingoperationmustbeperformedfirst.Thedrillingtoolisheldinthetailstock,andthelatteristhenfedagainsttheworkpiece.鏜孔和內(nèi)部車削：鏜孔和內(nèi)部車削經(jīng)過鏜桿或適當(dāng)內(nèi)部切削刀具在內(nèi)表面進(jìn)行。假如初始工件是實(shí)心，則必須首先進(jìn)行鉆孔作業(yè)。鉆孔刀具安裝在尾架上，然后對(duì)著工件進(jìn)給。52/743.LatheOperationsTaperturning.Taperturningisachievedbydrivingthetoolinadirectionthatisnotparalleltothelatheaxisbutinclinedtoitwithananglethatisequaltothedesiredangleofthetaper.Followingarethedifferentmethodsusedintaper-turningpractice:錐面車削：錐面車削經(jīng)過沿著與車床主軸不平行而傾斜成一個(gè)等于錐面所需角度方向進(jìn)刀來實(shí)現(xiàn)。下面是在實(shí)際錐面車削中采取不一樣方法：53/743.LatheOperations(1)Rotatingthediscofthecompoundrestwithanangleequaltohalftheapexangleofthecone.Feedismanuallyprovidedbycrankingthehandleofthecompoundrest.Thismethodisrecommendedfortaperturningofexternalandinternalsurfaceswhenthetaperangleisrelativelylarge.將復(fù)式刀架盤旋轉(zhuǎn)一個(gè)等于圓錐體頂角二分之一角度。經(jīng)過搖動(dòng)復(fù)式刀架操縱柄手動(dòng)提供進(jìn)給。當(dāng)錐角相對(duì)較大時(shí)切削外錐面和內(nèi)錐面推薦使用這種方法。54/743.LatheOperations(2)Employingspecialformtoolsforexternal,veryshort,conicalsurfaces.Thewidthoftheworkpiecemustbeslightlysmallerthanthatofthetool,andtheworkpieceisusuallyheldinachuckorclampedonafaceplate.Inthiscase,onlythecrossfeedisusedduringthemachiningprocessandthecarriageisclampedtothemachinebed.對(duì)很短外錐面采取特殊成型刀具。工件寬度必須略小于刀具寬度，而且工件通常由卡盤支撐或夾緊在花盤上。在這種情況下，機(jī)加工作業(yè)時(shí)只有橫向進(jìn)給而大拖板則夾緊在床身上。55/743.LatheOperations(3)Offsettingthetailstockcenter.Thismethodisemployedforexternaltaperturningoflongworkpiecesthatarerequiredtohavesmalltaperangles(lessthan8°).Theworkpieceismountedbetweenthetwocenters;thenthetailstockcenterisshiftedadistanceSinthedirectionnormaltothelatheaxis.偏移尾架頂尖。對(duì)需要較小錐角(小于8°)較長(zhǎng)工件外錐面車削采取這種方法。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(dòng)一距離S。56/743.LatheOperations(4)Usingthetaper-turningattachment.Thismethodisusedforturningverylongworkpieces,whenthelengthislargerthanthewholestrokeofthecompoundrest.Theprocedurefollowedinsuchcasesinvolvescompletedisengagementofthecrossslidefromthecarriage,whichisthenguidedbythetaper-turningattachment.采取錐面車削附加裝置。這種方法用于車削很長(zhǎng)工件，其長(zhǎng)度大于復(fù)式刀架整個(gè)行程。在這種場(chǎng)所下要遵照步驟是將橫向滑板完全脫離大拖板，然后經(jīng)過錐面車削附加裝置進(jìn)行引導(dǎo)。57/743.LatheOperationsDuringthisprocess,theautomaticaxialfeedcanbeusedasusual.Thismethodisrecommendedforverylongworkpieceswithasmallconeangle,i.e.,8°through10°.在此作業(yè)中，能照常使用自動(dòng)軸向進(jìn)給。對(duì)含有較小錐角(即8°到10°)很長(zhǎng)工件推薦采取這種方法。58/743.LatheOperationsThreadcutting.Whenperformingthreadcutting,theaxialfeedmustbekeptataconstantrate,whichisdependentupontherotationalspeed(rpm)oftheworkpiece.Therelationshipbetweenbothisdeterminedprimarilybythedesiredpitchofthethreadtobecut.螺紋切削：在螺紋切削作業(yè)時(shí)，軸向進(jìn)給必須保持恒定速率，這取決于工件轉(zhuǎn)速(rpm)。二者之間關(guān)系基本上由被切削螺紋所需節(jié)距決定。59/743.LatheOperationsAspreviouslymentioned,theaxialfeedisautomaticallygeneratedwhencuttingathreadbymeansoftheleadscrew,whichdrivesthecarriage.Whentheleadscrewrotatesasinglerevolution,thecarriagetravelsadistanceequaltothepitchoftheleadscrew.如前所述，當(dāng)依靠驅(qū)動(dòng)大拖板絲桿切削螺紋時(shí)軸向進(jìn)給是自動(dòng)產(chǎn)生。絲桿旋轉(zhuǎn)一圈，大拖板就行進(jìn)等于絲桿節(jié)距一段距離。60/743.LatheOperationsConsequently,iftherotationalspeedoftheleadscrewisequaltothatofthespindle(i.e.,thatoftheworkpiece),thepitchoftheresultingcutthreadisexactlyequaltothatoftheleadscrew(絲桿).所以假如絲桿旋轉(zhuǎn)速度等于心軸轉(zhuǎn)速(即工件轉(zhuǎn)速)，生成切削螺紋節(jié)距就恰好等于絲桿節(jié)距。61/743.LatheOperationsThepitchoftheresultingthreadbeingcutthereforealwaysdependsupontheratiooftherotationalspeedsoftheleadscrewandthespindle:Pitchoftheleadscrew/Desiredpitchofworkpiece=rpmoftheworkpiece/rpmofleadscrew=spindle-to-carriagegearingratio.所以被切削生成螺紋節(jié)距總是取決于絲桿和心軸轉(zhuǎn)速比：絲桿節(jié)距/工件所需節(jié)距=工件轉(zhuǎn)速/絲桿轉(zhuǎn)速=心軸到大拖板傳動(dòng)比。62/743.LatheOperationsThisequationisusefulindeterminingthekinematiclinkagebetweenthelathespindleandtheleadscrewandenablesproperselectionofthegeartrain(輪系)betweenthem.這公式在決定車床心軸和絲桿之間運(yùn)動(dòng)學(xué)關(guān)系時(shí)很有用，而且提供了正確挑選它們之間輪系方法。63/743.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(duì)相對(duì)較長(zhǎng)工件也能安裝在兩個(gè)車床頂尖之間。使用刀具外形必須恰好與要切削螺紋輪廓一致，即三角形刀具必須用于三角形螺紋等等。64/743.LatheOperationsKnurling.Knurlingismainlyaformingoperationinwhichnochipsareproduced.Itinvolvespressingtwohardenedrollswithroughfilelikesurfacesagainsttherotatingworkpiecetocauseplasticdeformationoftheworkpiecemetal.滾花：滾花主要是一個(gè)不產(chǎn)生切屑成型操作。它使用兩個(gè)帶有粗銼式表面淬火滾輪壓在旋轉(zhuǎn)工件上使工件金屬產(chǎn)生塑性變形。65/743.LatheOperationsKnurlingiscarriedouttoproducerough,cylindrical(orconical)surfaces,whichareusuallyusedashandles.Sometimes,surfacesareknurledjustforthesakeofdecoration;therearedifferenttypesofpatternsofknurlsfromwhichtochoose.滾花用于生成粗糙圓柱(或圓錐)面，通慣用來作手柄。有時(shí)表面滾花只為裝飾之故；有不一樣滾花圖案類型可供選擇。66/74

Unit11LatheandTurning

1.Thelatheanditsconstruction2.LatheCuttingTools3.LatheOperations4.CuttingSpeedandFeed67/744.CuttingSpeedandFeedCuttingSpeedsandFeed切削速度和進(jìn)給Thecuttingspeed,whichisusuallygiveninsurfacefeetperminute(SFM),isthenumberoffeettraveledinthecircumferentialdirectionbyagivenpointonthesurface(beingcut)oftheworkpiecein1minute.