第8-9次課UNIT11LatheandTurning市公開課一等獎省賽課微課金獎?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)、能同時被安裝刀具數(shù)量和自動化程度，車床—或更確切地說是車床類機床，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.即使車床類機床各種多樣，但它們在結(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。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)動無級調(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)過此孔進給。Also,thatholehasataperedsurfacetoallowmountingaplainlathecenter.Theoutersurfaceofthespindleisthreadedtoallowmountingofachuck,afaceplate,orthelike.同時，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)軌滑動鑄件，它有一定位裝置能讓整個尾架依據(jù)工件長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動鑄件，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出移動。18/741.ThelatheanditsconstructionThisisachievedthroughtheuseofahandwheelandascrew,aroundwhichanutfixedtothequillisengaged.Theholeintheopensideofthequillistaperedtoenablemountingoflathecentersorothertoolsliketwistdrillsorboringbars.Thequillcanbelockedatanypointalongitstravelpathbymeansofaclampingdevice（夾持機構(gòu)）.這經(jīng)過使用手輪和螺桿來到達，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路徑被鎖定在任何點。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/或橫向進給。它實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H形滑塊。20/741.ThelatheanditsconstructionThecarriagecanbemovedeithermanuallyormechanicallybymeansoftheapronandeitherthefeedrodortheleadscrew.大拖板能手動或者經(jīng)過溜板箱和光桿(進給桿)或絲桿(引導(dǎo)螺桿)機動。21/741.ThelatheanditsconstructionWhencuttingscrewthreads,powerisprovidedtothegearboxoftheapronbytheleadscrew.Inallotherturningoperations,itisthefeedrodthatdrivesthecarriage.Theleadscrewgoesthroughapairofhalfnuts,whicharefixedtotherearoftheapron.在切削螺旋時，動力經(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)動大拖板。絲桿穿過一對固定在溜板箱后部剖分螺母。22/741.ThelatheanditsconstructionWhenactuatingacertainlever,thehalfnutsareclamped

togetherandengagewiththerotatingleadscrewasasinglenut,whichisfed,togetherwiththecarriage,alongthebed.Whentheleverisdisengaged,thehalfnutsarereleasedandthecarriagestops.當(dāng)開動特定操作桿時，剖分螺母夾在一起作為單個螺母與旋轉(zhuǎn)絲桿嚙合，并帶動拖板沿著床身提供進給。當(dāng)操作桿脫離時，剖分螺母釋放同時大拖板停頓運動。23/741.ThelatheanditsconstructionOntheotherhand,whenthefeedrodisused,itsuppliespowertotheapronthroughawormgear.Thelatteriskeyedtothefeedrodandtravelswiththeapronalongthefeedrod,whichhasakeywayextendingtocoveritswholelength.另首先，當(dāng)使用光桿時則經(jīng)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。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。它與光桿和絲桿連接，能輕易并快速地經(jīng)過簡單轉(zhuǎn)換適當(dāng)操作桿選擇各種進給。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。因為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)運動距離能被控制，這距離就能夠被認為是進給。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。與普通采取縱向進給車削作業(yè)相反，那些側(cè)表面經(jīng)過采取橫向進給產(chǎn)生。32/742.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。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，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地折斷長切屑，以防形成很長可能會在機加工操作中引發(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)過用銅焊還是機械卡裝，刀尖能夠是實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)普通車床上進行各種機加工作業(yè)。42/743.LatheOperationsItmustbeborneinmind,however,thatmoderncomputerizednumericallycontrolledlatheshavemorecapabilitiesandcandootheroperations,suchascontouring,forexample.Followingareconventionallatheoperations.然而，必須記住當(dāng)代計算機數(shù)控車床含有更多功效而且能夠進行其它操作，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單也是最普通。工件旋轉(zhuǎn)一整圈產(chǎn)生一個圓心落在車床主軸上圓；因為刀具軸向進給運動這種動作重復(fù)許屢次。44/743.LatheOperationsTheresultingmachiningmarksare,therefore,ahelixhavingaverysmallpitch,whichisequaltothefeed.Consequently,themachinedsurfaceisalwayscylindrical.所以，由此產(chǎn)生機加工痕跡是一條含有很小節(jié)距螺旋線，該節(jié)距等于進給。所以機加工表面一直是圓柱形。45/743.LatheOperationsTheaxialfeedisprovidedbythecarriageorthecompoundrest,eithermanuallyorautomatically,whereasthedepthofcutiscontrolledbythecrossslide.軸向進給經(jīng)過大拖板或復(fù)式刀架手動或自動提供，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0.25英寸或6毫米)和較小進給。另首先，精車則最好采取很小進給、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)時習(xí)慣于采取夾住大拖板，這是因為切削力傾向于將刀具(當(dāng)然包含整個大拖板)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。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)表面進行。假如初始工件是實心，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。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等于錐面所需角度方向進刀來實現(xiàn)。下面是在實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)一個等于圓錐體頂角二分之一角度。經(jīng)過搖動復(fù)式刀架操縱柄手動提供進給。當(dāng)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。54/743.LatheOperations(2)Employingspecialformtoolsforexternal,veryshort,conicalsurfaces.Thewidthoftheworkpiecemustbeslightlysmallerthanthatofthetool,andtheworkpieceisusuallyheldinachuckorclampedonafaceplate.Inthiscase,onlythecrossfeedisusedduringthemachiningprocessandthecarriageisclampedtothemachinebed.對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，機加工作業(yè)時只有橫向進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。對需要較小錐角(小于8°)較長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工件，其長度大于復(fù)式刀架整個行程。在這種場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，能照常使用自動軸向進給。對含有較小錐角(即8°到10°)很長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，軸向進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)動大拖板絲桿切削螺紋時軸向進給是自動產(chǎn)生。絲桿旋轉(zhuǎn)一圈，大拖板就行進等于絲桿節(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=心軸到大拖板傳動比。62/743.LatheOperationsThisequationisusefulindeterminingthekinematiclinkagebetweenthelathespindleandtheleadscrewandenablesproperselectionofthegeartrain(輪系)betweenthem.這公式在決定車床心軸和絲桿之間運動學(xué)關(guān)系時很有用，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，對相對較長工件也能安裝在兩個車床頂尖之間。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：滾花主要是一個不產(chǎn)生切屑成型操作。它使用兩個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切削速度和進給Thecuttingspeed,whichisusuallygiveninsurfacefeetperminute(SFM),isthenumberoffeettraveledinthecircumferentialdirectionbyagivenpointonthesurface(beingcut)oftheworkpiecein1minute.