机械专业英语课件9

单词复习：上一课回顾1Lesson9GrindingMachines

磨床

重点词汇：2Paragraph1Grindingisachip-making(生成切屑的)metalcutting(金属切削)process,everybitasmuchasturningormilling,exceptthatitisperformedona"micro"level(微观范围)wherethechipsaretoosmalltobeeasilyseenandidentified.磨削是切屑加工的金属切削过程，除了切屑小得难以发现和识别以外其加工过程完全像车削（turning）和铣削(milling)。3Anotherdifferencebetweengrindinganditslarge-scale(宏观)cousins,isthatthegrinding"tools",whichareabrasive(磨削性的)particle,arenotuniformlyshapedandorientedinthecarrier(载体),beitawheel,stone,orsomeotherdevice.磨削与形成大尺寸切屑的切削方法相比另一个最基本的不同是磨削刀具，它是磨料颗粒，在载体上形状和方向均不一致，是砂轮形状、石头或其它装置。

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Inthemetalcuttingterms,grindingisahybridbetweenturningandmilling.从金属切削角度讲，磨削是车削和铣削的综合。

Likemilling,thegrindingtoolisinmotion,andliketurning,theworkpieceisalsonearlyalwaysmoving,althoughnotnecessarilyrotating.像铣削一样，磨削刀具（高速）运动，像车削一样，工件虽不一定旋转但也总是运动的。

5Thedistinctionbetweenrotatingworkpieces,andthosemovinginalinearoroscillatingfashionundergrindingtool,butotherwisefixed,definedthemostbasicdivisioningrindingapplications.与工件旋转的相比，在磨削刀具下面直线或往复运动的工件及其安装方式的差别形成了磨削的各基本类型。

6Theformerisgenericallydescribedas"cylindrical”grinding,whilethelateris"surface"grinding,eventhoughbothtypescanproduceprecisionsurfaceontheworkpiecewhichisnotnecessarilyroundorflat.前者称为外圆磨削，后者称为平面磨削，两种形式都能加工出粗糙工件的高精度表面。

7Paragraph3:Thefactthatboththetoolandworkpiecearenormallymovingmakesanalysisandcontrolofgrindingoperationsconsiderablymorecomplexthanisthecasewithturningormilling.工件和刀具通常都是运动的这一事实使得磨削的分析与控制与车削和铣削相比复杂得多。

8ThisisoneofthemainreasonswhymanygrindermanufacturersstilltendtodesignandbuildtheirownCNCcontrols.这也是磨削生产者倾向于设计和制造磨削（专用的）CNC系统的主要原因之一。

9Paragraph4:Manycylindricalgrindersarelaidoutonapatternsimilartoalathe.

许多外圆磨床（cylindricalgrinder）设计成与车床相似的样式。

10Insteadofatoolholder,theyhaveamechanismtofeedthegrindingwheel,butalltheotherelements:headstock,Tailstock,waysandbedarenormallyquiterecognizabletoanyonefamiliarwithturningmachines.代替刀夹（toolholder），由一个机构实现磨削砂轮的进给(feed)，而所有其它部件——主轴箱(headstock)、尾架(tailstock)、导轨(ways)和床身(bed)，通常都可以在车床上找到一个相似的部件。

11Themajordifference,however,isthattheentireworkholdingsystemusuallyismountedonasetofwayssoitcanbetraversedpastthewheelduringthegrindingoperating.主要区别在于整个工件夹持系统安装在一组导轨上，因此可以相对砂轮做轴向进给。12Paragraph5Typically,inanOD(OutsideDiameter)cylindricalgrinderthewheelheadisfedradiallyintotheworkpiece,whichmayeitherremainstationaryorbereciprocatedpastit.在外圆磨床上，砂轮沿径向对工件进给，工件或许保持静止或许（轴向）往复运动。13Whentheworkpiecereciprocates,infeedmotionsaretypicallymadeonlyattheendofeachstroke.工件往复运动时，径向进给只是在每个行程(stroke)的端部进行。

14Paragraph6Thethirdmajortypeofcylindricalgrinderisthe"centerless"(无心)design,whichhasnodirectanalogintheworldofturning.第三种主要形式的磨床是无心(centerless)磨床，所有车床没有与它相似的。

15Inacenterlessgrinder(无心磨床),theworkpieceisnotheldbyeithercentersorachuck(卡盘),butissupportedona"blade"(托板)betweenthegrindingwheelanda"regulating"wheel(导轮),whichcontrolsitsrotation.在无心磨床上工件既不通过中心也不用卡盘夹持，而是放在砂轮和导轮之间的托板上，导轮控制它的旋转。16The“regulating”wheelcontrolstherotationalspeedoftheworkpiece,servingasbothadrivingmechanism,andabrakeiftheworkpiecepicksupspeedfromthegrindingwheel.导轮控制工件的旋转速度，它是驱动机构，砂轮使工件的速度增大时，它又是一个制动器。

The"blade"keepstheworkinpositionbetweenthetwowheels.托板使工件在两轮间就位。

Paragraph717Paragraph8Surfacegrinders(平面磨床)alsocomeinseveralbasicdesigns.平面磨床也有几种基本的设计。

Probablythemostcommonhasthewheelanditsassociatedmachinerymountedaboveareciprocatingtableorotherlinermotiondevicethatholdstheworkpiece.或许最一般的是砂轮及其相关的安装在往复运动的工作台上或其它直线运动装置上，用于夹持工件的机构。

18Thewheelisfedacrosstheaxisofreciprocation,whiletheworkpiecemovesbackandforthunderit.工件来回运动时，砂轮作轴向进给。19Paragraph9Conceptually,thistypeofgrinderissimilartoaplanerinwhichthetoolholderhasbeenreplacedbythegrindingwheel.从概念上讲，这种类型的磨床与（龙门）刨床(planer)相似，只是砂轮（装置）代替了刀夹。

Thegrindingisnormallydonewiththeperipheryofthewheelonthistypeofmachine.在这种机床上，磨床是通过砂轮的圆周(periphery)来工作的。20Grindingisaprocesswithsuchabroadapplicationrangethatmanyvariationsonthesebasicdesignthemeshavebeendevelopedovertheyears,andnoattemptwillbemadetocoverthemallhereindetail.磨削是应用相当广泛的工艺（方法），多年来开发了许多基于基本设计的工艺方法，这里不可能全部涵盖。

Paragraph1021Jiggrinders,ultra-precisionbearingballgrinders,andawholespectrumofotherspecializedgrinderscouldeacheasilybethetopicofanarticlelongerthanthisone.坐标磨床、超高精轴承球磨床和其它所有专用磨床，每一个都很容易写成一篇长于本文的文章。22Theprinciples,however,areessentiallyuniversalandshouldbeapplicablewithslightmodificationtovirtuallyanygrindingapplicationyoumayhave.而原理基本上是一样的，几乎所有磨削加工余量都很小。23Paragraph11Onetypeofspecialtygrinderthatdoesmeritbriefmentionisthetoolandcuttergrinder(工具磨床),which,asitsnameimplies,isdesignedforsharpening(刃磨)andre-sharpening(修磨)cuttingtools.一种值得一提的专用磨床是工具磨床，顾名思义，它是用来磨切削刀具的。24Thesemachinesareessentiallyhybridsincorporatingfeaturesofbothcylindricalandsurfacegrinders,whicharenecessaryforthespecializedtaskstheyarerequiredtoperform.这种磨床集外圆磨床和平面磨床于一身，对于我们要完成的一些特殊任务是非常必要的。

25Regardlessofthetypeofgrinder,themostimportantattributesitmusthavearerigidityandstability.不管哪种磨床，必须具有的最重要属性是刚度和稳定性。

Paragraph1226Thisisparticularlytrueincreepfeed(慢进给磨削)applications,aspecialformofgrindingwhichisperformedinasinglepass(一次走刀),withaveryhighdepthofcut,andlowworkspeed.在缓进给磨削中表现尤为突出，这是一种特殊的磨削方式，单走刀完成加工，切削深度很大，工件（进给）速度较低。27Properlyapplied,creepfeedgrindingcancutoverallmachiningtimebyupto50%withnolessofdimensionalorgeometricprecisionorsurfacefinishquality(表面质量).缓进给磨削削减全部磨削加工时间高达50%，而尺寸精度、形位精度和表面质量不降低。

28Toachievetheseresults,however,thegrindermustbedesignedspeciallyforcreepapplications,sincethetechniqueisparticularlysensitivetostaticanddynamicstabilityofthemachineandrequiresuptothreetimesthespindlepowerofacomparableconventionalgrindingprocess.为达到这一目的，磨床必须面向缓进给磨削专门设计，因为静态或动态稳定性对技术要求非常高，需要的主轴（砂轮）动力可达传统工艺的三倍。

Paragraph1329Creepfeedalsorequiresspecialdressing(砂轮修磨)capacities,carefulattentiontowheel"hardness”,goodcoolantcontrol,andagreatdealofexperience-basedprocessknowledge.

缓进给磨削同时还要求特殊的修整能力，特别是砂轮的硬度，好的冷却系统，积累起来的丰富的工艺知识。

30Creepfeed,likeallothermetalworkingtechnologies,offerssignificantadvantagesforspecificapplicationswhenproperlyapplied.像其它的金工技术一样，缓进给磨削在一些特殊场合有很大的优越性。

Itisnotapanacea,anditisnottheanswertoeverygrindingproblem.但它不是灵丹妙药，也不是任何磨削问题都能解决。

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