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1英文原文BASICMACHININGOPERATIONSMACHININGTOOLSHAVEEVOLVEDFROMTHEEARLYFOOT–POWEREDLATHEEGYPTIANSANDJOHNWILKINSON’SBORINGMILLTHEYAREDESIGNEDTOPROVIDERIGIDSUPPORTFORBOTHTHEWORKPIECEANDTHECUTTINGTOOLANDCUTTINGTOOLANDCANPRECISELYCONTROLTHEIRRELATIVEPOSITIONSANDTHEVELOCITYOFTHETOOLWITHRESPECTTOTHEWORKPIECEBASICALLY,INMETALCUTTING,ASHARPENEDWEDGESHAPEDTOOLREMOVESARATHERNARROWSTRIPOFMETALFROMTHESURFACEOFADUCTILEWORKPIECEINTHEFROMOFASEVERELYDEFORMEDCHIPTHECHIPISWASTEPRODUCTTHATISWORKPIECEINTHEFROMOFASEVERELYDEFORMEDCHIPISAWASTEPRODUCTTHATISCONSIDERABLYSHORTERTHANTHEWORKPIECEFROMWHICHITCAMEBUTWITHACORRESPONDINGINCREASEINTHICKNESSOFTHEUNCUTCHIPTHEGEOMETRICALSHAPEOFTHEMACHINESURFACEDEPENDSONTHESHAPEOFTHETOOLANDITSPATHDURINGTHEMACHININGOPRATIONMOSTMACHINEOPERATIONSPRODUCEPARTSOFDIFFERINGGEOMETRYIFAROUGHCYLINDRICALWORKPIECEREVOLVESABOUTACENTRALAXISANDTOOLPENETRATESBENEATHITSSURFACEANDTRAVELSPARALLELTOTHECENTEROFROTATION,ASURFACEOFREVOLUTIONISPRODUCED,ANDTHEOPERATIONISCALLEDTURNINGIFAHOLLOWTUBEISONTHEMACHINEDONTHEINSIDEINASIMILARMANNER,THEOPERATIONISCALLEDBORINGPRODUCINGANEXTERNALCONICALSURFACEOFUNIFORMLYVARYINGDIAMETERISCALLEDTAPERTURNINGIFTHETOOLPOINTTRAVELSINAPATHOFVARYINGRADIUS,ACONTOUREDSURFACELIKETHATOFBOWLINGPINCANBEPRODUCED；OR,IFTHEPIECEISSHORTENOUGHANDTHESUPPORTISSUFFICIENTLYRIGID,ACONTOUREDSURFACECOULDBEPRODUCEDBYFEEDINGASHAPEDTOOLNORMALTOTHEAXISOFROTATIONSHORTTAPEREDORCYLINDRICALSURFACESCOULDALSOBECONTOURFORMEDFLATORPLANESURFACEAREFREQUENTLYREQUIREDTHEYCANBEGENERATEDBYRADIALTURNINGORFACING,INWHICHTHETOOLPOINTMOVESNORMALTOTHEAXISOFROTATIONINOTHERCASES,ITISMORECONVENIENTTOHOLETHEWORKPIECESTEADYANDRECIPROCATETHETOOLACROSS,ITISSERIESOFSTRAIGHTLINECUTSWITHACROSSWISEFEEDINCREMENTBEFOREEACHCUTTINGSTROKETHISOPERATIONISCALLEDPLANNINGANDISCARRIEDOUTONASHAPERFORLARGERPIECESITISEASIERTOKEEPTHETOOLSTATIONARYANDDRAWTHEWORKPIECEUNDERITASINPLANNINGTHETOOLISFEDATEACHRECIPROCATIONCONTOUREDSURFACESCANBEPRODUCEDBYUSINGSHAPEDTOOLSMULTIPLEEDGEDTOOLSCANALSOBEUSEDDRILLINGUSESATWINEDGEDFLUTEDTOOLFORHOLESWITHDEPTHSUPTO5TO10TIMESTHEDRILLDIAMETERWHETHERTHEDRILLTURNSORTHEWORKPIECEROTATES,RELATIVEMOTIONBETWEENTHECUTTINGEDGEANDTHEWORKPIECEISTHEIMPORTANTFACTORINMILLINGOPERATIONSAROTARYCUTTERWITHANUMBEROFCUTTINGEDGESENGAGESTHEWORKPIECE,WHICHMOVESSLOWLYWITHRESPECTTOTHECUTTERPLANEORCONTOUREDSURFACESMAYBEPRODUCED,DEPENDINGONTHEGEOMETRYOFTHECUTTERANDTHETYPEOFFEEDHORIZONTALORVERTICALAXESOFROTATIONMAYBEUSED,ANDTHEFEEDOFTHEWORKPIECEMAYBEINANYOFTHETHREECOORDINATEDIRECTIONSBASICMACHINETOOLSMACHINETOOLSAREUSEDTOPARTOFASPECIFIEDGEOMETETRICALSHAPEANDPRECISESIZEBYREMOVINGMETALFROMADUCTILEMATERIALINTHEFORMCHIPSTHELATTERAREAWASTEPRODUCTANDVARYFROMLONGCONTINUOUSRIBBONSOFADISPOSALPOINTOFVIEW,TOEASILYHANDEDWELLBROKENCHIPSRESULTINGFROMCASTIRONMACHINETOOLSPERFORMFIVEBASICMETALREMOVEPROCESSESTURNING,PLANNING,DRILLING,MILLING,ANDGRINDINGALLOTHERMETALREMOVALPROCESSESAREMODIFICATIONSOFTHESEFIVEBASICPROCESSESFOREXAMPLE,BORINGISINTERNALTURNING；REAMING,TAPPING,ANDCOUNTERBORINGMOLLIFYDRILLEDHOLESANDARERELATEDTODRILLING；HOBBLINGANDGEARCUTTINGAREFUNDAMENTALLYMILLINGOPERATIONS；HACKSAWINGANDBROACHINGAREAFROMOFPLANNINGANDHONING；LAPPING,SUPERFINISHING,POLISHING,ANDBUFFINGAREVARIANTSOFGRINDINGORABRASIVEREMOVALOPERATIONSTHEREFORE,THEREAREONLYFOURTYPESOFBASICMACHINETOOLS,WHICHUSECUTTINGTOOLSOFSPECIFICCONTROLLABLEGEOMETRYTHEGRINDINGPROCESSFORMSCHIPS,BUTTHEGEOMETRYOFTHEABRASIVEGRAINISUNCONTROLLABLETHEAMOUNTANDRATEOFMATERIALREMOVEDBYTHEVARIOUSMACHININGPROCESSESMAYBELARGE,ASINHEAVYTURNINGOPERATIONS,OREXTREMELYSMALL,ASINLAPPINGORSUPERFINISHINGOPERATIONSWHEREONLYTHEHIGHSPOTSOFASURFACEAREREMOVEDAMACHININGTOOLPERFORMSTHREEMAJORFUNCTIONS1ITRIGIDLYSUPPORTSTHEWORKPICEORITSHOLDERANDTHECUTTINGTOOL；2ITPROVIDESRELATIVEMOTIONBETWEENTHEWORKPICEANDTHECUTTINGTOOL；3ITPROVIDESARANGEOFFEEDSANDSPEEDSUSUALLYRANGINGFROM4TO32CHOICESINEACHCASE2SPEEDANDFEEDSINMACHININGSPEEDS,FEEDS,ANDDEPTHPFCUTARETHETHREEMAJORVARIABLESFORECONOMICALMACHININGOTHERVARIABLESARETHEWORKANDTOOLMATERIALS,COOLANTANDGEOMETRYOFTHECUTTINGTOOLTHERATEOFMETALREMOVALANDPOWERREQUIREDFORMACHININGDEPENDUPONTHESEVARIABLESTHEDEPTHSOFCUT,FEED,ANDCUTTINGSPEEDAREMACHINESETTINGTHATMUSTBEESTABLISHEDINANYMETALCUTTINGOPERATIONTHEYALLAFFECTTHEFORCES,THEPOWER,ANDTHERATEOFMETALREMOVALTHEYCANBEDEFINEDBYCOMPARINGTHEMTOTHENEEDLEANDRECORDOFAPHONOGRAPHTHECUTTINGSPEEDVISREPRESENTEDBYTHEVELOCITYOFTHERECORDSURFACERELATIVETOTHENEEDLEINTHETONEARMATANYINSTANTFEEDISREPRESENTEDBYTHEADVANCEOFTHENEEDLERADIALLYINWARDPERREVOLUTION,ORISTHEDIFFERENCEINPOSITIONBETWEENTWOADJACENTGROOVESTHEDEPTHOFCUTISTHEPENETRATIONOFTHENEEDLEINTOTHERECORDORTHEDEPTHOFTHEGROOVESTURNINGONLATHECENTERSTHEBASICOPERATIONSOPERATIONSPERFORMEDONANENGINELATHEAREILLUSTRATEDINFIG113THOSEOPERATIONSPERFORMEDONEXTERNALSURFACESWITHASINGLEPOINTCUTTINGTOOLARECALLEDTURNINGEXCEPTFORDRILLING,REAMING,ANDTAPPING,THEOPERATIONSONINTERNALSURFACESAREALSOPERFORMEDBYASINGLEPOINTCUTTINGTOOLALLMACHININGOPERATE,INCLUDINGTURNINGANDBORING,CANBECLASSIFIEDASROUGHING,FINISHING,ORSEMIFINISHINGTHEOBJECTIVEOFAROUGHINGOPERATIONISTOREMOVETHEBULKOFTHEMATERIALASRAPIDLYANDASEFFICIENTLYASPOSSIBLE,WHILELEAVINGASMALLAMOUNTOFMATERIALONTHEWORKPIECEFORTHEFINISHINGOPERATIONFINISHINGOPERATIONSAREPERFORMEDTOOBTAINTHEFINALSIZE,SHAPE,ANDSURFACEFINISHONTHEWORKPIECESOMETIMESASEMIFINISHINGOPERATIONWILLPRECEDETHEFINISHINGOPERATIONTOLEAVEASMALLPREDETERMINEDANDUNIFORMAMOUNTOFSTOCKONTHEWORKPIECETOBEREMOVEDBYTHEFINISHINGOPERATIONGENERALLY,LONGERWORKPIECESARETURNEDWHILESUPPORTEDONONEORTWOLATHECENTERSCONESHAPEDHOLES,CALLEDCENTERHOLES,WHICHFITTHELATHECENTERSAREDRILLEDINTHEENDOFTHEWORKPIECEUSUALLYALONGTHEAXISOFTHECYLINDRICALPARTTHEENDOFTHEWORKPIECEADJACENTTOTHETAILSTOCKISALWAYSSUPPORTEDBYATAILSTOCKCENTER,WHILEENDNEARTHEHEADSTOCKMAYBESUPPORTEDBYAHEADSTOCKCENTERORHELDINACHUCKTHEHEADSTOCKENDOFTHEWORKPIECEMAYBEHELDINAFOURJAWCHUCK,ORINACOLLETTYPECHUCKTHISMETHODHOLDSTHEWORKPIECEFIRMLYANDTRANSFERSTHEPOWERTOTHEWORKPIECESMOOTHLY；THEADDITIONALSUPPORTTOTHEWORKPIECEPROVIDEDBYTHECHUCKLESSENSTHETENDENCYFORCHATTERTOOCCURWHENCUTTINGPRECISERESULTCANBEOBTAINEDWITHTHISMETHODIFCAREISTAKENTOHOLDTHEWORKPIECEACCURATELYINTHECHUCKVERYPRECISERESULTSCANBEOBTAINEDBYSUPPORTINGTHEWORKPIECEBETWEENTWOCENTERSALATHEDOGISCLAMPEDTOTHEWORKPIECE；TOGETHERTHEYAREDRIVENBYTHEDRIVERPLATEMOUNTEDONTHESPINDLENOSEONEENDOFTHEWORKPIECEISMACHINED；THENTHEWORKPIECECANBETURNEDAROUNDINTHELATHETOMACHINETOOTHERENDTHECENTERHOLESINTHEWORKPIECESERVEASPRECISELOCATINGSURFACESASWELLASBEARINGSURFACESTOCARRYTHEWEIGHTOFTHEWORKPIECEANDTORESISTTHECUTTINGFORCESAFTERTHEWORKPIECEHASBEENREMOVEFROMTHELATHEFORANYREASON,THECENTERHOLESWILLACCURATELYALIGNTHEWORKPIECEBACKINTHELATHEORINANOTHERLATHE,ORINACYLINDRICALGRINDINGMACHINETHEWORKPIECEMUSTNEVERBEHELDATTHEHEADSTOCKENDBYBOTHACHUCKANDALATHECENTERWHILEATFIRSTTHOUGHTTHISSEEMSLIKEAQUICKMETHODOFALIGNINGTHEWORKPIECEINTHECHUCK,THISMUSTNOTBEDONEBECAUSEITISNOTPOSSIBLETOPRESSEVENLYWITHTHEJAWSAGAINSTTHEWORKPIECEWHILEITISALSOSUPPORTEDBYTHECENTERTHEALIGNMENTPROVIDEDBYTHECENTERWILLNOTBEMAINTAINEDANDTHEPRESSUREOFTHEJAWSMAYDAMAGETHECENTERHOLE,THELATHECENTER,ANDPERHAPSEVENTHELATHESPINDLECOMPENSATINGORFLOATINGJAWCHUCKSUSEDALMOSTEXCLUSIVELYONHIGHPRODUCTIONWORKPROVIDEANEXCEPTIONTOTHESTATEMENTSMADEABOVETHESECHUCKSAREREALLYWORKDRIVERSANDCANNOTBEUSEDFORTHESAMEPURPOSEASORDINARYTHREEORFOURJAWCHICKSWHILEVERYLARGEDIAMETERWORKPIECEARESOMETIMESMOUNTEDONTWOCENTERS,THEYAREPREFERABLYHELDATTHEHEADSTOCKENDBYFACEPLATEJAWSTOOBTAINTHESMOOTHPOWERTRANSMISSION；MOREOVER,LARGELATHEDOGSTHATAREADEQUATETOTRANSMITTHEPOWERNOTGENERALLYAVAILABLE,ALTHOUGHTHEYCANBEMADEASASPECIALFACEPLATEJAWSARELIKECHUCKJAWSEXCEPTTHATTHEYAREMOUNTEDONAFACEPLATE,WHICHHASLESSOVERHANGFROMTHESPINDLEBEARINGSTHANALARGECHUCKWOULDHAVEBORINGTHEOBJECTIVEOFBORINGAHOLEINALATHEIS31、TOENLARGETHEHOLE2、TOMACHINETHEHOLETOTHEDESIREDDIAMETER3、TOACCURATELYLOCATETHEPOSITIONOFTHEHOLE4、TOOBTAINASMOOTHSURFACEFINISHINTHEHOLETHEMOTIONOFTHEBORINGTOOLISPARALLELTOTHEAXISOFTHELATHEWHENTHECARRIAGEISMOVEDINTHELONGITUDINALDIRECTIONANDTHEWORKPIECEREVOLVESABOUTTHEAXISOFTHELATHEWHENTHESETWOMOTIONSARECOMBINEDTOBOREAHOLE,ITWILLBECONCENTRICWITHTHEAXISOFROTATIONOFTHELATHETHEPOSITIONOFTHEHOLECANBEACCURATELYLOCATEDBYHOLDINGTHEWORKPIECEINTHELATHESOTHATTHEAXISABOUTWHICHTHEHOLEISTOBEMACHINEDCOINCIDESWITHTHEAXISOFROTATIONOFTHELATHEWHENTHEBORINGOPERATIONISDONEINTHESAMESETUPOFTHEWORKTHATISUSEDTOTURNANDFACEIT,PRACTICALLYPERFECTCONCENTRICITYANDPERPENDICULARITYCANBEACHIEVEDTHEBORINGTOOLISHELDINABORINGBARWHICHISFEDTHROUGHTHEHOLEBYCARRIAGEVARIATIONSOFTHISDESIGNAREUSED,DEPENDINGONTHEJOBTOBEDONETHELEADANGLEUSED,IFANY,SHOULDALWAYSBESMALLALSO,THENOSERADIUSOFTHEBORINGTOOLMUSTNOTBETOOLARGETHECUTTINGSPEEDUSEDFORBORINGCANBEEQUALTOTHESPEEDFORTURNINGHOWEVER,WHENTHESPINDLESPEEDOFTHELATHEISCALCULATED,THEFINISHED,ORLARGEST,BOREDIAMETERSHOULDBEUSEDTHEFEEDRATEFORBORINGISUSUALLYSOMEWHATLESSTHANFORTURNINGTOCOMPENSATEFORTHERIGIDITYOFTHEBORINGBARTHEBORINGOPERATIONISGENERALLYPERFORMEDINTWOSTEPS；NAMELY,ROUGHBORINGANDFINISHBORINGTHEOBJECTIVEOFTHEROUGHBORINGOPERATIONISTOREMOVETHEEXCESSMETALRAPIDLYANDEFFICIENTLY,ANDTHEOBJECTIVEOFTHEFINISHBORINGOPERATIONISTOOBTAINTHEDESIREDSIZE,SURFACEFINISH,ANDLOCATIONOFTHEHOLETHESIZEOFTHEHOLEISOBTAINEDBYUSINGTHETRIALCUTPROCEDURETHEDIAMETEROFTHEHOLECANBEMEASUREDWITHINSIDECALIPERSANDOUTSIDEMICROMETERCALIPERSBASICMEASURINGINSTRUMENT,ORINSIDEMICROMETERCALIPERSCANBEUSEDTOMEASURETHEDIAMETERDIRECTLYCOREDHOLESANDDRILLEDHOLESARESOMETIMESECCENTRICWITHRESPECTTOTHEROTATIONOFTHELATHEWHENTHEBORINGTOOLENTERSTHEWORK,THEBORINGBARWILLTAKEADEEPERCUTONONESIDEOFTHEHOLETHANONTHEOTHER,ANDWILLDEFLECTMOREWHENTAKINGTHISDEEPERCUT,WITHTHERESULTTHATTHEBOREDHOLEWILLNOTBECONCENTRICWITHTHEROTATIONOFTHEWORKTHISEFFECTISCORRECTEDBYTAKINGSEVERALCUTSTHROUGHTHEHOLEUSINGASHALLOWDEPTHOFCUTEACHSUCCEEDINGSHALLOWCUTCAUSESTHERESULTINGHOLETOBEMORECONCENTRICTHANITWASWITHTHEPREVIOUSCUTBEFORETHEFINALE,FINISHCUTISTAKEN,THEHOLESHOULDBECONCENTRICWITHTHEROTATIONOFTHEWORKINORDERTOMAKECERTAINTHATTHEFINISHEDHOLEWILLBEACCURATELYLOCATEDSHOULDERS,GROOVES,CONTOURS,TAPERS,ANDTHREADSAREALSOBOREDINSIDEOFHOLESINTERNALGROOVESARECUTUSINGATOOLTHATISSIMILARTOEXT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