數(shù)控技術概述

NUMERICALCONTROLTECHNOLOGYChapter1IntroductiontoNumericalControlTeacherXuCijun1387208295362956.Chapter1

INTRODUCTIONTONUMERICALCONTROL

1.1、FundamentalofNCTechnology1.2、ClassificationsofNCMachines1.3、FeaturesofNumericalControlandItsApplicationAreasCourseDescription:?NCisoneofthemostimportantachievementsinmechanicalengineeringfieldin20century.?Itisacrossingandintegratingtechnologycomprisingofcomputertechnology,automaticcontroltechnology,informationtechnology,sensetechnology,andmachiningtechnology.?NumericalControlTechnologyhasbecameoneoftheimportanttechnicalbasicclassesofmechanicalengineeringspecialty.Toshibaevents.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.1、DevelopmentHistoryofNC

1946-thefirstcomputerappearedintheworld,whichliftthecurtainonthemankindintoinformationtime.

1948-ParsonsCorporationbroughtforwardusingcomputertocontrolmachinewhentheymachinedthesurfacecontoursofairfoilshape.ParsonsCorporationwasamini-helicoptermanufacturer.Themachiningaccuracyoftheairfoilshapewas±0.0381mm.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.1、DevelopmentHistoryofNC

UnderthesupportbytheU.SAirForceResponsedbytheServomechanismsLaboratoryattheMIT(MassachusettsInstituteofTechnology).Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.1、DevelopmentHistoryofNC

Threeyearslater,in1952

MITandParsonsCorporationcooperatedwitheachother,anddevelopedthefirstNCmachinewhichnamedCincinnatiHydrotelmillingmachine.Background,timeandplace.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.1、DevelopmentHistoryofNCThefirstgeneration,1952~1955vacuumtubes,electricalrelaysandcomplicatedmachinecontrolinterfaces.Thesecondgeneration,1955~1959miniatureelectronictubes,transistors.Thethirdgeneration,1959~1965smallscaleintegratedcircuits..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.1、DevelopmentHistoryofNCAbovethreegenerations,

theirNCfunctionswereperformedbyhardware(electroniccircuits),sowecallthem“hardwiredNC”(硬線數(shù)控)

1955

1959

1965.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.1、DevelopmentHistoryofNCThefourthgeneration,1970s(1970~1974)minicomputers.(CNC)Thefifthgeneration,1974-microprocessor.1979(VLIC)(MCNC)1994~PC-NC..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.1、DevelopmentHistoryofNCAfterthefourthgenerations,

theirNCfunctionswereperformedbysoftware(basedoncomputer),sowecallthem“softwiredNC”or“computernumericalcontrol”(計算機數(shù)控CNC)

1970

1974

1994.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.2ConceptofNCandCNC1、NC(NumericalControl,數(shù)字控制)

NumericalControl（NC）isaformofprogrammableautomationinwhichthemechanicalactionsofamachinetoolorothermachinesarecontrolledbyaprogramcontainingcodedalphanumericdata..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.2ConceptofNCandCNC2、NumericalControlTechnology,(數(shù)控技術)

ItmeansthetechnologywhichadoptsNCmethodstocontrolaworkprocesstorealizetheautomation..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.2ConceptofNCandCNC3、NumericalControlMachineTools,(數(shù)控機床)

Itis

akindofmachinetools

whichadoptsthenumericalcontroltechnologytorealizetheworkprocessautomation.ItisatypicalexampleofNCapplication..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.2ConceptofNCandCNC4、NumericalControlSystem,(數(shù)控系統(tǒng))

Itis

theequipmentwhichcanrealizethenumericalcontrol..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.2ConceptofNCandCNC5、CNC(ComputerNumericalControl,計算機數(shù)控)

Themachinecontrolunitsarebasedoncomputertechnology..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineTools

Thecontrolsystemofanumericallycontrolledmachinetoolcanhandlemanytaskscommonlydonebytheoperatorofaconventionalmachine.Thesystemhastheabilitytoperformthecontrolfunctionsthroughthenumericalinputinformation,whichisthecontrolprogram,alsocalledthepartprogram..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineToolsTheworkprocessofNCisshownastherightfigure.PartdrawingPartprogramControlcomputerServo-driveunitMachinetoolPartFirstly,thepartprogrammershouldstudythepartdrawingandtheprocesschart..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineToolsTheworkprocessofNCisshownintherightfigure.PartdrawingPartprogramControlcomputerServo-driveunitMachinetoolPartThenthepartprogrammershouldpreparethecontrolprogramonastandardforminthespecifiedformat.Itcontainsallthenecessarycontrolinformation.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineToolsTheworkprocessofNCisshownintherightfigure.PartdrawingPartprogramControlcomputerServo-driveunitMachinetoolPartNextthepartprogramistransferredintothecontrolcomputer(MDI).thecomputerconvertseachcommandintothesignalthattheservo-driveunitneeds.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineToolsTheworkprocessofNCisshownintherightfigure.PartdrawingPartprogramControlcomputerServo-driveunitMachinetoolPartAtlast,theservo-driveunitdrivesthemachinetooltomanufacturethefinishedpart.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineTools

AtypicalNCmachinetoolhasfivefundamentalunits:(1)theinputmedia;(2)themachinecontrolunit;(3)theservo-driveunit;(4)thefeedbacktransducer;(5)themechanicalmachinetoolunit.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineTools

Thegeneralrelationshipamongthefivecomponentsisillustratedinthebelow.MachineControlunitInputmediaServo-driveMachinetoolFeedbackTransducer.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineToolsMachineControlunitInputmediaServo-driveMachinetoolFeedbackTransducerTheinputmediacontainstheprogramofinstructions,itisthedetailedstep-by-stepcommandsthatdirecttheactionsofthemachinetool;theprogramofinstructionsiscalledapartprogram..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineToolsMachineControlunitInputmediaServo-driveMachinetoolFeedbackTransducerTheprogramiscodedonasuitablemediumforsubmissiontothemachinecontrolunit.Thecommonmediuminthepastispunchedtape,magnetictape:.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineToolsMachineControlunitInputmediaServo-driveMachinetoolFeedbackTransducerNow,Thecommonmediumisdiskette,electronictransferfromacomputer(RS232C):.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineToolsMachineControlunitInputmediaServo-driveMachinetoolFeedbackTransducer

MCUconsistsofamicrocomputerandrelatedcontrolhardwarethatstorestheprogramofinstructionsandexecutesitbyconvertingeachcommandintomechanicalactionsofmachinetool,onecommandatatime.theMCUincludessystemsoftware,calculationalgorithm,andtransitionsoftwaretocoverttheNCpartsprogramintoausableformatfortheMCU.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.1.3BasicComponentsofNCMachineToolsMachineControlunitInputmediaServo-driveMachinetoolFeedbackTransducerSpindleandfeeddrivemotorsandtheirservo-amplifiersarethecomponentsoftheservo-driveunit.TheMCUprocessesthedataandgeneratesdiscretenumericalpositioncommandsforeachfeeddriveandvelocitycommandforthespindledrive.ThenumericalcommandsareconvertedintosignalvoltagebytheMCUunitandsenttoservo-amplifiers,whichprocessandamplifythemtothehighvoltagelevelsrequiredbythedrivemotors.Thedrivesinmachinetoolsareclassifiedasspindleandfeeddrivemechanisms..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2CLASSIFICATIONSOFNCMACHINENumericalcontrolmachinesareclassifiedindifferentway:(1)ThetypesofNCmotioncontrolsystem;(2)Thetypeofservo-drivesystem;(3)ApplicationofNC.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.1TypesofNCMotionControlSystemMotioncontrolsystemsforNCcanbedividedintotwotypes:(1)Point-to-pointcontrolsystem(點位控制系統(tǒng));(2)Continuous(Contouring)pathcontrolsystem;（連續(xù)控制或輪廓控制系統(tǒng)）.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.1TypesofNCMotionControlSystem1.2.1.1Point-to-pointcontrolsystemPoint–topoint(positioning)controlinNCItisalsocalledPositioningcontrolsystem,Whichmovestheworktabletoaprogrammedlocationwithoutregardtothepathtakentogettothelocation.Thatistosay,thepathbetweenpointsisoflittleconcernandisnotparticularlycontrolled.Theprogramconsistsofaseriesofpointlocationsatwhichoperationsareperformed.Suchasdrillingorpunchingahole..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.1TypesofNCMotionControlSystem1.2.1.1point-to-pointcontrolsystemManyNCpoint–to-pointsystemscontainamorecomplexMCU.INtheseservos,positioningcommandsareevaluatedsimultaneouslysothatvectormotionintwoaxesispossible.Themovementsbetweenpointscanbedonealongstraightor450vectorspathsdeterminedbythemachinewaysorslides.Suchsystemsaresometimescalledstraight-cutcontrolsystem.（點位/直線）.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.1TypesofNCMotionControlSystem1.2.1.2ContouringControlSystem

Itisalsocalledcontinuouspathcontrolsystem,whichmanagesthesimultaneousmotion(resultantmotion)ofthecuttingtoolintwo,three,four,offiveaxesbyinterpolating(插補)theproperpathbetweenprescribedpoints.Itenablesthecuttingtooltogenerateangularsurfaces,two-dimensionalcurves,orthree-dimensionalcontoursintheworkpiece,suchasmillingandturningoperations..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.1TypesofNCMotionControlSystem1.2.1.3InterpolationTocutalongacircularpath,thecirclemustbedividedintoaseriesofstraight-linesegmentsthatapproximatethecircularpath.Thetooliscommandedtomachineeachlinesegmentinsuccessionsothatthemachinedsurfacecloselymatchesthedesiredshape..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.2TypesofNCServo-DriveSystem

TheprincipalfunctionofNCisthepositioningofthetoolorthemachinetableinaccordancewiththeprogrammeddata.IndustryhasdevelopedthreedifferenttypesofdrivesbasedonhowtheNCsystemaccomplishespositioning.Thesearetheopen-loop（開環(huán)）,theclosed-loop（閉環(huán)）andhalfclosed-loop（半閉環(huán)）drivesystem..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.2TypesofNCServo-DriveSystem1.2.2.1Open-LoopServo-DriveItisthesimplestandleastcostformofservo-drive.Itischaracterizedasasystemthatlacksfeedback.Thatis,onceaninputcontrolsignalissent,thereisnosensingdevicetoconfirmtheactionofthecontrolsignal.DrivingcircuitSteppingmotorWorktableLeadscrewPulsetrain.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.2TypesofNCServo-DriveSystem1.2.2.2Half-Closed-LoopServo-DriveItischaracterizedasasystemthattheindirectfeedbackmonitorstheoutputofservomotor.AlthoughthismethodispopularwithNCsystems,itisnotasaccurateasdirectfeedback,Thehalf-closed-loopsystemcomparesthecommandpositionsignalwiththedrivesignaloftheservomotor..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.2TypesofNCServo-DriveSystem1.2.2.2Half-Closed-LoopServo-DrivePositioncomparecircuitSpeedcontrolcircuitWorktableInstructionSpeedfeedbacksignalPositionfeedbacksignalLeadscrewServomotor.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.2TypesofNCServo-DriveSystem1.2.2.3Closed-LoopServo-DriveItischaracterizedasasystemthatthedirectfeedbackmonitorstheoutputofservomotor.Afeedbacksensordirectlymeasuresthepositionofworktable.Withitsdrivesignaloriginatedbytheworktable,Itisthepreferredsystembecauseitmonitorstheactualpositionoftheworktableonwhichthepartismounted.Itismoreaccurate;however,itsimplementationcostsarehigher..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.2TypesofNCServo-DriveSystem1.2.2.3Closed-LoopServo-DrivePositioncomparecircuitSpeedcontrolcircuitWorktableInstructionSpeedfeedbacksignalPositionfeedbacksignalLeadscrewServomotor.Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNCTheapplicationsofCNCaredividedintotwocategories:Machinetoolapplications;non-machinetoolapplications.

Itshouldbenotedthattheapplicationsarenotalwaysidentifiedbythename“numericalcontrol”,thistermisusedprincipallyinthemachinetoolindustry..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.1MachineToolApplicationThemostcommonapplicationsofNCareinmachinetoolcontrol,machiningwasthefirstapplicationofNC.Machiningisamanufacturingprocessinwhichthegeometryofworkisproducedbyremovingexcessmaterial.Bycontrollingtherelativemotionbetweenacuttingtoolandtheworkpiece,thedesiredgeometryiscreated..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.1MachineToolApplicationThecommonNCmachinetoolsarelistedinthefollowingalongwiththeirtypicalfeatures:NClathe(數(shù)控車床)Turningrequirestwo-axiscontinuouspathcontrol,eithertoproduceastraightcylindricalgeometryortocreateaprofile..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.1MachineToolApplicationNCboringmill(數(shù)控鏜銑床)horizontalorverticalspindle.Boringissimilartoturning,exceptthataninternalcylinderiscreatedinsteadofanexternalcylinder.Theoperationrequirescontinuouspath,two-axiscontrol...Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.1MachineToolApplicationNCdrillpress(數(shù)控鉆床)Thesemachinesusepoint-to-pointcontrolofworkheadandtwoaxiscontroloftheworktable.SomeNCdrillpresseshaveturretscontainingsixoreightdrillbits..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.1MachineToolApplicationNCmillingmachine(數(shù)控銑床)Itrequirescontinuouspathcontroltoperformstraightcutorcontouringoperations..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.1MachineToolApplicationNCgrindingmachine(數(shù)控磨床)Itisintendedforfinishingtreatmentofworkparts.Thegrindingmachineincludescylindrical-,surface-,internal-,spindle-,thread-,gear-andtool-grindingmachines..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.1MachineToolApplicationMachinecenter(加工中心)ItisdefinedasmultifunctionNCmachineswithautomatictoolchangerandtoolstorage.Ithastheabilitytoperformdrilling,turning,reaming,boring,milling,contouring,andthreadingoperationsonasinglemachine..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.1MachineToolApplicationMachinecenter(加工中心)Machiningcentersareclassifiedaseitherverticalorhorizontal.Verticalmachiningcenterscontinuetobewidelyacceptedandused,primarilyforflatpartsandwherethree-axismachiningisrequiredonthesurfaceofasinglepartsuchasthemoldandthedie.Horizontalmachiningcentersareparticularlyusedforthelarge,boxy,andheavyparts..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.1MachineToolApplicationMachinecenter(加工中心).Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.2Non-MachineToolApplicationPunchpressesforsheetmetalholepunching(數(shù)控沖床)Thetwo-axisNCoperationissimilartothatofadrillpressexceptthatholesareproducedbypunchingratherthanbydrilling..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.2Non-MachineToolApplicationPressesforsheetmetalbending(數(shù)控折彎機)Insteadofcuttingsheetmetal,thesesystemsbendsheetmetalaccordingtoprogrammedcommands..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.2Non-MachineToolApplicationWeldingmachine(數(shù)控焊接機)BothspotweldingandcontinuousarcweldingmachinesareavailablewithautomaticcontrolsbasedonNC..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.2Non-MachineToolApplicationThermalcuttingmachine(數(shù)控熱切割機)Suchasoxyfuelcutting(火焰切割),lasercutting(激光切割),andplasmaarccutting(等離子電弧切割).Thestockisusuallyflat;thustwo-axiscontrolisadequate.Somelasercuttingmachinescancutholesinpreformedsheetmetalstock,requiringfourorfiveaxiscontrol..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.2.3ApplicationofCNC1.2.3.2Non-MachineToolApplicationTubebendingmachine(數(shù)控彎管機)Automatictubebendingmachinesareprogrammedtocontrolthelocationandtheangleofthebend.Importantapplicationsincludeframesofbicyclesandmotorcycles..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.3FEATURESOFNCANDITSAPPLICATIONAREAS1.3.1AdvantagesandDisadvantagesofNCNChasmanybenefitsandadvantagesovermanualproductionmethods,butNCismoresophisticatedtechnologythanconventionalproductionmethods..Chapter1

INTRODUCTIONTONUMERICALCONTROL1.3.1AdvantagesandDisadvantagesofNCAdvantagesofNC(1)Greateraccuracyandrepeatability(2)Morecomplexpartgeometriesarepossible(3)Nonproductivetimeisreduced(4)Lowerscraprates(5)Inspectionrequirementsarereduced(6)Engineeringchangescanbea