數(shù)控技術(shù)1 機(jī)電工程學(xué)院課件

數(shù)控技術(shù)1機(jī)電工程學(xué)院課件《NCTechnology》

Ch1introduction《NCTechnology》

Outline?Terms&basicconceptsHistoryofNCandCNC?NCversusCNC?BasicelementsofaCNCmachine?AdvantagesandlimitationofCNC?ModeofNCcontrolsystem《NCTechnology》

WhatisNC&CNC?NC:NumericalControl數(shù)控(技術(shù))CNC:ComputerNumericalControl計(jì)算機(jī)數(shù)控(技術(shù))NCmachinetool數(shù)控機(jī)床《NCTechnology》

PrincipleofNCmachinetool

Howtorealizemachining?relativemovement!WhatistheNCmachinetool?Theprogrammednumericalcommandsareusedtocontroltherelativemovementandactionsofmachinetool!《NCTechnology》

AnexleN003G90G01X+325.9Y+279.346Z-429.7S1000T02F500M07第三程序段絕對(duì)坐標(biāo)直線段加工終點(diǎn)坐標(biāo)主軸轉(zhuǎn)速2號(hào)刀具進(jìn)給速度冷卻液打開(kāi)《NCTechnology》

Computernumericalcontrol(CNC)istheprocessofmanufacturingmachinedparts.Productioniscontrolledandallocatedbyacomputerizedcontroller.Thecontrollerusesmotorstodriveeachaxisofamachinetoolandactuallyregulatesthedirection,speed,andlengthoftimeeachmotorrotates.Aprogrammedpathisloadedintothemachine'scomputerbytheoperatorandthenexecuted.Theprogramconsistsofnumericpointdatainconjunctionwithspecializedmachinecontrolcommandsandfunctioncodes.PrincipleofNCmachinetool

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TheworkprocessofNC《NCTechnology》

BasiccomponentsofCNCmachinetool《NCTechnology》

TheevolutionofNCTheprincipleofNCmanufacturinghasbeenevolvingsincetheIndustrialRevolution.NotuntilWorldWarIIdidindustrialistsrealizethattheycouldn'tmeetbothquantityandqualityrequirementsatthesametime.《NCTechnology》ENIACDuringWorldWarIItheUnitedStatesArmyBallisticResearchLabandtheUniversityofPennsylvaniacollaboratedondevelopmentofENIAC,theworld'sfirstdigitalcomputer.

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TheevolutionofNC

ToensurethatallU.S.militaryairplanesweremanufacturedidentically,theUnitedStatesAirForceinvitedseveralcompaniestodevelopandmanufacturenumericalcontrolsystemsthatcouldhandlethevolumeandrepeatability.ThefirstcontractwasawardedtotheParsonsCorporationofMichigan,whichthensubcontracteddevelopmentofaservosystemforthemachinetooltotheServomechanismLaboratoryatMIT《NCTechnology》

TheServoMechanismlaboratoryatMIT《NCTechnology》

TheevolutionofNCThespecificgoalsofdevelopingNC:IncreaseproductionImprovethequalityandaccuracyofmanufacturedpartsStabilizemanufacturingcosts

Manufactureandassemblecomplexpartsquickly《NCTechnology》

ThefirstNCmachineproducing

identicalparts《NCTechnology》TheevolutionofNCBy1960,NCwaswidelyacceptedandreadilyavailable.ThemajorityofthesefirstgenerationNCmachinetoolsrequiredcodedpapertapetorun.TheengineerswouldgenerateNCcodeontheircomputers,thenencodelongstripsofpapertapebypunchingholepatternsinthem.Later,theuseof“man-readable”solvedthisproblem《NCTechnology》

AnearlyNCpapertapereader《NCTechnology》

CNCDirectnumericalcontrolanddistributednumericalcontrol(DNC)describecommunicationstoamachinetoolfromaremotecomputer.《NCTechnology》

APTFrom1955to1960,MITalsodevelopedacomputer-assistedprogrammingsystemcalledautomaticallyprogrammedtools(APT).Thisprogramminglanguagewasdevelopedtoeasethetaskofcomplicatedthree-axisprogramming,mainlyintheaerospaceindustry.APTusesEnglish-likewordstodescribethegeometryandthetoolmotionsonapartprogram.《NCTechnology》

MICROCOMPUTERTECHNOLOGYThemoderncomputerisanelectronicmachinethatperformsmathematicalorlogicalcalculationsinaccordancewithapredeterminedsetofinstructions.從1974年開(kāi)始采用微型電子計(jì)算機(jī)控制的系統(tǒng)(MicrocomputerNumericalControl----MNC)《NCTechnology》

CURRENTDEVOLOPMENTOPENCNC《NCTechnology》

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AdvantagesandLimitationsofCNC《NCTechnology》

AdvantagesandLimitationsofCNC《NCTechnology》

請(qǐng)大家欣賞機(jī)床發(fā)展的歷史回顧《NCTechnology》

NCSYSTEMCLASSIFICATIONBasedonmodeofcontrolBasedontypesofservo-drivesystemBasedonapplication……《NCTechnology》

ModeofNCcontrolSystemPointtopointPoint-to-pointsystem,alsocalledPositingcontrolsystem,movestheworktabletoaprogrammedlocationwithoutregardforthepathtakentogettothelocation.contouringcontrolsystemThecontouringfacilityenablesanNCmachinetofollowanypathatanyprescribedfeed-rate.

Thecontouringcontrolsystem,alsocalledcontinuouspathcontrolsystem,managesthesimultaneousmotionofthecuttingtoolintwo,three,four,orfiveaxesbyinterpolatingtheproperpathbetweenprescribedpoints.《NCTechnology》

Pointtopoint1:Axialpath《NCTechnology》

Pointtopoint2:45degreeslinepath3:Linearpath《NCTechnology》

CircularInterpolationTheoretically,Capableofcreatingcurveandcircle,usingincrementofsmalllineorpolygon.《NCTechnology》

Exleofcontinuouspath《NCTechnology》

CNCInterpolationInterpolator

Hardwaredevice(NCsystem)

Softwareprogram(CNCsystem)Functions:Computeindividualaxisvelocitiestodrivetoolalongprogrammedpathatgivenfeed-rate.Generateintermediatecoordinatepositionsalongtheprogrampath.《NCTechnology》

TypesofInterpolation5typesofinterpolation:Linear（直線）Circular（圓弧）Helical（螺旋線）Parabolic（拋物線）Cubic(三次)《NCTechnology》

TypesofNCServo-DriveSystemsOpen-loopservo-driveHalf-closed-loopservo-driveclosed-loopservo-drive《NCTechnology》

Open-loopservo-drive《NCTechnology》

Open-loopservo-driveSimplestandleastcostformofservo-driveThesystemlacksfeedback,thatis,oncetheinputsignalissent,thereisnosensingdevicetoconfirmtheactionofthecontrolsignal.Theservomotorisusuallysteppingmotorsteppingmotoroutputshaftrotatesindirectproportiontopulsesreceived.

Highaccuracy,easyimplementationandcompatiblewithdigitalsignalslowtorque,limitedspeedandriskofmissedpulseunderload《NCTechnology》

ApplicationareaTheactionsperformedbythecontrolsystemaresimpleTheactuatingfunctionisveryreliableAnyreactionforcesopposingtheactuationaresmallenoughtohavenoeffectontheactuation.UsedintheeconomicNCmachine!《NCTechnology》

Half-closed-loopservo-drive《NCTechnology》

Half-closed-loopservo-driveIndirectfeedbackmonitorstheoutputofservomotor.PopularwithNCsystemThehalf-closed-loopsystemcomparesthecommandpositionsignalwiththedrivesignaloftheservomotor.Convenienttoadjust;goodstability.Unabletosensebacklashorleadscrewwindupduetovaryingloads.《NCTechnology》

closed-loopservo-drive《NCTechnology》

closed-loopserv