数字控制_计算机数字控制_与计算机数控机床的安全和维护

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1、苏州大学本科生毕业设计（论文）NC、CNCandMaintenanceforCNCMachine1.1TheHistoryofNCandCNCDevelopmentNumericalControl(NC)isanymachiningprocessinwhichtheoperationsareexecutedautomaticallyinsequencesasspecifiedbytheprogramthatcontainstheinformationforthetoolmovements.TheNCconceptwas

2、proposedinthelate1940sbyJohnParsonsofTraverseCity,Michigan.Parsonsrecommendedamethodofautomaticcontrolthatwouldguideamillingcuttertoproducea”thru-axiscurve”inordertogeneratesmoothprofilesonworkpieces.In1949，TheU.S.AirForceawardParsonsacontracttodevelopanewtypeof

3、machinetoolthatwouldbeabletospeedupproductionmethods.ParsonscommissionedtheMassachusettsInstituteofTechnology(M.I.T)TOdevelopapracticalimplementationofhisconcept.ScientistsandengineersatM.I.Tbuiltacontrolsystemforatwo-axismillingmachinethatusedaperforatedpaperta

4、peastheinputmedia.Inashortperiodoftime,allmajormachinetoolmanufacturerswereproducingsomemachineswithNC,butitwasnotuntilthelate1970sthatcomputer-basedNCbecamewidelyused.NCmaturedasanautomationtechnologywheninexpensiveandpowerfulmicroprocessorsreplacedhard-wirelog

5、ic-makingcomputer-basedNCsystems.WhenNumericalControlisperformedundercomputersupervision,itiscalledComputerNumericalControl(CNC).ComputersarethecontrolunitsofCNCmachines,theyarebuiltinorlinkedtothemachinesviacommunicationschannels.Whenaprogrammerinputsomeinforma

6、tionintheprogrambytapeandsoon,thecomputercalculatesallnecessarydatatogetthejobdone.OnthefirstNumericallyControlled(NC)machineswerecontrolledbytape,andbecauseofthat,theNCsystemswereknownastape-controlledmachines.Theywereabletocontrolasingleoperationenteredintothe

7、machinebypunchedonmagnetictape.Therewasnopossibilityofeditingtheprogramonthemachine.Tochangetheprogram,newtapehadtobemade.Today’ssystemshavecomputerstocontroldata;theyarecalledComputerNumericallyControlled(CNC)machines.ForbothNCandCNCsystems,workingprinciplesare

8、thesame.Onlythewayinwhichtheexecutionis21苏州大学本科生毕业设计（论文）controlledisdifferent.Normally,newsystemsarefaster,morepowerful,andmoreversatile.1.1TheApplicationsofNC/CNCFig