数控技术专业英语 教学课件 作者 黄义俊 电子教案统一模板(数控)Unit4.ppt

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1、Unit4TheComponentsofCNCMachinesLesson7TheConstructionofCNCMachines4.1Lesson8TheComponentsofCNCMachines4.2ReadingMaterials7TheOperationPanelofCNCMachinesⅠ4.3ReadingMaterials8TheOperationPanelofCNCMachinesⅡ4.44.1Lesson7TheConstructionofCNCMachinesCNCmachine

2、toolsarecomplexassemblies.Ingeneral,CNCmachinetoolconsistsofthefollowingunits:1.Computer—Aswithallcomputers,theCNCmachinecomputerworksonabinaryprincipleusingonlytwocharacters1and0,forinformationprocessingprecisetimeimpulsesfromthecircuit.Therearetwostates

3、,astatewithvoltage,1,andastatewithoutvoltage,0.Seriesofonesandzeroesaretheonlystatesthatthecomputerdistinguishesacalledmachinelanguage,whichistheonlylanguagethecomputerunderstands.Whencreatingtheprogram,theprogrammerdoesnotcareaboutthemachinelanguage.Heor

4、shesimplyusesalistofcodesandkeysinthemeaningfulinformation.Specialbuilt-insoftwarecompilestheprogramintomachinelanguageandthemachinemovesthetoolbyitsservomotors.However,theprogrammabilityofthemachineisdependentonwhetherthereisacomputerinthemachine’scontro

5、l.2.Controlsystem—TherearetwotypesofcontrolsystemsonNC/CNCmachines:open-loopandclosed-loop.Thetypeofcontrolloopuseddeterminestheoverallaccuracyofthemachine.Theopen-loopcontrolsystemdoesnotprovidepositioningfeedbacktothecontrolunit.Theclosed-loopcontrolsys

6、temisveryaccurate.Ithasanautomaticcompensativefunctionforerror,sincethefeedbackdeviceindicatestheerrorandthecontrolmakesthenecessaryadjustmentstobringtheslidebacktotheposition.TheyapplyAC,DCorhydraulicservomotors.3.Drivemotors—Thedrivemotorscontrolthemach

7、ineslidemovementonNC/CNCequipment.Theyfallintofourbasictypes:Steppermotorsconvertadigitalpulsegeneratedbythemicrocomputerunit(MCU)intoasmallsteprotation.Steppermotorsareusedinopen-loopcontrolsystems,whileAC,DCorhydraulicservomotorsareusedinclosed-loopcon

8、trolsystems.Directcurrent(DC)servomotorsarevariablespeedmotorsthatrotateinresponsetotheappliedvoltage.Theyareusedtodrivealeadscrewandgearmechanism.DCservomotorsprovidehigher-torqueoutputthansteppermotors.Alternati