外文翻译--数控生产设备及数控机床开环控制伺服系统

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1、附录OpenSystemMeritOfComputerNumericalControlNumericalcontrol(NC)isaformofprogrammableautomationinwhichtheprocessingequipmentiscontrolledbymeansofnumbers,letters,andothersymbols.Thenumbers,letters,andsymbolsarecodedinanappropriateformattodefineaprogramofinstructionsforaparticularworkpartorjob.When

2、thejobchanges,theprogramofinstructionsischanged・ThecapabilitytochangetheprogramiswhatmakesNCsuitableforlow-andmedium-volumeproduction.Itismucheasiertowritenewprogramsthantomakemajoralterationsoftheprocessingequipment.1•BasicComponentsOfNCAnumericalcontrolsystemconsistsofthefollowingthreebasiccom

3、ponents:-Programofinstructions•Machinecontrolunit•ProcessingequipmentThegeneralrelationshipamongthethreecomponentsisillustratedinFig.2.1.Theprogramisfedintothecontrolunit,whichdirectstheprocessingequipmentaccordingly.Theprogramofinstructionsisthedetailedstep-by-stepcommandsthatdirecttheprocessin

4、gequipment.Initsmostcommonform,thecommandsrefertopositionsofamachinetoolspindlewithrespecttotheworktableonwhichthepartisfixtured.Moreadvancedinstructionsincludeselectionofspindlespeeds,cuttingtool,andotherfunction.Themostcommonmediuminuseoverthelastseveraldecadeshasbeen1-in.-widepunchedtape・Beca

5、useofthewidespreaduseofthepunchedtape,NCissometimescalled"tapecontrol^.However,thisisamisnomerinmodernusageofnumericalcontrol.Comingintousemorerecentlyhavebeenmagnetictapecassettesandfloppydiskettes.Themachinecontrolunit(MCU)consistsoftheelectronicsandcontrolhardwarethatreadandinterprettheprogra

6、mofinstructionandconvertitintomechanicalactionsofthemachinetoolorotherprocessingequipment.TheprocessingequipmentisthethirdbasiccomponentofanNCsystem.Itisthecomponentthatperformsusefulwork.Inthemostcommonexampleofnumericalcontrol,onethatperformsmachiningoperations,theprocessingequipmentconsistsof

7、theworktableandspindleaswellasthemotorsandcontrolsneededtodrivethem.2・TypesOfControlSystemsTherearetwobasictypesofcontrolsystemsinnumericalcontrol:point-to-pointandcontouring.Inthepoint-to-pointsystem,alsocalledpositioning,e