数控技术---外文翻译.doc

NUMERICALCONTROLNumericalcontrol(N／C)isaformofprogrammableautomationinwhichtheprocessingequipmentiscontrolledbymeansofnumbers，letters，andothersymbols．Thenumbers，letters，andsymbolsarecodedinanappropriateformattodefineaprogramofinstructionsforaparticularworkpartorjob．Whenthejobchanges，theprogramofinstructionsischanged．ThecapabilitytochangetheprogramiswhatmakesN／Csuitableforlow-andmedium-volumeproduction．Itismucheasiertowriteprogramsthantomakemajoralterationsoftheprocessingequipment．Therearetwobasictypesofnumericallycontrolledmachinetools：point—to—pointandcontinuous—path(alsocalledcontouring)．Point—to—pointmachinesuseunsynchronizedmotors，withtheresultthatthepositionofthemachiningheadCanbeassuredonlyuponcompletionofamovement，orwhileonlyonemotorisrunning．Machinesofthistypeareprincipallyusedforstraight—linecutsorfordrillingorboring．TheN／Csystemconsistsofthefollowingcomponents：datainput，thetapereaderwiththecontrolunit，feedbackdevices，andthemetal—cuttingmachinetoolorothertypeofN／Cequipment．Dat