外文翻译=数控技术=4000字符@英语翻译

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1、NUMERICALCONTROLNumericalcontrol(N／C)isaformofprogrammableautomationinwhichtheprocessingequipmentiscontrolledbymeansofnumbers，letters，andothersymbols．Thenumbers，letters，andsymbolsarecodedinanappropriateformattodefineaprogramofinstructionsforaparticularworkpa

2、rtorjob．Whenthejobchanges，theprogramofinstructionsischanged．ThecapabilitytochangetheprogramiswhatmakesN／Csuitableforlow-andmedium-volumeproduction．Itismucheasiertowriteprogramsthantomakemajoralterationsoftheprocessingequipment．Therearetwobasictypesofnumerica

3、llycontrolledmachinetools：point—to—pointandcontinuous—path(alsocalledcontouring)．Point—to—pointmachinesuseunsynchronizedmotors，withtheresultthatthepositionofthemachiningheadCanbeassuredonlyuponcompletionofamovement，orwhileonlyonemotorisrunning．Machinesofthis

4、typeareprincipallyusedforstraight—linecutsorfordrillingorboring．TheN／Csystemconsistsofthefollowingcomponents：datainput，thetapereaderwiththecontrolunit，feedbackdevices，andthemetal—cuttingmachinetoolorothertypeofN／Cequipment．Datainput，alsocalled“man—to—control

5、link”，maybeprovidedtothemachinetoolmanually，orentirelybyautomaticmeans．Manualmethodswhenusedasthesolesourceofinputdataarerestrictedtoarelativelysmallnumberofinputs．Examplesofmanuallyoperateddevicesarekeyboarddials，pushbuttons，switches，orthumbwheelselectors．T

6、hesearelocatedonaconsolenearthemachine．Dialsaleanalogdevicesusuallyconnectedtoasyn-chro-typeresolverorpotentiometer．Inmostcases，pushbuttons，switches，andothersimilartypesofselectorsayedigitalinputdevices．Manualinputrequiresthattheoperatorsetthecontrolsforeach

7、operation．Itisaslowandtediousprocessandisseldomjustifiedexceptinelementarymachiningapplicationsorinspecialcases．Inpracticallyallcases，informationisautomaticallysuppliedtothecontrolunitandthemachinetoolbycards，punchedtapes，orbymagnetictape．Eight—channelpunche

8、dpapertapeisthemostcommonlyusedformofdatainputforconventionalN／Csystems．Thecodedinstructionsonthetapeconsistofsectionsofpunchedholescalledblocks．Eachblockrepresentsamachinefunction，amachiningope