Numerical Control 英语论文

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1、NumericalControlThiscenturyhasseenmachinerybecomemoreautomated，therebyeliminatingmachine-operatorinterventioninthemanufacturingprocess.Yet，asautomationhasincreased，machineshavebecomeinherentlymorespecialized.Ahighlyautomatemachinethatmayturnout20000compon

2、entsperday，willgenerallybeabletoproduceonlyalimitedclassofcomponents.Untilrecently，prototypesandlowvolumecomponentswereproducedbymanuallyoperatedconventionalmachinetools.Withtheadventofnewhard-to-machinematerialsandrequirementsforcomponentofaprecisionthat

3、canapproachonepartintenthousand，thebesthumanoperatorshavereachedthelimitedclassoftheirability.Theserequirements，togetherwithaneedforcomponentflexibility，haveleadtoaformofautomaticmachinecontrolknownbythegenericnameNumericalControl.1.WhatisNumericalControl

4、（NC）？NumericalControlisamethodofcontrollingthemovementsofmachinecomponentsbydirectlyinsertingcodedinstructions，intheformofnumbersandletters,intothesystem.Thesystemautomaticallyinterpretsthesedataandconvertsthemtooutputsignals.Thesesignals，inturn，controlva

5、riousmachinecomponents—forexample，byturningspindlesonandoff，changingtools，movingtheworkpieceorthetoolsalongspecificpaths，orturningcuttingfluidsonandoff。Wecanseefromthisdefinitionthatthesequenceofeventsisbothpreplannedandpredictable.Inotherwords，anydesired

6、sequenceofeventscanbechangingthosecodedinstructionsandcanalsobechangedbychangingthosecodedinstructions.Therefore，NCsystemsareconsideredtobethetypicalformofprogrammableautomation。2.ThehistoricalbackgroundofNCThebasicconceptofNCisnotnewatallanddatesbacktoth

7、eearlyyearsoftheIndustrialRevolution，whenJosephJacquarddevelopedamethodtocontroltextileloomsbyusingpunchedcards.Butwhenheappliedforapatentforhisinvention，hewasdeniedthatrightbytheQueenofEnglandbecauseshebelievethatitwouldhaveputpoorworkersofwork（noticethe

8、similaritywithrobotsnowadays）.Infact,thisoldinventioncanbeconsideredsimple,crudeformsofmechanicalNC.AmodernversionofNCemergedin1947attheParsonsEngineeringCompanyofTraverseCity，Michigan，asaresultoftheneedofJohnC.Pars