機(jī)械專(zhuān)業(yè)英語(yǔ)

機(jī)械專(zhuān)業(yè)英語(yǔ)第一篇：機(jī)械專(zhuān)業(yè)英語(yǔ)機(jī)械專(zhuān)業(yè)英語(yǔ)楊亞炬20XX0334506機(jī)電103班考慮磨削力的磁懸浮磨床電主軸轉(zhuǎn)子系統(tǒng)動(dòng)態(tài)特性分析摘要:以電磁軸承支承的磨床也主軸為研究對(duì)象，建立了轉(zhuǎn)子的彈性支承模型，對(duì)其進(jìn)行了模態(tài)分析，得出轉(zhuǎn)子固有頻率隨支承剛度變化的規(guī)律;對(duì)施加磨削力時(shí)轉(zhuǎn)子的穩(wěn)態(tài)響應(yīng)特性進(jìn)行了分析，根據(jù)危險(xiǎn)界面的節(jié)點(diǎn)位移，初步確定了主軸系統(tǒng)的穩(wěn)定性。關(guān)鍵詞:電磁軸承支承系統(tǒng);磨床電主軸;模態(tài)分析;穩(wěn)態(tài)響應(yīng)特性引言電磁軸承具有無(wú)摩擦、元磨損、高速度、高精度及可長(zhǎng)期免維護(hù)等優(yōu)點(diǎn)，因此被廣泛應(yīng)用于高速旋轉(zhuǎn)類(lèi)機(jī)械中。采用電磁軸承支承的磨床電主軸是典型的機(jī)電一體化系統(tǒng)，由于磨削過(guò)程的復(fù)雜性，其支承主軸系統(tǒng)的影響與其他軸承相比更為突出[1刀。轉(zhuǎn)子的動(dòng)態(tài)特性是電磁軸承支承特性與轉(zhuǎn)子結(jié)構(gòu)動(dòng)力學(xué)特性綜合作用的結(jié)果。在對(duì)轉(zhuǎn)子實(shí)施控制之前，研究轉(zhuǎn)子本身的動(dòng)力學(xué)行為對(duì)控制系統(tǒng)的設(shè)計(jì)是很重要的時(shí)。本文以某電磁軸承支承的磨床電主軸為研究對(duì)象，建立了轉(zhuǎn)子的彈性支承模型，對(duì)其進(jìn)行了模態(tài)分析和施加磨削力時(shí)的穩(wěn)態(tài)響應(yīng)特性分析。軸、砂輪連接桿、前后徑向軸頸套、前后平衡環(huán)、止推盤(pán)和隔磁環(huán)等組成，其他部件與轉(zhuǎn)軸之間采用過(guò)盈連接。轉(zhuǎn)子總重5.90kg，總長(zhǎng)507mm，穩(wěn)定懸浮時(shí)轉(zhuǎn)子和徑向軸承之間的間隙為0.2mm，軸向軸承1.砂輪2傳感器3.前輔助軸承4.前徑向軸承5.轉(zhuǎn)軸6.軸向軸承7.冷卻水套8.電機(jī)部分9.后徑向軸承10.后輔助軸承間隙為0.3mm。建立有限元模型電磁軸承支承為典型的彈性支承，有限元分析模型采用16個(gè)彈簧單元模擬徑向電磁軸承的16個(gè)磁極。止推盤(pán)兩側(cè)分別采用8個(gè)彈簧轉(zhuǎn)軸根據(jù)轉(zhuǎn)子的結(jié)構(gòu)形式，用ANSYS建立起轉(zhuǎn)子的實(shí)體有限元分析模型，模態(tài)分析支承剛度對(duì)轉(zhuǎn)子固有頻率的影晌根據(jù)轉(zhuǎn)子的有限元分析模型，用ANSYS對(duì)其進(jìn)行模態(tài)分析[5J。忽略彈簧單元的阻尼，支承剛度在5X106~lXI09N/m范圍內(nèi)變化階模態(tài)，得到轉(zhuǎn)子的正進(jìn)動(dòng)固有頻率和負(fù)進(jìn)動(dòng)固有頻率，進(jìn)一步研究臨界轉(zhuǎn)速時(shí)，首先剔除負(fù)進(jìn)動(dòng)固有頻率[6J?？梢缘玫睫D(zhuǎn)軸前四階固有頻率隨剛度變化曲線,轉(zhuǎn)子的正進(jìn)動(dòng)固有頻率隨支承剛度的增大而增大，且轉(zhuǎn)子的低階固有頻率隨支承剛度增加的幅度較大。當(dāng)支承剛度增大到1.6X108N/m時(shí)，轉(zhuǎn)子的2~4階固有頻率已無(wú)多模態(tài)分析完畢后，將磨削激振力施加于砂輪處進(jìn)行諧響應(yīng)分析，在砂輪外圓節(jié)點(diǎn)7746處施加Y方向力(實(shí)部為88.328N、虛部為1.9737N)和Z方向力(實(shí)部為1.9737N、虛部為88.328N)，這樣磨削力為一簡(jiǎn)諧力。COMBIN14單元的剛度取2.0X107N/m，為分析轉(zhuǎn)子在高頻段的響應(yīng)，將激振力的頻率范圍擴(kuò)大至0~1600Hz，分20XX載荷步進(jìn)行諧響應(yīng)分析。當(dāng)主軸工作在30000r/min(對(duì)應(yīng)額定工作頻率500.0Hz)、48OOOr/min(對(duì)應(yīng)最高工作頻率800.OHz)，即轉(zhuǎn)速處于一階與二階臨界轉(zhuǎn)速之間時(shí)，由轉(zhuǎn)子的二階振型(圖5)可以看出，轉(zhuǎn)子在砂輪、前保護(hù)軸承、前徑向軸承和后徑向軸承處的中心截面為危險(xiǎn)截面。圖7~圖10分別為砂輪、前保護(hù)軸承、前徑向軸承和后徑向軸承處的振動(dòng)幅值一頻率響應(yīng)后徑向軸承處節(jié)點(diǎn)4484振動(dòng)幅值一頻率響應(yīng)曲線移增大幅值在一階固有頻率處最小，二階固有頻率處最大，三階固有頻率處次之。磨床電主軸的結(jié)構(gòu)參數(shù)如下:轉(zhuǎn)子與前后保護(hù)軸承的間隙為O.lmm，與前后徑向軸承的間隙為0.2mm。由表3可知，當(dāng)激振力頻率達(dá)到轉(zhuǎn)子一階、三階固有頻率時(shí)，轉(zhuǎn)子產(chǎn)生的共振位移在轉(zhuǎn)曲線，在有限元模型上分別對(duì)應(yīng)節(jié)點(diǎn)7746、7818、7559和4484的振動(dòng)幅值頻率響應(yīng)。各危險(xiǎn)截面的節(jié)點(diǎn)Y方向位移如表3所示。當(dāng)激振力頻率達(dá)到轉(zhuǎn)子的固有頻率時(shí)，轉(zhuǎn)子的位移(振動(dòng)幅值)會(huì)突然增大，通過(guò)前三階的幅頻響應(yīng)曲線可以看出，轉(zhuǎn)子位子間隙范圍之內(nèi);但達(dá)到轉(zhuǎn)子二階固有頻率時(shí)，轉(zhuǎn)子產(chǎn)生的共振位移會(huì)超出間隙要求，使得轉(zhuǎn)子與軸承碰撞，發(fā)生危險(xiǎn)，因此應(yīng)避免激振力頻率達(dá)到轉(zhuǎn)子的二階固有頻率。由轉(zhuǎn)子的二階振型可以看出，轉(zhuǎn)子在后保護(hù)軸承處的徑向位移小于后徑向軸承處的徑向位移，故可判定后保護(hù)軸承處在Y方向的位移小于2.0X10一7m。各危險(xiǎn)截面的節(jié)點(diǎn)位移均在間隙范圍內(nèi)，因此可初步判定轉(zhuǎn)子在額定轉(zhuǎn)速和最高轉(zhuǎn)速下工作時(shí)，給其施加Fn=88.328N、Ft=1.9737N的磨削力，可穩(wěn)定工作。結(jié)論(1)完全彈性支承下，電主軸轉(zhuǎn)子固有頻率的總體變化趨勢(shì)隨支承剛度的增大而增大，并且在支承剛度較低時(shí)，固有頻率隨支承剛度的變化較大。當(dāng)支承剛度到達(dá)一定值時(shí)，轉(zhuǎn)子的前四階固有頻率趨于穩(wěn)定，在設(shè)計(jì)控制系統(tǒng)時(shí)可控制軸承的剛度高于此值，以便轉(zhuǎn)子具有穩(wěn)定的臨界轉(zhuǎn)速。(2)在施加了磨削激振力后，通過(guò)幅值頻率響應(yīng)分析確定了幾個(gè)危險(xiǎn)界面的節(jié)點(diǎn)位移，可初步判斷主軸系統(tǒng)的穩(wěn)定性。DynamicAnalysisforElectricSpindleRotorSystemofMagneticLevitationGrinderConsideringGrindingForceAbstract:Thispaperbui1tanelasticbearingmodelfortherotorofgrinderelectricspindlesupportedbyelectromagnetbearingandanalyzedthemodeoftherotor,educedthelawsabouttherotorinherentfrequencieschangingalongwithbearingstiffness.Then,itanalyzedsteadystateresponsecharacteristicsoftherotorwhileapplyinggrindingforce.Accordingtothenodedisplacementsofdangerinterface,stabilityofspindlesystemisensuredinitially.Keywords:supportingsystemofelectromagnetbearing;grinderelectricspindle;modeanalysis;steadystateresponsecharacteristics.IntroductionElectromagneticbearingswithnofriction,wearyuan,high-speed,highprecisionandlong-termmaintenance-free,etc.,itiswidelyusedinhigh-speedrotatingmachinery.Theelectromagneticbearinggrinderelectricspindleisatypicalmechatronicsystems,duetothecomplexityofthegrindingprocess,thesupportingspindlesystemcomparedwithotherbearingmoreprominent[1knife.Thedynamiccharacteristicsoftherotortheelectromagneticbearingcharacteristicsandrotorstructuredynamicscombinedresult.Beforecontroloftherotorembodiment,thestudyrotordynamicbehaviorofthecontrolsystemdesignisveryimportant.Anelectromagneticbearinggrinderelectricspindlerotorelasticsupportmodel,itsmodalanalysisandsteady-stateresponsecharacteristicsinthegrindingforceisapplied.Shaft,wheelconnectingrod,frontandrearradialjournalcover,frontandrearstabilizerring,thrustplate,andeveryothermagneticinterferenceconnectionbetweentheothercomponentsandtheshaft.Therotortotalweightof5.90kg,Totallength507mm,stablesuspensionoftherotorandtheradialbearinggapof0.2mm,andtheaxialbearingwheelsensor3.Formerauxiliarybearingfrontradialbearing5.Shaftaxialbearingcoolingwaterjacketmotorsection9afterradialbearing10aftertheauxiliarybearingclearanceof0.3mm.FiniteelementmodelTheelectromagneticbearingthetypicalelasticsupport,finiteelementanalysismodelwith16springelementtosimulatetheradialmagneticbearing16pole.Onbothsidesofthethrustplate8springpivotEstablishedwithANSYSbasedonthestructureoftherotor,therotorsolidfiniteelementanalysismodel,ModalAnalysisSupportstiffnessIMPACTnaturalfrequencyoftherotorbasedonthefiniteelementanalysismodeloftherotor,modalanalysisusingANSYSits[5J.Thedampingofthespringelementisignored,thethesupportstiffness5X106~lXI09N/mrangeordermodalrotorisprecessionnaturalfrequenciesandnegativeprecessionnaturalfrequency,furtherstudyofthecriticalspeed,thefirstnaturalfrequency[excludingthenegativeprecession6J.Cangettheshaftfirstfournaturalfrequencyofthecurvewiththechangeinstiffnessoftherotorisprecessionnaturalfrequencywiththesupportstiffnessincreases,andtherateofincreaseofthelow-ordernaturalfrequencyoftherotorwiththebearingstiffness.The2-4ordernaturalfrequencyoftherotorFoundwhenthesupportingstiffnessincreasesto1.6X108N/m,Modalanalysisaftergrindingexcitingforceisappliedatthewheelattheharmonicresponseanalysis,theYdirectionoftheforceappliedtothewheelouternode7746(88328Nrealpart,imaginarypart19737N),andZdirectionsforce(therealpartof9737N,theimaginarypartofthe88328N),sothatthegrindingforceofasimpleharmonicforce.COMBIN14elementstiffnesstake2.0x107N/mfortheanalysisoftheresponseoftherotorathighfrequencies,thefrequencyrangeoftheexcitationforceisexpandedto0to1600Hz,20XXoadstepharmonicresponseanalysis.Spindle30000r/min(correspondingtothenominaloperatingfrequency500.0Hz),of48OOOr/min(correspondingtothemaximumoperatingfrequencyof800OHZ)thatspeedinthefirst-orderandsecond-ordercriticalspeed,thesecondrotorvibrationtype(Figure5)canbeseen,therotorwheel,thefrontprotectivebearings,theradialbearingandtherearradialbearingatthecenterofasectionalviewofthedangeroussection.Figures7to10respectivelyforthewheel,thefrontprotectivebearings,thefrontradialbearingandaradialbearingatafrequencyresponseofthevibrationamplitudeofthevibrationamplitudeoftheradialbearingatthenode4484frequencyresponsecurveshiftincreasedamplitudeinaThenaturalfrequenciesattheminimum,followedbythenaturalfrequencyofthesecond-order,third-ordernaturalfrequency.OfGrinderSpindlestructureparametersareasfollows:rotorprotectionbeforeandafterbearingclearanceO.lmmthefrontandrearradialbearingclearanceof0.2mm.SeenfromTable3,whenthefrequencyoftheexcitationforcetotherotor-order,third-ordernaturalfrequency,theresonancegeneratedbytherotordisplacementinthetransfercurveinthefiniteelementmodel,respectivelycorrespondingtothenodes7746,7818,7559and4484,theamplitudeofvibrationfrequencyresponse.ThenodesintheYdirectionofthedangeroussectionofthedisplacementshowninTable3.Whenthefrequencyoftheexcitationforceisreachedwhenthenaturalfrequencyoftherotor,therotordisplacement(vibrationamplitude)willsuddenlyincreases,frequencyresponsecurveofthewebthroughthefirstthreecanbeseen,withinthescopeoftheclearanceoftherotorcharts;butreachedrotorSecondOrdernaturalfrequencyoftherotoroftheresonancedisplacementwillexceedthespacingrequirements,sothattherotorandthebearingcollisiondanger,thesecondnaturalfrequencyoftheexcitingforcethefrequencyoftherotorshouldthereforebeavoided.Bythesecond-ordervibrationoftherotorcanbeseen,theradialdisplacementoftherotorafterprotectionoftheradialdisplacementofthebearingislessthantheradialbearingatthedisplacementofthebearingsintheYdirection,itcanbedeterminedafterprotectionSmaller2.0X10am.OfthedangeroussectionofthenodaldisplacementsgappreliminarydeterminationrotoratratedspeedandmaximumSpeedworkwhenappliedtoitsFn=88.328NFT=9737Ngrindingforcecanworkstably.Conclusions(1)fullyresilientsupport,theoveralltrendofthenaturalfrequencyoftheelectro-spindlerotorwithbearingstiffnessincreases,andthesupportingrigidityislow,thelargerthechangeofthenaturalfrequencywiththesupportstiffness.Whenthesupportingrigidityreachesacertainvalue,thefirstfournaturalfrequenciesoftherotorisstabilizedinthedesignofthecontrolsystemcancontrolthestiffnessofthebearingishigherthanthisvalue,thestabilityofthecriticalspeedfortherotorhaving.(2)Inthegrindingexcitingforceisappliedbytheamplitudefrequencyresponseanalysisidentifiedseveralriskinterfacenodaldisplacementscandeterminetheinitialstabilityofthespindlesystem.第二篇：大學(xué)機(jī)械專(zhuān)業(yè)英語(yǔ)總結(jié)Unit11Machinetoolshaveevoledfromtheearlyfoot-poweredlathesoftheEgyptiansandJohnWilkinson’sboringmill.Mostmachiningoperationsproducepartsofdifferinggeometry.Flatorplainsurfacesarefrequentlyrequired.Multiple-edgedtoolscanalsobeused.ThebasicoperationsperformedonanenginelatheareillustratedinFig11-3.Thoseoperationsperformedonexternalsurfaceswithasinglepointcuttingtoolarecalledturning.Theobjectiveofboringaholeinalatheis:1.Toenlargethehole2,Tomachinetheholetothedesireddiameter.3.Toaccuratelylocatethepositionofthehole.4.Toobtionasmothsurfacefinishinthehole.Unit12Broachingisaprocessforinternalorexternalmachiningoffalt,round,orcontouredsurfaces.Sawingisthepartingofmaterialbyusingmetaldisks,blades,bands,orabrasivedisksasthecuttingtools,Reamingisamachiningprocessforenlarging,smoothingand/oraccuratelysizingexistingholesbymeansofmultiedgeflutescuttingtools.Unit13Weldingisessentialtotheexpansionandproductivityofourindustries.Electroplatingisaprocessinwhichametalisdepositedontoametallicsubstrate.Solderingisthejoiningofmetalsbycausingalower-melting-pointmetaltowetoralloywiththejointsurfacesandthenfreezeinplace.Cleaningoperationsareperformedbothpreparatorytoandafterfinishingoperations.Unit14Lathesaredesignedtorotatetheworkpieceandfeedthecuttingtoolinthedirectionnecessarytogeneratetherequiredmachinedsurface.Vertical-boringmachinehorizontal-boringmachineplanningmachinehorizontal-millingmachinevertical-millingmachineUnit15AJMremovesmaterialthroughthemechanicalcationofafocusedstreamofabrasiveladengas.USMisamechanicalmaterialremovalprocesswhichisusedtogenerateholesandcavitiesinhardorbrittleworkpieces.ECMisaprocessthatremovesmaterialthroughtheptincipleofeiectrolysis.Unit16Grouptechnologyisaveryimportantmethodologyintoday’smanufacturingenvironment,particularlyforbatchproduction,andisbecomingincreasinglysignificant.Forpartstobegroupedbasedoneitherdesigncharacteristicsandfeatuersormanufacturingprocesses,theymustbeclassifiedintopredeterminedcategoriesandcodedforretrievalanduse.Unit17Flexibilityisanimportantcharacteristicinthemodernmanufacturingsetting.Cellularmanufacturingistheconceptoforganizingplantfacilitiesandprocessplanningforfamily-of-partmanufactuer.Machinecentersoriginstedoutoftheircapabilitytoperformavarietyofmachiningoperationsonaworkpiecebychangingtheirowncuttingtools.SoftwareisthevitalinvisibleelementthanactuallydrivestheFMS.TherearetwobasiclevelsofsoftwarerequiredforanFMS:1:operatingsystem2:applicationsoftwareUnit18Computerintegratedmanufacturingisthetermusedtodescribethemodernapproachtomanufacturing.Managementistheprocessofmakingdirectingtheactivitiesofpersonneltoachievestatedobjectives.AnAGVisacomputer-controlled,driverlessvehicleusedfortransportingmaterialsformpointinamanufacturingsetting.InanydiscussionofAGVs,threekeytermsarefrequentlyused:1:Guidepath.2:Routing.3:Trafficmanagement.Unit19Partacquisitiontimeishighlydependentonthenatureofthelayoutoftheassenmblyareaandthemethodofassembly.Assemblyinthemanufacturingprocessconsistsofputtingtogetherallthecomponentpartsandsub-assembliesofagivenproduct,fastening,performinginspectionsandfunctionaltests,labeling,separatinggoodassembliesfrombad,andpackagingandorpreparingthemforfinaluse.Unit20XXutomationisawidelyusedterminmanufacturing.FixedautomationiswhatHarderwasreferringtowhenhecoinedthewordautomation.Numericalcontrolcanbedefinedasaformofprogrammableautomationinwhichtheprossiscontrolledbynumbers,letters,andsymbols.Theprogramofinstructionsisthedetailedstep-by-stepsetofdirectionswhichtellthemachinetoolwhattodo.Thehighestdegreeofautomationobtainablewithspecial-purpose,multifunctionmachinesisachievedbyusingtransfermachines.第三篇：機(jī)械專(zhuān)業(yè)英語(yǔ)文章中英文對(duì)照英語(yǔ)原文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.Datainput,alsocalled“man—to—controllink”,maybeprovidedtothemachinetoolmanually,orentirelybyautomaticmeans.Manualmethodswhenusedasthesolesourceofinputdataarerestrictedtoarelativelysmallnumberofinputs.Examplesofmanuallyoperateddevicesarekeyboarddials,pushbuttons,switches,orthumbwheelselectors.Thesearelocatedonaconsolenearthemachine.Dialsaleanalogdevicesusuallyconnectedtoasyn-chro-typeresolverorpotentiometer.Inmostcases,pushbuttons,switches,andothersimilartypesofselectorsaredigitalinputdevices.Manualinputrequiresthattheoperatorsetthecontrolsforeachoperation.Itisaslowandtediousprocessandisseldomjustifiedexceptinelementarymachiningapplicationsorinspecialcases.Inpracticallyallcases,informationisautomaticallysuppliedtothecontrolunitandthemachinetoolbycards,punchedtapes,orbymagnetictape.Eight—channelpunchedpapertapeisthemostcommonlyusedformofdatainputforconventionalN/Csystems.Thecodedinstructionsonthetapeconsistofsectionsofpunchedholescalledblocks.Eachblockrepresentsamachinefunction,amachiningoperation,oracombinationofthetwo.TheentireN/Cprogramonatapeismadeupofanaccumulationofthesesuccessivedatablocks.Programsresultinginlongtapesallwoundonreelslikemotion-picturefilm.Programsonrelativelyshorttapesmaybecontinuouslyrepeatedbyjoiningthetwoendsofthetapetoformaloop.Onceinstalled,thetapeisusedagainandagainwithoutfurtherhandling.Inthiscase,theoperatorsimplyloadsand1unloadstheparts.Punchedtapesalepreparedontypewriterswithspecialtape—punchingattachmentsorintapepunchingunitsconnecteddirectlytoacomputersystem.Tapeproductionisrarelyerror-free.Errorsmaybeinitiallycausedbythepartprogrammer,incardpunchingorcompilation,orasaresultofphysicaldamagetothetapeduringhandling,etc.Severaltrialrunsareoftennecessarytoremoveallerrorsandproduceanacceptableworkingtape.Whilethedataonthetapeisfedautomatically,theactualprogrammingstepsaledonemanually.Beforethecodedtapemaybeprepared,theprogrammer,oftenworkingwithaplanneroraprocessengineer,mustselecttheappropriateN/Cmachinetool,determinethekindofmaterialtobemachined,calculatethespeedsandfeeds,anddecideuponthetypeoftoolingneeded.Thedimensionsonthepartprintarecloselyexaminedtodetermineasuitablezeroreferencepointfromwhichtostarttheprogram.Aprogrammanuscriptisthenwrittenwhichgivescodednumericalinstructionsdescribingthesequenceofoperationsthatthemachinetoolisrequiredtofollowtocuttheparttothedrawingspecifications.Thecontrolunitreceivesandstoresallcodeddatauntilacompleteblockofinformationhasbeenaccumulated.Ittheninterpretsthecodedinstructionanddirectsthemachinetoolthroughtherequiredmotions.Thefunctionofthecontrolunitmaybebetterunderstoodbycomparingittotheactionofadialtelephone,where,aseachdigitisdialed,itisstored.Whentheentirenumberhasbeendialed,theequipmentbecomesactivatedandthecalliscompleted.Siliconphotodiodes,locatedinthetapereaderheadonthecontrolunit,detectlightasitpassesthroughtheholesinthemovingtape.Thelightbeamsareconvertedtoelectricalenergy,whichisamplifiedtofurtherstrengthenthesignal.Thesignalsarethensenttoregistersinthecontrolunit,whereactuationsignalsarerelayedtothemachinetooldrives.Somephotoelectricdevicesarecapableofreadingatratesupto1000characterspersecond.Highreadingratesarenecessarytomaintaincontinuousmachine—toolmotion；otherwisedwellmarksmaybegeneratedbythecutteronthepartduringcontouringoperations.Thereadingdevicemustbecapableofreadingdatablocksataratefasterthanthecontrolsystemcanprocessthedata.AfeedbackdeviceisasafeguardusedonsomeN/Cinstallationstoconstantlycompensateforerrorsbetweenthecommandedpositionandtheactuallocationofthemovingslidesofthemachinetool.AnN/Cmachineequippedwiththiskindofadirectfeedbackcheckingdevicehaswhatisknownasaclosed-loopsystem.Positioningcontrolisaccomplishedbyasensorwhich,duringtheactualoperation,recordsthepositionoftheslidesandrelaysthisinformationbacktothecontrolunit.Signalsthusreceivedalecomparedtoinputsignalsonthetape,andanydiscrepancybetweenthemisautomaticallyrectified.Inanalternativesystem,calledanopen—loopsystem,themachineispositionedsolelybysteppingmotordrivesinresponsetocommandsbyacontrollers.ThereisonebasictypeofNCmotions.Point-to-pointorPositionalControlInpoint-to-pointcontrolthemachinetoolelements(tools,table,etc.)aremovedtoprogrammedlocationsandthemachiningoperationsperformedafterthemotionsarecompleted.Thepathorspeedofmovementbetweenlocationsisunimportant;onlythecoordinatesoftheendpointsofthemotionsareaccuratelycontrolled.Thistypeofcontrolissuitablefordrillpressesandsomeboringmachines,wheredrilling,tapping,orboringoperationsmustbeperformedatvariouslocationsontheworkpiece.Straight-LineorLinearControlStraight-Linecontrolsystemsareabletomovethecuttingtoolparalleltooneofthemajoraxesofthemachinetoolatacontrolledratesuitableformachining.Itisnormallyonlypossibletomoveinonedirectionatatime,soangularcutsontheworkpiecearenotpossible,consequently,formillingmachines,onlyrectangularconfigurationscanbemachinedorforlathesonlysurfacesparallelorperpendiculartothespindleaxiscanbemachined.Thistypeofcontrolledmotionisoftenreferredtoaslinearcontrolorahalf-axisofcontrol.Machineswiththisformofcontrolarealsocapableofpoint-to-pointcontrol.TheoriginalN/Cusedtheclosed—loopsystem.Ofthetwosystems,closedandopenloop,closedloopismoreaccurateand,asaconsequence,isgenerallymoreexpensive.Initially,open—loopsystemswereusedalmostentirelyforlight-dutyapplicationsbecauseofinherentpowerlimitationspreviouslyassociatedwithconventionalelectricsteppingmotors.Recentadvancesinthedevelopmentofelectrohydraulicsteppingmotorshaveledtoincreasinglyheaviermachineloadapplications.中文譯文數(shù)控技術(shù)數(shù)控是可編程自動(dòng)化技術(shù)的一種形式,通過(guò)數(shù)字、字母和其他符號(hào)來(lái)控制加工設(shè)備。數(shù)字、字母和符號(hào)用適當(dāng)?shù)母袷骄幋a為一個(gè)特定工件定義指令程序。當(dāng)工件改變時(shí),指令程序就改變。這種改變程序的能力使數(shù)控適合于中、小批量生產(chǎn),寫(xiě)一段新程序遠(yuǎn)比對(duì)加工設(shè)備做大的改動(dòng)容易得多。數(shù)控機(jī)床有兩種基本形式：點(diǎn)位控制和連續(xù)控制(也稱(chēng)為輪廓控制)。點(diǎn)位控制機(jī)床采用異步電動(dòng)機(jī),因此,主軸的定位只能通過(guò)完成一個(gè)運(yùn)動(dòng)或一個(gè)電動(dòng)機(jī)的轉(zhuǎn)動(dòng)來(lái)實(shí)現(xiàn)。這種機(jī)床主要用于直線切削或鉆孔、鏜孔等場(chǎng)合。數(shù)控系統(tǒng)由下列組件組成：數(shù)據(jù)輸入裝置,帶控制單元的磁帶閱讀機(jī),反饋裝置和切削機(jī)床或其他形式的數(shù)控設(shè)備。數(shù)據(jù)輸人裝置,也稱(chēng)“人機(jī)聯(lián)系裝置”,可用人工或全自動(dòng)方法向機(jī)床提供數(shù)據(jù)。人工方法作為輸人數(shù)據(jù)唯一方法時(shí),只限于少量輸入。人工輸入裝置有鍵盤(pán),撥號(hào)盤(pán),按鈕,開(kāi)關(guān)或撥輪選擇開(kāi)關(guān),這些都位于機(jī)床附近的一個(gè)控制臺(tái)上。撥號(hào)盤(pán)通常連到一個(gè)同步解析器或電位計(jì)的模擬裝置上。在大多數(shù)情況下,按鈕、開(kāi)關(guān)和其他類(lèi)似的旋鈕是數(shù)據(jù)輸入元件。人工輸入需要操作者控制每個(gè)操作,這是一個(gè)既慢又單調(diào)的過(guò)程,除了簡(jiǎn)單加工場(chǎng)合或特殊情況,已很少使用。幾乎所有情況下,信息都是通過(guò)卡片、穿孔紙帶或磁帶自動(dòng)提供給控制單元。在傳統(tǒng)的數(shù)控系統(tǒng)中,八信道穿孔紙帶是最常用的數(shù)據(jù)輸入形式,紙帶上的編碼指令由一系列稱(chēng)為程序塊的穿孔組成。每一個(gè)程序塊代表一種加工功能、一種操作或兩者的組合。紙帶上的整個(gè)數(shù)控程序由這些連續(xù)數(shù)據(jù)單元連接而成。帶有程序的長(zhǎng)帶子像電影膠片一樣繞在盤(pán)子上,相對(duì)較短的帶子上的程序可通過(guò)將紙帶兩端連接形成一個(gè)循環(huán)而連續(xù)不斷地重復(fù)使用。帶子一旦安裝好,就可反復(fù)使用而無(wú)需進(jìn)一步處理。此時(shí),操作者只是簡(jiǎn)單地上、下工件。穿孔紙帶是在帶有特制穿孔附件的打字機(jī)或直接連到計(jì)算機(jī)上的紙帶穿孔裝置上做成的。紙帶制造很少不出錯(cuò),錯(cuò)誤可能由編程、卡片穿孔或編碼、紙帶穿孔時(shí)的物理?yè)p害等形成。通常,必須要試走幾次來(lái)排除錯(cuò)誤,才能得到一個(gè)可用的工作紙帶。雖然紙帶上的數(shù)據(jù)是自動(dòng)進(jìn)給的,但實(shí)際編程卻是手工完成的,在編碼紙帶做好前,編程者經(jīng)常要和一個(gè)計(jì)劃人員或工藝工程師一起工作,選擇合適的數(shù)控機(jī)床,決定加工材料,計(jì)算切削速度和進(jìn)給速度,決定所需刀具類(lèi)型,仔細(xì)閱讀零件圖上尺寸,定下合適的程序開(kāi)始的零參考點(diǎn),然后寫(xiě)出程序清單,其上記載有描述加工順序的編碼數(shù)控指令,機(jī)床按順序加工工件到圖樣要求?？刂茊卧邮芎蛢?chǔ)存編碼數(shù)據(jù),直至形成一個(gè)完整的信息程序塊,然后解釋數(shù)控指令,并引導(dǎo)機(jī)床得到所需運(yùn)動(dòng)。為更好理解控制單元的作用,可將它與撥號(hào)電話(huà)進(jìn)行比較,即每撥一個(gè)數(shù)字,就儲(chǔ)存一個(gè),當(dāng)整個(gè)數(shù)字撥好后,電話(huà)就被激活,也就完成了呼叫。裝在控制單元里的紙帶閱讀機(jī),通過(guò)其內(nèi)的硅光二極管,檢測(cè)到穿過(guò)移動(dòng)紙帶上的孔漏過(guò)的光線,將光束轉(zhuǎn)變成電能,并通過(guò)放大來(lái)進(jìn)一步加強(qiáng)信號(hào),然后將信號(hào)送到控制單元里的寄存器,由它將動(dòng)作信號(hào)傳到機(jī)床驅(qū)動(dòng)裝置。有些光電裝置能以高達(dá)每秒1000個(gè)字節(jié)的速度閱讀,這對(duì)保持機(jī)床連續(xù)動(dòng)作是必須的,否則,在輪廓加工時(shí),刀具可能在工件上產(chǎn)生劃痕。閱讀裝置必須要能以比控制系統(tǒng)處理數(shù)據(jù)更快的速度來(lái)閱讀數(shù)據(jù)程序塊。反饋裝置是用在一些數(shù)控設(shè)備上的安全裝置,它可連續(xù)補(bǔ)償控制位置與機(jī)床運(yùn)動(dòng)滑臺(tái)的實(shí)際位置之間的誤差。裝有這種直接反饋檢查裝置的數(shù)控機(jī)床有一個(gè)閉環(huán)系統(tǒng)裝置。位置控制通過(guò)傳感器實(shí)現(xiàn),在實(shí)際工作時(shí),記錄下滑臺(tái)的位置,并將這些信息送回控制單元。接受到的信號(hào)與紙帶輸入的信號(hào)相比較,它們之間的任何偏差都可得到糾正。在另一個(gè)稱(chēng)為開(kāi)環(huán)的系統(tǒng)中,機(jī)床僅由響應(yīng)控制器命令的步進(jìn)電動(dòng)機(jī)驅(qū)動(dòng)定位,工件的精度幾乎完全取決于絲杠的精度和機(jī)床結(jié)構(gòu)的剛度。有幾個(gè)理由可以說(shuō)明步進(jìn)電機(jī)是一個(gè)自動(dòng)化申請(qǐng)的非常有用的驅(qū)動(dòng)裝置。對(duì)于一件事物,它被不連續(xù)直流電壓脈沖驅(qū)使,是來(lái)自數(shù)傳計(jì)算機(jī)和其他的自動(dòng)化的非常方便的輸出控制系統(tǒng)。當(dāng)多數(shù)是索引或其他的自動(dòng)化申請(qǐng)所必備者的時(shí)候,步進(jìn)電機(jī)對(duì)運(yùn)行一個(gè)精確的有角進(jìn)步也是理想的。因?yàn)榭刂葡到y(tǒng)不需要監(jiān)聽(tīng)就提供特定的輸出指令而且期待系統(tǒng)適當(dāng)?shù)胤磻?yīng)的公開(kāi)-環(huán)操作造成一個(gè)回應(yīng)環(huán),步進(jìn)電機(jī)是理想的。一些工業(yè)的機(jī)械手使用高抬腿運(yùn)步的馬乘汽車(chē)駕駛員,而且步進(jìn)電機(jī)是有用的在數(shù)字受約束的工作母機(jī)中。這些申請(qǐng)的大部分是公開(kāi)-環(huán),但是雇用回應(yīng)環(huán)檢測(cè)受到驅(qū)策的成份位置是可能的。環(huán)的一個(gè)分析者把真實(shí)的位置與需要的位置作比較,而且不同是考慮過(guò)的錯(cuò)誤。那然后駕駛員能發(fā)行對(duì)步進(jìn)電機(jī)的電脈沖,直到錯(cuò)誤被減少對(duì)準(zhǔn)零位。在這個(gè)系統(tǒng)中,沒(méi)有信息反饋到控制單元的自矯正過(guò)程。出現(xiàn)誤動(dòng)作時(shí),控制單元繼續(xù)發(fā)出電脈沖。比如,一臺(tái)數(shù)控銑床的工作臺(tái)突然過(guò)載,阻力矩超過(guò)電機(jī)轉(zhuǎn)矩時(shí),將沒(méi)有響應(yīng)信號(hào)送回到控制器。因?yàn)?步進(jìn)電機(jī)對(duì)載荷變化不敏感,所以許多數(shù)控系統(tǒng)設(shè)計(jì)允許電機(jī)停轉(zhuǎn)。然而,盡管有可能損壞機(jī)床結(jié)構(gòu)或機(jī)械傳動(dòng)系統(tǒng),也有使用帶有特高轉(zhuǎn)矩步進(jìn)電機(jī)的其他系統(tǒng),此時(shí),電動(dòng)機(jī)有足夠能力來(lái)應(yīng)付系統(tǒng)中任何偶然事故。最初的數(shù)控系統(tǒng)采用開(kāi)環(huán)系統(tǒng)。在開(kāi)、閉環(huán)兩種系統(tǒng)中,閉環(huán)更精確,一般說(shuō)來(lái)更昂貴。起初,因?yàn)樵葌鹘y(tǒng)的步進(jìn)電動(dòng)機(jī)的功率限制,開(kāi)環(huán)系統(tǒng)幾乎全部用于輕加工場(chǎng)合,最近出現(xiàn)的電液步進(jìn)電動(dòng)機(jī)已越來(lái)越多地用于較重的加工領(lǐng)域。第四篇：機(jī)械專(zhuān)業(yè)英語(yǔ)復(fù)試詞匯總結(jié)（推薦）機(jī)械英語(yǔ)詞匯大全2金屬切削metalcutting機(jī)床machinetool拉孔broaching裝配assembling數(shù)學(xué)模型mathematicalmodel畫(huà)法幾何descriptivegeometry金屬工藝學(xué)technologyofmetals刀具cutter摩擦friction聯(lián)結(jié)link傳動(dòng)drive/transmission軸shaft彈性elasticity頻率特性frequencycharacteristic誤差error響應(yīng)response定位allocation機(jī)床夾具jig動(dòng)力學(xué)dynamic運(yùn)動(dòng)學(xué)kinematic靜力學(xué)static分析力學(xué)analysemechanics拉伸pulling壓縮hitting剪切shear鑄造found流體動(dòng)力學(xué)fluiddynamics機(jī)械制圖Mechanicaldrawing流體力學(xué)fluidmechanics投影projection加工machining視圖view液壓hydraulicpressure剖視圖profilechart切線tangent標(biāo)準(zhǔn)件standard機(jī)電一體化mechanotronicscomponentmechanical-electricalintegration零件圖partdrawing氣壓airpressurepneumaticpressure裝配圖assemblydrawing穩(wěn)定性stability尺寸標(biāo)注sizemarking介質(zhì)medium技術(shù)要求technical液壓驅(qū)動(dòng)泵fluidclutchrequirements液壓泵hydraulicpump剛度rigidity閥門(mén)valve內(nèi)力internalforce失效invalidation位移displacement強(qiáng)度intensity截面section載荷load疲勞極限fatiguelimit應(yīng)力stress斷裂fracture安全系數(shù)saftyfactor塑性變形plasticdistortion扭轉(zhuǎn)twist彎曲應(yīng)力bendingstress強(qiáng)度intensity三相交流電three-phaseAC磁路magneticcircles變壓器transformer異步電動(dòng)機(jī)asynchronousmotor幾何形狀geometrical精度precision正弦形的sinusoid交流電路ACcircuit機(jī)械加工余量machiningallowance變形力deformingforce變形deformation應(yīng)力stress硬度rigidity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