毕业设计英文翻译资料.docx
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毕业设计英文翻译资料.docx
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毕业设计英文翻译资料
Vol.1,2012
*Vehicles
*Mechatronics
*BasicsofMechanicalDesign
*MechanicalManufacture&Automation
MCanxixunInformationandNewsService
Contents
BasicsofMechanicalDesign2
(机械设计基础)2
AGuidetotheSelectionofLinearActuatorsforpositioningsystems(高小飞)2
Howtogetbettermotionwithplasticparts(王佳鹏)4
Hydraulicdrivescleanerair(杨海迎)7
Suppressioncircuitsforclutchesandbrakes(李慎龙)10
GettingENERGYSAVINGSfrompneumaticsystems(赵春)11
MechanicalManufacture&Automation15
(机械制造与自动化)15
Whathappenswhenautomationsystemsfail?
(赵方英)15
Teamdevelopsrobotsystemstoremoveaircraftcoatings(赵方英)16
Machineinsertsdifferent-sizedpinsinthesameassembly(李臣光)17
WorldwideCNCMarketReturnsBig(李臣光)18
EasierMachineVision(李臣光)18
Mechatronics(机电一体化)20
Howtoavoidelectricalhazardswithairlogic(钟雨锋)20
What’supwithmodel-basedengineering?
(许博)22
Researcherslooktosimplifydynamicsystemsdesign(许博)23
Metal-facedinductivesensorsfordurability(张应志)24
Aerospace、MarineTech&Application24
(海空技术与应用)24
Boeingcompletes737MAXconceptdevelopmentphase(张应志)25
Softwarecouldenablechangesearlyinaircraftdesignprocess(李帅)25
RockwellAutomationtosupplyPACsanddrivestoUSNavy(李帅)26
BasicsofMechanicalDesign
(机械设计基础)
AGuidetotheSelectionofLinearActuatorsforpositioningsystems(高小飞)
Specifyinglinearmotionsystemsisn’ttheblackartmanyengineersthinkitis.Thisarticleprovidessomeusefultipsandguidanceforengineersonhowtoselectthemostsuitablelinearactuatorsforsingleandmulti-axispositioningsystems.
Manyengineersarestillnotconfidentwhenitcomestoselectingsuitablelinearmotionsystemsforanapplication.Someengineersavoidlinearmotionsystemsaltogetherandreverttotheirtraditionalcomfortzoneofspecifyingrotaryalternatives,evenifthatmeansover-engineeringasolution.Inrealitythough,specifyinglinearmotionsystemsisnotthe‘blackart’thatmanyengineersthinkitis.
Onmostoccasions,ifengineersjustpickupthephoneanddiscusstheirapplicationwithalinearsystemssupplier,potentialissuescanusuallyberesolvedandasuitablesolutionfound.Bytalkingthroughtheirconcernswithanexperiencedlinearapplicationengineer,companiescanoftensavethemselvesalotofwasteddesigneffortorpreventthesystemfrombeingtoocostly(i.e.over-engineered).Thesuppliercanalsoinformthecustomerexactlywhatisandwhatisn’tpossibleintermsoflinearmotionsystemsandcanprovidevaluableadviceandguidanceonintegrateddrives,mountingarrangementsandfixings.
Inselectinglinearactuatorsforsingleandmulti-axishandling&positioningsystems,terminologycanbeconfusing.Manyengineerscommonlyrefertolinearactuatorsas‘linearmodules’,‘drivenlinearsystems’or‘linearX-Ytables’.Thesetypesofsystems,whichwewillrefertoaslinearmodules,normallyincorporateanumberofdifferentlineardrivesandactuators,includingbelt-drivenlinearactuators,ballscrew-drivenlinearactuators,lineartablesandlinearmotors.
Thefactorsbelowneedcarefulconsiderationwhenselectingasuitablelinearmoduleforasingle-axis,two-axisorthree-axispositioningsystem:
SystemConfiguration
Systemconfiguration,includingthenumberofaxesofmotion,isoftenthefirstfactorthatneedscarefulthought.Themostcommonaretwo-axis(X-Y)configurations,butlesscomplexsingle-axisapplicationsandthree-axisconfigurationsarealsopossible.
Orientation&Mounting
Systemorientationandmountingarealsokeyfactors.Inasingleaxislinearsystem,thisisfairlystraightforward,butinmultipleaxissystems,thisbecomesmorecomplex.Factorstoconsiderhereincludethedirectionoftravelofeachaxis.Doestheloadneedtobemovedsimultaneouslyinmultipleaxesordoeseachaxismoveindividually?
Doesthesystemrequireamovingcarriage(standard)oramovingrail?
Aretheaxesvertical,horizontalorinclined?
Arethemountingpositionsofeachactuatorat0,90or180degreestothehorizontal?
Otherfactorstoconsiderincludethespacingbetweensupportpointsinthesystem,aswellashowrigidandflatthesupportingsurfaceisfortheentirelinearpositioningsystem.
Mass&CentreofGravity
Themass(andgeometry)oftheobjecttobemovedandthepositionofitscentreofgravityasitmovesrelativetoacoordinateordatumpointoneachaxismustalsobecalculated.Clearly,asamassisacceleratedordeceleratedalongmultipleaxesoftravel,thepositionofitscentreofgravityrelativetoeachaxiswillchange.Thisneedscarefulconsiderationsothatthemomentloadsatmultiplepointsinthesystemcanbeestablished.Often,calculatingthebestandworst-casescenarios(usingdesigncalculationsoftwaresuchasSchaeffler’sLinearEasySolution)andthenaveragingtheseissufficientformostapplications.
Otherquestionshereincludewhethersufficientloadcarryingcapacity(includingstaticsafetyfactors)hasbeenallowedinthesystemtocaterforinstantaneousmomentloads?
Also,arethereareanyoverhungloadsinthesystem,includingdrives,electricmotorsormotorisedgearboxes?
StrokeLengths
The‘effective’and‘total’strokelengthforeachaxisisalsocritical.Withballscrewdrivenlinearactuators,forexample,thestrokelengthislimitedtothelengthoftheballscrewitself.Therefore,maximumstrokelengthstendtobearound3metres.Butwithbelt-drivensystems,therearenosuchrestrictionsandsostrokelengthscanbehigherthanthis,uptoasmuchas20metresifrequired.Iflinearmotorsarespecified,intheory,strokelengthisunlimited,butinreality,lengthsabove10metresarerare.
Accuracy&Repeatability
Dependingontheapplication,accuracyandrepeatabilitywilldiffergreatlybetweenapplications.Mostcustomersknowwhattheiraccuracyrequirementsarewhentheycontactus.Forexample,iftheactuatorisforanautomatedpick-and-placemachine,thenitislikelythathighrepeatabilityandaccuracyarerequired.Typically,theaccuracyofaballscrew-drivenlinearactuatoris0.16mmpermetrewithrepeatabilityof+/-0.01mm.Forbelt-drivenactuators,typicalaccuracyisaround0.5mmpermetre,withrepeatabilityof+/-0.10mm.
TraverseSpeeds&Accelerations
Thelimitingfactorsfortraversespeedsandtraversetimesaretheballscrewsand/orthebearings.Typically,withballscrew-drivenactuators,maximumspeedsof3m/sarepossible.Forbelt-drivenactuatorswithtrackrollerguidancesystems,themaximumspeedisaround8-9m/s.Ifrecirculatinglinearbearingsareusedwithbelt-drivenactuators,maximumspeedsaresimilartotheirballscrewequivalents(i.e.3m/s).
Accelerationitselfisnotnormallythedefiningissueinmulti-axispositioningsystems.Itistheloadsduetotheseaccelerationsinthesystemthatarecritical.Thehighestaccelerationofanylinearactuatortodateisaround40m/s2,althoughtypicallyaccelerationsaremorelikelytobemuchlessthanthis,oftenbetween0.5m/s2and5m/s2.Decelerationisalsoimportant,particularlyifthereareemergencystopsrequiredinthesystem.
Cycletimerequirements
Cycletimesdictatethelifeofalinearsystem.Forexample,apositioningsystemsuchasatoolchangeronamachinetoolmightchangethetoolfivetimesperhour.Howisthiscycletimegoingtovaryfromday-to-dayandhowwillthisaffectthefatiguelifeofthelinearcomponentswithinthesystem?
Ifthecustomerneedsthesystemtolastforaminimumof10years,changingthetoolfivetimeseveryhourmaynotbeanissue.Butifthetoolischanged10timesperhour,adifferenttypeoflinearsystemmayberequiredinordertoguaranteea10-yearoperatinglife.
ExternalLoads&Forces
Thisincludesexternalimpactforcesonthesystemsuchasstopsorhumaninterventions.Issomethingpushingorpullingontheloadtobemovedordoestheloadtobebroughtquicklytoastopattheendofitstravel?
Forexample,adrivemaybringthelinearactuatortoastopora‘home’datumposition.Howthisisachievedandhowthisaffectstheloadsonthemasstobemovedarekeyconsiderations.Asafetystrokefactormayalsoberequiredhere.
EnvironmentalFactors
Environmentalfactorssuchastemperature,humidityandcontamination(i.e.dust,oil,water,washdowns,chemicalsandcoolants,etc.)willalsoaffectthechoiceoflinearsystem.Adustyworkingenvironmentmayrequirethecustomertoimplementexternalbellowsordustextractiondevicesforthelinearsystem.Linearactuatorscanbeprotectedfromtheenvironmentbyincorporatingspecialseals,corrosion-resistantmaterialsandcoatings,specialgreasesorbyusingplasticpartswherenecessary.
Inmedicalapplications,theoverallnoiseofthesystemmaybeafactorthatneedsaddressing.Alowerspeedlinearactuatormaybethesolutionhere,butifhighspeedsneedtobemaintained,specialcomponents,materialsorcoatingsmayneedtobespecifiedinordertominimisenoiselevels.
ElectricalConsiderations
Formulti-axispositioningsystems,drivesandotherelectricalsystemsareoftencomplexandthereforerequirecarefulconsideration.Amulti-axislinearmoduleislikelytoincorporateelectricmotors,controllers,geareddrives,cables,grippers,limitswitches,encoders,brakesandothercontroldevices.
Howtogetbettermotionwithplasticparts(王佳鹏)
Polymerbearingsurfacesresistwear,don’tneedmaintenance,andcanrunsurprisinglyfast.
Engineersmightonlyglanceatthedimensionsandloadcapacitiesofrollerandcamfollowerstoensuretheywillfitintheirdesignbeforeplacinganorder.Buttheyshouldpaycloserattentionbecausethesecomponentscanmakeorbreaktheperfor
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