机械设计外文文献

1、MechanicalDesignJohnErnstAbstract：Amachineisacombinationofmechanismsandothercomponentswhichtransformstransmits.Examplesareengines,turbines,vehicles,hoists,printingpresses,washingmachines,andmoviecameras.Manyoftheprinciplesandmethodsofdesignthatapplytomachinesalsoapplytomanufacturedarticlesthatarenot

2、truemachines.Thetermmechanicaldesignisusedinabroadersensethanmachinedesigntoincludetheirdesign.Themotionandstructuralaspectsandtheprovisionsforretentionandenclosureareconsiderationsinmechanicaldesign.Applicationsoccurinthefieldofmechanicalengineering,andinotherengineeringfieldsaswell,allofwhichrequi

3、remechanicaldevices,suchasswitches,cams,valves,vessels,andmixers.Keywords:MechanicalDesign；MechanismsDesignProcess；ApplicationTheDesignProgressDesigningstartswithaneedreal.Existingapparatusmayneedimprovementsindurability,efficiency,weight,speed,orcost.Newapparatusmaybeneededtoperformafunctionpreviou

4、slyDonebymen,suchascomputation,assembly,orservicing.WiththeobjectivewhollyorpartlyInthedesignpreliminarystage,shouldallowtodesignthepersonnelfullytodisplaythecreativity,noteachkindofrestraint.Evenifhashadmanyimpracticalideas,alsocaninthedesignearlytime,namelyinfrontoftheplanblueprintiscorrected.Only

5、then,onlythendoesnotsendtostopsuptheinnovationthementality.Usually,mustproposeseveralsetsofdesignproposals,andthenperformthecomparison.Hasthepossibilityverymuchintheplanwhichfinallydesignated,hasusedcertainnotinplansomeideaswhichaccepts.Whenthegeneralshapeandafewdimensionsoftheseveralcomponentsbecom

6、eapparent,analysiscanbegininearnest.Theanalysiswillhaveasitsobjectivesatisfactoryorsuperiorperformance,plussafetyanddurabilitywithminimumweight,andacompetitivecost.Optimumproportionsanddimensionswillbesoughtforeachcriticallyloadedsection,togetherwithabalancebetweenthestrengthsoftheseveralcomponents.

7、Materialsandtheirtreatmentwillbechosen.Theseimportantobjectivescanbeattainedonlybyanalysisbasedupontheprinciplesofmechanics,suchasthoseofstaticforreactionforcesandfortheoptimumutilizationoffriction;ofdynamicsforinertia,acceleration,andenergy;ofelasticityandstrengthofmaterialsforstressanddeflection;o

8、fphysicalbehaviorofmaterials;andoffluidmechanicsforlubricationandhydrodynamicdrives.Theanalysesmaybemadebythesameengineerwhoconceivedthearrangementofmechanisms,or,inalargecompany,theymaybemadebyaseparateanalysisdivisionorresearchgroup.Designisareiterativeandcooperativeprocess,whetherdoneformallyorin

9、formally,andtheanalystcancontributetophasesotherthanhisown.Productdesignrequiresmuchresearchanddevelopment.ManyConceptsofanideamustbestudied,tried,andtheneitherusedordiscarded.Althoughthecontentofeachengineeringproblemisunique,thedesignersfollowthesimilarprocesstosolvetheproblems.Productliabilitysui

10、tsdesignersandforcedinmaterialselection,usingthebestprogram.Intheprocessofmaterial,themostcommonproblemsforfive(a)dontunderstandornotuseaboutthelatestapplicationmaterialstothebestinformation,(b)failedtoforeseeandconsiderthereasonableusematerialmay(suchaspossible,designersshouldfurtherforecastandcons

11、iderduetoimproperuseproducts.Inrecentyears,manyproductsliabilityinlitigation,theuseofproductsandhurttheplaintiffaccusedmanufacturer,andwonthedecision),(c)ofthematerialsusedallorsomeofthedata,data,especiallywhentheuncertaintylong-termperformancedataisso,(d)qualitycontrolmethodisnotsuitableandunproven

12、,(e)bysomecompletelyincompetentpersonschoosematerials.Throughtotheabovefivequestionsanalysis,mayobtainthesequestionsisdoesnothavethesufficientreasonexistencetheconclusion.Mayforavoidthesequestionstothesequestionsresearchanalysestheappearanceindicatingthedirection.Althoughusesthebestchoiceofmaterialm

13、ethodnottobeabletoavoidhavingtheproductresponsibilitylawsuit,designsthepersonnelandtheindustrycarriesonthechoiceofmaterialaccordingtothesuitableprocedure,maygreatlyreducethelawsuitthequantity.Mayseefromtheabovediscussion,thechoicematerialpeopleshouldtothematerialnature,thecharacteristicandtheprocess

14、ingmethodhavecomprehensiveandthebasicunderstanding.Finally,adesignbaseduponfunction,andaprototypemaybebuilt.Ifitstestsaresatisfactory,theinitialdesignwillundergocertainmodificationsthatenableittobemanufacturedinquantityatalowercost.Duringsubsequentyearsofmanufactureandservice,thedesignislikelytounde

15、rgochangesasnewideasareconceivedorasfurtheranalysesbasedupontestsandexperienceindicatealterations.Salesappeal.SomeRulesforDesignInthissectionitissuggestedthat,appliedwithacreativeattitude,analysescanleadtoimportantimprovementsandtotheconceptionandperfectionofalternate,perhapsmorefunctional,economica

16、l,anddurableproducts.Tostimulatecreativethought,thefollowingrulesaresuggestedforthedesignerandanalyst.Thefirstsixrulesareparticularlyapplicablefortheanalyst.(1)Acreativeuseofneedofphysicalpropertiesandcontrolprocess.(2)Recognizefunctionalloadsandtheirsignificance.Anticipateunintentionalloads.Devisem

17、orefavorableloadingconditions.Provideforfavorablestressdistributionandstiffnesswithminimumweight.Usebasicequationstoproportionandoptimizedimensions.(7)Choosematerialsforacombinationofproperties.(8)Selectcarefully,stockandintegralcomponents.(9)Modifyafunctionaldesigntofitthemanufacturingprocessandred

18、ucecost.(10)Provideforaccuratelocationandnoninterferenceofpartsinassembly.Machinerydesigncoversthefollowingcontents.Providesanintroductiontothedesignprocess,problemformulation,andsafetyfactors.Reviewsthematerialpropertiesandstaticanddynamicloadinganalysis,Includingbeam,vibrationandimpactloading.Revi

19、ewsthefundamentalsofstressanddefectionanalysis.(4)Introducesfatigue-failuretheorywiththeemphasisonstress-lifeapproachestohigh-cyclefatiguedesign,whichiscommonlyusedinthedesignofrotationmachinery.Discussesthoroughlythephenomenaofwearmechanisms,surfacecontactstresses,andsurfacefatigue.Investigatesshaf

20、tdesignusingthefatigue-analysistechniques.Discussesfluid-filmandrolling-elementbearingtheoryandapplicationGivesathoroughintroductiontothekinematics,designandstressanalysisofspurgears,andasimpleintroductiontohelical,bevel,andwormgearing.Discussesspringdesignincludingcompression,extensionandtorsionspr

21、ings.Dealswithscrewsandfastenersincludingpowerscrewandpreloadfasteners.Introducesthedesignandspecificationofdiskanddrumclutchesandbrakes.Thecompletedesignofamachineisacomplexprocess.Themachinedesignisacreativework.Projectengineernotonlymusthavethecreativityinthework,butalsomustinaspectandsoonmechani

22、caldrawing,kinematics,engineeringmaterial,materialsmechanicsandmachinemanufacturetechnologyhasthedeepelementaryknowledge.Oneofthefirststepsinthedesignofanyproductistoselectthematerialfromwhicheachpartistobemade.Numerousmaterialsareavailabletotodaysdesigners.Thefunctionoftheproduct,itsappearance,thec

23、ostofthematerial,andthecostoffabricationareimportantinmakingaselection.Acarefulevaluationofthepropertiesofa.materialmustbemadepriortoanycalculations.Carefulcalculationsarenecessarytoensurethevalidityofadesign.Incaseofanypartfailures,itisdesirabletoknowwhatwasdoneinoriginallydesigningthedefectivecomp

24、onents.Thecheckingofcalculations(anddrawingdimensions)isofutmostimportance.Themisplacementofonedecimalpointcanruinanotherwiseacceptableproject.Allaspectsofdesignworkshouldbecheckedandrechecked.Thecomputerisatoolhelpfultomechanicaldesignerstolightentediouscalculations,andprovideextendedanalysisofavai

25、labledata.Interactivesystems,basedoncomputercapabilities,havemadepossibletheconceptsofcomputeraideddesign(CAD)andcomputer-aidedmanufacturing(CAM).Howdoesthepsychologistfrequentlydiscusscausesthemachinewhichthepeopleadaptsthemtooperate.Adesignpersonnelsbasicresponsibilityisdiligentlycausesthemachinet

26、oadaptthepeople.Thiscertainlyisnotaneasywork,becausecertainlydoesnothavetoallpeopletosayinfactallisthemostsuperioroperatingareaandtheoperatingprocess.Anotherimportantquestion,projectengineermustbeabletocarryontheexchangeandtheconsultationwithotherconcernedpersonnel.Intheinitialstage,designstheperson

27、neltohavetocarryontheexchangeandtheconsultationonthepreliminarydesignwiththeadministrativepersonnel,andisapproved.Thisgenerallyisthroughtheoraldiscussion,theschematicdiagramandthewritingmaterialcarrieson.Iffrontsues,themachinedesigngoalistheproductioncanmeetthehumanneedtheproduct.Theinvention,thedis

28、coveryandtechnicalknowledgeitselfcertainlynotnecessarilycanbringtheadvantagetothehumanity,onlyhaswhentheyareappliedcanproduceontheproductthebenefit.Thus,shouldrealizetocarriesonbeforethedesigninaspecificproduct,mustfirstdeterminewhetherthepeopledoneedthiskindofproductMustregardasthemachinedesignisth

29、emachinedesignpersonnelcarriesonusingcreativeabilitytheproductdesign,thesystemanalysisandaformulationproductmanufacturetechnologygoodopportunity.Graspstheprojectelementaryknowledgetohavetomemorizesomedataandtheformulaismoreimportantthan.Themerelyservicedataandtheformulaisinsufficienttothecompletelyd

30、ecisionwhichmakesinagooddesignneeds.Ontheotherhand,shouldbeearnestpreciselycarriesonalloperations.Forexample,evenifplaceswrongadecimalpointposition,alsocancausethecorrectdesigntoturnwrongly.Gooddesignpersonnelshoulddaretoproposethenewideamoreoveriswillingtoundertakethecertainrisk,whenthenewmethodisn

31、otsuitable,useoriginalmethod.Therefore,designsthepersonneltohavetohavetohavethepatience,becausespendsthetimeandtheendeavorcertainlycannotguaranteebringssuccessfully.Abrand-newdesign,therequestscreenabandonsabsolutelymany,knowsverywellthemethodforthepeople.Becausemanypersonofconservativenessdoesthisc

32、ertainlyisnotaneasymatter.Amechanicaldesignershouldunceasinglyexploretheimprovementexistingproductthemethod,shouldearnestlychooseoriginally,theprocessconfirmationprincipleofdesigninthisprocess,withhasnotunifieditaftertheconfirmationnewidea.Humanlifecannotbeseparatedfromthemachinery,itiseverywhere,bu

33、tforthemechanicalmanufacturing,production,anditsdevelopmentandfuture,weknowlittleabout.Afterthissemester,Ihavemoreknowledgeandunderstandingoftheprofessionofthemechanical.Fromtheprimitivesocietyofearlyhumanusesuchasaxes,knivesandothersimpletools,toasimplelever,pulley,humanbicycles,animal-KipShumcarto

34、ols,developedtoamorecomplexhydraulicdrive,wind-drivenShuinianandwindmillsmorecomplexmachinery.Afterthe18thcenturyBritishIndustrialRevolution,thesteamengine,internalcombustionengines,electricmotors,mechanicalpowersourcefortherapiddevelopmentofmanufacturing,transport,humanbeingsbegantoenterthemodernci

35、vilizedsociety.The20thcentury,thecomputerissuingautomaticcontroltechnology,informationtechnology,infectiousorganiccombinationoftechnology,sothatthemachineryisfullymodernizedphase.Robotics,CNCmachinetools,high-speeddeliveryvehicles,heavymachineryandthelargenumberofadvancedmachineryandequipmenttoaccel

36、eratetheprosperityandprogressofhumansociety,humanscantravelintospace,landingonthemoon,youcanexplorethevastdepthsofthesea,toliveandpassbelowthesurfaceallofwhichcannotbeseparatedfromthemachinery,thedevelopmentofthemachineryintotheintelligentstage.Machineryhasbecomeoneofthefiveelementsofproductionandse

37、rvicesofmodernsociety.Thehistoryofthedevelopmentofthemechanicalhistoryofthedevelopmentofhumancivilization.InancientChinesemechanicalengineering,inventionandcreativityisverybrilliant,suchasgrindingtechnology,metalsmeltingtechnology.Chinasmachinerymanufacturingindustrydevelopedafter1949.AfterthefoundingofnewChina,thetremendousachievementsofChinaseconomyareinseparablefromtheprogressofthemanufacturingsector.Afterdecadesofstruggle,Chinasmanufacturingcomponentswithconsiderablescaleand