模具毕业设计外文翻译(英文+译文)

('模具毕业设计外文翻译InjectionMoldingThebasicconceptofinjectionmoldingrevolvesaroundtheabilityofathermoplasticmaterialtobesoftenedbyheatandtohardenwhencooled.Inmostoperations,granularmaterial(theplasticresin)isfedintooneendofthecylinder(usuallythroughafeedingdeviceknownasahopper),heated,andsoftened(plasticizedorplasticized),forcedouttheotherendofthecylinder,whileitisstillintheformofamelt,throughanozzleintoarelativelycoolmoldheldclosedunderpressure.Here,themeltcoolsandhardensuntilfullyset-up.Themoldisthenopened,thepieceejected,andthesequencerepeated.Thus,thesignificantelementsofaninjectionmoldingmachinebecome:1)thewayinwhichthemeltisplasticized(softened)andforcedintothemold(calledtheinjectionunit);2)thesystemforopeningthemoldandclosingitunderpressure(calledtheclampingunit);3)thetypeofmoldused;4)themachinecontrols.Thepartofaninjection-moldingmachine,whichconvertsaplasticmaterialfromasoldphasetohomogeneousseni-liguidphasebyraisingitstemperature.Thisunitmaintainsthematerialatapresenttemperatureandforceitthroughtheinjectionunitnozzleintoamold.Theplungerisacombinationoftheinjectionandplasticizingdeviceinwhichaheatingchamberismountedbetweentheplungerandmold.Thischamberheatstheplasticmaterialbyconduction.Theplunger,oneachstroke;pushesunbeltedplasticmaterialintothechamber,whichinturnforcesplasticmeltatthefrontofthechamberoutthroughthenozzleThepartofaninjectionmoldingmachineinwhichthemoldismounted,andwhichprovidesthemotionandforcetoopenandclosethemoldandtoholdthemoldclosewithforceduringinjection.Thisunitcanalsoprovideotherfeaturesnecessaryfortheeffectivefunctioningofthemoldingoperation.Movingplateisthememberoftheclampingunit,whichismovedtowardastationarymember.themovingsectionofthemoldisboltedtothismovingplate.Thismemberusuallyincludestheejectorholesandmoldmountingpatternofblotholesor“T”slots.Stationaryplateisthefixedmemberoftheclampingunitonwhichthestationarysectionofthemoldisbolted.Thismemberusuallyincludesamold-mounting模具毕业设计外文翻译patternofbolesor“T”slots.Tierodsarememberoftheclampingforceactuatingmechanismthatserveasthetensionmemberoftheclampwhenitisholdingthemoldclosed.Theyalsoserveasaguttedmemberforthemovableplate.Ejectorisaprovisionintheclampingunitthatactuatesamechanismwithinthemoldtoejectthemoldedpart(s)fromthemold.Theejectionactuatingforcemaybeappliedhydraulicallyorpneumaticallybyacylinder(s)attachedtothemovingplate,ormechanicallybytheopeningstrokeofthemovingplate.Methodsofmeltingandinjectingtheplasticdifferfromonemachinetoanotherandareconstantlybeingimplored.conventionalmachinesuseacylinderandpistontodobothjobs.Thismethodsimplifiesmachineconstructionbutmakescontrolofinjectiontemperaturesandpressuresaninherentlydifficultproblem.Othermachinesuseaplasticizingextrudertomelttheplasticandpistontoinjectitwhilesomeharebeendesignedtouseascrewforbothjobs:Nowadays,sixtypercentofthemachinesuseareciprocatingscrew,35%aplunger(concentratedinthesmallermachinesize),and5%ascrewpot.Manyoftheproblemsconnectedwithinejectionmoldingarisebecausethedensitiesofpolymerschangesomarkedlywithtemperatureandpressure.thightemperatures,thedensityofapolymerisconsiderablycowerthanatroomtemperature,providedthepressureisthesame.Therefore,ifmoldswerefilledatatmosphericpressure,“shrinkage”wouldmakethemoldingdeviateformtheshapeofthemold.Tocompensateforthispooreffect,moldsarefilledathighpressure.Thepressurecompressesthepolymerandallowsmorematerialstoflowintothemold,shrinkageisreducedandbetterqualitymoldingsareproduced.Cludesamold-mountingpatternofboltholesor“T”slots.Tierodsaremembersoftheclampingforceactuatingmechanismthatserveasthetensionmembersofclampwhenitisholdingthemoldclosed.Ejectorisaprovisioninthecalmingunitthatactuatesamechanismwithinthemoldtoejectthemoldedpart(s)formthemold.Theejectionactuatingforcemaybeappliedhydraulicallyorpneumaticallybyacylinder(s)attachedtothemovingplate,ormechanicallybytheopeningstrokeofthemovingplate.Thefunctionofamoldistwofold:impartingthe模具毕业设计外文翻译desiredshapetotheplasticizedpolymerandcoolingtheinjectionmoldedpart.Itisbasicallymadeupoftwosetsofcomponents:thecavitiesandcoresandthebaseinwhichthecavitiesandcoresaremounted.Themold,whichcontainsoneormorecavities,consistsoftwobasicparts:(1)astationarymoldshalfonethesidewheretheplasticisinjected,(2)Movinghalfontheclosingorejectorsideofthemachine.Theseparationbetweenthetwomoldhalvesiscalledthepartingline.Insomecasesthecavityispartlyinthestationaryandpartlyinthemovingsection.Thesizeandweightofthemoldedpartslimitthenumberofcavitiesinthemoldandalsodeterminethemachinerycapacityrequired.Themoldcomponentsandtheirfunctionsareasfollowing:(1)MoldBase-Holdcavity(cavities)infixed,correctpositionrelativetomachinenozzle.(2)GuidePins-MaintainProperalignmentofentryintomoldinterior.(3)SpreeBushing(spree)-Providemeansofentryintomoldinterior.(4)Runners-Conroymoltenplasticfromspreetocavities.(5)Gates-Controlflowintocavities.(6)Cavity(female)andForce(male)-Controlthesize,shapeandsurfaceofmoldarticle.(7)WaterChannels-Controlthetemperatureofmoldsurfacestochillplastictorigidstate.(8)Side(actuatedbycame,gearsorhydrauliccylinders)-Formsideholes,slots,undercutsandthreadedsections.(9)Vent-Allowtheescapeoftrappedairandgas.(10)EjectorMechanism(pins,blades,stripperplate)-Ejectrigidmoldedarticleformcavityorforce.(11)EjectorReturnPins-Returnejectorpinstoretractedpositionasmoldclosesfornextcycle.Thedistancebetweentheoutercavitiesandtheprimaryspreemustnotbesolongthatthemoltenplasticlosestoomuchheatintherunnertofilltheoutercavitiesproperly.Thecavitiesshouldbesoarrangedaroundtheprimaryspreethateachreceivesitsfullandequalshareofthetotalpressureavailable,throughitsownrunnersystem(ortheso-calledbalancedrunnersystem).Therequirestheshortestpossibledistancebetween模具毕业设计外文翻译cavitiesandprimarysprue,equalrunnerandgatedimension,anduniformculling.注射成型注射成型的基本概念是使热塑性材料在受热时熔融，冷却时硬化，在大部分加工中，粒状材料（即塑料树脂）从料筒的一端（通常通过一个叫做“料斗”的进料装置）送进，受热并熔融（即塑化或增塑），然后当材料还是溶体时，通过一个喷嘴从料筒的另一端挤到一个相对较冷的压和封闭的模子里。溶里在模腔里冷却，硬化，直至完全固化。然后将模子打开，推出工件，并重复以上工序。因此，注塑成型机的重要组成部分是：1）将溶体塑化并挤进进模腔（称做“注塑单元”）；2）开模和家压合模9称为“合模系统”）；3）使用上午模具类行；4）机器控制。注射装置通过家热将固态塑料转化成均匀的半液态塑体。它保持塑料当前温度并加压使之通过喷嘴进入模具。柱塞集塑化和注射为一体。在柱塞与模具之间没有加热室，几热室通过热传导加热塑料。每次行程，柱塞将待熔化塑料推入加热室，依次将熔化的塑料挤到加热室前端并通过喷嘴注射出去（注射到模具中去）合模装置是注射成型机的一个部分，该装置上安装有模具。合模装置提供运动和动力以开模几合模，并且在注射过程中提供压力保持模具紧闭同时，该装置还提供成型工艺有效运动所必需的其它特性。动模板是合模装置的一部分，在合模时向定模板移动。型腔的运动部分用螺栓固定在动模板上，动模板通常动模板通常含顶出杆，螺栓空或T型槽的安装模具的型板。拉杆是合模力驱动机构中的一个构件，当夹具保持动模闭合时，拉杆起夹具的拉力构件的作用。顶出器是合模装置的一个部件，它驱动模具中的执行机构从模具中顶出成型制品。顶出力可由液压或气动装置通过装在动模板上的油（气）缸来施加，或者通过动模板开模行程来施加。塑料熔融与塑料注射的方式随机器的不同而不同,并不断得以改善。常规的机器采用一个料筒和一个活塞来进行熔融和注射。虽然这种方式简化了机器的结构，但却使注射的温度和压力控制成了一个固有的难题。有的机器用一个塑化挤压器来熔化塑料，用一个活塞进行注射。另外，还有一些已设计出来的机器采用一个螺杆来完成熔模具毕业设计外文翻译融和注射。目前，百分之六十的机器采用往复式螺杆，百分之三十五的机器采用柱塞；百分之六十的机器采用螺罐。聚合物的密度在不同的温度和压力下变化很大，并由此产生了注射成型的许多问题。在压力不变的情况下，在高温下的聚合物的密度比在低温下的要低得多，因此，如果在大气压下向模子充模，成型件回因“收缩”而与模子的形状形成偏差。为了补偿这一偏差，模子充料在高压下进行。高压压缩了聚合物并能使更多的材料流入模腔。这样，“收缩”就减少了，生产的成型件的质量就得以提高。模具的功能有两方面：一是使可塑聚合物按希望的形状成型，而是使其冷却定型。注射模具基本由两套部件组成：型腔和型芯，安装型腔和型芯的模板。具有一个型腔或多个型腔的模具由两个基本部分组成：（1）注射塑料一侧的定模（2）闭合及顶出机器一侧的动模。两哈夫对开的定模、动模分界线叫做分型面。有时，型腔一部分在定模中，一部分在动模中。塑料成型制品的尺寸和重量限制了一副模具中型腔的数目，并且取得了所需的注射机床生产能力。模具的零部件及其功能如下：（1）模板—保持型腔相对注射机床的喷嘴具有固定、正确的位置。（2）导柱—保持定模、动模哈夫在合模时具有正确的相对位置。（3）主流道衬套—提供熔融塑料流入模具内部的通道。（4）流道—将容忍塑料从浇注口传送到各型腔。（5）浇口—控制熔融塑料流入型腔。（6）凹模（阴模）和凸模（阳模）—控制成型塑料制品的尺寸、形状及表面纹理。（7）冷却水道—控制模具表面温度，使塑料制品冷固成型。（8）侧板（由凸轮、齿轮或液压油缸驱动）—形成制品的侧孔、侧槽、侧凹螺纹部分。',)