冲压模具类中英文翻译、外文文献翻译、外文翻译

二、TheinjectionandCompressionMoldingInjectionmoldingsiprincipallyusedfortheproductionofthethermoplasticparts,althoughsomeprogresshasbeenmadeindevelopingamethodforinjectionmoldingsomethermosettingmaterials.Theproblemofinjectingameltedplasticintoamoldcavityformareservoirofmeltedmaterialhasbeenextremelydifficulttosolveforthermosettingplasticswhichcureandhardenundersuchconditionswithinafewminutes.Theprincipleofinjectionmoldingisquitesimilartothatofdie-casting.Theprocessconsistsoffeedingaplasticcompoundinpowderedorgranularformfromahopperthroughmeteringandmeltingstagesandtheninjectingitintoamold.Afterabriefcoollingperiod,themoldisopenedandthesolidifiedpartejected.Injection-moldingmachinescanbearrangedformanualoperation,automaticsingle-cucleoperation,andfullautomaticoperation.Theadvantageofinjectionmoldingare:ahighmoldingspeedadaptedformassproductionispossible;thereisawidechoiceofthermoplasticmaterialsprovidingavarietyofusefullproperties;itispossibletomoldthreads,undercuts,sideholes,andlargethinsections.Severalmethodsareusedtoforceorinjectthemeltedplasticintothemold.Themostcommonlyusedsysteminthelargermachinesisthein-linereciprocatingscrew.Thescrewactsasacombinationandplasticizingunit.Astheplasticisfedtotherotatingscrew,itpassesthroughthreezonesasshown:feed,compression,andmetering.Afterthefeedzone,thescrew-flightdepthisgraduallyreduced,forcingtheplastictocompress.Theworkisconvertedtoheatbyshearingtheplastic,makingitasemifluidmass.Inthemeteringzone,additionalheatisappliedbyconductionfromthebarrelsurface.Asthechamberinfrontofthescrewbecomesfilled,itforcesthescrewback,trippingalimitswitchthatactivatesahydrauliccylinderthatforcesthescrewforwardandinjectsthefluidplasticintotheclosedmold.Anantiflowbackvalvepreventsplasticunderpressurefromescapingbackintothescrewflights.Theclampingforcethatamachineiscapableofexertingispartofthesizedesignationandismeasuredintons.Arule-of-thumbcanbeusedtodeterminethetonnagerequiredforaparticularjob.Itisbasedontwotonsofclampforcepersquareinchofprojectedarea.Iftheflowpatternisdifficultandthepartsarethin,thismayhavetogotothreeorfourtons.Manyreciprocating-screwmachinesarecapableofhandingthermosettingplasticmaterials.Previouslythesematerialswerehandledbycompressionortransfermolding.Thermosettingmaterialscureorpolymerizeinthemoldandareejectedhotintherangeof375℃～410℃.Thermoplasticpartsmustbeallowedtocoolinthemoldinordertoremovethemwithoutdistortion.Thusthermosettingcyclescanbefaster.Ofcoursethemoldmustbeheatedratherthanchilled,aswiththermoplastics.TheimportanceofInjectingthemoldare:⑴、Plasticshavethedensitysmall,thequalitylight,thespecifictenacitybig,theinsulatingpropertygood,thedielectriclosslow,thechemicalstabilitystrong,theformationproductivityhighandthepriceinexpensiveandsoonthemerits,obtaineddaybydaythewidespreadapplicationinthenationaleconomyandpeople'sdailylifeeachdomain,asearlyasinthebeginningof1990s,theplasticannualoutputalreadysurpassedthesteelandironandthenon-ferrousmetalannualoutputsumtotalaccordingtothevolumecomputation.Inmechanicalandelectrical(forexampleso-calledblackelectricalappliances),domainsandsoonmeasuringappliance,chemical,theautomobileandastronauticsaviation,theplastichasbecomethemetalthegoodsubstitutionmaterial,hadthemetalmaterialplastictendency.⑵、Taketheautomobileindustryastheexample,asaresultoftheautomobilelightweight,thelowenergyconsumptiondevelopmentrequest,theautomobilesparepartmaterialconstitutionoccurredobviouslyhasmodelledthebandsteelthechange,atpresentourcountryautomobileplasticaccountsfor5%whichtheautomobilewasself-possessedto6%,butoverseashasreached13%,forecastaccordingtotheexpert,theautomobileplasticbicycleamountusedwillalsobeablefurthertoincrease.Onmodernvehicles,regardlessofisoutsideinstallstheassorteditems,theinternalinstallationassorteditems,thefunctionandthestructuralelement,allmayusetheplasticmaterial,outsideinstallstheassorteditemstohavethebumper,thefender,thewheelhubcap,theairdeflectorandsoon;Aftertheinternalinstallationassorteditemshaveinthedisplayboard,thevehicledoortheboard,thevice-displayboard,thesundrygoodsboxlid,thechair,theguardshieldandsoon;Thefunctionandthestructuralelementhavethefueltank,theradiatorheader,thespatialfilterhood,thefanbladeandsoon.Statisticshaveindicated,ourcountryin2000automobileoutputmorethan200tenthousand,thevehicleamountedto1,380,000tonswiththeplastic.Lookedfromthedomesticandforeignautomobileplasticapplicationsituationthat,theautomobileplasticamountusedalreadybecameoneofweightautomobileproductiontechnicallevelsymbols.⑶、Injectionofamoldingformationasplasticworkpiecemosteffectiveformationmethodsbecausemaybyonetimetakeshapeeachkindofstructurecomplex,thesizepreciseandhasthemetaltoinlayaproduct,andtheformationcycleisshort,maybymoldmulti-cavities,theproductivitybehigh,whenmassproductionsthecostisveryinexpensive,easytorealizetheautomatedproduction,thereforeholdstheextremelyimportantstatusintheplasticprocessingprofession.Statisticshaveindicated,plasticmoldcompositionallmolds(includingmetalpattern)38.2%,theplasticproductgrossweightabout32%isusesininjectingtheformation,80%aboveengineeringplasticsproductallmustusetheinjectionformationwayproduction.4.countsaccordingtothecustoms,ourcountryin2000altogetherimportedmold977,000,000USdollars,inwhichplasticmoldingformsaltogether550,000,000USdollars,occupiedfor56.3%,2001yearsaltogethertoimportmold1,112,000,000USdollars,inwhichplasticmoldingformsaltogether616,000,000USdollars,accountedfor55.4%.Fromthevariety,theimportvolumebiggestistheplasticmoldingforms.⑷、Countsaccordingtothecustoms,ourcountryin2000altogetherimportedmold977,000,000USdollars,inwhichplasticmoldingformsaltogether550,000,000USdollars,occupiedfor56.3%,2001yearsaltogethertoimportmold1,112,000,000USdollars,inwhichplasticmoldingformsaltogether616,000,000USdollars,accountedfor55.4%.Fromthevariety,theimportvolumebiggestistheplasticmoldingforms.Incompressionmoldingthepalsticmaterialaspowderorpreformsisplacedintoaheatedsteelmoldcavity,Sincethepartingsurfaceisinahorizontalplane,theupperhalfofthemolddescendsvertically.Itclosesthemoldcavityandpressuresforapredeterminedperiod.Apressureoffrom2to3tonssquareinchandatemperaureatapproximately350Fconvertstheplastictoasemiliquidwhichflowstoallpartsofthemoldcavity.Usuallyfrom1to15minutesisrequiredforcuring,altougharecentlydevelopedalkydplasticwillcureinlessthan25secends.Themoldisthenopendedandthemoldedpartremoved.Ifmetalinsersaredesiredintheparts,theyshouldbeplacedinthemoldcavityonpinsorintheholesbeforetheplasticisloaded.Also,thepreformsshouldbepreheatedbeforeloadingintothemoldcavitytoeliminategases,inproveflow,anddecreasecuringtime.Dieletricheatingisaconvenientmethodofheatingthepreforms.Sincetheplasticmaterialisplaceddirectlyintothemoldcavity,themolditselfcanbesimplerthanthoseusedforothermoldingprecesses.Gatesandspruesareunnecessary.Thisalsoresultsinasavinginmaterial,becausetrimmed-offgatesandsprueswouldbeacompletelossofthethermosettingplastic.Thepressrequirethefullattentionofoneoperator.However,severalsmallerpressescanbeoperatedbyoneoperator.Thepressesareconvenientlylocatedsotheoperatorcaneasilymovefromonetothenext.Bythetimehegetsaroundtoaparticularpressagain,thatmoldwillbereadytoopen.thethermosettingplasticswhichhardenunderheatandpressurearesuitableforcompressionmoldingandtransfermolding.Itisnotpracticaltomoidshermoplasticmaterialsbythesemethods,sincethemoldswouldhavetobealternatelyheatedandcooled.Inordertohardenandejectthermoplasticpartsformthemold,coolingwouldbenecessary.Typesofmoldsforcompressionmolding.Themoldsusedforcompressionmoldingareclassifiedintofourbasictypes,namely,positivemolds,landedpositivemold,flash-typemolds,andsemipositivemolds.Inapositivemoldtheplungerontheuppermoldentersthelowermoldcavity.sincetherearenolandsorstopsonthelowerdie,theplungercompletelytraptheplasticmaterialanddescendswithfullpressureonthecharge.Adensepartwithgoodelectricalandphysicalpropertiesisproduced.Theamountofplasticplacedinthediecavitymustbeaccuratelymeasured,sinceitdeterminesthethicknessofthepart.Alandedpositivemoldissimilartoapositivemoldexceptthatlandsareaddedtostopthetraveloftheplungeratpredeterminedpoint.Inthiscase,thelandsabsorbsomeofthepressurethatshouldbeexertedontheparts.Thethicknessofthepartswillbeaccuratelycontrolled,butthedensitymayvarycansideraby.Inaflash-typemold,flashredgesareaddedtithetopandbottommolds.Astheuppermoldexertspressureontheplastic,excessmaterialisforcedoutbetweentheflashridgeswhereitformsflash.Thisflashisfurthercompressed.becomeshardened,andfinallystopsthedownardthaveloftheuppermold.Aslightexcessoftheplasticmaterialisalwayscharedtoensuresufficientpressurstoproduceadensemoldedpart.Thistypeofmoldiswidelyusedbecauseitiscomparativelyeasytoconstructanditcontrolsthicknessanddensitywithincolselimits.Thesemipositivemoldisacombinationodtheflashtypeandlandedposivemolds.Inadditiontotheflashridges,alandisemployedtorestrictthetraveloftheuppermold.

汽车开发周期从40个月缩短到4个月。1、模具在工业发展中的地位采用模具生产零部件，具有生产效率高、质量好、成本低、节约能源和原材料等一系列优点，用模具生产制件所具备的高精度、高复杂程度、高一致性、高生产率和低消耗，是其他加工制造方法所不能比拟的。已成为当代工业生产的重要手段和工艺发展方向。现代经济的基础工业。现代工业品的发展和技术水平的提高，很大程度上取决于模具工业的发展水平，因此模具工业对国民经济和社会发展将起越来越大的作用。1989年3月国务院颁布的《关于当前产业政策要点的决定》中，把模具列为机械工业技术改造序列的第一位、生产和基本建设序列的第二位(仅次于大型发电设备及相应的输变电设备)，确立模具工业在国民经济中的重要地位。1997年以来，又相继把模具及其加工技术和设备列入了《当前国家重点鼓励发展的产业、产品和技术目录》和《鼓励外商投资产业目录》。经国务院批准，从1997年到2000年，对80多家国有专业模具厂实行增值税返还70%的优惠政策，以扶植模具工业的发展。所有这些，都充分体现了国务院和国家有关部门对发展模具工业的重视和支持。目前全世界模具年产值约为600亿美元，日、美等工业发达国家的模具工业产值已超过机床工业，从1997年开始，我国模具工业产值也超过了机床工业产值。模具是大批量生产同形产品的工具，是工业生产的主要工艺装备。据统计，在家电、玩具等轻工行业，近90％的零件是综筷具生产的；在飞机、汽车、农机和无线电行业，这个比例也超过60％。例如飞机制造业，某型战斗机模具使用量超过三万套，其中主机八千套、发动机二千套、辅机二万套。从产值看，80年代以来，美、日等工业发达国家模具行业的产值已超过机床行业，并又有继续增长的趋势。据国际生产技术协会预测，到2000年，产品尽件粗加工的75%、精加工的50％将由模具完成；金属、塑料、陶瓷、橡胶、建材等工业制品大部分将由模具完成，50％以上的金属板材、80％以上的塑料都特通过模具转化成制品。2、模具的历史发展模具的出现可以追溯到几千年前的陶器和青铜器铸造，但其大规模使用却是随着现代工业的掘起而发展起来的。19世纪，随着军火工业(枪炮的弹壳)、钟表工业、无线电工业的发展，冲模得到广泛使用。二次大战后，随着世界经济的飞速发展，它又成了大量生产家用电器、汽车、电子仪器、照相机、钟表等零件的最佳方式。从世界范围看，当时美国的冲压技术走在前列——许多模具先进技术，如简易模具、高效率模具、高寿命模具和冲压自动化技术，大多起源于美国；而瑞士的精冲、德国的冷挤压技术，苏联对塑性加工的研究也处于世界先进行列。50年代，模具行业工作重点是根据订户的要求，制作能满足产品要求的模具。模具设计多凭经验，参考已有图纸和感性认识，对所设计模具零件的机能缺乏真切了解。从1955年到1965年，是压力加工的探索和开发时代——对模具主要零部件的机能和受力状态进行了数学分桥，并把这些知识不断应用于现场实际，使得冲压技术在各方面有飞跃的发展。其结果是归纳出模具设计原则，并使得压力机械、冲压材料、加工方法、梅具结构、模具材料、模具制造方法、自动化装置等领域面貌一新，并向实用化的方向推进，从而使冲压加工从仪能生产优良产品的第一阶段。进入70年代向高速化、启动化、精密化、安全化发展的第二阶段。在这个过程中不断涌现各种高效率、商寿命、高精度助多功能自动校具。其代表是多达别多个工位的级进模和十几个工位的多工位传递模。在此基础上又发展出既有连续冲压工位又有多滑块成形工位的压力机—弯曲机。在此期间，日本站到了世界最前列——其模具加工精度进入了微米级，模具寿命，合金工具钢制造的模具达到了几千万次，硬质合金钢制造的模具达到了几亿次p每分钟冲压次数，小型压力机通常为200至300次，最高为1200次至1500次。在此期间，为了适应产品更新快、用期短(如汽车改型、玩具翻新等)的需要，各种经济型模具，如锌落合金模具、聚氨酯橡胶模具、钢皮冲模等也得到了很大发展。从70年代中期至今可以说是计算机辅助设计、辅助制造技术不断发展的时代。随着模具加工精度与复杂性不断提高，生产周期不断加快，模具业对设备和人员素质的要求也不断提高。依靠普通加工设备，凭经验和手艺越来越不能满足模具生产的需要。90年代以来，机械技术和电子技术紧密结合，发展了NC机床，如数控线切割机床、数控电火花机床、数控铣床、数控坐标磨床等。而采用电子计算机自动编程、控制的CNC机床提高了数控机床的使用效率和范围。近年来又发展出由一台计算机以分时的方式直接管理和控制一群数控机床的NNC系统。随着计算机技术的发展，计算机也逐步进入模具生产的各个领域，包括设计、制造、管理等。国际生产研究协会预测，到2000年，作为设计和制造之间联系手段的图纸将失去其主要作用。模具自动设计的最根本点是必须确立模具零件标准及设计标准。要摆脱过去以人的思考判断和实际经验为中心所组成的设计方法，就必须把过去的经验和思考方法，进行系列化、数值化、数式化，作为设计准则储存到计算机中。因为模具构成元件也干差万别，要搞出一个能适应各种零件的设计软件几乎不可能。但