沖壓模具類中英文翻譯、外文文獻翻譯、外文翻譯

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.

汽車開發(fā)周期從40個月縮短到4個月。1、模具在工業(yè)發(fā)展中的地位采用模具生產(chǎn)零部件，具有生產(chǎn)效率高、質(zhì)量好、成本低、節(jié)約能源和原材料等一系列優(yōu)點，用模具生產(chǎn)制件所具備的高精度、高復雜程度、高一致性、高生產(chǎn)率和低消耗，是其他加工制造方法所不能比擬的。已成為當代工業(yè)生產(chǎn)的重要手段和工藝發(fā)展方向?，F(xiàn)代經(jīng)濟的基礎工業(yè)?，F(xiàn)代工業(yè)品的發(fā)展和技術水平的提高，很大程度上取決于模具工業(yè)的發(fā)展水平，因此模具工業(yè)對國民經(jīng)濟和社會發(fā)展將起越來越大的作用。1989年3月國務院頒布的《關于當前產(chǎn)業(yè)政策要點的決定》中，把模具列為機械工業(yè)技術改造序列的第一位、生產(chǎn)和基本建設序列的第二位(僅次于大型發(fā)電設備及相應的輸變電設備)，確立模具工業(yè)在國民經(jīng)濟中的重要地位。1997年以來，又相繼把模具及其加工技術和設備列入了《當前國家重點鼓勵發(fā)展的產(chǎn)業(yè)、產(chǎn)品和技術目錄》和《鼓勵外商投資產(chǎn)業(yè)目錄》。經(jīng)國務院批準，從1997年到2000年，對80多家國有專業(yè)模具廠實行增值稅返還70%的優(yōu)惠政策，以扶植模具工業(yè)的發(fā)展。所有這些，都充分體現(xiàn)了國務院和國家有關部門對發(fā)展模具工業(yè)的重視和支持。目前全世界模具年產(chǎn)值約為600億美元，日、美等工業(yè)發(fā)達國家的模具工業(yè)產(chǎn)值已超過機床工業(yè)，從1997年開始，我國模具工業(yè)產(chǎn)值也超過了機床工業(yè)產(chǎn)值。模具是大批量生產(chǎn)同形產(chǎn)品的工具，是工業(yè)生產(chǎn)的主要工藝裝備。據(jù)統(tǒng)計，在家電、玩具等輕工行業(yè)，近90％的零件是綜筷具生產(chǎn)的；在飛機、汽車、農(nóng)機和無線電行業(yè)，這個比例也超過60％。例如飛機制造業(yè)，某型戰(zhàn)斗機模具使用量超過三萬套，其中主機八千套、發(fā)動機二千套、輔機二萬套。從產(chǎn)值看，80年代以來，美、日等工業(yè)發(fā)達國家模具行業(yè)的產(chǎn)值已超過機床行業(yè)，并又有繼續(xù)增長的趨勢。據(jù)國際生產(chǎn)技術協(xié)會預測，到2000年，產(chǎn)品盡件粗加工的75%、精加工的50％將由模具完成；金屬、塑料、陶瓷、橡膠、建材等工業(yè)制品大部分將由模具完成，50％以上的金屬板材、80％以上的塑料都特通過模具轉化成制品。2、模具的歷史發(fā)展模具的出現(xiàn)可以追溯到幾千年前的陶器和青銅器鑄造，但其大規(guī)模使用卻是隨著現(xiàn)代工業(yè)的掘起而發(fā)展起來的。19世紀，隨著軍火工業(yè)(槍炮的彈殼)、鐘表工業(yè)、無線電工業(yè)的發(fā)展，沖模得到廣泛使用。二次大戰(zhàn)后，隨著世界經(jīng)濟的飛速發(fā)展，它又成了大量生產(chǎn)家用電器、汽車、電子儀器、照相機、鐘表等零件的最佳方式。從世界范圍看，當時美國的沖壓技術走在前列——許多模具先進技術，如簡易模具、高效率模具、高壽命模具和沖壓自動化技術，大多起源于美國；而瑞士的精沖、德國的冷擠壓技術，蘇聯(lián)對塑性加工的研究也處于世界先進行列。50年代，模具行業(yè)工作重點是根據(jù)訂戶的要求，制作能滿足產(chǎn)品要求的模具。模具設計多憑經(jīng)驗，參考已有圖紙和感性認識，對所設計模具零件的機能缺乏真切了解。從1955年到1965年，是壓力加工的探索和開發(fā)時代——對模具主要零部件的機能和受力狀態(tài)進行了數(shù)學分橋，并把這些知識不斷應用于現(xiàn)場實際，使得沖壓技術在各方面有飛躍的發(fā)展。其結果是歸納出模具設計原則，并使得壓力機械、沖壓材料、加工方法、梅具結構、模具材料、模具制造方法、自動化裝置等領域面貌一新，并向?qū)嵱没姆较蛲七M，從而使沖壓加工從儀能生產(chǎn)優(yōu)良產(chǎn)品的第一階段。進入70年代向高速化、啟動化、精密化、安全化發(fā)展的第二階段。在這個過程中不斷涌現(xiàn)各種高效率、商壽命、高精度助多功能自動校具。其代表是多達別多個工位的級進模和十幾個工位的多工位傳遞模。在此基礎上又發(fā)展出既有連續(xù)沖壓工位又有多滑塊成形工位的壓力機—彎曲機。在此期間，日本站到了世界最前列——其模具加工精度進入了微米級，模具壽命，合金工具鋼制造的模具達到了幾千萬次，硬質(zhì)合金鋼制造的模具達到了幾億次p每分鐘沖壓次數(shù)，小型壓力機通常為200至300次，最高為1200次至1500次。在此期間，為了適應產(chǎn)品更新快、用期短(如汽車改型、玩具翻新等)的需要，各種經(jīng)濟型模具，如鋅落合金模具、聚氨酯橡膠模具、鋼皮沖模等也得到了很大發(fā)展。從70年代中期至今可以說是計算機輔助設計、輔助制造技術不斷發(fā)展的時代。隨著模具加工精度與復雜性不斷提高，生產(chǎn)周期不斷加快，模具業(yè)對設備和人員素質(zhì)的要求也不斷提高。依靠普通加工設備，憑經(jīng)驗和手藝越來越不能滿足模具生產(chǎn)的需要。90年代以來，機械技術和電子技術緊密結合，發(fā)展了NC機床，如數(shù)控線切割機床、數(shù)控電火花機床、數(shù)控銑床、數(shù)控坐標磨床等。而采用電子計算機自動編程、控制的CNC機床提高了數(shù)控機床的使用效率和范圍。近年來又發(fā)展出由一臺計算機以分時的方式直接管理和控制一群數(shù)控機床的NNC系統(tǒng)。隨著計算機技術的發(fā)展，計算機也逐步進入模具生產(chǎn)的各個領域，包括設計、制造、管理等。國際生產(chǎn)研究協(xié)會預測，到2000年，作為設計和制造之間聯(lián)系手段的圖紙將失去其主要作用。模具自動設計的最根本點是必須確立模具零件標準及設計標準。要擺脫過去以人的思考判斷和實際經(jīng)驗為中心所組成的設計方法，就必須把過去的經(jīng)驗和思考方法，進行系列化、數(shù)值化、數(shù)式化，作為設計準則儲存到計算機中。因為模具構成元件也干差萬別，要搞出一個能適應各種零件的設計軟件幾乎不可能。但