模具专业英语毕业课程设计外文文献翻译中英文翻译.docx

模具专业英语毕业课程设计外文文献翻译中英文翻译.docx

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模具专业英语毕业课程设计外文文献翻译中英文翻译

资料来源：

文章名：

Theinjectionmoldingandmachine

书刊名：

《ProfessionalEnglishformould》

作者：

王浩钢曹艳清

出版社：

人民邮电出版社

章节：

Chapter1-3

页码：

P1~P18

文章译名：

模具专业英语

外文原文:

Lesson1Theinjectionmoldingandmachine

1.Theinjectionmolding

Injectionmoldingisprincipallyusedfortheproductionofthethermoplasticparts,althoughsomeprogresshasbeenmadeindevelopingamethodforinjectionmoldingsomethermosettingmaterials.Theproblemofinjectingameltedplasticintoamoldcavityfromareservoirofmeltedmaterialhasbeenextremelydifficulttosolveforthermosettingplasticswhichcureandhardenundersuchconditionswithinafewminutes.Theprincipleofinjectionmoldingisquitesimilartothatofdie-casting.Theprocessconsistsoffeedingaplasticcompoundinpowderedorgranularformfromahopperthroughmeteringandmeltingstagesandtheninjectingitintoamold?

.Afterabriefcoolingperiod,themoldisopenedandthesolidifiedpartejected.Injection-moldingmachinescanbearrangedformanualoperation,automaticsingle-cycleoperation,andfullautomaticoperation.Theadvantageofinjectionmoldingare:

（i）ahighmoldingspeedadaptedformassproductionispossible;（ii）thereisawidechoiceofthermoplasticmaterialsProvidingavarietyofusefulpropertics;（iii）itispossibletomoldthreads,undercuts,sideholes,andlargethinsections.

2.Theinjection-moldingmachine

Severalmethodsareusedtoforceorinjectthemeltedplasticintothemold.Themostcommonlyusedsysteminthelargermachinesisthein-linereciprocatingscrew.Thescrewactsasacombinationinjectionandplasticizingunit.Astheplasticisfedtotherotatingscrew,itpassesthroughthreezonesasshown:

feed,compression,andmetering.Afterthefeedzone,thescrew-fightdepthisgraduallyreduced,forcingtheplastictocompress.Theworkisconvertedtoheatbyshearingtheplastic,makingitasemifluidmass.Inthemeteringzone,additionalheatisappliedbyconductionfromthebarrelsurface.Asthechamberinfrontofthescrewbecomesfilled,itforcesthescrewback,trippingalimitswitchthatactivatesahydrauliccylinderthatforcesthescrewforwardandinjectsthefluidplasticintotheclosedmold.Anantiflowbackvalvepreventsplasticunderpressurefromescapingbackintothescrewflights.

Theclampingforcethatamachineiscapableofexertingispartofthesizedesignationandismeasuredintons.Arule-of-thumbcanbeusedtodeterminethetonnagerequiredforaparticularjob.Itisbasedontwotonsofclampforcepersquareinchofprojectedarea.Iftheflowpatterisdifficultandthepartsarethin,thismayhavetogotathreeorfourtons.

Manyreciprocating-screwmachinesarecapableofhandingthermosettingplasticmaterials.Previouslythesematerialswerehandledbycompressionortransfermolding.Thermosettingmaterialscureorpolymerizeinthemoldandareejectedhotintherangeof375C~410C.Thermoplasticparts

mustbeallowedtocoolinthemoldinordertoremovethemwithoutdistortion.Thusthermosettingcyclescanbefaster.Ofcoursethemoldmustbeheatedratherthanchilled,aswiththermoplastics.

Readingmaterial

Acompetentmoulddesignermusthaveathoroughknowledgeoftheprinciplesofmouldmakingasthedesignofthevariouspartsofthemoulddependsonthetechniqueadoptedforitsmanufacture.

Thischapterisincludedprimarilyforthebeginnerwhodoesnothaveabackgroundknowledgeof

thevariousmachiningandothermouldmakingtechniques.Tocoverthetopicofmouldmakingthoroughlywouldrequireacompanionworkequalinsizetothismonographandthereforethisintroductiontothesubjectmust,ofnecessity,besuperfcial.However,wehopethatveryfactthatitisincludedinamonographondesign,willemphasizetheimportanceofmouldmakingasasubjectandwillalsoencouragethebeginnertoafurtherandmorecompletestudyinthisfield.

Themajorityofmouldsaremanufacturedbytheuseofconventionalmachinetoolsfoundinmostmodemtoolrooms.Fromthemanufacturingviewpointweclassifythemouldintotwoparts（i）thecavityandcore,and（ii）theremainderofthemould.Thelattetpartiscommonlyreferredtoasbolsterwork.

Theworkonthecavityandcoreisbyfarthemostimportantasitisfromthesemembersthattheplasticsmouldingtakesitsform.

Theworkonthecavityandcorecanfurtherbeclassifieddependinguponwhethertheformisofasimpleoracomplexnature.Forexample,thecavityandcoreforacircularorrectangularbox-typemouldingisfarsimplertomakethanacavityandcoretoproduceatelephonehandsetmoulding.Themouldpartsforthesimpleformareproducedonsuchmachinetoolsasthelatheandthemillingmachine,whereasthemorecomplexformrequirestheuseofsomekindofcopyingmachine.

Thebolsterworkisnotascriticalasthemanufactureofthecavityandcoreformsbutnevertheless,accuracyinthemanufactureofthevariouspartsnecessarytoensurethatthemoldcanbeassembledbythefitterwithoutanundueamountofbench-work,

Now,whilethebolsterworkisalwaysproducedonconventionalmachinetool,thecavityandcore,particularlytheformer,canbeproducedbyoneofanumberofothertechniques.Theseincludeinvestmentcasting,electro-deposition,coldhobbing,pressurecastingandsparkmachining.

1.Machinetools

Thepurposeofanymachinetoolistoremovemetal.Eachmachinetoolremovesmetalinadifferentway.Forexample,inonetype（thelathe）metalisremovedbyasinglepointtoolastheworkisrotated,whereasinanothertype（themillingmachine）acutterisrotatedandmetalisremovedastheworkisprogressedbeneathit.

Whichmachinetoolistobeusedforaparticularjobdependstoalargeextentuponthetypeofmachiningrequired.Thereis,however,acertainamountofoverlappingandsomemachinetoolscanbeutilizedforseveraldifferentoperations.

Themachinetoolswhichwillbefoundinthemoderntoolroomareasfollows:

（i）Lathesforturning,boringandscrewcutting,etc.

（ii）Cylindricalgrindingmachinesfortheproductionofprecisioncylindricalsurfaces.

（iii）Shapingandplaningmachinesforthereductionofsteelblocksandplatestotherequiredthicknessandfor"squaringup"theseplates

（iv）Surfacegrindingmachinesfortheproductionofprecisionflatsurfaces.

（v）Millingmachinesfortherapidremovalofmetal,formachiningslots,recesses,boringholesmachiningsplines,etc.

（vi）Tracer-controlledmillingmachinesforaccuratereproductionofcomplexcavityandcoreforms.

Inadditiontotheabovelistofmajormachinetoolsthereis,ofcourse,ancillaryequipmentwithoutwhichnotoolroomwouldbecomplete.Thisincludespowersaws,drillingmachines,toolpostgrinders,hardeningandpolishingfacilities,etc.

2.Castings

Themanufactureofcavitiesandcoresinsteelbytheconventionalcastingmethodusingsandmouldsisnotsatisfactoryowingtothepoorfinishobtainedandtotheporositywhichoccurson,orjustbelowthesurfaceofthecasting.Theexpenditureinvolvedinplugging,machiningandfinishingtheseconventionalcastingsmakesthismethodofmouldmakinguneconomic.

TheShawinvestmentcastingprocessdocsnot,however,sharethedisadvantagesassociatedwithsandcastingandisthereforeapplicabletothemanufactureofcavitiesandcores.Theprocessiscarriedoutbyspecialistsandthemouldmakersuppliesthecompanywithapatternoftherequiredmouldpart.Asthefinalcastingwillbeanaccuratereproductionofthepatternsupplied,thismustbemanufacturedtoclosetolerancesandhaveagoodsurfacefinish.Toallowforthecontractionofthesteeloncoolingthepatternismadeapproximately0.020mm/mm（in/in）oversize.

3.Electro-deposition

Electro-depositionisanelectrochemicalprocessusedtoreproduceaccuratelyacavityorcoreformfromagivenpattern.Thepatterncanbemadeinaneasilyworkedmaterialandisthereverseformtothatrequired.Thatis,amalepatternisrequiredforacavityandafemalepatternforacore.Normallyitismucheasiertomachineamalepatternthanthereversecavityformanditisforthisreasonthatmostapplicationsforthistechniqueareforintricatecavitywork.

4.Coldhobbing

Coldhobbingisaprocessinwhichahardenedsteelmasterhobisforcedintoasoftsteelblankundercondiderablepressure.

Hobbingisusedfortheproductionofcavitieswhichbyvirtueoftheirshapewouldbedifficulttodie-sinkonconventionalmachinetools.

5.Pressurecasting

Beryllium-copperisamaterialwhichisincreasinglybeingusedinmouldconstructionbecauseitpossessesseveraldesirablecharacteristics.Inparticularithasahighthermalconductivitycombinedwithareasonablehardness（BrinellHardnessNumberofabout250）,whichmakesitsuitableforcertaintypesofcavityandcore,andforothermouldparts,suchashotrunnerunitsecondarynozzles.

Itshighthermalconductivitymeansthatwhenberyllium-copperisusedforacavityoracore,theheatfromthemeltwillbetransferredawayfromtheimpressionfasterthanifacorrespondingsteelcavityandcoreareused,andthisoftenresultsinashortermouldingcycle.

Berylium-coppercanbemachined,inwhichcasetheconventionalmachinetoolsareused,anditcanbecold-hobbed,hot-hobbedorpressure-cast,Thelasttechniqueofferscertainadvantagesoverthehobbingmethods,inthatcoldorhothobbingofberyllium-coppertendstoworkhardenthematerialwhichresultsinthedevelopmentofstressconcentrations.

Pressurecasting（orliquidhobbing）isusedmainlyfortheproductionofcavitiesbutifcanbeused,whereapplicable,fortheproductionofthecoresaswell,Asthetermssuggest,itisbasicallyaprocesswhichcombinesthecastingandho