外文翻譯-- 注塑模具.doc

InjectionMoldsA.BasicmolddesignAninjectionmoldconsistsofatleasttwohalvesthatarefastenedtothetwoplatensoftheinjectionmoldingmachinesothattheycanbeopenedandclosed.Intheclosedposition,theproduct-formingsurfacesofthetwomoldhalvesdefinethemoldcavityintowhichtheplasticmeltisinjectedviatherunnersystemandthegate.Coolingprovisionsinthemoldprovideforcoolingandsolidificationofthemoldedproductsothatitcanbesubsequentlyejected.B.TypesofEjectionForproductejectiontooccur,themoldmustopen.Theshapesofthemoldedproductdetermineswhetheritcanbeejectedsimplybyopeningthetwomoldhalvesorwhetherundercutsmustbepresent.Thedesignofamoldisdictatedprimarilybytheshapeoftheproducttobemoldedandtheprovisionsnecessaryforproductejection.Injection-moldedproductscanbeclassifiedas:1Productswithoutundercuts(e.g.,plaques,strips,half-shells,cups).2Productswithexternalundercutsorlateralopenings(e.g.,spoolsandbobbins,beveragecrates,threadedbolts).3Productswithinternalundercuts(e.g.,threadedclosures,housings).4Productswithexternalandinternalundercuts(e.g.,bumperfascias,electricalandautomotiveinstrumenthousings,cameras,etc.).C.DesignRulesTherearemanyrulesfordesigningmolds.Theserulesandstandardpracticesarebasedonlogic,pastexperience,convenience,andeconomy.Fordesigning,moldmaking,andmolding,itisusuallyofadvantagetofollowtherules.Butoccasionally,itmayworkoutbetterifaruleisignoredandanalternativewayisselected.Inthistext,themostcommonrulesarenoted,butthedesignerwilllearnonlyfromexperiencewhichwaytogo.Thedesignermusteverbeopentomewideasandmethods,tonewmoldingandmoldmaterialsthatmayaffecttheserules.D.TheBasicMold1.MoldCavitySpaceThemoldcavityspaceisashapeinsidethemold,”excavated”(bymachiningthemoldmaterial)insuchamannerthatwhenthemoldingmaterial(inourcase,theplastic)isforcedintothisspaceitwilltakeontheshapeofthecavityspaceand,therefore,thedesiredproductTheprincipleofamoldisalmostasoldashumancivilization.Moldshavebeenusedtomaketools,weapons,bells,statues,andhouseholdarticles,bypouringliquidmetals(iron,bronze)intosandforms.suchmolds,whicharestillusedtodayinfoundries,canbeusedonlyoncebecausethemoldisdestroyedtoreleasetheproductafterithassolidified.Today,wearelookingforpermanentmoldsthatcanbeusedoverandover.Nowmoldsaremadefromstrong,durablematerials,suchassteel,orfromsofteraluminumormetalalloysandevenfromcertainplasticswherealongmoldlifeisnotrequiredbecausetheplannedproductionissmall.Ininjectionmoldingthe(hot)plasticisinjectedintothecavityspacewithhighpressure,sothemoldmustbestrongenoughtoresisttheinjectionpressurewithoutdeforming.2.NumberofCavitiesManymolds,particularlymoldsforlargerproducts,arebuiltforonly1cavityspace(asingle-cavitymold),butmanymolds,especiallylargeproductionmolds,arebuiltwithormorecavities.Thereasonforthisispurelyeconomical.Ittakesonlylittlemoretimetoinjectseveralcavitiesthantoinjectone.Forexample,a4-cavitymoldrequiresonly(approximately)one-fourthofthemachinetimeofasingle-cavitymold.Conversely,theproductionincreasesinproportiontothenumberofcavities.Amoldwithmorecavitiesismoreexpensivetobuildthanasingle-cavitymold,but(asinourexample)notnecessarily4timesasmuchasasingle-cavitymold.Butitmayalsorequirealargermachinewithlargerplatenareaandmoreclampingcapacity,andbecauseitwilluse(inthisexample)4timestheamountofplastic,itmayneedalargerinjectionunit,sothemachinehourcostwillbehigherthanforamachinelargerenoughforthesmallermold.Today,mostmulticavitymoldsarebuiltwithapreferrednumberofcavities:2,4,6,8,12,16,24,32,48,64,96,128.Thesenumbersareselectedbecausethecavitiescanbeeasilyarrangedinarectangularpattern,whichiseasierfordesigninganddimensioning,ormanufacturing,andforsymmetryaroundthecenterofthemachine,whichishighlydesirabletoensureequalclampingforceforeachcavity.Asmallernumberofcavitiescanalsobelaidoutinacircularpattern,evenwithoddnumbersofcavities,suchas3,5,7,9.Itisalsopossibletomakecavitylayoutsforanynumberofcavities,providedsuchrulesassymmetryoftheprojectedareasaroundthemachinecenterlineareobserved.3.CavityShapeandShrinkageTheshapeofthecavityisessentiallythe”negative”oftheshapeofthedesiredproduct,withdimensionalallowancesaddedtoallowforshrinkingoftheplastic.Theshapeofthecavityisusuallycreatedwithchip-removingmachinetolls,orwithelectricdischargemachining(EDM),withchemicaletching,orbyanynewmethodthatmaybeavailabletoremovemetalorbuilditup,suchasgalvanicprocesses.Itmayalsobecreatedbycasting(andthenmachining)certainmetals(usuallycopperorzincalloys)inplastermoldscreatedfrommodelsoftheproducttobemade,orbycasting(andthenmachining)somesuitablehardplastics(e.g.,epoxyresins).Thecavityshapecanbeeithercutdirectlyintothemoldplatesorformedbyputtinginsertsintotheplates.E.CavityandCoreByconvention,thehollow(concave)portionofthecavityspaceiscalledthecavity.Thematching,oftenraised(orconvex)portionofthecavityspaceiscalledthecore.Mostplasticproductsarecup-shaped.Thisdoesnotmeanthattheylooklikeacup,buttheydohaveaninsideandanoutside.Theoutsideoftheproductisformedbythecavity,theinsidebythecore.Thealternativetothecupshapeistheflatshape.Inthiscase,thereisnospecificconvexportion,andsometimes,thecorelookslikeamirrorimageofthecavity.Typicalexamplesforthisareplasticknives,gamechips,orrounddiskssuchasrecords.Whiletheseitemsaresimpleinappearance,theyoftenpresentseriousmoldingproblemsforejectionoftheproduct.Usually,thecavitiesareplacedinthemoldhalfthatismountedontheinjectionside,whilethecoresareplacedinthemovinghalfofthemold.Thereasonforthisisthatallinjectionmoldingmachinesprovideanejectionmechanismonthemovingplatenandtheproductstendtoshrinkontoandclingtothecore,fromwheretheyarethenejected.Mostinjectionmoldingmachinesdonotprovideejectionmechanismsontheinjection(“hot”)side.注：該文選自張曉黎李海梅主編。塑料加工和模具專業(yè)英語化學工業(yè)出版社，2004注塑模具A基本模具設(shè)計一個注塑模具至少包括兩半，這些固定在兩個盤的注塑機，以便他們能夠開啟和關(guān)閉。在關(guān)閉位置，產(chǎn)品形成表面兩個半確定模具型腔將其注入塑料熔體通過熱流道系統(tǒng)和門。冷卻規(guī)定提供模具冷卻和凝固的成型產(chǎn)品，以便能夠隨后順利流出.B注塑的類型產(chǎn)品注射發(fā)生時，模具必須打開。制品的形狀決定了它是能夠被直接開模取出還是必須考慮凹孔的影響。模具的設(shè)計是決定模具的形狀主要是由該產(chǎn)品將成型的規(guī)定和必要的產(chǎn)品注射。注塑產(chǎn)品可分為：1Products不削弱（如斑塊，帶，半彈，杯）。2Products與外部削弱或側(cè)開口的（例如，線軸和筒子，飲料箱，螺紋螺栓）。3Products內(nèi)部破壞（例如，線程關(guān)閉，外殼）。4Products與外部和內(nèi)部破壞（例如，保險杠fascias，電器和汽車儀表外殼，照相機等）。C.設(shè)計規(guī)則設(shè)計模具有許多規(guī)則。這些規(guī)則和標準的做法是根據(jù)邏輯，過去的經(jīng)驗，方便，經(jīng)濟的角度考慮的.對于設(shè)計，模具制造，成型，按照這些規(guī)則通常是有優(yōu)勢的.但是有些時候，它可能更好的工作如果忽視了這種方法而選擇可另一種設(shè)計原則.在這段文章中，最常見的規(guī)則被選擇，但設(shè)計者將會根據(jù)經(jīng)驗去確定應該選擇的規(guī)則，同時設(shè)計者必須想出新的方法和建議去設(shè)計新的模具和模具材料，這些可能會影響到這些規(guī)則。D.基本模具1.模具型腔空間在模具型腔形狀空間內(nèi)的模具，“挖掘”（由機械加工的模具材料）以這種方式，當成型材料（在目前情況下，塑料）是被迫進入這一領(lǐng)域?qū)⒉扇〉男螤钋坏目臻g，因此，得到理想的產(chǎn)品.模具的這一原理幾乎和人類文明有一樣漫長的歷史.模具已被用來制造工具，武器，鐘聲，雕像，和家居用品，通過澆注液態(tài)金屬（鐵，銅）到沙形式。這種模具，這是沿用至今的鑄造廠，但是只能使用一次，因為為了在產(chǎn)品固化后將其取出而不得不將其毀壞.今天，我們正在尋找永久鑄模，可重復使用?，F(xiàn)在的模具都是用堅固的，可回收利用的材料做成的，比如鋼鐵，軟鋁或金屬合金。某些塑料模具在長期的生活并不需要，因為計劃生產(chǎn)量本來就少。在注塑成型的（熱）塑料注入腔空間用高壓，因此，模具必須強大到足以抵制注射壓力不變形。2.型腔的數(shù)目許多模具，特別是較大的模具產(chǎn)品，是專為只有1腔空間（單腔模具），但許多鑄模，尤其是大型的生產(chǎn)模具，建有或更多的型腔，這個原因完全是從經(jīng)濟的角度考慮的。It這樣就只需要投入稍微多一點的時間去注入幾個型腔而不是僅僅的一個。例如，一個4腔模具只需要（約）的四分之一的時間注入一個單腔模具。總之，產(chǎn)量的增加完全可以根據(jù)型腔數(shù)目的增加而增加。當然也個擁有多個型腔的模具要遠比只有一個型腔的模具昂貴的多，但（因為在我們的例子）不一定就比單腔模具有四倍的產(chǎn)量。而且可能需要有更大機板面積的機器，更好的鉗位能力，因為它會使用（在這個例子中）4倍的塑料，它可能需要更大的注射單元，使機器的成本比小的模具的成本更高。今天，大部分多模腔模具都用一定的首選號碼標注