流道基礎中英文對照外文翻譯文獻

中英文對照外文翻譯文獻流道基礎中英文對照外文翻譯文獻(文檔含英文原文和中文翻譯)原文：1.ThebasicTherunnerisachannelmachinedintothemodplatetoconnectthespruewiththeentrance(gate)totheimpression.Inthebasictwo-platemodtherunnerispositionedonthesurfacewhileonthemorecomplexdesignstherunnermaybepositionedbelowthepartingsurfaceThewalloftherunnerchannelmustbesmoothtopreventanyrestrictiontoflow.Also,astherunnerhastoberemovedwiththemolding,theremustbenomachinemarksleft,whichwouldtendtoretaintherunnerinthemodplate.Toensurethatthesepointsaremet,it'sdesirableforthemoddesignertospecifythattherunner(channel)ispolished'inlineofdraw'.Therearesomeotherconsiderationsforthedesignertobearinmind:(i)theshapeofthecrosssectionoftherunner,(ii)thesizeoftherunner.Runnercross-sectionshapeThecross-sectionalshapeoftherunnerusedinamodisusuallyoneoffourforms(Figure4.2):fullyround(a),trapezoidal(b),modifiedtrapezoidal(c)andhexagonal(d).Thereasonwhytheseparticularformsareusedinpreferencetoothersareoutlinedbelow.Thecriterionofefficientrunnerdesignisthattherunnershouldprovideamaximumcross-sectionalareafromthestandpointofpressuretransferandminimumcross-sectionalareatoperipherywill,therefore,giveadirectindicationoftheefficiencyoftherunnerdesign;therunnersectionaregiverinFigure4.3.Ascanbeseen,thevarioustypesofstandpoint;whereastheratiosexhibitedbythesemicircularandrectangulartypesmaketheirusegenerallyundesirable.Unfortunately,thesquarerunnerisnotverysatisfactoryeither,butforanotherreason:itisdifficulttoeject.Inpractice,becauseofthis,anangleof10°isincorporatedontherunnerwell,thusmodifyingthesquaretothetrapezoidalsection.Thevolumeofthetrapezoidalrunnerisapproximately25%greaterthanthatofaroundrunnerwithcorrespondingdimensions(W=D,Figure4.2).Toreducethisdifferenceandstillmaintaincorrespondingdimensions,amodifiedtrapezoidalformhasbeendeveloped(Figure4.2c)inwhichthevolumeisonly14%greater(approximately)thanitsroundcounterpart.Thehexagonalrunnerisbasicallyadoubletrapezoidalrunner,wherethecross-sectionalareaofthisrunnertypeisabout82%ofthatofthecorrespondingroundrunner.Naturallyifsimilarcross-sectionalareasarerequired,thenthevalueforD(Figure4.2c)mustbeincreasedaccordthehexagonalrunnercomparedwithmatchingthetwohalvesofaroundrunner.Thispointappliesparticularlytorunnerswhichareless3mm(1/8in)inwidth.Astheplasticmeltprogressesthroughtherunnerandmodsystemthemeltadjacenttothecoldmodsurfacewillrapidlydecreaseintemperatureandsolidify.Thematerialwhichfollowswillpassthroughthecenterofthissolidifiedmaterialand,becauseofthelowthermalconductivitythatmostthermoplasticsposses,thesolidifiedmaterialactsasaninsulationandmaintainsthetemperatureofthecentralmeltflowregion.Ideally,thegateshouldthereforebepositionedinlinewiththecenteroftherunnertoreceivethematerialfromthecentralflowstream.Thisconditionmaybeachievedwiththefullyroundrunner(Figure4.4a),andalsowiththehexagonalrunnerThebasictrapezoidaldesigns(Figure4.2bandc)arenotassatisfactoryinthisrespectsincethegatecannotnormallybepositionedinlinewiththecentralflowstream.Themainobjectiontothefullyroundrunneristhatthisrunnerisformedfromtwosemicircularchannelsmachinedoneineachofthemodplates.Itisessentialthatthesechannelsareaccuratelymatchedtopreventanundesirableandinefficientrunnersystembeingdeveloped.Asimilarargumentappliestothehexagonalrunnersystem.Thefactthatthesechannelsmustbeaccuratelymatchedmeansthatthemodcostforamodcontainingroundorhexagonalrunnerwillbegreaterthanforonecontainingtrapezoidalrunners.Thechoiceofrunnersectionisalsoinfluencedbythequestionwhetherpositiveejectionoftherunnersystemispossible.Consider,forinstance,thecaseofatwo-platemodinwhichacircularrunnerhasbeenmachinedfrombothpartingsurface.Inthiscase,asthemodopens,therunnerispulledfromitschannelinonemodhalfanditisthenejectedfromtheothermodhalfeitherdirectly,byejectorpins,orbyrelyingonitsattachmenttothemoldingsbythegates(Figure4.5).Formulti-platemolds,however,positiveejectionoftherunnersystemisnotpracticable.Herethebasictrapezoidal-typerunnerisalwaysspecified,therunnerchannelbeingmachinedintotheinjectionhalffromwhichitispulledasthemodopens.Inthiswaytherunnerisfreetofallundergravitybetweenmodplates.Ifacircularrunnerhadbeenpecified,however,therunnersystemcouldwelladheretoitschannelandmakeitsremovaldifficult(Figure4.6).Summingupthepointsconcerningcross-sectionalshape,wecansaythatforsimpletwo-platemoldswhichhaveaflatpartingsurfacethefullyroundrunnerorhexagonalrunneristobeprefaced,theincreasedmodcostbeingrelativelysmall.Formoldswhichhavecomplexpartingsurface,whereitwouldbedifficulttomatchaccuratelythesemicircularchannelsoftheroundrunneror,formulti-platemolds,thetrapezoidalormodifiedtrapezoidalsectionshouldbeused.2.RunnersizeWhendecidingthesizeoftherunnerthedesignermustconsiderthefollowingfactors:(i)thewallsectionandvolumeofthemolding(ii)thedistanceoftheimpressionfromthemainrunnerorsprue,(iii)runnercoolingconsiderations,(iv)therangeofmouldmaker'scuttersavailableand(v)theplasticsmaterialtobeused.(i)Thecross-sectionalareaoftherunnermustbesufficienttopermitthefreezesandforpackingpressuretobeappliedforshrinkagecompensationifrequired,Becauseofthis,runnersbelow2mm(3/32in)diameterareseldomusedandeventhisdiameterisnormallylimitedtobranchrunnersunder25mm(1in)inlength.(ii)Thefurthertheplasticmelthastotravelalonetherunnerthegreateristheresistancetoflow.Hencethedistancetheimpressionisfromthespruehasadirectbearingonthechoiceofcross-sectionalsizeoftherunner.Forexample,whereasa5mm(3/16in)(iii)Thecross-sectionalareaoftherunnershouldnotbesuchthatitcontrolstheinjectioncycle,althoughthisissometimesunavoidableforverylightmoldingsThelargerhecross-sec~tionareaoftherunnerthegreateristhebulkofmaterialitcontainsandthelongertheperiodittakestocoolsufficientlytoenablethemodtobeopenedandthemoldingsandrunnerejected.Forthisreasonitisundesirabletomaketherunnerlargerthan10mm(]in)diameterformostmaterials.However,therigidPVCsandtheacrylicsareexceptionsduetotheirhighviscosityanddiametersupto13mm(1/2in)areused.(iv)Thesizechosenfortherunnershouldbeinarangeconsistentwiththemouldmakers'snothavingtocarryinstockamultitudeofdifferent!sizesofcutters.Inpracticethefollowingarethemorecommonsizes:2-13mminImmstepsinthemetricrangeand~-?inWith~instepsintheimperialunitrange.Thefollowingempiricalformulaissuggestedasaguideofthesizeoftherunnerorbranchrunnerformoldingsweighingupto200g(Ig(7oz),andwithwallsectionslessthan3mm(0.125in).FortherigidPVCsandtheacrylics,increasethecalculateddiameterby25%.Theformulaisusedinconjunctionwiththenotesgivenpreviously.

(i)Therunnershouldnotbebelow2mm(3/32in)diameter,norabove10mm(3/8in)diameter(or13mm(1/2in)diameterwhereapplicable).

(ii)ThecalculatedsizeshouldbeincreasedtothenextsuitablecuttersizeFigure4.7showsaplotofdiameterversuslengthofrunnerforvariousweightsofmolding,adoptingthemetricsystemofdimensioning.Figure4.8showsacorrespondingplotusingtheImperialdimensioningsystem.Forexample,a120g(4oz)moldinginpolyethylenebeingfedbya50mm(2in)longrunnerwillrequireadiameterof7mm(5/16in).Theoreticallythecross-sectionalareaofthemainrunnershouldbeequalto,orinexcessof,thecombinedcross-sectionalareasofthebranchrunnersthatitisfeeding.Thisrelationshipis,however,ignoredwhenthemaximumsuggesteddiameterisreachedThemainobjectiontothefullyroundrunneristhatthisrunnerisformedfromtwosemicircularchannelsmachinedoneineachofthemodplates.Itisessentialthatthesechannelsareaccuratelymatchedtopreventanundesirableandinefficientrunnersystembeingdeveloped.Asimilarargumentappliestothehexagonalrunnersystem.Thefactthatthesechannelsmustbeaccuratelymatchedmeansthatthemodcostforamodcontainingroundorhexagonalrunnerwillbegreaterthanforonecontainingtrapezoidalrunners.Thechoiceofrunnersectionisalsoinfluencedbythequestionwhetherpositiveejectionoftherunnersystemispossible.Consider,forinstance,thecaseofatwo-platemodinwhichacircularrunnerhasbeenmachinedfrombothpartingsurface.Inthiscase,asthemodopens,therunnerispulledfromitschannelinonemodhalfanditisthenejectedfromtheothermodhalfeitherdirectly,byejectorpins,orbyrelyingonitsattachmenttothemoldingsbythegates(Figure4.5).Formulti-platemolds,however,positiveejectionoftherunnersystemisnotpracticable.Herethebasictrapezoidal-typerunnerisalwaysspecified,therunnerchannelbeingmachinedintotheinjectionhalffromwhichitispulledasthemodopens.Inthiswaytherunnerisfreetofallundergravitybetweenmodplates.Ifacircularrunnerhadbeenspecified,however,therunnersystemcouldwelladheretoitschannelandmakeitsremovaldifficult3.RunnerlayoutThelayoutoftherunnersystemwilldependuponthefollowingfactors:(i)thenumberofimpressions,(ii)theshapeofthecomponents,(iii)thetypeofmod(i.e.,two-plateormulti-platemold),(iv)thetypeofgate.Therearetwomainconsiderationswhendesigningarunnerlayout.

Therunnerlengthshouldalwaysbekepttoaminimumtoreducepressurelosses,andtherunnersystemshouldbebalanced.(i)Thecross-sectionalareaoftherunnermustbesufficienttopermitthefreezesandforpackingpressuretobeappliedforshrinkagecompensationifrequired,Becauseofthis,runnersbelow2mm(3/32in)diameterareseldomusedandeventhisdiameterisnormallylimitedtobranchrunnersunder25mm(1in)inlength.(Runnerbalancingmeansthatthedistancetheplasticmaterialtravelsfromthesprue1othegateshouldbethesameforeachmoldingThissystemensuresthatalltheimpressionswillfilluniformlyandwithoutinterruptionprovidingthegatelandsandthegateareasareidentical,Figure4.9showsexample~ofmoldsallbasedonthebalancedrunnerprinciple.譯文：流道基礎流道是在模板上加工出的連接主流道和進入（澆口）型腔的一條溝槽。在兩板式基本模具中，流道設置在分型面上而在較復雜的設計中流道也許設置在分型面的下面。流道的壁必須光滑，防止料流受到阻礙。另外，由于流道廢料必須和塑件一起取出，所以流道壁上必須不留下任何加工痕跡，避免流道廢料滯留在模板上。為了確保這些要點得到滿足，要求模具設計者在圖紙中注明這條流道需要沿取出方向拋光。另外還有一些要求設計者用心考慮的：（1）流道的橫截面形狀，（2）流道的尺寸和（3）流道的布置。模具中用到的流道橫截面形狀，通常是四種形式之一（圖4.2）：整圓（a），梯形（b）,U型（c），和六角形（d）。為什么采用這些特殊的形狀而不采用其他形狀的理由說明如下。流道設計效率的評判標準從壓力傳遞的角度來看流道應該具有最大的橫截面積，而從熱量傳遞的角度來看，應該和周邊有最小的接觸面積。因此橫截面積和周長的比率將直接可以指示流道設計的效率。這個值較高時，效率也高。各種類型流道橫截面的比率如圖4.3所示?？梢姀倪@種角度考慮圓形和方形的流道是兩種最滿意的設計。而半圓和矩形的比率使得它們通常很少使用。可是，方形的流道由于另一個原因，也不能另人滿意：就是頂出困難。實際上由于這個原因，在流道的直壁上，設計了一個10度的斜度，從而修改成梯形截面。梯形流道的體積在相同尺寸的（W=D,）情況下，大約比圓形流道大25%。為了減少這個不同，并且仍然維持相同的尺寸，改進后的梯形如圖4.2c所示，這個體積比之圓形的增加量大約只有14%。六角形流道基本上是兩個梯形，在分型面上相對吻合。其橫截面積大約是對應圓形流道的82%。當然，假如要求相似的橫截面積，則D值必須相應地增加。某些模具工認為，六角形流道和圓形流道相比前者在兩半模上的吻合較為方便。這點尤其適用在流道寬度尺寸少于3mm的情況。當塑料熔體通過流道和模腔時，鄰近冷的模腔表面的熔體將快速降溫而固化。其后的料流將穿過這些已經(jīng)固化的材料中心，由于大多數(shù)熱塑性塑料所具有的低熱傳導率，已固化的材料起到了隔熱作用并維持了中心料流的溫度。因此理論上，澆口應該位于流道的中心線上，從中心料流獲得材料。這種效果可以從整圓流道得到，也可以從六角形流道得到。一般的梯形流道設計難以在這方面得到滿足，因為其澆口通常不能定位在料流的中心線上。）整圓流道的主要問題是這種流道是由分別加工在兩塊模板上的兩個半圓合成的。所以把這兩個流道精確地吻合防止流道系統(tǒng)發(fā)生不良組合和效率受阻的現(xiàn)象。對六角形流道也有類似的問題。由于這些流道必須精確地吻合，使得采用圓形或六角形流道的模具比梯形流道的模具的成本高。流道截面的選擇也受到流道系統(tǒng)的頂出是否實際可行的影響。例如，考慮兩板式模具中已經(jīng)在分型面的兩邊加工成圓形流道的情況。這種情況下，當開模時，模具一側(cè)的流道廢料被從流道中拉出，然后在另一半模具中或直接被頂桿頂出或被連接在塑件上的澆口廢料帶出?？墒菍τ诙嗄０宓哪＞?，流道系統(tǒng)的可靠頂出是不可能的。這時，總是采用基本的梯形流道設計，其流道開在注射半模上，當開模時流道廢料被拉出。然后在重力的作用下，從模板之間自然下落。如果這時設計了圓形流道的話，流道系統(tǒng)可能會粘滯在流道壁上，使得流道廢料的去除發(fā)生困難?？偨Y(jié)有關(guān)橫截面形狀的幾點，我們可以說，對于具有平面分型面的簡單兩板式模具選用整圓或六角形流道較好，模具的成本增加相對較少。對于具有復雜分型面的模具，或?qū)τ诙嗄０迥＞?，由于圓形流道的兩半圓難以精確地吻合，應該采用梯形的或U形截面的流道。流道尺寸在決定流道尺寸時，設計者必須考慮以下因素：（1）塑件的壁厚和體積,（2）主流道或分流道距離型腔的尺寸，（3）流道冷卻條件，（4）模具工使用的刀具尺寸范圍和（5）所使用的塑料。（1）流道的橫截面積必須滿足允許熔體在流道凍結(jié)之前通過和充滿型腔，并且使得補縮所需要的保壓壓力能作用到型腔。因此很少使用小于2毫米（3/32in）直徑的流道，甚至這種尺寸的流道通常限于在長度在25毫米（in）以下的分流道上使用（2）此外，塑料熔體必須克服流道內(nèi)的流