流道基础中英文对照外文翻译文献

中英文对照外文翻译文献流道基础中英文对照外文翻译文献(文档含英文原文和中文翻译)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.译文：流道基础流道是在模板上加工出的连接主流道和进入（浇口）型腔的一条沟槽。在两板式基本模具中，流道设置在分型面上而在较复杂的设计中流道也许设置在分型面的下面。流道的壁必须光滑，防止料流受到阻碍。另外，由于流道废料必须和塑件一起取出，所以流道壁上必须不留下任何加工痕迹，避免流道废料滞留在模板上。为了确保这些要点得到满足，要求模具设计者在图纸中注明这条流道需要沿取出方向抛光。另外还有一些要求设计者用心考虑的：（1）流道的横截面形状，（2）流道的尺寸和（3）流道的布置。模具中用到的流道横截面形状，通常是四种形式之一（图4.2）：整圆（a），梯形（b）,U型（c），和六角形（d）。为什么采用这些特殊的形状而不采用其他形状的理由说明如下。流道设计效率的评判标准从压力传递的角度来看流道应该具有最大的横截面积，而从热量传递的角度来看，应该和周边有最小的接触面积。因此横截面积和周长的比率将直接可以指示流道设计的效率。这个值较高时，效率也高。各种类型流道横截面的比率如图4.3所示。可见从这种角度考虑圆形和方形的流道是两种最满意的设计。而半圆和矩形的比率使得它们通常很少使用。可是，方形的流道由于另一个原因，也不能另人满意：就是顶出困难。实际上由于这个原因，在流道的直壁上，设计了一个10度的斜度，从而修改成梯形截面。梯形流道的体积在相同尺寸的（W=D,）情况下，大约比圆形流道大25%。为了减少这个不同，并且仍然维持相同的尺寸，改进后的梯形如图4.2c所示，这个体积比之圆形的增加量大约只有14%。六角形流道基本上是两个梯形，在分型面上相对吻合。其横截面积大约是对应圆形流道的82%。当然，假如要求相似的横截面积，则D值必须相应地增加。某些模具工认为，六角形流道和圆形流道相比前者在两半模上的吻合较为方便。这点尤其适用在流道宽度尺寸少于3mm的情况。当塑料熔体通过流道和模腔时，邻近冷的模腔表面的熔体将快速降温而固化。其后的料流将穿过这些已经固化的材料中心，由于大多数热塑性塑料所具有的低热传导率，已固化的材料起到了隔热作用并维持了中心料流的温度。因此理论上，浇口应该位于流道的中心线上，从中心料流获得材料。这种效果可以从整圆流道得到，也可以从六角形流道得到。一般的梯形流道设计难以在这方面得到满足，因为其浇口通常不能定位在料流的中心线上。）整圆流道的主要问题是这种流道是由分别加工在两块模板上的两个半圆合成的。所以把这两个流道精确地吻合防止流道系统发生不良组合和效率受阻的现象。对六角形流道也有类似的问题。由于这些流道必须精确地吻合，使得采用圆形或六角形流道的模具比梯形流道的模具的成本高。流道截面的选择也受到流道系统的顶出是否实际可行的影响。例如，考虑两板式模具中已经在分型面的两边加工成圆形流道的情况。这种情况下，当开模时，模具一侧的流道废料被从流道中拉出，然后在另一半模具中或直接被顶杆顶出或被连接在塑件上的浇口废料带出。可是对于多模板的模具，流道系统的可靠顶出是不可能的。这时，总是采用基本的梯形流道设计，其流道开在注射半模上，当开模时流道废料被拉出。然后在重力的作用下，从模板之间自然下落。如果这时设计了圆形流道的话，流道系统可能会粘滞在流道壁上，使得流道废料的去除发生困难。总结有关横截面形状的几点，我们可以说，对于具有平面分型面的简单两板式模具选用整圆或六角形流道较好，模具的成本增加相对较少。对于具有复杂分型面的模具，或对于多模板模具，由于圆形流道的两半圆难以精确地吻合，应该采用梯形的或U形截面的流道。流道尺寸在决定流道尺寸时，设计者必须考虑以下因素：（1）塑件的壁厚和体积,（2）主流道或分流道距离型腔的尺寸，（3）流道冷却条件，（4）模具工使用的刀具尺寸范围和（5）所使用的塑料。（1）流道的横截面积必须满足允许熔体在流道冻结之前通过和充满型腔，并且使得补缩所需要的保压压力能作用到型腔。因此很少使用小于2毫米（3/32in）直径的流道，甚至这种尺寸的流道通常限于在长度在25毫米（in）以下的分流道上使用（2）此外，塑料熔体必须克服流道内的流