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塑膠產(chǎn)品設(shè)計(jì)PlasticPartDesign就傳統(tǒng)射出成形而言,實(shí)用的最小壁厚在0.75到1.00mm之間。如果要採(cǎi)用更薄的壁厚,卻又缺乏實(shí)際的經(jīng)驗(yàn),可以借助CAE作科學(xué)的決定。Forconventionalinjectionmolding,apracticalminimumwallthicknessisintherangeof0.75to1.00mm.Whenthinnerwallsarerequiredbutactualexperienceisabsent,theminimumpossiblethicknesscanbescientificallydeterminedbyCAE.壁厚
WallThickness壁厚不均是注塑成形中最大的麻煩製造者。這對(duì)薄壁零件尤然。這些麻煩包括了遲滯現(xiàn)象、短射、凹陷、發(fā)赤、噴流、翹曲及長(zhǎng)冷卻時(shí)間等;目前都可用CAE以直接或間接的方式預(yù)測(cè)。Non-uniformwallthicknessisthebiggesttroublemakerinplasticinjectionmolding.Thisisespeciallytruetothin-wallpart.Thetroubles,includinghesitation,shortshot,sinkmark,blush,jetting,warpageandlongcoolingtimeetc.,canbepredicted,directlyorindirectly,byusingCAE.壁厚不均
Non-uniformWallThickness設(shè)計(jì)高收縮率材料成型品時(shí),設(shè)計(jì)者應(yīng)將壁厚變化限制在10%。就低收縮率材料而言,許容壁厚變化可到25%。Whiledesigninginjectionmoldedpartsinhighmoldshrinkagefactormaterials,thedesignershouldtrytolimitwallthicknessvariationto10%.Theallowablewallthicknessvariationforthelowmoldshrinkagefactormaterialscanbeupto25%.壁厚不均
Non-uniformWallThickness壁厚設(shè)計(jì)WallThicknessDesign差[Poor]較好[Better]最好[Best]掏空設(shè)計(jì)(1)CoringOutDesign(1)改進(jìn)設(shè)計(jì)[Improved]原設(shè)計(jì)[Original]差[Poor]改進(jìn)[Improved]掏空設(shè)計(jì)(2)CoringOutDesign(2)外側(cè)凸轂OutsideBossA'A'A(DIA)BB=AB=2A(max.)SectionA'-A'熔接線(xiàn)70
100
熔接線(xiàn)空洞或/和凹陷的形成Voidor/andSinkMarkForming空洞(Void)凹陷(SinkMark)肋厚和內(nèi)圓角半徑的影響TheEffectofRibThickness&FilletRadius突出件和公稱(chēng)厚壁相交處的內(nèi)圓角半徑太大,會(huì)致使凹陷、空洞、殘餘應(yīng)力和長(zhǎng)的冷卻時(shí)間。該內(nèi)圓角半徑太小,會(huì)致使應(yīng)力集中。一個(gè)好的折中方案是採(cǎi)用公稱(chēng)壁厚的25%,作為內(nèi)圓角半徑。Alargefilletradiuscausessinkmark,void,residualstressandlongcoolingtime.Asmallfilletradiuscausesstressconcentration.Agoodcompromiseistousearadius,whichis25%ofthenominalwall(NW),atthejunctionoftheNWandaprojection.內(nèi)圓角半徑FilletRadius肋的底部厚度BottomThicknessofRibW0.5W2.5WW1.2WD1.5WD(A)(B)肋的設(shè)計(jì)(一)RibDesign(1)t =wallthichnessB=0.5tC =3tAAD=2BE=0.13mm(radius)F=1.5-2deg假如需要更大的強(qiáng)度,可增加肋的數(shù)目Ifmorestrengthisrequired,addadditionalribs.FBDECt
肋的設(shè)計(jì)(二)RibDesign(2)角板設(shè)計(jì)(三)GussetDesign(3)與側(cè)壁相連之凸轂(熱塑性塑膠)BossatWall(Thermoplastics)A =凸轂附著處壁厚 wallthicknessB =凸轂外環(huán)直徑 dia.ofbossoverradiiC =0.5AD =2BE =1~2degF =0.13mm(radius)G =DH =0.8AI =A/4J =2BK =0.3~1JL =0.5ALHA'A'KEIGJDAFCBSectionA'-A'遠(yuǎn)離側(cè)壁之凸轂(熱塑性塑膠)BossAwayFromWall(Thermoplastics)A =凸轂附著處壁厚 wallthicknessB =凸轂外環(huán)直徑
(含底部修整圓弧半徑) dia.ofbossoverradiiC=0.5AD=2BE =1-2degF =0.13mm(radius)G=0.95DH=0.3Gmin.toGmax.I =0.5AHEFDFGCBAIWallThickness,RibConventional0.080to0.125in(2.0to3.2mm)Thinwall:0.050to0.080in <0.050in(1.2to2.0mm) (1.2mm)WallThickness,BossesConventional0.080to0.125in(2.0to3.2mm)Thinwall:0.050to0.080in <0.050in(1.2to2.0mm) (1.2mm)WallThickness,GussetsConventional0.080to0.125in(2.0to3.2mm)Thinwall:0.050to0.080in <0.050in(1.2to2.0mm) (1.2mm)突出件在和公稱(chēng)厚壁相交處的建議厚度:以高縮水率的結(jié)晶性塑膠而言,可採(cǎi)用公稱(chēng)壁厚的50%。以低縮水率的非結(jié)晶性塑膠而言,可採(cǎi)用公稱(chēng)壁厚的75%。Therecommendedthicknessatthejunctionofaprojectionandthenominalwall(NW)is50%oftheNWthicknessforhigh-mold-shrinkage,crystallinematerials.Thelower-mold-shrinkage-factor,amorphousplasticscanhavethicknessesofupto75%ofthepart’sNWthickness.突出件壁厚
ThicknessoftheProjection有些情形,在美觀的考慮下,是不容許些微凹陷的。設(shè)計(jì)者應(yīng)當(dāng)考慮將建議厚度減少10%。Inthosecaseswhereaestheticconsiderationsprecludeevenaslightsinkmark,adesignershouldconsiderreducingtherecommendedribthicknessbyanadditional10percent.突出件壁厚
ThicknessoftheProjection從成型容易的觀點(diǎn)來(lái)看,突出件的高度以產(chǎn)品公稱(chēng)壁厚的2.5到3倍為宜。Fromaneaseofmoldingperspective,theheightofprojectionsshouldbelimitedto2.5to3timesthepartnominalwallthickness.突出件高度HeightoftheProjection強(qiáng)固的、脆的、剝蝕性的、黏的塑件要有大的脫模角和光滑的拋光。軟的、延展性的、和光滑的塑件則可有小的脫模角。Largedraftanglesandasmoothpolisharerequiredforpartsmoldedinstrong,brittle,abrasive,andstickymaterials.Smallerdraftanglescanbeusedonsoft,ductile,andslipperymaterials.突出件脫模角DraftAngleoftheProjection以本錢(qián)和可製造性的觀點(diǎn),理想的脫模角是消費(fèi)者可以接受的前題下,最大的角度。就多數(shù)情況而言,每邊1°應(yīng)已足夠,但2°或5°可以更好。模穴應(yīng)順著開(kāi)模方向打光。Theidealdraftangle,fromacostandmanufacturabilityperspective,isthelargestanglethatwillnotdistractfromtheconsumer’sacceptanceoftheproduct.Inmostcases,1°persidewillbeadequate,but2°or5°persidewouldbebetter.Thecavitiesthatformprojectionsshouldbedraw-polished.突出件脫模角DraftAngleoftheProjection距離應(yīng)大於產(chǎn)品公稱(chēng)壁厚的2倍。使得模具鋼材具備足夠的強(qiáng)度以抵抗彎曲,並且提供足夠的吸熱器,以免產(chǎn)生凹陷和成型應(yīng)力。Thisdistanceshouldbeatleast2timesthepart’snominalwallthickness,sothemoldsteelprovideenoughstrengthtoresistbendingandenoughheatsinktoavoidsinkmarkandmoldedinstress.突出件和側(cè)壁/突出件的距離TheDistancebetweenProjectionandSideWall/ProjectionAAAAA-AA-ALongRibAirTrapWhere1/r :樑的曲率
curvatureofthebeamM :彎曲力矩
bendingmomentE :彈性模數(shù)
modulusofelasticityI :斷面積對(duì)中立軸的慣性矩
momentofinertiaofthecross-sectionalareawithrespecttotheneutralaxisEI :撓曲剛性flexuralrigidity撓曲剛性
FlexuralRigidityW樑BeamLWhere :最大偏移maximumdeflectionW:負(fù)荷loadL :樑長(zhǎng)lengthofbeamE :彈性模數(shù)modulusofelasticityI :斷面積對(duì)中立軸的慣性矩momentofinertia ofthecross-sectionalareawithrespecttothe neutralaxisEI :撓曲剛性flexuralrigidity :最大應(yīng)力maximumstress :中立軸到到其斷面離其最遠(yuǎn)的點(diǎn)的距離
distancefromtheextremepointofacrosssectiontotheneutralaxisofthiscrosssection
Young’sModulus,ETheratiobetweenstressandstrainisconstant,obeyingHooke’sLaw,withintheelasticityrangeofanymaterial.ThisratioiscalledYoung’smodulusandismeasuredinMpaorpsi.NeutralAxis?10.8平板和肋板的比較
ComparisonbetweenPlain&RibbedPlates和平板比,假設(shè)基於相同的慣性矩(剛性),肋板需料少了43%,I/A卻增加了1.79倍。肋板的最大厚度減為平板的1/4,使得冷卻時(shí)間驟降15/16(94%)。Basedonthesamemomentofinertia(stiffness),ribbedplateneeds43%lessmaterialbutboostI/Aby1.79timescomparingwithplaneplate.Themaximumthicknessofribbedplateisonly1/4ofplainplate’s;showingadramaticcoolingtimereductionof94%(15/16).平板和肋板的比較
ComparisonbetweenPlain&RibbedPlatesRibheight/basethicknessRibspacingratio(Wr=.33,.2,.1,.05,.02,.01)Stressratio應(yīng)力比
(肋/無(wú)肋)StressRatio(Ribbed/Unribbed)DeflectionratioRibspacingratio(Wr=.33,.2,.1,.05,.02,.01)Ribheight/basethickness偏移比
(肋/無(wú)肋)DeflectionRatio(Ribbed/Unribbed)各種一體成形的內(nèi)鎖件能增加薄殼的剛性。Avarietyofmolded-ininterlockscanaddstiffnesstothin-wallhousingdesigns.結(jié)構(gòu)設(shè)計(jì)是薄殼成形零件的基礎(chǔ)。Structuraldesignisthebaseofthin-wallmoldingparts.薄殼成形零件不僅僅是一趨勢(shì),而且也是降低本錢(qián)和提高競(jìng)爭(zhēng)力的有效途徑。Thin-wallmoldingpartisnotonlyatrendbutalsoaneffectivewaytoachievecostreductionandcompetitivenessincrease.結(jié)構(gòu)設(shè)計(jì)和薄殼成形零件StructuralDesign&Thin-wallMoldingPartsLivingHingeDesignforPPandPE:(a)before,and(b)afterBending180oTypicalValuesofLivingHingeDesignforPPandPE:(a)MostApplication;(b)Self-openingHingeDesignMostCommonLivingHingeDesign:(a)before,and(b)afterBending180oRecommendedLivingHingeDesignwiththeNeutralAxisintheCenter:(a)before,and(b)atBendingAngleof180oCrossSectionthroughtheEntireHingeShowingItsPrincipalDimensionsCrossSectionofaPortionofaLivingHingeDesignandItsNeutralAxisPositionHingeDesignDetail:(a)asMolded;(b)asAssembled“RightWay〞
AssemblyHingeDetailCableIgnitionBracketAxonometricViewCableIgnitionBracketSideViewCableIgnitionBracketTopViewHingeDetail:
(a)InitialDesign;(b)ImprovedDesignHingeBehaviorafterAssemblyPOLYPROPYLENEHINGEDESIGNFULLR.0.18-0.300.25R.(2)PL‘X’‘Y’0.25TEARRIBATEACHENDOFHINGENOTES: 1.‘Y’DIM.PERPARTDESIGN2.‘X’DIM.=2Y+0.250.76R.0.25R.1.250.76R.(2)PL100O0.130.18–0.300.25TEARRIBATEACHENDOFHINGEPOLYPROPYLENEHINGEDESIGN孔Holes以射出成型而言,圓孔形狀理想,原因是塑料冷卻時(shí),它收縮到心型銷(xiāo),假設(shè)銷(xiāo)為圓形,應(yīng)力會(huì)均勻的分布在圓銷(xiāo)面上。Roundholesaretheidealshapefortheinjectionmoldingprocess.Thereasonforthisisthatasplasticmaterialcoolsitshrinksontothecorepinthatformsaholeand,withroundholes,thestressisuniformlydistributedaroundit.孔Holes這一尼龍風(fēng)扇因安裝孔的直線(xiàn)孔緣末端的鎖入應(yīng)力而損毀。Thisnylonfanfailedduetomolded-instressattheendofthestraightsectiononthemountinghole.孔Holes孔Holes孔Holes內(nèi)圓角和向外延伸的內(nèi)圓角(B,C,D)可以減低鎖入的應(yīng)力並且使得產(chǎn)品變強(qiáng)。Insideandoutwardlyextendingradiuses(B,C,D)reducemolded-instressandresultinastrongerpart.孔Holes從易於成型的觀點(diǎn)來(lái)看,相鄰二孔緣的距離,或是孔緣和產(chǎn)品邊緣的距離,至少要有壁厚的兩倍,而絕對(duì)不可小於壁厚。Fromaneaseofmoldingperspective,thedistancefromoneholetothenext,ortotheedgeofapart,mustbeataminimumtwotimesthepart’swallthickness,andneverlessthanthepart’swallthickness孔Holes孔Holes圖中的孔太靠近產(chǎn)品的邊緣,塑料的收縮使得該孔和其周?chē)谋”诙家蛑でheholeshownhereistooclosetotheedgeofthepart.Shrinkageoftheplasticmaterialhasdistortedthisholeandthethinwallaroundit.孔Holes
(FigureI)孔Holes圖I的盲孔A的長(zhǎng)徑比應(yīng)以2:1或3:1為限。形成圖I穿孔B的心型銷(xiāo)的自由端是頂在母模面上。這樣的心型銷(xiāo)獲得支持,而長(zhǎng)徑比可增加到6:1。Thelength-to-diameterratiooftheblindholeinFigureI(A)islimitedtoonly2:1or3:1.ThethroughholeBinFigureIallowsthefreeendofthecorepintobeseatedagainstthecavity.Thissupportsthecoreandallowsitslength-to-diametertobe6:1.孔Holes如圖I的C所示,將型心延伸至母模側(cè)的配合孔,可以提供額外的支撐,兩頭支撐的型心銷(xiāo)的長(zhǎng)徑比可達(dá)12:1。如圖I的D所示,以二支型心銷(xiāo)成型深孔,可以消除型心銷(xiāo)和母模面的磨耗。這種方法產(chǎn)生的孔也可有12:1的長(zhǎng)徑比。Telescopingthecoreintoamatingholeinthecavity,CinFigureI,providesadditionalsupport.Acorepinanchoredatbothendscanhavealength-to-diameterratioof12:1.Moldingadeepholewithtwocorepins,DinFigureI,eliminateswearbetweenthecorepinandthecavity.Holesproducedinthismannercanalsohavea12:1length-to-diameterratio.塑膠工業(yè)協(xié)會(huì)(SPI)指定12種拋光,從鑽石高度拋光,到噴砂粗度拋光。依照SPI模具拋光指南,來(lái)指定外表光滑度,已經(jīng)被國(guó)際接受。TheSocietyofthePlasticsIndustry(SPI)specified12finishes,rangingfromahighdiamondpolishtoarough,blastedsurface.TheSPIMoldFinishGuidehasbecometheinternationallyacceptedforspecifyingsurfacefinishes.外表光滑度
SurfaceFinish如果型心形成的內(nèi)面沒(méi)有拋光,頂出力和循環(huán)時(shí)間都會(huì)相應(yīng)增加。Ifthecorethatformstheinsidesurfacesisnotsmoothlypolished,theejectionforcesandthecycletimewillincreaseaccordingly.外表光滑度
SurfaceFinish只在成型品頂出方向拋光,可以消除側(cè)凹。這種拋光方法被稱(chēng)作“抽拋〞。設(shè)計(jì)工程師應(yīng)於零件須要最小或0脫模角時(shí),指定抽拋。Polishingthemoldonlyinthedirectionthatthemoldedpartmovesduringejectioneliminatestheseundercuts.Thispolishingtechniqueiscalled“drawpolishing.〞Designengineerswouldbewelladvisedtospecifydrawpolishingonpartsrequiringminimalornodraftangles.外表光滑度
SurfaceFinish無(wú)論模面如何光滑,低密度聚乙烯都無(wú)法產(chǎn)生和聚苯乙烯接近的光亮外表。補(bǔ)強(qiáng)料加得多的塑料不能有效的產(chǎn)生光亮的外表。一般說(shuō)來(lái),熱模較之冷模,較能產(chǎn)生光滑的外表。保壓缺乏的產(chǎn)品無(wú)法忠實(shí)的複現(xiàn)模面的光滑。Regardlessofthefinishonthemold,low-densitypolyethylenecanneverproducetheshinyappearanceofapolystyrenepart.Heavilyfilledorreinforcedpolymercannotreliablyproduceshinysurfaces.Generallyspeaking,ahotmoldwillproducebettersurfacesthanacoldmold.Apoorlypackedoutpartwillnotfaithfullyreplicatethemoldpolishonallofthepartsurfaces.外表光滑度
SurfaceFinish最軟的聚乙烯和聚氯乙烯、polyurethanes和某些熱塑性elastomers有沾黏高度拋光金屬面的傾向。這類(lèi)黏的材料,一般較易從粗糙面或輕度噴砂面脫模。Thesoftestpolyethylenesandpolyvinylchlorides,polyurethanes,andsomethermoplasticelastomershaveatendencytoadheretohighlypolishedmetalsurfaces.Stickymaterialsofthistypewillnormallyreleasebetterfrommoldingsurfaceswithmatteorlightlyblastedsurfacefinish.外表光滑度
SurfaceFinish強(qiáng)壯而又有些彈性的塑膠,像聚丙烯、ABS和耐衝擊聚苯乙烯,較之剛而脆的材料,如一般用途用聚丙烯和壓克力,更能接受粗略?huà)伖獾哪C?。?duì)這些硬而脆的材料,抽拋是非常有益的。Strongbutsomewhatflexibleplastics,suchaspolypropylene,ABS,andimpactstyrene,aremoretolerantofroughlypolishedmoldingsurfacesthanrigid,brittlematerials,suchasgeneral-purposestyreneandacrylics.Drawpolishingisverybeneficialwiththesehard,brittlematerials.外表光滑度
SurfaceFinish不能指望產(chǎn)品設(shè)計(jì)師、模具製造者以及拋光公司知道所有不同塑料的癖性。然而,我們可以倚賴(lài)塑料供應(yīng)商和有經(jīng)驗(yàn)的成型者,他們知道那一種模面光滑度適合那一種特定的塑料。Productdesigners,moldmakers,andpolishingcompaniescannotbeexpectedtoknowtheidiosyncrasiesofallofthedifferentplasticmaterials.Plasticmaterialsuppliersandexperiencedmolderscan,however,bereliedupontoknowwhatmoldfinishisoptimalforagivenmaterial.外表光滑度
SurfaceFinish有些工業(yè)界的內(nèi)行者,估計(jì)拋光代表了模具平均本錢(qián)的10%。這個(gè)平均值當(dāng)然會(huì)有明顯的差異,這要看模具的尺寸和形狀、金屬的硬度、要求拋光的程度、以及拋光前模面的光滑程度。Someindustryinsidershaveestimatedthat,ontheaverage,polishingcanrepresent10%ofamoldoverallcost.Thisaveragewillobviouslyvary,dependingonthesizeandshapeofthemold,thehardnessofthemetal,thelevelofpolishrequired,andhowwellthemoldwasfinishedpriortopolishing.外表光滑度
SurfaceFinish對(duì)不透明件而言,大多數(shù)消費(fèi)者無(wú)法分辨SPI指南中最高三級(jí)光滑度的分別,SPI的最高二級(jí)光滑度應(yīng)為可以看穿的透明件保存。換言之,為何要花錢(qián)在消費(fèi)者無(wú)法感謝的外表光滑度上?MostconsumerswillnotnoticethedifferencesbetweentheSPIGuidethreehighestfinishesonanopaquepart.ThetwobestSPIfinishesshouldbereservedfortransparent,see-throughparts.Inotherwords,whyspendmoneyonasurfacefinishthattheconsumercannotappreciate?外表光滑度
SurfaceFinish產(chǎn)品圖上必須標(biāo)明外表光滑度,高度建議參照SPI模具光滑度指南。Thesurfacefinishmustbeclearlyindicatedonthepartdrawing.ItisstronglyrecommendedthatsurfacefinishbespecifiedaccordingtoSPIMoldFinishGuide.外表光滑度
SurfaceFinish外表花紋
Pattern咬花
Texture設(shè)計(jì)者必須指出咬花從那裏開(kāi)始,到那裏結(jié)束。一個(gè)好的咬花標(biāo)註,應(yīng)該指出花紋號(hào)碼、咬花深度、咬花位置,如果要更得當(dāng)?shù)脑?huà),還要加上花紋的方向。當(dāng)一產(chǎn)品是由數(shù)件零件組合而成,一定要指出咬花花紋的方向。Thedesignermustindicatewherethetexturestopsandstarts.Agoodtexturingnoteshouldindicatethepatternnumber,depthoftexture,itslocation,and-ifappropriate-thedirectionofthepattern.Inthoseinstanceswhereseveralpartsfittogetherinoneproduct,thedirectionofthetexturepatternabsolutelymustbespecified.咬花
Texture咬花
Texture半結(jié)晶塑料的收縮率較高,這些塑料因在平行和垂直於熔膠流動(dòng)方向有著不同的收縮率,而多了一層問(wèn)題。這問(wèn)題又因成型條件改變致使結(jié)晶度變化而更形複雜。如果塑料冷卻得慢,結(jié)晶度和收縮率都會(huì)增加。Thesemi-crystallineplasticshashighermoldshrinkagefactors.Thesematerialshavetheadditionalproblemofdifferentshrinkagefactorsparalleltoandperpendiculartothedirectionofmeltflow.Thisproblemisfurthercompoundedbyvariationsinthedegreeofcrystallinitycausedbychangesinmoldingconditions.Ifthematerialiscooledslowly,therewillbeanincreaseincrystallinityandmoldshrinkage.收縮
Shrinkage
非結(jié)晶塑料收縮率低,較易維持尺寸的複現(xiàn)性。發(fā)表的收縮率,是以3.175mm(0.125吋)的壁厚為準(zhǔn)。Itiseasiertomaintaindimensionalreproducibilitywithlowmoldshrinkagefactoramorphousmaterials.Thepublishedmoldshrinkagedataisbasedonamoldedpartwitha3.175mm(0.125inch)wallthickness.收縮
Shrinkage
設(shè)計(jì)射出成型零件,當(dāng)塑料收縮率高時(shí),應(yīng)試圖限制壁厚變化在10%之內(nèi)。當(dāng)塑料收縮率低時(shí),許容壁厚變化在25%以?xún)?nèi)。Whiledesigninginjectionmoldedpartsinhighmoldshrinkagefactormaterials,thedesignershouldtrytolimitwallthicknessvariationsto10%.Theallowablewallthicknessvariationforthelowmoldshrinkagefactormaterialscanbeupto25%.收縮
Shrinkage
塑膠模具設(shè)計(jì)PlasticMouldDesign徐昌煜CharlesHsu模具設(shè)計(jì)的優(yōu)先順序PrioritiesofMouldDesign澆注系統(tǒng)設(shè)計(jì)(FillingSystemDesign)排氣系統(tǒng)設(shè)計(jì)(VentingSystemDesign)冷卻系統(tǒng)設(shè)計(jì)(CoolingSystemDesign)脫模系統(tǒng)設(shè)計(jì)(EjectingSystemDesign)澆注系統(tǒng)設(shè)計(jì)FillingSystemDesign徐昌煜CharlesHsu澆注系統(tǒng)設(shè)計(jì)的優(yōu)先順序PrioritiesofFillingSystemDesign產(chǎn)品設(shè)計(jì)(PartDesign)型腔設(shè)計(jì)(CavityDesign)澆口設(shè)計(jì)(GateDesign)流道設(shè)計(jì)(RunnerDesign)豎澆道設(shè)計(jì)(SprueDesign)噴嘴設(shè)計(jì)(NozzleDesign)豎澆道Sprue主流道MainRunner成品Part澆口Gate冷料井ColdSlugWell支流道BranchRunner典型的澆注系統(tǒng)TypicalFillingSystem每增加一個(gè)澆口,至少增加一條熔接線(xiàn),同時(shí)增加一個(gè)澆口痕跡、增加流道的體積以及增加較多的積風(fēng)。Everytimeonegateisadded,oneweldline,atleast,onegatemark,morerunnervolumeandmoreairtrapswillbeadded.在型腔能夠完滿(mǎn)充填的前提下,澆口數(shù)目是愈少愈好。Aslongasthecavityisabletobefilledappropriately,gatesarethelessthebetter.為了減少澆口數(shù)目,每一澆口應(yīng)就塑流力所能及的流長(zhǎng)/壁厚比之內(nèi),找出可以涵蓋最大零件面積的進(jìn)澆位置。Inordertoreducethenumberofgates,eachgateshallbelocatedatwherethemeltisabletocovermaximumpartareabasedonthelargestmeltflowlength/thicknessratio.澆口數(shù)目TheNumberofGates熔膠波前推進(jìn)Melt-FrontAdvancement充填模式,積風(fēng)和熔接線(xiàn)FillingPatterns,Air-TrapsandWeldLinesLocation熔接線(xiàn)WeldLines材料[Material]:PC-GF50原設(shè)計(jì)[Original]更改設(shè)計(jì)[Revised]更改澆口位置以重新定位熔接線(xiàn)WeldLinesCanBeRelocatedByChangingGateLocation典型對(duì)頭熔接線(xiàn)伸張強(qiáng)度保存值TypicalButtWeldTensileStrengthRetentionValues熔接線(xiàn)冷料井WeldSlugWell對(duì)頭熔接線(xiàn)[Buttweld]熔接線(xiàn)冷料井[Weldslugwell]熔接線(xiàn)WeldLines熔接線(xiàn)WeldLines當(dāng)波前相遇後,繼續(xù)一塊兒流動(dòng),如此產(chǎn)生的熔接線(xiàn)是動(dòng)態(tài)的。這樣的線(xiàn)條也稱(chēng)作熔合線(xiàn)。
熔接線(xiàn)形成後,熔膠不再流動(dòng),如此產(chǎn)生的熔接線(xiàn)是靜態(tài)的或是對(duì)頭的。靜態(tài)的熔接線(xiàn)位於型腔的末端,一般比靠近澆口的動(dòng)態(tài)的熔接線(xiàn)脆弱而且明顯。Whentheflowfrontsmeetandcontinuetoflowtogether,theresultingweldlineisreferredtoasdynamic.Thistypeofweldlineisalsocalledameldline.Weldlinesthatareformedwithnoadditionalmeltflowarereferredtoasstaticorbuttweldlines.Staticweldlineslocatedattheextremitiesofacavityarenormallyweakerandmoreobviousthandynamicweldlinesformedclosetoagate.左邊澆口在這些窗葉的中央,產(chǎn)生了靜態(tài)的熔接線(xiàn)。Thegatelocatedontheleftsidecreatesstaticweldlinesinthemiddleoftheselouvers.熔接線(xiàn)WeldLines熔接線(xiàn)WeldLines這一局部充填的產(chǎn)品,顯示了兩條靜態(tài)的熔接線(xiàn),在外面二孔外產(chǎn)生;澆口位於產(chǎn)品上邊中央。Thispartiallyfilledpartshowstwostaticweldlinesbytheoutsideholes.Thegateislocatedatthecenterofthepart,nearthetop.積風(fēng)AirTraps排氣Vent大部份熱塑性塑膠MostThermoplastics A0.08mm B3.18mm C12.7mm D0.25mm尼隆和聚縮醛(POM)NylonandAcetal(POM) A0.04mm B3.18mm C12.7mm D0.25mm進(jìn)料流道FeedRunner塑膠成品PlasticPartAD排氣槽VentBSEC.A'-A'CA'A'流動(dòng)平衡FlowBalance熔膠波前於同一時(shí)間抵達(dá)型腔各末端。Meltfrontreachestheendsofcavityatthesametime.洗衣機(jī)圈板洗衣機(jī)圈板冷氣通風(fēng)飾罩-原始設(shè)計(jì)Air-conditionerGrille,Original18gatespressure:76MPa冷氣通風(fēng)飾罩-更正設(shè)計(jì)Air-conditionerGrille,Revised8gatespressure:75MPa分析結(jié)果比較ComparisonofAnalysisResults十二澆口設(shè)計(jì)12GateDesign原始設(shè)計(jì)OriginalDesign電子零件置物箱材料Material:ABS四澆口設(shè)計(jì)4GateDesign更正設(shè)計(jì)RevisedDesign電子零件置物箱材料Material:ABS電子零件置物箱四澆口和十二澆口設(shè)計(jì)比較表論語(yǔ)?季氏第十六
不患寡而患不均,
不患貧而患不安。
-孔子-如何快速平衡多型腔模之塑流HowtoBalanceFlowsInAMulti-cavityMould首先調(diào)整一排支流道內(nèi)之次支流道尺寸,使此支流道內(nèi)之各型腔可平衡充填。
First,adjustrunnersizeinonebranchtomakeflowbalancedinthisbranch.再調(diào)整各支流道前段之尺寸,使各支流道可平衡充填。
Then,adjustthefirstsection’srunnersizeineachbranchtomakeflowbalancedinallbranches.一排支流道之不平衡充填Unbalanced
FlowInABranch一排支流道平衡後之充填BalancedFlowInABranch128型腔模之不平衡充填UnbalancedFlowInA128CavityMould128型腔模平衡後之充填BalancedFlowInA128CavityMouldTherunnersystemshowsthatwarmer,low-viscositymaterial(yellowandred)followstheinsidewallwhenthemeltsplitsatanintersection.Melt〞Flipper〞剪切速率ShearRate剪切應(yīng)力shearstress黏度viscosity剪切速率shearrate剪切應(yīng)力ShearStress澆口種類(lèi)GateTypes針點(diǎn)澆口PinGate扇型澆口FanGate潛伏澆口SubmarineGate邊緣(薄膜)澆口Edge(Film)Gate凸片澆口TabGate閥式澆口ValveGate環(huán)狀澆口RingGate導(dǎo)致平直製件的澆口設(shè)計(jì)GateDesignforFlatPart中心澆口CenterGate扇形澆口FanGate最壞的Worst壞的Worse較好的Better最好的Best側(cè)澆口EdgeGate薄模澆口FilmGate澆口設(shè)計(jì)(減少滯流效應(yīng))GateDesigntoAvoidHesitation澆口gate薄thin厚thick差的設(shè)計(jì)Poor好的設(shè)計(jì)Good薄thin厚thick澆口gate0.94秒時(shí),遲滯現(xiàn)象在1.2mm厚凸片處發(fā)生幫浦零件(Part,Pump)塑料(Polymer):POM公稱(chēng)厚度3.2mm沒(méi)有遲滯現(xiàn)象幫浦零件(Part,Pump)塑料(Polymer):POM澆口設(shè)計(jì)(防止凹陷和空洞)GateDesigntoAvoidSinkMark&Void澆口gate澆口gate差的Poor好的Good噴流Jetting使用沖擊型澆口以防止噴流AvoidJettingbyUsingImpingementGate差的Poor好的Good差的Poor好的Good使用沖擊型澆口以防止噴流AvoidJettingbyUsingImpingementGate使用凸片澆口以防止噴流AvoidJettingbyUsingTabGate使用適當(dāng)?shù)臐部谛螤钜苑乐箛娏鰽voidJettingbyProfilingGateProperly差的Poor好的Good幫浦零件(Part,Pump)塑料(Polymer):POM進(jìn)澆處(Polymerentrance):澆口厚(Gatethickness)1.2mm,型腔厚(Cavitythickness)3.2mm問(wèn)題(Problem):噴流(Jetting)PoorDesignCausingJettingGatePart :Handle,RefrigeratorMaterial :ABSProblem :JettingMarkGasPin氣輔射出成型冰箱把手澆口及氣針入口澆口太小,導(dǎo)致噴流痕產(chǎn)生厚度差異過(guò)大,導(dǎo)致二次噴流痕產(chǎn)生R角過(guò)小,氣體通路接近把手內(nèi)側(cè),外側(cè)則因體積收縮造成凹陷痕跡閥式澆口ValveGate1.閥式澆口梢 Valve-GatePin2. 加熱管 Heater3. O型環(huán) #610"0"Ring4. 流道歧管模板 ManifoldPlate5. 軸封環(huán) SealRetainer6. 套筒軸封 SleeveSeal7. 枕塊 SupportPillar8. 油壓缸 HydraulicCylinder閥式澆口(一)ValveGate(1)全部閥式澆口同時(shí)打開(kāi)時(shí)之充填狀況Moldfillingwithallthevalvegates(shut-offgates)openedatthesametime.閥式澆口(二)ValveGate(2)部份閥式澆口延遲打開(kāi),改變充填模式Moldfillingwithdelayedvalvegateopening;fillingpattern,weldlinesandairtrapsarechanged.多澆口設(shè)計(jì)Multi-gateDesign閥式澆口ValveGate矩形邊緣澆口設(shè)計(jì)RectangularEdgeGateDesignL=0.5~0.75mmW=澆口寬度(mm)gatewidthinmmA=型腔表面積(mm2
)surfaceareaofcavityinmm2n=材料常數(shù)materialconstant
0.6forPE,PS0.7forPOM,PP0.75forABS0.8forCA,PMMA,PA,PC0.9forPVCh=nth=澆口厚度(gatethick.inmm)t=製件壁厚(wallthick.inmm)WtLh扇形澆口設(shè)計(jì)FanGateDesignL=1.3mmW=w=澆口寬度[mm]gatewidthinmmA=型腔表面積[mm]surfaceareaofcavityinmmn=材料常數(shù)[materialconstant]0.6forPE,PS0.7forPOM,PP0.75forABS0.8forCA,PMMA,PA,PC0.9forPVC澆口厚度[gatethick.inmm]t=製件壁厚[wallthick.inmm]22h1=nth2=wh1/D重疊式澆口設(shè)計(jì)OverlapGateDesignW=w=澆口寬度[mm]gatewidthinmmA=型腔表面積[mm]surfaceareaofcavityinmmn=材料常數(shù)[materialconstant]0.6forPE,PS0.7forPOM,PP0.75forABS0.8forCA,PMMA,PA,PC0.9forPVC澆口厚度[gatethick.inmm]=nt澆口長(zhǎng)度[landlengthinmm]t=製件壁厚[wallthick.inmm]22
L1=0.5~0.75L2=h+(w/2)凸耳澆口設(shè)計(jì)TabGateDesignL=0.5~0.75mmW=w=澆口寬度[mm]gatewidthinmmA=型腔表面積[mm]surfaceareaofcavityinmmn=材料常數(shù)[materialconstant]0.6forPE,PS0.7forPOM,PP0.75forABS0.8forCA,PMMA,PA,PC0.9forPVC澆口厚度[gatethick.inmm]t=製件壁厚[wallthick.inmm]22h1=nth2=0.9t針點(diǎn)澆口設(shè)計(jì)PinGateDesignL =0.5~0.75mmd =澆口直徑(mm)gatediameterinmmt =製件壁厚(mm)wallthick.inmmA =型腔表面積
(mm)surfaceareaofcavityinmmn =材料常數(shù)materialconstant
0.6forPE,PS0.7forPOM,PP0.75forABS0.8forCA,PMMA,PA,PC0.9forPVCdLt潛伏式澆口設(shè)計(jì)SubgateDesignW=w=澆口寬度[mm]gatewidthinmmA=型腔表面積[mm]surfaceareaofcavityinmmn=材料常數(shù)[materialconstant]0.6forPE,PS0.7forPOM,PP0.75forABS0.8forCA,PMMA,PA,PC0.9forPVC澆口厚度[gatethick.inmm]=ntt=製件壁厚[wallthick.inmm]230~15o~25o2水力直徑HydraulicDiameterWhereisthehydraulicdiameter水力直徑Aisthecross-sectionalareaoftheflow
流路斷面積Pisthewettedperimeter濕周長(zhǎng)在不同剖面形狀,相同斷面積下之變化Variousrunnerprofiles,basedonthesamecross-sectionalarea水力直徑HydraulicDiameter流道尺寸設(shè)計(jì)(1)RunnerSizing(1)D :流道直徑(mm) runnerdiameterinmmW :下游塑膠重量(g) downstreamplasticweightL :流道長(zhǎng)度(mm) runnerlengthinmm流道尺寸設(shè)計(jì)(2)RunnerSizing(2)流道尺寸設(shè)計(jì)(3)RunnerSizing(3)流道尺寸設(shè)計(jì)(4)RunnerSizing(4)H/2(L)比較圓形流道截面積(AR)與改良型梯形流道截面積(AT)。假設(shè)圓形流道的直徑與改良型梯形流道的高度相等。Comparingthecross-sectionalareaoffull-roundrunner(AR)andtheoneofmodifiedtrapezoidal(AT),whenthediameteroftheroundrunnerandtheheightofthetrapezoidalrunnerarethesame.換言之,改進(jìn)型梯形流道所使用的材料比圓形流道的材料多了20.38%。Inotherwords,modifiedtrapezoidalrunneruses20.38%morematerialthanfull-roundrunnerdoes.冷料井設(shè)計(jì)ColdSlugWellDesign2d次流道Secondaryrunnerd主流道Primaryrunner澆口Gate型腔Cavity冷料井設(shè)計(jì)ColdSlugWellDesign倒椎度冷料井豎澆道拉料桿Reversetapercoldslug-wellspruepullerZ型冷料井豎澆道拉料桿"Z"-tapercoldslug-wellspruepuller溝型冷料井豎澆道拉料桿Groovedcoldslug-wellspruepuller冷料井設(shè)計(jì)ColdSlugWellDesign澆道襯套尺寸SprueBushingSizing噴嘴球頭和澆道襯套承窩半徑RadiusofNozzleHead&ofSprueBushSocket排氣系統(tǒng)設(shè)計(jì)VentingSystemDesign徐昌煜CharlesHsu為何排氣仍然還是一個(gè)問(wèn)題?Whyventingisstillaproblem?因?yàn)榻档蜕渌伲尫e風(fēng)有較多的時(shí)間逃氣,是一件太容易的事。但是…Becauseitistooeasytoslowdowntheinjectionspeedandgivethetrappedairmoretimetoescape.But...排氣Vent射速一降,熔膠溫度很快降低,射壓必須提高,殘餘應(yīng)力隨之提高,翹曲的可能性增加。如果想藉提高料溫,以降低射壓,料溫必須升得很高,這樣又會(huì)引起塑料裂解。Wheninjectionspeedislower,melttemperaturegoesdownveryfast,injectionpressurehastobeincreased,residualstressisincreasedandthepossibilitygettingwarppagebecomeshigher.Ifonewouldliketoincreasebarreltemperaturetoreducetherequiredinjectionpressure,thebarreltemperaturehastobeincreasedtoaquitehighlevelandpolymerdegradationwouldbeinduced.排氣Vent高料溫和高射壓都說(shuō)明充填系統(tǒng)有了流動(dòng)的問(wèn)題Bothhighbarreltemperatureandhighinjectionpressureareindicationsofflowprobleminthefillingsystem.排氣Vent我們常發(fā)現(xiàn):射速提高時(shí),塑料表現(xiàn)得更為出色。Itisquitecommonthatmaterialperformsbetterwhenitisinjectedfaster.最適化螺桿速度充分運(yùn)用摩擦熱,將塑流保持在最正確狀態(tài)。許多充填和翹曲的問(wèn)題也就迎刃而解。Anoptimizedramspeedprofilefullyusesthefrictionheattokeepthebestflowcharacteristics,whichcorrectsmanyofthefillandwarpageproblems.排氣Vent有了適當(dāng)?shù)呐艢猓渌倏梢蕴岣?,充填和保壓可達(dá)良好狀態(tài),不須過(guò)度增加料管和噴嘴的溫度。Withproperventing,theinjectionspeedcouldbeincreasedtoachievegoodfillandpackconditions,withouthavingtoraisethebarrelandnozzleheats,improperly.排氣Vent深度(depth): 1.0.075mm易流塑料(easy-flowmat.) 2.0.125mm難流塑料(stiffer-flowmat.) 3.深度深到流道末端見(jiàn)毛邊為準(zhǔn)(deepenoughtofeelflashatrunnerend)寬度(width):
和流道同寬(aswideasrunnerdia.)排氣唇部(ventlip):1.5mmA1拋光(finish)排氣通道通大氣(ventchanneltoatmosphere): 1mm深(deep)流道排氣RunnerVent流道排氣RunnerVent深度(depth) :參照廠商建議(referto manufacturer’srecommendation)寬度(width) :全圓周長(zhǎng)(wholeperimeter)or 5mm/25mm長(zhǎng)度(length) :1.5mmor1mmA1拋光(finish)排氣通道通大氣(ventchanneltoatmosphere):
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