《塑胶模具设计》PPT课件.ppt

塑膠產品設計PlasticPartDesign徐昌煜CharlesHsu,就傳統射出成形而言，實用的最小壁厚在0.75到1.00mm之間。如果要採用更薄的壁厚，卻又缺乏實際的經驗，可以借助CAE作科學的決定。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。這對薄壁零件尤然。這些麻煩包括了遲滯現象、短射、凹陷、發赤、噴流、翹曲及長冷卻時間等；目前都可用CAE以直接或間接的方式預測。Non-uniformwallthicknessisthebiggesttroublemakerinplasticinjectionmolding.Thisisespeciallytruetothin-wallpart.Thetroubles,includinghesitation,shortshot,sinkmark,blush,jetting,warpageandlongcoolingtimeetc.,canbepredicted,directlyorindirectly,byusingCAE.,壁厚不均Non-uniformWallThickness,設計高收縮率材料成型品時，設計者應將壁厚變化限制在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,壁厚設計WallThicknessDesign,掏空設計(1)CoringOutDesign(1),掏空設計(2)CoringOutDesign(2),外側凸轂OutsideBoss,空洞或/和凹陷的形成Voidor/andSinkMarkForming,肋厚和內圓角半徑的影響TheEffectofRibThicknessshowingadramaticcoolingtimereductionof94%(15/16).,平板和肋板的比較ComparisonbetweenPlain(b)Self-openingHingeDesign,MostCommonLivingHingeDesign:(a)before,and(b)afterBending180,RecommendedLivingHingeDesignwiththeNeutralAxisintheCenter:(a)before,and(b)atBendingAngleof180,CrossSectionthroughtheEntireHingeShowingItsPrincipalDimensions,CrossSectionofaPortionofaLivingHingeDesignandItsNeutralAxisPosition,HingeDesignDetail:(a)asMolded;(b)asAssembled,“RightWay”AssemblyHingeDetail,CableIgnitionBracketAxonometricView,CableIgnitionBracketSideView,CableIgnitionBracketTopView,HingeDetail:(a)InitialDesign;(b)ImprovedDesign,HingeBehaviorafterAssembly,POLYPROPYLENEHINGEDESIGN,NOTES:1.YDIM.PERPARTDESIGN2.XDIM.=2Y+0.25,POLYPROPYLENEHINGEDESIGN,孔Holes,以射出成型而言，圓孔形狀理想，原因是塑料冷卻時，它收縮到心型銷，若銷為圓形，應力會均勻的分布在圓銷面上。Roundholesaretheidealshapefortheinjectionmoldingprocess.Thereasonforthisisthatasplasticmaterialcoolsitshrinksontothecorepinthatformsaholeand,withroundholes,thestressisuniformlydistributedaroundit.,孔Holes,這一尼龍風扇因安裝孔的直線孔緣末端的鎖入應力而損毀。Thisnylonfanfailedduetomolded-instressattheendofthestraightsectiononthemountinghole.,孔Holes,孔Holes,最初，此一玻纖補強的尼龍計時鏈輪中央的方型驅動軸孔，有四個銳角。使用幾個月後，這些鏈輪，從方孔的銳角，到其附近的鏈輪齒根，產生裂隙而報廢。後來，在方孔的四個角落，加了向外延伸的小孔之後，鏈輪便不再開裂。Theglass-fiber-reinforcednylontimingsprocketswereintroducedwithsharpcornersonthesquaredriveshafthole.Thesesprocketsfailedafterseveralmonthsinthefieldduetocracksradiatingfromacorneronthesquareholetotherootofanearbygeartooth.Thesefieldfailureswereeliminatedbyaddingtheoutwardlyextendingradiuses.,孔Holes,內圓角和向外延伸的內圓角(B,C,D)可以減低鎖入的應力並且使得產品變強。Insideandoutwardlyextendingradiuses(B,C,D)reducemolded-instressandresultinastrongerpart.,孔Holes,孔A和B能以簡單直接開模的方式成形，孔C則須要一較複雜的側向運動心型，方能成形。HolesAandBcanbemoldedwithasimple,straightopeningmold.HoleCrequiresamorecomplexside-actingmold.,從易於成型的觀點來看，相鄰二孔緣的距離，或是孔緣和產品邊緣的距離，至少要有壁厚的兩倍，而絕對不可小於壁厚。Fromaneaseofmoldingperspective,thedistancefromoneholetothenext,ortotheedgeofapart,mustbeataminimumtwotimesthepartswallthickness,andneverlessthanthepartswallthickness,孔Holes,孔Holes,圖中的孔太靠近產品的邊緣，塑料的收縮使得該孔和其周圍的薄壁都因之扭曲。Theholeshownhereistooclosetotheedgeofthepart.Shrinkageoftheplasticmaterialhasdistortedthisholeandthethinwallaroundit.,孔Holes(FigureI),孔Holes,圖I的盲孔A的長徑比應以2:1或3:1為限。形成圖I穿孔B的心型銷的自由端是頂在母模面上。這樣的心型銷獲得支持，而長徑比可增加到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的配合孔，可以提供額外的支撐，兩頭支撐的型心銷的長徑比可達12:1。如圖I的D所示，以二支型心銷成型深孔，可以消除型心銷和母模面的磨耗。這種方法產生的孔也可有12:1的長徑比。Telescopingthecoreintoamatingholeinthecavity,CinFigureI,providesadditionalsupport.Acorepinanchoredatbothendscanhavealength-to-diameterratioof12:1.Moldingadeepholewithtwocorepins,DinFigureI,eliminateswearbetweenthecorepinandthecavity.Holesproducedinthismannercanalsohavea12:1length-to-diameterratio.,塑膠工業協會(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，來指定表面光滑度，已經被國際接受。TheSocietyofthePlasticsIndustry(SPI)specified12finishes,rangingfromahighdiamondpolishtoarough,blastedsurface.TheSPIMoldFinishGuidehasbecometheinternationallyacceptedforspecifyingsurfacefinishes.,表面光滑度SurfaceFinish,如果型心形成的內面沒有拋光，頂出力和循環時間都會相應增加。Ifthecorethatformstheinsidesurfacesisnotsmoothlypolished,theejectionforcesandthecycletimewillincreaseaccordingly.,表面光滑度SurfaceFinish,只在成型品頂出方向拋光，可以消除側凹。這種拋光方法被稱作“抽拋”。設計工程師應於零件須要最小或0脫模角時，指定抽拋。Polishingthemoldonlyinthedirectionthatthemoldedpartmovesduringejectioneliminatestheseundercuts.Thispolishingtechniqueiscalled“drawpolishing.”Designengineerswouldbewelladvisedtospecifydrawpolishingonpartsrequiringminimalornodraftangles.,表面光滑度SurfaceFinish,無論模面如何光滑，低密度聚乙烯都無法產生和聚苯乙烯接近的光亮外表。補強料加得多的塑料不能有效的產生光亮的外表。一般說來，熱模較之冷模，較能產生光滑的外表。保壓不足的產品無法忠實的複現模面的光滑。Regardlessofthefinishonthemold,low-densitypolyethylenecanneverproducetheshinyappearanceofapolystyrenepart.Heavilyfilledorreinforcedpolymercannotreliablyproduceshinysurfaces.Generallyspeaking,ahotmoldwillproducebettersurfacesthanacoldmold.Apoorlypackedoutpartwillnotfaithfullyreplicatethemoldpolishonallofthepartsurfaces.,表面光滑度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。這類黏的材料，一般較易從粗糙面或輕度噴砂面脫模。Thesoftestpolyethylenesandpolyvinylchlorides,polyurethanes,andsomethermoplasticelastomershaveatendencytoadheretohighlypolishedmetalsurfaces.Stickymaterialsofthistypewillnormallyreleasebetterfrommoldingsurfaceswithmatteorlightlyblastedsurfacefinish.,表面光滑度SurfaceFinish,強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，更能接受粗略拋光的模面。對這些硬而脆的材料，抽拋是非常有益的。Strongbutsomewhatflexibleplastics,suchaspolypropylene,ABS,andimpactstyrene,aremoretolerantofroughlypolishedmoldingsurfacesthanrigid,brittlematerials,suchasgeneral-purposestyreneandacrylics.Drawpolishingisverybeneficialwiththesehard,brittlematerials.,表面光滑度SurfaceFinish,不能指望產品設計師、模具製造者以及拋光公司知道所有不同塑料的癖性。然而，我們可以倚賴塑料供應商和有經驗的成型者，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.,表面光滑度SurfaceFinish,有些工業界的內行者，估計拋光代表了模具平均成本的10%。這個平均值當然會有明顯的差異，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.,表面光滑度SurfaceFinish,對不透明件而言，大多數消費者無法分辨SPI指南中最高三級光滑度的分別，SPI的最高二級光滑度應為可以看穿的透明件保留。換言之，為何要花錢在消費者無法感激的表面光滑度上？MostconsumerswillnotnoticethedifferencesbetweentheSPIGuidethreehighestfinishesonanopaquepart.ThetwobestSPIfinishesshouldbereservedfortransparent,see-throughparts.Inotherwords,whyspendmoneyonasurfacefinishthattheconsumercannotappreciate?,表面光滑度SurfaceFinish,產品圖上必須標明表面光滑度，高度建議參照SPI模具光滑度指南。Thesurfacefinishmustbeclearlyindicatedonthepartdrawing.ItisstronglyrecommendedthatsurfacefinishbespecifiedaccordingtoSPIMoldFinishGuide.,表面光滑度SurfaceFinish,一般說來，成本或交貨期，會隨著決定採用電火花加工法、噴砂法和照相化學腐蝕法的順序而增加。所有方法都能供給不同程度的表面花紋。較細的花紋像編織物或風乾木材的紋理，只能靠照相化學腐蝕提供。Generallyspeaking,thecostanddeliverytimeincreaseswiththedecisiontogofromEDMingtoblastingtoPCEing.Allthreetechniquescanprovidevaryingdegreesofmattefinishes.Themoredetailedfinishes,suchasfabricorweatheredwood,areavailableonlywithPCEing.Note:PCEisPhotoChemicalEtching,表面花紋Pattern,根據經驗法則，對母模側模壁(冷卻時，塑料從其離開)而言，每0.025mm咬花深度，單邊至少要有1.5脫模角。有些咬花供應商要求在公模側模壁(冷卻時，塑料向其包裹)，提供2倍的脫模角。安全的作法是避免在内面採用咬花。Theruleofthumb,appliedtothesidewallofcavitiesthatthematerialshrinksawayfromasitcools,isaminimumof1.5ofdraftpersideforeach0.025mm(0.001inch)oftexturedepth.Sometexturesuppliersaskfortwiceasmuchdraftoninsidesurfaces,thatthematerialshrinksontoasitcools.Asaferapproachistoavoidusingtextureoninsidesurfaces.,咬花Texture,設計者必須指出咬花從那裏開始，到那裏結束。一個好的咬花標註，應該指出花紋號碼、咬花深度、咬花位置，如果要更得當的話，還要加上花紋的方向。當一產品是由數件零件組合而成，一定要指出咬花花紋的方向。Thedesignermustindicatewherethetexturestopsandstarts.Agoodtexturingnoteshouldindicatethepatternnumber,depthoftexture,itslocation,and-ifappropriate-thedirectionofthepattern.Inthoseinstanceswhereseveralpartsfittogetherinoneproduct,thedirectionofthetexturepatternabsolutelymustbespecified.,咬花Texture,設計者完成產品設計之前，能做的最重要的單一事項，就是會同專業的咬花供應商作專案檢討。Thesinglemostimportantthingthatadesignercandotooptimizetheuseoftexturingistoreviewtheprojectwithaknowledgeabletexturesupplierbeforefinalizingthepartdesign.,咬花Texture,半結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方向有著不同的收縮率，而多了一層問題。這問題又因成型條件改變致使結晶度變化而更形複雜。如果塑料冷卻得慢，結晶度和收縮率都會增加。Thesemi-crystallineplasticshashighermoldshrinkagefactors.Thesematerialshavetheadditionalproblemofdifferentshrinkagefactorsparalleltoandperpendiculartothedirectionofmeltflow.Thisproblemisfurthercompoundedbyvariationsinthedegreeofcrystallinitycausedbychangesinmoldingconditions.Ifthematerialiscooledslowly,therewillbeanincreaseincrystallinityandmoldshrinkage.,收縮Shrinkage,非結晶塑料收縮率低，較易維持尺寸的複現性。發表的收縮率，是以3.175mm(0.125吋)的壁厚為準。Itiseasiertomaintaindimensionalreproducibilitywithlowmoldshrinkagefactoramorphousmaterials.Thepublishedmoldshrinkagedataisbasedonamoldedpartwitha3.175mm(0.125inch)wallthickness.,收縮Shrinkage,設計射出成型零件，當塑料收縮率高時，應試圖限制壁厚變化在10%之內。當塑料收縮率低時，許容壁厚變化在25%以內。Whiledesigninginjectionmoldedpartsinhighmoldshrinkagefactormaterials,thedesignershouldtrytolimitwallthicknessvariationsto10%.Theallowablewallthicknessvariationforthelowmoldshrinkagefactormaterialscanbeupto25%.,收縮Shrinkage,塑膠模具設計PlasticMouldDesign徐昌煜CharlesHsu,模具設計的優先順序PrioritiesofMouldDesign,澆注系統設計(FillingSystemDesign)排氣系統設計(VentingSystemDesign)冷卻系統設計(CoolingSystemDesign)脫模系統設計(EjectingSystemDesign),澆注系統設計FillingSystemDesign,徐昌煜CharlesHsu,澆注系統設計的優先順序PrioritiesofFillingSystemDesign,產品設計(PartDesign)型腔設計(CavityDesign)澆口設計(GateDesign)流道設計(RunnerDesign)豎澆道設計(SprueDesign)噴嘴設計(NozzleDesign),典型的澆注系統TypicalFillingSystem,每增加一個澆口，至少增加一條熔接線，同時增加一個澆口痕跡、增加流道的體積以及增加較多的積風。Everytimeonegateisadded,oneweldline,atleast,onegatemark,morerunnervolumeandmoreairtrapswillbeadded.在型腔能夠完滿充填的前提下，澆口數目是愈少愈好。Aslongasthecavityisabletobefilledappropriately,gatesarethelessthebetter.為了減少澆口數目，每一澆口應就塑流力所能及的流長/壁厚比之內，找出可以涵蓋最大零件面積的進澆位置。Inordertoreducethenumberofgates,eachgateshallbelocatedatwherethemeltisabletocovermaximumpartareabasedonthelargestmeltflowlength/thicknessratio.,澆口數目TheNumberofGates,熔膠波前推進Melt-FrontAdvancement,充填模式,積風和熔接線FillingPatterns,Air-TrapsandWeldLinesLocation,熔接線WeldLines,更改澆口位置以重新定位熔接線WeldLinesCanBeRelocatedByChangingGateLocation,典型對頭熔接線伸張強度保留值TypicalButtWeldTensileStrengthRetentionValues,熔接線冷料井WeldSlugWell,熔接線WeldLines,熔接線WeldLines,當波前相遇後，繼續一塊兒流動，如此產生的熔接線是動態的。這樣的線條也稱作熔合線。熔接線形成後，熔膠不再流動，如此產生的熔接線是靜態的或是對頭的。靜態的熔接線位於型腔的末端，一般比靠近澆口的動態的熔接線脆弱而且明顯。Whentheflowfrontsmeetandcontinuetoflowtogether,theresultingweldlineisreferredtoasdynamic.Thistypeofweldlineisalsocalledameldline.Weldlinesthatareformedwithnoadditionalmeltflowarereferredtoasstaticorbuttweldlines.Staticweldlineslocatedattheextremitiesofacavityarenormallyweakerandmoreobviousthandynamicweldlinesformedclosetoagate.,左邊澆口在這些窗葉的中央，產生了靜態的熔接線。Thegatelocatedontheleftsidecreatesstaticweldlinesinthemiddleoftheselouvers.,熔接線WeldLines,熔接線WeldLines,這一部分充填的產品，顯示了兩條靜態的熔接線，在外面二孔外產生；澆口位於產品上邊中央。Thispartiallyfilledpartshowstwostaticweldlinesbytheoutsideholes.Thegateislocatedatthecenterofthepart,nearthetop.,積風AirTraps,排氣Vent,流動平衡FlowBalance,熔膠波前於同一時間抵達型腔各末端。Meltfrontreachestheendsofcavityatthesametime.,洗衣機圈板,洗衣機圈板,冷氣通風飾罩-原始設計Air-conditionerGrille,Original,18gatespressure:76MPa,冷氣通風飾罩-更正設計Air-conditionerGrille,Revised,8gatespressure:75MPa,分析結果比較ComparisonofAnalysisResults,十二澆口設計12GateDesign,四澆口設計4GateDesign,電子零件置物箱四澆口和十二澆口設計比較表,論語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,一排支流道之不平衡充填UnbalancedFlowInABranch,一排支流道平衡後之充填BalancedFlowInABranch,128型腔模之不平衡充填UnbalancedFlowInA128CavityMould,128型腔模平衡後之充填BalancedFlowInA128CavityMould,Therunnersystemshowsthatwarmer,low-viscositymaterial(yellowandred)followstheinsidewallwhenthemeltsplitsatanintersection.,Melt”Flipper”,剪切速率ShearRate,剪切應力shearstress黏度viscosity剪切速率shearrate,剪切應力ShearStress,澆口種類GateTypes,導致平直製件的澆口設計GateDesignforFlatPart,澆口設計(減少滯流效應)GateDesigntoAvoidHesitation,0.94秒時，遲滯現象在1.2mm厚凸片處發生,幫浦零件(Part,Pump)塑料(Polymer):POM,公稱厚度3.2mm,沒有遲滯現象,幫浦零件(Part,Pump)塑料(Polymer):POM,澆口設計(避免凹陷和空洞)GateDesigntoAvoidSinkMarkfillingpattern,weldlinesandairtrapsarechanged.,多澆口設計Multi-gateDesign,閥式澆口ValveGate,矩形邊緣澆口設計RectangularEdgeGateDesign,扇形澆口設計FanGateDesign,重疊式澆口設計OverlapGateDesign,凸耳澆口設計TabGateDesign,針點澆口設計PinGateDesign,潛伏式澆口設計SubgateDesign,水力直徑HydraulicDiameter,Whereisthehydraulicdiameter水力直徑Aisthecross-sectionalareaoftheflow流路斷面積Pisthewettedperimeter濕周長,在不同剖面形狀，相同斷面積下之變化Variousrunnerprofiles,basedonthesamecross-sectionalarea,水力直徑HydraulicDiameter,流道尺寸設計(1)RunnerSizing(1),D:流道直徑(mm)runnerdiameterinmmW:下游塑膠重量(g)downstreamplasticweightL:流道長度(mm)runnerlengthinmm,流道尺寸設計(2)RunnerSizing(2),流道尺寸設計(3)RunnerSizing(3),流道尺寸設計(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，改良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.,冷料井設計ColdSlugWellDesign,冷料井設計ColdSlugWellDesign,冷料井設計ColdSlugWellDesign,澆道襯套尺寸SprueBushingSizing,噴嘴球頭和澆道襯套承窩半徑RadiusofNozzleHeadmaterialconstitutes6%andthemouldonly4%ofthecostofeachpart.Smallthin-wallpartstypicallybenefitfromimprovedcoolingmorethanthickparts.,冷卻設計CoolingDesign,典型的冷卻系統TypicalCoolingSystem,模溫調節機Temperaturecontrollingunit,軟管Hoses,冷卻迴路2CoolingCircuit2,冷卻迴路1CoolingCircuit1,泵Pump,收集歧管Collectionmanifold,供給歧管Supplymanifold,模具冷卻系統MouldCoolingSystem,冷卻孔道CoolingC