塑胶产品模具设计

第六章塑料产品与模具设计PlasticPartandMoldDesign浇注系统设计FillingSystemDesign模具设计的优先顺序PrioritiesofMoldDesign浇注系统设计(FillingSystemDesign)排气系统设计(VentingSystemDesign)冷却系统设计(CoolingSystemDesign)脱模系统设计(EjectingSystemDesign)浇注系统设计的优先顺序PrioritiesofFillingSystemDesign产品设计(PartDesign)型腔设计(CavityDesign)浇口设计(GateDesign)流道设计(RunnerDesign)竖浇道设计(SprueDesign)喷嘴设计(NozzleDesign)豎澆道Sprue主流道MainRunner成品Part澆口Gate冷料井ColdSlugWell支流道BranchRunner典型的浇注系统TypicalFillingSystem壁厚不均是注塑成形中最大的麻烦制造者。这对薄壁零件尤然。这些麻烦包括了迟滞现象、短射、凹陷、发赤、喷流、翘曲及长冷却时间等；目前都可用CAE以直接或间接的方式预测。Non-uniformwallthicknessisthebiggesttroublemakerinplasticinjectionmolding.Thisisespeciallytruetothin-wallpart.Thetroubles,includinghesitation,shortshot,sinkmark,blush,jetting,warpageandlongcoolingtimeetc.,canbepredicted,directlyorindirectly,byusingCAE.壁厚不均

Non-uniformWallThickness壁厚设计WallThicknessDesign差[Poor]较好[Better]最好[Best]掏空设计(1)CoringOutDesign(1)改进设计

[Improved]原设计

[Original]差[Poor]改进

[Improved]掏空设计(2)CoringOutDesign(2)气泡或/和凹陷的形成Voidor/andSinkMarkForming气泡

(Void)凹陷

(SinkMark)肋厚和内圆角半径的影响TheEffectofRibThickness&FilletRadius肋的底部厚度BottomThicknessofRibW0.5W2.5WW1.2WD1.5WD(A)(B)肋的设计(一)RibDesign(1)t =wallthichnessB=0.5tC =3tAAD=2BE=0.13mm(radius)F=1.5-2deg假如需要更大的強度,可增加肋的數目Ifmorestrengthisrequired,addadditionalribs.FBDECt

肋的设计(二)RibDesign(2)肋的设计(三)RibDesign(3)与侧壁相连之凸壳(热塑性塑料)BossatWall(Thermoplastics)A =凸壳附着处壁厚

wallthicknessB =凸壳外环直径

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'远离侧壁之凸壳(热塑性塑料)BossAwayFromWall(Thermoplastics)A =凸壳附着处壁厚

wallthicknessB =凸壳外环直径

(含底部修整圆弧半径)

dia.ofbossoverradiiC=0.5AD=2BE =1-2degF =0.13mm(radius)G=0.95DH=0.3Gmin.toGmax.I =0.5AHEFDFGCBAI外侧凸壳OutsideBoss

A'A'A(DIA)BB=AB=2A(max.)SectionA'-A'Where1/r :樑的曲率

curvatureofthebeamM :弯曲力矩

bendingmomentE :弹性模数

modulusofelasticityI :断面积对中立轴的惯性矩

momentofinertiaofthecross-sectionalareawithrespecttotheneutralaxisEI :翘曲刚性

flexuralrigidity挠曲刚性

FlexuralRigidityNeutralAxis?10.8平板和肋板的比较

ComparisonbetweenPlain&RibbedPlates和平板比，若基于相同的惯性矩(刚性)，肋板需料少了43%，I/A却增加了1.79倍。肋板的最大厚度减为平板的1/4，使得冷却时间骤降15/16(94%)。Basedonthesamemomentofinertia(stiffness),ribbedplateneeds43%lessmaterialbutboostI/Aby1.79timescomparingwithplaneplate.Themaximumthicknessofribbedplateisonly1/4ofplainplate＇s;showingadramaticcoolingtimereductionof94%(15/16).平板和肋板的比较

ComparisonbetweenPlain&RibbedPlatesAvarietyofmolded-ininterlockscanaddstiffnesstothin-wallhousingdesigns.各种一体成形的內锁件能增加薄壳的刚性。结构设计是薄壳成形零件的基础。Structuraldesignisthebaseofthin-wallmoldingparts.薄壳成形零件不仅仅是一趋势，而且也是降低成本和提高竞争力的有效途径。Thin-wallmoldingpartisnotonlyatrendbutalsoaneffectivewaytoachievecostreductionandcompetitivenessincrease.结构设计和薄壳成形零件StructuralDesign&Thin-wallMoldingParts每增加一个浇口，至少增加一条熔接线，同时增加一个浇口痕迹、增加流道的体积以及增加较多的积风。Everytimeonegateisadded,oneweldline,atleast,onegatemark,morerunnervolumeandmoreairtrapswillbeadded.在型腔能够完满充填的前提下，浇口数目是愈少愈好。Aslongasthecavityisabletobefilledappropriately,gatesarethelessthebetter.为了减少浇口数目，每一浇口应就塑流力所能及的流长/壁厚比之内，找出可以涵盖最大零件面积的进浇位置。Inordertoreducethenumberofgates,eachgateshallbelocatedatwherethemeltisabletocovermaximumpartareabasedonthelargestmeltflowlength/thicknessratio浇口数目TheNumberofGates熔胶波前推进Melt-FrontAdvancement充填方式,积风和熔接线FillingPatterns,Air-TrapsandWeldLinesLocation熔接线WeldLines材料[Material]:PC-GF50原设计[Original]更改设计[Revised]更改浇口位置以重新定位熔接线WeldLinesCanBeRelocatedByChangingGateLocation典型对头熔接线伸张强度保留值TypicalButtWeldTensileStrengthRetentionValues熔接线冷料井WeldSlugWell对头熔接线[Buttweld]熔接线冷料井[Weldslugwell]积风AirTraps排气Vent大部份热塑性塑料MostThermoplastics A0.08mm B3.18mm C12.7mm D0.25mm耐隆和聚缩醛(POM)NylonandAcetal(POM) A0.04mm B3.18mm C12.7mm D0.25mm进料流道FeedRunner塑料成品PlasticPartAD排气孔VentBSEC.A'-A'CA'A'充填均衡FlowBalance熔胶波前于同一时间抵达型腔各末端。Meltfrontreachestheendsofcavityatthesametime.原始设计OriginalDesign十二浇口设计12GateDesign电子零件置物箱材料Material：ABS四浇口设计4GateDesign修正設計RevisedDesign电子零件置物箱材料Material：ABS电子零件置物箱四浇口和十二浇口设计比较表剪切速率ShearRate剪切應力shearStress黏度viscosity剪切速率shearrate剪切应力ShearStress浇口种类GateTypes針點澆口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閥澆口ValveGate環狀澆口RingGate导致平直零件的浇口设计GateDesignforFlatPart中心浇口CenterGate扇形浇口FanGate最坏的Worst坏的Worse较好的Better最好的Best侧浇口EdgeGate薄模浇口FilmGate浇口设计(减少滞流效应)GateDesigntoAvoidHesitation澆口gate薄thin厚thick差的設計Poor好的設計Good薄thin厚thick澆口gate浇口设计(避免凹陷和气泡)GateDesigntoAvoidSinkMark&Void澆口gate澆口gate差的Poor好的Good使用重叠浇口以避免喷流AvoidJettingbyUsingOverlapGate差的Poor好的Good正确的浇口位置以避免喷流AvoidJettingbyLocatingGateCorrectly差的Poor好的Good使用凸片浇口以避免喷流AvoidJettingbyUsingTabGate使用适当的浇口形状以避免喷流AvoidJettingbyProfilingGateProperly差的Poor好的Good泵零件(Part,Pump)塑料(Polymer):POM进浇处(Polymerentrance)：浇口厚(Gatethickness)1.2mm，模穴厚(Cavitythickness)3.2mm问题(Problem)：喷流(Jetting)PoorDesignCausingJettingGatePart :Handle,RefrigeratorMaterial :ABSProblem :JettingMarkGasPin气辅成型冰箱把手浇口及气针入口浇口太小,导致喷流痕产生厚度差异过大,导致二次喷流痕产生R角过小,气体通路接近把手内侧,外侧則因体积收缩造成凹陷痕迹阀浇口ValveGate1.阀浇口梢

Valve-GatePin2. 加热管Heater3. O型环#610"0"Ring4. 流道歧管模板ManifoldPlate5. 轴封环

SealRetainer6. 套筒轴封

SleeveSeal7. 枕块SupportPillar8. 油压缸

HydraulicCylinder阀浇口(一)ValveGate(1)全部阀浇口同时打开时之充填状况Moldfillingwithallthevalvegates(shut-offgates)openedatthesametime.阀浇口(二)ValveGate(2)部份阀浇口推迟打开，改变充填方式Moldfillingwithdelayedvalvegateopening;fillingpattern,weldlinesandairtrapsarechanged.多浇口设计

Multi-GateDesign阀式浇口ValveGate矩形边缘浇口设计RectangularEdgeGateDesignL=0.5~0.75mmW=澆口寬度(mm)gatewidthinmmA=型腔表面積(mm

)surfaceareaofcavityinmmn=材料常數materialconstant0.6forPE,PS0.7forPOM,PC,PP0.8forCA,PMMA,PA0.9forPVC22h=nth=澆口厚度(gatethick.inmm)t=零件壁厚(wallthick.inmm)WtLh扇形浇口设计FanGateDesignL=1.3mmW=w=浇口宽度[mm]gatewidthinmmA=型腔表面积[mm]surfaceareaofcavityinmmn=材料常数[materialconstant]0.6forPE,PS0.7forPOM,PC,PP0.8forCA,PMMA,PA0.9forPVC浇口厚度[gatethick.inmm]t=零件壁厚[wallthick.inmm]

2

2

h1=nt

h2=wh1/D重叠式浇口设计OverlapGateDesignW=w=澆口寬度[mm]gatewidthinmmA=型腔表面積[mm]surfaceareaofcavityinmmn=材料常數[materialconstant]0.6forPE,PS0.7forPOM,PC,PP0.8forCA,PMMA,PA0.9forPVC澆口厚度[gatethick.inmm]=nt澆口長度[landlengthinmm]t=零件壁厚[wallthick.inmm]

2

2

L1=0.5~0.75L2=h+(w/2)凸耳浇口设计TabGateDesignL=0.5~0.75mmW=w=浇口宽度[mm]gatewidthinmmA=型腔表面积[mm]surfaceareaofcavityinmmn=材料常数[materialconstant]0.6forPE,PS0.7forPOM,PC,PP0.8forCA,PMMA,PA0.9forPVC浇口厚度[gatethick.inmm]t=零件壁厚[wallthick.inmm]

2

2

h1=nth2=0.9tL=0.5~0.75mmd=浇口直径(mm)gatediameterinmmt=零件壁厚(mm)wallthick.inmmA=型腔表面积(mm)surfaceareaofcavityinmmn =材料常数materialconstant0.6forPE,PS0.7forPOM,PC,PP0.8forCA,PMMA,PA0.9forPVC针点浇口设计PinGateDesigndLt潜伏式浇口设计SubgateDesignW=w=浇口宽度[mm]gatewidthinmmA=型腔表面积[mm]surfaceareaofcavityinmmn=材料常数[materialconstant]0.6forPE,PS0.7forPOM,PC,PP0.8forCA,PMMA,PA0.9forPVC浇口厚度[gatethick.inmm]=ntt=零件壁厚[wallthick.inmm]

230~15º~25º

2水力直径

HydraulicDiameterWhereDHisthehydraulicdiameter水力直径

Aisthecross-sectionalareaoftheflow流路断面积

Pisthewettedperimeter湿周长水力直径

HydraulicDiameter在不同剖面形状，相同断面积下之变化Variousrunnerprofiles,basedonthesamecross-sectionalarea流道尺寸设计(1)RunnerSizing(1)D :流道直径(mm) runnerdiameterinmmW :下游塑料重量(g) downstreamplasticweightL :流道长度(mm) runnerlengthinmm流道尺寸设计(2)RunnerSizing(2)流道尺寸设计(3)RunnerSizing(3)流道尺寸设计(4)RunnerSizing(4)流道尺寸设计(A1)RunnerSizing(A1)G :重量

weightS :零件厚度

thicknessD' :参考直径

referencediameterG(g)

D'(mm)forPS,ABS,SAN,CAB流道尺寸设计(A2)RunnerSizing(A2)

G(g)

D'(mm)forPE,PP,PA,POMG :重量

weightS :零件厚度

thicknessD' :参考直径

referencediameter流道尺寸设计(B)RunnerSizing(B)D':参考直径

referencediameterL :长度

lengthfL:长度系数

LengthcoefficientD :流道直径

runnerdiameterfLL(mm)D=D'‧fL冷料井设计ColdSlugWellDesign2d次流道Secondaryrunnerd主流道Primaryrunner澆口Gate型腔Cavity倒椎度冷料井竖浇道拉料杆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冷料井设计ColdSlugWellDesign浇道衬套尺寸SprueBushingSizing排气系统设计VentingSystemDesign为何排气仍然还是一个问题？Whyventingisstillaproblem?因为降低射速，让积风有较多的时间逃气，是一件太容易的事。但是…Becauseitistooeasytoslowdowntheinjectionspeedandgivethetrappedairmoretimetoescape.But...排气Vent射速一降，熔胶温度很快降低，射压必须提高，残余应力随之提高，翘曲的可能性增加。如果想藉提高料温，以降低射压，料温必须升得很高，这样又会引起塑料裂解。Wheninjectionspeedislower,melttemperaturegoesdownveryfast,injectionpressurehastobeincreased,residualstressisincreasedandthepossibilitygettingwarppagebecomeshigher.Ifonewouldliketoincreasebarreltemperaturetoreducetherequiredinjectionpressure,thebarreltemperaturehastobeincreasedtoaquitehighlevelandpolymerdegradationwouldbeinduced.排气Vent高料温和高射压都说明充填系统有了流动的问题Bothhighbarreltemperatureandhighinjectionpressureareindicationsofflowprobleminthefillingsystem.排气Vent我们常发现:射速提高时，塑料表现得更为出色。Itisquitecommonthatmaterialperformsbetterwhenitisinjectedfaster.最适化螺杆速度充分运用摩擦热，将塑流保持在最佳状态。许多充填和翘曲的问题也就迎刃而解。Anoptimizedramspeedprofilefullyusesthefrictionheattokeepthebestflowcharacteristics,whichcorrectsmanyofthefillandwarpageproblems.排气Vent有了适当的排气，射速可以提高，充填和保压可达良好状态，不须过度增加料管和喷嘴的温度。Withproperventing,theinjectionspeedcouldbeincreasedtoachievegoodfillandpackconditions,withouthavingtoraisethebarrelandnozzleheats,improperly.排气Vent深度(depth): 1.0.075mm易流塑料(easy-flowmat.) 2.0.125mm难流塑料(stiffer-flowmat.) 3.深度深到流道末端见毛边为准

(deepenoughtofeelflashatrunnerend)宽度(width):和流道同宽(aswideasrunnerdia.)排气唇部(ventlip):1.5mmA1抛光(finish)排气通道通大气(ventchanneltoatmosphere): 1mm深(deep)流道排气RunnerVents深度(depth):参照厂商建议(refertomanufacturer’srecommendation)宽度(width):全圆周长(wholeperimeter)or5mm长度(length):1.5mmA1抛光(finish)排气通道通大气(ventchanneltoatmosphere):1mm深(deep)分模面排气PartingLineVents深度(depth):参照厂商建议(refertomanufacturer’srecommendation)宽度(width):全圆周长(wholeperimeter)长度(length):1.5mm排气沟(ventgroove):1mm深(deep)顶出销或心型销排气EjectorandCorePinVents冷却系统设计CoolingSystemDesign模具冷却设计的目的PurposesofMoldCoolingDesign1.均衡冷却(改良产品品质) EvenCooling(ImprovePartQuality)2.有效冷却 (提高生产力) EfficientCooling(IncreaseProductivity)薄壳产品不像传统壁厚者一般可以承受较大的因热传不均而产生的残余应力。为了将收缩弯翘控制在可以接受的程度，均衡的冷却设计变得非常重要。Thin-wallpartcannotaffordasmuchthermalinducedresidualstressastheconventionalonedoes.Anevencoolingdesignbecomesveryimportanttocontroltheshrinkageandwarpageatanacceptablelevel.冷却设计

CoolingDesign射出成型周期时间InjectionMoldingCycleTime充填时间FillTime开模时间OpenTime后充填时间Post-fillTime对冰箱水果蔬菜盘之类的大零件而言，材料往往占成本50%以上。对小而薄的零件而言，成形机费用可占成本的90%，材料6%，而模具只占4%。小而薄的产品较之厚者更能从冷却的改善而获得效益。Forlargermoldedparts,materialtypicallyrepresentsmorethan50%ofthepartcostforarefrigeratorcrispertray.Inthecaseofathin-wallsmallpart,thepresscostcouldbe90%ofthecostofthepart;materialconstitutes6%andthemoldonly4%ofthecostofeachpart.Smallthin-wallpartstypicallybenefitfromimprovedcoolingmorethanthickparts.冷却设计

CoolingDesign典型的冷却系统TypicalCoolingSystem模温调节机Temperaturecontrollingunit软管Hoses冷却回路2CoolingCircuit2冷却回路1CoolingCircuit1泵Pump收集歧管Collectionmanifold供给歧管Supplymanifold模具冷却管路

MoldSchematic冷却孔道CoolingChannels入口Inlet出口Outlet入口Inlet出口Outlet喷泉管Bubbler障板管Baffle热管HeatPipe蒸发部位热输入HeatIn凝结部位热输出HeatOut液体Liquid蒸汽Vapor灯心(毛细管)Wick(Capillary)热管的应用TheApplicationOfHeatPipe理论上最短冷却时间Min.PossibleCoolingTime理论上最短冷却时间themin.possiblecoolingtime产品最大厚度themax.partthickness熔胶的热扩散度thermaldiffusivityofthemelt射出温injectiontemp.冷却液温度coolanttemp.顶出温度ejectiontemp.冷却时间和厚度分布CoolingTimeandThicknessProfile差的设计BadDesign好的设计GoodDesign冷却孔道直径、深度和节距建议值RecommendedDiameter,Depth&PitchD:直径为10至14mmDiameterofCoolingChannel,10to14mmd:深度为D至3D