塑料件注塑基本知識(shí)

塑料的分類熱固性酚醛樹脂氨基塑料有機(jī)硅塑料硅酮塑料環(huán)氧樹脂熱塑性GeneralpurposeABS,PP,PE…..EngineeringPC,PC+ABS,PBT,PET,Nylon….ReinforcedFiber,Mineral…..熱固性塑料的填料粉狀填料滑石粉,云母粉,石英粉流動(dòng)好,比容小,塑料性脆,成型壓力小.木粉流動(dòng)好,比容小,易吸濕.熱固性塑料的填料纖維填料棉纖維,石纖維,碎布纖維…….流動(dòng)性差,比容大,易吸濕,成型壓力大,強(qiáng)度好.填充性不良,易熔接不良.玻璃纖維流動(dòng)性差,方向明顯.比容大,裝模不便,模具磨損大.加壓時(shí)機(jī):過早,填料與樹脂分離,溢料多.過晚易發(fā)生填充不足.熱塑性塑料成形收縮率塑料粒子分子量大小,結(jié)晶/非結(jié)晶.塑件結(jié)構(gòu)嵌件布局/數(shù)量,料流方向料流方向大，垂直小玻纖增強(qiáng)：料流方向小，垂直大澆口形式,尺寸,分布成型條件熱塑性塑料流動(dòng)性好分子量大小:分子量小,分子量分布寛.分子結(jié)構(gòu)規(guī)整性差熔融指數(shù)高表現(xiàn)粘度小流動(dòng)比大.熱塑性塑料結(jié)晶性結(jié)晶型壁薄,冷卻快,結(jié)晶低,收縮小,透明度高各向異性,內(nèi)應(yīng)力大.易變形,翹曲非結(jié)晶型熱塑性塑料熱敏性及水敏性熱敏性:料溫高,易變色,易降解,對(duì)模具的腐蝕大.水敏性:在有水的情況下,在高溫,高壓下會(huì)降解.熱塑性塑料吸濕性吸濕,粘附水份不易吸濕,粘附水份水解使樹脂起泡,流動(dòng)性下降,外觀及機(jī)電性能不良.塑件設(shè)計(jì)脫模斜度精度高,取小值較高,較大的尺寸,取小值形狀復(fù)雜不易脫模取大值收縮率大的取大值壁厚較厚者取大值型心面比型腔面小.增強(qiáng)塑料宜取大,自潤(rùn)材料可取小.塑件的壁厚壁厚均勻原則壁厚越厚,流程越長(zhǎng)壁厚決定塑件的使用性能:強(qiáng)度,電氣性能,尺寸穩(wěn)定性裝配壁厚一般為1~6mm,常用2~3mm避免翹曲變形的設(shè)計(jì)保持壁厚均勻檢查相交部分逐漸改變壁厚加強(qiáng)筋加強(qiáng)筋的厚度必須小于相連接的壁厚網(wǎng)格式加強(qiáng)筋須低于四周的高度.有可能的情況下,螺絲柱需與本體連接.支承面小支承面的配合優(yōu)于大支承面以螺絲柱部位可得到高強(qiáng)度的可靠裝配．圓角和孔連接處以圓角過渡：減小應(yīng)力，改善流動(dòng)，提高強(qiáng)度：0.5~1mm孔間距不宜太?。河瞄L(zhǎng)圓孔加凸臺(tái)．螺釘孔加倒角以容屑．鉸鏈鉸鏈的截面不易過長(zhǎng)壁厚減薄過渡處以圓弧過渡壁厚一般為0.2~0.4mm材料：ＰＰ注：融體流向必須是通過鉸鏈部分，使其線性分子延主鏈折彎．塑件的尺寸精度影響因素成型材料成型條件塑件形狀模具結(jié)構(gòu)：Gate,Flow,Direction,Parting,Tooling存放條件塑料機(jī)的發(fā)展開煉機(jī)和壓延機(jī)螺桿擠出機(jī)(十九世紀(jì)后期)柱塞式注射成型機(jī)(二十世紀(jì)初)線式螺桿注射機(jī)(1956年)塑機(jī)的分類混煉機(jī)械捏合，開煉，密煉機(jī)壓鑄機(jī)擠出機(jī)注射機(jī)壓延機(jī)：人造革，塑料薄膜等吸塑機(jī)吹塑機(jī)注射機(jī)的結(jié)構(gòu)組成注射裝置塑化部件：螺桿，料筒和噴嘴料斗，計(jì)量裝置，傳動(dòng)裝置，注射和移動(dòng)油缸合模裝置前后固定模板，移動(dòng)模板，連接前后固定板用拉桿，合模油缸，移動(dòng)油缸，連桿機(jī)構(gòu)，調(diào)模裝置，頂出裝置．注射成型過程FillInjectionPackInjectionHoldScrewReturnDecompressionCoolingTimeMoldOpenEjectorForwardEjectorBackMoldCloses注射機(jī)的基本參數(shù)公稱注射量注射壓力注射速率塑化能力鎖模力合模裝置的基本尺寸模板尺寸，拉桿空間，模板最大開距，動(dòng)模板的行程，模具最大／小厚度注射模分類單分型面注射模具雙分型面注射模具帶有活動(dòng)鑲件的注射模具橫向分型軸芯注射模具自動(dòng)卸螺紋模具定模頂出模具無流道模具（熱流道，絕熱流道）單分型面注射模具雙分型面注射模具注射模典型結(jié)構(gòu)成型零部件澆注系統(tǒng)導(dǎo)向部分分型抽芯機(jī)構(gòu)頂出裝置冷卻，加熱系統(tǒng)排氣系統(tǒng)LeaderPinClampingPlateStationaryHalfMoveableHalfEjectorPlateCavitySprueBushingThepathwayformaterialtofollowtogetfromtheinjectionnozzletothemoldcavity.Comprisedof:SprueRunnerGateRunnerSystemUseBalancedRunnerSystemsDiameter(min)vs.Length(max) 3/16”=6”long 5/16”=12”long 3/8”=15”longRunnersUnbalancedBalancedColdwellTrapscoldslugsformedattipofinjectionnozzleKeepsslugsfromenteringmoldColdwellRunnersFullRoundModifiedTrapezoidalTrapezoidalHalfRoundArunnerisonlyasefficientasthelargestfullroundrunnerdrawninit’scrosssectionSprueBushingsSizingDraft(1.5°-3.5°PerSide)Pullers&ColdwellAspruebushingistheentryportforinjectingresinintothemoldUndercutRingBallPullerZPullerReverseTaperDesignedtopullthespruefromthespruebushingwhenthemoldisopenedSpruePuller澆口設(shè)計(jì)流動(dòng)的分布需均勻開在最厚的部分，以便保持最大的保壓澆口應(yīng)設(shè)計(jì)到熔體最后冷卻的地方注意玻纖排列方向的影響澆口的類型針點(diǎn)式澆口潛伏式澆口邊緣澆口扇形澆口平縫式澆口（薄片澆口）圓環(huán)形澆口澆口的類型輪輻式澆口爪澆口護(hù)耳式澆口直澆口澆口的類型Tunnel/SubEdgePinpointHotManifoldsHotManifoldsHotmanifoldssystems:ProvidesheatedpassagetomoldcavityAllows15%to20%fastercyclesEliminatessprue&runnerscrapImprovespartqualityReducesmolded-instressExternallyHeatedManifoldAIRGAPINSULATESMANIFOLDFROMPLATESUNIFORMTEMPERATUREALONGMELTCHANNELEXTERNALLYHEATEDUNRESTRICTEDFLOWLESSPRESSUREDROPEASIERMAINTENANCECourtesyofHot

ManifoldsHeaterProbeMeltChannelCoolingPlugLocatorRingHeaterManifoldPocketMeltChannelHeaterCoolingINTERNALLYHEATEDEXTERNALLYHEATEDHotManifoldsExternallyheatedhotrunnersystemsarerecommended:ReducepressuredropReduceshearandthermalhistoryPreventburnandbrownstreaksEasechangesincolorormaterialFacilitatepurgingValve-GatedHotManifoldsCYLINDERPISTONVALVEPINSPRUEBUSHINGMANIFOLDINSULATORINSULATINGAIRGAPNOZZLEHOUSINGNOZZLETIPNOZZLEHEATERMANIFOLDPLATECAVITYPLATEHotManifoldsManifoldsizingStreamliningTipdesignStand-offs/insulationControlsHotManifoldsBALANCEDMANIFOLDUNBALANCEDMANIFOLD分型抽芯機(jī)構(gòu)手動(dòng)側(cè)向分型抽芯機(jī)動(dòng)側(cè)向分型抽芯彈簧，斜導(dǎo)柱，彎銷，斜導(dǎo)槽，鍥塊，斜滑塊液壓／氣動(dòng)側(cè)向分型抽芯分型抽芯機(jī)構(gòu)模具模擬動(dòng)畫八

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分型抽芯機(jī)構(gòu)Cooling/HeatingWateristypicallyusedtoheatorcoolmoldUniformmoldtemperatureiscriticalto:Cycletime -WarpagecontrolShrinkage -DimensionalcontrolSurfaceappearance -StresscontrolCrystallinity -SinksandvoidsWeldlines -BlushGlass/mineral -JettingColdflowPlanWaterFirstWhenDesigningMold

Cooling/HeatingSomecriticaldetails:Depth/pitch/diameterTurbulentflowMTLsofconstructionDesignWaterChannelsVentingUnfilledproducts.0005”-.001”FilledProducts .001”-.002”

(over10%)

D1TheroutebywhichairisallowedtoescapefromthecavityPartingLineVentD1OtherVentingTechniquesPin“flats”ContinuousventBladesPorousmetalVacuumOverflowMoldSurfaceEjectorPinPinVentingEjectionBladesPinsLiftersStripperringsSleevesDraftDraftallowseasierpartejectionfromtoolingConventional:1°persideWithtexture:(1°+1.5°per.001”depth)NodraftDraftDrawDirectionToolingMetalSelectionMaterialTypeHomopolymersandUnfilledCopolymersReinforcedMaterial

SteelTypeP20S7H13420ToolSteelCharacteristicsMediumAlloyMoldSteelShockresistingtoolsteelHotworktoolsteel(Crbased)StainlesssteelTypicalHardnessasFinished(RockwellC)30-36Rc54-56Rc50-52