注射成型基本原理簡(jiǎn)介(important)

1、注射成型基本原理簡(jiǎn)介注射成型基本原理簡(jiǎn)介 注塑成型是一種注射兼模塑的成型的方法,又稱(chēng)注射成型.是塑料成型加工最普通也是最早的成型方法. 注塑過(guò)程包括預(yù)塑,計(jì)量,注射,充模,泠卻定型等過(guò)程,得到一定幾何形狀和精度的塑件制品. 注塑工藝參數(shù)的選擇和調(diào)整及原料,模具,設(shè)備對(duì)制品質(zhì)量將產(chǎn)生直接影響.目錄目錄n塑膠特性簡(jiǎn)介塑膠特性簡(jiǎn)介n成型基本原理成型基本原理n成型常見(jiàn)不良及分析成型常見(jiàn)不良及分析材料材料塑料塑料(高分子)熱固性熱固性熱塑性熱塑性工程通用無(wú)定型結(jié)晶性無(wú)定型結(jié)晶性PCABSMPPOPEIPPSPETPOM PAPMMAPSPVCPEPPInjection Molding Plastic塑料

2、類(lèi)型塑料類(lèi)型塑膠分子結(jié)構(gòu)塑膠分子結(jié)構(gòu)Injection Molding PlasticRaise Temperature of PolymerAdding heat increases space between molecular chainsbut crystalline structure prevents flow.Model of Crystalline PolymersRigid SolidSoft SolidFlows EasilyTGTMInjection Molding Process固態(tài)難於流動(dòng)較易流動(dòng)Injection Molding ProcessModel of Am

3、orphous PolymersAdding Heat Increases Space 外熱提供空間Between Molecular Chains 在分子鏈之間Raise Temperature of Polymer TGLocked 固態(tài)固態(tài)EntanglementsStiff Flow難于流動(dòng)難于流動(dòng)Easier Flow 較易流動(dòng)較易流動(dòng)Injection Molding VariablesMelt Temperature熔融溫度熔融溫度35302520151050.030.060.090.120.150.180.210.240Wall Thickness in Inches壁厚(In

4、)MeltFlow(in.)LEXAN?101550 deg F.101 600 deg. FIncreased Melt Temperature yields increased Flow.提高熔融溫度導(dǎo)致增加流動(dòng)However, Too High a Melt Temperature May Cause Degradation.但,過(guò)高熔融溫度造成降解Injection Molding MaterialThermoplastics and Degradation熱塑性塑料和降解熱塑性塑料和降解Degradation 降解降解TemperatureTime 時(shí)間時(shí)間Injection Mol

5、dingBarrel UnitThe Reciprocating Screw(Filling) ThroatHeating CoilsNozzleHopperBarrelForce, TorqueFrom Injection Unit料筒組件料筒組件回轉(zhuǎn)式螺桿回轉(zhuǎn)式螺桿噴嘴加熱料斗加料口料筒來(lái)自注塑單元的力和力矩計(jì)量區(qū)熔融區(qū)加料區(qū)Screw 螺桿Injection MoldingnBarrel UnitnThe Reciprocating ScrewScrew Rotation Feeds and ShearsMaterial Into a Melt. Melt Collects Into F

6、ront of Barrel, Forcing Screw BackShotRotation and Back Pressure出量通過(guò)螺桿回轉(zhuǎn)，熔體聚集于料筒前部，反作用力使螺桿后退?；剞D(zhuǎn)力矩和背壓熔化混合熔化混合Injection Molding EquipmentBarrel UnitThe Reciprocating ScrewShotInjection Pressure注射壓力注射壓力流動(dòng)射出流動(dòng)射出在一定壓力,速度下熔體從噴嘴 流道 澆口 型腔的充填成型過(guò)程Injection Flow 熔融流動(dòng)Injection Molding ProcessInjection Molding V

7、ariablesInjection Speed100010010100100010000LEXAN?141 644 deg FLEXAN?141 608 deg FLEXAN?141 572 deg FApparentViscosity(Pa/s)Shear Rate (1/s)Injection Speed affects the viscosity of the molten material.注射注射速度速度表觀粘度表觀粘度剪切速率剪切速率注射速度影響熔體粘度注射速度影響熔體粘度Injection Molding VariablesInjection Pressure ProfileHy

8、draulicPressureTimeFill TimeScrew Run TimeBack PressurePeak Injection PressurePressure Applied by Injection Ram to Force the Plastic From the Barrel to the Mold.注射壓力曲線注射壓力曲線注射壓力峰值注射壓力峰值液液壓壓壓壓力力填充時(shí)間壓縮保壓壓縮保壓保壓保壓Packing PressureCushion (35mm)緩沖墊緩沖墊Barrel UnitThe Reciprocating ScrewInjection Molding Equ

9、ipment模腔填滿(mǎn)塑膠后,繼續(xù)施加於模腔塑膠上的注射壓力.Injection Molding VariablesCushionCushion (35mm)Material remaining in barrel whenthe ejection phase is completed.注過(guò)程結(jié)束后，殘于料筒前注過(guò)程結(jié)束后，殘于料筒前端的熔體端的熔體The injection molding process should allow a cushion to provide sufficient packing pressure in the mold緩沖墊緩沖墊注過(guò)程必須要有緩沖墊以保證注過(guò)程

10、必須要有緩沖墊以保證有效的保壓有效的保壓緩沖墊緩沖墊 Injection Molding variablesBarrel UnitThe Reciprocating Screw 冷卻固化冷卻固化加料加料產(chǎn)品冷卻固化而脫模后又不致於發(fā)生變形.Injection Molding ProcessPart Cooling and SolidificationHot MeltCooled MoldSolid Part制件冷卻和固化制件冷卻和固化熱熔體溫度較低的模具固化的制件來(lái)源來(lái)源：機(jī)器機(jī)器 停機(jī)時(shí)間過(guò)長(zhǎng) 機(jī)器長(zhǎng)時(shí)間不用 未清干凈料筒 噴嘴/止逆閥不良 不合適螺桿類(lèi)型模具模具 在澆口和流道上有死角材料材

11、料塑膠粒中雜質(zhì)其它樹(shù)脂降解來(lái)自料筒壁面降解物次料/受污染原料其它其它生產(chǎn)/操作環(huán)境注塑加工參數(shù)黑點(diǎn)黑點(diǎn)(black points)Injection Molding Non Good Parts診斷診斷: 注射速度太快 澆口太小 澆口位置不當(dāng) 澆口太長(zhǎng) 模具過(guò)冷 料溫過(guò)低 噴嘴有滴垂噴射痕噴射痕(flow marks)是熔融材料流動(dòng)的痕跡,以澆口為中心而呈現(xiàn)的條紋模樣.Injection Molding Non Good Parts診斷診斷:產(chǎn)品脫模角度不夠模具排氣不良保壓過(guò)大頂針過(guò)少或太小頂針粘住制品頂針頂出力不平衡成型品脫模之際,因頂出銷(xiāo)的頂力或成型品倒鉤位之阻力,該部呈現(xiàn)白色痕跡.Inj

12、ection Molding Non Good Parts頂白頂白診斷診斷:不正確的進(jìn)料注射壓力和速度過(guò)低注射時(shí)間太短止回閥有問(wèn)題.模具排氣不良模溫過(guò)低料溫過(guò)低或料熔體粘度太高是熔融塑料未完全流遍成型空間(模穴的各個(gè)角落之現(xiàn)象.Injection Molding Non Good Parts充填不足充填不足(shot short)診斷診斷: 機(jī)器止回閥問(wèn)題 注射速度過(guò)快 背壓過(guò)大 模具排氣不良 模溫過(guò)高 摩擦燒焦 檢查澆口及主流道大小 塑膠原料降解成形品表面因材料過(guò)熱所致的變色及成型品的銳角部份或肋的前端等材料焦黑的現(xiàn)象.Injection Molding Non Good Parts燒焦燒焦(burn marks)診斷診斷:無(wú)足夠的材料或較厚肋注射壓力過(guò)低射膠時(shí)間太短機(jī)器融膠能力不足模溫太高澆口過(guò)小流道過(guò)長(zhǎng)產(chǎn)品肋/壁厚比不當(dāng)澆口位置不當(dāng)模具排氣不良成型品表面產(chǎn)生凹陷的現(xiàn)象. 是體積收縮所致,通常見(jiàn)於肉厚部分,肋或凸出的背面,直接澆口肉厚不均的部份.Injection Molding Non Good Parts收縮收縮(sink marks)診斷診斷:材料降解(料筒有熱點(diǎn), 材料在噴嘴處有死角)注射壓力或速度過(guò)低或過(guò)高背壓過(guò)低在澆口,機(jī)器噴嘴或熱流道摩擦燒焦料溫過(guò)高在塑膠粒中有污染過(guò)多水分銀條是在成型品表面或表面附近,沿材料流動(dòng)方向,呈現(xiàn)的銀白色條