注射成型基本原理簡介

1、注射成型基本原理簡介,注塑成型是一種注射兼模塑的成型的方法,又稱注射成型.是塑料成型加工最普通也是最早的成型方法. 注塑過程包括預(yù)塑,計(jì)量,注射,充模,泠卻定型等過程,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)備對制品質(zhì)量將產(chǎn)生直接影響.,前言,目錄,塑膠特性簡介成型基本原理成型常見不良及分析,材料,塑料(高分子),熱固性,熱塑性,工程,通用,無定型,結(jié)晶性,無定型,結(jié)晶性,

2、PCABSMPPOPEI,PPSPETPOM PA,,,,,,,,,,,,,,,,,,,,,PMMAPSPVC,PEPP,,,,,Injection Molding Plastic,塑料類型,塑膠分子結(jié)構(gòu),Injection Molding Plastic,,,,Raise Temperature of Polymer,Adding heat increases space between molecular chain

3、s,but crystalline structure prevents flow.,Model of Crystalline Polymers,Rigid Solid,Soft Solid,Flows Easily,T,G,T,M,Injection Molding Process,固態(tài),難於流動(dòng),較易流動(dòng),Injection Molding Process,,Model of Amorphous Polymers,Raise Tem

4、perature of Polymer,,,T,G,Locked 固態(tài)Entanglements,Stiff Flow難于流動(dòng),Easier Flow 較易流動(dòng),Injection Molding Variables,Melt Temperature熔融溫度,Increased Melt Temperature yields increased Flow.提高熔融溫度導(dǎo)致增加流動(dòng)However, Too High a Melt

5、 Temperature May Cause Degradation.但,過高熔融溫度造成降解,Injection Molding Material,Thermoplastics and Degradation熱塑性塑料和降解,Injection Molding,Barrel UnitThe Reciprocating Screw,(Filling) Throat,,Heating Coils,Nozzle,Hopper,Barre

6、l,Force, TorqueFrom Injection Unit,料筒組件回轉(zhuǎn)式螺桿,噴嘴,加熱,料斗,加料口,料筒,來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 Molding,,Barrel UnitThe Reciprocating Screw,Screw Rotation Feeds and ShearsMaterial Into a Melt. Melt

7、Collects Into Front of Barrel, Forcing Screw Back,Shot,,,Rotation and Back Pressure,,出量,通過螺桿回轉(zhuǎn)，熔體聚集于料筒前部，反作用力使螺桿后退。,回轉(zhuǎn)力矩和背壓,熔化混合,Injection Molding Equipment,,,,,,,,,,,,,,,Barrel UnitThe Reciprocating Screw,Shot,,,Inje

8、ction Pressure,注射壓力,,流動(dòng)射出,在一定壓力,速度下熔體從噴嘴 流道 澆口 型腔的充填成型過程,,,,Injection Flow 熔融流動(dòng),Injection Molding Process,Injection Molding Variables,Injection Speed,100010010,Injection Speed affects the viscosity of the

9、molten material.,注射速度,表觀粘度,剪切速率,注射速度影響熔體粘度,Injection Molding Variables,注射壓力曲線,注射壓力峰值,液壓壓力,填充時(shí)間,,,壓縮保壓,保壓,Packing Pressure,,Cushion (3~5mm),緩沖墊,,Barrel UnitThe Reciprocating Screw,Injection Molding Equipment,模腔填滿塑膠后,繼續(xù)施加

10、於模腔塑膠上的注射壓力.,Injection Molding Variables,Cushion,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,Cushion (3~5mm),Material remaining in barrel whenthe ejection phase is completed.注過程結(jié)束后，殘于料筒前端的熔體The injection molding process should all

11、ow a cushion to provide sufficient packing pressure in the mold,,緩沖墊,注過程必須要有緩沖墊以保證有效的保壓,緩沖墊,,,Injection Molding variables,Barrel UnitThe Reciprocating Screw,冷卻固化,,,加料,,,,,,,,,,,,,,,,,,,,,,,,,,,,,產(chǎn)品冷卻固化而脫模后又不致於發(fā)生變形.,Inje

12、ction Molding Process,Part Cooling and Solidification,Hot Melt,Cooled Mold,Solid Part,制件冷卻和固化,熱熔體,溫度較低的模具,固化的制件,來源：機(jī)器停機(jī)時(shí)間過長機(jī)器長時(shí)間不用未清干凈料筒噴嘴/止逆閥不良不合適螺桿類型模具在澆口和流道上有死角,材料塑膠粒中雜質(zhì)其它樹脂降解來自料筒壁面降解物次料/受污染原料其它生產(chǎn)/操作環(huán)境注

13、塑加工參數(shù),黑點(diǎn)(black points),Injection Molding Non Good Parts,診斷:注射速度太快澆口太小澆口位置不當(dāng)澆口太長模具過冷料溫過低噴嘴有滴垂,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:產(chǎn)品脫模角度不夠模具排氣不良保壓過大頂針過少或太小頂針粘住制品頂針頂出

14、力不平衡,成型品脫模之際,因頂出銷的頂力或成型品倒鉤位之阻力,該部呈現(xiàn)白色痕跡.,,,Injection Molding Non Good Parts,頂白,診斷:不正確的進(jìn)料注射壓力和速度過低注射時(shí)間太短止回閥有問題.模具排氣不良模溫過低料溫過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(shot short),診斷

15、:機(jī)器止回閥問題注射速度過快背壓過大模具排氣不良模溫過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(burn marks),診斷:無足夠的材料或較厚肋注射壓力過低射膠時(shí)間太短機(jī)器融膠能力不足模溫太高澆口過小流道過長產(chǎn)品肋/壁厚比不當(dāng)澆口位置不當(dāng)模具排氣不

16、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(sink marks),診斷:材料降解(料筒有熱點(diǎn), 材料在噴嘴處有死角)注射壓力或速度過低或過高背壓過低在澆口,機(jī)器噴嘴或熱流道摩擦燒焦料溫過高在塑膠粒中有污染過多水分,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)的銀白色條紋.,In

17、jection Molding Non Good Parts,銀條(sliver streaks),診斷:注射壓力太低塑化太快不正確進(jìn)料在料斗進(jìn)料中夾帶空氣模具排氣不良模溫過低熔料過熱止回閥功能不足夠,,熔融塑料中有水份,揮發(fā)性氣體於成型過程進(jìn)入成型品部而殘留的空洞現(xiàn)象.,Injection Molding Non Good Parts,氣泡(bubbles & voids),謝謝!!!,人有了知識，就會(huì)具備各種