Abstract:

An emulated mold with a circular cavity was built for the better understanding of the melt flow behavior of water-assisted injection molding process.Tracer technique was used for showing the melt flow.The cavity was filled alternately with red and green polypropylene tablets.After the mold was heated to make these tablets melt completely, water was injected into the melt to fill the cavity.The melt flow patterns were visualized under high-pressure water.The results show that the instabilities of water penetration into the melt from the water injector are caused by the high-viscosity melt around the injector, the melt near the mold wall flows back during the primary penetration, and the back flows become weaker and weaker along the penetration direction of water.The melt shrinkage during the secondary penetration is an approximately linear decrease process, and the melt shear flow is weaker than that during the primary penetration.At the same time, the fountain flow may occur in the melt front of water.

Key words:

水辅助注塑, 示踪技术, 熔体流动, 流动痕迹

摘要：

构建了用于研究水辅助熔体充模的仿真模具，采用红色和绿色着色剂作为示踪剂，通过水辅助着色的聚丙烯（PP）熔体在柱状模腔里充模，获得了能够反映熔体流动痕迹的样品。通过观察流痕，对水作用下熔体的充模流动进行了研究。实验结果表明：在一次穿透中，与注水喷嘴接触的高黏度熔体造成水从喷嘴射入熔体的不稳定，水的穿透导致模壁附近熔体可能产生回流现象，回流沿水的穿透方向呈减弱趋势。在二次穿透中，水前缘熔体黏度和黏度分布对水的穿透影响较大，熔体体积的收缩是近似线性的减小过程，熔体的剪切流动弱于一次穿透。实验中还发现，水前缘的熔体也会产生“喷泉流”。

关键词:

水辅助注塑, 示踪技术, 熔体流动, 流动痕迹