工艺参数对水辅助熔体充模流动的影响

摘要

The melt flow patterns were obtained by using an emulated mold and tracer technique. The effects of water-assisted injection molding conditions on melt flow were investigated based on the patterns. The results showed that the longer the water injection delay time, the nearer the back flow to the water channel, the narrower the melt flow under a strong shear force in the water channel. At a low melt temperature, the melt near the mold wall was hard to flow. A higher melt temperature increased the bubbles in the melt near the water injector, and resulted in a thicker back flow layer. When water pressure was higher, the force that water dragged the melt was stronger, and back flow disappeared in the melt flow field. When water pressure was lower, the melt near the water channel was subjected to a stronger shear force. The high viscous resistance around the water injector was much greater than the resistance resulting from increasing short shot size.%基于水辅助注塑仿真模具,采用示踪技术,对不同注水延迟时间、注水压力、熔体温度和熔体填充量下的水辅助充模的熔体流痕进行了考察,研究了工艺参数对熔体流动的影响.实验结果表明:随着注水延迟时间的增加,一次穿透中的回流区域呈向水道边靠近的趋势,随水流动的熔体减少,受强剪切作用的熔体区域在水道边变窄.熔体温度低,模壁附近的高黏度熔体流动性差.增高熔体温度,水更容易穿人熔体,注水喷嘴附近熔体中的泡孔增多,回流层增加.当注水压力高到一定值后,水对熔体的拖动足以克服熔体阻力对流动的影响,回流消失,水的穿透作用明显.注水压力低时,靠近水道的熔体受到的剪切作用大.与喷嘴接触的高黏度熔体形成的流阻远大于增加熔体量形成的流阻.