基于不同材料特性的水辅注塑模拟

基于广义非牛顿流体本构方程,采用有限体积法,对不同类型材料(结晶型材料PE和非结晶型材料HIPS、ABS)的短射法水辅注塑成型进行了数值模拟研究。研究发现,结晶型材料PE因结晶导致的体积收缩性,使其水辅注塑制件的水穿透长度比其它两种非结晶材料更长。当冷却时间过长时,结晶型材料PE因结晶导致的内应力增加,使其水辅注塑制件的水穿透长度比其他两种非结晶材料更短。这3种材料在注水延迟时间或注射量增加的情况下,均不利于水穿透长度的增加。另外,结晶型材料PE比非结晶型材料HIPS和ABS更容易发生二次穿透现象,且当熔体经过一定时间冷却,黏度提高时,更容易发生该现象。

The Simulation Based on Different Material Properties at Water-Assisted Injection Molding

Based on generalized non-newtonian fluid constitutive equation,the finite volume method was used to simulate the short-shot water-assisted injection molding of different types of materials(crystallized material PE,non-crystallized HIPS and ABS).It was found that the volume shrinkage of crystalline material PE due to crystallization made the water penetration length longer than other two non-crystalline materials;when the cooling time was too long,the internal stress of crystallized material PE due to crystallization increased.The water penetration length was shorter than that of the other two non-crystalline materials;these three materials were not conducive to the increase of the water penetration length when the water injection delayed time or the injection amount was increased.In addition,the crystalline material PE was more likely to undergo secondary penetration than the non-crystalline materials HIPS and ABS,and was particularly likely to occur when the melt was cooled for a certain period of time.