注水速度对水辅共注成型的影响仿真及分析

Simulation and Analysis on the Influence of Water Injection Rate to Water-assisted Co-injection Molding

基于现有的熔体共注成型层流填充模型,熔体采用Cross-WLF模型,在水相填充时引入非定常流场模型和湍流模型,构建了水辅共注过程中水相湍流形态的理论模型以及数学模型。对水辅共注成型的整个填充过程采用有限体积法进行数值模拟,不对熔体厚度进行人为的设定并且不忽略皮层熔体前沿"喷泉"效应,研究了注水速度对产品形貌的影响。模拟结果显示,增加注水速度会使水相的穿透深度和熔体的残留壁厚减小,并且产品的中空成型率也会随之增大。

By combining laminar model for melts flow with turbulence model for water flow, the melts are described by the Cross-WLF model, a reasonable numerical model was set up to describe the fluids flow behaviors during the filling stage of water assisted-co-injection molding process. The fountain effect at the melt advancing front was taken into consideration and finite volume method was adopted to realize the numerical simulation. Then the influence of water injection speed on the distributions of different materials was investigated. The result showed that a higher water injection speed lead to a shorter water penetration length, thinner residual wall thickness of melts and a higher hollow forming rate.