水辅成型中的穿透机理研究

Study for water penetrating mechanism in water-assisted injection molding

针对一次穿透理论在预测残余壁厚方面的局限,提出了厚度方向再穿透理论及算法。建立了量纲为一的黏性可压缩非牛顿熔体在水辅成型厚度方向再穿透中的控制方程,导出了求解压力场的变分方程和速度场的计算公式,用分部积分和力学基本原理建立了再穿透速度与注水压力、熔体密度、黏度、穿透长度、穿透半径之间的关系,并开发了模拟程序。实验结果表明应用厚度方向再穿透理论可以有效地提高水辅成型的预测精度。

The limitation of the first penetration theory on prediction of residual thickness in Water-assisted Injection Molding(WAIM) is invesigated and the theory of second penetration on thickness direction is proposed to solve the problem in this study.The governing equations for viscous compressible non-Newtonian melt during the second penetration of WAIM are established using dimensionless method.To get the numerical solution,the varational equation for pressure and a formula for velocity expressed by pressure gradient are derived with integration by parts.The relationship between the second penetrating velocity and water pressure,melt density,viscosity,penetrated length and penetrated radius is set up using integration by parts and mechanical principle.Finally,a program is developed to get the numerical solutions for pressure,temperature,velocity and residual thickness in WAIM.The experimental results show the second penetration theory and algorithm proposed in this paper can improve the simulating precision effectively.