注塑充模过程中温度场的全三维数值模拟

Simulation of temperature field in filling stage of injection molding using three-dimensional model

注塑充填过程中,聚合物温度的变化直接影响到成型过程的各个方面,因此,对注塑流动过程中温度场的准确预测具有重要意义.采用有限元方法对注塑充填过程中温度场的三维数值分析进行了研究.没有采用传统的HeleShaw薄壁假设,而是全面考虑了对流项在各个方向的影响,提出了一种全三维的温度场计算的数学模型和数值实现方法.采用Galerkin法对能量方程进行了三维有限元离散,同时,为保证数值计算过程的稳定性,采用上风法来处理对流项和黏性热项.模型可预测非牛顿非等温流体在任意厚度型腔内流动时的温度场.和二维模型相比,它具有更加广泛的适用范围,计算结果也更准确.数值算例证明了给出的模型和算法的可靠性.

The variation of the temperature of polymer would have important influence on the injection molding process. So predicting exactly the temperature field during filling is very meaningful. 3D numerical analysis of temperature field in filling stage of injection molding is investigated with the FEM method. Without the use of the Hele-Shaw approximation, the three-dimensional theoretical model and numerical scheme for temperature field were established by considering the influence of convection items in three dimensions. The energy equation was discretized using the Galerkin method. In order to keep numerical stability, the upwind method was used to handle the convection item and viscous heat item. The temperature field of the non-Newtonian and nonisothermal fluid within cavities with arbitrary thickness could be pridicted with the model. A wider range of parts was possible and the prediction results were better than the 2D or 2.5D model. The validity of the model was tested through the analysis of two cavities.