プラスチック射出成形における反りとウェルドライン温度の多目的最適化

抄録

In plastic injection molding (PIM) is one of the most manufacturing process for producing plastic product. In PIM, warpage and weldline are major defects and they should be minimized for high product quality. Process parameters such as melt temperature, injection time, packing pressure and cooling time strongly affect product quality. It is important for minimizing warpage and weldline to determine the optimal process parameters. This study considers the box type product and proposes a method to determine the optimal process parameters for minimizing the warpage and maximizing the minimum weldline temperature. It is difficult to measure the length of weldline directly, and other method is needed to evaluate the weldline indirectly. The higher the minimum weldline temperature is, the shorter the length of weldline is. So, the minimum weldline temperature is maximized to minimize the length of the weldline. Numerical simulation in the PIM is so intensive that a sequential approximate optimization is used to identify the pareto-frontier. Through the numerical result, it is confirmed that there is trade-off relationship between the warpage and the minimum weldline temperature. In addition, it is identified that the melt temperature and the injection time have influence minimum weldline maximization and the packing pressure has influence warpage minimization.