Optimization of valve gate timings of an automotive cowl top cover for minimizing cavity pressure

Abstract

When it comes to injection molding products, the effect of injection pressure generated in the injection molding process is of great significance. To enhance the quality products with energy consumption reduced, it is vital to minimize the pressure within a mold. Accordingly, this study suggests a method to control the pressure in a mold and minimize the max. pressure by means of a cowl top cover. To this end, an optimal design was implemented to minimize the max. pressure in a mold by controlling the melt temperature and mold temperature among process condition factors as well as the valve gate’s open time. For the injection analysis, Moldflow, a CAE program, was utilized. For automation of design, API functions of Moldflow and PIAnO(process integration, automation and optimization), a commercial PIDO(process integration and design optimization ) program, also were used. Each cycle of the cowl top cover filling analysis and packing analysis took 13 hours when a computer with CPU of X5690 3.47GHz and RAM of 96GB was used. The design involved such a large number of interpretations that the use of common optimal design procedures and algorithms to produce an optimum solution would take too much time and its efficiency would be unsatisfactory. To obtain optimal experiment results with the min. number of experiments, the design of experiments was utilized, and the kriging and meta-model were generated in reference to the relation between the design variables and reaction values in the experiment points of OA (orthogonal array). In addition, the evolutionary algorithm, a meta-model-based optimization algorithm, was utilized in combination with PIAnO. The result of the optimal design shows that when the meta-model was used in comparison with the max. pressure of the initial model with the aim to minimize the max. pressure in the mold, the pressure decreased as much as 20%, which demonstrates the validity of the suggested optimal design method that utilizes a meta-model