사출성형에서 밸브 게이트를 이용한 충전 밸런스 개선에 관한 연구

Abstract

In injection molding, the hot runner system allows molten resin to circulate through the manifold and hot nozzles, maintaining a consistent resin temperature through electric heating. This results in lower pressure loss compared to cold runner systems and provides the advantage of flexible gate placement. In this study, the effects of delay times applied to two valve gates on flow patterns and weld line positions were investigated through both injection molding simulations and experimental validation. A hot runner mold equipped with two valve gates—designed specifically for molding automotive door grips—was used in the experiments. The location of the weld line varied significantly with the injection speed; at lower injection speeds, a more pronounced filling imbalance was observed between the left and right sides of the cavity. When the valve gate delay time was short, the weld line shifted toward the direction opposite to the gate with the applied delay. Conversely, when the delay time was long, the weld line moved toward the gate where the delay was applied. Injection molding experiments were conducted with varying valve gate delay times. The experimental results closely matched the simulation results in terms of flow patterns and weld line positions. These findings confirm that valve gate delay times can be determined analytically to achieve flow balance.