다수 캐비티 사출금형에서의 균형 충전을 위한 러너 시스템 연구

Abstract

The injection mold with multi-cavity is essential for mass production of plastic products. Multi-cavity molds are designed to geometrically balanced runner system to uniformly fill to each cavity. However, despite geometrical balanced runner system, filling imbalances between cavity to cavity have always been observed in injection molding. These imbalances affect molded product quality such as part dimension, warpage, and strength as negative factor. To solve these problems, many studies such as Melt Flipper, RC Pin, and others have been presented. The results of these studies have been an effect on filling balances in multi-cavity molds. But, those have had a limitation that additional insert parts must have existed in the mold. In this study, the filling imbalance according to runner shapes by CAE analysis was investigated. And a new runner system is suggested for filling balance between cavity to cavity using "Melt-Buffer" with simple change of runner shape. A series of simulation to confirm feasibility of Melt-Buffer’s effects was conducted using injection molding CAE program. And a series of injection molding experiment was conducted using plastic materials such as ABS and PP. As results of this study, feasibilities of filling balances by Melt-Buffer were confirmed. Also, a closed-loop-control system is suggested for filling balance in hot-runner mold, and an experiment of this system was conducted.