Improving of Strength around Flow Front Meeting Area in Molded Products by Core Pin Driving Method inside Injection Mold

Abstract

Core pin driving method in the injection mold was proposed, in which core pins were installed in the runners located on both sides of the flow front meeting area, and internal melt flow was generated at the meeting part by the up-and-down movement of the core pins. In this paper, using a new mold in which the installation position of the core pin was changed inside the cavity, first, a simple method for estimating the internal melt flow caused by the drive of the core pin was proposed. Then, by this method, the internal melt flow, glass fiber orientation, tensile strength and fracture modes of the molded product were investigated. As a result, the area of flow front meeting face changes due to the forced melt flow driven by the core pin, and the area affects the joying strength of the meeting face, so that the tensile strength of the molded product changes. As described above, the molding phenomenon of the core pin driving method and the molded product characteristics were clarified.