| 摘要 |
PURPOSE: To improve reliability of an injection molding by providing at least one support portion protruding on an edge face of an injection-molding core brought into contact with an edge of a paper tube case, thereby preventing walls of the tube from suffering bending and deflecting. CONSTITUTION: At least one support portion 6 is provided in a shape protruding on an edge face 10 adjacent to a straight upper outer edge 11 of an injection- molding core 4. Thus, an edge 2 of a tubular paper core is supported in contact with the support portion 6. At the time of pushing and engaging the case to and with a mandrel, its part is projected into a cavity of the mold, and the part is supported from an outside by walls of an outward or outside mold member and supported from an inside by the support portion 6. And, a flat end face 17 of the portion 6 is formed in plane with an outer face 7 of the core 4, and connected to the outer face. Thus, the case is pushed and engaged to and with the core member 4 and pulled to be removed therefrom without any fault almost likewise without the portion 6 at all. |
