| 摘要 |
PURPOSE:To accurately manufacture a molded item having undercuts on its inner surface by a method wherein the positioning between a fixed mold and a movable mold is regulated by fitting a first projection to a first recess and the radial positioning of each split block is regulated by fitting a second projection to a second recess. CONSTITUTION:A convergent center core 12 and a plurality of split blocks 22, 24, 26 and 28, which regulate the inner peripheral surface with undercuts of a cavity 42, are equipped. A first projection 60, which extends axially, is provided at the tip face of the center core. A second projection 42, which extends axially, is provided at the tip face of each split block. In addition, in a mold on the side, on which neither center core not split blocks are provided, a first recess 62, to which the first projection is fitted, and a second recess 66, to which the second projection is fitted, are provided. The positioning between a fixed mold and a movable mold is regulated by fitting the first projection 60 to the first recess 62. The radial positioning of each split block is regulated by fitting the second projection 64 to the second recess 66. Accordingly, a molded item having undercuts can be accurately manufactured at low cost. |
