| 摘要 |
PURPOSE:To obtain a screw made of synthetic resin with sufficient strength by a method in which a projected part is provided on the molding face of a mold molding the end surface of the head of a screw so as to position it on the central axis of the stock, and the end of the stock is radially expanded by the projected part in the process of press, thereby molding the outer periphery of the head. CONSTITUTION:A conical projected part 13 is provided on the molding face molding the end surface of the head of a screw in the mold 12 molding the end of the head so as to position it on the central axis of the stock 3. If the stock 3 is pressed in the longitudinal direction by the ram 15 of a press, the product 16 molded with the thread 16a and the outer peripheral part 16b of a dish-like head is obtained. Then, the end of the stock 3 is radially expanded by the projected part 13, and long fibers 2 are forcedly pushed into the outer periphery 16b. Since the side of projected part 13 runs in parallel with the face 14 molding the outer peripheral surface of the head of the screw to be molded with a top force 10 and a bottom force 11, the long fibers 2 are distributed to lie in parallel with the outer peripheral surface of the head. A head-burying member 17 is pushed against the end surface of the head of a molded object 16 and is stuck thereto by using the mold 18 for molding the end surface of the head. |
