| 摘要 |
PURPOSE:To enable reduction of production cost by a large margin by cold casting a reguired form of torus which has a hole in the center and also shrinking the diameter of the hole to make the hole smaller. CONSTITUTION:As the first process, a torus 1 is formed with a comparatively large hole 2' in the center. As the second process, it is press molded by cold casting in metal molds 12, 13 and 14 to form a cylinder 1 which has a flange 3. At this time,the diameter of the hole 2 is shrunk and made smole hole 2. In the third process, the cylinder 1 and the flange 3 are press molded in cold casting by metal molds 15, 16 and 17 to form a stage 5 and a projection 6. In the fourth process, an edge 4 around the flange 3 is cut down by metal molds 18 and 19. |
