| 摘要 |
PROBLEM TO BE SOLVED: To provide a molding method of a ring shape product for precisely molding a through hole and a concave or convex part adjacent to the through hole. SOLUTION: A material W0 is pressed in an axial line direction for molding a large diameter convex part 5 protruding circularly at peripheral vicinity of one end part in an axial direction, a large concave tank 6 hollowed roundly in its inner peripheral side, and, a central bottom part 7 protruding at a central vicinity of the other end part, so as to form a preparative molding W1. The molding W1 is further pressed in an axial direction for molding a circular small diameter convex part 8 being protruded in the same direction of the large diameter convex part 5 at a central side of the convex part 5. Also, a small concave tank 9 circularly hollowed at its inner peripheral side is molded so as to form an intermediate molding W2 for being injected into a die curving space of a bottom die. An upper die is descended so that a work weight abuts the intermediate molding W2 for holding the intermediate molding and for having a punch punching through a central vicinity of the central bottom part 7 of the molding W2. Under this condition, the molding W2 is pressed between the ring punch being further descended and the die so as to mold a ring shape product W3 by finishing an outer surface, including a concave part 11 being adjacent to a through hole 10.
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