| 摘要 |
PROBLEM TO BE SOLVED: To provide a shaft forming method, more concretely, a method for forming a hollow shaft projecting from a flat part integrally with the flat part by subjecting a metal plate to forging where a stepped shaft is formed on a metal plate by forging. SOLUTION: The method comprises: a preparation stage where a metal plate 10 is placed on a straight die 110 in which a hole 116 is formed; a first forging stage where a knockout 120 provided at the inside of the hole 116 in the straight die 110 is pushed into the hole 116 of the metal plate 10 by a straight punch 140 in a state of being confronted with the tip of the punch, and back pressure is applied to the metal plate 10, so as to roll the metal plate 10 to the side face of a shaft; a shaft inserting stage where an already formed first step shaft 14 is inserted into a stepped die 210 at which a small-diameter part is formed on the depth of the hole 216; and a stepping forging stage where, as the metal plate 10 inserted into the stepped hole 216 is further pushed into the small-diameter part by a stepped punch 240 having an outside diameter same as the inside diameter of the second step shaft 15 to be formed, in a state where the knockout 220 provided at the inside of the hole 216 is confronted with the tip of the stepped punch 240, back pressure is applied to the metal plate 10 by the knockout 220, thus the metal plate pushed against the tip of the stepped punch is rolled to the side face of the shaft. COPYRIGHT: (C)2007,JPO&INPIT
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