| 摘要 |
PURPOSE:To prevent a thickness flow of a base material in the pre-stage of a swell by constituting a die so that a base material holding part for contacting a base material part part which becomes a swell part of a final product and pressing it down is formed, before starting swell forming. CONSTITUTION:With regard to forming of a stepped shaft, etc., in the pre-stage for starting swell forming by a swell forming die part 3, a flat shape base material holding part is formed in advance by projecting a reference surface O of a die 1 so that a base material part S1 which becomes a swell part R of a product W adheres tightly to a roller die 1. In this regard, a height (h) of the holding part 5 is kept roughly constant between process (2)-(3), and thereafter, decreased gradually, and a groove continued to a width l1 of the holding part 5, namely, a width l2 of a groove 4 formed by a shaft part forming die part 2 and the die part 3 is brought close gradually to a swell width l3 of the product. In this way, a thickness flow of a base material in the pre-stage of a swell forming can be prevented, and a sufficient swell quantity is obtained. |
