| 摘要 |
A method of hydroforming work that allows obtaining of a hydroforming molded item of large tube expansion ratio and complex configuration and allows the working through a reduced number of working steps. The method of hydroforming work is includes fitting a metal tube to a split mold, clamping the mold and applying an internal pressure and a push force along the axis of the tube to the metal tube. In the first hydroforming step, the metal tube is expanded in one direction of a cross section of the metal tube so as to obtain an intermediate product that, in the entirety of a tube expanded area along the axis of the tube, has a circumferential length ranging from 90 to 100% of the circumferential length of a product configuration and that, in the above one direction, has a height greater than that of the product at at least a portion along the axis of the tube. Thereafter, in the second hydroforming step, the intermediate product is formed into the final product while reducing the height thereof in the above one direction in the entirety or a part along the axis of the tube. Further, in the event of a bent configuration, a bending step is implemented between the first hydroforming step and the second hydroforming step.
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