| 摘要 |
The method comprises a first stage during which a blank holder (1) is brought into contact with the sheet (2), a second stage in which a pressurised fluid is fed by means of a first hydraulic circuit to the cavity (4) in a die (3) below the sheet and a third stage in which a punch (7) is displaced towards the sheet to deform it plastically through the combined action of the pressures generated by the punch and the fluid. In accordance with the invention the second pressurised fluid delivered from a second hydraulic circuit is caused to act on the upper surface (9) of at least a portion (10) of the sheet so as to balance out the pressures acting on the undersurface (11) of the said portion while the former is displaced towards the sheet. <IMAGE> |
