| 摘要 |
The die cushion is composed of a plurality of hydraulic units, each possessing at least one sheet-metal-holding cylinder acted upon by flowing pressure medium, and at least one forming cylinder for supporting a movable forming contour. The sheet-metal-holding cylinder and forming cylinders of each hydraulic unit are flow-connected to one another via a flow path and form a closed-hydraulic system, at least until a predetermined pressure level is reached. During the descent of the sheet-metal-holding cylinders, the flowing pressure medium displaced from the latter acts upon the forming cylinders and drives in the forming direction forming plungers accommodated axially movably in said forming cylinders. Accordingly, the realizable forming distances are split up into partial distances which, on the one hand, are to be covered by the forming plungers of the forming cylinders and, on the other hand, are to be effected by plungers accommodated in the sheet-metal holding cylinders. The required sheet-metal-holding force is in this case used as the driving force for the forming plungers.
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