Patent ID: 8302517
Filing Date: 2012-11-06
Classification: B21D,Y10T

Abstract:
1. A punch press for punching a workpiece, comprising a press frame having a press bed for holding a lower die and a movably-mounted ram operatively connected to a drive device and carrying an upper die, a controllable supporting device configured to generate a variable force that is effective between the ram and the press bed, and a control unit which includes a reversing hydraulic valve and which is operatively associated with the supporting device to detect via a sensor device a measured ram position or a press angle that has a unique correlation with a ram position and that influences a supporting force exerted by the supporting device and acting between the ram and the workpiece as a function of the press angle or the measured ram position such that the supporting force is increased from a lower value to a higher value to allow a reversing operation of the hydraulic valve at a predetermined press angle just prior to a press angle at which a counterforce exerted by the workpiece during punching ceases.