PRESS WITH HYDRAULIC CONTROL SYSTEM

摘要

A press for forming sheet material into a shaped article comprising a frame, first and second complementary dies, a cam supported by the frame for reciprocally moving the first die along an axis between a first position axially spaced from the second die and a second position fully mated with the second die, the cam including a dwell period when the first die is in the second position. The press includes a bolster supporting the second die for axial movement between upper and lower limits, the bolster being axially spaced from the upper limit by movement of the first die to the second position. The press also includes a hydraulic power circuit responsive to the position of the cam for normally biasing the bolster toward its upper limit under a first hydraulic pressure and for biasing the bolster toward the upper limit under a second hydraulic pressure during the dwell period, the second hydraulic pressure being greater than the first hydraulic pressure.