Abstract: A press frame has an upper frame member, a lower frame member, a platen having a tool mounted thereon and disposed at the lower frame member, a working piston-and-cylinder unit disposed at the upper frame member and centered on an upright axis, the piston of the working piston-and-cylinder unit being displaceable and formed with a chamber in alignment with the platen and adapted to receive the tool, an elastomeric pad disposed in the chamber for evenly distributing pressing forces acting on a workpiece on the tool upon the supply of a hydraulic medium under pressure to the piston, whereby an outward force from the chamber is applied to the piston, with means forming a ring space between the piston and cylinder of the working unit at least in part peripherally surrounding the chamber, and means for supplying the ring space with the pressurized hydraulic medium, whereby a pressing force is applied to the piston to counterbalance the outward force.

Abstract: A sheet-metal workpiece is clamped in a bending press with its one side lying on a pair of bending beams spaced apart in a transport direction and with a bending roller pressing in a bending direction transverse to the transport direction against the other side of the workpiece between the beams. A first feeler roller is pressed against the one side of the workpiece at the first location opposite the bending roller with a force sufficient to relieve substantially all of the elastic deformation in the workpiece. The workpiece is contacted to each side of the first feeler roller with second and third feeler rollers spaced apart in the transport direction and the spacing between the first feeler roller and the second and third feeler rollers in the bending direction is then measured to ascertain the permanent bend (plastic deformation) of the workpiece.