Abstract: A die for drawing molded sheet metal parts has a bottom part of the die and a top part of the die. These parts are movably guided toward each other. One of these parts has a draw ring. The other part of the die has a sheet metal holder received on a plurality of hydraulically operating cylinders. There is a draw punch, which is enclosed by the sheet metal holder and is supported on at least one hydraulically operating cylinder. The punch is communicatively connected with at least one of the operating cylinders serving for the support of the sheet metal holder. The punch is acted upon by a hydraulic fluid displaced from this operating cylinder during the drawing process. Thus, the draw punch will move in the direction opposite to the movement of the sheet metal holder.

Abstract: The drawing tool comprises a hydraulic element for deriving from the movement of the blank holder a simultaneous, oppositely directed movement of the drawing punch. The hydraulic element comprises a centrally disposed working piston, an annular piston, which surrounds that working piston, and a cylinder, which surrounds the annular piston. The working piston and the annular piston are adapted to be supplied with pressure fluid from first and second cylinder chambers which are hydraulically separated from each other and which are adapted to communicate with each other under the control of at least two alternative flow paths, which differ in hydraulic design so that they cause pressure changes on different pressure levels to be effected in the second cylinder chamber. A pressure detector detects the pressure of the fluid in the cylinder chambers and enables an alternative flow path in response to a rise of the pressure above a predetermined limit.

Abstract: A hydraulic element including a working cylinder defining a cylinder chamber having an axis and containing hydraulic medium, a working piston movable in the cylinder chamber along the axis and having an interior end arranged to communicate with the hydraulic medium in the cylinder chamber, and an annular piston movable in the cylinder chamber, along the axis, and enclosing the working piston, the annular piston having an interior end communicating with the hydraulic medium in the cylinder chamber so that movement of one of the pistons in a first direction along the axis causes the other of the pistons to move in a second direction opposite to the first direction.

Abstract: A sheet metal tool as two relatively movable tool sections, one of which is rovided adjacent its sheet metal-shaping face with a sheet metal holder which is movable relative to that face. Also movable relative to that face is a pressure-distributing unit composed of two spaced parallel plates which are maintained at a predetermined distance by spacers, this unit serving as an abutment for the sheet metal holder.