Abstract: A method for locally increasing pressing pressure on a press tool having an abutment surface for being clamped onto a clamping surface in a press comprises providing a power unit smaller than the abutment surface and having an internal space, positioning the power unit between the clamping surface and the abutment surface, pressing the clamping surface against the abutment surface, connecting the internal space to a source of pressurized hydraulic fluid, and supplying the pressurized hydraulic fluid to the internal space thereby causing the power unit to expand and to exert a local pressure on the abutment surface.

Abstract: An apparatus is provided for compensating for such deformations as occur in operation in first and second clamping surfaces intended for a tool in a press. The clamping surfaces are reciprocally moveable towards and away from one another in order to move a first and second part of the tool towards and away from one another, and the first and second tool parts have a first and second abutment surface for abutment against the first and second clamping surfaces and the deformations cause uneven pressure in at least one contact region between the tool and the clamping surfaces. According to the present invention, there is disposed, in at least one contact region between a clamping surface and an abutment surface, a power unit which, on activation, is operative to press, away from the clamping surface located in the contact region at least a part of the abutment surface of the tool located there.

Abstract: A method for locally increasing pressing pressure on a press tool having an abutment surface for being clamped onto a clamping surface in a press comprises providing a power unit smaller than the abutment surface and having an internal space, positioning the power unit between the clamping surface and the abutment surface, pressing the clamping surface against the abutment surface, connecting the internal space to a source of pressurized hydraulic fluid, and supplying the pressurized hydraulic fluid to the internal space thereby causing the power unit to expand and to exert a local pressure on the abutment surface.

Abstract: A hydraulic press for deep drawing has mutually reciprocating clamping rings (6, 13) for idly clamping a sheet metal blank (5) with a predetermined force. The clamping rings (6, 13) are operated each by their cylinder (9, 14). The press has a tool (4) for forming the sheet blank (5), and a power unit (10, 11, 16) for generating a relative movement between, on the one hand, the clamping rings (6, 13) and, on the other hand, the tool (4). During the forming phase, the working volumes of the cylinders (9, 14) are interconnected to a common volume to which there is further connected a pressure maintenance device wit a pressure sensor (22), a regulator valve (23) and a pump (28). The piston areas of the cylinders (9, 14) are suitably equal.