Patent ID: 8387524

Claim:
A method for locally increasing pressing pressure in a press tool having a first tool part clamped to a first clamping surface in a press and a second tool part clamped to a second clamping surface in the press, the method comprising: providing a power unit smaller than the first tool part, the first clamping surface larger than the first tool part and the second clamping surface larger than the second tool part, positioning the power unit between the first tool part and the first clamping surface so that said power unit is not in contact with a work piece during operation of said power unit and said power unit having an internal space, pressing said work piece between the first and second tool parts by activating press cylinders in the press, allowing a slide to be deformed under influence of pressure, connecting the internal space to a source of pressurized hydraulic fluid; and supplying said pressurized hydraulic fluid to the internal space thereby causing the power unit to expand to exert a local pressure on the first tool part to compensate for the deformation of the slide.