Patent ID: 8375765

Claim:
A method for controlling a cylinder/piston unit of a counterforce ram in a fineblanking or stamping press having a press ram and said counterforce ram, the method synchronizing the cylinder/piston unit with the press ram in a manner for reducing a pressure peak occurring at impact between a tool of the fineblanking or stamping press and a workpiece during a fineblanking or stamping operation, wherein the tool comprises a die, and the press ram is driven mechanically or hydraulically, comprising: continuously maintaining, using a first accumulator, a cushion pressure applied to the cylinder/piston unit from a low-pressure source, wherein the cushion pressure is preadjustable; subjecting the cylinder/piston unit, using a second accumulator, to a displacement pressure from a connectable high-pressure source to vary pressure in the cylinder/piston unit between the cushion pressure and an increased pressure for performing fineblanking or stamping; setting the preadjustable cushion pressure by supplying first control hydraulic fluid to the first accumulator; setting the preadjustable displacement pressure, using a control unit, by supplying second control hydraulic fluid to the second accumulator; and regulating a pressure pulse, attributable to an impact between the tool and the workpiece, independently of a quantity of the second control hydraulic fluid being supplied to said second accumulator by discharging an amount of the second control hydraulic fluid in accordance with an amplitude of the pressure pulse into a second tank that is separate from a fluid source tank that supplies the second accumulator with the second control hydraulic fluid; and wherein a total pressure in the cylinder/piston unit is maintained during the fineblanking or stamping operation to be at least the cushion pressure, is increased above the cushion pressure for an impending impact between said tool and said workpiece, and is regulated at impact to reduce effects of said pressure peak on the workpiece; and wherein maintaining said cushion pressure during the fineblanking or stamping operation allows ejection of the counterforce ram to be synchronized with retraction of the press ram.