Patent ID: 6920821

Claim:
A hydraulic press stop-control method, comprising: supplying hydraulic oil to one of a head-side cylinder chamber of a hydraulic oil cylinder and a rod-side cylinder chamber of the hydraulic oil cylinder by forward and reverse rotation of a two-way pump driven by a servo motor, to thereby move a ram vertically; pressurizing the hydraulic oil with a pressure, which does not exceed a pressure resulting from a weight of the ram, by the reverse rotation of the two-way pump; decreasing a pressure difference of the hydraulic oil between a rod-side cylinder chamber-side piping on a rod-side cylinder chamber-side of a speed switching valve and a two-way pump-side piping on a two-way pump side of the speed switching valve, the speed switching valve being provided along a piping connecting the two-way pump and a rod-side cylinder chamber of the hydraulic cylinder; stopping the ram at a predetermined position; and moving the ram vertically, and pressing a workpiece by cooperation between a punch and a die attached to the ram.