High-speed driving method of pressure cylinder

A high-speed driving method of a pressure cylinder including:

• a moving step of moving a piston to a target position by supplying and discharging compressed air to and from a head-side pressure chamber and a rod-side pressure chamber on opposite sides of the piston of the pressure cylinder by a head-side servo valve and a rod-side servo valve individually connected to the pressure chambers;
• a clamping step of bringing a pressure member at a tip end of a piston rod coupled to the piston in contact with a workpiece;
• and a pressing force applying step of pressing the workpiece with the pressure member,
• wherein, in the moving step, which of a head-side end and a rod-side end of the pressure cylinder the target position is closer is sensed, the pressure chamber on a side of the end far from the target position is pressure-controlled so that a pressure of the pressure chamber is maintained at a set value by the servo valve connected to the pressure chamber, and the pressure chamber on a side of the end close to the target position is positioning-controlled so as to stop the piston in the target position by controlling coming in and out of the compressed air by the servo valve connected to the pressure chamber,
• in the clamping step, control for allowing the pressure member to touch the workpiece softly by making an exhaust opening degree of the rod-side servo valve constant is carried out when a distance between the pressure member and the workpiece has become equal to or shorter than a certain distance, and
• in the pressing force applying step, both servo valves are controlled so that the pressure of the head-side pressure chamber becomes higher than the pressure of the rod-side pressure chamber by a set value.