Patent ID: 6799501
Filing Date: 2004-10-05
Classification: B23K,F15B

Abstract:
A high speed driving method of a pressure cylinder comprising:an advancing working step for driving a piston of a pressure cylinder by air pressure supplied and discharged from a servo valve to move a piston rod to a forward stroke end, to thereby pressurize a work to carry out a predetermined operation; an intermediate stopping step for retreating the piston rod to an intermediate stopping position and stopping the piston rod at the intermediate stopping position; and a speed reducing step for reducing a speed of the piston rod in a vicinity of the forward stroke end by a cushioning function generated by limiting a flow rate of exhaust gas from a rod-side pressure chamber, wherein the intermediate stopping step comprises: a process for detecting an operation position of the piston rod by a position detector and feeding back a detected position signal to a control apparatus of the servo valve; a process for controlling the servo valve by the control apparatus such that a deviation between the detected position signal and a set position signal for intermediate stopping of the piston rod becomes zero, thereby stopping the piston rod at a set position; and a process for maintaining a state in which substantially same pressures are supplied to pressure chambers on opposite sides of the piston; wherein during the speed reducing step, if an internal pressure in the rod-side pressure chamber at the time the cushioning effect function becomes less than an internal pressure in a head-side pressure chamber, actuation of a quick exhaust valve is triggered to directly open the rod-side pressure chamber into atmosphere, and to reduce a piston back pressure, to shorten a time until a maximum pressuring force is generated by the piston rod.