BREAKTHROUGH SHOCK ABSORBER

PROBLEM TO BE SOLVED: To shorten a series of working time for performing punching work to a lot of works W while contriving the simplification of the constitution of a breakthrough shock absorber 63 and the reduction of the manufacturing cost of the breakthrough shock absorber 63. SOLUTION: The breakthrough shock absorber is provided with shock absorbing cylinders 65 arranged on a bolster 13, shock absorbing rods 69 arranged on a slide 15, a pair of shock absorbing circuits 71, 73 for respectively connecting the hydraulic oil chambers 67 of the shock absorbing cylinders 65 to a tank 31, a stop/allowance switching valves 75 which are arranged on the way of the shock absorbing circuit 71 on one side and with which the stop state where the flow of hydraulic oil to the side of the tank 31 is stopped and/or the allowance state where the flow of the hydraulic oil to the side of the tank 31 is allowed and a flow rate control valve 81 which is arranged on the way of the other shock absorbing circuit 73 and with which the flow of the large flow rate of the hydraulic oil to the side of the tank 31 is controlled. COPYRIGHT: (C)2004,JPO&NCIPI