Hydraulic system of hydraulic die cushion of punching machine

The utility model relates to a hydraulic system of a punching machine hydraulic die cushion, which comprises an oil tank and a die cushion oil cylinder, a first oil pipe and a second oil pipe are respectively inserted on the oil tank, and one end of the first oil pipe and one end of the second oil pipe are both connected with the die cushion oil cylinder. A main motor pump station set, a first-stage one-way valve and a second-stage one-way valve are sequentially arranged on the first oil pipe in the direction from the oil tank to the die cushion oil cylinder, and a cooling device, a first one-way valve for backpressure and a high-pressure overflow valve are sequentially arranged on the second oil pipe in the direction from the oil tank to the die cushion oil cylinder. A connecting pipe is arranged on the second oil pipe and located between the first backpressure one-way valve and the cooling device, one end of the connecting pipe is connected with the first oil pipe, and the joint of the connecting pipe and t