The driving system of hydraulic press mainly has two types: pump direct drive and pump-accumulator drive. The pump directly drives the pump of this drive system to provide high-pressure working fluid to the hydraulic cylinder, the distribution valve is used to change the direction of the liquid supply, and the overflow valve is used to adjust the limited pressure of the system, and at the same time plays a role of safety overflow. This kind of drive system has few links and simple structure. The pressure can be automatically increased or decreased according to the required working force, reducing electric energy consumption, but the capacity of the pump and its driving motor must be determined by the maximum working force and maximum working speed of the hydraulic machine. This type of drive system is mostly used in small and medium hydraulic presses, but also large (such as 120,000 kN) free forging hydraulic presses directly driven by pumps.
Pump-accumulator drive In this drive system there is one or a group of accumulators. When the high-pressure working fluid supplied by the pump has a surplus, it is stored by the accumulator; when the supply is insufficient, it is supplemented by the accumulator. With this system, the capacity of the pump and the motor can be selected according to the average consumption of the high-pressure working fluid, but because the pressure of the working fluid is constant, the electric energy consumption is large, and the system has many links and the structure is more complicated. This kind of drive system is mostly used for large hydraulic presses, or a set of drive system drives several hydraulic presses.
