Detailed explanation of the structural principle of hydraulic press

The driving system of hydraulic press mainly includes two types: pump direct drive and pump-accumulator drive. Pump direct drive: The pump of this driving system provides high-pressure working fluid to the hydraulic cylinder, the distribution valve is used to change the direction of fluid supply, and the overflow valve is used to adjust the limited pressure of the system and play an overflow role at the same time. This driving system has fewer links and simple structure. The pressure can automatically increase or decrease according to the required working force, reducing the power consumption, but the capacity of the pump and its driving motor must be determined by the working force and working speed of the hydraulic press. This type of driving system is mostly used for small and medium-sized hydraulic presses, and there are also large (such as 120,000 kN) free forging hydraulic presses driven directly by pumps.

Pump-accumulator drive: There is one or a group of accumulators in this driving system. When the high-pressure working fluid supplied by the pump has a surplus, it is stored in the accumulator; when the supply is less than the required amount, it is supplemented by the accumulator. With this system, the capacity of the pump and the motor can be selected according to the average usage of the high-pressure working fluid, but because the pressure of the working fluid is constant, the power consumption is large, and the system has many links and a relatively complex structure. This drive system is mostly used for large hydraulic presses, or a set of drive systems is used to drive several hydraulic presses.

Structural type

According to the direction of the force, hydraulic presses are divided into two types: vertical and horizontal. Most hydraulic presses are vertical, while hydraulic presses for extrusion are mostly horizontal. According to the structural type, hydraulic presses are divided into two types: double-column, four-column, eight-column, welded frame and multi-layer steel belt winding frame. Medium and small vertical hydraulic presses also use C-frame type. C-frame hydraulic presses are open on three sides, easy to operate, but have poor rigidity. The welded frame hydraulic press for stamping has good rigidity, open front and back, but closed left and right. In the vertical four-column free forging hydraulic press with upper transmission, the cylinder is fixed in the upper beam, the plunger is rigidly connected to the movable crossbeam, the movable crossbeam is guided by the column, and moves up and down under the pressure of the working fluid. There is a workbench on the beam that can move forward and backward. The upper anvil and the lower anvil are installed under the movable crossbeam and on the workbench respectively. The working force is borne by the frame composed of the upper and lower crossbeams and the column. Large and medium-sized free forging hydraulic presses driven by pump-accumulator usually use three working cylinders with three-level working force. In addition to the working cylinder, there are also a balance cylinder and a return cylinder that apply force upward.

 

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