Hydraulic press working principle
Hydraulic press is a device that uses hydraulic transmission technology for pressure processing, and can be used to complete various forging and press forming processing. For example, the forging of steel, the forming of metal structural parts, the pressing of plastic products and rubber products, etc. Hydraulic press is one of the machinery that applied hydraulic transmission very early. At present, hydraulic transmission has become the main transmission form of pressure processing machinery. Hydraulic presses have become important equipment in the heavy machinery manufacturing, aviation industry, plastics and non-ferrous metal processing industries.
The hydraulic transmission system of the hydraulic press is mainly based on pressure conversion, with high system pressure, large flow and high power. Therefore, special attention should be paid to improving the power utilization rate of the prime mover and preventing shock and vibration when the pressure is relieved to ensure safety and reliability.
According to the requirements of the pressing process, the main cylinder of the hydraulic press can complete the basic working cycle of rapid down-deceleration, pressure-holding delay, pressure relief return, and stop (any position), and the pressure, speed and pressure-holding time need to be adjustable. The ejection hydraulic cylinder is mainly used to eject the workpiece, and it is required to realize the actions of ejection, retreat, and stop. For example, when the sheet is stretched, auxiliary actions such as lifting, stopping and pressure return of the ejector hydraulic cylinder are required. Sometimes it is necessary to use a press cylinder to compress the blank to prevent the periphery from wrinkling.
The hydraulic press takes the maximum pressure (tonnage) that may be output by the main actuator (master cylinder) in the main motion as the main specification of the hydraulic press, and has been serialized. The tonnage of the ejector cylinder often adopts 20%-50% of the tonnage of the main cylinder. The ejector cylinder of the extruder can use about 10% of the main tonnage. The tonnage of the blanking cylinder of the double-acting hydraulic drawing press is generally about 60% of the tonnage of the drawing cylinder.
The speed of the main cylinder is determined by the pressure processing technology. Generally, in the hydraulic system directly supplied by the pump, the working stroke speed does not exceed 50mm/s, the fast forward speed does not exceed 300mm/s, and the hydraulic press retreats and fast forwards and the speed is equal.