The hydraulic drive system of the four-column hydraulic press consists of a power mechanism, a control mechanism, an actuator, an auxiliary mechanism and a working medium. The power mechanism usually uses an oil pump as the power mechanism, and is generally a product type oil pump. In order to meet the requirements of the speed of the actuator, an oil pump or multiple oil pumps are used. Gear pump for low pressure (oil pressure less than 2.5MP); vane pump for medium pressure (oil pressure less than 6.3MP); plunger pump for high pressure (oil pressure less than 32.0MP). Pressure processing and forming of various plastic materials, such as extrusion, bending, stretching of stainless steel sheet steel and cold forming of metal parts, and also for pressing of powder products, grinding wheels, bakelite, and resin thermosetting products.
The evolution of the working medium The hydraulic machine initially uses water as the working medium, and later uses an emulsion of a small amount of emulsified oil added to the water to increase lubricity and reduce rust. In the late 19th century, a hydraulic press with mineral oil as the working medium appeared. The oil has good lubricity, corrosion resistance and moderate viscosity, which is beneficial to improve the performance of the hydraulic press. In the second half of the 20th century, a new type of water-based emulsion appeared, and its emulsified form was “water-in-oil” rather than the original “oil-in-water”. The outer phase of the "water-in-oil" emulsion is oil. Its lubricity and corrosion resistance are close to that of oil, and its oil content is small and it is not easy to burn. However, water-based emulsions are more expensive and limit its promotion. The role of working medium
The working medium used in the hydraulic press not only transmits the pressure but also ensures that the working parts of the machine are sensitive, reliable, long-lived and have less leakage. Basic requirements for working media The basic requirements for hydraulic media for working media are:
1 has suitable fluidity and low compressibility to improve the efficiency of the transmission;
2 can prevent rust;
3 has good lubrication properties;
4 easy to seal;
5 anti-oxidation, stable performance, long-term work without deterioration.