Thread Content
According to Dr. Zhang from Hydraulics Talent Network, part of Yilan Group, the main factor causing damage to sealing elements is impurities in the working fluid. These impurities grind against each other within the sealing elements, causing the valve to leak. Therefore, abroad, it has been proposed that hydraulic components of corresponding grades should use filters with appropriate precision. They believe that for 5μM oil pump sealing elements, the service life can be increased by 10 times compared to those using 10μM filters, if a filter with a filtration precision of 3/μM is used. However, the valves used in hydraulic support operate in extremely harsh environments. In the coal mining face, the total length of the oil pipes is over 1,000 meters, with more than 4,000 connection fittings, and the liquid tanks lack any special dust prevention facilities. There are a large amount of floating impurities in the emulsion, and considerable amounts of coal powder, rock particles, and iron shavings remain at the bottom of the cylinder columns and within the valve chambers. The inlet valve spool and seat, due to frequent opening and closing as well as high liquid flow rates, experience rapid seal failure. Practice has shown that it is very difficult to reduce the contamination of the liquid in the support hydraulic system. Some have proposed using high-pressure filters at the emulsion pump stations, along with small filters installed at the inlet of each support. But it gets blocked quickly during operation, resulting in a flow interruption. On the other hand, with the development of hydraulic support technology. Higher requirements have been placed on the performance of valves and their service life. Currently, with filters and magnetic filtration units equipped with 120-mesh screens, the lifespan of hydraulic valves is measured based on the total flow rate of the emulsion passing through the valve under test and the number of times the valve is opened and closed. But in reality, the results of indoor type tests differ greatly from those of actual operations underground. Many current **formal experiments have introduced anti-pollution requirements; in some cases, appropriate amounts of coal powder are added to the emulsion, while in others mechanical impurities are incorporated. To this end, new types of sealing pairs with strong anti-pollution capabilities and suitable for underground working conditions are required. The service life of various hydraulic valves in hydraulic supports is very short. The approaches taken abroad to address this issue are to improve the filtering precision of the system and enhance the quality of the emulsion, but these measures yield limited results. This paper analyzes the development process of the sealing pairs in cartridge valves, and discusses the relationship between the materials of the sealing pairs and their sealing performance. It points out that sealing technology is key to extending the service life of hydraulic valves in hydraulic support systems.