In the moving parts, the wear of the parts is caused by long-term friction. When the gap between the shaft and the hole is worn to a certain extent, the parts must be replaced. Therefore, the designer chooses the one with lower hardness and better wear resistance when designing. The material is the shaft sleeve or bushing, which can reduce the wear of the shaft and the seat. When the shaft sleeve or bushing is worn to a certain extent, it can be replaced, which can save the cost of replacing the shaft or seat. Generally speaking, the bushing and the seat are made of Interference fit, and clearance fit with the shaft, because no matter what, it is unavoidable to avoid wear and tear, and can only prolong the life, and shaft parts are relatively easy to process; there are also some new designers who do not like this design, thinking that it is It is to increase the cost during manufacturing, but after a period of use, it is still necessary to transform in this way during maintenance, but the transformation will easily reduce the accuracy of the equipment. The reason is very simple. The second processing cannot guarantee the position of the center of the seat hole. To add, the bushing is used to replace rolling bearings (in fact, the bushing is also a kind of sliding bearing) in some places with low rotational speed, high radial load and high clearance requirements (such as camshafts), and the material requires low hardness and resistance. Grinding, the inner hole of the shaft sleeve is ground and scraped, which can achieve high matching accuracy. There must be a lubricating oil groove on the inner wall. The lubrication of the shaft sleeve is very important. If it is dry ground, the shaft and the shaft sleeve will be scrapped soon. When installing, scrape the inner hole wall of the bushing, so that many small pits can be left, and the enhanced lubrication bushing and bushing are of different types according to different industrial and mining conditions. The most important conditions are: pressure, velocity, product of pressure and velocity, lubrication state, and load properties. The quick and easy automatic selection of bushings is included.
Wrapped around the valve stem, it is worn and can be easily replaced. If the bushing is not used, it is the parts that are replaced when worn. So the replacement is to replace the bushing (in the design, the hardness of the bushing is reduced to make it a wear-bearing part in the friction pair). Because of its convenient processing, low replacement cost and easy replacement. Of course, there are also guiding functions, which are secondary.
