Needle roller bearing
Needle bearing is a roller bearing with cylindrical roller. Compared with its diameter, the roller is slender and long. This kind of roller is called needle roller. Despite its small cross-section, bearings still have high load-bearing capacity. Needle-roller bearings are equipped with slender and long rollers (roller diameter D < 5mm, L/D < 2.5, L is roller length), so the radial structure is compact. When the inner diameter size and load capacity of needle-roller bearings are the same as other types of bearings, the outer diameter is the smallest, which is especially suitable for supporting structures whose radial mounting size is limited.
In order to ensure the same load capacity and operation performance as ring bearing, the surface hardness of raceway surface of shaft or shell hole should be similar to that of raceway of bearing ring. This kind of bearing can only bear radial load.
1. The friction coefficient of rolling bearing is smaller than that of sliding bearing, and the transmission efficiency is higher. Generally, the friction coefficient of sliding bearings is 0.08-0.12, while that of rolling bearings is only 0.001-0.005;
2. Rolling bearings have been standardized, serialized and universal, suitable for mass production and supply, and easy to use and maintain;
3. Rolling bearings are made of bearing steel and heat treated, so rolling bearings are not only equipped with equipment. It has higher mechanical properties and longer service life, and can save the expensive non-ferrous metals used in the manufacture of sliding bearings.
4. The internal clearance of rolling bearings is very small, and the processing accuracy of each part is high, so the running accuracy is high. At the same time, the rigidity of the bearing can be increased by preloading. This is very important for precision machinery;
5. Some rolling bearings can bear both radial and axial loads, so the structure of bearing bearings can be simplified;
6. Because rolling bearings have high transmission efficiency and fewer calories, it can reduce the consumption of lubricating oil and save lubricating maintenance;
7. Rolling bearings can be easily applied. On the axis of any orientation in space.