How to purchase rolling bearings
Rolling bearings are bearings with many types. Rolling INA bearings can be divided into many categories. How to choose rolling bearings? Now that there are many bearing markets, how to choose bearings with good quality and reasonable price?
The rolling bearing ring bears three kinds of loads, cyclic load, partial load, and swing load. Rotation accuracy. When the bearing has a higher rotation accuracy requirement, in order to eliminate the influence of elastic deformation and vibration, clearance fit should be avoided. In the axial displacement fit of the bearing, when a ring of the bearing is required to move axially during operation, the outer ring of the bearing and the housing hole of the bearing housing should adopt a loose fit.
For the choice of matching, the bearing and the shaft are matched with the base hole system, and the shell is matched with the base shaft system. The matching of the bearing and the shaft is different from the tolerance matching system used in the machine manufacturing industry. The tolerance zone of the bearing inner diameter is mostly below the change. Therefore, under the same matching conditions, the matching of the bearing inner diameter and the shaft is tighter than the usual fit. . Although the tolerance zone of the bearing outer diameter and the tolerance zone of the base shaft system are below the zero line, their values are different from the general tolerance system.
For the structure and material of the bearing housing hole, it is not advisable to use an interference fit when matching with the outer ring of the bearing, nor to make the outer ring rotate in the housing hole. For bearings installed in thin-walled shell holes, light metal shell holes or hollow shafts, a tighter fit than thick-walled shell holes, cast iron shell holes or solid shafts should be used. The size of the load, the interference between the bearing ring and the shaft or housing hole depends on the size of the load. When the load is heavier, a larger interference fit is used; when the load is light, a smaller interference fit is used. Generally, when the radial load P is less than 0.07C, it is a light load, when P is greater than 0.07C and equal to or less than 0. When it is 15C, it is a normal load, and when P is greater than 0.15C it is a heavy load.
Operating temperature, when the bearing is running, the temperature of the ring is often higher than the temperature of the adjacent parts. Therefore, the inner ring of the bearing may loosen from the shaft due to thermal expansion, and the outer ring may affect the axial direction of the bearing in the housing hole due to thermal expansion. Swimming. When selecting the fit, the temperature difference and expansion and contraction of the bearing device part should be taken into consideration. When the temperature difference is large, the interference between the shaft and the inner ring should be larger. It is easy to install and disassemble. For heavy machinery, the bearing should adopt loose fit. When tight fit is required, separable bearings, inner ring with tapered holes and bearings with adapter sleeves or withdrawal sleeves can be selected.
When purchasing bearings, you should choose a high-reputation bearing approach, and choose bearings based on the requirements, size, material and other characteristics of the bearings. Bearings are divided into many types, mainly based on your own needs.