Factors affecting the service life of rolling bearings and fitting assembly.

Bearing use factors mainly refer to whether the installation and adjustment, use and maintenance, maintenance and repair meet the technical requirements. According to the technical requirements of bearing installation, use, maintenance and maintenance, the load, rotational speed, working temperature, vibration, noise and lubrication conditions of self-aligning roller bearings in operation are monitored and inspected, and the cause of abnormality is found immediately. Adjust and make it back to normal. The installation condition is one of the most important factors in use. The improper installation of the bearing often leads to the change of the stress state between the parts of the whole set of bearings. the internal factors of bearing running in abnormal state and ending service life early mainly refer to the three major factors that determine bearing quality, such as structural design, manufacturing process and material quality.

1, the choice of bearing clearance: users generally only tell what type and grade they are in when buying bearings, and rarely put forward requirements for bearing clearance. Business personnel must ask the operating conditions of the bearing, in which the speed, temperature and fit tolerance of the self-aligning roller bearing are directly related to the choice of bearing clearance. Generally speaking, motors with speeds below 3500 rpm mostly use CM clearance, such as high-temperature high-speed motors require relatively large clearance. After assembly, the bearing clearance will be reduced due to the expansion of the inner hole and the reduction of the outer circle, and the reduction of clearance = interference × 60% (except that the bearing chamber is aluminum). For example, the bearing before assembly clearance is 0.01mm, assembly interference is 0.01mm, then the bearing after assembly clearance is 0.004mm. In theory, the noise and life of the bearing reach a better state at zero clearance, but considering the problem of temperature rise in actual operation, the bearing has a better clearance of 0.002mm-0.004mm after assembly.

2. The choice of grease: the selection of grease is generally based on the rotational speed, temperature resistance, noise requirements and starting torque of self-aligning roller bearings, which requires the business staff to have a good understanding of the performance of all kinds of grease.

3, the choice of bearing type: the bearing type is generally selected by the technical personnel of the user according to the use conditions and bearing load of the supporting products. The business staff mainly know whether the actual load of the user is consistent with the selected bearing, and if the cylindrical roller bearing does not meet the requirements, the customer should be advised to change the model as soon as possible, but there is generally no problem in the selection of the model unless the special product is selected.

4. the selection of bearing sealing type: the lubrication of self-aligning roller bearing can be divided into oil lubrication and grease. Oil-lubricated bearings generally choose the form of bearings, grease-lubricated bearings generally choose dustproof cover or rubber seal seal. The dustproof cover is suitable for parts with high temperature or good use environment. The seals are divided into contact seal and non-contact seal. The contact seal has good dustproof performance but large starting torque, and the non-connecting seal has small starting torque, but the sealing performance is not as good as the contact seal.

The metallurgical quality of bearing materials used to be the main factor affecting the early failure of rolling bearings. With the progress of metallurgical technology, such as vacuum degassing of bearing steel, the quality of raw materials has been improved. The proportion of raw material quality factor in the failure analysis of self-aligning roller bearing has decreased obviously, but it is still one of the main influencing factors of bearing failure. Whether the material selection is appropriate or not is still a factor that must be considered in bearing failure analysis.