Ball bearing is a kind of rolling bearing, such as Flanged Ball Bearings. The ball is installed in the middle of the inner steel ring and the outer steel ring, and can bear a large load, also called ball bearing. Bearing clearance (internal clearance) refers to the total distance that a bearing ring can move in a certain direction relative to another ring before the bearing is installed with the shaft or bearing housing. According to the direction of movement, it can be divided into radial clearance and axial clearance.
The internal clearance of the bearing before installation must be distinguished from the internal clearance (operating clearance) of the bearing when the operating temperature is reached after installation. The original internal clearance (before installation) is usually greater than the operating clearance. This is due to the difference in the degree of fit involved in the installation and the difference in the thermal expansion of the inner and outer rings of the bearing and related components that cause the inner and outer rings to expand or contract.
Bearing internal clearance and specified value
The size of the internal clearance (also called the clearance) of the rolling bearing in operation has a great influence on the bearing performance such as fatigue life, vibration, noise, and temperature rise.
Therefore, selecting the internal clearance of the bearing is an important research project for the bearing that determines the structural size.
Generally, in order to obtain a stable test value, a specified test load is given to the bearing, and then the clearance is tested. Therefore, the measured clearance value is larger than the theoretical clearance (in the radial clearance, also called geometric clearance), that is, one more elastic deformation caused by the test load (called the test clearance Show the difference).
Generally, the clearance before installation is specified by the theoretical internal clearance.
Choice of internal clearance:
The following points should be considered when selecting the most suitable clearance according to the conditions of use:
(1) The matching of the bearing, the shaft and the housing causes the change of the clearance.
(2) The clearance changes due to the temperature difference between the inner and outer rings when the bearing is working.
(3) The material used for the shaft and the housing affects the change of bearing clearance due to different expansion coefficients.
For bearings that generally work normally, the radial clearance of the basic group should be used first. But for bearings that work under special conditions, such as high temperature, high speed, low noise, low friction and other requirements, the radial clearance of the auxiliary group can be selected. Choose smaller radial clearances for precision bearings, bearings for machine tool spindles, etc. If there are special requirements for bearing clearance, the bearing can meet the needs of customers.
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