How to control the radial clearance and positioning of bearings, which is more conducive to the guarantee of motor performance?

Three phase motor‘s bearing internal clearance refers to the total distance that one bearing ring can move in radial or axial direction relative to another bearing ring. For the bearing’s clearance, it is necessary to distinguish between the initial clearance before installation and the working clearance after installation and reaching its operating temperature. The initial clearance of the bearing is generally larger than the working clearance, due to the tolerance match of different interference amounts, as well as the different degrees of thermal expansion of the bearing ring and its adjacent parts, resulting in the expansion or compression of the ring.

In order to make the 3 phase motor bearing run well, the radial clearance is very important, which needs to choose the appropriate bearing to match it according to the actual characteristics and operating conditions of the motor. The general principle of bearing operation is that the working clearance of ball bearings should be zero or slightly pre-tightened; However, for cylindrical roller bearings, a certain residual clearance must be left during operation.
Under normal working conditions, the suitable working clearance can be obtained by selecting the ordinary group of clearance bearings. However, when the working and installation conditions are different from the general situation, such as the inner ring and the outer ring of the bearing are interference fit, or the temperature difference between the inner ring and the outer ring has a great impact, the bearing with a larger or smaller clearance than the ordinary group should be selected.

In general, must have the appropriate amount of interference, bearing ring can be fixed in the radial direction and enough support. If the bearing ring is not properly or adequately fixed, it is easy to cause damage to the bearing and related parts. However, sometimes in order to facilitate installation and disassembly, or bearings need to have the function of axial movement because they are used in the floating end, interference fit cannot be used. In some adopt under the condition of clearance fit, need to take some special measures to reduce the wear and tear caused by creep, such as: fitting surface hardening on the surface of bearing and gear shoulder, through special lubrication slot to lubrication fitting surface and exclusion of wear particles, or use bearing lateral positioning key way to fix the bearing.