Bearing Clearance 2018-09-04 17:13:55

The play has a very important influence on the overall performance of the rolling bearing. When the installation and operating conditions are certain, the clearance determines the load distribution of the bearing and the maximum contact stress, and affects the fatigue life of the bearing. Therefore, there is an optimum working clearance, which makes the bearing have the longest fatigue life. For angular contact ball bearings, the play also determines its fatigue life. If the clearance is not properly selected, it is very easy to cause early failure of the bearing.
Angular contact ball bearings are generally used in pairs. They are classified into two types: pre-gap and pre-load. Machine tool bearings with higher stiffness requirements are preloaded, and the shaft's mating interference is small (approximately a few microns). There is no need to consider the effect of the interference on the working clearance when pairing. However, for bearings with large interference, the influence of the interference on the radial clearance must be considered. In this case, the pre-gap configuration is used. And JB / T 10186-2000 only for 7200B and
The pre-gap value of the 7300B bearing series is specified and is not specified for other series, so theoretical calculations are required to select a suitable clearance range.
The effects of cooperation, temperature rise and centrifugal effect on the working clearance of deep groove ball bearings have been discussed more, but these factors have less influence on the clearance of angular contact ball bearings. Therefore, the following are the cooperation, temperature rise and centrifugation. The effect of the effect on the angular bearing ball bearing clearance is analyzed.

1 Factors affecting the preload of angular contact ball bearings
If the preload of the bearing increases, the stiffness can be increased, but an excessive preload will cause the bearing to generate abnormal heat, resulting in early failure of the bearing. In the positioning pre-tightening, the pre-tightening force depends on the bearing installation conditions, including the cooperation of the bearing, the centrifugal effect during operation and the temperature rise.
1.1 Bearing cooperation
For machine tool bearings, the inner ring is generally an interference fit and the outer ring is a clearance fit. The interference fit between the inner ring and the shaft changes the radial dimension, resulting in an increase in the preload.

1.2 Centrifugal effect
When the bearing runs at high speed, the inner channel will expand due to the centrifugal effect, causing the radial play of the bearing to change and increase the preload.
1.3 Temperature rise
When the bearing is running, due to its internal friction, lubricant agitation and other external factors, it will lead to increased bearing temperature and expansion of the part.

Among the bearing parameters, the contact angle has a great influence on the amount of axial clearance change.
Among the effects of interference fit, centrifugal effect, and temperature rise on bearing clearance, the effect of interference fit is greatest.
In practical applications, if the bearing is interference fit, the impact of the interference interference on the bearing clearance should be taken into consideration, and a certain clearance should be reserved to avoid excessive preload and prevent the bearing from failing in advance. When the angular contact ball bearings are actually paired, the radial clearance variation should be converted into the axial clearance variation