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The clearance analysis of angular contact ball bearing

wallpapers News 2021-02-22
Angular contact ball bearings mainly bear large unidirectional axial loads. The greater the contact angle, the greater the load capacity. The cage material is steel plate, brass or engineering plastics, and its forming method is stamping or turning, depending on the form of the bearing or the conditions of use. There are other combinations of angular contact ball bearings, double row angular contact ball bearings and four-point contact ball bearings.
Angular contact ball bearings can simultaneously bear radial load and axial load. Can work at a higher speed. The larger the contact angle, the higher the axial bearing capacity. The contact angle of high-precision and high-speed bearings is usually 15 degrees. Under the action of axial force, the contact angle will increase. Single row angular contact ball bearings can only bear axial load in one direction. When subjected to radial load, an additional axial force will be generated. And it can only limit the axial displacement of the shaft or the bearing seat in one direction. If installed in pairs, the outer rings of a pair of bearings are opposed, that is, the wide end faces the wide end face and the narrow end faces the narrow end face. In this way, the additional axial force can be avoided, and the shaft or housing can be restricted to the axial gap in both directions.
Angular contact ball bearing clearance analysis
Angular contact ball bearings are usually used in pairs, and their applications are divided into two types: pre-clearance and pre-load. Machine tool bearings with higher rigidity requirements adopt a preloaded structure, and the matching interference of the shaft is small (about a few microns), and there is no need to consider the impact of matching interference on the working clearance when pairing. However, for bearings with large matching interference, the influence of interference on its radial clearance must be considered. In this case, the pre-clear configuration is usually used.
For angular contact ball bearings, the clearance also determines their fatigue life. If the gap is not selected properly, it is easy to cause premature bearing failure.
Factors affecting the preload of angular contact ball bearings
If the pre-tightening force of the bearing is increased, the rigidity can be improved, but excessive pre-tightening force will cause abnormal heating of the bearing, which will lead to premature bearing failure. When positioning the pre-tightening force, the pre-tightening force depends on the installation conditions of the bearing, including bearing fit, centrifugal effect and temperature rise during operation.
1. Matching of bearings
For machine tool bearings, usually, the inner ring has an interference fit and the outer ring has a clearance fit. The interference fit between the inner ring and the shaft will cause the radial dimension to change, resulting in an increase in the preload.
2. Centrifugal action
When the bearing is running at high speed, the internal passage will expand due to the centrifugal effect, which will cause the radial clearance of the bearing to change and increase the preload.
3. Temperature rise
When the bearing is in operation, due to its internal friction, lubricant agitation and other external factors, the temperature of the angular contact ball bearing will rise and the parts will expand.
(1) Among the bearing parameters, the contact angle has a greater influence on the change of axial clearance.
(2) Among the influence of interference fit, centrifugal effect and temperature rise on bearing clearance, interference fit has the greatest influence.
(3) In practical applications, if the bearing has an interference fit, the influence of the fit interference on the bearing clearance should be considered, and a certain amount of clearance should be reserved to avoid excessive preload and premature bearing overshoot. Surplus. Bearing failure.
(4) When the angular contact ball bearings are actually paired, the change in radial clearance should be converted into the change in axial clearance for consideration.

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