​Clearance Control Of Deep Groove Ball Bearings

Aiming at the problem that the radial clearance is usually controlled by the axial clearance in the production of deep groove ball bearings, and the radial clearance is out of tolerance after the sleeve is assembled, the accuracy of the inner and outer channels and steel balls is strictly controlled, and the axial clearance is calculated by compression. The radial clearance range at the time of clearance, the lower limit remains unchanged, and the upper limit is compressed by 15%. The axial clearance obtained by this method is used as the benchmark to control the actual radial clearance after fitting. The verification of the example shows that this method can meet the technological requirements.

Clearance Analysis of Angular Contact Ball Bearings

For angular contact ball bearings, the clearance also determines its fatigue life. If the clearance is improperly selected, it is very easy to cause early failure of the bearing.

Angular contact ball bearings are generally used in pairs, and there are two types of applications: pre-clearance and pre-load. Machine tool bearings with high rigidity requirements are preloaded, and the fit interference of the shaft is small (about a few microns), so there is no need to consider the influence of the fit interference on the working clearance when pairing. However, for bearings with large interference, the influence of interference on its radial clearance must be considered, and pre-clearance configuration is often used at this time. However, JB/T 10186-2000 only stipulates the pre-clearance value of the 7200B and 7300B bearing series, and does not stipulate the other series, so it is necessary to carry out theoretical calculation and select an appropriate clearance range.

Factors affecting the preload of angular contact ball bearings: If the preload of the bearing increases, the stiffness can be improved, but excessive preload will cause the bearing to generate abnormal heat, resulting in early failure of the bearing. In positioning preload, the preload depends on the bearing installation conditions, including bearing fit, centrifugal effects during operation, and temperature rise.

1. Matching of bearings

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 its radial dimension, resulting in an increase in the preload.

2. Centrifugal effect

When the bearing runs at high speed, the inner channel will expand due to the centrifugal effect, causing the radial clearance of the bearing to change and increasing the preload.

3. Temperature rise

When the bearing is in operation, the combined effect of its internal friction, lubricant agitation and other external factors will cause the bearing temperature to rise and the expansion of the part.

(1) Among the bearing parameters, the contact angle has a great influence on the change of the axial clearance. (2) Among the influences 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, it is necessary to take into account the influence of the interference fit on the bearing clearance, and a certain clearance should be reserved to avoid excessive preload and premature failure of the bearing. When angular contact ball bearings are actually paired, the change in radial clearance should be converted into the change in axial clearance for consideration.