Deep groove ball bearing clearance control
For the deep groove ball bearings used in the production of axial clearance control of radial clearance, radial clearance clearance after the problem, through the strict control of the accuracy of the inner and outer channel and steel ball, and compression calculation of axial travel The radial clearance range during the gap, the lower limit value remains unchanged, and the upper limit value is reduced by 15%. The axial clearance obtained by this method is used as a reference to control the actual radial clearance after jointing. Example verification shows that this method can meet the process requirements .
Clearance analysis of angular contact ball bearings
For angular contact ball bearings, the clearance 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 used in two types of preload and preload. The bearings with higher stiffness require a preload configuration and the shaft has a small amount of fitting interference (approximately a few microns). When pairing, it is not necessary to consider the effect of the fit interference on the working clearance. However, for a bearing with a large amount of interference, the influence of the interference on its radial clearance must be considered. At this time, the pre-backlash configuration is often used. The JB /T 10186-2000 only specifies the pre-backlash values for the 7200B and 7300B bearing series, and there is no provision for other series. Therefore, theoretical calculations are required to select a suitable clearance range.
Factors influencing preloading of angular contact ball bearings: If the preload of the bearing increases, the stiffness can be increased, but excessive preload will cause abnormal heating of the bearing, leading to early failure of the bearing. In positioning pretensioning, the preload depends on the mounting conditions of the bearing, including the fit of the bearing, the centrifugal effect during operation, and the temperature rise.
1. Bearing assemble
For machine tool bearings, the inner ring generally has an interference fit and the outer ring has a clearance fit. The interference fit between the inner ring and the shaft changes its radial dimension, leading to an increase in the pre-tightening force.
2. Centrifugal effect
When the bearing is running at a 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 running, due to the combined action of its internal friction, agitation of the lubricant and other external factors, the bearing temperature will rise and the part will expand.
(1) In the bearing parameters, the contact angle has a great influence on the amount of axial clearance change. (2) interference fit, centrifugal effect, temperature rise on bearing clearance
In the impact, the influence of interference fit is greatest. (3) In practical applications, if the bearing interference fits, the influence of the fit interference on the bearing clearance needs to be taken into account, and a certain clearance should be reserved to avoid causing too large pre-tightening force and premature failure of the bearing. When the angular contact ball bearing is actually paired, the amount of radial clearance change should be converted into the amount of axial clearance change.