Abstract:  Aiming at the problem that the widely used formula for calculating the balls selfrotation speed in ball bearings under pure rolling conditions was not reasonable, based on the calculation formula of the balls selfrotation speed in Harris theory, the derivation process was revised through kinematic analysis and the corresponding explanations were made. The correct method for calculating the balls selfrotation speed in ball bearings under the pure rolling condition was given. For the balls selfrotation speed in ball bearings was an important parameter for fault diagnosis and dynamic analysis of a ball bearing, based on the Gupta model, a dynamic model of rolling ball bearings with ball defects was established. The rationality of the proposed method in calculating the balls selfrotation speed was discussed by researching the time interval between impacts and verified through experiments. The results indicate that the ωbH obtained by the previous calculation formula for the balls selfrotation speed is larger than the actual selfrotation speed of the ball by ωccosα. In the process of calculating the balls selfrotation speed in ball bearings, the effect of the translation speed of the center point of the rolling ball on the speed of the rolling ballraceway contact point should be considered.

Key words:  rolling bearing; selfrotation speed of balls; fault diagnosis; dynamics analysis