Kinematic characteristics and fault feature frequency of flexible thin-wall ellipse bearing

Abstract

Flexible thin-wall ellipse bearing (FTEB) is a new type of bearing with completely different kinematic characteristics and fault feature frequencies from ordinary rolling bearing. It is found that the trajectory of the roller center of FTEB is not consistent with the pitch ellipse, while that of ordinary rolling bearing is the pitch circle. The motion trajectory of the roller relative to the pitch ellipse and the cage is further studied. A velocity distribution model of FTEB is proposed, it is proved that FTEB has radial velocity. The radial velocity and acceleration of FTEB are time-varying, and their frequency is twice that of the shaft, while ordinary bearing has no radial velocity and acceleration. Based on the velocity model, the fault feature frequencies of FTEB are derived, which are not fixed values but fluctuating, and the fault feature frequencies of ordinary bearing are only the special cases of FTEB. The vibration of the FTEBs with damaged outer and inner rings is detected, and the results show that there are periodic impacts caused by the rotation of the long and short axes of ellipse in the vibration of FTEB. Finally, the fault impulse feature of the damaged outer and inner rings is extracted, which verifies the theoretical result of the fault feature frequencies of FTEB.