Cage motion analysis in coupling influences of ring guidance mode and rotation mode

Abstract

A dynamic model of a high-speed instrument rotor bearing is established, in which the parched oil lubrication is considered. The machine for dynamic test of the cage is designed to measure the cage centroid trajectory, and there comes a good agreement between the experimental results and the theoretical results. Based on the dynamic model, the force and motion of bearing cage under different conditions is analyzed, for instance, inner ring rotates with inner ring guidance (IRIG), inner ring rotates with outer ring guidance (IROG), outer ring rotates with inner ring guidance (ORIG), and outer ring rotates with outer ring guidance (OROG). Considering of ring guidance mode and rotation mode, the cage movement is investigated through the decomposition of the force on the cage. It is found the direction of cage-guide ring friction force has a significant effect on the cage whirl. When the cage is guided by rotated ring, the direction of cage-guide ring friction force is same as that of the cage whirl, and the cage movement is relatively stable; When the cage is guided by fixed ring, the direction of cage-guide ring friction force is opposite to that of the cage whirl, and the instability of the cage increases. The cage is more stable when the inner ring rotation is relative to the outer ring rotation. The instability of the cage whirl speed will cause fluctuations in the whirl radius of the cage.