An investigation on cage instability based on dynamic model considering guiding surface three-dimensional contact

The cage instability significantly affects the bearing dynamic behavior and weakens the rotating system performance. To predict this instability, however, a bearing dynamic model with detailed consideration of the interface and velocity between the cage and the other components is still lacking. To this end, this paper proposes a new bearing dynamic model that places all moving components in the inertial coordinate frame. The geometrical interactions and velocities between the cage and other components are considered in detail. The slicing method is employed to derive the interaction between the deflected cage and the guiding ring. The influence mechanism of two typical operating conditions on cage dynamic behavior is investigated from the perspective of ball/pocket collisions. On this basis, new indictors are defined to study the thresholds for operating condition leading to cage instability. Attempts are further made to improve cage stability by optimizing bearing contact angle. The results show that heavy radial loads significantly enhance the cage instability and the shock exerted on the cage. Interestingly, the smaller the contact angle, the more pronounced the improvement in the cage dynamic performance.