Dynamic Service Mechanism of Double-Row Spherical Roller Bearings Due to Self-Aligning Behavior

Spherical roller bearings (SRBs) are widely used under self-aligning operating conditions, such as rotor bending or an angular misalignment between inner and outer rings due to their self-aligning function. However, the characterization of SRBs' self-aligning function is often ignored in the present models. The reason for this is that the self-aligning condition is essentially a fault condition, and many scholars have assumed SRBs are in an ideal operating condition. Although there is nothing wrong with this analysis theoretically, it is incapable of characterizing SRBs' service behavior comprehensively. In this work, the Lagrange equation was introduced to model the relationship among the rollers and the inner and outer rings. The contact region in particular was characterized in detail in order to solve the problems of undetermined contact status (UCS) and the varying law of the self-aligning contact angle (SAC angle). For the experiment, a novel SRBs pedestal with a self-aligning operating condition was designed, and the relevant self-aligning function testing was carried out. A good agreement was shown between the theoretical and experimental results. The results pointed out that, if taking no account of the self-aligning function, SRBs can be regarded as angular contact ball bearings or cylinder roller bearings. The amplitude of the inner-ring motion orbit is determined by the external load, but the shape is influenced by the direction and magnitude of the SAC angle. In the example of this paper, the values of the main frequency equal 136.8 Hz. Some additional frequencies are clearly aroused under the self-aligning operating condition, whose value is approximately equal to 8.3 Hz or its integer multiples. The dynamic performance of SRBs will be substantially improved by a light axial load plus an anticlockwise self-aligning contact angle rather than a large axial preload.