A Refined Double-row Spherical Roller Bearing Model and its Application in Performance Assessment of Moving Race Shaft Misalignments

Abstract

Largely due to their self-aligning and superior loading capabilities, spherical roller bearings have seen extensive application. Compared with the single-row deep-grooved-ball (DGB) bearing, the dynamics involved in the operation of double-row spherical roller bearings (SRBs) are much more complicated; double-row SRBs have at least twice as many degrees of freedom (DoFs) as DGBs. Also, the contact forces between each one of a pair of rollers and the inner race/outer race can be different, resulting in unbalanced axial forces on the moving race and causing axial displacement and angular movements of the moving race. Due to its complexity, modeling efforts carried out so far have not included the effects of the rotational DoFs of the moving race. Aiming at improving the state of the art, a comprehensive dynamic model of SRBs is developed in this investigation. This model takes into account all the DoFs of the moving race, including the angular movements about both the vertical and horizontal axes. Subsequently, the contact angle between each individual roller and the moving race is correlated with each linear and rotational DoF of the moving race. The model developed in this investigation can quantitatively analyze the effects of linear and rotational shaft misalignments. Therefore, it provides guidelines for optimizing system installation requirements/procedure, which will be valuable for high-precision machine systems. The simulation results demonstrate that the rotational DoFs of the moving race have major effects on the force/displacement responses and thus should be included in the model for a more accurate assessment of the system performance. Extensive case studies are carried out to assess the effects of the loading conditions and radial clearance, as well as shaft misalignment.