Roundness error stacking in assembled spherical roller bearings and its impact on rotor subcritical vibration

In industrial processes, large rotors are commonly operated below the critical speed, where bearings can be an important source of subcritical vibration. This paper presents a complete study and analysis of the roundness error stacking in rotor-bearing systems. The investigation on how the roundness error of tapered shafts is transferred through the bearing inner ring to the raceways during the assembly process allows to evaluate the final roundness profile of the raceways as the sum of the shaft roundness profile plus the inner ring thickness variation. The method’s validity is verified for relative orientations and mounting conditions between the components. A test case is presented in which 3D conical grinding is applied to a shaft tapered bearing installation seats, reducing the roundness error of installed bearings when compared to previous research results. The relevance of the study was proven with rotordynamic measurements, which show that minimized roundness error reduces vibrations.