Roller Profile Development for an Axially Loaded, Single Row Spherical Roller Bearing in an Oscillating Application

Typically it is not recommended to use a single row spherical roller bearing in an application in which there are significant axial loads. The use of these bearings in a less than optimal customer application can be driven by the need for a high load capacity within a limited geometric envelope. Specialized roller profiles can be developed that eliminate high contact stresses on the roller ends that can lead to the premature failure of the bearing. In this paper, analytical results are presented for the roller to raceway contact stress of four different roller profiles with a given load applied to the bearing. The profiles considered are single transverse radius, double transverse radii, and optimized symmetric and asymmetric. The piecewise logarithmic profiles developed are applied to a barrel roller in this paper, but a generalized method is developed such that the profile could be applied to any type of roller—cylindrical, barrel, hourglass, or tapered. The analysis results for two of the profiles are validated by dynamic testing performed within RBC’s Corporate Test Laboratory on a three axis, hydraulic, computer controlled test rig. The bearing inner ring is oscillated while the bearing is subjected to simultaneous radial and axial loads. The control software allows the monitoring of radial displacement and bearing torque during testing. The test results correlate very well with the analytical results. The displacement and torque readouts are shown to predict the onset of raceway fatigue and spalling for one of the roller configurations before testing is complete and the bearing is disassembled.