Simulation of Cone Bore Growth in Bearings With a Three-Ring Model

Cone bore growth in case-carburized bearings was modeled by incorporating the mechanisms of thermal-induced phase transformation and low temperature creep in an approximate model of the cone. The inner case, core, and outer case regions of the bearing cone are modeled by three concentric rings. Using a mechanics of materials approach with the aid of some simplifying assumptions (i.e., radial stresses remain zero throughout the ring thickness and net circumferential strain is the same for all three rings), the influence of temperature, interference fit stresses, initial case carburizing stresses, and stress relaxation on the change in bore diameter and circumferential stress during service could be determined. The model indicated that both thermal-induced transformation and low temperature creep may play a role in bore growth during service. As temperature was increased from 70° C to 200°C, the susceptibility to bore growth became greater. Also, an increase in the interference fit increased the initial cone bore growth rate. In addition, the effect of the recondition treatment on the bore diameter and residual stresses was studied. The bore diameter generally decreased during the recondition treatment, and this was attributed to the relaxation of residual stresses by low temperature creep.