Thermal contact conductance between rollers and bearing rings

Abstract To predict the TCC between rollers and bearing rings, an integrated thermal contact conductance (TCC) model between cylindrical surfaces was proposed. The surface topography was characterized by the Cantor set theory, and the structure function of the surface topography was used to identify the equivalent fractal dimension. Then the fractal contact model was established, and an effective contact factor was constructed to modify the contact parameters by considering the contact between two cylindrical surfaces. Finally, the discrete and continuous models were established to predict the TCC between rollers and bearing rings. To verify the validity of the TCC model, the experiments of TCCs were conducted and then the comparison between the measured and predicted TCCs was performed. The results show that the maximum and average errors between the predicted TCC and the measured data are 10.21% and 8.14%, respectively. Besides, the effects of the key factors on the TCC between rollers and rings were discussed. The TCC increases with the contact pressure because the critical generation n c increases with the contact load. Moreover, the smaller the fractal dimension, the rougher is the surfaces, and then the smaller is the TCC. The TCC between rollers and bearing rings increases with the dimensionless contact area. Besides, the TCC increases with the rotational speed for the fully run-in roller bearing, and the TCC of the dynamic lubricated roller bearing is much higher than that of the static lubricated roller bearing and that of the static non-lubricated roller bearing.