Analyses of thermal hydrodynamic lubrication in high-speed rolling. Part II: the effect of non-Newtonian viscosity models

In normal cold rolling, the hydrodynamic pressures established in the lubricating zones are sufficiently high to lead to a significant increase in oil viscosity. This characteristic can have a substantial effect on rolling performance. The most notable distinctions in oil viscosity at high pressures between the Roelands and Barus models are investigated here. By using the perturbation method to obtain the rolling parameters, the effect of non-Newtonian lubrication has been evaluated by three non-Newtonian models and one Newtonian model. The results from these analyses reveal that, in normal rolling, Barus' model can produce the greater rolling quantities - including hydrodynamic pressures and film thicknesses, film temperature, driving torque and separating force. However, the differences in these parameters between Newtonian and non-Newtonian models are quite small.