Mixed-film lubrication theory and tension effects on metal rolling processes

A cold rolling model, based on Wilson and Chang's asperity flattening model and von Mises homogenous deformation model, for mixed film lubrication is developed. A more rigorous average Reynolds equation is used to calculate the hydrodynamic pressure. The variations of the yield stress with strain are considered in the model. An efficient iteration procedure is developed to solve the contact area, film thickness, and hydrodynamic pressure. The model is more practical with fewer assumptions, and converges quickly. It is applicable to a wider range of rolling regimes, particularly at high rolling speed. The calculation results agree well with the literature as well as with measured data from a rolling mill. © 1999 by ASME.