Thermal effect on the film thickness in high-speed lubricated cold rolling of a strip—an inlet zone analysis

Abstract

A thermal analysis of hydrodynamic lubrication of high-speed cold rolling of strips in the inlet zone has been made to estimate the film thickness in the contact region. The piezoviscous effect, which would be significant in the case of heavy-duty rolling when a large reduction in the thickness of the strip takes place during the rolling process, has been incorporated using Roelands' viscosity model. The generalized Reynolds equation in the inlet zone has been solved using the finite difference method to determine the pressure distribution. Temperature variations across the film have been expressed using Legendre's polynomial at Lobatto points while solving the energy equation. Temperature variations along the film were determined using the finite difference method by solving the energy equation. The results for the film thickness-temperature profile in the inlet zone have been estimated for high-speed rolling of the strip (up to 50m/s) with and without sliding for heavy reduction in thickness of the strip. Significant reduction in the film thickness due to the thermal effect has been found.