Heat transfer in the roll gap during hot rolling

Abstract

A series of pilot mill hot-rolling tests involving AA5052, AA5 182, and copper samples has been performed. These rolling tests encompassed a range of rolling pressures, rolling speeds, reductions and temperatures. In addition, two types of lubricants were employed in the hot rolling of the aluminum alloy samples. Instantaneous roll-gap heat-transfer coefficients (HTCs) have been calculated from roll-gap surface temperature measurements. These measurements were made from double-intrinsic thermocouples secured on the surface of the samples. Average roll-gap HTCs have been calculated from the bulk temperatures of the samples immediately before and after rolling. The roll-gap HTC was calculated by an implicit, one-dimensional finite-difference technique. The resulting roll-gap HTCs of both the aluminum alloy and the copper samples were compared to those obtained for steel rolling in a previous study. The roll-gap HTC has been proposed to be a function of the harmonic conductivity of the material being rolled and the roll, the ratio of the rolling pressure to the surface flow stress of the material being rolled, and the surface roughnesses of the roll and the material being rolled.