AN INVERSE FINITE-ELEMENT EVALUATION OF ROLL COOLING IN HOT-ROLLING OF STEELS

While roll cooling systems have been employed in steel rolling mills for years, the heat transfer related phenomena in roll cooling are still not fully understood. In this paper, a combined experimental and finite element approach has been used to study the local heat transfer of spray cooling in the hot rolling of shaped steels. A production-scale hot rolling mill has been instrumented; the thermal behavior at typical operation conditions has been monitored and investigated. The measurement temperatures have been used to quantify the heat flux in the bite region and heat transfer coefficient in the spray portion through an inverse heat conduction (IHC) technique. The present study indicates that the heat transfer at the bite region is extremely high, and can generate significantly large thermal stresses and expansions to deteriorate the roll surface and shape. In order to demonstrate the reliability of the IHC results, a direct finite element analysis based on the estimated heat flux and the heat transfer coefficient as the boundary conditions has been performed to predict the temperatures at the measurement locations. Excellent agreement has been found between the prediction and measurement.