MODEL EXPERIMENTS FOR THE DETERMINATION OF THE HEAT-TRANSFER COEFFICIENT AND TRANSITION THERMAL-ANALYSIS IN THE DIRECT ROLLING PROCESS

The direct rolling process of steel is characterized by two rotating w ater-cooled rolls receiving a steady supply of molten metal that solid ifies onto the rolls. A solidification analysis of the molten metal co nsidering phase transformation and thermofluids is performed using the finite-difference method with curvilinear coordinates to reduce compu ting time. An enthalpy-specific-heat method is used to handle relaxati on of latent heat during the phase change. The computed flow field is used to analyze solidification in the molten metal. The temperature di stribution in the cooling roll is obtained using a two-dimensional fin ite-element method, because of the complex roll shape due to the cooli ng holes in the rolls and secure improvement in the accuracy of the ca lculation results. The energy equation of the cooling roll is solved s imultaneously with the conservation equation of the molten metal in or der to consider heat transfer from the molten metal. The calculated ro ll temperature is compared to experimental results and the heat-transf er coefficient between the cooling roll surface and the cast material is also determined from comparison of the measured roll temperature an d the calculated roll temperature. (C) 1998 Published by Elsevier Scie nce S.A. All rights reserved.