Roll pass evaluation for hot shape rolling processes

Abstract

Since the complex shaped caliber rolling usually takes place in hot operation, three dimensional mechanical behavior coupled with the heat transfer in and around the billet must be taken into account for accurate evaluation of the roll pass system. In the present study, the authors propose a new simulation approach to deal with the above coupling problem: the deformation mode method for the three dimenional deformation in the steady-state rolling process, and the two dimensional boundary element method for radiation and convection heat transfer between mill stands. Furthermore, to deal with temperature history in plastic working, heat generation by plastic deformation and friction work and heat transfer between rolls and billet are both taken into account in every incremental reduction. As an example, the butterfly roll pass system is taken in the actual angle steel rolling. It is found that (1) the mechanical behavior and characteristics can be discussed by the calculated metal flow, strain and temperature distributions in the whole roll pass system, and (2) the numerically estimated cross-sectional shapes after rolling are in fairly good agreement with the experimental measurements in the actual processing. The above example demonstrates the validity and effectiveness of the present modelling even for the industrial shape rolling process.