AN ASYMPTOTIC MODEL OF WORK ROLL HEAT-TRANSFER IN STRIP ROLLING

An asymptotic model of work roll heat transfer is developed using a mu ltiple time scale approach. The model is appropriate under typical hig h Peclet number rolling conditions and provides a unified framework fo r relating previous roll heat transfer models. The solution consists o f a fast time scale thermal boundary layer near the roll surface, alon g with a slow time scale Core heat transfer problem. Several features of the model are illustrated. First, boundary layer behavior is examin ed under steady and dynamic conditions. Here, the decay rate for bound ary layer transients is determined and theoretical steady-state temper ature distributions are compared against previously reported experimen tal data. Heat transfer within the core is then considered under relat ively general surface heating conditions. In the special case where th e surface heat flux is constant, core temperatures are shown to increa se linearly with time. In the last illustration, the model is used to obtain inverse estimates of circumferentially varying roll surface hea t flux and temperature distributions. In this case, comparisons are ma de with the finite difference-based inverse estimates recently reporte d by Huang et al., International Journal of Heat and Mass Transfer, 19 95, 38, 1019-1031. (C) 1997 Elsevier Science Ltd.