Influence of runout table operation setup on hot strip quality,subject to initial strip condition: heat transfer issues

Abstract

The heat transfer behaviour of the runout table operation has been modelled in the first stage of an investigation to quantify parameters affecting the final product quality of hot strip coil. The study has been carried out using the commercial software package ABAQUS/Standard, along with the available user routine capabilities. With the complex nature of heat removal during the process, emphasis is placed on the accurate description of the boundary conditions so as to achieve satisfactory temperature predictions. A preprocessor was developed to formulate actual plant data within the user routines, allowing the simulation of the accelerated cooling process according to particular cooling strategies as defined by the online control system. The model independently considers the geometrical position of the top and bottom laminar sprays and the calculation of the strip surface heat transfer coefficients at each time increment is achieved using boundary layer theory and an experimentally proven numerical model. With an error in temperature prediction of less than 5%, the accuracy of the model suggests that heat transfer at the top strip surface is dominant, the impact of residual coolant on subsequent impingement zones has an adverse effect on effective heat removal during the process, and, thus, a non-linear inverse relationship exists between strip speed and cooling effectiveness.