Control Technology of Secondary Cooling Process in Round Billet Continuous Casting Based on a Mathematical Model

For the improvement of quality of round billet, a mathematical model of secondary cooling process control has been developed on the following procedure. (1) Cylindrical heat transfer model suitable for round section is considered, and one dimensional difference equation along the billet radius is derived. (2) In regard to the boundary condition of billet surface, heat transfer coefficients which are suitable for mold area, direct cooling area and indirect cooling area respectively are selected. (3) The authors have developed a control method determining optimum water flow in order to keep the temperature fall pattern of billet surface at the aimed value by using the above mentioned model. This control method is being put into practice and improves the control accuracy of surface temperature of round billet, and it contributes to the reduction of degrading ratio due to surface defects and so on.