A set-up technology of the hot strip mill has been newly developed to control the head-end gauge with high accuracy. This technology consists of the rolling load model, which has the equations of rolling temperature, deformation resistance and friction coefficient, and the roll gap model.
The equation of deformation resistances expresses the influences of phase transformation and strain accumulation besides the basic deformation hardening, which are derived from the results of hot compression tests of eighteen kinds of steels with typical chemical compositions. Using this equation, the friction coefficients in actual rolling are calculated from measured rolling loads, and the equation of the friction coefficient is expressed as a function of several rolling conditions. Moreover, in order to compensate errors of the rolling load model, the adaptive control by groups of material kinds and sizes is combined with the conventional time-series adaptive control not to interfere with each other. The roll gap model takes into consideration the change of elastic deformation of rolls with roll profiles.
These models are applied to the hot strip mill at Kakogawa Works, and the gauge accuracy at the head-end can be remarkably improved over all kinds of steel strips with any size.
