1991 Volume 4 Issue 4 Pages 140-154
To realize a low-order thickness control system for tandem cold mills, a multivariable control algorithm based on decentralized technique has been studied. In the algorithm, the static interaction and the dynamic one are treated separately. The static interaction due to interstands tension produces steady state thickness errors at neighboring two stands. While, the dynamic interaction between thickness and tension control weaken the effect of each other. The steady state thickness is optimally controlled using a multivariable control method. The dynamic response at each stand is improved by a new thickness and tension control sub-system in which the interaction is eliminate a by the non-interaction control. The low-order system based on decentralized concept facilitates parameters adjustment and system maintenance. This system has been applied to the tandem cold mill and the off-gauge length corresponding to non-permissible thickness deviation is reduced by more than 20 % compared with that before application.
