Research And Application Of Hydraulic Looper Control System In Hot Rolling Mill

In process of hot rolling, the control accuracy of looper height and strip tension is the key which determines the strip properties. The background of this paper is an international cooperative project named "Mathematical modeling of hydraulic looper and Analysis of dynamic characteristics of looper-tension in hot rolling", which is commissioned to the State Key Laboratory of Rolling and Automation Northeastern University by South Korea’s POSCO firm, with the looper control system of finishing mills as a study. It introduces the looper control procedures of the production line, analyses the fundamental principle of looper height control and strip tension control and establishes the coupling mathematical model of looper height and strip tension. Then, in combination with the co-simulation technology which is based on MATLAB and ADAMS, the conventional control method and noninteracting decoupling control method are used in studying and analysing the control system. The main works and results are as following:(1) The development of looper height and strip tension control technology is introduced associating with the hot strip producing process and the rolling technology. Object to the steady stage in hot rolling process, the control principle of looper height and strip tension are deeply studied.(2) Based on the mechanism causing strip tension, the coupling mathematical model of looper height and strip tension control system is established. By Laplace changing method, the transfer function of the looper multivariable control system is deduced, therefore the basis of simulation and the study of control methods is formed.(3) The looper height and tension control system is a typical double-input and double-output multivariable control system. Based on the coupling mathematical, the Simulink simulation tool of Matlab is used to study the coupling and decoupling control system of looper height and strip tension. The simulation results show that, compared with the conventional control system, the decoupling control system can greatly reduce the coupling characteristic of looper height and strip tension.(4) In order to have a further research on the electrical and mechanical performance of hydraulic looper system, the co-simulation strategy based on ADAMS and MATLAB is put forward. The mechanical model is established by ADAMS and the control algorithm model is established by MATLAB. So the co-simulation can be finished smoothly by defining output and input interface. Test shows that the virtual model established by ADAMS can be well close to the actual physical model, which can simplify the modeling process and provide a reliable basis for physical prototype test.