Research And Development Of Flatness Control System In Cold Strip Rolling

This paper was based on the strip shape control core technology for self develop and its industrial application project of1250mm cold rolling mill in Anshan Iron&Steel Corporation. Flatness control systems of six high rolls have been thoroughly studied. Aiming at the flatness feedback control model have been built. Good flatness control ability and reliable control stability of these models were proven by industry experiments and online application. The main works are shown as follows:(1) Flatness control systems of1250mm cold mill in Anshan Iron&Steel Corporation has been studied and analyzed. The hardware architecture and software architecture for flatness control system were established.(2) A special mathematical model is built up to calculate the efficiency function of actuators under the condition that wide thin strip is rolled. In this model, the coupled impacts between roll deformation and strip deformation are considered. Roll deformation is calculated by influence function method, and strip deformation is calculated by revised three-dimensional difference method.This paper present a detailed theoretical analysis of asymmetry bending roll,finally contrast and analyze applied effect in the practice.(3)The dirtributed computer control system was established in the flatness real-time on-line control. The flatness control system consist of embedded industry controller; the industry process control computer; the level II control computer; the flatness meter computer; DSP applied in signal processing; the data acquisition computer; the data server; PLC+FM458and so on. The industral Ethernet protocol and Profibus protocol were used in different computers communication for flatness control system.(4) The target curve setting model of flatness control system was established based on control pattern recognition and steel-roling process requirements. The strip target shape was compensated and corrected based on the influence of edge drop on strip shape; the influence of the manual include compensation curve of predcessor’s works. The target shape control precision can be improved by using these models. (5) The online control mathematical model of flatness was established based on actuator efficiency function. The actuators eddiciency optimizing function model was developed. The collaborative work was based on multimedia flatness actuators. The actuarors include in tilt; the work bending roll; the intermediate bending roll; the intermediate roll shift and work roll segments spray colling,etc. The flatness control capability was improved and the functional of flatness control system was optimized by using this model.(6) The Smith predictor model and dynamic gain control model were developed. The different control modes were used under different rolling techniques aiming at the delay characteristics faltness control system. The characteristic response of flatness control system and the actuator adjust time were improved through the two control mode compared with the traditional PI control.(7) Industry experiments were carried out to validate and analyse the flatness control results of these models that have been built up in this paper. The industry experiments and practical application results showed that the flatness control effects of feedback control were improved, and good strip shape was obtained by applying these models. The industrial application software of flatness control system were developed. The strip shape quality reached71in1250mm mill by using those models, and0.18mm ultra-thin strip was produed in1250mm mill.The present paper was focused on the flatness control models for six high mill. It can provide great help in theory and practical application to the development of flatness control system of six high mill.