Papers by Author: Dian Hua Zhang

Abstract: Coiling temperature of hot rolled strip is one of the important parameters which affect performances of hot rolled strip. The control of coiling temperature is highly nonlinear and time-varying. Based on the laminar cooling control system of a hot rolling plant, a coiling temperature prediction model based on BP neural network was established. Many factors which affect coiling temperature control were taken into account, and the BP neural network was trained by actual production data. The simulation was carried out, which indicates that coiling temperature can be predicted precisely, and the BP neural network model has the prospect of online application.

Abstract: The process control system for tandem cold mill is the core of the production line control system. Its operating status influences the stable production of strip directly. In this paper a tandem cold rolling process control system of cold-rolled sheet plant was taken as an object, the structural framework of control system was designed, the composition and function was introduced.

Abstract: A 1450mm cold rolling mill roll stepped cooling control technology has been studied. The basic principle of stepped cooling control has been analyzed. The important role of stepped cooling control in the control of thermal crown has been elaborated. In order to analyze impact of stepped cooling on the sectional shape of the strip, the roll under the influence of the cooling water temperature field has been established. The model of optimal cooling capacity in each segment has been established. The model has been successfully applied to a 1450mm cold rolling mill roll, and a good effect has been achieved.

Abstract: The influence on the shape of the strip from rolling force fluctuations has been analyzed. The combination of intermediate roll bending and work roll bending has been adopted. The principle of rolling force feed-forward control has been analyzed. The feed-forward control model has been established on the basis of neural networks. The model has been successfully applied to a rolling mill and a good effect has been achieved.

Abstract: Using the characteristics of prediction model, rolling optimization and feedback correction, a AWC system based on generalized predictive control was designed, and its control performance was simulated based on a hot strip continuous mill. The results show that generalized predictive controller achieves better control effects than the normal PID on response time and steady precision with matching model; when model mismatching is caused by inaccuracy of plastic coefficient and pure delay time, the normal PID is overshot or even oscillation, but the control performance of the generalized predictive controller is not influenced by model parameter variations .

Abstract: The hot rolled strip thickness accuracy sometimes can not be guaranteed after a long time for waiting for slabs or other reasons. The reason is when rolling, the rollgap adaptive model has considered the thermal expansion of the roll. So when rolling is restarted, thermal expansion of the rolls must be cleared in order to accurately calculate the setup rollgap value. The finite element software ANSYS is used to calculate the temperature field and thermal expansion amount of the rolls in the rolling process. Application results show that this method can improve the accuracy of strip thickness.

Abstract: Thickness model adaption plays a important role in obtaining strip with high thickness precision. In order to improve the thickness precision, a complete thickness model adaption system has been designed for every specific model used in the setup system including gap position model, temperature model, rolling force model. Snapshot data and stretch equation are used to adapt gap position. Forced convection coefficient is selected as adaption parameter. A deformation resistance-based fitting quadratic curve is proposed in rolling force adaption, it can be inherited to any other thick range class and a quick thickness adaption method is introduced. Application results show that this adaptive system is with high accuracy, quick adaption and high stability.

Abstract: In order to improve the setting accuracy of rolling force model, a comprehensive parameters adaptive objective function of rolling force was established. During the adaptive process, the adaptive coefficients of friction coefficient and deformation resistance were taken as the optimized parameters, and the Rosenbrock algorithm was used to search the optimal solution of the objective function. The proposed adaptive method has been applied successfully to a 1450mm 5-stand tandem cold mill. Application results show that the forecast accuracy of rolling force model has been improved significantly.

Abstract: In accordance with the feature of pure delay in monitor AGC system for hot rolling mill, a new self-tuning PI Smith prediction controller based on chaotic particle swarm optimization (CPSO) is developed. The algorithmic principle and design method of new controller are given. Based on the typical monitor AGC model of tandem hot mill, the analysis of dynamic performance for traditional PI Smith prediction controller and CPSO self-tuning PI Smith prediction controller is done by MATLAB. The simulation results indicate that CPSO self-tuning PI Smith prediction controller has faster response and higher static accuracy than traditional PI Smith prediction controller.

Abstract: The HOFC (High Order Flatness Control) work roll curve was designed using Matlab. It has great flatness control ability, for the roll diameter in the position of the 1/4 roll length can be altered with the changing of angle and index parameters. Combined with the data from a hot strip factory, the elastic deformation of the HOFC work roll was analyzed following the influence coefficient method. The distribution curves of the exit thickness, roll force, work roll bending, pressure between rolls, roll flatting, and roll gap geometry were given under the conditions of different roll parameters. Results show that the HOFC work roll curve can eliminate the high flatness defects, reduce the edge drop, improve the lateral thickness uniformity, and maximize the available cross section of the strip effectively.