| One of the key factors influencing the product quality is strip crown in hot rolling aluminum strip and the thermal effect of work-roll is the important factor in the process of the theoretical research. The exsiting control techniques have higher requirements on the basis equipment of hot rolling mill, which are suitable for advanced production line of hot rolling aluminum strip. And the equipment investment is high. In addition, the enterprises producing hot rolling aluminum strip are small or medium in the domestic and the equipments are relatively backward. Therefore, the control method of strip crown with simple, economic and high precision is very necessary.On the basis of theoretical and experimental study, the indirect method of measurement and control of hot rolling aluminum strip crown was put forward. And the purpose of detection and control of strip crown was achieved by used this method on the two-high hot rolling mill. The main research contents are as follow:(1) The fluid-thermal coupling model was established based on the theory of turbulent jet theory. The structure of cooling system was optimized based on the research on convective heat transfer characteristics between work-roll and fluid. And on this basis, the segmented cooling system was developed, including the designed of the straight-pilot solenoid valve and the structure of segmented cooling control system. In addition, the capacity of cooling system is verified by the specific test.(2) The thermal effect of work-roll was studied. The three-dimensional temperature model of work-roll is set up based on finite element method. And the thermal effect of work-roll in the rolling process and the intermittent period, the influence factors such as cooling fluid flow, rolling speed and the cooling fluid distribution were researched. In order to improve the model calculation precision, the strip deformation heat and friction heat were considered in studying the contact heat transfer coefficient between work-roll and strip, the convective heat transfer coefficient between work-roll and cooling fluid was concluded by finite element analysis, and the temperature of work-roll and strip was obtained by measuring temperature system.(3) Considering the temperature features influenced by cooling fluid and aluminum oxide film of work-roll surface in the production of hot rolling aluminum strip, and based on the principle of infrared sensor, online temperature monitoring system of work-roll and aluminum strip were developed, which included design of the mechanical structure and control system.(4) The indirect detection method of hot rolling aluminum strip crown was put forward based on the artificial neural network theory and the developed of work-roll temperature measurement system. Considering the convergence rate and prediction accuracy of the model, the adaptive PSO-BP neural network model was developed. And the prediction model of hot rolling aluminum strip crown was set up by using actual rolling parameters for the training sample. Finally, the purpose of indirect detection strip crown was achieved according to the work-roll temperature and the related rolling parameters.(5)The segmented cooling closed-loop fuzzy control system was developed based on fuzzy control theory, the goal of which was work-roll temperature presetting model, work-roll temperature online detection was used as the feedback loop, and segmented cooling system was actuators. On this basis, as well as the theoretical analysis of affecting factors on strip crown, the indirect control method of strip crown was obtained. This method was applied to the actual hot rolling production, and the effectiveness was verified by specific field test. |
