Study On Control Technology For High Speed Film Casting Machine

The film casting machine is a kind of complex mechanical equipment, and its development direction is high speed, intelligent and high accuracy. In recent years, the capacity of manufacture of the domestic film casting machine has improved a lot, but when it compared with the international advanced technology, there is still a gap in the key indexes such as the intelligent operation, the winding speed, the error of film thickness and the width of film, etc.To improve the production efficiency of the film casting machine and ensure the width of film, the layer of film and the high stability, it is important to solve those problems that constrain the speed of the casting machine. The problems mainly contain the multi-motor synchronization control, the tension control when film is winded in a high speed, and the error control of film thickness. They are the common problems that exist in the designing of film casting machine at home and abroad, and mastered not enough in the domestic production currently.The research object of this dissertation is the high speed film casting machine, and the aim is to establish its automatic control system, to research the interrelated control technologies, and to design the control system.The main reseach contents of the dissertation are as follows:(1) Multi-motor speed synchronization controlTo solve the problem of multi-motor speed synchronization in film casting machine, an improved adjacent cross-coupling structure fuzzy PID control algorithm is proposed. The adjacent cross-coupling structure is improved, the control parameters are redefined, and equations of the redefined parameters are established. Also, to solve the time-varying and nonlinear problem of the motor model, fuzzy PID controllers are designed and added to the improved adjacent cross-coupling structure. Based on the theory of fuzzy inference, fuzzy PID controller is designed, which is combined with fuzzy controller and PID controller.(2) Tension control when film is winded in a high speedAccording to the dynamic process of the winding system of the film casting, the dynamic relationships of tension and speed, radius, rotate speed are analyzed, and the compensating law of the radius and the rotaty speed are calculated. Based on the models, a tension control system is established. The speed closed loop is formed by controlling the difference of speed, the tension closed loop is formed by controlling the winding speed using BP Neural Network PID controller, and a compensation is added to the winding speed according to the mechanical structure of the system, so the tension can maintain stability in the whole winding process.(3) Accuracy control of the film thicknessThe dissertation establishes a set of control system for the film thickness, using the technology of virtual instrument. It integrates the data-collection cards and the control cards to the computer, uses the Labview software to compile the visual monitoring procedures, and uses the neural network intelligent control algorithm to ensure the accuracy.(4) Establishment of the casting machine’s control systemThe control system of the high-speed film casting machine is established, the software and hardware are designed, and the subsystems of the multi-motor speed synchronization control and the winding tension control are designed. The control system has the characteristics of real-time, standardization, modularity, etc., provides sufficient resources of hardware and software for the study of next-generation casting machine, and has an important reference value for the common real-time multi-task control system. Based on it, the whole performance of the control system, the improved adjacent cross-coupling structure fuzzy PID multi-motor proportional synchronizition control algorithm and the winding tension control algorithm are verified by experiments. The results show that the proposed control algorithm has high accuracy and stability, which has great significance to improve the quality and the whole dynamic performance of the casting machine.