Design & Research Of The Hydraulic Servo Control System In Hot Strip Rolling Looper

In the hot strip rolling mills, the constant tension between racks is usually maintained by looper.The looper is a machine which has free rolls, and this free roll will rise to be higher than the rolling line when the strip goes through the work rolls. The strip's tension and the looper's rise are monitored continuously. When the looper achieves the target position, the control system will make the tension between the racks to achieve its target value. If the tension achieves its target value when the looper still deviates from the target position, the rate of adjacent rack's roller needs to be adjusted.At present, there are few hot strip rolling mills designed by domestic heavy machinery manufacturers independently. Research on the looper device for hydraulic servo control system is not intensive. Due to great economic benefit and social benefit brought by this machine's design, use and reconstruction, domestic manufacturing enterprises should master the technique of the equipment's design and have the ability of independent research and development. As a result, China National Erzhong Group Co. together with Chongqing University took on the research to solve fundamentally the basic design difficulty of looper device hydraulic servo control system, which aimed to promote the design ability of our company and provide theory backing and technical support. This paper focuses on the overall performance of the hydraulic servo control system of this hot strip rolling mills looper device and puts emphasis upon three parts as follows:â‘ Analysis of the operational principle and load model of the hydraulic servo control system of the looper installation.By analyzing the looper rotation device, the working principles of the control system were made out; by analyzing the load model of the device, the relationship of the displacement between its rotation angle and fuel tanks and the displacement between the loaded and fuel tanks is found to be nonlinear; Because of the needs of classical control theory, the nonlinear model will be changed to be linear by using the method of regression analysis. The analysis demonstrated that control system can be divided into displacement control loop and pressure control loop.â‘¡Establishment of the of hydraulic servo control systemThe hydraulic servo control system of the looper devices was simplified. Corresponding mathematical models of this system's load, servo amplifier, hydraulic servo valve, hydraulic cylinder and displacement sensor are established and some transformations are made. Mathematical model of the control system was ultimately made out.â‘¢Dynamic simulation of the hydraulic servo control systemDynamic structure map was drew by using simulation software MATLAB toolbox, dynamic simulation parameter was identified according to the practical conditions, and simulation curve of the hydraulic control system of the looper control device was also obtained. Research was made on the stability, rapidity and accuracy of the control system. At the same time, main parameters were changed and simulated and the main factors which impact the system's dynamic characteristics are identified.Results of this research provide a theoretical backing and guiding to the design of looper device of the hot strip rolling mills and it also makes great sense to application. The results of this research have been successfully used in the design and study of hydraulic servo control system of looper device in China National Erzhong Group Co.