Experimental Study On Measuring And Control System Of Pneumatic Strip Flatness Rolls And Basic Theory Modeling Of Strip Flatness

Strip flatness is the main quality standard. Following the improving of the quality of strip thickness, the request to the one of strip flatness is higher and higher. Flatness control becomes the important technique's developing direction of the modern high-precision rolling mill. Flatness measuring, pattern identification, flatness control theory and mathematical modeling are the theory base and the key problem of the flatness control. Currently, only foreign companies, such as Siemense and ABB, can explore the flatness closed-loop control systems, which are applied in the practical flatness control. Domestic flatness control and measuring lies in the research phase. The dynamic characteristic of the pneumatic flatness measuring rolls is calibrated again on the base of the seven-segment pneumatic flatness measuring roll explored by the research group led by Professor Wang Yiqun. It adopted the method of optical fiber phase Correction Compensation to eliminate the circle error of the measuring rolls and perfecting pneumatic flatness measuring equipment. On this base, Virtual Instrument LabVIEW is used to explore the software system of pneumatic flatness measuring, which realizes the on-line measuring. Aimed at the characteristics of modern rolling, on the base of the pattern recognition based on fuzzy classification theory, the result of the pattern identification is optimized, combining with the Particle Swarm theory and simplex method, which reflects the real flatness state better. By the computer Ethernet communication technique, the result of the flatness pattern identification can be transmitted to the automatic gauge control system of the 300 4-roll reverse rolling mill which can realize the flatness closed-loop control by the bending equipment and the incline roll equipment. As the bending system is the key technique of the flatness closed-loop control, its dynamic and static characteristics are important for the performance of the flatness closed-loop control system. Aimed at its characteristics of nonlinear, time-variant and uncertainty, Fuzzy Self-adaptive PID is designed in bending system for improving the adjusting role of hydraulic bending system on flatness and dynamic characteristic of the rolling mill.With the development of the computer technique, the technique of the virtual simulation increasingly becomes the important constituent of the system design and simulation. Virtual rolling technique has important practical values for learning the performance of the system, improving the control technique and studying the technics process. It can provide the technique support and the simulation experiment environment for the design of modern rolling mill and rolling mill modification, and it also can explore the new characteristics of the current rolling mill and improve technics parameters to improve the quality and the output of the product. Considering the influence such as nonlinearity of servo valve, the hydraulic cylinder position, rolling power and bending power on the flatness, this subject builds the model of hydraulic screw-down system and the bending system. According to the whole flatness theory, strip metal transmutation model, rollers elasticity transmutation model and rolling power model are built respectively. To improve the simulation velocity, strip 3-dimension metal transmutation model is simplified. The influence function method is applied on rollers elasticity transmutation model, which is used widely in the practice. On the base of the model above, a whole virtual flatness control system is built...