The Research On The Flatness Control System Of The Five-stand Tandem Cold Rolling Mill Of Tangshan Steel

Flatness is a key quality indicator of cold-rolled strip steel and also an important factor to determine their market competitiveness. With the rising demand of improvement on strip's flatness quality from the industrial users like automobiles, light industry, household appliances and electric manufacturing etc., flatness control technology has become one of the core technologys on cold-rolled strip steel production and is another development&research issue in countries all over the world after the development&research of thickness control technology. Using high-performance computer control system to improve the mill's control technologys is an important way of improving the cold-rolled strip's flatness quality and economic benefit.Taking the Five-stand Tandem Cold Rolling Mill of Tangshan Steel as the researched object, this thesis analyses the cause of flatness defects, the factors resulting in flatness measurement errors, and the principles of flatness measurement and control in cold rolling, and researches the components, the interfaces, the scheme of flatness measurement and control, and the control effects of the flatness control system. The flatness control results show that the flatness control system runs stably and its control precision is high, and it can guarantee sufficiently the flatness quality of strip products.The main research contents of the thesis are as follows:(1) The cause of flatness defects. Flatness defects are created by a mismatch between the strip profile and the loaded roll gap profile. This mismatch results in uneven reduction across the strip width, producing an uneven strain profile across the strip.(2) Flatness measurement errors analysis. Factors, such as flatness measurement meter calibration, measurement range limits of flatness measurement meter, strip temperature distribution, misalignment of equipments related to flatness measurement, surface defects/ bending of flatness measurement roll etc.,will all have impact on the flatness measurement accuracy.(3) The structure and control scheme of high-precision flatness measurement and control system based on the optimal control algorithm.The thesis is structured as follows:The exordium introduces the importance and necessity of researching and designing high-performance flatness control system of Tandem Cold Rolling Mill, the development of flatness control technology, the source and research contents of this researched subject. The second chapter introduces the theoretical research on the flatness control in cold rolling. The third chapter introduces the compositions and interfaces of the flatness control system of the Tandem Cold Rolling Mill. From the fourth to the fifth chapter, the thesis introduces the realization of flatness measurement and control of tandem cold-rolled strip steel.The sixth chapter gives the effects of flatness control and presents the conclusion.