Study On Hydraulic Auto Gauge Control System Of Twin-roll Continuous Caster

The thickness accuracy and shape accuracy of steel strip are two key quality performances of steel strip. They are greatly improved due to the progress and application of roll theory and control theory. Automatic Gauge Control (AGC) is one of the two key technologies in the rolling field and directly affects the quality of strip products. Twin-roll steel strip casting is a new steel-strip production method of representing the steel industry tendency. Thus, research on AGC system has important theoretical and practical significance.The basic theory about AGC used in rolling mill is scrupulously studied in the paper, based on an overview of the present status and perspectives of AGC technologies. The paper also discusses the basic theory about rolling process, including elastic equation of rolling mill, plastic equation of rolled piece, elastic-plastic curve figure and gauge aviation equation etc. The modes of AGC are studied in detail, such as thickness AGC, pressure AGC, front feedback AGC, tensional AGC, monitor AGC, mass flow AGC. After analyzing features and fields of application, the paper point out that one or more modes should be used in the AGC system, considering the type of the rolling mill and accuracy requirements of products. Moreover, it analyzes the controlling modes of pressure AGC, which frequently used on rolling mill, including BISRA mode, decoupling set mode, gauge meter mode, dynamic set mode and PID gauge meter mode, gains the characteristics and dynamic behaviors of them, which provides fundamental basis for the design of AGC system.The hydraulic AGC system of the twin-roll caster has been designed, based on the studies and analyses mentioned above. It contains two parties: a hydraulic system and an electric control system. An electro-hydraulic position servo control system is used in the hydraulic system, which can press down the roller quickly and accurately to control the roll gap. The hydraulic system is the body of the wholly AGC system. According to the present status of the modern industry in and the characteristics of AGC system, the electric control system adopts two-level computer control structure: process automatic system and basic automatic system. The control strategy combines pressure AGC and monitor AGC. In the end, using the classical model building theory, the mathematic model has been established. Based on the model, the paper analyzes the dynamic behavior of the electro-hydraulic servo system.