Research On Roll Gap Control Strategy Of Twin Roll Strip Vibration Cast-rolling

Copper aluminum composite plate has the advantages of good conductivity,excellent thermal conductivity,corrosion resistance,light weight and low price of aluminum,which is widely used in power system,electronic devices,machinery,automobile,daily necessities and other fields.With the advantages of short process,low energy consumption and low cost,composite casting and rolling technology has attracted a large number of enterprises and scholars to carry out relevant research,which has become an important research hotspot in the production technology of copper aluminum composite plate.However,there are still a series of problems such as crack,uneven structure and coarse grain in the strip produced by composite cast-rolling technology.Therefore,in view of these problems,Du Fengshan put forward a new technology of twin roll vibration cast-rolling for thin strip,which can refine the grain structure by vibration to improve the strip quality.However,because the vibration field of this technology is realized by the up and down vibration of one side roll,the frequency and fluctuation range of rolling force are higher than traditional cast-rolling,which brings some challenges to roll gap control.In order to ensure the precision of roll gap and grain refinement,the hydraulic screw down system and its internal control algorithm are designed and studied in this paper.By analyzing the characteristics of vibration compound cast-rolling process,the control strategy for copper aluminum composite cast-rolling was formulated to ensure the smooth preparation of copper aluminum composite strip.In order to reduce the influence of fluctuating rolling force on roll gap accuracy in vibration casting rolling process,the compatibility of valve control cylinder and the influence of back pressure were analyzed,and the schematic diagram of hydraulic screw down servo system was determined.In order to further improve the precision of roll gap control,tcfpso optimization algorithm is proposed to optimize the parameters of roll gap PID controller.The algorithm is realized by building a joint simulation platform of hydraulic screwdown system of vibration cast-rolling.After that,the mathematical model of valve controlled cylinder is established and analyzed.The influence of rolling force of different frequency and amplitude on the hydraulic screwdown system is analyzed,and further improvement is proposed.Based on the actual hydraulic screw down system of vibration cast-rolling,the step signal response experiment,hydraulic cylinder synchronous experiment,actual strip rolling experiment and microstructure observation were carried out respectively.The experimental results show that the hydraulic screw down system designed in this paper can ensure the grain size of strip structure is refined,and the roll gap control accuracy is also well controlled.In order to reduce the impact of rolling force mutation caused by liquid level instability on the roll gap control accuracy,this paper developed a piecewise PID control strategy,and verified the feasibility of the control strategy through the establishment of visual simulation platform.