Retrofit Design On Thickness Control System For Jingtang 2230mm Continuous Cold Roll Mill

Thickness is an important indicator of cold roll products,each production line is concerned about it and improving the accuracy of thickness control.Model preset is a process description of rolling,which reflects the requirement of the external conditions during strip deformation,and directly influences the accuracy of the thickness control.AGC system is a real-time description of rolling,which is used to eliminate the deviation between the actual state and the model preset during strip deformation,also is the key of anti-interference performance of the thickness control system.In order to obtain a higher level of thickness control accuracy,it is necessary to start with above two aspects.Two main problems:strip break during high strength steel roll and scrap cut loss caused by strip head and tail thickness deviation being too much,happened on Shougang Jingtang 2230mm continuous cold roll mill.Taking care of the theory of the thickness control and the requirements in the process of practical production,this thesis retrofits and design the original system.The main work is as follows.At first,analyzed line structure,system composition,equipment parameters of 2230mm continuous cold roll mill,and studied on the control system.Analyzed problems existed in thickness control system during production process on the basis of that.The results of correlation analysis show that the main reason for the thickness control problem include rolling force preset not accurate,high strength steel FGC(Fly Gauge Control)process anomaly and AGC(Automatic Gauge Control)system control capacity is not high,etc.Secondly,contrapose problems above,make the corresponding countermeasures and corresponding modification of the thickness control system.(1)the deformation resistance calculation factor inaccurate result in rolling force calculation is not accurate,adjust the steel grade family and deformation resistance calculation factor to solve this problem.(2)FGC start point is in weld during high strength steel rolling that lead to FGC process abnormal,change start point to the front of the weld to solve this problem.(3)Stand 1 mass flow AGC thickness deviation calculation problems,solved by adjusting the thickness deviation calculation period.Controller response is slow,dynamically adjust the gain according to the thickness deviation value to improve response speed.Stand 2 feed-forward AGC adjustment ability is not enough,by increasing the compensation to make it perfect.Stand 4 monitor AGC has very serious hysteresis,increases the differential control to reduce the effects of hysteresis.Tension AGC can't play a proper role because control dead band is too large,solved by modified tension dead band.The retrofit scheme are implemented in the actual system,the practice production shows that the time of strip break during high strength steel rolling decrease,scrap cut loss caused by strip head and tail thickness deviation decrease,which achieve anticipated goal for retrofit design.