Flatness Control System And Finite Element Simulation Of Control Efficiency For Cold Rolling

Based on the automatic control system research project for a 1450mm pickling and tandem cold mill,the flatness preset control model and related compensation control model were built.On the basis of control efficiency of flatness actuators,the optimal multi-variable flatness closed-loop feedback control model and feedforward control model have been built.Take the UCM mill as research object,the elastic-plastic finite element and dynamic explicit algorithm were used to analyze the cold strip rolling process.The main work is as follows:(1)The flatness target curve model based on flatness control,crown control as well as requirements of subsequent processing has been developed.Moreover,the basic flatness target curve based on strip instability criterion has been developed.According to the rolling process and equipment condition,compensation models such as coil shape,edge drop,temperature difference across strip,manual adjustment of flatness actuators have been development.According to incoming material situation and status of mill,the target and actual roll gap crown have been calculated.Combined the influence function of the flatness actuators for the roll gap,the set values of flatness actuators have been calculated.(2)According to characteristic of UCM mill flatness actuators,the control strategy which can calculate the adjustments of the actuators dependent on flatness deviation in the relay manner has been formulated.Flatness controlling efficiency of work roll bending and intermediate roll bending has been analyzed.Subsequently,based on the control efficiency of flatness actuators,the optimal multi-variable flatness control algorithm through least square method has been developed.Eventually,the feed forward flatness control strategy has been established,which use the work roll bending force and intermediate roll bending force to compensate the influence of rolling force fluctuation.(3)The theory of finite deformation elasto-plastic finite element method was discussion.Take the cold rolling process as the object,using the actual process parameters,the sheme of mesh quantity and distribution strategy of roll system and strip have been formulated.After setting the material mechanic property parameters of roller and strip,the tension and bending roll force load application method was given,and the 3D finite element model of strip cold rolling process has been developed.(4)The simulation results of FEM model and field production data have good fitting degree.With different work roll bending force or intermediate roll bending force,the 3D distribution of rolling pressure in the contact zone and the strip transverse were achieved.The pressure distribution between rolls has been got,and the effect of flatness actuators on pressure distribution between rolls has been discussed.(5)According to the simulation results,the thickness distribution along cross-section of the strip in different working conditions has been analyzed.The effect of flatness actuators on strip crown and edge drop has been discussed in detail.The horizontal strip thickness distributions with different values of flatness actuators have been obtained,the flatness controll efficiency curves were achieved,and the effect of flatness actuators' regulating quantity on flatness controll efficiency curves were been discussed.The results of the study are practical for flatness control of cold rolling mill.The study has certain significance to the development and optimazition of flatness control system.