Thermal Boundary Condition Inversion Of Strip Controlled Cooling

Controlled rolling and controlled cooling technology is one of the greatest achievements of the steel industry in twentieth Century.The controlled cooling technology can not only improve the output of steel strip,but also can keep the toughness of the steel strip,improve the steel strength,and thermal boundary conditions are very important parameters in the controlled cooling process,which directly affects the temperature distribution of steel strip.Inaccurate control of the temperature will cause the residual stress on the strip surface,reduce the surface quality,in the coiling stage,the control temperature is too high prone to adhesion,the control temperature is too low will lead to increased coiler power consumption.Therefore,it is an important branch in the research of iron and steel rolling to study the cooling boundary condition.It is difficult to directly measure the heat transfer boundary condition of strip cooling.According to the Inverse Heat Transfer Problem(IHTP)method,the thermal boundary condition of strip cooling is determined according to the local measurable temperature information of strip,which is an effective technical program.According to the present situation of research on inversion of boundary conditions of controlled cooling heat transfer and the main problems,this paper adopts the dynamic matrix control(Dynamic Matrix Control,DMC)inversion algorithm on strip heat transfer boundary conditions,and on the basis of the reconstruction of strip temperature distribution.The main work of this paper includes:(1)The mathematical model of cooling and heat transfer process is analyzed and established.The finite element method is used to separate the differential equation of heat conduction.The algebraic equations are used to solve the algebraic equations.The influence of different meshing on the temperature distribution of strip was analyzed by numerical simulation.(2)In this paper,the basic idea of DMC method is introduced.Combining with the control of cooling and heat transfer process in the second chapter,the surface heat flow of strip is the parameter to be inversion,and the DMC is used to control the cooling and heat transfer boundary condition Program.Based on the above inversion scheme,the reliability of the inversion results of the strip surface heat flow is enhanced without the assumption of the specific function of the surface heat flow in the future period.(3)Based on the simulation of the surface heat flux inversion,the distribution of temperature field is reconstructed.The influence of temperature measurement error,future time step and the position of measuring points on the inversion accuracy and temperature distribution are discussed.The simulation results show that the DMC inversion method can realize the effective inversion of the surface heat flow of the strip.The result of the satisfactory future boundary condition can be obtained by using the smaller future time step,which reduces the dependence of the inversion result on the future time step The DMC can obtain better inversion results in a certain range of temperature measurement error,indicating that the established inversion scheme has certain resistance to ill-posedness.In addition,the position of the measuring point has some influence on the inversion result,and the inversion result is worse when the measuring point is far from the inversion point.