Study On Computational Model Of Thermal Crown Of Work Roll In Hot Strip Rolling

Owing to the restarting after changing rolls and stopping operation in hot striprolling, work roll is in an unsteady state for some time. In this state, the rolling processparameters are relatively unstable, which may easily result in the defect of tongue shapeon the head. Generally, the phenomenon of head thickness tolerance deviation of the stripat a distance of25meters from the head. For this, it is only useful for the main part andthe head thickness tolerance deviation can only be removed several meters for qualityassessment. In recent years, there has been a growing concern among customers on thequality of strip production. To improve flatness and thickness accuracy and achieve highyield, it is vital to study the feature of temperature distribution and thermal expansion andanalyze the effects of rolling process parameters on temperature distribution and thermalexpansion of work roll in this stage. The main researches are as follows:1) According to heat transfer mechanism, a computer model based on finite elementmethod is developed to calculate the heat transfer equation in axial direction underunsteady-state conditions. ANSYS finite element analysis software is used to establish aplane finite element model of work roll, which does not include back-up roll and stripwhose effects on work roll are corrected by cyclic evolution of heat transfer coefficient.2) It utilizes thermal-structural coupled method, associates with the practice of1700mm hot strip rolling in a domestic factory and optimizes thermal boundaryconditions reasonably. Cyclic evolution of thermal loadings is applied on the model, andthen the results of simulation are compared with the measured data by Stenvens P G. Itindicates that the model and the method are practical.3) Based on the above model, effects of work roll material, work roll diameter,rolling process parameters on work roll temperature distribution and thermal expansionare studied, which will provide theoretical foundation for compensation control ofthermal crown to optimize gauge and profile control.