FEM Simulation Of Rough Vertical Rolling Process And Research On Double Parabolic Dog-bone Model In Hot Rolled Strip

With the rapid development of continuous casting and rolling technology, continuous casting billets are widely used to adapt to the fierce market competition. However, it is difficult to change billet width online. The vertical-horizontal rolling is usually used in roughing trains to adjust and control the slab width. Because of the high ratio of width to thickness, the deformation of slab is mainly restricted in a small zone on the edge, so the cross section of slab appears double drum apparently after vertical rolling, and then the dog-bone shape is formed.The double parabolic dog-bone shape model for vertical rolling is firstly proposed in this paper, and the analytical solution of shape parameters and rolling force are obtained. The double parabolic model is significant to width control and prediction of rolling force in vertical rolling.The main research contents are as follows:(1) For the deformation characteristics of dog bone shape after vertical rolling, effect of reduction rate, initial thickness, roll diameter, initial width, and roll rotation speed on dog-bone shape are researched. The models of dog-bone shape in different research conditions are given according to the analysis of the three methods experimental regression, FEM and theoretical study.(2) FEM model in vertical rolling process is built based on the platform of ABAQUS. The solution of simulation is obtained by using ABAQUS/Explicit solver. The deformation of slab is mainly restricted in a small zone on the edge according to the changes of the stress-strain, displacement contour, the curve of rolling force and node velocity with time.(3) The double parabolic dog-bone shape model and corresponding velocity and strain rate fields are firstly proposed based on the incompressibility condition and stream function. The Mean Yield Criterion, integral mean value theorem, and the co-line vector inner product method are used respectively in integration of plastic deformation, shear and friction powers based on the first variation principle of rigid-plastic material. Then an analytical solution of slab total power in vertical rolling is obtained. Finally, the power and shape parameters are received by minimizing the power functional.(4) Based on double parabolic model, the computing system of prediction dog-bone shape parameter is developed using Visual C++/MFC. Comparing double parabolic model with FEM simulation’s, Yun’s and Okado’s models, the accuracy of the power and shape parameters predicted by double parabolic model is verified under different engineering strain, initial thickness, and roll radius. The prediction error of the double parabolic model is less than 7% compared with that of FEM simulation, Yun’s and Okado’s model. The complete profile of slab at exit is provided, and then analytical rolling force and the shape parameters in vertical rolling are predicted easily and quickly by using double parabolic model in different production conditions.