Combined Analysis Of Vertical Rolling Force In Rough Rolling With Slip-line And Slab Method

With the rapid development of industrialization and urbanization in China,there has been a significant increase in demand for high-quality hot rolling strip products across industries,in actual production,in order to improve the quality of hot rolling products,the width of hot rolling slab is usually controlled by means of alternating between vertical rolling and flat rolling.In the process of vertical rolling,due to the width to thickness ratio of steel slabs is very high,plastic deformation is mainly concentrated on the edge of slabs,the cross section of the slab formed as a dog-bone shape.Currently,the formulas which are used to calculate the rolling force in vertical rolling are all based on the horizontal rolling processing.When they are used,they will be added by some increment.Because of the differences between vertical rolling and horizontal rolling,this method often leads to obvious errors between predicted value and measured value of vertical rolling force.After these formulas are used in field,a lot of time is needed to the self-learning.The empirical formulas summarized in the rolling field can not give the mutual restriction relationships between the rolling parameters to meet different conditions,and numerical models are difficult to program for automated production systems.Therefore,the development of an analytical model of vertical rolling force with rolling theories support,strong resolution and good programmability has practical significance for hot rolling strip production.Based on a deep understanding of the principle of the dog-bone shape and the deformation characteristics in vertical rolling,slip-line and the combination of slip-line and slab method is firstly proposed to analyse the vertical rolling force in present paper.The main research contents are as follows:(1)In the process of studying vertical rolling,it is noticed that vertical rolling satisfies the characteristics of plane deformation,so it is known that slip-line is suitable for analyzing vertical rolling under stable rolling conditions.On the basis of this condition,rigid and plastic areas of the rolled piece were divided;Slip-line Field and hodograph were drawn out.(2)Analytical solutions of vertical rolling force,rolling torque and rolling power were deduced with Hencky stress equation.Accoording to geometrical of Slip-line Field of the plastic area in vertical rolling and incompressibility condition,the maxium depth and average height of dog-bone deformation area were calculated.Compared the calculated value with measured data in field,accuracy was in a good agreement.(3)Combined with the maxium depth of dog-bone deformation obtained by Slip-line,used slab method to establish static equilibrium differential equation along the altitude in deformation area with yield criterion to deduce the analytical solution of vertical rolling force,and analyzed the physical significance of this vertical rolling force model.(4)Built FEM model in vertical rolling based on the platform of ANSYS/LS-DYNA.Obtained the solution of simulation by using LS-PREPSOT,summarized the deformation law of vertical rolling and compared with the analytical solution obtained by combined solution in this paper,the error is small,verified the physical significance of this rolling force model.The vertical rolling force obtained by the combined solution in this paper and the measured data in strip hot rolling field has been compared.The error of the comparison results is within 10%,and the precision can satisfy the requirement of production control in a strip rolling plant.