Modeling And Analysis Of Bending Curvature After Snake Rolling Of Two-Layered Metal Clad Plate

As a strategic emerging material,metal-based composite plate has been mainly promoted by the country.In aerospace,military,automotive,chemical and coal machinery and other fields have a wide range of application needs.However,they face challenges such as low bond strength,bending after rolling and lack of theoretical models,which affect product quality and production stability.Snake rolling composite is a novel technique that inherits the advantages of asynchronous rolling composite and staggered rolling composite.It combines strong shear force and plate shape control capabilities with a new reverse bend zone for greater board shape regulation.Therefore,snake rolling composite has great potential in metal-based plate rolling composite field.This thesis is based on the National Natural Science Foundation of China: The contact behavior and coupled rolling with inter-pass cooling mechanism research for the snake/gradient temperature rolling of the metal clad laminate plate.To investigate the bending curvature of two-metal sheets after same-diameter asynchronous rolling and same-diameter asynchronous snake rolling,A theoretical analytical model of bending curvature after asymmetric rolling was established.The effect of different process parameters on the bending curvature of two-metal sheets after asymmetric rolling has also been studied,enriching the theory of asymmetric rolling.The main work in this thesis is as follows:(1)To study the effect of different roll offset,roll speed ratios,reduction rates,thickness ratios,working roll diameters and rolling temperatures on the bending curvature of two-metal sheets after rolling during the asymmetric rolling by finite element simulation.(2)According to the non-uniform distribution characteristics of the axial velocity along the vertical section direction in the deformation zone,a model of metal flow with additional flow functions was established;A near-real kinematic licence velocity field theoretical calculation model is developed from the kinematic characteristics of the sheet after rolling.By applying the first variational principle of rigid plasticity and the principle of minimum energy,a complete full power model of the deformation zone including internal plastic deformation power,shear power and friction power models is developed,with the optimised theoretical approach to obtain the optimal solution.Based on the calculated cumulative shear strain difference between the top and bottom parts of the rolling deformation zone and the cumulative axial strain difference between the top and bottom surfaces,a theoretical calculation model for bending curvature after rolling with the same diameter and speed asynchronous rolling was established.(3)The entrance boundary condition is modified to a parabolic shape according to the characteristics of the velocity distribution at the rigid-plastic boundary,on the basis of the asynchronous rolling.Based on the unique deformation zone of snake rolling,the boundary model,full flow function model and full power model were established.And optimally solving the full power model.On the basis of the bending curvature model for the same diameter and speed asynchronous rolling,the bending curvature of the back-slip zone and the additional back-bending zone are modelled,and a theoretical calculation model of the bending curvature after rolling of the same diameter and speed snake rolling is established.(4)In the same-diameter asynchronous rolling,The maximum relative error between the bending curvature of the finite element simulations and rolling experiments and the bending curvature calculated by the theoretical model is13.49% and the minimum relative error is 0.84%.In the same-diameter snake rolling composite,the maximum relative error between the bending curvature calculated by the theoretical model and the bending curvature of the numerical simulation composite plate is 13.82%,and the minimum relative error is-1.06%.