The purpose of this study Is to develop a three-dimensional coupled thermo-elastic-plastic finite element model of nonisothermal rolling and analyze the strip curvature caused by the difference in the heat transfer boundary conditions of the upper and lower rollers. The difference in the rotation speed between the upper and lower rollers was utilized in an attempt to correct the aforementioned curvature in hot rolling due to unsymmetricai cooling conditions. In addition, the changes in shape, temperature field, and strain field of the strip during the various stages were analyzed and can be used to obtain the lateral plastic flow of the strip. As for the aspect of heat transfer, the various possible boundary conditions in the actual hot rolling were considered, which include the convection boiling of the air and water, and the radiation loss. Then, the three-dimensional finite difference heat transfer equation is derived according to the concept of heat balance. As for the determination of the direction of tangential friction force, this study also developed a modification algorithm to adjust to the three-dimensional rolling process. After a comparison with the experimental data in Ref 8 and IS, and the simulated temperature distribution In Ref 17, the partial results obtained from the computation by the numerical analytical model verify that the theoretical model and computer programs established in this study are reasonable. This study shows that hot rolling can greatly reduce the rolling force and strain rate with the early appearance of plastic deformation, and the distribution of temperature field Is basically affected by the heat transfer, boundary conditions. However, unsymmetricai heat transfer boundary conditions will cause unsymmetricai rolling forces of the upper and lower rollers and cause strip curvature; this condition can be corrected by the difference in the rotation speed of the rollers.
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