Numerical Simulation Analysis Of Rolls Deformation For Four-High Mill

All the time, our country demand of the high quality sheet is relatively scarce. Especially the quality demand of thin sheet is stricter and stricter. Producing sheet with good performance and high dimensional accuracy, the mill and process is required strictly and accurately.Many factors affect the sheet quality in the rolling forming process of sheet. Some methods such as experience and experiments has been used to control sheet shape, but the capital was consumed largely and the research cycle was long. What the most important was that the deformation state of roller in rolling process was not measured and the results was not well. With the development and maturation of finite element simulation, it are increasingly used in metal plastic deformation. It can reduce the cost and improve the efficience. What the most important is that the deformation state of roller in rolling process can be received. So the ANSYS are used to simulate the rolling process. The simulation data and result are used as the certain reference data.The research object of this paper is four roll mill. The simulation analysis of four roll mill is done from tension and friction coefficient. The banding deformation of work rolling and backup rolling, rolling force and roll system structure stiffness are used as review projects. Using the LS-DYNA module of ANYSYS finite element software, the rolling process is analyzed through the elastic-plastic deformation theory. The three dimensional model is constructed with using ANSYS finite element software. Putting measured per reduction ratio as finite conditions, the mechanical deformation behavior of the roll is analyzed with the change of forth and back tension and friction coefficient. These effect factors of forth and back tension and friction coefficient is analyzed on roll system bending deformation, rolling force and roll system structure stiffness. The distribution regularity of roll system bending deformation, rolling force and roll system structure stiffness is gotten with the different tension and friction.From the simulation we can get the following conclusions:Tension plays an important role in rolling process. It can decrease the roller bending deformation and rolling force, meanwhile, improve the roll system structure stiffness. So the sheet shape can be controlled exactly and the service life of the roller can be prolonged. Comparing the effect in rolling process between forward and backward tension, the backward tension can remarkably decrease the rolling force and the roller bending deformation, meanwhile, the roll system structure stiffness raise quickly.The friction coefficient between sheet and work rolling has an important influence in rolling process. With the decrease of friction coefficient, the roller bending deformation and rolling force decreases, while the roll system structure stiffness improves. But the low friction coefficient may cause the roll slippage and biting hard. So the reasonable friction coefficient is of significance to ensure the sheet quality.So improving the backup tension and decreasing the friction coefficient is very necessary in reasonable roll process.Aiming at sheet rolling, especially reversible rolling, the reasonable match of tension and friction has importance significance for the good produce quality. In this paper, combining the actual field conditions to simulation, the characteristic of roll system structure is analyzed. The reliable reference data can be provided to the selection of roll model and roll process.