On the effect of vertical motion of roll system upon dynamic behavior and stability of rolling mill

In some special rolling technologies, a key issue of the material processing is the roll motion along the vertical direction, since it is directly linked to stability of the whole system, and affects the product quality. To address this issue, this paper innovatively investigates the impact of roll motion on the dynamic characteristics of the system. The dynamic variation patterns of the process parameters under roll motion are first identified. It is known that a significant role on the system excitation is played by the process parameters. Therefore, the structure-process coupling strategy is applied to introduce the effect of roll motion into the system dynamics model, to confer its capability of predicting the real dynamic characteristics, for special rolling process. The multiscale small-parameter perturbation method is used to investigate the amplitude–frequency characteristics, and the system vibration response is found through a solution based on the Runge–Kutta method. Numeric results demonstrate that the roll motion significantly influences the system dynamic features, being showing a softening-type dynamic nonlinearity, under variation of many process parameters, which particularly affects the vibration amplitude and the degree of nonlinearity. The evolution of the system dynamic behavior in response to changes of mechanical and process parameters is then determined. The findings confirm the great influence of system parameters under roll motion condition upon the nonlinear dynamic features of the rolling mill. They provide a theoretical reference to set up the rolling process parameters and the system stability control in operation.