Horizontal collision vibration of the cold rolling mill considering the structural clearance and dynamic constraints

To improve the stability of the cold rolling system, this paper investigates the horizontal collision vibration of the cold rolling mill under both structural clearance and dynamic constraints. Taking into account the clearance between the bearing seat of the working roll and the frame side plate, as well as the dynamic constraints imposed on the working roll by the horizontal vibration of the frame, the horizontal collision vibration model of the cold rolling system is established. Three motion states, including free motion, adhesive motion, and collision vibration, are analyzed for the horizontal vibration of the working roll and frame, and the state conditions in which the system undergoes the above-mentioned motion changes are analyzed. It is found that when the working roll and the frame collide multiple times and experience a decrease in amplitude difference, the two evolve into adhesive motion. By establishing Poincaré map and analyzing the single-parameter bifurcation characteristics, the evolution paths of “period-doubling bifurcation → chaotic motion” and “Hopf bifurcation → almost periodic motion → chaotic motion” in the cold rolling system are revealed. When the cold rolling system enters chaotic motion through different motion paths, the topological structure of this chaotic motion differs. The two-parameter chaotic characteristics of the horizontal collision vibration of the cold rolling system are studied, and the two-parameter matching regions for periodic and chaotic motions of the system are determined. This study reveals the interaction mechanism between the working roll and the frame, as well as the complex evolution process of horizontal collision vibration under structural clearance and dynamic constraints, thereby providing a theoretical reference for vibration reduction and stable operation of the cold rolling system.