Instability of roll nonlinear system with structural clearance in rolling process

The vibration instability of the nonlinear dynamic system of the rolls considering the structural clearance was theoretically investigated,which is caused by the roll assembly accuracy deviation in the hot rolling process.Firstly,the dynamic rolling force model was established based on the Wekbrod model under the influence of the roll grinding deviation and the stability of the deformation zone.Further,the horizontal and vertical direction coupling dynamic model of the work roll was established considering the structural clearance between the roll and mill frame.Then,the nonlinear dynamic equation was solved by the Runge-Kutta method.The simulation results show that the dynamic system presents the nonlinear vibration characteristics,which shows that the instability of the system is a slowly varying response process with the characteristics of self-excited vibration and forced vibration.Finally,the comparison results show the consistency between the simulation and the test.