: Chatter is a particular case of self-excited vibrations which arise in rolling operations as a consequence of the interaction between the structural dynamics of the mill stand and dynamics of the rolling process. Dynamic forces generated in the rolling process deflect the structure of the mill, leading to variations at the roll gap and the roll speed. These, in turn, result in further variations of rolling forces. Under certain circumstances, the interaction between the structure and process may become such that energy, of the mill’s drives, is captured by the process and transformed into vibratory energy of the structure. In this paper, to analyze the chatter vibration of mill machine, a dynamic model of cold rolling process using finite element method (FEM) is considered. Similar to previous models, the model presented here has two sub models, one for structure of the mill and the other for the rolling process. The structure of a mill stand is modeled as a system of linear spring and lumped masses in order to simulation the interaction between the rolls. Work roll was simulated by assuming an elastic element. Hard contact is employed to simulate the contact between the surface of the strip and the work roll. The whole strip body is meshed by 2D deformable elasto-plastic continues elements with an elastic roll. An implicit dynamic FE analysis of rolling process for detection of chatter is presented using ABAQUS/Implicit. The influence of rolling parameters such as rolling speed, reduction and friction coefficient on chatter vibration is investigated and it was showed that the possibility of chatter onset increased by raising the rolling velocity; furthermore, increasing the reduction ratio in a constant friction coefficient reduces the systems stability.
