Instabilities and wear propagation in calenders

Paper calenders are required for the manufacturing process of paper products on the basis of pulp. Failures or interruptions during the production process have to be absolutely avoided. Some of the occurring malfunctions can be traced back to vibrational phenomena: so-called sudden instabilities and wear propagation on the roller’s surface. The understanding of the interaction between the structural dynamics and the paper is fundamental for the description of the system’s behavior and is therefore investigated in detail. The derivation of the contact kinematics allows the determination of the fundamental equations of motion and an eigenvalue problem. The analysis of the analytically derived eigenvalues reveals stabilizing configurations of the system in order to avoid self-excited vibrations. For the analysis of the wear propagation on the roller’s surface, a rotating beam model with a wear layer is introduced. The worn surface is analyzed and the origin of barring patterns is examined. Furthermore, various influences on the wear propagation, such as the roller’s anisotropy or the bearing stiffness, are analyzed.