MODELING OF THE NONLINEAR, AXIAL VIBRATIONS OF THE ROTOR ASSEMBLY IN A DISC REFINER

This paper describes a model for the nonlinear axial vibrations of the rotor assembly in a disc refiner. These were investigated to determin e whether nonlinear effects could cause instabilities during normal op eration. The rotor was modelled as a rigid body subject to a reaction force from the compression of pulp in the refiner, steam thrust due to self-pressurization and a thrust load from a hydrodynamic bearing. Th e damping introduced by the thrust bearing was found to play a major r ole in keeping vibrations to a sufficiently low level that any nonline ar effects are small.