WOUND ROLL GENERATED UNSTABLE VIBRATION ON A TWO-DRUM WINDER

摘要

Nip contact between the paper roll, winding drum and rider roll or some other nip roller may cause that the wound roll is deformed into a convex polygon. This deformation process is accompanied with a strong vibration. The conditions under which this phenomenon occurs depend very much on the web properties. For example, in the paper industry some bulky grades with a high layer-to-layer coefficient of friction are known to be prone to this unstable vibration. In this paper a simple wind-up model of a two-drum winder, capable of capturing quite comprehensively this phenomenon, is developed. The pattern formation is modelled via viscoelastic surface deformation. This results in a system of linear delay differential equations. Performing Laplace transformation to the system equations enables to study the stability of the system as a function of the web properties, nip drum stiffness, wind-up geometry and damping. The model parameters related to the viscoelastic surface deformation are measured experimentally for several paper grades. The paper is concluded by studying the system stability in a certain resonance condition. It is demonstrated that the system can be stabilised by changing the structural parameters of the winder.