The role of analytical winding dynamics in winder design

Winder design is guided by the principle that major excitation sources should not hit any of the system's resonance frequencies. Excitation of fixed rotating members (drums, guide rolls, rider rolls) can be eliminated through better balancing and greater manufacturing accuracy. However, the wound paper rolls remain a variable and important source of excitation. This report emphasizes the need to include this source of excitation in winder design. Among the features to be considered in winder design are the rotation and excitation frequencies of the paper roll, growth of roll mass, changes in winding geometry as roll diameter increases, roll flexibility in winding nips, and damping characteristics of the paper rolls. These features are reviewed along with a proposed mathematical approach that includes the paper rolls in the winder structural model by modeling the nip contacts as distributed springs. Practical techniques for reducing winder vibration are also presented. Application : explains how paper properties can affect the roll's performance on the winder and describes techniques for reducing winder vibration.