Comparative study on active and passive dancers used for attenuation of web tension disturbances

A dancer mechanism, used in most of the web process lines, consists of a roller which is either connected to a fixed support by passive elements such as springs and dampers or is force loaded in opposition to the web tension. Dancer mechanisms are commonly used to attenuate web tension disturbances caused by uneven wound rolls, eccentric rollers, mis-alignment of idle rollers, and slacks in webs. A dancer mechanism is also used as a feedback element in a number of web tension control systems. The tension control system is driven by the variations in the position of the dancer mechanism as opposed to the variations in actual tension from the desired tension.Since a substantial number of web process lines in web handling industries use dancer mechanisms, there is a need for a systematic comparative study of different types of dancer mechanisms and their applicability; the focus of this paper will be on such a study. Active and passive dancers will be compared using analytical models; a representative sample of the most common dancer mechanisms will be considered. The results of this analysis will assist in the selection of the dancer mechanism and its components, design of the dancer mechanism, and the effectiveness of a particular dancer mechanism to reject different types of web tension disturbances. Also, to substantiate the fundamental analysis, results from experiments, for certain situations, will be shown and discussed.Mechanical and Aerospace Engineerin