Dancer roll

A dancer roll is used to generate a tension within the web and can be used for controlling a following drive (pull rolls, winder).

A dancer rolls consists of an idler roll mounted on an swiveling arm. The weight of the roll should be compensated e.g. by a counter weight, so that the roll can be pressed into the web path with a defined power. This is usually done by pneumatic pressure, where the operator sets a certain tension which is transmitted by an EP-converter into a pneumatic pressure. Before and after the dancer roll arranged pull rolls are used to keep the tension within the web.

If the dancer roll leaves the neutral position (e.g. by a length variation within the web) this movement will be detected by a pulse generator mounted at the pivoting center of the dancer roll. The signal of the pulse generator will be used as correction signal for the following pull roll system, which then runs faster or slower to compensate the length difference. As a result the dancer roll will move in the neutral position again.