Tilted guides with friction in web conveyance systems

Abstract

One challenge in designing web conveyance systems is controlling the displacement and vibration of the webs by guides without introducing instabilities or higher frequency disturbances from flange impacts. A solution to this problem is to use an actively or passively tilted guide or roller to steer the web. In this paper, a model of tilted guides with friction is developed, and it is shown that tilted guides produce a change in the web’s displacement, slope, bending moment, and shear force. When the web is conceptually unwrapped from its path, the normal force between the web and a tilted guide has a component that acts in the direction of the web’s lateral displacement, resulting in an equivalent force and bending moment acting on the web. The model is validated by measurements, and is compared to a previously existing model of guide tilt. In the configurations studied, the displacement of the web near the guide is linearly dependent on the tilt angle and tension and it increases exponentially with the web’s span length. When the guide’s tilt is oriented towards the center of the web’s wrap around the guide, the equivalent bending moment is zero in the absence of friction, and there is good agreement between the model developed in this paper and the previously existing model. However, when the center of the web’s wrap is oriented 90° away from the guide’s tilt orientation, the equivalent force is zero in the absence of friction, and measurements demonstrate the necessity of the equivalent bending moment.