A paper-transport mechanism using tapered rubber rollers to generate cross-directional tractive force.

A paper transport mechanism that generates tractive force in the cross direction perpendicular to the paper transport direction was developed. The mechanics of this mechanism were then investigated by using the finite element method (FEM). A pair of tapered rubber rollers is the key point of the mechanism. Each roller has two tapered surfaces that thin out in the same direction. The thin sides of both tapered rollers face each other symmetrically to form the center of the transport mechanism. A cylindrical steel roller is pressed toward the tapered roller by a spring. Paper sheets are nipped between the tapered rubber roller and the cylindrical steel roller. On being pressed, the tapered roller is bent around the mid point of the side of the roller because of it has an asymmetrical cross section. The bend first produces shear stress on the contacting area perpendicular to the transport direction. Second, it produces a bulgy deformation so the roller shape is pressed out in the same direction. These processes generate tractive force on the paper. However, the tapered roller generates not only a tractive force but also a twisting moment. Therefore, one roller has two tapered surfaces to cancel the twisting moment. FEM analysis indicates that the tractive force could be estimated within 20% error in comparison with the measured value. The advantages of the new mechanism are that rubber rollers are used in almost all paper-handling equipment and simply cutting two tapers can generate tractive force. This mechanism improves transport reliability preventing wrinkles and slack. [ABSTRACT FROM AUTHOR]