Winding Experiments on Nonuniform Thickness Webs

Abstract

Webs have non-uniformity in thickness that results from the processes by which the webs are made. Webs are stored in the form of wound rolls. The stresses in the wound roll will vary spatially due to the non-uniform thickness. The non-uniformity in thickness may vary over the width and down the length of the web. Winding models have been developed that attempt to capture the spatial variation of the internal stresses as affected by thickness non-uniformity. This study used experimental methods to validate winding models. Center winding tests were performed with and without nip rollers and core pressure data, outer lap radius, and roll hardness data were collected across the wound roll width. Thickness was mapped over the entirety of the polyester web used in the winding tests and web material properties were measured to provide necessary input for the winding model. Good agreement was found between the test results and the winding model. Better agreement was found in the core pressure than the outer lap radius.