Methods of compressively treating flexible sheet materials

Claim 1

In a process of establishing a continuous longitudinal compressive treatment of a running length of flexible material comprising pressing the material with a confining surface against a moving drive surface and beyond said confining surface and on the same side of the material engaging the material with a retarding surface, the improvement comprising initially positioning the confining surface in material-driving position while maintaining the retarding surface in an ineffective position, subsequently relatively moving a pressing means generally along the drive surface with respect to said confining and retarding surfaces to position the retarding surface closer to the drive surface to progressively increase the retarding effect, while doing the latter, continuing the pressing of the confining surface so that there occurs at all times travel of the material without slippage relative to the drive surface up to a point O beneath the confining surface, close to but spaced in advance of the beginning point M of said retarding surface, at which point O slippage of the material relative to said drive surface commences, and then while continuing to press the confining surface, bodily shifting the latter rearwardly against the direction of travel of the material, and retarding the material in the regioN vacated by said shifted confining surface.