Abstract: A winding core capable of being made in relatively thick-walled configurations and yet capable of being readily collapsed into a flattened configuration for shipping or storage prior to use comprises a plurality of fibrous plies helically wound one atop another and adhered together to form a tube. The plies are arranged in two or more groups of two or more plies each. The plies of each group are adhered to one another over at least a substantial majority of their facing surfaces, but the adjacent groups are non-adhered to each other over at least a substantial majority of their facing surfaces.

Abstract: Wide ply gaps are intentionally introduced into one or more plies in a radially intermediate zone of the wall of a spirally wound tube. Each ply having wide ply gaps is narrower than the width that would ordinarily be employed at a given spiral winding angle to achieve a butt joint between adjacent edges of consecutive turns of the ply, and the ply is wound at that given spiral winding angle in such a manner that gaps are defined between the adjacent edges of the consecutive turns of the ply. The wide ply gaps have the effect of increasing the compliance of the intermediate zone of the tube wall in the radial direction. Such increased radial compliance has been found to improve the ID stiffness of the tube relative to a tube constructed of the same materials but having no ply gaps in the intermediate zone.

Abstract: A wound tube comprising at least two plies having a cold seal adhesive or cohesive layer for bonding the plies together. The plies are wrapped spirally about an axis to form a tube, which may then be cut to appropriate lengths. Once formed, the tubes may be used in a variety of applications including as cores for hygienic paper rolls.

Abstract: Wide ply gaps are intentionally introduced into one or more plies in a radially intermediate zone of the wall of a spirally wound tube. Each ply having wide ply gaps is narrower than the width that would ordinarily be employed at a given spiral winding angle to achieve a butt joint between adjacent edges of consecutive turns of the ply, and the ply is wound at that given spiral winding angle in such a manner that gaps are defined between the adjacent edges of the consecutive turns of the ply. The wide ply gaps have the effect of increasing the compliance of the intermediate zone of the tube wall in the radial direction. Such increased radial compliance has been found to improve the ID stiffness of the tube relative to a tube constructed of the same materials but having no ply gaps in the intermediate zone.

Abstract: A spirally or convolutely wound multi-layer tube includes one or more plies or layers that have embossments formed therein and projecting from one or both sides of each such ply or layer. The embossments increase the effective caliper and volume of the ply without adding mass. The embossments can abut an adjacent ply or layer of the tube and space such adjacent ply or layer from regions of the embossed ply or layer between the embossments, thereby forming void spaces in the tube wall.

Abstract: A testing apparatus for determining dynamic strength of sample paper cores includes a rotatably driven pneumatic chuck for engaging the inner surface of a sample core to rotatably drive the sample core, and a variable-tension belt assembly having a flexible belt which is looped over the sample core and tensioned to simulate the load applied to a paper core in actual use. The belt is tensioned by a pneumatic cylinder which is controlled under feedback control by a servo valve and a computer controller so that the load applied to the sample core accurately tracks a predetermined desired load schedule versus time.