Method and apparatus for producing coreless rolls of sheet material and a coreless roll of material

Abstract

A roll of sheet material, such as plastic film wrap, having an inner layer wound at low tension and an outer layer wound under greater tension provides a coreless roll. Eliminating the need for a core reduces the cost of producing rolls of sheet material, and reduces the weight and outer dimensions of the roll with a consequent reduction in shipping and storage costs. An apparatus and method for producing such a roll, from a pre-wound master roll or as part of a production line for forming the sheet material, involves varying the longitudinal tension applied to sheet material as it is wound onto an expandable mandrel. After the roll has cured, the mandrel is collapsed and disengaged from the roll to provide a coreless roll. The mater roll can be prestretched prior to forming the coreless roll, if desired, and can be prestretched as a step in the formation of the coreless roll.

Dependencies are inferred from the claim text.