Patent ID: 6851643
Filing Date: 2005-02-08
Classification: B31C,B65H,Y10T

Abstract:
1. A spirally wound tube formed to have enhanced ID stiffness under radially inward compressive loads on the tube, the tube comprising: a plurality of plies spirally wound about an axis and adhered together to form a tube, a wall of the tube comprising a radially inwardly located zone, a radially outwardly located zone, and a radially intermediate zone located between said inwardly and outwardly located zones, each zone comprising at least one paperboard ply; the intermediate zone including a narrow ply having a width less than that of plies of the inwardly and outwardly located zones, the narrow ply being wound such that a gap exists between adjacent edges of consecutive turns of the narrow ply, the gaps in the intermediate zone causing the intermediate zone to have a greater compliance in a radial direction of the tube than that of the inwardly and outwardly located zones, thereby enhancing the ID stiffness of the tube.