Rectangilar-Ribbed Profile Tubular Core and Method

Abstract

Disclosed is a tubular core on which sheets of metal or other material can be wound and supported, for shipment, handling and dispersal, and a method for forming the core. The core comprises a metal sheet or strip which has a rectangular-ribbed cross-sectional profile of flattened ribs, and which is wound spirally into a tubular configuration. The core is formed by passing the strip through a plurality of roll-forming stands, to initiate forming and progressively form an arcuate ribbed sinusoidal profile, then a final roll-forming pass is used (or several such passes are used) to flatten the ribs of the profile so that the rectangular flattened ribs collectively form a support surface for the sheets which are wound and supported on the core.

What is claimed is: 
     
         1 . A method for forming a metal strip into a cylindrical core, comprising:
 passing an elongated metal strip having width and length and opposite longitudinal edges through a multiplicity of forming stands each of which forms curved longitudinally extending sinusoidal corrugations in said strip or changes the size of existing curved corrugations or both, then passing the strip through at least one final forming stand for flattening the corrugations, wherein upon completion of the corrugation forming process a plurality of the rectangular corrugations as-formed along the width of the strip comprise longitudinally extending, alternating ribs including upwardly extending ridges and downwardly extending grooves, the ridges and grooves comprising generally vertical spaced-apart sidewalls with the ridges further comprising longitudinally extending, flattened, spaced-apart top surfaces extending between adjacent ridge sidewalls and the grooves further comprising longitudinally extending, flattened, spaced-apart bottom surfaces extending between adjacent groove sidewalls, the flattened ridges and flattened grooves together forming a rectangular ribbed cross sectional profile extending along the width of the strip transverse to the length thereof;   forming the opposite longitudinal edges of the as-formed corrugated metal strip into flanges adapted for forming an interlocking seam;   helically coiling the as-formed corrugated strip into a cylinder having a longitudinal axis and an outer surface defined by flat, spaced-apart surfaces selected from the top surfaces and the bottom surfaces; and   compressing the opposite edge flanges together thereby forming an interlocking seam extending in a spiral around the cylinder along the longitudinal axis thereof.   
     
     
         2 . The method of  claim 1  wherein the metal strip is aluminum and is 0.005″ to 0.050″ thick. 
     
     
         3 . The method of any of  claims 1  and  2  wherein during the helical coiling step, the metal strip is oriented at a helix angle of approximately 60° or greater relative to the longitudinal axis. 
     
     
         4 . A cylindrical core, comprising:
 an elongated metal strip having width and length and being helically coiled into a cylinder, the cross-sectional profile of the strip along the width thereof transverse to the length thereof including corrugations comprising longitudinally extending alternating ribs including upward extending ridges alternating with downward extending grooves, the ridges having longitudinally extending, generally flattened, spaced-apart top surfaces, the grooves having longitudinally extending, generally flattened, spaced-apart bottom surfaces, and the flattened ridges and the flattened grooves together forming a flat ribbed corrugated transverse cross section;   said cylinder having an outer surface formed by flat spaced-apart surfaces selected from the top surfaces of the ridges and the bottom surfaces of the grooves; and   a lockseam of joined opposite edges of the metal strip, the lockseam extending in a spiral around the cylinder along the longitudinal axis thereof.   
     
     
         5 . The core of  claim 4  wherein the metal strip is aluminum and is 0.005″ to 0.050″ thick. 
     
     
         6 . The core of  claim 5  wherein the pipe diameter is at least approximately 6″. 
     
     
         7 . The core of any of  claims 4 ,  5  and  6  wherein prior to forming the cylinder the aluminum strip is approximately 0.023″ thick and approximately 3⅝″ wide; the vertical dimension between adjacent top and bottom surfaces of the as-formed cylinder is approximately 0.27″; the width of the flat ridge surfaces is approximately 0.027″, the distance between adjacent flat ridge surfaces is approximately 0.027″; the width of the flat groove surfaces is approximately 0.027″, the distance between adjacent flat ridge surfaces is approximately 0.027″; and the diameter of the as-formed cylinder is within the range approximately 16″-24″. 
     
     
         8 . The core of  claim 7  further comprising embossments in the legs of the ribs.