Corrugated sheet and method of manufacturing same

Abstract

Disclosed is a metal sheet having a first major surface and an opposite second major surface, a first end and an opposite second end, and a first side edge and an opposite second side edge. The sheet has a plurality of parallel corrugations having a length defining a first axis extending along the sheet, a width defining a second axis extending across the sheet, and a depth defining a third axis extending through the sheet. The corrugations are formed by roll forming of the metal sheet. In transverse cross section, each of the corrugations comprises a substantially convex portion and a substantially concave portion. The substantially convex and concave portions each comprise a plurality of substantially linear portions with curved transition portions therebetween. The curved transition portions have a radius sufficiently small to cause plastic deformation of the metal sheet during roll forming of the corrugations. The substantially convex and concave portions each approximate a smooth curve.

1 . A method of corrugating a sheet of metal, the method comprising:
 providing a non-corrugated sheet of metal having a first major surface and a second major surface opposite the first major surface;   deforming the sheet to form in the sheet a plurality of parallel corrugations having a length extending in a first direction along the sheet, a width extending in a second direction across the sheet, and a depth extending in a third direction through the sheet,   wherein, in a cross section through the sheet transverse to the length of the corrugations, at least some portions of the corrugations comprise a shape approximating a smooth curve, and   wherein the shape approximating a smooth curve comprises a plurality of first portions, wherein adjacent said first portions are oriented at an angle to one another and interconnected by second portions, the metal in the second portions being plastically deformed during forming of the corrugations.   
     
     
         2 . The method as claimed in  claim 1 , wherein the metal in the first portions does not undergo plastic deformation during forming of the corrugations. 
     
     
         3 . The method as claimed in  claim 1 , wherein the second portions are curved and have a radius sufficiently small to cause plastic deformation of the metal when the sheet is deformed to that radius. 
     
     
         4 . A method according to  claim 1 , wherein the first portions are substantially linear. 
     
     
         5 . The method as claimed in  claim 1 , wherein a curve of best fit of the shape approximating a smooth curve has a radius of at least 5 times greater than the radius of the second portions. 
     
     
         6 . The method as claimed in  claim 1 , wherein each of the second portions has a radius of between 1 mm and 6 mm, and wherein, prior to being deformed, the sheet has a thickness of between 0.2 mm and 0.6 mm. 
     
     
         7 . The method as claimed in  claim 1 , wherein a curve of best fit of the shape approximating a smooth curve has a radius of greater than 10 mm. 
     
     
         8 . The method as claimed in  claim 7 , wherein the radius of the curve of best fit of the shape approximating a smooth curve is between 10 mm and 100 mm. 
     
     
         9 . The method as claimed in  claim 1 , wherein each of the first portions has a length of less than 0.2 times the radius of the associated said shape approximating a smooth curve. 
     
     
         10 . The method as claimed in  claim 9 , wherein the length of each of the first portions is between 0.05 and 0.15 times the radius of the associated said shape approximating a smooth curve. 
     
     
         11 . The method as claimed in  claim 1 , wherein the corrugations are defined by alternating said substantially convex and substantially concave portions, and the at least some portions of the corrugations comprising a shape approximating a smooth curve comprise the substantially convex and substantially concave portions. 
     
     
         12 . The method as claimed in  claim 11 , wherein a point of inflection between adjoining said substantially convex and substantially concave portions is at a crest and/or a trough of the corrugations. 
     
     
         13 . The method as claimed in  claim 11 , wherein one point of inflection between adjoining said substantially convex and substantially concave portions is at a crest of the corrugations and another is at a location between crests and troughs of the corrugations in the third direction. 
     
     
         14 . The method as claimed in  claim 11 , wherein points of inflection between adjoining said substantially convex and substantially concave portions are substantially midway between crests and troughs of the corrugations in the third direction. 
     
     
         15 . The method as claimed in  claim 11 , wherein the radii of the curves of best fit of the substantially convex and substantially concave portions are substantially equal. 
     
     
         16 . A corrugated sheet of metal produced using a method of corrugating a sheet of metal, the method comprising:
 providing a non-corrugated sheet of metal having a first major surface and a second major surface opposite the first major surface;   deforming the non-corrugated sheet to convert it into a corrugated sheet having a plurality of parallel corrugations, the corrugations having a length extending in a first direction along the corrugated sheet, a width extending in a second direction across the corrugated sheet, and a depth extending in a third direction through the corrugated sheet,   wherein, in a cross section through the corrugated sheet transverse to the length of the corrugations, at least some portions of the corrugations comprise a shape approximating a smooth curve, and   wherein the shape approximating a smooth curve comprises a plurality of first portions, wherein adjacent said first portions are oriented at an angle to one another and interconnected by second portions, the metal in the second portions being plastically deformed during forming of the corrugations.