초록 ▼

A sheet of cold rolled material having on both of its surfaces rows of projections and rows of depressions, the projections on one surface corresponding with the depressions on the other surface, the relative positions of the projections and depressions being such that lines drawn on a surface of th

A sheet of cold rolled material having on both of its surfaces rows of projections and rows of depressions, the projections on one surface corresponding with the depressions on the other surface, the relative positions of the projections and depressions being such that lines drawn on a surface of the sheet between adjacent rows of projections are non-rectilinear, the sheet having a base gauge G, wherein each projection has a substantially continuous region of peak plastic strain at, toward or about its apex and/or is thinned by no more than 25% of its base gauge G. Methods of forming the sheet material and tools for forming the sheet material are disclosed.

대표청구항 ▼

The invention claimed is: 1. A method of forming sheet material, the method comprising providing a sheet material having a base gauge G, providing a pair of opposed tools having rows of teeth on their outer surface, placing the sheet material between the tools and moving the tools such that rounded

The invention claimed is: 1. A method of forming sheet material, the method comprising providing a sheet material having a base gauge G, providing a pair of opposed tools having rows of teeth on their outer surface, placing the sheet material between the tools and moving the tools such that rounded sheet engaging surfaces of the teeth on one tool urge portions of the sheet material into gaps between the teeth on the other tool to form projections on both surfaces of the sheet material, wherein the relative positions of the projections and corresponding depressions on the surfaces is such that lines drawn on a surface of the sheet between adjacent rows of projections are non-rectilinear, and wherein the projections have a substantially continuous region of peak plastic strain at, toward or about their apex and are thinned by no more than 25% of its base gauge G.