Patent ID: 7353681

Claim:
A cold rolling apparatus for impressing a pattern on a surface of a sheet article made of a predetermined metal, said apparatus comprising: a. a pair of rolls each having an outer surface that has a cylindrical part, said rolls being disposed with a gap present between said cylindrical parts of said rolls; b. one of the rolls of said pair having a localized surface region that is displaced by at least 5 microns relative to the cylindrical part of said roll such that, when said localized region is brought into proximity with the other roll of said pair, a spacing exists therebetween that is narrower than said gap; and c. one of said rolls of said pair having a localized patterning feature to be impressed on the surface of said sheet article, said localized patterning feature being aligned with said localized surface region, at least when engaging said sheet article, for impressing said pattern into the surface of said sheet article; wherein the gap is of a width effective to cause the cylindrical parts of said rolls to engage opposite surfaces of the sheet article while imparting compression less than a bulk elastic yield strength of said metal.