SHEET OF COLD ROLLED MATERIAL AND METHOD FOR ITS MANUFACTURE

Lim (10) od hladno valjanog materijala koja ima na obje svoje površine redove (R12) izbočina (11) i redove (R13) udubina (12), te izbočine (11) na jednoj površini odgovaraju udubinama (12) na drugoj površini, a relativni položaji izbočina (11) i udubina (12) su takvi da linije povučene na površini lima (10) između susjednih redova (R12) izbočina (12) nisu pravocrtne, te lim (10) ima osnovnu debljinu (G), naznačena time da svaka izbočina (11) ima u osnovi neprekidno područje vršne plastične deformacije (PP) na ili oko njenog vrha i stanjena je za ne više od 25% njene osnovne debljine (G). Patent sadrži još 14 patentnih zahtjeva. 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.