US Patent 8425225 Made to the rapid heating sections of continuous heat-treatment lines

Method of reducing the formation of folds on metal strips (1) exposed to rapid heating in continuous heat-treatment lines, in which lines said strips are caused to pass through heating sections (2) comprising successive and separate heating means (5; 5a; 5b; 5c; 5d), wherein the average slope of the increase in temperature of the strip between the inlet and the outlet of a heating means decreases from one heating means to the following heating means.