Method for rolling metal sheets with variable thickness

A method for rolling metal sheets with variable thickness, the method including:

• determining a first distribution of areas (having an increased thickness with respect to a nominal rolling thickness of the sheet, said first distribution of areas including one or more areas,
• determining, for each area of said first distribution, an increase of volume of material corresponding to the difference between the volume of material underlying each area with the thickness assigned on the basis of said first distribution, and the volume of material underlying the corresponding area with the nominal rolling thickness,
• determining a second distribution of areas (having an increased thickness with respect to the nominal rolling thickness, wherein said second distribution of areas includes one or more areas,
• assigning, to each area of said second distribution an increase of volume of material corresponding to the difference between the volume of material underlying each area with the thickness assigned on the basis of said second distribution, and the volume of material underlying the corresponding area with the nominal rolling thickness, wherein the overall increase of volume of the one or more areas of said second distribution is equal or higher to the overall increase of volume of the one or more areas of said first distribution,
• positioning the one or more areas of said first distribution along said sheet in a desired position within a figure that corresponds to a plane development of a component of a motor-vehicle which is to undergo a pressing operation,
• positioning the one or more areas of said second distribution outside of said figure,
• providing a pair of mill rolls having a surface relief that corresponds, developed on a plane, to the combination of the first and the second distribution of areas with increased thickness, and rolling said metal sheet by means of said pair of mill rolls.