Method for hot rolling Z-sections sheet piles

A method for rolling a Z-section sheet pile having a first flange, a second flange, which is substantially parallel to said first flange, an inclined web, a first corner joining said web to said first flange, a second corner joining said web to said second flange, wherein each of said corners has an opening angle a greater than 90°;

• wherein said method comprises the steps of:
• rolling a precursor of said Z-section sheet pile with a curved precursor of said web in successive roll gaps defined by at least one roll pair comprising a grooved upper roll and a grooved lower roll, wherein:
• a precursor of the first corner and an adjoining first part of said curved precursor of said web are formed in a first groove of said upper roll, and
• a precursor of the second corner and an adjoining second part of said curved precursor of said web are formed in a first groove of said lower roll;
• and
• subsequently straightening said curved precursor of said web by introducing said precursor of said Z-section sheet pile between an upper straightening roll and a lower straightening roll;
• wherein:
• at least in the roll gaps that finish forming said curved precursor of said web, said lower roll has a diameter that decreases in a discontinuous manner in an interval between said first groove in said upper roll and said first groove in said lower roll, and said upper roll has a diameter that increases in said interval in a complementary manner.