Multi-stand rolling mill for rod-shaped bodies comprising three motorized-rollers stands

A rolling mill (1) for tubular bodies comprising a first section (10) for rolling on mandrel defined by a first plurality of rolling stands (15′, 15, 15″) arranged in sequence along a rolling axis (100),

• a second section (20) for extracting said mandrel, reducing and calibrating the diameter of said tubular bodies, said second section being downstream of said first section (10), wherein the distance between a last rolling stand of the first section (10) and a first rolling stand of the second section (20) in a range of 8 to 14 m,
• wherein said tubular bodies exiting from said first section (10) have an external diameter equal or greater than 100 mm and
• directly enter said second section (20), said second section (20) comprising a second plurality of rolling stands (25′, 25, 26, 27, 26′, 27′) without mandrel, arranged in sequence along said rolling axis (100),
• wherein each stand (25′, 25, 26, 27, 26′, 27′) of said second section (20) comprises three rollers, the rotation axes of which are arranged at 120° relative to one another and
• wherein, for each stand (25′, 25, 26, 27, 26′, 27′) of said second section, said rotation axes are rotated by 180° relative to corresponding rotation axes of an adjacent stand, said position of said rotation axes being assessed with respect to a vertical reference direction, and
• wherein at least one stand of said second section (20) comprises a motorized roller having a vertical rotation axis,
• wherein the second section (20) comprises first releasing thrust cylinders (290) positioned on the inlet side (20′) and
• second locking thrust cylinders (291) being positioned on the outlet side (20″) of the second section (20) and capable of exerting an axial thrust on the stands (25′, 25, 26, 27, 26′, 27′) of the second section in a direction opposite to the rolling direction (200) for compacting the stands along the rolling direction and locking them axially.