PRODUCTION METHOD OF HIGH-STIFFNESS TONGUE-AND-GROOVE SECTION Russian patent published in 2015 - IPC B21B1/08 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, and namely to production of large tongue-and-groove Larsen sections. Claimed process comprises the billet heating, section rolling and cooling. Said billet is produced by longitudinal slitting of dismantled large-diameter main line pipe to two-four parts with transverse bulge. The billet is heated in pusher-type roller heating furnace to 570÷650°C and subjected to multipass rolling to tongue-and-groove section. Directly before every rolling pass the billet longitudinal zones are subjected to local heating to 950÷1050°C at the rate of 450÷600°C/sec. In the next rolling pass, said zones are subjected to high-intensity deformation of 15÷45% to curve the angles of rolled tongue-and-groove section. After every rolling pass geometrical sizes and relative location of the section horizontal and vertical flanges are fixed by accelerated local cooling of the said zones. In second rolling pass the periodic convexo-concave surface of increased bending strength can be formed at the medium horizontal flange.

EFFECT: higher precision of sizes and bending strength.

2 cl, 2 dwg, 1 ex