METHOD FOR PRODUCING LARGE-DIAMETER LONGITUDINAL WELDED PIPES Russian patent published in 2021 - IPC B21C37/08 

FIELD: pipes.

SUBSTANCE: invention relates to pipe production. The method for producing large-diameter longitudinal welded pipes includes forming a flat sheet and subsequent final bending of the edges. The final bending of the edges is executed by longitudinal rolling with a tool in the form of a lower roll and two upper rollers, wherein the radius of curvature of the working surfaces of the lower roll is determined by the formula:

,

and the radius of curvature of the working surfaces of the upper rollers by the formula wherein: R, mm is the radius of the lower roll; D, mm is the outer diameter of the pipe; s, mm is the thickness of the pipe wall; B’, mm is the technological forming gap; r, mm is the radius of the upper roller; C, mm is the technological bending gap of the edges equal to 6 to 10 mm; ΔQ, mm is the non-negative difference between the horizontal displacement of the centres of curvature of the upper and lower tools; π is the Pythagorean number; φ is the springing coefficient.

EFFECT: increased geometry of pipes and reduction in residual stresses are ensured.

1 cl, 5 dwg