METHOD OF PRODUCING THIN-WALL MULTI-FACE TUBES (VERSIONS) Russian patent published in 2011 - IPC B21C37/15 

FIELD: metallurgy.

SUBSTANCE: first method comprises pre-forming round billet without varying wall perimetre and thickness into multi-face billet, and final forming to finished section by lengthwise rolling with reducing tube perimetre and squeezing its walls at multi-face mandrel. Tube parametre reduction is performed with relative deformation not exceeding 8%, while wall squeezing features relative deformation of about 25% with simultaneous reduction in distance between opposite faces and wall relative deformation-to-reduction deformation ratio making at least 1. Second method comprises pre-forming round billet into multi-face billet with convex faces, and final forming into finished section without varying wall thickness. Pre-forming brings about billet with face convexity varying from 0.005 to 0.040 of face width, and perimetre equal to finished section perimetre. Final forming into finished section is performed by crosswise bending of all faces by rolls made with convex generatrix of working surfaces. The width of contact the roll with the tube is varying from 0.3 to 0.7 of face width.

EFFECT: production of thin-wall multi-face tubes with precise geometrical sizes and high surface quality.

2 cl, 3 ex, 4 dwg