METHOD FOR PRODUCTION OF CONVERSION TUBULAR BILLET FOR ROLLING OF COLD-ROLLED PIPES OF LARGE AND MEDIUM DIAMETRES OF HARDLY-DEFORMED GRADES OF STEELS AND ALLOYS Russian patent published in 2010 - IPC B21B3/00 B21B23/00 B21B21/00 

FIELD: technological processes.

SUBSTANCE: invention relates to method for production of conversion tubular billet for rolling of cold-rolled pipes of large and medium diametres of hardly-deformed grades of steels and alloys. Method includes production of sheet billet, gouging of sheet along width, preparation of sheet edges for welding, forming of sheet billet into tubular conversion billet and welding of longitudinal edges with consumable or non-consumable electrode of the same grade steel, forming of conversion tubular billet is carried out in rolls with length of up to 4.5 m with ratio of diametre to wall thickness D/S=20-40, at the same time width of seams and height of beaded welds of conversion tubular billet is identified on the basis of the following expressions: B=K × D/S, B₁=K₁ × D/S, h=K₂ S, h₁=K₃ S, where B is width of outer seams beads in conversion tubular billets, mm; B₁ is width of inner seams beads in conversion tubular billets, mm; D is outer diametre of conversion tubular billets, mm; S is wall thickness of conversion tubular billets, mm; K=1.0-1.5 is coefficient for determination of outer seam beads width, larger values of which relate to conversion tubular billets with lower ratio D/S; K₁=0.95-1.3 is coefficient for detection of inner seams beads width, larger values of which relate to conversion tubular billets with lower ratio D/S; h is height of outer seams beads reinforcing, mm; h₁ is height of inner seams beads reinforcing, mm; K₂=0.1-0.25 is coefficient for detection of outer seams beads height, larger values of which relate to conversion tubular billets with smaller thicknesses of walls; K₃=0.1-0.15 - coefficient for detection of inner seams beads height, larger values of which relate to conversion tubular billets with smaller thicknesses of walls.

EFFECT: invention provides for production of high-quality pipes in accordance with GOST 9941 from welded conversion tubular billets instead of seamless ones and considerable reduction of metal consumption coefficient in process of conversion: conversion straight-seam tubular billet - cold rolled pipe, and accordingly, reduction of cost of cold rolled pipes from hardly-deformed grades of steels and alloys.

5 cl, 1 tbl