METHOD OF CONVERSION PIPE MANUFACTURING IN PIPE ROLLING PLANTS WITH PILGER MILLS OF LOW-ELASTICITY STEEL WITH BORON CONTENT OF 1,3-1,8% Russian patent published in 2008 - IPC B21B21/00 

FIELD: technological processes.

SUBSTANCE: method involves ingot casting by electroslag refining; turning and drilling of central hole in ingots; ingot heating to the elasticity temperature; piercing at piercing mill to form shells; shell rolling at pilger mill to form conversion pipes of 290x12x23000-24000 mm dimensions. Rolling of front ends at (1.0-1.2) L_rec length is performed for S_f=S_y+K wall width, and rolling of rear ends at (1.2-1.5) L_rec length is performed for S_r=S_y-K₁ wall width, where L_rec=1100-1150 is recoil distance of feeder during rolling 290 mm diameter pipes in rolls with 980 mm barrel diameter, mm; S_f is front end pipe wall thickness, mm; S_y=12 is rated wall thickness of conversed pipes for regular rolling process, mm; S_r is rear end pipe wall thickness, mm; K=(2-3) is growth factor of pipe wall thickness during front end rolling, mm; K_l=(0.5-0.8) is diminishment factor of pipe wall thickness during rear end rolling, mm.

EFFECT: reduced metal expenditure and cost of commercial hexagon pipes.

1 tbl