METHOD OF SEAMLESS PIPE PRODUCTION AT THE AGGREGATE WITH SCREW PIERCING MACHINES AND CONTINUOUS LENGTHWISE ROLLING Russian patent published in 2012 - IPC B21B19/00 

FIELD: metallurgy.

SUBSTANCE: pipes are produced at the aggregate with screw piercing machines and continuous lengthwise rolling. The method includes heating of initial block, centring, first and second piercing in the screw piercing machines, rolling in the lengthwise rolling mills at the internal tool, calibration, cooling and adjustment. Production of high accuracy size pipes with quality outer and inner surface is ensured by the fact that the centering of blocks is made mechanically before heating, first piercing is made until rough tube is received with correspondence of diameter to thickness of walls within 5-7 and total reduction value at first and second piercing amounts to 55-85% of the aggregate reduction. At this the lengthwise rolling is made at the straight plug, which length equals to 0.12-0.8 of the rough pipe length, and the plug moving with speed of 25-65% of the speed of pipe output from the last mill. The first piercing reduces inner diameter of rough tube as compared to the block diameter and the second piercing increases the diameter of rough tube.

EFFECT: increased quality and accuracy of pipe geometry sizes produced with screw piercing method.

2 cl, 1 ex