METHOD OF PRODUCING SLEEVES Russian patent published in 2017 - IPC B21B19/04 

FIELD: metallurgy.

SUBSTANCE: method comprises plugless reduction of the ingot of fixed length in three-roll breaking-down mill caliber formed by rolls deployed at the feed angle, and piercing of the reduced ingot in the piercing mill. After deformation of 0.75-0.85 length of the ingot, roll speed of breaking-down mill is reduced to a value corresponding to 15-50% of the roll speed atestablished process of ingot reduction. When reducing the ingot with length of more than one and a half of breaking-down mill roll body lengths, feed angle of breaking-down mill rolls is regulated by mathematical relationship. Reduction of the ingot with length of less than one and a half of breaking-down mill roll body lengths is carried out with a gradual regulated increase in the roll speed after its gripping.

EFFECT: improved quality of the end surface of the sleeves, reduced defects from the ring delamination on exterior and interior surfaces of tubes, increased durability of the rolling tool.

3 cl, 3 dwg, 5 tbl