METHOD OF SCREW ROLLING OF HOLLOW PRODUCTS Russian patent published in 2012 - IPC B21B19/04 

FIELD: metallurgy.

SUBSTANCE: method involves deformation of a hollow cylindrical workpiece on a short holder in mushroom-shaped rolls. Constancy of the angular velocity of a workpiece along the entire length from the necking cross-section to the yield cross-section minimises twisting of the workpiece and its slippage relative to the surface of the roll due to the fact that the rolling is carried out with mushroom-shaped rolls with a withdrawal cone angle α_withdrawal that is selected in the range of 15(K-1)+1.5°<α_withdrawal<30(K-1)+3°, spread at the rollout angle β that is selected in the range of 15(K-1)(m+1)+1.5^o<β<30(K-1)(m+1)+3°, where K is pipe size diameter coefficient, m is ratio of a roll diameter in the necking to a workpiece diameter, d_mp is a pipe diameter, d₃ is a workpiece diameter, D_n is a roll diameter in the necking.

EFFECT: invention is intended to improve product quality by reducing slippage of the metal and twisting of the workpiece during screw rolling.

1 dwg