METHOD OF SEAMLESS TUBE PRODUCTION Russian patent published in 2012 - IPC B21B19/04 

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy, particularly, to screw piercing and continuous lengthwise rolling mills. Proposed method comprises heating entry shell, center-drilling, piercing at screw piercing mill on mandrel, rolling at lengthwise rolling mill on mandrel, sizing, cooling and straightening. After piercing, shell is rolled at screw rolling mill on short taper mandrel on feeding the shell rear end into deformation site wherein roll turn axis is shifted relative to nick section through 0.05-0.25 of roll barrel length toward deformation zone exit, while inlet cone inclination is some 1.0-2.5° smaller than inclination in deformation site at piercing.

EFFECT: intensified treatment of metal structure, reduced stretching strains.

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