METHOD OF MANUFACTURING SEAMLESS PIPES WITH A DIAMETER LESS 120 mm SCREW ROLLER Russian patent published in 2017 - IPC B21B19/00 

FIELD: metallurgical engineering.

SUBSTANCE: method includes heating the blank, piercing and rolling in several passages in a calibre formed by rolls, rulers and a short mandrel mounted on a rod, with a re-adjustment of the calibre after piercing by removing the mandrel with the stem and installing a new mandrel with a rod in the calibre by moving it axially relative to rolls and rulers without changing their position. In the first pass the blank is pierced on a spherical-conical mandrel with a reduction in the outer diameter of the sleeve by 3…20%, and when reconfiguring the calibre by removing the mandrel with the rod and installing a new mandrel with a rod, a new cylindrical mandrel is installed on which the liner is rolled, carrying out in each pass from 4 to 6 particular compressions along the wall, with relative deformation along the wall 5…20% and a decrease in the outer diameter by 8…18%.

EFFECT: improving the quality of pipes and productivity by using mandrels and rods of a diameter sufficient to prevent their plastic deformation during the piercing process.

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