PIERCING MILL FOR HELICAL ROLLING Russian patent published in 2006 - IPC B21B13/00 B21B19/02 B21B31/00 

FIELD: rolled tube production processes and equipment, namely piercing mils for helical rolling.

SUBSTANCE: piercing mill for helical rolling includes working stand with one barrel-shaped upper roll and with two barrel-shaped lower rolls whose symmetry axes are shifted in vertical plane relative to rolling axis; rotation drive mechanism of lower rolls. Upper roll is provided with drive mechanism arranged at side of working stand opposite relative to arrangement of lower roll drive mechanism. Gorge radius Rx of upper roll is calculated with use of expression: Rx = (Rb + Ru + h)/ (Ru/Rb - h/Rb - 1) where Ru - radius of upper roll, Rb - radius of pierced blank, h - shift value of symmetry axis of lower rolls relative to rolling axis along gorge radius, is in range 0 - 200 mm.

EFFECT: improved quality of pierced sleeves, enhanced biting of blank between rolls.

4 dwg