PIERCING ROLLING APPARATUS FOR PRODUCING ROLLED MATERIAL FREE FROM SURFACE TORSION

摘要

A piercing rolling apparatus utilizing the principle of the Stiefel Mannesmann type piercing mill and having two main rolls axes of which incline with each other vertically at the feed angle beta with respect to the longitudinal axis of the material to be rolled and cross with each other horizontally at the cross angle gamma with respect to the longitudinal axis of the material. A seamless steel pipe free from surface torsion is obtained by adjusting these angles beta and gamma .