Method of producing tubular body in a press roll piercing mill

摘要

A method of producing a cylindrical metallic tubular body in a press roll piercing mill. The method involves applying a pressing force to a polygonal metal billet in the axial direction thereof while guiding the billet by means of a guide during its advance, rolling corner portions of the billet to a certain degree with a pair of rolling rolls having semicircular grooves disposed above and below the billet prior to the contacting of a plug with the center of the front end surface of the billet, and successively piercing the billet by means of the plug while the billet is rolled, the tip portion the plug being retained on the pass center line by the rolling rolls.