Reduction of the Polygonization in Continuous Butt-weld Pipe Rolling

Abstract

This paper describes the method for eliminating the polygonization of thick-wall steel tube in a reducing mill.
(1)Roll-r.p.m. pattern which realizes the stretch pattern corresponding with O.D. reduction distribution in reducing stands.
(2)Roll caliber which satisfies such a condition that the sum of O. D. reduction in two adjacent stands is constant at arbitrary point on tubular circumference.
These two made it possible to produce the steel tube which has no polygonization even in thickwall size (for example, butt-welded pipe of 48.6φ×8.5t or 60.5φ×8.5t) and to increase the rolling yield.