TUBE REDUCING APPARATUS AND ROLL FOR TUBE REDUCING APPARATUS

摘要

A tube reducing apparatus, comprising a plurality of stands disposed along a rolling axis, wherein a tube is passed through the plurality of stands along the rolling axis for reducing. Each of the stands comprises rolls of (n) in quantity (n >= 3) disposed around the rolling axis, and the rolls of (n) in quantity are displaced 180°/n around the rolling axis from the rolls of (n) in quantity contained in the stand on a previous stage. Each of the rolls of (n) in quantity contained in the stands excluding the last stand comprises a groove of arch shape in cross section. The bottom part of the groove is formed in an arc shape having a first radius about the rolling axis in cross section, and a distance between the surface of a roll flange part positioned between the bottom part of the groove and the edge of the groove and the rolling axis is longer than the first radius, and a distance between the edge of the groove and the rolling axis is longer than the first radius at the groove of the roll contained in the stand on the previous stage. Accordingly, the tube reducing apparatus can suppress both the angulation of inner surfaces and the occurrence of damage to edges.