TAPERED STEEL TUBE MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a tapered steel tube manufacturing method capable of preventing degradation of the product accuracy by the change in the outside air temperature at low cost. SOLUTION: In the tapered steel tube manufacturing method, a steel tube is tapered by allowing a drawing roller R of a drawing device S to be abutted on a circumferential surface of the steel tube while the steel tube is passed through a heating device H and heated. A temperature insulation cover 10 is provided on a space between the drawing roller R and the heating device H on the upstream side thereof so as to surround the steel tube, and the steel tube is tapered while suppressing the temperature drop of a work W heated by the heating device H. COPYRIGHT: (C)2007,JPO&INPIT