A method of manufacturing a steel pipe having a different thickness and a steel pipe having a different thickness

摘要

A method of manufacturing a steel pipe having a different thickness from a hollow tube-like base pipe, comprising the steps of arranging the base pipe in a die and regulating the movement of the base pipe in the longitudinal direction, Wherein the plug is inserted from one end side of the tubular body to enlarge an outer shape of the one end side to be caught by the die; And an ironing process for widening the inner shape while maintaining the outer shape of the primer tube is performed to form a thin wall portion.