| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel tube manufacturing method by the solid phase press welding in which the increase in wall thickness of internal and external surfaces of a seam portion is suppressed, and the internal and external surfaces of the seam portion are smoothed. SOLUTION: In the manufacturing method in which a steel strip 1 is continuously rolled by a form roll to form an open tube 7, both edges thereof are induction-heated to the temperature range below the melting point, and butt- welded by a squeeze roll to manufacture the steel tube 8, an edge end forming an internal surface side of the edges of the open tube and an edge end forming an external surface side thereof are formed in advance before the butt-welding. These edge ends are preferably formed on the steel strip before forming the open tube. |
