| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a metal tube by which generation of underfill in the metal tube can be suppressed.SOLUTION: A method for manufacturing a metal tube according to an embodiment includes one or more heating processes and plural upsetting processes. In the heating process, a tube end part of a metal tube is heated. In the upsetting process, upsetting of the heated tube end part is performed by use of a mandrel bar and a die. A taper angle of an outer taper part of a mandrel bar, which is used in the second or later upsetting processes is larger than a taper angle of an outer taper part of a mandrel bar which is used in the previous upsetting process.SELECTED DRAWING: Figure 4 |
