| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of an intermediate cylindrical metal fitting which can form a stepped part having a large amount of diameter shrinkage in a bridge formation part of the intermediate cylindrical metal fitting. SOLUTION: A first process in which a window part 3 is formed at a predetermined position of a cylindrical metal pipe material, a second process in which the window part 3 is separated and a connection part in a predetermined section which connects both end parts of the metal pipe material is cut to remove a part having a predetermined length in the axial direction and form extended parts 6, 7, and a third process in which the window part 3 is separated and a diameter of a connection part in the remaining section which connects the metal pipe materials is shrunk to form stepped parts 4a, 5a and form bridge formation parts 4, 5 are done. |
