| 摘要 |
PROBLEM TO BE SOLVED: To expand, in a proper state, the tube of a tube member inserted into a through-hole, the opening part of which has an oblique shape to the axial center.SOLUTION: In a method of expanding a tube, a drain tube 3 of a tube member is inserted into a through-hole 2 formed obliquely in the opening portion at both ends thereof and mounted by expanding the tube, and the method includes: an insertion step where the drain tube 3 is inserted into the through-hole 2 so that the ends are projected from the opening portions at both ends of the through-holes; a tube expanding step where next, a tube expanding tool 5 is inserted into the inside of the drain tube 3 and the drain tube 3 is expanded to a predetermined inside diameter while moving the tube expanding tool 5 from one end of the drain tube 3 to the other end; a cutting step where next, each end of the drain tube 3 which is projected from each opening portion of the through-hole 2 is cut along the oblique shape of each opening portion; and a welding step where next, the end of the cut drain tube 3 and the opening portion of the through-hole 2 are welded. |
