TUBE EXPANSION METHOD

摘要

A tube expansion method in which a drain pipe (3) that is a pipe member is inserted into and installed onto a through hole (2) both end opening portions of which are formed at an angle after an expansion in diameter. The present invention comprises an inserting step in which the drain pipe is inserted into the through hole in such a manner that an end portion protrudes from both end opening portions of the through hole, a subsequent tube expanding step in which a tube expansion tool (5) is inserted into the drain pipe and the drain pipe is expanded in diameter to reach a predetermined inner diameter while moving the tube expansion tool from one end portion of the drain pipe toward the other end portion, a subsequent cutting step in which each end portion of the drain pipe protruding from each opening portion of the through hole is cut along a diagonal shape of each opening portion, and a subsequent welding step in which the end portion of the drain pipe that is cut is welded with the opening portion of the through hole.