| 摘要 |
PURPOSE:To make a mandrel not separated from the holder even in case of a turning force being caused on the mandrel fitted to the holder by providing the attachment which provides with the engaging part engagable with the upper part of the holder on the lower face freely slidably on the upper face of a fitting plate. CONSTITUTION:The engaging and disengaging works of an engaging part 19 and mandrel 1 is performed by engaging the upper part of the holder 8 and engaging part 19 by locating the engaging part 19 of the attachment 18 on the upper part of the holder 8, in case of attaching and detaching the mandrel 1 to and from the holder 8. In the pipe expansion working, the attachment 18 is moved with its sliding, the engaging part 19 thereof is dislocated from the upper part position of the holder 8 and the engagement of the engaging part 19 and the upper part of the holder 8 is surely checked. Consequently, it is prevented that the mandrel 1 is separated from the holder 8, even in case of the turning force being caused on the mandrel 1.
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