| 摘要 |
PROBLEM TO BE SOLVED: To make in an almost perfect round shape a rolled pipe body for pipe-in-pipe working. SOLUTION: In the pipe line-renewing method, locking tools 12 are placed at four positions in the inner-circumference of a circular pipe body 11 having unconnected edges. Wires 15 extended radially inside are all locked respectively to the locking tools 12, and guided to one axial direction of the pipe body 11 by pully blocks 27 placed to bases 23 of an intermediate work 22. All the wires 15 are pulled in one axial direction of the pipe in the state in which reaction force is acted on the intermediate work 22. Thus, in the inside periphery of the pipe body 11 where the locking tools 12 are fixed, a roll-up force acts evenly in a wide range in the peripheral direction. As a result, the pipe body 11 is contracted in a cylindrical shape in the cross section. The pipe body 11 in the contracted state is inserted into a sleeve pipe, and the wire tension is released within the sleeve pipe to expand the pipe body. COPYRIGHT: (C)2009,JPO&INPIT
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