| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a center-extrusion propulsion pipe of which the full length is shortened, thereby implementing sharply curved propulsion construction according to a center-extrusion propulsion engineering method. <P>SOLUTION: At one terminal side of an outer tube 15, an insertion part 15b is provided which is inserted to a collar part 12a of one adjacent propulsion pipe 11A. An inner tube 16 for extrusion makes its side terminal portion in an extrusion direction freely removable with respect to a distal end of the insertion part 12b of another adjacent propulsion pipe 11B. A length of the inner tube 16 for extrusion is set to such a length that the inner tube is accommodated within the outer tube while remaining a portion that becomes a collar part 15c at another terminal side of the outer tube 15 while a jack 17 for center extrusion is pulled in most. The inner tube is accommodated and fixed within the outer tube 15, so that the other terminal side of the outer tube 15 becomes the collar part 15c. Therefore, during center extrusion work, the inner tube is made movable inside the outer tube 15 while being fixed to the distal end of the insertion part 12b of the other adjacent propulsion pipe 11A. <P>COPYRIGHT: (C)2013,JPO&INPIT |
