| 摘要 |
PROBLEM TO BE SOLVED: To provide a sand pile manufacturing hollow pipe for omitting the connecting work of the hollow pipe, and manufacturing a sand pile having an improved deep depth even if a height is restricted. SOLUTION: This sand pile manufacturing expansion hollow pipe 1 is composed of an upper outer tube 2 and a lower inner tube 3 with a built-in air valve 4 extensively fitted to the upper outer tube 2, and is provided with a first lock means 5 for fixing the upper outer tube 2 and the lower inner tube 3 in a contracted state, a second lock means 6 for fixing the upper outer tube 2 and the lower inner tube 3 in an extended state and a pressurized air supply means for supplying air in a pressurized air part 34 partitioned by the air valve 4 of the lower inner tuber 3. COPYRIGHT: (C)2004,JPO
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