| 摘要 |
PROBLEM TO BE SOLVED: To provide a digger which improves construction efficiency by preventing clogging with gravel. SOLUTION: The digger 1 is fitted to the front end of a rod 11, and is suspended in the earth for drilling work. A fixed pipe 12 for reverse circulation is fixed to the front end of the rod 11, and hydraulic motors 2, 2, which rotates a bit 3, are disposed on both sides of the fixed pipe 12. Earth and sand dug up by the rotation of the bit 3 is sucked together with dug mud water into the front end entrance of the fixed pipe 12, and is sent out onto the ground by an underwater sand pump 4, which is driven by a hydraulic motor 40, as shown by an arrow in the drawing. The digger 1 includes a fixed teeth 51 which are spaced at proper intervals and are fixed to the inner surface of the front end of the fixed pipe 12, and crushing teeth 52 which extend from the base of the bit 3 to the inside of the fixed pipe 12 and circle along the inner periphery of the fixed pipe 12 as the bit 3 rotates. Gravel is crushed by the fixed teeth 51 and crushing teeth 52, and is sent out onto the ground smoothly. COPYRIGHT: (C)2007,JPO&INPIT
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