| 摘要 |
PROBLEM TO BE SOLVED: To obtain a device excavating a pile hole 16 of a concrete prefabricated pile 15 with a widened diameter of the front end (the lower end) without removing earth. SOLUTION: Approximately fan-like recessed surfaces 4 opened toward the outer circumference 3 on the lower surface of a lower end plate 2 of a rotatable steel pipe 1 around the center line (c) are formed around the center line (c) at regular intervals, the pivot 5 is provided to the point of each fan-like recessed surface 4, a forward and reverse freely movable cutting edge 6 is provided along the fan-like recessed surface 4 with a pivot 5 as the center, the front end of a cutting edge 6 is projected from the outer circumference 3 on the lower surface of the lower end plate 2, a projected end 6a is diagonally crossed with the outer circumference 3, and the diagonally crossed direction(b) is separated from the outer circumference 3 toward the opposite direction to the rotational direction (a) of the lower end plate 2. COPYRIGHT: (C)2004,JPO
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