| 摘要 |
PROBLEM TO BE SOLVED: To obtain an auger screw capable of preventing sediment discharge on the ground while controlling increase in resistance against shaft rotation, and drilling a straight excavation pit.SOLUTION: An auger screw comprises an auger shaft 11 moved up and down and rotated and driven by an auger machine 2, an auger head 12 installed at the bottom edge of the auger shaft and is rotated in a normal direction along with the auger shaft for drilling the ground R, and a spiral plate 21 installed on the auger shaft above the auger head. The spiral plate is of a spiral form that moves upward as the shaft is rotated in a normal direction during drilling operation, and its undersurface is slanted or curved in the radial direction so that the central section in the radial direction is positioned below the peripheral section. The outer diameter of the spiral plate equals to or is less than the diameter H of the rotating auger head, but is 80% or greater of the outer diameter H of the rotating auger head. A cylinder 22 having an outer diameter that is the same as the outer diameter of the spiral plate is installed around the auger shaft above the spiral plate, continuously with the spiral plate 21 and coaxially with the auger shaft. |
