| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for removing soil on a screw of an earth auger with no leader. SOLUTION: In a soil removing method, vibration is given to a screw 3 on the way of drilling a ground 27 and then pulling an auger 1 out thereof to drop soil off from spiral grooves in the screw coming out of a drilled hole, the vibration is given to the screw being rotated. An auger driving unit 2 has a vibrator 4 installed thereon for giving vibration to the screw 3 perpendicular to its shaft, the vibrator 4 being mounted on a weight mount 11 or on a weight 12 mounted thereon. Protrusions 17 are provided on the outer periphery of the shaft of the screw 3 corresponding to the bottoms 15 of the spiral grooves at proper spaces along the direction of spiral grooves. The protrusions 17 is formed with front portions 19, in the rotating direction of the screw during drilling, relatively gently rising and rear portions 20 lowering more sharply than the front portions.
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