| 摘要 |
PROBLEM TO BE SOLVED: To provide an excavation device for an earth drill having no possibility of to breaking a hydraulic device in conducting the expanding work of the bottom area of a vertical hole and fittable to a relatively small earth drill. SOLUTION: This excavation device is provided with a blade-like excavation section 322 opened by the depressing force of an earth drill work machine 400 and the reaction from the hole bottom. The excavation section 322 is provided with a cutting edge 326 toward the rotating direction of the earth drill, and the wall face of the vertical hole around the hole bottom is drilled to expand the bottom area.
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