| 摘要 |
PROBLEM TO BE SOLVED: To obtain a drilling method for drilling a hole which is resistant to cave-in of its internal wall even in an area of brittle ground, to thereby enhance cost efficiency, and to obtain a drill for use in the drilling method. SOLUTION: The drill 10 includes a cylindrical cutting bit 12, a guide portion 32, and a taper coupler 36, and a rod 26 is penetrated through these component parts. Drilling is carried out by rotating the drill 10 and pressing the cutting bit 12 onto the ground so as to apply strikes onto the same. A through hole 20 is formed in the tip portion of the cutting bit 12 at a location decentered from its center. By jetting compressed air from the through hole 20, slime is raised to a side face of the drill 10. Since the through hole 20 is decentered from the center, the drill 10 is eccentrically rotated, and the slime is pressed onto an internal wall of the hole by a side face of the guide portion 32.
|
