| 摘要 |
PROBLEM TO BE SOLVED: To obtain a drill for rock-like matter high in twist rigidity having the fixing surface of a large cutting blade regardless of configurational restriction for directly fixing a tubular element and capable of sufficiently discharging hole cutting refuse. SOLUTION: In the drill for rock-like matter having a drill head 5 provided with the cutting blade 6 and constituted of a hard material and a shaft 3 provided with at least one spiral ridge 7 constituting a spiral groove 2, the free space of the spiral groove 2 along the length in the axial direction of the spiral groove is made large as separated from the drill head in the axial direction of the spiral groove. Preferably, the height of the spiral ridge 7 related to a core diameter 12 is made taper in a conical shape toward the drill head. Further, the spiral ridge is formed into an almost equal shape other than its height when looked from a transverse cross section of a spiral and the height of the spiral ridge of the shaft in the region adjacent to the drill head 5 in the axial direction is reduced.
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