| 摘要 |
PROBLEM TO BE SOLVED: To provide a core drill for cutting work of a sapphire single crystal boule which is used for drilling and taking out a columnar ingot from hard brittle material (single crystal boule) such as sapphire single crystal with a drilling device, can reduce friction resistance upon a drilling operation and, further, has improved discharge performance of sludge produced by drilling.SOLUTION: A core drill 10 for cutting work of a sapphire single crystal boule allows a plurality of segment chips 50 for cutting an object to be drilled to be adhered to a tip of a blind cylindrical core bit 20 formed of a helical groove 30 on a lateral surface at an equal interval. Therein, the segment chip 50 has a cut surface of a curved surface of which the curvature radius R is 1.5 to 5.0 mm and is formed of a groove going to the helical groove of the core bit in the circumferential direction.SELECTED DRAWING: Figure 1 |
