| 摘要 |
PROBLEM TO BE SOLVED: To restrain crazing and cracking of a work and to attempt extension of longevity of a cutting tool in the case of applying cutting work on a brittle material. SOLUTION: Head end surfaces 15, 15 made of two flat surfaces are formed on a head end of a columnar axial knife edge part 12, and a linear crossing crest line of these head end surfaces 15, 15 is made into a cutting blade 16. The overall surface of the knife edge part 12 is covered with a diamond film. The cutting blade 16 extends in the diametrical direction of the knife edge part 12 as seen from the head end side in the axis O direction, extends in a direction orthogonal with the axis O as seen from a side surface of a tool main body 11, and it reaches an outer peripheral surface 12A of the knife edge part 12. A holding angleθmade by the two head end surfaces 15, 15 is set in a range of 45 deg.<=θ<=175 deg.. Two chip discharge grooves 41, 41 extending to the base end side from the head end are formed on an outer periphery of the knife edge part 12. Central thickness d of the tool main body is set more than 0.5D against an outside diameter D of the cutting blade 16.
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