Nachi - Fujikoshi Corporation

Junichi Noshiro

Ryo Hayashi

In a hard-film-coated drill having a cemented carbide drill body coated with a hard film, the drill body is provided with a smooth region at a boundary between a flank surface and a rake surface. The surface hardness of the hard film is within 2000 to 2500 HV in Vickers hardness. A radius r1 (μm) of curvature of the first ridgeline Lwhere the smooth region and the flank surface intersect is represented by r1=0.45×D+a1 (10≤a1≤25), where D is the diameter (mm) of the body. A radius r2 (μm) of curvature the second ridgeline Lwhere the flank surface and a margin intersect is represented by r2=0.65×D+a2 (39≤a2≤67). A thickness t1 (μm) of the hard film is represented by t1=0.8×ln(D)+a3 (0.7≤a3≤3.0).

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Toyama, Japan

Junichi Noshiro