| 摘要 |
PROBLEM TO BE SOLVED: To provide a rotary cutting tool for cutting a hole such as a blind hole, from which chips are hardly discharged, capable of efficiently discharging chips, preventing the accuracy of a cut surface and the state of a blade tip from being degraded, easily regrinding a cutting edge, and prolonging the lifetime thereof. SOLUTION: In the rotary cutting tool, a tip is provided on a fore end of a shaft-like base member, and a fore end cutting edge and an outer circumferential cutting edge are provided on a fore end side of the tip and on the outer circumferential side of the tip, respectively. A breaker piece is provided on a rake face of the tip, an erection face is formed in the direction directed to the fore end side of the tip of a face constituting the breaker piece and across the axis of rotation. A protrusion is provided on the erection face. The protrusion has a substantially V-shaped section in the direction orthogonal to the rake face and parallel to the fore end cutting edge. The substantially V-shaped fore end is formed to be on the rake face side with a space from the rake face. Preferably, the angle of the substantially V-shaped fore end is 3-20°, the distance from the substantially V-shaped fore end to the rake face is 1.0-4.0 mm, and the angle of inclinationβof the erection face is 15-45°. COPYRIGHT: (C)2009,JPO&INPIT
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