| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a drill capable of suppressing a cutting edge fracture or wearing, while ensuring the sharpness at a leading edge of a drill body.SOLUTION: A drill includes: a drill body 1 rotated about an axis; a chip discharge groove 2 formed on an outer peripheral surface of the drill body 1, and spirally extending from a tip end of the drill body 1 toward a base end side; a cutting edge formed at an intersecting ridge line portion between a wall surface 2a facing a drill rotating direction of the chip discharge groove 2 and a tip end surface of the drill body 1; and a leading edge 5 formed at an intersecting ridge line portion between the wall surface 2a facing the drill rotating direction of the chip discharge groove 2 and the outer peripheral surface of the drill body 1. At the leading edge 5, a first projecting curved surface portion 11 is formed, which extends in an extending direction of the leading edge 5 and has a projecting curve-shaped cross section vertical to the extending direction. A curvature radius of the first projecting curved surface 11 is 20-100μm.</p> |
