| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a drill which has the improved strength of a cutting edge and achieves high speed working and a long life by controlling the discharge direction of cutting chips to an upward direction of a hole thereby efficiently discharging the chips. <P>SOLUTION: The cutting edge 14 of the drill 1 is formed in an manner retreated rearward in a rotation direction of the drill 1 in such a manner that a rake angle in the radial direction becomes large along the direction toward the outer circumferential direction of the drill 1, and the rake angle α in the radial direction at the outer circumferential end satisfies -50°≤α≤-15°. The cutting edge 14 is formed with a leading angle becoming large along the direction toward the outer circumferential direction of the drill, and with a leading angle β being 50°≤β≤110° in a range including a second cutting edge 14b and a chamfer part 19. <P>COPYRIGHT: (C)2012,JPO&INPIT |
