| 摘要 |
PROBLEM TO BE SOLVED: To improve durability by restraining welding of a margin without impairing brazing strength of a cutting edge tip. SOLUTION: Since the surfaces of margins 18, 20 are provided with a diamond film 32, welding to the margins 18, 20 is restrained, and on the other hand, since the cutting edge tip 24 is brazed to the drill body 12 after coating with the diamond film 32, a predetermined brazing strength is obtained to substantially improve the life of a tool. Since the cutting edge tip 24 is brazed to the drill body 12 after coating with the diamond film 32 and the cutting edge 30 or the like is shaped, there is no fear that the knife edge is rounded due to coating of the cutting edge 30 with the diamond film 32, and excellent sharpness is obtained to further improve the working accuracy. COPYRIGHT: (C)2006,JPO&NCIPI
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