| 摘要 |
PROBLEM TO BE SOLVED: To reduce inner wall surface roughness of a forming work hole even in a drill for improving abrasion resistance by covering a surface of an edge part with a hard coating film. SOLUTION: The surface of the edge part 12 is covered with the hard coating film, and polishing work is applied to a surface of first and second margin parts 52 and 54 formed in a land part 50 of at least the edge part 12. Surface roughness Ra of the polishing work-applied first and second margin parts is set in a range of 0.1μm to 0.3μm. COPYRIGHT: (C)2004,JPO&NCIPI
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