| 摘要 |
PROBLEM TO BE SOLVED: To provide a boring tool capable of efficiently opening a hole with a very small diameter. SOLUTION: The boring tool 10 has a base part 12 and a tool part 14 provided at a distal end side coaxial with the base part 12. A cutter bit 15 is provided at a side face, an inclined face 20 is provided at a top end 10a, and a C-chamfered face 22 is provided at a distal end outer circumference. The outer diameter D is 0.02-0.18 mm, and the length L of a cutter bit part 16 having the cutter bit 15 is seven times or more of the outer diameter D. The dimension C of the C-chamfered face 22 is 0.075-0.35 times of the outer diameter D. A center hole 34 lower than an aluminum alloy die 30 is formed by a given tool 39 in the first process. A ventilation hole 32 is positioned by the center hole 34 and opened by the boring tool 10 in the second process. The inclination angle of the inclined face 20 in the circumference direction is 0°. COPYRIGHT: (C)2009,JPO&INPIT
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