| 摘要 |
PROBLEM TO BE SOLVED: To increase the supplied quantity of a cutting fluid without impairing the strength and rigidity of a drill body or a cutting edge. SOLUTION: A swarf discharging flute 4 is formed on the periphery of a point in the drill body 1, a cutting edge 6 is formed at an intersecting ridge line of a rake face formed on an internal periphery of the swarf discharging flute 4 with a top major flank 3 of the drill body 1, and a cutting fluid supply hole 11 directed from the rear end side to the point is drilled inside the drill body 1, and the supply hole 11 is opened so as to form three holes or more of openings 12 in the top major flank 3. COPYRIGHT: (C)2004,JPO
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