| 摘要 |
A drill comprising, a central cutting edge tip which is arranged on an axial portion of a distal end of a spindle body, and a peripheral cutting edge tip which is arranged on an outer peripheral portion of the distal end of the spindle body, each of the tips including a tip body, the central cutting edge tip being arranged so that its longitudinal direction is parallel with a radius direction of the spindle body, a long-side cutting edge and a long-side corner cutting edge adjacent to an axial side of the long-side cutting edge being formed as an end cutting edge, and the short-side corner cutting edge adjacent to the long-side corner cutting edge being arranged so as to go beyond the axis of the spindle body, the peripheral cutting edge tip being arranged so that its longitudinal direction is parallel with a radius direction of the spindle body, the short-side cutting edge and the short-side corner cutting edge adjacent to an outer peripheral side of the short-side cutting edge being 9 formed as an end cutting edge, and the long-side corner cutting edge adjacent to the short-side corner cutting edge being arranged so as to be inclined with respect to an axis of the spindle body.
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