| 摘要 |
A drill insert includes a pair of cutting webs inclined relative to each other, a pair of transversely opposed cutting portions, each cutting portion partially defining a side portion of a corresponding cutting web. Each cutting portion includes an outer cutting edge, an inner cutting edge connected to the outer cutting edge and having a positive rake angle, and a notch having a first face, a curved second face and a curved valley, the curved valley connecting the first face and the second face. The first face is bound by the curved valley and the inner cutting edge. The drill insert further includes a chisel defined by the first face, the valley, the second face and the inner cutting edge of each cutting portion and the cutting webs converging to a point region.
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