| 摘要 |
A cutting insert (22) has an upper rake surface, peripheral flank surfaces, a base, and a central axis of rotational symmetry, the intersection between the upper rake surface and the peripheral flank surfaces forming at least one cutting edge. The peripheral flank surfaces of the cutting insert include a first flank surface portion (28) bounded in part by the cutting edge and in part by a lower boundary, the first flank surface portion having a primary positive relief angle, and a second flank surface portion (30) extending from the lower boundary towards the base, the second flank surface portion having a relief angle no greater than about zero. The positive relief angle is typically less than about 30 DEG , and preferably between about 4 DEG and about 20 DEG . Optionally, the peripheral flank surfaces may further include a third flank surface portion (40) extending from adjacent to the second flank surface portion towards the base, the third flank surface portion having a secondary positive relief angle.
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