| 摘要 |
This invention relates to a polygonal turning insert having primary cutting edges (12), which individually include a nose edge (14) and two main edges (15), which converge toward the same. Behind the nose edge, chip-directing guide surfaces are formed, viz., on one hand, a breast surface (24) included in a knob (20) situated behind the nose edge along a bisector between the main edges (15), and, on the other hand, a pair of flank surfaces (21) included in a land being behind. According to the invention, at a distance behind the knob (20), there is formed a second breast surface (25), the upper part of which is situated on a higher level than the upper part of the first breast surface (24). In such a way, it is guaranteed that thin chips, which tend to pass or jump over the first breast surface without being affected by the same, will impinge on the second, higher breast surface and be subjected to guiding by the same. |
