| 摘要 |
The cutter (1) has a shaft portion (2) with a cylindrical cross-section and extended along a center axis (M). A cutting portion (3) is connected at a distal extremity (4) of the shaft portion. The cutting portion comprises an upper surface (5) and a lower surface (6) forming cutting edges (7, 8) in a plane. The cutting edges in a region of another distal extremity (9) of the cutting portion strike on each other and form a tip (10). The tip is rounded off with a curvature (11). The curvature is extended around a center. |
