| 摘要 |
There is now provided a rotary cutting tool, particularly a drill, that has at least two cutting edges that respectively comprise a main cutting edge and that respectively are disposed, particularly symmetrically, with respect to the central axis of a cutter portion, whereby the radius of the main cutting edges is less than the maximal cutting edge radius of the cutter portion. A secondary cutting edge is associated with a main cutting edge, this secondary cutting edge is curvilinear in at least a portion and is configured as smooth finishing cutting edge, this secondary cutting edge comprises a plurality of curve-forming radii, whereby in an outer smooth finishing region within the region of the maximal cutting edge radius, the curve-forming radius of the smooth finishing cutting edge is greater than the maximal cutting edge radius. The cutter portion that is adjacent to the outer smooth finishing region is tapered by a taper that diminishes the size in the direction away from the main cutting edges.
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