| 摘要 |
<p>A cutting head comprises a drill tip (4) which in its turn comprises a chisel edge (5), at least two main cutting edges (6) which each extend between a central end at said chisel edge and an outer end and a recess (17) associated with each main cutting edge and located at each side of the chisel edge. Each said recess (17) comprises a chip breaking groove (18) extending along the main cutting edge (6) spaced from the main cutting edge by a distance.</p> |
