| 摘要 |
<p>A one-piece cutting head (30) for a drill bit comprises a main cutting edge (40) extending substantially between opposite radial extremities (32,34) of the cutting head, and a plurality of arms (36,38) extending substantially transverse thereto. The main cutting edge (40) is an edge between rake surfaces (42,44) and relief surfaces (46,48) of the cutting head, each rake surface and each relief surface comprising a plurality of facets (60,62,64,66,68,69). Adjacent facets have a transverse edge (63,65,67,71,73) therebetween, each transverse edge extending from the main cutting edge without meeting another transverse edge, each facet also having an outer edge spaced apart from the main cutting edge. Each transverse arm (36,38) extends substantially from the outer edge of one or more facets (60,66).</p> |
