| 摘要 |
<p>A novel form of drill bit is disclosed. The bit (30) comprises a bit body having a leading face (32) and gauge surface (44, 46). Cutting inserts (32, 34, 36) are set into the bit body, each cutting insert being in the form of a segment of a composite PCD (polycrystalline diamond) or PCBN (polycrystalline cubic boron nitride) composite. Thus each insert has a PCD or PCBN compact (40) carried by a carbide backing (42). The PCD or PCBN compact of each insert is exposed at the leading face or at the gauge surface to perform an axial cutting or gauge maintenance function during drilling.</p> |
