摘要 |
A rotary drill bit comprises a bit body (10) having a shank for connection to a drill string, a plurality of cutting members (14) mounted at the surface of the bit body, and a passage in the bit body for supplying drilling fluid to the surface of the bit body. The cutting member (14) consists of a cutting element (18) on a stud (19), each cutting element (18) comprising a thin hard facing layer (21), for example polycrystalline diamond, bonded to a less hard backing layer (22), for example tungsten carbide. The maximum instantaneous load to which each cutting element (18) may be subject in use is reduced by reducing the thickness of the cutting element. A method of diffusion bonding of the cutting element (18) to the slud (19) is disclosed. |