| 摘要 |
<p>The present invention provides a drill bit (1 ), and a method for its manufacture, that is suitable for use within a casing drilling process. The drill bit (1 ) comprises a monolithic body (5, 6, 8) made from bronze, e.g. aluminium bronze or nickel aluminium bronze, and a relatively hard material mounted thereon. The hard material may comprise polycrystalline diamond (PDC), tungsten carbide or cubic boron nitride. In one embodiment the monolithic body comprises a crown (6) and a plurality of cutting members (5). The hard material may be mounted directly on the crown or, alternatively, on the cutting members (5). The described drill bit (1 ) facilitates the drilling of hard rock formations while still being capable of being drilled through by a standard oilfield drill bit.</p> |
