| 摘要 |
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.
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