| 摘要 |
A drill bit cable of breaking off and milling up the core of a material being drilled is disclosed. The drill bit includes a shaft having an internal fluid conduit, and a working portion adapted to drill a hole. The working portion includes an exterior shoulder and an exit port. The exit port comprises an exit channel that communicates fluid from the fluid conduit to the working portion of the drill bit. The axis of the exit channel is offset from the axis of the drill bit. The exit channel at least partially overlaps the axis of the drill bit in order to define the diameter of the core formed during the drilling process. The exit port also includes a radially expanding interior shoulder that is adapted to break off the core and mill up the core fragments to prevent the core from entering into the fluid conduit.
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