Diamond bit with annular mud distributing groove

Claim 1

An improved full hole diamond bit of the type which includes a shank having a side wall and a central bore; a cutting surface connected to the shank for cutting a hole during operation of the bit, the cutting surface comprising a side wall portion for scraping the wall of the hole during operation, and also comprising a core-forming portion for scraping a portion of the hole bottom during operation, the core forming portion comprising a diamond-carrying surface tapered upwardly toward the top of the bit when in the operating position; and a core ejector conduit extending from the upper end of the core-forming portion of the cutting surface through the side wall of the shank; wherein, in operation, the full hole diamond bit forms a core which passes up the core ejector conduit and is ejected through the shank side wall, and wherein the improvement comprises a system for distributing mud to the cutting surface which comprises: an annular groove provided in the core-forming part of the cutting surface; at least one fluid supply conduit connecting the annular groove with the central bore of the shank; and a plurality of channels formed in the cutting surface, said channels intersecting the annular groove; said channels being divided into at least two groups of at least one channel each, a first group of channels extending away from the annular groove along the cutting surface towards the core ejector conduit and a second group of channels extending away from the annular groove along the cutting surface toward the side wall portion thereof, whereby, in operation, drilling fluid flows from the central bore of the shank, through the fluid supply conduits, into the annular groove and then in part flows through the first group of channels in the cutting surface toward the core ejection conduit, and in part flows through the second group of channels in the cutting surface towards the side wall portion.