Importance

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Abstract

A new and improved drill bit for connection on a drill string has a hollow tubular body with an end cutting face and an exterior peripheral stabilizer surface with cylindrical sintered carbide inserts positioned therein. Nozzle passages extend from the interior of the bit body through the cutting face, preferably at an angle of about 10.degree.-25.degree. relative to the longitudinal axis of the body, and consist of a passage in the bit body and a removable and interchangeable nozzle member. The nozzle member is secured in place either by peripheral grooves and snap rings or aligned smaller passages in the nozzle member and the bit body having a retaining pin positioned therein. The cutting face preferably has a plurality of recesses therein which receive, by an interference fit, a plurality of cutting elements of the type known as STRATAPAX, consisting of a cylindrical stud having an angular supporting surface with a cutting disc bonded thereon consisting of sintered carbide having a cutting surface of polycrystalline diamond. The studs of the cutting element may have a groove along one side which aligns with a small recess along the side of the cutting element recess to receive a metal pin operable to secure the cutting element in place and against twisting. Additionally, an offset counterbore may be provided at the top of the cutting element recesses which provide for stress relief of the cutting elements during cutting operation.

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First Claim