Importance

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Abstract

A drill bit for connection on a drill string has a hollow tubular body with an end cutting face provided with a tungsten carbide coated surface 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 for receiving a removable and interchangeable nozzle member therein. The cutting face 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 recesses in the cutting face have milled offset recesses adjacent to the edges thereof which are sized and positioned to permit the cutting discs to be partially recessed and to restrain the cutting elements from rotation during use. The cutting face is coated with tungsten carbide to a thickness of 0.012-0.040 in. by means of a high-velocity, high-temperature plasma coating process after the cutting elements are assembled in the bit body. This process coats the steel bit body with tungsten carbide without coating or otherwise affecting the cutting inserts. The coating is metallurgically bonded to the steel bit body and protects against wear during drilling for periods of several hundred hours.

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First Claim