Smith International, Inc.

Roger P Johns

Gary Ray Portwood

Michael S Oliver

Huy D Bui

Charles R Muren

Gilbert S Tyner

A roller cone drill bit is disclosed that leaves uncut a substantial formation core having a diameter from 10% to 25% of the bit gage diameter. The bit is designed to have normal size bearings, cone shell thickness and cutter protrusion to allow the use of standard drilling weights and RPM, thereby achieving a significant increase in drilling rate. When drilling abrasive formations, ultra hard cutting teeth are used in the cone apex to maintain the core diameter.

Core cutting rock bit

An air percussion hammer drill is disclosed for operation in an earthen formation. The air compression hammer mechanism comprises a piston that reciprocates while simultaneously rotating within its housing. A hammer drill bit slidably keyed to the bottom of the piston transfers the impact energy to the formation and rotates during operation independent of an attached drill string. The air percussion hammer assembly is therefore ideally suited to directional drilling activities.

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Terrace Mustang, OK, United States of America

Roger P Johns