Smith International, Inc.

Peter M Davies

Dennis D Bond

Hubert W Penka, Jr

Zhou Yong

Cary A Roth

Ernest L Buford

Disclosed is a rolling cone cutter and drill bit employing multiple inserts retained as a cluster in an aperture in the cone cutter. Apertures in which the insert clusters are retained are multilobed apertures formed by intersecting bores formed in the cone steel. The apertures may also be created by forming spaced apart bores and milling regions of the cone steel that extends between the bores. The inserts in a cluster may be retained within the aperture to differing depths, may extend above the cone steel to differing extension lengths, and may have cutting portions having a variety of shapes. The inserts in a cluster may be made of different materials in order to optimize cutting duty. The bores forming the multilobed aperture may be parallel or skewed, and may create an aperture having a multilevel bottom surface so as to permit the insertion of an insert having a relatively large cutting surface in instances when the cone design would not otherwise permit the use of a cylindrical insert of the desired diameter.

Drill bit and cutter having insert clusters and method of manufacture

A method is disclosed for forming a drill bit structure to which a cutting element is to be affixed. The method includes applying a layer of hardfacing material to a basic bit structure, removing the layer of hardfacing material in a location to which the cutting element is to be affixed, and forming an attachment structure at the location. In one embodiment, the removing is performed by electrode discharge machining. In one embodiment, the basic bit structure is a roller cone, and the cutting element is an insert adapted to be interference fit within a socket in the roller cone.

Hardfaced drill bit structures and method for making such structures

A method of manufacturing a rock bit leg from a rough bit leg forging is disclosed whereby multiple machining operations are performed by a six-axis CNC machining center. Three dimensional datum surfaces are initially formed on a rough leg forging. The rough leg forging is then mounted in a holding fixture. The fixture, including the leg forging, is secured to the six-axis CNC machining center. A three dimensional datum reference from the leg forging is set into the NC function of the six-axis machining center. The rough leg forging includes a pair of extended flanges coincident with the 120.degree. leg surfaces. The leg flanges mount to complimentary surfaces formed on the leg holding fixture, thus securing the leg within the fixture without interference of any of the machining processes. The CNC machining center performs a majority of the material removal operations to prepare the leg for subsequent assembly through manipulation of the six interactive axes of the CNC machining center. The machining center positions the rough forging of the rock bit leg in any and all attitudes necessary to accomplish each of the separate material removal operations thereby maintaining extremely close tolerances since the leg forging remains indexed to and secured within the fixture throughout all of the machining processes.

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Ponca City, OK, United States of America

Peter M Davies