Smith International, Inc.

Ernest L Buford

Zhou Yong

Peter M Davies

Hubert W Penka, Jr

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.

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Ponca City, OK, United States of America

Ernest L Buford