Abstract: A gage surface cutting element (22, 30, 50, 70, 100, 120) for a cutter (20) in a roller cone drill bit (10) has a generally cylindrical body (32, 52, 72, 102, 122) formed of a hard and wear-resistant material. The cutting end (34, 54, 74, 104, 124) of the cutting element (22, 30, 50, 70, 100, 120) has a generally conical cutting surface (38, 58, 78, 108, 128) substantially perpendicular to a longitudinal axis of the cylindrical body (32, 52, 72, 102, 122). A plurality of generally parallel shallow and elongated grooves (40-42, 60-63, 80-82, 110-112, 130-132) are formed in the conical cutting surface (38, 58, 78, 108, 128), and a plurality of elongated strips of an ultra hard material (44-46, 64-67, 84-86, 114-116, 134-136) is disposed in the grooves. The result is a conical cutting surface (38, 58, 78, 108, 128) that has alternating hard and ultra hard cutting surfaces that can be oriented at 0.degree., 90.degree., or any angle in between with respect to the rotational direction of the cutter cone (20).

Abstract: A drill bit including at least one rolling cutter body with rows of relatively hard substantially outwardly projecting and circumferentially spaced cutting inserts projecting from the cutter body and having effective erosion reducing features by application of hardfacing materials placed in oriented regular patterns and shapes on designated critical and vulnerable cutter body areas. The cutter body is produced by a method wherein the body is marked in specific locations of desired patterns, shapes, or boundaries, and, then, hardfacing is applied in these specific boundaries to avoid the insert hole locations. After the hardfacing is permanently bonded to the specified areas, the holes are drilled and the hard cutting inserts are pressed into the holes.

Abstract: A rotary rock bit is provided having a lubrication system with an expansion space within the lubricant reservoir to accommodate changes in lubricant volume. A flexible diaphragm is located within the lubricant reservoir. The lubricant reservoir is filled with lubricant thereby moving the flexible diaphragm to a substantially completely filled position. A predetermined volume of lubricant is displaced from the lubricant reservoir by forcing a fluid through passage means in the reservoir cap, moving the flexible diaphragm and displacing a predetermined volume of lubricant thereby providing an expansion space within the lubricant reservoir.

Abstract: Lubricant is circulated from a lubricant reservoir to the bearings of a rotary rock bit and back to the lubricant reservoir by a lubricant circulation system that is operated by rotation of the cone cutter upon the bearing pin of the bit. A seal is positioned between the rolling cone cutter and the arm of the bit to maintain lubricant in the bearing area and to prevent fluid in the borehole from entering the bearing area. A lubricant reservoir is located in the bit body. A first passage connects the lubricant reservoir with the bearing area to channel lubricant from the lubricant reservoir to the bearing area. A second passage extends from the bearing area to the lubricant reservoir to allow lubricant to be channeled back to the lubricant reservoir.