Abstract: A medium to high carbon steel body of a roller cone for a drilling bit is machined to final dimensions, and is thereafter rendered absorbent to laser light by application of black paint or black etch. Holes for hard tungsten carbide or like inserts are drilled in the light absorbent steel body. The entire steel body, including the holes, is subjected to a laser treatment which, however, is effective to raise to above austenitizing temperature only the dark light absorbent surfaces. Walls of the insert holes, being shiny, reflect the laser light and are not effected by it. Rapid self-quenching of the laser heated surfaces results in a hard martensitic layer in the external surface, with a surface hardness of 57 to 60 Rockwell C units. The seal gland, heel, and spindle bore areas of the roller cones are hardened similarly by exposure to laser light. In an alternative process, the hard tungsten carbide or like inserts are press fitted into the holes before the laser treatment.

Abstract: Tools, and particularly rock bit cutter cones, having "hard" cermet cutter inserts enveloped in an intermediate layer or coating of a suitable high melting metal, and embedded in a cast steel matrix, are disclosed. The cermet inserts, which usually comprise tungsten carbide in a cobalt phase (WC-Co), are coated with a layer of a metal or metal alloy, preferably nickel, which does not substantially melt during the subsequent step of casting the steel matrix of the tool. An additional layer of copper is advantageously employed on the cermet insert beneath the layer of the high melting metal, such as nickel. The coated inserts are held in appropriate position in a suitable mold, and the steel matrix of the tool is poured from molten metal. The coatings on the cermet inserts prevent thermal shock to the inserts, prevent deterioration of the cermet due to diffusion of carbon into the adjacent steel, and metallurgically bond the inserts to the embedding steel matrix.

Abstract: A belleville seal for a sealed bearing rotary cone rock bit. The inner static ring portion of the annular belleville seal is metal and is interference fitted over the base of a journal bearing. The separation joint formed between the inner diameter of the static ring portion of the belleville seal and the outside diameter of the journal bearing is circumferentially welded using a high-energy beam source to form a hermetically sealed metallurgical bond therebetween.

Abstract: This invention relates to a belleville seal for a sealed bearing rotary cone rock bit. The inner static ring portion of the annular belleville seal is metal and is interference fitted over the base of a journal bearing. The separation joint formed between the inner diameter of the static ring portion of the belleville seal and the outside diameter of the journal bearing is circumferentially welded using a high-energy beam source to form a hermetically sealed metallurgical bond therebetween.

Abstract: A resilient O-ring shaft seal for use in a rotary rock bit is described wherein the degree of squeeze imposed upon the O-ring seal is increased in one or more discrete steps, occurring as drilling conditions or bearing deterioration cause rising temperatures to be imposed on the seal. The squeeze is increased in discrete steps through a thermally related shape change in one or more nitinol, or the like, back up rings positioned adjacent to the packing ring seal housed within a seal gland. The seal gland is formed between a rock bit journal and a rock cutter cone rotatably mounted to the journal.