An improved journal bearing for rotary cone type mining or oilfield rock bits is disclosed. Such rock bits typically have several cutters each rotatably mounted on a cantilevered bearing pin. The cutter and respective bearing have complementary journal bearing surfaces. A retainer is provided at one end at the bearing surfaces for keeping the cutter on the bearing pin and a seal is provided at the opposite end. In addition to the usual axial thrust surface located towards the radially inner end of the bearing pin, one or more secondary axial thrust surfaces are provided in one embodiment of the invention. Alternatively, at least one series of grooves or other axial lubricant flow restrictor is provided at the complementary bearing surfaces. The invention greatly improves the load carrying capacity of the bearing.
An earth boring bit has rotating cones with two lubricant passages to increase bearing capacity and cause lubricant circulation. A lubricant reservoir in the body supplies lubricant to passages between the cone and bearing pin. A pressure compensator equalizes lubricant pressure to the exterior of the bit. A first passage leads from the reservoir to the upper side of the bearing pin. A second passage leads from the reservoir to the bearing pin at a point from 185 degrees to 225 degrees as seen from an inner end of the bearing pin. This point is located in a diverging region 51d of an annular clearance surrounding the bearing pin.
An abrasive wear-resistant material includes a matrix and sintered and cast tungsten carbide pellets. A device for use in drilling subterranean formations includes a first structure secured to a second structure with a bonding material. An abrasive wear-resistant material covers the bonding material. The first structure may include a drill bit body and the second structure may include a cutting element. A method for applying an abrasive wear-resistant material to a drill bit includes providing a bit, mixing sintered and cast tungsten carbide pellets in a matrix material to provide a pre-application material, heating the pre-application material to melt the matrix material, applying the pre-application material to the bit, and solidifying the material. A method for securing a cutting element to a bit body includes providing an abrasive wear-resistant material to a surface of a drill bit that covers a brazing alloy disposed between the cutting element and the bit body.
