Abstract: A roller cutter drill bit adapted to drill bores in the earth comprising a bit body of steel having a plurality of bearing journals at its lower end, and a plurality of roller cutters, each having a recess therein receiving one of the journals. A radial bearing asembly for each roller cutter rotatably mounts the roller cutter on the journal, and an axial or thrust bearing assembly at the free end of each journal carries axial forces applied to the roller cutter during drilling, with the thrust bearing assembly thus being subject to rotary frictional forces and heating upon rotation of the drill bit during drilling. According to this invention, a heat dissipation member formed of material having higher thermal conductivity than steel is incorporated into the bit body. This material extends from the free end toward the attached end of the journal for conducting heat away from the thrust bearing assembly, thereby reducing bearing temperatures and providing longer bearing life.

Abstract: A rolling cutter drill bit is disclosed which utilizes a main body having a threaded end for connection in a drill string, and a plurality of rolling cutter assemblies joined to the bottom of the bit body by means such as electron beam welding.

Abstract: A rotary drill bit having a plurality of journal-mounted rotating cutters and jet passageways through which drilling fluid is discharged between the cutters is provided with removable nozzles for air or other drilling fluid. The nozzles are provided with a peripheral groove and secured in place in said passageways by the divided ends of a bifurcated retaining pin.