| 摘要 |
A rotary rock bit is described having a plurality of legs extending downwardly from the main bit body. Each leg further includes an inwardly extending journal pin for rotatively supporting a cone-type cutter. An annular thrust member is provided for axially retaining the cutter onto the journal pin. In one embodiment the thrust member is adapted to extend into an annular groove formed in the journal pin with the other radial surface thereof engaging an inner annular surface of the cutter. The radial surface of the thrust member is then welded to cutter by an electron beam process. An access aperture is provided in the journal pin and leg to enable the electron beam to pass therethrough and strike the thrust member and cutter. During this operation, the cutter is rotated along with the thrust member across the access aperture to create a 360 DEG weld therebetween. In another embodiment, an annular groove is formed in the cutter cavity for receiving the thrust member. An access hole is formed in the cutter to enable the electron beam to pass therethrough and strike the engaging surfaces of the thrust member and journal pin. Similarly, relative rotational movement of the components enables a 360 DEG weld to be created.
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