improvement in systems of bearings for bits of rock drills

摘要

A roller cone rock bit is disclosed with an improved bearing system. The improvement comprises a journal bearing (41) which is substantially frusto-conically shaped and a roller cone bearing (42) which is reverse shaped to mate with the journal bearing. The invention also includes a means (43) for maintaining the journal and roller cone bearing in compression against each other. In the preferred embodiment, the journal and roller cone bearings comprise polycrystalline diamond and the compression is maintained by a threaded bolt (43) which is tightened to the point of putting the bolt in tension. In one preferred embodiment, the bolt is threaded into the cone and rotates in the center of the journal. In another preferred embodiment, the bolt is threaded into the leg (34) of the journal and the cone rotates about it. In both of these embodiments, thrust bearings (45, 46) are located between the head of the bolt and the leg or cone surface contacted. The bolt's threads can either be locked in place, or allowed to self- tighten as the cone rotates during drilling. The invention has application in extending the life of bits used in oil, gas and geothermal drilling operations. IMAGE