| 摘要 |
Journal bearings are employed to rotatably support the roller cones of a drill bit for drilling wells or the like. Enough clearance is provided at the journal bearing between the bearing pin and the roller cone to accommodate a thick film of fluid lubricant. The bearing is sonically driven, preferably by means of a resonant vibration system, in a torsional vibration mode, the torsional energy being developed in an elastic column which receives such energy from an orbiting mass oscillator. The roller cone is also mechanically rotated by virtue of conventional rotary motion of the drilling string. The energy provided at the bearing from the resonant vibration system, in view of its periodically reversing high G acceleration short-time duration force pulses, effectively operates to increase the gap in the forward portions of the journal bearing between the bearing pin and the roller cone during the "rearward" acceleration of the sonic vibration cycle causing the lubricant to run from the rear portions of the bearing around to the forward portions thereof where the lubricant builds up a thick film so that when the "forward" portion of the cycle reoccurs, there will be an ample oil film in these forward loaded portions to provide the needed lubrication.
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