| 摘要 |
<p>A rolling cutter drill bit has at least one roller cutter (118) mounted on a cantilevered bearing shaft (116) with a sealed bearing and lubrication system, lubricant pressure balancing means (28), lubricant pressure relief means, and a volume compensating rigid face seal assembly (132) axially movable through an operating range. The face seal assembly comprises two cooperating face seal rings, one ring (144) mounted on the bearing shaft and the other ring (146) mounted in the cutter; a first energizer (148) for the seal ring mounted on the bearing shaft, having a stiffness K1; and a second energizer (150) for the seal ring mounted in the cutter, having a stiffness K2. In order to minimise the variation in the sealing face force as the assembly moves through its operating range, the stiffness K2 is less than half, and preferably less than .2, of the stiffness K1. <IMAGE></p> |
