| 摘要 |
<p>A rolling cutter is rotatably mounted on a cantilevered bearing shaft by a radical bearing and an axial bearing. The axia bearing comprises a relatively flat multi-segmented thrust bearing surface having at least two segments of differing metallic compsns. One segment has a compsn. having low coefft. of friction at low temps. and the other segment has a compsn. having a low coefft. of friction at high temps. Used as a thrust face bearing structure for rolling cutter drill bit, esp. high offset, high drag bit. The thrust bearing structure has alternating segments of different metallic bearing materials selected for low temp. and high temp. operability.The structure has high hardness and low coefft. of friction across a broad range of operating temps.</p> |
