| 摘要 |
A bearing (7), for use in a borehole, through which well-flushing medium may be passed for cooling purposes comprises two adjacent bearing surfaces formed by shaped bodies (11, 12) each having a bearing layer (13, 14) provided thereon. The bearing layer (13, 14) comprises diamond particles embedded in a bearing layer material which may comprise a binding metal such as cobalt, nickel or brass. The bearing layer may be formed simultaneously with the formation of the shaped body by a sintering process for tungsten carbide and a binding metal therefor, or separately and subsequently secured to the shaped body. Both radial (7, 8) and thrust (9, 10) bearings may be so formed and incorporated in a bearing block comprising two tubular shells (1, 2) for the direct drive of a deep-drilling bit. Passages (Figs. 9, 10) may be provided in the bearing layer to control the amount of flushing medium passed through the bearings. The bearings disclosed withstand high static and dynamic loads and have good wear characteristics. <IMAGE> |
