| 摘要 |
A rotary drill bit comprising at least one roller cutter (12) which is rotatably supported over bearing means (14, 15, 16) and provided with cutting means (13). The bearing means comprises a radial friction bearing (16) with a bearing element (25) of wear resistant material, such as hard metal. In order to improve the surface contact between the bearing element (25) and the inner bearing surface (27) in the roller cutter (12), and in order to remove impurities from the cooperating bearing surfaces a longitudinal groove (30) is provided in the bearing element (25). The fluid primarily supplied for flushing the groove (30) is secondarily used to cool the bearing element (25). |
