Bearing means in rotary drill bits
AssigneeSandvik Aktiebolag
InventorErik A. Persson
Life of this patent
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Abstract
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).
Claims10
A rotary drill bit comprising a head, at least one bearing shaft on said head, a roller cutter rotatably mounted on said bearing shaft, said roller cutter carrying cutting means, bearing means for rotatably supporting said roller cutter on said bearing shaft, said bearing means comprising at least one radial friction bearing, said radial friction bearing having a bearing element of wear resistant material, such as sintered hard metal alloy, said bearing element being located at the side of said bearing shaft which faces the bottom of the hole being drilled by the drill bit, said bearing element being provided with a surface which is curved in the latitudinal direction of the bearing element and in the rotational direction of the roller cutter whereby being adapted to cooperate with an inner bearing surface in the roller cutter, characterized in that the curved surface of the bearing element is provided with a groove which extends in the longitudinal direction of the bearing element.
Dependencies are inferred from the claim text.