Rotary rock bit with infiltrated bearings
AssigneeDresser Industries, Inc.
InventorKenneth O. McDowell
Life of this patent
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Abstract
A rotary rock bit is formed as a rock bit body, a bearing shaft supported by the rock bit body, a rotary cutter adapted to be rotatably mounted on the bearing shaft, and at least one bearing that promotes rotation between the rotary cutter and the bearing shaft. Each bearing includes a bearing element having a steel matrix with steel-free volumes distributed therethrough. The matrix is a hypoeutectoid steel having more than about 0.40 weight percent carbon. An anti-galling alloy resides within the steel-free volumes of the steel matrix. The anti-galling alloy is a silver-copper alloy having a composition of from about 60 weight percent to about 95 weight percent silver, balance copper.
Claims14
A rotary rock bit, comprising:
- a rock bit body;
- a bearing shaft supported by the rock bit body;
- a rotary cutter adapted to be rotatably mounted on the bearing shaft;
- and
- at least one bearing that promotes rotation between the rotary cutter and the bearing shaft, each bearing including a bearing element having
- a steel matrix with steel-free volumes distributed therethrough, the steel matrix having a hypoeutectoid composition with more than about 0.40 weight percent carbon, and
- an anti-galling alloy residing within the steel-free volumes of the steel matrix, the anti-galling alloy comprising a silver-copper alloy consisting essentially of from about 60 weight percent to about 95 weight percent silver, balance copper.
A method for fabricating a rock bit, comprising the steps of:
- preparing a rock bit bearing, the step of preparing a rock bit bearing comprising the steps of
- providing a mixture of powders having a net composition that is a hypoeutectoid steel having more than about 0.40 percent by weight carbon,
- sintering the mixture of powders to produce a porous matrix structure having open-cell porosity therein,
- providing an infiltrant alloy having a composition consisting essentially of from about 60 percent to about 95 percent silver, balance copper, and
- heating the porous matrix structure in contact with the infiltrant alloy so that the infiltrant alloy melts and infiltrates into the open-cell porosity to produce an infiltrated structure, but such that the matrix structure does not melt.
Dependencies are inferred from the claim text.