Soft formation drill bit
AssigneeSmith International, Inc.
InventorsLloyd L. Garner, Charles Richard Harris
Life of this patent
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Abstract
A rock bit with rotary cone cutter means having hardened insert teeth utilizing fewer than the normal number of teeth or of cutters used for a given gage hole wherein the cone cutter body is of greater diameter and for approximately the same axial length, of a greater wall thickness and to accommodate a greater insert tooth depth or grip length and permit a proportional increase in extension of the insert from the cutter body to provide greater penetration with fewer insert teeth in contact at a given time, and also providing for increased journal bearing area to increase the life of the extended insert cutters.
Claims10
A drill bit for drilling holes in soft formations such as limestones, shales or the like, comprising:
- a bit body of given diameter adapted for rotation about an axis within a cylindrical space and having an under side comprising a dome,
- no more than a pair of journal leg means extending downwardly from said body and having journal means extending downwardly and inwardly within said cylindrical space from the lower end portions of the journal legs beneath said dome,
- rotary cone cutter body means on said journal means, the approximate slant height line of the surface of the rotary cone cutter body means intermediate the base and apex of the cone where the cutter means is nearest said axis of the bit, is approximately parallel to said axis,
- hardened insert means imbedded in and extending from said rotary cone cutter body means,
- said insert means being disposed about said rotary cone cutter body means,
- and said insert means being of such length that, when the rotary cone cutter body means is in drilling position, at least a portion of said insert means extends outwardly from said surface of the rotary cone cutter body means to intersect the axis of rotation of the bit body while the material of the cone cutter body per se is spaced laterally from said axis.
Dependencies are inferred from the claim text.