Anti-tracking feature for rock bits

Abstract

The harmful effects of tracking are reduced for a drill bit having roller cones with at least one of the outermost rows of active teeth containing one or more teeth having a height that does not extend to the height of at least one of the outermost rows on another roller cone on the bit. The crest on this tooth may have a length in a circumferential direction that is wider than an overall width of the tooth in the outer to inner direction. The invention may be used on any cutter row, not just the outermost row. The design may be used on a different roller cone or row, or more than one cutter row. The anti-tracking feature may be located between the leading and trailing edges of the tooth on one or more roller cones.

Description

[0001]This application claims priority to U.S. Provisional Pat. App. No. 61 / 046,508, filed on Apr. 21, 2008, and i s incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Technical Field[0003]The present invention relates in general to drill bits and, in particular, to an improved system, method, and apparatus for reducing the harmful effects of tracking with drill bits.[0004]2. Description of the Related Art[0005]A roller cone earth-boring drill bit has a number of cones, typically three, each of which is rotatably mounted to a bearing pin. Each cone rotates about its axis when the bit body rotates around the bit axis. The cones have cutting elements, often in rows, which may be teeth integrally formed in the cone metal, or tungsten carbide inserts pressed into mating holes in the cone metal.[0006]Each cone has an outermost or heel row near a gage surface of the cone and one or more inner rows. One or more of the cones have cutting elements located ne...

AI Technical Summary

Benefits of technology

[0011]The cutter design removes the peak of the uncut bottom left by the other roller cones, significantly removing the depth of the pocket and allowing the other roller cones to continue to cut with their crests rather than with the sides of their active teeth or with their cones. Tracking is reduced regardless of the tooth count in the other rows or weight on bit. The invention may be used on any cutter row that shares a common bit diameter and not just the outermost row. Moreover, the invention may be used on a different roller cone or row, or more than one cutter row that shares a common bit diameter.

Problems solved by technology

These ridges are detrimental because they grow in height until they contact the supporting metal of the cone.

This lowers the unit load on the cutting elements and causes undesirable erosion and wear.

While workable, a wider pitch means fewer cutting elements and less durability.

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