Importance

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Abstract

A mounting for cutter wheels on rotary rock drill bits includes a spindle with two annular axial load bearing surfaces, one of which interfaces in a rotational relationship with a cylindrical segmented bushing affixed to the inside surface of a cavity in the cutter wheel and the other of which interfaces through a top hat bushing flange in a rotational relationship with an annular end bearing surface in the cavity of the cutting wheel. A compressive silver coating on the cylindrical bushing before it is split, leaving uncoated edges for precise registration and bit onto a cylindrical race surface machined into the spindle, provides lubrication in addition to compressing under load to distribute axial loading forces from the cutter wheel in proportion to the two axial load bearing surfaces on the spindle. A small, precise, initial clearance between the annular end bearing surface in the cavity of the cutter wheel and the distal axial load bearing surface on the spindle, which clearance disappears upon initial wear-in and seating, also provides proportional axial load distribution to the two axial load bearing surfaces on the spindle. A slanted seal groove in the cutter wheel allows positioning the cylindrical bushing close to the proximal end surface while protecting the seal from a worn proximal end surface.

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First Claim