Rotary drill bits
Number of patents in Portfolio can not be more than 2000
United States of America Patent
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-
Sep 14, 1993
Grant Date -
N/A
app pub date -
Oct 31, 1991
filing date -
Oct 31, 1991
priority date (Note) -
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status (Latency Note)
Importance
Abstract
A rotary drill bit for drilling holes in subsurface formations comprises a bit body having a shank for connection to a drill string, a plurality of preform primary cutting elements mounted on the bit body and defining a primary cutting profile having a downwardly convex nose portion. There are associated with at least certain of the primary cutting elements respective secondary elements which are spaced inwardly of the primary profile. The distance of the secondary elements from the primary profile, when measured in a direction perpendicular to said profile, is generally greater for secondary elements nearer the nose portion than it is for secondary elements further away from the nose portion, and is preferably such that the vertical distance of the secondary elements from the profile is substantially constant.
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