Drill bit for Kevlar laminates
AssigneeHughes Helicopters, Inc.
InventorEddie A. Greene
Life of this patent
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Abstract
An improved drill bit for drilling Kevlar laminates or the like, has a pair of helical edges each terminating in an outer cutting point; a center point; and concavely curved cutting edges extending between the center point and each of the outer cutting point. The cutting edges curve back sharply from the cutting points in a plane transverse to the longitudinal drill bit axis and in a direction opposite to normal rotation of said drill bit so as to draw material served by the cutting points radially inwardly from the edge of a bore. A method is disclosed for modifying a conventional drill point to the novel configuration by grinding on a grinding wheel.
Claims9
An improved drill bit for drilling Kevlar laminates or the like, said drill bit having a pair of helical leading edges each terminating in an outer cutting point;
- a center point;
- and concavely curved cutting edges extending between said center point and each said outer cutting point, said cutting edges curving back sharply from said cutting points as viewed along the longitudinal drill bit axis and in a direction opposite to normal rotation of said drill bit so as to draw material severed by said cutting points radially inwardly from the edge of a bore, said helical leading edges having a reduced rake angle along a leading edge segment adjacent to said cutting points relative to the rake angle of said leading edges along portions removed from said outer cutting points to thereby increase the shearing effect of said edges and minimize lifting of workpiece material by said leading edges.
Dependencies are inferred from the claim text.