Twist Drill With Negative Axial Rake Transition Between The Lip And The Secondary Cutting Edge

• Main Author: GEORGE STEPHEN MICHAEL
• Format: Patent
• Language: English
• Published: 16.12.2010
• Subjects: BORING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GRINDING; MACHINE TOOLS; MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; METAL-WORKING NOT OTHERWISE PROVIDED FOR; PERFORMING OPERATIONS; POLISHING; TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TRANSPORTING; TURNING

A drill for making a hole within a workpiece has a body extending along a longitudinal axis, at least one flute extending along the body, and a drill point extending from the end of the body. The drill point has a periphery and is comprised of a chisel edge, a primary cutting edge extending inwardly from the periphery, a secondary cutting edge extending outwardly from the chisel edge, and a tertiary cutting edge connecting the primary cutting edge with the secondary cutting edge, wherein the tertiary cutting edge has a negative axial rake angle. A method for producing such a drill point is also disclosed wherein in one grinding pass a gash forms the axial rake angle of the secondary cutting edge, and in a separate grinding pass a portion of the secondary cutting edge is removed to produce a tertiary cutting edge having an axial rake angle that is negative.