- Patent Title: Twist drill with unequal flute spacing and unequal relief angles
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Application No.: US15448427Application Date: 2017-03-02
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Publication No.: US10195675B2Publication Date: 2019-02-05
- Inventor: Stephen Michael George
- Applicant: Kennametal Inc.
- Applicant Address: US PA Latrobe
- Assignee: KENNAMETAL INC.
- Current Assignee: KENNAMETAL INC.
- Current Assignee Address: US PA Latrobe
- Agent Matthew S. Bedsole
- Main IPC: B23B51/02
- IPC: B23B51/02

Abstract:
A twist drill having a shaft with a longitudinal axis, wherein the cutting tool includes a plurality of flutes extending about the longitudinal shaft along a helix angle and a plurality of lands adjacent the flutes. Each land has a cutting edge adjacent a corresponding flute and a margin (i.e. relief surface). A cutting point is adjacent a forward end of the shaft. A first, second and third forward cutting surfaces are adjacent the first, second and third cutting edges, respectively, and extend proximate the cutting point axially rearward for a predetermined length about the longitudinal axis of the shaft. The cutting edges are unequally angularly spaced from each other, and each forward cutting surface has a primary relief angle that are unequal to each other.
Public/Granted literature
- US20180250755A1 TWIST DRILL WITH UNEQUAL FLUTE SPACING AND UNEQUAL RELIEF ANGLES Public/Granted day:2018-09-06
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