Smith, Gambrell & Russell, LLP
Drill
A drill includes a pair of main cutting edges extending from a distal portion of the drill to a position close to a proximal end of the drill to entirely define a two-edge configuration, and a pair of auxiliary cutting edges extending between positions at the distal and proximal sides of a maximum diameter position to partly define a four-edge configuration. A ridgeline of each auxiliary cutting edge is located within an angle smaller than 90° from a ridgeline of the corresponding main cutting edge toward the rear in a rotation direction of the drill. The point angle of the auxiliary cutting edges increases at a higher rate than the point angle of the main cutting edges in a predetermined range from the maximum diameter position toward a distal end of the drill.
Makotoloy Co., Ltd. Fuji Jukogyo Kabushiki Kaisha
B B Y Y Y B B B B
B23B B23B Y10T Y10T Y10T B23B B23B B23B B23B
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Hirofumi Manabu Hideharu Eiji Tatsuo Junji
Higashiwaki Saito Takahashi Hashimoto Nakahata Tsuchiya