Sumitomo Electric Hardmetal Corp.

Sumitomo Electric Industries, Limited

Kawasaki Jukogyo Kabushiki Kaisha

Hisao Oka

Kiichi Meguro

Kazuo Maeda

Yoshiji Sato

Satoshi Suzuki

Junichi Tamura

Tatsuya Shino

A small diameter portion having an outside diameter smaller than a diameter of the drill is formed on a front end side of a body of the drill in which a cutting edge includes at least two portions, that is, a rotation center side cutting edge portion and an outer peripheral side cutting edge portion and point angles of the respective cutting edge portions reducing gradually from the rotation center side cutting edge portion to the outer peripheral side cutting edge portion. The cutting edge with the point angles varied is formed in the small diameter portion. A flat cutting edge having an inclination angle &#x3b2; of 30&#xb0; or less with respect to a line perpendicular to an axis of the drill is provided in a step portion formed between the small diameter portion and a large diameter portion.

Drill

An end mill includes first cutting edges which spiral in a direction defining a positive helix angle and second cutting edges which spiral in a direction defining a negative helix angle, the first cutting edges and the second cutting edges being disposed at positions shifted in a circumferential direction. The first cutting edges and the second cutting edges are each configured to be continuous over an effective cutting edge length. At an axially forward end of the end mill, a first phase angle between one of the first cutting edges and its adjacent second cutting edge located adjacent to the first cutting edges in an opposite direction to a tool rotation direction is set to be different from a second phase angle between the second cutting edge and its adjacent first cutting edge located adjacent to the second cutting edges in the opposite direction to the tool rotation direction.

End mill

Growing community of inventors

Osaka, Japan

Hisao Oka