Mitsubishi Materials Corporation

Toyota Motor Hokkaido, Inc.

Kensuke Kohno

Yoshio Kobayashi

Naoki Yoshizumi

Toru Yamazaki

Hideyuki Fujiwara

You Tanaka

This broach includes a broach body having a shaft shape and a cutting edge section in which cutting edges protrude and are arranged in a longitudinal direction on an outer circumference of the broach body. The cutting edge section includes, in the order from a front side of the broach body, an circumference cutting section in which an outer diameter of each of the cutting edges sequentially increases rearward, and a tooth thickness cutting section in which a thickness of each of the cutting edges sequentially increases from the cutting edges at a rear end of the circumference cutting section toward the rear side. At least a rear end portion of the circumference cutting section is a high-feed cutting section in which the cutting depth per cutting edge is set in a range of 0.15 mm or more and 0.30 mm or less.

Broach

A plurality of cutting edges that are arranged on an outer circumference of a shaft-shaped broach body are provided with a spline teeth group, which contains a plurality of spline teeththat groove a prepared hole of a work material, and a round teeth group, which is disposed in a different position from the spline teeth group along an axis direction and contains a plurality of round teeth that machine an inner circumference of the prepared hole. At least one gullet is formed to extend along the outer circumference of the broach body in a circumferential direction around the axis between the round teeth that are adjacent to one another in the axis direction in the round teeth group. The gullet extends toward the axis direction, gradually twisting toward the circumferential direction. The spline teeth group and the round teeth group are formed integrally on the outer circumference of the broach body.

This helical broach forms a twisted groove at the inner circumference of a machined hole of a workpiece by a plurality of cutting teeth, the plurality of cutting teeth include a plurality of circumference cutting teeth which are arranged on the tip-end side of the broach body, and include a plurality of tooth thickness cutting teeth which are arranged on the rear-end side of the broach body. The plurality of tooth thickness cutting teeth include cutting edges and guiding edges, respectively. The tooth thickness cutting tooth positioned closest to the rear-end side of the broach body is provided with the guiding edge instead of the cutting edge at the intersecting ridge part between a rake face and a lateral surface facing one wall surface of both groove wall surfaces of the twisted groove of the workpiece.

Growing community of inventors

Akashi, Japan

Kensuke Kohno