Nachi - Fujikoshi Corporation

Masayuki Tsuno

Hideki Sato

Shota Miura

Kazuyuki Nakamura

A helical broach which eliminates the need for a fixing means for fixing a workpiece during gear machining is provided. The helical broach includes: a plurality of cutting edges; a spiral flute formed between adjacent cutting edges to extend in a spiral manner with a predetermined helix angle with respect to an axial direction of the helical broach; and a gullet formed between adjacent cutting edges to extend with a predetermined helix angle with respect to a circumferential direction of the helical broach. In the helical broach, the expression: 0.5&#x2264;tan &#x3b2;/tan(&#x3b1;+&#x3b2;)&#x2264;0.7 is satisfied, wherein &#x3b2; is the helix angle of the spiral flute, and (90&#xb0;&#x2212;&#x3b1;) is the helix angle of the gullet with reference to a central axis of the helical broach. An internal gear machining method using the helical broach is also provided.

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Toyama, Japan

Masayuki Tsuno