| 摘要 |
A broach has a main body of a cemented carbide material. On this main body, a front grip portion, a cylindrical portion following the front grip portion and provided with a plurality of guide parts in its outer periphery, a broach cutting edge portion following an end of the cylindrical portion and having a number of cutting edges, and a cylindrical extension following the broach cutting edge portion and having a maximum outer periphery dimension to such an extent that the extension does not interfere with a work are integrally provided. On an end surface of the cylindrical extension, a load receiving shoulder is formed, which leads to a rear grip portion including a small-diameter part and is orthogonal to or inclined with respect to a broach axis. The load receiving shoulder has a sufficient area to bear a cutting load. A broaching machine grips the rear grip portion with its load receiving surface abutting against the load receiving shoulder of the cemented carbide broach. The broach, even when having a small diameter, does not suffer from an insufficient tensile strength of the front grip portion.
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