Cemented carbide broach and broaching machine

Abstract

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.

Description

technical field [0001] The present invention relates to push-type or compression-loaded carbide broaches and broaching machines for reaming spline holes, square holes, keyways, round holes, etc. Background technique [0002] A cemented carbide broach has a cutting edge made of cemented carbide material and is used for machining a material having a high hardness of 45 to 65 HRC (Rockwell hardness C scale) after hardening treatment. In this cemented carbide broach, when the control part and the cutting edge are made in one piece, the control part is made of a cemented carbide material with low tolerance for tensile or pulling load, so there is a possibility of the control part breaking question. [0003] Taking this into consideration, JP-A-2002-137118 in its accompanying drawing 1 proposes a combined broach in which the hollow cylindrical cutting edge part is made of hard alloy material and the control part is made of alloy steel. However, under this combination structure, ...

AI Technical Summary

Problems solved by technology

[0005] However, even with this configuration, when the broach has a small diameter, the broach suffers from problems similar to those of the combination broach described above

More specifically, in a small-diameter broach, the shaft diameter of the rear control portion including the small-diameter portion clamped by the broach clamping portion (storage body 24) is small, so there is a possibility that, in the broaching will not be strong enough to overcome compressive loads during milling

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