Patent ID: 8485763
Filing Date: 2013-07-16
Classification: B23D,B23F,Y10T

Abstract:
1. A helical broach for roughing comprising a cutting tooth part in which a plurality of spline teeth are arranged side by side in an axial direction, the spline teeth each including cutting teeth which are arranged at a predetermined helix angle, the cutting teeth each having an acute angle portion and an obtuse angle portion on both sides of a cutting edge thereof in a circumferential direction for cutting a work piece, wherein on an obtuse angle portion side of the cutting edge of each of the cutting teeth disposed in the circumferential direction on part of the spline teeth, an inclined portion or a tapered portion for cutting the work piece is formed by gradually increasing a height of the cutting tooth from the obtuse angle portion side toward the acute angle portion side so that the height of the cutting tooth on an acute angle portion side differs from that on the obtuse angle portion side, the part of the spline teeth being spline teeth disposed sequentially from a leading one of the spline teeth, and the cutting teeth of the other part of the spline teeth are each formed in such a way that its height stays constant in the circumferential direction.