Patent ID: 8931982
Filing Date: 2015-01-13
Classification: B23B,Y10T

Abstract:
1. A throw-away rotating tool comprising: a body having a plurality of erected portions erected around an axis at an interval from each other; and a cutting head made from a material harder than the body and having a projecting coupling portion projected from a rear end, the projecting coupling portion being inserted in a space formed by the erected portions and relatively rotated around the axis to couple the projecting coupling portion and the erected portions together, wherein the throw-away rotating tool includes a plurality of protrusions formed in a protruding shape at a predetermined twist angle as a part of an outer peripheral wall of the projecting coupling portion and sandwiched between inner peripheral walls of the erected portions, and the twist angle and a twist direction of the plurality of protrusions are set in such a way that with relative rotation of the body and the cutting head when coupling the projecting coupling portion and the erected portions together, the plurality of protrusions come into contact with the inner peripheral walls of the erected portions from a rear end side and their contact area gradually increases; wherein the inner peripheral walls are each formed as a set of arcuate curves of the same radius centered about the axis; and the twist direction of the plurality of protrusions is set to the same direction as a twist direction of a ridge line on a side facing a direction of relative rotation between a groove recessed in an outer periphery of the body and the inner peripheral walls, and the twist angle of the plurality of protrusions is set to an angle larger than a twist angle of the ridge line.