Patent attributes
A superhard sintered body containing cubic boron nitride is bonded to an apical angle part of a tool body having a polygonal shape, and an edge and a chip breaker are formed on the superhard sintered body. A chamfer is formed on the intersection between the upper surface and the side surface of the superhard sintered body, the chip breaker has a protrusion, and an angle θ formed by ridges on the apex of the protrusion or a tangential line at a point bisecting the ridges and a bisector for the apical angle and the ratio of the distance between a first intersection between the two ridges on the apex of the protrusion and an extreme point of the first ridge to the distance between a second intersection between a straight line passing through the first intersection and the extreme point and the outer periphery of the tool body and the first intersection are in prescribed ranges.
