TECHNICAL FIELD

The present invention relates to a throwaway insert. The present application claims a priority based on Japanese Patent Application No. 2016-243351 filed on Dec. 15, 2016, the entire content of which is incorporated herein by reference.

BACKGROUND ART

Japanese Patent Laying-Open No. 11-320219 (Patent Literature 1) discloses a throwaway insert including: a base (base material) having a corner portion provided with a recess; and a cutting edge member (hard sintered material) joined to the recess. The cutting edge member includes: an upper surface; a first side surface flush with a side surface of the base; and a second side surface facing a side surface of the recess. This cutting edge member includes: a first ridgeline formed by the upper surface and the first side surface and serving as a cutting edge; and a second ridgeline formed by the upper surface and the second side surface. The first ridgeline crosses the second ridgeline at an acute angle.

CITATION LIST

Patent Literature

PTL 1: Japanese Patent Laying-Open No. 11-320219

SUMMARY OF INVENTION

A throwaway insert according to one embodiment of the present invention includes a base and a cutting edge member. The base has an upper surface, a lower surface, and a plurality of side surfaces that connect the upper surface to the lower surface, the base being provided with a recess at a corner portion at which the upper surface crosses two side surfaces of the plurality of side surfaces. The cutting edge member is joined to the recess. The cutting edge member includes: a rake face; a flank face extending to cross the rake face; a first connecting face; a second connecting face; and a first ridgeline serving as a cutting edge. The first connecting face connects the flank face to one side surface of the two side surfaces and extends to cross the rake face. The second connecting face connects the flank face to the other side surface of the two side surfaces and extends to cross the rake face. The first ridgeline is formed by the rake face and the flank face. The rake face includes: a main surface extending along the upper surface; and a first chamfer provided at an edge tip portion of the cutting edge member, the edge tip portion including an extreme tip portion of the cutting edge member. The cutting edge includes a first cutting edge part constituted of a first ridgeline part formed by the first chamfer and the flank face. In a plan view from the upper surface of the base, the flank face, the first connecting face, and the second connecting face are located external to the base. The first chamfer is inclined relative to the main surface so as to increase a thickness of the cutting edge member as the first chamfer is closer to the main surface.

