Patent ID: 7891916

Claim:
An insert for a drill comprising a square flat plate-shaped insert body, the insert body having one square face being a rake face, each of four side ridge portions of the rake face being formed with a cutting edge, the insert for a drill being detachably attached to an indexable insert drill with one of the cutting edges being made to protrude toward the tip of the drill body of an indexable insert drill, each of the cutting edges having a corner cutting edge located at a corner of the rake face, and a major cutting edge and a wiper edge which extend substantially toward one peripheral direction of the rake face from the corner cutting edge, the major cutting edge having a first major cutting edge portion which has a convexly curved shape and extends from the corner cutting edge, and a second major cutting edge portion which is smoothly connected to the first major cutting edge portion and extends linearly, as seen from a direction facing the rake face, and the wiper edge having a straight shape intersecting the second major cutting edge portion at an obtuse angle.