Insert for Drill, Drill and Method of Cutting Work Material

An insert for a drill, comprising:

• an insert main body with a top surface and a slide surface;
• wherein the insert main body comprises
• a cutting edge on an intersection part of the top surface and the side surface which comprises a bent portion projected outward when viewed from the top surface, and
• a breaking groove on the top surface which comprises a concave shape along the cutting edge, and
• wherein a width of the breaking groove is maximum at a position corresponding to the bent potion.

An insert for a drill, comprising:

• an insert main body with a top surface and a side surface;
• wherein the insert main body comprises
• a cutting edge on an intersection part of the top surface and the side surface which comprises a bent portion projected outward when viewed from the top surface, and
• a breaking groove on the top surface which comprises a concave shape along the cutting edge,
• wherein the breaking groove comprises a rise face part inclined higher as a distance from the cutting edge increases, and
• wherein a rise angle of the rise face part is minimum at a position corresponding to the bent portion.

An insert for a drill, comprising:

• an insert main body with a top surface and a side surface;
• wherein the insert main body comprises
• a cutting edge on an intersection part of the top surface and the side surface which comprises a bent portion projected outward when viewed from the top surface,
• a breaking groove on the top surface which comprises a concave shape along the cutting edge,
• wherein the breaking groove comprises a rake face part inclined higher as a distance from the cutting edge decreases, and
• wherein a rake angle of the rake face part is minimum at a position corresponding to the bent portion.