Insert, drill, and method of manufacturing machined product using the same

An insert, comprising:

• an upper surface comprising:
• a first corner part;
• a second corner part;
• and
• a first side connected to the first corner part and the second corner part;
• a lower surface;
• a side surface located between the upper surface and the lower surface;
• and
• a cutting edge located at the first corner and the first side, and comprising:
• a first cutting edge located at the first corner part;
• a second cutting edge located between the first cutting edge and the second corner part;
• a third cutting edge located between the second cutting edge and the second corner part, having a convex curvilinear shape with a first radius of curvature, and extending downward as going farther from the second cutting edge toward the second corner part;
• a fourth cutting edge located between the third cutting edge and the second corner part, having a convex curvilinear shape with a second radius of curvature, and extending upward as going farther from the third cutting edge in a side view toward the second corner part;
• and
• a fifth cutting edge located between the third cutting edge and the fourth cutting edge, and having a concave curvilinear shape in a side view;
• wherein
• the second radius of curvature is smaller than the first radius of curvature,
• the fifth cutting edge has a third radius of curvature that is larger than the second radius of curvature, and
• the third cutting edge passes through a center of the first side between the first corner part and the second corner part that is subsequent to the first corner part.

An insert, comprising:

• an upper surface comprising:
• a first corner part;
• a second corner part;
• and
• a first side connected to the first corner part and the second corner part;
• a lower surface;
• a side surface located between the upper surface and the lower surface;
• and
• a cutting edge located at the first corner and the first side, and comprising:
• a first cutting edge located at the first corner part;
• a second cutting edge located between the first cutting edge and the second corner part;
• a third cutting edge located between the second cutting edge and the second corner part, having a convex curvilinear shape with a first radius of curvature, and extending downward as going farther from the second cutting edge toward the second corner part;
• a fourth cutting edge located between the third cutting edge and the second corner part, having a convex curvilinear shape with a second radius of curvature, and extending upward as going farther from the third cutting edge in a side view toward the second corner part;
• and
• a fifth cutting edge located between the third cutting edge and the fourth cutting edge, and having a concave curvilinear shape in a side view;
• wherein
• the second radius of curvature is smaller than the first radius of curvature,
• the upper surface further comprises an inclined surface being inclined downward as going farther from the cutting edge towards a center of the upper surface,
• the inclined surface comprises:
• a first inclined surface located along the first cutting edge;
• a second inclined surface located along the second cutting edge, and having a first inclination angle;
• a third inclined surface located along the third cutting edge, and having a second inclination angle;
• a fourth inclined surface located along the fourth cutting edge, and having a third inclination angle;
• and
• each of the second inclination angle and the third inclination angle is larger than the first inclination angle;
• and
• the third cutting edge passes through a center of the first side between the first corner part and the second corner part that is subsequent to the first corner part.