Insert, cutting tool, and method for cutting workpiece using the cutting tool

A cutting insert, comprising:

• an upper surface;
• a lower surface positioned at a side opposite to the upper surface;
• a lateral surface connected tothat the upper surface and the lower surface;
• and
• a cutting edge positioned at an intersection of the lateral surface and the upper surface;
• wherein the upper surface comprises
• a corner portion positioned at a boundary between the upper surface and the lateral surface, the corner portion having a shape of a curved line that is outwardly convex in a plan view,
• a side portion connected to the corner portion and forming the cutting edge together with the corner portion,
• a rake face that extends along the side portion and the corner portion and extends downward with increasing distance from the side portion and the corner portion,
• a first rising face that is separated from the cutting edge with the rake face disposed therebetween and extends upward with increasing distance from the rake face, and
• a second rising face that is connected to an upper portion of the first rising face and extends upward with increasing distance from the first rising face,
• wherein the first rising face comprises
• a first region that extends along the corner portion, and
• a second region that extends along the side portion,
• wherein the second rising face comprises
• a third region that extends along the corner portion, and
• a fourth region that extends along the side portion,
• wherein an inclination angle of the first region is greater than an inclination angle of the third region in a sectional view taken along a bisector of the corner portion, wherein an inclination angle of the second region is greater than an inclination angle of the fourth region in a sectional view taken in a direction orthogonal to the side portion, wherein an entirety of a first boundary, which is a boundary between the first region and the third region, is positioned above the corner portion, and wherein a second boundary, which is a boundary between the second region and the fourth region, includes a portion positioned below the side portion.