Cutting insert
The cutting edge has: a corner cutting edge; a flat cutting edge continuous to a first end portion of the corner cutting edge; and a main cutting edge continuous to a second end portion of the corner cutting edge opposite to the first end portion of the corner cutting edge. The rake face has: a first rising surface portion; and a first rake face portion continuous to the first rising surface portion and located opposite to the corner cutting edge when viewed from the first rising surface portion. When viewed in a direction perpendicular to the reference surface, the first boundary includes a first line segment extending, from one of the flat cutting edge and the corner cutting edge, in a direction crossing a straight line extending along the main cutting edge.
1. A cutting insert comprising:
a first surface;
a second surface located opposite to the first surface; and
a side surface continuous to both of the first surface and the second surface,
a ridgeline between the first surface and the side surface including a cutting edge,
the first surface including a rake face and a reference surface, the rake face being continuous to the cutting edge, the reference surface being located opposite to the cutting edge relative to the rake face, the reference surface having a flat shape,
the cutting edge having a corner cutting edge, a flat cutting edge, and a main cutting edge, the flat cutting edge being continuous to a first end portion of the corner cutting edge, the main cutting edge being continuous to a second end portion of the corner cutting edge opposite to the first end portion of the corner cutting edge,
the rake face having a first rising surface portion and a first rake face portion, the first rake face portion being continuous to the first rising surface portion, the first rake face portion being located opposite to the corner cutting edge when viewed from the first rising surface portion,
in a cross section parallel to the flat cutting edge and perpendicular to the reference surface, a first boundary between the first rising surface portion and the first rake face portion being an inflection point,
when viewed in a direction facing the reference surface, the first boundary including a first line segment extending, from one of the flat cutting edge and the corner cutting edge, in a direction crossing a straight line extending along the main cutting edge, and
when the rake face is directed upward, the flat cutting edge is located on an upper side relative to the corner cutting edge in a direction perpendicular to the reference surface.
2. The cutting insert according to claim 1 , wherein when viewed in the direction facing the reference surface, the first boundary includes a second line segment continuous to the first line segment and extending in a direction inclined relative to the first line segment.
3. The cutting insert according to claim 2 , wherein when viewed in the direction facing the reference surface, in a direction parallel to the flat cutting edge, an interval between the main cutting edge and a position at which the first line segment is continuous to one of the flat cutting edge and the corner cutting edge is larger than an interval between the main cutting edge and a position at which the first line segment is continuous to the second line segment.
4. The cutting insert according to claim 2 , wherein when viewed in the direction facing the reference surface, an angle between the second line segment and a straight line parallel to the flat cutting edge is more than or equal to 80° and less than or equal to 90°.
5. The cutting insert according to claim 2 , wherein
the rake face has a second rising surface portion and a second rake face portion, the second rake face portion being continuous to the second rising surface portion, the second rake face portion being located opposite to the corner cutting edge when viewed from the second rising surface portion,
in a cross section parallel to the main cutting edge and perpendicular to the reference surface, a second boundary between the second rising surface portion and the second rake face portion is an inflection point,
when viewed in the direction facing the reference surface, the second boundary includes a third line segment continuous to the second line segment and extending in a direction inclined relative to the second line segment.
6. The cutting insert according to claim 5 , wherein the third line segment is continuous to the main cutting edge.
7. The cutting insert according to claim 1 , wherein when viewed in the direction facing the reference surface, an angle between the first line segment and a straight line extending along the flat cutting edge is more than or equal to 20° and less than or equal to 80°.
8. The cutting insert according to claim 1 , wherein the first boundary is continuous to the main cutting edge.
9. The cutting insert according to claim 1 , wherein the first boundary is continuous to the corner cutting edge.