Cutting insert, cutting tool, and method for manufacturing machined product
A cutting insert may include a first surface, a second surface, a third surface, and a land surface. The first surface may include a first corner and a first side. The land surface may be located between the first surface and the third surface. The land surface may include a first land surface connecting to the first corner, and a second land surface connecting to the first side. A width of the first land surface in a front view as viewed from a side of the first surface may be a first width, the first width at an end portion on a side of the second land surface may be larger than the width at a part connecting to a midportion of the first corner.
1. A cutting insert, comprising:
a first surface having a polygonal shape and comprising a first corner and a first side extended from the first corner;
a second surface located on a side opposite to the first surface;
a third surface located between the first surface and the second surface; and
a land surface located between the first surface and the third surface, wherein
the land surface comprises:
a first land surface connecting to the first corner, and
a second land surface connecting to the first side and abutting the first land surface;
the first land surface comprises:
a midportion, and
a first end portion located at a side of the second land surface;
the first land surface has a first width in a front view of the first surface;
the first width at the first end portion is larger than the first width at the midportion;
the first land surface has a first height in a side view of the first land surface;
the first height at the midportion is larger than the first height at the first end portion;
the second land surface has a second width in the front view of the first surface;
the second land surface comprises a part where the second width becomes smaller going away from the first land surface and a part where the second width is constant, or the second width only becomes smaller going away form the first land surface;
a ridge line where the first surface intersects with the first land surface is a convex curvilinear arc in which a second radius of curvature at the midportion of the first land surface is smaller than a third radius of curvature at the first end portion in the front view of the first surface;
the ridge line where the first surface intersects with the first land surface and the second land surface is without a concave section;
the first surface further comprises a second side extending from the first corner;
the land surface further comprises a third land surface connecting to the second side;
the first land surface further comprises a second end portion located at a side of the third land surface; and
the first width at the second end portion is larger than the first width at the midportion.
2. The cutting insert according to claim 1 , wherein
the first land surface further comprises a part where the first width becomes larger approaching the first end portion from the midportion in the front view of the first surface.
3. The cutting insert according to claim 1 , wherein
a ridge line where the third surface intersects with the first land surface has a circular arc shape in which a first radius of curvature is constant in the front view of the first surface.
4. The cutting insert according to claim 1 , wherein
the third land surface has a third width in the front view of the first surface, and
the third land surface comprises a part where the third width becomes smaller going away from the first land surface.
5. A cutting tool, comprising:
a holder comprising a pocket located on a side of a front end of the holder; and
the cutting insert according to claim 1 , the cutting insert being located in the pocket.
6. A method for manufacturing a machined product, comprising:
rotating a workpiece;
bringing the cutting tool according to claim 5 into contact with the workpiece being rotated; and
moving the cutting tool away from the workpiece.