Cutting insert, cutting tool, and method for manufacturing machined product
A cutting insert in a non-limiting aspect of the present disclosure may include an upper surface having a polygonal shape and including a first side, a lower surface, and a lateral surface. The lateral surface may include a first lateral surface located between the first side and the lower surface. The first lateral surface may include a first region that is flat. The first region may include a first central region, a first upper region and a first lower region. The first upper region may be located closer to the upper surface than the first central region, and may have a larger width than the first central region. The first lower region may be located closer to the lower surface than the first central region, and may be a larger width than the first central region.
1 . A cutting insert, comprising:
an upper surface having a polygonal shape and comprising a first side;
a lower surface located on a side opposite to the upper surface;
a lateral surface located between the upper surface and the lower surface;
an upper cutting edge located on an intersection of the upper surface and the lateral surface; and
a lower cutting edge located on an intersection of the lower surface and the lateral surface,
wherein
an imaginary straight line passing through a center of the upper surface and a center of the lower surface is a central axis,
the lateral surface comprises a first lateral surface located between the first side and the lower surface,
the first lateral surface has a convex shape in a cross section orthogonal to the central axis, and comprises
a first region that is flat, and
a second region that is flat and inclined relative to the first region, the first region comprises
a first central region,
a first upper region which is located closer to the upper surface than the first central region, and which has a larger width in a direction orthogonal to the central axis than the first central region, and
a first lower region which is located closer to the lower surface than the first central region, and which has a larger width in a direction orthogonal to the central axis than the first central region.
2 . The cutting insert according to claim 1 , wherein a maximum value of a width of the first upper region in a direction orthogonal to the central axis is larger than a maximum value of a width of the first lower region in a direction orthogonal to the central axis.
3 . The cutting insert according to claim 1 , wherein
the first lateral surface further comprises a first flank surface located between the first region and the upper surface, and
the first region is located closer to the central axis than the first flank surface in a cross section along the central axis.
4 . The cutting insert according to claim 1 , wherein the first region comes closer to the central axis as coming closer to the upper surface in a cross section along the central axis.
5 . The cutting insert according to claim 1 , wherein
the second region comprises
a second central region,
a second upper region which is located closer to the upper surface than the second central region, and which has a larger width in a direction orthogonal to the central axis than the second central region, and
a second lower region which is located closer to the lower surface than the second central region, and which has a larger width in a direction orthogonal to the central axis than the second central region.
6 . The cutting insert according to claim 5 , wherein a maximum value of a width of the second lower region in a direction orthogonal to the central axis is larger than a maximum value of a width of the second upper region in a direction orthogonal to the central axis.
7 . The cutting insert according to claim 5 , wherein
the first lateral surface further comprises a second flank surface located between the second region and the lower surface, and
the second region is located closer to the central axis than the second flank surface in a cross section along the central axis.
8 . The cutting insert according to claim 5 , wherein the second region comes closer to the central axis as coming closer to the lower surface in a cross section along the central axis.
9 . The cutting insert according to claim 5 , wherein the first upper region is adjacent to the second central region in a direction orthogonal to the central axis.
10 . The cutting insert according to claim 5 , wherein the second lower region is adjacent to the first central region in a direction orthogonal to the central axis.
11 . The cutting insert according to claim 1 , wherein
the first region comprises a first constraining surface configured to be in direct contact with an external holder, and
the second region comprises a second constraining surface configured to be in direct contact with the external holder.
12 . The cutting insert according to claim 1 , wherein
the upper surface further comprises:
a second side adjacent to a first end portion of the first side, and
a third side adjacent to a second end portion of the first side, wherein the second end portion is opposite the first end portion,
the lateral surface further comprises:
a second lateral surface between the second side and the lower surface, and
a third lateral surface between the third side and the lower surface, the third lateral surface being opposite to the second lateral surface,
an imaginary straight line passing through a center of the second lateral surface and a center of the third lateral surface is a lateral axis,
the first region is inclined away from the lateral axis in a direction away from the second lateral surface, and
the second region is inclined away from the lateral axis in a direction away from the third lateral surface.
13 . The cutting insert according to claim 12 , wherein
a boundary between the first region and the second region is distal from the lateral axis at the first lateral surface in the cross section orthogonal to the central axis.
14 . The cutting insert according to claim 1 , wherein
the first region is spaced from the upper surface.
15 . The cutting insert according to claim 14 , wherein
the second region is spaced from the lower surface.
16 . A cutting insert, comprising:
an upper surface having a polygonal shape and comprising a first side;
a lower surface on a side opposite to the upper surface;
a lateral surface between the upper surface and the lower surface;
an upper cutting edge on an intersection of the upper surface and the lateral surface; and
a lower cutting edge at an intersection of the lower surface and the lateral surface,
wherein
an imaginary straight line passing through a center of the upper surface and a center of the lower surface is a central axis,
the lateral surface comprises a first lateral surface located between the first side and the lower surface,
the first lateral surface has a convex shape in a cross section orthogonal to the central axis, and comprises
a first region that is flat, and
a second region that is flat and inclined relative to the first region, the first region comprises:
a first upper region, wherein a width of the first upper region in a direction orthogonal to the central axis increases in a direction toward the upper surface, and
a first lower region is closer to the lower surface than the first upper region, wherein a width of the first lower region in a direction orthogonal to the central axis increases in a direction toward the lower surface.
17 . A cutting tool, comprising:
a holder having a columnar shape extended along a rotation axis from a first end to a second end, the holder comprising a pocket on a side of the first end; and
a cutting insert at the pocket, wherein
the cutting insert comprises:
an upper surface having a polygonal shape and comprising a first side;
a lower surface on a side opposite to the upper surface;
a lateral surface between the upper surface and the lower surface;
an upper cutting edge at an intersection of the upper surface and the lateral surface; and
a lower cutting edge at an intersection of the lower surface and the lateral surface, wherein
an imaginary straight line passing through a center of the upper surface and a center of the lower surface is a central axis,
the lateral surface comprises a first lateral surface located between the first side and the lower surface,
the first lateral surface has a convex shape in a cross section orthogonal to the central axis, and comprises:
a first region that is flat and in direct contact with the pocket, and
a second region that is flat and inclined relative to the first region, the second region being in direct contact with the pocket,
the first region comprises:
a first central region,
a first upper region which is closer to the upper surface than the first central region, and the first upper region has a larger width in a direction orthogonal to the central axis than the first central region, and
a first lower region which is closer to the lower surface than the first central region, and the first lower region has a larger width in a direction orthogonal to the central axis than the first central region.