Reamer
A reamer is rotated about a central axis and has, in a direction along a central axis, a tool front end and a tool rear end that is an end opposite to the tool front end. The reamer includes a blade on a tool front end side. The blade has, on a circumferential surface, a chamfered cutting edge located on the tool front end side, a circumferential cutting edge contiguous to an end of the chamfered cutting edge on a tool rear end side, and a margin that is a surface contiguous to the circumferential cutting edge. The circumferential cutting edge includes a front end portion between a first position and a second position, the first position being an end on a chamfered cutting edge side, the second position having a distance of 1 mm from the first position in a direction of extension of the circumferential cutting edge.
1. A reamer that is rotated about a central axis and has, in a direction along the central axis, a tool front end and a tool rear end that is an end opposite to the tool front end,
the reamer comprising a blade on a tool front end side, wherein
the blade is made of a cemented carbide including metal carbide particles,
the blade has on a circumferential surface:
a chamfered cutting edge located on the tool front end side,
a circumferential cutting edge contiguous to an end of the chamfered cutting edge on a tool rear end side, and
a margin that is a surface contiguous to the circumferential cutting edge,
a flute is formed at the circumferential surface of the blade,
the circumferential cutting edge is formed at a ridgeline of the margin and the flute,
the circumferential cutting edge includes a front end portion between a first position and a second position, the first position being an end on a chamfered cutting edge side, the second position having a distance of 1 mm from the first position in a direction of extension of the circumferential cutting edge, and
as viewed from a direction passing through the central axis and the circumferential cutting edge and being orthogonal to the central axis, the circumferential cutting edge at the front end portion in an as-manufactured state does have a chipping that extends from the circumferential cutting edge to the margin and that is less than 10 μm when measured in a direction orthogonal to the direction of extension of the circumferential cutting edge.
2. The reamer according to claim 1 , wherein the blade is back tapered such that a diameter of a circumcircle of the blade in a cross-section orthogonal to the central axis decreases by not less than 0.05 mm as a distance from the tool front end increases per 100 mm.
3. The reamer according to claim 2 , wherein
the metal carbide particles have a mean particle size of not greater than 0.8 μm.
4. The reamer according to claim 1 , wherein
the metal carbide particles have a mean particle size of not greater than 0.8 μm.