Cutting tool
A cutting tool according to an aspect of the present disclosure includes a shank, a joint, and a cutting portion attached through the joint to the shank. The cutting portion includes a core and a surface portion. The surface portion is disposed around a central axis of the cutting portion to cover an outer circumferential surface of the core. The surface portion includes a cutting edge. The cutting edge is disposed on an outer circumferential surface of the surface portion and formed in a helical shape about the central axis. The surface portion is a composite sintered material including a hard phase formed of a plurality of diamond particles and a plurality of cubic boron nitride particles, and a binder phase forming the remainder.
1. A cutting tool comprising:
a shank;
a joint; and
a cutting portion attached through the joint to the shank,
the cutting portion including:
a core; and
a surface portion disposed around a central axis of the cutting portion to cover an outer circumferential surface of the core,
the surface portion including a cutting edge disposed on an outer circumferential surface of the surface portion and formed in a helical shape about the central axis,
the surface portion being a composite sintered material including:
a hard phase formed of a plurality of diamond particles and a plurality of cubic boron nitride particles; and
a binder phase forming a remainder,
wherein the diamond particles arranged adjacent to each other in the composite sintered material are bonded at least partially to each other.
2. The cutting tool according to claim 1 , wherein
a volume ratio of the hard phase to the composite sintered material is in a range from 0.6 to 0.99 inclusive.
3. The cutting tool according to claim 1 , wherein
a volume ratio of the cubic boron nitride particles to the hard phase is in a range from 0.1 to 0.4 inclusive.
4. The cutting tool according to claim 3 , wherein
the volume ratio of the cubic boron nitride particles to the hard phase is in a range from 0.2 to 0.4 inclusive.
5. The cutting tool according to claim 1 , wherein
the diamond particles have a D50 in a range from 0.3 μm to 5 μm inclusive,
the diamond particles have a D90 of 10 μm or less,
the cubic boron nitride particles have a D50 in a range from 0.3 μm to 3 μm inclusive, and
the cubic boron nitride particles have a D90 of 5 μm or less.
6. The cutting tool according to claim 5 , wherein
the diamond particles have a D50 in a range from 0.3 μm to 2 μm inclusive,
the diamond particles have a D90 of 3 μm or less,
the cubic boron nitride particles have a D50 in a range from 0.3 μm to 2 μm inclusive, and
the cubic boron nitride particles have a D90 of 3 μm or less.
7. The cutting tool according to claim 1 , wherein
the binder phase contains cobalt.
8. The cutting tool according to claim 1 , wherein
the core is made of cemented carbide containing cobalt, and
a volume ratio of the cobalt to the cemented carbide is in a range from 0.1 to 0.2 inclusive.
9. The cutting tool according to claim 1 , wherein
the cutting edge has a helix angle in a range from 35° to 75° inclusive.
10. The cutting tool according to claim 9 , wherein
the helix angle is in a range from 45° to 70° inclusive.
11. The cutting tool according to claim 10 , wherein
the helix angle is in a range from 55° to 65° inclusive.
12. The cutting tool according to claim 1 , further comprising an attachment joined to the cutting portion by the joint and removably attached to the shank.