US-12617024-B2 - Cutting tool

US12617024B2US 12617024 B2US12617024 B2US 12617024B2US-12617024-B2

Abstract

A cutting tool according to the present disclosure has a rake face, a flank face, and a cutting edge. The cutting edge is located between the rake face and the flank face. The cutting tool includes a substrate composed of a cubic boron nitride sintered material, and an oxide layer that covers the substrate and that constitutes at least part or whole of the rake face, the flank face, and the cutting edge. The oxide layer includes at least one element selected from a group consisting of titanium, aluminum, zirconium, and cobalt. A thickness of the oxide layer is 2 μm or less.

Inventors

Naoki Watanobe
Masashi Harada
Takashi Harada
Satoru Kukino

Assignees

SUMITOMO ELECTRIC HARDMETAL CORP.

Dates

Publication Date: 20260505
Application Date: 20210618
Priority Date: 20200622

Claims (11)

1 . A cutting tool comprising: a rake face; a flank face; and a cutting edge located between the rake face and the flank face, wherein the cutting tool includes a substrate composed of a cubic boron nitride sintered material, and an oxide layer that covers the substrate and that constitutes part or whole of at least one of the rake face, the flank face, and the cutting edge, the oxide layer consists of one or more oxides that include at least one element selected from a group consisting of titanium, aluminum, zirconium and cobalt, a thickness of the oxide layer is 30 nm or more and 300 nm or less, the substrate includes cubic boron nitride grains and a binder in contact with the cubic boron nitride grains, the oxide layer is contiguous to the binder, and the oxide layer includes the same element as an element included in the binder.
2 . The cutting tool according to claim 1 , wherein when a cutting region is defined as a region sandwiched between a first imaginary line and a second imaginary line, a ratio of an area occupied by the oxide layer in the cutting region is 20% or more and 80% or less, the first imaginary line being separated by 200 μm on the rake face from an imaginary ridgeline formed by intersection of a plane obtained by extending the rake face and a plane obtained by extending the flank face, the second imaginary line being separated by 200 μm on the flank face from the imaginary ridgeline.
3 . The cutting tool according to claim 1 , wherein part of the cubic boron nitride grains is exposed from the oxide layer.
4 . The cutting tool according to claim 2 , wherein part of the cubic boron nitride grains is exposed from the oxide layer.
5 . A cutting tool comprising: a rake face; a flank face; and a cutting edge located between the rake face and the flank face, wherein the cutting tool includes a substrate composed of a cubic boron nitride sintered material, and an oxide layer that covers the substrate and that constitutes only part or whole of a surface of at least one of the rake face, the flank face, and the cutting edge, the oxide layer includes at least one element selected from a group consisting of titanium, aluminum, zirconium and cobalt, a thickness of the oxide layer is 2 μm or less, the substrate includes cubic boron nitride grains and a binder in contact with the cubic boron nitride grains, the oxide layer is contiguous to the binder, and the oxide layer includes the same element as an element included in the binder.
6 . The cutting tool according to claim 5 , wherein the thickness of the oxide layer is 30 nm or more and 300 nm or less.
7 . The cutting tool according to claim 5 , wherein when a cutting region is defined as a region sandwiched between a first imaginary line and a second imaginary line, a ratio of an area occupied by the oxide layer in the cutting region is 20% or more and 80% or less, the first imaginary line being separated by 200 μm on the rake face from an imaginary ridgeline formed by intersection of a plane obtained by extending the rake face and a plane obtained by extending the flank face, the second imaginary line being separated by 200 μm on the flank face from the imaginary ridgeline.
8 . The cutting tool according to claim 5 , wherein part of the cubic boron nitride grains is exposed from the oxide layer.
9 . The cutting tool according to claim 6 , wherein when a cutting region is defined as a region sandwiched between a first imaginary line and a second imaginary line, a ratio of an area occupied by the oxide layer in the cutting region is 20% or more and 80% or less, the first imaginary line being separated by 200 μm on the rake face from an imaginary ridgeline formed by intersection of a plane obtained by extending the rake face and a plane obtained by extending the flank face, the second imaginary line being separated by 200 μm on the flank face from the imaginary ridgeline.
10 . The cutting tool according to claim 6 , wherein part of the cubic boron nitride grains is exposed from the oxide layer.
11 . The cutting tool according to claim 7 , wherein part of the cubic boron nitride grains is exposed from the oxide layer.

Description

TECHNICAL FIELD The present disclosure relates to a cutting tool. The present application claims a priority based on International Patent Application No. PCT/JP2020/024453 filed on Jun. 22, 2020, the entire contents of which are hereby incorporated by reference. BACKGROUND ART Japanese Patent Laying-Open No. 2017-159380 (PTL 1) discloses an end mill having a rake face in which a plurality of streaks (recesses) are formed. CITATION LIST Patent Literature PTL 1: Japanese Patent Laying-Open No. 2017-159380 SUMMARY OF INVENTION A cutting tool according to the present disclosure includes a rake face, a flank face, and a cutting edge. The cutting edge is located between the rake face and the flank face. The cutting tool includes a substrate composed of a cubic boron nitride sintered material, and an oxide layer that covers the substrate and that constitutes part or whole of at least one of the rake face, the flank face, and the cutting edge. The oxide layer includes at least one element selected from a group consisting of titanium, aluminum, zirconium, and cobalt. A thickness of the oxide layer is 2 μm or less. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic perspective view showing a configuration of a cutting tool according to a first embodiment. FIG. 2 is a schematic side view showing the configuration of the cutting tool according to the first embodiment. FIG. 3 is a schematic cross sectional view when viewed along a line of FIG. 2. FIG. 4 is an enlarged schematic view of a region IV in FIG. 3. FIG. 5 is a schematic plan view showing a configuration of a cutting region. FIG. 6 is a schematic cross sectional view showing the configuration of the cutting region. FIG. 7 is an enlarged schematic cross sectional view showing a configuration of a first modification of the cutting tool according to the first embodiment. FIG. 8 is an enlarged schematic cross sectional view showing a configuration of a second modification of the cutting tool according to the first embodiment. FIG. 9 is a first schematic cross sectional view showing a configuration of a cutting tool according to a second embodiment. FIG. 10 is a second schematic cross sectional view showing the configuration of the cutting tool according to the second embodiment. FIG. 11 is a partial schematic cross sectional view showing a configuration of a cutting tool according to a third embodiment. FIG. 12 is a partial schematic cross sectional view showing a configuration of a cutting tool according to a fourth embodiment. FIG. 13 is a first schematic cross sectional view showing a configuration of a cutting tool according to a fifth embodiment. FIG. 14 is a second schematic cross sectional view showing the configuration of the cutting tool according to the fifth embodiment. FIG. 15 is a diagram showing a relation between an angle formed by two adjacent straight line portions and a position in a peripheral direction, FIG. 16 is a partial schematic cross sectional view showing the configuration of the cutting tool according to the fifth embodiment. FIG. 17 is a partial schematic cross sectional view showing a configuration of a cutting tool according to a sixth embodiment. FIG. 18 is a partial schematic cross sectional view showing a configuration of a cutting tool according to a seventh embodiment. FIG. 19 is a schematic cross sectional view showing a state in which cutting is performed using the cutting tool according to the fifth embodiment. DETAILED DESCRIPTION Problem to be Solved by the Present Disclosure When cutting a workpiece using a rotary cutting tool, centrifugal force acts on coolant, with the result that it is difficult to keep the coolant in the vicinity of a cutting point while effectively transporting the coolant to the vicinity of the cutting point. In the end mill described in Japanese Patent Laying-Open No. 2017-159380, the coolant is kept in a valley portion of the recess provided in the rake face, thereby improving lubricity. However, when large cutting resistance is exerted on the cutting edge in the end mill, stress is concentrated in the recess, with the result that its life until breakage of the cutting edge may be short. Advantageous Effect of the Present Disclosure According to the present disclosure, the life of a cutting tool breakage of a cutting edge can be extended. Summary of Embodiments of the Present Disclosure First, summary of embodiments of the present disclosure will be described. (1) A cutting tool 100 according to the present disclosure includes a rake face 4, a flank face 3, and a cutting edge 72. Cutting edge 72 is located between rake face 4 and flank face 3. Cutting tool 100 includes a substrate Si composed of a cubic boron nitride sintered material, and an oxide layer 80 that covers substrate 81 and that constitutes part or whole of at least one of rake face 4, flank face 3, and cutting edge 72. Oxide layer 80 includes at least one element selected from a group consisting of titanium, aluminum, zirconium, and co