Cutting blade and method for manufacturing cutting blade

Abstract

A cutting blade (10) is provided with: a plate-shaped base material (20); a coarse-grain film (31) comprising particles having an average particle diameter of 0.5 [mu] m or more; and a fine particle film (32) comprising particles having an average particle diameter of less than 0.5 [mu] m. Furthermore, the base material (20) has a cutting edge (21) and a cutting edge part (22), the cutting edge (21) is at least a part of the outer edge, and the thickness of the cutting edge part (22) becomes smaller when the cutting edge part (22) is closer to the cutting edge (21). The coarse grain film (31) covers the surface of the cutting blade part (22) and the blade tip (21), and the fine grain film (32) covers the surface of the coarse grain film (31) on the blade tip (21).

Description

Technical Field

[0001] The present disclosure relates to a cutting tool and a method for manufacturing the cutting tool. Background Art

[0002] A cutting tool having a quadrangular plate-shaped base material is disclosed in Patent Document 1. One side of the outer edge of the base material forms a cutting edge. In other words, the base material has a cutting edge portion that becomes thinner as it approaches the cutting edge.

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-185648

[0004] For the base material of the cutting tool described in Patent Document 1, in order to suppress the consumption of the base material, a coating layer may be provided. For example, the surface of the base material is covered with a coarse-grained film composed of particles having a large average particle diameter. In this case, the outer surface of the coarse-grained film has irregularities corresponding to the average particle diameter. Therefore, it is difficult to make the cutting edge of the cutting tool sharp. Summary of the Invention

[0005] In order to solve the above problems, one aspect of the present disclosure provides a cutting tool including: a plate-shaped base material; a coarse-grained film composed of particles having an average particle diameter of 0.5 μm or more; and a fine-grained film composed of particles having an average particle diameter of less than 0.5 μm, the base material having a cutting edge and a cutting edge portion, the cutting edge being at least a part of the outer edge, and the thickness of the cutting edge portion becoming smaller as it approaches the cutting edge, the coarse-grained film covering the surface of the cutting edge portion and the cutting edge, and the fine-grained film being on the cutting edge and covering the surface of the coarse-grained film.

[0006] In addition, one aspect of the present disclosure provides a method for manufacturing a cutting tool, including: a base material preparation step of preparing a base material that is plate-shaped and has a cutting edge and a cutting edge portion, the cutting edge being at least a part of the outer edge, and the thickness of the cutting edge portion becoming smaller as it approaches the cutting edge; a first film formation step of forming a coarse-grained film on the cutting edge and the surface of the cutting edge portion after the base material preparation step, the coarse-grained film being composed of particles having an average particle diameter of 0.5 μm or more; a second film formation step of forming a fine-grained film on the cutting edge and the surface of the cutting edge portion after the first film formation step, the fine-grained film being composed of particles having an average particle diameter of less than 0.5 μm; and a cutting edge processing step of etching the fine-grained film on the cutting edge and the surface of the cutting edge portion after the second film formation step so that at least the fine-grained film remains on the cutting edge.

[0007] According to the above structure, since the fine-grained film exists on the cutting edge, it is easier to make the shape sharp than in the case where the cutting edge is only covered with the coarse-grained film.

[0008] The front end shape of the cutting tool can be made sharp. Description of the Drawings

[0009] Figure 1 is a perspective view of the cutting tool.

[0010] Figure 2 is a front view of the cutting tool.

[0011] Figure 3 is along Figure 2 an enlarged cross-sectional view of the cutting tool taken along line 3-3 in

[0012] Figure 4 is an enlarged cross-sectional view near the tip of the cutting tool.

[0013] Figure 5 is an explanatory diagram showing the manufacturing method of the cutting tool.

[0014] Figure 6 is an explanatory diagram showing the first film-forming process.

[0015] Figure 7 is an explanatory diagram showing the tip machining process.

[0016] Figure 8 is an enlarged cross-sectional view of a modified example of the cutting tool. Detailed Description of the Invention

[0017]

[0018] Hereinafter, a preferred embodiment of a cutting tool 10 and a method for manufacturing the cutting tool 10 will be described with reference to the drawings. In addition, there are cases where the drawings are enlarged to make the structural elements easier to understand. There are cases where the dimensional ratios of the structural elements are different from the actual dimensional ratios or from the dimensional ratios in other drawings.

[0019] (Regarding the Cutting Tool)

[0020] As Figure 1 shown, the cutting tool 10 includes a substrate 20. The substrate 20 is in a plate shape. As Figure 2 shown, the substrate 20 includes a cutting edge portion 22, a tip 21, and a flank portion 23. In addition, the surface having the largest area among the surfaces of the substrate 20 is defined as the main surface 25. In the present embodiment, the surface having the largest area of the flank portion 23 is the main surface 25. When the substrate 20 is viewed in a direction orthogonal to the main surface 25, the substrate 20 is rectangular. In addition, the material of the substrate 20 is cemented carbide. Cemented carbide is an alloy obtained by sintering powders of hard metal carbides. For example, cemented carbide is an alloy obtained by mixing tungsten carbide and cobalt as a binder and sintering them.

[0021] The tip 21 is provided at at least a part of the outer edge of the base material 20. Specifically, when observing the base material 20 in the direction orthogonal to the main surface 25, the tip 21 is provided at one long side among the four sides of the base material 20.

[0022] As Figure 3 shown, the cutting edge portion 22 is a portion that is continuous with the tip 21 and has a smaller thickness as it approaches the tip 21. That is, among the four sides of the base material 20 when observing the base material 20 in the direction orthogonal to the main surface 25, the cutting edge portion 22 extends over the entire long side where the tip 21 is provided. When observing a cross-section at a cross-section orthogonal to the main surface 25 of the base material 20, the cross-sectional shape of the cutting edge portion 22 is a substantially isosceles triangle shape with the tip 21 as the vertex.

[0023] The flank portion 23 is the portion of the base material 20 other than the tip 21 and the cutting edge portion 22. As Figure 2 shown, when observing the flank portion 23 in the direction orthogonal to the main surface 25, it is substantially rectangular. In addition, the thickness of the flank portion 23 in the direction orthogonal to the main surface 25 is substantially the same throughout the region.

[0024] As Figure 1 shown, the cutting tool 10 includes a coating film 30. The coating film 30 covers the tip 21 and the cutting edge portion 22 on the surface of the base material 20. In addition, the coating film 30 covers a part of the flank portion 23 on the side connected to the cutting edge portion 22. The thickness of the coating film 30 in the direction orthogonal to the surface of the base material 20 is substantially constant throughout the region.

[0025] (Regarding the coating film)

[0026] As Figure 3 shown, the coating film 30 includes a coarse particle film 31 and a fine particle film 32. The materials of the coarse particle film 31 and the fine particle film 32 include diamond. Specifically, the coarse particle film 31 and the fine particle film 32 are films formed by closely aggregating diamond particles.

[0027] The coarse particle film 31 covers the tip 21 and the cutting edge portion 22. The coarse particle film 31 is composed of diamond particles with an average particle diameter of 0.5 μm or more. Specifically, the average particle diameter of the diamond particles constituting the coarse particle film 31 is about 1.9 μm. In addition, for example, the average particle diameter is measured as follows. First, an arbitrary portion on the surface of the coarse particle film 31 is photographed by an electron microscope. The photographed range is, for example, a range of 15 μm square. Next, within the range of the photographed image, the outer edges of the respective particles are determined. In addition, the length of the longest line segment drawn from an arbitrary point on the outer edge of the particle to another point is taken as the particle diameter of the particle. Moreover, within the range of this image, the average value of the particle diameters of the respective particles is calculated. This value is taken as the average particle diameter of the particles constituting the coarse particle film 31.

[0028] AsFigure 3 As shown, the fine particle film 32 covers at least the surface of the coarse particle film 31 on the tip 21 of the cutting tool. In addition, "on the tip 21" means the direction opposite to the flank 23 with respect to the tip 21 of the cutting tool. Specifically, as described above, when observing a cross-section at a cross-section orthogonal to the main surface 25 of the base material 20, the cutting edge portion 22 has an isosceles triangle shape with the tip 21 side as the apex angle θ. Moreover, the portion on the virtual line L that bisects the apex angle θ and does not intersect the base material 20 is referred to as "on the tip 21".

[0029] In this embodiment, the fine particle film 32 hardly exists on the surface of the cutting edge portion 22. In other words, the thickness of the fine particle film 32 on the surface of the cutting edge portion 22 is substantially zero. Therefore, the thickness of the fine particle film 32 on the surface of the cutting edge portion 22 is smaller than the thickness of the fine particle film 32 on the tip 21.

[0030] The fine particle film 32 is composed of diamond particles having an average particle diameter of less than 0.5 μm. In addition, the method for measuring the average particle diameter of the particles constituting the fine particle film 32 is the same as the method for measuring the average particle diameter of the particles constituting the coarse particle film 31. However, there are cases where the particles constituting the fine particle film 32 are so small that the particle diameter cannot be measured by the above method. In this case, as long as it is clear from the magnification of the electron microscope or the like that the average particle diameter is less than 0.5 μm, the particles can be regarded as constituting the fine particle film 32 without specifically calculating the average particle diameter.

[0031] As Figure 4 shown, the shape of the diamond particles constituting the coarse particle film 31 is substantially columnar. In addition, the shape of the diamond particles constituting the fine particle film 32 is substantially spherical. Moreover, the difference in the shape of these particles is due to the difference in crystal structure. Specifically, in the diamond particles constituting the coarse particle film 31, the proportion of carbon atoms bonded to each other by sp 3 hybrid orbitals is higher than the proportion of carbon atoms bonded to each other by sp 2 hybrid orbitals. And, in the diamond particles constituting the fine particle film 32, the proportion of carbon atoms bonded to each other by sp 2 hybrid orbitals is higher than the proportion of carbon atoms bonded to each other by sp 3 hybrid orbitals. In addition, for example, the above bonding method of carbon atoms contained in the coating film 30 can be inferred from the measurement results of Raman spectroscopy.

[0032] As described above, on the surface of the cutting edge portion 22, the coarse particle film 31 is not covered by the fine particle film 32 and is exposed to the outside. In the present embodiment, reflecting the shape and the average particle size of the particles, the arithmetic mean roughness of the surface of the coarse particle film 31 is larger than the arithmetic mean roughness of the surface of the fine particle film 32. In addition, the arithmetic mean roughness of the surface of the coating film 30 covering the tool tip 21 and the cutting edge portion 22 is measured by a laser microscope. For example, in any part of the surface of the coating film 30 covering the tool tip 21 and the cutting edge portion 22, a range of 1.25 mm is measured. In addition, the critical value of the surface roughness is 0.25 mm. In addition, the measurement pitch is 0.13 μm.

[0033] (Regarding the manufacturing method of the cutting tool)

[0034] Next, the manufacturing method of the cutting tool 10 will be described.

[0035] As Figure 5 shown, the manufacturing method of the cutting tool 10 includes a base material preparation step S101, a first film formation step S102, a second film formation step S103, and a tool tip machining step S104.

[0036] First, the base material preparation step S101 is performed. In the base material preparation step S101, a base material 20 is prepared. The base material 20 is plate-shaped with a main surface 25 and has a tool tip 21 and a cutting edge portion 22. The tool tip 21 is at least a part of the outer edge, and the thickness of the cutting edge portion 22 becomes smaller as it approaches the tool tip 21. In addition, the details of the shape and the like of the base material 20 are as described above.

[0037] Next, as Figure 5 shown, the first film formation step S102 is performed. In the first film formation step S102, a coarse particle film 31 is formed on at least the tool tip 21 and the surface of the cutting edge portion 22 of the base material 20 prepared in the base material preparation step S101. The coarse particle film 31 is composed of particles having an average particle size of 0.5 μm or more. Specifically, in the first film formation step S102, diamond coating is performed by chemical vapor deposition, a so-called hot wire CVD method.

[0038] More specifically, first, pre-treatment of the base material 20 is performed. In the pre-treatment of the base material 20, the surface of the base material 20 is activated by a chemical solution or the like. Next, a seeding treatment is performed on the surface of the base material 20 that has been activated by the pre-treatment. The seeding treatment is a treatment for seeding diamond particles.

[0039] Next, as Figure 6As shown, diamond coating is performed on the tip 21 and the surface of the cutting edge portion 22 using a film forming apparatus 50. The film forming apparatus 50 includes a chamber 60 into which a reaction gas flows. The chamber 60 has a reaction space 61 for chemical vapor deposition. In addition, the chamber 60 has an inlet 62 for allowing the reaction gas to flow into the reaction space 61. In addition, the chamber 60 has an exhaust port 63 for discharging the reacted gas from the reaction space 61. The film forming apparatus 50 includes a heat source 80 for heating the substrate 20 inside the chamber 60. The heat source 80 is a hot wire. The heat source 80 is inside the chamber 60 and is located on the tip 21 side of the substrate 20.

[0040] In the film forming apparatus 50, while the substrate 20 is held inside the chamber 60, methane and hydrogen are caused to flow in as reaction gases. Then, the heat source 80 is operated for a specified time to bring the substrate 20 to 600 to 800°C. Through prior experiments, the specified time is predetermined as the time that makes the average particle diameter of the particles formed on the tip 21 and the surface of the cutting edge portion 22 become a specified value of 0.5 μm or more. In addition, in this embodiment, the specified value is determined to be 2 μm. As a result, the diamond particles adhering to the surface of the tip 21 and the cutting edge portion 22 grow, and a coarse grain film 31 is formed.

[0041] Next, as Figure 5 shown, a second film forming step S103 is performed. In the second film forming step S103, a fine particle film 32 is formed on the tip 21 and the surface of the cutting edge portion 22 after the coarse grain film 31 is formed by the first film forming step S102. The fine particle film 32 is composed of particles having an average particle diameter of less than 0.5 μm. Specifically, following the first film forming step S102, diamond coating is performed by chemical vapor deposition.

[0042] In the second film forming step S103, in the film forming apparatus 50, while the substrate 20 is held inside the chamber 60, the heat source 80 is operated to bring the substrate 20 to 600 to 800°C. Then, methane and hydrogen are caused to flow in as reaction gases. At this time, methane and hydrogen are caused to flow in for a time that makes the average particle diameter of the particles formed on the tip 21 and the surface of the cutting edge portion 22 become a specified value of less than 0.5 μm. As a result, the fine particle film 32 is formed. In addition, by adjusting the heating temperature of the heat source 80, the temperature of the substrate 20, the pressure inside the chamber 60, the concentration of hydrogen, the concentration of methane, the amount of other additives, etc., the growth mode of the diamond particles, that is, the average particle diameter of the formed particles, can be adjusted.

[0043] Next, as Figure 5As shown, the tip machining process S104 is performed. In the tip machining process S104, the particulate film 32 on the surface of the cutting edge portion 22 is etched so that at least the particulate film 32 remains on the tip 21. Thereby, the particulate film 32 on the tip 21 is sharpened. Specifically, machining is performed by ion etching.

[0044] As Figure 7 shown, in the tip machining process S104, an ion beam 40 is irradiated onto the coating film 30 covering the tip 21 and the cutting edge portion 22. Thereby, the particulate film 32 on the tip 21 is sharpened. In addition, the particulate film 32 on the surface of the cutting edge portion 22 in the particulate film 32 formed by the second film forming process S103 is removed. At this time, machining is performed so that when observing a cross-section in a direction orthogonal to the main surface 25, the angle of the outer surface of the coating film 30 covering the cutting edge portion 22 with the tip of the particulate film 32 covering the tip 21 as the vertex becomes a specified angle. Thereby, the cutting tool 10 is manufactured.

[0045] (Effects of this Embodiment)

[0046] (1) According to the above embodiment, since the particulate film 32 exists on the tip 21, it is easier to make the tip shape of the cutting tool 10 sharp compared to the case where only the coarse grain film 31 covers the tip 21.

[0047] (2) In the above embodiment, the thickness of the particulate film 32 on the surface of the cutting edge portion 22 is substantially zero. In other words, the coarse grain film 31 is not covered by the particulate film 32 on the surface of the cutting edge portion 22 and is exposed to the outside. Since the coarse grain film 31 is exposed in this way, it is possible to suppress wear of the cutting tool 10 from occurring in the portion where the coarse grain film 31 is exposed.

[0048] (3) According to the above embodiment, on the outer surface of the cutting edge portion 22, the coarse grain film 31 is not covered by the particulate film 32 and is exposed to the outside. Since the hardness of the coarse grain film 31 is high, it is not easily worn compared to the particulate film 32. Therefore, it is possible to suppress a change in the shape of the cutting tool 10 due to wear of the coarse grain film 31. In addition, in this embodiment, the arithmetic mean roughness of the outer surface of the coating film 30 covering the cutting edge portion 22 is larger than the arithmetic mean roughness of the outer surface of the coating film 30 covering the tip 21. Thereby, when cutting an object with the cutting tool 10, the coating film 30 of the cutting edge portion 22 is not easily adhered to the object to be cut. Thereby, the object to be cut is easily separated from the cutting tool 10.

[0049] (4) In the above-described embodiment, the materials of the fine particle film 32 and the coarse particle film 31 are diamond. Thus, the coarse particle film 31 and the fine particle film 32 are not easily worn. Therefore, when cutting an object with the cutting tool 10, the accuracy of the roughness of the cut surface and the like is not easily deviated. In addition, since the materials of the fine particle film 32 and the coarse particle film 31 are diamond, they can be easily formed by chemical vapor deposition in the first film forming step S102 and the second film forming step S103.

[0050] (5) According to the above-described embodiment, among the diamond particles constituting the coarse particle film 31, the proportion of carbon atoms bonded to each other by Sp 3 hybrid orbitals is higher than the proportion of carbon atoms bonded to each other by Sp 2 hybrid orbitals. Moreover, among the diamond particles constituting the fine particle film 32, the proportion of carbon atoms bonded to each other by Sp 2 hybrid orbitals is higher than the proportion of carbon atoms bonded to each other by Sp 3 hybrid orbitals. That is, the number of carbon atoms per unit volume of the coarse particle film 31 is larger than the number of carbon atoms per unit volume of the fine particle film 32. Thus, the hardness and wear resistance of the coarse particle film 31 can be made higher than the hardness and wear resistance of the fine particle film 32.

[0051] (6) The shape of the diamond particles constituting the coarse particle film 31 is substantially columnar. In addition, the shape of the diamond particles constituting the fine particle film 32 is substantially spherical. When moving the cutting tool 10 in the direction in which the virtual line L extends to cut an object, if the tip 21 is covered only by the coarse particle film 31, cracks are likely to occur along the boundaries of the columnar particles. Therefore, by covering the tip 21 with the fine particle film 32, the generation of cracks is easily suppressed.

[0052] (7) In the above-described embodiment, by performing etching using the tip machining step S104 after the first film forming step S102 and the second film forming step S103, a structure is realized in which the fine particle film 32 is provided on the tip 21 and the fine particle film 32 is hardly present on the surface of the cutting edge portion 22. Therefore, in the second film forming step S103, it is not necessary to adopt a special film forming step in which diamond particles grow only in a specific portion.

[0053] <Modification Example>

[0054] The above-described embodiment and the following modification examples can be implemented in combination with each other within a technically non-contradictory range.

[0055] · The shape of the base material 20 is not limited to the example of the above-described embodiment. For example, the shape of the base material 20 may be disk-shaped, and in this case, it is sufficient that the tip 21 and the cutting edge portion 22 are provided on at least a part of the outer peripheral edge of the disk-shaped base material 20.

[0056] Alternatively, for example, when the substrate 20 is viewed from a direction orthogonal to the main surface 25, the cutting edge tip 21 may be provided on one of the short sides of the four sides of the rectangular substrate 20.

[0057] Alternatively, for example, when the substrate 20 is viewed from a direction orthogonal to the main surface 25, the cutting edge tip 21 may be provided on two or more of the four sides of the rectangular substrate 20.

[0058] · The material of the substrate 20 is not limited to the examples of the above-described embodiments. For example, it may be steel or ceramic.

[0059] · The shape of the cutting edge tip 21 is not limited to the examples of the above-described embodiments. For example, the shape of the cutting edge tip 21 may also be a so-called serrated knife.

[0060] · The shape of the cutting edge portion 22 is not limited to the examples of the above-described embodiments. For example, when viewed in cross-section in a plane orthogonal to the main surface 25 of the substrate 20, the outer edge shape of the cutting edge portion 22 in the range from the flank portion 23 side to the cutting edge tip 21 is not linear but polygonal. That is, the cutting edge tip 21 may also be in a shape such as a so-called two-stage cutting edge. Alternatively, for example, on the outer surface of the cutting edge portion 22, the surface on the main surface 25 side is in the same plane as the main surface 25 compared to the cutting edge tip 21. That is, when viewed in cross-section in a plane orthogonal to the main surface 25 of the substrate 20, the cross-sectional shape of the cutting edge portion 22 may also be a substantially right-angled triangle shape with the cutting edge tip 21 as the vertex.

[0061] · The shape of the flank portion 23 is not limited to the examples of the above-described embodiments. For example, the thickness of the flank portion 23 in the direction orthogonal to the main surface 25 is not substantially the same throughout the region.

[0062] · The materials of the coarse particle film 31 and the fine particle film 32 may not be diamond. The materials of the coarse particle film 31 and the fine particle film 32 only need to have a hardness higher than that of the substrate 20. That is, the materials of the coarse particle film 31 and the fine particle film 32 only need to be materials that can harden the surface of the substrate 20.

[0063] · The coarse particle film 31 and the fine particle film 32 only need to cover at least the cutting edge tip 21 and the cutting edge portion 22. For example, they may also cover the entire main surface 25 of the substrate 20.

[0064] · The fine particle film 32 may also be present on the surface of the cutting edge portion 22. In this case, the fine particle film 32 may also partially cover the coarse particle film 31, as Figure 8 shown, and may also cover substantially the entire region of the coarse particle film 31.

[0065] · When the fine particle film 32 covers the coarse particle film 31 on the surface of the cutting edge portion 22, as Figure 8As shown, it is preferable that the thickness TB of the fine particle film 32 on the cutting edge portion 22 is smaller than the thickness TE of the fine particle film 32 on the tool tip 21. In addition, the thickness TB of the fine particle film 32 on the cutting edge portion 22 is defined as the dimension of the fine particle film 32 in the direction perpendicular to the outer surface of the cutting edge portion 22. Further, the thickness TE of the fine particle film 32 on the tool tip 21 is defined as the dimension of the fine particle film 32 overlapping on the line segment assuming a line segment connecting the tool tip 21 and the front end of the fine particle film 32 covering the tool tip 21. In addition, by controlling the irradiation time of the ion beam 40 in the tool tip machining step S104, the thickness TB of the fine particle film 32 on the cutting edge portion 22 and the thickness TE of the fine particle film 32 on the tool tip 21 can be adjusted to arbitrary thicknesses respectively.

[0066] In Figure 8 In the example shown, since the thickness TB of the fine particle film 32 on the cutting edge portion 22 is thin, even if the fine particle film 32 wears, the change in the overall shape of the cutting tool 10 can be suppressed to a minimum. Moreover, if the coarse particle film 31 is exposed as a result of the wear of the fine particle film 32, further wear of the cutting tool 10 can be suppressed.

[0067] · It is also possible that the proportion of the carbon atoms of diamond contained in the fine particle film 32 bonded to each other by Sp 2 hybrid orbitals is lower than the proportion bonded to each other by Sp 3 hybrid orbitals. In addition, it is also possible that the proportion of the carbon atoms of diamond contained in the coarse particle film 31 bonded to each other by Sp 3 hybrid orbitals is lower than the proportion bonded to each other by Sp 2 hybrid orbitals. Even if each particle constituting the coarse particle film 31 and the fine particle film 32 does not have the above crystal structure, the effects described in (1) can be obtained.

[0068] · The arithmetic mean roughness of the surface of the exposed coarse particle film 31 may also be equal to or less than the arithmetic mean roughness of the surface of the fine particle film 32. As long as the hardness of the coarse particle film 31 is greater than the hardness of the fine particle film 32, the effects described in (1) can be obtained.

[0069] · In the above-described embodiment of the manufacturing method, in addition to methane and hydrogen, gases such as argon and acetone may also be introduced. For example, in the second film forming step S103, the fine particle film 32 may be formed by adjusting the argon concentration and the acetone concentration.

[0070] · In the above-described embodiment of the manufacturing method, the coarse particle film 31 and the fine particle film 32 may also be formed by methods other than chemical vapor deposition. For example, the surfaces of the tool tip 21 and the cutting edge portion 22 may be diamond-coated using a high temperature and high pressure synthesis method, a microwave plasma CVD method, an electron impact CVD method, a DC plasma method, an arc discharge plasma CVD method, a plasma jet CVD method, a combustion flame method, etc.

[0071] In addition, the film-forming method of the coarse-grained film 31 used in the first film-forming step S102 and the film-forming method of the fine-grained film 32 used in the second film-forming step S103 may also be different. For example, it may be that in the first film-forming step S102, the coarse-grained film 31 is formed on the tip 21 and the cutting edge portion 22 by chemical vapor deposition. Next, in the second film-forming step S103, generation of diamond fine particles may be repeated by the microwave plasma CVD method, whereby the fine-grained film 32 is formed.

[0072] In the tip machining step S104, it is sufficient that the fine-grained film 32 on the surface of the tip 21 and the cutting edge portion 22 is etched so that the fine-grained film 32 remains at least on the tip 21. After the tip machining step S104, the coating film 30 on the tip 21 may not be sharpened.

[0073] <Supplementary Note>

[0074] The following describes the technical ideas derived from the above-described embodiments and modification examples.

[0075] [1] A cutting tool, comprising:

[0076] A plate-shaped base material;

[0077] A coarse-grained film composed of particles having an average particle diameter of 0.5 μm or more; and

[0078] A fine-grained film composed of particles having an average particle diameter of less than 0.5 μm,

[0079] The base material has a tip and a cutting edge portion, the tip is at least a part of the outer edge, and in the cutting edge portion, the thickness becomes smaller as it approaches the tip,

[0080] The coarse-grained film covers the surface of the cutting edge portion and the tip,

[0081] The fine-grained film is on the tip and covers the surface of the coarse-grained film.

[0082] [2] The cutting tool according to [1], wherein

[0083] The thickness of the fine-grained film on the surface of the cutting edge portion is smaller than the thickness of the fine-grained film on the tip.

[0084] [3] The cutting tool according to [1] or [2], wherein

[0085] The coarse-grained film is exposed to the outside without being covered by the fine-grained film on the surface of the cutting edge portion.

[0086] [4] The cutting tool according to any one of [1] to [3], wherein,

[0087] The materials of the above-mentioned fine particle film and the above-mentioned coarse particle film contain diamond.

[0088] [5] The cutting tool according to [4], wherein,

[0089] The proportion of the carbon atoms of the diamond contained in the above-mentioned fine particle film bonded by Sp 2 hybrid orbitals is higher than the proportion bonded by Sp 3 hybrid orbitals,

[0090] The proportion of the carbon atoms of the diamond contained in the above-mentioned coarse particle film bonded by Sp 3 hybrid orbitals is higher than the proportion bonded by Sp 2 hybrid orbitals.

[0091] [6] A method for manufacturing a cutting tool, which includes:

[0092] A substrate preparation process for preparing a substrate, which is plate-shaped, has a tool tip and a cutting edge portion, the above-mentioned tool tip is at least a part of the outer edge, and the thickness is smaller the closer to the above-mentioned tool tip in the above-mentioned cutting edge portion;

[0093] A first film-forming process, after the above-mentioned substrate preparation process, forming a coarse particle film on the above-mentioned tool tip and the surface of the above-mentioned cutting edge portion, the above-mentioned coarse particle film is composed of particles with an average particle size of 0.5 μm or more;

[0094] A second film-forming process, after the above-mentioned first film-forming process, forming a fine particle film on the above-mentioned tool tip and the surface of the above-mentioned cutting edge portion, the above-mentioned fine particle film is composed of particles with an average particle size less than 0.5 μm; and

[0095] A tool tip processing process, after the above-mentioned second film-forming process, etching the above-mentioned fine particle film on the above-mentioned tool tip and the surface of the above-mentioned cutting edge portion so that at least the above-mentioned fine particle film remains on the above-mentioned tool tip.

[0096] [7] The method for manufacturing a cutting tool according to [6], wherein,

[0097] The materials of the above-mentioned fine particle film and the above-mentioned coarse particle film are diamond.

[0098] Explanation of reference numerals

[0099] 10... Cutting tool; 20... Substrate; 21... Tool tip; 22... Cutting edge portion; 31... Coarse particle film; 32... Fine particle film; S101... Substrate preparation process; S102... First film-forming process; S103... Second film-forming process; S104... Tool tip processing process.

Claims

1. A cutting tool, wherein, Comprising: A plate-shaped base material; A coarse particle film composed of particles with an average particle size of 0.5 μm or more; and A fine particle film composed of particles with an average particle size less than 0.5 μm, The above-mentioned base material has a tool tip and a cutting edge portion. The above-mentioned tool tip is at least a part of the outer edge, and the thickness becomes smaller as it gets closer to the above-mentioned tool tip in the above-mentioned cutting edge portion, The above-mentioned coarse particle film covers the surface of the above-mentioned cutting edge portion and the above-mentioned tool tip, The above-mentioned fine particle film is on the above-mentioned tool tip and covers the surface of the above-mentioned coarse particle film.

2. The cutting tool according to claim 1, wherein, The thickness of the above-mentioned fine particle film on the surface of the above-mentioned cutting edge portion is smaller than the thickness of the above-mentioned fine particle film on the above-mentioned tool tip.

3. The cutting tool according to claim 1 or 2, wherein, The above-mentioned coarse particle film is exposed to the outside without being covered by the above-mentioned fine particle film on the surface of the above-mentioned cutting edge portion.

4. The cutting tool according to any one of claims 1 to 3, wherein, The materials of the above-mentioned fine particle film and the above-mentioned coarse particle film contain diamond.

5. The cutting tool according to claim 4, wherein, The carbon atoms of the diamond contained in the above-mentioned particulate film are bonded to each other in a proportion of Sp 2 hybrid orbitals higher than the proportion of bonding in Sp 3 hybrid orbitals. The carbon atoms of the diamond contained in the above-mentioned coarse-grained film are bonded to each other in a proportion of Sp 3 hybrid orbitals, which is higher than the proportion of bonding in Sp 2 hybrid orbitals.

6. A manufacturing method of a cutting tool, wherein, Comprising: A base material preparation process for preparing a base material which is plate-shaped and has a tool tip and a cutting edge portion. The above-mentioned tool tip is at least a part of the outer edge, and the thickness becomes smaller as it gets closer to the above-mentioned tool tip in the above-mentioned cutting edge portion; A first film-forming process for forming a coarse particle film on the above-mentioned tool tip and the surface of the above-mentioned cutting edge portion after the above-mentioned base material preparation process. The above-mentioned coarse particle film is composed of particles with an average particle size of 0.5 μm or more; A second film-forming process for forming a fine particle film on the above-mentioned tool tip and the surface of the above-mentioned cutting edge portion after the above-mentioned first film-forming process. The above-mentioned fine particle film is composed of particles with an average particle size less than 0.5 μm; and A tool tip processing process for etching the above-mentioned fine particle film on the above-mentioned tool tip and the surface of the above-mentioned cutting edge portion after the above-mentioned second film-forming process so that at least the above-mentioned fine particle film remains on the above-mentioned tool tip.

7. The manufacturing method of the cutting tool according to claim 6, wherein, The materials of the above-mentioned fine particle film and the above-mentioned coarse particle film are diamond.

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