Cutting tool

Abstract

This cutting tool is provided with a base material and a coating film disposed on the base material, and is characterized in that the coating film includes a first layer on the base material, a second layer on the first layer, and a third layer on the second layer, the first layer is composed of titanium carbonitride, the second layer is composed of aluminum oxide, and the third layer is composed of aluminum oxide. The third layer is composed of titanium carbonitride, and the residual stress X of the first layer, the residual stress Y of the second layer, and the residual stress Z of the third layer satisfy the relationship of formula 1.

Description

Technical Field

[0001] The present disclosure relates to cutting tools. Background Art

[0002] Conventionally, cutting tools having a substrate and a coating disposed on the substrate have been used for cutting (Patent Documents 1 to 6).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-037150

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2020-116645

[0007] Patent Document 3: International Publication No. 2009 / 112116

[0008] Patent Document 4: International Publication No. 2022 / 244241

[0009] Patent Document 5: International Publication No. 2022 / 244242

[0010] Patent Document 6: International Publication No. 2022 / 244243 Summary of the Invention

[0011] The cutting tool of the present disclosure is a cutting tool having a substrate and a coating disposed on the substrate,

[0012] The coating includes a first layer on the substrate, a second layer on the first layer, and a third layer on the second layer,

[0013] The first layer is composed of titanium carbonitride,

[0014] The second layer is composed of alumina,

[0015] The third layer is composed of titanium carbonitride,

[0016] The residual stress X of the first layer, the residual stress Y of the second layer, and the residual stress Z of the third layer satisfy the relationship of Formula 1.

[0017] X < Y < Z Formula 1 Brief Description of the Drawings

[0018] Figure 1 is a schematic cross-sectional view illustrating one embodiment of the cutting tool of the present disclosure.

[0019] Figure 2It is a schematic cross-sectional view of an example of a CVD (Chemical Vapor Deposition) apparatus for manufacturing a cutting tool of the present disclosure. Detailed Description of the Invention

[0020] [Problems to be Solved by the Present Disclosure]

[0021] In recent years, the demand for improving tool life has been increasing. Especially in the light interrupted turning of alloy steel with black skin material, further improvement of tool life is pursued. As important factors for further improving tool life in the light interrupted turning of alloy steel with black skin material, "wear resistance" and "chipping resistance" can be cited. In addition, from the viewpoint of improving wear resistance, in the light interrupted turning of alloy steel with black skin material, a cutting tool is used which is a cutting tool having a substrate and a coating disposed on the substrate, wherein the coating includes a first layer located on the substrate, a second layer located on the first layer, and a third layer located on the second layer, the first layer is composed of titanium carbonitride, the second layer is composed of alumina, and the third layer is composed of titanium carbonitride. However, in such a coating, since the third layer is easily damaged by sandblasting, it is difficult to introduce sufficient residual stress into the first layer, so there is a case where "chipping resistance" is insufficient. In addition, due to minute damages caused by insufficient "chipping resistance", there is a case where wear is likely to occur (that is, there is a case where "wear resistance" is insufficient). Therefore, by having both excellent "wear resistance" and excellent "chipping resistance", especially in the light interrupted turning of alloy steel with black skin material, extension of tool life is also pursued.

[0022] Accordingly, an object of the present disclosure is to provide a cutting tool having a long tool life especially in the light interrupted turning of alloy steel with black skin material.

[0023] [Effects of the Present Disclosure]

[0024] According to the present disclosure, it is possible to provide a cutting tool having a long tool life especially in the light interrupted turning of alloy steel with black skin material.

[0025] [Description of Embodiments of the Present Disclosure]

[0026] First, embodiments of the present disclosure will be listed and described.

[0027] (1) The cutting tool of the present disclosure is a cutting tool having a substrate and a coating disposed on the substrate, wherein,

[0028] the coating includes a first layer located on the substrate, a second layer located on the first layer, and a third layer located on the second layer,

[0029] The first layer is composed of titanium carbonitride,

[0030] The second layer is composed of aluminum oxide,

[0031] The third layer is composed of titanium carbonitride,

[0032] The residual stress X of the first layer, the residual stress Y of the second layer and the residual stress Z of the third layer satisfy the relationship of Equation 1.

[0033] X < Y < Z Equation 1

[0034] According to the present disclosure, it is possible to provide a cutting tool that has a long tool life especially in the light interrupted turning of alloy steel with black skin material.

[0035] (2) In the above (1), the residual stress X of the first layer is preferably -1.0 GPa or more and -0.3 GPa or less. Thereby, it is possible to provide a cutting tool that has an even longer tool life especially in the light interrupted turning of alloy steel with black skin material.

[0036] (3) In the above (1) or (2), the residual stress Y of the second layer is preferably -0.5 GPa or more and 0.1 GPa or less. Thereby, it is possible to provide a cutting tool that has an even longer tool life especially in the light interrupted turning of alloy steel with black skin material.

[0037] (4) In any one of the above (1) to (3), the residual stress Z of the third layer is preferably -0.3 GPa or more and 0.4 GPa or less. Thereby, it is possible to provide a cutting tool that has an even longer tool life especially in the light interrupted turning of alloy steel with black skin material.

[0038] (5) In any one of the above (1) to (4), the thickness of the first layer is preferably 3 μm or more and 15 μm or less. Thereby, it is possible to provide a cutting tool that has an even longer tool life especially in the light interrupted turning of alloy steel with black skin material.

[0039] (6) In any one of the above (1) to (5), the thickness of the second layer is preferably 3 μm or more and 15 μm or less. Thereby, it is possible to provide a cutting tool that has an even longer tool life especially in the light interrupted turning of alloy steel with black skin material.

[0040] (7) In any one of the above (1) to (6), the thickness of the third layer is preferably 2 μm or more and 4 μm or less. Thereby, it is possible to provide a cutting tool that has an even longer tool life especially in the light interrupted turning of alloy steel with black skin material.

[0041] [Details of Embodiments of the Present Disclosure]

[0042] A specific example of a cutting tool according to an embodiment of the present disclosure will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals denote the same or corresponding parts. In addition, the dimensional relationships such as length, width, thickness, and depth are appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0043] In this specification, the expression in the form of "A to B" means the upper and lower limits of the range (that is, A or more and B or less). When there is no unit description for A and only the unit is described for B, the unit of A is the same as the unit of B.

[0044] [Embodiment 1: Cutting Tool]

[0045] For the cutting tool according to an embodiment of the present disclosure, Figure 1 will be described.

[0046] An embodiment of the present disclosure (hereinafter, also referred to as "this embodiment".) is a cutting tool 10 including a substrate 1 and a coating 2 disposed on the substrate 1, wherein

[0047] the coating 2 includes a first layer 3 on the substrate 1, a second layer 4 on the first layer 3, and a third layer 5 on the second layer 4,

[0048] the first layer 3 is made of titanium carbonitride,

[0049] the second layer 4 is made of alumina,

[0050] the third layer 5 is made of titanium carbonitride,

[0051] the residual stress X of the first layer 3, the residual stress Y of the second layer 4, and the residual stress Z of the third layer 5 satisfy the relationship of Formula 1.

[0052] X < Y < Z Formula 1

[0053] According to the present disclosure, it is possible to provide a cutting tool having a long tool life particularly in light interrupted turning of alloy steel of black skin material. The reason is presumed as follows.

[0054] The residual stress X of the first layer 3, the residual stress Y of the second layer 4, and the residual stress Z of the third layer 5 satisfy the relationship of Formula 1.

[0055] X < Y < Z Formula 1

[0056] Thus, due to the relatively lower residual stress on the substrate 1 side of the coating 2, the defect resistance can be improved. Additionally, due to the relatively higher residual stress on the surface side of the coating 2, the film breakage caused by stress introduction is reduced and the occurrence of film tissue peeling is easily suppressed, so the abrasion resistance can be improved.

[0057] That is, according to the present disclosure, since the cutting tool 1 can have both excellent "abrasion resistance" and excellent "defect resistance", it is possible to provide a cutting tool that has a long tool life especially in the light interrupted turning of alloy steel with a black skin material.

[0058] "Cutting Tool"

[0059] As Figure 1 shown, the cutting tool 10 according to an embodiment of the present disclosure includes a substrate 1 and a coating 2 disposed on the substrate 1. The coating 2 preferably covers the entire surface of the substrate 1, but even if a part of the substrate 1 is not covered by the coating 2 or the composition of the coating 2 is locally different, it does not deviate from the scope of this embodiment. When a part of the substrate 1 is not covered by the coating 2, the coating 2 is preferably arranged to cover at least the surface of the part of the substrate 1 related to cutting. In this specification, the part related to the cutting of the substrate 1 also depends on the size and shape of the substrate 1, but in the substrate 1, it refers to the area surrounded by a hypothetical plane where the distance from the cutting edge ridge line to the perpendicular line along the cutting edge ridge line on the substrate 1 side is, for example, any one of 5 mm, 3 mm, 2 mm, 1 mm, and 0.5 mm.

[0060] The cutting tool 10 of this embodiment can preferably be used as cutting tools 10 such as drills, end mills, indexable cutting inserts for drills, indexable cutting inserts for end mills, indexable cutting inserts for milling, indexable cutting inserts for turning, metalworking saws, tooth cutting tools, reamers, taps, etc.

[0061] "Substrate"

[0062] As the substrate 1, any substrate that has been conventionally known as such a substrate can be used. For example, it is preferably any one of cemented carbide (WC-based cemented carbide, cemented carbide containing WC and Co, cemented carbide further added with carbides and nitrides such as Ti, Ta, Nb, etc.), cermet (cermet mainly composed of TiC, TiN, TiCN, etc.), high-speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, alumina, etc.), cubic boron nitride sintered body or diamond sintered body.

[0063] Among these various base materials 1, WC-based cemented carbides and cermets (particularly TiCN-based cermets) are particularly preferably selected. Since the balance between hardness and strength of these base materials 1 is excellent particularly at high temperatures, when used as the base material 1 of the cutting tool 10, it can contribute to the long life of the cutting tool 10.

[0064] 《Coating》

[0065] The coating 2 includes a first layer 3 on the base material 1, a second layer 4 on the first layer 3, and a third layer 5 on the second layer 4. The coating 2 covers the base material 1, thereby improving various properties such as the wear resistance and chipping resistance of the cutting tool 10, and has the effect of contributing to the long life of the cutting tool 10. In addition, the coating 2 can include the "other layers" described later within the range that does not impair the effects of the present disclosure, based on the first layer 3, the second layer 4, and the third layer 5.

[0066] The thickness of the coating 2 is preferably 6 μm or more and 30 μm or less. If the thickness of the coating 2 is less than 6 μm, the life of the cutting tool 10 tends to be easily shortened due to the too thin thickness of the coating 2. On the other hand, if the thickness of the coating 2 exceeds 30 μm, chipping of the coating 2 tends to occur easily at the initial stage of cutting, and the life of the cutting tool 10 tends to be easily shortened. The thickness of the coating 3 can be measured by observing the cross-section of the coating 2 using a scanning electron microscope (SEM). Specifically, with the observation magnification of the cross-section sample being 5,000 to 10,000 times and the observation area being 100 to 500 μm 2 , the thickness range of three parts is measured in one field of view, and the average value is taken as the "thickness". The same applies to the thickness of each layer described later, unless otherwise specified.

[0067] <First Layer>

[0068] <Composition of the First Layer>

[0069] The first layer 3 is composed of titanium carbonitride. Here, "being composed of titanium carbonitride" means that as long as the effects of the present disclosure are shown, inevitable impurities can be included on the basis of titanium carbonitride. As such inevitable impurities, for example, chlorine atoms (Cl) etc. can be cited. The overall content rate of the inevitable impurities in the first layer 3 is preferably greater than 0 mass% and less than 3 mass%.

[0070] That the first layer 3 is composed of titanium carbonitride is measured by X-ray diffraction method (XRD) and energy dispersive X-ray analysis (EDX). The content rate of the inevitable impurities in the first layer 3 is measured by secondary ion mass spectrometry (SIMS). In addition, it is confirmed that: as long as measured by the same cutting tool 10, even if the measurement part is arbitrarily selected, there is no deviation in the measurement result.

[0071] <Structure of the first layer>

[0072] The thickness of the first layer 3 is preferably 3 μm or more and 15 μm or less. Thereby, since it is possible to have both more excellent wear resistance and more excellent defect resistance, it is possible to provide a cutting tool having a longer tool life especially in the light interrupted turning of alloy steel of black skin material. The lower limit of the thickness of the first layer 3 is preferably 3 μm or more, more preferably 5 μm or more, and still more preferably 7 μm or more. The upper limit of the thickness of the first layer 3 is preferably 15 μm or less, more preferably 13 μm or less, and still more preferably 11 μm or less. The thickness of the first layer 3 is more preferably 5 μm or more and 13 μm or less, and still more preferably 7 μm or more and 11 μm or less.

[0073] <Residual stress of the first layer>

[0074] The residual stress X of the first layer 3 is preferably -1.0 GPa or more and -0.3 GPa or less. Thereby, when a minute defect occurs, it becomes easy to suppress the expansion of damage, so it is possible to provide a cutting tool having a longer tool life especially in the light interrupted turning of alloy steel of black skin material. The lower limit of the residual stress X of the first layer 3 is preferably -1.0 GPa or more, more preferably -0.9 GPa or more, and still more preferably -0.8 GPa or more. The upper limit of the residual stress X of the first layer 3 is preferably -0.3 GPa or less, more preferably -0.4 GPa or less, and still more preferably -0.5 GPa or less. The residual stress X of the first layer 3 is more preferably -0.9 GPa or more and -0.4 GPa or less, and still more preferably -0.8 GPa or more and -0.5 GPa or less.

[0075] The residual stress X of the first layer 3 can be determined by measuring the first layer 3 with an X-ray residual stress device by the sin2ψ method (pages 54 to 66 of "X-ray Stress Measurement Method" (published by Yoshikentang Co., Ltd. in 1981 by the Japan Society for Materials Science)). In addition, in this measurement, the temperature is room temperature (20 °C). In addition, it was confirmed that as long as the measurement is performed on the same cutting tool 10, even if the measurement site is arbitrarily selected, there is no deviation in the measurement results.

[0076] <Second layer>

[0077] <Composition of the second layer>

[0078] The second layer 4 is composed of alumina. Here, "composed of alumina" means that as long as the effects of the present disclosure are shown, inevitable impurities can be included on the basis of alumina. As such inevitable impurities, for example, chlorine atoms (Cl) etc. can be cited. The overall content rate of the inevitable impurities in the second layer 4 is preferably more than 0 mass% and less than 3 mass%.

[0079] The second layer 4 is composed of alumina and is measured by X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDX). In the second layer 4, the content rate of inevitable impurities is measured by secondary ion mass spectrometry (SIMS). In addition, it was confirmed that as long as the measurement is performed with the same cutting tool 10, even if the measurement site is arbitrarily selected, there is no deviation in the measurement results.

[0080] <Structure of the second layer>

[0081] The thickness of the second layer 4 is preferably 3 μm or more and 15 μm or less. Thus, since it is possible to have both more excellent wear resistance and more excellent chipping resistance, it is possible to provide a cutting tool having a longer tool life especially in the light interrupted turning of alloy steel with black skin material. The lower limit of the thickness of the second layer 4 is preferably 3 μm or more, more preferably 5 μm or more, and further preferably 7 μm or more. The upper limit of the thickness of the second layer 4 is preferably 15 μm or less, more preferably 13 μm or less, and further preferably 11 μm or less. The thickness of the second layer 4 is more preferably 5 μm or more and 13 μm or less, and further preferably 7 μm or more and 11 μm or less.

[0082] <Residual stress of the second layer>

[0083] The residual stress Y of the second layer 4 is preferably -0.5 GPa or more and 0.1 GPa or less. Thus, since the residual stress is moderately introduced and the structure of alumina is hardly damaged, the chipping resistance can be improved, and it is possible to provide a cutting tool having a longer tool life especially in the light interrupted turning of alloy steel with black skin material. The lower limit of the residual stress Y of the second layer 4 is preferably -0.5 GPa or more, more preferably -0.4 GPa or more, and further preferably -0.3 GPa or more. The upper limit of the residual stress Y of the second layer 4 is preferably 0.1 GPa or less, more preferably 0 GPa or less, and further preferably -0.1 GPa or less. The residual stress Y of the second layer 4 is more preferably -0.4 GPa or more and 0 GPa or less, and further preferably -0.3 GPa or more and -0.1 GPa or less.

[0084] The residual stress Y of the second layer 4 can be determined by the same method as the method for measuring the residual stress X of the first layer 3 except for the point where the second layer 4 is measured. In addition, it was confirmed that as long as the measurement is performed with the same cutting tool 10, even if the measurement site is arbitrarily selected, there is no deviation in the measurement results.

[0085] <Third layer>

[0086] <Composition of the third layer>

[0087] The third layer 5 is composed of titanium carbonitride. Here, "composed of titanium carbonitride" means that as long as the effects of the present disclosure are shown, inevitable impurities can be included on the basis of titanium carbonitride. Examples of such inevitable impurities include chlorine atoms (Cl). The overall content rate of the inevitable impurities in the third layer 5 is preferably greater than 0% by mass and less than 3% by mass.

[0088] That the third layer 5 is composed of titanium carbonitride is measured by X-ray diffraction method (XRD) and energy dispersive X-ray analysis (EDX). In the third layer 5, the content rate of the inevitable impurities is measured by secondary ion mass spectrometry (SIMS). In addition, it has been confirmed that as long as the measurement is performed on the same cutting tool 10, even if the measurement site is arbitrarily selected, there is no deviation in the measurement results.

[0089] <Structure of the third layer>

[0090] The thickness of the third layer 5 is preferably 2 μm or more and 4 μm or less. Thus, since more excellent chipping resistance and more excellent wear resistance can be achieved concurrently, a cutting tool having a longer tool life especially in light interrupted turning of alloy steel with black skin material can be provided. The lower limit of the thickness of the third layer 5 is preferably 2 μm or more, more preferably 2.5 μm or more. The upper limit of the thickness of the third layer 5 is preferably 4 μm or less, more preferably 3.5 μm or less. The thickness of the third layer 5 is more preferably 2.5 μm or more and 3.5 μm or less.

[0091] <Residual stress of the third layer>

[0092] The residual stress Z of the third layer 5 is preferably -0.3 GPa or more and 0.4 GPa or less. Thus, since flank wear at the initial stage of machining can be easily suppressed, a cutting tool having a longer tool life especially in light interrupted turning of alloy steel with black skin material can be provided. The lower limit of the residual stress Z of the third layer 5 is preferably -0.3 GPa or more, more preferably -0.2 GPa or more, and further preferably -0.1 GPa or more. The upper limit of the residual stress Z of the third layer 5 is preferably 0.4 GPa or less, more preferably 0.3 GPa or less, and further preferably 0.2 GPa or less. The residual stress Z of the third layer 5 is more preferably -0.2 GPa or more and 0.3 GPa or less, and further preferably -0.1 GPa or more and 0.2 GPa or less.

[0093] The residual stress Z of the third layer 5 can be determined by the same method as the method for measuring the residual stress X of the first layer 3 except for the point where the third layer 5 is measured. In addition, it has been confirmed that as long as the measurement is performed on the same cutting tool 10, even if the measurement site is arbitrarily selected, there is no deviation in the measurement results.

[0094] <Relationship between the first layer, the second layer and the third layer>

[0095] The residual stress X of the first layer 3, the residual stress Y of the second layer 4, and the residual stress Z of the third layer 5 satisfy the relationship of Equation 1.

[0096] X < Y < Z Equation 1

[0097] Thus, since the cutting tool 10 can have both excellent wear resistance and excellent chipping resistance, it can exhibit a long tool life especially in the light interrupted turning of alloy steel with a black skin material.

[0098] Y - X is preferably 0.1 or more and 0.6 or less. Thus, since it is more difficult for chipping to occur from the first layer 3 to the second layer 4, the cutting tool can have more excellent chipping resistance. Y - X is more preferably 0.15 or more and 0.55 or less, and further preferably 0.2 or more and 0.5 or less.

[0099] Y - Z is preferably -0.6 or more and -0.1 or less. Thus, since it is more difficult for chipping to occur from the second layer 4 to the third layer 5, the cutting tool 10 can have more excellent chipping resistance. Y - Z is more preferably -0.55 or more and -0.15 or less, and further preferably -0.50 or more and -0.20 or less.

[0100] <Other Layers>

[0101] As other layers, for example, a base layer (not shown), an intermediate layer (not shown), and a surface layer (not shown) can be cited. The base layer is a layer disposed between the base material 1 and the first layer 3. The surface layer is a layer located on the surface of the coating film 2. The intermediate layer is a layer disposed between the first layer 3 and the second layer 4, between the second layer 4 and the third layer 5, or both. In addition, the intermediate layer is a thin adherent layer such as TiCNO. Therefore, the intermediate layer does not affect the stress distribution.

[0102] [Embodiment 2: Manufacturing Method of Cutting Tool]

[0103] Use Figure 2 The manufacturing method of the cutting tool of the present embodiment will be described. Figure 2 is a schematic cross-sectional view of an example of a CVD apparatus used for manufacturing the cutting tool of the present embodiment.

[0104] The manufacturing method of the cutting tool of the present embodiment is the manufacturing method of the cutting tool described in Embodiment 1, wherein

[0105] The manufacturing method of the cutting tool includes:

[0106] A first step, in which the base material is prepared;

[0107] Second process, in the second process, a coating film is formed on the substrate; and

[0108] Third process, in the third process, a cutting tool is obtained by sandblasting the coating film,

[0109] The second process sequentially includes a 2A process of forming a first layer by CVD method, a 2B process of forming a second layer by CVD method, and a 2C process of forming a third layer by CVD method. The detailed content of each process will be described below.

[0110] 《First process》

[0111] In the first process, a substrate is prepared. The substrate can be the substrate described in Embodiment 1.

[0112] For example, when using cemented carbide as the substrate, a commercially available substrate can be used, or it can be manufactured by a general powder metallurgy method. In the case of manufacturing by a general powder metallurgy method, for example, WC powder and Co powder are mixed by a ball mill or the like to obtain a mixed powder. After drying the mixed powder, it is formed into a predetermined shape to obtain a formed body. By further sintering the formed body, a WC-Co based cemented carbide (sintered body) is obtained. Next, by performing predetermined cutting edge processing such as honing on the sintered body, a substrate made of WC-Co based cemented carbide can be manufactured. Even for substrates other than the above, as long as they are substrates publicly known as such substrates, any one can be prepared.

[0113] 《Second process》

[0114] In the second process, a coating film is formed on the above substrate to obtain a cutting tool. The formation of the coating film is performed using, for example, Figure 2 the CVD apparatus shown. The CVD apparatus 30 includes: a plurality of substrate setting jigs 31 for holding the substrate 1; and a reaction vessel 32 made of heat-resistant alloy steel that covers the substrate setting jigs 31. In addition, a temperature control device 33 for controlling the temperature inside the reaction vessel 32 is provided around the reaction vessel 32. A gas inlet pipe 35 having a gas inlet 34 is provided in the reaction vessel 32. In the internal space of the reaction vessel 32 where the substrate setting jigs 31 are arranged, the gas inlet pipe 35 extends in the vertical direction and is arranged so as to be rotatable about the vertical axis. In addition, a plurality of ejection holes (through holes 36) for ejecting gas into the reaction vessel 32 are provided. Using this CVD apparatus 30, the first layer, the second layer, and the third layer that constitute the above coating film can be formed.

[0115] The second process sequentially includes a 2A process of forming a first layer by CVD method, a 2B process of forming a second layer by CVD method, and a 2C process of forming a third layer by CVD method. When the coating film includes the "other layer" described in Embodiment 1, the "other layer" can be formed by a conventionally known method.

[0116] <2A process: Process of forming a first layer by CVD method>

[0117] In the 2A process, a first layer is formed by CVD method. More specifically, first, the substrate 1 is disposed on the substrate setting jig 31, the temperature and pressure in the reaction vessel 32 are controlled within a predetermined range, and at the same time, the raw material gas for the first layer is introduced into the reaction vessel 32 from the gas introduction pipe 35. Thus, a first layer is formed on the substrate 1.

[0118] As the raw material gas for the first layer, TiCl 4 , CH 3 CN, CO, N 2 , HCl and H 2 mixed gas are used.

[0119] The content rate of TiCl 4 in the mixed gas is preferably 8.0 vol% or more and 9.0 vol% or less. The content rate of CH 3 CN in the mixed gas is preferably 0.2 vol% or more and 1.0 vol% or less. The content rate of CO in the mixed gas is preferably 1.3 vol% or more and 2.0 vol% or less. The content rate of N 2 in the mixed gas is preferably 8.0 vol% or more and 12.0 vol% or less. The content rate of HCl in the mixed gas is preferably 1.0 vol% or more and 3.0 vol% or less.

[0120] The temperature in the reaction vessel 32 is preferably controlled to be 800 °C or more and 850 °C or less, and the pressure in the reaction vessel 32 is preferably controlled to be 100 hPa or more and 120 hPa or less. In addition, it is preferable to rotate the gas introduction pipe 35 during gas introduction.

[0121] For the above manufacturing method, by controlling each condition of the CVD method, the morphology of the first layer changes. For example, by adjusting the film formation time, the thickness of the first layer is controlled.

[0122] <2B process: Process of forming a second layer by CVD method>

[0123] In the 2B process, the second layer is formed by CVD method. More specifically, first, the first cutting tool precursor with the first layer formed on the substrate is disposed on the substrate setting jig 31, the temperature and pressure in the reaction vessel 32 are controlled within a predetermined range, and at the same time, the raw material gas for the second layer is introduced into the reaction vessel 32 from the gas introduction pipe 35. Thereby, the second layer is formed on the first layer.

[0124] As the raw material gas for the second layer, AlCl 3 , CO 2 , H 2 S and H 2 mixed gas are used.

[0125] The content rate of AlCl 3 in the mixed gas is preferably 2.0% by volume or more and 2.5% by volume or less. The content rate of CO 2 in the mixed gas is preferably 2.5% by volume or more and 3.5% by volume or less. The content rate of H 2 S in the mixed gas is preferably 0.5% by volume or more and 1.0% by volume or less.

[0126] The temperature in the reaction vessel 32 is preferably controlled to be 980 °C or more and 1015 °C or less, and the pressure in the reaction vessel 32 is preferably controlled to be 60 hPa or more and 75 hPa or less. In addition, it is preferable to rotate the gas introduction pipe 35 during gas introduction.

[0127] For the above manufacturing method, by controlling each condition of the CVD method, the morphology of the second layer changes. For example, by adjusting the film formation time, the thickness of the second layer is controlled.

[0128] <2C process: Process of forming the third layer by CVD method>

[0129] In the 2C process, the third layer is formed by CVD method. More specifically, first, the second cutting tool precursor with the first layer formed on the substrate and the second layer formed on the first layer is disposed on the substrate setting jig 31, the temperature and pressure in the reaction vessel 32 are controlled within a predetermined range, and at the same time, the raw material gas for the third layer is introduced into the reaction vessel 32 from the gas introduction pipe 35. Thereby, the third layer is formed on the second layer.

[0130] As the raw material gas for the third layer, TiCl 4 , CH 3 CN, CO, N 2 , HCl and H 2 mixed gas are used.

[0131] The TiCl 4The content ratio is preferably 8.0% by volume or more and 9.0% by volume or less. CH in the mixed gas 3 The content ratio of 3 is preferably 0.2% by volume or more and 0.8% by volume or less. The content ratio of CO in the mixed gas is preferably 1.3% by volume or more and 2.0% by volume or less. N in the mixed gas 2 The content ratio is preferably 8.0% by volume or more and 12.0% by volume or less. The content ratio of HCl in the mixed gas is preferably 1.0% by volume or more and 3.0% by volume or less.

[0132] The temperature inside the reaction vessel 32 is preferably controlled to be 950 °C or more and 1000 °C or less, and the pressure inside the reaction vessel 32 is preferably controlled to be 80 hPa or more and 100 hPa or less. In addition, it is preferable to rotate the gas inlet pipe 35 when introducing the gas.

[0133] For the above manufacturing method, by controlling the conditions of the CVD method, the morphology of the third layer changes. For example, by adjusting the film formation time, the thickness of the third layer is controlled.

[0134] <Third process: Process of obtaining a cutting tool by performing sandblasting on the coated film>

[0135] In the third process, a cutting tool is obtained by performing sandblasting on the coated film. Here, "sandblasting" is a process in which a large number of small spheres (media) such as steel or non-ferrous metals (e.g., ceramics) collide (project) with the surface of the coated film such as the rake face at high speed to change many properties such as the residual stress on the surface.

[0136] Examples of the type of the medium include ceramics, zirconia, alumina, etc.

[0137] The average particle diameter of the medium is 100 μm or more and 200 μm or less.

[0138] The concentration of the projected medium is 100 g / min or more and 350 g / min or less. The concentration of the projected medium is preferably 150 g / min or more and 250 g / min or less.

[0139] The distance between the projection part of the projected medium and the surface of the coated film (hereinafter, also referred to as "projection distance".) is 35 mm or more and 60 mm or less. The projection distance is preferably 35 mm or more and 50 mm or less.

[0140] The projection angle of the medium with respect to the surface of the coated film is 75°.

[0141] The pressure applied to the above medium during projection (hereinafter, also referred to as "projection pressure".) is preferably 0.10 MPa or more and 0.50 MPa or less, and more preferably 0.15 MPa or more and 0.45 MPa or less.

[0142] The treatment time of sandblasting is preferably 20 seconds or more and 30 seconds or less.

[0143] Each condition of the above sandblasting treatment can be appropriately adjusted corresponding to the constitution of the above coating.

[0144] <Other processes>

[0145] In the manufacturing method according to the present embodiment, supplementary processes can also be appropriately performed within the range that does not impair the effects of the present embodiment, in addition to the above processes.

[0146] <Features of the manufacturing method of the cutting tool of the present embodiment>

[0147] A cutting tool can be manufactured, and the cutting tool obtained by the above manufacturing method is a cutting tool having a substrate and a coating disposed on the substrate. The coating includes a first layer on the substrate, a second layer on the first layer, and a third layer on the second layer. The first layer is composed of titanium carbonitride, the second layer is composed of alumina, the third layer is composed of titanium carbonitride, and the residual stress X of the first layer, the residual stress Y of the second layer, and the residual stress Z of the third layer satisfy the relationship of Formula 1.

[0148] X < Y < Z Formula 1

[0149] The reason is presumed as follows.

[0150] The feature of the manufacturing method of the cutting tool of the present embodiment lies particularly in that in the 2C process, on the basis of forming the third layer on the second layer, through the third process, using coarse media with an average particle size of 100 to 200 μm, the concentration of the media is 100 g / min or more and 350 g / min or less, and the projection angle of the media with respect to the surface of the coating is 75°, and the projection distance is 35 mm or more and 60 mm or less, and thus it is carried out. By projecting coarse media at a projection angle of 75°, stress is easily introduced to the substrate side of the coating. In addition, since the concentration of the media is thin, the projection speed of the media can be easily increased, and thus stress is more easily introduced to the substrate side of the coating. In addition, since the projection distance is long, a difference can be made between the stress of the third layer and the stress of the second layer. Thus, the residual stress X of the first layer, the residual stress Y of the second layer, and the residual stress Z of the third layer can satisfy the relationship of the above Formula 1. This is the result of in-depth research by the inventors of the present invention and is newly discovered.

[0151] Examples

[0152] The present embodiment will be further specifically described by way of examples. However, the present embodiment is not limited by these examples.

[0153] <Manufacture of cutting tool>

[0154] As follows, cutting tools related to Specimens 1 to 31 and 101 to 104 were produced.

[0155] <First process>

[0156] As a base material, an indexable carbide cutting insert (shape: manufactured by Sumitomo Electric Carbide Co., Ltd., SEET13T3AGSN-G) having a composition consisting of TaC (2.0% by mass), Co (11.0% by mass), and WC (the balance) (including inevitable impurities) was prepared.

[0157] <Second process>

[0158] In such a manner that the composition of the first layer was as described in Tables 3 and 4, the first layer was formed on the above base material by CVD method under the following conditions (2A process). The film formation time was appropriately prepared such that the first layer had the thickness described in Tables 3 and 4.

[0159] (Conditions of 2A process)

[0160] · Content of TiCl 4 in the mixed gas: 8.0 to 9.0% by volume

[0161] · Content of CH 3 CN in the mixed gas: 0.2 to 1.0% by volume

[0162] · Content of CO in the mixed gas: 1.3 to 2.0% by volume

[0163] · Content of N 2 in the mixed gas: 8.0 to 12.0% by volume

[0164] · Content of HCl in the mixed gas: 1.0 to 3.0% by volume

[0165] · Content of H 2 in the mixed gas: the balance

[0166] · Temperature: 800 to 850 °C

[0167] · Pressure: 100 to 120 hPa

[0168] Next, in such a manner that the composition of the second layer was as described in Tables 3 and 4, the second layer was formed on the above first layer by CVD method under the following conditions (2B process). The film formation time was appropriately prepared such that the second layer had the thickness described in Tables 3 and 4.

[0169] (Conditions of 2B process)

[0170] · Content ratio of AlCl in the mixed gas 3 : 2.0 - 2.5% by volume

[0171] · Content ratio of CO in the mixed gas 2 : 2.5 - 3.5% by volume

[0172] · Content ratio of H 2 S in the mixed gas: 0.5 - 1.0% by volume

[0173] · Content ratio of H 2 in the mixed gas: balance

[0174] · Temperature: 980 - 1015 °C

[0175] · Pressure: 60 - 75 hPa

[0176] Next, with the composition of the third layer as described in Table 3 and Table 4, under the following conditions, the third layer was formed on the above-mentioned second layer by CVD method (2C process). The film formation time was appropriately prepared so that the third layer had the thickness described in Table 3 and Table 4.

[0177] (Conditions of 2C process)

[0178] · Content ratio of TiCl in the mixed gas 4 : 8.0 - 9.0% by volume

[0179] · Content ratio of CH 3 CN in the mixed gas: 0.2 - 0.8% by volume

[0180] · Content ratio of CO in the mixed gas: 1.3 - 2.0% by volume

[0181] · Content ratio of N 2 in the mixed gas: 8.0 - 12.0% by volume

[0182] · Content ratio of HCl in the mixed gas: 1.0 - 3.0% by volume

[0183] · Content ratio of H 2 in the mixed gas: balance

[0184] · Temperature: 950 - 1000 °C

[0185] · Pressure: 80 - 100 hPa

[0186] <Third process>

[0187] The surface of a cutting tool having a first layer, a second layer, and a third layer (in other words, a cutting tool having a coating) was subjected to sandblasting under the conditions described in Table 1 and Table 2.

[0188] Through the above steps, cutting tools related to Specimens 1 to 31 and 101 to 104 were produced.

[0189] Table 1

[0190]

[0191] Table 2

[0192]

[0193] Table 3

[0194]

[0195] Table 4

[0196]

[0197] "Evaluation of the Characteristics of Cutting Tools"

[0198] <Composition of the First Layer>

[0199] For the cutting tools related to each specimen, the composition of the first layer was determined by the method described in Embodiment 1. The obtained results were entered in the "Composition" column of the "First Layer" column in Table 3 and Table 4. When "TiCN" is entered in the "Composition" column of the "First Layer" column in Table 3 and Table 4, it means that the first layer is composed of titanium carbonitride.

[0200] <Residual Stress X of the First Layer>

[0201] For the cutting tools related to each specimen, the residual stress X of the first layer was determined by the method described in Embodiment 1. The obtained results were entered in the "X [GPa]" column of Table 3 and Table 4.

[0202] <Composition of the Second Layer>

[0203] For the cutting tools related to each specimen, the composition of the second layer was determined by the method described in Embodiment 1. The obtained results were entered in the "Composition" column of the "Second Layer" column in Table 3 and Table 4. When "Al 2 O 3 " is entered in the "Composition" column of the "Second Layer" column in Table 3 and Table 4, it means that the second layer is composed of aluminum oxide.

[0204] <Residual Stress Y of the Second Layer>

[0205] For the cutting tools related to each specimen, the residual stress Y of the second layer was obtained by the method described in Embodiment 1. The obtained results were entered in the column of "Y [GPa]" in Table 3 and Table 4.

[0206] <Composition of the third layer>

[0207] For the cutting tools related to each specimen, the composition of the third layer was obtained by the method described in Embodiment 1. The obtained results were entered in the column of "Composition" in the column of "Third layer" in Table 3 and Table 4. When "TiCN" is described in the column of "Composition" in the column of "Third layer" in Table 3 and Table 4, it means that the third layer is composed of titanium carbonitride.

[0208] <Residual stress Z of the third layer>

[0209] For the cutting tools related to each specimen, the residual stress Z of the third layer was obtained by the method described in Embodiment 1. The obtained results were entered in the column of "Z [GPa]" in Table 3 and Table 4.

[0210] <Thickness of the coating>

[0211] For the cutting tools related to each specimen, the thickness of the coating was obtained by the method described in Embodiment 1. The obtained results were entered in the column of "Thickness [μm]" in the column of "Coating" in Table 3 and Table 4.

[0212] <Cutting test>

[0213] Using the cutting tools related to each specimen, a cutting test was carried out under the following cutting conditions. Wear and slight defects were combined and the damage progressed, and the tool life was measured by the time when the flank wear amount Vb [mm] exceeded 0.3 mm. The obtained results were entered in the column of "Tool life [min]" in Table 3 and Table 4.

[0214] (Cutting conditions)

[0215] Workpiece: SCM440 (grooved round bar)

[0216] Machining: Turning the outer diameter of the grooved round bar

[0217] Cutting speed: 250 m / min

[0218] Feed rate: 0.3 mm / rev

[0219] Depth of cut: 2.0 mm

[0220] Cutting fluid: Water-soluble cutting oil

[0221] The above cutting conditions correspond to the cutting conditions of light interrupted turning of alloy steel with black skin material.

[0222] The cutting tools related to Specimens 1 to 31 correspond to the examples. The cutting tools related to Specimens 101 to 104 correspond to the comparative examples. From the results in Table 3 and Table 4, it can be seen that: compared with the cutting tools related to Specimens 101 to 104, the cutting tools related to Specimens 1 to 31 also have a long tool life in the light interrupted turning of alloy steel with black skin material.

[0223] From this, it can be known that: the cutting tools related to Specimens 1 to 31 also have a long tool life in the light interrupted turning of alloy steel with black skin material.

[0224] The embodiments and examples of the present disclosure have been described above, but it was also initially planned to appropriately combine the configurations of the above-described embodiments and examples or to make various modifications.

[0225] It should be considered that the embodiments and examples disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is not represented by the above-described embodiments and examples, but by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims.

[0226] Description of Reference Numerals

[0227] 1: Substrate; 2: Coating; 3: First layer; 4: Second layer; 5: Third layer; 10: Cutting tool; 30: CVD apparatus; 31: Substrate setting jig; 32: Reaction vessel; 33: Temperature control device; 34: Gas inlet; 35: Gas inlet pipe; 36: Through hole.

Claims

1. A cutting tool comprising a substrate and a coating disposed on the substrate, wherein, the coating includes a first layer on the substrate, a second layer on the first layer, and a third layer on the second layer, the first layer is composed of titanium carbonitride, the second layer is composed of alumina, the third layer is composed of titanium carbonitride, the residual stress X of the first layer, the residual stress Y of the second layer, and the residual stress Z of the third layer satisfy the relationship of Formula 1, X < Y < Z Formula 1.

2. The cutting tool according to claim 1, wherein, the residual stress X of the first layer is not less than -1.0 GPa and not more than -0.3 GPa.

3. The cutting tool according to claim 1 or 2, wherein, the residual stress Y of the second layer is not less than -0.5 GPa and not more than 0.1 GPa.

4. The cutting tool according to any one of claims 1 to 3, wherein, the residual stress Z of the third layer is not less than -0.3 GPa and not more than 0.4 GPa.

5. The cutting tool according to any one of claims 1 to 4, wherein, the thickness of the first layer is not less than 3 μm and not more than 15 μm.

6. The cutting tool according to any one of claims 1 to 5, wherein, the thickness of the second layer is not less than 3 μm and not more than 15 μm.

7. The cutting tool according to any one of claims 1 to 6, wherein, the thickness of the third layer is not less than 2 μm and not more than 4 μm.

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