Cutting tool

Abstract

A cutting tool according to the present invention comprises a base material, and a coating that is disposed on the base material, wherein the coating includes a first layer positioned on the base material and a second layer positioned on the first layer, the first layer is composed of α-Al2O3, the second layer is composed of TiCN, the thickness of the second layer is at least 0.5 μm and less than 2.0 μm, and the residual stress X of the second layer is −2.0 GPa or greater and −0.5 GPa or less.

Description

cutting tools

[0001] The present disclosure relates to cutting tools.

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

[0003] JP 2020-037150 A JP 2020-116645 A International Publication No. 2009 / 112116 International Publication No. 2022 / 244241 International Publication No. 2022 / 244242 International Publication No. 2022 / 244243

[0004] The cutting tool of the present disclosure is a cutting tool comprising a substrate and a coating disposed on the substrate, the coating including a first layer located on the substrate and a second layer located on the first layer, the first layer being α-Al ２ O ３ the second layer is made of TiCN, the thickness of the second layer is 0.5 μm or more and less than 2.0 μm, and the residual stress X of the second layer is −2.0 GPa or more and −0.5 GPa or less.

[0005] Fig. 1 is a schematic cross-sectional view illustrating one embodiment of the cutting tool of the present disclosure. Fig. 2 is a schematic cross-sectional view illustrating another embodiment of the cutting tool of the present disclosure. Fig. 3 is a schematic cross-sectional view illustrating still another embodiment of the cutting tool of the present disclosure. Fig. 4 is a schematic cross-sectional view of an example of a CVD (Chemical Vapor Deposition) apparatus used in manufacturing the cutting tool of the present disclosure.

[0006] [Problem to be Solved by the Present Disclosure] In recent years, there has been an increasing demand for improved tool life, particularly in the interrupted turning of cast iron. Important factors for further improving tool life in the interrupted turning of cast iron include "wear resistance" and "chipping resistance." Furthermore, from the perspective of improving the cutting performance of cutting tools in the interrupted turning of cast iron, a cutting tool is provided that includes a substrate and a coating disposed on the substrate, and the coating is formed of α-Al positioned on the substrate. ２ O ３ layer and the α-Al ２ O ３and a TiCN layer located on the α-Al layer. ２ O ３ Since the TiCN layer is formed by a CVD method, the TiCN layer is formed by a CVD method. Here, the TiCN layer contributes to the "wear resistance" and "chipping resistance" of the coating. Furthermore, from the viewpoint of improving "wear resistance," cutting tools are used in which the thickness of the TiCN layer is 0.5 μm or more but less than 2.0 μm. However, in such cutting tools, when attempting to impart high compressive residual stress to provide better cutting performance, the thin TiCN layer is prone to wear and wear, making it difficult to achieve both excellent "wear resistance" and excellent "chipping resistance." Therefore, there is a need to combine excellent "wear resistance" and excellent "chipping resistance" to extend tool life, especially in intermittent turning of cast iron.

[0007] Therefore, an object of the present disclosure is to provide a cutting tool that has a long tool life, particularly in interrupted turning of cast iron.

[0008] Effect of the Present Disclosure According to the present disclosure, it is possible to provide a cutting tool having a long tool life, particularly in the interrupted turning of cast iron.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. (1) A cutting tool of the present disclosure is a cutting tool including a substrate and a coating disposed on the substrate, wherein the coating includes a first layer located on the substrate and a second layer located on the first layer, and the first layer is made of α-Al. ２ O ３ the second layer is made of TiCN, the thickness of the second layer is 0.5 μm or more and less than 2.0 μm, and the residual stress X of the second layer is −2.0 GPa or more and −0.5 GPa or less.

[0010] According to the present disclosure, a cutting tool having a long tool life can be provided, particularly in intermittent turning of cast iron.

[0011] (2) In the above (1), the thickness of the first layer may be 3.0 μm or more and 15.0 μm or less, thereby providing a cutting tool having a longer tool life, particularly in intermittent turning of cast iron.

[0012] (3) In the above (1) or (2), the orientation index TC(0 0 12) of the first layer may be 3.0 or more, thereby providing a cutting tool having a longer tool life, particularly in interrupted turning of cast iron.

[0013] (4) In any of the above (1) to (3), the coating may further include a third layer located between the substrate and the first layer, the third layer may be made of TiCN, and the residual stress Y of the third layer may be -1.0 GPa or more and 1.0 GPa or less. This makes it possible to provide a cutting tool having a longer tool life, particularly in intermittent turning of cast iron.

[0014] [Details of the embodiment of the present disclosure] A specific example of a cutting tool according to one embodiment of the present disclosure (hereinafter also referred to as "the present embodiment") will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference symbols represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been changed as appropriate for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0015] In this specification, the expression "A to B" means the upper and lower limits of a range (i.e., A or more and B or less), and when no unit is specified for A and a unit is specified only for B, the unit of A and the unit of B are the same.

[0016] In the present disclosure, when a compound or the like is represented by a chemical formula, unless the atomic ratio is particularly limited, it is intended to include any conventionally known atomic ratio, and should not necessarily be limited to only those within the stoichiometric range.

[0017] [Embodiment 1: Cutting Tool] A cutting tool according to one embodiment of the present disclosure will be described with reference to Figures 1 to 3. One 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 the coating 2 includes a first layer 3 located on the substrate 1 and a second layer 4 located on the first layer 3, and the first layer 3 is made of α-Al ２ O ３ The second layer 4 is made of TiCN, the thickness of the second layer 4 is 0.5 μm or more and less than 2.0 μm, and the residual stress X of the second layer 4 is −2.0 GPa or more and −0.5 GPa or less.

[0018] According to the present disclosure, it is possible to provide a cutting tool 10 having a long tool life, particularly in the interrupted turning of cast iron. The reason for this is presumably as follows.

[0019] (a) The thickness of the second layer 4 is 0.5 μm or more and less than 2.0 μm. This can improve the “wear resistance” of the cutting tool 10.

[0020] (b) As described above, the "wear resistance" of the cutting tool 10 can be improved by setting the thickness of the second layer 4 to be 0.5 μm or more and less than 2.0 μm. However, when attempting to impart high compressive residual stress to further improve the cutting performance of the cutting tool 10 by simply setting the thickness of the second layer 4 to be 0.5 μm or more and less than 2.0 μm, the second layer 4 may be easily worn away due to its thin thickness. Therefore, particularly in the intermittent turning of cast iron, it may be difficult to provide a cutting tool 10 with a long tool life that combines excellent "wear resistance" and excellent "chipping resistance."

[0021] (c) In the cutting tool 10 according to this embodiment, the residual stress X of the second layer 4 is −2.0 GPa or more and −0.5 GPa or less. ２ O ３ Since excellent compressive residual stress can be imparted to the surface side of the coating from the layer consisting of (i.e., the first layer), the "chipping resistance" of the cutting tool 10 can be improved.

[0022] 1 to 3 , a 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; however, it is within the scope of this embodiment if a portion of the substrate 1 is not coated with the coating 2 or if the coating 2 has a partially different configuration. In cases where a portion of the substrate 1 is not coated with the coating 2, the coating 2 may be disposed so as to cover at least the surface of a portion of the substrate 1 involved in cutting. In this specification, the portion of the substrate 1 involved in cutting refers to a region of the substrate 1 surrounded by a cutting edge ridge and a virtual surface that is, depending on the size and shape of the substrate 1, a distance from the cutting edge ridge toward the substrate 1 along a perpendicular to a tangent to the cutting edge ridge, for example, 5 mm, 3 mm, 2 mm, 1 mm, or 0.5 mm.

[0023] The cutting tool 10 of this embodiment can be suitably used as a cutting tool 10 such as a drill, an end mill, an indexable cutting tip for a drill, an indexable cutting tip for an end mill, an indexable cutting tip for a milling process, an indexable cutting tip for a turning process, a metal saw, a gear cutting tool, a reamer, a tap, etc.

[0024] <<Substrate>> Any conventionally known substrate 1 of this type can be used as the substrate 1. For example, the substrate 1 is preferably any one of cemented carbide (WC-based cemented carbide, cemented carbide containing WC and Co, cemented carbide containing carbonitrides of Ti, Ta, Nb, etc.), cermet (mainly composed of TiC (titanium carbide), TiN (titanium nitride), TiCN (titanium carbonitride), etc.), high-speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), cubic boron nitride sintered body, and diamond sintered body.

[0025] It is particularly preferable to select a WC-based cemented carbide or a cermet (particularly a TiCN-based cermet) from among these various substrates 1. These substrates 1 have an excellent balance between hardness and strength, particularly at high temperatures, and therefore, when used as the substrate 1 of a cutting tool 10, can contribute to extending the life of the cutting tool 10.

[0026] Coating The coating 2 includes a first layer 3 located on the substrate 1 and a second layer 4 located on the first layer 3. By covering the substrate 1, the coating 2 improves various properties of the cutting tool 10, such as wear resistance and chipping resistance, and has the effect of extending the life of the cutting tool 10. The effects of the present disclosure can be achieved by having the second layer present in part or the entire area involved in cutting. The coating 2 may include a first layer 3 located on the substrate 1 and a second layer 4 located on the first layer 3. The coating 2 may further include a third layer 5 located between the substrate 1 and the first layer 3. The coating 2 may include a first layer 3 located on the substrate 1, a second layer 4 located on the first layer 3, and a third layer 5 located between the substrate 1 and the first layer 3. The coating 2 may further include a fourth layer 6 located on the second layer 4. The coating 2 may be composed of a first layer 3 positioned on the substrate 1, a second layer 4 positioned on the first layer 3, and a fourth layer 6 positioned on the second layer 4. The coating 2 may be composed of the first layer 3 positioned on the substrate 1, the second layer 4 positioned on the first layer 3, a third layer 5 positioned between the substrate 1 and the first layer 3, and a fourth layer 6 positioned on the second layer 4. In addition to the first layer 3, second layer 4, and third layer 5, the coating 2 may also include "other layers" described below, as long as the effects of the present disclosure are not impaired.

[0027] The thickness of the coating 2 may be 3.5 μm or more and 30.0 μm or less. If the thickness of the coating 2 is less than 3.5 μm, the coating 2 is too thin, which tends to shorten the life of the cutting tool 10. On the other hand, if the thickness of the coating 2 exceeds 30.0 μm, chipping of the coating 2 tends to occur in the early stages of cutting, which tends to shorten the life of the cutting tool 10. 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, the observation magnification of the cross section sample is set to 5,000 to 10,000 times, and the observation area is set to 100 to 500 μm. ２ The thickness width is measured at any three points in one visual field, and the average value is taken as the "thickness." The same applies to the thickness of each layer described below unless otherwise specified.

[0028] <First Layer> <Composition of First Layer> The first layer 3 is made of α-Al２ O ３ (In other words, it is made of α-alumina). ２ O ３ "consisting of α-Al" means, as far as the effects of the present disclosure are concerned, ２ O ３ This means that the first layer 3 may contain inevitable impurities in addition to the above. Examples of the inevitable impurities include chlorine atoms (Cl). The total content of the inevitable impurities in the first layer 3 may be more than 0 mass % or less than 3 mass %.

[0029] The first layer 3 is α-Al ２ O ３ The content of inevitable impurities in the first layer 3 is measured by secondary ion mass spectrometry (SIMS). It has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected, as long as the measurement is performed using the same cutting tool 10.

[0030] <Structure of First Layer> The thickness of the first layer 3 may be 3.0 μm or more and 15.0 μm or less. This allows the cutting tool 10 to have both better wear resistance and better chipping resistance, making it possible to provide a cutting tool 10 with a longer tool life, particularly in intermittent turning of cast iron. The thickness of the first layer 3 may be 3.2 μm or more and 13.1 μm or less, or 3.5 μm or more and 10.2 μm or less.

[0031] <Orientation Index TC(0 0 12) of First Layer> The orientation index TC(0 0 12) of the first layer 3 may be 3.0 or more. This allows for both better wear resistance and better chipping resistance, making it possible to provide a cutting tool 10 with a longer tool life, particularly in intermittent turning of cast iron. The orientation index TC(0 0 12) of the first layer 3 may be 3.0 or more and 8.0 or less, 3.1 or more and 7.7 or less, or 3.2 or more and 7.4 or less.

[0032] In this specification, the "orientation index TC(0 0 12) of the first layer 3" means the orientation index TC(0 0 12) of the (0 0 12) plane in the first layer 3, among the orientation indexes TC(hkl) defined by the following formula 1:

[0033]

[0034] In Equation 1, I(hkl) represents the X-ray diffraction intensity of the (hkl) reflection plane, and I ０ (hkl) indicates the standard intensity according to ICDD PDF card number 00-010-0173. Furthermore, n in Equation 1 indicates the number of reflections used in the calculation, which is 8 in this embodiment. The (hkl) planes used for reflection are (012), (104), (110), (0 0 12), (113), (024), (116), and (300).

[0035] ICDD (registered trademark) is an abbreviation for International Centre for Diffraction Data, and PDF (registered trademark) is an abbreviation for Powder Diffraction File.

[0036] The orientation index TC (0 0 12) of the first layer 3 of this embodiment can be expressed by the following formula 2.

[0037]

[0038] Therefore, "the orientation index TC(0 0 12) of the first layer 3 is 3.0 or more" means that the value obtained by the above formula 2, which is obtained by substituting TC(0 0 12) into the above formula 1, is 3.0 or more.

[0039] The above-described TC(hkl) can be measured by analysis using an X-ray diffraction device. TC(hkl) can be measured, for example, using Rigaku Corporation's SmartLab (registered trademark) (scan speed: 21.7° / min, step: 0.01°, scan range: 15-140°) under the following conditions. In this embodiment, the results of TC(hkl) measurement using an X-ray diffraction device are referred to as "XRD results." (Conditions) Characteristic X-rays: Cu-Kα Tube voltage: 45 kV Tube current: 200 mA Filter: Multilayer mirror Optical system: Focusing method X-ray diffraction method: θ-2θ method When using an X-ray diffraction device, X-rays are irradiated onto the rake face of a cutting tool. Since the rake face is usually uneven, while the flank face is flat, it is preferable to irradiate the X-rays onto the flank face to eliminate external disturbances. In particular, X-rays are irradiated onto a portion of the flank extending over a range of approximately 2 to 4 mm from the cutting edge ridge. This increases the reproducibility of the results. In this embodiment, the value of the orientation index TC(hkl) of the first layer 3 on the flank of the substrate is the same as the value of TC(hkl) of the first layer 3 on the rake face of the substrate. In this embodiment, it was confirmed that similar results could be obtained even if multiple measurement locations were arbitrarily selected on the same sample and the above measurements were performed on each measurement location.

[0040] The orientation index TC (0 0 12) of the first layer 3 is determined by the H ２ The S content [vol %] can be adjusted appropriately to fall within a desired range.

[0041] <Second Layer> <Composition of Second Layer> The second layer 4 is made of TiCN. Here, "made of TiCN" means that the second layer 4 may contain inevitable impurities in addition to TiCN, as long as the effects of the present disclosure are exhibited. Examples of the inevitable impurities include chlorine atoms (Cl). The total content of the inevitable impurities in the second layer 4 may be greater than 0% by mass or less than 3% by mass.

[0042] The fact that the second layer 4 is made of TiCN is measured by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The content of inevitable impurities in the second layer 4 is measured by secondary ion mass spectrometry (SIMS). It has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected, as long as the measurement is performed using the same cutting tool 10.

[0043] <Structure of Second Layer> The thickness of the second layer 4 is 0.5 μm or more and less than 2.0 μm. This can improve the "wear resistance" of the cutting tool 10. The thickness of the second layer 4 may be 0.6 μm or more and 1.8 μm or less, or 0.7 μm or more and 1.7 μm or less.

[0044] <Residual Stress of Second Layer> The residual stress X of the second layer 4 is −2.0 GPa or more and −0.5 GPa or less. This can improve the “chipping resistance” of the cutting tool 10. The residual stress X of the second layer 4 may be −1.9 GPa or more and −0.6 GPa or less, or may be −1.8 GPa or more and −0.9 GPa or less.

[0045] "Residual stress" refers to a type of internal stress (intrinsic strain) present within a layer. Residual stress can be broadly divided into compressive residual stress and tensile residual stress. Compressive residual stress refers to residual stress expressed as a "-" (negative) numerical value (expressed in units of "GPa" in this specification). For example, "compressive residual stress of 10 GPa" can be understood as a residual stress of -10 GPa. Therefore, the concept of a large compressive residual stress indicates that the absolute value of the numerical value is large, and the concept of a small compressive residual stress indicates that the absolute value of the numerical value is small. Tensile residual stress refers to residual stress expressed as a "+" (positive) numerical value (expressed in units of "GPa" in this specification). For example, "tensile residual stress of 10 GPa" can be understood as a residual stress of 10 GPa. Therefore, the concept of a large tensile residual stress indicates that the numerical value is large, and the concept of a small tensile residual stress indicates that the numerical value is small.

[0046] The residual stress X of the second layer 4 can be determined by measuring the second layer 4 using an X-ray residual stress device with the sin2ψ method (see pages 54-66 of "X-Ray Stress Measurement Method" (published by Yokendo Co., Ltd., Japan Society for Materials Science, 1981). The temperature during the measurement is room temperature (20°C). It has also been confirmed that, as long as the measurement is performed using the same cutting tool 10, there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0047] <Third Layer> <Composition of Third Layer> The third layer 5 is made of TiCN. Here, "made of TiCN" means that the third layer 5 may contain inevitable impurities in addition to TiCN, as long as the effects of the present disclosure are exhibited. Examples of the inevitable impurities include chlorine atoms (Cl). The total content of the inevitable impurities in the third layer 5 may be greater than 0% by mass or less than 3% by mass.

[0048] The fact that the third layer 5 is made of TiCN is measured by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The content of inevitable impurities in the third layer 5 is measured by secondary ion mass spectrometry (SIMS). It has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected, as long as the measurement is performed using the same cutting tool 10.

[0049] <Structure of Third Layer> The thickness of the third layer 5 may be 2 μm or more and 12 μm or less. This allows for both better chipping resistance and better wear resistance, making it possible to provide a cutting tool with a longer tool life, particularly in intermittent turning of cast iron. The thickness of the third layer 5 may be 4 μm or more and 10 μm or less, or 5 μm or more and 7 μm or less.

[0050] <Residual Stress of Third Layer> The residual stress Y of the third layer 5 may be -1.0 GPa or more and 1.0 GPa or less. This can impart better wear resistance and better chipping resistance to the cutting tool 10, thereby providing a cutting tool with a longer tool life, particularly in intermittent turning of cast iron. The residual stress Y of the third layer 5 may be -1.0 GPa or more and 0.5 GPa or less, or -1.0 GPa or more and 0.1 GPa or less.

[0051] The residual stress Y in the third layer 5 can be determined by a method similar to the method for measuring the residual stress X in the second layer 4, except that the measurement is performed on the third layer 5. It has been confirmed that, as long as the measurement is performed using the same cutting tool 10, there is no variation in the measurement results even if the measurement location is arbitrarily selected.

[0052] <Fourth Layer> <Composition of Fourth Layer> The fourth layer 6 is made of TiN. Here, "made of TiN" means that the fourth layer 6 may contain inevitable impurities in addition to TiN, as long as the effects of the present disclosure are exhibited. Examples of the inevitable impurities include chlorine atoms (Cl). The total content of the inevitable impurities in the fourth layer 6 may be greater than 0 mass% or less than 3 mass%.

[0053] The fact that the fourth layer 6 is made of TiN is measured by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The content of inevitable impurities in the fourth layer 6 is measured by secondary ion mass spectrometry (SIMS). It has been confirmed that there is no variation in the measurement results even if the measurement location is arbitrarily selected, as long as the measurement is performed using the same cutting tool 10.

[0054] <Structure of Fourth Layer> The thickness of the fourth layer 6 may be 0.1 μm or more and 0.5 μm or less. This allows for both better chipping resistance and better wear resistance, making it possible to provide a cutting tool with a longer tool life, particularly in intermittent turning of cast iron. The thickness of the fourth layer 6 may be 0.2 μm or more and 0.4 μm or less.

[0055] <Other Layers> Examples of other layers include an underlayer (not shown), an intermediate layer (not shown), and a surface layer (not shown). The underlayer is a layer disposed between the substrate 1 and the third layer 5 when the third layer is present, and is a layer disposed between the substrate 1 and the first layer 3 when the third layer is not present. The surface layer is a layer located on the surface of the coating 2. The intermediate layer is a layer disposed between the third layer 5 and the first layer 3, between the first layer 3 and the second layer 4, or between the second layer 4 and the fourth layer 6. The intermediate layer is a thin adhesive layer such as TiCNO. Therefore, the intermediate layer does not affect the stress distribution.

[0056] [Embodiment 2: Method for manufacturing a cutting tool] A method for manufacturing a cutting tool of this embodiment will be described with reference to Fig. 4. Fig. 4 is a schematic cross-sectional view of an example of a CVD apparatus used in manufacturing the cutting tool of this embodiment.

[0057] The method for manufacturing a cutting tool of this embodiment is the same as the method for manufacturing a cutting tool as described in embodiment 1, and includes: a first step of preparing a substrate; a second step of forming a coating on the substrate; and a third step of blasting the coating to obtain a cutting tool. The second step includes, in this order, a second step A of forming a first layer by a CVD method and a second step B of forming a second layer by a CVD method. The second step may further include a second step C of forming a third layer by a CVD method before the second step A. The second step may further include a second step D of forming a fourth layer by a CVD method after the second step B. Details of each step are described below.

[0058] First Step In the first step, a substrate is prepared. The substrate described in the first embodiment can be used.

[0059] For example, when a cemented carbide is used as the substrate, a commercially available substrate may be used, or it may be manufactured by a general powder metallurgy method. When manufactured by a general powder metallurgy method, for example, WC powder and Co powder are mixed using a ball mill or the like to obtain a mixed powder. The mixed powder is then dried and molded into a predetermined shape to obtain a compact. The compact is then sintered to obtain a WC-Co cemented carbide (sintered body). Next, the sintered body is subjected to a predetermined cutting edge processing such as honing, thereby producing a substrate made of a WC-Co cemented carbide. Any substrate other than those described above can also be prepared as long as it is a conventionally known substrate of this type.

[0060] <<Second Step>> In the second step, a coating is formed on the substrate to obtain a cutting tool. The coating is formed using, for example, a CVD apparatus as shown in FIG. 4 . The CVD apparatus 30 includes a plurality of substrate setting jigs 31 for holding the substrate 1 and a heat-resistant alloy steel reaction vessel 32 that encases the substrate setting jigs 31. A temperature control device 33 is provided around the reaction vessel 32 to control the temperature inside the reaction vessel 32. The reaction vessel 32 is provided with a gas introduction pipe 35 having a gas introduction port 34. The gas introduction pipe 35 extends vertically within the internal space of the reaction vessel 32 in which the substrate setting jigs 31 are placed, and is rotatable about the vertical axis. The gas introduction pipe 35 is also provided with a plurality of ejection holes (through holes 36) for ejecting gas into the reaction vessel 32. Using this CVD apparatus 30, the third, first, second, and fourth layers that constitute the coating can be formed as follows.

[0061] When the coating film includes the "other layer" described in embodiment 1, the "other layer" can be formed by a conventionally known method.

[0062] <Step 2C: Step of forming the third layer by CVD method> In step 2C, the first layer is formed by CVD method. More specifically, first, the substrate 1 is placed in the substrate setting jig 31, and while the temperature and pressure in the reaction vessel 32 are controlled within predetermined ranges, a source gas for the first layer is introduced into the reaction vessel 32 from the gas introduction pipe 35. In this way, the third layer is formed on the substrate 1.

[0063] The source gas for the third layer is TiCl ４ , C.H. ３ C.N., C.O., N. ２ , HCl, and H ２ A mixture of the following gases is used.

[0064] TiCl in mixed gas ４ The content of CH in the mixed gas may be 8.0% by volume or more and 9.0% by volume or less. ３ The CN content in the mixed gas may be 0.2% by volume or more and 1.0% by volume or less. The CO content in the mixed gas may be 1.3% by volume or more and 2.0% by volume or less. ２ The content of HCl in the mixed gas may be 8.0% by volume or more and 12.0% by volume or less. The content of HCl in the mixed gas may be 1.0% by volume or more and 3.0% by volume or less.

[0065] The temperature inside the reaction vessel 32 may be controlled to be 800° C. or higher and 850° C. or lower, and the pressure inside the reaction vessel 32 may be controlled to be 100 hPa or higher and 120 hPa or lower. Note that the gas introduction pipe 35 may be rotated when introducing the gas.

[0066] In the above manufacturing method, the state of the third layer can be changed by controlling the conditions of the CVD method, for example, by adjusting the film formation time, the thickness of the third layer can be controlled.

[0067] <Step 2A: Step of Forming First Layer by CVD Method> In Step 2A, the first layer is formed by CVD method. More specifically, when Step 2D is performed, the first cutting tool precursor having the third layer formed on the substrate is placed in the substrate setting jig 31, and a source gas for the first layer is introduced into the reaction vessel 32 from the gas inlet pipe 35 while controlling the temperature and pressure within the reaction vessel 32 within a predetermined range. This forms the first layer on the third layer. Alternatively, when Step 2D is not performed, the substrate 1 is placed in the substrate setting jig 31, and a source gas for the first layer is introduced into the reaction vessel 32 from the gas inlet pipe 35 while controlling the temperature and pressure within the reaction vessel 32 within a predetermined range. This forms the first layer on the substrate.

[0068] The source gas for the first layer is AlCl３ , CO ２ , H ２ S, and H ２ A mixture of the following gases is used.

[0069] AlCl in mixed gas ３ The content of CO in the mixed gas may be 2.0% by volume or more and 2.5% by volume or less. ２ The content of H in the mixed gas may be 2.5% by volume or more and 3.5% by volume or less. ２ The content of S may be 0.5% by volume or more and 1.0% by volume or less.

[0070] The temperature inside the reaction vessel 32 may be controlled to be 980° C. or higher and 1015° C. or lower, and the pressure inside the reaction vessel 32 may be controlled to be 60 hPa or higher and 75 hPa or lower. Note that the gas introduction pipe 35 may be rotated when introducing the gas.

[0071] In the above manufacturing method, the state of the first layer can be changed by controlling the conditions of the CVD method, for example, by adjusting the film formation time, the thickness of the first layer can be controlled.

[0072] <Step 2B: Step of forming second layer by CVD method> In step 2B, the second layer is formed by CVD method. More specifically, first, the second cutting tool precursor having the first layer formed on the substrate is placed in substrate setting jig 31, and while the temperature and pressure in reaction vessel 32 are controlled within predetermined ranges, a source gas for the second layer is introduced into reaction vessel 32 through gas inlet pipe 35. In this way, the second layer is formed on the first layer.

[0073] The source gas for the second layer is TiCl ４ , C.H. ３ C.N., C.O., N. ２ , HCl, and H ２ A mixture of the following gases is used.

[0074] TiCl in mixed gas ４ The content of CH in the mixed gas may be 8.0% by volume or more and 9.0% by volume or less. ３The CN content in the mixed gas may be 0.2% by volume or more and 0.8% by volume or less. The CO content in the mixed gas may be 1.3% by volume or more and 2.0% by volume or less. ２ The content of HCl in the mixed gas may be 8.0% by volume or more and 12.0% by volume or less. The content of HCl in the mixed gas may be 0.5% by volume or more and 2.0% by volume or less.

[0075] The temperature inside the reaction vessel 32 is controlled to be 850° C. or higher and 950° C. or lower, and the pressure inside the reaction vessel 32 is controlled to be 100 hPa or higher and 110 hPa or lower. When introducing the gas, the gas introduction pipe 35 may be rotated.

[0076] In the above manufacturing method, the state of the second layer can be changed by controlling the conditions of the CVD method, for example, by adjusting the film formation time, the thickness of the second layer can be controlled.

[0077] <Step 2D: Step of forming fourth layer by CVD method> In step 2D, the fourth layer is formed by CVD method. More specifically, first, the third cutting tool precursor having the second layer formed on the first layer is placed in a substrate setting jig 31, and a source gas for the fourth layer is introduced into the reaction vessel 32 through the gas inlet pipe 35 while controlling the temperature and pressure within a predetermined range within the reaction vessel 32. In this way, the fourth layer is formed on the second layer.

[0078] The source gas for the fourth layer is TiCl ４ , N ２ , HCl, and H ２ A mixture of the following gases is used.

[0079] TiCl in mixed gas ４ The content of N in the mixed gas may be 3% by volume or more and 7% by volume or less. ２ The content of HCl in the mixed gas may be 20% by volume or more and 30% by volume or less. The content of HCl in the mixed gas may be 5% by volume or more and 10% by volume or less.

[0080] The temperature inside the reaction vessel 32 may be controlled to be 800° C. or higher and 1000° C. or lower, and the pressure inside the reaction vessel 32 may be controlled to be 100 hPa or higher and 110 hPa or lower. Note that the gas introduction pipe 35 may be rotated when introducing the gas.

[0081] In the above manufacturing method, the state of the fourth layer can be changed by controlling the conditions of the CVD method. For example, the thickness of the fourth layer can be controlled by adjusting the film formation time.

[0082] <Step 3: Blasting the Coating to Obtain a Cutting Tool> In step 3, the coating is blasted to obtain a cutting tool. Here, "blasting" refers to a process in which a large number of small spheres (media) made of steel or non-ferrous metal (e.g., ceramics) are collided (projected) at high speed against the surface of the coating, such as the rake face, to change various properties of the surface, such as residual stress.

[0083] The types of media include, for example, ceramics, zirconia, alumina, and the like.

[0084] The average particle size of the media is more than 15 μm and not more than 30 μm.

[0085] The density of the projected media is 100 g / min or more and 350 g / min or less.

[0086] The distance between the projection unit that projects the media and the surface of the coating (hereinafter also referred to as "projection distance") is 20 mm or more and less than 30 mm.

[0087] The projection angle of the media is 45° to the surface of the coating.

[0088] The pressure applied to the medium when projecting (hereinafter also referred to as "projection pressure") is 0.10 MPa or more and 0.50 MPa or less.

[0089] The blasting treatment time is 20 seconds or more and 50 seconds or less.

[0090] The above-mentioned conditions for the blasting treatment can be adjusted appropriately in accordance with the structure of the coating.

[0091] <Other Steps> In the manufacturing method according to this embodiment, in addition to the steps described above, additional steps may be appropriately performed as long as the effects of this embodiment are not impaired.

[0092] <Features of the manufacturing method of the cutting tool according to the present embodiment> The cutting tool obtained by the manufacturing method described above is a cutting tool including a substrate and a coating disposed on the substrate, the coating including a first layer located on the substrate and a second layer located on the first layer, and the first layer is made of α-Al ２ O ３ The second layer is made of TiCN, the thickness of the second layer is 0.5 μm or more and less than 2.0 μm, and the residual stress X of the second layer is −2.0 GPa or more and −0.5 GPa or less. The reason for this is presumed to be as follows.

[0093] The cutting tool manufacturing method of this embodiment is characterized in that the second step includes steps 2A and 2B, and in step 2B, the film formation time is adjusted so that the thickness of the second layer is 0.5 μm or more and less than 2.0 μm, and in step 2B, the temperature inside the reaction vessel 32 is controlled to be 850° C. or more and 950° C. or less, and the pressure inside the reaction vessel 32 is controlled to be 100 hPa or more and 110 hPa or less, and in step 3, the average particle size of the media is more than 15 μm and 30 μm or less, the concentration of the projected media is 100 g / min or more and 350 g / min or less, the projection distance is 20 mm or more and less than 30 mm, the projection angle of the media is 45° with respect to the surface of the coating, the projection pressure is 0.10 MPa or more and 0.50 MPa or less, and the blasting treatment time is 20 seconds or more and 50 seconds or less. This makes it possible to suppress wear of the second layer caused by the blasting treatment and to effectively impart compressive residual stress to the second layer. This was newly discovered by the present inventors as a result of extensive research.

[0094] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0095] <<Preparation of Cutting Tools>> Cutting tools according to Samples 1 to 22 and 101 to 107 were prepared as follows.

[0096] <First Step> As a substrate, a cemented carbide indexable cutting tip (shape: SEET13T3AGSN-G, manufactured by Sumitomo Electric Hardmetal Corporation) having a composition consisting of Co (6 mass%) and WC (balance) (but containing unavoidable impurities) was prepared.

[0097] <Second Step> For each of Samples 19 to 22, 106, and 107, a third layer was formed on the substrate by CVD under the following conditions so that the composition of the third layer was as shown in Tables 5 and 6 (Step 2C). The deposition time was adjusted appropriately so that the third layer had the thickness shown in Tables 5 and 6. (Conditions for Step 2C) TiCl in the mixed gas ４ Content of CH in mixed gas: 8.0 to 9.0% by volume ３ CN content: 0.2 to 1.0% by volume CO content in the mixed gas: 1.3 to 2.0% by volume N content in the mixed gas ２ Content of HCl in the mixed gas: 1.0 to 3.0 vol% Content of H in the mixed gas: 8.0 to 12.0 vol% ２ Content: Remaining Temperature: 800-850°C Pressure: 100-120hPa

[0098] Next, for each of Samples 19 to 22, Sample 106, and Sample 107, a first layer was formed on the third layer by CVD under the following conditions so that the composition of the first layer was as shown in Tables 3 and 4 (Step 2A). Furthermore, for each of Samples 1 to 18 and Samples 101 to 105, a first layer was formed on the substrate by CVD under the following conditions so that the composition of the first layer was as shown in Tables 5 and 6 (Step 2A). The deposition time was appropriately adjusted so that the first layer had a thickness as shown in Tables 5 and 6. The H content in the mixed gas was adjusted so that the orientation index TC (0 0 12) of the first layer was as shown in Tables 5 and 6. ２ The content of S was appropriately adjusted within the following range: (Conditions of Step 2A) AlCl in the mixed gas ３ Content of CO in the mixed gas: 2.0 to 2.5% by volume ２ Content of: 2.5 to 3.5% by volume H in the mixed gas ２S content: 0.5 to 1.0% by volume H in the mixed gas ２ Content: Remaining Temperature: 980-1015°C Pressure: 60-75hPa

[0099] Next, for each of Samples 1 to 22, 102 to 104, 106, and 107, a second layer was formed on the first layer by CVD under the following conditions so that the composition of the second layer would be as shown in Tables 5 and 6 (Step 2B). The deposition time was adjusted appropriately so that the third layer would have the thickness shown in Tables 5 and 6. (Conditions for Step 2B) TiCl in the mixed gas ４ Content of CH in mixed gas: 8.0 to 9.0% by volume ３ CN content: 0.2 to 0.8% by volume CO content in the mixed gas: 1.3 to 2.0% by volume N content in the mixed gas ２ Content of HCl in the mixed gas: 0.5 to 2.0% by volume. Content of H in the mixed gas: 8.0 to 12.0% by volume. ２ Content of: remainder Temperature: as described in Tables 1 and 2 Pressure: as described in Tables 1 and 2

[0100] For Sample 105, a second layer was formed on the first layer by CVD under the following conditions (Step 2B) so that the composition of the second layer was as shown in Table 6. The deposition time was adjusted appropriately so that the second layer had the thickness shown in Table 6. (Conditions for Step 2B) AlCl in the mixed gas ３ Content of NH in the mixed gas: 6.0% by volume ３ Content of: 1.5% by volume H in the mixed gas ２ Content of: remainder Temperature: as shown in Table 2 Pressure: as shown in Table 2

[0101] Note that for sample 101, step 2B was not performed.

[0102] As described above, a coating was formed on the substrate for each of Samples 1 to 22 and Samples 101 to 107.

[0103] <Third Step> The surface of the coating was subjected to blasting under the conditions shown in Tables 3 and 4.

[0104] By the above procedure, cutting tools according to Samples 1 to 22 and 101 to 107 were produced.

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111] <Evaluation of Cutting Tool Characteristics> <Composition of First Layer> For each sample cutting tool, the composition of the first layer was determined by the method described in Embodiment 1. The results are shown in the "Composition" column of the "First Layer" column in Tables 5 and 6. In Tables 5 and 6, the "Composition" column of the "First Layer" column shows "α-Al ２ O ３ ", the first layer is α-Al ２ O ３ It means that it consists of

[0112] <Orientation index TC(0 0 12) of first layer> For each cutting tool sample, the orientation index TC(0 0 12) of the first layer was determined by the method described in embodiment 1. The obtained results are shown in the "TC(0 0 12)" column of the "First layer" column in Tables 5 and 6.

[0113] <Composition of Second Layer> For each sample cutting tool, the composition of the second layer was determined by the method described in Embodiment 1. The results obtained are shown in the "Composition" column of the "Second Layer" column in Tables 5 and 6. When "TiCN" is listed in the "Composition" column of the "Second Layer" column in Tables 5 and 6, it means that the second layer is made of TiCN.

[0114] <Residual stress X of second layer> For each cutting tool sample, the residual stress X of the second layer was determined by the method described in embodiment 1. The obtained results are shown in the column "X [GPa]" in Tables 5 and 6.

[0115] <Composition of Third Layer> For each sample cutting tool, the composition of the third layer was determined by the method described in Embodiment 1. The results obtained are shown in the "Composition" column of the "Third Layer" column in Tables 5 and 6. When "TiCN" is listed in the "Composition" column of the "Third Layer" column in Tables 5 and 6, it means that the third layer is made of TiCN.

[0116] <Residual stress Y of third layer> For each cutting tool sample, the residual stress Y of the third layer was determined by the method described in embodiment 1. The results are shown in the "Y [GPa]" column of Tables 5 and 6.

[0117] <Coating Thickness> The coating thickness of each sample cutting tool was determined by the method described in Embodiment 1. The results obtained are shown in the "Thickness [μm]" column of the "Coating" column in Tables 5 and 6.

[0118] <Cutting Test> Cutting tests were performed using the cutting tools of each sample under the following cutting conditions. The tool life was measured as the time when the maximum flank wear amount Vbmax [mm] of the ridge line portion of the cutting tool exceeded 0.3 mm due to the combined effects of wear and chipping. The results are shown in the "Tool Life [min]" column of Tables 5 and 6. (Cutting Conditions) Workpiece: FCD450 (grooved round bar) Processing: External turning of grooved round bar Cutting speed: 250 m / min Feed rate: 0.2 mm / rev Cutting fluid: Water-soluble cutting oil The above cutting conditions correspond to those for intermittent turning of cast iron.

[0119] The cutting tools of Samples 1 to 22 correspond to Examples. The cutting tools of Samples 101 to 107 correspond to Comparative Examples. The results in Tables 5 and 6 show that the cutting tools of Samples 1 to 22 have a longer tool life than the cutting tools of Samples 101 to 107, even in the interrupted turning of cast iron.

[0120] From the above, it was found that the cutting tools according to Samples 1 to 22 have a long tool life even in the intermittent turning of cast iron.

[0121] Although the embodiments and examples of the present disclosure have been described above, it is originally intended that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways.

[0122] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the embodiments and examples described above, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

[0123] REFERENCE SIGNS LIST 1 substrate, 2 coating, 3 first layer, 4 second layer, 5 third layer, 6 fourth 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 located on the substrate and a second layer located on the first layer, and the first layer is α-Al ２ O ３ the second layer is made of TiCN, the second layer has a thickness of 0.5 μm or more and less than 2.0 μm, and the second layer has a residual stress X of −2.0 GPa or more and −0.5 GPa or less.

2. The cutting tool according to claim 1, wherein the thickness of the first layer is 3.0 μm or more and 15.0 μm or less.

3. A cutting tool according to claim 1 or 2, wherein the orientation index TC(0 0 12) of the first layer is 3.0 or more.

4. A cutting tool according to any one of claims 1 to 3, wherein the coating further includes a third layer located between the substrate and the first layer, the third layer being made of TiCN, and the residual stress Y of the third layer being -1.0 GPa or more and 1.0 GPa or less.

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