Coated tool, cutting tool, and method for producing cut workpiece

Abstract

This coated tool comprises a base and at least one coating layer positioned on the base. The coating layer contains at least one element selected from among elements of groups 4, 5, and 6 in the periodic table, Al, and Si, and at least one element selected from C and N. The average value of the developed area ratio of the surface of the coating layer is 1.1 or more after heat treatment at a temperature of 1050-1100°C inclusive in an atmosphere.

Description

Methods for manufacturing coated tools, cutting tools, and machined products

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure relate to methods of manufacturing coated tools, cutting tools, and machined workpieces.

[0002] BACKGROUND ART As a tool used in cutting processes such as turning or milling, a coated tool is known in which the surface of a substrate made of cemented carbide, cermet, ceramics, or the like is coated with a coating layer to improve wear resistance and the like.

[0003] For example, a coated tool is known which comprises a substrate and a coating coated on the surface thereof, the coating including an intermediate film coated on the surface of the substrate and an oxide film coated on the surface of the intermediate film. The intermediate film is made of at least one material selected from the group consisting of TiN, TiCN, TiAlN, TiAlZrN, TiAlCrN and AlCrN. The oxide film is made of (Al ０．５ Cr ０．５ ) ２ O ３ , (Al ０．５５ Cr ０．４５ ) ２ O ３ , (Al ０．６ Cr ０．４ ) ２ O ３ , (Al ０．７ Cr ０．３ ) ２ O ３ , (Al ０．８ Cr ０．２ ) ２ O ３ and (Al ０．９ Cr ０．１ ) ２ O ３ It consists of at least one selected from the group consisting of (see, for example, WO 2012 / 018063).

[0004] A coated tool according to one aspect of this embodiment includes a substrate and at least one coating layer located on the substrate, the coating layer containing at least one element selected from the group 4, 5, and 6 elements of the periodic table, Al, and Si, and at least one element selected from C and N, and the average developed area ratio of the surface of the coating layer is 1.1 or greater after heat treatment at a temperature of 1050°C or higher and 1100°C or lower in an air atmosphere.

[0005] Fig. 1 is a perspective view showing an example of a coated tool according to this embodiment. Fig. 2 is a cross-sectional view showing an example of an insert according to this embodiment. Fig. 3 is a front view showing an example of a cutting tool according to this embodiment. Fig. 4A is a schematic view showing one step of a method for manufacturing a machined product according to this embodiment. Fig. 4B is a schematic view showing one step of a method for manufacturing a machined product according to this embodiment. Fig. 4C is a schematic view showing one step of a method for manufacturing a machined product according to this embodiment.

[0006] Hereinafter, modes for carrying out the methods for manufacturing a coated tool, a cutting tool, and a machined product according to the present disclosure (hereinafter referred to as "embodiments") will be described in detail with reference to the drawings. The methods for manufacturing a coated tool, a cutting tool, and a machined product according to the present disclosure are not limited to the embodiments described below. In the following embodiments, the same components are designated by the same reference numerals, and redundant explanations will be omitted.

[0007] BACKGROUND ART As a tool used in cutting processes such as turning or milling, a coated tool is known in which the surface of a substrate made of cemented carbide, cermet, ceramics, or the like is coated with a coating layer to improve wear resistance and the like.

[0008] However, conventional coated tools have poor adhesion resistance, which can result in a shortened tool life.

[0009] As described above, the prior art has room for further improvement in terms of improving welding resistance.

[0010] Therefore, there is a need for a technology that can overcome the above-mentioned problems and improve welding resistance.

[0011] <Coated Tool> Fig. 1 is a perspective view showing an example of a coated tool according to this embodiment. As shown in Fig. 1, the coated tool 1 according to this embodiment has an insert 11.

[0012] (Insert 11) The insert 11 has, for example, a hexahedron shape in which the upper and lower surfaces (surfaces intersecting with the Z axis shown in FIG. 1) are shaped like a substantially parallelogram. The insert 11 according to this embodiment has a lower surface opposite to the upper surface, and has side surfaces between the upper and lower surfaces.

[0013] One corner portion of the insert 11 may function as a cutting edge portion. The cutting edge portion has a first surface (e.g., a part of the top surface) and a second surface (e.g., a part of the side surface) that is connected to the first surface. In this embodiment, the first surface functions as a "rake face," and the second surface functions as a "flank face." A cutting edge is located on at least a part of the ridge where the first surface and the second surface intersect, and the coated tool 1 cuts the workpiece by bringing this cutting edge into contact with the workpiece.

[0014] A through-hole 15 is located in the center of the insert 11, penetrating the insert 11 from top to bottom. The central axis of the through-hole 15 may pass through the center of the upper surface and the center of the lower surface. A screw 75 is inserted into the through-hole 15 to attach the coated tool 1 to a holder 70 (described later) (see FIG. 3).

[0015] 1 is merely an example and does not limit the shape of the coated tool according to the present disclosure. The coated tool according to the present disclosure may have, for example, a rod-shaped body having a rotation axis and extending from a first end to a second end, a cutting edge located at the first end of the body, and a groove extending spirally from the cutting edge toward the second end of the body.

[0016] Fig. 2 is a cross-sectional view showing an example of the insert according to the present embodiment. The cross section shown in Fig. 2 may be a cross section parallel to the central axis of the through hole 15. As shown in Fig. 2, the insert 11 has a base body 2 and at least one coating layer 3.

[0017] (Substrate 2) The substrate 2 is formed of, for example, a cemented carbide. The cemented carbide contains a hard phase containing at least W (tungsten), specifically WC (tungsten carbide). The cemented carbide may contain a binder phase containing at least one iron group element such as Ni (nickel) and Co (cobalt). As an example, the substrate 2 may be a WC-based cemented carbide whose main component is hard particles made of WC. Here, the main component refers to a cemented carbide whose main component is 80 mass % or more of the hard particles made of WC. When the substrate 2 is the above-mentioned cemented carbide, the substrate 2 has better heat resistance.

[0018] The substrate 2 may be a cermet. The cermet contains, for example, Ti (titanium), specifically, TiC (titanium carbide), TiN (titanium nitride), or TiCN (titanium carbonitride). The cermet may also contain at least one iron group element such as Ni and Co.

[0019] The substrate 2 may be a cubic boron nitride sintered body containing cubic boron nitride (cBN) particles. The substrate 2 is not limited to cubic boron nitride (cBN) particles, and may contain particles of hexagonal boron nitride (hBN), rhombohedral boron nitride (rBN), wurtzite boron nitride (wBN), or the like.

[0020] The substrate 2 may be made of ceramic. The ceramic may be, for example, Al ２ O ３ (aluminum oxide) may be contained. ２ O ３ (Aluminum oxide) includes, for example, κ-Al ２ O ３ and α-Al ２ O ３ The ceramic may contain other elements in addition to aluminum oxide. For example, the ceramic may contain, in addition to aluminum oxide, at least one of magnesium (Mg), calcium (Ca), strontium (Sr), silicon (Si), and elements from Groups 3 and 4 of the periodic table.

[0021] (Coating layer 3) The coating layer 3 coats the base body 2 for the purpose of improving, for example, the welding resistance of the base body 2. In the example of Fig. 2, the coating layer 3 coats the entire base body 2. The coating layer 3 is not particularly limited as long as it is located at least on the surface of the base body 2. When the coating layer 3 is located on the surface of the base body 2, the surface of the insert 11 where the coating layer 3 is located has high welding resistance.

[0022] The coating layer 3 contains at least one element selected from the group 4, 5 and 6 elements of the periodic table, aluminum (Al), and silicon (Si), and at least one element selected from the group 10 carbon (C) and nitrogen (N). For example, the coating layer 3 contains Al ａ Ti ｂ Nb ｃ M ｄ , and at least one element selected from C and N. M is at least one element selected from elements in Groups 4, 5, and 6 of the periodic table excluding Ti and niobium (Nb), and Si. a, b, c, and d satisfy the relationships 0.4≦a≦0.65, 0.35≦b≦0.6, 0.01≦c≦0.05, and a+b+c+d=1. As an example, the composition of the coating layer 3 may be (AlTiNbWSi)N. The notation (AlTiNbWSi)N indicates the type of constituent elements and does not indicate that the atomic ratio of the constituent elements is equal. The coating layer 3 does not necessarily need to contain M. For example, the composition of the coating layer 3 may be (AlTiNb)N. The notation (AlTiNb)N indicates the type of constituent elements and does not indicate that the atomic ratio of the constituent elements is equal. The coating layer 3 has high hardness at high temperatures (for example, 1100° C.) and high oxidation resistance.

[0023] The thickness of the coating layer 3 may be 1 μm or more and 7 μm or less. In particular, when the thickness of the coating layer 3 is 1.5 μm or more, the performance of the coated tool 1 is likely to be improved. When the thickness of the coating layer 3 is 3 μm or less, the fracture resistance of the coating layer 3 is likely to be improved. Therefore, when the thickness of the coating layer 3 is 1.5 μm or more and 3 μm or less, the fracture resistance and the like of the coating layer 3 are likely to be improved.

[0024] In this embodiment, at least the coating layer 3 included in the coated tool 1 is subjected to heat treatment in an air atmosphere at a temperature of 1050°C or higher and 1100°C or lower. For example, the coated tool 1 including the coating layer 3 is heated in an air atmosphere to a temperature of 1050°C or higher and 1100°C or lower using a heating device such as an air atmosphere electric furnace. In the heat treatment step of the present disclosure, the coated tool 1 including the coating layer 3 may be heated in an air atmosphere for one hour from the start of heating until the temperature reaches 1050°C. Thereafter, the coated tool 1 may be held at 1050°C for one minute. After holding at 1050°C for one minute, the coated tool 1 may be furnace-cooled for a certain period of time.

[0025] The term "heat treatment" in the present disclosure refers to a heating treatment performed on the coated tool 1 on which the coating layer 3 has been formed by a physical vapor deposition (PVD) method or the like, and is different from, for example, a baking treatment required for manufacturing the coated tool 1. By performing heat treatment on the coated tool 1 before use in cutting, the coated tool 1 may be brought into the same or similar state as the coated tool 1 during or after cutting, and the properties of the coated tool 1 may be evaluated.

[0026] The heat treatment in the present disclosure is performed in an air atmosphere, i.e., an atmosphere containing oxygen, and may cause an oxidation reaction of the coating layer 3. If the heat treatment temperature is 1050°C or higher, an oxidation reaction may occur in the coating layer 3, and therefore the properties of the coating layer 3 of the coated tool 1 can be evaluated under conditions identical to or similar to the conditions of the coated tool 1 during cutting. If the heat treatment temperature is 1100°C or lower, it is possible to reduce the risk of deterioration of the substrate 2 due to the heat treatment. As a result, it is possible to reduce the risk that the coating layer 3 will be affected by deterioration of the substrate 2 due to the heat treatment, and to evaluate the properties of the coating layer 3 of the coated tool 1.

[0027] The average developed area ratio of the surface of the coating layer 3 is 1.1 or greater after heat treatment at a temperature of 1050°C or higher and 1100°C or lower in an air atmosphere. The developed area ratio (Sdr) of the surface of the coating layer 3 is a parameter that represents the ratio of the increase in the surface area of ​​the coating layer 3 in a measurement area relative to the planar area of ​​the measurement area, when any region on the surface of the coating layer 3 is designated as the measurement area. The developed area ratio (Sdr) of the surface is specified as "ISO 25178" by the ISO (International Organization for Standardization). A large developed area ratio of the surface of the coating layer 3 is considered to indicate high surface roughness. The developed area ratio of the surface of the coating layer 3 can be measured, for example, using a non-contact (optical probe) surface profiler. Specifically, the developed area ratio of the surface of the coating layer 3 can be obtained by measuring and analyzing the surface profile of the coating layer 3 in the measurement area using a laser microscope surface profiler. The average value of the developed area ratio on the surface of the coating layer 3 is the average value of the developed area ratios measured in a plurality of measurement regions on the surface of the coating layer 3.

[0028] When the coated tool 1 is used to cut a workpiece, the temperature of the coating layer 3, which is included in the coated tool 1 and comes into contact with the workpiece, rises. If the average developed area ratio of the surface of the coating layer 3 is 1.1 or more after heat treatment, the surface roughness of the coating layer 3 on the coated tool 1 during cutting is considered to be high. In such a case, the cutting resistance of the coating layer 3 during cutting is likely to be reduced. As a result, the adhesion resistance of the coated tool 1 to the workpiece is likely to be improved. In addition, in the above case, the specific surface area of ​​the coating layer 3 after cutting is likely to be increased. As a result, the coating layer 3 is more likely to cool after cutting.

[0029] The average value of the developed area ratio of the surface of the coating layer 3 may be 0.1 or less before the heat treatment. Here, "0.1 or less" includes 0. That is, the average value of the developed area ratio of the surface of the coating layer 3 may be 0. In this case, the developed area ratio of the surface of the coating layer 3 in all measurement regions is 0. A developed area ratio of the surface of the coating layer 3 of 0 means that the surface of the coating layer 3 is flat. If the average value of the developed area ratio of the surface of the coating layer 3 is 0.1 or less before the heat treatment, it is considered that the surface roughness of the coating layer 3 is small before the heat treatment. On the other hand, since the average value of the developed area ratio of the surface of the coating layer 3 is 1.1 or more after the heat treatment, it is considered that the surface roughness of the coating layer 3 is large after the heat treatment. That is, in the above case, the surface roughness of the coating layer 3 increases due to the heat treatment.

[0030] When the average value of the developed area ratio of the surface of the coating layer 3 is 0.1 or less before the heat treatment, the surface roughness of the coating layer 3 is small before the heat treatment. In such a case, it is easier to improve the wear resistance of the coated tool 1 including the substrate 2 and the coating layer 3. When the coated tool 1 is used for cutting a workpiece, the coating layer 3 of the coated tool 1 comes into contact with the workpiece. Because the surface roughness of the coating layer 3 is small before cutting, which corresponds to before the heat treatment, it is easier to reduce the roughness of the surface of the cut workpiece.

[0031] From the above, when the average value of the developed area ratio of the surface of the coating layer 3 is 1.1 or less after heat treatment and the average value of the developed area ratio of the surface of the coating layer 3 is 0.1 or less before heat treatment, the welding resistance is improved under high temperature conditions where welding of the workpiece material is likely to occur, and the wear resistance is likely to be improved under low temperature conditions where welding of the workpiece material is relatively unlikely to occur.

[0032] The average value of the arithmetic mean curvature of the peaks on the surface of the coating layer 3 may be 21,000 / mm or more after heat treatment. The arithmetic mean curvature of the peaks (Spc) on the surface of the coating layer 3 is a parameter that represents the arithmetic mean of the principal curvatures of the peaks present in an arbitrary region on the surface of the coating layer 3 as a measurement region. The arithmetic mean curvature of the peaks (Spc) is specified as "ISO 25178" in the ISO (International Organization for Standardization). The measurement region for the arithmetic mean curvature of the peaks (Spc) may be a region different from the measurement region for the above-mentioned surface developed area ratio (Sdr). When the arithmetic mean curvature of the peaks on the surface of the coating layer 3 is large, it is considered that the sharpness of the multiple peaks present on the surface of the coating layer 3 is large on average. The arithmetic mean curvature of the peaks on the surface of the coating layer 3 can be measured, for example, by using a non-contact (optical probe) surface profilometer. Specifically, the laser microscope surface profilometer is used to measure and analyze the surface shape of the coating layer 3 in a measurement area, thereby obtaining the arithmetic mean curvature of the peaks on the surface of the coating layer 3. The average value of the arithmetic mean curvature of the peaks on the surface of the coating layer 3 is the average value of the arithmetic mean curvatures of the peaks measured in multiple measurement areas on the surface of the coating layer 3.

[0033] When the coated tool 1 is used to cut a workpiece, the temperature of the coating layer 3, which is included in the coated tool 1 and comes into contact with the workpiece, rises. If the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer 3 after heat treatment is 21,000 / mm or more, it is considered that the sharpness of the peaks present on the surface of the coating layer 3 of the coated tool 1 during cutting is high on average. In such a case, it becomes easier to reduce the area of ​​the coating layer 3 that comes into contact with the workpiece. Accordingly, it becomes easier to reduce the cutting resistance of the coating layer 3 during cutting. As a result, it becomes easier to improve the adhesion resistance of the coated tool 1 to the workpiece.

[0034] If the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer 3 after heat treatment is 21,000 / mm or more, the risk of the workpiece being torn off during cutting is likely to be reduced. As a result, the risk of the machined surface of the workpiece becoming cloudy is likely to be reduced. Furthermore, cracks that may occur in the coating layer 3 due to impacts applied to the coating layer 3 during cutting are more easily deflected. Accordingly, crack bridging is more easily induced in the coating layer 3 that receives impacts during cutting. As a result, the toughness of the coating layer 3 during cutting is likely to be improved.

[0035] The average value of the arithmetic mean curvature of the peaks on the surface of the coating layer 3 may be 5000 / mm or less before the heat treatment. If the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer 3 is 5000 / mm or less before the heat treatment, it is considered that the sharpness of the peaks on the surface of the coating layer 3 is small on average before the heat treatment. On the other hand, if the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer 3 is 21000 / mm or more after the heat treatment, it is considered that the sharpness of the peaks on the surface of the coating layer 3 is large on average after the heat treatment. That is, in the above case, the sharpness of the peaks on the surface of the coating layer 3 increases due to the heat treatment.

[0036] If the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer 3 before heat treatment is 5000 / mm or less, the sharpness of the peaks on the surface of the coating layer 3 before heat treatment is small on average. In this case, it is easier to improve the wear resistance of the coated tool 1 including the substrate 2 and the coating layer 3. When the coated tool 1 is used for cutting a workpiece, the coating layer 3 of the coated tool 1 comes into contact with the workpiece. Because the sharpness of the peaks on the surface of the coating layer 3 before cutting, which corresponds to before heat treatment, is small on average, it is easier to reduce surface roughness of the cut workpiece.

[0037] From the above, when the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer 3 is 21,000 / mm or more after heat treatment and the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer 3 is 5,000 / mm or less before heat treatment, the welding resistance is improved under high-temperature conditions where welding of the workpiece material is likely to occur, and the wear resistance is likely to be improved under low-temperature conditions where welding of the workpiece material is relatively unlikely to occur.

[0038] The coating layer 3 may contain Al. When the coating layer 3 contains Al, the coating layer 3 may contain aluminum oxide after the heat treatment due to an oxidation reaction of the coating layer 3 caused by the heat treatment. Aluminum oxide tends to increase the surface roughness of the coating layer 3 and the sharpness of the peaks present on the surface of the coating layer 3. Therefore, after the heat treatment, it becomes easier to achieve an average developed area ratio of the surface of the coating layer 3 of 1.1 or more and an average arithmetic mean curvature of the peaks on the surface of the coating layer 3 of 21,000 / mm or more.

[0039] When the coating layer 3 contains Al, the coating layer 3 may contain aluminum oxide after the heat treatment due to an oxidation reaction of the coating layer 3 caused by the heat treatment. The aluminum oxide contained in the coating layer 3 can reduce the oxidation reaction of the coating layer 3 during the heat treatment. As a result, the oxidation resistance of the coated tool 1 including the coating layer 3 can be easily improved.

[0040] The coating layer 3 may contain Nb. When the coating layer 3 contains Nb, the coating layer 3 may contain niobium oxide due to an oxidation reaction of the coating layer 3 caused by heat treatment. When the coating layer 3 contains niobium oxide, the hardness of the coating layer 3 is likely to be increased. Therefore, the wear resistance of the coated tool 1 including the coating layer 3 is likely to be improved.

[0041] When the coating layer 3 contains Al and Nb, Nb may promote the formation of aluminum oxide in the coating layer 3 during heat treatment. Aluminum oxide tends to increase the surface roughness of the coating layer 3 and the sharpness of the peaks present on the surface of the coating layer 3. Therefore, after heat treatment, it becomes easier to achieve an average developed area ratio of the surface of the coating layer 3 of 1.1 or more and an average arithmetic mean curvature of the peaks on the surface of the coating layer 3 of 21,000 / mm or more.

[0042] When the coating layer 3 contains Al and Nb, Nb may promote the formation of an aluminum oxide film in the coating layer 3 during heat treatment. That is, Nb facilitates the formation of a denser aluminum oxide film in the coating layer 3. This further reduces the oxidation reaction of the coating layer 3 during heat treatment. As a result, the oxidation resistance of the coated tool 1 including the coating layer 3 is further improved.

[0043] The coating layer 3 may contain at least one of W and Si. When the coating layer 3 contains at least one of W and Si, the affinity between the substrate 2 and the coating layer 3 is improved, which makes it easier to improve the adhesion of the coating layer 3 to the substrate 2. Therefore, the wear resistance of the coated tool 1 including the substrate 2 and the coating layer 3 is easily improved.

[0044] The coating layer 3 may contain W, and may contain tungsten oxide due to an oxidation reaction of the coating layer 3 caused by heat treatment. In this case, the heat resistance of the coating layer 3 is easily improved. Therefore, the heat resistance of the coated tool 1 including the coating layer 3 is easily improved.

[0045] When the coating layer 3 contains Al and W, a layer containing aluminum oxide and tungsten oxide is likely to be formed inside the aluminum oxide film in the coating layer 3. In such a case, it is easy to improve the adhesion of the aluminum oxide film to the inside of the coating layer 3. As a result, it is easy to further improve the oxidation resistance of the coated tool 1 including the coating layer 3. Such a layer makes it easy to improve the heat resistance of the coating layer 3. Therefore, it is easy to improve the heat resistance of the coated tool 1 including the coating layer 3.

[0046] The coating layer 3 may contain Al and Ti. The Al content in the coating layer 3 may be greater than the Ti content in the coating layer 3.

[0047] In this case, partial substitution of Ti by Al is promoted in the Ti-containing crystals. Accordingly, the hardness of the coating layer 3 is likely to be increased. Therefore, the wear resistance of the coated tool 1 including the coating layer 3 is likely to be improved. In the oxidation reaction of the coating layer 3 caused by the heat treatment, the generation of aluminum oxide in the coating layer 3 may be further promoted. As a result, the oxidation reaction of the coating layer 3 during the heat treatment is likely to be further reduced. As a result, the oxidation resistance of the coated tool 1 including the coating layer 3 is likely to be further improved.

[0048] <Method for manufacturing a coated tool> Next, an example of a method for manufacturing a coated tool according to the present embodiment will be described. The method for manufacturing a coated tool according to the present embodiment is not limited to the following method.

[0049] The coated tool 1 is manufactured by forming at least one coating layer 3 on a substrate 2. The coating layer 3 may be formed by, for example, a physical vapor deposition (PVD) method. For example, when the coating layer 3 is formed by physical vapor deposition while the substrate 2 is held on the inner peripheral surface of the through hole 15, the coating layer 3 is easily formed so as to cover the entire surface of the substrate 2 except for the inner peripheral surface of the through hole 15.

[0050] Examples of physical vapor deposition methods include ion plating methods such as arc ion plating (AIP) and sputtering. The arc ion plating method uses arc discharge in a vacuum atmosphere to evaporate target elements, and nitrogen (N ２ ) gas, etc. to form a film of the target element or a nitride of the target element.

[0051] For example, when the coating layer 3 is formed on the substrate 2 by arc ion plating, the coated tool 1 can be easily produced by the following method.

[0052] As an example, a target of each of Al, Ti, Nb, and M elements, a target of composite elements, or a sintered target is prepared, where M is at least one element selected from the elements of Groups 4, 5, and 6 of the periodic table excluding Ti and Nb, and Si.

[0053] Next, the target, which is the source of the element, is evaporated and ionized by arc discharge or glow discharge. The ionized element is, for example, nitrogen (N ２ ) gas and is deposited on the surface of the substrate 2. This makes it possible to form a coating layer 3 on the substrate 2.

[0054] Here, in order to achieve an average developed area ratio of the surface of the coating layer 3 of 1.1 or more and an average arithmetic mean curvature of the peaks on the surface of the coating layer 3 of 21,000 / mm or more after heat treatment at a temperature of 1,050°C or more and 1,100°C or less in an atmospheric atmosphere, it is possible to increase, for example, the plasma density and plasma energy of the ionized elements and gradually increase the bias voltage applied to the substrate 2. Examples of methods for increasing the plasma density and plasma energy of the ionized elements include: - setting the temperature of the substrate 2 to a temperature in the range of 500°C to 600°C, - setting the gas pressure of nitrogen gas or the like to a pressure in the range of 2 Pa to 8 Pa, - setting the distance between the target and the substrate 2 (T-S distance) to a distance in the range of 50 mm to 200 mm, - forming a magnetic field linearly in the target direction, - setting the distance between the cathodes to a distance in the range of 100 mm to 200 mm, - setting the magnetic flux density of the magnet to a magnetic flux density in the range of 20 mT to 80 mT, - setting the current of the arc discharge or the like to a range of 130 A to 160 A, etc. Examples of methods for gradually increasing the bias voltage applied to the substrate 2 include gradually increasing the bias voltage applied to the substrate 2 within a range of -50 V to -120 V.

[0055] <Cutting Tool> Next, a cutting tool including the above-described coated tool 1 will be described with reference to Fig. 3. Fig. 3 is a front view showing an example of a cutting tool according to this embodiment.

[0056] As shown in FIG. 3 , the cutting tool 100 according to this embodiment includes the coated tool 1 and a holder 70 for fixing the coated tool 1 .

[0057] The holder 70 is a rod-shaped member extending from a first end (the upper end in FIG. 3 ) to a second end (the lower end in FIG. 3 ). The holder 70 is made of, for example, steel or cast iron. Of these materials, steel may be used, as it has high toughness.

[0058] The holder 70 has a pocket 73 at the end on the first end side. The pocket 73 is a portion where the coated tool 1 is attached, and has a seating surface that intersects with the rotation direction of the workpiece and a constraint side surface that is inclined relative to the seating surface. The seating surface is provided with a screw hole into which a screw 75, which will be described later, is threaded.

[0059] The coated tool 1 is positioned in a pocket 73 of the holder 70 and attached to the holder 70 by a screw 75. That is, the screw 75 is inserted into the through hole 15 of the coated tool 1, and the tip of the screw 75 is inserted into a threaded hole formed in the seating surface of the pocket 73 to screw the threaded portions together. In this way, the coated tool 1 is attached to the holder 70 so that the cutting edge portion protrudes outward from the holder 70.

[0060] In this embodiment, a cutting tool 100 used for so-called turning is illustrated. Examples of turning include internal diameter machining, external diameter machining, and grooving. The cutting tool is not limited to that used for turning. For example, the coated tool 1 may be used as a cutting tool used for milling. Examples of cutting tools used for milling include milling cutters such as flat milling cutters, face milling cutters, side milling cutters, and groove milling cutters, and end mills such as single-blade end mills, multi-blade end mills, tapered-blade end mills, and ball end mills.

[0061] Turning is performed using a lathe. Turning includes the steps of rotating a workpiece, bringing a fixed cutting tool 100 into contact with the rotating workpiece to remove the surface of the rotating workpiece, and removing the cutting tool 100 from the workpiece. By machining the workpiece into a desired rotationally symmetric shape in this manner, it becomes easier to manufacture a rotationally symmetric machined product. Turning is performed using a milling machine. Turning includes the steps of rotating the cutting tool 100, bringing the rotating cutting tool 100 into contact with the fixed workpiece to remove the fixed workpiece, and removing the cutting tool 100 from the workpiece. By machining the workpiece into a desired shape in this manner, it becomes easier to manufacture a machined product.

[0062] In this embodiment, an example is shown in which the shapes of the upper and lower surfaces of the cutting tool 100 are parallelograms. The shapes of the upper and lower surfaces of the cutting tool 100 may be rhombic, square, etc. The shapes of the upper and lower surfaces of the cutting tool 100 may be triangular, pentagonal, hexagonal, etc. The shape of the cutting tool 100 may be a positive type or a negative type. A positive type is a type in which the side surfaces are inclined with respect to a central axis passing through the centers of the upper and lower surfaces of the cutting tool 100, and a negative type is a type in which the side surfaces are parallel to the central axis.

[0063] <Method for manufacturing a machined product> Next, a method for manufacturing a machined product according to this embodiment will be described with reference to Figures 4A, 4B, and 4C. Figures 4A, 4B, and 4C are schematic views showing one step of the method for manufacturing a machined product according to this embodiment.

[0064] The machined product 200 is produced by cutting a workpiece 201. 4A, 4B, and 4C illustrate turning using a lathe as an example of cutting. The manufacturing method for the machined product 200 in this embodiment includes the steps of: rotating the workpiece 201 (step A); bringing the workpiece 201 into contact with the cutting tool 100 (step B); and moving the cutting tool 100 relatively away from the workpiece 201 (step C).

[0065] More specifically, first, as shown in Fig. 4A, the workpiece 201 is rotated around the axis O1, and the cutting tool 100 is brought relatively close to the workpiece 201. Next, as shown in Fig. 4B, the cutting edge of the coated tool 1 is brought into contact with the workpiece 201 to cut the workpiece 201. Next, as shown in Fig. 4C, the cutting tool 100 is moved relatively away from the workpiece 201.

[0066] In Fig. 4A, the axis O1 is fixed and the workpiece 201 is rotated while the cutting tool 100 is moved in the Y1 direction to approach the workpiece 201. In Fig. 4B, the cutting edge of the coated tool 1 is brought into contact with the rotating workpiece 201 to cut the workpiece 201. In Fig. 4C, the cutting tool 100 is moved in the Y2 direction while the workpiece 201 is rotated to move away from the workpiece 201.

[0067] In the cutting process in the manufacturing method of the machined product according to this embodiment, the cutting tool 100 is moved in each step to bring the cutting tool 100 into contact with the workpiece 201 or to move the cutting tool 100 away from the workpiece 201. However, the manufacturing method of the machined product is not limited to this mode, as a matter of course.

[0068] For example, in step A, the workpiece 201 may be brought closer to the cutting tool 100. Similarly, in step C, the workpiece 201 may be moved away from the cutting tool 100. To continue the cutting process, the workpiece 201 may be kept rotating, and the step of bringing the cutting edge of the cutting tool 100 into contact with different locations on the workpiece 201 may be repeated.

[0069] When performing milling instead of turning, the cutting tool may be rotated around a rotation axis in step A. Furthermore, in step B, the workpiece 201 may be cut by bringing the cutting edge of the rotating coated tool 1 into contact with the workpiece 201. Furthermore, in step C, the cutting tool may be moved away from the workpiece 201. The milling may be performed using a milling machine.

[0070] Typical examples of the material of the workpiece 201 include carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals.

[0071] Examples of the present disclosure will be specifically described below, but the present disclosure is not limited to the examples shown below.

[0072] (Example) First, a coating layer was formed on a substrate by arc ion plating to produce a coated tool including the substrate and the coating layer located thereon. Here, a WC-based cemented carbide was used as the substrate. The coating layer was formed on the substrate under the following conditions. Table 1 shows the arc ion plating conditions for forming the coating layer on the substrate. Substrate temperature: 500°C to 600°C. Target composition: See Table 1. Gas pressure: 2 to 8 Pa. Distance between target and substrate (T-S distance): 50 to 200 mm (See Table 1). Bias voltage: Gradually increased within a range of -30 to -75 V (See Table 1). Magnetic field distribution: Cathode distance: 100 to 200 mm (See Table 1). Magnet magnetic force: 20 to 80 mT (See Table 1). The deposition time was adjusted so that the thickness of the coating layer formed on the substrate was 2 μm. The average composition of the coating layer formed on the substrate was the composition shown in Table 1. In this manner, coated tools of Samples No. 1 to No. 9 shown in Table 1 were prepared.

[0073] Next, for the coated tools of Samples No. 1 to No. 9, a laser microscope surface profiler (Keyence Corporation: VK-X1050) was used to measure the developed area ratio in four measurement regions on the surface of the coating layer before heat treatment. The measurement conditions are shown below. Laser microscope surface profile measurement conditions: Device model number: Shape analysis laser microscope Model number: VK-X1050 Magnification: 2400 Field of view: 16.8 × 12.6 μm Measurement optical system: Pinhole confocal optical system Height measurement display resolution: 5 nm Width measurement display resolution: 0.01 μm Measurement quality: 2048 × 1536 Frame rate: 4 Hz Measurement laser light source: Red laser 661 nm Output: 1.0 mW Class: Class 2 laser product (IEC 60825-1, JIS C6802) Next, the average value of the developed area ratio in the four measurement regions on the surface of the coating layer before heat treatment was calculated.

[0074] The average developed area ratios of the coating layer surface before heat treatment are shown in Table 2. It was confirmed that the average developed area ratios of the coating layer surface were 0.1 or less for all of the coated tools of Samples 1 to 6 according to the examples before heat treatment. On the other hand, it was confirmed that the average developed area ratios of the coating layer surface were greater than 0.1 for all of the coated tools of Samples 7 to 9 according to the comparative examples before heat treatment.

[0075] Next, for the coated tools of Samples 1 to 9, the arithmetic mean curvature of the peaks in four measurement regions on the surface of the coating layer before heat treatment was measured using a laser microscope surface profiler (Keyence Corporation: VK-X1050). The measurement conditions were the same as those for measuring the developed area ratio described above. Next, the average value of the arithmetic mean curvature of the peaks in the four measurement regions on the surface of the coating layer before heat treatment was calculated. The average value of the arithmetic mean curvature of the peaks on the surface of the coating layer before heat treatment is shown in Table 2. It was confirmed that the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer was 5000 / mm or less before heat treatment for all of the coated tools of Samples 1 to 6 according to the examples. On the other hand, it was confirmed that the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer before heat treatment for all of the coated tools of Samples 7 to 9 according to the comparative examples was greater than 5000 / mm before heat treatment.

[0076] Next, for the coated tools of Samples 1 to 9, the types of elements contained in the coating layers before heat treatment were identified using a scanning transmission electron microscope (Hitachi High-Tech HD-2700) and an elemental analyzer (Horiba EMAX Evolution). It was confirmed that the elements contained in the composition shown in Table 1 were contained in the coating layers of all of the coated tools of Samples 1 to 9 before heat treatment. The Al and Ti contents in the coating layers of Samples 1 to 9 before heat treatment were determined. It was confirmed that the Al content in the coating layers of Samples 1, 3, and 4 according to the examples and Samples 7 to 9 according to the comparative examples was greater than the Ti content in the coating layers before heat treatment. On the other hand, for Samples 2, 5, and 6 according to the examples, the Al content in the coating layers was greater than the Ti content in the coating layers before heat treatment. It was confirmed that in all of the coated tools No. 6, the Al content in the coating layer was equal to or less than the Ti content in the coating layer before the heat treatment.

[0077] Next, for the coated tools of Samples No. 1 to No. 9, the coated tools including the coating layers were heated in an air atmosphere using an air atmosphere electric furnace (NHK-170 manufactured by Nitto Kagaku Co., Ltd.). Specifically, the coated tools were heated to 1,050°C at a heating rate of 1 hour in an air atmosphere, held at 1,050°C for 1 minute, and then furnace-cooled. In this manner, the coating layers included in the coated tools were heat-treated.

[0078] Next, for the coated tools of Samples 1 to 9, the developed area ratios of four measurement regions on the surface of the coating layer after the heat treatment were measured using a laser microscope surface profiler (Keyence Corporation: VK-X1050). The average value of the developed area ratios of the four measurement regions on the surface of the coating layer after the heat treatment was then calculated. Table 2 shows the average developed area ratios of the surface of the coating layer after the heat treatment. It was confirmed that the average developed area ratios of the surface of the coating layer were 1.1 or more after the heat treatment for all of the coated tools of Samples 1 to 6 according to the examples. On the other hand, it was confirmed that the average developed area ratios of the surface of the coating layer were less than 1.1 after the heat treatment for all of the coated tools of Samples 7 to 9 according to the comparative examples.

[0079] Next, for the coated tools of Samples 1 to 9, the arithmetic mean curvature of the peaks in four measurement regions on the surface of the coating layer after the heat treatment was measured using a laser microscope surface profilometer (Keyence Corporation: VK-X1050). Next, the average value of the arithmetic mean curvature of the peaks in the four measurement regions on the surface of the coating layer after the heat treatment was calculated. The average value of the arithmetic mean curvature of the peaks on the surface of the coating layer after the heat treatment is shown in Table 2. It was confirmed that the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer for all of the coated tools of Samples 1 to 4 according to the example was 21,000 / mm or more after the heat treatment. On the other hand, it was confirmed that the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer for all of the coated tools of Samples 5 and 6 according to the example and the coated tools of Samples 7 to 9 according to the comparative example was less than 21,000 / mm after the heat treatment.

[0080] Next, for the coated tools of Samples 1 to 9, the types of elements contained in the coating layers after heat treatment were identified using a scanning transmission electron microscope (Hitachi High-Tech HD-2700) and an elemental analyzer (Horiba EMAX Evolution). It was confirmed that the elements contained in the composition shown in Table 1 were contained in the coating layers after heat treatment for all of the coated tools of Samples 1 to 9. The Al and Ti contents in the coating layers after heat treatment were determined for the coated tools of Samples 1 to 9. It was confirmed that the Al content in the coating layers was greater than the Ti content in the coating layers for all of the coated tools of Samples 1, 3, and 4 according to the examples and Samples 7 to 9 according to the comparative examples. On the other hand, for Samples 2, 5, and 6 according to the examples, the Al content in the coating layers was greater than the Ti content in the coating layers after heat treatment. It was confirmed that in all of the coated tools No. 6, the Al content in the coating layer after the heat treatment was equal to or less than the Ti content in the coating layer.

[0081] Next, cutting tests were conducted on the coated tools of the example and the comparative example. The cutting test conditions are shown below. Cutting conditions Workpiece material: SUS304 Cutting speed: Vc = 80 m / min (low speed) and 130 m / min (high speed) Feed: f = 0.08 mm / rev Depth of cut: ae = 1.5 mm Cutting state: Wet Cutting tool shape: GBA43R300-030GM Evaluation method: Turning was performed for 120 minutes under the above conditions, and the wear width of the front flank after cutting was measured.

[0082] Table 3 shows the results of the cutting test for each of the coated tools of Samples No. 1 to No. 9. More specifically, Table 3 shows the wear width (mm) of the leading flank of the coated tool when cutting at low or high speed under the above cutting conditions.

[0083] As shown in Table 3, the wear width of the front flank of the coated tools of Samples 1 to 6 according to the examples was smaller than the wear width of the front flank of the coated tools of Samples 7 to 9 according to the comparative examples, both in low-speed cutting and high-speed cutting. Thus, it was confirmed that the performance of the coated tools of Samples 1 to 6 according to the examples was improved compared to the coated tools of Samples 7 to 9 according to the comparative examples. It is believed that the performance of the coated tools was improved when the average value of the developed area ratio of the surface of the coating layer was 1.1 or more after heat treatment. It is believed that the performance of the coated tools was improved when the average value of the developed area ratio of the surface of the coating layer was 0.1 or less before heat treatment. It is believed that the performance of the coated tools was improved when the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer was 5000 / mm or less before heat treatment.

[0084] The wear width of the front flank of the coated tools of Examples No. 1 to No. 4 was smaller than the wear width of the front flank of the coated tools of Examples No. 5 and No. 6, in both low-speed and high-speed cutting. Thus, it was confirmed that the performance of the coated tools of Examples No. 1 to No. 4 was improved compared to the coated tools of Examples No. 5 and No. 6. It is believed that the performance of the coated tools was further improved because the average value of the arithmetic mean curvature of the peaks on the surface of the coating layer was 21,000 / mm or more after heat treatment.

[0085] The wear width of the front flank of the coated tools of Examples No. 1 and No. 2 was smaller than the wear width of the front flank of the coated tools of Examples No. 3 to No. 6, both in low-speed cutting and high-speed cutting. Thus, it was confirmed that the performance of the coated tools of Examples No. 1 and No. 2 was improved compared to the coated tools of Examples No. 3 to No. 6. It is believed that the performance of the coated tools was further improved by the inclusion of at least one of W and Si in the coating layer.

[0086] The wear width of the front flank of the coated tool of Example Sample No. 1 was smaller than the wear width of the front flank of the coated tools of Example Samples No. 2 to No. 6, both in low-speed cutting and high-speed cutting. Thus, it was confirmed that the performance of the coated tool of Example Sample No. 1 was improved compared to the coated tools of Example Samples No. 2 to No. 6. It is believed that the performance of the coated tool was further improved by the inclusion of W in the coating layer.

[0087] The present technology can be configured as follows: (1) A coated tool comprising a substrate and at least one coating layer located on the substrate, wherein the coating layer contains at least one element selected from among elements of Groups 4, 5, and 6 of the periodic table, Al, and Si, and at least one element selected from among C and N, and wherein the average developed area ratio of the surface of the coating layer is 1.1 or more after heat treatment at a temperature of 1050°C to 1100°C in an air atmosphere. (2) The coated tool according to (1), wherein the average developed area ratio of the surface of the coating layer is 0.1 or less before the heat treatment. (3) The coated tool according to (1) or (2), wherein the average arithmetic mean curvature of peaks on the surface of the coating layer is 21000 / mm or more after the heat treatment. (4) The coated tool according to any one of (1) to (3), wherein the average value of the arithmetic mean curvature of peaks on the surface of the coating layer is 5000 / mm or less before the heat treatment. (5) The coated tool according to any one of (1) to (4), wherein the coating layer contains Al. (6) The coated tool according to any one of (1) to (5), wherein the coating layer contains Nb. (7) The coated tool according to any one of (1) to (6), wherein the coating layer contains at least one of W and Si. (8) The coated tool according to any one of (1) to (7), wherein the coating layer contains W. (9) The coated tool according to any one of (1) to (8), wherein the coating layer contains Al and Ti, and wherein the Al content in the coating layer is greater than the Ti content in the coating layer. (10) A cutting tool comprising: a rod-shaped holder having a pocket at an end thereof; and the coated tool according to any one of (1) to (9) positioned in the pocket. (11) A method for manufacturing a machined product comprising the steps of: rotating a workpiece or the cutting tool according to (10), bringing the workpiece and the cutting tool into contact with each other, and moving the cutting tool relatively away from the workpiece.

[0088] Further advantages and / or modifications may readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0089] REFERENCE SIGNS LIST 1 coated tool 11 insert 15 through hole 2 substrate 3 coating layer 70 holder 73 pocket 75 screw 100 cutting tool

Claims

1. A coated tool comprising: a substrate; and at least one coating layer located on the substrate, wherein the coating layer contains at least one element selected from the group 4, 5, and 6 elements of the periodic table, Al, and Si, and at least one element selected from the group C and N, and wherein the average developed area ratio of the surface of the coating layer is 1.1 or greater after heat treatment in an air atmosphere at a temperature of 1050°C or higher and 1100°C or lower.

2. The coated tool according to claim 1, wherein the average developed area ratio of the surface of the coating layer is 0.1 or less before the heat treatment.

3. The coated tool according to claim 1 or 2, wherein the average value of the arithmetic mean curvature of peaks on the surface of said coating layer after said heat treatment is 21,000 / mm or more.

4. A coated tool according to any one of claims 1 to 3, wherein the average value of the arithmetic mean curvature of peaks on the surface of the coating layer before the heat treatment is 5000 / mm or less.

5. The coated tool according to any one of claims 1 to 4, wherein the coating layer contains Al.

6. The coated tool according to any one of claims 1 to 5, wherein the coating layer contains Nb.

7. The coated tool according to any one of claims 1 to 6, wherein the coating layer contains at least one of W and Si.

8. The coated tool according to any one of claims 1 to 7, wherein the coating layer contains W.

9. The coated tool according to any one of claims 1 to 8, wherein the coating layer contains Al and Ti, and the Al content in the coating layer is greater than the Ti content in the coating layer.

10. A cutting tool comprising: a rod-shaped holder having a pocket at an end thereof; and a coated tool according to any one of claims 1 to 9 positioned in said pocket.

11. A method for manufacturing a machined product, comprising the steps of: rotating a workpiece or the cutting tool described in claim 10; bringing the workpiece and the cutting tool into contact; and moving the cutting tool relatively away from the workpiece.

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