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

Abstract

This coated tool comprises a base material, and a coating layer positioned on the base material. The coating layer includes a laminate in which a plurality of first layers and a plurality of second layers are alternately laminated. Each of the plurality of first layers and the plurality of second layers contains aluminum and titanium. At least the plurality of second layers in the coating layer furthermore contain boron. The boron content of the plurality of second layers is higher than the boron content of the plurality of first layers.

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 Coated tools are known as cutting tools used in cutting processes such as turning and milling, and have improved wear resistance and the like by coating the surface of a substrate made of cemented carbide, cermet, ceramics, or the like with a coating layer.

[0003] For example, the present invention is a method for manufacturing a substrate made of a cubic boron nitride sintered body and a coating film provided on the substrate, the coating film including an MAlN layer, in which M in the MAlN layer represents a metal element including titanium, chromium, or both, and the MAlN layer is a cubic M ｘ Al １－ｘ Contains N crystal grains, M ｘ Al １－ｘ A cutting tool is known in which the atomic ratio x of the metal element M to N is 0.3 or more and 0.7 or less (see, for example, WO 2021 / 024736).

[0004] A coated tool according to one aspect of the embodiment includes a substrate and a coating layer positioned on the substrate, the coating layer including a stack of alternating first layers and second layers, each of the first layers and second layers containing aluminum and titanium, at least the second layers in the coating layer further containing boron, and the boron content in the second layers is higher than the boron content in the first layers.

[0005] FIG. 1 is a perspective view showing an example of a coated tool according to an embodiment. FIG. 2 is a cross-sectional view showing an example of an insert according to an embodiment. FIG. 3 is a cross-sectional view showing an example of a configuration of a coating layer according to an embodiment. FIG. 4 is a cross-sectional view showing another example of a configuration of a coating layer according to an embodiment. FIG. 5 is a front view showing an example of a cutting tool according to an embodiment. FIG. 6 is a schematic view showing one step of a method for manufacturing a machined product according to an embodiment. FIG. 7 is a schematic view showing one step of a method for manufacturing a machined product according to an embodiment. FIG. 8 is a schematic view showing one step of a method for manufacturing a machined product according to an 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] For example, in order to improve the efficiency of cutting processing using a cutting tool, it is required to improve the durability of the coated tool. Thus, the conventional techniques have room for further improvement in terms of improving durability.

[0008] Therefore, there is a need for a technology that can overcome the above-mentioned problems and improve durability.

[0009] <Coated Tool> Fig. 1 is a perspective view showing an example of a coated tool according to an embodiment. As shown in Fig. 1, the coated tool 1 according to the embodiment has an insert 11.

[0010] (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 the embodiment has a lower surface opposite to the upper surface, and has side surfaces between the upper and lower surfaces.

[0011] 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 the 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 applying this cutting edge to the workpiece.

[0012] 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. 5 ).

[0013] 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.

[0014] Fig. 2 is a cross-sectional view showing an example of an insert according to the 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.

[0015] (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.

[0016] 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.

[0017] 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.

[0018] The substrate 2 may be made of ceramic. The ceramic may be, for example, Al ２ O ３ (aluminum oxide) may be contained. ２ O３ (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.

[0019] (Coating layer 3) The coating layer 3 coats the base body 2, for example, to improve the wear resistance of the base body 2. In the example of Fig. 2, the coating layer 3 coats the entire base body 2. The arrangement of the coating layer 3 on the base body 2 is not particularly limited as long as the coating layer 3 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 wear resistance.

[0020] <Configuration of Covering Layer 3> Here, an example of the configuration of the covering layer according to the embodiment will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view showing an example of the configuration of the covering layer according to the embodiment.

[0021] 3, the coated tool 1 according to the embodiment includes a substrate 2 and a coating layer 3 located on the substrate 2. The coating layer 3 includes a stack 31 in which a plurality of first layers 31 a and a plurality of second layers 31 b are alternately stacked.

[0022] Each of the plurality of first layers 31a and the plurality of second layers 31b contains aluminum (Al) and titanium (Ti).

[0023] At least the second layers 31b in the coating layer 3 further contain boron (B). The first layers 31a in the coating layer 3 may not contain boron. Both the first layers 31a and the second layers 31b may further contain boron.

[0024] The boron content in the plurality of second layers 31b is higher than the boron content in the plurality of first layers 31a. The boron content in the plurality of first layers 31a is, for example, an average value of the boron contents (atomic %) in the plurality of first layers 31a measured at a plurality of positions in the thickness direction of the coating layer 3. The boron content in the plurality of second layers 31b is, for example, an average value of the boron contents (atomic %) in the plurality of second layers 31b measured at a plurality of positions in the thickness direction of the coating layer 3. The boron content in the plurality of first layers 31a may be 0.

[0025] The first layers 31a are made of, for example, Al ａ Ti ｂ B ｃ M ｄ and at least one element selected from carbon, nitrogen, and oxygen. M is at least one metal selected from Groups 4, 5, and 6 (excluding Cr and W) of the periodic table of elements and Si. a, b, c, and d are 10≦a≦50, 40≦b≦90, and 0≦c≦5, and a+b+c+d=100. The multiple first layers 31a do not necessarily need to contain B. The multiple first layers 31a do not necessarily need to contain M. As an example, the composition of the multiple first layers 31a may be AlTiN. The notation AlTiN indicates the type of constituent elements and does not indicate that the atomic ratio of the constituent elements is equal.

[0026] The plurality of second layers 31b are made of, for example, Al ｅ Ti ｆ B ｇ M ｈand at least one element selected from carbon, nitrogen, and oxygen. M is at least one metal selected from Groups 4, 5, and 6 (excluding Cr and W) of the periodic table of elements and Si. e, f, g, and h are 10≦e≦50, 40≦f≦89.9, and 0.1≦g≦10, and e+f+g+h=100. The second layers 31b do not necessarily need to contain M. As an example, the second layers 31b may have a composition of AlTiBN. The notation AlTiBN indicates the type of constituent elements and does not indicate that the atomic ratio of the constituent elements is equal.

[0027] The thickness of the laminate 31 may be, for example, 1 μm or more and 5 μm or less. The average thickness of the first layers 31 a may be, for example, 100 nm or more and 700 nm or less. The average thickness of the second layers 31 b may be, for example, 100 nm or more and 700 nm or less.

[0028] According to the embodiment, it is possible to improve the durability of the coated tool 1. Therefore, when cutting is performed using a cutting tool including the coated tool 1 according to the embodiment, it is possible to improve the processing efficiency of the cutting tool. For example, when the cutting speed of the cutting tool is increased, a high cutting load is applied to the cutting tool. According to the embodiment, it is possible to perform good cutting even in cutting where a high cutting load is applied to the cutting tool.

[0029] Among coating layers having multiple layers each containing aluminum and titanium, coating layers with varying aluminum and titanium contents have been known. Specifically, coating layers in which layers with a relatively high aluminum content and layers with a relatively high titanium content are alternately stacked have been known. In such coating layers, the layer with a relatively high titanium content has excellent toughness, and the layer with a relatively high aluminum content has excellent wear resistance. However, there are limits to achieving both excellent toughness and wear resistance simply by varying the aluminum and titanium contents.

[0030] According to the embodiment, the coating layer 3 contains boron, and the boron content of the second layers 31b is higher than the boron content of the first layers 31a. By varying the boron content of the first layers 31a and the second layers 31b in this manner, it is possible to achieve both superior toughness and wear resistance compared to a case where the aluminum and titanium contents are simply varied.

[0031] The first layer 31a has a relatively low boron content, which ensures the excellent toughness of the AlTiN coating. Furthermore, the second layer 31b has a relatively high boron content, which facilitates the refinement of AlTiN crystal grains by boron, thereby improving hardness. Therefore, it is possible to achieve both excellent toughness and wear resistance.

[0032] The titanium content in the first layers 31a may be higher than the aluminum content in the first layers 31a, and the titanium content in the second layers 31b may be higher than the aluminum content in the second layers 31b. The titanium content in the first layers 31a is, for example, an average value of the titanium contents (atomic %) in the first layers 31a measured at multiple positions in the thickness direction of the coating layer 3. The titanium content in the second layers 31b is, for example, an average value of the titanium contents (atomic %) in the second layers 31b measured at multiple positions in the thickness direction of the coating layer 3. In this case, it is possible to more easily improve the durability of the coated tool 1.

[0033] As described above, when the titanium content is higher than the aluminum content in both the first layers 31a and the second layers 31b, the toughness of the laminate 31 as a whole is likely to be improved. This is because both the first layers 31a and the second layers 31b have a relatively high titanium content and are therefore excellent in toughness. A relatively high titanium content can lead to a decrease in wear resistance. However, the relatively high boron content in the second layers 31b reduces the decrease in wear resistance in at least the second layers 31b. This allows the laminate 31 as a whole to achieve both excellent toughness and wear resistance, making it easier to improve the durability of the coated tool 1.

[0034] The titanium content of the first layers 31 a may be higher than the titanium content of the second layers 31 b, which makes it possible to more easily improve the durability of the coated tool 1.

[0035] The aluminum content in the first layers 31 a may be lower than the aluminum content in the second layers 31 b. The aluminum content in the first layers 31 a is, for example, an average value of the aluminum contents (atomic %) in the first layers 31 a measured at multiple positions in the thickness direction of the coating layer 3. The aluminum content in the second layers 31 b is, for example, an average value of the aluminum contents (atomic %) in the second layers 31 b measured at multiple positions in the thickness direction of the coating layer 3. In this case, it is possible to more easily improve the durability of the coated tool 1.

[0036] The ratio of the sum of the titanium contents in the first layers 31a and the second layers 31b to the sum of the aluminum contents in the first layers 31a and the second layers 31b may be 1.8 to 2.3, which further improves the durability of the coated tool 1.

[0037] The presence and content of aluminum, titanium, and boron in the first layers 31 a and the second layers 31 b can be determined by, for example, analysis using an energy dispersive X-ray spectrometer (EDS) attached to a scanning transmission electron microscope (STEM). For example, if no boron is detected in the first layers 31 a when the analysis using the EDS attached to the STEM is performed as described above, the boron content in the first layers 31 a is determined to be 0.

[0038] The presence and content of aluminum, titanium, and boron in the first layers 31 a may be constant or may vary. For example, when the laminate 31 is divided into three equal regions, an inner region, a central region, and an outer region, along the stacking direction, the aluminum content of the first layers 31 a located in the central region may be higher than the aluminum content of the first layers 31 a located in the inner region.

[0039] When the aluminum content of the first layer 31a located in the central region is relatively high, the hardness of the first layer 31a located in the central region is relatively increased. Therefore, the rigidity of the laminate 31 as a whole is likely to be increased. When the aluminum content of the first layer 31a located in the inner region is relatively low, the toughness of the first layer 31a located in the inner region is relatively increased. Therefore, the laminate 31 is less likely to peel off from a portion adjacent to the inside of the laminate 31 (such as the base 2).

[0040] The aluminum content of the first layer 31 a located in the central region may be higher than the aluminum content of the first layer 31 a located in the outer region. If the aluminum content of the first layer 31 a located in the outer region is relatively low, the toughness of the first layer 31 a located in the outer region is relatively increased. Therefore, sudden fracture is less likely to occur during initial wear during cutting.

[0041] The presence and content of aluminum, titanium, and boron in the plurality of second layers 31b may be constant or may vary. For example, when the laminate 31 is divided into three equal regions along the stacking direction, namely, an inner region, a central region, and an outer region, the aluminum content of the second layer 31b located in the central region may be greater than the aluminum content of the second layer 31b located in the inner region. As with the first layer 31a, this tends to increase the rigidity of the entire laminate 31, and also makes the laminate 31 less likely to peel from the region adjacent to the inside of the laminate 31 (such as the base 2).

[0042] The aluminum content of the second layer 31b located in the central region may be greater than the aluminum content of the second layer 31b located in the outer region. If the aluminum content of the second layer 31b located in the outer region is relatively small, sudden fracture is less likely to occur during initial wear in cutting, as in the case of the first layer 31a.

[0043] Next, another example of the configuration of the coating layer according to the embodiment will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view showing another example of the configuration of the coating layer according to the embodiment.

[0044] As shown in Fig. 4, the coating layer 3 further includes an underlayer 32 located between the substrate 2 and the laminate 31, and the underlayer 32 has a thermal expansion coefficient between that of the substrate 2 and that of the laminate 31. The substrate 2 and the laminate 31 in the coating layer 3 shown in Fig. 4 are similar to the substrate 2 and the laminate 31 in the coating layer 3 shown in Fig. 3, respectively.

[0045] The underlayer 32 located between the substrate 2 and the laminate 31 has a thermal expansion coefficient between that of the substrate 2 and that of the laminate 31. This makes it possible for the underlayer 32 to reduce the difference in thermal expansion between the substrate 2 and the laminate 31 in response to temperature changes in the coated tool 1. This makes it possible to improve the adhesion between the substrate 2 and the laminate 31.

[0046] The substrate 2 may be a cubic boron nitride sintered body, and the underlayer 32 may contain aluminum chromium nitride.

[0047] The underlayer 32 is, for example, Al ｉ Cr ｊ M ｋ and nitrogen. M is at least one metal selected from Groups 4, 5, and 6 (excluding W) of the periodic table of elements and Si. i and j are 50≦i≦90 and 10≦j≦50, and i+j+k=100. The underlayer 32 does not necessarily need to contain M. As an example, the composition of the underlayer 32 may be AlCrN. The notation AlCrN indicates the type of constituent elements and does not indicate that the atomic ratio of the constituent elements is equal.

[0048] The thickness of the underlayer 32 may be, for example, not less than 0.01 μm and not more than 0.5 μm.

[0049] The underlayer 32 containing aluminum chromium nitride tends to have a thermal expansion coefficient between that of the base 2, which is a cubic boron nitride sintered body, and that of the laminate 31. The underlayer 32 containing aluminum chromium nitride tends to have a high chemical affinity for the base 2, which is a cubic boron nitride sintered body. This makes it possible to improve the adhesion between the base 2, which is a cubic boron nitride sintered body, and the laminate 31.

[0050] The presence and content of aluminum, chromium, and nitrogen in the underlayer 32 can be determined by analysis using, for example, an energy dispersive X-ray spectrometer (EDS) attached to a scanning transmission electron microscope (STEM).

[0051] <Method for manufacturing the coated tool 1> Next, an example of a method for manufacturing the coated tool 1 according to this embodiment will be described. The method for manufacturing the coated tool 1 according to this embodiment is not limited to the following manufacturing method.

[0052] The coated tool 1 is manufactured by forming a 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 using physical vapor deposition while the substrate 2 is held on the inner circumferential surface of the through hole 15, the coating layer 3 can be formed so as to cover the entire surface of the substrate 2 except for the inner circumferential surface of the through hole 15.

[0053] 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 a target metal, and nitrogen (N ２ ) gas, etc. to form a film of metal or metal nitride.

[0054] For example, when the coating layer 3 is formed on the substrate 2 by arc ion plating, the coated tool 1 can be produced by the following method.

[0055] As an example, a target A such as a metal target of Al, Cr, or M, a composite alloy target, or a sintered target is prepared, where M is at least one metal selected from Groups 4, 5, and 6 (excluding W) of the periodic table of elements, and Si.

[0056] Next, the target A, which is a metal source, is evaporated and ionized by arc discharge or glow discharge. The ionized metal is then ionized with nitrogen (N ２ ) gas and is deposited on the surface of the substrate 2. As a result, the underlayer 32 can be formed on the substrate 2.

[0057] As an example, a target B such as a metal target of Al, Ti, or M, a composite alloy target, or a sintered target is prepared, where M is at least one metal selected from Groups 4, 5, and 6 (excluding Cr and W) and Si in the periodic table.

[0058] Next, the target B, which is a metal source, is evaporated and ionized by arc discharge or glow discharge. The ionized metal is then evaporated with nitrogen (N ２ ) gas and is deposited on the surface of the substrate 2 or on the surface of the underlayer 32 formed on the substrate 2. This allows the first layer 31 a to be formed on the substrate 2 or on the underlayer 32 formed on the substrate 2.

[0059] As an example, a target C such as a metal target of Al, Ti, B, or M, a composite alloy target, or a sintered target is prepared, where M is at least one metal selected from Groups 4, 5, and 6 (excluding Cr and W) and Si in the periodic table of elements.

[0060] Next, the target C, which is a metal source, is evaporated and ionized by arc discharge or glow discharge. The ionized metal is then evaporated with nitrogen (N ２ ) gas and is deposited on the surface of the substrate 2 or on the surface of the underlayer 32 formed on the substrate 2. This allows the second layer 31b to be formed on the substrate 2 or on the underlayer 32 formed on the substrate 2.

[0061] Next, the formation of the first layers 31 a and the second layers 31 b is alternately repeated using the above-described target B and the above-described target C. This allows the formation of a stack 31 in which a plurality of first layers 31 a and a plurality of second layers 31 b are alternately stacked on the base 2 or the underlayer 32 formed on the base 2.

[0062] Here, the conditions for the arc ion plating method include, for example, the following: temperature inside the furnace: 300°C to 800°C; gas pressure of nitrogen gas or the like: 2 Pa to 5 Pa; distance between targets A, B, and C and the substrate 2: 100 mm to 800 mm; bias voltage applied to the substrate 2: 20 V to 100 V.

[0063] <Cutting Tool> Next, the configuration of a cutting tool including the coated tool 1 described above will be described with reference to Fig. 5 . Fig. 5 is a front view showing an example of a cutting tool according to an embodiment. The cutting tool is used for cutting a workpiece, thereby producing a machined product. Examples of cutting include turning and milling.

[0064] As shown in FIG. 5 , a cutting tool 100 according to the embodiment includes the coated tool 1 and a holder 70 for fixing the coated tool 1 .

[0065] The holder 70 is a rod-shaped member extending from its front end (upper end in FIG. 5 ) to its rear end (lower end in FIG. 5 ). The holder 70 is made of, for example, steel or cast iron. Of these materials, steel, which has high toughness, may also be used.

[0066] The holder 70 has a pocket 73 located at the end on the tip 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.

[0067] 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.

[0068] In the embodiment, a cutting tool 100 used for so-called turning is exemplified. Examples of turning include internal diameter machining, external diameter machining, grooving, and cut-off. The cutting tool is not limited to a tool 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.

[0069] <Method for manufacturing machined product> Next, a method for manufacturing a machined product according to an embodiment will be described with reference to the drawings. Figures 6, 7, and 8 are schematic diagrams showing steps of the method for manufacturing a machined product according to an embodiment.

[0070] The machined product 200 is produced by cutting a workpiece 201. Turning performed using a lathe is illustrated in Figures 6 to 8 as an example of cutting. The manufacturing method for the machined product 200 in this embodiment includes the following steps: (1) a step of rotating the workpiece 201; (2) a step of bringing the workpiece 201 into contact with the cutting tool 100; and (3) a step of moving the cutting tool 100 relatively away from the workpiece 201.

[0071] More specifically, first, as shown in Fig. 6, 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. 7, the cutting edge of the insert 11 is brought into contact with the workpiece 201 to cut the workpiece 201. Then, as shown in Fig. 8, the cutting tool 100 is moved relatively away from the workpiece 201.

[0072] In this embodiment, the axis O1 is fixed and the cutting tool 100 is moved in the Y1 direction while the workpiece 201 is being rotated, thereby bringing the cutting tool 100 closer to the workpiece 201. In Fig. 7, the cutting edge of the insert 11 is brought into contact with the rotating workpiece 201 to cut the workpiece 201. In Fig. 8, the cutting tool 100 is moved in the Y2 direction while the workpiece 201 is being rotated, thereby moving the cutting tool 100 away from the workpiece 201.

[0073] In the cutting process in the manufacturing method of the 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, but of course, this is not limited to this form.

[0074] For example, in step (1), the workpiece 201 may be brought closer to the cutting tool 100. Similarly, in step (3), 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.

[0075] When performing milling instead of turning, the cutting tool may be rotated around a rotation axis in step (1). Furthermore, in step (2), the workpiece 201 may be cut by bringing the cutting edge of the rotating insert 11 into contact with the workpiece 201. Furthermore, in step (3), the cutting tool may be moved away from the workpiece 201. Milling may be performed using a milling machine.

[0076] Typical examples of the material of the workpiece 201 include carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metals.

[0077] Examples of the present disclosure will be specifically described below, but the present disclosure is not limited to the examples shown below.

[0078] (Example) A coating layer including an underlayer and a laminate of alternating first layers and second layers was formed on a substrate, which was a cubic boron nitride sintered body, by arc ion plating.

[0079] First, an underlayer was formed on the substrate. The target composition for forming the underlayer was Al ７０ Cr ３０ The average composition of the underlayer formed on the substrate was Al ７０ Cr ３０ The thickness of the underlayer was 300 nm.

[0080] Next, a laminate was formed by alternately stacking multiple first layers and multiple second layers on the underlayer. Four coated tools including a substrate, an underlayer located on the substrate, and a laminate located on the underlayer were fabricated as coated tools according to the example. Here, the four coated tools are referred to as Sample No. 1, Sample No. 2, Sample No. 3, and Sample No. 4. Table 1 shows the compositions of the targets used to form the multiple first layers and multiple second layers included in the laminate (first layer target composition, second layer target composition) and the average compositions of the multiple first layers and multiple second layers included in the laminate (first layer average composition, second layer average composition) for each coated tool.

[0081]

[0082] In each coated tool, the first layers each had an average thickness of 400 nm, the second layers each had an average thickness of 400 nm, and the stack thickness was 3500 nm.

[0083] As a comparative example, a conventional coated tool (Competitor's Product A) was prepared.

[0084] Next, cutting tests were carried out on the coated tools according to the examples and the comparative examples under the following conditions.

[0085] <Cutting test conditions> Workpiece: SCM415H Cutting speed (Vc): 200 m / min Feed (f): 0.1 mm / rev Depth of cut (ap): 0.2 mm Cutting condition: Wet Tool used: CNGA120408S01225ME Cutting time: 11.5 minutes

[0086] The width of nose wear in the thickness direction of the coating layer was measured for each coated tool according to the examples. Table 2 shows the ratio of the Ti content to the Al content in the laminate (Ti / Al) and the width of nose wear (nose wear (mm)) for each coated tool according to the examples. Here, the value of Ti / Al was calculated as the ratio of the sum of the titanium content in the first layers and the titanium content in the second layers to the sum of the aluminum content in the first layers and the aluminum content in the second layers.

[0087]

[0088] Similarly, the width of the nose wear in the coated tool according to the comparative example was 0.1 mm.

[0089] As described above, it was confirmed that the width of nose wear of each of the coated tools according to the Examples was smaller than the width of nose wear of the coated tool according to the Comparative Examples at a certain cutting time, and that the durability of each of the coated tools according to the Examples was higher than that of the coated tool according to the Comparative Examples.

[0090] It was confirmed that the width of nose wear of the coated tools of Samples No. 1 and No. 2, which had Ti / Al values ​​of 1.8 or more and 2.3 or less, was smaller than the width of nose wear of the coated tools of Samples No. 3 and No. 4, which had Ti / Al values ​​of less than 1.8 or more than 2.3. In other words, it was confirmed that the durability of each coated tool having a Ti / Al value of 1.8 or more and 2.3 or less was higher than the durability of coated tools having a Ti / Al value of less than 1.8 or more than 2.3.

[0091] The present technology may have the following configurations: (1) A coated tool comprising: a substrate; and a coating layer located on the substrate, wherein the coating layer includes a stack of alternating first layers and second layers, wherein each of the first layers and the second layers contains aluminum and titanium, and at least the second layers in the coating layer further contain boron, and wherein the boron content in the second layers is higher than the boron content in the first layers. (2) The coated tool according to (1), wherein the titanium content in the first layers is higher than the aluminum content in the first layers, and the titanium content in the second layers is higher than the aluminum content in the second layers. (3) The coated tool according to (1) or (2), wherein the titanium content in the first layers is higher than the titanium content in the second layers. (4) The coated tool according to any one of (1) to (3), wherein the aluminum content in the plurality of first layers is lower than the aluminum content in the plurality of second layers. (5) The coated tool according to any one of (1) to (4), wherein a ratio of the sum of the titanium content in the plurality of first layers and the titanium content in the plurality of second layers to the sum of the aluminum content in the plurality of first layers and the aluminum content in the plurality of second layers is 1.8 or more and 2.3 or less. (6) The coated tool according to any one of (1) to (5), wherein the coating layer further includes an underlayer located between the substrate and the stack, and the underlayer has a thermal expansion coefficient between the thermal expansion coefficient of the substrate and the thermal expansion coefficient of the stack. (7) The coated tool according to (6), wherein the substrate is a cubic boron nitride sintered body, and the underlayer contains aluminum chromium nitride. (8) A cutting tool comprising: a holder extending from a front end to a rear end and having a pocket located on the front end side; and the coated tool according to any one of (1) to (7) located in the pocket.(9) A method for manufacturing a machined product, comprising: a step of rotating a workpiece or the cutting tool described in (8); a step of bringing the workpiece and the cutting tool into contact; and a step of moving the cutting tool relatively away from the workpiece.

[0092] 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.

[0093] REFERENCE SIGNS LIST 1 coated tool 11 insert 15 through hole 2 substrate 3 coating layer 31 laminate 31a first layer 31b second layer 32 base layer 70 holder 73 pocket 75 screw 100 cutting tool 200 machined workpiece 201 workpiece O1 shaft

Claims

1. A coated tool comprising: a substrate; and a coating layer disposed on the substrate, wherein the coating layer includes a stack of alternating first layers and second layers, each of the first layers and the second layers containing aluminum and titanium, and at least the second layers in the coating layer further containing boron, the boron content of the second layers being higher than the boron content of the first layers.

2. The coated tool according to claim 1, wherein the titanium content in the plurality of first layers is higher than the aluminum content in the plurality of first layers, and the titanium content in the plurality of second layers is higher than the aluminum content in the plurality of second layers.

3. The coated tool according to claim 1 or 2, wherein the titanium content in the plurality of first layers is higher than the titanium content in the plurality of second layers.

4. The coated tool according to any one of claims 1 to 3, wherein the aluminum content in the plurality of first layers is lower than the aluminum content in the plurality of second layers.

5. A coated tool according to any one of claims 1 to 4, wherein the ratio of the sum of the titanium content in the first layers and the titanium content in the second layers to the sum of the aluminum content in the first layers and the aluminum content in the second layers is 1.8 or more and 2.3 or less.

6. A coated tool according to any one of claims 1 to 5, wherein the coating layer further includes an underlayer positioned between the substrate and the laminate, and the underlayer has a thermal expansion coefficient between the thermal expansion coefficients of the substrate and the laminate.

7. The coated tool according to claim 6, wherein the substrate is a cubic boron nitride sintered body, and the underlayer contains aluminum chromium nitride.

8. A cutting tool comprising: a holder extending from a front end to a rear end and having a pocket located on the front end side; and a coated tool according to any one of claims 1 to 7 located in the pocket.

9. A method for manufacturing a machined product, comprising the steps of: rotating a workpiece or the cutting tool according to claim 8; bringing the workpiece and the cutting tool into contact; and moving the cutting tool relatively away from the workpiece.

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