Coated tool and cutting tool

Abstract

A coated tool according to a non-limiting aspect of the present disclosure comprises a plate-shaped substrate and a coating layer located on the surface of the substrate. The coated tool has an upper surface. The upper surface includes first corners and second corners having a larger angle than the first corners. The residual stress of the coating layer at the first corners is denoted by a. The residual stress of the coating layer at the second corners is denoted by b. Furthermore, a and b are different.

Description

Coated tool and cutting tool Cross-reference to related applications

[0001] This application claims the priority of Japanese Patent Application No. 2024-183596 filed on October 18, 2024, and incorporates the entire disclosure of this prior application herein by reference.

[0002] This disclosure relates to coated tools and cutting tools.

[0003] As a coated tool used for cutting tools and the like, for example, a coated tool described in JP-A-2021-142610 (Patent Document 1) is known. The coated tool described in Patent Document 1 includes a tool substrate, a hard coating disposed on the surface of the tool substrate, and a cutting edge. The hard coating has a titanium carbonitride layer. The residual stress on the outermost surface of the cutting edge portion and the portion adjacent to the cutting edge in this titanium carbonitride layer is -1.5 GPa or less.

[0004] A coated tool according to a non-limiting aspect of the present disclosure is a coated tool including a plate-shaped substrate and a coating layer located on the surface of the substrate. The coated tool has an upper surface. The upper surface has a first corner and a second corner having a larger angle than the first corner. Let the residual stress of the coating layer at the first corner be a. Let the residual stress of the coating layer at the second corner be b. The a and the b are different.

[0005] It is a perspective view showing a coated tool according to a non-limiting aspect of the present disclosure. It is a plan view of the coated tool shown in FIG. 1 as viewed from the upper surface side. It is a plan view of the coated tool shown in FIG. 1 as viewed from the upper surface side. It is a schematic diagram for explaining the width of a crack in the coated tool shown in FIG. 1. It is a cross-sectional view showing the vicinity of the surface of a coated tool according to a non-limiting aspect of the present disclosure. It is a cross-sectional view showing the vicinity of the surface of a coated tool according to a non-limiting aspect of the present disclosure. It is a plan view showing a cutting tool according to a non-limiting aspect of the present disclosure.

[0006] <Covering Tool> A coating tool 1, which is not limited to this disclosure, will be described in detail below with reference to the drawings. However, in the drawings referenced below, for the sake of convenience of explanation, only the main components necessary for describing the embodiment are shown in a simplified manner. Therefore, the coating tool 1 may include any components not shown in the drawings referenced below. Also, the dimensions of the components in each drawing do not faithfully represent the dimensions of the actual components or the dimensional ratios of each component.

[0007] In addition, a cutting insert may be shown as an example of a coated tool 1, although this is not limited to this example. A cutting insert may also be called a tip.

[0008] The coating tool 1 may comprise a plate-shaped base 3 and a coating layer 7 located on the surface 5 of the base 3, as shown in the example (not limited to) in Figures 1 to 6.

[0009] The coating tool 1 may have an upper surface 9. Note that the upper surface 9 is a convenient designation and does not indicate an upward direction. For example, the upper surface 9 does not need to face upwards when using the coating tool 1.

[0010] The coating tool 1 is not limited to a specific size. For example, the length of one side of the top surface 9 may be set to 8 to 20 mm. Also, the height from the top surface 9 to the surface opposite to the top surface 9 (bottom surface) may be set to 3 to 20 mm.

[0011] The top surface 9 may be polygonal in shape. In one example, not limited to Figure 2, the top surface 9 is rhombic in shape. When the top surface 9 is rhombic in shape, it may have two acute corners 11 and two obtuse corners 13. In other words, the four corners of the rhombic top surface 9 may be two acute corners 11 and two obtuse corners 13.

[0012] An acute corner 11 is a corner where, when the top surface 9 is viewed from the front, the angle at which the two edges extending from the corner intersect is less than a right angle. Conversely, an obtuse corner 13 is a corner where, when the top surface 9 is viewed from the front, the angle at which the two edges extending from the corner intersect is greater than a right angle.

[0013] The angles at the acute corner 11 and the obtuse corner 13 are not limited to specific values. For example, the angle of the acute corner 11 may be set to 25° or more and less than 90°. The angle of the obtuse corner 13 may be set to more than 90° and 155° or less.

[0014] The two acute corners 11 may be a first acute corner 15 and a second acute corner 17. Also, the two obtuse corners 13 may be a first obtuse corner 19 and a second obtuse corner 21.

[0015] Here, the upper surface 9 may have a first corner and a second corner with a larger angle than the first corner. In one example, not limited to Figure 2, the first corner is a first acute-angled corner 15, and the second corner is a second obtuse-angled corner 21.

[0016] The residual stress of the coating layer 7 at the first acute corner 15 (first corner) may be denoted as a. The residual stress of the coating layer 7 at the second obtuse corner 21 (second corner) may be denoted as b. Furthermore, a and b may be different. In this case, the chipping resistance is high at corners where the residual stress is relatively small. Also, the wear resistance is high at corners where the residual stress is relatively large. Therefore, the coated tool 1 has high chipping resistance and wear resistance. When chipping resistance or wear resistance is high at the first corner with a relatively small angle, it is effective for machining complex-shaped parts or near-net-shape parts and tends to show a good cutting life. Also, when chipping resistance or wear resistance is high at the second corner with a relatively large angle, it tends to show a good cutting life in mill scale cutting of cast iron or rough machining of forged products.

[0017] The relationship between a and b may be a < b. In this case, the fracture resistance is high at the first acute-angled corner 15 where the residual stress is relatively small. Also, the wear resistance is high at the second obtuse-angled corner 21 where the residual stress is relatively large.

[0018] a may be in the range of -0.2 to 0.3 GPa. Also, b may be in the range of 0.2 to 0.5 GPa. b may be in the range of 0.3 to 0.5 GPa. These numerical ranges may be the mean.

[0019] The residual stress of the coating layer 7 at the first obtuse corner 19 may be denoted as c. The residual stress of the coating layer 7 at the second acute corner 17 may be denoted as d. The relative magnitudes of a, b, c, and d may not differ by a = c = d ≠ b. In other words, a, b, c, and d may be the same, while only b differs. In these cases, intermittent machining and finishing can be performed with a single chip without changing the chip, which improves machining efficiency. In particular, continuous and intermittent machining can be performed simultaneously in surface contact machining.

[0020] The relative magnitudes of a, b, c, and d may be a = c = d < b. In this case, the first acute corner 15, the first obtuse corner 19, and the second acute corner 17 have high fracture resistance, while the second obtuse corner 21 has high wear resistance. Note that having the same residual stress, such as a = c = d, does not necessarily mean that they are exactly the same, but may also mean that a difference of 0.1 GPa in the average value of the residual stresses being compared is acceptable.

[0021] a may be a compressive stress and b may be a tensile stress. In this case, the fracture resistance at the first acute corner 15 is higher. Note that c and d may also be compressive stresses. If a is a compressive stress, a may be in the range of -0.2 to -0.1 GPa.

[0022] If the residual stress value is positive (+), the residual stress is tensile stress. If the residual stress value is negative (-), the residual stress is compressive stress. The relative magnitudes of a, b, c, and d are not evaluated in terms of absolute values. That is, the relative magnitudes of a, b, c, and d are considered in terms of their positive and negative signs. For example, in sample No. 3 of the example described later, a is a negative value and b is a positive value. In these cases, a < b is evaluated.

[0023] Residual stress may be measured, for example, using the sin²ψ method with an X-ray Diffraction (XRD) device.

[0024] The measurement conditions for residual stress may be set as follows, for example: Radiation source: CuK Output: 50kV, 1000μA Collimator diameter: 0.5mmφ Measurement method: sin²ψ method Other: Measurements are performed with n=3 and the average value is calculated.

[0025] The residual stress of the coating layer 7 at the corner may be measured within a 5 mm range from the corner. The residual stress measured within this range may be considered as the residual stress of the coating layer 7 at the corner.

[0026] The coating tool 1 may further include, in addition to the upper surface 9, a side surface 23 adjacent to the upper surface 9 and a cutting edge 25 located at the intersection of the upper surface 9 and the side surface 23, as shown in the example not limited to Figure 1.

[0027] The upper surface 9 may be a rake face. The entire upper surface 9 may be a rake face, or only a part of it may be a rake face. For example, the portion of the upper surface 9 along the cutting edge 25 may be a rake face.

[0028] The side surface 23 may be a relief surface. The entire side surface 23 may be a relief surface, or only a part of it may be a relief surface. For example, the region of the side surface 23 along the cutting edge 25 may be a relief surface.

[0029] The cutting edge 25 may be located along the entire intersection of the top surface 9 and the side surface 23, or it may be located only along a portion of this intersection. For example, the cutting edge 25 may be located at a corner. The cutting edge 25 may also be located along the first side 27 and the second side 29 as described below. The cutting edge 25 can be used to cut the workpiece when manufacturing a workpiece using the coated tool 1.

[0030] The second corner may be adjacent to the first corner. In one example, not limited to Figure 2, the second obtuse-angled corner 21, which is the second corner, is adjacent to the first acute-angled corner 15, which is the first corner. When the second corner is adjacent to the first corner, it becomes possible to broaden the range of cutting conditions that can be recommended for a single insert. For example, it becomes possible to apply a single insert to many cutting operations, such as finishing at the first corner and roughing at the second corner, or low-speed cutting at the first corner and high-speed cutting at the second corner.

[0031] The top surface 9 may have a third corner adjacent to the first corner, with a larger angle than the first corner. The top surface 9 may also have a fourth corner adjacent to the second and third corners, with a smaller angle than the second and third corners. In one example, not limited to Figure 2, the third corner is the first obtuse-angled corner 19, and the fourth corner is the second acute-angled corner 17. That is, in one example, not limited to Figure 2, the four corners of the rhombic top surface 9 and the first to fourth corners have the following relationship: First corner: First acute-angled corner 15; Second corner: Second obtuse-angled corner 21; Third corner: First obtuse-angled corner 19; Fourth corner: Second acute-angled corner 17

[0032] The top surface 9 may further have a first side 27 and a second side 29, as shown in the example not limited to Figure 3. The first side 27 may extend from the first acute corner 15 (first corner) toward the first obtuse corner 19 (third corner). The second side 29 may extend from the first acute corner 15 (first corner) toward the second obtuse corner 21 (second corner). In other words, of the four sides of the rhombus-shaped top surface 9, the side connected to the first acute corner 15 and the first obtuse corner 19 may be the first side 27, and the side connected to the first acute corner 15 and the second obtuse corner 21 may be the second side 29. In the example not limited to Figure 3, the first side 27 and the second side 29 are of equal length.

[0033] The upper surface 9 may further have a first region 31 and a second region 33. The first region 31 may be located along the first edge 27. The second region 33 may be located along the second edge 29. The first region 31 and the second region 33 may be located on the rake face.

[0034] In the example shown in Figure 3, which is not limited to this design, the first region 31 is a strip-shaped region connected to the first side 27. The second region 33 is a strip-shaped region connected to the second side 29. The second region 33 is connected to the first region 31 via the first acute corner 15 (first corner). In other words, the first region 31 and the second region 33 are each connected to the first acute corner 15 (first corner).

[0035] The residual stress of the coating layer 7 in the first region 31 and the second region 33 may be in the range of -0.2 to 0.3 GPa. The residual stress of the coating layer 7 in the first region 31 may be measured within a range of 5 mm from the first side 27. The residual stress of the coating layer 7 in the second region 33 may be measured within a range of 5 mm from the second side 29.

[0036] The residual stresses of the coating layer 7 in the first region 31 and the second region 33 may be the same. Also, the residual stresses of the coating layer 7 in the first region 31 and the second region 33 may be the same as the residual stresses of the coating layer 7 at the first acute corner 15.

[0037] The length of the first region 31 in the direction along the first side 27 may be defined as the first length L1. The length of the second region 33 in the direction along the second side 29 may be defined as the second length L2. Furthermore, the first length L1 and the second length L2 may be different. In this case, the recommended depth of cut for a single chip can be changed by changing the orientation of the holder on which the chip is attached. For example, intermittent machining can be performed at the first acute corner 15, and finishing can be performed at the obtuse corner 13, making it possible to handle many types of machining with a single chip. As a result, machining costs can be reduced and machining efficiency can be increased.

[0038] The relationship between the first length L1 and the second length L2 may be such that the first length L1 > the second length L2. In this case, chipping of the chip is less likely to occur when performing full contact machining of the end face. If the second length L2 is less than or equal to half of the first length L1, chipping of the chip is even less likely to occur when performing full contact machining of the end face.

[0039] The first length L1 may be in the range of 8 to 20 mm. The second length L2 may be in the range of 6 to 10 mm.

[0040] The first region 31 may be connected to the first obtuse-angled corner 19 (third corner). The second region 33 may be separated from the second obtuse-angled corner 21 (second corner).

[0041] The surface roughness of the coating layer 7 at the first acute corner 15 (the first corner) may be smaller than the surface roughness of the coating layer 7 at the second obtuse corner 21 (the second corner). In this case, at the first acute corner 15 where the surface roughness is relatively small, the cutting resistance is likely to be reduced during cutting operations such as interrupted machining. Also, at the second obtuse corner 21 where the surface roughness is relatively large, the chips are likely to be curled properly, chip breakage is likely to be appropriately performed, and abnormal damage to the coated tool 1 is likely to be suppressed.

[0042] The surface roughness may be evaluated by the arithmetic mean roughness (Ra). The arithmetic mean roughness (Ra) of the coating layer 7 at the first acute corner 15 may be 0.2 to 0.4 μm. Also, the arithmetic mean roughness (Ra) of the coating layer 7 at the second obtuse corner 21 may be 0.3 to 0.5 μm.

[0043] The arithmetic mean roughness (Ra) may be measured using a laser microscope surface profiler. Specific measurement conditions may be set, for example, as follows. Apparatus: Non-contact surface property measuring device manufactured by Mitaka Kohki Co., Ltd. Model number: PF-60 Measurement principle: Point autofocus method ISO 25178-605 AF axis scale resolution: 0.01 μm X-Y axis scale resolution: 0.1 μm Laser: λ = 635 nm Output 1.0 mW or less Measurement range: 400 μm Measurement pitch: 1.0 μm Measurement method: Index measurement AF gain: Standard AF sensor: Wide Objective lens: ×100

[0044] The measurement of the surface roughness of the coating layer 7 at the corner may be performed within a range of 2 mm from the corner. The surface roughness measured within this range may be regarded as the surface roughness of the coating layer 7 at the corner.

[0045] The surface roughnesses of the coating layer 7 at the first acute corner 15, the first obtuse corner 19, and the second acute corner 17 may be the same. Note that the surface roughnesses being the same is not limited to being exactly the same, and it may mean allowing a difference of 0.04 μm in the arithmetic mean roughness (Ra) to be compared.

[0046] R honing may be provided at the first acute corner 15 (first corner) and the second obtuse corner 21 (second corner). The R honing of the first acute corner 15 may be larger than the R honing of the second obtuse corner 21. In this case, in continuous machining using the second obtuse corner 21 with relatively small R honing, the cutting edge is likely to be improved and the life is also likely to be prolonged.

[0047] The size relationship of the R honing may be evaluated by the radius of curvature. The radius of curvature of the R honing at the first acute corner 15 may be 0.045 to 0.075 mm. Also, the radius of curvature of the R honing at the second obtuse corner 21 may be 0.03 to 0.07 mm.

[0048] R honing may also be provided at the first obtuse corner 19 and the second acute corner 17. The respective R honings at the first acute corner 15, the first obtuse corner 19, and the second acute corner 17 may be the same. Note that the fact that the R honings are the same is not limited to being exactly the same, and it may mean allowing a difference of 0.002 mm in the radius of curvature of the R honings to be compared.

[0049] The thickness of the coating layer 7 at the first acute corner 15 (first corner) may be smaller than the thickness of the coating layer 7 at the second obtuse corner 21 (second corner). In this case, in continuous machining using the second obtuse corner 21 with a relatively large thickness of the coating layer 7, the life is likely to be prolonged.

[0050] The thickness of the coating layer 7 may be an average value. The average thickness of the coating layer 7 at the first acute corner 15 may be 8 to 18 μm. Also, the average thickness of the coating layer 7 at the second obtuse corner 21 may be 9 to 19 μm.

[0051] The average thickness of the coating layer 7 may be measured by cross-sectional observation using an electron microscope. For example, the thickness may be measured at 10 or more measurement points at arbitrary locations on the coating layer 7, and the average value may be calculated. Examples of electron microscopes include scanning electron microscopes (SEM) and transmission electron microscopes (TEM).

[0052] The thickness of the coating layer 7 at the corner may be measured within a 3 mm range from the corner. The thickness measured within this range may be considered as the thickness of the coating layer 7 at the corner.

[0053] The thickness of the coating layer 7 at the first acute corner 15, the first obtuse corner 19, and the second acute corner 17 may be the same. Note that "the thickness of the coating layer 7 is the same" does not mean that they are exactly the same, but rather that a difference of 0.4 μm in the average thickness of the coating layers 7 being compared is permitted.

[0054] The coating layer 7 at the first acute corner 15 (first corner) and the second obtuse corner 21 (second corner) may have cracks 35 (see Figure 4). The cracks 35 may open on the surface of the coating layer 7. The width W of the crack 35 in the coating layer 7 at the first acute corner 15 may be greater than the width W of the crack 35 in the coating layer 7 at the second obtuse corner 21. In this case, the coolant is more likely to remain on the cutting edge, and the cooling effect during cutting is more likely to improve.

[0055] The crack 35 may be band-shaped when the upper surface 9 is viewed from the front. In this case, the width W of the crack 35 is the dimension perpendicular to the direction in which the crack 35 extends.

[0056] The width W of the crack 35 may be an average value. The average width of the crack 35 in the coating layer 7 at the first acute corner 15 may be 1 to 30 μm, 5 to 15 μm, or 8 to 12 μm. Also, the average width of the crack 35 in the coating layer 7 at the second obtuse corner 21 may be 0.01 to 0.1 μm.

[0057] The average width of the crack 35 may be measured by observing the coating layer 7 (upper surface 9) using a laser microscope. For example, a 205 μm × 275 μm area of ​​the microscope image obtained by photographing the coating layer 7 (upper surface 9) at 500x magnification may be used as one field of view. Alternatively, the width W of the cracks present in the aforementioned field of view may be measured at five measurement points perpendicular to the direction in which the crack 35 extends, at intervals of 0.13 μm or 0.26 μm, and the average value may be calculated.

[0058] The width W of the crack 35 may be measured within a range of 3 mm from the corner. The width W of the crack 35 measured within this range may be considered as the width W of the crack 35 present in the coating layer 7 at the corner.

[0059] The coating layer 7 at the first obtuse corner 19 and the second acute corner 17 may also have cracks 35. The width W of the cracks 35 in the respective coating layers 7 at the first acute corner 15, the first obtuse corner 19, and the second acute corner 17 may be the same. Note that the width W of the cracks 35 being the same does not mean that they are exactly the same, but may mean that a difference of 1 μm in the average width of the cracks 35 being compared is permitted.

[0060] The base material 3 may be a sintered alloy. The sintered alloy may be made of cemented carbide. In other words, the base material 3 may be made of cemented carbide. The cemented carbide may contain a hard phase and a binder phase. The hard phase in the cemented carbide may contain, for example, tungsten carbide (WC). Furthermore, the hard phase in the cemented carbide may contain WC as the main component. That is, the cemented carbide may be a WC-based cemented carbide. Note that "main component" means the component with the largest mass percentage value compared to other components.

[0061] The bonding phase in cemented carbide may contain iron group metals. Examples of iron group metals include cobalt (Co) and nickel (Ni). The bonding phase in cemented carbide may contain at least one of Co and Ni. The bonding phase in cemented carbide may contain iron group metals as its main component. The bonding phase can function as a phase that bonds adjacent hard phases.

[0062] The substrate 3 may be made of a cemented carbide. In this case, the hard phase may be made of WC. Alternatively, the hard phase may contain a cubic crystal structure compound in addition to WC. In this case, the cubic crystal structure compound may be composed of at least one selected from carbides, nitrides, carbon oxides, nitrogen oxides and their mutual solid solutions of elements from groups 4, 5, and 6 of the periodic table. That is, the hard phase may consist of at least one cubic crystal structure compound selected from carbides, nitrides, carbon oxides, nitrogen oxides and their mutual solid solutions of elements from groups 4, 5, and 6 of the periodic table, and WC. Furthermore, the bonding phase may mainly consist of Co and / or Ni.

[0063] When the substrate 3 is a sintered alloy, the sintered alloy may consist of a cermet. In other words, the substrate 3 may consist of a cermet. The cermet may contain a hard phase and a bonding phase. The hard phase in the cermet may contain, for example, a titanium (Ti) compound. Examples of Ti compounds include titanium carbonitride (TiCN), titanium carbide (TiC), and titanium nitride (TiN). Furthermore, the hard phase in the cermet may contain a Ti compound as its main component. That is, the cermet may be a Ti-based cermet.

[0064] The bonding phase in a cermet may contain iron group metals. The bonding phase in a cermet may contain at least one of Co and Ni. The bonding phase in a cermet may contain iron group metals as its main component.

[0065] The composition of substrate 3 may be measured, for example, by energy dispersive X-ray spectroscopy (EDS). The measurement may be performed using an EDS attached to an electron microscope.

[0066] The coating layer 7 may be located on the entire surface 5 of the substrate 3, or only on a portion of it. That is, the coating layer 7 may be located on at least a portion of the surface 5 of the substrate 3 (the corners, the first side 27, and the second side 29).

[0067] The coating layer 7 may be formed by chemical vapor deposition (CVD). In other words, the coating layer 7 may be a CVD film. Furthermore, the coating layer 7 may be a PVD film formed by physical vapor deposition (PVD).

[0068] The coating layer 7 may be a single layer or a structure in which multiple layers are laminated. Examples of the composition of the coating layer 7 include TiCN, Al2O3 (alumina), and TiN.

[0069] The coating layer 7 may have a TiCN layer 37 and an Al2O3 layer 39 in that order from the substrate 3, as shown in the example shown in Figure 5. The TiCN layer 37 may be in contact with the substrate 3. The Al2O3 layer 39 may be in contact with the TiCN layer 37.

[0070] The coating layer 7 may have, in order from the substrate 3, a TiN layer 41, a TiCN layer 37, and an Al2O3 layer 39, as shown in the example not limited to Figure 6. The TiN layer 41 may be in contact with the substrate 3. The TiCN layer 37 may be in contact with the TiN layer 41. The Al2O3 layer 39 may be in contact with the TiCN layer 37.

[0071] The TiCN layer 37 may have an average thickness of approximately 6 to 9 μm. The Al2O3 layer 39 may have an average thickness of approximately 3 to 5 μm. The TiN layer 41 may have an average thickness of approximately 1 to 2 μm.

[0072] The covering tool 1 may have a through hole 43. The through hole 43 can be used to attach a screw or clamp member when fixing the covering tool 1 to a holder. The through hole 43 may be formed from the upper surface 9 to the surface opposite the upper surface 9 (the lower surface), or it may open on these surfaces. There is no problem if the through hole 43 is configured to open in mutually opposing regions on the side surface 23.

[0073] <Method for Manufacturing a Covered Tool> Next, a method for manufacturing a covered tool, not limited to this disclosure, will be explained using the case of manufacturing a covered tool 1 as an example.

[0074] When manufacturing the coated tool 1, a base body 3 may be prepared first. The process will be explained using the example of preparing a base body 3 made of a sintered alloy. First, an inorganic powder such as a carbide, nitride, carbonitride, or oxide, which can form a base body 3 by firing, may be mixed with metal powder, carbon powder, etc., as appropriate to obtain a mixed powder. Next, this mixed powder may be molded into a predetermined cutting tool shape by known molding methods such as press molding, casting, extrusion molding, or cold isostatic press molding. For example, the obtained mixed powder may be molded into a cutting tool shape with a plate shape and a rhomboid top surface. Then, the resulting molded body may be fired in a vacuum or a non-oxidizing atmosphere to obtain a base body 3 made of a sintered alloy. The corners of the obtained base body 3 may be subjected to R-honing.

[0075] Next, a coating layer 7 may be formed on the surface 5 of the obtained substrate 3 by CVD to obtain a coated tool 1.

[0076] The TiCN layer 37 may be formed as follows. First, a mixed gas may be prepared as the reaction gas composition, consisting of 0.1 to 10 volume% titanium tetrachloride (TiCl4) gas, 10 to 60 volume% nitrogen (N2) gas, 0.1 to 15 volume% acetonitrile (CH3CN) gas, and the remainder being hydrogen (H2) gas. Then, this mixed gas may be introduced into a chamber, the temperature may be set to 800 to 1100°C and the pressure to 5 to 30 kPa, and the TiCN layer 37 may be formed.

[0077] The Al2O3 layer 39 may be formed as follows. First, a mixed gas may be prepared as the reaction gas composition, consisting of 0.5 to 5 volume% aluminum trichloride (AlCl3) gas, 0.5 to 3.5 volume% hydrogen chloride (HCl) gas, 0.5 to 5 volume% carbon dioxide (CO2) gas, 0.5 volume% or less hydrogen sulfide (H2S) gas, and the remainder being hydrogen (H2) gas. Then, this mixed gas may be introduced into a chamber, the temperature may be set to 930 to 1010°C and the pressure to 5 to 10 kPa, and the Al2O3 layer 39 may be formed.

[0078] The TiN layer 41 may be formed as follows. First, a mixed gas may be prepared as the reaction gas composition, consisting of 0.1 to 10 volume% titanium tetrachloride (TiCl4) gas, 10 to 60 volume% nitrogen (N2) gas, and the remainder being hydrogen (H2) gas. Then, this mixed gas may be introduced into a chamber, the temperature may be set to 800 to 1010°C and the pressure to 10 to 85 kPa, and the TiN layer 41 may be formed.

[0079] Alternatively, the gas used for film formation may be injected directly onto the second obtuse-angled corner 21 (second corner) during film formation. By forming the film in this manner, it is possible to adjust the film thickness and residual stress b of the second obtuse-angled corner 21.

[0080] The coating layer 7 may be cooled after deposition. In this case, the cooling rate may be set to 1 to 10°C / min. When cooled under these conditions, band-shaped cracks 35 are likely to form in the coating layer 7 at the corners.

[0081] The formed coating layer 7 may be subjected to blast treatment to make a and b different. For example, if the coating layer 7 at the first acute-angled corner 15 (first corner) is subjected to blast treatment, but the coating layer 7 at the second obtuse-angled corner 21 (second corner) is not subjected to blast treatment, it is possible to make a and b different from each other so that a < b.

[0082] Furthermore, when the coating layer 7 at the first obtuse-angled corner 19 and the second acute-angled corner 17 is subjected to the same blast treatment as the first acute-angled corner 15, it is possible to make a, c, and d have the relationship a=c=d.

[0083] If the coating layer 7 at the first acute corner 15 is blast-treated, but the coating layer 7 at the second obtuse corner 21 is not, the surface roughness of the coating layer 7 at the first acute corner 15 tends to be less than that of the coating layer 7 at the second obtuse corner 21. Also, the R-honing at the first acute corner 15 tends to be greater than that at the second obtuse corner 21. The thickness of the coating layer 7 at the first acute corner 15 tends to be less than that of the coating layer 7 at the second obtuse corner 21.

[0084] When the coating layer 7 at the first obtuse-angled corner 19 and the second acute-angled corner 17 is subjected to the same blast treatment as the first acute-angled corner 15, the surface roughness of the coating layer 7 at the first acute-angled corner 15, the first obtuse-angled corner 19, and the second acute-angled corner 17 tends to be the same. Also, the R-honing at the first acute-angled corner 15, the first obtuse-angled corner 19, and the second acute-angled corner 17 tends to be the same. The thickness of the coating layer 7 at the first acute-angled corner 15, the first obtuse-angled corner 19, and the second acute-angled corner 17 tends to be the same.

[0085] The blasting process may be dry. Examples of blasting agents include spherical ceramic particles and spherical metal particles. Examples of materials for spherical ceramic particles include Al2O3, ZrO2, and SiC. Examples of materials for spherical metal particles include steel. Spherical ceramic particles and spherical metal particles may also be called spherical particles. The average particle size of the spherical particles may be 20 to 150 μm. The average particle size of the spherical particles may be measured by laser diffraction. The hardness (HV) of the spherical particles may be 400 to 1200. HV (Vickers hardness) may be measured in accordance with JIS Z 2244:2009.

[0086] The blasting conditions may be set as follows, for example: Pressure: 0.2 to 0.5 MPa Time: 3 to 15 seconds

[0087] If the coating layer 7 at the first acute corner 15 is subjected to blast treatment under the above conditions, and the coating layer 7 at the second obtuse corner 21 is not subjected to blast treatment under the above conditions, then a and b are likely to fall within the above-described numerical range.

[0088] The coating layer 7 along the first side 27 and the second side 29 may be subjected to blast treatment under the above conditions. In this case, the first region 31 and the second region 33, in which the residual stress of the coating layer 7 is within the above numerical range, are more likely to be formed. Furthermore, the length of the blast treatment in the direction along the first side 27 may be different from the length of the blast treatment in the direction along the second side 29. For example, if the length of the blast treatment in the direction along the first side 27 is made relatively longer, the first length L1 and the second length L2 can be made different from each other such that the relationship first length L1 > second length L2 is obtained.

[0089] If the coating layer 7 at the first acute corner 15 is blast-treated, but the coating layer 7 at the second obtuse corner 21 is not blast-treated, the width W of the crack 35 in the coating layer 7 at the first acute corner 15 tends to be larger than the width W of the crack 35 in the coating layer 7 at the second obtuse corner 21.

[0090] When the coating layer 7 at the first obtuse-angled corner 19 and the second acute-angled corner 17 is subjected to the same blast treatment as the first acute-angled corner 15, the width W of the cracks 35 in the coating layer 7 at the first acute-angled corner 15, the first obtuse-angled corner 19, and the second acute-angled corner 17 tends to be the same.

[0091] The above manufacturing method is merely one example of a method for manufacturing the coated tool 1. Therefore, it goes without saying that the coated tool 1 is not limited to those manufactured by the above manufacturing method.

[0092] <Cutting Tools> Next, a cutting tool 101, not limited to this disclosure, will be described with reference to the drawings, using the case in which the above-described coated tool 1 is provided as an example.

[0093] The cutting tool 101 may include a holder 103 and a coated tool 1, as shown in the example not limited to Figure 7. The holder 103 may extend from a first end 103a toward a second end 103b, and may have a pocket 105 on the side of the first end 103a. The coated tool 1 may be located in the pocket 105. When the cutting tool 101 includes a coated tool 1, the coated tool 1 has high fracture resistance and wear resistance, resulting in excellent cutting performance and stable cutting.

[0094] The pocket 105 may be the portion into which the covering tool 1 is attached. The pocket 105 may be open on the outer circumferential surface of the holder 103 and on the end face on the side of the first end 103a.

[0095] The covering tool 1 may be mounted in the pocket 105 such that at least a portion of the cutting edge 25 protrudes from the holder 103. Alternatively, the covering tool 1 may be mounted in the pocket 105 by a screw 107. That is, the covering tool 1 may be mounted in the pocket 105 by inserting the screw 107 into the through hole 43 of the covering tool 1, and then inserting the tip of the screw 107 into a screw hole formed in the pocket 105 and fixing the screw 107 in the screw hole. In this case, the lower surface of the covering tool 1 may be in direct contact with the pocket 105, or a sheet may be sandwiched between the covering tool 1 and the pocket 105.

[0096] Examples of materials for the holder 103 include steel and cast iron. When the holder 103 is made of steel, it has high toughness.

[0097] In the example shown in Figure 7, a cutting tool 101 used in so-called turning operations is illustrated. Examples of turning operations include internal diameter machining, external diameter machining, and grooving operations. Note that the cutting tool 101 (coated tool 1) is not limited to turning operations. For example, there is no problem in using the coated tool 1 as a cutting tool 101 used in milling operations.

[0098] The above exemplifies one aspect of the coating tool 1 and cutting tool 101 that are not limited to the present disclosure. However, it goes without saying that the present disclosure is not limited to the embodiments described above, and any such embodiment can be used as long as it does not deviate from the gist of the present disclosure.

[0099] For example, the coating tool 1 and the cutting tool 101 may have the following configurations: [1] The coating tool is a coating tool comprising a plate-shaped base and a coating layer located on the surface of the base, wherein the coating tool has an upper surface, the upper surface having a first corner and a second corner having a larger angle than the first corner, the residual stress of the coating layer at the first corner being a and the residual stress of the coating layer at the second corner being b, and a and b being different. [2] In the coating tool of [1] above, the relationship between a and b may be a < b. [3] In the coating tool of [2] above, a may be in the range of -0.2 to 0.3 GPa and b may be in the range of 0.2 to 0.5 GPa. [4] In any one of the coating tools of [1] to [3] above, the second corner may be adjacent to the first corner. [5] The coating tool described in [4] above has a top surface which is a scooping surface and further includes a third corner adjacent to the first corner and having a larger angle than the first corner, a first side extending from the first corner toward the third corner, a second side extending from the first corner toward the second corner, a first region located along the first side, and a second region located along the second side, wherein the residual stress of the coating layer in the first region and the second region is in the range of -0.2 to 0.3 GPa, the length of the first region in the direction along the first side is defined as the first length, and the length of the second region in the direction along the second side is defined as the second length, and the first length and the second length may be different. [6] The coating tool described in [5] above may have a relationship between the first length and the second length such that the first length > the second length. [7] The coating tool described in [6] above may have a first length in the range of 8 to 20 mm and a second length in the range of 6 to 10 mm. [8] In any one of the coating tools described in [1] to [7] above, the surface roughness of the coating layer at the first corner may be less than the surface roughness of the coating layer at the second corner. [9] In any one of the coating tools described in [1] to [8] above, R-honing may be provided at the first corner and the second corner, and the R-honing at the first corner may be greater than the R-honing at the second corner.

[10] In any one of the coating tools described in [1] to [9] above, the thickness of the coating layer at the first corner may be less than the thickness of the coating layer at the second corner.

[11] In any one of the coating tools described in [1] to

[10] above, the coating layer at the first corner and the second corner may have cracks that open on the surface of the coating layer, and the width of the crack in the coating layer at the first corner may be greater than the width of the crack in the coating layer at the second corner.

[12] In any one of the coating tools described in [1] to

[11] above, the coating layer may have a TiCN layer and an Al2O3 layer in that order from the substrate side.

[13] In any one of the coating tools described in [1] to

[11] above, the coating layer may have a TiN layer, a TiCN layer and an Al2O3 layer in that order from the substrate side.

[14] The cutting tool may comprise a holder extending from a first end toward a second end and having a pocket on the side of the first end, and one of the covering tools [1] to

[13] located in the pocket.

[0100] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0101] [Sample No. 1-4] <Preparation of coated tools> First, the substrate was prepared. Specifically, a mixed powder was obtained by mixing 6% by mass of metallic cobalt powder with an average particle size of 1.2 μm, 0.5% by mass of titanium carbide powder with an average particle size of 2 μm, 5% by mass of niobium carbide powder with an average particle size of 2 μm, and the remainder being tungsten carbide powder with an average particle size of 1.5 μm. The average particle size of each powder was measured using the microtrac method.

[0102] Next, the obtained mixed powder was press-molded into a cutting tool shape (CNMG120408) with a rhombic top surface in a plate shape to obtain a molded body. Then, the obtained molded body was subjected to a binder removal treatment and fired in a non-oxidizing atmosphere to obtain a substrate made of cemented carbide. The firing temperature was set to 1450°C and the firing time to 1 hour, and an argon atmosphere was used as the non-oxidizing atmosphere.

[0103] The composition of the obtained cemented carbide was measured using EDS. Specifically, cross-sectional observation was performed using an EDS attached to a SEM, with a magnification of 5,000 to 20,000 times, and the average value of five measurements was used. Five elements were selected for measurement: tungsten carbide, cobalt, titanium, carbon, and nitrogen, and EDS was performed on these elements.

[0104] EDS measurements revealed that the obtained cemented carbide contained a hard phase and a binder phase. More specifically, the obtained cemented carbide had a hard phase containing WC as its main component and a binder phase containing Co as its main component.

[0105] The corners of the obtained substrate were subjected to R-honing. Then, a coating layer was deposited on the surface of the substrate by CVD. The coating layer was deposited in the following order from the substrate side: a TiN layer, a TiCN layer, and an Al2O3 layer. The deposition conditions for each layer are as follows.

[0106] (Conditions for depositing the TiN layer) First, a mixed gas was prepared as the reaction gas composition, consisting of 1 volume% titanium tetrachloride (TiCl4) gas, 38 volume% nitrogen (N2) gas, and the remainder being hydrogen (H2) gas. This mixed gas was then introduced into the chamber, and the temperature was set to 850°C and the pressure to 16 kPa. The deposition time was set to 180 minutes.

[0107] (Conditions for depositing the TiCN layer) First, a mixed gas was prepared as the reaction gas composition, consisting of 4% by volume of titanium tetrachloride (TiCl4) gas, 23% by volume of nitrogen (N2) gas, 0.4% by volume of acetonitrile (CH3CN) gas, and the remainder being hydrogen (H2) gas. This mixed gas was then introduced into the chamber, and the temperature was set to 850°C and the pressure to 9 kPa. The deposition time was set to 400 minutes.

[0108] (Conditions for depositing the Al2O3 layer) First, a mixed gas was prepared as the reaction gas composition, consisting of 3.7 volume% aluminum trichloride (AlCl3) gas, 0.7 volume% hydrogen chloride (HCl) gas, 4.3 volume% carbon dioxide (CO2) gas, 0.3 volume% hydrogen sulfide (H2S) gas, and the remainder being hydrogen (H2) gas. This mixed gas was then introduced into the chamber, and the temperature was set to 950°C and the pressure to 7.5 kPa. The film deposition time was set to 380 minutes.

[0109] The coating layer was cooled after deposition. The cooling rate was set to 5°C / min. The cooled coating layer was observed using a laser microscope. As a result, cracks were found to have formed in the coating layer at the corners. The cracks were open on the surface of the coating layer. Furthermore, when viewed from the front on the top surface, the cracks were band-shaped.

[0110] The deposited coating layer was subjected to blast treatment to obtain the coated tools shown in Table 2. The obtained coated tools had a top surface with a side length of 12 mm and a height of 5 mm from the top surface to the bottom surface.

[0111] Blasting was performed on the coating layer at the first acute-angled corner (first corner) and the second obtuse-angled corner (second corner), as well as on the coating layer along the first and second sides, using blasting conditions A to C shown in Table 1 in combinations shown in Table 2. The blasting was performed dry. The blasting agent used was spherical particles (material: steel) with an average particle size of 50 μm and a hardness (HV) of 1000.

[0112] The residual stress of the coating layer at the first acute corner (first corner) and the second obtuse corner (second corner) of the obtained coated tool was measured according to the method illustrated above. The measurement results are shown in the "Residual Stress (GPa)" column in Table 2. The residual stress of the coating layer at the first acute corner is shown in column "a". The residual stress of the coating layer at the second obtuse corner is shown in column "b".

[0113] For each sample, blasting was performed along the first and second edges so that the lengths of the first and second regions matched the "Region Length (mm)" values ​​in Table 2. The first length is shown in the "First Region" column. The second length is shown in the "Second Region" column.

[0114] Furthermore, the residual stresses described above were also measured in the first and second regions. As a result, in each sample, the residual stresses of the coating layer in the first and second regions were the same as the residual stresses of the coating layer at the first acute-angle corner.

[0115] The arithmetic mean roughness (Ra) of the coating layer at the first acute corner and the second obtuse corner was measured according to the method exemplified above. The measurement results are shown in the "Arithmetic Mean Roughness (Ra) (μm)" column in Table 2.

[0116] The relative magnitudes of R-honing at the first acute-angle corner and the second obtuse-angle corner were evaluated using the radius of curvature. The measurement results are shown in the "R-honing (mm)" column of Table 2.

[0117] The average thickness of the coating layer at the first acute-angled corner and the second obtuse-angled corner was measured according to the method exemplified above. Measurements were taken at 10 measurement points using a scanning electron microscope (SEM). The measurement results are shown in the "Coating Layer Thickness (μm)" column of Table 2.

[0118] The average crack width at the first acute-angled corner and the second obtuse-angled corner was measured according to the method exemplified above. The measurement results are shown in the "Crack Width (μm)" column of Table 2.

[0119] Furthermore, the coating layers at the first obtuse-angled corner (third corner) and the second acute-angled corner (fourth corner) were subjected to the same blast treatment as the first acute-angled corner (first corner). The residual stress, arithmetic mean roughness (Ra), R honing, average thickness of the coating layer, and average crack width were then measured at the first obtuse-angled corner and the second acute-angled corner as described above. As a result, the values ​​at the first obtuse-angled corner and the second acute-angled corner were the same as the values ​​at the first acute-angled corner for each sample.

[0120] <Evaluation> The obtained coated tools were subjected to cutting tests under the following conditions.

[0121] (Cutting Test 1: Fracture Resistance Evaluation) Machining Method: Turning Cutting Speed: 48 m / min Feed Rate: 0.27 mm / rev Depth of Cut: 1.0 mm Workpiece Material: S45C φ200 16-groove steel Machining Condition: WET Evaluation Item: Check the number of impacts (times) until the cutting edge breaks using the first acute-angle corner.

[0122] (Cutting Test 2: Wear Resistance Evaluation) Machining Method: Turning Cutting Speed: 300 m / min Feed Rate: 0.3 mm / rev Depth of Cut: 1.5 mm Workpiece Material: SCM435 φ200 round bar Machining Condition: WET Evaluation Item: Check the wear width (mm) at 21 min of machining time using the second obtuse-angle corner.

[0123] The evaluation results are shown in Table 3. Note that "Number of impacts until cutting edge breakage (times)" in Cutting Test 1 in Table 3 represents the number of impacts until the cutting edge breaks during the cutting process, and can also be called an intermittent performance evaluation.

[0124]

[0125]

[0126]

[0127] Samples No. 1 to 3 showed high abrasion resistance and fracture resistance.

[0128] 1...Covering tool 3...Substrate 5...Surface 7...Covering layer 9...Top surface 11...Acute corner 13...Obtuous corner 15...First acute corner (first corner) 17...Second acute corner (fourth corner) 19...First obtuse corner (third corner) 21...Second obtuse corner (second corner) 23...Side surface 25...Cutting edge 27...First side 29...Second side 31...First region 33...Second region 35...Crack 37...TiCN layer 39...Al2O3 layer 41...TiN layer 43...Through hole 101...Cutting tool 103...Holder 103a...First end 103b...Second end 105...Pocket 107...Screw L1...First length L2...Second length W... Crack width

Claims

1. A coating tool comprising a plate-shaped base and a coating layer located on the surface of the base, wherein the coating tool has an upper surface, the upper surface having a first corner and a second corner having a larger angle than the first corner, the residual stress of the coating layer at the first corner being a, the residual stress of the coating layer at the second corner being b, and a and b being different.

2. The coating tool according to claim 1, wherein the relationship between a and b is a < b.

3. The coating tool according to claim 2, wherein a is in the range of -0.2 to 0.3 GPa and b is in the range of 0.2 to 0.5 GPa.

4. The covering tool according to any one of claims 1 to 3, wherein the second corner is adjacent to the first corner.

5. The coating tool according to claim 4, wherein the upper surface is a scooping surface and further comprises a third corner adjacent to the first corner and having a larger angle than the first corner, a first side extending from the first corner toward the third corner, a second side extending from the first corner toward the second corner, a first region located along the first side, and a second region located along the second side, wherein the residual stress of the coating layer in the first region and the second region is in the range of -0.2 to 0.3 GPa, the length of the first region in the direction along the first side is defined as the first length, the length of the second region in the direction along the second side is defined as the second length, and the first length and the second length are different.

6. The covering tool according to claim 5, wherein the relationship between the first length and the second length is such that the first length > the second length.

7. The covering tool according to claim 6, wherein the first length is in the range of 8 to 20 mm and the second length is in the range of 6 to 10 mm.

8. The coating tool according to any one of claims 1 to 7, wherein the surface roughness of the coating layer at the first corner is smaller than the surface roughness of the coating layer at the second corner.

9. The coating tool according to any one of claims 1 to 8, wherein R-honing is provided on the first corner and the second corner, and the R-honing of the first corner is larger than the R-honing of the second corner.

10. The coating tool according to any one of claims 1 to 9, wherein the thickness of the coating layer at the first corner is smaller than the thickness of the coating layer at the second corner.

11. The coating tool according to any one of claims 1 to 10, wherein the coating layer at the first corner and the second corner has cracks that open on the surface of the coating layer, and the width of the crack in the coating layer at the first corner is greater than the width of the crack in the coating layer at the second corner.

12. The coating tool according to any one of claims 1 to 11, wherein the coating layer comprises, in order from the substrate, a TiCN layer and an Al2O3 layer.

13. The coating tool according to any one of claims 1 to 11, wherein the coating layer comprises, in order from the substrate, a TiN layer, a TiCN layer, and an Al2O3 layer.

14. A cutting tool comprising: a holder extending from a first end toward a second end and having a pocket on the side of the first end; and a covering tool according to any one of claims 1 to 13, positioned in the pocket.

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