CN117813172A

CN117813172A - Covering tool and cutting tool

Info

Publication number: CN117813172A
Application number: CN202280054577.3A
Authority: CN
Inventors: 森聪史
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2021-08-31
Filing date: 2022-08-03
Publication date: 2024-04-02
Also published as: WO2023032582A1

Abstract

The overlay tool of the present disclosure is an overlay tool having a substrate and an overlay layer located on at least a portion of a surface of the substrate. In the covering tool according to one embodiment of the present disclosure, 15 times of hardness are measured at 5 points of different depths in the measurement range while changing the pressing load of the pressing head with a measurement range from the surface of the covering layer to a depth of 20% of the thickness of the covering layer, and in this case, the coefficient of variation (standard deviation/average value) of the hardness obtained from the average value and standard deviation of the measured values of 15 times is 0.11 or less in each depth.

Description

Covering tool and cutting tool

Technical Field

The present disclosure relates to a cover tool and a cutting tool.

Background

As a tool used for cutting such as turning and milling, for example, a coated tool having a base body such as cemented carbide, cermet, ceramics, or boron nitride sintered compact is known (see patent document 1).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2002-3284

Disclosure of Invention

One embodiment of the present disclosure is a cover tool having a substrate and a cover layer located on at least a portion of a surface of the substrate. In the covering tool according to one embodiment of the present disclosure, the indentation load of the indenter is changed in a measurement range from the surface of the covering layer to a depth of 20% of the thickness of the covering layer, and 15 times of hardness are measured at 5 points of different depths in the measurement range, respectively, and in this case, the coefficient of variation (standard deviation/average value) of the hardness obtained from the average value and standard deviation of the measured values of 15 times is 0.11 or less for each depth.

Drawings

Fig. 1 is a perspective view showing an example of a covering tool according to the embodiment.

Fig. 2 is a side cross-sectional view showing an example of a covering tool according to the embodiment.

Fig. 3 is a schematic enlarged view of the portion III shown in fig. 2.

Fig. 4 is a schematic enlarged view of the VI portion shown in fig. 3.

Fig. 5 is a front view showing an example of a cutting tool according to the embodiment.

FIG. 6 is a table summarizing the results of hardness measurements for samples No.1 to No. 7.

Fig. 7 is a table summarizing standard deviation, coefficient of variation, and coefficient of variation differences calculated based on the results of hardness measurements for samples nos. 1 to 7.

FIG. 8 is a table summarizing the results of cutting tests for samples No.1 to No. 3.

Detailed Description

Hereinafter, a mode (hereinafter, referred to as "embodiment") for implementing the covering tool and the cutting tool of the present disclosure will be described in detail with reference to the accompanying drawings. The covering tool and the cutting tool of the present disclosure are not limited to this embodiment. The embodiments can be appropriately combined within a range where the processing contents are not contradictory. In the following embodiments, the same reference numerals are given to the same parts, and overlapping description is omitted.

In the embodiments described below, expressions such as "fixed", "orthogonal", "perpendicular" and "parallel" are sometimes used, but these expressions do not need to be strictly "fixed", "orthogonal", "perpendicular" and "parallel". That is, the above expressions allow variations in manufacturing accuracy, setting accuracy, and the like, for example.

In the above-described conventional techniques, there is room for further improvement in terms of improving the quality of the finished surface of the workpiece without impairing the durability.

< covering tool >

Fig. 1 is a perspective view showing an example of a covering tool according to the embodiment. As shown in fig. 1, the covering tool 1 according to the embodiment may include a bit body 2 and a cutting edge portion 3. The covering tool 1 according to the embodiment has a hexahedral shape with a parallelogram shape on the upper surface and the lower surface (the surface intersecting the Z axis shown in fig. 1), for example.

The covering tool 1 has a first surface 6 (here, an upper surface), a second surface 7 (here, a side surface) connected to the first surface 6, and a ridge portion 8 located between the first surface 6 and the second surface 7. The first surface 6 has a rake surface for scooping up chips generated by cutting. In addition, the second face 7 has a flank.

The first surface 6 has a plurality of (four in this case) corners 61 in plan view. The corner 61 is a region including the corner of the first face 6. The cutting edge 11 is located in the ridge portion 8 in at least one of the plurality of corner portions 61. The covering tool 1 cuts a material to be cut by bringing the cutting edge 11 into contact with the material to be cut.

(cutter head body 2)

The bit body 2 is formed of cemented carbide, for example. Cemented carbide contains W (tungsten), specifically WC (tungsten carbide). The cemented carbide may contain at least one of Ni (nickel) and Co (cobalt). The bit body 2 may be formed of cermet. The cermet contains, for example, ti (titanium), specifically TiC (titanium carbide) or TiN (titanium nitride). The cermet may contain Ni and Co.

One of the portions of the bit body 2 corresponding to the corner portions 61 of the covering tool 1 may have a seating surface 4 for mounting the cutting edge portion 3. Further, a through hole 5 penetrating the bit body 2 up and down may be provided in the central portion of the bit body 2. Screws 75 (see fig. 5) for attaching the covering tool 1 to a holder 70 described later are inserted into the through holes 5.

(cutting edge portion 3)

The cutting edge portion 3 is integrated with the bit body 2 by being attached to the seating surface 4 of the bit body 2. The cutting edge 3 is formed to cover one of the corners 61 of the tool 1. The cutting edge portion 3 forms a part of the first surface 6, the second surface 7, and the ridge portion 8. The cutting edge 11 is located at least in part of the ridge line portion 8 of the cutting edge portion 3.

The structure of the cutting edge portion 3 will be described with reference to fig. 2. Fig. 2 is a side cross-sectional view showing an example of the covering tool 1 according to the embodiment. As shown in fig. 2, the cutting edge portion 3 has a base body 10. Further, the cutting edge portion 3 has a coating layer 20 located on at least a part of the surface of the base body 10.

(substrate 10)

The substrate 10 may be cemented carbide, cermet, ceramic. The substrate 10 may be a boron nitride sintered body containing a plurality of boron nitride particles. In an embodiment, the base 10 may be a cubic boron nitride (cBN) sintered body containing a plurality of cubic boron nitride particles. The substrate 10 may have a composition TiN, al, al between a plurality of boron nitride particles ₂ O ₃ Etc. The plurality of boron nitride particles are firmly bonded by the bonding phase. In addition, the matrix 10 need not necessarily have a binding phase.

The third surface 9 continuous with the first surface 6 and the second surface 7 may be located on at least a part of the cutting edge 11. The third surface 9 may be, for example, a C surface (chamfer surface) that cuts the corners of the first surface 6 and the second surface 7 obliquely and linearly. The third surface 9 may be an R surface (rounded surface) formed by rounding the corners of the first surface 6 and the second surface 7. In addition, the cutting edge 11 does not necessarily have to have the third face 9.

A substrate 30, for example, made of cemented carbide or cermet, may also be located on the lower surface of the base body 10. In this case, the base body 10 is bonded to the seating surface 4 of the bit body 2 via the substrate 30 and the bonding material 40. The joining material 40 is, for example, a brazing material. The base body 10 may be bonded to the bit body 2 via the bonding material 40 at a portion other than the seating surface 4 of the bit body 2.

(cover layer 20)

The cover layer 20 covers the base 10 for the purpose of improving wear resistance, heat resistance, and the like of the cutting edge portion 3, for example. In the example of fig. 2, the cover layer 20 is located on both the bit body 2 and the base body 10, but the cover layer 20 may be located at least on the base body 10. When the cover layer 20 is located on the side surface of the base body 10 corresponding to the second surface 7 of the cutting edge portion 3, the second surface 7 has high wear resistance and heat resistance.

In the covering tool 1 according to the embodiment, the hardness is measured 15 times at 5 points of different depths by pressing the indenter from the surface of the covering layer 20 to 20% of the depth of the covering layer 20 while changing the pressing load of the indenter with the surface of the covering layer 20 as the measurement start point, and in this case, the coefficient of variation (standard deviation/average value) of the hardness, which is obtained from the average value and standard deviation of the measured values 15 times, may be 0.11 or less for each depth.

The covering tool 1 having this structure can improve the quality of the finished surface of the workpiece without impairing the durability. Further, the hardness of the cover layer 20 of the cover tool 1 having this structure is uniform. If the hardness of the cover layer 20 is uniform, the wear of the cutting edge during processing becomes uniform. As a result, the quality of the finished surface of the workpiece is improved.

The difference between the maximum value and the minimum value of the variation coefficient in the cover layer 20 may be 0.06 or less. In the covering tool 1 having this structure, the hardness of the covering layer 20 is also uniform in the depth direction. As a result, the wear of the cutting edge during machining becomes more uniform, and the quality of the finished surface of the workpiece is further improved.

The average value of the 15 measured values may be 25GPa or more at each depth. The covering tool 1 having this structure has high hardness, and the wear resistance of the edge is improved, so that the machining variation of the machined surface is reduced. As a result, the surface quality of the workpiece is improved.

The average value of 15 measured values may be 30GPa or more at each depth. The hardness of the covering tool 1 having this structure is higher, the wear resistance of the edge is further improved, and the machining variation of the machined surface is smaller. As a result, the surface quality of the workpiece is improved.

The arithmetic average roughness Ra of the cover layer 20 may be 0.2 μm or less. The covering tool 1 having this structure can improve the quality of the finished surface of the workpiece without impairing the durability.

(specific structure of the cover layer 20)

Next, a specific structure of the cover layer 20 is described with reference to fig. 3. Fig. 3 is a schematic enlarged view of the portion III shown in fig. 2.

As shown in fig. 3, the cover layer 20 has at least a hard layer 21. The hard layer 21 may have 1 or more metal nitride layers. The hard layer 21 is a layer having superior abrasion resistance to the intermediate layer 22 described later. The hard layer 21 may be 1 layer or a plurality of metal nitride layers may be stacked. Specifically, the hard layer 21 may have a first hard layer 23 in which a plurality of metal nitride layers are stacked, and a second hard layer 24 located above the first hard layer 23. The hard layer 21 has a structure described below.

(intermediate layer 22)

In addition, the cover layer 20 may also have an intermediate layer 22. The intermediate layer 22 may also be located between the substrate 10 and the hard layer 21. Specifically, the intermediate layer 22 may be connected to the base 10 on one side and connected to the hard layer 21 on the other side.

The adhesion between the intermediate layer 22 and the substrate 10 is higher than that between the hard layer 21. As the metal element having such characteristics, for example, zr, V, cr, W, al, si, Y can be given. The intermediate layer 22 contains at least one or more of the above metal elements.

In addition, a monomer of Ti, a monomer of Zr, a monomer of V, a monomer of Cr, and a monomer of Al are not used as the intermediate layer 22. This is because they have low melting points and low oxidation resistance, and are therefore unsuitable for use in cutting tools. Further, the adhesion between the monomer of Hf, the monomer of Nb, the monomer of Ta, and the monomer of Mo and the base 10 is low. However, for an alloy including Ti, zr, V, cr, ta, nb, hf, al, this is not limiting.

The intermediate layer 22 may be an al—cr alloy layer containing an al—cr alloy. The intermediate layer 22 has particularly high adhesion to the substrate 10, and therefore has a high effect of improving the adhesion between the substrate 10 and the cover layer 20.

In the case where the intermediate layer 22 is an al—cr alloy layer, the content of Al in the intermediate layer 22 may be larger than the content of Cr in the intermediate layer 22. For example, the composition ratio (at%) of Al to Cr in the intermediate layer 22 may be 70:30. by setting the composition ratio as described above, the adhesion between the base 10 and the intermediate layer 22 is higher.

The intermediate layer 22 may contain a component other than the metal element (Zr, V, cr, W, al, si, Y). However, from the viewpoint of adhesion to the substrate 10, the intermediate layer 22 may contain at least 95 atomic% or more of the above metal element in total. More preferably, the intermediate layer 22 contains 98 at% or more of the above metal element in total. For example, when the intermediate layer 22 is an al—cr alloy layer, the intermediate layer 22 may contain at least 95 at% or more of Al and Cr in total. Further, the intermediate layer 22 may contain at least 98 at% or more of Al and Cr in total. For example, it can be determined by analysis using EDS (energy dispersive X-ray spectroscopy) attached to STEM (scanning transmission electron microscope).

Further, since Ti has poor wettability with the base 10 according to the embodiment, it is preferable that Ti is not contained in the intermediate layer 22 as much as possible from the viewpoint of improving adhesion with the base 10. Specifically, the Ti content in the intermediate layer 22 may be 15 at% or less.

In this way, in the covering tool 1 according to the embodiment, the intermediate layer 22 having higher wettability with the base 10 than the hard layer 21 is provided between the base 10 and the hard layer 21, so that the adhesion between the base 10 and the covering layer 20 can be improved. Further, since the adhesion between the intermediate layer 22 and the hard layer 21 is also high, the hard layer 21 is not likely to be peeled off from the intermediate layer 22.

In addition, cBN used as the base 10 is an insulator. cBN as an insulator has room for improvement in adhesion to a film formed by PVD (physical vapor deposition). In contrast, in the covering tool 1 according to the embodiment, the intermediate layer 22 having conductivity is provided on the surface of the base 10, so that the adhesion between the hard layer 21 formed by PVD and the intermediate layer 22 is high.

(hard layer 21)

Next, the structure of the hard layer 21 will be described with reference to fig. 3 and 4. Fig. 4 is a schematic enlarged view of the IV portion shown in fig. 3.

As shown in fig. 3, the hard layer 21 has a first hard layer 23 located on the intermediate layer 22 and a second hard layer 24 located on the first hard layer 23.

(first hard layer 23)

The first hard layer 23 may contain a crystal of a cubic crystal including at least one element selected from group 4 elements, group 5 elements, and group 6 elements of the periodic table, and Al, si, B, Y and Mn, and at least one element selected from C, N and O.

Specifically, the first hard layer 23 may have a plurality of first metal nitride layers 23a and a plurality of second metal nitride layers 23b. The first hard layer 23 may have a structure in which the first metal nitride layers 23a and the second metal nitride layers 23b are alternately stacked.

The thicknesses of the first metal nitride layer 23a and the second metal nitride layer 23b may be 50nm or less, respectively. In this way, by forming the first metal nitride layer 23a and the second metal nitride layer 23b thin, the residual stress of the first metal nitride layer 23a and the second metal nitride layer 23b is small. As a result, peeling, cracking, and the like of the first metal nitride layer 23a and the second metal nitride layer 23b are less likely to occur, for example, and thus the durability of the cover layer 20 is high.

The first metal nitride layer 23a is a layer in contact with the intermediate layer 22, and the second metal nitride layer 23b is formed on the first metal nitride layer 23 a.

The first metal nitride layer 23a and the second metal nitride layer 23b may contain a metal included in the intermediate layer 22.

For example, it is assumed that two metals (herein, "first metal", "second metal") are included in the intermediate layer 22. In this case, the first metal nitride layer 23a contains nitrides of the first metal and the third metal. The third metal is a metal not included in the intermediate layer 22. Further, the second metal nitride layer 23b contains nitrides of the first metal and the second metal.

For example, in the embodiment, the intermediate layer 22 may contain Al and Cr. In this case, the first metal nitride layer 23a may contain Al. Specifically, the first metal nitride layer 23a may be an AlTiN layer containing AlTiN, which is a nitride of Al and Ti. The second metal nitride layer 23b may be an AlCrN layer containing AlCrN as a nitride of Al and Cr.

In this way, by positioning the first metal nitride layer 23a containing the metal contained in the intermediate layer 22 on the intermediate layer 22, the adhesion between the intermediate layer 22 and the hard layer 21 is high. Thus, the hard layer 21 is hard to peel from the intermediate layer 22, and thus the durability of the cover layer 20 is high.

The AlTiN layer, which is the first metal nitride layer 23a, is excellent in, for example, abrasion resistance in addition to the adhesion to the intermediate layer 22. The second metal nitride layer 23b, i.e., the AlCrN layer, is excellent in heat resistance and oxidation resistance, for example. In this way, the coating layer 20 includes the first metal nitride layer 23a and the second metal nitride layer 23b having different compositions, so that the wear resistance, heat resistance, and other characteristics of the hard layer 21 can be controlled. This can extend the tool life of the covering tool 1. For example, in the hard layer 21 according to the embodiment, mechanical properties such as adhesion to the intermediate layer 22 and abrasion resistance can be improved while maintaining excellent heat resistance of AlCrN.

The first hard layer 23 may be formed by, for example, arc ion plating (AIP method). The AIP method is a method of forming a metal nitride (AlTiN and AlCrN herein) by evaporating a target metal (AlTi target and AlCr target herein) by arc discharge in a vacuum atmosphere and combining the metal nitride with N2 gas. The intermediate layer 22 may be formed by an AIP method.

The second hard layer 24 may also be located above the first hard layer 23. Specifically, the second hard layer 24 is in contact with the second metal nitride layer 23b in the first hard layer 23. The second hard layer 24 is, for example, a metal nitride layer (AlTiN layer) containing Ti and Al, similarly to the first metal nitride layer 23 a.

The thickness of the second hard layer 24 may be thicker than the thicknesses of the first metal nitride layer 23a and the second metal nitride layer 23b. Specifically, as described above, when the thicknesses of the first metal nitride layer 23a and the second metal nitride layer 23b are 50nm or less, the thickness of the second hard layer 24 may be 1 μm or more. For example, the thickness of the second hard layer 24 may also be 1.2 μm.

Thus, for example, when the friction coefficient of the second hard layer 24 is low, the welding resistance of the covering tool 1 can be improved. Further, for example, when the hardness of the second hard layer 24 is high, the wear resistance of the covering tool 1 can be improved. Further, for example, when the oxidation start temperature of the second hard layer 24 is high, the oxidation resistance of the covering tool 1 can be improved.

The thickness of the second hard layer 24 may be thicker than the thickness of the first hard layer 23. Specifically, in the embodiment, when the thickness of the first hard layer 23 is 0.5 μm or less, the thickness of the second hard layer 24 may be 1 μm or more. For example, in the case where the thickness of the first hard layer 23 is 0.3 μm, the thickness of the second hard layer 24 may be 1.2 μm. By making the second hard layer 24 thicker than the first hard layer 23 in this way, the above-described effects of improving the weld resistance, abrasion resistance, and the like are enhanced.

The thickness of the intermediate layer 22 may be, for example, 0.1 μm or more and less than 0.6 μm. That is, the intermediate layer 22 may be thicker than each of the first metal nitride layer 23a and the second metal nitride layer 23b and thinner than the first hard layer 23.

< cutting tool >

Next, a structure of a cutting tool including the covering tool 1 will be described with reference to fig. 5. Fig. 5 is a front view showing an example of a cutting tool according to the embodiment.

As shown in fig. 5, a cutting tool 100 according to the embodiment includes a cover tool 1 and a holder 70 for fixing the cover tool 1.

The holder 70 is a rod-shaped member extending from a first end (upper end in fig. 5) toward a second end (lower end in fig. 5). The holder 70 is made of steel or cast iron, for example. Particularly, steel having high toughness is preferably used for these members.

The holder 70 has a pocket 73 at the first end side end. The pocket 73 is a portion to which the covering tool 1 is attached, and has a seating surface intersecting the rotation direction of the workpiece and a restraining side surface inclined with respect to the seating surface. The seating surface is provided with a screw hole into which a screw 75 to be described later is screwed.

The covering tool 1 is positioned in the pocket 73 of the holder 70 and is fitted to the holder 70 by means of screws 75. That is, the screw 75 is inserted into the through hole 5 of the covering tool 1, and the tip of the screw 75 is inserted into a screw hole formed in the seating surface of the pocket 73, so that the screw portions are screwed together. Thereby, the covering tool 1 is fitted to the holder 70 such that the cutting edge portion 3 protrudes outward from the holder 70.

In the embodiment, a cutting tool for so-called turning work is exemplified. Examples of the turning include an inner diameter machining, an outer diameter machining, and a grooving machining. The cutting tool is not limited to a tool used for turning. For example, the covering tool 1 may also be used for a cutting tool used in milling. Examples of the cutting tool used for milling include milling tools such as a face milling tool, a side milling tool, and a slotting milling tool, and end milling tools such as a single-blade end milling tool, a multi-blade end milling tool, a tapered-blade end milling tool, and a ball end milling tool.

Example (example)

A cubic boron nitride sintered body containing a cubic boron nitride powder, a Ti compound and an Al compound as a binder phase is produced, and the obtained cubic boron nitride sintered body is bonded to a seat surface of a bit body made of cemented carbide via a bonding material.

Specifically, first, a TiN raw material powder of 72 to 82% by volume, an Al raw material powder of 13 to 23% by volume, and an Al of 1 to 11% by volume were prepared ₂ O ₃ Raw material powder. Next, an organic solvent is added to each of the raw material powders prepared. As the organic solvent, alcohols such as acetone and isopropyl alcohol (IPA) can be used. Then, the mixture is pulverized and mixed by a ball mill for 20 to 24 hours. After pulverization and mixing, the solvent was evaporated, thereby obtaining a first mixed powder.

Further, a volume ratio of cBN powder having an average particle diameter of 2.5 μm or more and 4.5 μm or less to cBN powder having an average particle diameter of 0.5 μm or more and 1.5 μm or less is 8 or more and 9 or less: 1 to 2. Next, an organic solvent is added to the blended powder. As the organic solvent, alcohols such as acetone and IPA can be used. Then, the mixture is pulverized and mixed by a ball mill for 20 to 24 hours. After pulverization and mixing, the solvent was evaporated, thereby obtaining a second mixed powder.

Next, the obtained first mixed powder and second mixed powder were mixed at a volume ratio of 68 or more and 78 or less: the ratio of 22 to 32 is set. An organic solvent and an organic binder are added to the formulated powder. As the organic solvent, alcohols such as acetone and IPA can be used. Further, as the organic binder, paraffin wax, acrylic resin, or the like can be used. Then, the mixture is pulverized and mixed with a ball mill for 20 to 24 hours, and then the organic solvent is evaporated, whereby a third mixed powder is obtained. In the step of using the ball mill, a dispersant may be added as needed.

Then, the third mixed powder is molded into a given shape, thereby obtaining a molded body. The molding may be performed by a known method such as uniaxial pressing or Cold Isostatic Pressing (CIP). The molded article is heated at a predetermined temperature in the range of 300 ℃ to 600 ℃ inclusive, and the organic binder is evaporated.

Next, the molded article is placed in an ultrahigh pressure heating device, and heated at a pressure of 4GPa or more and 6GPa or less for 15 minutes or more and 30 minutes or less at 1200 ℃ or more and 1500 ℃ or less. Thus, a cubic boron nitride sintered body according to the embodiment was obtained. Then, the obtained cubic boron nitride sintered body was mounted on a seat surface of a bit body made of cemented carbide via a joining material.

Next, a coating layer was formed on the surface of the chip by Physical Vapor Deposition (PVD). Then, the cover layer was subjected to aeromap (registered trademark) treatment under the conditions shown below, thereby producing sample No.1 (example 1). Further, a coating tool which did not perform aeromap (registered trademark) treatment on the coating layer after film formation was used as sample No.2 (comparative example 1). Further, a commercially available covering tool having cBN as a base was prepared as sample No.3 (comparative example 2).

Further, a coating layer was formed on the surface of cemented carbide (wc—co alloy) by physical vapor deposition, and then aerolpa (registered trademark) treatment was performed on the coating layer under the conditions shown below, thereby producing sample No.4 (example 2). Further, a coating tool which did not perform aeromap (registered trademark) treatment on the coating layer after film formation was used as sample No.5 (comparative example 3), sample No.6 (comparative example 4) and sample No.7 (comparative example 5).

< conditions for Aerolap (registered trademark) treatment >

The device comprises: aerolap (registered trademark) manufactured by Japanese speedshore company

Medium: multi-angle

Diameter of medium: 0.1-0.5 mm

Blade inverter frequency: 40Hz

Injection time: 0 seconds (no treatment, sample No.2, no.3, no.5 to No. 7), 10 seconds (sample No.1, no. 4)

Wet/dry: wet type

In addition, the medium is ejected by the rotation of the blade portion. The rotational speed of the blade portion was controlled to 40Hz (40 revolutions per second) by an inverter.

Next, hardness was measured using a micro indentation hardness tester "ENT-1100b/a" (manufactured by eioninc, inc.) using a depth of 20% of the thickness of the cover layer from the surface of the cover layer as a measurement range for each sample, and the indentation load of the indenter was varied in a 10N scale from 10N to 50N, thereby measuring hardness (nano indentation test).

Specifically, after bringing the indenter into contact with the surface of the cover layer, the displacement of the indenter (change in the indentation depth) when the load is changed by measuring the flow of load application, maximum load holding, and unloading is performed, thereby obtaining a load displacement curve. Then, the hardness is calculated from the resulting load displacement curve. A series of measurements were performed 15 times each using pressing loads (maximum loads) 10N, 20N, 30N, 40N, and 50N (i.e., 5 points at different depths), and the average of the measured values of the hardness of 15 times was taken as the hardness under the pressing load.

In order to confirm the effect of aerolpa (registered trademark) treatment, the hardness was also measured on the cubic boron nitride sintered body of the cutting edge and the coating layer on the cemented carbide of the cutting edge main body.

FIG. 6 is a table summarizing the results of hardness measurements for samples No.1 to No. 7. As shown in FIG. 6, among samples No.1 to No.7, samples No.1 to No.3 had a matrix composed of cBN, and samples No.4 to No.7 had a matrix composed of cemented carbide (WC-Co-based alloy). The thickness (average thickness) of the coating layer was 3.0 μm in each of samples No.1 to No. 7. In contrast to the example in which aerolpa (registered trademark) was applied to the cover layers in sample nos. 1 and 4, the comparative example in which aerolpa (registered trademark) was not applied to the cover layers in sample nos. 2, 3, and 5 to 7.

The "ratio of press depth to average thickness 1" shown in fig. 6 is a ratio of the maximum press depth of the indenter to the average thickness of the cover layer, where the press load is 10N. Similarly, the ratio 2 to the ratio 5 of the press depth to the average thickness are ratios of the maximum press depth of the indenter to the average thickness of the cover layer, respectively, in the case where the press loads are 20N, 30N, 40N, and 50N.

The ratio of the pressing depth to the average thickness of sample No.1 was 4.6%, 6.8%, 8.6%, 9.9% and 11.1%, respectively. The ratio of the pressing depth to the average thickness of sample No.2 was 5.5%, 8.4%, 10.1%, 12.3% and 12.9%, respectively. The ratio of the pressing depth to the average thickness of sample No.3 was 5.5%, 8.4%, 10.1%, 12.3% and 12.9%, respectively. The ratio of the pressing depth to the average thickness of sample No.4 was 4.6%, 6.5%, 8.2%, 9.7% and 11.0%, respectively. The ratio of the pressing depth to the average thickness was 4.6%, 6.6%, 8.6%, 10.0% and 11.2% for sample No.5, respectively. The ratio of the pressing depth to the average thickness was 4.7%, 6.8%, 8.8%, 10.6% and 12.5% for sample No.6, respectively. The ratio of the pressing depth to the average thickness was 5.0%, 6.7%, 8.5%, 10.2% and 11.8% for sample No.7, respectively.

The "hardness 1" shown in fig. 6 is an average of measured values of 15 measurements performed with the press-in load set to 10N. Similarly, the hardness 2 to hardness 5 are averages of measured values of 15 measurements performed with the press-in loads set to 20N, 30N, 40N, and 50N, respectively.

In the hardness of sample No.1, the hardness 1 was 28.7GPa, the hardness 2 was 28.5GPa, the hardness 3 was 27.8GPa, the hardness 4 was 28.1GPa, and the hardness 5 was 28.5GPa. In the hardness of sample No.2, the hardness 1 was 12.9GPa, the hardness 2 was 20.0GPa, the hardness 3 was 20.7GPa, the hardness 4 was 20.1GPa, and the hardness 5 was 20.8GPa. In the hardness of sample No.3, the hardness 1 was 29.9GPa, the hardness 2 was 32.2GPa, the hardness 3 was 30.8GPa, the hardness 4 was 30.4GPa, and the hardness 5 was 31.1GPa.

In the hardness of sample No.4, the hardness 1 was 30.2GPa, the hardness 2 was 31.7GPa, the hardness 3 was 32.1GPa, the hardness 4 was 30.5GPa, and the hardness 5 was 31.2GPa. In the hardness of sample No.5, the hardness 1 was 29.2GPa, the hardness 2 was 30.7GPa, the hardness 3 was 28.7GPa, the hardness 4 was 29.5GPa, and the hardness 5 was 29.2GPa. In the hardness of sample No.6, the hardness 1 was 27.6GPa, the hardness 2 was 27.4GPa, the hardness 3 was 25.3GPa, the hardness 4 was 23.8GPa, and the hardness 5 was 22.0GPa. In the hardness of sample No.7, the hardness 1 was 24.5GPa, the hardness 2 was 29.1GPa, the hardness 3 was 27.5GPa, the hardness 4 was 26.8GPa, and the hardness 5 was 25.2GPa.

Thus, the hardness of sample No.1 subjected to aerolpa (registered trademark) was 25GPa or more in all of the hardness 1 to 5 (in other words, in each press-in depth). In contrast, the hardness of sample No.2, which was not subjected to aerolpa (registered trademark) treatment, was less than 25GPa in all of the hardness 1 to 5. Thus, it was found that sample No.1 subjected to the Aerolap (registered trademark) treatment had higher hardness than sample No.2 not subjected to the Aerolap (registered trademark) treatment.

"σ1" shown in fig. 7 is the standard deviation of the measured value of 15 measurements performed with the press-in load (maximum load) 10N. Specifically, the square of the difference between each measured value and the average value (i.e., hardness 1) of 15 times was averaged, and the positive square root thereof was calculated as σ1. Similarly, σ2 to σ5 are standard deviations of measurement values of 15 measurements performed by the press-in loads 20N, 30N, 40N, and 50N, respectively.

In sample No.1, in the standard deviation of hardness, σ1 was 2.49GPa, σ2 was 2.29GPa, σ3 was 2.79GPa, σ4 was 2.78GPa, and σ5 was 1.71GPa. In the sample No.2, in the standard deviation of hardness, σ1 was 8.32GPa, σ2 was 8.70GPa, σ3 was 8.88GPa, σ4 was 12.27GPa, and σ5 was 7.17GPa. Regarding sample No.3, in the standard deviation of hardness, σ1 was 4.42GPa, σ2 was 4.50GPa, σ3 was 4.13GPa, σ4 was 4.16GPa, and σ5 was 3.84GPa.

In sample No.4, in the standard deviation of hardness, σ1 was 2.70GPa, σ2 was 2.70GPa, σ3 was 2.70GPa, σ4 was 1.92GPa, and σ5 was 2.71GPa. Regarding sample No.5, in the standard deviation of hardness, σ1 was 5.82GPa, σ2 was 4.11Gpa, σ3 was 5.77GPa, σ4 was 4.95GPa, and σ5 was 4.17GPa. Regarding sample No.6, in the standard deviation of hardness, σ1 was 4.00GPa, σ2 was 4.23GPa, σ3 was 4.47GPa, σ4 was 4.72GPa, and σ5 was 4.17GPa. In sample No.7, in the standard deviation of hardness, σ1 was 7.46GPa, σ2 was 4.96GPa, σ3 was 7.56GPa, σ4 was 5.31GPa, and σ5 was 5.25GPa.

The "coefficient of variation 1" shown in fig. 7 is a value obtained by dividing the standard deviation σ1 by the hardness 1 (standard deviation σ1/hardness 1). Similarly, the coefficient of variation 2 is a value obtained by dividing the standard deviation σ2 by the hardness 2, the coefficient of variation 3 is a value obtained by dividing the standard deviation σ3 by the hardness 3, the coefficient of variation 4 is a value obtained by dividing the standard deviation σ4 by the hardness 4, and the coefficient of variation 5 is a value obtained by dividing the standard deviation σ5 by the hardness 5.

For sample No.1, the coefficient of variation 1 was 0.09, the coefficient of variation 2 was 0.08, the coefficient of variation 3 was 0.10, the coefficient of variation 4 was 0.10, and the coefficient of variation 5 was 0.06. For sample No.2, the coefficient of variation 1 was 0.42, the coefficient of variation 2 was 0.43, the coefficient of variation 3 was 0.43, the coefficient of variation 4 was 0.61, and the coefficient of variation 5 was 0.34. For sample No.3, the coefficient of variation 1 was 0.15, the coefficient of variation 2 was 0.14, the coefficient of variation 3 was 0.13, the coefficient of variation 4 was 0.14, and the coefficient of variation 5 was 0.12.

For sample No.4, the coefficient of variation 1 was 0.09, the coefficient of variation 2 was 0.09, the coefficient of variation 3 was 0.08, the coefficient of variation 4 was 0.06, and the coefficient of variation 5 was 0.09. For sample No.5, the coefficient of variation 1 was 0.20, the coefficient of variation 2 was 0.13, the coefficient of variation 3 was 0.20, the coefficient of variation 4 was 0.17, and the coefficient of variation 5 was 0.14. Regarding sample No.6, the coefficient of variation 1 was 0.15, the coefficient of variation 2 was 0.15, the coefficient of variation 3 was 0.18, the coefficient of variation 4 was 0.20, and the coefficient of variation 5 was 0.23. For sample No.7, the coefficient of variation 1 was 0.30, the coefficient of variation 2 was 0.17, the coefficient of variation 3 was 0.27, the coefficient of variation 4 was 0.20, and the coefficient of variation 5 was 0.21.

In this way, the variation coefficient of samples No.1 and No.4 as examples was 0.11 or less in any of the variation coefficients 1 to 5 (i.e., in all the measured press-in depths). In contrast, the coefficients of variation of samples No.2, no.3, no.5 to No.7 as comparative examples were all larger than 0.11 in the coefficients of variation 1 to 5. From the results, it was found that the coating layers of sample nos. 1 and 4 as examples have smaller variation in hardness due to the measurement site, in other words, have more uniform hardness, than the coating layers of sample nos. 2, 3, and 5 to 7 as comparative examples.

Further, cutting tests were performed on samples No.1 to No.3 whose base body was cBN. Specifically, the cutting material was subjected to intermittent tests using SCr420H under the following conditions. After the intermittent test, the arithmetic average roughness of the cut surface of the cut material SC420H was measured.

< cutting test conditions >

Material to be cut: SCr420H (phi 70X 50mm, phi 10-8 holes)

Cutting speed Vc:150m/min

Feeding f:0mm/rev

Incision ap:0mm of

Atmosphere: WET (WET-like food)

FIG. 8 is a table summarizing the results of cutting tests for samples No.1 to No. 3. As shown in FIG. 8, concerning samples Nos. 1 to 3, the arithmetic average roughness Ra of the cut surface of the workpiece was 0.69 μm, 1.48 μm and 1.34 μm, respectively.

In this way, the surface roughness of the cut surface was smaller in the cut material cut using sample No.1 as an example than in the cut materials cut using sample nos. 2 and 3 as comparative examples. From the results, it is clear that the coating tool according to the example can improve the quality of the finished surface of the workpiece compared with the coating tool according to the comparative example.

< other embodiments >

In the above-described embodiment, the covering tool 1 in which the base body 10 made of boron nitride particles or the like is attached to the bit body 2 made of cemented carbide or the like and is covered with the covering layer 20 is described. The coating tool of the present disclosure may be, for example, a tool in which all of a hexahedral base body having a parallelogram shape on the upper and lower surfaces is a cubic boron nitride sintered body, and a coating layer is formed on the base body.

In the above-described embodiment, the case where the upper surface and the lower surface of the covering tool 1 are parallelogram-shaped is shown as an example, but the upper surface and the lower surface of the covering tool 1 may be diamond-shaped, square-shaped, or the like. The shape of the upper surface and the lower surface of the covering tool 1 may be triangular, pentagonal, hexagonal, or the like.

The shape of the covering tool 1 may be positive or negative. The positive type is a type in which the side face is inclined with respect to a central axis passing through the center of the upper surface and the center of the lower surface of the covering tool 1, and the negative type is a type in which the side face is parallel with respect to the above central axis.

In the above embodiment, the case where the matrix 10 contains particles of cubic boron nitride ((cBN) is described, but the matrix disclosed in the present application may contain particles of hexagonal boron nitride (hBN), rhombohedral boron nitride (rBN), wurtzite boron nitride (wBN) or the like, and the matrix 10 is not limited to boron nitride, but may be cemented carbide, cermet or the like, for example, the cemented carbide may contain W (tungsten), specifically WC (tungsten carbide), the cemented carbide may contain Ni (nickel) or Co (cobalt), the cermet may contain Ti (titanium), specifically TiC (titanium carbide) or TiN (titanium nitride), and the cermet may contain Ni or Co.

In the above-described embodiment, the case where the covering tool 1 is used for cutting processing has been described, but the covering tool of the present application can be applied to tools other than cutting tools such as tools for excavation and cutters.

As described above, the covering tool (the covering tool 1 as an example) according to the embodiment is a covering tool having a base body (the base body 10 as an example) and a covering layer (the covering layer 20 as an example) located on at least a part of the surface of the base body. In the covering tool according to one embodiment of the present disclosure, the indentation load of the indenter is changed in a measurement range from the surface of the covering layer to a depth of 20% of the thickness of the covering layer, and when the hardness is measured 15 times at 5 points of different depths in the measurement range, the coefficient of variation (standard deviation/average value) of the hardness obtained from the average value and standard deviation of the measured values of 15 times is 0.11 or less for each depth.

Further effects and modifications can be easily derived by 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.

Description of the reference numerals-

1 cover tool

2 cutter head main body

3 cutting edge portion

4 seat surface

5 through holes

8 edge line part

10 matrix

11 cutting edge

20 cover layer

1 hard layer

22 intermediate layer

23 first hard layer

23a first metal nitride layer

23b second metal nitride layer

24 second hard layer

30 substrate

40 bonding material

61 corner part

70 retainer

73 pocket

75 screw

100 cutting tool.

Claims

1. A coating tool having a substrate and a coating layer on at least a portion of a surface of the substrate,

taking the depth from the surface of the covering layer to 20% of the thickness of the covering layer as a measuring range, respectively measuring 15 times of hardness at 5 positions with different depths in the measuring range while changing the pressing load of the pressing head,

in this case, the standard deviation, which is a coefficient of variation in hardness obtained from the average value of the 15 measured values and the standard deviation, is 0.11 or less in each depth.

2. The overlay tool according to claim 1, wherein,

the average value is 25GPa or more in each depth.

3. The overlay tool according to claim 1 or 2, wherein,

the average value is 30GPa or more in each depth.

4. The covering tool according to claim 1 to 3, wherein,

the coating layer has an arithmetic average roughness Ra of 0.2 [ mu ] m or less.

5. The overlay tool according to any one of claims 1-4, wherein,

the coating layer contains a cubic crystal containing at least one element selected from group 4 elements, group 5 elements, and group 6 elements of the periodic table, and Al, si, B, Y and Mn, and at least one element selected from C, N and O.

6. The overlay tool according to claim 5, wherein,

the cap layer has an AlTiN layer containing AlTiN crystals as crystals of the cubic crystal.

7. The overlay tool according to claim 5, wherein,

the cover layer has an AlCrN layer containing AlCrN crystals as crystals of the cubic crystal.

8. The overlay tool according to claim 5, wherein,

the coating layer has a plurality of AlTiN layers containing AlTi crystals and a plurality of AlCrN layers containing AlCrN crystals as crystals of the cubic crystal.

9. The overlay tool according to any one of claims 1-8, wherein,

the substrate is at least one selected from cemented carbide, cermet, ceramics and sintered compact containing cubic boron nitride.

10. A cutting tool is provided with:

a holder extending from a first end toward a second end, the holder having a pocket on the first end side; and

the covering tool of any one of claims 1 to 9 located in the pocket.