Cutting blade of superhard alloy

Abstract

A superhard alloy cutting blade has: a base; and a cutting edge, which is disposed on the extension line of the base and has a cutting tip as the foremost part. The Vickers hardness (HV) is greater than or equal to 1250 and less than or equal to 2030. The thickness of the cutting edge at a position 1 μm from the cutting tip toward the base is defined as T1 μm, and the thickness of the cutting edge at a position 3 μm from the cutting tip toward the base is defined as T2 μm. T1 is greater than or equal to 0.6 and less than or equal to 2.2. Within the range of T1 from 0.6 to 0.9, T1+0.6≤T2≤(10 / 3)T1-0.4; within the range of T1 from 0.9 to 2.2, T1+0.6≤T2≤(15 / 13)T1+(39 / 25).

Description

Technical Field

[0001] This invention relates to a cutting blade made of superhard alloy. This application claims priority to Japanese Patent Application No. 2020-106045, filed June 19, 2020. All descriptions in that Japanese patent application are incorporated herein by reference. Background Technology

[0002] Currently, cutting blades are disclosed in, for example, Japanese Patent Application Publication No. 10-217181 (Patent Document 1), Japanese Patent Application Publication No. 2001-158016 (Patent Document 2), International Publication No. 2014 / 050883 (Patent Document 3), International Publication No. 2014 / 050884 (Patent Document 4), Japanese Patent Application Publication No. 2017-42911 (Patent Document 5), and Japanese Patent Application Publication No. 2004-17444 (Patent Document 6).

[0003] Patent Document 1: Japanese Patent Application Publication No. 10-217181

[0004] Patent Document 2: Japanese Patent Application Publication No. 2001-158016

[0005] Patent Document 3: International Publication No. 2014 / 050883

[0006] Patent Document 4: International Publication No. 2014 / 050884

[0007] Patent Document 5: Japanese Patent Application Publication No. 2017-42911

[0008] Patent Document 6: Japanese Patent Application Publication No. 2004-17444 Summary of the Invention

[0009] The superhard alloy cutting blade of the present invention comprises: a base; and a cutting edge disposed on an extension line of the base, having a cutting tip as the foremost tip, having a Vickers hardness HV greater than or equal to 1250 and less than or equal to 2030, the thickness of the cutting edge at a position 1 μm from the cutting tip toward the base being defined as T1 μm, the thickness of the cutting edge at a position 3 μm from the cutting tip toward the base being defined as T2 μm, and T1 being greater than or equal to 0.6 and less than or equal to 2.2. In the range of T1 from 0.6 to 0.9, T1+0.6≤T2≤(10 / 3)T1-0.4; in the range of T1 from 0.9 to 2.2, T1+0.6≤T2≤(15 / 13)T1+(39 / 25). Attached Figure Description

[0010] Figure 1 This is a longitudinal cross-sectional view of the superhard alloy cutting blade 1 involved in Embodiment 1.

[0011] Figure 2 It is a graph showing the relationship between the thickness T1μm of the cutting edge 120 at a position 1μm away from the cutting tip 121t and the thickness T2μm of the cutting edge 120 at a position 3μm away from the cutting tip 121t in the superhard alloy cutting blade 1.

[0012] Figure 3 This is a longitudinal cross-sectional view of the superhard alloy cutting blade 1 involved in Embodiment 2.

[0013] Figure 4 This is a longitudinal cross-sectional view of the superhard alloy cutting blade 1 involved in Embodiment 3.

[0014] Figure 5 This is a longitudinal cross-sectional view of the superhard alloy cutting blade 1 involved in Embodiment 4.

[0015] Figure 6 This is a perspective view of the apparatus used to illustrate the cutting test.

[0016] Figure 7 It is along Figure 6 A cross-sectional view of line VII-VII in the diagram.

[0017] Figure 8 It is a microscopic photograph (microscope) showing the notch of the cutting edge. Detailed Implementation

[0018] [The problem this invention aims to solve]

[0019] If the cutting edge is too thin, the cutting tip cannot withstand the cutting impact and will produce debris. If the cutting edge is too thick, the cutting resistance is high, the profile quality is poor, and the profile becomes rough.

[0020] [Description of embodiments of the present invention]

[0021] First, the embodiments of the present invention will be described.

[0022] (Implementation Method 1)

[0023] Figure 1 This is a longitudinal cross-sectional view of the superhard alloy cutting blade 1 involved in Embodiment 1. (See attached image.) Figure 1 As shown, the superhard alloy cutting blade 1 has a cutting tip 121t extending along the blade transition direction. Figure 1 It is a cross-section in a direction orthogonal to the cutting edge transition direction. For example... Figure 1 As shown, the flat-edged, superhard alloy cutting blade 1 has a base 110 and a cutting edge 120 as a cutting execution part. A connecting part may be provided between the base 110 and the cutting edge 120.

[0024] (Material)

[0025] The material used for the superhard alloy cutting blade 1 is a superhard alloy with tungsten carbide and cobalt as the main components. The cobalt content used in the superhard alloy is in the range of 3% to 25% by mass. Preferably, the cobalt content is in the range of 5% to 20% by mass. The composition of the elements constituting the superhard alloy is determined by ICP-based spectrophotometry and Co titration. In addition to tungsten carbide and cobalt as the main components, the superhard alloy of the present invention sometimes contains elements such as chromium, vanadium, tantalum, and niobium used to adjust properties such as grain size. The size of the tungsten carbide crystals in the superhard alloy is preferably 0.1 μm to 4 μm. More preferably, the crystal size is less than or equal to 2 μm.

[0026] Furthermore, preferably, the superhard alloy contains TaC (tantalum carbide), a component used to suppress the grain growth of tungsten carbide in the superhard alloy, with a preferred content of 0.1 to 2% by mass. The additives used to suppress grain growth can be V8C7 (vanadium carbide) or Cr3C2 (chromium carbide). At least one of TaC, V8C7, and Cr3C2 can be substituted, or combinations thereof can be made. In this case, the content of each is 0.1 to 2% by mass. The Vickers hardness HV of the superhard alloy is greater than or equal to 1250 and less than or equal to 2030. The Vickers hardness is measured using a Vickers hardness tester.

[0027] (shape)

[0028] The shape of the superhard alloy cutting blade 1 is basically a rectangular plate. The shortest side of the plate is set as the thickness.

[0029] The superhard alloy cutting blade 1 has: a base 110; and a cutting edge 120, which is disposed on the extension line of the base 110 and has a shape that is thinned towards the cutting tip 121t, which is the foremost part.

[0030] Preferably, the thickness of the base 110 is constant. The base 110 has, for example, a thickness of 50 to 1000 μm, the required thickness varying depending on the size of the workpiece being cut. Furthermore, the cutting edge 120 is formed on an edge extending from the base 110. The dimension of the cutting edge 120 in the direction from the cutting edge 120 toward the base 110 (Z-axis direction) is expressed as the width of the cutting edge 120. The dimension in the direction perpendicular to both the cutting transition direction and the width direction of the cutting edge 120 (Y-axis direction) is expressed as the thickness of the cutting edge 120.

[0031] In a longitudinal section orthogonal to the cutting edge transition direction, within a range of 3 μm from the cutting edge tip, the cutting edge 120 has an outwardly convex portion 120t. This convex portion 120t is located further outward than the straight line S connecting the cutting edge 121t and a position at a distance H2 (3 μm) in the width direction from the cutting edge 121t. The presence of the convex portion 120t increases the strength of the cutting edge 120 compared to a straight cutting edge without the convex portion 120t. The convex portion 120t can be square or curved.

[0032] The cutting edge 120 has a first portion 121 and a second portion 122. The first portion 121 and the second portion 122 have outer surfaces 121s and 122s. The outer surfaces 121s and 122s are straight. The outer surfaces 121s and 122s can also be curved. If we compare the angle θ formed by the two outer surfaces 121s in opposite positions and the angle formed by the two outer surfaces 122s in opposite positions, the angle formed by the outer surfaces 122s is smaller than the angle formed by the outer surfaces 121s. This angle increases as the cutting edge 121t approaches. In this embodiment, the outer surfaces 121s and 122s are symmetrical about the center line C. However, the outer surfaces 121s and 122s can also be asymmetrical about the center line C. The slope of the outer surface 121s is different in the part at a distance H1 (1 μm) from the tip 121t and in the part at a distance H2 (3 μm) from the tip 121t.

[0033] The cutting object of the superhard alloy cutting blade 1 is, for example, ceramic raw sheets, metal foil, or hard resin before firing, such as multilayer capacitors or multilayer inductors.

[0034] In extrusion-based cutting, the object to be cut is expanded while being extruded and cut. For example, if the object to be cut is a green ceramic sheet with high density, its hardness increases, making it prone to notching at the cutting edge.

[0035] like Figure 1 As shown, a large load is applied to the tip of a superhard alloy cutting blade 1 that is lowered in the Z-axis direction for cutting. When the blade is thin and the angle between its two outer surfaces 121s is small (i.e., acute), nicks (also called chips) are easily formed. If nicks form, the sharpness naturally decreases, making it unsuitable for cutting and easily scratching the cut surface of the object. While superhard alloys, which have high hardness and low toughness compared to other materials, exhibit excellent resistance to bending and wear compared to other materials, they are particularly prone to nicking.

[0036] To prevent notches in the cutting tip 121t, the inventors of this invention focused on a distance of 1 μm from the foremost point of the cutting tip 121t in the direction of the base 110. Figure 1 H1) and 3μm ( Figure 1 The shape of the cutting tip (H2) in the invention. Through repeated trial and error, the inventors discovered that the initial notch is generated within a range of 1–3 μm from the cutting tip 121t in the base direction, and the size of the notch increases during continuous cutting.

[0037] Sometimes, the defects are caused by machining marks or localized deviations in the material composition. However, by conducting tests to eliminate these causes, it was determined that the following super-hard alloy cutting blade 1 is an effective countermeasure against defects.

[0038] Figure 2 This is a graph showing the relationship between the thickness T1μm of the cutting edge 120 at a position 1μm away from the cutting tip 121t and the thickness T2μm of the cutting edge 120 at a position 3μm away from the cutting tip 121t in a superhard alloy cutting blade 1. T1 is greater than or equal to 0.6 and less than or equal to 2.2. If T1 is less than 0.6, the thickness is excessively reduced, and the strength of the superhard alloy cutting blade 1 cannot be obtained. If T1 exceeds 2.2, the width of the tip of the cutting edge 120 is excessively increased, resulting in cracking on the cutting surface of the object being cut. If T exceeds 2.2, the tip of the cutting edge 120 becomes flat. In this case, it can be seen that the strength of the cutting tip 121t is relatively large, but the stress generated on the cutting tip 121t during cutting becomes too large, and the cutting tip 121t is prone to chipping.

[0039] Within the range of T1 from 0.6 to 0.9, T1+0.6≤T2≤(10 / 3)T1-0.4. If T1+0.6>T2, the angle of the tip of the cutting edge 120 decreases, resulting in good sharpness but making it prone to chipping. If T2>(10 / 3)T1-0.4, T2 becomes excessively larger relative to T1 of the cutting edge 120, thus reducing sharpness and making it prone to stress on the cutting surface, leading to cracks and scratches.

[0040] "The area where the blade strength cannot be obtained" refers to the range where T2 < 3T1. Within this range, it refers to the area where a concave region forms from the blade tip 121t to H2. "The area where the cutting resistance increases due to the increased tip angle (re-attachment, rough cut surface)" refers to the phenomenon of re-attachment of the workpiece after cutting. Furthermore, a rough cut surface refers to the formation of micro-cracks on the cut surface, resulting in a rough surface. In ceramic capacitors, this characteristic cannot be obtained; therefore, poor cut surface roughness is a serious defect.

[0041] Within the range of T1 from 0.9 to 2.2, T1+0.6≤T2≤(15 / 13)T1+(39 / 25). If T1+0.6>T2, the angle of the tip of the cutting edge 120 decreases, making it easier to generate chips. If T2>(15 / 13)T1+(39 / 25), the angle of the tip of the cutting edge 120 increases, increasing the cutting resistance. As a result, poor surface roughness is easily produced.

[0042] Here, the superhard alloy cutting blade 1 has the following shape: it has a base (also called a shank) with a parallel surface, which is used to facilitate cutting, i.e., the blade tip, and to fix the cutting blade to the cutting device. As more specific necessary characteristics, it is required to have good sharpness, wear resistance, resistance to welding of the object being cut, strength against bending, and long service life.

[0043] Regarding sharpness, the shape of the blade tip is particularly important, taking into account the damage to the workpiece being cut. A thin blade with a small (acute) angle at the tip is preferable. However, it's unavoidable that a thinner blade will have lower strength. Therefore, current cutting blades are designed with one or more levels of angle between the blade tip and the base, thereby increasing the angle of the very tip.

[0044] Such thin-bladed blades utilize hard materials such as superhard alloys in addition to high-carbon steel. However, they are difficult to machine, especially when the material is hard; they possess rigidity but are difficult to cut and have low toughness, making them prone to chipping. Furthermore, chipping is also likely to occur during product use.

[0045] Currently, various cutting edge designs have been proposed to meet the above characteristics, but no detailed insights have been offered regarding materials that are difficult to notch and the shape of the blade tip.

[0046] As previously mentioned, an initial notch is formed approximately 3 μm from the cutting tip 121t in the direction of the base 110. In the CAE (Computer Aided Engineering) analysis, even with changes in the angle of the cutting tip 121t, the stress concentration point is not at the tip of the cutting tip 121t, but rather approximately 3 μm in the direction of the base 110. The initial notch at the cutting tip 121t sometimes occurs at approximately 5 μm, depending on the situation, presumably due to the development of cracks. That is, it can be said that the strength required to withstand the stress concentration at this location is sufficient. By designing the profile as a curve in the longitudinal section, where the width of the cutting edge decreases as it approaches the cutting tip, the notch at the stress concentration point can be suppressed most effectively. Preferably, the profile is designed as a curve in the longitudinal section, where the width of the cutting edge decreases as it approaches the cutting tip.

[0047] The present invention optimizes the combination of the aforementioned material and the shape of the foremost end, i.e. the blade thickness, which are factors that affect the notch, so that the notch can be easily generated by satisfying all the above conditions.

[0048] Furthermore, regarding nick resistance, a sharp cutting tip 121t provides good sharpness, but carries the risk of nicking. To further reduce this risk, a curved surface at the tip of the cutting edge 120 is more effective. Obviously, the cutting tip 121t wears down with continuous cutting; more preferably, it meets the range of T1 mentioned above and has a curved surface.

[0049] The cutting edge 120, which is the cutting actuator formed in the direction of the base 110, can achieve the same effect whether it has one or multiple cutting edges. In addition, if the shape of its longitudinal section is composed of straight lines, the same effect can be achieved even if it has curves in a part.

[0050] The method for machining the cutting edge 120 to obtain the aforementioned shape is performed, for example, by grinding with an abrasive, similar to the current method. Alternatively, sandblasting can be used as a method for forming the micro-curved surface. Furthermore, micro-curved surfaces can be formed by cutting with materials softer than the object being cut, such as clay with dispersed abrasive.

[0051] For example, a cutting blade 1 made of superhard alloy is used to cut a solid material mixed with hard abrasive powder, thereby enabling the blade 120 to come into contact with the hard material in the solid material mixed with hard abrasive powder and to process it, thus forming the blade 120.

[0052] Here, clay materials can be cited as examples of solids incorporating hard abrasives. Additionally, powders of diamond, W, Mo, WC, Al2O3, TiO2, TiC, TiCN, SiC, Si3N4, BN, etc., can be cited as examples of hard materials.

[0053] Regarding the powder particle size of the aforementioned hard material, preferably, in terms of Fsss (Fisher Sub-Sieve Sizer) particle size, the average particle size of the secondary particles is less than or equal to 1 μm. In particular, as a finishing process, the type and size of the hard material particles, the amount added to the solid, and the processing time can be adjusted. Furthermore, the manufacturing method of the superhard alloy cutting blade 1 is not limited to the method described above.

[0054] (Implementation Method 2)

[0055] Figure 3 This is a longitudinal cross-sectional view of the superhard alloy cutting blade 1 involved in Embodiment 2. (See attached image.) Figure 3As shown, regarding the superhard alloy cutting blade 1 of Embodiment 2, the position at which the distance from the cutting tip 121t is H1 (1 μm) becomes the boundary where the slope changes discontinuously at the outer surface 121s, which differs from the superhard alloy cutting blade 1 of Embodiment 1. The boundary where the slope of the outer surface 121s changes discontinuously can be located at a distance less than H1 (1 μm) from the cutting tip 121t, such as... Figure 1 That way, it can be positioned between H1 and H2, or at a distance of H2 (3μm) from the tip 121t.

[0056] (Implementation Method 3)

[0057] Figure 4 This is a longitudinal cross-sectional view of the superhard alloy cutting blade 1 involved in Embodiment 3. (See attached image.) Figure 4 As shown, in the superhard alloy cutting blade 1 of Embodiment 3, the cutting tip 121t is rounded, which differs from the superhard alloy cutting blade 1 of Embodiment 1, where the cutting tip 121t is sharp. The radius of curvature of the cutting tip 121t can be a single radius. Alternatively, multiple radii of curvature of the cutting tips 121t can exist, forming a so-called composite R (radian) shape.

[0058] In the first part 121, near the base 110, the outer surface 121s is straight, and becomes curved as it approaches the tip 121t, with the radius of curvature decreasing. The slope of the outer surface 121s changes continuously from the straight part to the curved part.

[0059] (Implementation Method 4)

[0060] Figure 5 This is a longitudinal cross-sectional view of the superhard alloy cutting blade 1 involved in Embodiment 4. (See attached image.) Figure 5 As shown, regarding the superhard alloy cutting blade 1 according to Embodiment 4, the tip 121t of the first portion 121 is rounded. The outer surface 121s of the first portion 121 has: a straight portion near the side of the second portion 122; and a curved portion near the side of the tip 121t. At the boundary between the straight portion and the curved portion, the slope of the outer surface 121s changes discontinuously.

[0061] [Details of embodiments of the present invention]

[0062] (Example 1)

[0063] Figure 6 This is a perspective view of the apparatus used to illustrate the cutting test. Figure 7 It is along Figure 6The cross-sectional view along line VII-VII is shown. The superhard alloy cutting edge 1 (flat-edged cutting edge) used in the experiment was set to 40 mm in the edge transition direction (X-axis direction), 0.1 mm in the base thickness (Y-axis direction), 22.0 mm in the edge height (Z-axis direction), and 1.8 mm in the cutting execution part's edge machining height (Z-axis height of edge 122). Regarding the material, tungsten carbide and cobalt were used as the basic components. The tungsten carbide grain size was adjusted by using metallic carbides such as chromium carbide, vanadium carbide, and tantalum carbide as additives, and the amount of cobalt added was also adjusted to obtain a sintered superhard alloy. As an example, a superhard alloy material with a Vickers hardness of 1580 was used. The tungsten carbide grain size and the amount of cobalt added were adjusted to change the hardness.

[0064] <Grinding>

[0065] The sintered body is ground into a plate shape with a thickness of 100μm, a cutting height of 22mm, and a cutting transition length of 40mm using a diamond grinding machine to form a blank for machining the front cutting edge.

[0066] <The Formation of the Blade>

[0067] Next, the aforementioned blank is used to form the front cutting edge. During this forming process, the blank is fixed to a dedicated workpiece holder with adjustable angle using a specialized grinding machine employing diamond cylindrical grinding tools. When the cutting edge has two sections, the cutting edge 120 is formed having the following components: a first section 121, which has one edge at its foremost point in a direction with a length of 40 mm relative to the long side of the blank and a forehead angle; and a second section 122, which is continuously arranged relative to the first section 121 and continuous relative to the base 110.

[0068] <Flat-surface molding>

[0069] In order to form Figure 1 The outer surfaces 121s and 122s of the plane shown are convex in shape on both sides using a cylindrical grinding tool.

[0070] <Convex Bending Outer Surface Molding>

[0071] In order to form Figure 4 The outer surface 121s, shown as a convex curved surface, forms a clay-like block of hard particles such as diamond and WC particles. The cutting tip is then pressed against this block at high speed and continuously to form a convex shape. The size of the convex part is adjusted according to the number of presses, speed, and angle.

[0072] The arithmetic mean roughness Sa (arithmetic mean height ISO 25178) of the outer surfaces 121s and 122s was set to be less than or equal to 0.02 μm. The surface roughness Ra of the outer surfaces 121s and 122s was measured using a non-contact surface roughness measuring device employing a white interferometer. Specifically, a non-contact three-dimensional roughness measuring device (Nexview (registered trademark)) manufactured by Zygo Corporation was used, with the measurement range in the aforementioned longitudinal section set to 0.15 mm in the X direction and 0.05 mm in the Z direction. Regarding the measurement field of view, the magnification of the zoom lens was set to 2x, and the magnification of the objective lens was set to 50x.

[0073] <Sectional Confirmation>

[0074] To confirm the cross-section, images were taken at 10,000x magnification using a Schottky electric field release scanning electron microscope (JSM-7900F, Nippon Electronics Co., Ltd.). The thickness of the cutting edge (thickness of the cutting edge 120) at distances of 1 μm and 5 μm from the tip 121t was measured using mechanical coordinates and length measurement functions. The Vickers hardness was measured using a Picodentor HM500 (Fisher Instruments Co., Ltd.). The results are shown in Tables 1 to 3.

[0075] [Table 1]

[0076]

[0077] [Table 2]

[0078]

[0079] [Table 3]

[0080]

[0081] In Tables 1 to 3, "Hardness HV" refers to the Vickers hardness of the superhard alloy cutting edge 1. "Coordinate position" is defined as T1 for the thickness 1 μm from the cutting edge, T2 for the thickness 3 μm from the cutting edge, and so on. Figure 2 The T1-T2 coordinates are shown in the plotted coordinates.

[0082] Regarding "C curved surface C and non-curved surface N of the cutting edge", "C" is set when the proportion of curved surface on the cutting edge (outer surface 121s, 122s) is greater than the proportion of non-curved surface, and "N" is set when the proportion of non-curved surface on the cutting edge (outer surface 121s, 122s) is greater than the proportion of curved surface.

[0083] Regarding the presence or absence of curvature at the very tip of the blade, if it exists at the tip 121t... Figure 4Such a curved surface is "Y", if like Figure 1 If there is no curved surface at the tip of the blade (121t), then it is "N".

[0084] The “Figure” indicates the appendix that most closely resembles the shape of each sample. For example, the surface of sample number 2 is smaller in scale, and when viewed as a whole, it is similar to… Figure 3 Most similar. For all samples, a convex portion 120t was confirmed to be located further outward than the straight line S.

[0085] Regarding the cutting evaluation test, various applications were cited, focusing on uniform composition and hardness. The cutting object was a commonly available PVC sheet. It was fixed using an adhesive sheet with a thickness greater than or equal to 0.1 mm and less than or equal to 3.0 mm. Furthermore, the adhesive sheet served to prevent the foremost tip of the cutting edge from contacting the worktable supporting the cutting object during extrusion cutting, thus preventing the formation of a notch. The cutting object had a width of 30 mm in the X-axis direction and a thickness of 0.5 mm in the Z-axis direction. The cutting speed was set to 300 mm / s in the Z-axis direction.

[0086] The conditions of this test ( Figure 6 and Figure 7 )

[0087] Workpiece material: Polyvinyl chloride sheet, 0.5mm thick, 290mm wide, 30mm long, Vickers hardness (HV) 15.

[0088] Test setup: A cutting power meter 9255 (cutting power meter 2003) manufactured by Kisler was mounted on a machining center V55 (platform 2004) manufactured by Makino Frees Manufacturing Co., Ltd.

[0089] Workpiece installation: From bottom to top, there are 10mm thick acrylic sheet 2002, 1mm thick double-sided adhesive sheet 2001, and PVC sheet 100 as the workpiece.

[0090] Cutting conditions: cutting speed 300 mm / s, cutting interval 2.5 mm, indentation 0.55 mm, cutting angle relative to the workpiece length ±0.5°, cutting profile angle relative to the workpiece 90°±0.5°, number of cuts 100 (2.5 mm interval).

[0091] Confirmation items: Notch (depth greater than or equal to 3μm or width greater than or equal to 10μm), cut surface condition

[0092] exist Figure 6 and Figure 7In the apparatus shown, the superhard alloy cutting blade 1 is held in place by chucks 3001 and 3002. The superhard alloy cutting blade 1 descends at a speed of 300 mm / s to perform continuous cutting. Here, in order to perform continuous cutting, cutting is not performed at the same position on the PVC sheet 100 that is being cut; the cutting position can be moved each time the superhard alloy cutting blade 1 rises.

[0093] The condition of the cutting tip after 100 cuts was evaluated based on the number of notches generated along the entire cutting transition direction. The notch count was defined as any notch in the edge portion of the cutting tip that had a width exceeding 10 μm or a depth exceeding 3 μm. Figure 8 The count was performed.

[0094] In the method for measuring the notch, a measuring microscope is used. Specifically, a 50x eyepiece and a 20x objective lens are mounted on an "Olinpass" measuring microscope (STM6-LM), and the cutting edge (XZ plane) is placed on a plane. Figure 8 This is a microscope image showing the notch of the cutting edge. Note Figure 8 The cutting edge tip 121t is parallel to the measuring stage. Align the focal point with the cutting edge tip 121t, and align the cutting edges 121t at both ends of the notch 121k with the reference line in the X-axis direction of the measuring instrument. Set the measured value of Y to "0" and use it as the reference. Figure 8 The distance between the two points where the baseline in the X-axis direction intersects with the end of the notch 121k is defined as the width of the notch 121k. The depth of the notch 121k is defined as the lowest point in the Y-direction of the notch 121k, measured from the X-axis. At this time, a notch 121k is defined as having been generated at the tip of the cutting edge if the width is greater than or equal to 10 μm and the depth is greater than or equal to 3 μm.

[0095] The blade tip with 3 or fewer notches is rated "A", with 4 to 6 notches it is rated "B", with 7 to 10 notches it is rated "C", with 11 to 30 notches it is rated "D", and with 31 or more notches it is rated "E".

[0096] Regarding the condition of the cut surface, it was evaluated based on the surface roughness Sa (arithmetic mean roughness). A score of "A" was given if Sa was less than or equal to 0.02 μm; "B" if Sa exceeded 0.02 μm but less than or equal to 0.05 μm; "C" if Sa exceeded 0.05 μm but less than or equal to 0.1 μm; "D" if Sa exceeded 0.1 μm but less than or equal to 0.2 μm; and "E" if Sa exceeded 0.2 μm. Evaluations up to "C" were acceptable. The surface roughness Sa of the cut surface was measured using the same apparatus as the outer surface 121s. Specifically, the surface roughness Sa of any cross-section of the cut surface was evaluated using a Nexview (registered trademark) from Zygo Corporation within a square region with sides of 60 μm.

[0097] Samples 1 to 14, with a Vickers hardness of 1200, have relatively low hardness, resulting in notches at the cutting tip. Consequently, the cut surface condition deteriorates.

[0098] The embodiments and examples disclosed herein are illustrative in all respects and should be understood as not imposing limitations. The scope of the invention is not defined by the foregoing description but by the claims, and is intended to include the equivalent scope of the claims and all modifications within that scope.

[0099] Explanation of the label

[0100] 1. Superhard alloy cutting blade, 100 PVC sheet, 110 base, 120 cutting edge, 120t protrusion, 121 first part, 121k notch, 121s, 122s, 123s outer surface, 121t cutting tip, 122 second part, 2001 double-sided adhesive sheet, 2002 acrylic sheet, 2003 cutting power meter, 2004 stage, 3001, 3002 chuck.

Claims

1. A cutting blade made of superhard alloy, wherein, The superhard alloy cutting blade has the following characteristics: Base; as well as The cutting edge, which is located on the extension line of the base, has a cutting tip as its foremost point. Vickers hardness HV is greater than or equal to 1250 and less than or equal to 2030. The thickness of the cutting edge at a position 1 μm from the tip towards the base is defined as T1 μm, and the thickness of the cutting edge at a position 3 μm from the tip towards the base is defined as T2 μm, where T1 is greater than or equal to 0.6 and less than or equal to 2.

2. In the range of T1 from 0.6 to 0.9, T1+0.6≤T2≤(10 / 3)T1-0.4; in the range of T1 from 0.9 to 2.2, T1+0.6≤T2≤(15 / 13)T1+(39 / 25).

2. The superhard alloy cutting blade according to claim 1, wherein, In a longitudinal section orthogonal to the blade transition direction, the shape is set as a curve such that the width of the blade portion decreases as it approaches the blade tip.

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