Flat cutting blade

Abstract

The present invention provides a flat cutting blade composed of a WC-Co-based or WC-Ni-based cemented carbide and comprising a flat plate-like base part extending along a center line and a blade part extending, along the center line, from an end of the base part. The blade part has a blade tip section. A ridge line is formed at the cutting edge of the blade tip section. In a longitudinal section extending in both the extension direction and a thickness direction orthogonal to the extension direction, the variation σ in the width of the ridge line in the thickness direction is greater than 0 and equal to or less than 2.000.

Description

Flat cutting blade

[0001] This disclosure relates to a flat-edged cutting blade. This application claims priority to Japanese Patent Application No. 2024-027123, filed February 27, 2024. The entire contents of this Japanese patent application are incorporated herein by reference.

[0002] Conventionally, a flat cutting blade is disclosed, for example, in International Publication No. 2014 / 050883 (Patent Document 1).

[0003] International Publication No. 2014 / 050883

[0004] A flat-edged cutting blade made of a WC-Co or WC-Ni cemented carbide alloy, having a flat base extending along a center line and a cutting edge extending from the end of the base, wherein the cutting edge has a cutting edge portion, and a ridge line is formed at the tip of the cutting edge portion, and in a longitudinal cross section extending both in a thickness direction perpendicular to the extension direction and in the extension direction, the variation σ of the width of the ridge line in the thickness direction is greater than 0 and not greater than 2.000.

[0005] FIG. 1 is a perspective view showing a state in which a sheet-like object 1 is being press-cut using a flat-edge cutting blade 100 according to the first embodiment. FIG. 2 is a side view of the flat-edge cutting blade 100 of FIG. 1 as viewed from the direction indicated by arrow II. FIG. 3 is a perspective view of an apparatus for explaining a cutting test. FIG. 4 is a cross-sectional view of the apparatus taken along line IV-IV in FIG. 3. FIG. 5 is a cross-sectional view of an object 1. FIG. 6 is a photograph showing the width of the ridge line 122 of the flat-edge cutting blade 100. FIG. 7 is an SEM photograph for observing the width of the ridge line 122.

[0006] [Problem to be Solved by the Present Disclosure] Conventional flat cutting blades have a problem in that they tend to scratch the cut surface of the object to be cut.

[0007] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0008] In Patent Document 1, "life" refers to the point at which chipping causes damage to the cross-sectional shape of the workpiece, and in the case of a cutting blade for a multilayer capacitor, the blade's life ends when peeling of the laminated film occurs. However, if there is a large variation in the ridge width of the cutting edge of the blade tip during cutting, wear and resistance increase, deteriorating cutting quality and reducing yield.

[0009] Demand has been growing in recent years in new markets, including 5G communication devices, robotics, electric vehicles (EVs), and self-driving cars. MLCCs (Multi-Layer Ceramic Capacitors) are becoming more functional without shrinking in size (lower profile). Improved characteristics, such as higher capacitance, higher current capability, and lower ESL, are required for MLCCs, requiring high-precision cutting quality.

[0010] The edge of a cutting blade has ridges, and variations in the width of these ridges result in differences in cutting quality. If the ridge width is wide, the force is distributed over a wider area even when the same amount of force is applied. This dulls the blade's sharpness, increases the contact area with the workpiece, and increases wear and resistance. This reduces energy efficiency during cutting, dulls the blade's sharpness, and cracks form in the workpiece first, damaging the cut surface and resulting in a poor appearance. On the other hand, if the ridge width is narrow, the contact area with the workpiece is small, making it more likely for stress to concentrate. The force and wear during cutting cause stress to concentrate, resulting in greater force being applied and causing the chip to expand. The chip grows larger with each use, and the chipped part catches on or is scraped off the workpiece, leaving a deep scratch on the cut surface. This reduces cutting performance (lifespan) and reduces the yield of the workpiece.

[0011] Multilayer ceramic capacitors have a structure in which dielectric layers and internal electrodes are laminated in multiple layers. The capacitance can be increased by narrowing the distance between electrodes by making the dielectric layers thinner, or by increasing the number of layers to increase the total electrode area.

[0012] 100 to 1,000 or more layers of green sheets are stacked and pressed into a single unit. The integrated laminated sheet is then cut to the required size and chipped. The laminated sheet can be made denser and harder through thinning and multi-layering techniques. As the material becomes harder, a wider ridgeline distributes the force over a wider area, even when the same amount of force is applied. The contact area with the workpiece increases, resulting in increased wear and resistance. This reduces energy efficiency during cutting. Dulling blades can cause cracks to form in the workpiece before they are cut, damaging the cut surface and resulting in poor appearance. On the other hand, a narrow ridgeline reduces the contact area with the workpiece, making stress more likely to concentrate. Large forces, such as force and wear, can cause chips to expand and grow with each use. The chipped portion can catch on or scrape the workpiece, leaving deep scratches on the cut surface and reducing cutting quality.

[0013] The present disclosure provides a flat cutting blade capable of improving cutting quality, which includes a flat base extending along a centerline and a cutting edge extending from an end of the base, and is made of a WC-Co or WC-Ni cemented carbide alloy, wherein the cutting edge has a cutting edge having a ridgeline formed at its tip, and the ridgeline has a thicknesswise width variation σ greater than 0 and not greater than 2.000 in a longitudinal cross section extending both in the thickness direction perpendicular to the extension direction and in the extension direction.

[0014] [Correction based on Rule 91 12.08.2025] The inventors have found that the variation in width of the ridge line in the thickness direction is related to the cutting quality. If the variation in width of the ridge line in the thickness direction σ is more than 0 and not more than 2.000, a high-quality cut surface can be provided.

[0015] The ridgeline width variation is measured at five points on the ridgeline at intervals of 5 mm in the blade length direction. The ridgeline width (unit: μm) is determined at these five points on the ridgeline. The ridgeline widths at the five points are designated W1, W2, W3, W4, and W5, and the average value of the ridgeline widths at the five points is designated A. The variation σ is calculated using the following formula:

[0016] σ=[1 / 5{(W1-A) 2 +(W2-A)2 +(W3-A) 2 +(W4-A) 2 +(W5-A) 2}] 1 / 2 This makes it possible to provide a cutting blade that satisfies both stable shape accuracy and cutting performance from the initial cut.

[0017] An important characteristic required of cutting blades is sharpness (not damaging the chip cross section). The shape of the cutting edge is particularly important, and the smaller (sharper) the cutting edge angle (edge ​​angle) the better. However, the thinner the cutting edge, the lower the strength. The tip becomes more susceptible to chipping, which inevitably leads to cutting scratches on the object being cut.

[0018] Furthermore, the thicker the tip of the cutting edge, the greater the cutting resistance (penetration volume) and the more likely a pre-crack will occur, which will inevitably damage the workpiece and reduce the cutting quality.

[0019] In the present disclosure, the variation σ in the width of the ridgeline of the tip of the blade is greater than 0 and not more than 2.000, which has been confirmed to improve the quality (lifespan) when cutting multilayer ceramic capacitors.

[0020] [Correction based on Rule 91 12.08.2025] It is preferable that the variation σ is greater than 0 and less than or equal to 0.100, as this improves the quality of the cut surface.

[0021] The cemented carbide preferably contains 3 mass % to 25 mass % of Co or Ni, which maximizes the strength of the cemented carbide.

[0022] The cutting edge angle of the cutting edge is preferably 20° to 40°, inclusive, which provides the best sharpness and lifespan of the flat cutting blade.

[0023] The present disclosure provides a flat-edge cutting blade capable of improving cutting quality. Fig. 1 is a perspective view showing a state in which a flat-edge cutting blade 100 according to a first embodiment is used to press-cut a sheet-like object 1. Fig. 2 is a side view of the flat-edge cutting blade 100 of Fig. 1 as viewed from the direction indicated by arrow II.

[0024] 1 and 2, the flat cutting blade 100 includes a flat base 110 extending along a center line C, and a cutting edge 120 extending from the end of the base 110. The flat cutting blade 100 is made of a WC—Co-based or WC—Ni-based cemented carbide alloy.

[0025] The blade portion 120 has a cutting edge 121, and a ridge 122 is formed at a tip 121t of the cutting edge 121. In a thickness direction (Y direction) perpendicular to the extension direction (Z direction) and in a longitudinal cross section ( FIG. 2 ) extending in both the extension direction and the thickness direction, the variation σ of the width of the ridge 122 in the thickness direction is greater than 0 and not greater than 2.000.

[0026] The material used for the flat cutting blade 100 is a cemented carbide alloy mainly composed of WC, Co, and Ni. The WC crystal grain size in the cemented carbide alloy is preferably 0.1 μm or more and 4 μm or less. The Co and Ni content used in the cemented carbide alloy is preferably 3 to 25% by mass. Vanadium carbide may be added to inhibit grain growth in order to control the WC crystal grains. Tantalum carbide or chromium carbide may be added to increase hardness.

[0027] That is, the WC-Co or WC-Ni cemented carbide may contain at least one selected from the group consisting of vanadium carbide, tantalum carbide, and chromium carbide.

[0028] The thickness of the base 110 of the flat cutting blade in the Y direction is preferably 0.1 mm to 1 mm inclusive. By setting the thickness within this range, even if the chip to be cut is thick (1 mm or more), the thickness of the flat cutting blade 100 itself is increased to increase rigidity, thereby suppressing deflection of the base 110 during cutting, and thus making it less likely to chip.

[0029] 1 and 2, the pair of inclined surfaces 121s has a linear shape, but the pair of inclined surfaces 121s may have a curved shape. The inclined surfaces 121s may have a shape that is a combination of a curved shape and a linear shape.

[0030] The pair of inclined surfaces 121s may be convex outward or convex inward. The cutting edge angle θ1 formed by the pair of inclined surfaces 121s can be changed as appropriate depending on the type of workpiece. For example, the cutting edge angle θ1 can be set to 7° or more and 40° or less, preferably 20° or more and 40° or less.

[0031] [Details of the embodiment of the present disclosure] (Preparation of sample numbers 1 to 15) Using cemented carbide FM10K (WC—Co-based material (Co added amount 14 mass%)) manufactured by A.L.M.T.C., and a WC—Ni-based material (Ni added amount 10 mass%), flat cutting blades 100 of sample numbers 1 to 15 in Table 1 were produced. The shape of each flat cutting blade 100 was 40 mm in width in the X direction, 0.4 mm in thickness in the Y direction, and 20 mm in length in the Z direction as shown in FIG.

[0032] When producing the flat cutting blades 100 of sample numbers 1 to 13, burrs were generated on the tip 121t of the cutting edge 121, so the portion from the tip 121t to a depth of about 0.5 mm was immersed in diluted nitric acid with a concentration of 50% by mass for 1 to 3 minutes for etching to remove the burrs. Sample numbers 14 and 15 were not subjected to deburring with diluted nitric acid.

[0033] The flat cutting blades 100 of sample numbers 1 to 15 were observed using a SEM (Scanning Electron Microscope).

[0034] Specifically, a field emission scanning electron microscope (S-4200) manufactured by Hitachi, Ltd. was used, and the flat cutting blade 100 was set vertically in a chamber and measured.

[0035] The evaluation criteria were to measure the ridgeline width at five locations, 5 mm apart, over a 40 mm length, with the central portion of the cut surface enlarged 1,000 to 20,000 times. The ridgeline width was wider where chipping had occurred. The portion for which the ridgeline width was measured was the portion that contributed to cutting by coming into contact with the workpiece 1.

[0036] The blade shapes of the flat cutting blades 100 of sample numbers 1 to 15 are as shown in Table 1.

[0037]

[0038] Fig. 6 is a photograph showing the width of the ridgeline 122 of the flat cutting blade 100. Fig. 7 is an SEM photograph for observing the width of the ridgeline 122. As shown in Figs. 6 and 7, the point where the two inclined surfaces 121s of the flat cutting blade 100 intersect is the tip 121t. The tip 121t is formed with a ridgeline 122 extending in the X direction (the blade length direction). The width W of the ridgeline in the Y direction varies depending on the measurement location.

[0039] (Cutting Test) A cutting test was carried out using these flat cutting blades 100.

[0040] Fig. 3 is a perspective view of an apparatus for explaining a cutting test. Fig. 4 is a cross-sectional view of the apparatus taken along line IV-IV in Fig. 3. As shown in Fig. 3 and Fig. 4, in order to evaluate cutting performance, a Kistler cutting dynamometer 9255 (hereinafter referred to as cutting dynamometer 2003) was set on stage 2004 of a Makino Milling Machine V55.

[0041] Set from the bottom are an acrylic plate 2002 having a thickness of 10 mm, a double-sided adhesive sheet 2001 having a thickness of 1 mm, and an object to be cut 1. The object to be cut 1 is a PVC plate having a thickness of 0.5 mm, a width of 240 mm, and a length of 30 mm.

[0042] The flat cutting blade 100 was set in the holders 3001 and 3002. The length of the flat cutting blade 100 in the X direction was 40 mm, and the angle (angle in the XZ plane: θ3) formed between both ends of the flat cutting blade 100 and the top surface 1 a of the workpiece 1 was ±0.5°.

[0043] The cutting conditions were a cutting speed of 300 mm / s, a cutting interval of 12 mm, and a push-in depth of 0.55 mm. One step consisted of 24 cuts in the Y direction (from the upper surface 1a to the lower surface 1f) in FIG. 4 . The first, second, 23rd, and 24th cuts were not evaluated. 25 cut pieces (cut pieces of the object 1) were produced in one step. One step was repeated 80 times, producing a total of 2,000 pieces of the object 1.

[0044] [Correction based on Rule 91 12.08.2025] (Evaluation of scratches on the cutting object) Scratches on the cutting object were measured using a non-contact surface roughness measuring device using white light. Specifically, roughness Sz (maximum height: ISO 25178) was measured using a non-contact three-dimensional roughness measuring device (New View 7300) manufactured by Zygo Corporation. The cutting surface 2b of the cutting object 1 was placed on a flat surface with the cutting surface 2b facing up. The presence or absence of irregularities on the cutting surface was evaluated on a three-point scale. The results are shown in Table 2.

[0045] [Amendment under Rule 91 12.08.2025]

[0046] The surfaces were rated on a three-point scale: surfaces with no visible irregularities (Sz 0.1 μm or less) were rated "A"; surfaces with minor irregularities on the cut surface that were not scratches (Sz greater than 0.1 μm and less than 0.5 μm) were rated "B"; and surfaces with large irregularities on the cut surface (Sz greater than 0.5 μm) were rated "C."

[0047] (Evaluation of Surface Roughness of Inclined Surface) The surface roughness (Sa) of the inclined surface 121s was measured using a non-contact surface roughness measuring device using white light. Specifically, a non-contact three-dimensional roughness measuring device (New View 7300) manufactured by Zygo Corporation was used. The measurement range in the vertical cross section of FIG. 2 was 0.15 mm in the X direction and 0.05 mm in the Z direction. The measurement field was set to a zoom lens magnification of 1x and an objective lens magnification of 50x. Measurement correction was performed using a robust bandpass filter, with the lower cutoff frequency wavelength set to 250 μm and the upper cutoff frequency wavelength set to 2.5 μm. The surface roughness Sa of all samples was 0.1 μm or more and 1 μm or less.

[0048] From Table 2, sample numbers 1 to 13, in which the ridge width variation σ was greater than 0 and not greater than 2.000, were evaluated as "B" or higher.

[0049] Furthermore, if the variation σ was greater than 0 and less than or equal to 0.100, an evaluation of "A" was obtained. The embodiments disclosed herein are illustrative in all respects and should be considered not to be limiting. The scope of the present invention is defined by the claims rather than the above-described embodiments, and it is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

[0050] 1 Object to be cut, 1a Upper surface, 1f Lower surface, 2b Cutting surface (shear surface), 3b Cutting scar, 100 Flat cutting blade, 110 Base, 120 Blade portion, 121 Cutting tip portion, 121s Inclined surface, 121t Tip, 122 Ridge line, 2001 Double-sided adhesive sheet, 2002 Acrylic plate, 2003 Cutting dynamometer, 2004 Stage, 3001, 3002 Holder.

Claims

1. A flat cutting blade made of a WC-Co or WC-Ni cemented carbide alloy, with a flat base extending along a centerline and a cutting edge extending from the end of the base along the centerline, wherein the cutting edge has a cutting edge portion, and a ridge line is formed at the tip of the cutting edge portion, and in a longitudinal cross section extending both in the thickness direction perpendicular to the extension direction and in the extension direction, the variation σ of the width of the ridge line in the thickness direction is greater than 0 and not greater than 2.

000.

2. [Correction based on Rule 91 12.08.2025] A flat cutting blade according to claim 1, wherein the variation σ is greater than 0 and not greater than 0.100.

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