Flat cutting blade

Abstract

The present invention has a configuration wherein: the contours of a first blade section in a vertical cross-section extending both in an extension direction and a thickness direction perpendicular to the extension direction have a first inclined surface which is inclined relative to a center line so as to become thinner as the distance from a base part increases in the extension direction, and has a tip end section which forms the blade tip; the contours of a second blade section in the vertical cross-section have a second inclined surface which abuts the first inclined surface, and is more linear and has a more shallow incline relative to the center line than the incline of the first inclined surface; the contours of a third blade section in the vertical cross-section have a concave curved surface which abuts the second inclined surface and curves in a concave shape toward the center line side; and the length of the second blade section is greater than or equal to the length of the first blade section in the extension direction.

Description

[Technical Field]

[0001] The present disclosure relates to a flat-edged cutting blade. This application claims priority to Japanese Patent Application No. 2022-208048, filed December 26, 2022, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, flat cutting blades have been disclosed, for example, in Japanese Patent Laid-Open No. 2001-158016 (Patent Document 1) and International Publication No. 2020 / 130092 (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-158016 [Patent Document 2] International Publication No. 2020 / 130092 Summary of the Invention

[0004] The flat cutting blade of the present disclosure is a flat cutting blade made of a WC-Co or WC-Ni cemented carbide alloy and having a flat base extending along a centerline and blade portions extending from ends of the base in the extension direction, wherein the blade portions include a first blade portion located farthest from the base in the extension direction, a second blade portion located adjacent to the first blade portion on the base side in the extension direction, and a third blade portion located between the second blade portion and the base in the extension direction, and in a longitudinal cross section extending in both a thickness direction perpendicular to the extension direction and in the extension direction, The outer shape of the first blade portion has a first inclined surface that is inclined with respect to the center line so as to become thinner with increasing distance from the base in the extension direction, and a pointed portion that serves as a cutting edge; in the longitudinal cross section, the outer shape of the second blade portion has a second inclined surface that is inclined linearly with respect to the center line at a gentler angle than the inclination of the first inclined surface and is in contact with the first inclined surface; in the longitudinal cross section, the outer shape of the third blade portion has a concavely curved surface that is concave toward the center line and is in contact with the second inclined surface; and in the extension direction, the length of the second blade portion is greater than the length of the first blade portion. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a perspective view showing a state in which a sheet-like object 1 is being cut by push cutting using a flat cutting blade 100 according to the first embodiment. [Figure 2] FIG. 2 is a side view of the flat cutting blade 100 of FIG. 1 as seen from the direction of arrow II. [Figure 3] FIG. 3 is an enlarged side view of the section III of the flat cutting blade 100 of FIG. [Figure 4] FIG. 4 is a side view of a flat cutting blade 100 according to the second embodiment. [Figure 5] FIG. 5 is an enlarged side view of the V portion of the flat cutting blade 100 of FIG. [Figure 6] FIG. 6 is a perspective view of an apparatus for explaining a cutting test. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. [Figure 8] FIG. 8 is a diagram of the cutting object 1 after cutting, illustrating a method for evaluating the cut surface 1b. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Problem to be solved by this disclosure] Conventional flat cutting blades have the problem that the cut surface of the object to be cut is oblique.

[0007] Patent Document 2 proposes a cutting technology for large MLCCs (Multi-Layer Ceramic Capacitors) using a shape in which the second cutting edge is shorter than the first cutting edge. With this shape, the thickness of the tip of the cutting edge becomes extremely thin, reducing cutting resistance. However, while the cutting edge becomes sharp, there is a problem in that rigidity decreases, reducing the perpendicularity of the surface of the workpiece cross section parallel to the direction of blade movement.

[0008] Demand has been growing in recent years in new markets, including 5G communications equipment, robotics, xEVs (electric vehicles), and self-driving cars. This has led to advances in high-density lamination technology for relatively large MLCCs. To achieve high capacitance, materials with high dielectric constants are being selected, thinner dielectrics are being used, and the number of layers is increasing. This increases the hardness of the green sheet, while the lamination between electrodes becomes narrower, which tends to reduce perpendicular cutting ability when cutting the workpiece.

[0009] Multilayer ceramic capacitors have a structure in which dielectric layers and internal electrodes are stacked in multiple layers, and the capacitance can be increased by making the dielectric layers thinner to narrow the distance between the electrodes, or by increasing the number of layers to increase the total electrode area.

[0010] 100 to 1000 or more green sheets are stacked and pressure is applied to form an integral mold. The integrally molded laminated sheet is cut to a predetermined size and chipped. As laminated sheets become denser and harder through thinning and multi-layering technologies, the material becomes harder, which can cause bending of the cutting edge and base material. When cutting an object to be cut, if the cutting resistance (penetration volume) is large, the cutting edge and base material will bend, causing a gradient in the chip cross section and deteriorating perpendicular cutting ability. The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a flat-edged cutting blade that can reduce bending of the cutting edge and improve perpendicular cutting ability.

[0011] The flat cutting blade disclosed herein is a flat cutting blade made of a WC-Co or WC-Ni cemented carbide alloy, and includes a flat base extending along a centerline and a blade portion extending from an end of the base in the extension direction. The blade portion includes a first blade portion located farthest from the base in the extension direction, a second blade portion located adjacent to the first blade portion on the base side in the extension direction, and a third blade portion located between the second blade portion and the base in the extension direction. In a longitudinal cross section extending in both a thickness direction perpendicular to the extension direction and the extension direction, the outer shape of the first blade portion has a first inclined surface inclined with respect to the centerline so as to become thinner with increasing distance from the base in the extension direction, and a pointed portion serving as the cutting edge.

[0012] In the longitudinal cross section, the outer shape of the second blade portion has a second inclined surface that is linearly inclined relative to the center line at a more gradual angle than the inclination of the first inclined surface and is in contact with the first inclined surface, and in the longitudinal cross section, the outer shape of the third blade portion has a concavely curved surface that is concavely curved toward the center line and is in contact with the second inclined surface, and in the extension direction, the length of the second blade portion is greater than or equal to the length of the first blade portion.

[0013] In a flat-edged cutting blade configured in this manner, the length of the second blade portion is greater than or equal to the length of the first blade portion, thereby suppressing deflection of the second blade portion and making it possible to cut the object to be cut vertically.

[0014] Preferably, in the longitudinal cross section, the first inclined surface has either a convexly curved surface that curves convexly away from the center line and is in contact with the second inclined surface, or a linearly inclined surface.

[0015] An important characteristic required of cutting blades is sharpness (not damaging the chip cross section). To improve sharpness, the shape of the cutting edge is particularly important, and the smaller (sharper) the cutting edge angle, the better. However, the thinner the cutting edge, the lower the strength, and the bending of the cutting edge and base material inevitably leads to a gradient in the chip cross section.

[0016] Furthermore, the thicker the cutting edge, the greater the cutting resistance (penetration volume), which inevitably leads to damage to the chip cross section.

[0017] The present disclosure provides a flat cutting blade with appropriate cutting edge rigidity that allows for good perpendicular cutting performance, i.e., the cut surface of an object to be cut is perpendicular to the surface of the object. It has been confirmed that reducing the deflection of the cutting edge improves perpendicular cutting performance when cutting multilayer ceramic capacitors.

[0018] (Embodiment 1) A flat cutting blade according to a first embodiment of the present invention will be described below with reference to the drawings. In the following description of the embodiment, the same or corresponding parts in the drawings will be given the same reference numerals, and description thereof will not be repeated.

[0019] 1 is a perspective view showing a state in which a sheet-like object 1 is being push-cut using a flat-blade cutting blade 100 according to embodiment 1. As shown in FIG. 1, the flat-blade cutting blade 100 according to embodiment 1 pushes-cut the sheet-like object 1 by moving in the vertical direction. The flat-blade cutting blade 100 includes a base 110 and a blade portion 120.

[0020] The sheet-like object 1 to be cut is, for example, a ceramic green sheet before firing such as a multilayer capacitor or a multilayer inductor, a metal foil, or a hard resin.

[0021] Fig. 2 is a side view of the flat-edged cutting blade 100 of Fig. 1 as viewed from the direction of arrow II. Fig. 3 is an enlarged side view of portion III of the flat-edged cutting blade 100 of Fig. 2. As shown in Figs. 1 and 2, the base 110 of the flat-edged cutting blade 100 according to the first embodiment is flat and extends along a center line C. The extension direction of the base 110 is the Z direction, the thickness direction perpendicular to the extension direction of the base 110 is the Y direction, and the width direction perpendicular to both the extension direction and the thickness direction of the base 110 is the X direction.

[0022] The blade portion 120 extends from an end of the base portion 110 in the extension direction (Z direction). In this embodiment, the blade portion 120 extends symmetrically with respect to the center line C. However, the blade portion 120 may also extend asymmetrically with respect to the center line C.

[0023] When the dimension of one side of the object 1 in the Y direction across the cutting position by the flat-edged cutting blade 100 is significantly smaller than the dimension on the other side, i.e., when the dimension of the object in the Y direction is significantly smaller, when the sheet-like object 1 is press-cut with the flat-edged cutting blade 100, the object with the smaller dimension in the Y direction may be cut at an angle along the slope of the tip side of the blade portion 120. To prevent the object from being cut at an angle, the shape of the tip side of the blade portion 120 may be such that the slope of the side that comes into contact with the object with the smaller dimension in the Y direction is smaller than the slope of the opposite side with respect to the center line C. In this case, the blade portion 120 is extended asymmetrically with respect to the center line C.

[0024] As shown in Fig. 2, the blade portion 120 includes a first blade portion 121, a second blade portion 122, and a third blade portion 123. The first blade portion 121 is located farthest from the base portion 110 in the extension direction (Z direction). The second blade portion 122 is located adjacent to the first blade portion 121 on the base portion 110 side in the extension direction (Z direction). The third blade portion 123 is located between the second blade portion 122 and the base portion 110 in the extension direction (Z direction). Note that the blade portion 120 may further include one or more blade portions located between the third blade portion 123 and the base portion 110 in the extension direction (Z direction).

[0025] The thickness of the base 110 is preferably 0.1 mm or more and 1 mm or less. By setting the thickness within this range, when the chip to be cut is thick (1 mm or more), the thickness of the flat cutting blade 100 itself is large. This increases the rigidity of the base 110, making it possible to suppress deflection of the substrate during cutting.

[0026] In a longitudinal cross section extending in both the thickness direction (Y direction) and the extension direction (Z direction), the outer shape of the first blade portion 121 has a first inclined surface 121s that is linearly inclined with respect to the center line C so as to become thinner with increasing distance from the base 110 in the extension direction (Z direction), and a pointed portion 121t that serves as the cutting edge. In this embodiment, the first inclined surface 121s and the pointed portion 121t are each disposed symmetrically with respect to the center line C. The thickness of the first blade portion 121 is greatest at the end on the base 110 side in the extension direction (Z direction).

[0027] In this embodiment, the tip 121t extends linearly in the longitudinal cross section (FIG. 2). However, the tip 121t may extend in a curved shape convexly toward the side opposite to the base 110 in the longitudinal cross section.

[0028] In this embodiment, if the interior angle between the first inclined surfaces 121s in the longitudinal section is θ1, it is preferable that 16°≦θ1≦40°. The length of the first cutting edge 121 in the extension direction (Z direction) is L1. A smaller θ1 can reduce the penetration volume, but the cutting edge of the flat cutting blade 100 is more likely to chip during cutting, and the rigidity of the first cutting edge 121 becomes insufficient, making the cutting edge more likely to bend.

[0029] In the vertical cross section, the outer shape of the second blade portion 122 has a second inclined surface 122s that is in contact with the first inclined surface 121s and is linearly inclined more gently with respect to the center line C than the inclination of the first inclined surface 121s. In this embodiment, the second inclined surfaces 122s are disposed symmetrically with respect to the center line C.

[0030] The length L2 of the second blade portion 122 in the extension direction (Z direction) is equal to or greater than the length L1 of the first blade portion 121.

[0031] As shown in FIG. 3, the second inclination angle formed by a line CP parallel to the center line C and the second inclined surface 122s is designated as θ2. It has been found that as θ2 increases, the chip cross section becomes more likely to become inclined (deformed, crushed) and be damaged. The cutting edge angle θ2 is preferably 3°≦θ2≦18° and θ2<θ1. A smaller θ2 can reduce the penetration volume, but it has been found that bending is more likely to occur. It has also been found that as θ2 increases, the chip cross section becomes more likely to become inclined (deformed, crushed) and be damaged.

[0032] Furthermore, if the surface roughness (Sa) of the second cutting edge exceeds 0.6 μm, the chip cross section may be damaged, and the chip may be rejected in a visual inspection.

[0033] 2, in the longitudinal cross section, the external shape of the third blade portion 123 has a concavely curved surface 123s that is concavely curved toward the center line C and in contact with the second inclined surface 122s. The length of the third blade portion 123 in the extension direction (Z direction) is L3.

[0034] The flat cutting blade 100 according to the first embodiment is made of a rigid cemented carbide alloy. Specifically, it is made of a WC-Co or WC-Ni cemented carbide alloy. However, the material of the flat cutting blade 100 is not limited to cemented carbide, and may be steel depending on the object to be cut.

[0035] The flat cutting blade 100 according to the first embodiment of the present invention can be formed by grinding using a grinding wheel. The radius of curvature of the concave curved surface is approximately equal to the radius of the grinding wheel.

[0036] Here, the method for measuring each dimension will be described. The length of each blade in the extension direction (Z direction) is measured using a measuring microscope. Specifically, an Olympus measuring microscope (STM6-LM) is fitted with a 10x eyepiece and a 20x objective lens. The length of each blade in the extension direction (Z direction) is the average of the measurements of the YZ cross section at 10mm intervals in the X direction.

[0037] The interior angle θ1 between the first inclined surfaces 121s, the second inclined angle θ2, and the radius of curvature of the concavely curved surface are measured based on the image of the vertical cross section captured using a scanning electron microscope (SEM). Specifically, a Hitachi field emission scanning electron microscope (S-4200) is used to capture an image of the vertical cross section at high magnification. The interior angle θ1 between the first inclined surfaces 121s and the second inclined angle θ2 are measured based on the captured image using a protractor or the like. The radius of curvature of the concavely curved surface is the radius of an approximation circle of the concavely curved surface obtained based on the captured image using a least squares method or the like.

[0038] (Embodiment 2) Fig. 4 is a side view of the flat-edged cutting blade 100 according to embodiment 2. Fig. 5 is an enlarged side view of the V portion of the flat-edged cutting blade 100 in Fig. 4. The flat-edged cutting blade 100 according to embodiment 2 differs from the flat-edged cutting blade 100 of embodiment 1 in that the first inclined surface 1121s of the first cutting portion 121 is convex, whereas the first inclined surface 121s of the first cutting portion 121 is linear.

[0039] When the cutting edge interior angle (θ1) is small, the cutting resistance decreases, but chipping becomes more likely. To solve this problem, forming a first inclined surface 1121s with a convex curve increases the thickness of the blade, making it possible to suppress chipping. The interior angle (θ1) formed by the two first inclined surfaces 1121s is the angle between the two straight lines 2121 at the pointed end 121t.

[0040] The straight line 2121 is a straight line connecting the sharp edge 121t and the boundary between the first cutting edge 121 and the second cutting edge 122.

[0041] (Example) Flat cutting blades of sample numbers 1 to 13 (Figs. 1-3) and sample numbers 21 to 30 (Figs. 4 and 5) were fabricated using cemented carbide FM10K material manufactured by A.L.M.T. Corporation or a WC-Ni-based material (with 10% Ni added by mass). Each blade had a width of 40 mm in the X direction, a thickness of 0.4 mm in the Y direction, and a length of 20 mm in the Z direction. The third cutting edge 123 had a minimum thickness of 0.1 mm in the Y direction. The blade shapes of the flat cutting blades of sample numbers 1 to 13 and 21 to 30 are shown in Tables 1 and 2.

[0042] [Table 1]

[0043] [Table 2]

[0044] The "height of the convex portion" in Table 2 is the height t of the convex portion 121st shown in Fig. 5. The height t is the distance from the straight line 2121 to the furthest convex portion 121st.

[0045] Fig. 6 is a perspective view of an apparatus for explaining a cutting test, and Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 6.

[0046] As shown in Figures 6 and 7, the cutting evaluation method involved placing a Kistler cutting dynamometer 9255 (hereinafter referred to as cutting dynamometer 2003) on stage 2004 of a Makino Milling Machine Machining Center V55. From the bottom up, a 10-mm-thick acrylic plate 2002, a 1-mm-thick double-sided adhesive sheet 2001, and the workpiece 1 were placed. The workpiece 1 was a PVC plate 2 mm thick, 290 mm wide, and 30 mm long. The flat-edged cutting blade 100 was 40 mm long and set in holders 3001 and 3002 so that both ends of the flat-edged cutting blade 100 (5 mm) did not impinge on the workpiece 1. The angle between the tip 121t and the top surface 1a of the workpiece 1 (angle in the XZ plane) was set to within a range of ±0.5°. The cutting conditions were a cutting speed of 300 mm / s, a cutting interval of 12 mm, and a penetration depth of 2.05 mm. One step is defined as a total of 24 cuts made in the Y direction in Figure 6. The first, second, 23rd, and 24th cuts are not evaluated. 25 cut pieces (cut pieces of the cut object 1) can be produced in one step, and one step can be repeated five times to create a total of 100 cut pieces (cut pieces of the cut object 1).

[0047] (Vertical cut evaluation) The perpendicular cutting ability was evaluated by observing the cut pieces of the object 1 after the above-mentioned cutting test.

[0048] FIG. 8 is a diagram of the cutting object 1 after cutting, illustrating a method for evaluating the cut surface 1b. In the method for measuring the perpendicular cut property, an Olympus measuring microscope (STM6-LM) was used, and a 50x eyepiece and a 20x objective lens were attached. top surface Place the cut surface 1b on the left side with 1a facing up.

[0049] The point where the pointed end 121t in Figure 8 first enters the workpiece 1 is designated as point 2b, and care must be taken to ensure that the measurement stage is parallel to the upper surface 1a. The point on the lower surface 1f that is reached by moving from point 2b in the Z-axis direction is designated as point 2a. Focus on point 2b, and measure the distance to point 2a on the lower surface 1f in the Z-axis direction of the measuring instrument; this distance is designated as L11.

[0050] The point on the lower surface 1f of the cutting surface 1b that the tip 121t last contacted is defined as point 2c. The distance from point 2a to point 2c in the Y-axis direction is measured and defined as L12. Since tan θ4=L11 / L12, θ4=tan -1 Calculate (L11 / L12) to find θ4, which is the angle between the top surface 1a and the straight line 1e that passes through points 2b and 2c.

[0051] 24 cuts are made in one step, and the cut surfaces 1b of the 1st, 2nd, 23rd, and 24th cuts are not evaluated, so 20 cut surfaces 1b are evaluated per step, and 80 cut surfaces 1b are evaluated in four steps. The number of cut surfaces where θ4 is in the range of 90°±2° is defined as n, and the value of n / 80 is the pass rate. A pass rate of 99% or more was given an "A," a pass rate of 80% or more but less than 99% was given a "B," and a pass rate of less than 80% was given a "C."

[0052] (Surface roughness evaluation of the second inclined surface) The surface roughness (Sa) of the second inclined surface 122s is measured using a non-contact surface roughness measuring device that uses laser light. Specifically, a non-contact three-dimensional roughness measuring device (NewView7300) manufactured by Zygo Corporation is used, and the measurement range in the longitudinal section is 0.15 mm in the X direction and 0.05 mm in the Z direction. The measurement field of view is set to a zoom lens magnification of 1x and an objective lens magnification of 50x. Measurement correction is 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.

[0053] The results are shown in Tables 1 and 2. From Tables 1 and 2, it can be seen that sample numbers 1 to 12 and 21 to 29, in which the length L1 was equal to or greater than the length L2, achieved a result of evaluation B or higher.

[0054] Furthermore, from Tables 1 and 2, it was confirmed that if the length L2 is equal to or greater than the length L1 and is equal to or greater than 100 μm and equal to or less than 2000 μm, and the relationship that θ1 is 16°≦θ1≦40°, and the relationship that θ2 is 3°≦θ2≦18° is satisfied, then an evaluation of A can be obtained. It was also confirmed that if the length L2 is less than the length L1, then an evaluation of C can be obtained.

[0055] The embodiments and examples disclosed herein should be considered to be illustrative in all respects and not restrictive.

[0056] The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. In addition, in the above embodiment, the cross-sectional shape of the flat cutting blade is symmetrical with respect to the center line C, but the cross-sectional shape of the flat cutting blade does not necessarily have to be symmetrical with respect to the center line C in order to obtain the perpendicular cutting effect. [Explanation of symbols]

[0057] 1 Object to be cut, 1a top surface, 1b cutting surface, 1e, 2121 straight line, 1f bottom surface, 2a, 2b, 2c points, 100 flat cutting blade, 110 base, 120 blade section, 121 1st blade section, 121s, 1121s 1st inclined surface, 121st convex section, 121t tip section, 122 2nd blade part, 122s 2nd inclined surface, 123 3rd blade part, 123s concave curved surface, 2001 double-sided adhesive sheet, 2002 acrylic plate, 2003 cutting dynamometer, 2004 stage.

Claims

1. A flat cutting blade made of a WC-Co or WC-Ni cemented carbide alloy, the flat cutting blade having a flat base extending along a center line and a cutting edge extending from an end of the base in the extending direction, The blade portion includes a first blade portion located farthest from the base portion in the extension direction; a second blade portion positioned adjacent to the first blade portion on a base side in the extension direction; a third blade portion located between the second blade portion and the base portion in the extension direction, In a longitudinal cross section extending both in a thickness direction perpendicular to the extension direction and in the extension direction, the outer shape of the first blade portion has a first inclined surface inclined with respect to the center line so as to become thinner with increasing distance from the base portion in the extension direction, and a pointed portion serving as a cutting edge, In the longitudinal cross section, the outer shape of the second blade portion has a second inclined surface that is linearly inclined with respect to the center line more gradually than the inclination of the first inclined surface and is in contact with the first inclined surface, and in the longitudinal cross section, the outer shape of the third blade portion has a concavely curved surface that is concavely curved toward the center line and is in contact with the second inclined surface, and the length of the second blade portion in the extension direction is equal to or longer than the length of the first blade portion, A flat cutting blade, wherein the length of the first cutting edge along the center line is 52 μm or more.

2. A flat-edged cutting blade as described in claim 1, wherein the length of the first cutting edge along the center line is 150 μm or less.

3. A flat-edged cutting blade as described in claim 1 or 2, wherein the length of the second cutting edge along the center line is 100 μm or more.

4. A flat-edged cutting blade as described in claim 1 or 2, wherein the length of the second cutting edge along the center line is 162 μm or more.

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