blade

Abstract

By identifying the extremely fine details within a range of approximately 2 μm from the cutting edge, we provide blades with excellent cutting quality and durability. [Solution] The blade comprises a base 10 and a cutting portion 20 with a cutting edge 21 at its tip, the thickness of which gradually decreases from the base 10 toward the cutting edge 21, and at least one side surface 20A, 20B of the blade portion 20 is composed of one or more inclined planes 23A, 23B and curved surfaces 22A, 22B continuous therewith, and a position 2 μm from the cutting edge 21 toward the base 10 is located on the curved surfaces 22A, 22B. The angle (cutting edge angle θ1) between the inclined plane 20A of the blade portion 20 closest to the cutting edge 21 and the inclined plane 20B, which is the side surface opposite to this inclined plane 20A, and the angle (tangent angle θ2) between two tangent lines 24A, 24B tangent to both side surfaces of the blade portion 20 on a plane perpendicular to the blade length direction at a position 2 μm from the cutting edge 21 toward the base 10, satisfy the following relationship: 10°≦θ1≦30° 4°≦θ2-θ1≦60°

Description

[Technical Field]

[0001] The present invention relates to a blade, and more particularly to an industrial precision blade that requires precise cutting. [Background technology]

[0002] Industrial precision blades are used in cutting processes and situations in a variety of industries. The objects to be cut (workpieces) are diverse, including resin films used in industrial products, high-performance composite films used in smartphone panels, industrial rubber, food packaging, and resin-embedded cells for pathological testing. The required cutting quality (cutting performance) also varies depending on the workpiece, with some requiring no streaks or burrs on the cross section, others requiring the blade to bend and avoid diagonal cuts, and others requiring thin, uniform slices.

[0003] Generally, by adjusting the blade specifications, such as the shape, it is possible to provide an optimum blade for the physical properties of the workpiece and the required cutting quality. Here, the following patent documents are cited as documents that describe inventions related to blade shapes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7292487 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 describes the shape of the cutting edge, specifying the thickness of the cutting edge from 3 μm to 3 mm from the cutting edge to the base. This specified thickness shape from the cutting edge to the base is a so-called "clamshell shape," which is gently curved like the cross section of a clam. The "clamshell shape" is used for Japanese swords and kitchen knives to balance the strength and sharpness of the blade.

[0006] The applicant has discovered through SEM (Scanning Electron Microscope) image analysis of the state of the most distal end (cutting edge) of the blade, which is the cutting part when cutting various workpieces, that the shape of the blade within about 2 μm from the cutting edge has a significant effect on cutting quality and durability. However, Patent Document 1 does not mention this extremely fine part within about 2 μm from the cutting edge.

[0007] Therefore, the present invention aims to provide a blade that is excellent in both cutting quality and durability by specifying an extremely fine portion in the range of about 2 μm from the cutting edge. [Means for solving the problem]

[0008] As described above, the applicant has found that, through various cutting tests and observation of the cutting edge condition before and after cutting, it is the shape of the cutting edge within a few microns of the tip that has a significant effect on the cutting quality and durability of precision blades.

[0009] Figure 1 shows the changes in the microscopic state of the cutting edge and the object when a blade cuts an object. When the cutting edge penetrates the object (see Figure 1(a)), a microscopic fracture occurs at the part of the object where the cutting edge comes into contact (see Figure 1(b)). As the cutting edge penetrates further, the fracture surface is expanded near the cutting edge A, and the fracture at the tip progresses (see Figure 1(c)).

[0010] Therefore, by sharpening the cutting edge, micro-fractures are more likely to occur at the cutting edge of the object being cut, and the stress of spreading at the area V near the cutting edge is reduced, improving cutting quality. However, as a blade, strong forces are applied from the cutting edge to the area near the cutting edge, making chipping more likely to occur and reducing durability. Therefore, by optimizing the shape of the tip of the cutting edge within a few microns to suit the object being cut, we aim to achieve both cutting quality and durability.

[0011] In addition, the part from the tip to the base of the blade has a large impact on the quality of the cut surface because the blade penetrates the object and slides while pressing and rubbing against the cutting surface. To improve cutting quality, it is desirable to reduce the cutting angle in this part, but this would reduce the strength of the blade.

[0012] Therefore, in the blade of the present invention, in order to optimize the normally contradictory cutting quality and durability to suit the object to be cut, the cross-sectional shapes of the cutting edge and the part connecting the cutting edge to the base are defined as follows.

[0013] The blade of the present invention comprises a base and a cutting edge at its tip, the thickness of which gradually decreases from the base to the cutting edge, and at least one side of the blade is composed of one or more inclined planes and a curved surface continuous therewith, with a position 2 μm from the cutting edge toward the base located on the curved surface. The angle between the inclined plane closest to the cutting edge of the blade and the side opposite this inclined plane (hereinafter referred to as "cutting angle θ1"), and the angle between two tangents that touch both side surfaces of the blade on a plane perpendicular to the blade length direction at a position 2 μm from the cutting edge toward the base (hereinafter referred to as "tangent angle θ2"), are configured to satisfy the following relationship: 10°≦θ1≦30° 4°≦θ2-θ1≦60°

[0014] This configuration allows the blade shape to smoothly change from the cutting edge toward the base. In particular, within an extremely small area of ​​2 μm from the cutting edge, the difference in angle between the tangent angle θ2 and the blade angle θ1 (θ2-θ1) is set within a range of 4° to 60°. This allows for both cutting performance and durability at the initial stage of cutting, and reduces the contact area between the blade side and the cutting surface during cutting, resulting in a high-performance blade that achieves both cutting quality and durability. In this specification, the term "tangent line tangent to the side of the blade portion on a plane perpendicular to the blade length direction" refers to, if the side is a curved surface, a tangent line tangent to the curved surface that lies on a plane perpendicular to the blade length direction. If the side is flat, it refers to, if the side is flat, a straight line on the plane that lies on the plane perpendicular to the blade length direction. The angle between the two tangent lines on both sides of the blade portion is the tangent angle θ2.

[0015] It is also possible to set the blade angle θ1 within a narrow range of 10°≦θ1≦20°, and further limit the angle difference θ2-θ1 to 4°≦θ2-θ1≦20°. This configuration results in a sharper blade angle and gently controls the change in shape from the blade tip toward the base, resulting in excellent cutting performance, especially for objects with low cutting resistance, such as resin films and soft materials.

[0016] The blade angle θ1 can also be set in the range of 20°≦θ1≦30°, and the angle difference θ2-θ1 can be set larger, at 20≦θ2-θ1≦60°. With this configuration, the cutting edge has a relatively obtuse angle and the blade thickness at a position 2 μm from the cutting edge is also relatively large, but the angles on both sides from this point toward the base are reduced, and the increase in blade thickness is also suppressed. This provides the cutting edge with strength and durability, while reducing the contact area between the blade side and the cutting surface during cutting, providing a high-performance blade that combines cutting quality and durability.

[0017] When θ1 = θ2, the blade shape becomes a straight line extending from the base to the cutting edge at a cutting angle of θ1 at a position 2 μm from the cutting edge, as shown in Figure 2(a). In this case, the contact area between the blade and the cutting surface increases from the vicinity of the cutting edge to the base, resulting in a decrease in cutting quality.

[0018] On the other hand, in the blade of the present invention, θ1<θ2 in the portion from near the cutting edge toward the base of the blade, which reduces the contact area between the blade and the cutting surface from near the cutting edge to the base, improving cutting quality. However, if θ1 is too small, the strength of the blade decreases, and if θ2 is too large, the cutting edge loses its sharpness, resulting in reduced cutting quality. Therefore, in the present invention, the appropriate ranges for θ1 and θ2 that can achieve both cutting quality and durability are specified as described above.

[0019] Furthermore, the ratio θ2 / θ1 between the tangent angle θ2 and the cutting edge angle θ1 can be set within the range of 1.2≦θ2 / θ1≦4.0. This configuration optimizes the relative balance between the angle of the cutting edge and the opening angle of the entire cutting edge that follows behind it. This configuration focuses on the fact that the sharpness of the cutting edge and the shape behind the cutting edge functionally work together to determine cutting characteristics, and has the effect of increasing design flexibility to suit different materials and applications. [Effects of the Invention]

[0020] (1) By appropriately designing the angle difference θ2-θ1 in the smallest range immediately adjacent to the cutting edge, the blade can smoothly bite into the object during cutting while reducing the contact area between the blade side and the cutting surface during cutting, thereby providing a high-performance blade that combines cutting quality and durability.

[0021] (2) By setting the blade angle θ1 within a narrow range of 10°≦θ1≦20° and further limiting the angle difference θ2-θ1 to 4°≦θ2-θ1≦20°, the small blade angle θ1 improves the cutting performance at the initial stage of cutting. Furthermore, the narrow range of the angle difference θ2-θ1 between the tangent angle θ2 and the blade angle θ1 reduces the contact area between the blade side and the cutting surface during cutting, and also reduces the penetration volume of the blade. This enables high-precision cutting with minimal deformation or burrs for relatively soft materials. In particular, cutting performance with an emphasis on sharpness can be achieved for objects with low cutting resistance, such as resin films and soft materials.

[0022] (3) By setting the blade angle θ1 in the range of 20°≦θ1≦30° and further setting the angle difference θ2-θ1 to a large value of 20≦θ2-θ1≦60°, the cutting edge is not too sharp, the angles on both sides toward the base are reduced, and the increase in blade thickness is also suppressed, so the cutting edge is strong and durable, while the contact area between the blade side and the cutting surface during cutting is reduced, providing a high-performance blade that combines cutting quality and durability. Therefore, it is possible to maintain good cutting even with hard or viscous materials while preventing chipping of the cutting edge, and it can be used as a blade with excellent wear resistance and durability.

[0023] (4) By setting the ratio θ2 / θ1 of the tangent angle θ2 to the cutting angle θ1 in the range of 1.2≦θ2 / θ1≦4.0, it becomes possible to easily design the optimal blade shape according to the object to be cut, and it is possible to provide a highly versatile blade that can be applied to a variety of industrial fields. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is an explanatory diagram showing the changes in the microscopic state of the cutting edge and the object when the blade cuts the object. [Figure 2] FIG. 10 is an explanatory diagram showing how a blade enters an object to be cut and slides while pressing and rubbing against the cutting surface. [Figure 3] 1 is an external view showing an example of use of a blade according to an embodiment of the present invention; [Figure 4] (a) is an external view of the blade, (b) is an enlarged view of the cutting edge, and (c) is a cross-sectional view in a plane perpendicular to the blade length direction (the blade length L direction). [Figure 5] FIG. 2 is an explanatory diagram of a plane perpendicular to the blade length direction. [Figure 6] FIG. 2 is a cross-sectional view of an embodiment of a two-stage blade structure taken along a plane perpendicular to the blade length direction. [Figure 7] FIG. 10 is a cross-sectional view showing an example of an asymmetric blade. [Figure 8] FIG. 10 is an explanatory diagram of the amount of oblique cutting. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following describes in detail an embodiment of the present invention. However, the description of each component described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to the following content unless the gist of the present invention is changed.

[0026] Fig. 3 is an external view showing an example of use of a blade according to an embodiment of the present invention. Fig. 4(a) is an external view of the blade, Fig. 4(b) is an enlarged view of the cutting edge, and Fig. 4(c) is a cross-sectional view taken along a plane perpendicular to the blade length direction (the blade length L direction). Fig. 5 is an explanatory view of a plane perpendicular to the blade length direction.

[0027] The main cutting objects (hereinafter referred to as "workpieces") of the blades in the embodiments of the present invention include soft materials such as resin films, as well as relatively hard materials such as carbon fiber and glass epoxy.

[0028] The blade material may be stainless steel, high-speed steel, ceramic, diamond, or cemented carbide, but cemented carbide is preferred from the viewpoint of achieving both cutting performance and durability. When the cemented carbide for cutlery is a WC-Co system, the WC grain size is preferably 0.1 μm to 2.5 μm, and the Co content is preferably 6 to 24%. Furthermore, to suppress chipping and improve wear resistance, the WC grain size is preferably 0.1 to 0.7 μm, and the Co content is preferably in the range of 6 to 14%.

[0029] Alternatively, a coating containing diamond may be applied to at least the cutting edge, in which case the outer shape of the blade is formed in a state that includes the coating.

[0030] As shown in FIG. 3, the blade 1 in this embodiment includes a base 10 and a blade portion 20 having a cutting edge 21 at its tip. The blade portion 20 is formed continuously with the base 10. The base 10 is flat and is attached to a mounting portion M of a cutting device (not shown). The blade portion 20 is a cutting execution portion and cuts the workpiece 100. Note that in this embodiment, the blade 1 has a straight blade, and although an example of use in a push-cutting operation is shown, it can also be applied to other shaping and cutting methods, such as slicing.

[0031] As shown in Fig. 4, the blade portion 20 is configured so that its thickness gradually decreases from the base 10 toward the cutting edge 21. As shown in Fig. 4(c), the side surfaces 20A and 20B located on both sides of the cutting edge 21 in the blade thickness direction of the blade portion 20 are each configured with inclined flat surfaces 23A and 23B and curved surfaces 22A and 22B continuing therefrom. The curved surfaces 22A and 22B are formed in a range of approximately 10 to 50 µm from the cutting edge 21. That is, the curved surfaces 22A and 22B start at the cutting edge 21, end approximately 10 to 50 µm from the cutting edge, and connect to the inclined flat surfaces 23A and 23B.

[0032] In the blade 1 of this embodiment, the angle (blade angle) formed by the inclined plane 23A and the side surface opposite to the inclined plane 23A (i.e., the inclined plane 23B) is defined as θ1. Furthermore, when the angle (tangent angle) formed by two tangent lines 24A and 24B that are tangent to both side surfaces (i.e., the curved surfaces 22A and 22B) of the blade portion 20 on a plane A (see FIG. 5) perpendicular to the blade length direction at a position 2 μm from the cutting edge 21 toward the base 10 is defined as θ2, 10°≦θ1≦20° 4°≦θ2-θ1≦20° The configuration shall satisfy the following.

[0033] With this configuration, cutting edge 21 is sharp and has excellent biting properties, and the shape changes smoothly from cutting edge 21 toward base 10, thereby mitigating stress concentration on cutting edge 21. In other words, it is possible to provide a high-performance blade that combines cutting ability and durability in the early stages of cutting, and by reducing the contact area between the blade side and the cutting surface during cutting, it is possible to provide a blade that combines cutting quality and durability, and is therefore suitable for high-precision cutting of resin films, soft materials, etc.

[0034] In addition, the cutting edge angle θ1 and tangent angle θ2 are as follows: 20°≦θ1≦30° 20≦θ2-θ1≦60° It is possible to have a configuration that satisfies the above.

[0035] With this configuration, while the cutting edge has a relatively obtuse angle, the angle of both side surfaces toward the base is reduced and the increase in blade thickness is also suppressed, so the cutting edge has strength and durability, while the contact area between the blade side and the cutting surface during cutting is reduced, making it possible to provide a high-performance blade that combines cutting quality and durability.As a result, it is possible to maintain good cutting while suppressing chipping of the cutting edge even when cutting hard materials or highly viscous materials, and the shape is excellent in wear resistance and durability, making it suitable for cutting hard materials such as carbon fiber and glass epoxy.

[0036] That is, the blade 1 in this embodiment has the following blade angle θ1 and tangent angle θ2: 10°≦θ1≦30° 4°≦θ2-θ1≦60° By satisfying this requirement, the shape changes smoothly from the cutting edge 21 toward the base 10, and in particular, by setting the angle difference θ2-θ1 between the tangent angle θ2 and the cutting angle θ1 within a range of 4° to 60° in an extremely small range of 2 μm from the cutting edge, a high-performance blade that combines cutting quality and durability can be provided.

[0037] The shape of the blade portion 30 may also be a two-stage blade structure as shown in Fig. 6. Fig. 6 is a cross-sectional view of an embodiment of the two-stage blade structure taken along a plane perpendicular to the blade length direction. In this case, the side surfaces 30A, 30B of the blade portion 30 are configured such that, in a range L1 extending from the cutting edge 31 toward the base 10, they are configured with curved surfaces 32A, 32B, a range L2 is configured with first inclined planes 33A, 33B that are continuous with the curved surfaces 32A, 32B, respectively, and a range L3 is configured with second inclined planes 34A, 34B that are continuous with the first inclined planes 33A, 33B, respectively, and have a different inclination angle.

[0038] In this case, the cutting edge angle θ1 is the angle between the first inclined plane 33A, which is the inclined plane closest to the cutting edge 31 of the cutting portion 30 and is the first inclined plane continuing from the curved surfaces 32A and 32B, and the side surface opposite to this first inclined plane 33A (i.e., the first inclined plane 33B). A multi-stage blade with three or more stages is also possible. In either case, the tangent angle θ2 is the angle between two tangent lines 35A and 35B that are tangent to both side surfaces of the cutting portion 30 (i.e., the curved surfaces 32A and 32B) on planes perpendicular to the blade length direction, as described above, at a position 2 μm from the cutting edge 31 toward the base 10.

[0039] Although the above-described blade portions 20 and 30 have a symmetrical shape in a cross section perpendicular to the blade length direction, they can also have an asymmetrical shape. Furthermore, although the above-described blade portions 20 and 30 have a double-edged configuration, they can also have a single-edged configuration. That is, at least one side surface of the blade portions 20 and 30 may be composed of one or more inclined planes and a curved surface continuing therefrom.

[0040] Figure 7 is a cross-sectional view showing an example of an asymmetrical blade. As shown in Figure 7, the cutting angle between straight line 40 that passes through cutting edge 41 and is parallel to the base and right-side inclined flat surface 43A closest to cutting edge 41 is θ1', the cutting angle between left-side inclined flat surface 43B closest to cutting edge 41 is θ1'', the angle between right-side tangent line 44A at a position 2 μm from cutting edge 41 towards the base is θ2', and the angle between left-side tangent line 44B at a position 2 μm from cutting edge 41 towards the base is θ2''.

[0041] In this case, for an asymmetrical cutting tool, θ1' + θ1'' = θ1, θ2' + θ2'' = θ2, but θ1' ≠ θ1'' and / or θ2' ≠ θ2''. In the example of Figure 1(a), θ1' > θ1'' and θ2' > θ2''. In the example of Figure 1(b), θ1' > θ1'' and θ2' < θ2''.

[0042] In addition, for a blade with a single blade, θ1' = 0 or θ1'' = 0. In the example of Figure 2(c), θ1' = 0 and θ2' > θ2''. In both the asymmetric blade and the single blade, the ranges of θ1 and θ2 are the same as for a blade with a symmetrical double blade. [Example]

[0043] (Evaluation 1: PET sheet cutting test) Blade 1 shown in Figure 4(a) was manufactured, and an evaluation workpiece was cut to evaluate its cutting quality and durability. Blade 1 was made of a WC-Co based cemented carbide alloy, with a blade length L of 250 mm, a blade thickness t of 0.1 mm, and a width W of 20 mm. Several blades were manufactured with different combinations of blade angle θ1 and tangent angle θ2 within the ranges of 8°≦θ1≦22° and 0°≦θ2-θ1≦28°.

[0044] Cutting was performed using a servo press manufactured by Electric Discharge Precision Machining Laboratory, with a feed pitch of 1 mm. A measuring microscope MM-800 manufactured by Nikon Instech was used to observe the cut surface and measure wear. The shape of the cutting edge was observed by observing the cross section of the blade with a Keyence electron microscope VE-8000, and r, θ1, and θ2 were measured using the attached measurement function. The roughness Ra (arithmetic mean roughness) of the cut surface was measured with a Zygo Newview 7200.

[0045] A 0.2 mm thick PET sheet was used as the evaluation workpiece. The evaluation procedure consisted of evaluating the cutting quality followed by an evaluation of durability (life test). The cutting quality was evaluated by measuring the roughness Ra of the cut surface using a Newview 7200. Meanwhile, the life test was evaluated by observing the cut surface using a measuring microscope MM-800 after 1,000 cutting tests.

[0046] The criteria for judging cutting quality were as follows: if the roughness Ra of the cut surface was 0.16 μm or less and there was no cutting debris, it was marked "○"; if the roughness Ra of the cut surface was more than 0.16 μm but less than 0.6 μm and there was no cutting debris, it was marked "△"; and if the roughness Ra of the cut surface was more than 0.6 μm or cutting debris was produced, it was marked "×".

[0047] On the other hand, regarding durability, the size of the chipping at the tip was observed after 1000 cuts, and if the size of the chipping at the tip was less than 3 μm, it was marked as "○", if the size of the chipping at the tip was 3 μm or more but less than 5 μm, it was marked as "△", and if the size of the chipping at the tip was 5 μm or more, it was marked as "×".

[0048] In terms of both cutting quality and durability, blades that are judged as "good" or "good" can be said to satisfy the conditions.

[0049] Table 1 shows the evaluation results of the blade according to this embodiment. As shown in Table 1, by adopting an appropriate shape (parameters), the blade according to this embodiment was able to be made to have excellent durability as well as sharpness.

[0050] [Table 1]

[0051] (Evaluation 2: Cutting test of glass epoxy board) Blade 1 shown in Figure 4(a) was manufactured, and an evaluation workpiece was cut to evaluate its cutting quality and durability. Blade 1 was made of a WC-Co based cemented carbide alloy, with a blade length L of 250 mm, a blade thickness t of 0.1 mm, and a width W of 20 mm. Several blades were manufactured with different combinations of blade angle θ1 and tangent angle θ2 within the ranges of 18°≦θ1≦32° and 16°≦θ2-θ1≦64°.

[0052] Cutting was performed using a servo press manufactured by Electric Discharge Precision Machining Laboratory, with a feed pitch of 5 mm. A measuring microscope MM-800 manufactured by Nikon Instech was used to observe the cut surface and measure wear. The shape of the cutting edge was observed by observing the cross section of the blade with a Keyence electron microscope VE-8000, and r, θ1, and θ2 were measured using the attached measurement function. The roughness Ra (arithmetic mean roughness) of the cut surface was measured with a Zygo Newview 7200.

[0053] The evaluation workpiece used was a glass epoxy board with a thickness of 1.6 mm and 35 μm copper foil on both sides. The evaluation procedure consisted of evaluating the cutting quality followed by an evaluation of durability (life test). The cutting quality was evaluated by the amount of oblique cutting of the evaluation workpiece after cutting. Oblique cutting is a phenomenon in which the cross section of the cut workpiece is tilted due to factors such as the sharpness of the blade and uneven friction resistance between the blade and the workpiece during cutting. The definition of the amount of oblique cutting is as shown in Figure 8. The amount of oblique cutting was measured using a measuring microscope MM-800. On the other hand, the life test was evaluated by observing the cut surface using a measuring microscope MM-800 after 100 cutting tests.

[0054] When the amount of oblique cutting was less than 50 μm, it was rated as "○", when the amount of oblique cutting was 50 μm or more but less than 75 μm, it was rated as "△", and when the amount of oblique cutting was 75 μm or more, it was rated as "X". On the other hand, for durability, the size of the chipping at the tip was observed after 100 cuts, and when the size of the chipping at the tip was less than 10 μm, it was rated as "○", when the size of the chipping at the tip was 10 μm or more but less than 30 μm, it was rated as "△", and when the size of the chipping at the tip was 30 μm or more, it was rated as "X". On the other hand, regarding durability, the size of the chipping at the tip was observed after 100 cuts, and if the size of the chipping at the tip was less than 3 μm, it was marked as "○", if the size of the chipping at the tip was 3 μm or more but less than 5 μm, it was marked as "△", and if the size of the chipping at the tip was 5 μm or more, it was marked as "×".

[0055] In terms of both cutting quality and durability, blades that are judged as "good" or "good" can be said to satisfy the conditions.

[0056] The evaluation results are shown in Table 2. As shown in Table 2, the blade according to this embodiment was able to be made to have excellent durability as well as sharpness by adopting an appropriate shape (parameters).

[0057] [Table 2] [Industrial Applicability]

[0058] The blade of the present invention is capable of achieving both precise cutting performance and high durability, and is useful for processing and cutting high-performance materials in a variety of fields. In particular, it contributes to improving the quality of the cut surface and extending the blade life in situations where precise cutting is required, such as resin films, composite materials, carbon fiber, and glass epoxy. Therefore, the present invention can be widely used in a variety of industrial fields, including electronic components, displays, packaging, the medical field, and industrial rubber and plastic processing. [Explanation of symbols]

[0059] 1. Cutlery 10 base 20,30 Blade part 21, 31, 41 Cutting edge 22A,22B,32A,32B curved surface 23A,23B,33A,33B,43A,43B Inclined plane 24A,24B,35A,35B,44A,44B Tangent 40 Reference Line 100 Work

Claims

1. The blade has a base and a cutting edge at its tip. The blade portion has a thickness that gradually decreases from the base toward the cutting edge, and at least one side surface of the blade portion is composed of one or more inclined planes and a curved surface continuous therewith, and a position 2 μm from the cutting edge toward the base is located on the curved surface, The angle formed by the inclined plane closest to the cutting edge side of the cutting edge and the side surface opposite to this inclined plane is defined as θ 1 year, The angle formed by two tangents that are tangent to both sides of the blade on a plane perpendicular to the blade length direction at a position 2 μm from the cutting edge toward the base is defined as θ 2 When 10°≦θ 1 ≦30° 4°≦θ 2 -θ 1 ≦60° A blade characterized by:

2. The blade has a base and a cutting edge at its tip. The blade portion has a thickness that gradually decreases from the base toward the cutting edge, and at least one side surface of the blade portion is composed of one or more inclined planes and a curved surface continuous therewith, and a position 2 μm from the cutting edge toward the base is located on the curved surface, The angle formed by the inclined plane closest to the cutting edge side of the cutting edge and the side surface opposite to this inclined plane is defined as θ 1 year, The angle formed by two tangents that are tangent to both sides of the blade on a plane perpendicular to the blade length direction at a position 2 μm from the cutting edge toward the base is defined as θ 2 When 10°≦θ 1 ≦20° 4°≦θ 2 -θ 1 ≦20° A blade characterized by:

3. The blade has a base and a cutting edge at its tip. The blade portion has a thickness that gradually decreases from the base toward the cutting edge, and at least one side surface of the blade portion is composed of one or more inclined planes and a curved surface continuous therewith, and a position 2 μm from the cutting edge toward the base is located on the curved surface, The angle formed by the inclined plane closest to the cutting edge side of the cutting edge and the side surface opposite to this inclined plane is defined as θ 1 year, The angle formed by two tangents that are tangent to both sides of the blade on a plane perpendicular to the blade length direction at a position 2 μm from the cutting edge toward the base is defined as θ 2 When 20°≦θ 1 ≦30° 20≦θ 2 -θ 1 ≦60° A blade characterized by:

4. 1.2≦θ 2 / θ 1 The blade according to any one of claims 1 to 3, wherein the hardness is ≦4.0.

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