Fine line forming tool

Abstract

The present invention aims to provide a highly innovative fine-wire forming tool unlike anything in the conventional invention. [Solution] A fine wire forming tool for cutting and forming a fine wire 51 by moving it in contact with a workpiece 50, the tool having a plate-shaped cutting portion 1 made of cemented carbide with a rectangular cross-section at its tip, the plate-shaped cutting portion 1 being composed of a lower side portion 2 facing the direction of movement when cutting and forming the fine wire 51, an upper side portion 3 provided on the side opposite to the lower side portion 2 and inclined so as to move away from the lower side portion 2 towards the base end, and a tip vertical portion 4 between the tips of the lower side portion 2 and the upper side portion 3, the tool having a cutting edge 5a at the connecting corner 5 between the lower side portion 2 and the tip vertical portion 4.

Description

[[Technical Field]]

[0001] The present invention relates to a fine line forming tool. [[Background Art]]

[0002] Conventionally, there has been proposed a fine line forming tool (hereinafter referred to as "conventional example") for cutting and forming (groove-engraving) a fine line in the shape of a concave groove by moving the tool into contact with a workpiece made of plastic, for example.

[0003] As shown in FIG. 11, this conventional example has a plate-shaped cutting portion made of cemented carbide with a square longitudinal cross-section at the tip end. The plate-shaped cutting portion is composed of a lower side surface oriented in the moving direction when cutting and forming the fine line, and an upper side surface provided on the side opposite to the lower side surface and inclined such that the closer to the base end, the farther away from the lower side surface. A cutting edge is provided at the continuous corner between the tip of the lower side surface and the tip of the upper side surface. The plate-shaped cutting portion (the cutting edge) is brought into contact with the workpiece, and is pulled so that the lower side surface faces the moving direction, thereby forming the fine line.

[0004] It should be noted that the angle of the continuous corner in the conventional example is generally 28 to 47 degrees, and the reason why the upper side surface is inclined relative to the lower side surface is to enable processing at a corner portion where a wall surface rises near the processing surface on which the fine line is cut and formed, or in a narrow processing area, for example. [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0005] By the way, in the conventional example, although the plate-shaped cutting portion is made of cemented carbide, is hard, hard to break, and can provide a good cutting effect, as described above, the continuous corner between the lower side surface and the upper side surface is sharp and thin, which further leads to the problem that it is brittle and prone to chipping (a concave chipped portion occurs on the cutting edge) (see FIG. 12).

[0006] If a defect 35b is created in the cutting edge 35a when cutting, a distinct raised ridge 51a is formed on the bottom surface of the thin wire 51 (see Figure 13), which many users dislike as it looks unsightly.

[0007] This invention was made in view of the aforementioned situation and provides a highly innovative fine wire forming tool unlike anything in the conventional range. [Means for solving the problem]

[0008] The gist of the present invention will be explained with reference to the attached drawings.

[0009] This fine wire forming tool is used to cut and form a fine wire 51 by moving it in contact with a workpiece 50, and has a plate-shaped cutting portion 1 made of cemented carbide with a rectangular cross-section at its tip, the plate-shaped cutting portion 1 is composed of a lower side portion 2 facing the direction of movement when cutting and forming the fine wire 51, an upper side portion 3 provided on the side opposite to the lower side portion 2 and inclined so as to move away from the lower side portion 2 towards the base end, and a tip vertical portion 4 located between the tips of the lower side portion 2 and the upper side portion 3, and a cutting edge 5a is provided at the connecting corner portion 5 between the lower side portion 2 and the tip vertical portion 4.

[0010] Furthermore, the present invention relates to a fine wire forming tool according to claim 1, characterized in that the inclination angle of the upper side portion 3 with respect to the lower side portion 2 is set to 10 to 45 degrees, and the angle of the connecting corner portion 5 between the lower side portion 2 and the tip vertical portion 4 is set to 85 to 95 degrees.

[0011] Furthermore, the present invention relates to a fine wire forming tool according to either claim 1 or 2, characterized in that the height L of the tip vertical surface portion 4 is set to 0.005 mm to 0.05 mm.

[0012] Furthermore, the fine wire forming tool according to either claim 1 or 2 is characterized in that the plate-shaped cutting portion 1 has a uniform thickness from the lower surface portion 2 to the upper predetermined position P1, and the thickness from the upper predetermined position P1 to the upper surface portion 3 becomes thinner towards the top.

[0013] Furthermore, the fine wire forming tool according to claim 3 is characterized in that the plate-shaped cutting portion 1 has a uniform thickness from the lower surface portion 2 to the upper predetermined position P1, and the thickness from the upper predetermined position P1 to the upper surface portion 3 becomes thinner towards the top.

[0014] Furthermore, the present invention relates to a fine wire forming tool according to either claim 1 or 2, characterized in that the plate-shaped cutting portion 1 has a shape in which the plate thickness becomes thinner towards the base end.

[0015] Furthermore, the fine wire forming tool according to claim 3 is characterized in that the plate-shaped cutting portion 1 has a shape in which the plate thickness becomes thinner towards the base end.

[0016] Furthermore, the fine wire forming tool according to claim 4 is characterized in that the plate-shaped cutting portion 1 has a shape in which the plate thickness becomes thinner towards the base end.

[0017] Furthermore, the fine wire forming tool according to claim 5 is characterized in that the plate-shaped cutting portion 1 has a shape in which the plate thickness becomes thinner towards the base end.

[0018] Furthermore, the present invention relates to a fine wire forming tool according to either claim 1 or 2, characterized in that chamfered portions 6a are provided at the left and right corners 6 of the tip vertical portion 4 of the plate-shaped cutting portion 1.

[0019] Furthermore, the present invention relates to a fine wire forming tool according to either claim 1 or 2, characterized in that a support portion 1' is provided at the base end of the plate-shaped cutting portion 1, and this support portion 1' is connected to the handle 10. [Effects of the Invention]

[0020] Since the present invention is configured as described above, compared with the conventional example described above, a deficient portion is less likely to occur at the cutting working edge, and furthermore, thin lines can be formed by cutting easily and quickly. Thus, the present invention provides a very innovative thin line forming tool that has never existed before. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] [Figure 1] FIG. 1 is a perspective view showing the present embodiment. [Figure 2] FIG. 2 is an explanatory view of essential parts according to the present embodiment. [Figure 3] FIG. 3 is an explanatory view of essential parts according to the present embodiment. [Figure 4] FIG. 4 is an explanatory view of essential parts according to the present embodiment. [Figure 5] FIG. 5 is a schematic A-A cross-sectional view of FIG. 2. [Figure 6] FIG. 6 is a schematic explanatory view of essential parts according to the present embodiment. [Figure 7] FIG. 7 is an explanatory view showing the usage state of the present embodiment. [Figure 8] FIG. 8 is an operation explanatory view of essential parts according to the present embodiment. [Figure 9] FIG. 9 is an operation explanatory view of essential parts according to the present embodiment. [Figure 10] FIG. 10 is an explanatory view showing a case where a deficient portion 5b occurs at a cutting working edge 5a according to the present embodiment. [Figure 11] FIG. 11 is an explanatory view of essential parts according to a conventional example. [Figure 12] FIG. 12 is an explanatory view showing a case where a deficient portion 35b occurs at a cutting working edge 35a according to a conventional example. [Figure 13] FIG. 13 is an operation explanatory view of essential parts according to a conventional example. DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Preferred embodiments of the present invention will be briefly described below by illustrating the operation of the present invention based on the drawings.

[0023] Using the fine wire forming tool according to the present invention, when the connecting corner portion 5 (cutting edge 5a) provided on the plate-shaped cutting portion 1 made of cemented carbide is brought into contact with the workpiece 50 and the tool is moved in this state, the workpiece 50 is cut by the cutting edge 5a, and fine wires 51 are formed on the workpiece 50.

[0024] Incidentally, the plate-shaped cutting section 1 according to the present invention is composed of a lower side portion 2 facing the direction of movement when cutting and forming a thin wire 51, an upper side portion 3 provided on the side opposite to the lower side portion 2 and inclined so that it moves further away from the lower side portion 2 towards the base end, and a tip vertical portion 4 located between the tips of the lower side portion 2 and the upper side portion 3, with a cutting edge 5a provided at the connecting corner 5 between the lower side portion 2 and the tip vertical portion 4.

[0025] Therefore, the connecting corner portion 5, where the cutting edge 5a is provided, is thick in the vertical direction and has strong strength against the load when cutting and forming the thin wire 51.

[0026] Therefore, it is less likely that a chipped portion 5b will occur on the cutting edge 5a, and since it has sufficient strength to withstand the workpiece 50 (material) and can be cut with light force, the cutting and shaping of the fine wire 51 can be performed easily and quickly. [Examples]

[0027] Specific embodiments of the present invention will be described with reference to the drawings.

[0028] This embodiment is a fine wire forming tool for cutting and forming fine wires 51 by moving it in contact with a workpiece 50. In this embodiment, a synthetic resin component (a part of a plastic model) is used as the workpiece 50, and the tool is applied to cut and form fine wires 51 on this workpiece 50, consisting of a bottom surface 51' and an inner wall surface 51'' with a depth of approximately 0.2 mm to 0.3 mm (maximum of about 1 mm).

[0029] Specifically, as shown in Figure 1, this embodiment consists of a handle 10 and a plate-shaped cutting section 1 that is detachably attached to the tip connecting portion 10a of the handle 10. This plate-shaped cutting section 1 is provided at the tip of an elongated plate-shaped body made of cemented carbide (the portion from the tip to a predetermined position P2 on the base side, which is the connection point with the support portion 1'), and has a rectangular cross-section (rectangular cross-section of plate thickness) with a plate thickness of 0.1 mm (within the range of 0.1 to 6.0 mm). The support portion 1' is connected to the handle 10 (tip connecting portion 10a).

[0030] Furthermore, the plate-shaped cutting section 1 is composed of a lower side portion 2 facing the direction of movement when cutting and forming the thin wire 51, an upper side portion 3 provided on the opposite side of the lower side portion 2 and inclined so that it moves further away from the lower side portion 2 towards the base end, and a tip vertical portion 4 located between the tips of the lower side portion 2 and the upper side portion 3, with a cutting edge 5a provided at the connecting corner 5 between the lower side portion 2 and the tip vertical portion 4.

[0031] In this embodiment, the inclination angle θ1 of the upper surface portion 3 relative to the lower surface portion 2 is set to 25 degrees (10 to 45 degrees), and the angle θ2 (internal angle) of the connecting corner 5 between the lower surface portion 2 and the tip vertical surface portion 4 is set to 90 degrees. Furthermore, another upper surface portion 3' with a smaller inclination angle is continuously formed at the base end of the upper surface portion 3, which is the support portion 1'.

[0032] The inventors have found through various tests that when the angle θ2 of the connecting corner portion 5 is between 85 and 95 degrees, sufficient strength (strength comparable to that of plastic) is ensured, the cutting edge 5a is less prone to chipping, and good usability is achieved, such as being able to cut with light force.

[0033] In other words, if the angle θ2 is made smaller than 85 degrees (acute angle), the cutting edge 5a is more likely to be damaged. On the other hand, if the angle θ2 is made larger than 95 degrees (obtuse angle), the strength increases, but the workpiece 50 cannot be cut properly (cannot be cut with light force). In addition, problems occur such as the upper part of the cutting edge 5a interfering with the work in corner areas where a wall rises near the machined surface formed by cutting the thin wire 51, or in narrow machined areas, hindering the work, or the cutting angle becoming narrower.

[0034] Therefore, in this embodiment, the angle θ2 of the connecting corner 5 is set to 85 to 95 degrees, most preferably 90 degrees, and the aforementioned problems do not occur.

[0035] Furthermore, in this embodiment, as shown in Figures 3 and 4, the tip elevation portion 4 has a rectangular shape when viewed from the front, and the height L in the rising direction of this tip elevation portion 4 is set to 0.02 mm.

[0036] The inventors have conducted various experiments in this regard and have confirmed that when the height L of the tip surface portion 4 is 0.005 mm to 0.05 mm, sufficient strength (strength that can withstand plastic) is ensured, the cutting edge 5a is less likely to break, and good usability is obtained, such as being able to cut with light force.

[0037] In other words, if the height L of the tip surface portion 4 is made narrower (thinner) than 0.005 mm, the cutting edge 5a becomes more prone to chipping, and moreover, the cutting function of the cutting edge 5a deteriorates, making it impossible to cut the thin wire 51 flat. On the other hand, if the height L of the tip surface portion 4 is made wider (thicker) than 0.05 mm, the strength increases, but problems arise such as the upper part of the cutting edge 5a interfering with the work in corner areas where a wall surface rises near the processed surface formed by cutting the thin wire 51, or in narrow processed areas.

[0038] Therefore, in this embodiment, the height L of the tip vertical surface portion 4 is set to 0.005 mm to 0.05 mm, most preferably 0.02 mm, and the aforementioned problems do not occur.

[0039] In addition to the shape of the plate-shaped cutting section 1 according to the embodiment described above (a shape consisting of a lower side section 2, an upper side section 3, and a tip vertical section 4), the setting of the angle θ2 of the connecting corner section 5 and the setting of the height L of the tip vertical section 4 help to prevent damage to the cutting edge 5a as much as possible.

[0040] Incidentally, even with the aforementioned configuration, as shown in Figure 10, a defect 5b may occur in the cutting edge 5a due to aging or dropping. However, because it has the aforementioned tip elevation surface 4 of height L, the defect 5b does not penetrate from front to back, and the edge of this defect 5b also functions as the cutting edge 5a. Therefore, unlike in conventional examples, a distinct convex ridge 51b is not formed on the bottom surface of the thin wire 51, and it can be used for a long period of time as is.

[0041] Furthermore, in this embodiment, as shown in Figures 2 to 4, chamfered portions 6a (C-faces) are provided at the left and right corners 6 of the tip vertical portion 4 of the plate-shaped cutting portion 1 (the connecting corners between the tip vertical portion 4 of the plate-shaped cutting portion 1 and the left and right side surfaces 1a).

[0042] These left and right chamfered sections 6a are inclined inward toward the tip and are provided across the entire area of ​​the left and right corners 6, thus being connected to the left and right edges 5a' of the cutting edge 5a. The chamfering angle is 45 degrees (40 to 50 degrees is appropriate), and the dimensions of each chamfer (cutting length) are set to 0.005 mm (0.003 to 0.02 mm if the plate thickness of the plate cutting section 1 is 0.1 to 0.2 mm, and 0.005 to 0.1 mm is appropriate if the plate thickness of the plate cutting section 1 is thicker than 0.2 mm).

[0043] With this configuration, the left and right edges 5a' of the cutting edge 5a are located inward from the plate thickness position of the plate-shaped cutting section 1, and compared to the conventional example described above, a clean fine line 51 can be cut and formed easily and quickly.

[0044] Specifically, in conventional examples, the left and right edges 35a' of the cutting edge 35a extend to the thickness of the plate-shaped cutting portion 31, which presented the following problems.

[0045] In other words, when forming a fine wire 51 on a workpiece 50 by cutting, the cutting process may involve repeatedly tracing the surface until the desired depth (generally 0.2 to 0.3 mm) is reached. However, when attempting to insert the plate-shaped cutting portion 31 into the fine wire 51 for the second time or later, the left and right edges 35a catch on the inner edge of the opening of the fine wire 51, making insertion difficult. Consequently, the inner edge of the opening of the fine wire 51 may be cut, requiring repair.

[0046] Furthermore, in conventional methods, when tracing the previously cut area, it is difficult to insert the plate-shaped cutting part 31 straight into the thin line 51. If the cutting is done without noticing that it is not straight, the cutting may extend beyond the previously cut area. Alternatively, even if it is straight, the left and right edges 35a' tend to cut into the inner wall surface 51" of the thin line 51 and try to ride up, similarly causing the cutting to extend beyond the previously cut area, and in either case, repair is required.

[0047] Furthermore, in conventional cases, not only when tracing the previously trimmed area as described above, but also when attempting to trim an area that has not yet been trimmed, the left and right edges 35a may have an action that causes them to cut in the left or right direction depending on the amount of force applied (a subtle adjustment), making it impossible to trim straight (in the direction desired by the user).

[0048] Furthermore, in conventional cases, as mentioned above, a cutting action occurs in the left-right direction, meaning that stress is placed on the left and right sides, making those areas prone to damage.

[0049] In this respect, this embodiment is configured such that chamfered portions 6a are provided on the left and right corners 6 of the tip vertical portion 4 of the plate-shaped cutting portion 1, and the left and right edges 5a' of the cutting edge 5a are not located at the plate thickness position of the plate-shaped cutting portion 1. Therefore, the problems of the conventional example described above can be reliably resolved, and a clean, fine line 51 can be cut and formed easily and quickly as desired by the user.

[0050] In other words, when scraping by tracing over the line multiple times, when attempting to insert the plate-shaped scraping section 1 into the thin line 51 for the second time or later, the left and right edges 5' do not catch on the inner edge of the opening of the thin line 51, making it easier to insert and preventing the inner edge of the opening of the thin line 51 from being scraped away.

[0051] Furthermore, in this embodiment, when tracing the previously cut area, it is easy to insert the plate-shaped cutting part 1 straight into the thin line 51, and in this straight state, the previously cut area can be traced and cut. Moreover, in accordance with the shape of the chamfered part 6a, an inclined surface 51a is formed in the thin line 51 at the connecting corner between the bottom surface 51' and the inner wall surface 51'' (see Figures 8 and 9). This inclined surface 51a acts as a guide to support the chamfered part 6a, preventing it from riding up onto the inner wall surface 51'' when tracing the previously cut area, and allowing for good cutting by tracing the previously cut area.

[0052] Furthermore, in this embodiment, the presence of the left and right chamfered portions 6a prevents cutting action in the left-right direction, making it less likely to bend unexpectedly, and allowing the user to reliably move the plate-shaped cutting portion 1 to the desired position.

[0053] Furthermore, in this embodiment, the presence of the left and right chamfered portions 6a prevents chipping of the left and right portions of the cutting edge 5a, which is prone to stress.

[0054] Furthermore, in this embodiment, it has been confirmed that if the corner chamfering dimensions (cutting length) of the left and right chamfered portions 6a are not set to the above dimensions, but are set to be approximately the same as the left and right widths of the tip vertical portion 4 (equally 1 / 3 of the plate thickness each), the stability during cutting is further increased.

[0055] Specifically, for example, if the plate thickness of the plate-shaped cutting section 1 is 0.08 mm, the left and right width of the tip vertical section 4 and the chamfer dimensions of the left and right chamfer sections 6 are set to 0.026 mm (±10%). If the plate thickness of the plate-shaped cutting section 1 is 0.1 mm, the left and right width of the tip vertical section 4 and the chamfer dimensions of the left and right chamfer sections 6 are set to 0.033 mm (±10%). If the plate thickness of the plate-shaped cutting section 1 is 0.2 mm, the left and right width of the tip vertical section 4 and the chamfer dimensions of the left and right chamfer sections 6 are set to 0.066 mm (±10%).

[0056] In this configuration, a large inclined surface 51a is formed at the corner where the bottom surface 51' and the inner wall surface 51'' meet within the thin wire 51. If there is a need to remove this large inclined surface 51a, the so-called finishing process can be performed by removing the large inclined surface 51a using the above-mentioned dimension setting, where the left and right width of the tip vertical surface 4 is wider than the corner chamfering dimension (cutting length) of the left and right chamfered sections 6a.

[0057] Next, in this embodiment, as shown in Figures 2, 3, and 5, the plate-shaped cut section 1 has a vertical cross-sectional shape in which the plate thickness is uniform from the lower surface portion 2 to the upper predetermined position P1, and the plate thickness from the upper predetermined position P1 to the upper surface portion 3 becomes thinner towards the top.

[0058] In this embodiment, the width of the lower side portion 2 is set to 0.01 to 0.1 mm, and the width of the upper side portion 3 is set to 0.099 to 0.09 mm. Note that Figure 5 is a schematic diagram that does not reflect the actual dimensions, but is intended to show the change in plate thickness.

[0059] With this configuration, the lower portion that performs the cutting and shaping function has the strength necessary to cut the workpiece 50, and the upper portion does not come into contact with the inner wall surface 51" of the thin wire 51 (or does not come into contact with it easily, or even if it does come into contact, it does not make pressure contact), so damage to the inner wall surface 51" of the thin wire 51 is prevented, and a large frictional resistance is not generated between it and the inner wall surface 51", so the plate-shaped cutting portion 1 does not break due to overload, and moreover, it can be moved smoothly with light force.

[0060] Incidentally, even if a defect occurs on the left and right side surfaces 1a of the plate-shaped cutting section 1, the cutting can be done at the edges of the defect, so it does not affect the finished product.

[0061] Next, in this embodiment, as shown in Figure 6, the plate-shaped machined portion 1 has a cross-sectional shape in which the plate thickness becomes approximately 0.001 to 0.05 mm thinner towards the base end. Note that Figure 6 is a schematic diagram that does not reflect the actual dimensions, as it shows the change in plate thickness.

[0062] Specifically, if the plate thickness of the tip (the tip vertical surface portion 4 including the chamfered portion 6a) is 0.1 mm, then the plate thickness at the predetermined base end position P2, 1.5 mm from the tip, is set to a plate thickness that is 0.001 to 0.01 mm thinner (0.099 to 0.0090 mm). If the plate thickness of the tip is 0.4 mm, the predetermined base end position P2 is set to 2.0 mm, and if the plate thickness of the tip is 1.0 mm, the predetermined base end position P2 is set to 4.5 mm.

[0063] With this configuration, the left and right side portions 1a of the plate-shaped cutting portion 1 do not come into contact with the inner wall surface 51" of the thin wire 51 (or come into contact with it very little, or even if they do, they do not press against it), thus preventing damage to the inner wall surface 51" of the thin wire 51, and also preventing large frictional resistance from occurring between the inner wall surface 51" and the plate-shaped cutting portion 1 from breaking due to overload. Furthermore, it can be moved smoothly with light force, and moreover, it prevents the thin wire 51 from becoming thicker.

[0064] Furthermore, in this embodiment, even if the base end is repolished up to a predetermined position P2 (1.5 mm), the plate can still be used for thicknesses from 0.1 mm to 0.0095 mm.

[0065] As this embodiment is configured as described above, when the fine wire forming tool (handle 10) is held and the connecting corner portion 5 (cutting edge 5a) provided on the cemented carbide plate-shaped cutting portion 1 is brought into contact with the workpiece 50 and pulled in this state, the workpiece 50 is cut by the cutting edge 5a, and fine wires 51 are formed on the workpiece 50 (see Figure 7).

[0066] Incidentally, the plate-shaped cutting section 1 according to this embodiment is composed of a lower side portion 2 facing the direction of movement when cutting and forming the thin wire 51, an upper side portion 3 provided on the opposite side of the lower side portion 2 and inclined so that it moves further away from the lower side portion 2 towards the base end, and a tip vertical portion 4 located between the tips of the lower side portion 2 and the upper side portion 3, with a cutting edge 5a provided at the connecting corner 5 between the lower side portion 2 and the tip vertical portion 4.

[0067] Therefore, the connecting corner portion 5, where the cutting edge 5a is provided, is thick in the vertical direction and has strong strength against the load when cutting and forming the thin wire 51.

[0068] Therefore, according to this embodiment, it is less likely that a chipped portion 5b will occur on the cutting edge 5a, and moreover, it has sufficient strength to withstand the workpiece 50 (material) and can be cut with light force, thus enabling the cutting and shaping of the fine wire 51 to be simple and quick.

[0069] Furthermore, the present invention is not limited to this embodiment, and the specific configuration of each constituent element can be designed as appropriate. [Explanation of Symbols]

[0070] L Height P1 Upper predetermined position 1. Plate-shaped cutting section 1' Support part 2 Lower side part 3 Upper side part 4. Tip elevation section 5 consecutive corners 5a Edge of cutting action 6 Left and right corners 6a Chamfered section 10 Grip handle 50 Workpiece 51 Thin line

Claims

1. A fine wire forming tool for cutting and forming fine wires by moving it in contact with a workpiece, wherein the tip has a plate-shaped cutting section made of cemented carbide with a rectangular cross-section, and this plate-shaped cutting section is composed of a lower surface portion facing the direction of movement when cutting and forming the fine wire, an upper surface portion provided on the side opposite to the lower surface portion and inclined so as to move away from the lower surface portion towards the base end, and a tip vertical surface portion located between the tips of the lower surface portion and the upper surface portion, and a cutting edge is provided at the connecting corner between the lower surface portion and the tip vertical surface portion.

2. A fine wire forming tool according to claim 1, characterized in that the inclination angle of the upper surface portion with respect to the lower surface portion is set to 10 to 45 degrees, and the angle of the connecting corner between the lower surface portion and the tip vertical surface portion is set to 85 to 95 degrees.

3. A fine wire forming tool according to either claim 1 or 2, characterized in that the height of the tip vertical surface portion is set to 0.005 mm to 0.05 mm.

4. A fine wire forming tool according to either claim 1 or 2, characterized in that the plate-shaped cutting portion has a uniform thickness from the lower surface portion to a predetermined upper position, and the thickness from the predetermined upper position to the upper surface portion becomes thinner towards the top.

5. The fine wire forming tool according to claim 3, characterized in that the plate-shaped cutting portion has a uniform thickness from the lower surface portion to a predetermined upper position, and the thickness from the predetermined upper position to the upper surface portion becomes thinner towards the top.

6. A fine wire forming tool according to either claim 1 or 2, characterized in that the plate-shaped cutting portion has a shape in which the plate thickness becomes thinner towards the base end.

7. A fine wire forming tool according to claim 3, characterized in that the plate-shaped cutting portion has a shape in which the plate thickness becomes thinner towards the base end.

8. A fine wire forming tool according to claim 4, characterized in that the plate-shaped cutting portion has a shape in which the plate thickness becomes thinner towards the base end.

9. A fine wire forming tool according to claim 5, characterized in that the plate-shaped cutting portion has a shape in which the plate thickness becomes thinner towards the base end.

10. A fine wire forming tool according to either claim 1 or 2, characterized in that chamfered portions are provided at the left and right corners of the tip vertical surface of the plate-shaped cutting portion.

11. A fine wire forming tool according to either claim 1 or 2, characterized in that a support portion is provided at the base end of the plate-shaped cutting portion, and this support portion is connected to a handle.

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