Rectangular wire drawing die and method for manufacturing rectangular wire

Abstract

To suppress the occurrence of flaws on a workpiece in drawing.SOLUTION: A rectangular wire drawing die 10 used for drawing and extending a workpiece includes a surface 10c on an inlet side for allowing the workpiece to enter, a surface 10d on an outlet side for drawing the workpiece, and a hole 11 communicating with the surface 10c and the surface 10d. The hole 11 has a rectangular inlet side opening part 10c opened to the surface 11a part and a rectangular outlet side opening part 10d opened to the surface 11a part and having an area smaller than that of the inlet side opening part 11b, and a radius of a corner part 11a of the inlet side opening part 11c is larger than a radius of a corner part 11b of the outlet side opening part 11d.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rectangular wire drawing die and a method for manufacturing a rectangular wire. [Background technology]

[0002] 2. Description of the Related Art A method for manufacturing a rectangular wire is known in which a conductor wire is drawn through a die hole to form a rectangular wire having a rectangular cross section.

[0003] Patent document 1 describes, as an example of a die, a die having a hole formed so that the area gradually decreases from the entrance side to the exit side, and discloses a method for manufacturing a rectangular wire in which a conductive wire is passed through the hole of the die and drawn out to form the rectangular wire. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-4399 Summary of the Invention [Problem to be solved by the invention]

[0005] In the die used in the method for manufacturing a rectangular wire described in Patent Document 1, the radius of the corner of the entrance opening of the rectangular hole of the die that processes a round conductor (workpiece) into a rectangular wire is the same as the radius of the corner of the exit opening of the hole.

[0006] Therefore, when the conductor is inserted into the die, the corners of the conductor come into contact with the corners of the die hole, causing a concentration of surface pressure, which may result in scratches being formed on the conductor.

[0007] An object of the present invention is to provide a rectangular wire drawing die and a rectangular wire manufacturing method that can suppress the occurrence of scratches on a workpiece. [Means for solving the problem]

[0008] The flat wire drawing die of the present invention is a flat wire drawing die used for drawing and stretching a workpiece, and comprises a first surface on the entrance side through which the workpiece is introduced, a second surface on the exit side through which the workpiece is drawn, and a hole connecting the first surface and the second surface, the hole having a rectangular entrance side opening that opens on the first surface and a rectangular exit side opening that opens on the second surface and has an area smaller than that of the entrance side opening, and the radius of the corners of the entrance side opening is larger than the radius of the corners of the exit side opening.

[0009] The flat wire manufacturing method of the present invention is a flat wire manufacturing method in which a workpiece is subjected to a drawing process by drawing and stretching it through a hole in a flat wire drawing die, wherein the hole has a rectangular entrance opening that opens on a first surface on the entrance side of the workpiece, and a rectangular exit opening that opens on a second surface on the exit side of the workpiece and has an area smaller than that of the entrance opening, and the workpiece is introduced through the entrance opening, which has a corner with a radius larger than the radius of the corner of the exit opening, and then the workpiece is drawn and stretched through the exit opening. [Effects of the Invention]

[0010] According to the present invention, it is possible to suppress the occurrence of scratches on a workpiece during drawing. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing a schematic structure of a flat wire drawing die according to an embodiment of the present invention. FIG. [Figure 2] 1 is a cross-sectional view showing the shape of a rectangular wire drawing die according to an embodiment of the present invention. [Figure 3] FIG. 2 is a plan view showing the shape of the flat wire drawing die of the present embodiment. [Figure 4] FIG. 2 is a partially enlarged plan view showing the shape of a corner in the rectangular wire drawing die of the present embodiment when the angle φ is 30°. [Figure 5] FIG. 2 is a partially enlarged plan view showing the shape of a corner in the rectangular wire drawing die of the present embodiment when the angle φ is 60°. [Figure 6] FIG. 2 is a partially enlarged plan view showing the shape of a corner when the angle φ is 90° in the rectangular wire drawing die of the present embodiment. [Figure 7] FIG. 2 is a partially enlarged plan view showing the shape of a corner in the rectangular wire drawing die of the present embodiment when the angle φ is 120°. [Figure 8] FIG. 2 is a partially enlarged plan view showing the shape of a corner in the rectangular wire drawing die of the present embodiment when the angle φ is 150°. [Figure 9] FIG. 10 is a partially enlarged plan view showing the shape of a corner of a flat wire drawing die of a comparative example. [Figure 10] 1 is a graph showing the relationship between the angle φ and the surface pressure at the corners in the flat wire drawing die of the present embodiment. FIG. [Figure 11] FIG. 2 is a partially enlarged plan view showing parameters at a corner of the flat wire drawing die of the present embodiment. [Figure 12] 2 is a schematic diagram showing a formula for calculating the relationship between the radius (R1) of an inlet corner and the radius (R2) of an outlet corner in the rectangular wire drawing die of the present embodiment. FIG. [Figure 13] 1 is a schematic diagram showing an example of drawing processing of a workpiece in a flat wire manufacturing method using the flat wire drawing die of this embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an example of an embodiment of the flat wire drawing die and the flat wire manufacturing method using the flat wire drawing die of the present invention will be described. In the following description, the same reference numerals will be used in principle for the same or substantially the same configurations, elements, etc.

[0013] <Configuration of flat wire drawing dies> Fig. 1 is a diagram showing a schematic structure of a flat wire drawing die according to the present embodiment. That is, the flat wire drawing die 10 shown in Fig. 1 is drawn in a schematic manner to clearly show its shape.

[0014] The rectangular wire drawing die 10 has a through hole 11 through which a workpiece 12 (see FIG. 13 described later) is inserted and drawn out. That is, the rectangular wire drawing die 10 is a jig used when drawing the workpiece 12 through the hole 11 along a drawing direction D1 to perform a drawing process.

[0015] The rectangular wire drawing die 10 is made of, for example, cemented carbide, diamond, etc. The workpiece 12 to be drawn by the rectangular wire drawing die 10 is, for example, a rod-shaped copper material.

[0016] The rectangular wire drawing die 10 has an entrance side surface (first surface) 10c through which a rod-shaped workpiece 12 is introduced, an exit side surface (second surface) 10d through which the workpiece 12 is drawn out, and a hole 11 that connects the surfaces 10c and 10d. In other words, in the rectangular wire drawing die 10, the surface 10d on the exit side for the workpiece 12 is located on the opposite side from the entrance side surface 10c.

[0017] The hole 11 through which the workpiece 12 is drawn is a through-hole that opens to both the surface 10c and the surface 10d. Specifically, the hole 11 penetrates the rectangular wire drawing die 10 from the surface 10c side to the surface 10d side. The hole 11 has an entrance-side opening 11a that opens to the surface 10c of the rectangular wire drawing die 10, and an exit-side opening 11b that opens to the surface 10d and has a smaller area than the entrance-side opening 11a.

[0018] Since the hole 11 is a through hole for forming a rectangular wire from the workpiece 12 by drawing, the inlet-side opening 11a and the outlet-side opening 11b are each formed in a rectangular shape. Furthermore, the hole 11 is formed in a rectangular shape at every position from the inlet-side opening 11a to the outlet-side opening 11b. In other words, the hole 11 is a through hole formed in a pyramidal shape from the inlet-side opening 11a to the outlet-side opening 11b.

[0019] Next, Fig. 2 is a cross-sectional view showing a specific shape of the flat wire drawing die of this embodiment, and Fig. 3 is a plan view thereof. The specific shape of the flat wire drawing die 10 will be described with reference to Figs. 2 and 3.

[0020] The flat wire drawing die 10 of this embodiment has, as an example, a reduction portion 10a and a bearing portion 10b. The reduction portion 10a has an inlet surface 10c through which the workpiece 12 is introduced. The reduction portion 10a has a hole 11, which is a pyramidal through-hole.

[0021] On the other hand, the bearing portion 10b has an outlet surface 10d through which the workpiece 12 is pulled out along the pulling direction D1. The bearing portion 10b is formed with a hole 13 that communicates with the hole 11. The hole 13 is also a through-hole.

[0022] 2, an entrance opening 11a of the hole 11 is formed on the surface 10c through which the workpiece 12 is introduced, and a bearing opening 13a of the hole 13 is formed on the surface 10d through which the workpiece 12 is drawn. In other words, the flat wire drawing die 10 shown in FIG. 2 has a through hole that connects the entrance opening 11a, which opens on the surface 10c, to the bearing opening 13a, which opens on the surface 10d, and is made up of the hole 11 and the hole 13.

[0023] The opening at the exit of reduction section 10a, which corresponds to the end of hole 11, is outlet-side opening 11b. Therefore, in flat wire drawing die 10 shown in Fig. 2, outlet-side opening 11b at the end of hole 11 and bearing section opening 13a at the end (exit) of hole 13 are openings formed in the same shape. In other words, hole 13 is a through hole formed so that the hole shape is the same from outlet-side opening 11b to bearing section opening 13a.

[0024] 3, the entrance opening 11a that opens to the surface 10c is shaped like a rectangle having four corners 11c, and each of the four corners 11c of the entrance opening 11a is formed into an arc shape with rounded corners.

[0025] 2, the shape of the outlet-side opening 11b, which corresponds to the end point of the reduction section 10a, is also a substantially rectangular shape having four corners 11d, similar to the inlet-side opening 11a. Each of the four corners 11d of the outlet-side opening 11b is also formed into an arc shape with rounded corners.

[0026] 2 has a die angle of 2θ, and a die half angle of θ. In other words, the die angle of the rectangular wire drawing die 10 of this embodiment is the angle (2θ) from the die inner wall 11e to the opposite die inner wall 11f.

[0027] <Conditions for the corner radius of the entrance opening> In the flat wire drawing die 10 of this embodiment, the radius of the corner 11c of the entrance opening 11a of the hole 11 of the reduction section 10a is different from the radius of the corner 11d of the exit opening 11b of the hole 11 of the reduction section 10a.

[0028] The radius of the corner 11c of the inlet side opening 11a of the hole 11 of the reduction portion 10a verified in this embodiment will be described.

[0029] Each of Figures 4 to 8 shows the shape of the corner of the reduction section when the radius of the corner 11d of the outlet side opening 11b of the reduction section 10a of the flat wire drawing die 10 is fixed to a predetermined size and the radius of the corner 11c of the entrance side opening 11a of the reduction section 10a is varied.

[0030] Note that Figure 9 shows the shape of the corner of the reduction section 10a as a comparative example structure, in which the radius of the corner 11c of the inlet side opening 11a of the reduction section 10a and the radius of the corner 11d of the outlet side opening 11b are the same size.

[0031] 4 to 8, the radius of corner 11c of entrance opening 11a of hole 11 in reduction section 10a of flat wire drawing die 10 (reduction section entrance side corner radius) is defined as R1, and the radius of corner 11d of exit opening 11b of hole 11 in reduction section 10a (reduction section exit side corner radius) is defined as R2. Furthermore, the vertex of arc-shaped corner 11c of entrance opening 11a of hole 11 in reduction section 10a is defined as P1, and the vertex of arc-shaped corner 11d of exit opening 11b of hole 11 in reduction section 10a is defined as P2. Two lines connecting vertex P1 and vertex P2 are defined as S1 and S2, the intersection of line S1 and line S2 is defined as K1, and the angle formed by line S1 and line S2 at intersection K1 is defined as φ.

[0032] With the above parameter settings, Fig. 4 shows the shape of the reduction section corner when the angle φ = 30°, Fig. 5 shows the shape of the reduction section corner when the angle φ = 60°, and Fig. 6 shows the shape of the reduction section corner when the angle φ = 90°. Furthermore, Fig. 7 shows the shape of the reduction section corner when the angle φ = 120°, and Fig. 8 shows the shape of the reduction section corner when the angle φ = 150°. Note that Fig. 9 shows the shape of the reduction section corner when the angle φ = 0°. In Fig. 9, the line S1 and the line S2 do not intersect (are parallel), so the angle φ = 0°.

[0033] Using the magnitude of each angle φ in Figures 4 to 9 as a parameter, a simulation was performed using a predetermined analysis software (Ansys Mechanical 2023 R2 by Ansys Corporation) to determine the magnitude of the surface pressure at the corners of the workpiece 12 relative to the magnitude of the angle φ. In this simulation, the die angle (total angle: 2θ) was set to 18°, the radius (R2) of the corner 11d on the die exit side was fixed to 0.54 mm, and the radius (R1) of the corner 11c on the die entrance side was set to 0.54 mm to 1.79 mm, and the magnitude of the surface pressure at the radius R1 of each corner 11c was determined by simulation. The correspondence between the angle φ and the radius R1 of the corner 11c is as follows:

[0034] For an angle of φ=30°, R1 is approximately 0.87 mm, for an angle of φ=60°, R1 is approximately 1.12 mm, for an angle of φ=90°, R1 is approximately 1.33 mm, for an angle of φ=120°, R1 is approximately 1.54 mm, for an angle of φ=150°, R1 is approximately 1.79 mm, and for an angle of φ=0°, R1 is approximately 0.54 mm (R1=R2).

[0035] The results of a simulation performed under the above conditions are shown in Figure 10. As shown in Figure 10, by making the radius R1 of the corner 11c on the die inlet side larger than the radius R2 of the corner 11d on the die outlet side (R1 > R2), the surface pressure on the corner of the workpiece 12 can be reduced.

[0036] Specifically, the magnitude of the corner surface pressure when the angle φ = 0° is nearly 900 MPa, whereas in all cases where the angle φ is 30° or greater, the magnitude of the corner surface pressure is much smaller than when the angle φ = 0°.

[0037] In other words, in the flat wire drawing die 10, the radius R1 of the corner 11c of the inlet opening 11a is made larger than the radius R2 of the corner 11d of the outlet opening 11b, thereby reducing the surface pressure on the corner of the workpiece 12.

[0038] Next, we determine the preferred range of radius R1 of the corner 11c on the die inlet side. First, angle φ = 0°, as shown in part M1 of Figure 10, is the condition under which the surface pressure is greatest, and corresponds to the corner shape shown in Figure 9. In the corner shape of Figure 9, R1 is approximately 0.54 mm (R1 = R2). In other words, this is the case when radius R1 of corner 11c of inlet-side opening 11a and radius R2 of corner 11d of outlet-side opening 11b are the same size.

[0039] On the other hand, angle φ=90° is the condition for the smallest surface pressure, as shown in part N1 of Fig. 10, and corresponds to the corner shape shown in Fig. 6. Here, R1 is approximately 1.33 mm, and the center of arc-shaped corner 11c of inlet-side opening 11a and the center of arc-shaped corner 11d of outlet-side opening 11b are coaxial.

[0040] Furthermore, by comparing the workpiece 12 produced using the flat wire drawing die 10 of the shape shown in Figure 9 where R1 = R2 with the workpiece 12 produced using the flat wire drawing die 10 of the shape shown in Figure 6 where the center of corner 11c and the center of corner 11d are the same center, it was confirmed that reducing the surface pressure has the effect of suppressing the occurrence of conductor scratches.

[0041] Therefore, it is believed that the median pressure between the pressure at the M1 portion and the pressure at the N1 portion in Fig. 10 can reduce the degree of scratches formed on the workpiece 12. From Fig. 10, it can be seen that the median pressure between the pressure at the M1 portion and the pressure at the N1 portion in Fig. 10 is approximately 700 MPa. Therefore, it can be said that it is preferable to set the pressure at 700 MPa as the boundary value, and to set the angle φ within a range that results in a pressure of 700 MPa or less. In Fig. 10, it is preferable to set the angle φ so that it falls within the region A1.

[0042] 10, the angle φ is preferably in the range of 45° to 150°. Furthermore, since the surface pressure is smallest when the angle φ is 90° (part N1), it is optimal to set the angle φ to 90°.

[0043] Next, using the schematic diagram shown in Figure 11, the radius R1 of the corner 11c of the inlet-side opening 11a is expressed by a formula using the radius R2 of the corner 11d of the outlet-side opening 11b. Here, for the corner shape in Figure 11, the relationship between the angle φ and the angle λ is set to φ + 2λ = 90°. Also, the length of the hole 11 in the reduction section 10a in the drawing direction D1 is set to L (see Figure 2), and the die half angle is set to θ.

[0044] As shown in the calculation formula F1 in FIG. 12, φ+2λ=90°, so φ=90°-2λ, and λ=(90°-φ) / 2.

[0045] It can also be expressed as λ=arctan((Ltanθ+R2-R1) / Ltanθ), so λ=arctan(1+(R2-R1) / Ltanθ).

[0046] Therefore, (90°-φ) / 2=arctan(1+(R2-R1) / Ltanθ)···(Equation A).

[0047] The above (Equation A) can be converted to tan((90°-φ) / 2)=1+(R2-R1) / Ltanθ, which further becomes (R2-R1) / Ltanθ=tan((90°-φ) / 2)-1··· (Equation B).

[0048] The above formula (B) can be converted to R2-R1=Ltanθ×(tan((90°-φ) / 2)-1), and further to R1=R2-Ltanθ×[tan((90°-φ) / 2)-1].

[0049] Therefore, it can be expressed as R1=R2+Ltanθ×[1-tan((90°-φ) / 2)]···(Equation C).

[0050] Then, when the angle φ=45°, which is the lower limit of the preferable range of the angle φ, is substituted into (Equation C), (Equation C) becomes R1=R2+0.586×Ltanθ.

[0051] On the other hand, when the upper limit of the preferable range of the angle φ, ie, angle φ=150°, is substituted into (Equation C), (Equation C) becomes R1=R2+1.577×Ltanθ.

[0052] Therefore, the preferable range of the radius R1 of the corner 11c of the inlet side opening 11a is as follows: R2+0.586Ltanθ≦R1≦R2+1.577Ltanθ.

[0053] Furthermore, when the optimum angle φ=90°, (Equation C) becomes R1=R2+Ltanθ.

[0054] <Flat wire manufacturing method> As shown in FIG. 13, the flat wire manufacturing method of this embodiment involves drawing a workpiece 12 through a hole 11 in a flat wire drawing die 10 to stretch it, thereby subjecting the workpiece 12 to a drawing process.

[0055] The hole 11 of the rectangular wire drawing die 10 has a rectangular entrance opening 11a that opens on the entrance surface 10c, where the workpiece 12 is introduced, and a rectangular exit opening 11b that opens on the exit surface 10d, where the workpiece 12 is extracted, and has a smaller area than the entrance opening 11a. In other words, the hole 11 is a through hole that communicates with the surface 10c and the surface 10d.

[0056] Then, the workpiece 12 is introduced through the entrance side opening 11a, which has a corner 11c with a radius larger than the radius of the corner 11d of the exit side opening 11b, and the workpiece 12 is pulled out and stretched from the exit side opening 11b along the pulling direction D1.

[0057] The preferred range of the radius R1 of the corner 11c of the inlet side opening 11a is as follows: R2+0.586Ltanθ≦R1≦R2+1.577Ltanθ. Therefore, the workpiece 12 is pulled out and stretched from the hole 11 that satisfies the relationship R2+0.586Ltanθ≦R1≦R2+1.577Ltanθ.

[0058] Furthermore, when the optimum angle φ is 90°, the radius R1 of the corner 11c of the inlet opening 11a is R1=R2+Ltanθ.

[0059] <Effects of this embodiment> According to the flat wire drawing die 10 and flat wire manufacturing method of this embodiment, the radius (R1) of the corner 11c of the inlet opening 11a of the flat wire drawing die 10 is made larger than the radius (R2) of the corner 11d of the outlet opening 11b, thereby mitigating the concentration of surface pressure on the corners of the workpiece 12. In other words, the contact surface pressure at the corners of the workpiece 12 can be reduced.

[0060] This makes it possible to prevent scratches from being caused to the workpiece 12 during the drawing process.

[0061] In addition, by setting the radius R1 of the corner 11c of the entrance opening 11a of the flat wire drawing die 10 to the range R2+0.586Ltanθ≦R1≦R2+1.577Ltanθ, the contact surface pressure at the corner of the workpiece 12 can be further reduced.

[0062] Furthermore, by setting the radius R1 of the corner 11c of the entrance opening 11a of the rectangular wire drawing die 10 to R1 = R2 + Ltanθ (angle φ = 90°), the magnitude of the contact surface pressure at the corner of the workpiece 12 can be minimized.

[0063] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present invention. For example, in the above-described embodiment, the flat wire drawing die 10 is described as comprising the reduction portion 10a and the bearing portion 10b, but the flat wire drawing die 10 may have a structure in which a relief portion with a clearance angle is provided on the outlet side of the bearing portion 10b. [Explanation of symbols]

[0064] 10. Flat wire drawing die 10a Reduction section 10b Bearing part 10c side (first side) 10d face (2nd face) 11 holes 11a Inlet side opening 11b Outlet side opening 11c,11d corner 11e, 11f Die inner wall 12 Work material 13 holes 13a Bearing opening A1 area D1 Pulling direction F1 calculation formula K1 intersection L Reduction length P1 Apex of the arc-shaped corner on the entrance side P2 Apex of arc-shaped corner on the outlet side R1 Radius of corner at inlet of reduction section R2 Radius of corner at outlet of reduction section S1: The line connecting vertex P1 and vertex P2 S2: The line connecting vertex P1 and vertex P2 θ Die half angle φ is the angle between lines S1 and S2

Claims

1. A rectangular wire drawing die used to draw and stretch a workpiece, a first surface on an inlet side through which the workpiece is introduced; a second surface on an outlet side for extracting the workpiece; a hole communicating with the first surface and the second surface; Equipped with the hole has a rectangular inlet side opening that opens to the first surface and a rectangular outlet side opening that opens to the second surface and has an area smaller than that of the inlet side opening, A flat wire drawing die, wherein the radius of a corner of the inlet opening is larger than the radius of a corner of the outlet opening.

2. The flat wire drawing die according to claim 1, The radius of the corner of the inlet side opening is R1, The radius of the corner of the outlet side opening is R2, The length of the hole in the direction of drawing the workpiece is defined as L, When the half angle of the die angle is θ, A rectangular wire drawing die that satisfies the relationship: R2 + 0.586L tan θ ≦ R1 ≦ R2 + 1.577L tan θ.

3. The flat wire drawing die according to claim 2, A rectangular wire drawing die in which R1=R2+Ltanθ.

4. A method for manufacturing a rectangular wire, in which a workpiece is subjected to a drawing process by drawing and stretching the workpiece through a hole in a rectangular wire drawing die, the hole has a rectangular inlet-side opening that opens to a first surface on the inlet side of the workpiece, and a rectangular outlet-side opening that opens to a second surface on the outlet side of the workpiece and has an area smaller than that of the inlet-side opening, The method for manufacturing a rectangular wire includes introducing the workpiece into the entrance opening, which has a corner with a radius larger than the radius of the corner of the exit opening, and drawing out and stretching the workpiece from the exit opening.

5. The method for manufacturing a rectangular wire according to claim 4, The radius of the corner of the inlet side opening is R1, The radius of the corner of the outlet side opening is R2, The length of the hole in the direction of drawing the workpiece is defined as L, When the half angle of the die angle is θ, The method for manufacturing a rectangular wire includes pulling out and stretching the workpiece through the hole that satisfies the relationship: R2+0.586L tan θ≦R1≦R2+1.577L tan θ.

6. The method for manufacturing a rectangular wire according to claim 5, A method for manufacturing a rectangular wire, wherein R1=R2+Ltanθ.

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