Method for recovering copper from enamel wire

Abstract

To provide a method for recovering copper from an enamel wire, the method being capable of reducing an environmental load and recovering high-purity copper at low processing cost.SOLUTION: A method for recovering copper from an enamel wire removes an insulator 22 from an enamel wire 2 having the insulator 22 around a conductor 21 made of copper or a copper alloy to recover the copper or the copper alloy that constitutes the conductor 21, and includes a stripping step of subjecting the enamel wire 2 to diameter reduction processing and stripping the insulator 22 from the conductor 21, and a removal step of peeling and removing the insulator 22 that has been stripped from the conductor 21.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for recovering copper from an enameled wire. [Background technology]

[0002] Enamelled wires are known in which an insulator is formed by applying enamel paint around the conductor and drying it. It is known that when discarding enamelled wires, it is difficult to remove the insulation from the conductor and recover the copper because the conductor and the insulator adhere closely to each other.

[0003] Patent Document 1 discloses a method for removing the insulation of an enameled wire by heating and carbonizing the insulation and then applying a mechanical external force to the insulation. Patent Document 2 discloses a method for removing the insulation by immersing the enameled wire in an alkaline solution to hydrolyze the insulation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-174175 A [Patent Document 2] Japanese Patent Application Publication No. 10-25523 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method described in Patent Document 1 requires heating to high temperatures of 500°C or higher to carbonize the insulator, which requires a huge amount of thermal energy, resulting in high processing costs. In addition, the conductor may be oxidized during heating, or the carbide may be integrated with the conductor, resulting in a decrease in the purity of the recovered copper.

[0006] The method described in Patent Document 2 requires a high-concentration alkaline solution, which increases the cost of the chemicals and the waste liquid treatment, and therefore has problems of high environmental impact and high treatment costs. In addition, heating is required to hydrolyze the insulator, which further increases the treatment costs.

[0007] Therefore, an object of the present invention is to provide a method for recovering copper from enameled wire, which can reduce the environmental load and recover high-purity copper at low processing costs. [Means for solving the problem]

[0008] SUMMARY OF THE PRESENT DISCLOSURE OF THE PRESENT DISCLOSURE The present invention provides a method for recovering copper or copper alloy constituting an enameled wire by removing an insulator from an enameled wire having a conductor made of copper or a copper alloy around the conductor, the method comprising: a stripping step of subjecting the enameled wire to a diameter reduction process and stripping the insulator from the conductor; and a removal step of peeling and removing the insulator that has been stripped from the conductor. Effect of the Invention

[0009] According to the present invention, it is possible to provide a method for recovering copper from an enameled wire, which can reduce the environmental load and recover high-purity copper at low processing costs. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of an enameled wire copper recovery apparatus used in an enameled wire copper recovery method according to one embodiment of the present invention. FIG. [Diagram 2] 1(a) and 1(b) are diagrams illustrating the swaging process. [Diagram 3] 1 is a photograph showing an example of an enameled wire after swaging. [Figure 4] FIG. 2 is a diagram illustrating a die drawing process. [Diagram 5] Photographs showing an example of an enameled wire after die drawing are shown in (a) and (b). [Figure 6]FIG. 1 is a diagram illustrating processing by a tipping machine. [Figure 7] FIG. 2 is a perspective view showing an example of a removal device. [Figure 8] FIG. 13 is a diagram showing the results of a study on the processing conditions for swaging and processing using a tipping machine. [Figure 9] 13(a) and 13(b) are diagrams showing the results of examining the processing conditions for die drawing. [Figure 10] 1 is a flow diagram of a copper recovery method for an enameled wire according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [Embodiment Mode] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0012] Fig. 1 is a schematic diagram of an enameled wire copper recovery apparatus 1 (hereinafter simply referred to as copper recovery apparatus 1) used in the enameled wire copper recovery method according to the present embodiment. As shown in Fig. 1, the copper recovery apparatus 1 is an apparatus that removes insulator 22 from conductor 21 of enameled wire 2 to recover copper or copper alloy that constitutes conductor 21, and includes a stripping device 3 and a removal device 4.

[0013] The enameled wire 2 is an electric wire used in, for example, motors, transformers, induction heating coils, etc. for vehicles. The enameled wire 2 may be a round wire having a circular cross section, or a rectangular wire having a rectangular cross section. The enameled wire 2 is not limited to a round wire or a rectangular wire, and may have, for example, an elliptical or triangular cross section, and is not particularly limited in its cross section. The enameled wire 2 has a conductor 21 made of copper or a copper alloy, and an insulator 22 formed by applying and baking an enamel paint around the conductor 21. The insulator 22 is made of, for example, polyimide, polyamideimide, polyester, polyurethane, polyesterimide, etc.

[0014] It is known that in an enameled wire 2, the insulator 22 has a strong adhesive force to the conductor 21. Therefore, when discarding an enameled wire 2, it is not easy to remove the insulator 22 from the conductor 21 and recover the conductor 21 (i.e., recover the copper or copper alloy that constitutes the conductor 21). With the copper recovery device 1 according to this embodiment, even in an enameled wire 2 in which the conductor 21 and the insulator 22 have a strong adhesive force, the insulator 22 can be easily removed, making it possible to easily recover the copper or copper alloy that constitutes the conductor 21. This will be described in detail below.

[0015] (Peeling device 3) The stripping device 3 is a device that performs a stripping step of thinning the enameled wire 2 and stripping the insulator 22 from the conductor 21. Here, the thinning process refers to a process of reducing the cross-sectional area of ​​the enameled wire 2 in a cross section perpendicular to the longitudinal direction (in the case of a round wire, a process of reducing the outer diameter). More specifically, by performing the thinning process on the enameled wire 2 in the stripping device 3, a shear stress is generated at the interface between the conductor 21 and the insulator 22 due to the difference in the elongation between the conductor 21 and the insulator 22, causing partial peeling between the conductor 21 and the insulator 22. The thinning process may be swaging, die drawing, or processing using a tipping machine.

[0016] 2(a) and (b) are diagrams for explaining the swaging process (rotary swaging process). FIG. 2(b) shows a cross section taken along line AA in FIG. 2(a). When performing diameter reduction processing by swaging, a swaging machine (swager) 31 for performing the swaging process is used as the peeling device 3. The swaging process is one of the cold forging methods, and is a processing method that is generally used to reduce the diameter (diameter reduction) of a workpiece such as a tube or a rod-shaped body to a desired outer diameter.

[0017] The swaging machine 31 has a die 311 with an insertion hole 311a through which the enameled wire 2 is inserted. The insertion hole 311a is tapered so that the inner diameter gradually decreases from the inlet to the outlet of the enameled wire 2, and the enameled wire 2 is pressed into the insertion hole 311a to reduce the diameter. Furthermore, in the swaging process, the die 311 rotates (rotates around the central axis of the enameled wire 2) while striking the enameled wire 2, to reduce the diameter of the enameled wire 2. In the swaging process, the striking action is included, and therefore the insulator 22 is particularly likely to peel off from the conductor 21, and the insulator 22 is likely to peel off from the conductor 21 even when the degree of the processing (the reduction in area rate and the rate of change in Vickers hardness, which will be described later) is relatively small. In the illustrated example, the die 311 is divided into two parts, but the number of parts divided into the die 311 is not limited to this, and can be set appropriately to, for example, three, four, six, or the like.

[0018] Fig. 3 is a photograph showing an example of the enameled wire 2 after the swaging process. As shown in Fig. 3, it was confirmed that the insulator 22 was peeled off from the conductor 21 by performing the swaging process. The suitable processing conditions for the swaging process will be described later.

[0019] 4 is a diagram illustrating the die wire drawing process. In this case, a die wire drawing machine 32 for performing the die wire drawing process is used as the peeling device 3. The die wire drawing machine 32 has a die 321 in which a tapered insertion hole 321a is formed so that the inner diameter of the enamel wire 2 gradually decreases from the inlet to the outlet, and the enamel wire 2 is passed through the insertion hole 321a and drawn out, thereby performing the diameter reduction process. During the diameter reduction process, partial peeling occurs between the conductor 21 and the insulator 22 due to the difference in the elongation between the conductor 21 and the insulator 22.

[0020] Fig. 5 is a photograph showing an example of an enameled wire 2 after die drawing. By making a slit with a blade along the longitudinal direction of the enameled wire 2 after die drawing as shown in Fig. 5(a), it becomes possible to easily strip the insulator 22 from the conductor 21 as shown in Fig. 5(b). In the die drawing process, unlike the above-mentioned swaging process, the enameled wire 2 is not struck, so it is desirable to perform a relatively large degree of processing in order to make it easier to strip the insulator 22 from the conductor 21 in the subsequent removal process. The suitable processing conditions for die drawing will be described later.

[0021] FIG. 6 is a diagram for explaining processing by the pointing machine 33. In the pointing machine 33, the enameled wire 2 is thinned by passing it between a pair of rollers 331. In the pointing machine 33, the rollers 331 are rotated so that the outer circumferential surface of the rollers 331 moves in the opposite direction to the running direction (drawing direction) of the enameled wire 2 at the position where the rollers 331 contact the enameled wire 2. The pointing machine 33 is usually used to partially thin the tip of a linear or rod-shaped body, but when used as a peeling device 3, it is used to continuously thin the enameled wire 2 by passing the enameled wire 2 between the pair of rollers 331 and drawing it out. In processing by the pointing machine 33, the outer circumferential surface of the rollers 331 strongly rubs against the surface of the enameled wire 2, so that the insulator 22 can be easily peeled off from the conductor 21 even if the degree of processing is relatively small, as in the above-mentioned swaging process. The preferable processing conditions for processing by the pointing machine 33 will be described later.

[0022] (Removal device 4) The remover 4 is a device that performs a removal step of peeling and removing the insulator 22 peeled off from the conductor 21 by the peeling device 3. Fig. 7 is a diagram showing an example of the remover 4. As shown in Fig. 7, the remover 4 continuously makes slits 22a with a blade 41 along the longitudinal direction of the insulator 22 after the peeling step, and continuously peels off the insulator 22 divided by the slits 22a, thereby removing the insulator 22 from the conductor 21.

[0023] In this embodiment, a pair of blades 41 are disposed at positions facing each other above and below the center of the enameled wire 2, and each blade 41 forms a slit 22a along the longitudinal direction of the enameled wire 2, continuously dividing the insulator 22 into two, left and right. The divided insulator 22 is then opened to the left and right, and each insulator 22 is guided to a winding roller 43 via a guide roller 42. By winding the insulator 22 around the winding roller 43 while running the enameled wire 2, the insulator 22 is pulled to the left and right, and is continuously stripped from the conductor 21. Note that the up-down and left-right directions mentioned here are relative directions and are not limited to the vertical and horizontal directions.

[0024] The winding tension of the insulator 22 by the winding roller 43 is preferably 5% to 90% of the breaking strength of the insulator 22. The breaking strength of the insulator 22 is a value measured by cutting the insulator 22 into a strip of 1 mm width from the enameled wire 2 and then performing a tensile test using an autograph with a gauge length of 30 mm and a pulling speed of 10 mm / min. This allows the insulator 22 to be stably peeled off without bending or breaking. In addition, the angle θ between the direction in which the insulator 22 is pulled when peeling it from the conductor 21 and the running direction of the enameled wire 2 is preferably 30 degrees to 160 degrees, more preferably 90 degrees to 160 degrees. This makes it easier to peel the insulator 22 from the conductor 21 and also prevents the insulator 22 from breaking during winding. It should be noted that the removal device 4 in FIG. 7 is merely an example, and the specific structure of the removal device 4 can be appropriately changed.

[0025] (About the suitable processing conditions for the peeling process) First, we will consider the case where swaging and processing by the tipping machine 33 are performed as the diameter reduction processing in the peeling step. Swaging and processing by the tipping machine 33 were performed while changing the processing conditions, and it was confirmed whether the insulator 22 could be easily peeled off from the processed enameled wire 2. The results are shown in Figure 8. In Figure 8, the areas from which the insulator 22 could be easily peeled off are shown by hatching.

[0026] 8, when performing swaging and processing with the tipping machine 33, it is desirable to perform processing so that the area reduction rate is 9.2% or more. The area reduction rate can be calculated by the following formula, where A is the cross-sectional area of ​​the enameled wire 2 before processing and B is the cross-sectional area of ​​the enameled wire 2 after processing. Area reduction rate (%)={(AB) / A}×100

[0027] From Fig. 8, it can be seen that when performing swaging and processing using the tipping machine 33, it is desirable to perform processing so that the rate of change in Vickers hardness is 55% or more. The rate of change in Vickers hardness can be obtained by the following formula, where the Vickers hardness before processing is C and the Vickers hardness after processing is D. The Vickers hardness was measured using the method described in JIS Z2244 (2009). The measurement conditions were a load of 200g and a holding time of 15 seconds. The cross section of the sample was mirror-polished, and the average value of the values ​​measured at two points near the center of the conductor 21 was used. Vickers hardness change rate (%) = {(DC) / C} x 100

[0028] Next, we will consider the case where die drawing is performed as a diameter reduction process in the peeling step. Die drawing was performed while changing the processing conditions, and it was confirmed whether the insulator 22 could be easily peeled off from the processed enameled wire 2. The results are shown in Figures 9(a) and (b). In Figures 9(a) and (b), the areas where the insulator 22 could be easily peeled off are shown by hatching, as in Figure 8.

[0029] As shown in Fig. 9(a), when performing die drawing, it is desirable to perform the process so that the area reduction rate is 36% or more. Also, when performing die drawing, it is desirable to perform the process so that the elongation strain is 69% or more. The elongation strain can be obtained by the following formula, where E is the length of the conductor 21 before processing and F is the length of the conductor 21 after processing. Elongation strain (%) = {(FE) / E} x 100 Furthermore, as shown in FIG. 9(b), when performing die drawing, it is desirable to perform the processing so that the rate of change in Vickers hardness is 88% or more.

[0030] (Method of recovering copper from enameled wire) Fig. 10 is a flow diagram of the copper recovery method for enameled wire according to the present embodiment. As shown in Fig. 10, in the copper recovery method for enameled wire according to the present embodiment, the stripping step in step S1 and the removal step in step S2 are continuously repeated to recover copper or copper alloy constituting the conductor 21 of the enameled wire 2.

[0031] In the peeling process of step S1, the enameled wire 2 is subjected to a diameter-reducing process using a peeling device 3, and the insulator 22 is peeled off from the conductor 21. In this case, the diameter-reducing process can be performed by swaging, die drawing, or processing using a tipping machine 33. It is possible to apply a tensile stress to the enameled wire 2 as in a tensile test, but this is not preferable because the enameled wire 2 breaks before peeling occurs. When using swaging or processing using a tipping machine 33, it is preferable to perform processing so that the reduction in area is 9.2% or more and the change in Vickers hardness is 55% or more. When using die drawing, it is preferable to perform processing so that the reduction in area is 36% or more, the elongation strain is 69% or more, and the change in Vickers hardness is 88% or more. In the peeling process, it is not necessary for the entire insulator 22 to be peeled off from the conductor 21, and it is preferable that peeling occurs in a part of the insulator 22 so as to become the starting point of peeling.

[0032] In the removal process of step S2, the insulator 22 peeled off from the conductor 21 is peeled off and removed using a removal device 4. Here, as shown in FIG. 7, the insulator 22 after the peeling process is continuously cut with a blade 41 along the longitudinal direction, and the insulator 22 divided by the cuts 22a is continuously peeled off, thereby removing the insulator 22 from the conductor 21. However, the method is not limited to this, and any method may be used to remove the insulator 22 as long as the insulator 22 can be peeled off and removed. The conductor 21 from which the insulator 22 has been removed is wound up, for example, on a winding drum and collected.

[0033] (Functions and Effects of the Embodiments) As described above, the copper recovery method for enameled wire in this embodiment includes a stripping process in which enameled wire 2 is subjected to diameter reduction processing and insulator 22 is stripped from conductor 21, and a removal process in which insulator 22 that has been stripped from conductor 21 is peeled off and removed.

[0034] By performing the diameter-reducing process, the difference between the stretchability of the conductor 21 and the stretchability of the insulator 22 can be utilized to peel off the insulator 22 from the conductor 21, and the insulator 22 can be easily peeled off and removed from the conductor 21. This embodiment has a low environmental impact because it does not use chemicals that require waste liquid treatment, and since no heat treatment is required, the conductor 21 does not oxidize and the carbonized insulator 22 does not become integrated with the conductor 21, and high purity copper can be recovered. Furthermore, this embodiment does not require treatment using chemicals with high processing costs, and can utilize equipment for general diameter-reducing processes, so that equipment costs and processing costs are very low and copper or copper alloys can be recovered at low cost.

[0035] (Modification) In the above embodiment, a case has been described in which the peeling step and the removing step are performed on a single production line. However, the production line may be divided into separate steps, such that the enameled wire 2 is wound up once after the peeling step, and then the removing step is performed on the wound enameled wire 2.

[0036] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiment will be described by using the reference numerals and the like in the embodiment. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiment.

[0037] [1] A method for recovering copper or copper alloy constituting a conductor (21) by removing an insulator (22) from an enameled wire (2) having an insulator (22) around a conductor (21) made of copper or a copper alloy, the method comprising: a stripping step of subjecting the enameled wire (2) to a diameter reduction process and stripping the insulator (22) from the conductor (21); and a removal step of peeling and removing the insulator (22) that has been stripped from the conductor (21).

[0038] [2] The copper recovery method for enameled wire according to [1], wherein in the peeling step, swaging is performed as the diameter reduction process so that the area reduction rate is 9.2% or more.

[0039] [3] The copper recovery method for enameled wire according to [1], wherein in the peeling step, a swaging process is performed as the diameter reduction process so that a rate of change in Vickers hardness is 55% or more.

[0040] [4] The method for recovering copper from an enameled wire according to [1], wherein in the peeling step, the diameter reducing process comprises a die drawing process in which the enameled wire (2) is drawn while passing it through a die (321), and the die drawing process is performed so that the area reduction rate is 36% or more.

[0041] [5] The method for recovering copper from an enameled wire according to [1], wherein in the peeling step, the diameter reducing process comprises a die drawing process in which the enameled wire (2) is drawn while passing it through a die (321), and the die drawing process is performed so that an elongation strain is 69% or more.

[0042] [6] The method for recovering copper from an enameled wire according to [1], wherein in the peeling step, the diameter reducing process comprises a die drawing process in which the enameled wire (2) is drawn while passing it through a die (321), and the die drawing process is performed so that the rate of change in Vickers hardness is 88% or more.

[0043] [7] The method for recovering copper from an enameled wire according to [1], wherein in the peeling step, the enameled wire (2) is drawn through a nozzle (33) as the diameter reducing process, so that the area reduction rate is 9.2% or more.

[0044] [8] The method for recovering copper from an enameled wire according to [1], wherein in the peeling step, the enameled wire (2) is drawn through a nozzle (33) as the diameter reducing process, and the process is performed so that the rate of change in Vickers hardness is 55% or more.

[0045] [9] The copper recovery method for enameled wire according to [1], wherein in the removing step, slits (22a) are continuously made in the insulator (22) after the peeling step along a longitudinal direction with a blade (41), and the insulator (22) divided by the slits (22a) is continuously peeled off, thereby removing the insulator (22).

[0046] (Additional Note) Although the embodiment of the present invention has been described above, the invention according to the claims is not limited to the embodiment described above. It should be noted that not all of the combinations of features described in the embodiment are essential to the means for solving the problems of the invention. The present invention can be modified appropriately without departing from the spirit of the invention. [Explanation of symbols]

[0047] 1…Enamelled wire copper recovery device 2…Enameled wire 21...Conductor 22...Insulator 3…Peeling device 31…Swaging machine 32…Die drawing machine 33…mouth machine 4...Removal device 41…Blade

Claims

1. A method for recovering copper or copper alloy constituting a conductor by removing an insulator from an enameled wire having an insulator around a conductor made of copper or copper alloy, the method comprising the steps of: a stripping step of subjecting the enameled wire to a diameter-reducing process and stripping the insulator from the conductor; A removing step of peeling off and removing the insulator peeled off from the conductor. Method for recovering copper from enamelled wire.

2. In the peeling step, a swaging process is performed as the diameter reduction process so that the area reduction rate is 9.2% or more. The method for recovering copper from an enameled wire according to claim 1.

3. In the peeling step, a swaging process is performed as the diameter reduction process so that the rate of change in Vickers hardness is 55% or more. The method for recovering copper from an enameled wire according to claim 1.

4. In the peeling step, the diameter reducing process includes a die drawing process in which the enameled wire is drawn while passing through a die, and the die drawing process is performed so that the area reduction rate is 36% or more. The method for recovering copper from an enameled wire according to claim 1.

5. In the peeling step, the diameter reduction process includes a die drawing process in which the enameled wire is drawn while passing through a die, and the die drawing process is performed so that an elongation strain is 69% or more. The method for recovering copper from an enameled wire according to claim 1.

6. In the peeling step, the diameter reducing process includes a die drawing process in which the enameled wire is drawn while passing through a die, and the die drawing process is performed so that the rate of change in Vickers hardness is 88% or more. The method for recovering copper from an enameled wire according to claim 1.

7. In the peeling step, the enameled wire is drawn through a tipping machine as the diameter reducing process, and the reduction in area is 9.2% or more. The method for recovering copper from an enameled wire according to claim 1.

8. In the peeling step, the enameled wire is drawn through a tipping machine as the diameter reducing process, and the process is performed so that the rate of change in Vickers hardness is 55% or more. The method for recovering copper from an enameled wire according to claim 1.

9. In the removing step, the insulator after the peeling step is continuously cut with a blade along a longitudinal direction, and the insulator divided by the cuts is continuously peeled off to remove the insulator. The method for recovering copper from an enameled wire according to claim 1.

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