Method for producing enameled wire

Abstract

To provide an enameled wire made using a DIP material that offers superior flexibility and processability.SOLUTION: A method for producing an enameled wire includes: a step in which a copper wire material is prepared through the conform extrusion of a DIP material manufactured using the dip-forming technique; and a varnish application and baking step in which varnish is applied onto the copper wire material and the applied varnish is subsequently baked.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, upcast material and DIP material are known as representative examples of oxygen-free copper wire. "Upcast material" refers to copper wire produced by the upcast method, in which molten copper is solidified in a mold and continuously pulled upward. "DIP material" refers to copper wire produced by the dip forming method, in which molten copper is continuously solidified around the periphery of a core rod. For example, Patent Document 1 discloses a copper wire with excellent surface properties and fine crystal grains, which is produced by using upcast material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6233634 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors attempted to manufacture an enameled wire using the above-mentioned DIP material. Specifically, the DIP material was drawn and annealed to obtain a copper wire material, and varnish was applied to the copper wire material and baked to manufacture an enameled wire. However, when this method was used, the enameled wire tended to have a slightly high hardness (0.2% proof stress). An object of the present invention is to provide an enameled wire using a DIP material that is flexible and has excellent processability. [Means for solving the problem]

[0005] In order to solve the above problem, according to one aspect of the present invention, A step of preparing a copper wire material obtained by conformally extruding a DIP material produced by a dip forming method; a varnish application and baking process of applying varnish to the copper wire and baking the applied varnish; The present invention provides a method for producing an enameled wire, comprising the steps of: Effect of the Invention

[0006] According to the present invention, it is possible to provide an enameled wire that is flexible and has excellent processability by using a DIP material. [Brief description of the drawings]

[0007] [Figure 1] Fig. 1A is a diagram showing a method for producing an enameled wire according to an embodiment of the present invention, Fig. 1B is a diagram showing a schematic configuration of an apparatus for performing a step of preparing a copper wire, and Fig. 1C is a diagram showing a schematic configuration of an apparatus for performing a varnish application and baking step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A method for producing an enameled wire according to a preferred embodiment of the present invention will be described below, but the present invention is not limited to the embodiment. In this specification, the lower limit and upper limit of a numerical range indicated by "~" are included in the numerical range.

[0009] FIG. 1A shows steps of a method for producing an enameled wire according to an embodiment of the present invention. As shown in FIG. 1A, the method for producing an enameled wire according to the embodiment of the present invention includes a step (S1) of preparing a copper wire material by conform extrusion of a DIP material produced by a dip forming method, and a varnish application and baking step (S2) of applying varnish to the copper wire material and baking the applied varnish. FIG. 1B shows a schematic configuration of an apparatus used in the above-mentioned copper wire preparation step (S1), and FIG. 1C shows a schematic configuration of an apparatus used in the above-mentioned varnish application and baking step (S2). Each step will be described below.

[0010] [Step of preparing copper wire (S1)] In the step (S1) of preparing a copper wire, a copper wire is prepared by conform extrusion of a DIP material produced by a dip forming method. In this step, the copper wire may be prepared by manufacturing, or may be prepared by purchasing a commercially available product. In this embodiment, the copper wire is manufactured. Specifically, the copper wire is manufactured by a copper wire manufacturing system 1 shown in FIG. 1B. As shown in FIG. 1B, the copper wire manufacturing system 1 is a so-called manufacturing line for copper wire, and includes a master winding roller 11, a straightening device 12, a cleaning device 13, a conform extrusion device 14, and a winding roller 15, which are arranged in this order along the conveying direction of the DIP material that will become the copper wire. A copper wire-shaped DIP material to be used for conform extrusion is wound around the original winding roller 11. The DIP material is a so-called base material, and oil is attached to the surface as a residue. The original winding roller 11 is a supply device for supplying the DIP material to each device after the straightening device 12. The straightening device 12 is a device for improving the straightness of the DIP material. The cleaning device 13 has an ultrasonic cleaning function and is adapted to clean the surface of the DIP material. The cleaning device 13 may have a steam cleaning function or a simple water cleaning function instead of the ultrasonic cleaning function. The conform extrusion device 14 is a device for introducing the DIP material into the space defined by the wheel, shoe and abutment, and extruding it through a die to obtain a copper wire. The winding roller 15 is a device for winding up the copper wire. In the copper wire manufacturing system 1, the DIP material is unwound from a master winding roller 11, then straightened to a straightening shape by a straightening device 12, surface-cleaned by a cleaning device 13, and forcibly extruded by a conform extrusion device 14, and the obtained copper wire is wound up by a winding roller 15.

[0011] In addition, alcohol may be applied to the copper wire obtained by conformal extrusion. By applying alcohol to the copper wire, oxidation of the surface of the copper wire is suppressed. The alcohol to be applied is preferably a saturated alcohol having 2 to 4 carbon atoms.

[0012] The copper wire prepared as described above has, for example, the composition, shape, size, electrical conductivity, and mechanical properties shown below. (composition) The DIP material that makes up the copper wire is oxygen-free copper, so the copper wire is also oxygen-free copper. "Oxygen-free copper" is copper containing 99.96% by mass or more of Cu with the remainder being unavoidable impurities, and the total content of unavoidable impurities is preferably 0.03% by mass or less. Since the lower the oxygen content in oxygen-free copper, the better the electrical conductivity, the oxygen content is 0.001% by mass (10 ppm by mass) or less, preferably 0.0005% by mass or less (5 ppm by mass or less). Note that oxygen-free copper preferably contains 99.99% by mass or more of Cu.

[0013] (shape) Copper wire can have a variety of cross-sectional shapes that can be formed by conform extrusion. For example, round wire with a circular cross section is easy to process during extrusion and is likely to produce copper wire with excellent surface properties, shape accuracy, and dimensional accuracy. In addition, copper wire with a rectangular cross section, especially rectangular copper wire with an aspect ratio (ratio of long side to short side, long side / short side) of 10 or less, rectangular copper wire with an aspect ratio close to 1 such as a square, and irregular copper wire with a polygonal or elliptical cross section are also possible.

[0014] (size) The copper wire can be of various sizes. For example, a copper wire with a cross-sectional area of ​​4 to 150 mm 2 In the case where the copper wire is a round wire, for example, the wire diameter (diameter) may be about 3 to 13 mm. In the case where the copper wire is rectangular, for example, the thickness may be about 1 to 8 mm and the width may be about 3 to 35 mm.

[0015] (conductivity) The copper wire is made of oxygen-free copper and has high electrical conductivity, which is 100% IACS or higher, and preferably 101% IACS or higher.

[0016] (mechanical properties) The copper wire obtained by conformal extrusion of the DIP material produced by the dip forming method as described above is flexible and has excellent processing characteristics. In particular, the copper wire used in the manufacturing method of this embodiment has a lower 0.2% yield strength at room temperature than the copper wire obtained by drawing and annealing the DIP material. Specifically, the 0.2% yield strength of the copper wire is about 60 MPa or more and 90 MPa or less. Therefore, if the above-mentioned copper wire is used, there is no need to perform an annealing step to improve the flexibility of the copper wire before the subsequent varnish application and baking steps. In other words, in the method for producing an enameled wire according to the present embodiment, the copper wire does not require (is not required to) be annealed. When annealing is performed, the copper wire needs to be subjected to a certain tension as it passes through the annealing path. Also, adding the annealing process complicates the path line. Therefore, the copper wire becomes somewhat hard when the annealing process is performed, but the method for manufacturing an enameled wire according to the present embodiment can prevent this hardening.

[0017] [Varnish application and baking process (S2)] In the varnish application and baking step (S2), varnish is applied to the copper wire prepared as described above, and the applied varnish is baked. In particular, the varnishing and baking is carried out in a varnishing and baking system 2 shown in FIG. 1C. As shown in FIG. 1C, the varnishing and baking system 2 includes a varnishing device 21, a varnishing baking device 22, a take-up device 23, and a winding device 24. of These are arranged in this order along the conveying direction of the copper wire. The copper wire prepared as described above is first coated with varnish in a varnish coating device 21, and then the coated varnish is baked in a vertical varnish baking device 22. The coated varnish hardens by baking and becomes an insulating layer around the copper wire. Furthermore, an enameled wire is created by providing an insulating layer around the copper wire. The varnish may be any known varnish, including varnishes containing polyesterimide and polyamideimide, varnishes containing polyamideimide, varnishes containing polyimide, varnishes containing esterimide and amideimide, and any general-purpose varnish for producing enameled wires. The varnish baking device may be of horizontal type instead of vertical type. Furthermore, it is preferable that the application and baking of the varnish is appropriately repeated depending on the desired thickness of the insulating layer. For example, the number of times may be about 10 to 50 times, or about 15 to 50 times. In the cross section of the enameled wire, the thickness of the insulating layer is, for example, 60 μm or more, 100 μm or more, 120 μm or more, or 200 μm or more. There is no particular upper limit to the thickness of the insulating layer, but it may be, for example, about 230 μm or less. The application and baking of varnish is performed while applying tension to the copper wire, so the more times it is performed, the thinner and harder the copper wire tends to become. However, in the method for producing an enameled wire according to an embodiment of the present invention, a flexible copper wire is used as described above, so that a relatively flexible enameled wire can be obtained even if the application and baking of varnish is repeated. That is, a flexible enameled wire can be obtained despite the thick insulating layer. Specifically, the 0.2% proof stress of the obtained enameled wire can be, for example, 125 MPa or less, preferably 120 MPa or less, and more preferably 100 to 120 MPa. The take-up device 23 takes up the linear body (copper wire, enameled wire, etc.) and causes the linear body to travel, thereby carrying out each process. The produced enameled wire is taken up by the take-up device 24.

[0018] (effect) According to the method for producing an enameled wire according to the embodiment of the present invention, a copper wire material obtained by conform extrusion of a DIP material formed by a dip forming method is coated with varnish and baked, thereby making it possible to provide an enameled wire that is flexible and has excellent processing characteristics. EXAMPLES

[0019] (Example) The enameled wire of the example was obtained as follows. First, a DIP material of oxygen-free copper with a circular cross section of approximately 11 to 12 mm in diameter was prepared, and using a copper wire manufacturing system 1 as shown in Figure 1B, the DIP material was conformally extruded so that the cross section was rectangular and 2.04 mm x 3.06 mm. Next, using a varnish application and baking system as shown in FIG. 1C, polyimide varnish was applied to the copper wire and baked 46 times to provide an insulating layer around the copper wire, thereby obtaining an enameled wire of the example.

[0020] In order to evaluate the obtained enameled wire of the example, the following items were measured. <Thickness and width of copper wire> In the cross section of the obtained enameled wire, the thickness and width of the copper wire material were measured by measuring with a micrometer in accordance with JIS C 3216-2 JA.1. <Insulation layer thickness> The thickness of the insulating layer in the cross section of the obtained enameled wire was measured using a microscope. <0.2% yield strength> Test pieces were prepared according to JIS Z 2241 and the 0.2% yield strength was measured using a commercially available tensile testing machine. The gauge length was GL = 250 mm. <Adhesion> The adhesive strength of the insulating layer to the copper wire was measured. Specifically, a 180° peel test was performed between the copper wire and the insulating layer, and the adhesive strength (gf / mm) of the insulating layer was measured. <Area reduction rate> Using the copper wire obtained by conform extrusion as a reference, the area reduction rate of the copper wire of the enameled wire was calculated according to the following formula. Area reduction rate [%] = (1-(cross-sectional area of ​​copper wire of enameled wire) / (cross-sectional area of ​​copper wire after conform extrusion = 2.04mm x 3.06mm)) x 100

[0021] The measurement results for each evaluation item are shown in Table 1.

[0022] (Comparative Example) The comparative enameled wire was obtained as follows. First, a DIP material of oxygen-free copper with a circular cross section of about 8 mm in diameter was prepared, and the DIP material was drawn using a wire drawing machine so that the cross section was rectangular and 2.08 mm x 3.12 mm to obtain a copper wire material. Next, the copper wire obtained by drawing was annealed in a steam bright furnace at 500°C for 60 to 90 seconds. Next, using a varnish application and baking system, polyimide varnish was applied to the copper wire and baked 38 times to provide an insulating layer around the copper wire, thereby obtaining an enameled wire of the comparative example. To evaluate the enameled wire of the comparative example, measurements were performed in the same manner as for the enameled wire of the example. The measurement results are shown in Table 1. The area reduction rate of the copper wire material of the enameled wire in the comparative example was calculated based on the following formula. Area reduction rate [%] = (1-(cross-sectional area of ​​copper wire material in enameled wire) / (cross-sectional area of ​​copper wire material after drawing = 2.08mm x 3.12mm)) x 100

[0023] [Table 1]

[0024] As shown in Table 1, the number of times of varnish application and baking was 46 in the Example and 38 in the Comparative Example. Since the varnish application and baking are performed while applying tension to the copper wire, the more times they are applied, the thinner and harder the copper wire tends to become as it is drawn. However, even though the Example had more varnish application and baking than the Comparative Example, the 0.2% proof stress was 120 MPa, which was lower than the 145 MPa of the Comparative Example, and the Example had higher flexibility. Furthermore, the value of 0.2% proof stress divided by the number of times of varnish application and baking was also lower in the Examples than in the Comparative Examples, indicating higher flexibility. This is believed to be because in the Examples, the enameled wire is obtained by applying varnish to the copper wire obtained by conformal extrusion of the DIP material, whereas in the Comparative Examples, the enameled wire is obtained by applying varnish to the copper wire obtained by drawing and annealing the DIP material. That is, in the comparative example, distortion remains in the DIP material even after annealing due to wire drawing and rolling processing, whereas the copper wire material of the embodiment obtained by conformal extrusion of the DIP material is less likely to retain processing distortion and is more flexible than the copper wire material of the comparative example obtained by wire drawing and annealing the DIP material.

[0025] In addition, the adhesive strength of the insulating layer in the Example was 50 gf / mm, while in the Comparative Example it was 20 gf / mm, which was higher than that in the Example. This is thought to be because the reduction in area was smaller in the Example than in the Comparative Example, 3.6% and 7.5%, respectively, and therefore less force was applied between the copper wire and the insulating layer. [Industrial Applicability]

[0026] The method for producing an enameled wire according to an embodiment of the present invention is useful for producing an enameled wire for use in a coil, for example. [Explanation of symbols]

[0027] 1. Copper wire manufacturing system 2 Varnishing and baking system 11 Original Roller 12 Orthodontic device 13 Cleaning equipment 14 Conform Extrusion Equipment 15 Winding roller 21 Varnish application equipment 22 Varnish baking equipment 23 Take-off device 24 Winding device

Claims

1. A step of preparing a copper wire material obtained by conformally extruding a DIP material produced by a dip forming method; a varnish application and baking process of applying varnish to the copper wire and baking the applied varnish; 2. A method for producing an enameled wire, comprising the steps of:

2. 2. A method for producing an enameled wire according to claim 1, comprising the steps of: A method for producing an enameled wire, characterized in that the produced enameled wire has a 0.2% yield strength of 120 MPa or less.

3. 3. A method for producing an enameled wire according to claim 1, further comprising the steps of: The copper wire has a 0.2% yield strength of 60 MPa or more and 90 MPa or less. Manufacturing method of enameled wire.

4. 3. A method for producing an enameled wire according to claim 1, further comprising the steps of: The method for producing an enameled wire, wherein in the varnish applying and baking step, applying the varnish to the copper wire and baking the applied varnish are repeated 10 to 50 times.

5. 3. A method for producing an enameled wire according to claim 1, further comprising the steps of:

2. A method for producing an enameled wire, wherein the thickness of the insulating layer in a cross section of the enameled wire is 60 μm or more.

6. 3. A method for producing an enameled wire according to claim 1, further comprising the steps of:

13. A method for producing an enameled wire, comprising the steps of: applying varnish and baking the copper wire; and,

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