JP5171451B2 - Method of manufacturing copper wire for magnet wire, copper wire for magnet wire and magnet wire - Google Patents

Description

  The present invention relates to a method for producing a copper wire for a magnet wire, a copper wire for a magnet wire, and a magnet wire.

  Copper for wire rods suitable for magnet wires and the like is a copper rough wire drawn by rolling a copper ingot (continuous casting and rolling method), and such wire rod steel is a strand of a predetermined size (round wire, flat wire). After being processed into a wire etc., it is coated with a resin and used as a magnet wire or the like. In recent years, there has been a demand for oxygen-free copper that hardly generates gas voids during connection welding of magnet wires, and oxygen-free copper wires that do not generate gas voids during connection welding are used as the strands of the magnet wires. The oxygen-free copper wire can be produced by a dip forming method in which oxygen-free molten copper is continuously solidified on the outer periphery of the core rod (oxygen-free copper), or by solidifying molten copper in a mold placed on the surface of the molten copper. For example, there is an upward pulling continuous casting method (upcasting method) that continuously pulls upward.

  There are minute defects such as cracks on the surface of the oxygen-free copper wire. This minute defect remains when the oxygen-free copper wire is processed into an element wire (round wire, flat wire, etc.) of a magnet wire, and causes a defect such as swelling in the resin coating layer in the baking process after resin coating. Become. Further, in the flat wire, since the minute defect remaining in the direction perpendicular to the rolling direction axis is subjected to tensile stress at the time of the flat forming process, there is a problem that the minute defect is easily expanded. In addition, since the edge portion of the flat wire is not coated with a uniform thickness, there is a problem that defects such as swelling are likely to occur.

  On the other hand, the minute defect of the oxygen-free copper wire is caused by a coarse blowhole contained in the copper ingot, and the inner diameter of the blowhole contained in the copper ingot to be the copper wire for magnet wire is set to 3. Resin after resin coating by setting the thickness to 0 mm or less and subjecting the copper ingot to light rolling at a rolling reduction of 3 to 20% at a temperature of 800 to 950 ° C. before continuously rolling the copper ingot. There is a magnet wire and a method for manufacturing the same that renders a blow hole of a copper ingot that causes swelling or the like in a coating layer harmless (see Patent Document 1).

  Usually, the copper wire for magnet wire (rough drawing wire) manufactured by the continuous casting rolling method, dip forming method, or upcasting method described above, removes crack defects generated during rolling and oxide films that are irregularly pressed. For this purpose, a skinning process (cutting process) is incorporated in the next process of the casting process (see Patent Document 2).

  However, since an oxygen-free copper wire has remarkably low cutting properties such as skinning compared to a tough pitch copper wire, usually, a small amount of cutting and a plurality of times of cutting are performed in the skinning process. This is because the machinability of the oxygen-free copper wire is poor, so that when a large amount of skinning is performed at one time, new defects such as fogging are avoided.

  In this way, only by suppressing defects such as cracks existing on the surface of conventional oxygen-free copper wires, defects such as blistering of the resin coating layer cannot be suppressed in the baking process after resin coating. It has been desired to suppress defects such as fog caused by cutting defects. Furthermore, depending on the material of the resin, carbon dioxide is generated in the process of baking, especially in the case of pyramidoimide resins, so the surface of the wire (round wire, rectangular wire, etc.) before resin coating is very small. If there is a defect, there is a problem that a defect such as a blister is likely to occur at the time of baking, starting from the minute defect. Therefore, it is difficult to suppress the swelling of the resin coating layer unless any minute defect generated in the manufacturing process is considered as a problem.

JP-A-2005-313208 Japanese Patent Laid-Open No. 11-010220

  In the skinning process, the peelability of the oxygen-free copper wire varies greatly depending on the above-described production methods (continuous casting and rolling method, dip forming method, upcast method, etc.). Therefore, there is a problem that it is difficult to obtain a stable quality when a specific skinning condition is applied to an oxygen-free copper wire having a different manufacturing method.

  In particular, the oxygen-free copper wire produced by the upcast method has a new grain size compared to the other production methods described above (continuous casting and rolling method, dip forming method). It was difficult to obtain stable quality by inducing defects and the like.

  The technique described in Patent Document 1 described above makes harmless micro defects (blow holes) originally present on the surface of the oxygen-free copper wire (rough drawing wire), so that the resin coating layer can be formed in the baking process after resin coating. Although it is intended to reduce defects on the surface of the wire that cause defects such as blistering, it has been difficult to reduce defects newly generated during cutting such as peeling.

  In addition, the dip forming method, which is one of the methods for producing an oxygen-free copper wire, has a complicated production process, and the upcast method can produce an oxygen-free copper wire at a lower cost.

  From this, the present inventors examined the peelability of copper for wire rods (oxygen-free copper wire) produced by the upcast method, and the difference in peelability is the crystal grain size of copper for wire rods (longitudinal direction of wire rods). The inventors have found that this is caused by the crystal grain length) of the present invention and have made the present invention.

  Furthermore, the present inventors have performed a wire drawing process with an appropriate degree of processing on the wire material before the skinning process, thereby causing defects that may newly occur due to the hardness of the surface layer of the wire material. The optimal skinning conditions for suppression were selected.

  Accordingly, an object of the present invention is to provide a magnet wire in which defects such as swelling of the resin coating layer are reduced, and to suppress defects such as swelling that may occur in the resin coating layer in the baking process after resin coating. An object of the present invention is to provide a copper wire for magnet wires (oxygen-free copper wire) having good peelability. Another object of the present invention is to provide an inexpensive oxygen-free copper wire that can be produced by the upward pulling continuous casting method (upcast method).

In order to achieve the above object, a first aspect of the present invention provides a magnet wire in which a molten copper is continuously pulled up to form a cast wire, and the cast wire is stripped using a die to obtain a copper wire for a magnet wire. A method for producing a copper wire for forming a cast wire, wherein a crystal grain length in a longitudinal direction of the wire in a surface layer of the cast wire is controlled to 300 μm or less, and the cast wire is drawn at a workability of 30 to 40%. It is a manufacturing method of the copper wire for magnet wires characterized by carrying out skinning after processing .

Invention of Claim 2 is a manufacturing method of the copper wire for magnet wires of Claim 1 whose oxygen content of the said cast wire is 0.001 wt% or less .

The invention according to claim 3 is the magnet wire according to claim 1 or 2 , wherein the cast wire is formed by continuously pulling up a copper melt of 1100 to 1200 ° C at a speed of 4 to 5 m / min . It is a manufacturing method of a copper wire.

Invention of Claim 4 was manufactured using the manufacturing method of the copper wire for magnet wires in any one of Claims 1-3 , It is the copper wire for magnet wires characterized by the above-mentioned.

According to a fifth aspect of the present invention, the magnet wire is formed by coating the copper wire for the magnetic wire according to the fourth aspect with a resin coating layer having a two-layer structure of highly adhesive polyimide and polyamideimide. It is.

The invention of claim 6 is characterized in that the magnet wire copper wire according to claim 4 is coated with a resin coating layer composed of a three-layer structure of high adhesion polyamideimide, polyimide and polyamideimide. It is a magnet wire.

  According to the present invention, a magnet wire in which defects such as swelling of the resin coating layer are reduced by performing wire drawing with a processing degree of 30 to 40% on the rough-drawn wire (cast wire) before skinning. Moreover, it becomes possible to obtain a copper wire for a magnet wire with good peelability by making the crystal grain length in the longitudinal direction of the wire in the surface layer 300 μm or less.

  Hereinafter, a preferred embodiment of the present invention will be described in detail.

  FIG. 1 shows a cross-sectional view of a magnet wire according to an embodiment of the present invention. FIG. 1A shows a round wire magnet wire, and FIG. 1B shows a flat wire magnet wire. FIG. 2 shows a schematic diagram of the upcast apparatus.

  As shown in FIG. 2, an upcast apparatus (upward continuous casting apparatus) 10 includes a melting furnace (for example, an electric furnace) 11 for melting metal (copper) and a molten copper 12 melted in the melting furnace 11. A holding furnace (for example, an electric furnace) 14 that flows in via the molten metal slag 13, a casting apparatus 16 having a mold 15 whose lower part enters under the surface of the molten copper in the holding furnace 14, and the mold 15 pass through. A cooling water passage 17 through which cooling water for cooling the molten copper 12 flows, and a pulling up for pulling upward the copper molten metal 12 solidified in the mold 15 as an oxygen-free copper wire 18 (cast wire) 18 Device 19. An antioxidant 20 for preventing oxidation of the molten copper 12 is arranged on the surface of the molten copper in the melting furnace 11 and the holding furnace 14.

  The molten copper 12 is cooled and solidified in a mold 15 arranged on the surface of the molten copper in the holding furnace 14, and the oxygen-free copper wire 18 is continuously pulled upward using the pulling device 19.

  The oxygen-free copper wire rough-drawn wire 18 cast by the upcast apparatus 10 has a crystal grain size of the surface layer of 200 to 300 μm and an oxygen content of 0.001 wt% or less (or an oxygen concentration of 10 ppm or less). Is preferred.

  By drawing the molten copper at 1100 to 1200 ° C. continuously at a speed of 4 to 5 m / min, the rough drawn wire 18 of oxygen-free copper wire having a crystal grain size of the surface layer of 200 to 300 μm (in this embodiment, the wire diameter φ8 mm) can be obtained.

  Moreover, the oxygen-free copper wire in which the oxygen content is 0.001 wt% or less (or the oxygen concentration is 10 ppm or less) by disposing the antioxidant 20 on the surface of the molten copper in the melting furnace 11 and the holding furnace 14. The rough drawn wire 18 can be obtained.

  Here, as shown in FIG. 4, the crystal structure in the surface layer of the oxygen-free copper wire rough drawn wire 18 cast by the upcast apparatus 10 is a columnar crystal structure extending from the wire surface toward the inside of the wire. Moreover, it becomes a long and narrow crystal grain. Therefore, in this embodiment, the average value of the crystal grain length in the longitudinal direction of the wire in the surface layer is defined as the crystal grain size.

  Next, after drawing the oxygen-free copper wire 18 with a wire drawing device at a workability (area reduction ratio) of 30 to 40%, as shown in FIG. Skinning was performed using a die 21 (peeling device).

  A skinning die 21 used in the skinning process is composed of a die body 23 in which a die hole 22 through which a wire passes is formed, and a cutting edge 24 disposed on the wire material inlet side of the die hole 22. The die hole 22 is formed in a taper shape whose diameter increases toward the traveling direction of the wire. The skin peeling die 21 preferably has a rake angle θ of the cutting edge 24 of 20 to 35 °. The rake angle θ is an angle of the blade surface 24a of the cutting edge 24 with respect to a direction perpendicular to the wire longitudinal direction.

  Next, after the stripped wire is drawn to a predetermined wire diameter (in this embodiment, wire diameter φ2.6 mm) by a wire drawing device, the drawn wire is annealed and then annealed. Is processed into a round wire or a rectangular wire to obtain a copper wire 25 for magnet wire (a conductor of the magnet wire 26) (see FIG. 1).

  Finally, as shown in FIG. 1, the resin coating layers 27 and 28 were coated on the copper wire 25 (conductor) for magnet wire and baked to manufacture the magnet wire 26.

  As shown in FIG. 1, in the present embodiment, the resin coating layer has a two-layer structure of a lower layer 27 and an upper layer 28. For example, the resin coating layer has a two-layer structure of highly adhesive polyimide and polyamideimide.

  As the high adhesion polyimide, it is possible to use a PI resin insulating paint with an additive called an adhesion improver added and mixed. The adhesion improver is not particularly limited as long as it has an effect of improving the adhesion strength between the conductor (copper wire 25 for magnet wire) and the inner layer (lower layer 27). For example, butylated melamine resin Melamine resins such as trialkylamine, mercaptans such as mercaptobenzimidazole, polycarbodiimide resins, and the like. Two or more types of adhesion improvers may be added in combination.

  Although not shown, the resin coating layer may have a three-layer structure. For example, the resin coating layer has a three-layer structure of highly adhesive polyamideimide, polyimide, and polyamideimide.

  As a high adhesion polyamide imide, an adhesion improver comprising a polyamide imide resin, a resin such as thiadiazole, thiazole, mercaptobenzimidazole, thiophenol, thiophone, thiol, tetrazole, benzimidazole, butylated melamine, and heterocyclic mercaptan. A mixed resin in which any of them is mixed can be used.

  According to the present embodiment, the oxygen-free copper wire rough-drawn wire (cast wire) 18 is drawn at a working degree of 30 to 40%, and then stripped to provide the wire as a conductor of the magnet wire 26. (Magnetic wire copper wire 25) is processed (round wire, rectangular wire), coated with resin (resin coating layers 27, 28) and baked to form magnet wire 26, swelling of resin coating layers 27, 28, etc. Defects can be suppressed.

  That is, the oxygen-free copper wire has higher ductility than tough pitch copper, and the machinability such as peeling is remarkably lowered. Therefore, the machinability can be improved by curing the wire surface layer.

  When the degree of wire drawing is low (when the degree of processing is less than 30%), the surface of the wire is soft and does not harden sufficiently, causing fogging during the stripping process, resulting in a magnet wire As a result, the occurrence rate of blistering is high.

  Moreover, when the workability of wire drawing is high (when the workability is 50% or more), the wire surface layer is sufficiently cured, but the wire surface layer is hard, so that the cutting edge 24 of the peeling die 21 has a cutting edge. When the wire rod is difficult to squeeze and peels off more than a predetermined size during the skinning process, the scraps of the skin are clogged in the skinning die, resulting in a wire breakage.

  Further, according to the present embodiment, the rough drawn wire 18 of the oxygen-free copper wire has a fine structure in which the crystal grain length in the longitudinal direction of the wire in the surface layer is 300 μm or less, so that the copper for magnet wire with good peelability is provided. A line 25 can be obtained.

  When stripping the rough drawn wire 18 of the oxygen-free copper wire, the smaller the crystal grain length (crystal grain size) in the longitudinal direction of the wire in the surface layer, the more crystal grain boundaries that become the starting points of cutting exist, Shear deformation becomes easy, and machinability such as peeling is improved. Therefore, it is possible to remove minute defects such as cracks originally present in the rough drawn wire 18 having a wire diameter of 8 mm without generating new defects on the surface of the magnet wire copper wire 25.

  Conversely, if the crystal grain length (crystal grain size) in the longitudinal direction of the wire on the surface of the wire is large, there are few crystal grain boundaries that are the starting point of cutting, so the resistance variation during cutting is large and continuous shear deformation occurs. It becomes difficult and the peelability becomes worse. As a result, a new defect is generated on the surface of the copper wire 25 for the magnet wire, and a minute defect such as a crack that originally exists in the rough drawn wire 18 having a wire diameter of 8 mm cannot be removed. The incidence of blistering increases.

  Examples 1 to 6 and Comparative Examples 1 to 14 will be described below together with Table 1.

Example 1
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 5.0 m / min by an upcast method to produce a rough drawn wire of an oxygen-free copper wire having a wire diameter of 8 mm and a crystal grain size of 200 μm on the surface layer. . The rough-drawn wire was drawn at a workability of 30%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Example 2)
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 5.0 m / min by an upcast method to produce a rough drawn wire of an oxygen-free copper wire having a wire diameter of 8 mm and a crystal grain size of 200 μm on the surface layer. . The rough-drawn wire was drawn at a workability of 40%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Example 3)
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 4.5 m / min by an upcast method to produce an oxygen-free copper wire rough drawn wire having a diameter of 8 mm and a surface crystal grain size of 250 μm. . The rough-drawn wire was drawn at a workability of 30%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

Example 4
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 4.5 m / min by an upcast method to produce an oxygen-free copper wire rough drawn wire having a diameter of 8 mm and a surface crystal grain size of 250 μm. . The rough-drawn wire was drawn at a workability of 40%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Example 5)
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 4.0 m / min by an upcast method, and an oxygen-free copper wire rough drawn wire having a wire diameter of 8 mm and a crystal grain size of 300 μm was produced. . The rough-drawn wire was drawn at a workability of 30%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Example 6)
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 4.0 m / min by an upcast method, and an oxygen-free copper wire rough drawn wire having a wire diameter of 8 mm and a crystal grain size of 300 μm was produced. . The rough-drawn wire was drawn at a workability of 40%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Comparative Example 1)
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 5.0 m / min by an upcast method to produce a rough drawn wire of an oxygen-free copper wire having a wire diameter of 8 mm and a crystal grain size of 200 μm on the surface layer. . The rough-drawn wire was drawn at a workability of 20%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Comparative Example 2)
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 5.0 m / min by an upcast method to produce a rough drawn wire of an oxygen-free copper wire having a wire diameter of 8 mm and a crystal grain size of 200 μm on the surface layer. . After this rough-drawn wire was drawn at a workability of 50%, the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min.

(Comparative Example 3)
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 4.5 m / min by an upcast method to produce an oxygen-free copper wire rough drawn wire having a diameter of 8 mm and a surface crystal grain size of 250 μm. . The rough-drawn wire was drawn at a workability of 20%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Comparative Example 4)
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 4.5 m / min by an upcast method to produce an oxygen-free copper wire rough drawn wire having a diameter of 8 mm and a surface crystal grain size of 250 μm. . After this rough-drawn wire was drawn at a workability of 50%, the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min.

(Comparative Example 5)
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 4.0 m / min by an upcast method, and an oxygen-free copper wire rough drawn wire having a wire diameter of 8 mm and a crystal grain size of 300 μm was produced. . The rough-drawn wire was drawn at a workability of 20%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Comparative Example 6)
The cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 4.0 m / min by an upcast method, and an oxygen-free copper wire rough drawn wire having a wire diameter of 8 mm and a crystal grain size of 300 μm was produced. . After this rough-drawn wire was drawn at a workability of 50%, the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min.

(Comparative Example 7)
By an upcast method, the cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 3.0 m / min to produce a rough drawn wire of an oxygen-free copper wire having a wire diameter of 8 mm and a crystal grain size of 400 μm on the surface layer. . The rough-drawn wire was drawn at a workability of 20%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Comparative Example 8)
By an upcast method, the cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 3.0 m / min to produce a rough drawn wire of an oxygen-free copper wire having a wire diameter of 8 mm and a crystal grain size of 400 μm on the surface layer. . The rough-drawn wire was drawn at a workability of 30%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Comparative Example 9)
By an upcast method, the cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 3.0 m / min to produce a rough drawn wire of an oxygen-free copper wire having a wire diameter of 8 mm and a crystal grain size of 400 μm on the surface layer. . The rough-drawn wire was drawn at a workability of 40%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Comparative Example 10)
By an upcast method, the cast wire was continuously pulled upward from a molten metal at 1150 ° C. at a speed of 3.0 m / min to produce a rough drawn wire of an oxygen-free copper wire having a wire diameter of 8 mm and a crystal grain size of 400 μm on the surface layer. . After this rough-drawn wire was drawn at a workability of 50%, the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min.

(Comparative Example 11)
By the upcast method, the cast wire was continuously pulled upward from the molten metal at 1150 ° C. at a speed of 2.5 m / min to produce a rough drawn wire of oxygen-free copper wire having a wire diameter of φ8 mm and a surface crystal grain size of 500 μm. . The rough-drawn wire was drawn at a workability of 20%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Comparative Example 12)
By the upcast method, the cast wire was continuously pulled upward from the molten metal at 1150 ° C. at a speed of 2.5 m / min to produce a rough drawn wire of oxygen-free copper wire having a wire diameter of φ8 mm and a surface crystal grain size of 500 μm. . The rough-drawn wire was drawn at a workability of 30%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Comparative Example 13)
By the upcast method, the cast wire was continuously pulled upward from the molten metal at 1150 ° C. at a speed of 2.5 m / min to produce a rough drawn wire of oxygen-free copper wire having a wire diameter of φ8 mm and a surface crystal grain size of 500 μm. . The rough-drawn wire was drawn at a workability of 40%, and then the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min. After the skinning process, the wire drawn to a diameter of 2.6 mm was annealed. Thereafter, the annealed wire was flattened, the wire was then annealed, and finally a resin coating layer was coated on the wire and baked to produce a magnet wire. The resin coating layer was composed of a two-layer structure of highly adhesive polyimide and polyamideimide.

(Comparative Example 14)
By the upcast method, the cast wire was continuously pulled upward from the molten metal at 1150 ° C. at a speed of 2.5 m / min to produce a rough drawn wire of oxygen-free copper wire having a wire diameter of φ8 mm and a surface crystal grain size of 500 μm. . After this rough-drawn wire was drawn at a workability of 50%, the drawn wire was subjected to skinning with a skinning thickness of 0.15 mm. A skinning die was used for the skinning process, and the rake angle of the cutting edge of the die was set to 30 °. Further, the peeling speed was 200 m / min.

  In Examples 1 to 6 and Comparative Examples 1 to 14, the control of the crystal grain length (crystal grain size of the surface layer) in the longitudinal direction of the surface of the rough drawn wire of the oxygen-free copper wire is controlled by the speed of the pulling device (wire material) By changing the pulling speed of Specifically, an oxygen-free copper wire with a small surface grain size can be obtained by increasing the wire pulling speed, and a surface crystal grain size can be reduced by reducing the wire pulling speed. A large oxygen-free copper wire rough wire is obtained.

  Further, since the holding furnace is an electric furnace, the temperature of the molten metal in the holding furnace was controlled to be always constant. The temperature was measured by inserting a thermocouple into the holding furnace.

  Moreover, in Examples 1-6 and Comparative Examples 1, 3, 5, 7-9, 11-13, the resin content of 100 parts by weight of polyimide (Trenice (registered trademark) # 3000, manufactured by Toray Industries, Inc.) paint High adhesion polyimide to which 1 part by weight of an adhesion improver (butylated melamine resin) was added was used.

  Table 1 shows the crystal grain size of the surface layer of the oxygen-free copper wires of Examples 1 to 6 and Comparative Examples 1 to 14, the degree of wire rod processing before skinning, the presence or absence of disconnection during skinning, and the magnet wire. The incidence of blistering and overall evaluation are shown. Comprehensive evaluation was evaluated as “発 生” when the rate of occurrence of swelling when the magnet wire was used was 0.30 piece / km or less, and “x” when the rate was over 0.30 piece / km. Moreover, the thing with a disconnection at the time of a skinning process made the comprehensive evaluation x.

  As shown in Table 1, in Examples 1 to 6, when the stripping process was performed on the rough-drawn wire with a diameter of 8 mm manufactured by the upcast method, the peelability was good, and the surface of the wire was new. By removing minute defects such as cracks that originally existed on the surface layer of the rough drawn wire without generating defects, the occurrence rate of blistering when magnet wires were obtained was a good result.

  In Comparative Examples, Comparative Examples 1, 3, 5, 7, and 11 in which the degree of wire processing before skinning was 20% were not able to give sufficient processing to the surface of the wire, and the surface of the wire was in a soft state. As a result, fogging scratches occurred during the stripping process, and as a result, the rate of occurrence of swelling when the magnet wire was formed was high.

  In Comparative Examples 2, 4, 6, 10, and 14 in which the degree of wire rod processing before skinning was 50%, the wire surface layer was sufficiently processed and the wire surface layer was hardened. The cutting edge of the blade was difficult to squeeze into the wire, and peeled off to a thickness greater than a predetermined size during the skinning process, resulting in the scraping scraps being clogged in the skinning die and the wire being disconnected.

  In Comparative Examples 8, 9, 12, and 13, since the crystal grain size of the surface layer is large (the crystal grain length in the longitudinal direction of the wire in the surface layer is long) and there are few crystal grain boundaries that are the starting points of cutting, Fluctuation is large, continuous shear deformation becomes difficult, and the peelability becomes worse. As a result, new defects are generated on the surface of the wire, and minute defects such as cracks originally present in the rough drawn wire cannot be removed, resulting in a high occurrence rate of swelling when the magnet wire is used.

  In this example, evaluation was made using an enameled wire (magnet wire) having an insulating coating having a two-layer structure of highly adhesive polyimide and polyamideimide. Similarly good results were obtained when an enameled wire (magnet wire) having a three-layer insulating coating was used.

  Moreover, in this example, the evaluation of the oxygen-free copper wire having a surface layer crystal grain size smaller than “200 μm” is not performed because the current upcast apparatus has a crystal grain size of “200 μm” from the surface layer. This is because it is difficult to produce a small rough drawn wire (cast wire).

  Based on the above results, in order to obtain a copper wire for magnet wire with good peelability, a rough-drawn wire (cast wire) having a fine structure with a crystal grain length of 300 μm or less (200 to 300 μm) in the longitudinal direction of the wire in the surface layer In order to suppress defects such as blistering that may occur in the resin coating layer in the baking process after resin coating, the roughing wire (cast wire) before skinning has a processing degree of 30 to 40%. It was found that it was necessary to perform wire drawing.

FIG. 1 is a cross-sectional view of a magnet wire according to an embodiment of the present invention. FIG. 2 is a schematic diagram of the upcast apparatus. FIG. 3 is an explanatory view showing the rake angle of the skinning die. FIG. 4 is a schematic diagram showing a cross-sectional structure in the longitudinal direction of an oxygen-free copper wire (copper rough wire).

Explanation of symbols

12 Molten copper 18 Oxygen-free copper wire rough wire (cast wire)
21 Peeling dice (dies)
25 Copper wire for magnet wire (conductor of magnet wire)
26 Magnet wire 27 Resin coating layer (lower layer)
28 Resin coating layer (upper layer)

Claims (6)

A method for producing a copper wire for a magnet wire by continuously pulling up a molten copper to form a cast wire, and stripping the cast wire using a die to obtain a copper wire for a magnet wire , In forming the magnet wire, the crystal wire length in the longitudinal direction of the wire in the surface layer of the cast wire is controlled to 300 μm or less, and the cast wire is drawn at a workability of 30 to 40% and then stripped. Method for manufacturing copper wire. The method for producing a copper wire for a magnet wire according to claim 1, wherein the oxygen content of the cast wire is 0.001 wt% or less. Method of manufacturing magnet wire copper wire according to claim 1 or 2 copper melt of 1100 to 1200 ° C. continuously pulled up at a rate of 4 ~5m / min and forming the cast wire. It manufactured using the manufacturing method of the copper wire for magnet wires in any one of Claims 1-3 , The copper wire for magnet wires characterized by the above-mentioned. A magnet wire, comprising a copper wire for a magnet wire according to claim 4 and a resin coating layer having a two-layer structure of a highly adhesive polyimide and a polyamideimide. 5. A magnet wire comprising a copper wire for a magnet wire according to claim 4 and a resin coating layer having a three-layer structure of high adhesion polyamideimide, polyimide, and polyamideimide.

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