JPH0377602B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a copper rough drawn wire obtained by the deep forming method, which is a type of continuous casting method for metal wire, and particularly relates to a copper wire that is subjected to vacuum annealing after wire drawing. This is about the rough lines.

In recent years, the dip forming method has been put into practical use for producing copper wire. To explain the deep forming manufacturing method of this copper rough drawing wire with reference to Figure 1, there is a seed wire insertion hole 1 at the bottom.
A molten copper supply port 4 is connected from a melting furnace 3 to a crucible 2 made of a refractory material such as graphite in which
A seed wire 6 of a predetermined diameter, also made of pure copper, is continuously inserted into the crucible 2 from below the crucible 2 through the seed wire insertion port 1 to supply the molten copper 5. The seed wire 6 is then continuously pulled up vertically from the molten copper 5 in the crucible 2 and cooled by water cooling or the like in the cooling tower 7. Copper is deposited and solidified to continuously obtain a cast wire with a diameter larger than the diameter of the seed wire 6, and then the cast wire is hot rolled to produce a rough drawn copper wire of a desired diameter and then wound (not shown). It is wound onto a device. In this method, by continuously supplying the seed wire 6, the process from casting (adhesion and solidification of the molten copper 5 to the seed wire 6) to obtaining a rough drawn copper wire of a desired diameter is performed completely continuously. It has various advantages such as high quality and good quality.

By the way, when manufacturing copper wire using the deep forming method, in order to obtain copper wire of sound quality, it is necessary to use the method as already disclosed in U.S. Pat. The amount of oxygen in the molten copper in the Crucible is
It is known that the content must be 20ppm or less. In other words, if the amount of oxygen in molten copper exceeds 20 ppm, cracks will occur during processing such as rolling or wire drawing due to the formation of oxides, making it difficult to process even the finest wires. In extreme cases, cracks may occur in the casting rod itself. In this way, the amount of oxygen in the molten copper in the Crucible is
A common method for reducing the content to 20 ppm or less is to cover the surface of the molten copper with a reducing atmosphere gas, as described in the above-mentioned publication. That is, the first
As shown in the figure, a reducing atmosphere gas supply port 8 is provided on the side wall of the crucible 2, and reducing atmosphere gas is supplied from this supply port 8 to the inside of the crucible 2.
A method is adopted in which the surface of the molten copper inside the Crucible 2 is covered with a reducing atmosphere gas to prevent oxygen absorption from the surface of the molten copper.

As mentioned above, when manufacturing copper wire using the deep forming method, it is important to keep the amount of oxygen in the molten copper to 20 ppm or less. It has long been known that reducing the oxygen content of the deposited and solidified layer to 20 ppm or less is effective in obtaining copper wire of sound quality, but when implementing this conventional method, It is thought that it is desirable to keep the oxygen content well below 20 ppm, and therefore, in actual operations, the oxygen content in molten copper is usually suppressed to an extremely small value of less than 10 ppm. It was hot. However, although the copper wire material produced in this manner has good quality itself, the following disadvantages occurred in the manufacturing process.

That is, the copper rough drawn wire obtained by the dip forming method described above is drawn to the desired wire diameter and wound onto an iron bobbin, etc., and the wound bobbin is placed in a vacuum annealing furnace. Normally, the wire is charged and subjected to vacuum annealing to soften it, but during vacuum annealing, the softened rough drawn copper wire is joined to each other at the contact area between the wires, and the processed wire is removed from the bobbin. Situations may occur where it is no longer possible to perform the operations smoothly. In this case, in order to unwind the treated wire from an iron bobbin, etc., it is necessary to peel off the wire that is joined to the adjacent wire at the contact area, and as a result, the wire is bent at the peeled part. In particular, thin wire rods with a diameter of 0.3 mm or less may break at the part where they are peeled off, and this situation is a serious problem when actually heat-treating copper rough drawn wire manufactured by the deep forming method. I was getting used to it.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional circumstances, it is an object of the present invention to provide a copper rough-drawn wire by dip forming, which does not cause bonding between wound wires even when subjected to vacuum annealing.

As mentioned above, when a copper wire wound around an iron bobbin or the like is subjected to vacuum annealing, the phenomenon in which adjacent wire rods bond to each other is thought to be due to thermal diffusion between the wire rods. On the other hand, it is known that thermal diffusion, which causes this bonding phenomenon between wires, also generally promotes crystal grain growth of the material. Therefore, the present inventors believed that if they could find conditions that would not cause excessive grain growth during vacuum annealing, they would be able to prevent the bonding phenomenon described above at the same time, and conducted various experimental studies. It was discovered that the grain growth of copper wire by vacuum annealing is closely related to the oxygen content, and that bonding phenomena actually occur frequently in this case. Based on these findings, the present invention was developed in which the wires do not bond to each other even when copper rough-drawn wire is vacuum annealed by dip forming.

In other words, the copper rough drawing wire by deep forming of the present invention involves continuously dipping a seed wire made of pure copper in molten copper and pulling it up, thereby causing the molten copper to adhere and solidify around the seed wire, and then hot rolling. Copper rough drawn wire obtained by the deep forming method, which is subjected to vacuum annealing after wire drawing, has an oxygen content of 10 ppm or more and 20 ppm or less in the adhering solidified layer on the surface. It is characterized by the fact that

The present invention will be explained in more detail below with reference to the embodiment shown in FIG.

Figure 2 shows that a suitable number of rough drawn copper wires with different amounts of oxygen are manufactured using the deep forming method, each wire is drawn to a diameter of 0.2 mm, and wound around an iron bobbin.
After vacuum annealing at a temperature of 400℃ for 2 hours and 30 minutes, the size of the crystal grains of each wire and the bonding state between the wound wires were examined, and the results and the surface of each wire due to dip forming were examined. This figure shows the relationship between the amount of oxygen contained in the deposited and solidified layer.

In the figure, the vertical axis is the grain size (μm)
is shown, and the horizontal axis shows the amount of oxygen content (ppm). In addition, the upper part of the figure shows the results of qualitative evaluation of the bonding state between the wound wire rods. That is, the mark ◯ indicates that there is no bond between the wire rods, and the mark x indicates that the state of bond between the wire rods is significant. As shown in the figure, when the oxygen content was close to 20 ppm, the crystal grain size was about 10 μm, and no bonding occurred between the wires. In addition, the amount of oxygen content decreases,
At around 11ppm, crystal grain growth is observed, and the 40μ
m, but no bonding occurs between the wire rods. However, at an oxygen content of 10 ppm, the curve shown in the figure suddenly rises to a critical level, and in all cases where the oxygen content is 10 ppm or less, crystal grains are
The thickness was approximately 100 μm, and the state of bonding between the wires was also remarkable.

As is clear from the above examples, when the wire rod obtained by the dip forming method is wound around an iron bobbin etc. and subjected to vacuum annealing, the amount of oxygen content
With a critical value of 10 ppm, bonding occurs between wire rods when the concentration is lower than that. Therefore, in order to prevent this, the oxygen content must be adjusted to 10 ppm or more. As mentioned above, when manufacturing copper wire by the deep forming method, if the oxygen content exceeds 20 ppm, cracks may occur, making it difficult to stably obtain copper wire of good quality. Therefore, the upper limit of the amount of oxygen was set at 20 ppm. Specifically, as shown in FIG. 1, the reducing atmosphere gas supply port 8 provided on the side wall of the crucible 2
A reducing atmosphere gas is supplied to the inside of the Crucible 2, and the amount of oxygen content is adjusted by covering the molten copper surface inside the Crucible 2 with the reducing atmosphere gas and suppressing oxygen absorption from the molten copper surface. Ta.

As described above, according to the present invention, as a copper rough drawn wire that is formed by deep forming and that is subjected to vacuum annealing after wire drawing, the oxygen content in the adhering solidified layer on the surface is is adjusted so that it is 10ppm or more and 20ppm or less,
After drawing the copper wire, winding it onto an iron bobbin, etc., and vacuum annealing, adjoining wires do not bond with each other, so the process after vacuum annealing does not occur. can be smoothly fed out from iron bobbins, etc. Further, in this case, the wire is not bent or broken because the bond is peeled off, and a copper rough drawn wire by dip forming can be obtained at a low cost.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view showing the main parts of a device for carrying out the deep forming method, and Figure 2 shows the size of crystal grains and oxygen content of rough drawn copper wire by deep forming. FIG. 2... Crucible, 3... Melting furnace, 4... Molten copper supply port, 6... Seed wire, 7... Cooling tower, 8... Reducing atmosphere gas supply port.

Claims (1)

[Claims] 1 Copper roughening obtained by the deep forming method in which a seed wire made of pure copper is continuously immersed in molten copper and pulled up, thereby causing the molten copper to adhere and solidify around the seed wire, and then hot rolled. Copper rough drawing wire, which is a drawing wire and is subjected to vacuum annealing after wire drawing, is produced by deep forming, characterized in that the oxygen content in the solidified layer on the surface is 10 ppm or more and 20 ppm or less. Copper rough wire.