JP2008255416A - Method for manufacturing copper material, and copper material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an inexpensive oxygen-free copper material having low softening temperature and high electric conductivity and also to provide a copper material. <P>SOLUTION: In a method for directly manufacturing a copper material from molten oxygen-free copper using an up-drawing continuous casting machine, at least one metal or alloy selected from Ti, Zr, V, Ta, Fe, Ca, Mg and Ni or alloys thereof is added to the molten oxygen-free copper stored in a molten metal storing means of the up-drawing continuous casting machine to regulate the proportion of the metal or alloy contained in the molten oxygen-free copper to 0.0004 to 0.055 wt.%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a copper material, and more particularly to a method for producing an oxygen-free copper material.

  At present, most of various types of wires including copper wires are formed by a continuous casting and rolling method. First, the molten metal melted in the shaft furnace is supplied to an SCR-type or continuous rod (registered trademark) type continuous casting means to obtain a casting bar. Next, the casting bar is supplied to a hot rolling means connected to the continuous casting means and rolled to a predetermined outer diameter. Thereafter, the rolled material is cooled, and a rough drawing line is obtained (for example, see Patent Document 1).

  In the continuous casting and rolling method, each line of the melting step, the casting step, and the hot rolling step is continuous, which is an efficient method for producing the roughing wire and is an excellent method for productivity. The rough drawing wire thus obtained is then subjected to a cold drawing step and an annealing step to obtain a final product (for example, a copper wire). One component of this copper wire is tough pitch copper. Since tough pitch copper can use a mixture of scrap copper and electric copper, the raw material cost is low. Moreover, since tough pitch copper has a higher oxygen content than oxygen-free copper, it inevitably has a feature that the content of oxidized impurities is higher than oxygen-free copper. Further, as a method for producing oxygen-free copper, there is an upward pulling continuous casting method (upcasting method) in which molten copper is solidified in a mold disposed on the surface of the molten copper and continuously pulled upward. In recent years, this oxygen-free copper has been used for magnet wires for motors.

JP-A-6-240426

  By the way, industrial productivity can be improved by performing continuous annealing in the annealing process of copper wire manufacture (a cold wire drawing process and an annealing process are performed continuously). However, in this case, if the softening temperature of the annealed material is high, the annealing process takes time, and it is necessary to match the production speed of the cold drawing process with the production speed of the annealing process, which hinders the productivity of copper wire. Is done. Moreover, when the softening temperature of the material to be annealed is high, the thermal energy required for annealing increases, leading to an increase in product cost. Therefore, the softening temperature of the material to be annealed is lowered.

  In order to lower the softening temperature of the copper material, it is necessary to remove the impurity elements contained in the copper base material and increase the Cu purity. As a method for removing the impurity element, there are, for example, selection of a molten metal raw material (using a high-purity material), oxidation refining of the molten metal, reduction refining, and the like. However, this method of removing the impurity element is a method that is very expensive. For this reason, when tough pitch copper is used for the molten metal raw material, this method is extremely disadvantageous economically and cannot be said to be an industrially suitable method. Furthermore, in recent years, there has been a demand for oxygen-free copper that hardly causes gas voids during connection welding of a magnet wire or the like, and tough pitch copper is not suitable in this respect.

  On the other hand, as another method for lowering the softening temperature of the copper material, it is known that the concentration of a certain element among impurity elements contained in the copper base material may be lowered. One of the elements mentioned here includes sulfur (S) and lead (Pb) that are present in a solid solution state in Cu. In order to reduce the concentration of S and Pb solid-dissolved in Cu, measures such as vacuum degassing of the molten copper and heat treatment at a specific temperature on the copper bar after casting have been attempted. However, since these conventional measures cannot sufficiently reduce the concentration of S and Pb, the softening temperature of the copper material cannot be sufficiently lowered. Furthermore, with the spread of HEV cars in recent years, high conductivity is required for the conductor of the magnet wire from the viewpoint of increasing the efficiency of the motor.

  An object of the present invention created in view of the above circumstances is to provide an oxygen-free copper material manufacturing method and a copper material that are inexpensive, have a low softening temperature, and have a high electrical conductivity.

  In order to achieve the above object, a method for producing a copper material according to the present invention is a method for producing a copper material directly from an oxygen free molten copper using an upward pulling continuous casting apparatus. At least one metal or alloy selected from Ti, Zr, V, Ta, Fe, Ca, Mg, or Ni is added to the oxygen-free copper melt stored in the storage means and included in the oxygen-free copper melt The ratio of the metal or alloy to be adjusted is adjusted to 0.0004 to 0.055% by weight.

  On the other hand, the copper material which concerns on this invention is a copper material manufactured using the manufacturing method of the copper material mentioned above, Comprising: A semi-softening temperature is 110 degrees C or less.

  According to the present invention, it is possible to obtain an excellent effect that an oxygen-free copper material that is inexpensive, has a low softening temperature, and has high conductivity can be obtained.

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

  The manufacturing method of the copper material which concerns on one preferred embodiment of this invention manufactures a copper material directly from an oxygen free molten copper using an upward pulling continuous casting apparatus.

  Specifically, first, Ti, Zr, V, Ta, Fe, Ca, Mg, or Ni are added to the oxygen-free copper molten metal stored in the molten metal storage means (for example, a melting furnace) of the upward pulling continuous casting apparatus. At least one metal or alloy selected from is added. At this time, the addition amount is adjusted so that the ratio of the metal or alloy contained in the oxygen-free copper melt is 0.0004 to 0.055 wt%. These metals (or alloys) are all metals having a high affinity with S (hereinafter referred to as sulfur-affinity metals). The sulfur-affinity metal mentioned here may be either a simple substance or a mixture of metal elements, or a simple substance or a mixture of alloys.

  The oxygen-free copper herein means pure copper having an oxygen content of 10 ppm or less and containing inevitable impurities.

  Next, an oxygen-free copper molten metal containing a sulfur-affinity metal is pulled upward from a mold placed on the surface of the molten copper, and an oxygen-free copper roughing material (for example, a roughing wire) is continuously produced. Thereafter, the roughing material is appropriately subjected to cold surface reduction to obtain a final wire diameter, and a copper material (for example, copper wire) having a semi-softening temperature of 110 ° C. or less is obtained. A product obtained by subjecting this copper material to annealing treatment is the final product. The semi-softening temperature mentioned here is a temperature at which the tensile strength of the copper material after heating for 60 minutes becomes half the tensile strength of the copper material before heating.

  The content of the sulfur-affinity metal is defined as 0.0004 to 0.055% by weight, preferably 0.0005 to 0.045% by weight, more preferably 0.001 to 0.045% by weight. Is less than 0.0004% by weight, the sulfur-soluble metal and S dissolved in the copper base material do not sufficiently react, and the effect of lowering the softening temperature cannot be sufficiently obtained. On the other hand, when the content exceeds 0.055% by weight, the amount of the sulfur-affinity metal that dissolves in the copper material increases so much that the softening temperature of the copper material increases conversely.

  The reason why the semi-softening temperature is defined as 110 ° C. or lower, preferably 100 ° C. or lower is that when the semi-softening temperature is 110 ° C. or higher, the effect of reducing the softening temperature of the copper material is not sufficient.

  Here, the reason why the softening temperature of the copper material according to the present embodiment is greatly reduced is considered as follows.

  Ordinary oxygen-free copper has about 10 ppm of S dissolved therein, and this S is said to be a major factor that raises the softening temperature of the copper material. Therefore, in the manufacturing method according to the present embodiment, a sulfur-affinity metal is added at a predetermined ratio to the oxygen-free molten copper just before casting. The sulfur-affinity metal (for example, Ti) reacts with S dissolved in the oxygen-free copper melt, so that S is precipitated as a sulfide (for example, TiS), and the solid solution amount of S is reduced. . Further, since the sulfur-affinity metal becomes a nucleus when the oxygen-free copper melt is solidified and recrystallized, it is possible to reduce the recrystallization energy of oxygen-free copper. It is considered that the softening temperature of the copper material can be greatly reduced by these combined effects.

  The form of the roughing material used in the manufacturing method according to the present embodiment and the finally obtained copper material is not particularly limited as long as it can be formed by surface reduction processing. For example, the shape is linear or plate-like. Or any of the stripes.

  Next, the operation of the copper material according to the present embodiment will be described.

  Usually, a copper wire obtained by subjecting a rough drawn material to cold surface reduction, drawing, and drawing is a high-hardness wire (for example, hard copper wire) by work hardening. For this reason, when annealing normal copper wire, particularly when annealing annealing, high temperature and long time heat treatment is required.

  However, the oxygen-free copper material obtained by the manufacturing method according to the present embodiment is selected from Ti, Zr, V, Ta, Fe, Ca, Mg, or Ni as the oxygen-free copper melt as a raw material for the copper material. The at least one sulfur-affinity metal is added so that the content thereof is 0.0004 to 0.055% by weight.

  Here, since the sulfur affinity metal is a metal having a strong reactivity with oxygen, it easily reacts with oxygen in the atmosphere and oxidizes. Therefore, if it takes a long time to add the sulfur-affinity metal to the oxygen-free copper melt and actually put it into the casting, it takes longer time for the sulfur-affinity metal to be exposed to the atmosphere. It becomes an addition loss. Therefore, it is important to suppress the reaction between the sulfur affinity metal and oxygen in the atmosphere. In the manufacturing method according to the present embodiment, a desirable timing for adding the sulfur affinity metal to the molten copper is immediately before casting. Moreover, the addition form of a sulfur affinity metal may add the simple substance of a sulfur affinity metal directly, However, It is preferable to add what was alloyed with the copper base material. Thereby, as described above, oxidation of the sulfur affinity metal can be suppressed. In addition, variation in the amount of addition can be suppressed, and as a result, the accuracy of the content of sulfur-affinity metal can be increased.

  The copper material obtained by the above manufacturing method uses oxygen-free copper and has a softening temperature lower than that of an oxygen-free copper material manufactured by a conventional method (hereinafter referred to as a conventional copper material) (for example, Semi-softening temperature becomes 110 ° C. or lower). For this reason, the copper material of the present embodiment can be sufficiently annealed at a lower temperature. Therefore, when performing annealing annealing, the copper material of the present embodiment can be annealed at a lower temperature and in a shorter time than a conventional copper material. As a result, productivity of the copper material is improved, and energy required for manufacturing the copper material can be reduced.

  The copper material of the present embodiment is made of oxygen-free copper having excellent connection weldability, and its softening temperature is significantly lower than that of conventional copper materials. Is a copper material that is inexpensive and has a very high industrial value.

  As described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various other things are assumed.

  Next, although this invention is demonstrated based on an Example, this invention is not limited to this Example.

  Using an upcast continuous up-drawing continuous casting apparatus, a rough drawn wire made of oxygen-free copper and having a diameter of 8 mm was produced. The constituent material of the rough drawn wire is obtained by adding a sulfur-affinity metal at a predetermined ratio to an oxygen-free molten copper. The rough drawing wire was repeatedly subjected to cold surface reduction and annealing treatments as appropriate, and copper wires having a diameter of 0.5 mm were prepared (Sample 1 to Sample 18).

  In Sample 1, no sulfur-affinity metal was added.

  About samples 2-4, Ti was added as a sulfur affinity metal, respectively. Example 1 containing 0.003% by weight of Ti (Example 1), one containing 0.0003% by weight of Ti (Comparative Example 2), and one containing 0.06% by weight of Ti (Comparative) Example 3).

  For Samples 5 to 7, as a sulfur-affinity metal, a sample containing 0.003% by weight of Zr (Example 2), a sample containing 0.003% by weight of Fe (Example 3), Mg (Example 4) was obtained by adding 0.003% by weight.

  For samples 8 and 9, Ta was added as a sulfur-affinity metal. A sample containing 0.006% by weight of Ta was designated as (Example 5), and a product containing 0.04% by weight of Ta was designated as (Example 6).

  About samples 10-13, Ni was added as a sulfur affinity metal, respectively. A sample containing 0.0005% by weight of Ni (Example 7), a sample containing 0.005% by weight of Ni (Example 8), and a sample containing 0.01% by weight of Ni (implemented) Example 9), 0.05% by weight of Ni was designated as (Example 10).

  For Samples 14 to 17, a total of 2 types of Ni + α were added as sulfur-affinity metals. Example 11 containing 0.01Ni + 0.001Ti (% by weight), Example 12 containing 0.01Ni + 0.001V (% by weight), and containing 0.01Ni + 0.0005Ca (% by weight) What was made into (Example 13) and what made 0.01Ni + 0.001Mn (weight%) contain were made into (Example 14).

  Sample 18 produced a rough drawn wire φ8 mm made of tough pitch copper using a continuous casting and rolling method (SCR method). The constituent material of the rough drawn wire is obtained by adding 0.003% by weight of Ti, which is a sulfur-affinity metal, to the oxygen-free molten copper. This rough drawing wire is subjected to cold wire drawing and annealing treatment as appropriate to produce a copper wire having a diameter of 0.5 mm (conventional example 1).

  A softening test was performed using the copper wires of Examples 1 to 14, Comparative Examples 1 to 3, and Conventional Example 1, and the softening characteristics were evaluated. The results are shown in Table 1. Here, the evaluation of the softening characteristics was performed using the semi-softening temperature. Moreover, about each copper wire, the complete annealing process (process which softens until the intensity | strength of a copper wire does not fall any more) was performed, and the electrical conductivity measurement was also implemented.

  As shown in Table 1, each of the copper wires of Examples 1 to 14 has a sulfur-affinity metal content in the range of 0.0004 to 0.055% by weight, and the production of the copper wire according to the present invention. I was satisfied with the method. The semi-softening temperature of each copper wire of Examples 1 to 14 is 110 ° C. or less (66 to 108 ° C.), and the semi-softening temperature (135 ° C.) of each copper wire of Comparative Example 1 to which no sulfur-affinity metal is added. ), The semi-softening temperature also decreased at 25 ° C. or higher (about 27 to 69 ° C.). When the copper wires of Examples 9 and 11 to 14 were compared with each other, one semi-softening temperature was further reduced except for Example 13 (Ca addition) when Ni was added as a sulfur-affinity metal in addition to Ni. However, when Examples 9 and 13 are compared, there is no significant increase in the semi-softening temperature. Therefore, if it is a small amount, Ca that can be expected to improve the heat resistance may be added.

  On the other hand, the copper wire of Comparative Example 2 has a sulfur-affinity metal content of too low, 0.0003% by weight, so that no effect of lowering the softening temperature of the copper wire can be obtained, and the semi-softening temperature is It was 135 ° C. exactly the same as the copper wire of Comparative Example 1.

  Further, the copper wire of Comparative Example 3 has a sulfur-affinity metal content of 0.06% by weight, so that the softening temperature of the copper wire is raised conversely, and the semi-softening temperature is no sulfur-affinity metal. The temperature was about 231 ° C., which was about 100 ° C. higher than the case of addition (copper wire of Comparative Example 1).

  The electrical conductivity of each copper wire after the complete annealing treatment was 101.5% IACS or higher in Examples 1 to 14 having a low semi-softening temperature, but Comparative Examples 1 to 3 having a high semi-softening temperature were 101 Less than 5% IACS. Moreover, when the copper wire which is a sample and the front-end | tips of a copper wire were faced | matched and TIG-welded, in the case of the copper wire of a prior art example, the void was formed in copper, Examples 1-14 of this invention, and In Comparative Examples 1 to 3, no void was observed.

  From the above, a sulfur-affinity metal is added to the oxygen-free copper melt, which is a constituent material of the rough drawing wire, at a predetermined ratio, and the oxygen-free copper melt is supplied to the upward pulling continuous casting apparatus to produce a copper wire. Thus, it was confirmed that the softening temperature of the copper wire can be greatly reduced. Furthermore, no voids were generated in the conductor during welding, and connection reliability was greatly improved.

Claims (2)

In a method for producing a copper material directly from an oxygen-free copper melt using an upward pulling continuous casting apparatus,
At least one metal or alloy selected from Ti, Zr, V, Ta, Fe, Ca, Mg, or Ni is added to the oxygen-free copper molten metal stored in the molten metal storage means of the upward pulling continuous casting apparatus. And the ratio of this metal or alloy contained in an oxygen free molten copper is adjusted to 0.0004 to 0.055 weight%, The manufacturing method of the copper material characterized by the above-mentioned.   The copper material manufactured using the manufacturing method of Claim 1, Comprising: Semi-softening temperature is 110 degrees C or less, The copper material characterized by the above-mentioned.