JPWO2018154962A1 - Copper wire manufacturing method - Google Patents

Abstract

A method for producing a copper wire comprising a copper wire made of copper or a copper alloy, wherein a wire diameter of a slab pulled up from a mold is 8 mm or more, and a ratio of a pulling cycle of the slab to the wire diameter is 0. A preparatory step of preparing an upcast material obtained by performing an updrawing casting method so as to obtain a wire drawing material having a workability of 40% or more. A method for producing a copper wire comprising a wire step.

Description

  The present invention relates to a method for producing a copper wire. This application claims priority based on Japanese Patent Application No. 2017-032700 filed on Feb. 23, 2017, and incorporates all the description content described in the above Japanese application.

  Patent Document 1 discloses a method of subjecting an upcast material obtained by a top casting method to conform extrusion as a method for producing a copper wire material having excellent surface properties.

Japanese Patent Laying-Open No. 2015-28903

  Conform extrusion is a molding method in which a material (upcast material) is inserted into the groove of a rotating wheel, and the material is plastically flowed by heat generated by friction heat between the wheel and the material, and extruded from a die. The wire speed tends to be slower than the wire drawing.

  Moreover, although conform extrusion can manufacture a long material continuously, it is difficult to make a long material with a comparatively small diameter. Therefore, in patent document 1, wire drawing is given to the extruded material obtained by performing conform extrusion.

The method for producing a copper wire according to the present disclosure is as follows:
A copper wire manufacturing method for obtaining a copper wire made of copper or a copper alloy,
Up-cast obtained by performing the up-casting method so that the wire diameter of the slab pulled upward from the mold is 8 mm or more, and the ratio of the pulling cycle of the slab to the wire diameter is 0.5 or less. A preparation process for preparing the material;
A wire drawing step of obtaining a wire drawing material by subjecting the upcast material to a wire drawing process at a working degree of 40% or more.

[Problems to be solved by this disclosure]
An object of the present invention is to provide a method for producing a copper wire that is excellent in surface properties and can efficiently obtain a copper wire suitable for a conductor material.

[The invention's effect]
The manufacturing method of the said copper wire is excellent in surface property, and can obtain efficiently the copper wire suitable for the raw material of a conductor.

[Description of Embodiment of the Present Invention]
The top casting method can produce a wire having a lower oxygen concentration (for example, an oxygen-free copper wire). However, the upcast material obtained by the top casting method has poor surface properties. In the top casting method, the slab can be lifted intermittently at very small intervals to suppress the occurrence of squeezing (galling) between the mold and the slab or to suppress instability of the casting. is there. Therefore, the present inventors have paid attention to the fact that, as the surface property of the upcast material, when the slab is pulled upward from the mold, the crystal structure periodically changes depending on the pulling cycle. Here, the “pulling cycle” refers to a cycle of the pulling length when the slab is pulled intermittently at a constant interval. That is, in the intermittent pulling process of the slab, it refers to the distance at which the slab is pulled up after the slab pulling is interrupted until the next pulling interruption. “Crystal structure changes periodically” means that the slab is pulled up intermittently at regular intervals, and the crystal structure is divided between the area where the pulling is continued and the area where the pulling is interrupted. Say to change.

  When the period interval of the crystal structure of the upcast material is large, that is, when the pulling cycle of the slab is large, when the upcast material is drawn, the degree of work is low (for example, less than 40%) Cracks and breaks occur. The reason for this is that a periodic change occurs in the crystal structure of the upcast material during casting by the top casting method. This is because meandering occurs when the upcast material is fed out. When meandering occurs in the up-cast material, large line blurring occurs when the wire drawing die passes, and deep scratches occur due to rubbing with the capstan. Therefore, as a result of investigating means for making the crystal structure of the upcast material uniform, the period interval of the crystal structure of the upcast material is reduced, and the upcast material is stretched at a high workability (working degree of 40% or more). The knowledge that it is preferable to perform wire processing has been obtained, and the present invention has been completed. The contents of the embodiments of the present invention will be listed and described below.

(1) A method for producing a copper wire according to an embodiment of the present invention includes:
A copper wire manufacturing method for obtaining a copper wire made of copper or a copper alloy,
Up-cast obtained by performing the up-casting method so that the wire diameter of the slab pulled upward from the mold is 8 mm or more, and the ratio of the pulling cycle of the slab to the wire diameter is 0.5 or less. A preparation process for preparing the material;
A wire drawing step of obtaining a wire drawing material by subjecting the upcast material to a wire drawing process at a working degree of 40% or more.

  The term “copper wire” as used herein refers to a wire made of copper or a copper alloy and subjected to various processes that require wire drawing on an upcast material obtained by performing a top casting process. Therefore, as a copper wire, it may be called a wire drawing material, a skinning material, a heat treatment material, etc. depending on the manufacturing stage.

In the method for producing a copper wire according to the embodiment, by periodically drawing the upcast material at a high workability of 40% or more, the crystal structure of the upcast material periodically changed is leveled, and the upcast material Meandering caused by the periodicity of the crystal structure can be corrected. In particular, in the upcast material, the ratio of the pulling cycle L (mm) to the wire diameter D (mm) of the slab: L / D is 0.5 or less, so that the cycle interval of the crystal structure of the upcast material is shortened. It is easy to correct the meandering of the wire that may occur during wire drawing. Moreover, when the wire diameter of the slab (the wire diameter of the upcast material) is 8 mm or more, the degree of drawing of the upcast material can be sufficiently increased. As mentioned above, the manufacturing method of the copper wire of the embodiment performs up-casting by subjecting the up-cast material having a large wire diameter D and a short periodic interval of the crystal structure to a drawing process at a high workability of 40% or more. Periodic changes in the crystal structure of the material can be substantially eliminated and a substantially orthogonal state can be achieved.
Therefore, the manufacturing method of the said copper wire can reduce the surface defects, such as a crack which may arise at the time of wire drawing, is excellent in surface property, and can obtain easily the copper wire suitable for the raw material of a conductor.

  (2) As one form of the said manufacturing method of a copper wire, providing the skinning process which skins the said wire drawing material and obtains a skinning material is mentioned.

  By stripping the wire drawing material, surface defects such as scratches generated in the wire drawing material at the time of wire drawing can be removed, and a copper wire material having better surface properties can be obtained.

  (3) As one form of the manufacturing method of the said copper wire, providing the heat processing process which heat-processes to the said wire drawing material and obtains a heat processing material is mentioned.

  By subjecting the wire drawing material to heat treatment, the crystal structure of the wire drawing material can be recrystallized, and the crystal structure can be made uniform easily. Moreover, the drawability can be improved.

  (4) As one form of the manufacturing method of the said copper wire provided with a skinning process, the heat processing process which heat-processes to the intermediate | middle wire which performed the wire drawing process of 80% or less of the said skinning material, and obtains heat processing material Is provided.

  According to the said form, it is easy to make the crystal structure of a peeling material more uniform, and a wire drawing property can be improved more.

[Details of the embodiment of the present invention]
Details of the embodiment of the present invention will be described below. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to the claim are included.

[Method for producing copper wire]
The method for producing a copper wire according to the embodiment includes a preparation step of preparing an upcast material obtained by performing a top casting method, and a wire drawing step of obtaining a wire drawing material by subjecting the prepared upcast material to wire drawing processing. Is provided. The copper wire manufacturing method of the embodiment prepares an upcast material having a large wire diameter and a short period interval of the crystal structure, and subjecting this upcast material to wire drawing at a high workability of 40% or more. One of the features. Moreover, the manufacturing method of the copper wire of embodiment is equipped with the peeling process which gives a skinning material by skinning the said wire drawing material as needed. Furthermore, the manufacturing method of the copper wire material of embodiment is equipped with the heat processing process which heat-processes the said wire drawing material as needed, and obtains a heat processing material. Hereinafter, each process will be described in detail.

≪Preparation process≫
The preparation step is a step of preparing an upcast material obtained by performing the top casting method. A commercially available or known top casting machine can be used for casting by the top casting method. The upcast material has a wire diameter D of the cast slab pulled upward from the mold of 8 mm or more, and the ratio of the slab lifting cycle L to the wire diameter D: L / D is 0.5 or less. It was obtained by performing the draw casting method.

  The wire diameter D of the upcast material is 8 mm or more. The wire diameter D referred to here is an equivalent area circle equivalent diameter of the upcast material, and is a diameter of a circle having the same area as the cross-sectional area in the cross section of the upcast material. The upcast material is typically a round wire having a circular cross-sectional shape. The larger the wire diameter D of the upcast material, the higher the degree of drawing can be achieved in the drawing step described later. Therefore, the wire diameter D of the upcast material is preferably 8.5 mm or more, more preferably 10 mm or more, 12 mm or more, 15 mm or more, and particularly preferably 16 mm or more.

  The up-cast material can be obtained, for example, by pulling up a cast piece from a 1100-1200 ° C. molten copper at a pulling speed of 0.1-4 m / min and pulling it upward from the mold. The period L (mm) of the pulling length at the time of pulling up the slab is set so that the ratio L / D to the wire diameter D (mm) of the upcast material is 0.5 or less. It can be mentioned that the ratio L / D is constant regardless of the pulling speed within the pulling speed range. Moreover, the stop time between pulling at the time of pulling up is 0.01 to 60 sec. Here, the “pulling speed” means “from the start of pulling up to the next pulling up” when repeatedly raising and stopping the slab. It means the average speed in a series of operations “until completion of time to stop and hold in the stopped state”.

  In the upcast material obtained by the top casting method, the crystal structure periodically changes in the longitudinal direction as the slab is pulled up. This periodic change of the crystal structure can be seen by observing the longitudinal section of the upcast material with a microscope. This periodic change in the crystal structure causes meandering in the upcast material. If meandering occurs in the upcast material, it causes surface defects such as scratches that may occur during wire drawing in the wire drawing step described later. Specifically, a large line blur occurs when the wire drawing die passes due to meandering, and a deep flaw occurs due to rubbing with the capstan. As the slab pulling period L is shorter, the period interval of the crystal structure of the obtained upcast material can be shortened and the meandering can be reduced, so that the linear blur can be reduced and the load caused by rubbing with the capstan can be reduced. . Moreover, it is easy to correct the meandering of the upcast material at the time of wire drawing. Therefore, it is preferable that the ratio L / D with respect to the wire diameter D of an upcast material is 0.40 or less, further 0.35 or less, and especially 0.30 or less. On the other hand, if the pulling cycle L is too short, the productivity may decrease, so L / D is preferably 0.1 or more, more preferably 0.12 or more, and particularly preferably 0.15 or more. When L / D is 0.1 or more, disconnection due to instability of casting can hardly occur.

  The constituent material of the upcast material is so-called pure copper. Pure copper includes oxygen-free copper (containing 99.95% by mass or more of Cu, with the balance being inevitable impurities (preferably the total content of inevitable impurities is 0.03% by mass or less)). The smaller the oxygen content in the oxygen-free copper, the better the conductivity, so 0.005 mass% (50 mass ppm) or less, and more preferably 0.002 mass% (20 mass ppm) or less. The oxygen content can be adjusted by refining at the time of melting or by adjusting the casting atmosphere. The top casting method makes it easy to adjust the casting atmosphere and to reduce the oxygen content.

≪Wire drawing process≫
The wire drawing step is a step of obtaining a wire drawing material by subjecting the upcast material prepared in the preparation step to wire drawing at a working degree of 40% or more. For wire drawing, a wire drawing die is typically used.

  As a result of the study by the present inventors, when the upcast material is drawn at a low degree of processing (for example, a degree of processing of less than 40%) and the drawn material is stripped, scratches and the like generated in the wire Although surface defects can be removed to some extent, it was difficult to correct the meander of the upcast material. This is considered to be due to the fact that the periodic change of the crystal structure remains because the degree of wire drawing is low. Therefore, even if the surface defect is removed by skinning, if the wire remains meandering, scratches are newly generated due to subsequent rubbing with the capstan. Therefore, when the upcast material was subjected to wire drawing at a high workability of 40% or more, and the wire material was peeled, surface defects such as scratches generated in the wire drawing material could be removed, and the wire meandering could be performed. I was able to correct it. This is considered to be due to the fact that the periodic change of the crystal structure was substantially lost during wire drawing because of the high degree of wire drawing. Therefore, the upcast material does not meander in the subsequent manufacturing process, and it is possible to suppress a new scratch from being generated on the wire drawing material due to rubbing with the capstan.

  The wire drawing can be performed once or a plurality of times. When the wire drawing is performed once, the degree of processing at one time is 40% or more, and when the wire drawing is performed a plurality of times, the total degree of processing at multiple times is 40% or more. The higher the degree of wire drawing, the easier it is to eliminate periodic changes in the crystal structure of the wire. Therefore, it is preferable that the wire drawing workability (total workability in the case of multiple times) is 50% or more, more preferably 55% or more, 60% or more, 65% or more, and particularly preferably 70% or more.

≪Skinning process≫
The skinning process is a process of obtaining a skinning material by skinning the wire drawing material obtained in the wire drawing process. By performing skinning, surface defects such as scratches generated at the time of wire drawing can be removed, and a copper wire material having better surface properties can be obtained. For skin peeling, a skin peeling die is typically used.

  Skinning can be applied once or multiple times. When the skinning is performed once, the yield is easily reduced. When skinning is performed a plurality of times, defects such as scratches can be removed satisfactorily. The skinning thickness (removed thickness) can be appropriately selected according to the size of the material, the state of defects, and the like. For example, when the material is a wire having a diameter of about 5 mm to 15 mm, the skinning thickness (total thickness in the case of performing multiple times) is preferably 20 μm to 150 μm, and more preferably 40 μm to 100 μm. By making the skinning thickness 20 μm or more (preferably 40 μm or more) for a wire having a size in the above range, surface defects can be sufficiently removed, and 150 μm or less (preferably 100 μm or less). Yield reduction can be suppressed. In addition, the diameter of the wire after skinning is (the diameter of the raw material before skinning−the skinning thickness × 2).

  Since the wire that has been drawn at a high degree of processing of 40% or more is hardened by work hardening, it is easy to peel off by peeling off the wire, and defects such as mussels It is easy to suppress the occurrence of

≪Heat treatment process≫
The heat treatment step is a step of obtaining a heat treatment material by subjecting the wire drawing material obtained in the wire drawing step to a heat treatment. By performing the heat treatment, the crystal structure can be recrystallized, and the crystal structure can be easily made uniform. The heat treatment is preferably performed on a skinned material that has been skinned. In particular, the heat treatment is preferably performed on an intermediate wire that has been drawn at a degree of processing of 80% or less of the stripping material. This is because, in order to reduce defects such as scratches, it is desired to make the crystal structure uniform while the degree of work is low, but if the degree of work is too low, it is difficult for recrystallization to proceed uniformly. Therefore, it is preferable to perform the heat treatment on the intermediate wire having a processing degree of 78% or less, further 75% or less, and particularly 73% or less for the skinning material.

  The heat treatment conditions include a heating temperature of 200 ° C. or higher and 550 ° C. or lower, 250 ° C. or higher and 500 ° C. or lower, particularly 300 ° C. or higher and 450 ° C. or lower. Further, the holding time may be 0.2 seconds or more and 10 hours or less, more preferably 30 seconds or more and 8 hours or less, and particularly preferably 60 seconds or more and 5 hours or less. Either a batch process or a continuous process may be used for the heat treatment. When continuous treatment is performed, heat treatment can be performed on a long wire, and the holding time can be shortened.

≪Others≫
A copper deformed wire can be produced by rolling the copper wire to a rolling process for changing the shape. For example, in the rolling step, a copper flat wire can be produced by rolling the copper wire. The rolling conditions can be appropriately selected so as to obtain a copper deformed wire having a desired thickness, width, cross-sectional area, outer shape, and the like. Since the upcast material having a relatively large wire diameter of 8 mm or more is used, a copper deformed wire material such as a rectangular wire having a cross-sectional area of 2 mm ² or more can be obtained in the rolling process. Without performing this rolling step, the cross-sectional shape having a cross-sectional area of 2 mm ² or more can be made into a circular round wire by a wire drawing process. In addition, as said copper wire material, the drawn material which gave the wire drawing process to the upcast material, the peeling material which gave the skinning to the drawing material, the heat processing material which heat-treated the drawing material or the peeling material, and the peeling material Or the 2nd wire drawing material which performed the wire drawing process further to the heat processing material is mentioned.

  The said copper wire (copper wire of the final wire diameter) is made into a conductor, The coating process which forms an insulation coating on the surface of this conductor can be provided, and a covering copper wire can be manufactured. For the formation of the insulating coating, for example, a known technique used for manufacturing a known enameled wire can be used. Typically, the step of applying a resin constituting the insulating coating on the surface of the conductor, and the step of passing the applied conductor through a baking furnace, drying and curing the resin, and baking the resin are performed. It may be repeated one or more times until the thickness is reached. In addition, an insulating coating can be formed on the surface of the conductor by extrusion coating.

[Test Example 1]
Wires made of oxygen-free copper were produced under various conditions, and the surface state of the obtained wires was examined.

  Pure copper (Cu: 99.95 mass% or more and oxygen: 0.001 mass% or less oxygen-free copper) was prepared as a raw material to prepare a molten metal. The prepared molten metal was set to the pulling cycle L (mm), the pulling speed (m / min), and the stop time (sec) shown in Table 1, and subjected to top casting, and the wire diameter D (diameter, mm)) was prepared (preparation step: sample No. 1-1 to sample No. 1-6, sample No. 1-11 to sample No. 1-14). Table 1 also shows the ratio (L / D) of the pulling cycle L to the wire diameter D of the obtained upcast material.

  Sample No. For samples other than 1-14, the above-mentioned upcast material was drawn at a processing degree α shown in Table 1 to produce a drawn material having a wire diameter (diameter, mm) shown in Table 1 (drawing step). .

  The obtained sample No. Skinning materials were produced by applying skinning thickness (μm) shown in Table 1 to wire drawing materials other than 1-14 (skinning process).

Sample No. 1-1, sample no. 1-2, Sample No. 1-4 to Sample No. 1-6, Sample No. 1-11-Sample No. In No. 1-13, a heat treatment of 450 ° C. × 0.2 seconds was performed on the intermediate wire that had been subjected to wire drawing with a processing degree β shown in Table 1 as the degree of processing for the skinning material (heat treatment step). Sample No. In No. 1-14, an intermediate wire (wire diameter: 5 mm) in the middle of wire drawing was subjected to heat treatment at 450 ° C. × 0.2 seconds. Thereafter, all samples were subjected to wire drawing so that the total degree of processing shown in Table 1 was achieved, and final wires (copper wires) having a cross-sectional area (mm ² ) shown in Table 1 were produced.

  A conductor was produced from the obtained final wire, and a coated copper wire provided with this conductor was produced. As the surface properties of the wire, the state of occurrence of the swollen coating was examined using a commercially available flaw detector on the produced coated copper wire. If a surface defect such as a scratch is generated in the wire, the defective portion becomes an air reservoir and a defect such as a swelling of the coating occurs. Therefore, the surface property of the wire can be understood by examining the state of occurrence of the swelling of the coating. That is, a wire with less occurrence of blistering is excellent in surface properties. Regarding the state of occurrence of blistering of the coating, a commercially available flaw detection device is installed in addition to the coating forming facility, and a long wire rod (in this case, a coated copper wire) is run, so that the coating is continuously formed and scratched. An in-line method that can count the number of occurrences of blisters was used. The results are shown in Table 1 as the occurrence points per 100 kg.

  As shown in Table 1, an upcast material having a wire diameter D of 8 mm or more and a short pulling cycle L (L / D is as small as 0.5 or less) is drawn at a working degree α of 40% or more. Sample No. applied 1-1 to Sample No. No. 1-6 has a defect (occurrence of swelling of the coating per 100 kg) of 2.0 or less. 1-11-Sample No. It is low compared with 1-14, and it can be seen that the surface properties are excellent. This is considered to be due to the fact that the periodic change of the crystal structure formed along with the pulling cycle during the top-drawing casting was substantially eliminated during the wire drawing because of the high degree of wire drawing. In particular, it is considered that the pulling cycle L is short, the period interval of the crystal structure of the upcast material can be shortened, and the meandering accompanying the crystal structure during wire drawing is corrected.

  Furthermore, the sample No. 1 was subjected to heat treatment on the intermediate wire in the middle of wire drawing until reaching the final wire diameter. 1-1, sample no. 1-2, Sample No. 1-4 to 1-6 have a defect of 1.3 or less, and are further excellent in surface properties. This is considered to be because the crystal structure can be recrystallized by heat treatment and the crystal structure can be made uniform. In particular, sample No. 2 was obtained by heat-treating an intermediate wire having a degree of processing of 80% or less with respect to the stripping material. 1-1, sample no. 1-2, Sample No. 1-4, Sample No. It can be seen that 1-6 has a defect of 1.0 or less and is very excellent in surface properties. This is considered to be due to the fact that the wire drawing was improved by performing wire drawing on the uniform crystal structure. In addition, after performing the wire drawing at a working degree α of 81% (80% or more), the sample No. 1 was subjected to heat treatment on the skinned material subjected to the skinning. It can be seen that 1-6 has a defect of 0.3 or less and is most excellent in surface properties.

  On the other hand, sample no. 1-11, sample No. 1 with a long pulling cycle L (L / D is large as over 0.5) 1-12, the upcast material before skinning was drawn, but the degree of processing was low (less than 40%). Sample No. 1-13, where the upcast material was not drawn. 1-14 had large defects and poor surface properties. This is because the periodic change of the crystal structure formed in the upcast material along with the pulling cycle during top casting is not lost during wire drawing, and the meandering of the upcast material cannot be corrected. It can be considered that scratches were generated due to rubbing with the capstan or the like during the drawing to the diameter.

Claims (4)

A copper wire manufacturing method for obtaining a copper wire made of copper or a copper alloy,
Up-cast obtained by performing the up-casting method so that the wire diameter of the slab pulled upward from the mold is 8 mm or more, and the ratio of the pulling cycle of the slab to the wire diameter is 0.5 or less. A preparation process for preparing the material;
A copper wire manufacturing method comprising: a wire drawing step of drawing the up cast material at a workability of 40% or more to obtain a wire drawing material.   The manufacturing method of the copper wire of Claim 1 provided with the skinning process which gives a skinning material by skinning the said wire drawing material.   The manufacturing method of the copper wire of Claim 1 or Claim 2 provided with the heat processing process which heat-processes the said wire drawing material and obtains a heat processing material.   The manufacturing method of the copper wire of Claim 2 provided with the heat processing process which heat-processes to the intermediate | middle wire which performed the wire drawing process of 80% or less of the stripping material, and obtains a heat processing material.