JP2018158344A - Copper casting material manufacturing method and copper rough drawing wire manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a copper cast stock and a method for producing a copper rough drawing wire in which defects, such as cracks, less occur on a surface of the copper rough drawing wire.SOLUTION: A method for producing a copper cast stock includes a melting process that obtains a molten copper by melting a raw material copper in a fusion furnace, and a continuous casting process that obtains a copper cast stock by continuously casting the molten copper. In the continuous casting process, continuous casting is performed such that the ratio L/Lof an average length Lof a columnar crystal formed in a thickness direction of the copper cast stock obtained when the molten copper is continuously cast at a temperature T(°C) to a length Lof the columnar crystal formed in a width direction of the copper cast stock satisfies the following formula (1). L/L≤(1580-T)/300...(1).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a copper casting material used as a conductor such as an electric wire or cable, and a method for producing a copper rough wire.

  Copper wires are used as conductors in electric wires and cables wired to railway vehicles and the like, enameled wires that constitute motor coils mounted in automobiles and the like. Many of these copper wires are manufactured by continuously casting and rolling copper rough wires made of oxygen-free copper, tough pitch copper, etc., and then cold drawing and heat treatment (annealing treatment) of the obtained copper rough wires Is obtained by applying

  When manufacturing copper roughing wire, molten copper obtained by melting raw copper such as electric copper in a melting furnace is supplied to a belt and wheel continuous casting machine via a transfer rod and holding furnace. A cast copper material is obtained by continuously casting the supplied molten copper. And the copper roughing wire which has a predetermined | prescribed outer diameter is manufactured by further hot-rolling and cooling the obtained copper cast material. In addition, when manufacturing a copper rough wire, the continuous casting rolling method in which each process of melt | dissolution of raw material copper, continuous casting, and hot rolling is continued is used (for example, refer patent document 1).

JP 2010-234442 A

  When manufacturing a copper casting material by continuous casting, the molten copper supplied in the mold in the molten state is cooled by a water-cooled mold. As a result, the molten copper in the mold is solidified at the contact surface with the mold to produce a solidified layer (hereinafter also referred to as a solidified shell). From this solidified shell to the inside, there is unsolidified molten copper on the upstream side of the mold, but this unsolidified molten copper is solidified by being cooled while being supplied to the downstream side of the mold. In this way, the molten copper supplied to the mold is completely solidified to produce a cast material.

  At this time, if the molten copper is not uniformly cooled in the mold, the thickness of the solidified shell is not uniform. The solidified shell is subjected to stress due to shrinkage and deformation generated in the solidified shell during cooling. In the initial stage of solidification of the solidified shell, this stress is concentrated on the thinned portion of the solidified shell. Due to this stress, cracks occur on the surface of the thinned portion of the solidified shell.

  The cracks on the surface of the solidified shell expand due to external forces such as subsequent thermal stress in the continuous casting process, bending stress and straightening stress of the continuous casting machine, and large cracks are generated on the surface of the copper cast material. The crack existing in the copper casting material becomes a surface defect in the next hot rolling step, and defects such as scratches and cracks are generated on the surface of the copper rough drawing wire. For this reason, it is necessary to prevent the surface of the copper casting material from being cracked at the stage of producing the copper casting material.

  Accordingly, an object of the present invention is to provide a method for producing a copper casting material in which defects such as cracks are unlikely to occur on the surface of the copper rough wire, and a method for producing a copper rough wire.

  In order to achieve the above object, one aspect of the present invention provides a method for producing a copper casting material according to the following [1] to [3] and a method for producing a copper rough wire according to the following [4] to [5]. .

[1] A melting step of melting raw material copper in a melting furnace to obtain molten copper, and a continuous casting step of obtaining a copper casting material by continuously casting the molten copper. In the continuous casting step, The average length L ₁ of columnar crystals formed in the thickness direction of the copper cast material obtained when continuously casting copper at a temperature T (° C.) and the columnar crystals formed in the width direction of the copper cast material A method for producing a cast copper material, characterized in that continuous casting is performed so that a ratio L ₁ / L ₂ to a length L ₂ of the above satisfies the following formula (1):
L ₁ / L ₂ ≦ (1580−T) / 300 (1)

[2] The method for producing a copper cast material according to [1], wherein a ratio L ₁ / L ₂ between the length L ₁ and the length L ₂ is 1.0 or more and 1.6 or less.

[3] The method for producing a copper casting material according to any one of the above [1] or [2], wherein the temperature T of the molten copper is 1090 ° C. or more and 1200 ° C. or less.

[4] A melting step of melting raw material copper in a melting furnace to obtain molten copper, a continuous casting step of continuously casting the molten copper to obtain a copper cast material, and hot hot rolling of the copper cast material wherein the rolling step, the said at continuous casting process, the molten copper to said length L ₁ of the columnar crystal which is formed in the thickness direction of the copper cast material obtained when continuous casting at a temperature T (° C.) The copper cast material is continuously cast so that the ratio L ₁ / L ₂ with the length L ₂ of the columnar crystals formed in the width direction of the copper cast material satisfies the following expression (1): The manufacturing method of the copper rough drawing wire.
L ₁ / L ₂ ≦ (1580−T) / 300 (1)

[5] The method for producing a copper rough wire according to the above [4], wherein the hot rolling step hot-rolls the cast material at a temperature of 450 ° C. or higher and 950 ° C. or lower.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the copper casting material which hardly produces defects, such as a crack, in the surface of a copper rough drawing wire, and the manufacturing method of a copper rough drawing wire can be provided.

It is a schematic block diagram which shows the manufacturing apparatus of the copper casting material and copper rough drawing wire which concerns on one Embodiment of this invention. It is a cross-sectional photograph when the copper casting material which concerns on one Embodiment of this invention is observed from a casting direction. The relationship between the molten copper temperature at the time of continuously casting the copper casting material according to one embodiment of the present invention and the ratio of the columnar crystal lengths L ₁ and L ₂ of the copper casting material, and the surface of the obtained copper casting material It is a figure which shows the presence or absence of a crack of.

  The inventors of the present invention have confirmed that the higher the molten copper temperature during continuous casting, the larger the crystal grains on the surface of the obtained copper cast material, and the easier it is for the surface of the copper cast material to crack. Then, the present inventors pay attention to the relationship between the molten copper temperature during continuous casting and the length of the columnar crystals formed in the resulting copper casting material, and a uniform solidified shell is formed and the copper casting is performed. It has been found that there is a range where the occurrence of cracks on the surface of the material is suppressed. The present invention has been made based on this finding and is as follows.

[Copper cast material, copper roughing wire manufacturing equipment]
A copper casting material and a copper roughing wire manufacturing apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram illustrating a copper casting material and a copper roughing wire manufacturing apparatus according to the present embodiment.

  As shown in FIG. 1, a copper roughing wire manufacturing apparatus 10 according to the present embodiment is configured as a so-called belt-and-wheel continuous casting and rolling apparatus for continuously casting and rolling a copper alloy material. For example, a melting furnace 210, upper iron 220, holding furnace 230, lower iron 260, tundish 300, pouring nozzle 320, continuous casting machine 500, continuous rolling device 620, and coiler 640. .

  The melting furnace 210 is configured to heat and melt the raw material copper to generate the molten copper 110, and includes, for example, a furnace body and a burner provided at a lower portion of the furnace body. The raw copper is put into the furnace body and heated by a burner, whereby molten copper 110 is continuously generated. As the material of the raw material copper, for example, electrolytic copper made of pure copper such as tough pitch copper, oxygen-free copper, and high-purity copper can be used.

  The upper iron 220 is provided on the downstream side of the melting furnace 210, connects the melting furnace 210 and the holding furnace 230, and transfers the molten copper 110 generated in the melting furnace 210 to the holding furnace 230 on the downstream side. It is configured.

  The holding furnace 230 is provided on the downstream side of the upper iron 220, and is configured to heat and store the molten copper 110 transferred from the upper iron 220 at a predetermined temperature. The holding furnace 230 is configured to transfer a predetermined amount of the molten copper 110 to the lower iron 260 while maintaining the molten copper 110 at a predetermined temperature.

  The lower iron 260 is provided on the downstream side of the holding furnace 230 and is configured to transfer the molten copper 110 transferred from the holding furnace 230 to the tundish 300 on the downstream side.

  In addition, the apparatus from the upper iron 220 to the tundish 300 may be configured to continuously add a predetermined metal element to the molten copper 110 to be supplied. Examples of the metal element added to the molten copper 110 include tin (Sn), titanium (Ti), magnesium (Mg), aluminum (Al), calcium (Ca), and manganese (Mn). That is, preferably, at least one of these metal elements is added to the molten copper 110. These metal elements are added, for example so that it may be contained in molten copper at the density | concentration of 0.02 mass% or more and 10 mass% or less. The method for adding the metal element is not particularly limited, and for example, wire injection in which a wire made of a metal element is put into the molten copper 110 can be used.

  The tundish 300 is provided on the downstream side of the lower iron 260, temporarily stores the molten copper 110 transferred from the lower iron 260, and continuously supplies a predetermined amount of molten copper 110 to the continuous casting machine 500. It is configured to

  A pouring nozzle 320 for supplying the molten copper 110 to be stored to the continuous casting machine 500 is connected to the downstream side of the tundish 300. The pouring nozzle 320 is made of a refractory material such as silicon oxide, silicon carbide, silicon nitride or the like. The molten copper 110 accumulated in the tundish 300 is supplied to the continuous casting machine 500 through the pouring nozzle 320. An adjusting member for adjusting the supply amount of the molten copper 110 supplied to the continuous casting machine 500 via the pouring nozzle 320 may be provided in the vicinity of the opening of the pouring nozzle 320.

  The continuous casting machine 500 is configured to perform a so-called belt and wheel type continuous casting, and includes, for example, a wheel (or ring) 510 and a belt 520. Cylindrical wheel 510 has a groove having a predetermined cross-sectional shape on the outer periphery (for example, a groove having a quadrilateral cross-sectional shape). Further, the belt 520 is configured to move around the wheel 510 while contacting a part of the outer peripheral surface of the wheel 510. In the space formed between the groove portion of the wheel 510 and the belt 520, the molten copper 110 flowing out from the pouring nozzle 320 connected to the downstream side of the tundish 300 is injected. Further, the wheel 510 and the belt 520 are cooled by, for example, cooling water. By this cooling water, the molten copper 110 injected into the space formed between the groove portion of the wheel 510 and the belt 520 is cooled and solidified (solidified), and the cross-sectional shape when viewed from the casting direction is a quadrilateral. A rod-shaped copper casting material 120 made of is continuously cast.

When the copper casting material 120 is manufactured from the molten copper 110 supplied from the tundish 300 to the continuous casting machine 500, the copper casting material 120 having a quadrilateral cross-sectional shape is the molten copper 110 supplied to the continuous casting machine 500. Is formed in the width direction of the copper casting material 120 and the average length L ₁ of the columnar crystals formed in the thickness direction of the copper casting material 120 obtained when continuously cast at a temperature T (° C.). It is continuously cast so that the ratio L ₁ / L ₂ to the columnar crystal length L ₂ satisfies the following formula (1).
L ₁ / L ₂ ≦ (1580−T) / 300 (1)

At this time, the length ratio L ₁ / L ₂ of the columnar crystals formed on the copper casting 120 is preferably 1.0 or more and 1.6 or less, more preferably 1.2 or more and 1.5 or less. More preferably, it is 1.2 or more and 1.4 or less. By making the ratio L ₁ / L ₂ of the lengths of columnar crystals formed in the copper casting 120 within such a range, the thickness of the solidified shell formed in the mold can be made less likely to be uneven. it can. Therefore, the copper casting material 120 obtained by continuous casting is one in which the occurrence of cracks on the surface is suppressed. L ₁ is preferably 15 mm or more and 50 mm or less. Furthermore, the temperature T of the molten copper 110 supplied to the continuous casting machine 500 is preferably 1090 ° C. or higher and 1200 ° C. or lower, and more preferably 1120 ° C. or higher and 1160 ° C. or lower.

FIG. 2 is a cross-sectional photograph of the copper casting 120 according to an embodiment of the present invention when observed from the casting direction. The average length L ₁ of the columnar crystals formed in the thickness direction of the copper cast material 120 is the thickness of the cross section of the copper cast material 120 having a quadrilateral cross section as shown in FIG. The length L _1A of the columnar crystals from the position of the boundary (boundary 121a) formed by colliding columnar crystals formed along the direction to the position of each side 122 of the opposite side arranged in the thickness direction, and It shows that L _1B is an average length (L ₁ = (L _1A + L _1B ) / 2). The length L _{2 of the} columnar crystals formed in the width direction of the copper casting 120 is a columnar crystal formed along the thickness direction of the cross section in the copper casting 120 having a quadrilateral cross-sectional shape. Is the position of the boundary (boundary 121b) formed by the collision of the columnar crystals formed along the width direction and the opposite side disposed in the width direction from the position (intersection 123) intersecting the boundary 121a The length of the cast crystal up to the position of each side 122b. In addition, each length (L _1A , L _1B , L ₂ ) of the cross section of the copper cast material 120 was obtained by polishing and etching the cross section of the obtained copper cast material 120. Later, it can be obtained by directly applying a scale. Alternatively, a cross-sectional photograph may be taken with a microscope and measured using a length measurement function.

  The continuous rolling device 620 is provided on the downstream side (casting material discharge side) of the continuous casting machine 500 and continuously heats the copper casting material 120 transferred from the continuous casting machine 500 at a temperature of, for example, 450 ° C. or more and 950 ° C. or less. It is configured to be hot rolled. By rolling the copper casting 120, a rough copper wire 130 having a predetermined outer diameter is formed.

  The coiler 640 is provided on the downstream side (copper rough drawing wire discharge side) of the continuous rolling device 620 and is configured to wind up the copper rough drawing wire 130 transferred from the continuous rolling device 620.

[Copper casting material, copper roughing wire manufacturing method]
Next, a method for manufacturing a copper cast material and a copper rough wire using the above-described copper cast material and copper rough wire manufacturing apparatus 10 will be described.

  The manufacturing method of the copper casting material and copper rough drawing wire of this embodiment has a melting process, a tundish storage process, a molten copper outflow process, a continuous casting process, and a continuous rolling process. These steps are not performed discretely but continuously as a series of steps.

(Melting process)
First, raw copper is put into the furnace body of the melting furnace 210. For example, electrolytic copper made of pure copper such as tough pitch copper, oxygen-free copper, and high-purity copper is charged as raw material copper into the melting furnace 210 heated to 1100 ° C. or higher and 1320 ° C. or lower. Then, the furnace body is heated with a burner. Thereby, the molten copper 110 is produced | generated continuously.

  The molten copper 110 generated in the melting furnace 210 is transferred to the holding furnace 230 held at a predetermined temperature via the upper iron 220.

(Tundish storage process)
Next, the molten copper 110 is transferred from the holding furnace 230 to the tundish 300 via the lower iron 260. Thereby, the molten copper 110 is temporarily stored in the tundish 300.

  For example, tin (Sn), titanium (Ti), magnesium (Mg), aluminum (Al), calcium (Ca), manganese (Mn) with respect to the molten copper 110 between the upper iron 220 and the tundish 300. ) And the like may be continuously added. At this time, inclusions (eg, titanium, magnesium oxide, nitride, carbide, sulfide, etc.) containing metal elements (eg, titanium, magnesium, etc.) are generated in the molten copper 110. In addition, it is preferable that these metal elements are added so that it may be contained in molten copper with the density | concentration of 0.02 mass% or more and 10 mass% or less, for example.

(Mold copper outflow process)
Next, the molten copper 110 is caused to flow from the tundish 300 to the continuous casting machine 500 via the pouring nozzle 320.

(Continuous casting process)
Next, the molten copper 110 that has flowed out of the tundish 300 via the pouring nozzle 320 is formed between the groove portion of the wheel 510 (for example, the groove portion having a quadrilateral cross section) and the belt 520 in the continuous casting machine 500. Inject into the space to be. Then, the belt 520 is rotated while contacting a part of the outer peripheral surface of the wheel 510. At this time, the wheel 510 and the belt 520 are cooled to the cooling water. Thereby, the molten copper 110 is cooled and solidified, and the rod-shaped copper casting material 120 having a quadrilateral cross section when viewed from the casting direction is continuously cast.

When the copper casting 120 is manufactured from the molten copper 110 supplied from the tundish 300 to the continuous casting machine 500, the copper casting 120 having a quadrilateral cross-sectional shape is the molten copper 120 supplied to the continuous casting machine 500. Is formed in the width direction of the copper casting material 120 and the average length L ₁ of the columnar crystals formed in the thickness direction of the copper casting material 120 obtained when continuously cast at a temperature T (° C.). It is continuously cast so that the ratio L ₁ / L ₂ to the columnar crystal length L ₂ satisfies the following formula (1).
L ₁ / L ₂ ≦ (1580−T) / 300 (1)

At this time, the ratio L ₁ / L _{2 between} the average length L ₁ of the columnar crystals formed in the thickness direction of the copper cast material 120 and the length L ₂ of the columnar crystals formed in the width direction of the copper cast material 120. Is preferably 1.0 or more and 1.6 or less, more preferably 1.2 or more and 1.5 or less, and still more preferably 1.2 or more and 1.4 or less. Also, columnar average length L ₁ of the crystals formed in the thickness direction of the copper cast material 120 is preferably 15mm or more 50mm or less. Furthermore, the temperature T of the molten copper 110 supplied to the continuous casting machine 500 is preferably 1090 ° C. or higher and 1200 ° C. or lower, more preferably 1120 ° C. or higher and 1160 ° C.

FIG. 3 shows the relationship between the molten copper temperature T during continuous casting of the copper casting 120 and the ratio between the columnar crystal lengths L ₁ and L ₂ of the copper casting, and the cracks in the surface of the resulting copper casting. It is a figure which shows the presence or absence of.

  In this continuous casting process, the copper casting 120 is continuously cast so as to satisfy the above formula (1), so that the thickness of the solidified shell formed in the mold can be made non-uniform. . Therefore, in the copper casting 120 obtained by continuous casting so as to satisfy the above formula (1), as shown in FIG. 3, the occurrence of surface cracks can be suppressed. More specifically, when the molten copper 110 supplied to the continuous casting machine 500 is cooled, a space gap is formed between the side surface of the mold. When this space gap is generated, cooling of the molten copper 110 existing in the mold may be weakened. Therefore, it is preferable to enhance the cooling of the side surface of the copper casting 120 by adjusting the thickness of the carbon soot applied to the surface of the mold. In this way, by strengthening the cooling of the molten copper 110 existing in the mold, columnar crystals are formed in the cast copper cast material 120 so as to satisfy the length ratio shown in the above formula (1). . Therefore, in the obtained copper casting material 120, the crack does not generate | occur | produce on the surface. In particular, in the copper casting 120 that is continuously cast so as to satisfy the above formula (1), it is possible not only to prevent the surface having the cross section in the thickness direction from being cracked, but also to crack the surface having the width direction. Can also be prevented. As a result, defects such as cracks and scratches due to cracks on the surface of the copper casting 120 are less likely to occur on the surface of the copper roughing wire 130 obtained through a continuous rolling process described later.

(Continuous rolling process)
Next, the copper casting material 120 transferred from the continuous casting machine 500 is continuously rolled at a temperature of, for example, 450 ° C. or more and 950 ° C. or less by the continuous rolling device 620. Thereby, the copper roughing wire 130 having a predetermined outer diameter (for example, an outer diameter of 30 mm or less) is formed. Then, the copper roughing wire 130 transferred from the continuous rolling apparatus 620 is wound up by the coiler 640. Thereby, the copper rough wire 130 is manufactured.

  In addition, the obtained copper rough drawing wire 130 is further subjected to wire drawing or rolling to reduce the outer diameter, and further subjected to heat treatment as necessary, as a copper wire for application to conductors such as electric wires. It may be molded.

  Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the invention.

  The embodiments and examples described above do not limit the invention according to the claims. It should be noted that not all combinations of features described in the embodiments and examples are necessarily essential to the means for solving the problems of the invention.

DESCRIPTION OF SYMBOLS 10 Copper roughing wire manufacturing apparatus 110 Molten copper 120 Copper casting material 130 Copper rough drawing wire 210 Melting furnace 220 Upper bar 230 Holding furnace 260 Lower bar 300 Tundish 320 Pouring nozzle 500 Continuous casting machine 510 Wheel 520 Belt 620 Continuous rolling apparatus 640 Coiler

Claims (5)

A melting step of obtaining raw copper by melting raw copper in a melting furnace;
A continuous casting step of obtaining a copper casting by continuously casting the molten copper;
Including
In the continuous casting step, an average length L ₁ of columnar crystals formed in the thickness direction of the copper cast material obtained when continuously casting the molten copper at a temperature T (° C.) and the copper cast material A method for producing a copper cast material, characterized by being continuously cast so that a ratio L ₁ / L ₂ to a length L _{2 of} columnar crystals formed in the width direction satisfies the following expression (1).
L ₁ / L ₂ ≦ (1580−T) / 300 (1) _{2. The} method for producing a copper cast material according to claim ₁ , wherein a ratio L ₁ / L ₂ between the length L ₁ and the length L ₂ is 1.0 or more and 1.6 or less.   The method for producing a copper casting material according to claim 1 or 2, wherein the temperature T of the molten copper is 1090 ° C or higher and 1200 ° C or lower. A melting step of obtaining raw copper by melting raw copper in a melting furnace;
A continuous casting step of obtaining a copper casting by continuously casting the molten copper;
A hot rolling step of hot rolling the copper casting material;
Including
In the continuous casting step, an average length L ₁ of columnar crystals formed in the thickness direction of the copper cast material obtained when continuously casting the molten copper at a temperature T (° C.) and the copper cast material The copper cast wire is characterized in that the copper cast material is continuously cast so that the ratio L ₁ / L ₂ to the length L ₂ of the columnar crystals formed in the width direction satisfies the following formula (1): Production method.
L ₁ / L ₂ ≦ (1580−T) / 300 (1)   The said hot rolling process is a manufacturing method of the copper roughing wire of Claim 4 which hot-rolls the said cast material at the temperature of 450 degreeC or more and 950 degrees C or less.