HK1145664B - Process for manufacturing copper alloy wire - Google Patents

Description

Method for manufacturing copper alloy wire

Technical Field

The present invention relates to a method for producing a phosphorus-containing copper alloy wire by adding a refractory element such as iron and phosphorus to molten copper from a melting furnace and rolling the molten copper while continuously casting the molten copper.

The present application claims priority based on Japanese application No. 2007-269018, 10/16/2007, the contents of which are incorporated herein by reference.

Background

The copper alloy wire containing iron and phosphorus has excellent wear resistance, and by applying the copper alloy wire to overhead conductors for railways and the like, the frequency of repairs and the like can be reduced, and the running cost can be reduced.

As a method for producing the copper alloy wire containing iron and phosphorus, there is a continuous casting method described in patent document 1.

In the production method described in patent document 1, molten copper flowing out of a blast furnace for melting a copper raw material is temporarily kept in a non-oxidizing atmosphere in a holding furnace, and then oxygen and hydrogen are removed from the molten copper by a degassing treatment apparatus. The molten copper is then heated to a high temperature using a heating furnace while the 1 st alloying element is added. The molten copper is then transported via a conduit to a tundish where the 2 nd alloying element is added. By adding iron as the 1 st alloying element and phosphorus as the 2 nd alloying element, a copper alloy containing iron and phosphorus can be produced. Then, molten copper is supplied from a tundish into a graphite mold to produce an ingot, and the ingot is extruded and processed to produce a copper alloy wire.

On the other hand, as a method for continuously manufacturing a copper wire by continuously performing casting to rolling on a single line, there is a method using a belt-type continuous casting machine as described in patent document 2.

The main part of the belt-wheel type continuous casting machine is constituted by an endless belt which moves around, and a casting wheel which rotates with a part of the circumference in contact with the endless belt. The continuous casting machine is connected to a large-sized melting furnace such as a blast furnace and further connected to a calender, whereby molten copper from the melting furnace can be continuously cast and rolled to produce a copper wire at high speed on a flow line. Therefore, the belt wheel type continuous casting machine can obtain high productivity and can be mass-produced, so that the manufacturing cost of the copper wire can be reduced.

Patent document 1: japanese laid-open patent publication No. 2006-341268

Patent document 2: japanese laid-open patent publication No. 2001 and 314950

Disclosure of Invention

However, it is considered that the cost of the copper alloy wire containing iron and phosphorus shown in patent document 1 can be reduced by performing rolling while performing continuous casting using the belt-type continuous casting machine described in patent document 2.

However, when the graphite mold described in patent document 1 is used for casting, the ingot is vertically fed with a large cross-sectional area, and in the case of the belt-wheel type continuous casting machine described in patent document 2, since molten copper is bent while being cast, the cast structure is not appropriate, and cracks are likely to occur during cooling. In order to avoid this problem, it is considered that the difference between the molten copper temperature and the solidification point of copper can be reduced, but the temperature of molten copper is lowered only to a limited extent because refractory iron is added.

The present invention has been made in view of the above circumstances, and an object thereof is to reliably melt refractory elements such as iron and to enable continuous production of a phosphorus-containing copper alloy wire by a belt-wheel type continuous casting machine, thereby achieving cost reduction.

The present invention is a method for continuously producing a phosphorus-containing copper alloy wire while adding phosphorus and an element that is refractory to phosphorus to molten copper, wherein the molten copper is fed from a melting furnace to a heating furnace, is maintained at a first temperature, the refractory element is added to the heating furnace, and the molten copper fed from the heating furnace is conveyed to a tundish. Next, the temperature of the molten copper is lowered from the first temperature to a second temperature in the tundish, phosphorus is added, the molten copper from the tundish is supplied to a belt-type continuous casting machine, the cast copper material is taken out from the belt-type continuous casting machine, and the cast copper material is rolled to continuously produce a phosphorus-containing copper alloy wire.

That is, the refractory elements are classified into refractory elements and phosphorus that can be melted at a lower temperature than the refractory elements, and the refractory elements are first melted while the molten copper from the melting furnace is kept at a high temperature, and phosphorus is added while the temperature of the molten copper is lowered. Thus, when the molten copper is supplied from the tundish to the belt-wheel type continuous casting machine, the temperature of the molten copper is lowered, and therefore, casting can be performed smoothly with bending.

As the refractory element, one or two or more selected from iron, nickel, cobalt, chromium, and the like can be used.

In the production method of the present invention, as a method of lowering the temperature of the molten copper, a method of adding a copper ingot to the molten copper is preferable.

It is preferable that the temperature of the molten copper when the refractory element is added is 1150 ℃ or higher and the temperature of the molten copper when the phosphorus is added is 1130 ℃ or lower. Further, it is preferable that the temperature of the molten copper when the refractory element is added is 1170 ℃ or higher and the temperature of the molten copper when the phosphorus is added is 1120 ℃ or lower.

According to the present invention, since the molten copper fed from the melting furnace is kept at a high temperature in the heating furnace and the refractory element is added, the refractory element can be reliably melted, and since the molten copper is supplied to the pulley-type continuous casting machine in a state where the temperature of the high-temperature molten copper is reduced, the casting can be smoothly performed along with the bending of the pulley-type continuous casting machine, and the occurrence of cracks and the like can be prevented.

Brief description of the drawings

Fig. 1 is a schematic diagram showing a manufacturing apparatus used in a method for manufacturing a copper alloy wire according to an embodiment of the present invention.

FIG. 2A is a schematic view showing the results of the eddy current testing of the present embodiment of example 1.

FIG. 2B is a schematic view of eddy current testing showing the results of the comparative example of example 1.

FIG. 3A is a schematic view showing the results of the eddy current testing of the present embodiment of example 2.

FIG. 3B is a schematic view of eddy current testing showing the results of the comparative example of example 2.

[ description of symbols ]

1 copper alloy wire manufacturing device

21 st addition device

3 tundish

4 pouring nozzle

5 molten copper cooling device

6 phosphorus adding equipment

11 endless belt

13 casting wheel

A melting furnace

B holding furnace

C heating furnace

D casting conduit

E belt wheel type continuous casting machine

F calender

G coil

Detailed Description

Hereinafter, an embodiment of the method for manufacturing a phosphorus-containing copper alloy wire according to the present invention will be described with reference to the drawings.

First, a manufacturing apparatus thereof will be described.

The main parts of the copper alloy production apparatus 1 of the present embodiment are roughly composed of a melting furnace a, a holding furnace B, a heating furnace C, a casting duct D, a belt-wheel type continuous casting machine E, a calender F, and a coil G.

The melting furnace a has a cylindrical furnace body, and a blast furnace, for example, can be suitably used. A plurality of burners (not shown) are provided in a plurality of stages in the vertical direction along the circumferential direction at the lower portion of the melting furnace a. In the melting furnace a, combustion is performed in a reducing atmosphere to produce molten copper called oxygen-free copper. The reducing atmosphere can be obtained, for example, by increasing the fuel ratio in a mixed gas of natural gas and air.

The holding furnace B is used for temporarily holding the molten copper flowing out of the melting furnace a, and controlling the supply amount of the molten copper to the downstream side to be constant. The holding furnace B is provided with a heating device such as a burner so that the temperature of the molten copper to be held does not decrease. In addition, the reducing atmosphere can be formed in the furnace by increasing the fuel ratio of the burner or the like.

As the heating furnace C, for example, a small electric furnace that heats the molten copper fed out through the holding furnace B to a predetermined high temperature, and feeds the molten copper into the casting pipe D while maintaining the high temperature state thereof can be used.

The heating furnace C includes a 1 st addition device 2 for adding a refractory element such as iron to the high-temperature molten copper in the heating furnace C. The added refractory element such as iron may be, for example, a granular material.

The casting pipe D connects the holding furnace B and the heating furnace C, and the heating furnace C and the tundish 2, seals the molten copper in a non-oxidizing atmosphere, and conveys the molten copper to the tundish 3 while degassing treatment is performed. The non-oxidizing atmosphere can be formed by blowing a mixed gas of nitrogen and carbon monoxide as an inert gas or a rare gas such as argon into the casting duct D. As the degassing treatment, a plurality of gates (not shown) are provided in the middle of the casting pipe D, and a large amount of balls or powder (not shown) made of carbon is provided in a floating state between the gates, and degassing is performed by stirring the molten copper using the gates. The carbon balls or powder can efficiently discharge oxygen in the molten copper as carbon monoxide.

In the tundish 3, a pouring nozzle 4 is provided at the end of the molten copper flow direction to supply the molten copper from the tundish 3 to the belt wheel type continuous casting machine E. Further, a molten copper cooling facility 5 and a phosphorus adding facility 6 are provided in the tundish 3. The molten copper cooling facility 5 adds a copper block as a cold material to molten copper, and lowers the temperature of the molten copper by the heat of fusion of the copper block. The phosphorus adding device 6 is a device for adding phosphorus to molten copper that has been cooled by the addition of the copper nuggets.

The positions where the molten copper cooling apparatus 5 and the phosphorus adding apparatus 6 are provided are not necessarily limited to the tundish 3, but in order to avoid chemical reaction of phosphorus with oxygen as much as possible, it is appropriate to provide between the terminal end portion of the casting pipe D having passed through the degassing apparatus and the terminal end of the tundish 3 so as to add phosphorus to the molten copper subjected to the deoxidation treatment and the dehydrogenation treatment.

The belt wheel type continuous casting machine E is composed of an endless belt 11 which moves around, and a casting wheel 13 which rotates while bringing a part of the circumference into contact with the endless belt 11. The belt wheel type continuous casting machine E is further connected to a calender F.

The calender F calenders the cast busbar material 23 fed out from the belt-wheel type continuous casting machine E. The calender F is connected to the coil G via a flaw detector 19.

A method for producing a phosphorus-containing copper alloy wire using the phosphorus-containing copper alloy wire production apparatus having the above-described configuration will be described below.

First, a melting furnace a is charged with a copper raw material such as electrolytic copper, and the copper raw material is melted by combustion in a burner to obtain molten copper. At this time, the inside of the melting furnace a is made into a reducing atmosphere, and molten copper in a low-oxygen state is produced.

The molten copper obtained in the melting furnace a is temporarily held in the holding furnace B, and can be transported while being controlled to a constant flow rate, and supplied to the heating furnace C. The molten copper is, for example, 1100 ℃ or lower immediately after the melting furnace a using a burner, and is kept at a high temperature (first temperature) of, for example, 1150 to 1240 ℃ in the heating furnace C. More preferably, the first temperature is 1190 ℃ to 1210 ℃.

Iron (Fe) was added to the heating furnace C. At this time, the added iron is not completely melted in the molten copper of, for example, 1100 ℃ flowing out from the melting furnace a and the holding furnace B, and is likely to remain as unmelted Fe, but the molten copper can be maintained at a sufficiently high temperature in the heating furnace C, and therefore, even refractory iron can be completely dissolved in the molten copper. The iron may be, for example, granular metallic iron.

There is a method of adding a Cu-Fe alloy to melt the iron, but this method is not preferable because the cost of the additive is high.

Next, molten copper is transferred from the heating furnace C through the casting pipe D to make the casting pipe D have a non-oxidizing atmosphere, and the molten copper is stirred while flowing by providing a sprue (not shown) to perform degassing treatment. The degassing treatment can prevent the molten copper from being mixed with oxides or the like derived from Fe or Sn, and finally the oxygen concentration of the molten copper is 10ppm or less.

The degassed molten copper is transferred to a tundish 3, and in the tundish 3, a copper ingot is added as a cold material by a molten copper cooling apparatus 5 and a phosphorus adding apparatus 6, and phosphorus is simultaneously added. As the copper ingot, for example, in the case where the casting speed is 23 t/hr, the volume of the ingot is 1mm at 150 kg/hr³～150mm³The block of (1). By adding the copper slug, the molten copper temperature can be lowered to a second temperature, e.g. 1085-1130 ℃, lower than the first temperature. The second temperature is more preferably 1090 to 1110 ℃.

Phosphorus is added to the molten copper having the lowered temperature. As phosphorus as the additive material, a copper master alloy (15% P master alloy) containing 15 wt% of phosphorus (P) can be used. The molten copper temperature when the phosphorus is added is reduced to 1085 to 1130 ℃, because if the molten copper temperature exceeds 1130 ℃, cracks or fissures are likely to be generated in the cast mother wire 23 due to the growth of coarse columnar crystals.

It should be noted that if the molten copper fed from the melting furnace a is supplied without passing through the heating furnace C, phosphorus can be added to the molten copper at a relatively low temperature, but in doing so, the refractory iron is not dissolved in the copper and remains as unmelted iron, which is not preferable. Therefore, the temperature of molten copper is temporarily raised to melt the iron, and after the iron is completely dissolved, the temperature of molten copper is lowered to add phosphorus.

In this way, the molten copper with iron and phosphorus added thereto is poured from the tundish 3 into the belt-pulley-type continuous casting machine E to be continuously cast, and is discharged from the belt-pulley-type continuous casting machine E to be molded into the cast mother wire 23. The cast mother wire 23 is rolled by a rolling mill F to form a copper alloy base material 25 containing phosphorus, the presence or absence of a flaw is detected by a flaw detector 19, and then a coil G is wound while applying a lubricating oil such as wax.

According to this manufacturing method, the phosphorus-containing copper alloy base material 25 having good quality and no cracks can be manufactured while iron is completely dissolved in a solid solution. The phosphorus-containing copper alloy base material 25 was subjected to a melting treatment and an aging treatment, and then drawn as an overhead wire (トロリ line) having a groove after a peeling treatment.

For example, a phosphorus-containing copper alloy wire containing 0.080 to 0.500 wt% of Sn, 0.001 to 0.300 wt% of Fe, 0.001 to 0.100 wt% of P, and the balance of Cu and unavoidable impurities can be obtained, and a phosphorus-containing copper alloy wire containing 0.100 to 0.150 wt% of Sn, 0.080 to 0.120 wt% of Fe, 0.025 to 0.040 wt% of P, the balance of Cu and unavoidable impurities, and having a Fe/P ratio of 2.5 to 3.2 is preferable as an overhead wire.

Example 1

The effect of cracking due to the molten copper temperature when phosphorus was added to the tundish was tested.

The copper ingot as the cold material was a copper ball for electroplating of oxygen-free copper, having a diameter of 11mm, and fed back while detecting the molten copper temperature, for example, at a rate of 200 pieces/hour. The molten copper temperature was 1120 ℃. This molten copper was continuously cast by a belt-wheel continuous casting machine and rolled by a calender to produce a rough-rolled copper alloy wire having a diameter of 18 mm. The copper alloy wire contains Sn: 0.118 wt%, Fe: 0.090 wt%, P: 0.031 wt%, and the balance copper alloy containing Cu and unavoidable impurities. In this case, the Fe/P ratio is about 2.9. The oxygen (O) concentration was 8 ppm. Fig. 2A shows a schematic view of the copper alloy wire when flaw detection is performed by an eddy current flaw detector.

On the other hand, the addition of the cold material in the tundish was controlled so that the molten copper temperature became 1140 ℃, at which time, a molten copper containing Sn: 0.118 wt%, Fe: 0.078 wt%, P: 0.031 wt%, and the balance copper alloy containing Cu and unavoidable impurities. The oxygen (O) concentration was 6 ppm. A schematic flaw detection diagram of the copper alloy wire is shown in fig. 2B.

In the former example, about 4000kg was produced, 1 small flaw was found as a product of no trouble, 2 medium flaws were found, and 0 large flaw was found as a product of a defect. On the other hand, in the case of the latter comparative example, about 2800kg was produced, and a large flaw was found to the extent that the flaw detector could not measure it.

Example 2

Next, a mixture containing Co: 1550ppm, Ni: 310ppm, Zn: 280ppm, Sn: 380ppm, P: 470ppm, and the balance of Cu and unavoidable impurities (so-called HRS alloy), and is manufactured by rolling the copper alloy wire through a calender while continuously casting the copper alloy wire with the above-described belt-wheel type continuous casting machine. The oxygen (O) concentration was 6 ppm.

In the tundish, the molten copper temperature is detected and fed back, and at the same time, for example, a copper ingot as a cold material is added at a rate of 200 pieces/hour so that the tundish temperature is 1115 ℃. The flaw detection results obtained by the eddy current flaw detector for the copper alloy wire manufactured under the above conditions are shown in fig. 3A.

On the other hand, the addition of the cold material in the tundish was restricted, and as a result, the molten copper temperature became 1140 ℃. The flaw detection results of the copper alloy wire produced under these conditions by the eddy current flaw detector are shown in fig. 3B.

About 4000kg of the copper alloy wire was produced in the case of this example in which the tundish temperature was 1115 ℃, 19 small flaws were found out as products without hindrance, 12 medium flaws were found, and 6 large flaws were found as products. On the other hand, in the case of the comparative example in which the tundish temperature was 1140 ℃, about 4000kg was produced, and the number of small and medium damages was as large as impossible to measure, and 45 large damages were produced.

The present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the scope of the present invention. For example, the cold material to be added to the tundish may be a copper ball of deoxidized copper containing phosphorus, and the molten copper may be cooled and the phosphorus may be added at the same time. The phosphorus-containing copper alloy wire produced by the production method of the present invention can be applied to, for example, an automotive wiring having a diameter of 8mm to 30mm, in addition to an overhead wire.

Although the description has been given of the configuration in which the copper master alloy (15% P master alloy) is added by the phosphorus addition device provided in the tundish, the present invention is not limited thereto, and elements other than phosphorus may be added by the phosphorus addition device. Further, the tundish may be provided with a 2 nd addition device other than the phosphorus addition device to add another element.

Example 3

Further, the alloy contains Sn: 0.118 wt%, Fe: 0.090 wt%, P: 0.031 wt%, the balance being copper alloy wire containing Cu and unavoidable impurities, and is manufactured by continuous casting with the above-described belt-wheel continuous casting machine and rolling with a calender. The oxygen (O) concentration was 8 ppm.

First, molten copper obtained in a melting furnace is temporarily held in a holding furnace. The mixture was supplied to the heating furnace while controlling the flow rate to a constant value. A predetermined amount of iron (Fe) was added to the furnace while maintaining the temperature at 1200 ℃. The molten copper with the iron (Fe) added thereto is transported to a tundish via a casting pipe. Here, a cold material is added to cool the molten copper. As the copper block as the cold material, a copper ball for electroplating of oxygen-free copper having a diameter of 11mm was used, and the molten copper temperature was measured and fed back while feeding it at a rate of, for example, 220 pieces/hour. The molten copper temperature was 1100 ℃. Here, predetermined amounts of phosphorus (P) and tin (Sn) were added, and this molten copper was continuously cast by a belt-wheel continuous casting machine and rolled by a calender to produce a rough-rolled copper alloy wire having a diameter of 18 mm.

As a result of measuring the flaw on the wire surface using the eddy current flaw detector, about 4000kg was produced in the case of this example, 0 small flaws were found as products with no hindrance, 1 medium flaws were found, and 0 large flaws were found as products with defects. In addition, the cross section of the copper alloy wire was observed at 500 times using a metal microscope, and as a result, no unmelted iron (Fe) was present.

Claims (2)

1. A method for continuously producing a phosphorus-containing copper alloy wire by adding phosphorus and an element that is refractory to phosphorus to molten copper, comprising the steps of:

a step of feeding the molten copper from the melting furnace to a heating furnace, and adding a refractory element while maintaining the molten copper at the 1 st temperature in the heating furnace,

a step of transferring the molten copper from the heating furnace to a tundish to lower the temperature of the molten copper to a 2 nd temperature lower than the 1 st temperature and adding phosphorus, and

a step of supplying molten copper from the tundish to a belt-type continuous casting machine to produce a cast copper material, and rolling the cast copper material discharged from the belt-type continuous casting machine to continuously produce a phosphorus-containing copper alloy wire,

wherein the 1 st temperature of the molten copper when the refractory element is added is 1150 ℃ or higher, and the 2 nd temperature of the molten copper when the phosphorus is added is 1130 ℃ or lower.

2. The method for producing a phosphorus-containing copper alloy wire according to claim 1, wherein a copper ingot is added to the molten copper in order to lower the temperature of the molten copper.