JPWO2011036728A1 - Copper alloy trolley wire - Google Patents

Abstract

This copper alloy trolley wire is, by weight, Cr: 0.15-0.8%, Zr: 0.01-0.25%, Si: 0.01-0.1%, Hf: 0.1 It consists of a copper alloy having a composition containing 30 ppm, oxygen: 10 ppm or less, and the remainder including Cu and inevitable impurities, and has a crystal grain size of 30 μm or less. The copper alloy may further contain Mg: 0.001 to 0.05% by weight.

Description

  The present invention relates to a trolley line of a train line in a high-speed electric railway.

  In general, a wire rod made of pure copper or a copper alloy containing 0.3% by weight of Sn has been used as a trolley wire of an electric railway.

  However, as seen in the Shinkansen, recently, newly manufactured electric vehicles tend to increase in speed, and it is necessary to increase the overhead wire tension of the trolley wire accordingly. A line is sought.

  The above-described high-tension trolley wire is still proposed. For example, in Patent Document 1 and Patent Document 2, the weight percentage is Zr: 0.001 to 0.35% and Cr: 0.01 to 1.2%. 1 or 2 selected from Mg: 0.3% or less, Zn: 1.5% or less, Ag: 0.2% or less, and Cd: 0.5% or less as necessary A copper alloy trolley wire having a composition comprising 1.5% or less in total and the balance: Cu and inevitable impurities is described. As the inevitable impurities, Sn: 100 ppm or less, Si: 50 ppm or less, P: 50 ppm or less, Fe: 100 ppm or less, Ni: 100 ppm or less, Pb: 20 ppm or less, As: 20 ppm or less, Sb: 20 ppm or less, Bi: 20 ppm or less, S: The content of each impurity is limited to 10 ppm or less.

  These trolley wires made of pure copper or copper alloy are manufactured as follows. First, an ingot of pure copper or a copper alloy having a predetermined composition is manufactured, and a large diameter short pure copper or copper alloy coarse rolled coil is produced by hot rolling or hot extrusion of the ingot. The large diameter short pure copper or copper alloy rough rolled coil is press-welded and then drawn to a predetermined size. The trolley wire is manufactured by the above.

  However, the trolley wires described in Patent Document 1 and Patent Document 2 described above are not sufficiently satisfactory in terms of current-collecting sliding wear resistance and tensile strength. Furthermore, because of the poor pressure contact, not only the pressure contact part and its vicinity may be broken during drawing, but if the tensile strength of the pressure contact part is low, the trolley wire in the overhead state is cut at the pressure contact part. There was a cause of the accident.

Japanese Patent Laid-Open No. 3-56632 Japanese Patent Laid-Open No. 3-56633

  An object of the present invention is to provide a trolley wire having excellent properties in terms of tensile strength, strength of a press-contact portion, and current-collecting sliding wear resistance, no ingot cracking, and excellent workability.

The inventors of the present invention have studied to obtain a copper alloy trolley wire that is made of a copper alloy having a component composition excellent in pressure contact property, and has further improved current collection sliding wear resistance and tensile strength.
As a result, it contains Cr: 0.15-0.8%, Zr: 0.01-0.25%, Si: 0.01-0.1%, Hf: 0.1-30 ppm, and further required Accordingly, in a copper alloy containing Mg: 0.001 to 0.05%, when the oxygen content is limited to 10 ppm or less and the crystal grain size is 30 μm or less, the current-collecting sliding wear resistance and It was found that the tensile strength was improved and the press contact was also improved.

The present invention has been made based on such knowledge and has the following requirements.
The copper alloy trolley wire of the present invention is, by weight, Cr: 0.15-0.8%, Zr: 0.01-0.25%, Si: 0.01-0.1%, Hf: 0.0. It consists of a copper alloy having a composition containing 1 to 30 ppm, oxygen: 10 ppm or less, and the remainder including Cu and inevitable impurities, and the crystal grain size is 30 μm or less.
In the copper alloy trolley wire of the present invention, the copper alloy may further contain Mg: 0.001 to 0.05% by weight.

The trolley wire of the present invention has excellent properties in terms of tensile strength and current-collecting sliding wear resistance. Furthermore, it is excellent in the strength of the pressure contact portion, and excellent pressure contact properties can be obtained. Moreover, there is no ingot cracking and excellent workability. For this reason, a trolley wire can be manufactured at low cost.
In recent years, with the increase in the speed of electric vehicles, the tension of the trolley wire has increased, and the trolley wire has been severely damaged and worn. For this reason, the number of maintenance inspections such as replacement of trolley wires has increased, but the number of maintenance inspections can be reduced by using the trolley wires of the present invention.

FIG. 1 is a schematic view of an apparatus for measuring current-collecting sliding characteristics.

  The reason why the composition of the copper alloy constituting the trolley wire of the present invention is limited as described above will be described.

(A) Cr, Zr
Both Cr and Zr improve wear resistance by being present as dispersed particles in the Cu substrate. Furthermore, it is a component that brings about an improvement in heat resistance strength. However, when the Cr content exceeds 0.8% or the Zr content exceeds 0.25%, the dispersed particles become large, and the press-contact strength of the finished line after processing decreases. And an arc generation rate becomes high and current collection sliding wear resistance falls. On the other hand, when the Cr content is less than 0.15%, or the Zr content is less than 0.01%, the desired effect cannot be obtained. Therefore, the respective contents are determined so as to be in the range of Cr: 0.15 to 0.8% and Zr: 0.01 to 0.25%.

(B) Si
Si has the effect of improving the pressure contact strength and further improving the sliding wear characteristics. However, if the content is less than 0.01%, the desired effect cannot be obtained. On the other hand, if Si is contained in an amount exceeding 0.1%, the conductivity is lowered. For this reason, the Si content is set to 0.01 to 0.1%.

(C) Mg
Mg may be contained as required, but Mg also has the effect of improving the sliding wear characteristics, like Si. However, if the content is less than 0.001%, the desired effect cannot be obtained. On the other hand, if Mg is contained in excess of 0.05%, the familiarity with the current collector plate is deteriorated. For this reason, the content was set to 0.001 to 0.05%.

(D) Hf
Hf refines the crystal grains of the ingot, thereby reducing casting defects and improving the soundness and manufacturing yield of the ingot, and hot working of the ingot and subsequent cold working. It has the effect of improving workability and thereby suppressing the occurrence of defects such as cracks. Along with these actions, the final product (copper alloy trolley wire) has a crystal grain size of 30 μm or less, thereby improving the fatigue strength. However, if the content is less than 0.1 ppm, the effect of crystal grain refinement cannot be obtained. On the other hand, even if Hf is contained in excess of 30 ppm, the effect is not sufficiently obtained, resulting in an increase in cost and a decrease in conductivity. For this reason, the content of Hf is set to 0.1 to 30 ppm.

(E) Oxygen When oxygen exceeds 10 ppm, a crystallized product mainly composed of Cr, Zr, Si, Mg and an oxide is formed, and the size tends to be 2 μm or more. If a crystallized substance having a size of 2 μm or more remains in the trolley wire substrate, the strength of the bonded portion after pressure welding and the vicinity thereof are lowered. And the arc generation rate becomes high and the trolley wire is severely damaged. For this reason, the oxygen content is set to 10 ppm or less.

Next, an example of the manufacturing method of the copper alloy trolley wire of this invention is shown below.
First, reducing gas is blown into molten copper obtained by dissolving ordinary oxygen-free copper through a graphite nozzle. Copper oxide is temporarily added in the course of blowing the reducing gas, and then the reducing gas is blown to produce an extremely low oxygen copper melt of oxygen: 0.5 ppm or less. A predetermined amount of Cr is added to this ultra-low oxygen copper melt, and a predetermined amount of Zr, Si and Hf, and Mg is added as necessary. Thereafter, casting is performed to produce a cylindrical or prismatic ingot.

  The ingot is preferably heated to 850 ° C. to 1050 ° C. in a reducing atmosphere and hot-worked to produce a rough wire. This rough wire is hot-welded or cold-welded, and then subjected to a solution treatment consisting of holding at 800 to 1050 ° C. for 0.1 to 2 hours and subsequent rapid cooling. Further, a trolley wire having a predetermined cross-sectional dimension is produced by cold working.

As a raw material, electrolytic copper having an oxygen content of 20 ppm was prepared. This electrolytic copper was charged into a graphite crucible and dissolved in an Ar gas atmosphere. When the molten copper temperature reached 1200 ° C., CO gas at a flow rate of about 10 l / min was blown through a graphite nozzle and was blown continuously for 10 minutes. Thereafter, 1000 g of Cu ₂ O powder was instantaneously blown through the graphite nozzle, and the CO gas was blown continuously for 10 minutes. In this way, an extremely low oxygen copper melt having O _{2 of} 0.5 ppm or less was produced. Cr was added to the molten metal, and Zr, Si and Mg were further added and stirred. Next, the obtained molten copper alloy was cast into a mold to obtain a cylindrical copper alloy ingot having a diameter of 250 mm and a length of 3 m.

  This cylindrical copper alloy ingot was heated in a CO gas atmosphere at a temperature of 900 ° C. for 1 hour to produce a rough rolled wire having a diameter of 25 mm and a length of 300 m. This rough rolled wire was hot-welded to form a long hot rough rolled wire, and then subjected to a solution treatment comprising a temperature of 950 ° C. for 1 hour and subsequent water cooling in a CO gas atmosphere.

  The surface oxide of the rough rolled wire having a diameter of 25 mm subjected to the solution treatment was removed. And cold drawing was repeated 8 times, and finally the wire of diameter: 12mm was produced. The copper alloy wire thus obtained was further charged into a photolithography annealing furnace and subjected to an aging precipitation treatment at 450 ° C. for 1.5 hours. By the above, the trolley wires 1-1 to 1-5 and 2 to 8 of the present invention having the component compositions shown in Table 1, the trolley wires 1 to 15 of the comparative example, and the trolley wires of the conventional example were manufactured.

With respect to these trolley wires, the tensile strength at the portion other than the press contact portion and the tensile strength at the press contact portion were measured by the method shown in JIS E2101. As for the strength of the press-contact portion, the tensile strength of 95% or more is secured with respect to the tensile strength of the portion other than the press-contact portion, and the tensile strength of 85% or more to less than 95% is secured. A sample having a tensile strength of less than 85% was determined to be C, and the results are shown in Table 2.
Furthermore, the conductivity was measured at a measurement length of 1 m by a four-terminal method in accordance with JIS C 3001. The obtained results are shown in Table 2.

  Moreover, the current collection sliding wear characteristic was measured using the apparatus shown in FIG. FIG. 1 is a schematic diagram of an apparatus for measuring current-collecting sliding wear characteristics. In FIG. 1, 1 is a rotating body, 2 is a trolley wire, 3 is a current collector plate (slip plate), and 4 is a line-separation rate. It is a total.

  As shown in the trolley wire 2 of FIG. 1, the trolley wires 1-1 to 1-5, 2 to 8 of the present invention example, the trolley wires 1 to 15 of the comparative example, and the trolley wire of the conventional example have a diameter of 50 cm. It was wound around the rotating body 1. On the other hand, the current collector plate 3 made of a pantograph iron-based sliding plate (M-39, trade name) was pressed against the trolley wire with a pressing force of 2 kgf. The rotating body 1 is rotated at a peripheral speed of 15 km / hour for 60 minutes while a 20 A, 100 V direct current is passed through the current collecting plate 3 to collect current collecting plate wear rate, trolley wire cross-sectional area wear rate, arc generation rate, etc. The current-collecting sliding wear characteristics were measured.

The measured values obtained are shown in Table 3.
The current collector plate wear rate was determined by dividing the weight reduction amount of the current collector plate by the value obtained by converting the number of rotations of the rotating body into a distance.
The trolley wire cross-sectional area wear rate was determined by accurately measuring the diameter of the trolley wire after the test with a micrometer and dividing the decrease by the number of revolutions.
Further, since a potential difference of 10 to 20 V is generated when the arc is generated, it was determined that the arc was generated when the potential difference was 6 V or more and 50 V or less. Then, during the current collection wear test, this potential difference was measured for 10 seconds every 2 minutes using a wire separation rate meter. This was continuously recorded on a chart to determine the arc generation time. The percentage of arc generation time for this 10 seconds was determined as the arc generation rate.

Further, ingot cracking, crystal grain size, workability, and fatigue characteristics were evaluated by the following methods, and the obtained results are shown in Table 4.
As for ingot cracking, A (good) indicates that there are no practically harmful defects such as cracks on the outer surface and cross section, and C (bad) indicates that there are practically harmful defects such as cracks.
The crystal grain size was measured as follows in accordance with the comparative method defined in JIS H 0501. First, mechanical polishing and mirror finishing were performed on the cross section perpendicular to the axis of the manufactured trolley wire sample, and then etching was performed. Then, the etched cross section was observed with an optical microscope, and the image or photograph was compared with a standard photograph to measure the crystal grain size.
As for workability, when hot working and cold working are performed on the ingot, no defects such as cracks or entrainment that are harmful to use occur (A), and cracks that are harmful to use. A case where defects such as entrainment occurred was defined as C (bad).
The fatigue characteristics were evaluated by a fatigue test in which a trolley wire was supported at a length of 1 m and a strain amplitude was given to the center between the support points in a state where a tensile load of 19.6 kN was generated. A (good) when the fatigue limit or time strength has an advantage of 5% or more compared to the conventional trolley wire, and B (fair) when the equivalent or superiority of 5% or more is not seen .

  From the results shown in Tables 1 to 4, the trolley wires 1-1 to 1-5 and 2 to 8 of the present invention are all in comparison with the trolley wires of the conventional example, and the tensile strength and the current collecting sliding wear resistance. It has been found that it has excellent characteristics. Further, it can be understood that there is no ingot cracking, excellent workability, and manufacturing costs can be reduced.

  Moreover, since the trolley wires 1-1 to 1-5 and 2-8 of the present invention examples containing 0.1 to 30 ppm of Hf have no ingot cracking and the crystal grain size is 30 μm or less, the workability and It can be seen that the fatigue characteristics are excellent.

  As the speed of electric vehicles increases, the tension of the trolley wire increases and the trolley wire is severely damaged and worn. For this reason, the number of maintenance inspections such as replacement of trolley wires has increased, but the number of maintenance inspections can be reduced by using the trolley wires of the present invention.

  Since the trolley wire of the present invention has excellent properties in terms of tensile strength and current-collecting sliding wear resistance, damage and wear can be suppressed even when a large overhead wire tension is applied. For this reason, it can be suitably used as a trolley wire for an electric vehicle such as a Shinkansen that operates at high speed.

  1 Rotating body, 2 trolley wires, 3 current collector, 4 wire separation rate meter.

Claims (2)

In wt%, Cr: 0.15-0.8%, Zr: 0.01-0.25%, Si: 0.01-0.1%, Hf: 0.1-30 ppm, oxygen: 10 ppm or less Containing, consisting of a copper alloy of a composition containing Cu and inevitable impurities as the balance,
A copper alloy trolley wire having a crystal grain size of 30 μm or less. The copper alloy trolley wire according to claim 1, wherein the copper alloy further contains Mg: 0.001 to 0.05% by weight.

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