JPH06316735A - Hanging overhead wire - Google Patents

Abstract

PURPOSE:To obtain a hanging overhead wire excellent in high temp. creep strength and usable in a severe environment by specifying the oxygen content in a copper alloy to be a certain value or below. CONSTITUTION:The compsn. of a copper alloy contg., by weight, 0.15 to 1% Cr, 0.01 to 0.3% Zr and <=10ppm ocxygen, and the balance Cu with inevitable impurities is formed. Both in the case of >1% Cr content and >0.3% Zr content, its hot workability is deteriorated, and its working into wire rod is made hard. On the other hand, both in the case of <0.15% Cr and <0.01% Zr, desired tensile strength can not be obtd. Moreover, in the case of >10ppm oxygen, high temp. creep strength at >=200 deg.C can not be obtd. By regulating the oxygen content in the copper alloy contg. specified amounts of Cr and Zr to be <=10ppm, the copper alloy hanging overhead wire free from fracture even at the time of being hung in a high temp. environment and furthermore excellent in electrical conductivity can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension line for an electric railway having excellent high temperature creep characteristics.

[0002]

2. Description of the Related Art An overhead line in an electric railway is composed of a trolley wire for supplying electric power to an electric railway vehicle, a suspension overhead wire and a feeder wire for replenishing the shortage of supplied power and supporting the trolley wire in the air.

As described above, the suspended overhead wire is required to support the trolley wire in the air and to supplement the trolley wire with insufficient power, so that it has high conductivity (75% IACS or more) and high strength (60 kgf / mm ^2).
The above characteristics are required. Conventionally, a stranded wire of a hard copper wire was used for a suspended overhead wire, but in recent years, Cr: 0.3-
A suspension wire formed by twisting a copper alloy wire having a composition of 1.5% and Zr: 0.1 to 0.5% and the rest substantially consisting of Cu has also been proposed (Japanese Patent Publication No. 63-3936). See the bulletin).

[0004]

However, in the overhead wire system which has conventionally been composed of a suspension wire made of a copper trolley wire and a hard copper wire stranded wire, a steel core copper trolley wire having the same cross-sectional area has recently been used.
The power supply capacity of the trolley wire itself has decreased, and measures have been taken to make the suspended power supply more deficient in power supply (up by about 60%) than before. In recent years, the electric power consumption per train of electric railway cars has increased, and the number of such trains has also increased. On the other hand, electric railway cars are becoming faster and faster, and due to the wave propagation speed, it is required to reduce the overall diameter of the overhead wire in order to enable the electric railway cars to stably collect current from the trolley wire. And the suspension overhead wire also has a diameter of, for example, 4.
The diameter has been reduced from 7 thin wires of 3 mm to 7 thin wires of 3.7 mm in diameter. As a result, more current flows through the suspended overhead wire, and the amount of heat generated by it increases.
Therefore, as a countermeasure against this, suspended wire materials are required to have excellent tensile strength and excellent heat-resistant cleave characteristics up to 200 ° C or 300 ° C. The suspended overhead wire has a terminal weight of about 1000 kg suspended vertically and is stretched by the tension. However, when an electric railway car passes, the terminal part is repeatedly subjected to bending stress, which is repeated tens of thousands of times. In this case, a breakage may occur at this portion. For this portion, the suspension overhead wire is also required to have a property of being excellent in 90 ° cyclic bending property.

[0005]

Therefore, the present inventors have
While conducting research to develop a suspension wire made of copper alloy that can meet such requirements, conventional Cr and Zr
It has been obtained that the suspended wire made of a copper alloy in which oxygen contained in the copper alloy containing 10 ppm or less does not break even when stretched in a high temperature environment and has excellent conductivity. Of.

The present invention has been made on the basis of the results of such research, and in% by weight (hereinafter,% means% by weight), Cr: 0.15 to 1%, Zr: 0.01 to 0. ．
3%, oxygen: 10 ppm or less is contained, and the remainder is characterized by a suspension wire made of a copper alloy wire having a composition of Cu and inevitable impurities.

The reason why the composition of the copper alloy wire constituting the suspension wire of the present invention is limited as described above is that even if Cr is contained in excess of 1% and Zr is contained in excess of 0.3%. However, the hot workability is deteriorated, and it becomes difficult to process it into a wire. On the other hand, even if Cr is less than 0.15% or Zr is less than 0.01%, desired tensile strength can be obtained. I can't.

If oxygen is contained in excess of 10 ppm, high temperature creep strength of 200 ° C. or higher cannot be obtained. Therefore, the oxygen content is set to 10 ppm or less.

[0009]

[Example] As a raw material, prepared was electrolytic copper having an oxygen content of 20 ppm. The electrolytic copper was charged into a graphite crucible and melted in an Ar gas atmosphere. After blowing CO gas at a flow rate of 10 l / min through the graphite nozzle for 10 minutes continuously, 1000 g of Cu ₂ O powder was instantaneously blown through the graphite nozzle, and further the CO gas was continuously blown for 10 minutes. O by inserting
₂ : An extremely low oxygen copper melt of 10 ppm or less was prepared, Cr was added to this melt, Zr was further added and stirred, and then the obtained copper alloy melt was cast into a mold to have a diameter of 250 mm and a length of 250 mm. A cylindrical copper alloy ingot having a component composition shown in Table 1 having a size of 3 m was obtained.

This cylindrical copper alloy ingot is hot-rolled to produce a wire having a diameter of 18 mm, which is wound into a coil, heated at 950 ° C. for 30 minutes, and then water-cooled for solution treatment. And cold drawing, diameter: 13
mm wire rod, which was wound into a coil.

This coiled wire rod was subjected to precipitation aging treatment in a reducing atmosphere at 470 ° C. for 2 hours, and then cold drawn into a wire rod having a diameter of 4.3 mm. After winding it into a coil, it was again subjected to precipitation aging treatment in a reducing atmosphere at a temperature of 460 ° C. for 2 hours, and the above wire rod having a diameter of 4.3 mm was pitched with 7 wires.
Stranded wires having a diameter of 50 mm and a conductor outer diameter of 12.95 mm were used to produce suspension wires 1 to 5 of the present invention. On the other hand, a conventional suspension overhead wire having the component composition shown in Table 1 was also prepared. For the suspension wires 1 to 5 of the present invention and the conventional suspension wire, tensile strength at room temperature, 0.2% proof stress,
Elongation and conductivity were measured, and further, a high temperature creep rupture test was performed under the conditions of the time retention shown in Table 2 at a temperature of 200 ° C. and 300 ° C. in a N ₂ gas atmosphere, and the time until fracture was measured. The results are shown in Table 2. Further, the suspension wires 1 to 5 of the present invention and the conventional suspension wire were repeatedly subjected to a bending test, and the number of times of bending until breakage was measured. The results are also shown in Table 2. In the repeated bending test, the inner radius of bending is 2.5 times the wire diameter, and the bending direction is 90 ° from the vertical position, then returned to the original position, once, and then in the opposite direction. After bending to 90 °, it was returned to the original position, this was repeated twice, and this was repeated.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

From the results shown in Tables 1 and 2, the suspension lines 1 to 5 of the present invention having an oxygen content of 10 ppm or less have higher high temperature creep strength than the conventional suspension line having an oxygen content of 20 ppm or more. It turns out to be excellent. Therefore,
The suspension overhead wire of the present invention can be safely used even under the severe environment predicted now and in the future, and can also be used as the suspension overhead wire of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiharu Mae, 1-297 Kitabukuro-cho, Omiya-shi, Saitama, Central Research Laboratory, Mitsubishi Materials Corporation (72) Yutaka Furushiba 1-5-1-3, Marunouchi, Chiyoda-ku, Tokyo Ryo Materials Co., Ltd. (72) Inventor Kenji Yajima 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Materials Corporation Central Research Laboratory (72) Inventor Shunji Ishibashi 1-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanritsu Materials Within the corporation

Claims (1)

[Claims] 1. Cr: 0.15 to 1% by weight, Z
A suspended overhead wire comprising a copper alloy wire containing r: 0.01 to 0.3%, oxygen: 10 ppm or less, and the balance of Cu and inevitable impurities.