JPH0135574B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a linear magnetic material that is wrapped around electric wires to prevent freezing of overhead power transmission and distribution lines. During the winter, snow and ice accrete on overhead transmission and distribution lines in cold regions, especially in northern Japan and the back of Japan, and this can grow to a considerable size, increasing the weight of the wires in the span and causing wind pressure loads. This often leads to an increase in the slackness of the wires, breakage of the wires due to excessive tension, and even the collapse of steel towers. In addition, if ice and snow fall in the form of blocks, not only is there a danger to people passing under the overhead lines, but even if the area under the overhead lines is agricultural land, there is a risk of damaging crops, vinyl houses, etc.
There is a demand for a solution to this problem as it causes a major social problem. For this reason, as a measure to prevent snow accumulation, methods have been used to prevent snow accumulation, such as temporarily transmitting large currents to melt the snow due to the heat generated by the conductor, or attaching ring-shaped objects to power transmission lines to cause the snow to fall. However, large current power transmission cannot be carried out freely due to power system operation restrictions, and even if ring-shaped devices are installed, the effectiveness varies depending on the type of ice and snow.
Furthermore, if the grown ice and snow blocks are simply dropped, there is a risk that secondary disasters will occur at the point where they fall, and this cannot be said to be a sufficient countermeasure. On the other hand, when a sleeve made of magnetic material, a spirally processed linear body, tape, rod, etc. is wrapped around an AC power transmission line, hysteresis loss is generated when the AC magnetic field due to the transmission current passes through the sleeve, etc. A method of melting snow using heat loss due to eddy current loss has also been proposed, but wrapping these sleeves, wires, tapes, and rods around electric wires increases the weight of the wires, so it is desirable that they be as lightweight as possible. Furthermore, since heat generated from the magnetic material at temperatures at which icing and snow does not occur increases power transmission loss, it is desirable to use a material with a low Curie point that reduces magnetic properties and does not generate heat at high temperatures. By the way, Fe-N ₁ -C〓-Si alloy, etc., has a Curie point near room temperature as a magnetic alloy with a Curie point between 0℃ and 100℃, and also has good magnetic properties. When it is processed into a wire and covered with it, or processed into a wire or tape and wrapped around the wire, this magnetic material becomes a ferromagnetic material during snowfall.
Heat generation due to hysteresis loss or eddy current loss acts in combination with heat generation due to resistance loss in the wire, melting snow attached to the wire, magnetic material becomes paramagnetic in high temperature conditions, and power transmission is caused by unnecessary heat generation. This is a practically effective method as a countermeasure against snow damage because it eliminates losses. However, in the past, this type of alloy had the disadvantage that heat treatment conditions and processing conditions greatly affected the magnetic properties, resulting in poor reproducibility. For example, when processing wires into wires, drawing is usually performed, but regardless of the degree of drawing, the magnetic properties will deteriorate, and if a quantity that is effective as a snow damage countermeasure is attached to electric wires, it will cause significant damage. There are drawbacks such as an increase in weight, making it impossible to use it practically. The present invention has been made in view of the above circumstances, and provides a wire material for snow melting wires in which a highly conductive metal is coated around a magnetic material and strain is removed, and a conductive metal is coated around a magnetic metal wire material. A wire material for snow-melting electric wires, characterized in that, after the diameter is reduced to a predetermined diameter, the magnetic metal wire material is subjected to repeated bending processing so that the ratio of the diameter to the bending diameter is 2 to 9% to remove residual strain. It consists in the manufacturing method. When a magnetic material is subjected to wire drawing or rolling, the crystals become distorted, and the distortion tends to increase toward the outer periphery due to friction with processing equipment and other objects. It is generally believed that this residual strain changes the magnetic properties. In general, this strain is often recovered by heating, but in the case of magnetic metals (alloys) used in the present invention, the degree of recovery by heating is small, and the strength decreases when heated to high temperatures. In addition, there was a risk that a compound layer would be formed at the interface between the conductive metal and the magnetic material of the coating material, impeding the conductive performance or altering the magnetic properties. The method according to the present invention can recover the residual strain by heat treatment and significantly improve the magnetic properties without causing these drawbacks. Next, examples of the present invention will be described. Example 1 An Fe--Ni alloy having the composition shown in Table 1 was vacuum melted and cast into an ingot with a diameter of 30 mm, and then hot and cold forged to obtain a wire rod with a diameter of 10 mm.

[Table] After cleaning the surface of these wires to remove oxidation scale, oil, etc., they were coated with aluminum tubes with an outer diameter of 12 mm and a wall thickness of 0.8 mm, and then wire-drawn to a diameter of 2.6 mm.
Aluminum and the magnetic alloy inside were bonded metallically. When this wire is the wire diameter r of the magnetic metal wire and the bending diameter R, r/R=0.052, that is, 1.5%, 5.2%, 9.5%
The wire was repeatedly bent so that the bending strain was applied all around the outermost part of the alloy to remove residual strain, and the wire was drawn as it was and the strain was not removed by bending. Magnetic properties were measured using a magnetization measuring device. The results are shown in Table 2, and it can be seen that the composite wire according to the present invention has significantly improved magnetic properties. (In both cases, the measurement conditions were 0℃,
It is 30Oe. )

[Table] Example 2 Ni 6.2% by weight, Cr 3.1% by weight, Si 1.0% by weight balance
An alloy consisting of Fe and impurities was made into a composite wire of alloy and aluminum with a diameter of 2.6 mm by the same method as in Example 1, and this was repeatedly bent so that the strain shown in Table 3 was applied to the outermost part of the alloy wire. Processed,
Residual strain was removed. As can be seen from Table 3, when the bending strain is less than 2%, the improved effect is hardly recognized, and when it is more than 9%, it is not preferable because it causes waviness in the wire or the material breaks.

[Table] Example 3 Among the Fe-Ni alloys shown in Table 1, A and B
A composite wire with an outer diameter of 2.6 mm was prepared by coating aluminum with alloy and carbon steel in the same manner as in Example 1.
When the calorific value in an alternating magnetic field of 15 Oe was measured at 0°C, the calorific value per 1 kg was obtained as shown in Table 4.

[Table] From Table 4, it can be seen that the calorific value of Fe-Ni alloys that were subjected to residual strain relief processing was significantly increased compared to those that were not treated. In addition, it will be understood that the effect of residual strain relief does not appear in carbon steel, and the increase in heat generation due to strain relief is unique to Fe-Ni alloys. In addition, when carrying out the present invention, the above-mentioned r/R is 2.
If it is less than 9%, the strain relief is insufficient and the expected heat generation cannot be obtained, and if it exceeds 9%, the residual strain relief is sufficient, but machining may not be possible or it may be difficult to obtain the desired amount of heat in post-processing. The moldability or mechanical strength decreases, both of which are undesirable from a practical standpoint.In the end, a range of 2 to 9% can be said to be excellent in terms of heat generation, that is, snow melting effect, and strength workability.

Claims (1)

[Scope of Claims] 1. A wire material for a snow-melting electric wire, in which the surface of a magnetic metal material is coated with a conductive metal, and residual strain due to diameter reduction processing is removed. 2 Coating a conductive metal around the magnetic metal wire,
Manufacture of a wire material for snow-melting electric wire, which is characterized by reducing the diameter to a predetermined diameter and then repeatedly bending the wire material so that the ratio of the diameter of the magnetic metal wire material to the bending diameter is 2 to 9% to remove residual strain. Method.