JPH0681404B2 - Magnetic heating filament manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a magnetic heating filament used as a snow melting wire of an overhead wire, and particularly to a low magnetic field and high heat generation with improved magnetic heating characteristics. To a magnetic heating filament of a mold.

[Prior Art] As shown in FIG. 2, the structure of a magnetic filament used as a snow-melting wire of an overhead wire is made of a conductive metal or alloy around a core wire 1 made of a ferromagnetic metal or alloy. It is coated with the coating layer 2. This magnetic filament is used by winding it around an overhead wire at an angle close to a right angle to the twisting direction.

The principle of heat generation of the magnetic filament is as follows.
When an alternating current is passed in the overhead wire direction, a ring-shaped alternating magnetic field is generated around the overhead wire.

Then, in the magnetic filaments wound around the overhead wire, the core magnetic field 1 of which the spatial magnetic field component and the electric field component are ferromagnetic
The leakage magnetic flux of the surroundings is concentrated on the conductive coating layer 2 attached to the periphery of the ferromagnetic core wire 1. Electromagnetic induction occurs due to the concentrated magnetic flux, and an eddy current is generated in the coating layer 2 made of a conductive metal or alloy. Due to this eddy current
The Joule loss causes the magnetic heating filament to generate heat, which causes snow melting on the snow that has adhered to the overhead wire.

In this case, it is the magnitude of the eddy current loss that influences the heat generation amount. The following two factors influence the eddy current loss, and the heat generation amount is determined by the combination of these factors. Come on.

The time change of the leakage magnetic flux density passing through the conductive coating layer 2.

How to attenuate the electromagnetic field depending on the distance from the ferromagnetic core wire 1.

The magnetic permeability of the central ferromagnetic core wire 1 has a great influence on these characteristics. In particular, the magnetic permeability on the low magnetic field side influences these characteristics.

Thus, in the conventional filamentous body, a thick central magnetic material is coated with a conductive metal, and then this composite is thinned by plastic working, and then mechanical stress relaxation is performed to obtain a product.

[Problems to be Solved by the Invention] However, in this conventional manufacturing method, internal stress is not easily removed by mechanical stress relaxation,
Also, since the plastic working forms a texture in which the crystal orientations are concentrated in one direction, uniaxial magnetic anisotropy is likely to occur. When such magnetic anisotropy occurs, the magnetic permeability remarkably decreases. Normally, the snowmelt spiral wire loses its ability to melt in a magnetic field environment of 100e or less.

The present invention has been made in view of such problems,
It is an object of the present invention to provide a method for manufacturing a magnetic heating filament in which the magnetic permeability of a ferromagnetic core wire disposed in the center is improved, the heat generation characteristics are improved, and a sufficient snow melting ability can be provided even in a low magnetic field. .

[Means for Solving the Problems] A method of manufacturing a magnetic heating filament according to the present invention is to plastically work a ferromagnetic metal or alloy to obtain a core wire, and then heat the core wire to a temperature higher than its recrystallization temperature. After being heated and recrystallized, a conductive metal or alloy is plated and deposited around the core wire.

[Operation] In the present invention, after the core wire is plastically worked, the core wire is heated to a temperature higher than the recrystallization temperature to be recrystallized. As a result, the magnetic permeability which has been lowered by the plastic working is recovered, and a sufficiently high magnetic permeability can be obtained. On the other hand, this recrystallization temperature exceeds 900 ° C. for a metal or alloy used as a usual ferromagnetic core wire material, and therefore exceeds the melting point of an aluminum alloy usually used as a conductive coating layer. Therefore, this coating layer is deposited by plating around the core wire after the recrystallization heat treatment. As a result, a magnetic heating filament in which the magnetic permeability of the central magnetic body is remarkably improved can be obtained.

[Examples] Examples of the present invention will be specifically described below.

An alloy containing 3d transition metal such as Fe, Ni, Cr, Mn or Co is used for the central magnetic body (core wire) of the magnetic heating filament used as a snow melting wire, and an alloy mainly containing Fe is used. To be done. In these alloys, uniaxial anisotropy occurs due to internal residual stress generated by plastic working during wire drawing, resulting in a marked decrease in magnetic permeability.

FIG. 1 is a graph showing the magnetization characteristics of the commercially available 42 alloy with the horizontal axis representing the magnetic field (0 _e ) and the vertical axis representing the magnetic flux density (G).

In Fig. 1, the four types of materials whose magnetization characteristics are shown are those that have been drawn (drawn from wire diameter 8 mm to wire diameter 4 mm) at 450 ° C.
Those annealed at 900 ° C., solution-quenched at 900 ° C. for 30 minutes and then water-quenched, and annealed at 900 ° C. for 30 minutes.

The magnetic permeability can be obtained by dividing the maximum value of the magnetic flux density shown in Fig. 1 by the corresponding magnetic field. The magnetic permeability immediately after wire drawing thus obtained is 77 (CGS / EMU). Despite being low, the magnetic permeability after annealing at 900 ℃ is 1000 (CGS / EM
U), and an extremely high magnetic permeability of about 13 times is obtained. This is because recrystallization proceeded by annealing at 900 ° C. On the other hand, in the case of annealing at 450 ° C, since recrystallization does not occur, the transmittance is as low as 126 (CGS / EMU).

Therefore, in the method of the present invention, the ferromagnetic metal or alloy serving as the core wire is recrystallized by heating it to the recrystallization temperature or higher. After the recrystallization treatment, the core wire is not subjected to plastic working.

In the conventional method for producing a magnetic heating filament, as described above, the core wire is coated by coating the material for the conductive coating layer around the core wire and then drawing the composite. A magnetic filament coated with layers is produced. However, also in the present invention, if the coating layer is formed by wire drawing of the composite in the same manner and then the above-mentioned recrystallization treatment is carried out, the following problems occur.

That is, the snow-melting wire is used by being wound around an overhead wire,
An aluminum alloy is usually used for the conductive coating layer of the snow melting wire (magnetic heating filament). However,
Since the melting point of this aluminum alloy is lower than the recrystallization treatment temperature (for example, 900 ° C in the case of 42 alloy), the above-mentioned recrystallization treatment cannot be performed after depositing the aluminum alloy layer. Thus, it is extremely difficult to recrystallize the core wire after depositing the conductive coating layer. On the other hand, after recrystallizing the core wire, depositing an aluminum alloy material and drawing the composite to form an aluminum alloy coating layer around the core wire is a plastic deformation of the core wire. Will be added,
This causes a decrease in magnetic permeability.

Therefore, in the present invention, a coating layer of aluminum alloy or the like is formed on the core wire after the recrystallization treatment by plating. Examples of this plating method include hot dipping, electroplating, and electroless plating. When an aluminum alloy is used as the conductive coating layer, it is preferable to form the coating layer by a hot dip plating method in consideration of manufacturing cost and the like.

The magnetic heating filament produced in this way has a core wire of 42
If it is an alloy and the coating layer is an aluminum alloy, it is possible to obtain more than four times as much heat generation as the conventional magnetic heating filament, and it can also be used as a snow melting wire in a low magnetic field of 100e or less. Is.

[Effects of the Invention] According to the present invention, the magnetic core wire is recrystallized to remove anisotropy during plastic working to increase the magnetic permeability, and then the conductive coating layer is formed by plating. After the recrystallization treatment, the coating layer can be formed without applying plastic deformation to the core wire.

Therefore, according to the present invention, it is possible to manufacture a magnetic heating filament in which the magnetic permeability of the core wire is high, the amount of heat generation is significantly increased, and a sufficient snow melting effect is obtained even in a low magnetic field.

[Brief description of drawings]

FIG. 1 is a grab diagram showing the magnetization characteristics of 42 alloy, and FIG. 2 is a diagram showing a cross section of a magnetic heating filament. 1; Ferromagnetic metal or alloy core wire, 2; Conductive metal or alloy coating layer

Claims (2)

[Claims] Claim: What is claimed is: 1. A ferromagnetic metal or alloy is plastic-processed to obtain a core wire, which is then heated to a temperature higher than its recrystallization temperature to recrystallize the core wire. A method of manufacturing a magnetic heating filament, which comprises depositing a metal or an alloy by plating. 2. The method for producing a magnetic heating filament according to claim 1, wherein the conductive metal or alloy is applied to the core wire by hot dipping, electroplating or electroless plating.