JPH0821513B2 - Insulation coil manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to an insulating coil which is subjected to heat treatment at a high temperature after winding processing and is then used at a relatively low temperature, for example, a superconducting compound which produces an intermetallic compound by a high temperature heat treatment The present invention relates to a method for producing a core wire coil for a material, a coil using an amorphous iron core that needs to be heat-treated at a high temperature, and the like.

“Prior art and its problems” Conventionally, as an insulating coil that is heat-treated at such a high temperature, an inorganic insulating material such as enamel frit is applied on a conductor, and this is heated to form a ceramic insulating layer. It is known that the insulated wire is wound into a coil.

However, since the conductor and the ceramic insulating layer are in close contact with each other, the flexibility as an insulated wire is not sufficient, and there is a problem that the insulating layer is cracked when wound around a coil. Since the coefficient of thermal expansion is different from that of the insulating layer, there is a problem that strain is accumulated in the ceramic layer due to heat shock during heat treatment and the ceramic layer is easily separated.

In order to improve such a problem, an inorganic fiber such as glass fiber is fixed on a conductor by using a binder resin,
Then, heat it to harden the binder resin to make an insulated wire, wrap this insulated wire on a bobbin, etc., and then heat it to a high temperature in the air to decompose and eliminate the binder resin, leaving only the inorganic fiber, the conductor and the inorganic fiber. There is known a coil in which the adhesion to and almost disappears and sufficient heat resistance is obtained.

However, in this insulated coil, when the binder resin is thermally decomposed, the conductor and the bobbin are simultaneously oxidized. Therefore, the conductor and the bobbin must be made of a material having good oxidation resistance. There was a limited inconvenience.

For this reason, the present inventors first provided an insulating layer composed of inorganic fibers and a soluble binder resin on a conductor to form an insulated wire, wound the insulated wire into a coil, and made the coil a good quality of the soluble binder resin. We proposed a method of manufacturing an insulating coil by immersing it in a solvent and dissolving and removing the soluble binder resin. Although this method solves the above problems, the wires of the coil are not adhered to each other.Therefore, when used at around room temperature, the wires tend to move due to temperature changes, vibrations, etc., and the characteristics of the coil change. It was

[Means for Solving the Problems] Therefore, according to the present invention, an insulated wire in which an insulating layer made of an inorganic fiber and a soluble binder resin is formed on a conductor, or an inorganic particle and a soluble binder resin are formed on the conductor. The insulated wire on which the second insulating layer composed of the first insulating layer, the inorganic fiber and the soluble binder resin is formed is wound to form a coil, and the coil is immersed in a good solvent of the soluble binder resin to dissolve and remove the soluble binder resin. Then, after heat treatment in an inert atmosphere, the above problems were solved by impregnating with an insulating resin or a solution containing an insulating resin and an inorganic substance.

FIG. 1 shows a first example of an insulated wire used in the present invention, in which reference numeral 1 is a conductor. The conductor 1 is not particularly limited, and one made of a material having poor oxidation resistance at high temperature such as copper, copper alloy, and superconducting wire coated with these metals is particularly preferable.
The diameter of the conductor 1 is about 0.1 to 5 mm, but the diameter is not limited to this.

A first insulating layer 2 is provided on the surface of the conductor 1. The first insulating layer 2 is obtained by coating and impregnating a resin liquid consisting of a soluble binder resin while winding the inorganic fibers densely around the conductor 1 in a spiral shape, and heating at a temperature not higher than the curing temperature of the soluble binder resin to volatilize the solvent. Then, the inorganic fibers are fixed to the conductor 1. As the inorganic fibers, there are used monofilaments such as electric glass fibers, alumina fibers, zirconia fibers, silica fibers, or twisted yarns, aligned yarns, woven tapes and the like made of these. Further, as the soluble binder resin, any resin may be used as long as it is a resin that is easily dissolved in water and an organic solvent, but in the unlikely event that a small amount of resin remains as a monomer and easily decomposes and disappears,
For example, a methacrylic acid ester polymer, an acrylic acid ester polymer and their copolymers, polyethylene oxide which is soluble in water and an organic solvent are preferable. This resin liquid has a concentration of 0.
5 to 40% by weight is used. The heating temperature may be a temperature at which water and an organic solvent are volatilized, and when a thermosetting resin is used as the soluble binder resin, it needs to be kept at a temperature lower than its crosslinking temperature.

The insulating layer 2 usually has a thickness of about 5 to 500 μm. In addition, the ratio of the inorganic fibers in the insulating layer 2 is a weight ratio.
It is preferably from 60 to 99.5%, and the content of the soluble binder resin is as small as possible.

A lubricating layer is provided on the insulating layer 2 as needed. This lubricating layer is for improving the slipperiness of the surface and the workability when the insulated electric wire is wound around a coil, and is formed by applying a soluble wax.

FIG. 2 shows a second example of the insulated wire used in the present invention. This insulated wire has a first conductor 1 which is composed of inorganic particles and a soluble binder resin.
The insulating layer 3 is provided. As the inorganic particles, powders of alumina, silica, zirconia, glass or the like having an average particle size of 0.1 to 10 μm are used. Moreover, as the soluble binder resin, the same ones as described above are used. The concentration of the soluble binder resin is 0.5 to 40% by weight. A dispersion liquid is prepared by adding inorganic particles to the resin liquid, and the dispersion liquid is applied to the conductor 1 and heated at a temperature not higher than the curing temperature of the soluble binder resin to be fixed to the conductor 1. Then, the first insulating layer 3 is formed. The thickness of the first insulating layer 3 is usually 0.5 to 50 μm, and the proportion of the inorganic particles is 70 to 99.5% by weight.

A second insulating layer 4 made of inorganic fibers and a soluble binder resin is provided on the first insulating layer 3. The second insulating layer 4 is similar to the insulating layer 2 of the insulated wire of the previous example, and has a thickness of about 5 to 500 μm.

Next, a method of manufacturing an insulated coil using such an insulated wire 5 will be described.

First, the insulated wire 5 is wound around a bobbin 6 to form a coil 7, as shown in FIG. Next, the coil 7 is immersed in a good solvent for the soluble binder resin to dissolve and remove the soluble binder resin. When the insulated wire 5 is covered with a lubricating layer, the lubricating layer is previously removed by immersing it in a solvent that dissolves the lubricant forming the lubricating layer. If the lubricant and the soluble binder resin are soluble in the same solvent, they can be dissolved and removed at the same time.

As the good solvent, water, ketones, esters, alcohols, hydrocarbons, halogenated hydrocarbons and the like are appropriately selected in combination with a soluble binder resin, and if necessary, these solvents are about 60 to 70 ° C. May be heated to accelerate the dissolution of the resin. When the soluble binder resin is specifically dissolved, it is preferable to change the solvent several times.

By the immersion in the solvent, the insulating layer 2 of the insulated wire 5 or the soluble binder resin of the first insulating layer 3 and the second insulating layer 4 is dissolved and removed, and these insulating layers 2, 3 and 4 are inorganic particles having good heat-resistant insulating properties and Since the insulating coil 7 is made of inorganic fiber, its heat resistance is extremely high.

Next, the insulating coil 7 thus obtained is heat-treated in an inert gas or vacuum in an inert high temperature atmosphere. This heat treatment heats the conductor 1 to generate an intermetallic compound in the conductor metal or a phase change of the metal forming the bobbin or the iron core. It is necessary to use for. The heat treatment is performed by heating under vacuum or in an inert gas such as nitrogen or argon at 500 to 900 ° C. for about 1 to 50 hours.

In this heat treatment, since the insulating layers 2, 3 and 4 are all made of an inorganic material, the insulating characteristics of the coil 7 do not change.

Next, as shown in FIG. 4, the insulating coil 7 that has been heat-treated is impregnated with an insulating resin or a solution of an insulating resin and an inorganic substance. The insulating resin is preferably a resin having good electric insulation and heat resistance such as epoxy resin, silicone resin, and phenol resin, and a solution obtained by dissolving these resins in an organic solvent is used for impregnation. As the inorganic material, inorganic powder such as insulating silica, alumina, glass is used. For the impregnation treatment, a usual method such as vacuum impregnation treatment is used. After impregnation, the resin is heated by heating to about 100 to 150 ° C. to remove the solvent, and then heated to the resin curing temperature to cure the resin. Further, when using an insulating resin and an inorganic substance, by setting the weight ratio of the insulating resin and the inorganic substance to 3/7 or less, it is possible to make the impregnated product composed of the insulating resin and the inorganic substance porous. Therefore, it is suitable for cooling the coil by permeating a cooling gas or a cooling liquid into the inside of the coil.

By this impregnation treatment, the wire between the coils is fixed with an impregnating material 8 made of an insulating resin or an insulating resin and an inorganic material, and the intended insulated coil is obtained.

[Operation] According to such a method of manufacturing an insulated coil, since inorganic particles or inorganic fibers that do not adhere to the conductor 1 are adhered to the conductor 1 by using a soluble binder resin, insulation is achieved during processing such as coil winding. The layers 2, 3 and 4 are not separated from the conductor 1, and the surfaces of the insulating layers 2, 3 and 4 are relatively smooth and difficult to rub, so that the wires are rubbed against each other or the brim of the bobbin is caught. It does not have the problem of being scratched or the fibers falling apart and shows good processability. Also,
Since the soluble binder resin is dissolved and removed before the heat treatment, the generation of carbon or the like that deteriorates the electrical insulating property is eliminated in the heat treatment step. In addition, since the impregnation treatment is performed after the heat treatment and the inter-wire portion of the coil 7 is filled and solidified with the resin or the impregnated material made of the resin and the inorganic material, mechanical vibration or impact may cause short-circuit between the wires or deterioration of insulation. It never happens. Furthermore, since the heat treatment is performed in an inert atmosphere, a material that is susceptible to high temperature oxidation can be used for the conductor and bobbin.

Example 1 A glass fiber having a diameter of 1.5 mm was spirally wound with a glass fiber having a diameter of 7 μm, and a copolymer composed of 50 parts of normal butyl methacrylate and 50 parts of iso-butyl acrylate (glass transition temperature 40 ℃) 30% toluene solution was applied and impregnated, then toluene was volatilized in a heating furnace at 150 ℃ to form an insulating layer of about 100 μm of glass fiber and acrylate copolymer to obtain an insulated wire. .

Then, the insulated wire was wound on a ceramic-coated metal bobbin having a body diameter of 50 mm and an inner width of 150 mm by 10-layer bifilar winding to form a coil.

The coil was immersed in dichloromethane, which is a good solvent for the acrylate copolymer, and when the resin of about 2 or 3 layers of the coil was dissolved, the acrylate copolymer was dissolved and removed by a method of replacing with new dichloromethane. Next, after heating this coil at 800 ° C. for 50 hours in a nitrogen atmosphere, the insulation resistance between wires at room temperature was measured and it was confirmed that it was 10 ⁹ Ω or more. Next, this coil was impregnated with a 30% solution of epoxy resin in methyl ethyl ketone, the solvent was volatilized, and the resin was cured by heating to obtain an insulated coil.

Example 2 Alumina 50 having an average particle size of 5 μm was formed on the surface of a copper wire having a diameter of 1.5 mm.
% By weight and 50% by weight of glass frit with a softening flow temperature of 700 ° C
75 parts by weight of inorganic particles and 25 parts by weight of a copolymer (glass transition temperature 40 ° C.) of 50 parts of normal butyl methacrylate and 50 parts of iso-butyl acrylate dissolved and dispersed in toluene, and dried. The thickness is about 30
A μm first insulating layer was provided. Next, a glass fiber having a diameter of 7 μm was spirally wound around the first insulating layer, and a copolymer composed of 50 parts of normal butyl methacrylate and 50 parts of iso-butyl acrylate (glass transition temperature).
40 ℃) 30% toluene solution is applied and impregnated, then 150
Toluene was volatilized in a heating furnace at 0 ° C., and a second insulating layer of about 100 μm of glass fiber and acrylate copolymer was provided. After that, the binder resin was removed and heat treated as in Example 1, and then impregnated to obtain an insulated coil.

Example 3 The coil after heat treatment of Example 1 was vacuum impregnated with a dispersion liquid obtained by dissolving and dispersing 60 parts by weight of alumina particles having an average particle size of 0.5 μm and 40 parts by weight of epoxy resin in toluene to form an insulating coil. I got it.

Example 4 The coil after heat treatment in Example 2 was vacuum impregnated with a dispersion liquid obtained by dissolving and dispersing 60 parts by weight of alumina particles having an average particle size of 0.5 μm and 40 parts by weight of epoxy resin in toluene to form an insulating coil. I got it.

These four types of insulating coils were subjected to a vibration test 10 ⁴ times in each of the vertical and horizontal directions of the coil at an acceleration of 9.8 G and an amplitude of 2 mm, and the inter-line insulation characteristics before and after the test were investigated.

For comparison, the same vibration test was performed on the coils of Examples 1 and 2 which were not subjected to the impregnation treatment after the heat treatment. These results are shown in the attached table.

As is clear from this result, it is understood that the insulated coils of Examples 1 to 4 have excellent vibration resistance characteristics.

[Effects of the Invention] As described above, according to the method of manufacturing an insulated coil of the present invention, an inorganic wire and a soluble binder resin are formed on an insulated wire or conductor in which an insulating layer made of an inorganic fiber and a soluble binder resin is formed on the conductor. And a second insulating layer composed of an inorganic fiber and a soluble binder resin are wound to form a coil, and the coil is immersed in a good solvent of the soluble binder resin to form the soluble binder resin. It is dissolved and then heat treated in an inert atmosphere, and then impregnated with an insulating resin or a solution consisting of an insulating resin and an inorganic substance, so the soluble binder resin can be dissolved and removed before the heat treatment. The generation of carbon or the like that lowers the electric insulation is eliminated. In addition, since the impregnation process is performed after the heat treatment and the resin or the resin and the inorganic substance are filled and fixed in the inter-wire portion of the coil, mechanical vibration or shock does not cause short-circuit between wires or deterioration of insulation. Further, since the heat treatment is carried out in an inert atmosphere, there is an advantage that a material which is weak against high temperature oxidation can be used for the conductor and the bobbin.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a first example of an insulated electric wire used in the present invention, and FIG. 2 is a schematic sectional view showing a second example of an insulated electric wire used in the present invention. FIG. 4 is a partial cross-sectional view showing an example of the method of manufacturing the insulated coil of the present invention in the order of steps. 1 ... Conductor, 2 ... Insulating layer, 3 ... First insulating layer, 4 ...
Second insulating layer, 5 ... Insulated wire, 7 ... Insulated coil, 8 ...
... impregnated material

Claims (2)

[Claims] 1. A coil is formed by winding an insulated wire in which an insulating layer made of an inorganic fiber and a soluble binder resin is formed on a conductor, and the coil is immersed in a good solvent for the soluble binder resin to dissolve and remove the soluble binder resin. And then heat-treating in an inert atmosphere, and then impregnating with an insulating resin or a solution of the insulating resin and an inorganic material. 2. An insulated electric wire having a first insulating layer made of inorganic particles and a soluble binder resin and a second insulating layer made of inorganic fibers and a soluble binder resin formed on a conductor and wound to form a coil. Is immersed in a good solvent for the soluble binder resin to dissolve and remove the soluble binder resin, then heat treated in an inert atmosphere, and then impregnated with an insulating resin or a solution consisting of an insulating resin and an inorganic substance. How to make a coil.