JPH09270340A - Wound core excellent in rigidity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a wound core having excellent rigidity at high temperature, by a method wherein a core material formed by winding a plurality of times of a silicon steel band, resin to be impregnated or applied to the above- mentioned core material, and a heat-proof sheet wound on the core material are provided. SOLUTION: This wound core is formed by winding a heat-proof sheet on a core material, and a glass heat-proof sheet is used for the heat-proof sheet. This heat-proof glass sheet has the structure formed by winding heat-proof glass fibers into a resin sheet. Also, a metal sheet, which has the thermal expansion coefficient approximate to that of the core material, is used as the heat- resisting sheet. In this case, the steel material such as the stainless steel and the non-ferrous material such as Al and Ti are used for the metal sheet. Also, an insulator can be interposed between the core material and the metal sheet. In this case, an insulating material is applied or an insulating sheet is used. Also, a heat-resisting sheet having an outer layer consisting of a metal and an inner layer consisting of an insulator, may be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wound iron core used for a cut core or the like, and more particularly, it has a strength that can be used at a temperature exceeding the glass transition temperature of a resin impregnated or applied as an adhesive or an insulating agent. Regarding an excellent wound iron core.

[0002]

2. Description of the Related Art An iron core is an electromagnetic electronic component used in a transformer or the like, and a wound iron core is known as such an iron core. The wound iron core is formed by impregnating or applying a resin on an iron core material formed by winding a silicon steel strip a plurality of times, and is used as a cut core or the like. The resin used in this case is essential as an adhesive for maintaining the shape of the iron core material and as an insulating agent.

Regarding the insulating agent for electric equipment, JIS4003
It is classified according to the maximum allowable temperature. That is, the maximum operating temperature is specified as 130 ° C. for type B, 155 ° C. for type F, and 180 ° C. for type H.

On the other hand, conventionally, varnish has been generally used as the resin with which the cut core is impregnated, but its glass transition temperature is 60 to 90 ° C. When the glass transition temperature is exceeded, the adhesive strength becomes extremely high. Decrease, above 120 ° C,
It drops to less than 1/5 of the strength at room temperature and peels off easily. Therefore, the strength of the varnish generally used for the cut core depends on whether or not it can be applied to the B type, and it is difficult to apply it to the F type and the H type.

Although cut cores are not used at such temperatures in normal meter applications, there are B class, F class and H class specifications for power applications, and long-term use is considered. In some cases, the conventional cut core has a problem in strength.

In order to solve such a problem, it is possible to increase the cut core strength not only by the varnish but also by another method. For example, a method of welding the cut core laminated portion and a method of hardening the entire cut core by epoxy resin powder coating can be considered.

However, when the welding method is adopted, there is a drawback that the iron loss characteristics are deteriorated. Even if the method of hardening by powder coating is adopted, at most B
It can only withstand the temperatures of the seeds, and cannot be said to withstand high temperature use sufficiently.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a wound iron core having excellent strength even at a high temperature exceeding the glass transition temperature of the resin used. Is an issue.

[0009]

In order to solve the above problems, the present invention provides an iron core material formed by winding a silicon steel strip a plurality of times, a resin impregnated or applied to the iron core material, and an iron. Provided is a wound iron core having excellent strength, which comprises a heat-resistant sheet wound around a core material.

By winding the heat-resistant sheet in this manner, even when the adhesive strength of the resin decreases when the resin is used at a high temperature exceeding the glass transition point of the resin, it is reinforced by the heat-resistant sheet to maintain sufficient strength. it can.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A wound iron core according to the present invention is characterized in that a heat resistant sheet is wound around an iron core material. Here, a heat-resistant glass sheet can be used as the heat-resistant sheet. The heat resistant glass sheet generally has a structure in which heat resistant glass fibers are woven into a resin sheet. Since this heat-resistant glass sheet can sufficiently withstand a high temperature of 180 ° C. or higher, the strength of the wound iron core at a high temperature can be made excellent.

However, the coefficient of thermal expansion is different from about 1.1 × 10 ⁻⁵ / ° C. of the silicon steel strip constituting the iron core material,
Further, in the case where the resin sheet has a structure in which the heat-resistant glass fiber is woven, the elongation thereof is 5 to 6%, so that a gap is gradually formed between the iron core material and the heat-resistant glass sheet during actual use.

From this point of view, it is preferable to use a metal sheet having a thermal expansion coefficient similar to that of the iron core material as the heat resistant sheet. As the metal sheet, either a steel material such as stainless steel or a non-ferrous material such as Al or Ti can be used, and among these, a steel material such as stainless steel having a thermal expansion coefficient substantially equal to that of the iron core material is preferable. Among them, non-magnetic austenitic stainless steel is particularly preferable from the viewpoint of not vibrating due to electromagnetic force.

In the case where the heat-resistant tape is made of metal, when the resin disappears from between the iron core material and the heat-resistant sheet at a high temperature exceeding the glass transition temperature of the resin, there occurs a portion where the metals come into contact with each other to conduct electricity. When used, the metal sheet will be damaged by heating. Therefore, it is preferable to interpose an insulator between the iron core material and the metal sheet. In this case, an insulator may be applied or an insulating sheet may be used. From the viewpoint of ease of construction, it is preferable to use a heat resistant sheet having an outer layer made of metal and an inner layer made of an insulator. In any case, it is preferable to use an insulator that does not disappear even when used at high temperature, and examples of such an insulator include a heat resistant glass tape and a polyimide tape.

Specific examples of such a heat resistant sheet include:
An example is SUS tape. These are easily available, and it is possible to prepare various thicknesses from 10 μm to 0.1 μm or more at a pitch of 10 μm. For practical use, this tape having an adhesive layer formed thereon is preferable. However, when the adhesive layer is used as the insulating layer, it may disappear as described above, and therefore it is preferably used in combination with a heat resistant glass tape, a polyimide tape or the like.

When a metal is used as the heat-resistant sheet, magnetic flux is generated not only in the iron core material but also in the metal sheet, and heat is generated due to the iron loss of the metal sheet itself, so that the core temperature becomes higher as it is excited at a high frequency. Raises the problem of increasing.
Therefore, it is important that the heat-resistant sheet has a small iron loss. From such a point of view, as the heat-resistant sheet, one having an electric resistance equal to or larger than that of the silicon steel strip which is the iron core material and having a thickness equal to or smaller than the thickness of the caustic steel strip. It is preferable to use.

In the present invention, the heat-resistant sheet may be in the form of tape or foil, and the form is not particularly limited. Further, the thickness of the heat resistant sheet is preferably in the range of 0.01 to 0.1 mm from the viewpoint of being wound and used.

The silicon steel strip constituting the iron core material is not particularly limited, and the Si content is 6.5.
%, A high-silicon-containing steel strip, a Si content of about 3%, an isotropic material, or an anisotropic material.

As the resin used in the present invention, a varnish can be used as in the case of a usual wound iron core, but it is not limited to this. Further, the method of applying the resin to the iron core material may be impregnation or application.

Since the wound iron core of the present invention is used in a high frequency range of 400 Hz or higher, it is suitable for applications where the temperature is B type or higher, and examples of such applications include an anode reactor.

Next, the manufacturing process of the iron core of the present invention will be briefly described for the case of using it as a cut core. First,
A silicon steel strip is wound around a winding frame many times to obtain an iron core material.
Next, this iron core material is charged into an annealing furnace and subjected to strain relief annealing in an inert atmosphere. Then, a resin such as varnish is impregnated or applied to this iron core material. In this case, a method that is usually used, that is, a method of impregnating an iron core material with a resin such as varnish using an autoclave and then baking it can be adopted. Then, a heat resistant sheet is wound. Thereafter, cutting, polishing, and etching are performed, and a cut core is manufactured through necessary inspections. In this case, it is possible to omit the steps of polishing and etching depending on the required performance.

The winding of the heat-resistant sheet used in the present invention is not limited to the above-mentioned impregnation or application of the resin, but it is preferably performed before or after the resin-impregnation or application step, or before or after the cutting step. The method for fixing the heat resistant sheet is not particularly limited, but a method of impregnating a resin such as varnish or the like is adopted. Further, the heat-resistant sheet does not necessarily have to be wound around the entire iron core material, and may be a part thereof.

Next, an example in which the wound iron core of the present invention is applied to a cut core will be described. First, FIG. 1 shows a conventional cut core. In the figure, A is a cut surface. FIG. 2 relates to the present invention, in which the cut core 10 in (a) is an iron core material 1.
The heat-resistant sheet 2 is wound around the leg portion in the vicinity of the cut surface A, and the cut core 10 ′ in (b) further has the heat-resistant sheet 3 wound around the top portion.

[0024]

Embodiments of the present invention will be described below. A high-frequency material, which is a 0.1 mm thick 6.5% Si silicon steel strip, is wound to form an iron core material, and a heat-resistant sheet is wound around the leg portion, and then the varnish is applied to the iron core material. Was impregnated. The heat resistant sheet was fixed to the iron core material by this varnish impregnation. After that, the wound iron core manufactured in this manner was cut into a cut core having a structure shown in FIG. Here, as the heat-resistant sheet, 0.0
A SUS304 tape having a thickness of 3 mm and a polyimide tape (Kapton tape) having a thickness of 0.025 mm were stacked and used.
For comparison, a cut core of the same shape without winding a heat resistant sheet was prepared as usual.

At a frequency of 10 kHz and a core temperature of 120 ° C.,
Change the magnetic flux density so that it becomes 150 ℃ and 180 ℃,
An energization test was carried out for 100 hours, and the state of the core was observed.
Table 1 shows the results. In Table 1, ∘ indicates that the core shape did not change, and x indicates that the cut surface was deformed and a gap was generated in the laminated surface.

[0026]

[Table 1]

As shown in Table 1, in Comparative Example, the core shape did not change at 120 ° C., but at 150 ° C. and 180 ° C., the cut surface was deformed and a gap was formed in the laminated surface. On the other hand, in the case of the example of the present invention, it was confirmed that the core shape did not change at any temperature up to 180 ° C.

[0028]

As described above, according to the present invention,
It is possible to obtain a wound iron core having excellent strength even at a high temperature exceeding the glass transition temperature of the resin used.

[Brief description of drawings]

FIG. 1 is a perspective view showing a normal cut core.

FIG. 2 is a perspective view showing a cut core according to an embodiment of the present invention.

[Explanation of symbols]

 1 ... Iron core material 2, 3 ... Heat-resistant sheet 10, 10 '... Cut core A ... Cut surface

Claims (6)

[Claims] 1. An iron core material formed by winding a silicon steel strip a plurality of times, a resin impregnated into or applied on the iron core material, and a heat-resistant sheet wound on the iron core material. A wound iron core with excellent strength. 2. The wound iron core according to claim 1, wherein the heat resistant sheet is a heat resistant glass sheet. 3. The wound iron core according to claim 1, wherein the heat resistant sheet is made of metal. 4. The wound iron core according to claim 3, wherein an insulator is interposed between the iron core material and the heat resistant sheet. 5. The wound iron core according to claim 1, wherein the heat resistant sheet has an outer layer made of a metal and an inner layer made of an insulator. 6. The heat-resistant sheet has an electric resistance equal to or higher than that of the iron core material and a thickness equal to or thinner than that of the silicon steel strip. The wound iron core according to claim 3 or 4.