JP2002222719A - Manufacturing method of molded coil and molded coil - Google Patents

Abstract

(57) [Summary] An object of the present invention is to suppress occurrence of cracks in a molded coil without deteriorating workability in manufacturing a molded coil. SOLUTION: The bobbin 6 forms an intermediate layer 2 in which a fibrous glass nonwoven fabric mat 2A is wound between an inner peripheral layer 1 and an outer peripheral layer 3, and is used for resin molding of a winding 7A formed on the bobbin 6. Since the intermediate layer 2 is not molded, the molded coil 7
Since the thermal stress during the heat curing of B and the operation of the transformer can be absorbed by the fibrous glass nonwoven fabric mat 2A, the occurrence of cracks in the mold coil 7B can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded coil, and more particularly, to a bobbin made of a prepreg material (hereinafter referred to as a prepreg material) in which a fibrous glass cloth contains an epoxy resin composition and a fibrous glass nonwoven fabric mat. The present invention relates to a method of manufacturing a used mold coil.

[0002]

2. Description of the Related Art A bobbin is generally used to wind a conductor when a molded coil for a molded transformer is manufactured. Conventionally, this bobbin is a mold processed into a cylindrical shape made of wood or metal as described in JP-A-57-187921, or a prepreg material is previously formed into a cylindrical shape as described in Japanese Patent No. 2645105. The one molded (made) into a shape is used.

A wooden or metal bobbin has a mechanical strength enough to withstand the tightening force of the winding, but on the other hand, because of its heavy weight, the bobbin moves during the production of a molded coil or after the epoxy resin composition is cured. There is a drawback that requires labor such as disassembly of the mold.

On the other hand, in order to solve this drawback, there is known a method in which a prepreg material formed into a cylindrical shape in advance is used as a bobbin. This method does not require a wooden or metal mold when manufacturing the coil, and is relatively lightweight, so that the coil can be moved smoothly. In addition, since the bobbin plays the role of a mold, there is an advantage that the operation of disassembling and cleaning the bobbin is completed in a short time after the production of the molded coil.

However, even in this method, a conductor such as aluminum or copper is wound directly around the bobbin when the molded coil is manufactured. Therefore, the difference in the coefficient of linear expansion between the bobbin and the conductor causes the epoxy resin composition to be hardened by heat. There is a problem that thermal stress occurs during operation of the transformer and the transformer, and cracks occur in the molded coil.

As a measure to prevent the occurrence of cracks due to such thermal stress, as described in JP-A-8-191023, a fibrous glass nonwoven fabric mat is wound around the outer periphery of the bobbin and then the conductor is wound. A method is known in which a small gap is provided between a bobbin and a conductor to reduce thermal stress.

[0007] However, although this method suppresses the cracks generated on the bobbin during the production of the molded coil, in order to resin-mold the fibrous glass nonwoven fabric mat during the production of the molded coil, it is necessary to heat the epoxy resin composition or to operate the transformer. At times, thermal stress cannot be sufficiently absorbed, and the problem that cracks occur in the molded coil has not been solved.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a molded coil which can improve the workability in producing the molded coil and suppress the occurrence of cracks in the molded coil.

[0009]

A bobbin according to the present invention comprises an intermediate layer in which a fibrous glass nonwoven fabric mat is wound between an inner peripheral layer and an outer peripheral layer so as to absorb thermal stress during energization of a molded coil. When the coil wound around the bobbin is formed by resin molding to form a molded coil, the intermediate layer is not molded. Since it can be absorbed by the mat, the above-mentioned object can be achieved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to FIG.
This will be described with reference to (A), (B), (C) and FIG. The bobbin 6 applied to the molded coil 7B of the present invention will be described below. FIG. 1A is a perspective view in which the configuration of the bobbin 6 is partially sectioned. 1 is an inner peripheral layer, 2 is an intermediate layer, 3 is an outer peripheral layer, and 4 is a cylindrical mold.

The bobbin 6 is manufactured by winding a prepreg material at least once or more to form an inner peripheral layer 1, and winding a fibrous glass nonwoven fabric mat 2 A at least once or more to form an intermediate layer 2. The outer layer 3 is formed by winding a prepreg material at least once thereon, and after heating and curing, a mold 4 is formed.
Is removed, and the bobbin 6 is manufactured.

As described above, the bobbin 6 is composed of the inner layer 1, the intermediate layer 2, and the outer layer 3. The inner peripheral layer 1 is formed by winding a prepreg material containing an epoxy resin composition on the fibrous glass cloth 1A so as to withstand the tightening force when the conductor is wound on the bobbin 6. The intermediate layer 2 is formed by winding a fibrous glass nonwoven fabric mat 2A around the inner peripheral layer 1 so as to absorb thermal stress during energization when the mold coil 7B is cured. The outer peripheral layer 3 retains the shape of the intermediate layer in the intermediate layer 2, and also contains the epoxy resin composition in the fibrous glass cloth 3 </ b> A in order to prevent the injected epoxy resin composition 11 from entering the intermediate layer 2. Wrapped prepreg material.

The function of the conventional bobbin is to withstand the tightening force when the conductor 7 is wound around the inner peripheral layer 1. The intermediate layer 2 absorbs expansion of the inner peripheral layer 1 caused by heating, and has a role of relieving thermal stress generated in the mold coil 7B. The outer peripheral layer 3 plays a role of fixing and bonding for preventing the intermediate layer 2 from falling off and out of shape.

As described above, the point that the bobbin of the present invention is constituted by three layers having the above-described effects is that the prepreg material 14 shown in FIG. This is a major difference from the conventional bobbin 12 composed of a single layer.

If the thickness of the outer peripheral layer 3 is too large, expansion due to heat becomes large and the effect of the present invention is hardly exerted. Therefore, it is preferable to make the outer layer 3 as thin as possible. The epoxy resin composition contained in the prepreg material is not particularly limited as long as it is a resin composition containing, for example, an epoxy resin as a main component and being cured by heating or the like.

Further, the fibrous glass cloth 1 shown in FIG.
A and 3A are not particularly limited as long as they are a structure in which a plurality of bundled glass fibers are woven in a cross shape. The fibrous glass nonwoven fabric mat 2A of FIG. 1B is not particularly limited as long as it has a structure in which glass fibers are entangled randomly. The fibrous glass nonwoven fabric mat 2A is made of a fibrous glass nonwoven fabric mat 2A in accordance with elongation and shrinkage of conductors, windings and resin due to thermal stress.
A functions to expand and contract in the directions of arrows X and Y.

By applying the above-described bobbin 6 of the present invention to the molded coil 7B, it is possible to shorten the manufacturing time of the molded coil 7B and to reduce the thermal stress generated in the molded coil 7B to suppress the occurrence of cracks. Is obtained. Hereinafter, the present invention will be described specifically with reference to examples. (Example 1) An example of manufacturing a molded coil 7B according to the present invention will be described. First, the bobbin 6 of the present invention applied to the molded coil 7B of the present invention was manufactured by the method described below. FIGS. 1A, 1B, and 1C are perspective views in which the configuration of the bobbin 6 used in the first embodiment is partially sectioned.
It is a top view of the member used for (A). 1 is an inner peripheral layer, 2 is an intermediate layer, 3 is an outer peripheral layer, and 4 is a cylindrical mold.

As shown in FIGS. 1A, 1B and 1C, the bobbin 6
Is formed into a cylindrical mold 4 by winding a prepreg material containing an epoxy resin composition into a fibrous glass cloth 1A five times to form an inner peripheral layer 1, and a fibrous glass nonwoven fabric mat 2A is formed thereon once. The intermediate layer 2 is formed by winding, and a prepreg material containing an epoxy resin composition in a fibrous glass cloth 3A is further wound once thereon to form the outer layer 3, and then the prepreg material is heated. Was cured, and the cylindrical mold 4 was finally removed to produce a bobbin 6.

Next, the winding 7A is connected to a winding machine as shown in FIG.
After setting the bobbin 6 on 5, the conductor 7 coated with an electrical insulator and the interlayer insulator 8 are alternately wound, and one end of the outer insulating layer 9 is brought into close contact with the flange 10 on its outer peripheral side. It was made in about 40 minutes by winding.

Further, a method of manufacturing the molded coil 7B of the present invention will be described. FIG. 3 is a schematic cross-sectional view of a part of a molded coil 7B of the present invention manufactured using the winding 7A. 6 is a bobbin, 7 is a conductor, 8 is an interlayer insulator, 9 is a peripheral insulating layer, 10 is a flange, and 11 is an epoxy resin composition.

As shown in FIG. 3, the winding 7A is heated at 170 ° C. for 4 hours to dry the winding 7A and harden the outer peripheral insulating layer 9. Then, the space surrounded by the bobbin 6 and the outer insulating layer 9 and the conductor 7
And epoxy resin composition 1 in a space surrounded by interlayer insulator 8
After impregnating and injecting 1 and heating and hardening at 100 ° C for 5 hours, the flange 10 was removed.
It was cooled to room temperature over 12 hours to produce a molded coil 7B.

In this embodiment, the molded coil 7B
Applied the same voltage as during the operation of the transformer, and the temperature of the mold coil 7B rose to about 150 ° C. According to the elongation and contraction of the winding 7A due to the thermal stress, the fibrous glass nonwoven fabric mat 2A of the intermediate layer 2 is moved in the direction of the arrow X, as shown in FIG.
No cracks were generated because of expansion and contraction in Y. Further, when the molded coil 7B was cooled, no crack occurred in the molded coil 7B even when the fibrous glass nonwoven fabric mat 2A contracted in the arrow direction Y. No cracks occurred during heat curing and cooling during production of the molded coil.

Further, in each of the steps up to the completion of the manufacture of the winding 7A and the molded coil, the work can be continuously performed without replacing the bobbin 6, so that the manufacturing time of the winding 7A is shorter than that of Comparative Example 2 described later. It can be shortened from about 60 minutes to about 40 minutes to two thirds. (Comparative Example 1) Next, an example in which a molded coil 7Y is manufactured by a conventional method will be described. FIG. 4 is a perspective view in which a part of the conventional bobbin 12 used in Comparative Example 1 is sectioned. After winding the prepreg material 14 around the cylindrical mold 4 six times,
The epoxy resin composition contained in the prepreg material was cured by heating to produce a bobbin 12. Bobbin 12 to mold 4
Removed more.

Next, the method of manufacturing the winding 7X is as shown in FIG.
The bobbin 12 was set in the mold 4A of the winding machine 5, and the winding 7X was manufactured in the same manner as in Example 1 in about 40 minutes.

FIG. 6 is a schematic diagram partially showing the configuration of a molded coil 7Y produced by using the winding 7X. 4
A is a metallic mold, 7 is a conductor, 8 is an interlayer insulator, 9 is a peripheral insulating layer, 10 is a flange, 11 is an epoxy resin composition, and 12 is a conventional bobbin. As shown in FIG. 6, the molded coil 7Y of Comparative Example 1 was manufactured in the same procedure as in Example 1.

Although the comparative example 1 could be manufactured in the same time as the molded coil of the example 1, the structure was not provided with a fibrous glass nonwoven fabric mat. Thermal stress was generated between the conductors 7, and cracks occurred near the interface between the bobbin 12 of the molded coil 7Y and the conductor 7. (Comparative Example 2) Further, Comparative Example 2 also has the same bobbin 1 as Comparative Example 1.
2, an example in which the molded coil 7Y is manufactured by a method obtained by improving the comparative example 1 will be described. As shown in FIG. 7, a bobbin 12 similar to that of Comparative Example 1 is set in a mold 4A of a winding machine 5, and a fibrous glass nonwoven fabric mat 13 is manually placed around the bobbin 12 to prevent cracks. Winding,
The seam of the fibrous glass nonwoven fabric mat 13 was fixed with an insulating tape so as not to fall off, and thereafter the winding 7X was manufactured in the same manner as in Example 1 in about 60 minutes.

FIG. 8 is a schematic diagram showing a cross section of a part of a molded coil 7Y manufactured using the winding 7X of the comparative example 2 obtained above. 4A is a metallic mold, 7 is a conductor, 8 is an interlayer insulator, 9 is a peripheral insulating layer, 10 is a flange, 11 is an epoxy resin composition, 12 is a conventional bobbin, and 13 is a fibrous glass nonwoven fabric mat. . The fibrous glass nonwoven fabric mat 13 was resin-molded together when the molded coil 7Y was manufactured. Others were produced in the same manner as in Example 1.

When a voltage equivalent to that during the operation of the transformer is applied, the molded coil 7Y
Increased to about 150 ° C. Since the epoxy resin composition is impregnated in the fibrous glass nonwoven fabric mat 13 in accordance with the elongation (shrinkage during cooling) of the winding 7X due to thermal stress, the mold coil 7Y does not expand sufficiently (shrinkage during cooling). Cracks occurred. Also, cracks occurred in the molded coil 7Y during cooling.

Further, since a work process such as winding the fibrous glass nonwoven fabric mat 13 around the bobbin 12 provided in the mold 4A was extra than in the first embodiment, the time required for manufacturing the winding 7X was 1.5 times that in the first embodiment. (About 60 minutes). Further, the time required for manufacturing the winding 7X was longer than the time required for manufacturing the winding of the present invention, because the mold was changed when the bobbin 12 was manufactured and when the winding 7X was manufactured.

[0030]

According to the present invention, since the thermal stress generated in the molded coil can be reduced, the occurrence of cracks can be suppressed, and the time required to produce the coil for the molded coil can be reduced by three times.
The effect was obtained that it could be shortened to 2/2.

[Brief description of the drawings]

FIG. 1 is a diagram showing a part of a bobbin according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a step of manufacturing a winding by a winding machine using the bobbin of FIG.

FIG. 3 is a schematic sectional view of a molded coil manufactured using the windings of FIG. 2;

FIG. 4 is a perspective view showing a cross section of a part of a conventional bobbin.

FIG. 5 is a schematic sectional view showing a step of manufacturing a winding by a winding machine using the bobbin of FIG. 4;

FIG. 6 is a schematic sectional view of a molded coil manufactured using the windings of FIG.

FIG. 7 is a schematic sectional view showing a step of manufacturing a winding by a winding machine using a conventional bobbin.

FIG. 8 is a schematic sectional view of a molded coil manufactured using the windings of FIG. 7;

[Explanation of symbols]

1 ... inner peripheral layer, 1A ... fibrous glass cloth, 2 ... intermediate layer, 2
A: fibrous glass nonwoven fabric mat, 3: outer peripheral layer, 3A: fibrous glass cloth, 4, 4A: die, 5: winding machine, 6: bobbin, 7: conductor, 7A: winding, 7B: molded coil , 8
... interlayer insulator, 9 ... outer peripheral insulating layer, 10 ... flange, 11 ... epoxy resin composition, 12 ... bobbin, 13 ... fibrous glass nonwoven fabric mat, 14 ... prepreg material.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Izumi Gumi 46 Tomioka, Nakajo-cho, Kitakanbara-gun, Niigata Prefecture 1 within the Industrial Equipment Group, Hitachi, Ltd. (72) Inventor Tomohiro Kaizu Nakajo-cho, Kitakanbara-group, Niigata 46-1 Tomioka, F-term within the Industrial Machinery Group of Hitachi, Ltd. (reference) 5E044 AA07 AC01 AC06 BA01 CA02

Claims (3)

[Claims] 1. A method of manufacturing a molded coil in which an epoxy resin composition is cast into a winding in which a conductor covered with an electrical insulator is wound around a bobbin, wherein the bobbin has a tightening force when the conductor is wound. An inner peripheral layer in which a prepreg material containing an epoxy resin composition is wound on a fibrous glass cloth for withstanding a fibrous glass cloth, and a fibrous glass nonwoven fabric mat for absorbing thermal stress wound on the inner peripheral layer. An intermediate layer having an outer layer having a prepreg material containing an epoxy resin composition in a fibrous glass cloth for maintaining the shape of the intermediate layer wound around the intermediate layer, wherein the epoxy resin composition A method of manufacturing a mold coil, wherein the object is heated and cured to manufacture the bobbin, and the epoxy resin composition is molded on the winding wound around the bobbin to form a mold coil. . 2. A molded coil having a winding in which a conductor covered with an electrical insulator is wound around a bobbin, and an epoxy resin composition layer cast into the winding, wherein the bobbin is used when the conductor is wound. An inner layer wound with a prepreg material containing a thermosetting resin in a fibrous glass cloth so as to withstand a tightening force, and a fibrous glass nonwoven fabric for absorbing the thermal stress wound on the inner layer An intermediate layer having a mat, and an outer peripheral layer wound with a prepreg material containing a thermosetting resin in a fibrous glass cloth for maintaining the shape of the intermediate layer wound around the intermediate layer. A molded coil. 3. The method of manufacturing a molded coil according to claim 1, wherein the thickness of the intermediate layer is smaller than that of the inner layer and larger than that of the outer layer.