JPS6367283B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to an insulated wire, and more specifically, an insulated wire for forming a composite bonded conductor by fusing or bonding mutually insulated conductors with rectangular cross sections in parallel. It concerns electric wires.

Traditionally, coils for electric induction equipment, motors, etc. are made by winding insulated wires such as enamelled wires or fiber-wound wires into a predetermined shape, then impregnating them with varnish and bonding the wires together to integrate them. It was hot.

However, in recent years, in an effort to reduce the man-hours required for the varnish impregnation process and improve workability, self-bonding electric wires have been used that bond the wires together only by heating without impregnating them with varnish. It's here.
Such self-fusing wires were generally round wires, but recently, thin rectangular self-fusing wires have been used in electric induction equipment such as transformers and reactors to reduce eddy current loss in conductors. Adhesive wires have come to be used. Application examples using such flat wires include Utility Model Publication No. 53-28475 and Utility Model Publication No. 57
− Composite paper windings disclosed in Publication No. 17681, respectively;
Alternatively, there is a composite insulated wire shown in Japanese Utility Model Publication No. 47-43292. In each of these application examples, as shown in Figure 1, a plurality of self-adhesive electric wires A and B are connected in parallel, each of which has a rectangular conductor 1 coated with an enamel coating 2 and further coated with an adhesive 3. and combine,
An integrated bonded conductor was obtained by cooling after heating.

However, when the cross-sectional shape of the conventional bonded conductor formed as described above is drawn schematically as shown in Figure 1, the adjacent self-bonding wires A and B appear to be bonded uniformly. However, the actual effective bonding area is 20-30% of the total bonding area.
The reality is that the bonding strength is only moderate, and as a result, there is a drawback that sufficient bonding strength cannot be obtained.

In order to consider the causes of such defects, Fig. 2 shows a trace diagram of a micrograph of a cross section of a conventional commercially available self-bonding electric wire. The thickness of the enamel coating 2 is not uniform, and the coating 2a at the corners of the conductor 1 is quite thick. Therefore, as is clear from the somewhat exaggerated model diagram in Figure 3, only the corner portions 2a of the self-bonding wires A and B are joined, and most of the other flat parts are not joined. This has been clarified. Naturally, this was the cause of not being able to obtain the desired bonding strength.

The enamel coating 2 applied to the rectangular conductor 1 is formed by applying enamel varnish about 10 times and baking it. , coating 2
It has been considered difficult to form a uniform enamel coating because the thickness of the enamel is thicker at the corners and, conversely, at the flat areas.

On the other hand, when the conductor is rectangular, the electric field concentrates at the corners, so when focusing on the withstand voltage of the insulating coating, it is preferable that the coating be thicker at the corners. In some cases, the fusible electric wire allowed a thick coating to be applied to the corner portions as shown in FIG. Then, Utility Model Application Publication No. 55-12167,
This type of insulation, such as the self-adhesive insulated wire described in Japanese Patent Publication No. 55-47065, the self-bonding insulated wire described in Japanese Patent Publication No. 57-43963, or the application example of the self-bonding wire described above, Although there are relatively many inventions and ideas related to electric wires, there is no mention or consideration of the effective bonding area.

Therefore, this invention was made in view of the above circumstances, and an object of the present invention is to provide a self-fusion and self-adhesive insulated wire that dramatically increases the effective joint area and can be reliably joined. It is something to do.

Another object of the present invention is to reduce the thickness of the corners where the varnish is applied thicker than the flat parts by using a rectangular conductor with a cross section thinner than the thickness of the flat parts, so that the enamel coating on the joint surface becomes flat. It is to provide electric wires.

An embodiment of the present invention will be described below with reference to FIG. In the figure, a corner portion 1a of a rectangular conductor 1 shown by a dotted line is made thinner to form a corner portion 1b shown by a solid line. In this way, the thickness t ₁ of the flat part 1c
Conductor 1 with the thickness t ₂ of the corner part 1b smaller than
An enamel coating 2 is formed on the outer surface of the enamel.

With the above configuration, the bulge of the enamel coating 2 at the corner portion 1b is substantially eliminated, and the bonding surface becomes flat. Similar to the conventional method, an appropriate adhesive is applied to the outer surface of the coating 2. In this way, the effective bonding area can be significantly increased compared to conventional ones, and the bonding strength can be improved.

On the other hand, it is easy to understand that when applying an enamel having a characteristic of raising the flat part, the cross-sectional shape should be such that the thickness of the flat part is smaller than the thickness of the corner part.

As described above, a rectangular conductor with a cross-sectional shape in which the flat part and the corner part have different thicknesses can be easily manufactured by adapting the shape of the die for drawing the conductor to the above-mentioned cross-sectional shape. .

Note that the adhesive is applied to the outer surface of the enamel coating 2, but even if the adhesive is applied thickly at the corner portion 1b, the adhesive will temporarily melt when heated and blend into the adhesive surface. Since the coating thickness is generally thinner than the enamel coating, its effect on the effective bond area is negligible.

Here, enamel refers to polyvinyl formal, polyester, polyamide, polyurethane, epoxy resin, etc., and adhesive refers to self-fusing materials such as polyester, polyamide, butyral resin, etc. that melt when heated and solidify when cooled. This refers to heat-curable self-adhesive materials such as B-stage epoxy resins and phenolic resins that melt, react, and harden when heated.

In the above embodiments, an enamelled wire in which a paint-type varnish was applied to a rectangular conductor was described. However, even when using a varnish for electrodeposition as seen in the method for manufacturing a water-dispersed polyurethane varnish for electrodeposition described in Japanese Patent Publication No. 52-32399, the corners are thickly electrodeposited, so this invention It can also be applied and the same effect can be achieved.

As described above, the present invention has the effect of significantly increasing the bonding strength by making the portion of the rectangular conductor to which the enamel is thickly applied thinner in advance so that the bonding surface becomes flat.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional bonded conductor, Figure 2 is a cross-sectional view of the main part traced from a microscopic cross-sectional photograph of the conventional type, and Figure 3 is a sectional view of a bonded conductor to explain the drawbacks of the conventional type. FIG. 4 is a sectional view of a main part of an embodiment of the present invention. 1...Conductor, 1a, 1b...Corner part, 1c
... Flat part, 2 ... Enamel coating, 3 ... Adhesive. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. An insulated wire formed by forming a varnish coating on a rectangular conductor and further applying an adhesive, and connecting a plurality of rectangular conductors in parallel to form a composite bonded conductor, An insulated wire comprising the rectangular conductor having a cross-sectional shape in which the thickness of the plane part and the thickness of the corner part are different. 2. The insulated wire according to claim 1, wherein the varnish is an enamel varnish. 3. The insulated wire according to claim 1, wherein the varnish is an electrodeposition varnish. 4. The insulated wire according to claim 1, wherein the varnish has a characteristic that the thickness of the coating film differs between the flat part and the corner part. 5. The insulated wire according to claim 1, wherein the adhesive is a self-bonding adhesive that melts by heating and solidifies by cooling. 6. The insulated wire according to claim 1, wherein the adhesive is a thermosetting self-adhesive adhesive.