JPS609652B2 - Manufacturing method of molded coil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a molded coil, and more particularly to a method of manufacturing a molded coil in which an electromagnetic winding is molded with resin and is provided with a ventilation duct for cooling the coil.

In large-capacity molded transformers that use molded coils made of electromagnetic windings molded with resin, "in order to cool the molded coils, the molded coils are arranged in a cylindrical shape concentric with the coils.
It is common to have a ventilation duct penetrating between both end faces of the molded coil in the koji direction.

Fig. 1 shows a molded coil with an attached ventilation duct.

In the figure, lb is the inner coil, la is the outer coil,
A pair of inner and outer coils la and lb wound in the same manner in the radial direction are stacked in two stages in the crosswise direction.
Then, the inner and outer coils lb and la are molded with resin 3, and a plurality of axially extending and penetrating holes are formed between the inner coil lb and the outer coil la in order to cool each coil during molding. A ventilation duct 2 is formed. The manufacturing process of the molded coil having such a configuration will be explained in more detail.

When manufacturing a molded coil, a ventilation duct mold is first installed during the winding process, and after the winding process is completed, the entire winding is installed into a resin injection mold (not shown), and then placed into the resin injection mold. Inject the resin and let it harden.

Once the injected resin has hardened, the resin injection mold is removed, and then the ventilation duct molding mold 4 is pulled out in the direction of the arrow as shown in FIG. In this way, a molded coil with a ventilation duct is manufactured, but since the ventilation duct 2 is formed by pulling out the ventilation duct mold 4, the surface of the ventilation duct 2 is made so that it does not interfere with pulling out the ventilation duct mold 4. It must be smooth and free of irregularities, and generally a precision-machined metal integral piece is used as the ventilation duct mold 4.

By the way, the heat inside the mold coil moves to the outer surface of the mold coil by conduction, and is dissipated by radiation from the outer surface into the air and air convection, so heat dissipation in the ventilation duct is mainly due to convection. It is known.

Therefore, the flow of air within the ventilation duct is important in order to increase the cooling effect of the mold coil. Air flow is generally divided into laminar flow and turbulent flow, and Figures 3a and 3b show the flow velocity distribution of air when laminar flow and turbulent flow flow inside the ventilation duct.

As is clear from the figure, when a laminar flow flows, the flow velocity a is high at the center of the ventilation duct, but becomes smaller as it approaches the wall surface of the ventilation duct. On the other hand, in the case of turbulent flow b, the flow velocity is high both in the center of the ventilation duct and near the wall surface. Since the molded coil is cooled by dissipating heat from the inner wall surface of the ventilation duct by convection, it can be seen that when the molded coil flows in a turbulent state with a high velocity near the wall surface, heat dissipation is extremely good and the cooling effect is improved. However, as mentioned above, since the inner wall surface of conventional ventilation ducts is formed smoothly, the air flow inside the ventilation duct is actually a laminar flow with poor heat dissipation.
We cannot expect much cooling effect from the molded coil.

In order to turbulently sulfurize the laminar flow, it is possible to force a large amount of air to flow using an electric fan or the like, but this is not preferable because the power consumption of the electric fan increases. The simplest method for disturbing the flow of air in a ventilation duct is to attach a protrusion to the wall surface of the ventilation duct in a portion perpendicular to the air flow, that is, the inner wall surface of the ventilation duct.

If projections are attached to the inner wall of the ventilation duct, the air flow around the projections will be disturbed and the heat dissipation effect will be significantly improved. However, in order to attach protrusions to the inner wall of the ventilation duct, it is necessary to use a ventilation duct mold with an uneven surface. It was difficult to pull out the ventilation duct mold after curing, so it was not put to practical use. The present invention has been made in view of the above-mentioned points, and its object is to provide a method for manufacturing a molded coil that can easily form irregularities on the inner wall surface of a ventilation duct using a ventilation duct molding die having an uneven surface. is to provide.

The present invention incorporates a coil and a ventilation duct molding mold having an uneven surface and forming a ventilation duct in the direction of the ball near the coil into a removable resin injection mold, and then inserts the resin into the resin injection mold. After injecting and curing the injected resin, the resin injection mold is removed, and the ventilation duct mold is deformed and removed, thereby achieving the initial objective.

The present invention will be described in detail below based on embodiments shown in the drawings.

The manufacturing method of the molded coil in the present invention is almost the same as that of the conventional method, but in the present invention, the ventilation duct molding mold is formed of a special material, and the process of deforming and removing the ventilation duct molding mold after the resin hardens is newly added. I'm joining.

FIG. 4 and FIG. 5 show an example of a ventilation duct molding die employed in the molded coil manufacturing method of the present invention.

The ventilation duct molding mold 41G in this example is polyethylene,
The ventilation duct mold 4 is made of a thermoplastic polymer material such as polypropylene, nylon, vinyl chloride, polyethylene terephthalate, polybutylene, or noryl, and has irregularities 7 of arbitrary shapes on its surface.

The ventilation duct molding mold 4 made of these thermoplastic polymers has a softening point of about 80°C to 180°C. This ventilation duct mold 4 is inserted into the winding during the winding operation, but since the temperature at this time is room temperature, the ventilation duct mold 4 has sufficient hardness and is not easily deformed. Moreover, the injected resin must have a primary curing temperature lower than the softening point of the thermoplastic polymer material used for the ventilation duct mold 4.
If left at this primary curing temperature, the injected resin will harden. After curing, the mold is removed as described above, but in this embodiment, the final step of pulling out the ventilation duct mold 4 is performed as follows. That is, after the injected resin has hardened, the mold coil is heated to a temperature higher than the softening point of the thermoplastic polymer used in the ventilation duct mold 4. Then, the ventilation duct molding die 4 becomes soft and in a fluid state, and can be easily removed from the mold coil, and uneven portions are easily formed on the inner wall surface of the ventilation duct. Therefore, turbulence is generated in the cooling air flowing in the ventilation duct, and the cooling effect of the molded coil can be significantly improved. Furthermore, although the above-described example uses a thermoplastic polymer material as the ventilation duct mold, it is also possible to use paraffin instead of the thermoplastic polymer material. Commercially available paraffin has a softening point of 40
It is distributed between qo and 18pi0, and its deformation and removal can be performed in exactly the same way as in the above-mentioned embodiment. (Hereinafter, thermoplastic polymers and paraffin are referred to as heat deformable materials.) Section S
The figure shows a second embodiment of the ventilation duct mold employed in the molded coil manufacturing method of the present invention.

The ventilation duct mold 4 in this embodiment is formed by filling a thin sheet material 5 made of metal, Teflon, or the like with a heat-deformable material 6. Since the thin sheet material 5 is thin, it can be mechanically deformed by itself, but since it is filled with the heating deformable material 6 inside, it does not deform much at least at room temperature and can withstand winding work. To deform and pull out the ventilation duct forming mold 4 in this embodiment formed in this way, the mold coil is heated to remove the heated deformable material 6, and then the thin sheet material 5 remaining in the duct is removed as shown in FIG. A rod-shaped object is inserted between the hardened resin 10 and the hardened resin 10 as shown by the arrow, and the thin sheet material 5 is deformed as shown by the broken line and then pulled out. Since the thin sheet material 5 has appropriate elasticity, it can return to its original shape after being pulled out, and can be used again by being filled with the heat-deformable material 6. Furthermore, in the ventilation duct forming mold 4 shown in FIG.
It is also possible to use a material that contracts in proportion to the magnitude of this mechanical force.

That is, since the material that contracts in proportion to its mechanical size has voids inside, if it is used alone, the injected resin will be impregnated into the inside, but this is prevented because it is sealed with the thin sheet material 5. It becomes available for use. Materials whose volume changes in proportion to the magnitude of mechanical force include foamed polymers that contain many bubbles inside, nonwoven fabrics with high specific gravity and small nonwoven fabrics made by gathering fibers at low density, and wrinkled materials that create voids when stacked. There are fibers, etc.
If a material that shrinks in volume due to these mechanical forces is used, it will be slightly deformed during the winding process, but after the injected resin has hardened, an even larger mechanical force is applied and the material deforms greatly, causing the ventilation duct mold to It is possible to pull it out. (Hereinafter, materials that shrink in volume due to mechanical force will be referred to as mechanically deformable materials.
) By the way, if the above-mentioned thermally deformable material and mechanically deformable material are used repeatedly several times, they will inevitably become strained and difficult to use.

Therefore, for the purpose of reducing consumption, it is effective to use a core village in the center of the ventilation duct mold. Examples of this are shown in FIGS. 8 and 9. The ventilation duct molding die shown in the figure is also employed in the method of manufacturing a molded coil, and both ventilation duct molding molds 4 are formed with a core material 8 made of a plate material. Of course, the surface has uneven portions 7.
The core material 8 can be made of metal or Teflon, which has excellent heat resistance. The ventilation duct forming mold 4 shown in FIG. 8 has a heat deformable material 6 attached around a core material 8.
is constructed by winding a tape-like material. When manufacturing a mold coil using such a ventilation duct mold 4, the process is similar to that described above, but when pulling out the ventilation duct mold 4 as in this example, the mold coil is heated after the resin hardens, and the heat-deformed material is heated. The core material 8 may be taken out after softening the core material 6 and removing the fluid. Further, the ventilation duct forming mold 4 shown in FIG. 9 has a heat deformable material 6 attached around the core village 8 and a thin leaf material 5 attached to the outside of the heat deformable material 6. When extracting the ventilation duct mold 4 as in this example, the process is the same as the example shown in FIG. 8 until the core material 8 is removed, and then when the thin sheet material 5 is removed, it is removed as shown in FIG. 7. Note that the same effect can be obtained even if a mechanically deformable material is used in place of the heat deformable material 6 in this example. If a mechanically deformable material is used, the method for deforming and removing it is the same as that described with reference to FIG.
By manufacturing a molded coil using the ventilation duct molding die shown in FIGS. 8 and 9, irregularities are formed on the inner wall surface of the ventilation duct, and the cooling effect is significantly improved.

In addition, in the case shown in FIGS. 8 and 9, the core material 8 can be bent with a plate material to match the curvature of the ventilation duct, but instead of the plate material, a round twill 11 can be used as shown in FIG. Also good.

Furthermore, not only a round bar but also a cylindrical core material, that is, a circular core material, can be used instead. In this case, unlike the case of using plate materials, there is no need to adjust the curvature of the ventilation duct, and there is an advantage that an arbitrary curvature can be configured using several round rods or cylinders. Next, FIG. 11, FIG. 12, and FIG. 13 show a molded coil manufactured by the manufacturing method of the present invention using the ventilation duct molding die described so far.

As is clear from the figure, the molded coil manufactured by the manufacturing method of the present invention is molded coil 1 in all cases.
Since the wall surface 3a of the ventilation duct 2 inside has the uneven portion 9, air flows as a turbulent flow near the wall surface of the ventilation duct 2, and the cooling efficiency of the ventilation duct is significantly improved. The table shows the temperature of the internal electromagnetic winding during forced air cooling of a molded coil with an uneven ventilation duct manufactured using the molded coil manufacturing method of the present invention and a molded coil with a ventilation duct with a flat wall manufactured by the conventional technology. .

These conditions are exactly the same except for the shape of the ventilation duct wall surface. As is clear from the results in the table, the temperature rise of the molded coil with ventilation ducts produced by the molded coil manufacturing method of the present invention is significantly smaller than that of the molded coil with ventilation ducts produced by the conventional technology.

From this, it will be seen that the cooling performance of the molded coil with ventilation duct made by the method of manufacturing the molded coil of the present invention is significantly improved compared to that of the molded coil according to the prior art. Although the method has been described with an inner coil and an outer coil arranged, it does not necessarily have to be two coils. For example, even if there is only one coil, cooling ventilation is needed when molding it. Even when it is desired to form a duct, the same can be done, and the number of coils is not limited.

Furthermore, the step of deforming and removing the ventilation duct mold after the resin has been cured, which is the key point of the manufacturing method of the present invention, also includes the step of heating and softening the heat-deformable material such as the thermoplastic polymer material, and then fluidizing and removing it. It is something that

According to the method for manufacturing a molded coil of the present invention as described above, the coil is housed in a removable resin injection mold, and the ventilation duct molding mold has an uneven surface and forms ventilation ducts in all directions of the axis near the coil. After that, a resin is injected into the resin injection mold, and after the injected resin is cured, the resin injection mold is removed, and the ventilation duct mold is deformed and removed. However, even if an uneven ventilation duct molding mold is used, the ventilation duct molding mold can be easily removed from the mold coil by deforming it after the injected resin has hardened, and without causing any special effects on other parts, which was a long-awaited goal. The wall surface of the ventilation duct can be easily formed into an uneven shape, and the effect is great.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional perspective view showing a conventional molded coil;
The figure is a cross-sectional perspective view of the mold coil before the ventilation duct mold is removed, Figures 3a and 3b are diagrams showing the flow velocity distribution state of air flowing inside the ventilation duct, and Figure 4 is a diagram showing the mold coil manufacturing method of the present invention. FIGS. 5 and 6 are perspective views showing other embodiments of the ventilation duct mold used in the method of manufacturing a molded coil of the present invention; FIGS. FIG. 7 is a diagram illustrating the process of taking out the ventilation duct mold, and FIGS. 8, 9, and 10 are still other embodiments of the ventilation duct mold employed in the method of manufacturing a molded coil of the present invention. FIG. 11, FIG. 12, and FIG. 13 are partial perspective views of a molded coil manufactured by the molded coil manufacturing method of the present invention. 1... Coil, 2... Ventilation duct, 3...
Resin, 3a... Ventilation duct wall surface, 4... Ventilation duct mold, 5... Thin leaf material, 6... Heat deformable material, 7, 9... Unevenness Part, 8... Core material, 1
1... Maruhane. Mine' figure 2 figure younger brother 3 figure 4 figure 5 figure 5 figure 7 figure 8 fist? Younger brother noo Drawing hair// Drawing younger brother No. 2

Claims (1)

[Scope of Claims] 1. A coil and a ventilation duct molding mold having an uneven surface and forming a ventilation duct in the axial direction near the coil are incorporated into a removable resin injection mold, and then the coil is assembled into the resin injection mold. A method for manufacturing a molded coil, characterized in that the resin injection mold is removed after the injected resin is cured, and the ventilation duct mold is deformed and removed. 2. The ventilation duct mold is formed of a heat-deformable material with a higher softening point than the injection resin, and after the injection resin is cured at the primary curing temperature, the mold coil is heated to a temperature higher than the softening point of the ventilation duct mold. 2. The method of manufacturing a molded coil according to claim 1, wherein the heated deformable material is softened and removed by flowing. 3. The ventilation duct mold is formed of a heat-deformable material having a higher softening point than the injected resin, and a thin sheet material having elasticity that is wound around the heat-deformable material, and the injected resin is cured at the primary curing temperature. After that, the temperature of the molded coil is raised above the softening point of the ventilation duct mold to soften and remove the heated deformable material, and then the thin sheet material is deformed and removed, and the ventilation duct mold is deformed and removed. A method of manufacturing a molded coil according to claim 1, characterized in that: 4. The ventilation duct mold is made of a mechanically deformable material that shrinks in volume due to mechanical force, and a thin sheet material having elasticity that is wound around the mechanically deformable material, and the injected resin is cured. Afterwards, a mechanical force is applied to the mechanically deformable material to remove the deformation, and then the thin sheet material is deformed and removed, and the ventilation duct mold is deformed and removed. A method for manufacturing a molded coil according to item 1. 5. A patent characterized in that a core material extending in the axial direction is provided approximately at the center of the heat-deformable material constituting the ventilation duct mold, and the core material is taken out after the heat-deformable material is flowed and removed. A method for manufacturing a molded coil according to claim 2 or 3. 6 A core material extending in the axial direction is provided approximately at the center of the mechanically deformable material constituting the ventilation duct mold, and the core material is taken out after applying mechanical force to the mechanically deformable material and removing the deformation. 5. A method for manufacturing a molded coil according to claim 4.