JPH0226365B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a transformer case with a novel coating,
Regarding the painting method.

[Technical background and problems of the invention]

Generally, heat sinks of various configurations are attached to the case of a power distribution transformer. For example, U-shaped curved heat dissipation pipes are welded to the top and bottom of the transformer case side plates to communicate with the inside of the case, or the case side plates themselves are continuously bent into a wave shape to form heat dissipation fins. Furthermore, heat dissipation fins formed by continuously bending a band-shaped metal plate into a wave shape are welded to the outer periphery of the case side plate, or multiple heat dissipation fins formed by bending a metal plate into a V shape are attached to the case side plate. Those that are arranged and welded are used.
When painting a transformer case equipped with a heatsink as described above, in the case of a transformer case equipped with the first two heatsinks, a heatsink fin or heatsink tube integrally formed with the case side plate is added to the surface of the transformer case equipped with the first two heatsinks. Since only the surface is protruding, the painting process can be performed relatively well. However, the latter two types of heat sinks (i.e., heat dissipation fins made by continuously molding a metal strip into a corrugated shape are welded to the case, or multiple heat dissipation fins made by bending a metal plate into a V shape are welded to the case). In transformer cases with Since the heat dissipation fin itself is hollow, the surface of the case corresponding to the fin cannot be sufficiently coated, and this tendency is particularly strong on the back side of the corrugated top of the heat dissipation fin.
Over the years, rust has formed and there is a risk that some of the heat dissipation fins may corrode and be damaged. For this reason, when painting a transformer case to which corrugated fins are attached, the process has been carried out according to the schematic process diagram shown in FIG. In other words, the painting of transformer cases can be roughly divided into the undercoating process (corrosion-resistant treatment) and the top-coating process (weathering treatment), as shown in Figure 5. Apply the undercoat and topcoat of paint one by one through a spray gun on the back side of the heat dissipation fins, which are formed in a wave shape.
I went there several times. Therefore, the painting process is extremely time-consuming and labor-intensive, and since the back sides of the heat dissipation fins are spray-painted one by one, it is extremely difficult to automate the painting process.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks and provides a coating process with excellent corrosion resistance and weather resistance without spray painting the back side of the heat dissipation fins when painting a transformer case equipped with wave-shaped heat dissipation fins. The purpose of the present invention is to provide a transformer case coated with paint and a method for painting the transformer case.

[Summary of the invention]

In the process of undercoating a transformer case, which requires corrosion resistance, the present invention involves immersing the transformer case in an electrolytic paint solution made of water-soluble resin paint, using the transformer case as one electrode, and using the other separately provided electrode. By applying direct current between the electrodes, resin paint is deposited on the surface of the transformer case and on the inside of the corrugated heat dissipation fins attached to the case to form an electrodeposition film, which is called electrodeposition coating. An object of the present invention is to provide a transformer case with excellent corrosion resistance and weather resistance by performing electrostatic coating in the top coating process that requires coating, and a method for coating the transformer case.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

Reference numeral 1 designates a transformer case for power distribution, in which a band-shaped metal plate is formed into a cylindrical shape by well-known roll processing, the joints at both ends are butted or overlapped, and welded together by welding. At this time, the mounting holes 2 for mounting the primary and secondary bushings on the side plate of the case 1 are formed in advance by drilling the mounting holes 2 at predetermined positions in the metal plate and then performing roll processing. 3 is a circular inverted dish-shaped bottom plate welded to one open end of the transformer case 1 in a "raised bottom"shape; 4 is a corrugated heat dissipation fin attached to the side plate of the transformer case 1; 4 is a band-shaped metal plate bent into a V-shape and arranged in a wave shape on the side plate of the case 1. Each of these heat dissipation fins 4 has a point approximately at the center in the vertical direction, as shown in FIG. One small-diameter through hole 5 (approximately 4 to 7 mm in diameter) is bored on the side surface near the .
It goes without saying that the through holes 5 are formed to a size that does not obstruct the flow of air passing through the heat dissipation fins 4 and impair the cooling effect of the transformer.

Next, a case where the transformer case 1 is painted will be described.

The painting process of the transformer case 1 is carried out in the order shown in the schematic process diagram of FIG.

That is, the transformer case 1 is shot blasted, the surface of the case 1 is treated with a phosphoric acid/zinc solution, the case 1 is then heated and dried at 100 to 120°C, and then the undercoat of the case 1 is applied. Electrodeposition coating is performed as follows. Regarding this electrodeposition coating process, please refer to the 3rd page.
This will be explained using figures. The case 1, which has been surface-treated and dried, is suspended from a conveyor 7 via a hook 6 and conveyed in the direction of the arrow in the figure. On the other hand, a positive power supply bus bar 8 is provided along the conveyor 7, and when an electric brush 9 provided on the hook 6 comes into sliding contact with the bus bar 8, power is supplied to the case 1. In addition, an electrode 1 on the cathode side is placed in the electrodeposition paint tank 10 which is provided with an insulating lining and is filled with paint.
1 is installed, and power is supplied to this electrode 11 and case 1 from output ends 13 and 14 of a DC power supply device 12. Further, the electrodeposition paint tank 10 is filled with a water-soluble resin paint 15 for electrodeposition coating.
The transformer case 1 conveyed by the conveyor 7 is immersed in an electrodeposition paint bath 10 provided with a cathode side electrode 11. By immersion in case 1,
The anode current flows to the case 1 via the power supply busbar 8 on the anode side → the electric brush 9 → the hanger 6, while the cathode current flows from the electrode 11 to the water-soluble resin paint, where it is electrically connected for the first time and transforms. Electrodeposition coating is performed by electrically adhering electrically resistant paint to the case 1 while the container case 1 is moved in the electrocoating paint tank 10 by the conveyor 7. As a result, the electrodeposited coating film is formed on the outer surface of the transformer case 1, including the outer surface of the corrugated heat dissipating fins 4, with a substantially uniform thickness. Further, the back surface of the corrugated heat dissipation fin 4 has a perforation 5 formed in the side surface of the heat dissipation fin 4 so that electricity can also flow between the back surface of the heat dissipation fin 4 and the side plate of the case 1 covered by the heat dissipation fin 4. Therefore, an electrodeposited coating film having approximately the same thickness as the outer surface is formed on the back surface of the heat dissipation fin 4 as well. In particular, the coating film applied to the back surface of the heat dissipation fin 4 formed in a hollow shape is
As described above, by providing the through holes 5 on the side surfaces of the heat dissipating fins 4, it became possible to form a thicker electrodeposited coating film than in the case where the through holes 5 were not provided.

Here, a hollow heat radiation fin 4 having a through hole 5 is used.
The results of testing the degree of formation of an electrodeposition coating film formed on the back surface of a hollow heat dissipating fin having no through holes 5 are shown below.

A water-soluble resin paint was adjusted to have a non-volatile content of about 20%, and a transformer case 1 (the vertical dimension of the heat dissipation fin 4 was 800 mm) treated with zinc phosphate was immersed in this paint.
A voltage of 300 V was applied, and the total energization time was 4 minutes.
As a result, the coating thickness on the surface of the heat dissipation fin was approximately 38 μm regardless of the presence or absence of the through holes 5. However, through hole 5
On the back side of a heat dissipation fin that does not have a
The film thickness was 35μ, but the coating thickness gradually becomes thinner as it moves toward the center, and is about 8μ in the center.
only one had been formed. On the other hand, on the back side of the heat dissipation fin 4 provided with the through holes 5, a coating film of about 35 to 39 μm is formed near the top and bottom of the back surface of the heat dissipation fin 4, and a coating film of about 30 μm is also formed near the center. was.

According to the test results, the back side of the heat dissipation fin 4 formed in a hollow shape can be coated with electrodeposition almost the same as the outer surface by forming the through holes 5 in the heat dissipation fin 4 in a range that does not impede the flow of air. It was found that a film could be formed. After applying electrodeposition coating to the transformer case 1 as an undercoat, the transformer case 1 is air-dried → heat-dried (150 to 200°C) → cooled, and then the surface of the transformer case 1 is applied as a topcoat. Perform electrostatic painting. At this time, the back surface of the heat dissipation fin 4 can be coated with a highly corrosion-resistant electrodeposition coating with almost the same coating thickness as the outer surface, so that the back surface of the hollow heat dissipation fin 4 can be coated with the same thickness as the outer surface. No need to spray paint. After finishing the top coating process of the transformer case 1 by electrostatic coating, natural drying → heating drying (100 to 130° C.) is performed to complete the coating process of the transformer case 1.

The present invention has been described with reference to an example in which the transformer case 1 is provided with a plurality of heat dissipation fins 4 formed in a V-shape. Of course, the formed heat dissipation fins may be implemented on the transformer case disposed on the side plate of the case.

[Effects of the Invention] Since the present invention is configured as described above, it has the following effects.

(1) When painting a transformer case equipped with wave-shaped heat dissipation fins, a small-diameter through hole is provided approximately in the vertical center of the heat dissipation fin, and an electrodeposition coating is applied as the undercoating for the case. By performing electrostatic painting as the top coating process, it is possible to form a coating film on the back side of the wave-shaped heat dissipation fins with the same thickness as the outer surface, resulting in excellent corrosion and weather resistance. You can get a transformer case. In addition, the size and number of holes drilled in the heat dissipation fins can be set within a range that does not impede air flow and impair the cooling effect of the transformer. When mounted on a pillar, the through hole is very small, so it will not deteriorate the cooling function of the radiator or spoil its aesthetic appearance.

(2) In addition, since electrodeposition is used as an undercoat in the transformer case painting process, there is no need to paint the back side of the heat dissipation fins one by one using a spray gun as in the past. , Moreover, by providing through holes in the heat dissipation fins,
It is possible to quickly and reliably paint a transformer case by effectively utilizing the function of electrodeposition painting.

As described above, the present invention can shorten the transformer case painting process, automate it and save labor, and can easily and economically perform the transformer case painting process. On top of that,
The above-mentioned coating treatment makes it possible to provide a transformer case with excellent corrosion resistance and weather resistance.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the main parts of the transformer case of the present invention, Fig. 2 is a cross-sectional view of the joint, and Fig. 3 is the overall configuration of an electrodeposition coating device for performing the undercoat coating process on the transformer case. The explanatory diagram, FIG. 4, is a schematic process diagram illustrating the coating method of the present invention, and FIG. 5 is a schematic process diagram illustrating the conventional coating method. 1...Transformer case, 4...Radiation fin, 5...
...through hole.

Claims (1)

[Claims] 1. In a case in which a side plate of a transformer case is provided with corrugated heat dissipation fins, a through hole of a small diameter is bored in the heat dissipation fin within a range that does not obstruct air circulation;
A transformer case characterized in that an electrodeposited coating film is formed as a case undercoat on the surface of the transformer case to which the heat dissipation fins having the through holes are attached. 2. In a case equipped with corrugated heat dissipation fins on the side plate of the transformer case, the step of drilling small-diameter through holes in the heat dissipation fins of the case, and applying an undercoat to the surface of the transformer case to which the heat dissipation fins having the through holes are attached. A method for painting a transformer case, comprising the steps of applying an electrocoating film treatment as a coating, and applying an electrostatic coating film treatment as a top coat to the surface of the electrodeposition film.