JPS60117098A - Thin precoated aluminum sheet for fin of heat exchanger - Google Patents

Abstract

PURPOSE:To check the bridging of condensate between fins and at the same time reduce the wear of a tool during the forming of fins by a method wherein a hydrophilic film is applied on one side while a hydrophobic film on the other side of a thin aluminum sheet for fin of a heat exchanger. CONSTITUTION:A film 6' is formed on one side (the die side 3 during the forming of a collar 2) of a aluminum stock sheet 1 by applying hydrophilic paint, while a film 6 is formed on the other side (the punch side 4 during the forming of the collar 2) of the sheet 1 by applying hydrophobic paint. Any paint, both water-soluble and solvent type, will do so far as the performance requirements of fin are met. After being coated, the paints are baked under normal conditions. A precoated sheet obtained by the above-mentioned method is charged to a press in such a manner that its hydrophilic side faces to the opposite side (the die 3 side) to an second ironing punch 4 surface, which has the largest wear among the tool wears, in order to form the fin. Thus, the precoating of hydrophilic paint, which did not employed due to its development of severe tool wear in spite of its excellent hydrophilic permanence, can be made possible and, in addition, the bridging of condensate between fins can be checked.

Description

[Detailed description of the invention]
(:Using a pre-coated aluminum sheet with a 4-
In particular, prevent condensed water from forming ridges between the fins, and process 1 during molding.
1! This is a way to reduce the amount of forest.

Brake I/Fin type heat exchanger is 0.1~0.2mm at the crotch
-r notomyuno of fC degree, draw or do l a thin plate
] - It is made by inserting a copper or anno 1 mini-Uno tube into a fin that has been molded in the Resno style and tightly fitting it by mechanical expansion. However, especially in heat pump type heat exchangers, in order to prevent white powder (corrosion products) generated on the fins when heating starts in winter, that is, to improve corrosion resistance, and to prevent condensed water from forming bridges between the fins. Increasingly, a coating film is applied after molding to improve hydrophilic properties. As for the treatment method, most of the heat exchangers were immersed after being assembled, or perhaps because the fin pitch has been increased recently in order to make heat exchangers smaller, the conventional immersion method has problems such as clogging of the fins. It's becoming impossible to deal with it.

For this reason, so-called Preco I plates, in which a coating film is applied to a thin aluminum plate in advance before fin forming, are being used, but using such plates makes it difficult to form fins, especially when using the drawless method. There is a problem that the tool life is shorter than that of untreated coating, and this is noticeable in the case of so-called hydrophilic coatings that have improved durability by incorporating silica and calcium carbonate.The inventors have conducted various studies on this point. The fin forming process using the drawless method is shown in Figure 1 (
The aluminum blank (1) shown in (a) is subjected to piercing burring processing as shown in (b), then the first ironing processing shown in (・→) and the second ironing processing shown in (a) are performed. The collar (2) shown in Figure 5 is formed by reflaring every time the tool is reflared, but the most severe wear of the tool occurs in the second eye-r shown in Figure 5). In addition to the fact that it turned out to be the second ironing punch (4) in the upper part of the ironing process,
The present invention was completed after discovering that simply applying hydrophilic coating to one side of the fins would create a bridge between the fins.
This is what V did. Intrinsic cause ((3) indicates the second ironing die.

The present invention is as described in I (In < plate fin type heat exchanger 8F
Prevents the formation of bridges between the seven fins 11
This is a pre-coated aluminum thin plate that can reduce tool wear during molding as well as pre-coated aluminum sheets used for the fins of fin-type heat exchangers, with a hydrophilic coating on one side, Another example is a pre-coated aluminum sheet for the fins of a four-filter heat exchanger with a non-hydrophilic coating.

This will be explained in detail using the drawings.

FIG. 3 is a cross-sectional view of a part (II!l) of a pre-coated aluminum thin plate according to the present invention formed into a fin shape by the drawless method as shown in FIG. 2. is an aluminum base plate, (2
) indicates a part of the collar, (5) indicates one hole in the collar, (6) indicates a non-philic, water-based coating film, and (61) indicates a hydrophilic coating film. )), a hydrophilic paint is applied to form a coating film (6'), and a non-hydrophilic paint is applied to the other side (punch side (4) during color molding) to form a coating film (6').
6).

Such a precoated aluminum thin plate can be easily manufactured by the method shown below.

That is, for example, thickness 0.1 to 0.2 cm width] 000111
111 thin aluminum plate with hydrophilic paint on one side and i on the other.
Continuously apply non-hydrophilic paint to n1. Various methods can be used for coating (・Gravure or roll coater are suitable, and paints (・Water-soluble or solvent-based can be used as long as they meet the required characteristics of the fins. After painting, it is usually The Greco J plate obtained in this way has its hydrophilic side on the side opposite to the second iron bonding side (the die (3) side ) is introduced into the press machine and molded.For this reason, the hydrophilicity is maintained i
<Hydrophilic paint, which could not be used due to high tool wear despite good I, can be pre-coated, and bridges between fins can be suppressed.

jlJ, F The present invention will be explained based on examples.

J I S II II 11 tl il II (+
(+1(24 Thickness 0.115WIIl+, Width l il
il IF mm: Il was continuously coated. Degreasing is done by Nippon Paint Co., Ltd. Rd 322-N 6-C"70"
After C51 minute coating, wash with water, dry and apply -J1 hydrophilic coating 1 (acrylic) in Table 1 using a roll coater.
Next, apply hydrophilic paint to the opposite side and bake.
=)L/:I-i coil was manufactured. The width of this coil was 8.24 mm, and the diameter of the second ironing die was 8.35 mm using a continuous die for drawless forming manufactured by Hidaka Seiki Co., Ltd. mm, ironing rate of 52.2 mm, continuous molding was carried out by introducing monthly molding so that the hydrophilic painted surface was the opposite surface (die surface) to the second firing hole/chi surface, and the length was as shown in Figure 2. A fin with a diameter of 275 mm (48 holes in the hollow part) was obtained.The height of the hollow part in the hollow part was 1.6 mm and the inner diameter was 8.3 mm, as shown in Fig. 3. For this purpose, we created fins with a height of 2.0 mm and 2.5 mm in the hollow part, and fins molded under the same conditions with untreated fins and fins with both sides coated with hydrophilic paint. The wear of the punch tool during molding and the bridge formation caused by condensed water on the fins were investigated, and the results are shown in Table 1.

Tool wear was evaluated by the degree of wear of the second ironing bond, and the diameter was 0. (1111111 worn stock - up to the indicated size/Yo1
If the number of shots exceeds 1 million shots, mark C).
Those below this are marked with an X. The condition of bridge formation between the fins due to condensed water is as follows:
This is done by fixing 50 sheets (75 mm) with a jig and spraying distilled water towards the fins. If the fins get wet and do not form a bridge, mark 0. If some water droplets form and form a bridge, mark 0. And so.

Table 1: As is clear, the wear of the precoated fin +1 punch according to the present invention is not much different from that of the untreated punch, and it can be seen that it is difficult to form bridges due to condensed water.

As described above, the present invention is a plate-fin type heat exchanger with a ratio of 8:÷
This prevents the formation of bridges of condensed water between the fins and reduces wear on the two parts during fin forming.1. Work 11? e
It has a remarkable effect.

・1 Simple drawing r1x. /, I-Explanation Figures 1 (a) to (e) show fin forming If1 by the drawless method. (a) is an aluminum blank, (
'') shows 1 degree of sparring, (c) shows the first iron/g1 culm, 2) shows the second ironing process, and (e) shows 1 degree of beam finishing. Figure 2 shows the fin/molding 1 of the thin aluminum plate for fins according to the present invention.
．． , 11-A plan view showing an example of a fin, and FIG.

(1) Aluminum blank plate, (2) Part of empty part, (3)
・Second ironing punch/Gudais, (4)・Second ironing punch, (5) Some holes in the collar, (6) Non-hydrophilic coating film, (6′)・Hydrophilic coating film.

Figure 1 (E) Figure 2 Figure 3

Claims (1)

[Claims] A coating film with a hydrophilic coating on one side and a hydrophilic coating on the other side of the aluminum thin plate used for the fins of the Flu/-Tofuy type heat exchanger.
1) characterized by having an R1 hydrophilic coating film on one side;
Pre-recorded aluminum horn for pJy exchanger fins
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