JPH10193086A - Manufacture of aluminum heat exchanger, and aluminum heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum heat exchanger capable of performing the brazing free from any flux residues, etc., in a simple process with small amount of flux by brazing fins to heat exchanging pipes after the flux for brazing is applied to a surface of the heat exchanging pipes together with the binder. SOLUTION: A heat exchanger comprises a plurality of extruded flat pipes 4 as heat exchanging pipes to be communicated with a pair of header pipes 3 having a thermal medium inlet 1 and an outlet 2, and corrugated fins 5. The extruded flat pipes 4 are of aluminum alloy extruded stock, and the corrugated fins 5 are aluminum alloy plates which are bent in a meandering manner, and the flat pipes and the corrugated fins are brazed by applying the mixture of the brazing flux and the binder. The binder is, for example, the thermoplastic acrylic copolymer, and the flux is the fluoride flux, and the application quantity is preferably 0.05-4.0g/m<2> . The application process is simplified thereby, and the labor and time for the brazing work can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum heat exchanger and an aluminum heat exchanger, and more particularly to a heat exchanger tube made of aluminum and an aluminum alloy (hereinafter referred to as aluminum). The present invention relates to a method for manufacturing an aluminum heat exchanger formed by brazing a fin and a fin, and an aluminum heat exchanger.

[0002]

2. Description of the Related Art In general, aluminum heat exchangers in which aluminum fins and aluminum heat exchange tubes are brazed are widely used. In order to improve heat exchange efficiency, aluminum heat exchangers are made of aluminum. An extruded flat tube made of extruded profile is used.

When the heat exchanger core thus constructed is manufactured by a brazing method using a flux, the heat exchange tube and the fin are restrained and assembled by an assembling jig, and then the flux is applied to the entire assembled product. The method of performing brazing is generally performed. In this case, the flux is applied by diluting the flux with a solution such as water and applying the slurry solution by spraying, or by applying the flux by electrostatic coating.

[0004]

However, since the flux is applied to the entire product assembled by any of the application methods, the amount of the flux used is large, and the appearance of the product is deteriorated due to contamination by the flux after brazing. There was a problem of inviting.

Moreover, since flux is applied to the mounting jig, the jig becomes very dirty after brazing, and the maintenance of the jig after brazing is troublesome and the life of the jig is shortened. there were. In addition, the welding between the fins and the jig or the trace of the jig is left, so that the flux must be removed. Furthermore, it is necessary to devise measures such as covering seals and caps on parts that do not want to be contaminated with flux, such as unions and connectors of heat exchangers, to prevent flux from adhering during flux application. In addition, especially in the case of heat exchange tubes where surface corrosion is likely to occur, such as surface sprayed zinc material, rust-preventive oil is used to store the material before it is subjected to brazing, so material management is troublesome. There are problems.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method of manufacturing an aluminum heat exchanger capable of performing brazing free of flux residue and the like by a simple process with a small amount of flux and an aluminum heat exchanger. The purpose is to provide.

[0007]

According to a first aspect of the present invention, there is provided a method for manufacturing an aluminum heat exchanger, comprising the steps of: In the manufacturing method, after applying the flux for brazing to the surface of the heat exchange tube together with the binder,
The fin and the heat exchange tube are assembled and brazed.

[0008] In the present invention, the fluxing with the brazing and fluoride-based flux, the flux application amount to the heat exchange tube surface is better to 0.05g / m ² ~4.0g / m ² preferred (according Item 2).

According to a third aspect of the present invention, there is provided an aluminum heat exchanger in which a heat exchange tube and a fin are joined by brazing.
It is characterized by being coated with a mixture of a fluoride flux and a binder.

In the present invention, examples of the fluoride-based flux include aluminum fluoride, an alkali metal fluoride, an alkaline earth metal fluoride, and a composite fluoride thereof (eg, KAlF ₄ , K ₂ AlF _5. H ₂
O, K ₃ AlF ₆ , AlF ₃ , LiF, CaF ₂ , NaF,
Li ₃ AlF ₆ , RbF, CsF, BaF ₂ , AlF ₃ , K
F, BaF _2, etc.) or those containing these as main components can be used.

As the binder, for example, a thermoplastic acrylic copolymer can be used. It is preferable that the thermoplastic acrylic copolymer melts in, for example, an aliphatic alcohol having 1 to 8 carbon atoms and volatilizes without being carbonized and decomposed in the course of raising the temperature to the brazing temperature.

Further, when applying the above-mentioned brazing flux, a binder diluent may be used as necessary.

According to the present invention, by applying the mixture of the brazing flux and the binder to the brazing surface, the flux can be applied only to the joints, so that the amount of the flux used can be reduced. .
Further, the use of a binder can prevent peeling after coating and drying. Also, by using a fluoride-based flux as the brazing flux, the corrosion resistance of the heat exchanger can be improved.

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Here, the case where the present invention is applied to a parallel flow type aluminum heat exchanger will be described.

As shown in FIG. 1, the heat exchanger includes a pair of opposed header tubes 3 having an inlet 1 or an outlet 2 for a heat medium, and heat exchangers arranged in parallel with each other and communicating with the header tubes 3. It comprises a plurality of extruded flat tubes 4 as exchange tubes, and corrugated fins 5 disposed between the extruded flat tubes 4. In the heat exchanger thus configured, the extruded flat tube 4 is formed of an extruded aluminum alloy material, the corrugated fin 5 is formed by bending an aluminum alloy plate material in a meandering shape, and 4 and the corrugated fin 5 are integrally brazed by a brazing method using the brazing composition of the present invention.

For example, to braze the extruded flat tube 4 and the corrugated fin 5 to produce a heat exchanger core, FIG.
For example, a brazing composition can be applied to the surface of the extruded flat tube 4 by using an application device as shown in FIG.

The coating apparatus includes a container body 10 having a carry-in port 11 for an object to be coated, ie, an extruded flat tube 4, at an intermediate portion on one side and a carry-out port 12 at an upper portion on the other side;
An immersion tank 13 provided at a lower portion of the apparatus main body, an object-to-be-coated transporting means 14 for guiding the extruded flat tube 4 into the immersion tank 13 and pulling the extruded flat tube substantially vertically from the immersion tank 13, Drying means 1 for drying and baking the slurry solution 15 of the brazing composition adhering to the surface of No. 4
8 is provided.

In this case, a slurry solution 15 of a brazing composition in which a mixed powder of a fluoride-based flux is added to a binder solution is accommodated in the immersion tank 13. Maintained uniformly.

The object conveying means 14 is provided at the entrance 11.
A first guide roller 14a for guiding the extruded flat tube 4 drawn from the supply unit 17 of the extruded flat tube 4 wound in a coil shape in the vicinity thereof into the immersion tank 13; A second guide roller 14b for guiding the flattened extruded tube 4 supplied into the dipping bath 13 upward, and a third guide for guiding the flattened extruded tube 4 pulled up substantially vertically from the dipping bath 13 in a substantially horizontal direction. And the guide roller 14c.
The first to third guide rollers 14a, 14a
b and 14c are driven to rotate by a motor and a transmission mechanism (not shown).

The drying means 18 is formed of a pair of dryers 18a located above the immersion tank 13 for drying and baking both sides of the extruded flat tube 4. The drying means 18 is pulled up substantially vertically from the immersion tank 13. When the excess amount of the slurry solution 15 applied (adhered) to the extruded flat tube 4 is dripped and reaches an equilibrium state, the slurry solution (brazing composition) is baked. .

Next, a method for applying the brazing composition according to the present invention will be described. First, a slurry solution 15 of the brazing composition is prepared and stored in the immersion tank 13.

In this case, the brazing composition is formed of a mixture of a non-corrosive fluoride-based flux and a binder. In this case, the binder is
Those satisfying the following conditions are used. That is, a thermoplastic acrylic copolymer, for example, trade name: PARALOID
B-67 @ Rohm and Has Compa
ny, which dissolves in an aliphatic alcohol having 1 to 8 carbon atoms and which volatilizes without being carbonized during the process of raising the temperature of aluminum to a brazing temperature (for example, 600 ° C.). There is.

In the case of using a binder diluent as required in applying the flux, for example, methanol (methyl alcohol), ethanol (ethyl alcohol),
Propanol (isopropyl alcohol (IPA)),
Examples include butanol (butyl alcohol) or pentanol (amyl alcohol), water, and thinner.

The above-mentioned fluoride-based flux includes, for example, aluminum fluoride, alkali metal fluoride, alkaline earth metal fluoride and composite fluorides thereof (for example, KAlF ₄ , K ₂ AlF ₅ .H _2). O, K ₃ A
_{lF 6, AlF 3, LiF,} CaF 2, NaF, Li 3 Al
F ₆ , RbF, CsF, BaF ₂ , AlF ₃ , KF, Ba
F _2, etc.) or those obtained by the main component can be used. The ratio of each component of the brazing composition configured as described above is, for example, 5% of flux, 5% of binder, and 90% of alcohol for diluting binder (for example, IPA).

After the slurry solution 15 of the brazing composition is contained in the immersion tank 13 as described above, it is drawn from the object to be coated wound in advance in a coil shape, that is, the coil body of the extruded flat tube 4. The extruded flat tube 4 is connected to the entrance 1 of the apparatus body 10.
After being immersed in the immersion tank 13 from 1 via the first guide roller 14a, it is pulled up in a substantially vertical direction by the second guide roller 14b. At the time of this pulling up, the excess attached slurry solution 15 drips down, and when the slurry solution 15 attached to the extruded flat tube 4 is in an equilibrium state, the slurry solution 15 is dried and baked by the drying means 18. Then, the posture of the extruded flat tube 4 is changed from the vertical state to the horizontal state by the third guide roller 14c, and then taken out from the carry-out port 12,
It is straightened by straightening and cut to a predetermined length.
Then, the cut extruded flat tube 4 and the corrugated fin 5 are heated at a predetermined temperature and brazed integrally.

Therefore, according to the above-mentioned coating method, the extruded flat tube 4 is completely immersed, so that the entire surface is covered with the slurry solution 15 so that the entire surface of the extruded flat tube can be uniformly coated without unevenness. it can. Further, by pulling up vertically, there is no difference in the amount of adhesion between the front and back surfaces, and excess adhered slurry is removed from the extruded flat tube 4.
Therefore, the coating efficiency can be improved.

Further, in order to change the amount of the brazing composition, the amount of the flux can be easily changed by changing the concentration of the fluoride-based flux mixed powder in the slurry solution 15. The amount of adhesion is, for example, 0.
It can be set in the range of 05 g / m ^{2 to} 4.0 g / m ² . Moreover, according to the said coating method, the extrusion flat tube 4 can be continuously supplied (immersed), and the brazing composition can be continuously apply | coated on the surface.

In the above embodiment, the case where the extruded flat tube 4 is immersed in the slurry solution 15 of the brazing composition and applied is described. However, the method of applying the flux is not limited to such an immersion method. For example, as shown in FIG. 3, for example, the brazing composition 6 of the present invention can be applied to the surface of the extruded flat tube 4 by a spray nozzle 7 and then the extruded flat tube 4 and the corrugated fin 5 are brazed. Can be attached. According to this method, a flux coating device, a drying device, and the like are not required, and the size of the equipment can be reduced.

The extruded flat tube 4 can be either an extruded flat tube to which no brazing material is adhered or an electric resistance welded flat tube clad with brazing material, and an extruded flat tube to which no brazing material is adhered. When a brazing material is used, a brazing sheet can be used. In the case of an electric resistance welded flat tube clad with a brazing material, a cloth material can be used as the fin material.

In the above embodiment, a plurality of extruded flat tubes 4 are arranged in parallel between a pair of header tubes 3 and a corrugated fin 5 is interposed between the extruded flat tubes 4 for a parallel flow type heat exchanger. As described, as a serpentine type heat exchanger in which an extruded flat tube as a heat exchange tube is bent in a meandering shape and communicates with a header tube, and fins are similarly interposed between adjacent extruded flat tubes. Is also good.

[0031]

Next, a comparative test between the brazing method according to the present invention and a conventional brazing method will be described. ◎ Conditions ★ Test materials (both) ・ Heat exchange tube: JIS A1050 extruded flat tube ・ Fin material: Brazing sheet (A4343 + 1% Z)
n / A3003 + 2% Zn / A4343 + 1% Zn) ★ Flux application method ・ Comparative example Spray application of flux-containing slurry solution to the whole assembled product Flux application amount: 10 g / unit ・ Example Heat exchange tube with flux Used heat exchange Contents of tube: Flux adhering amount; 2 g / m ² Binder adhering amount; 4 g / m ² (The applied amount of flux of the whole assembled product is 1.5 g / unit)

As a result of testing the comparative example and the example under current operating conditions, the results shown in Table 1 were obtained.

[0033]

[Table 1]

As a result of the above experiment, the brazing method of the embodiment is completely the same as the brazed product and the product quality (radiation characteristics, corrosion resistance, etc.) of the brazing method of the comparative example, and the fillet size is also the same. However, with respect to the product appearance, the product of the example was superior to the product of the comparative example, and there was an advantage that the application step could be omitted without generating any stain on the jig.

The amount of the adhered flux was 0.05 g /
When the same test was performed in the range of m ^{2 to} 4.0 g / m ² , the same result as above was obtained. If the applied amount of the flux is 0.05 g / m ² or less, the brazing property is reduced due to insufficient flux, and the applied amount of the flux is 4.0 g / m 2.
^If it is ² or more, there is no problem in brazing property, but there is a problem that the amount of flux used is large, the attached film is thick, it is difficult to assemble, and the flux residue is locally generated. Therefore, the amount of the flux used can be reduced to about 1/5 or less of that of the comparative example.

[0036]

As described above, according to the present invention, the following excellent effects can be obtained.

1) Since the mixture of the brazing flux and the binder is applied to the brazing surface of the heat exchange tube, the amount of the flux used can be reduced as compared with the conventional method, and the application process is simplified. Therefore, the labor and time of the brazing operation can be reduced.

2) Since a binder is used, peeling after coating and drying can be prevented, and uniform and strong brazing can be performed.

3) Since the flux can be applied only to the joints, the entire product has no flux residue and the like, so that the product appearance can be improved and the product quality can be improved. Since a flux preventing cap or the like is not required at the time of applying the flux, it is possible to improve the efficiency of the flux applying operation and, hence, the brazing operation.

4) Since flux does not adhere to the assembly jig, maintenance of the jig after brazing is not required, and the life of the jig can be extended. In addition, since there is no trace of the jig or welding between the member and the jig, the quality of the product can be further improved in addition to the above 3).

5) Even in the case of a member whose surface is susceptible to corrosion, such as a surface sprayed zinc material, it is not necessary to use a rust preventive oil or the like, so that inventory management of the material before being subjected to brazing is easy. Become.

6) By using a fluoride flux as the brazing flux, the corrosion resistance of the heat exchanger can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example of a heat exchanger brazed by a brazing method according to the present invention.

FIG. 2 is a cross-sectional view illustrating an embodiment of a flux applying method according to the present invention.

FIG. 3 is an exploded perspective view showing another embodiment of the flux applying method according to the present invention.

[Explanation of symbols]

 Reference Signs List 4 Extruded flat tube (heat exchange tube) 5 Corrugated fin 6 Brazing composition 15 Slurry solution of brazing composition

Claims (3)

[Claims] 1. A method for manufacturing an aluminum heat exchanger in which a heat exchange tube and a fin are brazed and joined together, wherein a brazing flux is applied to a surface of the heat exchange tube together with a binder, and then the fin and the heat exchange tube are coated. And a method of manufacturing an aluminum heat exchanger. 2. A Flux with the brazing is fluoride flux, wherein the flux application amount to the heat exchanger tube surface is characterized by a 0.05 g / m ² to 4.0 g / m ² Item 2. The method for producing an aluminum heat exchanger according to Item 1. 3. An aluminum heat exchanger in which a heat exchange tube and a fin are joined by brazing, wherein a mixture of a fluoride-based flux and a binder is applied to a brazing surface of the heat exchange tube. Aluminum heat exchanger.