JP3084294B2 - Brazing method of hollow aluminum material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing method applied to brazing, for example, aluminum capacitors, evaporators, radiators for car air conditioners, aluminum capacitors for room air conditioners, and more particularly to aluminum containing hollow material. The present invention relates to a method of brazing a hollow aluminum material for brazing a component.

[0002] In this specification, the term aluminum is used to mean an aluminum alloy.

[0003]

2. Description of the Related Art In an aluminum heat exchanger as described above, a hollow aluminum material through which refrigerant, water, oil and the like are circulated is used. For example, in an aluminum capacitor for a car air conditioner called a multi-flow type, a large number of tubes as hollow aluminum materials are arranged in parallel, and both ends of each tube are a pair of hollow aluminum materials. It is joined and connected while being inserted into a hollow header as a material.

[0004] By the way, the above-mentioned aluminum heat exchanger is generally manufactured by flux-brazing each constituent member. However, the tubes are inserted into the header as described above, and they are firmly joined. To do so, it is desired that both the tube and the header be brazed not only on the outer surface but also on the inside of the header. In some cases, it is required to dispose the inner fin in the tube and braze and join the tube and the inner fin inside the tube.

[0005] Conventionally, the above-mentioned brazing of the heat exchanger is performed by:
By immersing the heat exchanger assembly in the flux suspension, the same high-concentration flux suspension was simultaneously introduced not only on the outer surface but also on the inside of the hollow material, and the flux was applied to both the inner and outer surfaces of the hollow material. Thereafter, the heating is performed at a predetermined temperature to melt the brazing filler metal.

[0006]

However, such a method has the following problems.

That is, a part of the flux in the suspension remains as a residue on the surface of the aluminum material as a residue even after brazing, but when the flux suspension is used, a large amount of flux is generated inside and outside the aluminum material. Remains on the surface.
The flux remaining on the inner surface of the aluminum material
Since the removal is extremely difficult, it has to be left alone. For this reason, refrigerant and water flowing inside the hollow aluminum material,
There has been a problem that the flux is peeled and mixed into the oil or the like over time, which causes clogging of the circuit or a decrease in performance.

The present invention has been made in order to solve such a problem, and it is an object of the present invention to suppress the residual flux inside the hollow aluminum material and maintain a good cleanness of the inner surface.

That is, the present invention relates to a method for brazing a hollow aluminum material on both inner and outer surfaces of the hollow aluminum material.
After assembling the joining member and before brazing, introducing a flux vapor-containing gas into the interior aluminum material of the assembly to bring the inner surface of the aluminum material into contact with the gas; The gist of the present invention is a brazing method for a hollow aluminum material, characterized in that the step of supplying a flux to the outer surface of the hollow aluminum material is performed in a separate step .

[0010]

[Function] Apart from supplying the flux to the outer surface of the hollow aluminum material, a gas containing flux vapor is introduced into the aluminum material to bring the inner surface of the hollow aluminum material into contact with the gas, so that the inner surface of the aluminum material is The flux residual amount can be almost eliminated. In addition, since sufficient brazing can be performed by supplying a sufficient flux to the outer surface of the hollow aluminum material, a decrease in bonding strength or leakage due to poor brazing does not occur.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described based on an embodiment in which the present invention is applied to brazing of an aluminum multi-flow type capacitor for a car air conditioner shown in FIG.

In FIG. 1, (1) is a multiplicity of aluminum flat tubes as hollow aluminum materials arranged vertically side by side, and (2) is arranged between adjacent tubes and outside the outermost tube. Aluminum corrugated fins, (3) and (4) are a pair of left and right aluminum hollow headers as hollow aluminum material, (5)
(5) Aluminum upper and lower side plates, (6)
Is a partition plate for dividing the left header (3) into upper and lower chambers.
As shown in FIG. 2, both ends of the tube (1) are inserted into the header from the tube insertion holes of the headers (3) and (4). The partition plate (6) is inserted into the inside of the header from a slit-shaped cut made in the header over a half circumference in the circumferential direction.

The brazing of the heat exchanger is performed as follows. That is, first, each component is set in a predetermined arrangement to obtain a heat exchanger assembly. Next, a flux vapor-containing gas is introduced into the tube (1) and the headers (3) and (4).
Here, the gas containing the flux vapor is N ₂ ,
An inert gas such as an Ar gas or a He gas may be used. On the other hand, the flux vapor exerts a flux action, that is, an action of removing the oxide film at the joint to improve the wettability and fluidity of the brazing material at the time of brazing in the next step, and plays a role of achieving good brazing. . Examples of the flux vapor include a gasified fluoride vapor of a compound of fluorine and another element and a gasified chloride vapor of a compound of chlorine and another element. Specifically, KAlF ₄ or HF can be suitably used. Such flux steam may be one kind or a mixture of plural kinds of steam. The content of the flux vapor is necessary to exert a good flux action.
It is preferable to set it to about 0.1 to 10000 ppm. 0.
If it is less than 1 ppm, there is a possibility that the flux effect is too small to exert a good flux action, and if it exceeds 10,000 ppm, the flux effect is saturated, which is rather an economic waste. Particularly preferred is 1 to 500 ppm. Also, it is desirable that there is no moisture or oxygen in the flux vapor-containing gas,
H ₂ O: about 10000 ppm or less, O ₂ : 10000 pp
If the amount is less than m, it has almost no effect on brazing properties. H ₂ O is there is a possibility that KAlF ₄ vapor or the like does not occur when more than 10000 ppm, O ₂ 10
If it exceeds 000 ppm, the surface oxide film of the aluminum material becomes thick, and there is a possibility that a problem may occur in brazing.

As described above, by introducing a gas containing flux vapor into a tube or the like and bringing the gas into contact with the inner surface of the tube or the like, the flux vapor probably exerts a flux action to remove an oxide film on the inner surface of the hollow member. It is presumed that it will be.

Next, a flux is supplied to the outer surface of the heat exchanger assembly as follows. That is, a high-concentration flux suspension having a flux concentration of about 30% is separately prepared and uniformly applied to the entire outer surface of the heat exchanger assembly. At this time, it is necessary to take care that the high-concentration suspension does not enter the inside of the header (3) (4) or the tube (1). As a method of application, the suspension may be sprayed, or the headers (3) and (4) may be covered with a lid and immersed in the suspension.

The heat exchanger assembly to which the flux suspension has been applied is then thoroughly dried and then transferred to a brazing furnace. Then, the inside of the furnace is heated to a predetermined temperature, the brazing filler metal is melted, and the constituent members are brazed and joined. Here, as the brazing filler metal, a brazing sheet generally clad in a core material is used. In this embodiment, the tube (1) and the corrugated fin (2), the corrugated fin (2) and the side plate (5), the headers (3) and (4) and the tube (1) are brazed, and the header ( 3) It is necessary to braze (4) and the tube (1), and the header (3) and the partition plate (6). For this reason, the headers (3) and (4), the corrugated fins (2) and the partition plate (6) are each composed of a double-sided brazing sheet. In FIGS. 2 and 3, (4a)
(3a) is the header core material, and (4b) and (3b) are the brazing material.
In FIG. 3, (6a) is a partition core material, and (6b) is a brazing material. Thus, the header (3)
(4) The brazing filler metal of the corrugated fins (2) and the partition plate (6) melts, but not only the outer surface but also the inside of the hollow material is exposed to the flux vapor in each component of the heat exchanger. A good wet spreading property of the brazing material is secured by the flux action, and a sufficient fillet is formed at the joint.

On the other hand, since the flux vapor-containing gas is introduced into the hollow aluminum material, there is almost no residual flux inside the aluminum material after brazing. Therefore, it is possible to prevent the residual flux from flowing into the refrigerant, oil, or the like after the use of the heat exchanger.

As shown in FIG. 4, the tube (1 ')
May be constituted by an electric resistance welded tube of a double-sided brazing sheet in which the brazing material (1b) is coated on both sides of the core material (1a), and an inner fin is loaded inside to join the two. Also in this case, by introducing the flux vapor-containing gas into the tube as the hollow material, it is possible to eliminate the flux residue after brazing while enabling sufficient brazing.

As another mode of supplying the flux to the outer surface of the heat exchanger assembly, there may be mentioned a method in which the inside of the brazing furnace is set to a gas atmosphere containing a flux vapor and the assembly is heated and brazed in this atmosphere. In this case, it is not necessary to apply the flux suspension to the outer surface of the heat exchanger assembly, so that not only the inner surface of the hollow material but also the outer surface of the assembly can be made extremely clean with almost no residual flux.

[0020]

According to the present invention, hollow aluminum
After assembling the aluminum material and the joining member , the flux supply process into the hollow aluminum material and the flux supply process into the outer surface of the hollow aluminum material are separated, and a flux vapor-containing gas is introduced into the hollow aluminum material. Since the inner surface of the aluminum material is brought into contact with the gas, the amount of residual flux adhered to the inner surface of the aluminum material after brazing can be almost eliminated. Meanwhile, hollow al
Brazing by supplying flux on the outer surface of minium material
It can be performed. Therefore, bonding strength due to poor brazing
It is possible to improve the cleanliness inside the aluminum material at each stage without lowering or leaking, and to prevent the mixing of residual flux into the refrigerant and water flowing inside the aluminum material, and This has the effect of suppressing circuit clogging and performance degradation.

[Brief description of the drawings]

FIG. 1 is a front view of a heat exchanger assembly used in an embodiment.

FIG. 2 is a sectional view taken along line II-II in FIG. 1 after brazing.

FIG. 3 is a longitudinal sectional view of a header near a partition plate after brazing.

FIG. 4 is a cross-sectional view showing another configuration example of the tube.

[Explanation of symbols]

 1, 1 '... tube (hollow aluminum material) 3, 4 ... header (hollow aluminum material)

Claims (1)

(57) [Claims] 1. A method of brazing a hollow aluminum material on both inner and outer surfaces of a hollow aluminum material, the method comprising the steps of: assembling the hollow aluminum material with the bonding member;
Before with cormorants, the step of contacting an aluminum material inner surface to the gas by introducing the flux vapor-containing gas into the hollow aluminum material of the assemblage, supplying a flux to the outer surface of the hollow aluminum material of the assembly was And in a separate step .