JP3053654B2 - 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, etc., and particularly to hollow aluminum materials. The present invention relates to a method of brazing a hollow aluminum material for brazing an aluminum 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 condenser for a car air conditioner called a multi-flow type, a large number of tubes as hollow aluminum materials arranged in parallel are arranged, and both ends of each tube are also the same as hollow aluminum materials. They are joined and connected while being inserted into a pair of hollow headers.

[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:
Prepare a relatively high-concentration flux suspension with a concentration of about 30% to exert a sufficient flux action, and immerse the heat exchanger assembly in this suspension to remove only the outer surface of the aluminum material. The same high-concentration flux suspension was simultaneously introduced into the inside and the flux was applied to both the inner and outer surfaces of the hollow aluminum material, and then heated to a predetermined temperature to melt the joining brazing material.

[0006]

However, such a method has the following problems.

That is, although a part of the flux in the suspension remains as it is on the surface of the aluminum material as a residue even after brazing, when a flux suspension having a high concentration as in the prior art is used, a large amount of flux exists. Flux remains on the inner and outer surfaces of the aluminum material. Thus, the flux remaining on the inner surface of the aluminum material is extremely difficult to remove, and must be left as it is. As a result, there has been a problem that the flux is peeled and mixed with the refrigerant, water, oil, and the like flowing inside the hollow aluminum material with the passage of time, causing clogging of the circuit and deterioration of performance.

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

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, a step of introducing a low-concentration flux suspension into the empty aluminum material of the assembly and applying a flux to the inner surface of the aluminum material, High concentration on the outer surface of the hollow aluminum material of the assembly
The gist of the present invention is a method of brazing a hollow aluminum material, wherein the step of supplying the flux is performed in a separate step .

[0010]

[Function] Apart from supplying the flux to the outer surface of the hollow aluminum material, a low-concentration flux suspension is introduced into the aluminum material to apply the flux to the inner surface of the hollow material in advance. Regardless of the amount, the amount of residual flux on the inner surface can be adjusted to be small. Also, use high-concentration flux on the outer surface of the hollow aluminum material .
Therefore, the brazing can be performed by supplying a sufficient flux, so that there is no occurrence of a decrease in bonding strength or leakage due to poor brazing.

[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 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 thin flux suspension having a flux concentration of about 5% or less is prepared, and the heat exchanger assembly is immersed in the suspension and placed in the tubes (1) and the headers (3) and (4). Introduce the suspension. Of course, this treatment also results in a low concentration flux being applied to the outer surface of the heat exchanger assembly. Next, the heat exchanger assembly is pulled up from the suspension and dried if necessary.

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.

[0015] The heat exchanger assembly to which the flux suspension has been applied is then thoroughly dried before being transferred to the 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 clad on a core material is generally used. In this embodiment, tube (1) and corrugated fin (2), corrugated fin (2) and side plate (5), header (3)
It is necessary to braze (4) and the tube (1) and braze the headers (3) and (4) and the tube (1), and the header (3) and the partition plate (6) inside the header. For this reason, the headers (3) and (4), the corrugated fin (2), and the partition plate (6) are each formed of a double-sided brazing sheet. In FIGS. 2 and 3, (4a) (3
a) 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. The header (3) is heated by the above heating.
(4) The brazing filler metal of the corrugated fins (2) and the partition plate (6) is melted. 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 suspension applied to the inside of the hollow aluminum material has a low concentration, the residual flux inside the hollow material becomes small 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 (7) is loaded inside to join the two. Also in this case, by introducing the low-concentration suspension into the tube as the hollow aluminum material, it is possible to suppress the flux residue after brazing while enabling sufficient brazing.

The type of the flux used in the present invention is not particularly limited, and a chloride-based flux, a fluoride-based flux, and other fluxes can be appropriately used. However, it is preferable to use a non-corrosive fluoride-based flux because no corrosive residue is generated.

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 flux gas-containing inert gas atmosphere, 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, and 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 application step to the inside of the hollow aluminum material and the flux supply step to the outer surface of the aluminum material are separated, and a low-concentration flux suspension is introduced into the hollow aluminum material. Since the flux is applied to the inner surface of the aluminum material, the amount of the flux remaining on the inner surface of the aluminum material after brazing can be made smaller than before. On the other hand, hollow aluminum
On the outer surface of the rubber material, use a high concentration
Lux can be supplied to perform brazing. Therefore, a decrease in bonding strength or leakage due to poor brazing may occur.
Without increasing the cleanliness inside the hollow aluminum material, it is possible to suppress the mixing of residual flux into the refrigerant or water flowing inside the aluminum material, and to suppress circuit clogging and performance deterioration in a heat exchanger or the like. effective.

[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)

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁷ Identification code FI B23K 101: 14

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;
A step of introducing a low-concentration flux suspension into the hollow aluminum material of the assembly before applying the flux to the inner surface of the aluminum material, and a step of applying a high-concentration flux to the outer surface of the hollow aluminum material of the assembly. A method for brazing a hollow aluminum material, wherein the step of supplying the flux is performed in a separate step .