JPH05208264A - Method for brazing aluminum material parts to each other - Google Patents

Abstract

PURPOSE:To inexpensively provide aluminum material products to the outside surfaces of which the residues of a flux do not stick according to brazing. CONSTITUTION:The aluminum material parts 1, 1 placed atop a conveyor 2 are brazed by heating during the passage through a heating furnace 3. The flux is not applied on the aluminum material parts 1, 1. Gaseous N2 contg. >=0.05vol.% gaseous HF is filled in the brazing space 6 of this heating furnace 3. The oxide films on the surfaces of the aluminum material parts 1, 1 are broken by the gaseous HF. The good brazing property of the aluminum material parts to each other is thus assured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The method of brazing aluminum parts to each other according to the present invention relates to a tube made of an aluminum material, which constitutes a heat exchanger used as a radiator, an evaporator, a heater core, a condenser, etc. for an automobile. Used for brazing fins.

[0002]

2. Description of the Related Art In recent years, a heat exchanger used as a radiator or the like is made of aluminum or an aluminum alloy (in the present specification, these are collectively referred to as "aluminum material").
It is often made by. When the heat exchanger is made of an aluminum material, the components are combined with each other in the state where the brazing filler metal is present at the contacting parts, and then the components are put into a heating furnace and the non-existence of N ₂ gas atmosphere etc. The constituent parts are brazed to each other by heating the constituent parts above the melting temperature of the brazing material in an oxidizing gas atmosphere.

For example, when configuring the core of a heat exchanger,
The tube is made from JIS 3003 material (0.6 wt% or less of Si,
7% by weight or less of Fe and 0.20 to 0.50% by weight of Cu
And an aluminum alloy containing 1.0 to 1.5% by weight of Mn and 0.10% by weight or less of Zn, and the balance of Al and Al as unavoidable impurities). JIS 4343 material (6.8 to 8.2 wt% Si and 0.8 wt% Fe or less) on both surfaces (the surface that contacts the outer surface of the tube) of
And 0.25 wt% or less Cu and 0.10 wt% or less
In the above non-oxidizing gas atmosphere, each of them is made of a so-called clad material in which a brazing material layer made of Mn and 0.20% by weight or less of Zn and the rest of which is Al and an aluminum alloy containing unavoidable impurities is laminated. The JIS 4343 material is melted by heating at 600 ° C. for about 3 minutes, and the tube and the fin are fixed by brazing.

Prior to the brazing work, flux is applied to the contact portions between the tubes and the fins, and the oxide film existing on the surfaces of the tubes and the fins is destroyed by heating, and the tubes and the fins are broken. The brazing is done well. The above-mentioned flux is described in, for example, Japanese Patent Publication No. 58-27037 and is commercially available as "NOCOLOK FLUX", 65.6.
~ 99.9% by weight KAlF ₄ and 34.4 ~ 0.1% by weight
A flux composed of K ₃ AlF ₆ is widely used.

By the way, when the brazing work of aluminum material parts is performed in the presence of such a flux,
After brazing, a residue of flux is produced, and this residue becomes white powder and adheres to the surface of the heat exchanger after completion. This residue not only deteriorates the appearance of the obtained heat exchanger, but, for example, when the heat exchanger is an evaporator, this residue is blown from the outlet of the air conditioner into the automobile interior,
This may cause passenger discomfort.

[0006] As a technique for preventing the generation of such a residue that causes such inconvenience, Japanese Patent Application Laid-Open No. 3-128171 discloses a method of brazing aluminum parts to each other.
A technique is described in which flux is not applied to the surface of the aluminum-made component, and flux flux is fed into the heating furnace instead. In the case of the technique described in this publication, a flux is heated and evaporated by a heating device provided outside the heating furnace, and the resulting flux vapor is filled in the heating furnace to form an oxide film on the surface of each aluminum-made component. Destroy.

[0007]

However, in the case of the technique described in Japanese Patent Laid-Open No. 3-128171, since the flux vapor is sent into the heating furnace, a heating means for heating and evaporating the flux is required, and brazing Not only does the entire device become complicated, but the running cost also increases.

The method for brazing aluminum parts to each other according to the present invention eliminates any of the inconveniences described above.

[0009]

The method of brazing aluminum parts of the present invention comprises combining a plurality of aluminum parts to be brazed with each other in a state where a brazing material is present at a contact portion. Then, the plurality of aluminum material parts are put into a heating furnace without applying flux to the surface, and the plurality of aluminum material parts are placed in a non-oxidizing gas atmosphere containing 0.05% by volume or more of HF gas. The heating is performed at a temperature higher than the melting temperature of the brazing material.

[0010]

In the brazing method for aluminum parts made according to the present invention having the above-mentioned structure, the surface of the aluminum parts is oxidized by the HF gas contained in the non-oxidizing gas existing in the heating furnace. The film is broken, and the aluminum parts to be brazed to each other directly contact each other without interposing the oxide film. As a result, when the brazing material is melted, the parts made of aluminum material are brazed together.

Particularly, in the case of the method for brazing aluminum parts of the present invention, since flux is not applied to the surfaces of aluminum parts to be brazed and joined, a residue may not be produced on the product surface after brazing. Absent. Moreover, instead of omitting the flux, a small amount of HF gas is sent into the heating furnace, so that it is not necessary to provide an extra device such as a heating device in order to obtain a gas for destroying the oxide film (HF gas).

If the mixing ratio of the HF gas is less than 0.05% by volume, the oxide film on the surface of the aluminum component will not be sufficiently destroyed, resulting in poor brazing property. The mixing ratio of HF gas was set to 0.05% by volume or more. Even if the mixing ratio of the HF gas increases, there is no particular problem with the brazing property. However, even if the mixing ratio greatly exceeds the above 0.05% by volume, the brazing property is improved accordingly. There is no. Even if the mixing ratio of HF gas is excessively large, the running cost increases due to the increased consumption of HF gas, which is more expensive than N ₂ gas which is widely used as an inert gas, and the exhaust treatment is troublesome. Since it is only troublesome, the mixing ratio of HF should be as low as possible as long as good brazing property is secured.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a brazing apparatus for carrying out the method for brazing aluminum parts according to the present invention. The aluminum parts 1, 1 assembled in a state to be fixed by brazing and temporarily fixed by a jig are placed on the upper surface of a conveyor 2 made of a heat-resistant material, and sent from left to right in FIG. A tunnel-shaped heating furnace 3 is provided above the conveyor 2 so that the aluminum material parts 1 and 1 are heated and brazed while being sent along the conveyor 2.

That is, in the heating furnace 3, the first residual heat space 4, the second residual heat space 5, the brazing space 6, and the cooling space 7 are sequentially arranged from the front side (the left side in FIG. 1) of the traveling direction of the conveyor 2.
Are provided in series with each other. The aluminum parts 1, 1 placed on the conveyor 2 are preheated while passing through the first and second residual heat spaces 4, 5, and are made up of aluminum parts before reaching the brazing space 6. 1, 1
Temperature reaches the melting temperature of the brazing material.

On the other hand, on the ceiling surface of the heating furnace 3, an air supply port 8 (and, if necessary, a nozzle for jetting cooling water) opening toward the brazing space 6 is provided in the cooling space 7 portion. It is provided. 9 is an air supply means for sending a mixed gas of N ₂ gas and HF gas to the air supply port 8, and mixes the N ₂ gas cylinder and the HF gas cylinder with the gases discharged from both gas cylinders at a predetermined ratio. And a mixer for The mixed gas of N ₂ gas and HF gas sent from the air supply port 8 is sent to the brazing space 6 and the brazing space 6
The aluminum material parts 1 and 1 passing through are covered. After passing through the brazing space 6, the mixed gas is discharged from an exhaust port 10 provided at the bottom of the second residual heat space 5, sent to an exhaust treatment facility provided separately, and detoxified.

Since the aluminum material parts 1, 1 pass through the brazing space 6 slowly, for example, for about 3 minutes, the oxide films on the surfaces of the aluminum material parts 1, 1 are destroyed during this time. At the same time, the brazing material is melted, and the temporarily fixed parts made of aluminum material are fixed by brazing. Aluminum parts 1 and 1 fixed by brazing
Is solidified by melting the brazing filler metal that is cooled while passing through the cooling space 7, and is taken out from the rear end portion of the conveyor 2 in the feeding direction.

Next, an experiment conducted to confirm the effect of the brazing method for aluminum parts of the present invention will be described.

The experiment was carried out by brazing a pair of plate materials 11 and 12 assembled together as shown in FIG. After brazing, the presence or absence of adhesion of residues on the surfaces of the pair of plate materials 11 and 12 and the brazing property were visually observed, and the results are shown in Table 1 below.

Table 1

[Table 1]

Of the pair of plate members 11 and 12, one plate member 11 is made of the JIS 3003 material and has a thickness of 1.0 mm, and its edge is butted against the upper surface of the one plate member 11. The other plate material 12 is a core material layer 13 made of the above JIS 3003 material.
JIS 4343 as the brazing material layers 14 and 14 on both front and back sides of
The material coated was used. The thickness of the other plate 12 as a whole was 0.5 mm, and the thickness of each brazing material layer 14, 14 was 0.05 mm. Brazing conditions are 600 ° C and 3
Minutes. In the above table, the brazing properties are the plate materials 11, 1
The ratio of the length L ₁ of the fillet formed by the brazing filler metal to the length L ₀ of the contact portion between the two is expressed as a percentage (100 · L ₁ / L ₀ ).

As is clear from the description in Table 1 above showing the results of the experiment, according to the brazing method for aluminum parts of the present invention, the flux residue adheres to the surface while maintaining the brazing property. Can be prevented.

Further, the method of brazing aluminum materials according to the present invention is not limited to brazing of the exposed portion such as the contact portion between the outer surface of the heat transfer tube and the fin, but also a laminated evaporator. When brazing a portion that has entered inside, such as a brazing portion between plate materials, at least the amount of Mg contained in the aluminum alloy forming the brazing material, if possible, the plate material The amount of Mg contained in the aluminum material composing 0 to 0.
It is preferably set to 03% by weight.

That is, F in HF gas is combined with Mg,
When Mg is contained in the aluminum alloy put in the heating furnace at the time of brazing, the amount of HF gas fed into the heating furnace increases because the compound of KMgF ₃ or MgF ₂ is produced. The amount of HF gas floating in the heating furnace is reduced, and the brazing properties of the above plate materials are likely to be poor.

On the other hand, for example, JP-A-62-798,
In the case of a laminated heat exchanger formed by stacking a large number of metal plates as described in Japanese Utility Model Laid-Open No. 61-119077, there is an overlapping part of metal plates to be brazed inside. To do. Therefore, it is necessary that the HF gas for brazing passes through the inside of the through holes formed in the multiple metal plates and reaches the overlapping portion.

However, when Mg is contained in the aluminum alloy forming the brazing material or the aluminum material forming the plate material, F is consumed before reaching the overlapping portion, and brazing of the overlapping portion is performed. The quality becomes poor. Therefore, as described above, by suppressing the amount of Mg as low as 0 to 0.03% by weight, the consumption of F in the HF gas is suppressed, and a sufficient amount of HF gas reaches the superposed portion. The brazing property of this overlapping portion is secured.

As described above, in order to confirm the effect of suppressing the amount of Mg to be small and improving the brazing property, the present inventor has made various types of aluminum-made clads having the compositions shown in Table 2 below. A plate material was made of the material, and a laminated heat exchanger was configured with the plate material, and the brazing property was observed. The clad material had a plate thickness of 0.5 mm, and the skin material was laminated on both sides by a thickness of 10% (the clad ratio was 20% on both sides in total). In Table 2, the skin material corresponds to the brazing material layer 14 in FIG. The brazing temperature and brazing time are 600 ° C.
It was 3 minutes.

Table 2

[Table 2]

As is clear from Table 2, by suppressing the amount of Mg contained in the aluminum material constituting the laminated heat exchanger to be small, the brazing property is improved and the laminated heat exchanger having high strength is obtained. Can be obtained.

[0029]

EFFECT OF THE INVENTION The method of brazing aluminum parts of the present invention is constructed as described above, but the flux application and drying steps are unnecessary, and no flux residue is generated after brazing. Because the surface is beautiful, you can obtain high quality aluminum brazing products such as aluminum heat exchangers without increasing the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional side view showing an example of a brazing apparatus for carrying out a brazing method for aluminum parts of the present invention.

FIG. 2 is a perspective view showing a plate material made of an aluminum material used in an experiment for confirming the effect of the method of the present invention.

[Explanation of sign]

 DESCRIPTION OF SYMBOLS 1 Aluminum component 2 Conveyor 3 Heating furnace 4 First residual heat space 5 Second residual heat space 6 Brazing space 7 Cooling space 8 Air supply port 9 Air supply means 10 Exhaust port 11 Plate material 12 Plate material 13 Core material layer 14 Wax Lumber layer

Claims (3)

[Claims] 1. A method in which a plurality of aluminum material parts to be brazed to each other are combined in a state where a brazing material is present at a contact portion, and then a flux is applied to the surface of the plurality of aluminum material parts. Instead of putting them in a heating furnace and heating the plurality of aluminum material parts above the melting temperature of the brazing material in a non-oxidizing gas atmosphere containing HF gas at 0.05% by volume or more, Brazing method. 2. The amount of Mg contained in the aluminum alloy constituting the brazing material is 0 to 0.03% by weight.
The method of brazing aluminum parts according to claim 1. 3. The brazing method for aluminum component parts according to claim 2, wherein the amount of Mg contained in the aluminum material forming the plurality of aluminum component parts is 0 to 0.03% by weight.