JPH05185206A - Continuous brazing furnace for gaseous flux brazing of aluminum material - Google Patents

Abstract

(57) [Summary] (Corrected) [Purpose] By brazing in an atmosphere containing flux gas, it is possible to eliminate flux residue on the aluminum brazing surface and to achieve brazing with excellent appearance quality and surface treatment. To do. A brazing furnace 1 having an inlet portion 2 and an outlet portion 7, and a conveying device 3 for sequentially and continuously conveying a plurality of aluminum joining members A from the inlet portion 2 of the brazing furnace 1 to the outlet portion 7.
With. The brazing furnace 1 is provided with a preheating section 4 close to the inlet side, the aluminum joining member A carried into the furnace from the inlet section 2 is preheated, and surface adsorbed water that interferes with the flux action is removed by evaporation. .. The aluminum joining member A that has passed through the preheating unit 4 is brazed by receiving the minimum required flux supply from the flux gas supply unit 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing apparatus for an aluminum material, which is preferably used for manufacturing an aluminum heat exchanger having a brazing specification, and in particular, a flux gas for continuously brazing in a flux gas atmosphere. The present invention relates to a continuous brazing furnace for brazing.

In this specification, the term aluminum is used to include its alloy.

[0003]

2. Description of the Related Art For example, when brazing a radiator for a car, an evaporator for a car cooler, a condenser or other heat exchanger made of aluminum for an electric machine or machine, except when vacuum brazing, a heat exchanger using flux is used. A method of brazing and joining the constituent members is often used.

Conventionally, when performing such flux brazing, the flux is first suspended in water or a solvent, and then this suspension is sprayed, showered or dipped onto the surface of the aluminum material to be joined. And then preheated and dried to evaporate and remove water, and then heated to a predetermined temperature in a non-oxidizing atmosphere to melt the brazing material for brazing.

However, this method requires the work of applying the suspension and the work of drying after the application, and is not good in productivity. In addition, since the amount of flux adhered to the aluminum material is generally large, the flux remains on the surface of the aluminum material after brazing to cause gray or white stains, which causes uneven color tone and impairs the appearance. There is also a problem that it interferes with surface treatments such as painting treatment and corrosion resistance treatment. Moreover, the residual flux adhered to the surface of the aluminum material, and its removal was extremely difficult.

Therefore, recently, a method of brazing in an atmosphere in which the flux is gasified has been proposed (Japanese Patent Laid-Open No. HEI 2).
-147164). When brazing is performed in such an atmosphere containing flux gas, the surface after brazing is supposed to be clean.

[0007]

However, even when brazing is carried out in such an atmosphere containing flux gas, the flux remains on the surface of the aluminum material to cause white spots, which deteriorates the appearance quality and reduces the surface quality. The processability may be deteriorated.

Therefore, as a result of various experiments and studies conducted by the inventor, the residual flux on the surface of the aluminum material during brazing in the above-described atmosphere containing flux gas was found to be
It was found that this is caused by the adsorbed water adsorbed on the surface of the aluminum material before brazing. That is, if the amount of adsorbed water on the surface of the aluminum material is large, the concentration of the flux gas must be increased in order to obtain good brazing properties, and as a result, the amount of the adhered flux on the surface of the brazed product increases and the excess flux Was found to remain on the surface of the brazed product.

The present invention has been made on the basis of the above findings, and in brazing in an atmosphere containing a flux gas, flux residue on the surface of an aluminum brazed product can be eliminated, resulting in excellent appearance quality and surface treatability. The present invention also aims at enabling excellent brazing, and provides a brazing device for this purpose.

[0010]

In order to achieve the above object, the present invention shows, with reference to the reference numerals in the drawings, a brazing furnace (1) having an inlet portion (2) and an outlet portion (7). And a transfer device (3) for sequentially and continuously transferring the plurality of aluminum joining members (A) from the inlet part (2) to the outlet part (7) of the brazing furnace (1), The brazing furnace (1) has a preheating section (4) provided near the inlet side for preheating the aluminum joining member (A) carried into the furnace, and an exit side of the preheating section (4). A flux gas supply section (5) which is provided in the vicinity of the furnace and supplies a flux gas to the aluminum joining member, and an inert gas supply section (8) which makes the atmosphere of the furnace an inert gas atmosphere. The feature is a continuous brazing furnace for flux gas brazing of aluminum material. .

[0011]

The aluminum joining member (A) placed on the carrier device (3) and continuously carried into the brazing furnace from the inlet portion (2) is preheated while passing through the preheating portion (4). The surface-adsorbed water is removed by evaporation. On the other hand, the flux gas is supplied from the flux gas supply part (5), and the entire zone becomes the flux gas-containing atmosphere. Aluminum joining member (A) that has passed through the preheating section (4) in this atmosphere
Enters and the flux is supplied to the aluminum joining member (A).

Since the surface-adsorbed water of the aluminum joining member (A) is removed by evaporation, the flux action is not hindered and good brazing can be achieved with a small amount of flux.

[0013]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1A shows a brazing apparatus according to the first embodiment of the present invention. In the figure, (1) is a brazing furnace, and an inlet portion (2) is provided at one end of the brazing furnace and an outlet portion (7) is provided at the other end. Then, a plurality of aluminum joining members (A) placed on the conveyor (3) at predetermined intervals are continuously carried into the furnace from the inlet portion (2) and transferred toward the outlet portion (7). Has been done.

The brazing furnace (1) is provided with a preheating section (4) on the inlet side over a predetermined range. The preheating section (4) plays a role of preheating the aluminum joining member (A) carried into the furnace to evaporate and remove the surface adsorbed water. Further, in the furnace (1), a flux gas supply part (5) is provided continuously to the preheating part (4), and the flux gas from this flux gas supply part (5) is brazed using N2 gas as a carrier gas. It is designed to be jetted downward into the furnace (1). Then, the supplied flux gas is made to exist uniformly in the atmosphere, and even if the aluminum joining member (A) has a complicated shape, the flux gas is circulated to the details of the aluminum joining member (A) at the flux gas ejection port (5a). A propeller-shaped stirrer (6) is provided in the vicinity of the inlet side of the brazing furnace.

Further, an N2 gas supply section (8) as an inert gas supply section is provided between the flux gas supply section (5) and the outlet section (7) of the brazing furnace (1), N2 gas is supplied from the N2 gas supply section (8) to the brazing furnace (1).
It is designed to be jetted and supplied toward the inlet side and the outlet side. Then, the inside of the furnace is set to the N2 gas atmosphere by this. Thus, N2
The gas is ejected toward the inlet side and the outlet side because the moisture on the surface of the joining member evaporated in the preheating section (4) is pushed toward the inlet side by the N2 gas ejected toward the inlet side and the inlet side exhaust port ( This is to prevent water from entering from the outlet portion (7) by N2 gas ejected toward the outlet side while being discharged from 9). The N2 gas ejected toward the outlet side is discharged from the outlet side exhaust port (10). The N2 gas flow rate is 1 to 20 at an average flow rate.
It is better to adjust so that it is cm / sec. Note that N
2 The gas supply part (8) does not necessarily have to be provided at the position on the outlet side with respect to the flux gas supply part (5).

In the brazing furnace shown in FIG. 1 (a), the aluminum joining member (A) is placed on the conveyor (3) and continuously carried into the brazing furnace from the inlet portion (2).
Is preheated while passing through the preheating section (4), and its temperature gradually rises. FIG. 1B shows the transition of the surface temperature of the aluminum joining member (A) transferred in the brazing furnace (1) corresponding to the position in the furnace. The surface-adsorbed water of the aluminum joining member (A) is evaporated and removed while it is preheated. Preheating time is 5 to promote effective removal of adsorbed water.
It is good to set it to about 20 minutes. The removed moisture is N
2 N2 ejected from the gas supply part (8) toward the inlet side
The gas flow is pushed to the inlet side and discharged from the inlet side exhaust port (9) to the outside of the furnace. On the other hand, the flux gas is supplied from the flux gas supply unit (5) using N2 gas as a carrier gas and stirred by the stirrer (6).
An area around the spouting port (5a) is made to have a flux gas containing N2 atmosphere around the center.

It is preferable to supply the above-mentioned flux gas so that the concentration of the flux gas in the atmosphere is 200 ppm or less. If the flux gas concentration exceeds 200 ppm, the amount of flux may be too large, and whitening may occur due to the residue of flux remaining on the brazed product.
This is because when the concentration is specified to be ppm or less, sufficient brazing and joining can be realized without causing flux residue and residue. Particularly preferable flux gas concentration is 20
~ 65 ppm.

Here, the term "flux gas" means vaporized flux. The type of flux is not particularly limited, but a non-corrosive fluoride-based flux such as KA
Examples thereof include a complex mixture in which 1F ₄ or other aluminum fluoride (AlF ₃ ) component and potassium fluoride (KF) component are contained in a eutectic composition or a composition range close thereto to form a complex. Most preferably, KAlF ₄ is used in terms of good flux action and gasification easiness.

When KAlF ₄ is used as the flux, it is preferable to set the concentration ratio of moisture to flux gas in the atmosphere to a moisture concentration of 1 and a flux gas concentration of more than 1. This is due to moisture in the atmosphere and KAlF
₄ is the following chemical formula

[Chemical 1] In since there is a risk that KAlF ₄ disappears with equal volume reaction as indicated, the amount of KAlF ₄ set larger than the water content, KAlF ₄ even when the complete response
Is to remain in the atmosphere. Particularly preferably, the concentration ratio of water to flux gas is set to 1: 1.1 or more.

By the way, if HF is contained in the atmosphere, HF reacts with Al of the aluminum material to form AlF ₃
It is preferable to regulate the HF concentration in the brazing atmosphere to 60 ppm or less in order to form a dense film such as that which impedes the wettability of the braze.

At the time of supplying the above-mentioned flux gas, the water concentration in the atmosphere must be regulated to 60 ppm or less. When the water concentration exceeds 60 ppm, the growth of the oxide film on the surface of the aluminum material is promoted despite the removal of the water adsorbed on the surface of the aluminum material. Therefore, a large amount of flux is still required to sufficiently remove the oxide film. Because. Therefore, by regulating the water concentration at the time of supplying the flux gas to 60 ppm or less, it is possible to effectively remove the adsorbed water on the surface of the aluminum material while suppressing the growth of the oxide film. Particularly preferred water concentration is 30
It is below ppm.

Aluminum joining member (A) which has passed through the preheating part (4) in the atmosphere containing the flux gas as described above.
However, in this embodiment, the temperature of the joining member is 40
The length of the preheating part (4), the position of the flux gas supply part (5), the speed of the conveyor (3), etc. are set so as to enter the above flux gas atmosphere when the temperature reaches 0 to 570 ° C. .. As described above, the flux gas is supplied when the temperature of the aluminum joining member is 400 to 570 ° C. The aluminum joining member is preheated and the adsorbed water on the surface thereof is increased before the temperature of the aluminum joining member reaches 400 ° C. Is effectively removed without being hindered by the flux film.

The flux in the atmosphere thus supplied to the aluminum joining member (A) is presumed to effectively adhere to the surface of the joining member at a temperature slightly lower than the brazing temperature. 200 pp
It is presumed that most of them can be adhered to the aluminum joining member (A) by setting it to be m or less. Therefore, there is no inconvenience that the flux gas flows out toward the preheating portion (4) and the preheating portion becomes a flux gas atmosphere.

Thereafter, as the conveyor (3) progresses, the temperature of the aluminum joining member (A) further rises and the brazing material is melted to achieve brazing joining.

After brazing, the joining member (A) is cooled by the time from the N2 gas supply section (8) to the outlet section (7) and is carried out of the furnace from the outlet section (7).

After adjusting the atmosphere in the furnace to a flux gas concentration within a predetermined range as described above, an aluminum material having a lower melting point than the aluminum joining member in this atmosphere is used, and the temperature is 590 to 610 ° C. × 1 to 15 as in the conventional case. The brazing material is melted by heating for about a minute to achieve brazing. At the time of brazing, the flux gas in the furnace effectively exhibits a flux action, and good brazing joining is achieved without causing residue of flux adhesion.

Incidentally, the following brazing test was carried out using the brazing apparatus shown in FIG.

That is, using an A1100 extruded tube material having a wall thickness of 0.75 mm and an A3003 alloy as a core material, Al-10%
Clad rate 9%, thickness 0.15m, made of Si alloy
A corrugated heat exchanger was assembled using the fin material of the double-sided brazing sheet of m.

Then, the above assembly is placed on a conveyor and carried into a brazing furnace (1) in an N 2 gas atmosphere shown in FIG. 1 (a), and first preheated in a preheating section (4) to evaporate adsorbed water on the surface. Removed.

Next, after continuously conveying to the flux gas supply section (5) to supply the KAlF ₄ flood gas to the heat exchanger assembly, brazing was performed. The temperature of the heat exchanger assembly at the time of supplying the flux gas was 460 ° C. In addition, the moisture concentration in the flux gas atmosphere is 20
ppm and the flux gas concentration was 50 ppm.

When the brazability and appearance of the brazed product obtained as described above were visually observed, sufficient fillets were formed at the joints, and no residual flux could be visually confirmed, and the appearance was extremely clean. there were. Also, after each brazing product was treated with phosphoric acid chromate and spray-coated with an acrylic resin, a 1 mm square square was marked on the surface of the coating film and a tape peeling test was conducted to find the number of squares remaining on the coating film. When the surface treatment property was evaluated by (cross-cut test), no peeling of the coating film was observed.

FIG. 2A shows a brazing device according to the second embodiment of the present invention. In addition, in FIG.
The same reference numerals are given to the same names as those of the brazing device shown in (a).

In this brazing apparatus, the preheating section (4) is set in a relatively wide range, and the flux gas from the flux gas supply section (5) is introduced into the brazing furnace (1) by using N 2 gas as the carrier gas. It is supposed to be jetted and supplied toward the side. Moreover, the N2 gas is supplied from the N2 gas supply section (8) toward the outlet side in the brazing furnace (1).
2 Gas is supposed to prevent water from entering through the outlet (7). This is because.

In the brazing furnace shown in FIG. 2 (a),
Aluminum joining member (A) placed on the conveyor (3) and continuously carried into the brazing furnace from the inlet (2)
Is preheated while passing through the preheating section (4), and its temperature gradually rises. FIG. 1B shows the transition of the surface temperature of the aluminum joining member (A) transferred in the brazing furnace (1) corresponding to the position in the furnace. The surface-adsorbed water of the aluminum joining member (A) is evaporated and removed while it is preheated. On the other hand, the flux gas is supplied from the flux gas supply unit (5) using N2 gas as a carrier gas and is agitated by the agitator (6). There is. The aluminum joining member (A) that has passed through the preheating section (4) enters this atmosphere, but in this embodiment, it enters the above flux gas atmosphere when the temperature of the joining member reaches 570 to 605 ° C. Thus, the length of the preheating part (4), the position of the flux gas supply part (5), the speed of the conveyor (3), etc. are set. As described above, the flux gas is supplied when the temperature of the aluminum joining member is 570 to 605 ° C. The aluminum joining member is preheated by the time the temperature of the aluminum joining member reaches 570 ° C. This is because the flux gas can be effectively removed without being hindered by the flux film, and the amount of the flux gas can be small. That is, if the temperature is lower than 570 ° C., the surface-adsorbed water of the aluminum material is not sufficiently removed, or the aluminum joining member is not in a sufficiently active state for the adhesion of the flux, resulting in a large amount of flux used. Will end up. On the other hand, when the temperature exceeds 605 ° C., the brazing filler metal melts, which causes brazing failure due to the delay of the flux supply.

Thereafter, as the conveyor (3) advances, the temperature of the aluminum joining member (A) further rises, the brazing material melts, and brazing joining is achieved.

After brazing, the joining member (A) is cooled by the time from the N2 gas supply section (8) to the outlet section (7) and is carried out of the furnace from the outlet section (7).

Incidentally, the following brazing test was carried out using the brazing apparatus shown in FIG.

That is, using an A1100 extruded tube material having a wall thickness of 0.75 mm and an A3003 alloy as a core material, Al-10%
Clad rate 9%, thickness 0.15m, made of Si alloy
A corrugated heat exchanger was assembled using the fin material of the double-sided brazing sheet of m.

Then, the above assembly is placed on a conveyor and carried into a brazing furnace (1) in an N 2 gas atmosphere shown in FIG. 2 (a). First, preheating is performed in a preheating section (4) to evaporate the adsorbed water on the surface. Removed.

Next, after being continuously conveyed to the flux gas supply section (5) to supply the KAlF ₄ flood gas to the heat exchanger assembly, brazing was performed. The temperature of the heat exchanger assembly at the time of supplying the flux gas was 590 ° C. In addition, the moisture concentration in the flux gas atmosphere is 20
ppm and the flux gas concentration was 30 ppm.
When the brazing property and appearance of the brazed product obtained as described above were visually observed, a sufficient fillet was formed at the joint, and no residual flux could be visually confirmed, and the appearance was extremely clean. Further, when the surface treatment property was evaluated by a cross-cut test, no peeling of the coating film was observed.

[0042]

As described above, according to the present invention, a brazing furnace having an inlet portion and an outlet portion, and a plurality of aluminum joining members are sequentially and continuously conveyed from the inlet portion to the outlet portion of the brazing furnace. Further, the brazing furnace is provided in the vicinity of the inlet side, and a preheating section for preheating the aluminum joining member carried into the furnace, and in the vicinity of the exit side of the preheating section. It is characterized in that it is provided with a flux gas supply part for supplying a flux gas to the aluminum joining member and an inert gas supply part for making the inside of the furnace an inert gas atmosphere. The member can be preheated in the preheating unit, and the surface-adsorbed water can be removed by evaporation. Then, after removing the surface adsorbed water, since the flux gas can be supplied to the aluminum joining member from the flux gas supply unit, it is possible to perform brazing in the absence of the surface adsorbed water that hinders the flux action, The amount of flux used can be suppressed to a necessary minimum. Therefore, while ensuring sufficient brazing property, it is possible to eliminate flux residue on the surface of aluminum material after brazing by reducing the amount of flux used, and to provide an aluminum brazed product with excellent appearance quality and high commercial value. Can be provided. In addition, it is possible to provide a brazed product having excellent adhesion without peeling of the film or coating even when surface treatment such as chemical treatment or coating is performed after brazing.

[Brief description of drawings]

FIG. 1A is a schematic configuration diagram of a continuous brazing furnace according to a first embodiment of the present invention. (B) is a graph showing a temperature state of the aluminum joining member transferred in the brazing furnace of (A).

FIG. 2A is a schematic configuration diagram of a continuous brazing furnace according to a second embodiment of the present invention. (B) is a graph showing a temperature state of the aluminum joining member transferred in the brazing furnace of (A).

[Explanation of symbols]

 A ... Aluminum joining member 1 ... Brazing furnace 2 ... Inlet part 3 ... Conveying device 4 ... Preheating part 5 ... Flux gas supply part 7 ... Exit part 8 ... Inert gas supply part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Sato 6-224 Kaiyamacho, Sakai City, Osaka Prefecture Showa Aluminum Co., Ltd.

Claims (1)

[Claims] 1. A brazing furnace (1) having an inlet part (2) and an outlet part (7), and a plurality of aluminums from the inlet part (2) of the brazing furnace (1) to the outlet part (7). A transfer device (3) for sequentially and continuously transferring the joining member (A) is provided, and further, the brazing furnace (1) is provided close to the inlet side and is carried into the furnace. Aluminum joining member (A)
And a preheating part (4) for preheating, a flux gas supplying part (5) provided in proximity to the exit side of the preheating part (4) for supplying flux gas to the aluminum joining member, and an inert gas atmosphere in the furnace. A continuous brazing furnace for flux gas brazing of aluminum material, comprising: an inert gas supply part (8).