JP2003094164A - Brazing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brazing method in which the strength and corrosion resistance of a member to which a female thread is formed can be sufficiently secured, and at the same time, the female thread forming member can be brazed more rationally. SOLUTION: The brazing method in which a plurality of aluminum members are integrally brazed by using a fluoride system flux with an atmosphere of an inert gas, is so constituted that at least one of the plurality of aluminum members is the female thread forming member to which the female thread to be screwed with a bolt is formed, the magnesium content of the female thread forming member is 0.40-0.70 [wt.%], and furthermore, the magnesium content of the other aluminum member which is brazed with the female thread forming member is smaller than the female thread forming member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing method for brazing a plurality of aluminum members using a fluorinated flux in an inert gas atmosphere.

[0002]

2. Description of the Related Art A brazing method called an NB method is adopted for manufacturing a heat exchanger. This NB method is a method of brazing an aluminum member in an inert gas atmosphere using a fluorinated flux. KAlF The fluoride-based flux, which is based on KF and AlF _{3 4, K 3
AlF 6, K 2 AlF 5,} K 2 AlF 5 · H 2 O or the like is used. Such a fluorinated flux is mixed with water or another solution to form a slurry, which is applied to the aluminum member. The aluminum member is sent to a brazing furnace after the flux is sufficiently dried. The inert atmosphere is an atmosphere sealed with an inert gas such as nitrogen gas or dry air.

In recent years, a method of further improving the NB method and applying a mixture of a silicon powder and a fluorinated flux to perform brazing has been developed. Such a brazing method produces a brazing material from the surface layer of the base material and has an advantage that it is not necessary to use a brazing sheet in which the brazing material is clad. The mechanism is as follows. First, in the process of reaching the brazing temperature, the flux melts and the aluminum oxide film is removed. Next, silicon particles come into contact with the aluminum surface from which the oxide film has been removed, and solid-phase diffusion of silicon with respect to aluminum occurs. Furthermore, as the temperature rises, the silicon particles diffuse into the liquid, and
A molten alloy of or near 1-Si eutectic is formed.
The molten metal is brought to the joint by flowing due to a capillary phenomenon or the like. Then, as the temperature decreases, the molten metal solidifies and a fillet is formed.

[0004]

By the way, it is well known that an Al-Mg alloy containing magnesium is advantageous for securing strength and corrosion resistance of an aluminum member.

However, in the above-mentioned NB method, magnesium contained in the aluminum member causes a decrease in brazing property. This is because the fluorinated flux easily reacts with magnesium. It has also been confirmed that when magnesium reacts with the flux, MgF is generated and the MgF adversely affects the flow of the molten alloy. Therefore, generally, about 0.40 [wt%] of magnesium is added.
The aluminum member including the above is considered to be somewhat unsuitable for the NB method.

However, depending on the type of aluminum member, a female screw for screwing a bolt may be formed, and magnesium must be contained to some extent in order to secure the strength and corrosion resistance of the female screw.

In particular, the strength of the aluminum member is also improved by adding zinc to aluminum.
However, when the content of zinc is high, the aluminum member becomes an anode and the corrosion resistance is impaired. Normally, the content of zinc in the female screw forming member is about 0.25 [wt].
%] Or less.

[0008] However, regarding the radiator and evaporator of the refrigeration cycle, and the heat exchanger such as the radiator and the heater core of the automobile, it is extremely important to secure the brazing property of the female thread forming member by the NB method at the manufacturing site thereof. It has become a challenge.

The present invention has been made in view of such circumstances, and it is possible to sufficiently secure the strength and corrosion resistance of a member having a female screw formed therein, and to braze the female screw forming member more reasonably. It is intended to provide a brazing method.

[0010]

The invention described in the first claim of the present application is a brazing method for integrally brazing a plurality of aluminum members using a fluorinated flux in an inert gas atmosphere. At least one of the aluminum members is a female screw forming member in which a female screw for screwing a bolt is formed, and the female screw forming member has a magnesium content of 0.40 to 0.70 [wt%], Further, the other aluminum member to be brazed to the female screw forming member is a brazing method having a structure in which the content of magnesium is smaller than that of the female screw forming member. It is possible to sufficiently secure the above and reasonably braze the female thread forming member.

That is, in such a brazing method, the magnesium contained in the aluminum member causes the brazing property to deteriorate, and the magnesium content is reduced to about 0.40.
An aluminum member containing [wt%] or more is said to be somewhat unsuitable for the NB method. In this respect, in the present invention, the magnesium content of the female thread forming member is 0.40 to 0.70.
By setting it to [wt%] to ensure sufficient strength of the female thread forming member, and by setting the content of magnesium in the other aluminum member to be brazed to the female thread forming member to be relatively small, Generation of MgF in one surface layer is suppressed to some extent, and the fluidity of the molten metal during brazing is maintained well.

As described above, the present invention is a brazing method that achieves a remarkable effect by summarizing each condition while considering the strength, corrosion resistance, and brazing property of the female thread forming member.

According to the second aspect of the present invention, the other aluminum member brazed to the female screw forming member is
Magnesium content is 0.01 to 0.40 [wt%]
According to the brazing method having the above configuration, the female thread forming member can be brazed more rationally.

That is, the present invention is a brazing method capable of obtaining excellent brazing property by more surely suppressing the generation of MgF in one surface layer of the joining portion of the aluminum member.

According to the third aspect of the present invention, the internal thread forming member has a zinc content of 0.01 to 0.25.
This is a brazing method having a constitution of [wt%]. With such a constitution, it is possible to sufficiently secure the strength and corrosion resistance of the female screw forming member.

That is, the strength of the aluminum member is improved by adding zinc to aluminum,
When the content of zinc is high, the aluminum member becomes an anode and the corrosion resistance is impaired. Therefore, the present invention, by setting the content of magnesium in the internal thread forming member to a range where brazing is satisfactory, and by setting the content of zinc to such an extent that corrosion resistance is not impaired,
The internal thread forming member is configured to ensure a good balance of strength and corrosion resistance.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION A specific example of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the brazing method of this embodiment is a brazing method in which a plurality of aluminum members are integrally brazed in an inert gas atmosphere using a fluorinated flux.

As the fluorinated flux, KF and Al
F_ThreeBased KAlF_Four, K _ThreeAlF₆, K_TwoA
IF₅, K_TwoAlF₅・ H_TwoO etc. are used.

The brazing material is clad to at least one aluminum member. Alternatively, a brazing material is produced from the surface layer of the base material by applying a mixture of silicon powder and a fluorinated flux to the aluminum member.

A plurality of aluminum members are provided with a flux and a brazing filler metal and assembled by using a jig. When the flux is sufficiently dried, a brazing furnace in an inert gas atmosphere sealed with nitrogen gas or dry air is used. Sent to.

Further, at least one of the plurality of aluminum members is a female screw forming member having a female screw formed therein for screwing a bolt. This female screw forming member has a magnesium content of 0.40 to 0.70 [wt%] and a zinc content of 0.01 to 0.25 [wt%].

The content of magnesium in the other aluminum member to be brazed to the female screw forming member is 0.01 to 0.40 [wt%], which is smaller than that in the female screw forming member.

In this example, the heat exchanger 1 shown in FIGS. 2 to 6 is manufactured by utilizing such a brazing method.

The heat exchanger 1 shown in these figures has fins 3
, A plurality of tubes 200 stacked together with a plurality of tubes 200, a pair of tanks 400 to which both ends of the tubes 200 are connected, an inlet and an outlet connector 500 respectively provided at important points of the tank, and the tubes 200. And side plates 600 that are reinforcing members provided above and below the fins 300 in the stacking direction.

An external pipe 700 that circulates a medium is connected to each connector 500, and the medium flows in from the connector 500 for the inlet and the tubes 200 and the fins 30.
After passing through the tube 200 while exchanging heat with the heat transferred to 0, it is discharged from the outlet connector 500.

The heat exchanger 1 is manufactured by assembling a plurality of aluminum members constituting the tube 200, the fin 300, the tank 400, the connector 500, and the side plate 600, and brazing the assembled body.

The tank 400 has a cylindrical shape, and the partition member 410 for partitioning the inside thereof and the tube 2 are provided.
00 is provided with a substantially semi-cylindrical first tank member 420 in which tube connection holes 421 for connecting the end portions of 00 are arranged, and a second semi-cylindrical second tank member 430 assembled with the first tank member 420. There is. A connector connection hole 43 for connecting the connector 500 is provided at a key part of the second tank member 430.
1 is provided.

The connector 500 of this embodiment is a block-shaped female screw forming member in which a female screw 510 for screwing the bolt B is formed. That is, each connector 500 is a member formed by processing an internal thread 510 on an aluminum alloy casting or die casting, and has a magnesium content of 0.40 to 0.
70 [wt%] and a zinc content of 0.0
It is 1 to 0.25 [wt%]. The second tank member 430 is a member formed by press-molding a plate made of an aluminum alloy and has a magnesium content smaller than that of the connector 500. In the case of this example, the magnesium content of the second tank member 430 is
It is 0.01 to 0.04 [wt%].

The connector 500 is provided with a pipe connector 710 provided at the tip of the external pipe 700. The pipe connector 710 is provided with a bolt insertion portion 711 through which the bolt B is inserted. The bolt B is inserted into the bolt insertion portion 711 and the female screw portion 510 of the connector 500 is inserted.
Is screwed onto. The flow path 520 of the connector 500 and the flow path 712 of the pipe connector 710 are connected via an O-ring R.

The connector 500 has a positioning hole 530.
In addition, the piping connector 710 is provided with a positioning pin 713 that matches the positioning hole 530. When connecting the connector 500 and the piping connector 710,
If these positioning holes 530 and the positioning pins 730 are matched, it is possible to prevent a situation in which another pipe is erroneously connected to the connector 500, and the efficiency of connection work can be improved.

Further, the connector 500 is provided with a caulking piece 540 which is engaged with the second tank member 430. The crimping piece 540 is provided in one opening of the flow path 520 and is inserted into the connector connection hole 431.
It is plastically deformed so as to press the peripheral edge of the connector connection hole 431. According to such a configuration, the second tank member 4
The 30 and the connector 500 can be firmly assembled, and the reliability of brazing can be improved.

As described above, the present example is a brazing method capable of satisfactorily securing the strength and corrosion resistance of the female screw forming member and rationally brazing the female screw forming member. It can be used very suitably for manufacturing.

[0034]

The invention described in the first claim of the present application is a brazing method for integrally brazing a plurality of aluminum members in an inert gas atmosphere using a fluorinated flux. At least one is a female screw forming member in which a female screw for screwing a bolt is formed, and the female screw forming member has a magnesium content of 0.40 to 0.70 [wt%], and further, the female screw. The other aluminum member to be brazed with the forming member is a brazing method in which the content of magnesium is smaller than that of the female screw forming member. With such a constitution, the strength and corrosion resistance of the female screw forming member are sufficiently secured. In addition, the internal thread forming member can be reasonably brazed.

According to the second aspect of the present invention, the other aluminum member to be brazed to the female thread forming member is
Magnesium content is 0.01 to 0.40 [wt%]
According to this configuration, the female screw forming member can be brazed more rationally.

According to the third aspect of the present invention, the internal thread forming member has a zinc content of 0.01 to 0.25.
This is a brazing method having a constitution of [wt%]. With such a constitution, the strength and corrosion resistance of the female screw forming member can be sufficiently secured.

[Brief description of drawings]

FIG. 1 is a table showing an outline of a brazing method according to a specific example of the present invention.

FIG. 2 is a front view showing a heat exchanger according to a specific example of the present invention.

FIG. 3 is a front perspective view showing a connector according to a specific example of the present invention.

FIG. 4 is a rear perspective view showing a connector according to a specific example of the present invention.

FIG. 5 is an exploded perspective view showing a tank according to a specific example of the present invention.

FIG. 6 is a cross-sectional view showing an external pipe and a connector according to a specific example of the present invention.

[Explanation of symbols]

1 heat exchanger 200 tubes 300 fins 400 tanks 410 Partition member 420 First tank member 421 Tube connection hole 430 Second tank member 431 Connector connection hole 500 connector 510 female screw 520 flow path 530 Positioning hole 540 caulking piece 600 side plate 700 External piping 710 Piping connector 711 Bolt insertion part 712 Positioning pin 713 flow path B bolt RO ring

Claims (3)

[Claims] 1. A brazing method for integrally brazing a plurality of aluminum members using a fluorinated flux in an inert gas atmosphere, wherein at least one of the plurality of aluminum members comprises:
A female screw forming member in which a female screw for screwing a bolt is formed, wherein the female screw forming member has a magnesium content of 0.4.
0 to 0.70 [wt%], and the other aluminum member to be brazed to the female screw forming member has a magnesium content smaller than that of the female screw forming member. 2. The magnesium content of the other aluminum member to be brazed to the female thread forming member is 0.01.
~ 0.40 [wt%].
Brazing method described. 3. The brazing method according to claim 1, wherein the internal thread forming member has a zinc content of 0.01 to 0.25 [wt%].