JP3337417B2 - Aluminum brazing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for brazing aluminum, for example, a method for brazing aluminum applied to joining and assembling various members in the electric field, vehicle field, heat exchanger field and the like.

[0002]

2. Description of the Related Art Brazing joining between aluminum materials is as follows.
Normally, a brazing sheet in which an Al-Si-based brazing material is clad on an aluminum material is used, and after the brazing sheet is assembled in a predetermined joining shape, the brazing sheet is charged into a brazing furnace and heated to a brazing temperature. Done. In the case of small parts, a brazing sheet may be formed into a predetermined shape and used, or a brazing material may be supplied to the brazing joint from the outside and heated by a torch or the like.

In this case, in order to perform sufficient bonding, it is necessary to destroy and remove the strong aluminum oxide existing on the surface of the aluminum. Usually, a flux is suspended in water or alcohol on the brazing surface. After spraying and evaporating the solvent, a brazing operation is performed.

However, when the shape of the brazing product or brazing joint is complicated, it is often difficult to uniformly apply the suspension of the flux to the surface of the brazing member. If the amount of flux is small, strong brazing is hindered.If the amount of applied flux is excessive, the flux falls off in the brazing furnace, causing contamination and corrosion inside the furnace, and the product after brazing. The bad effect of impairing the appearance has occurred.

In recent years, in order to omit the flux application operation immediately before brazing, a method of applying a flux to a surface of a material to be brazed, a method of applying a mixed composition of a flux and a brazing material, and applying in advance. Brazing compositions have been proposed. (JP-A-3-35870, JP-A-6-285681, JP-T-6-504485, Patent No. 2681380, Patent No.26813
No. 89)

According to these methods, even when the shape of a brazing product or brazing joint is complicated, it is possible to apply a flux to the surface of the material to be brazed, and a mixed composition of the flux and the brazing material can be used. In the case of application, there is no need to use an expensive brazing sheet clad with an Al-Si brazing material, and an aluminum plate not clad with a brazing material can be used. Another advantage is that the problem of mold wear caused by the Al-Si brazing material layer can be solved.

When the application area on the aluminum member is large, the application operation can be performed by a spraying method, a dipping method, a roll transfer method, etc. However, the spraying method has poor coating efficiency and the spray gun is also clogged. In the immersion method, it is easy to apply a composition with a constant composition ratio at high speed due to precipitation of the brazing powder or the flux powder. Excellent mass production effect and efficient.

However, Japanese Patent Application Laid-Open No. 3-35870, Japanese Patent No. 2681380, and Japanese Patent No. 268138
As described in Japanese Patent Publication No. 9, when a brazing composition using, as a binder, a resin made of an ethylene-based hydrocarbon such as an acrylic resin among organic resins volatilized by brazing heating, is applied by roll transfer. Tends to have many places where brazing is not sufficiently performed. Further, in order to improve the wettability of the flux composition to the aluminum material, when a composition obtained by adding a surfactant to the composition (Japanese Patent Application Laid-Open No. Hei 6-285681) is roll-transferred, the surfactant becomes the flux composition. The adhesion of the material is hindered, so that the brazing property tends to decrease.

A method using an alcohol such as isopropyl alcohol as a coating medium (Japanese Patent Application Laid-Open No. 6-50448)
No. 5) also has a problem that precipitation of the brazing filler metal powder or flux powder easily occurs in an alcohol solution, transferability is poor, sufficient adhesion is not always obtained, and strong brazing bonding cannot be achieved.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems in the case where a flux or a flux and a brazing material are previously coated on an aluminum member. In order to apply the brazing flux composition, the brazing composition containing the flux and the brazing material continuously and effectively at a high speed by a roll transfer method, the synthetic resin in the composition, the synthetic resin dissolved in the flux and the brazing material The purpose of this study was to conduct various experiments and studies on the organic solvent for suspending, the flux in the composition, the weight ratio of the brazing filler metal and the synthetic resin, and the combination of these. Is
An object of the present invention is to provide a method of brazing aluminum in which the transferability and adhesion of the composition to an aluminum member to be brazed are good and a strong brazed joint is obtained.

[0011]

According to a first aspect of the present invention, there is provided a method for brazing aluminum according to the present invention, in which a polymer of methacrylate or a copolymer of methacrylate is coated on the surface of an aluminum member. An organic solvent in which a synthetic resin having a coalescence as a main component dissolves and having an atomic ratio of carbon to oxygen in the molecular structure of 2 to 3 (excluding propanol), the synthetic resin having a weight ratio of 90 to 90 After applying a flux mixture composition obtained by adding 10 to 30% of brazing flux powder to 70%, heating or drying is performed to evaporate the organic solvent in the flux mixture composition. A flux composition comprising the synthetic resin and brazing flux is coated, and the aluminum member coated with the flux composition is brazed. Disposed at the junction, characterized by attaching heat brazing through the brazing material.

According to a second aspect of the present invention, there is provided a method for brazing aluminum, comprising the steps of: dissolving an organic solvent in which a synthetic resin having a methacrylate polymer or a methacrylate copolymer as a main component is dissolved on the surface of the aluminum member; In the molecular structure having an atomic ratio of carbon to oxygen of 2 to 3 (excluding propanol), the ratio by weight is
A brazing mixture composition comprising a brazing flux powder and a brazing material powder added in an amount of 10 to 30% based on 90 to 70% of a synthetic resin is applied, and then heated or dried to obtain a brazing mixture composition. By evaporating the organic solvent inside,
Coating the aluminum member with the brazing composition comprising the synthetic resin, the brazing flux and the brazing material, disposing the coated aluminum member at the brazing joint, and brazing by heating. Features.

According to a third aspect of the present invention, there is provided a method for brazing aluminum according to the first aspect, wherein the application of the flux mixture composition to the surface of the aluminum member is performed by a roll transfer method.

Further, in the method of brazing aluminum according to claim 4 of the present invention, in claim 2, the application of the brazing mixture composition to the surface of the aluminum member is performed by a roll transfer method. .

In the present invention, the brazing flux is
The purpose is to reduce and remove the oxide film formed on the surface of the aluminum member, and to promote the formation of a eutectic alloy of aluminum and brazing material. KF, AlF ₃ , KAl
F ₄ , K ₂ AlF ₅ , K ₃ AlF ₆ , CsF, RbF,
Fluoride-based fluxes such as LiF, NaF, and Ca ₂ F, or those containing these as main components can be most preferably used. When using chloride-based flux, it is necessary to remove the residue after brazing because corrosion of the aluminum material is likely to occur, and when using bromide-based flux, it is necessary to consider handling safety. There is.

As the brazing material, a metal which forms a eutectic alloy with aluminum at the time of brazing, for example, Si, Zn, C
u, Ge, etc. can be used. Also, alloys of these metals and aluminum, which form a eutectic alloy with aluminum during brazing, can be used, and one or more of these metals and alloys can be applied.

As the synthetic resin, a resin having a main component of a polymer of methacrylic acid ester or a copolymer composed of two or more methacrylic acid esters is preferable. Examples of the methacrylic acid ester include methyl methacrylate and ethyl methacrylate. , Propyl methacrylate, 2-methylpropyl methacrylate, normal butyl methacrylate,
Tertiary butyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, diethylaminoethyl methacrylate, 2-hydroxymethacrylate Ethyl, dimethylaminoethyl methacrylate, tert-butylaminoethyl methacrylate, glycidyl methacrylate,
Examples include methtetrahydrofurfuryl methacrylate and the like. These synthetic resins volatilize at the brazing temperature.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a method of coating a flux and a brazing material on an aluminum member to be brazed is as follows: the above-mentioned methacrylate polymer or methacrylate ester is coated on the surface of the aluminum member. A flux mixture composition obtained by adding a brazing flux powder to an organic solvent in which a synthetic resin in which coalescing is a main component is dissolved, or a brazing mixture composition obtained by adding a brazing flux powder and a brazing material powder. After applying by a roll transfer method, the coating is performed by heating or drying to evaporate the organic solvent in the flux mixture composition.
In the case of small parts, the composition can also be coated with a brush.

The organic solvent preferably has an atomic ratio of carbon to oxygen in the molecular structure of the organic solvent of 2 to 3, and preferably has some degree of hydrophilicity from the viewpoint of transferability. As the preferred organic solvent, one or more of ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monoethyl ether and the like are suitably used. However, propanol (2-propanol, 1-propanol) is excluded.

The flux powder and the brazing filler metal powder to be added to the organic solvent are preferably adjusted to a particle diameter of 100 μm or less. In particular, the particle diameter of the brazing filler metal powder is 100 μm
Is preferably not exceeded. If it exceeds 100 μm, precipitation is likely to occur during standing storage of the flux mixture composition and the brazing mixture composition, resulting in poor dispersibility.

The viscosity of the flux mixture composition and the brazing mixture composition is 100 to 100 (viscosity at a rotation speed of 1.0 rpm by an E-type viscometer (temperature: 25 ° C.)).
It is preferably 10,000 mPa · s, and 500 to
More preferably, it is 3000 mPa · s. When the viscosity is less than 100 mPa · s, the composition applied to the surface of the aluminum material has a high specific gravity flux powder or brazing material powder precipitated before drying, so that a large amount of synthetic resin having a low specific gravity is present on the applied surface. Therefore, the brazing property is impaired. If the viscosity exceeds 10,000 mPa · s,
It becomes difficult to apply the composition uniformly, and the transferability is reduced, and a portion with a large amount of coating and a portion with a small amount of coating are formed in the longitudinal direction of the aluminum material. Therefore, the brazing property is reduced.

The ratio of the weight of the brazing flux powder to the weight of the synthetic resin in the flux mixture composition, and the ratio of the total amount of the brazing flux powder and the brazing material powder to the weight of the synthetic resin in the brazing mixture composition are as follows. , 90-70%: 10
-30% is preferable, and excellent brazing jointability can be obtained at this ratio. If the flux powder or the total amount of the flux powder and the brazing filler metal powder exceeds 90%, the adhesion of the composition to the aluminum material becomes insufficient, and peeling tends to occur after application. , The brazing property is impaired, and the cost increases.

[0023]

EXAMPLE 1 As an aluminum member, an A1050 plate (0.5 m thick) was used.
m), and the composition was applied to one side of the composition by roll transfer. After the application, the mixture was passed through a gas furnace at an ambient temperature of 250 ° C. for 8 seconds to evaporate the organic solvent, and then cooled to obtain a test material. Flux powder and brazing filler metal powder are all mesh 33
After passing through a 0 (mesh / inch) sieve, the mixture was sufficiently mixed and dispersed by a sand mill, and an organic solvent was added to adjust the viscosity to a predetermined value. The viscosity was measured using an E-type viscometer (manufactured by Tokimec Co., Ltd.) at a temperature of 25 ° C. and a rotation speed of 1.0 rpm.

Table 1 shows the flux, the brazing material, the synthetic resin, the organic solvent, and the atomic ratio of carbon to oxygen in the organic solvent constituting the composition. In Table 1, the brazing filler metal Si-Zn
Is a mixture of 90 wt% Si powder and 10 wt% Zn powder, Al-S
i is Al-12 wt% Si alloy powder, organic solvent EGMEE is ethylene glycol monoethyl ether, PGMEE is propylene glycol monoethyl ether, DEGME
E is diethylene glycol monoethyl ether, DEG
MBE is diethylene glycol monobutyl ether, T
EGMEE is triethylene glycol monoethyl ether.

[0025]

[Table 1]

The coating amount of the flux mixture composition was adjusted to be 5 g / m ² by flux weight, brazing mixed composition was adjusted to be 5 g / m ² by a brazing material by weight. Table 2 shows the viscosity of the composition, the weight ratio of the flux and the synthetic resin, the total amount of the flux and the brazing material, and the weight ratio of the synthetic resin.

[0027]

[Table 2]

An aluminum member coated with the composition;
A corrugated member formed by meandering a 3003 aluminum alloy plate (thickness 0.1 mm) or an aluminum brazing sheet (thickness 0.1 mm, core material: A3103 alloy, skin material: A4045 alloy, cladding ratio 10%) is applied. After heating for 30 minutes to a temperature of 600 ° C. in a nitrogen gas atmosphere and holding for 3 minutes, brazing was performed by cooling in a furnace to evaluate brazing properties.

The brazing property was evaluated by examining the joining ratio at the joint between the aluminum member and the corrugated member. The joining ratio was expressed as a percentage of the joined portions with respect to 100 joined portions. Table 3 shows the evaluation results of the adhesion, transferability and brazing ability of the composition.
Shown in As can be seen in Table 3, the test material N according to the present invention
o. In all of the cases using Nos. 1 to 13, excellent brazing properties with a joining ratio of 95% or more were obtained.

[0030]

[Table 3]

Comparative Example 1 The same aluminum member as in Example 1 was used, and the composition was applied to one surface of the aluminum member according to the same method and conditions as in Example 1. After the application, the organic solvent was evaporated in a gas furnace at an ambient temperature of 250 ° C. for 8 seconds to cool the organic solvent in the same manner as in Example 1, and then cooled to obtain a test material.

The application amount of the flux mixture composition was adjusted to be 5 g / m ^{2 in} terms of the flux weight as in Example 1, and the brazing mixture composition was 5 g / m ^{2 in} terms of the brazing material weight.
Adjusted to be ² . Flux constituting the composition,
Table 4 shows the atomic ratio of carbon to oxygen of the brazing material, the synthetic resin, the organic solvent and the organic solvent, and shows the viscosity of the composition, the weight ratio of the flux and the synthetic resin, the total amount of the flux and the brazing material, and the weight ratio of the synthetic resin. Are shown in Table 5.

[0033]

[Table 4]

[0034]

[Table 5]

The brazing property of the aluminum member coated with the composition was evaluated in the same manner as in Example 1. Table 6 shows the evaluation results. As shown in Table 6, the test materials out of the conditions of the present invention have poor brazing properties.

[0036]

[Table 6]

[0037]

According to the present invention, the flux composition or the brazing composition can be precoated uniformly on the aluminum member to be brazed with good transferability and adhesion, and the flux application step during brazing can be omitted. A brazing method is provided which enables the use of an aluminum member which does not clad a brazing material in place of the brazing sheet.

Continuation of the front page (51) Int.Cl. ⁷ identification symbol FI B23K 35/363 B23K 35/363 F C09D 5/38 C09D 5/38 (58) Investigated field (Int.Cl. ⁷ , DB name) B23K 1 / 19 B23K 1/20 B23K 3/00 B23K 35/14 B23K 35/22 B23K 35/363 C09D 5/38

Claims (4)

(57) [Claims] 1. An organic solvent in which a synthetic resin having a methacrylic acid ester polymer or a methacrylic acid ester copolymer as a main component dissolves on the surface of an aluminum member, and has an atomic ratio of carbon to oxygen in the molecular structure. Is 2 to 3 (however, excluding propanol), by weight ratio,
After applying a flux mixture composition obtained by adding 10 to 30% brazing flux powder to 90 to 70% of the synthetic resin, heating or drying to evaporate the organic solvent in the flux mixture composition. Coating an aluminum member with a flux composition comprising the synthetic resin and brazing flux, disposing the aluminum member coated with the flux composition at a brazing joint, and brazing by heating via the brazing material. A brazing method for aluminum, comprising the steps of: 2. An organic solvent in which a synthetic resin containing a methacrylic acid ester polymer or a methacrylic acid ester copolymer as a main component is dissolved on the surface of an aluminum member, and the atomic ratio of carbon to oxygen in the molecular structure is 2. Is 2 to 3 (however, excluding propanol), by weight ratio,
After applying a brazing mixture composition obtained by adding 10-30% of brazing flux powder and brazing material powder to 90-70% of the synthetic resin, the mixture is heated or dried to form a brazing mixture composition. By evaporating the organic solvent of the above, the synthetic resin on the aluminum member, brazing flux,
A brazing composition comprising a brazing material and a brazing material, disposing an aluminum member coated with the brazing composition at a brazing joint, and brazing by heating. 3. The method according to claim 1, wherein the application of the flux mixture composition to the surface of the aluminum member is performed by a roll transfer method. 4. The method according to claim 2, wherein the application of the brazing mixture composition to the surface of the aluminum member is performed by a roll transfer method.