JPS5854909B2 - Method for manufacturing hollow structures by vacuum brazing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a hollow structure using a vacuum brazing method.

In recent years, aluminum alloy sheets have been increasingly joined by vacuum brazing, which does not require flux.

For this reason, various core material alloys and skin material alloys have been developed as vacuum brazing sheets for use in the tubular fin materials of heat exchangers.

The structure of the vacuum brazing sheet most commonly used in the past is to use JIS3003 alloy as the core material, Si with a weight of about 10% as the skin material, and M with a weight of about 1.7% as the skin material.
This is made by cladding the same type of skin material on both sides of the core material of an aluminum alloy containing g.

The first step was to confirm the performance of this brazing sheet.
As shown in the figure, the core material 1 with a thickness of 0.8
In the brazing sheet 3 in which the skin materials 2 and 2 are made of AA-8i-Mg alloy with a thickness of 0.1 mm, the Mg and Si of the skin materials 2 and 2 are changed, and this is JIS 30
The flow coefficient was measured from the ratio of the volume of the fillet 5 to the volume of the entire solder (skin material) when T-shaped joined to the substrate 4 made of 03, and the results are shown in the graph of Figure 2. show.

The bonding conditions in this case are vacuum degree 3 x 10-' tor.
r, heating holding time was 600°C x 3 minutes.

As is clear from the graph in FIG. 2, it can be seen that the greater the amount of Si and Mg added, the better the wettability.

Using this brazing sheet 3, an oil cooler 6 as shown in FIG. 3 or a radiator T as shown in FIG.
It has been found that the area of the fillet formed differs depending on the internal joining position, and there is a problem that a predetermined joining strength cannot be obtained, especially in the case of a hollow structure to which internal pressure is applied.

For example, it is recognized that the joint strength is different between a joint A on the outside of a hollow structure having a closed structure and a joint B on the inside of the hollow structure.

In order to investigate this problem, a cup 10 drawn from a brazing sheet has a diameter D = 3 as shown in FIG.
VN ventilation holes 11 were provided and the fillet areas were measured due to compositional changes of various skin materials when these were bonded to the substrate 4.

As a result, the fillet area of the outer joint A of the cup 10 is as shown in the graph of FIG.
As for the fillet area of the inner joint B, a curve as shown in the graph of FIG. 7 was obtained.

As is clear from these graphs, if the material of the skin material clad on both sides of the core material is the same, the fillet area will be different between the outer joint A and the inner joint B of the enclosed structure. Is recognized.

Furthermore, in order to confirm this effect, when the diameter of the ventilation hole 11 provided in the center of the cup 10 shown in FIG. When we investigated the change in fillet area in
As shown in the graph of FIG. 8, when the diameter becomes 7Wla or less, a sudden change appears, and it was confirmed that the fillet area becomes large in a somewhat confined atmosphere.

In view of the above, the present invention has been developed as a result of conducting various studies.When manufacturing hollow structures such as oil coolers and radiators with enclosed spaces by vacuum brazing, the outer joint portion and the inner joint portion are We have developed a method for manufacturing hollow structures using brazing sheets clad with a suitable skin material.

That is, the present invention is a method of manufacturing a hollow structure by brazing using a plating sheet, in which the plating sheet constituting the hollow structure has an aluminum alloy as a core material, and the inner surface of the hollow structure is coated with Si8. ~1
A skin material is formed by cladding an aluminum alloy consisting of 0.2 to 1.2% by weight of Mg and the balance Al, and a Si8 to 12 weight part and a M weight of -2 are provided on the outer surface of the hollow structure. This is a method for manufacturing a hollow structure in which vacuum brazing is performed using a plating sheet formed by cladding an aluminum alloy containing an amount of Mg equal to or greater than that contained in the skin material in terms of weight φ and the remainder being Al.

The present invention will be explained in more detail below.

The core material of the brazing sheet of the present invention is Al-Mn.
AA-Mg-8i alloy, or AA-Mg-8i alloy.

The skin material cladding on one surface of this core material is Si.
8 to 10% (hereinafter 饅 indicates weight %), Mg0.2 to 1
．． It is an aluminum alloy consisting of 2% Al and the balance Al.

This aluminum alloy is formed as a skin material for the joint inside the hollow structure.

In addition, the skin material cladding on the other surface of the core material is Si.
The aluminum alloy contains 8 to 12% Mg, 1 to 2% Mg, and contains more than the amount of Mg contained in the skin material, and the balance is AA'.

This aluminum alloy is formed as a skin material for the outer joint of the hollow structure.

The vacuum brazing sheet formed as described above contains Mg
The one with the smaller content is used so as to be located inside the hollow structure.

This is because Mg in the skin material vaporizes during vacuum brazing.
By reducing and removing Al2O3 formed on the surface of aluminum, this is bonded with the same effect as Fusix, but if the amount of Mg vapor is too large, the wax will flow too much and fillets are formed. area becomes smaller.

Therefore, as mentioned above, by making the amount of Mg in the skin material located inside the hollow structure smaller than the amount of Mg in the skin material located outside, the Mg vapor contained in the atmosphere of the joint can be reduced. The concentration is made almost equal to average the bonding strength.

The reason why the alloy composition of the skin material cladding on both sides (inside and outside of the hollow structure) of the core material of the plating sheet constituting the hollow structure in the present invention is limited as described above is as follows.

Si in the skin material used to be located inside the hollow structure
If the amount is less than 8%, the fluidity of the skin material (brazing material) will be low, and if it exceeds 10%, the fluidity will increase and there is a problem that it will flow outside the joint.

Furthermore, if the Mg content is less than 0.2%, fluidity is low and sufficient bonding strength cannot be obtained; if it exceeds 1.2%, fluidity becomes too large, resulting in poor bondability and moldability. Because it does.

Furthermore, if the amount of Si in the skin material formed on the outside of the hollow structure is less than 8%, the fluidity will decrease;
If it exceeds 2, the moldability decreases due to primary crystal Si.

Furthermore, if the Mg content is less than 1%, the fluidity will decrease, and if it exceeds 2%, cracks will easily occur during molding.

Furthermore, if the Mg amount is less than the Mg amount in the skin material clad on the other surface of the core material, the amount of Mg vapor in the atmosphere formed on the outside of the hollow structure will be smaller than that on the inside, resulting in sufficient bonding. This is because strength cannot be obtained.

Next, examples of the present invention will be described.

JI83003 was used as the core material of the plating sheet constituting the hollow structure, and both sides were coated with the materials shown in Table 1 (Al~
Using a vacuum brazing sheet clad with skin material having the composition shown in A6), as shown in Figure 9, it is 100 yut long, 70 yut wide, 30 yut high, and has a diameter of 5 yut on the top surface, joined at the center. Box-shaped test structure 13 provided with ventilation pipe 12
, conduct a pressure resistance test, and compare the results with the first one.
Shown in table ※※.

In addition, the bonding conditions in this case are: vacuum level 3 x 10-5 torr
r, heating and holding time was 600×3 minutes.

In addition, in order to compare with the present invention, a similar test structure 12 was created using the vacuum plating sheets shown in A1 to A6 above by turning them inside out and using sheets shown in A7 to A12, and a pressure resistance test was similarly conducted. Ta.

The results are also shown in Table 1.

As is clear from the above results, according to the method of the present invention, the composition of the skin material clad on the outside and inside of the core material of the plating sheet constituting the hollow structure is varied, and the hollow structure is vacuum brazed. In the case of manufacturing, the outside is clad with a skin material with excellent fluidity, and the inside is clad with a skin material with low Mg and Si content so that the fluidity can be adjusted by the influence of the atmosphere. By using this product, it is possible to uniformly and firmly join the joints inside and outside of a hollow structure, and it has an extremely excellent effect in manufacturing hollow structures such as oil coolers and radiators that have confined spaces. It is.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a test piece used to measure the fluidity coefficient of a brazing sheet, Figure 2 is a graph showing the fluidity coefficient when Si and Mg in the skin material is varied, and Figure 3 is a diagram of an oil cooler. FIG. 4 is a cross-sectional view of the radiator; FIG. 5 is a partially cut-away perspective view of a test cup;
FIG. 6 is a graph showing the outside fillet area of the cup shown in FIG. 5, FIG. 7 is a graph showing the inside fillet area,
Figure 8 is a graph showing changes in the inner fillet area when changing the diameter of the vent hole drilled in the cup.
The figure is a perspective view showing a test structure for measuring compressive strength. DESCRIPTION OF SYMBOLS 1... Core material, 2... Skin material, 3... Blazing sheet, 4... Base L 5-- Fillet, 6... Oil cooler, I... Radiator, 8... Fin material, 9... Tubular body, 10... Cup, 11... Vent hole, 12... Vent pipe, 13... Test structure.

Claims (1)

[Claims] 1. In a method of manufacturing a hollow structure by brazing using a praising sheet, the plating sheet constituting the hollow structure has an aluminum alloy as a core material,
On the inner surface of the hollow structure, a Si 8 to 10 weight layer is applied.
The skin material is made by cladding an aluminum alloy consisting of 0.2 to 1.2 weight of Mg and the balance of Al, and the outer surface of the hollow structure is coated with Si 8 to 12 weight and M weight - 2 weight φ.
Contains at least the amount of Mg contained in the skin material, and the balance is A
1. A method for manufacturing a hollow structure by vacuum brazing, characterized in that vacuum brazing is performed using a plating sheet whose skin material is formed by cladding an aluminum alloy made of aluminum alloy.