JPS6238796A - Sheet for vacuum brazing - Google Patents

Abstract

PURPOSE:To obtain a hollow structural body having good appearance and high pressure-resistance strength by specifying the alloy compsn. of a skin material to be formed on the outside and skin material to be formed on the inside so that the concn. of Si of the skin material to be formed on the outside is not made smaller than the concn. of Si of the skin material to be formed on the inside. CONSTITUTION:An Al solder alloy contg. by weight %, 5-14% Si, 0.2-3% Mg and 0.01-1% in total of 1 or >=2 kinds among Cu, Y, Ge, In, Bi, Sb, Ba, St, Pb, Sn, Li and Be and consisting of the balance Al is used as the skin material to be formed on the outside of a sheet for vacuum brazing. The Al brazing alloy contg. 5-14% Si, 0.2-3% Mg, and consisting of the balance Al is used as the skin material to be formed on the inside. The concn. of Si in the skin material to be formed on the outside is so adjusted as not to be make lower than the content of Si of the skin material to be formed on the inside.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application R1) The present invention relates to a vacuum plating sheet suitable for manufacturing a hollow structure such as a dron cup type oil cooler, evaporator or radiator.

(Prior Art) In recent years, a vacuum brazing method that does not require flux has been developed for brazing aluminum structures, and it has become popular since there is no concern about pollution. Vacuum brazing is a method of brazing in a vacuum using a plating sheet made of aluminum alloy as a core material and clad with aluminum brazing alloy on one or both sides as a skin material. It is used for attachment. Various aluminum alloys for core materials and aluminum solder alloys for skin materials have been developed for vacuum plating sheets, and are currently standardized by JIS Z 3263.

Utilizing this vacuum brazing, aluminum heat exchangers with hollow structures such as doron cup type oil coolers, enovolators, or radiators are manufactured.For example, a conventional doron cup type oil cooler is shown in Figure 1. As shown, a tubular body (1) formed from a plating sheet is layered with v1, and a full gate fin (2) is arranged between the tubular bodies (1), and manufactured by a vacuum brazing method. In addition, as shown in Figure 2, the radiator is constructed by attaching a tank (4) to the end of a flat tube (3) formed with a praising sheet, and placing corrugated fins (2) between the flat tubes (3). However, as shown in Figures 1 and 2, when a structure with a hollow part is manufactured by the vacuum brazing method, the inner joints of the hollow part are not sufficiently formed. In some cases, a predetermined bonding strength cannot be obtained.

This is because there is a discrepancy in the appropriate conditions for brazing between the joints inside the hollow structure and those outside the hollow structure, and the range of conditions that can be set to achieve good brazing at the same time on the inside and outside is narrow, so both must be set at the same time under the optimal conditions. This is thought to be because it is difficult to braze.

Conventionally, attempts have been made to overcome this problem by changing the composition of the brazing alloy that forms the inner and outer skin materials. For example, by regulating the Si content in the skin material of an aluminum alloy plate, and also The amount of Mg is 0.2 to 1.
2% by weight (hereinafter "weight%" will simply be abbreviated as %) to prevent an excessive amount of Mg vapor trapped inside the hollow body (Japanese Patent Application Laid-open No. 58-54909), on one side of the inner skin material. Aluminum vacuum plating sheet using a combination of fixed amounts of St and Mg (Japanese Unexamined Patent Publication No. 85364/1983)
is proposed.

However, in recent years, the requirements for quality such as pressure resistance and external finish of heat exchangers have become extremely high, and these conventional vacuum brazing materials have not necessarily met these requirements.

(Means for Solving the Problems) The present inventors have conducted extensive research to overcome the drawbacks of conventional vacuum brazing, and have obtained the following knowledge. That is, in a hollow structure assembled by brazing, such as a tank of a doron cup, the joint part is divided into two as shown in FIG. 3, which is an explanatory diagram of the test method described later, and FIG. They can be roughly divided into two types: one is a joint part (tweeter) A) formed by the inner skin material of the hollow structure, and the other is a joint part (fillet B) formed by the outer skin material.

First of all, solder breakage is likely to occur at B of the outer joints,
This not only causes problems in appearance but also leads to a decrease in pressure resistance. Furthermore, in the inner joint portion (for example, A), not only the solder breaks but also the size of the fillet is insufficient, which causes problems in terms of pressure resistance.

A formed by the inner skin material as shown in FIG.
As shown in Fig. 4, the fillet on the inside (A) becomes smaller as the fillet moves from A to C as shown in Figure 4. , sufficient Mg to remove the oxide film on the surface.
quantity is required, and sufficient fluidity is required to avoid breaking the solder.

At joint C, a sufficient amount of Mg is required to remove the oxide film on the surface, but there is no need to worry about solder breakage since the solder is supplied from joint A.

Then, a predetermined amount of S is applied to the inside and outside of the plating sheet.
i and Mg so that the 5iia degree in the outer skin material is not lower than the Si concentration in the inner skin material,
In addition, by adding certain additive elements to each of the inner and outer skin materials, the fluidity of the brazing material (for example, from A to C) is appropriately suppressed, and the brazability is stabilized both inside and outside. It was discovered that it is possible to manufacture a heat exchanger that does not cause breakage, increases the size of formed fillets (for example, A and B), and improves pressure resistance, and satisfies the high required standards.Based on this knowledge, the present invention was completed. I ended up doing it.

That is, in the present invention, a skin material made of an aluminum brazing alloy is clad on both sides of an aluminum alloy constituting an aluminum hollow structure by vacuum brazing, and the outer skin material contains 5 to 14% Si and 0.2 to 20% Mg. 3%
and Cu, Y, Ge, In, Bi, Sb, Ba, St, P
An aluminum brazing alloy containing one or more of B, Sn, Li, B, and e in a total of 0.01 to 1% and the balance being Al is used as the inner skin material to Si5 to 14.
% and 0.2 to 3% Mg, with the remainder being Al, and the Si concentration of the outer skin material is not lower than that of the inner skin material. A sheet for vacuum brazing (hereinafter referred to as the first invention), which is made by cladding a skin material made of an aluminum brazing alloy on both sides of an aluminum alloy constituting an aluminum hollow structure by vacuum brazing,
Si5~14% and Mg 0.2~ as the outer skin material
3% and the balance Al, and - as the inner skin material, 5 to 14% Si, Mg0
．． The outer skin material is made of an aluminum brazing alloy consisting of 2% to 3% and a total of 0.01 to 2% or more of any one or more of Na, Ca, Mn, Fe, Ti, and Ni, and the balance Al. A double-sided clad vacuum brazing sheet (hereinafter referred to as the second invention) characterized in that the Si concentration is not lower than the Si concentration of the inner skin material, and an aluminum hollow structure is constructed by vacuum brazing. It is made by cladding a skin material made of aluminum brazing alloy on both sides of an aluminum alloy, and Si is used as the outer skin material.
5-14%, Mg0.2-3%, Cu, Y, Ge, In
, Bi, Sb, Ba, St, Pb, Sn, Li, Be(
7) A total of 0.01 to 1% of any one or two or more types
Using an aluminum brazing alloy consisting of aluminum and the remainder Al,
The inner skin material contains 5-14% Si, 0.2-3% Mg, and 0.01-2% or more of any one or more of Na, Ca, Mn, Fe, Ti, and Ni, with the remainder being Al. A double-sided clad vacuum brazing sheet (hereinafter referred to as the third invention) characterized in that the Si concentration of the outer skin material is not lower than the Si concentration of the inner skin material using an aluminum brazing alloy consisting of ).

In the first to third inventions of the present invention, the meanings of the numerical limitations are as follows.

If the Si content is less than 5%, the fluidity is too low, and if it exceeds 14%, the forming process becomes difficult. In particular, the Si content is 7 to 1.
A range of 2% is desirable.

If the Mg content is less than 0.2%, the effect of destroying the oxidative film due to the evaporation of Mg cannot be expected, but if it exceeds 3%, the effect of Mg not only becomes saturated, but also the moldability deteriorates and the inside of the vacuum furnace The amount of Mg adhering to the furnace increases, which poses a problem in terms of furnace maintenance. In particular, it is desirable that the Mg content be within the range of 0.5 to 2%.

In the present invention, it is necessary to further adjust the fluidity of the brazing filler metal by adjusting additive elements. Cu, Y to be added in a predetermined amount
, Ge, In, Bf, Sb, Ba, Sr, Pb, Sn,
St and Be increase the fluidity of the wax. This is 0.01%
If it is less than 1%, the desired effect cannot be obtained, and if it exceeds 1%, moldability deteriorates. On the other hand, Na, Ca, Mn, Fe, T
i, Ni reduces the fluidity of the wax. This is o, oi
If it is less than 2%, the desired effect cannot be obtained, and if it exceeds 2%, moldability deteriorates.

Furthermore, in the above case, if the Si concentration of the outer skin material is lower than the Si concentration of the inner skin material, there will be a large discrepancy in the appropriate conditions for brazing between the joint inside the hollow structure and that outside the hollow structure. There is a problem in that the condition setting range for performing good brazing on the inside and outside at the same time is narrowed.

(Example) The present invention will be described below with reference to Examples.

3003 alloy is used as the core material, and both sides are clad with skin materials made of brazing alloy with the composition shown in Table 1, with a thickness of 0.8 m.
m Vacuum plating sheet was created 0 Next, this was press-formed, and four cups (combinations of cups 5 and 5 and 5 and 6) formed by press-forming this plating sheet were stacked to form a hollow for pressure test as shown in Fig. 3. Structure 7 was created by vacuum brazing.

In the figure, 5 is a cup with an exhaust port, and 6 is a cup without an exhaust port. Cup size is 52X52X10mm. 7 is a pressure tester connection pipe.

The conditions for vacuum brazing are that the brazing temperature is 10 to 15 degrees Celsius higher than the melting point of the inner skin material, and at that temperature
Hold for minutes. The degree of vacuum was 7 x 10' torr. Regarding the vacuum brazed pieces, the fillet conditions of the inner and outer joints were examined and a pressure test was conducted. The fillet appearance is shown in Figures 3 and 4, A, for the inside, and A in Figure 4 for the outside.
This was done for the part B in Figures 4 and 4. The result is the first
Also listed in the table.

As is clear from the results in Table 1 (Example sample No. 61~
According to the plating sheet No. 20, the fillet is uniform on both the inside and outside of the assembled hollow structure, and the pressure resistance is improved. The reason why the pressure resistance of the example is improved over the conventional example (■) Samples Nos. 31 to 34 is because of the ability to form fillets by adding third component elements such as Cu, Y, Ge, etc. or Na, Ca, Mn, etc. This shows that the results have improved.

Also, as is clear from the results in Table 1, in the comparative example, sample N
No. 21 could not be molded because of the large amount of St. Sample No. 22 has a small amount of Si, so no fillet is formed. Sample No. 23 has a large amount of Mg, so it cannot be formed. Sample No. 24 has a small amount of Mg, so no fillet is formed.

Sample Nos. 25 to 27 contain too many additive elements other than Mg and St, and cannot be formed. Sample No. 29 has S on the inside and outside.
The difference in i amount is too large, the frets are small and uneven,
Compressive strength also decreases.

(Effects of the Invention) According to the present invention, when manufacturing a hollow structure by vacuum brazing, it is easy to set brazing conditions that simultaneously improve the brazing properties of the inner and outer joints of the hollow part, and Defects are reduced.

When vacuum brazing composition is performed using the plating sheet of the present invention, the fillet at the joint becomes uniform, and a hollow structure with not only a clean appearance but also high pressure resistance strength can be obtained.

[Brief explanation of the drawing]

Figure 1 is a side view of an oil cooler manufactured by vacuum brazing, Figure 2 is a side view of a radiator manufactured by vacuum brazing, and Figure 3 is a partially cutaway example of a hollow structure for vacuum brazing testing. FIG. 4 is a partially enlarged view of the test hollow body shown in FIG. 3. Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) A skin material made of an aluminum brazing alloy is clad on both sides of the aluminum alloy constituting the hollow aluminum structure by vacuum brazing, and the outer skin material contains 5-14% Si and 0.2-3% Mg. Cu, Y, Ge
, In, Bi, Sb, Ba, St, Pb, Sn, Li,
A total of 0.01 to 1 of any one or two or more of Be.
%, the balance is Al, and the inner skin material is made of 5-14% Si and 0.2-3 Mg.
% (hereinafter, % indicates weight %) and the remainder is Al, and the Si concentration of the outer skin material is not lower than the Si concentration of the inner skin material. Double-sided cladding sheet for vacuum brazing. (2) A skin material made of aluminum solder alloy is clad on both sides of the aluminum alloy constituting the hollow aluminum structure by vacuum brazing, and the outer skin material contains 5 to 14% Si and 0.2 to 3% Mg. including the remainder Al
Using an aluminum brazing alloy consisting of 5-14% Si, 0.2-3% Mg, Na, Ca,
An aluminum brazing alloy containing one or more of Mn, Fe, Ti, and Ni in a total of 0.01 to 2% (or more, % indicates weight %) or more and the balance being Al is used to form the outer skin. A double-sided clad vacuum brazing sheet characterized in that the Si concentration of the material is not lower than the Si concentration of the inner skin material. (3) A skin material made of aluminum solder alloy is clad on both sides of the aluminum alloy constituting the hollow aluminum structure by vacuum brazing, and the outer skin material contains 5 to 14% Si and 0.2 to 3% Mg. Cu, Y, Ge
, In, Bi, Sb, Ba, St, Pb, Sn, Li,
A total of 0.01 to 1 of any one or two or more of Be.
%, the balance is Al, and the inner skin material contains 5-14% Si and 0.2-3% Mg.
and one or more of Na, Ca, Mn, Fe, Ti, and Ni in a total of 0.01 to 2% (or more, % indicates weight %) or more, and the balance is Al. A double-sided clad vacuum brazing sheet, characterized in that the Si concentration of the outer skin material is not lower than the Si concentration of the inner skin material.