JPH02147163A - Production of heat exchanger made of aluminum - Google Patents

Abstract

PURPOSE:To improve corrosion resistance and strength by using a specific Al alloy as the core material of a header plate material, cladding a specific Al-Si alloy to one surface thereof and a specific Al-Zn or Al-Zn-Mg alloy to the other surface to form the header plate material and subjecting the plate material to a specific heat treatment. CONSTITUTION:The header plate material is formed by using the alloy contg., by weight %, 0.4 to 1.2 Si, 0.15 to 1.0 Fe, 0.4 to 1.0 Cu, 0.5 to 1.3 Mn, and 0.05 to 0.8 Mg and the balance Al alloy as its core material and cladding the Al-Si alloy brazing filler contg. >=9wt.% Si on one surface thereof to 3 to 7% thickness. The sheet clad with the lining material of the Al-Zn alloy system contg. 0.5 to 3 Zn by weight % or the Al-Zn-Mg system contg. 0.5 to 3 Zn and 0.3 to 1.1 Mg on the other surface to 3 to 10% thickness is used and the surface thereof is brazed to the inside surface of a tank; thereafter, the tank is cooled at >=50 deg.C/min rate down to 500 to 200 deg.C, by which the heat exchanger made of the aluminum is produced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing lightweight aluminum heat exchangers, such as radiators and heater cores, using a header plate material with high strength and excellent corrosion resistance. .

[Conventional technology] AI used for cooling water heat dissipation in water-cooled engines of automobiles, etc.
For example, as shown in Fig. 1, a radiator made of liquid is equipped with header plates (4
) is provided to connect the upper tank (5) and lower tank (6).

At this time, the header plate (4) and each tank (5) (
For example, if the tank (5) (6) is made of synthetic resin, the joint with the tank (5) (6) is between the lower surface of the tank (5) and the upper surface of the peripheral edge of the header plate (4), as shown in Figure 2. Holding the backing (7), the outer periphery of the header plate (4) is caulked to the flan part (8) formed on the outer periphery of the upper end of the tank (5), and the tank (5) is attached to the header plate (4). is watertightly connected to the

In addition, both ends of the large number of liquid passage pipes (1) constituting the core part (3) fit into the perforated holes (9) formed in the header plate (4) without any gaps, and the periphery of each perforated hole (9) The inner circumferential surface of the vertical wall formed in the section and the outer circumferential surface of the liquid passage pipe (1) are joined together by brazing, and the fitting section is kept watertight.

In this way, the header plate (4) is connected to the upper and lower tanks (5).
) Close the - side of (6) and tank (5) (6)
and the core part (3), and its material is usually an aluminum alloy core material (1) as shown in Figure 3.
This header plate (4) and liquid passage tube (1) are attached to one side of the
) A brazing sheet clad with a layer of brazing material (11) is used for brazing the ends of the brazing material (11), and its thickness is approximately 1.4 to 1.6. In addition, the plate thickness of the liquid passage pipe (1) and the fin (2) is each 0.3
~0.4 mm and around 0.1 mm.

And the core material (10) of this brazing sheet is JI3
3003 alloy (AA'-Cu (1,0S~0.20
71%-Mn1. Q ~ 1.5 w1% Al of alloy alloy
However, if the core material (10) made of an Al alloy with a normal composition is exposed to the inner surface of the radiator tank and comes into direct contact with cooling water, pinholes may form in the core material (101) due to corrosion. Pitting corrosion is likely to occur.

According to experiments, chlorine ions (CA-
) to Iooppm, carbonate ion (HCO2) to 200p
When a test was continued for 6 months in which test water at 88°C containing 300 ppm of sulfate ions (SO42-) and ippm of copper ions (Cu2+) was circulated at a rate of 60 J2 per minute, pitting corrosion occurred through the header plate (4). This caused a water leak.

To prevent this, conventionally, as shown in Fig. 4, an Al-Zn-Mg alloy (Al-MgOJ ~1
．． Corrosion of the core material (10) is prevented by forming a coating layer (12) of lw1%-Zn0.8-1.3wt%-alloy) and subjecting this coating layer to sacrificial corrosion. There is.

To manufacture such a radiator using non-corrosive flux, a large number of liquid passage tubes and fins are stacked, and both ends of the liquid passage tubes are inserted into the holes in the header plate. After assembling the parts with a jig, degrease and apply 5% flux, and then apply 600 to 600
These are joined by brazing heat to 20°C. At this time, the dew point of the atmosphere is below -35℃, and the oxygen concentration is 1000p.
It is desirable that it is 9ffi or less. Furthermore, after brazing is completed, a cooling process is performed, and a resin tank is attached to each header plate as described above.

The heater core also uses the same material as the radiator. In this case, a brazing sheet similar to the header material is used instead of the resin tank, and may be manufactured by integral brazing.

[Problem to be solved by the invention]

In recent years, many attempts have been made to reduce the weight of AI-made radiators, and thinner header plate materials are also being considered.
If the existing materials were simply made thinner, there would be problems with structural strength, fatigue life, corrosion resistance, etc.

In other words, simply making the wall thinner will deform the outer periphery of the header plate and damage the watertight structure of the backing part, or cause fatigue failure of the periphery of the reheader plate due to changes in internal pressure. was extremely difficult. In addition, regarding the corrosion resistance of the outside of the header plate, that is, the atmospheric side, the current layered structure of the core material and brazing material of 33003 has a problem in its life when the plate thickness is reduced.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention provides a method for manufacturing lightweight aluminum heat exchangers, such as radiators and heater cores, made of a header plate material with excellent strength and corrosion resistance.

That is, one of the present inventions is to stack liquid passage pipes and fins, fit both ends of the liquid passage pipes into perforated holes in a header plate, use a chloride-based flux, and deposit them in air, dry air, or In the manufacture of aluminum heat exchangers, each header plate is brazed in an inert gas atmosphere using non-corrosive fluoride flux to form a tank that communicates with the liquid pipe. , S
i 0.4-1.2 v1%, Fe0. I5~1.0
w1%, Cu0.4-1. Ovt%, Mn0.5
~13 v1% and M g 0.05-0.8 w+
% and the balance is AI as a core material, one side of the core material is clad with 3-7% Al-Si alloy brazing filler metal containing 9wt% or more of 81, and the other side is clad with 0.5-3wt%. %
A++-Zll system containing Zn or 0.5~
3 wt% Zn and [1,3-1. I w1% M
Using a brazing sheet clad with an Al-Zn-Mg alloy lining material containing g to a thickness of 3 to 10%,
-The surface clad with Zn-based or Al1-Zn-Mg-based alloy lining material is used as the inner surface of the tank, and after brazing and heating,
It is characterized by cooling from 0°C to 200°C at a rate of 50°C/+nin or more.

Another aspect of the present invention is to stack liquid passage pipes and fins, fit both ends of the liquid passage pipes into the perforated holes of the header plate, and use chloride-based flux in the atmosphere, dry air, or In the manufacture of aluminum heat exchangers, each header plate is brazed in an inert gas atmosphere using non-corrosive fluoride flux to form a tank that communicates with the liquid pipe. , S
i0.4~1.2wt%, Fe0.15~1.0w
1%, Cu0.4-1.0wt%, Mn 0.5
~1.3 wt% and M g (1, (15 ~ Q, 11
Contains w1% and further contains Cr 0. Of~0.3 vt%
+' Z r [1,0f~0.3 v1%.

The core material is an alloy containing one or more types of Ti01O1~Q, 3wt%, and the balance is AI, and 9wt% is formed on one side of the alloy.
Aji-8i alloy brazing filler metal containing 3 to 7% Si
% thickness and 0.5~3vt% Zn on the other side.
AI-Zn containing or 0.5 to 3 wt% Zn
and Aji-Z containing 0.3-1.1 w1% Mg
Use a brazing sheet clad with n-Mg alloy lining material at a thickness of 3 to lθ%, and use the surface clad with kl-Zn or Al-Zn-Mg alloy lining material as the inner surface of the tank. After waxing heat, 500℃ to 200℃
It is characterized by cooling at a rate of 50° C./min or more.

[For production]

Next, the reason why the components of the core material constituting the brazing sheet used in such a header plate material are limited as described above will be described.

The addition of Si increases the finer Mg25j of cooling after brazing.
This is because particles can be precipitated, thereby improving material strength. And the Si content is 0.4 to 1
．． The reason for limiting it to 0wt% (hereinafter m1% is simply referred to as %) is that if it is less than 0.4%, the above effect will not be achieved, and if it exceeds 1.2%, the melting point of the core material will decrease, and grain boundaries will form at high temperatures during brazing. This is because a burning phenomenon occurs in which parts melt, resulting in a decrease in strength.

The addition of Fe has the effect of improving strength, and the reason for limiting its content to 0.15 to 1.0% is that less than 0.15% has no effect, and more than 1.0% significantly impairs corrosion resistance. This is because it reduces the

Addition of Cu has the effect of improving strength, utilizing electrode potential, and improving corrosion resistance, and its content can be reduced to 0.
．． The reason why it is limited to 4 to 1.0% is because these effects are insufficient if it is less than 1.4%, and self-corrosion resistance decreases if it exceeds 1.0%.

The addition of Mn has the effect of improving strength and corrosion resistance, and the reason why the content is limited to 0.5 to 1.3% is because if it is less than 0.5%, these effects will not be achieved.
This is because plastic workability deteriorates when the content exceeds %.

The addition of Mg has the effect of forming Mg2Si together with Si and improving the strength, and the content is increased from 0.05 to 0.8%.
The reason for this is that if it is less than 0.05%, it will not have these effects.
This is because if it exceeds 0.8%, the melting point of the core material decreases, a burning phenomenon occurs during brazing, leading to a decrease in strength, and furthermore, it reacts with fluoride-based flux, reducing brazability.

This is because adding one or more of Cr, Zr, and Ti can further improve the strength, and the reason why the content of each is limited to 0.01 to 0.3% is less than 0.01%. This is because, if it exceeds 0.3%, it will form a huge compound and reduce processability.

The reason why the Si content of the Al-Si alloy brazing filler metal cladding on one side of the core material is limited to 9% or more is that the brazing temperature can be lowered to prevent deformation of the header plate material at high temperatures. It is. The upper limit of the amount of Si is not particularly limited, but it is preferably up to about 12%, taking into account the diffusion of the brazing filler metal into the core material and the reduction in corrosion resistance due to the formation of Si plate-like initial products.

Furthermore, the cladding ratio of the brazing material is 0.8 ~ the thickness of the header plate is thinner than the conventional plate thickness! , 3~ for 3mm
A range of 7% is good; if it is less than 3%, brazing properties will decrease if the plate thickness becomes thinner, and if it exceeds 7%, the thickness ratio of the core material and lining material will decrease, improving strength and corrosion resistance. This is because it becomes impossible to do so.

The reason for limiting the alloy components of the lining material clad on the other side of the core material is as follows.

The addition of Zn makes the potential less base and can protect the core material from corrosion.The reason why the content is limited to 0.5 to 3% is that less than 0.5% is ineffective, and 3% This is because, if it exceeds this, not only will this effect become saturated, but also self-corrosion will increase, making it impossible to maintain the effect as a sacrificial layer.

The addition of Mg has the same effect of preventing corrosion of the core material as the addition of Zn, and limiting the content to 0.3 to 1.1% is 0.
．． This is because if it is less than 3%, these effects are not achieved, and if it exceeds 1.1%, it becomes difficult to braze the header plate material and the liquid passage pipe.

Furthermore, in the case of header plates with a plate thickness of 0.8 to 1.3 mm, the cladding ratio of the lining material is preferably in the range of 3 to 10%.
If it is less than 3%, the internal corrosion resistance will decrease, and if it exceeds 10%, the thickness ratio of the core material and brazing material will decrease, making it impossible to improve the strength and corrosion resistance.

In this way, in the production of unprecedentedly lightweight heat exchangers such as radiators and heater cores, the composition and thickness of not only the core material but also the brazing material and lining material must be adjusted in order to make the header plate material thinner. requires extremely strict adjustment.

Next, the header plate material using the above brazing sheet is assembled with the liquid passage pipe and fins, and heated for brazing.
The reason for specifying the subsequent cooling as described above is that it is possible to sufficiently increase the strength of the header plate. And brazing has a temperature range of 500°C that defines the subsequent cooling rate.
The temperature was limited to ~200°C because it is necessary to suppress the precipitation of gigantic Mg2Si in this temperature range in order for Mg2Si to be finely precipitated in the core material of this brazing sheet and to have an effective effect on improving strength. be. Furthermore, Mg2S has a cooling rate of 50°C/min or more in this temperature range.
This is because it enables fine precipitation of i, and if the cooling rate is less than this, giant Mg2Si will precipitate and the strength cannot be improved.

〔Example〕

Next, examples of the present invention will be described.

Example (1) An Al alloy containing the alloy components shown in Table 1 was cast by a conventional method, and after homogenization treatment, it was made to a predetermined thickness. Also the second
Ali-Si alloys containing Si in the weights shown in the table and A/Si alloys containing Zn and Mg in the weights also shown in Table 2.
-Zn and Ali-Zn-Mg alloys were cast, and each was hot-rolled to a predetermined thickness. Next, an Al alloy plate having the composition shown in Table 1 is used as a core material, the above Al-Si alloy plate is placed on one side of the core material as a brazing material, and the above AA'-Zn, Aji is placed on the other side as a lining material. -Zn-Mg alloy plates are stacked together in three layers and hot-rolled and cold-rolled to give a plate thickness of 1. The thickness was reduced to 0 mm and final annealing was performed at 360° C. for 2 hours.

Then, brazing sheets were made by cladding a brazing material and a lining material on one side of each core material with the cladding ratio shown in Table 2, and were used as header plate materials in the following tests.

■Strength test: These brazing sheets were heated in N gas without applying flux at 600°C x 10m1n, then cooled to 500°C to solidify the brazing material, and then cooled to 200°C. The speed is 3θ as shown in Table 3.
It was varied in the range of ~40 G'C/win and cooled, then allowed to stand at room temperature, and the tensile strength was measured after 4 days.

These measurement results are also listed in Table 3.

■Brazeability test...Si 4045 alloy (AI-S i 9. O-
Il. A 0.25 mm thick brazing sheet made by cladding 0% gold alloy brazing filler metal with 5% thickness on one side of the Moon 33003 alloy core material was processed into an ERW tube with a thickness of 2 mm and a width of 16 m.
A flat-shaped liquid passage tube having a diameter of m was made and fitted into 10 through holes drilled in the header plate material to produce a connecting mini-core consisting of the header plate material and the liquid passage tube. Next, after degreasing this mini-core, apply a 5% concentration fluoride flux, dry it at 200℃, and then heat it in a heated gas at 600℃ x 3m1n or 61O'''C x 3m1 as shown in Table 3.
n(7) brazing heat was applied to 10 identical mini-cores, and the state of liquid leakage at the joints between the liquid passage pipe and the through hole was investigated at a total of 100 locations.

As a result, the ratio of the number of leak-free joints was determined as the joint rate, and these are also listed in Table 3.

Note that cooling to 500° C. or lower after the addition of brazing heat was carried out under the same cooling conditions as in the above strength test.

■ External corrosion resistance test: Using the brazing sheet shown in Table 2, after heating and cooling under the same heating and cooling conditions as in the strength test, the surface clad with the brazing filler metal is exposed, and the inner lining material is clad with the brazing sheet. The exposed surface and side surfaces were sealed and salt water sprayed for three months, and the depth of pitting on the exposed surface was measured to evaluate the corrosion resistance of the outer surface of the header plate.

The measurement results are also listed in Table 3.

■Inner surface corrosion resistance test: Using the brazing sheet shown in Table 2, after heating and cooling under the same heating and cooling conditions as in the strength test, the surface clad with the lining material is exposed and the brazing sheet is clad with the brazing material. CI-195ppm, F
e3”30ppm, SSO42-60pp
We conducted an immersion test for 6 months, repeating a cycle of 8Ht immersion in 88℃ high-temperature water containing 1 ppm of Cu 2 +1 ppm, and then leaving it at room temperature for 1611+ days, and measured the depth of pitting on the exposed surface to evaluate the corrosion resistance of the inner surface of the header plate. evaluated.

The measurement results are also listed in Table 3.

*However, V is a conventional material and indicates It33003 alloy.

As shown in Table 3, the header plate materials produced by the methods Nα1 to Nα1 and 6 of the present invention all have a tensile strength of 18 kg1/NA.
The above is the conventional core material (JIS
Approximately 1.5 of the header plate material using 3003 alloy)
It turns out that it has twice the strength.

Furthermore, in the methods Nα1 to Nα16 of the present invention, the bonding rate was 9.
It is high at 5% or more, indicating excellent brazing properties. Furthermore, the corrosion resistance of the outer and inner surfaces is also good, and in particular, the corrosion resistance of the outer surface is due to the sacrificial effect caused by the potential difference between the brazing material and the core material, so the pitting corrosion resistance is significantly improved compared to the comparative method N11311. .

Therefore, although the header plate material has not conventionally been protected against corrosion using a sacrificial anode material such as a fin material, it is believed that the corrosion-resistant life of the header plate material can be sufficiently extended by the method of the present invention.

On the other hand, it can be seen that comparative methods No. 17 to No. 40 are inferior to the method of the present invention in any of the test results.

Example (2) Header plate materials Nα1 and Nα16 with a plate thickness of 1.0 mm according to the present invention shown in Table 2, and further 33003
JIS 4343 alloy (Si6□8~
8.2%-AI) Brazing filler metal is clad with a cladding rate of 8%, and the other side is clad with a Zn1%-M g 0.5%-Al alloy lining material with a cladding rate of 9%. A header plate material made of a 6 mm conventional material was formed into a header plate provided with perforated holes for attaching liquid passage pipes as shown in FIGS. 1 and 2. The header plate has a thickness of 0. Al-Mn-Zn with llmm and width 16mm
Pitch 1.5n+m, fin height 9,
Fins corrugated to 0mm and 3300 yen
It34343 with 8% cladding rate on one side of 3 alloy core material
A brazing sheet is clad with alloy brazing material and the other side is clad with JIS 7072 alloy lining material at the same cladding rate (8%), and is electrically welded to a thickness of 2.0 mm x width of 14.0 mm.
A radiator core was manufactured by assembling a flat liquid passage pipe of 5 mm x 451 mm in length and brazing in a normal gas atmosphere using fluoride flags.

Cooling after additional heat is 1θ from 500 to 200℃.
Cooling was carried out at a cooling rate of Q'C/min, and after cooling, a resin tank was attached to the peripheral edge of the header plate via a backing as shown in FIG.

Next, the weight, structural strength, and fatigue life of these three types of radiators were compared. As a result, the weight of the radiator core was reduced by 25% compared to the conventional one, and the weight of the radiator assembly including the resin tank was reduced by approximately 10%.The structural strength and fatigue life are the same as those of the tube. It was confirmed that both of these products were comparable to the current products.

〔Effect of the invention〕

As described above, according to the present invention, the strength and corrosion resistance of the header plate can be increased several times and its weight can be reduced, so the weight can be reduced without reducing the structural strength and life of heat exchangers such as radiators and heater cores. This has significant industrial effects, such as making it possible to reduce weight and further reduce material costs.

[Brief explanation of the drawing]

Figure 1 is a front view of the radiator, Figure 2 is a sectional view taken along line AA' in Figure 1, Figure 3 is a sectional view of the header plate material clad with only brazing metal, and Figure 4 is a sectional view of the brazing metal and inner parts. It is a sectional view showing a header plate material in which a tension layer was formed. 1......Liquid pipe 2...Fin 3...Core part 4...Header plate 5.6...・Tank 7...Backing 8...Flange part 9...Drilling hole 10...Core material 11... ...Brazing material 12 ... Lining material Figure 1 Figure 2 Figure 3 Figure 4

Claims (2)

[Claims] (1) Stack the liquid passage pipes and fins, fit both ends of the liquid passage pipes into the holes in the header plate, and use chloride-based flux in the atmosphere, dry air, or fluoride-based non-corrosive flux. In manufacturing an aluminum heat exchanger in which a tank communicating with a liquid pipe is formed on each header plate by brazing in an inert gas atmosphere using Si0.4 to Si0.1. 2
wt%. Fe0.15-1.0wt%. Cu0.4-1
．． 0 wt%, Mn0.5-1.3 wt% and Mg0.
Al-S containing Si of 05 to 0.8 wt% with the remainder being Al as a core material and containing 9 wt% or more of Si on one side.
The i-based alloy brazing filler metal is clad with a thickness of 3 to 7%, and the other side is clad with an Al-Zn system containing 0.5 to 3 wt% of Zn or 0.
．． 5-3 wt% Zn and 0.3-1.1 wt% M
Using a brazing sheet clad with an Al-Zn-Mg alloy lining material containing g to a thickness of 3 to 10%,
- After the surface clad with Zn-based or Al-Zn-Mg-based alloy lining material is brazed and heated to the inner surface of the tank, it is characterized by cooling from 500°C to 200°C at a rate of 50°C/min or more. Method of manufacturing an aluminum heat exchanger. (2) Stack the liquid passage pipes and fins, fit both ends of the liquid passage pipes into the holes in the header plate, and use chloride-based flux to expose them to air, dry air, or fluoride-based non-corrosive flux. In the manufacture of aluminum heat exchangers in which a tank is formed in each header plate by brazing in an inert gas atmosphere using flux, Si0.4 to 1 is used as the header plate material. ．．
2wt%, Fe0.15~1.0wt%, Cu0.4~
1.0wt, Mn0.5-1.3wt% and Mg0.
0.05 to 0.8 wt%, and further contains Cr of 0.01 to 0.0.
3wt%. Zr0.01-0.3wt%, Ti0.01
The core material is an alloy containing one or more types of ~0.3 wt% and the balance is Al, and on one side of the alloy is 9 wt% or more of Si.
clad with an Al-Si alloy brazing filler metal containing 0.5 to 3 wt% of Zn on the other side with a thickness of 3 to 7%.
system or 0.5 to 3 wt% Zn and 0.3 to 1.
Using a brazing sheet clad with an Al-Zn-Mg alloy lining material containing 1 wt% Mg at a thickness of 3 to 10%, cladding with an Al-Zn or Al-Zn-Mg alloy lining material. A method for manufacturing an aluminum heat exchanger, which comprises using the heated surface as the inner surface of a tank, and cooling the aluminum heat exchanger from 500°C to 200°C at a rate of 50°C/min or more after applying brazing heat.