JPH05279817A - Production of heat exchanger made of aluminum alloy - Google Patents

Abstract

PURPOSE:To produce a heat exchanger made of aluminum alloy capable of improving the heat efficiency and strength of a heat exchanger prepared by a brazing process. CONSTITUTION:At the time of producing a heat exchanger made of aluminum alloy by a brazing process, the heat exchanger made of aluminum alloy is produced by performing, in the course of cooling after the completion of brazing heating, holding at 400-500 deg.C for 10min-30hr and applying cooling through the temp. region between 200 and <400 deg.C at >=30 deg.C/min cooling rate and further applying ageing treatment at 120-220 deg.C for 30min-48hr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum alloy heat exchanger, and more specifically, an aluminum alloy heat exchanger for improving the heat efficiency and strength of a heat exchanger manufactured by a brazing method. A method for manufacturing an exchanger is provided.

[0002]

2. Description of the Related Art A heat exchanger such as a radiator has a plurality of flat tubes (1) as shown in FIG.
A thin fin (2) processed into a corrugated shape is integrally formed between the flat tubes (1), and both ends of the flat tube (1) are opened in a space formed by the header (3) and the tank (4).
The high temperature refrigerant is sent from the space on the side of one tank to the space on the side of the other tank (4) through the flat tube (1).
This is to circulate again the refrigerant whose temperature has become low due to heat exchange at (1) and fin (2). The tube material and header material of such a heat exchanger are, for example, JIS3003.
JIS 7 is used as a lining material having a sacrificial effect on the inside of the core material, that is, on the side that is constantly in contact with the refrigerant, using an alloy as the core material.
072 alloy, and the outside of the core is usually JIS
A brazing sheet in which a brazing material such as 4045 is clad is used. Further, although the fin material is used after being corrugated, JIS 3003 or an alloy containing Zn or the like is used for the purpose of giving a sacrificial effect thereto. These are assembled together by brazing.

A laminated evaporator is shown in FIG. 2, in which fins (5) and passage-constituting sheets (6) and (6 '), which are brazing sheets forming refrigerant passages (7) and (7'), are alternated. The fins are usually about 0.1 mm, and the passage-constituting sheet is a brazing sheet having a plate thickness of about 0.5 mm. In such an evaporator, in order to prevent the corrosion of the refrigerant passage from external corrosion, a fin material of JIS 3003 or an alloy containing Zn or the like is usually used for the purpose of giving a sacrificial effect to the same. An Al-1% Mn alloy is used in the refrigerant passage. Cu,
An alloy to which Zr or the like is added as needed is used as a core material, and a brazing material such as JIS 4004 or JIS 4343 is clad on the surface thereof.

Further, FIG. 3 shows a serpentine type condenser, in which a corrugated fin (9) made of a brazing sheet is formed by bending a tubular material (8) extruded into a tubular shape hot or warm into a meandering shape. Is attached. Here, (10) indicates a connector. JIS3003 alloy is used for the pipe material, and JIS3 is used for the fin.
003 or an alloy containing Zn or the like for the purpose of giving a sacrificial effect to the core material according to JIS 4004 or JIS 434.
A brazing material such as 3 is clad on both sides. All of these are assembled by brazing by heating to a temperature of around 600 ° C. and brazing. The brazing method includes a vacuum brazing method, a flux brazing method, and a brazing method.
Nocolock brazing method using a non-corrosive flux is performed.

By the way, in recent years, heat exchangers have been in the direction of weight reduction and downsizing, and therefore thinning of materials has been desired. However, when the conventional material is thinned, there is a problem that the heat conductivity of the heat exchanger is reduced due to the decrease in the thickness of the material, which lowers the thermal efficiency. For this reason, although Al-Zr alloy materials and the like have been mainly developed as fin materials,
There is a problem of low strength. Also, due to thinning,
The strength is insufficient. Therefore, some high strength alloys have been proposed, but sufficient strength has not been obtained. This is because the components of the high-strength alloy itself are restricted from the viewpoints of brazing property and corrosion resistance, and as a final step of the product, 6
This is because there is brazing that is heated to around 00 ° C., and therefore a mechanism for improving strength such as work hardening cannot be used.

[0006]

In view of such a situation, the present invention has developed a method of manufacturing a heat exchanger made of an aluminum alloy having excellent thermal efficiency and high strength. The aluminum alloy is manufactured by a brazing method. When manufacturing a heat exchanger, 400 to 500 ° C during cooling after the brazing heating is completed.
Hold at the temperature of 10 minutes to 30 hours and then 200
It is characterized in that cooling in a temperature range between 0 ° C and less than 400 ° C is performed at a cooling rate of 30 ° C / min or more, and further, aging treatment is performed at a temperature of 120 to 220 ° C for 30 minutes to 48 hours. It is a manufacturing method of an aluminum alloy heat exchanger.

[0007]

First, according to the brazing method of the present invention, JIS
Any conventional vacuum brazing method using a brazing material such as 4004, JIS 4343, or JIS 4045, a flux brazing method, or a nocolock brazing method using a non-corrosive flux is not particularly limited. This is because the present invention is a method of improving properties by heat-treating a heat exchanger that has completed brazing heating, and is not related to brazing itself before that. Therefore, pre-brazing assembly, cleaning,
Depending on the case, the flux application or the like may be performed as usual.
That is, it is sufficient to carry out the conventional method until the brazing heating and the cooling, and it is not necessary to change the brazing conditions specified for the purpose of improving the brazing property and preventing the fins from collapsing. Therefore, the present invention does not aggravate problems associated with brazing, such as brazing properties.

In the present invention, a treatment of maintaining the temperature of 400 to 500 ° C. for 10 minutes or more and 30 hours or less is performed during cooling after the brazing heating is completed. This is one of the main points of the present invention, and was obtained by the inventor after earnestly examining the change in the characteristics when the heat exchanger is reheated. That is, brazing heating is performed at a temperature near 600 ° C., but at that time, a considerable amount of the alloying elements in the material form a solid solution. For example, in the case of the 3003 alloy, Mn of about 1.0 wt% (hereinafter simply referred to as “%”), Fe of about 0.025%, and all of S.
The solid solution progresses during temperature rising and holding until i is solid dissolved. In the conventional heat exchanger, the material in which the alloy element is solid-solved is used. The present invention has obtained a method for improving the thermal conductivity of the material and improving the thermal efficiency of the heat exchanger by re-precipitating the solid solution element during brazing as described above. That is, when the material is held in the above temperature range, Mn, Fe, and Si, which are contained as additional elements and inevitable impurities in the material, are mainly precipitated, and the thermal conductivity of the material is improved. As a result, the thermal efficiency of the heat exchanger is improved by about 3% as compared with the case where this treatment is not carried out, although it is slightly different depending on the alloy of the material used. As described above, according to the present invention, since the heat treatment is performed when the entire heat exchanger is heated, the fins have not been conventionally considered for the thermal conductivity, and the thermal conductivity of the refrigerant passage is also improved. The thermal efficiency of is greatly improved. In addition, here, 50
Even if the temperature is maintained above 0 ° C or below 400 ° C, the precipitation of Mn and Fe, which greatly contributes to the improvement of thermal conductivity, progresses slowly, and a sufficient amount of precipitation is obtained when the holding time is less than 10 minutes. Since it cannot be done, it is decided to hold at 400 to 500 ° C. for 10 minutes or more. Further, even if the holding is carried out for more than 30 hours, the precipitation after that is small and the economical efficiency is poor.
Hold for less than 30 hours. Further, particularly when the temperature is kept below 400 ° C., the precipitation phase harmful to the corrosion resistance generated at the time of temperature rise in the refrigerant passage does not re-dissolve by heating, so that the corrosion resistance decreases.

When the treatment of the present invention is performed, Mn is 0.1
%, Fe, the solid solution amount decreases to about 0.001%,
At that time, since a compound containing Si is deposited, the amount of Si solid solution also decreases. The holding in the present invention does not need to be kept at a constant temperature, and may be changed in any manner within a temperature range of 400 to 500 ° C.

Further, in the present invention, after the holding at the above temperature, cooling in a temperature range between 200 ° C. and less than 400 ° C. is performed at a cooling rate of 30 ° C./min or more. This is to prevent precipitation of simple Si, Mg-based compounds, and Cu-based compounds. When these compounds precipitate during cooling,
The strength cannot be expected to improve due to age hardening which will be performed later. Here, if the cooling rate is less than 30 ° C./minute, the above precipitation occurs during cooling and the strength improving effect is not obtained. Incidentally, in the past, the average cooling rate was about 10 ° C./min, which was a cause of reducing the characteristics. Here, the cooling method may be any of furnace hollow cooling, air blowing cooling, water cooling, mist spraying, etc., and is not particularly limited.

In the present invention, the heat exchanger cooled as described above is further heated at a temperature of 120 to 220 ° C. for 30 minutes or more 48.
Perform aging treatment within time. This is done especially for the purpose of improving the strength of the tubes and plates. The aging temperature and time are slightly different depending on the alloy used in the heat exchanger, but both are 120 ° C or more and 220 ° C or less and 30 minutes or more and 48 hours or less. This is because it does not age harden.
This is because if the temperature exceeds 0 ° C., the amount of precipitation becomes too large and the corrosion resistance decreases. Also, if the time is less than 30 minutes, age hardening is not sufficiently performed, and the treatment exceeding 48 hours is not economical. This aging treatment is usually performed after cooling to room temperature by the above cooling, but when the temperature is less than 200 ° C., it may be performed during the above cooling. The method for manufacturing the heat exchanger of the present invention has been described above, and the aluminum alloy used as the material for the heat exchanger of the present invention will be described.

The present invention is a manufacturing method in which an age hardening type alloy is used for any member of the material of the heat exchanger,
If no age-hardening alloy is used, the final aging treatment is wasted. Usually, the upper limit of the additive element of the aluminum alloy used for the heat exchanger is Fe: 1.2%, Si: 1.2.
%, Cu: 1%, Mn: 2.0%, Mg: 2.5%, C
r: 0.3%, Zr: 0.3%, Ti: 0.3%, N
i: 0.5%, Zn: 3.0%, In: 0.3%, S
n: 0.3%. These may or may not be added depending on the type of each member and the type of heat exchanger to be assembled. In the present invention, one of the members of the heat exchanger is made of an alloy that does not exceed the above upper limit, and is Cu:
An aluminum alloy containing at least one of 0.3% or more and Mg: 0.1% or more is used. Cu or M
g is an element that improves the strength of the alloy by age hardening, and unless the alloy contains any of these, the final aging treatment of the present invention becomes useless. Such an age-hardening alloy is often used as a member of a heat exchanger, which serves as a passage for a refrigerant solution such as a tube.

By the way, in the present invention, the thermal conductivity of all members of the heat exchanger is improved by the heat treatment at a temperature of 400 to 500 ° C. This is because industrially used aluminum alloys always contain Fe and Si as unavoidable impurities, and since the present invention causes precipitation of Fe and Si, any aluminum alloy material can be used. Is the way. Furthermore, the thermal conductivity does not decrease in the aging treatment at a temperature of 120 to 220 ° C. Therefore, in the present invention, if the above age hardening alloy is used for any member,
Although the alloy is not limited to other members, when the present invention is used for an alloy containing 1% of conventional 3003 series Mn, M
The effect of improving the thermal efficiency by the precipitation of n is remarkable. Also, A
In the case of the 1-Zr-based alloy, there is an effect of improving thermal efficiency due to the precipitation effect of Zr.

Further, since the brazing material does not affect the present invention as described above, it is sufficient to use a conventionally used Al--Si type or Al--Si--Mg type brazing material. The invention makes no limitation on the brazing material.
After the present invention, steps such as flux removal and coating may be performed as usual.

[0015]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 Combination of aluminum alloy fin material having the composition shown in Table 1, tube material and header plate material
The radiator shown in was assembled (combinations are shown in Table 3).
As the tube material, a coil-shaped plate material having a plate thickness of 0.4 mm shown in Table 1 was manufactured by an ordinary method, and the coil-shaped plate material was slitted into a strip material of 35.0 mm according to the size of the electric resistance welded pipe.
This strip material was processed into an electric resistance welded pipe having a width of 16.0 and a thickness of 2.2 mm by using an electric resistance welded pipe manufacturing apparatus. Further, a coil-shaped plate material having a plate thickness of 1.0 mm and having the same structure was slitted to a width of 60 mm to obtain a header strip. The assembled radiator was applied with a 10% solution of a fluoride-based flux, heated in N ₂ gas under normal conditions, and brazed. Then, reheating was performed under the conditions shown in Table 2. Table 3 shows combinations of materials and heating conditions. The resulting radiator was investigated for thermal efficiency and corrosion resistance. The thermal efficiency was measured according to JIS D 1618 (Testing method for air conditioners for automobiles), and the rate of improvement with respect to the thermal efficiency of the heat exchanger by the conventional method is shown in Table 3. Also,
The fin material and the tube material were simultaneously heated and the strength was measured. The results are shown in Table 3.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

As is apparent from Table 3, Example No. 1 of the present invention produced by the method of the present invention. 1 to 3 and 8 to 10 are superior in thermal efficiency to the conventional example. Furthermore, the effect of improving the strength is remarkable in the tube material. On the other hand, Comparative Example No. manufactured by the comparative method. It can be seen that in Nos. 4 to 6 and 11 to 13, the thermal efficiency is not improved and the strength of the tube material is not improved.

Example 2 An aluminum alloy fin material having the composition shown in Table 1 and a plate material having the composition shown in Table 1 were combined, the core shown in FIG. 2 was assembled, and vacuum brazing was performed under normal conditions. After that, reheating was performed under the conditions shown in Table 2. These combinations are shown in Table 4. The heat efficiency of the obtained heat exchanger was investigated in the same manner as in Example 1. The results are shown in Table 4. In addition, the fin material and the tube material were simultaneously heated to measure the strength. The results are shown in Table 4.

[0021]

[Table 4]

As is clear from Table 4, Example No. of the present invention produced by the method of the present invention. 21-23 and 28-30 have excellent thermal efficiency, and the plate material has high strength. On the other hand, Comparative Example No. manufactured by the comparative method. It can be seen that 24-26, 31-33 do not show the effect of improving the thermal efficiency, and the strength of the plate material is not improved.

Example 3 An aluminum alloy fin material having the composition shown in Table 1 and an extruded multi-hole tube having the composition shown in Table 1 were coated with a chloride flux to assemble the core shown in FIG. I brazed in. Then Table 2
Reheating was performed under the conditions shown in. These combinations are shown in Table 5. The heat efficiency of the obtained heat exchanger was investigated. The results are shown in Table 5. In addition, the fin material and the tube material were simultaneously heated to measure the strength. The results are shown in Table 5.
Shown in.

[0024]

[Table 5]

As is apparent from Table 5, Example No. of the present invention produced by the method of the present invention. Nos. 41 to 43 and 48 to 50 are superior in thermal efficiency to the conventional example, and the strength of the tube material is also high.
On the other hand, Comparative Example No. manufactured by the comparative method. 44-4
It can be seen that Nos. 6, 51 to 53 are not effective in improving the thermal efficiency, and the strength of the tube material is not improved.

[0026]

As described above, when the heat exchanger is manufactured by the method for manufacturing the aluminum alloy heat exchanger of the present invention, the heat conductivity and strength of the members are improved, and the heat exchanger is small and lightweight. It is possible to make it possible, and it has a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view showing a radiator.

FIG. 2 is a partial cross-sectional perspective view showing a laminated evaporator.

FIG. 3 is a perspective view of a partial cross-section showing a laminated evaporator.

[Explanation of symbols]

 1 Flat Tube 2 Thin Fin 3 Header 4 Tank 5 Fin 6, 6'Passage Constituent Sheet 7, 7'Refrigerant Passage 8 Tubing 9 Corrugated Fin 10 Connector

Claims (1)

[Claims] 1. When manufacturing an aluminum alloy heat exchanger by a brazing method, a temperature of 400 to 500 ° C. is maintained for 10 minutes or more and 30 hours during cooling after completion of brazing heating, and then 200 ° C. As described above, aluminum is characterized by performing cooling in a temperature range of less than 400 ° C at a cooling rate of 30 ° C / min or more, and further performing aging treatment at a temperature of 120 to 220 ° C for 30 minutes to 48 hours. Method for manufacturing alloy heat exchanger.