JPH06172946A - Production of aluminum alloy fin material for heat exchanger - Google Patents

Abstract

PURPOSE:To produce a fin material made of an Al alloy for a heat exchanger excellent in heat conductivity and strength after brazing by subjecting the directly cast and rolled sheet of an Al alloy having a specified compsn. to cold rolling, thereafter annealing it at a specified temp. and furthermore executing final cold rolling. CONSTITUTION:An Al alloy having a compsn. contg., by weight, 0.005 to 0.3% Si, 0.5 to 1.2% Fe and one or two kinds of 0.1 to 1.2% Ni and Co or furthermore contg. 0.03 to 0.2% Zr and one or >= two kinds among <2.0% Zn, <0.3% In and <0.2% Sn independently or compositely, and the balance Al is directly cast and rolled to work into an Al alloy sheet having about <=20mm thickness. This Al alloy sheet is subjected to process annealing and is thereafter subjected to cold rolling into a sheet material having about 0.1mm thickness, which is furthermore annealed at 300 to 550 deg.C and is thereafter subjected to final cold rolling at 10 to 80% draft to work into a thin sheet material having about 0.06mm thickness. The thin sheet made of an Al alloy having excellent characteristics as a fin material for a heat exchanger can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum alloy fin material for a heat exchanger having high heat conductivity, and more particularly to a heat exchanger for an automobile manufactured by a brazing method. The present invention relates to a method for manufacturing an aluminum alloy fin material used as a fin for a radiator, a heater, a condenser or the like.

[0002]

2. Description of the Related Art Most heat exchangers for automobiles use Al and Al alloys and are manufactured by a brazing method. Usually, Al-Si type brazing material is used for brazing, so brazing is performed at a high temperature of about 600 ° C. In a heat exchanger such as a radiator, for example, as shown in FIG. 1, corrugated thin-walled fins (2) are integrally formed between a plurality of flat tubes (1) to form flat tubes.
Both ends of (1) are opened in the space consisting of the header (3) and the tank (4), and the high-temperature refrigerant is passed from the space on one tank side through the flat tube (1) to the other tank.
The refrigerant is sent to the space on the (4) side, and heat is exchanged in the flat tubes (1) and the thin fins (2) to recirculate the low temperature refrigerant.

By the way, in recent years, heat exchangers have been in the direction of weight reduction and miniaturization. For that purpose, it is necessary to improve the heat efficiency of the heat exchanger, and it is desired to improve the heat conductivity of the material. In particular, improvement of the thermal conductivity of the fin material has been studied, and a fin material of an alloy having an alloy composition close to that of pure aluminum has been proposed as a high thermal conductivity fin. However, when the fins are made thin, there is a problem that if the strength of the fins is not sufficient, the fins will be crushed when the heat exchanger is assembled, or will be broken when the heat exchanger is used. The pure aluminum alloy fin has a drawback of insufficient strength, and a fin material having high strength and improved thermal conductivity has not yet been developed. This is because the addition of alloying elements such as Mn is effective for increasing the strength, but since brazing is heated to around 600 ° C. in the process of manufacturing the heat exchanger, it is added to the alloy during brazing heating. This is because the element re-dissolves in solid solution and hinders improvement of heat conduction.

[0004]

In view of this, the present inventors inevitably include aluminum alloys used industrially in order to develop a fin material having high strength and thermal conductivity after brazing. It was considered necessary to optimize the amounts of Si and Fe, which are the elements to be added, in order to improve the thermal conductivity.
Further, it is believed that the problem can be solved by finding an alloy element having a large effect of improving the strength without lowering the thermal conductivity and developing a manufacturing process in which the effect of adding the element is most exerted, and the present invention Arrived

That is, the present invention is to develop a method for producing an aluminum alloy fin material for a heat exchanger, which is excellent in heat conductivity and strength after brazing. The invention according to claim 1 is 0.005 wt%. Over 0.3 wt% Si, 0.
One or two of Fe containing more than 5 wt% and 1.2 wt% or less, further Ni exceeding 0.1 wt% and 1.2 wt% or less, and Co exceeding 0.1 wt% and 1.2 wt% or less. In producing an aluminum alloy fin material containing seeds and the balance Al and unavoidable impurities, a plate material having a thickness of 20 mm or less is produced by direct casting and rolling, and after performing cold rolling on the plate material, 300 to A method for producing an aluminum alloy fin material for a heat exchanger, which comprises performing annealing in a temperature range of 550 ° C. and further performing cold rolling at 10 to 80%, and the invention according to claim 2 provides 0.005 wt. % To 0.3 wt% or less of Si, 0.5 wt% to 1.2 wt% or less of Fe, 0.03 wt% to 0.2 wt% or less of Zr, and more than 0.1 wt% of 1 N less than 2 wt%
i, 1 of Co exceeding 0.1 wt% and 1.2 wt% or less
In producing an aluminum alloy fin material containing one or two kinds and the balance Al and unavoidable impurities,
A plate material having a thickness of 20 mm or less is produced by direct casting and rolling, the plate material is cold-rolled, annealed in a temperature range of 300 to 550 ° C., and further cold-rolled by 10 to 80%. A method for manufacturing an aluminum alloy fin material for a heat exchanger, wherein the invention according to claim 3 is 0.00
Contains more than 5 wt% and less than 0.3 wt% Si, more than 0.5 wt% and less than 1.2 wt% Fe, and more than 0.1 wt% and less than 1.2 wt% Ni, more than 0.1 wt% 1.2 wt%
It contains one or two of the following Co, and further contains 2.0 wt% or less of Zn, 0.3 wt% or less of In, 0.3
containing one or more of wt% or less of Sn,
When manufacturing an aluminum alloy fin material composed of the balance Al and unavoidable impurities, the thickness of the aluminum alloy fin material is 2 by direct casting and rolling.
Aluminum for heat exchangers, characterized in that a plate material having a size of 0 mm or less is produced, cold-rolled to the plate material, annealed in a temperature range of 300 to 550 ° C., and further cold-rolled to 10 to 80%. A method for manufacturing an alloy fin material, wherein the invention of claim 4 is more than 0.005 wt% and 0.3 wt%
The following Si, Fe exceeding 0.5 wt% and 1.2 wt% or less,
Ni containing more than 0.03 wt% and less than 0.2 wt% Zr, and more than 0.1 wt% and less than 1.2 wt% Ni, 0.1 wt%
% Or more and 1.2 wt% or less Co of 1 or 2 types, 2.0 wt% or less Zn, 0.3 wt% or less In, 1 of 0.3 wt% or less Sn Seed or 2
In manufacturing an aluminum alloy fin material containing at least one kind and consisting of the balance Al and unavoidable impurities, a plate material having a thickness of 20 mm or less is produced by direct casting and rolling, and after the plate material is cold rolled, 300 A method for producing an aluminum alloy fin material for a heat exchanger, characterized by performing annealing in a temperature range of to 550 ° C and further performing cold rolling at 10 to 80%.

[0006]

First, the role of the additional element of the aluminum alloy using the manufacturing method of the present invention and the reason for limiting the alloy composition will be described. When Si coexists with Fe, Ni, or Co, Si has an action of promoting precipitation of Fe, Ni, or Co, and therefore increases intermetallic compounds that contribute to dispersion strengthening and improves strength. Further, by promoting the precipitation of Fe, Ni, and Co, the solid solution amount of Fe, Ni, and Co dissolved in the fin material is reduced, so that the thermal conductivity is improved. When Si is 0.005 wt% or less, the above effect is not sufficient, and
Even if it exceeds 3 wt%, the action of promoting the precipitation of Fe, Ni and Co does not change, but on the contrary, the solid solution amount of Si increases and the thermal conductivity decreases. Further, Si has the function of increasing the potential of the fin to reduce the sacrificial effect, and therefore, the smaller the amount, the more desirable. Therefore, although Si is set to more than 0.005 wt% and 0.3 wt% or less, particularly stable properties are exhibited at 0.03 to 0.2 wt%.

Fe forms an intermetallic compound and contributes to the improvement of strength. If the amount is 0.5 wt% or less, there is no effect,
When it exceeds 1.2 wt%, the moldability is deteriorated and it becomes difficult to perform corrugation molding of fins.

Ni and Co distribute a fine intermetallic compound in the alloy to improve the strength. When added together with Si, it is very likely to precipitate, so it is an element that can improve strength without lowering thermal conductivity. If the amount is 0.1 wt% or less, the effect is not sufficient, and if it is added in excess of 1.2 wt%, the formability is deteriorated and it becomes difficult to perform corrugate forming of fins.

Zr has a function of increasing the recrystallized grains of the fin generated during the brazing heat. When the recrystallized grains become small, the brazing material diffuses into the fins during brazing, and the fins are easily crushed. Since the present alloy contains a relatively large amount of Fe, the recrystallized grains may become small.
It is advisable to add r. If the amount is 0.03 wt% or less, the effect is not sufficient, and even if it is added in excess of 0.2 wt%, the effect remains the same and conversely the thermal conductivity decreases.

In the present alloy, Zn of 2.0 wt% or less,
One or more of In of 0.3 wt% or less and Sn of 0.3 wt% or less may be added. They are,
It is added to impart a sacrificial anode effect to the fin material, and if added in excess of the above amounts, the thermal conductivity will decrease.

The unavoidable impurities of the present alloy include Ti and B which are added due to the fineness of the ingot structure, and these unavoidable impurity elements are added if the content is 0.03 wt% or less. It doesn't matter.

The above are the reasons for limiting the alloy composition of the aluminum alloy used in the production method of the present invention.
In producing these aluminum alloy fin materials, a plate material having a plate thickness of 20 mm or less is produced by direct casting and rolling, and after cold rolling the plate material, 300 to 550 ° C.
It is characterized in that annealing is carried out in the temperature range of 10% and cold rolling of 10 to 80% is further carried out. This manufacturing method will be described below.

In the method for producing the fin material of the present invention, the above aluminum alloy is produced by the steps of direct casting and rolling, cold rolling and annealing. The direct casting and rolling may be performed by a conventionally known method such as the Hunter method or the 3C method. Here, the upper limit of the plate thickness produced by direct casting and rolling is set to 20 mm,
If it exceeds 20 mm, the quenching effect during casting is small, and Fe,
This is because the intermetallic compound generated from Ni and Co becomes coarse and the effect of improving the drooping resistance of the fin is reduced. Although the lower limit of the plate thickness is not particularly defined, it is set to about 2 mm due to the limit of manufacturing equipment. A plate (coil) manufactured by direct casting and rolling is first cold-rolled. The cold rolling is performed to a plate thickness such that the final cold rolling rate of the fin material falls within the range of 10 to 80%.
The cold rolling here may be performed in one pass, or may be performed in several passes.

After cold rolling, annealing is performed. Annealing is performed using a batch type furnace or a continuous type furnace. In the case of a batch type furnace, the temperature is 300 to 460 ° C and the time is 0.5 to 1
Two hours is the preferred range. By this annealing treatment, Ni or Co solid-dissolved in supersaturation by direct casting and rolling is precipitated, and the precipitated Ni and Co coarsen the recrystallized grains when brazing heat is added to improve droop resistance. 300 ° C
If the amount is less than the above value, recrystallization is not completed, so that the annealing treatment is insufficient. When it exceeds 460 ° C., the precipitation phase is coarsened, and there is no effect in improving the drooping property. If the time is less than 0.5 hours, the annealing treatment is insufficient and Ni and Co are not sufficiently precipitated. Further, since the treatment for a long time is economically problematic, the upper limit is preferably 12 hours. When using a continuous furnace, the temperature is 420 to 550 ° C., and the time is preferably 1 to 60 seconds. In case of continuous annealing,
It is characterized in that it can be annealed by heating for a short time, and for such short heating, it is possible to complete the annealing while directly dissolving Ni or Co which is dissolved in supersaturation by direct casting and rolling. You can Therefore, Ni and Co, which are solid-soluted in supersaturation by direct casting and rolling, remain in the fin in supersaturation as they are and are used for additional heat of the brazing. 42
If the temperature is lower than 0 ° C., the recrystallization is not completed, so that the annealing treatment is insufficient. The effect does not change even if the temperature exceeds 550 ° C, but the fuel cost increases. If the time is less than 1 second, the annealing treatment is insufficient. In addition, it is economically inefficient to perform the treatment at such a high temperature for a long time, and the solid solution Ni is dissolved.
It is preferable that the upper limit is 60 seconds, since Co and Co precipitate coarsely and the droop resistance is lowered.

After the above annealing, final cold rolling is performed. Final cold rolling is 10 to 80%. Final cold rolling rate is 1
This is because when the content is less than 0%, recrystallization does not occur when the fin is heated by brazing, and the brazing easily diffuses into the fin. If it exceeds 80%, fine recrystallized grains are generated when the fin is heated by brazing, and this also facilitates diffusion of the brazing into the fin. In terms of the above-mentioned wax diffusion (drooping property), the final cold rolling rate is 25 to 50%, and particularly excellent characteristics are exhibited. However, when controlling the final cold rolling for reasons such as adjusting the corrugation property according to the corrugator, if the range is 10 to 80%, the drooping property will be practically no problem.

Examples of the heat exchanger using the fin material of the present invention include, but are not limited to, radiators, condensers, evaporators and oil coolers for automobiles.

The fin brazing method of the present invention may be any of the conventional non-corrosive flux brazing, flux brazing, vacuum brazing and the like.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples. Aluminum alloy with the alloy composition shown in Table 1 has a thickness of 8 m
After direct casting and rolling to m, cold rolling was performed, and then fin materials were manufactured by the manufacturing process shown in Table 2. The plate thickness of the fin material is 60 μm. The drooping property of the obtained fin material, the strength after the heat of brazing and the electric conductivity were measured. The brazing heat was applied in nitrogen gas at 600 ° C. for 5 minutes. In the drooping test, the amount of drooping was measured when the fin material was projected and the brazing heat of 50 mm in length was applied to the brazing material. The results are shown in Table 3. Here, the electrical conductivity is an index of thermal conductivity, and if the electrical conductivity of the fin is improved by 5% IACS, the thermal efficiency of the heat exchanger is improved by about 1%. Here, the conventional example uses an Al-Zr alloy known as a fin having excellent thermal conductivity and a general 3003 alloy, and a normal manufacturing method of water cooling casting, chamfering, homogenizing treatment, and hot rolling. After cold rolling the hot rolled coil having a thickness of 3.5 mm, it is annealed in the manufacturing process of Table 2,
It is cold rolled.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

As is clear from Table 3, the fin materials of the conventional example and the comparative example are not excellent in tensile strength, electrical conductivity and drooping property, whereas the fin materials in the alloy range of the present invention. Then, it can be seen that the production method of the present invention exhibits excellent values in tensile strength and conductivity.

[0023]

As described above, the aluminum alloy fin material produced by the manufacturing method of the present invention has high strength and excellent thermal conductivity, and has remarkable industrial effects.

[Brief description of drawings]

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

[Explanation of symbols]

 1 Flat tube 2 Thin fin 3 Header 4 Tank

Claims (4)

[Claims] 1. A content of Si of more than 0.005 wt% and 0.3 wt% or less, Fe of more than 0.5 wt% and 1.2 wt% or less, and Ni of more than 0.1 wt% and 1.2 wt% or less. ,
In manufacturing an aluminum alloy fin material containing one or two kinds of Co exceeding 0.1 wt% and 1.2 wt% or less and the balance Al and unavoidable impurities, the thickness is directly cast and rolled. Aluminum for heat exchangers, characterized in that a plate material having a size of 20 mm or less is produced, cold-rolled to the plate material, annealed in a temperature range of 300 to 550 ° C., and further cold-rolled to 10 to 80%. Method for manufacturing alloy fin material. 2. Si of more than 0.005 wt% and 0.3 wt% or less, Fe of more than 0.5 wt% and 1.2 wt% or less, 0.0
One or two of Ni containing more than 3 wt% and less than 0.2 wt% Zr, more than 0.1 wt% and less than 1.2 wt% Ni, Co exceeding 0.1 wt% and less than 1.2 wt% In producing an aluminum alloy fin material containing seeds and the balance Al and unavoidable impurities, a plate material having a thickness of 20 mm or less is produced by direct casting and rolling, and after performing cold rolling on the plate material, 300 to A method for manufacturing an aluminum alloy fin material for a heat exchanger, which comprises performing annealing in a temperature range of 550 ° C. and further performing cold rolling at 10 to 80%. 3. Containing more than 0.005 wt% and less than 0.3 wt% Si, more than 0.5 wt% and less than 1.2 wt% Fe, and more than 0.1 wt% and less than 1.2 wt% Ni. ,
1 type or 2 types of Co of more than 0.1 wt% and 1.2 wt% or less, further 2.0 wt% or less of Zn, 0.
In producing an aluminum alloy fin material containing 1 wt% or more of In of 3 wt% or less and Sn of 0.3 wt% or less, and the balance Al and unavoidable impurities, the thickness of the aluminum alloy fin material is increased by direct casting and rolling. After making a plate material having a size of 20 mm or less and performing cold rolling on this plate material, 300 to 550 ° C.
The method for producing an aluminum alloy fin material for a heat exchanger, which comprises performing annealing in the temperature range of 10 to 80% and further performing cold rolling at 10 to 80%. 4. A Si content of more than 0.005 wt% and 0.3 wt% or less, a Fe content of more than 0.5 wt% and 1.2 wt% or less, 0.0
One or two of Ni containing more than 3 wt% and less than 0.2 wt% Zr, more than 0.1 wt% and less than 1.2 wt% Ni, Co exceeding 0.1 wt% and less than 1.2 wt% Containing at least one of Zn of 2.0 wt% or less, In of 0.3 wt% or less and Sn of 0.3 wt% or less, and the balance of Al and unavoidable impurities. In producing the aluminum alloy fin material, the plate material having a thickness of 20 mm or less is produced by direct casting and rolling, the plate material is cold-rolled, and then annealed in the temperature range of 300 to 550 ° C. A method for producing an aluminum alloy fin material for a heat exchanger, which comprises performing cold rolling at 80%.