JPH0331454A - Manufacture of aluminum alloy fin material for heat exchanger - Google Patents

Abstract

PURPOSE:To obtain the Al alloy fin material for a heat exchanger having excellent brazability and drooping resistance by subjecting an Al alloy contg. Mn and Fe to continuous casting and rolling, thereafter to cold rolling as well as executing alkali cleaning, subjecting the alloy to process annealing and thereafter executing final cold rolling. CONSTITUTION:An Al alloy contg., by weight, 0.3 to 2.0% Mn and 0.05 to 2.0% Fe is continuously cast and rolled into 2 to 10mm thickness, and the above Mn and Fe as the elements to be added are allowed to enter into solid soln. in a fine material. Next, the rolled sheet is subjected to cold rolling and alkali cleaning is simultaneously executed for 1 to 300 sec by an alkali soln. of >=10pH before or during the cold rolling to remove an oxidized film and to prevent the deterioration of the brazability. Furthermore, during the above cold rolling, process annealing is executed at 320 to 550 deg.C, and final cold rolling is thereafter executed at 15 to 70% rolling reduction into 0.04 to 0.2mm sheet thickness, by which the objective Al alloy fin material for a heat exchanger can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing an aluminum alloy fin material for a heat exchanger having excellent brazing properties and droop resistance.

[Prior art and problems to be solved by the invention] Aluminum alloy heat exchangers, which are generally assembled by brazing or joining, have passages (hereinafter referred to as tubes) through which a refrigerant such as water passes.
and heat dissipating fins, and the tube may be an extruded flat multi-hole tube or an Al-3i tube depending on the use of the heat exchanger.
Plates and electric resistance welded flat tubes are used, which are press-formed plates made of plating sheets clad with brazing filler metals as a skin material. As shown in Figure 2, the fin material used is a plating sheet in which both sides of the core material (4) are clad with a skin material (5), or a bare fin material (bare material) that is not clad with a skin material. ing.

Specific examples of aluminum alloy heat exchangers made by brazing are shown in FIGS. 3 to 6. Figure 3 shows a Dron cup evaporator, in which press-formed plates (6) made of praising sheets are stacked to form a tube (1), and corrugated fins (3) made of bare material or praising sheets are assembled to this. It is a combination. FIG. 4 shows an evaporator, which is a combination of a tube (1) made of an extruded flat multi-hole tube and a corrugated fin (3) made of a plating sheet. Figure 5 shows a capacitor, consisting of a tube (1) made of an extruded multi-hole tube and a corrugated fin (
3). Figure 6 shows a radiator, consisting of a tube (1) made of an ERW flat tube (brazing metal is on the outside of the tube) made of a plating sheet clad with Al-8i alloy brazing material on one side, and a bare material. fin(
3). The tubes and corrugated fins of these heat exchangers are assembled by flux brazing, vacuum brazing, or inert gas atmosphere brazing at a temperature of about 600°C.

Conventionally, in aluminum alloy heat exchangers that require assembly, such brazing is performed using Al-Mn alloys with good buckling resistance as fin materials, such as Tsuki S 3QO3 alloy (AJ
-0,05~0.20v1%Cu -1,0~1.5
wt%Mn alloy) (hereinafter w1% is abbreviated as %) or Moon S
3203 alloy (Al-1.0-1.5% Mn alloy) as a core material, and Al-Si alloy brazing material CAl-5 on both sides.
~12%Si alloy) or Al-31-Mg alloy brazing filler metal (
0.1" 0.2 mm thick plating sheet clad with Al-5~12% 5i-0,5~2% Mg alloy) or 0.1~0.04~0.2 mm thick plating sheet J.I.
Bare materials made of S 3003 and 3203 alloys are used.

In recent years, among heat exchangers, especially heat exchangers for automobiles, there is a trend toward weight reduction and downsizing, and there is a strong demand for thinner fins. However, when the fins are made thinner, there is a problem that the high-temperature buckling resistance decreases. Methods have been proposed to increase the strength. However, although fin materials manufactured by continuous casting and rolling do have high high-temperature strength, they have poor brazing properties and have problems in that sufficient brazing cannot be achieved due to heating.

[Means to solve the problem]

In view of this, as a result of various studies, the present invention has developed a method for producing an aluminum alloy fin material for heat exchangers that has excellent high-temperature buckling resistance (sagging resistance) and brazing resistance.

That is, one of the manufacturing methods of the present invention is that M n 0.3 to 2.0
%, F e O, containing 05 to 2.0% and the balance Al
After continuous casting and rolling, an aluminum alloy consisting of unavoidable impurities is made into a plate with a thickness of 2 to 10 m, followed by cold rolling, and washing with an alkaline solution of 9110 or higher for 1 to 3011 seconds before or during the cold rolling. After processing and performing intermediate annealing at 320 to 550°C during cold rolling, final cold rolling is performed at a rolling reduction of 15 to 70% to achieve a plate thickness of 0.04 to 550°C.
It is characterized by being made of 0.2 m fin material.

Another method of the present invention is that M n 0.3-2
．． 0%, F e O, 05-2.0%, and further Z
rO, 3% or less, Cr, 0.3% or less, Tie, 1% or less.

Cu O, 5% or less, Si 0.8% or less, Mg (1,5
Contains any one or two or more types within the range of % or less, the remainder A
After continuous casting and rolling, an aluminum alloy consisting of l and unavoidable impurities is made into a plate with a thickness of 2 to 1 G, and then cold rolled, and before or during the cold rolling, an alkaline solution with a pH of 1 to 100 g or higher is applied. After washing for seconds and performing intermediate annealing at 320 to 550°C during cold rolling, final cold rolling is performed at a rolling reduction of 15 to 70% to obtain a plate with a thickness of 0.04 to
It is characterized by being made of 0.02m fin material.

[Effect]

In the present invention, the alloy composition is limited as described above for the following reasons.

Mn improves the strength and sagging resistance of the fin material, and the reason why the Mn content is limited to 0.3 to 2.0% is that if it is less than the lower limit, the effect will not be sufficient, and if it exceeds the upper limit, the molding processability will deteriorate. This is to reduce the

Although Fe particularly improves strength, sagging resistance, and formability, its content is limited to 0.05 to 2.0%, because it is ineffective below the lower limit and adversely affects formability when it exceeds the upper limit. This is because it decreases to .

In addition, in the present invention, ZrO, 3% or less, Cr013%
Below, Ti is 0.1% or less, CuO is 5% or less.

The reason for adding one or more of Si 0.8% or less and Mg 0.5% or less is to further improve the room temperature strength and high temperature strength (sagging resistance) of the fin material. Zr, Cr, and Ti are effective in refining crystal grains and improving high-temperature strength, while CLI, Si, and Mg are effective in increasing the room-temperature strength of the fin and improving formability. Select and add.

In the manufacturing method of the present invention, first, an aluminum alloy having the above composition is continuously cast and rolled into a plate having a thickness of 2 to 10 cm. Continuous casting and rolling is carried out here because of the additive elements Mn and F.
The purpose of this is to dissolve e as a solid solution in the fin material, and in the conventional DC casting and hot rolling processes, most of Mn and Fe precipitate during hot rolling, and this improves the droop resistance of the fin. This is because it is not possible. In addition, the reason why plates with a thickness of 2 to 10 mm are made by continuous casting and rolling is that if the thickness is less than 2 mm, cracks will occur, reducing the productivity of continuous casting and rolling, and if the thickness exceeds 10 mm, cooling during solidification will occur. This is because the speed decreases and Mn and Fe cannot be sufficiently dissolved in solid solution.For continuous casting and rolling, the conventionally used Hunter method or 30 method is used, and the cooling rate is set to 50°C/sec or more. do.

Next, the above continuously cast rolled plate is cold rolled, and the plate thickness is 0.04~
The fin material is 0.2 mm. During this cold rolling 32
Perform intermediate annealing at 0 to 550°C to achieve a final cold rolling rate of 15
~70%. This is because the sagging resistance decreases even if the final cold rolling reduction is less than 15% or more than 70%. Furthermore, the intermediate annealing temperature was set at 320 to 550°C.
If the temperature is below 550℃, recrystallization will not proceed sufficiently and Mn will precipitate at subgrain boundaries during intermediate annealing, and brazing will extremely reduce sagging resistance during heating. This is because the Mn dissolved in solid solution precipitates and reduces the sagging resistance. The holding time for intermediate annealing is usually 0.5~
About 6 hours is sufficient.

By determining the additive elements of the alloy and the manufacturing process in this way, it is possible to obtain a fin material with excellent droop resistance.
Brazing is insufficiently durable.

When rolled by continuous casting and rolling, the oxide film formed on the plate surface during rolling becomes thick, and even after cold rolling to the fin material, this thick oxide film remains, reducing brazing properties. In the present invention, in order to prevent such brazing from deteriorating properties, alkaline washing is performed for 1 to 300 seconds using an alkaline solution having a pH of 111 or more before or during cold rolling.

The reason why alkali cleaning is not performed after cold rolling is that if one pass of cold rolling is not performed after alkali cleaning, the surface of the fin material will become extremely uneven and the brazing properties will deteriorate. .

However, if the alkaline cleaning condition is to treat with an alkaline solution with a pH of 10 or more for 1 to 300 seconds, if the concentration of the alkaline solution is less than pH 10 or the cleaning time is less than 1 second, the cleaning will be insufficient, and the oxide film will not be sufficiently removed. In addition, washing for more than 300 seconds is not only undesirable from the viewpoint of productivity, but also causes excessive Al to dissolve during washing, resulting in poor brazing properties. to Al-
This is because Mn-based intermetallic compounds remain and the brazing properties deteriorate.

In the present invention, a temperature range of 15 to 90°C is sufficient for performing alkaline cleaning, and the alkali used is NaO.
H, KOH, Ca(OH)2, etc. may be used, but it is particularly desirable to use 0.3 to 10% NaOH and conduct the treatment for 5 to 60 seconds. Furthermore, in the present invention, it is desirable to perform acid cleaning consecutively after alkaline cleaning. Acid cleaning has the effect of neutralizing the alkali with acid, preventing the alkaline solution from remaining on the surface of the plate and deteriorating the surface quality, and dissolving the crystallized phase that has risen to the surface due to the alkali cleaning. Attaching prevents sexual decline.

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

[Example] A fin material having a thickness of 0.06 m was produced from an aluminum alloy having the composition shown in Table 1 according to the manufacturing process shown in Table 2. A drooping test was conducted on the fin material obtained in this way, and as shown in Fig. 1, JI
Tube material made of 33003 alloy with a wall thickness of 0.4 mm (1
) and a corrugated fin (1) formed from the above fin material
Combine and heat at 600℃ in a vacuum of 5X10 Torr.
Vacuum brazing was performed for 0 minutes, and the bonding state and buckling state of the fins were examined. These results are shown in Table 3.

The droop test was carried out at 600℃ in vacuum with an overhang length of 50mm.
The amount of drooping after heating for 0 minutes was examined. In addition, the buckling condition is visually inspected after vacuum brazing, and those that do not cause buckling are
and those in which buckling occurred are indicated by x marks. Furthermore, the bonding condition was determined by peeling off the fin from the tube after vacuum brazing, measuring the length of the metallic bond between the tube and the fin, and examining the ratio to the total length to be bonded.
Those with 5% or more bonding are marked O, those with less than that are marked X.
Represented by a mark.

Table 3 As is clear from Tables 1 to 3, it can be seen that the fin material produced by the method of the present invention has superior fin characteristics as compared to the fin material produced by the conventional method. Also, NaO during cold rolling
It can be seen that the comparative method in which cleaning with H was omitted was inferior in fin characteristics. ′ [Effect of the invention] The fin material produced by the manufacturing method of the present invention as described above has the following properties:
It has excellent droop resistance and brazing properties, and has significant industrial effects such as making it possible to reduce the weight of heat exchangers by making the fins thinner.

[Brief explanation of drawings]

Fig. 1 is a side sectional view showing the state of the full gate fin and tube joined by vacuum brazing, Fig. 2 is a side sectional view showing an example of the fin material made of plating sheet, and Fig. 3
The figure is a side view showing an example of a Doron' cup evaporator.
FIG. 4 is a perspective view of an example of an evaporator, FIG. 5 is a perspective view of an example of a condenser, and FIG. 6 is a side view of an example of a radiator. 1, Tube 2, /1kl-3i alloy brazing filler metal 3, Corrugate fin 4, Core material 5, Skin material 6° Press-formed plate Fig. 2 Fig. 3 Fig. 1 Fig. 4 Fig. 5 Fig. 6

Claims (2)

[Claims] (1) Mn0.3-2.0wt%, Fe0.05-2.0wt%.
An aluminum alloy containing 0 wt% and the remainder Al and unavoidable impurities is continuously cast and rolled to a thickness of 2 to 10 m.
After forming a plate with a pH of 1 to 300 m, it is cold rolled, and before or during the cold rolling, it is heated to 1 to 300 m with an alkaline solution having a pH of 10 or more.
After washing for seconds and performing intermediate annealing at 320 to 550°C during cold rolling, final cold rolling is performed at a rolling rate of 15 to 70% to produce a fin material with a plate thickness of 0.04 to 0.2 mm. A method for producing an aluminum alloy fin material for a heat exchanger, characterized in that: (2) Mn0.3-2, 0wt%, Fe0.05-2.
0wt%, further Zr0.3wt% or less, Cr0.
3wt% or less, Ti 0.1wt% or less, Cu 0.5wt
% or less, Si 0.8wt% or less, Mg 0.5wt% or less, and the remainder is Al and unavoidable impurities. After forming a plate, it is cold rolled, washed for 1 to 300 seconds with an alkaline solution with a pH of 10 or more before or during the cold rolling, and intermediate annealed at 320 to 550°C during the cold rolling. , rolling ratio 1
Perform final cold rolling of 5-70% to obtain a plate thickness of 0.04-0.
．． A method for producing an aluminum alloy fin material for a heat exchanger, characterized in that the fin material is 2 mm thick.