JPH0788635A - Aluminum alloy brazing sheet having excellent formability and production of heat exchanger formed by using the same - Google Patents

Abstract

PURPOSE:To greatly improve the productivity of a heat exchanger for automobile to be produced by press forming and brazing and enhance the stability of quality by forming lubricating layers contg. powdery lubricating particles on the surfaces of an aluminum sheet or aluminum alloy sheet. CONSTITUTION:The lubricating layers deposited with org. lubricating particles at 5 to 1000mg/m<2> are formed on one or both surfaces of a clad metal formed by cladding skin materials consisting of an Al-Si alloy on one or both surfaces of a core material consisting of Al or Al alloy, by which the aluminum alloy brazing sheet having excellent formability is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for manufacturing aluminum heat exchangers having a hollow structure such as a drone cup type oil cooler, evaporator, intercooler, and radiator, and has excellent formability for brazing brazing. The present invention relates to a sheet and a heat exchanger manufacturing method using the sheet.

[0002]

2. Description of the Related Art In recent years, a vacuum brazing method that does not require a flux has been developed for brazing an aluminum structure, and a nocolock method that brazes a non-corrosive fluoride flux in a non-oxidizing atmosphere. It was started from a place where there is no concern about pollution. Vacuum brazing and Nocolock brazing use a brazing sheet in which an aluminum alloy is used as a core material and one or both sides of which are clad with an aluminum alloy (mainly Al-Si alloy) brazing material as a skin material, in a vacuum or in a nitrogen atmosphere. This is a brazing method and is used for brazing various structures such as heat exchangers.

The feature of the Nocolock brazing method is that the flux is non-corrosive, and therefore no post-treatment is required.
It is said that brazing cost is low. This flux is generally a potassium fluoroaluminate complex, and is used by being applied as an aqueous suspension by a dipping method or spray coating. For this reason, the joined body to be brazed is molded and assembled, thoroughly degreased with a solvent, then flux-coated and dried, and then heated and brazed.

As a vacuum brazing sheet used in a heat exchanger, a core material of JISA3003 (Al-0.
15 wt% Cu-1.1 wt% Mn), JIS A3005 (A
l-1.2wt% Mn-0.4wt% Mg), JIS A310
5 (Al-0.55 wt% Mn-0.5 wt% Mg), or JI
S A6951 (Al-0.35wt% Si-0.27wt% Mn-
0.6 wt% Mg) alloy is used, and the skin material is JIS BA
4004 (Al-9.7 wt% Si-1.5 wt% Mg), JI
S BA4104 (Al-9.7 wt% Si-1.5 wt% Mg
It is usual to use a brazing filler metal of 0.1 wt% Bi).
Further, as the nocolock brazing sheet, a core material such as JIS A3003 and an Al-Si based skin material BA4 is used.
343 (Al-7.5 wt% Si), BA4045 (Al-
It is usual to use 10 wt% Si). The plate thickness is 0.5
It is used as a brazing sheet of single sided or double sided clad with a brazing filler metal clad ratio of ~ 1.2 mm and 5-15%.

As an aluminum heat exchanger having a complicated structure using such a brazing sheet, a drone cup type evaporator, an oil cooler, a radiator, etc. are manufactured. For example, in a Delon cup type evaporator, sheet members (1) made of an Al alloy brazing sheet formed so that a refrigerant passage is formed as shown in FIG. 3 are stacked, and corrugated fins (1) are stacked between the stacked members (1). 2) is installed and 10 ^-5 Torr to 10 ^-4 To
It is manufactured by heating to 600 ℃ in a vacuum of rr level and brazing.

In this vacuum brazing, Mg added to the brazing brazing material begins to evaporate gradually from around 400 ° C., and the oxidizing gas in the furnace is changed to H ₂ O + Mg → MgO +
H ₂ and O ₂ + 2Mg → 2MgO is removed by a getter reaction, and when the brazing material melts, Mg in the brazing material evaporates rapidly, causing similar gettering and destruction effects on the oxide film on the brazing material surface. Is possible. Further, Si has the function of lowering the melting point of the brazing material and lowering the brazing temperature to improve the brazing property.

Further, a so-called Nocolock brazing method, in which an evaporator of this type is brazed in a nitrogen gas atmosphere using a small amount of fluoride-based flux, has been industrially put to practical use.

[0008]

The equipment manufactured by these brazing methods is usually press-molded to mold each member, degreased and washed, and then assembled before brazing. In this brazing, if the oil and dirt on the surface of the brazing sheet are not sufficiently removed, improper brazing such as wax breakage will occur immediately. Since many are used, an organic solvent such as triethane having a high degreasing power is mainly used for degreasing and cleaning.

However, recently, from the viewpoint of protecting the global environment, the regulation of the use of these solvents tends to be strengthened, so that development of materials and processing methods which can be processed without using these solvents is strongly desired. The present invention responds to such demands and provides a material which can be processed without press oil and can be brazed well even if it is brazed without going through a degreasing / washing step.

[0010]

[Means for Solving the Problems] On the other hand, regarding press formability, it is essentially important to improve the elongation of aluminum. It was found that the coating with a powdered lubricant is very effective for improving the lubricity. The present invention has been made based on such knowledge, and has developed a brazing sheet having excellent formability that solves the above problems and a method for manufacturing an Al heat exchanger using the brazing sheet.

That is, in the brazing sheet of the present invention, the amount of organic lubricating particles deposited on one or both sides of a laminated material in which a skin material made of an Al--Si alloy is clad on one or both sides of a core material made of Al or Al alloy. Is 5-10
An aluminum alloy brazing sheet excellent in formability, characterized in that a lubricating layer of 00 mg / m ² is formed, wherein the organic lubricating particles have an average particle size of 20 μm.
It is effective to use a wax having an average particle diameter of 2 μm or more and a melting point of 40 ° C. or more and 120 ° C. or less.

A first method of manufacturing an Al heat exchanger according to the present invention is one side of a core material made of Al or an Al alloy and one side of a laminated material in which a skin material made of an Al--Si alloy is clad, or one side thereof. Adhesion amount of organic lubricating particles on both sides is 5
After forming an aluminum alloy brazing sheet formed with a lubricating layer of up to 1000 mg / m ² and combining it with other members,
The method is characterized in that heating is performed at a temperature of 200 to 500 ° C. for less than one hour, then flux is applied and brazing is performed, and the second of the manufacturing methods of the present invention is to form the brazing sheet. And then brazing and heating in a vacuum after combining with other members. As the organic lubricating particles, it is effective to use a wax having an average particle size of 20 μm or less, or further an average particle size of 2 μm or more and a melting point of 40 ° C. or more and 120 ° C. or less.

[0013]

The present invention will be described in more detail below. As a brazing material for the brazing sheet in the present invention, an Al-Si-Mg-based alloy usually used for vacuum brazing or an Al-Si-based alloy used for Nocoloc brazing can be used. These brazing materials are used as brazing sheets by clad as a skin material on one or both sides of a core material. The aluminum material of the core material is not particularly limited, and a common core material made of Al or Al alloy can be used. Further, the manufacturing method of the combined material of the core material and the skin material, the thickness ratio thereof and the like are not particularly different from the conventional ones, and can be carried out according to the usual method.

As the organic lubricating particles, powdered paraffin wax, polyolefin wax and / or derivatives thereof are preferably used. These organic lubricating particles are preferably applied in a state of being dispersed in water or a solvent, and the application method can be arbitrarily selected from ordinary application methods such as roll coater, spraying and dipping. Further, in order to stably disperse the lubricating particles, it is rather preferable to add a small amount of a dispersant or a stabilizer within a range that does not impair the effects of the present invention.
The coating amount of the lubricant particles is limited to the range of 5 to 1000 mg / m ² for an adverse effect on the brazeability the processability improving effect is less than 5 mg / m ² is not sufficient, more than 1000 mg / m ^2.

If the lubricating particles do not melt during drying after coating, if the average particle size exceeds 20 μm, they tend to fall off during handling after drying and workability deteriorates. The average particle size of the lubricating particles is preferably 20 μm or less, more preferably 2 to 20 μm. If the wax has a melting point of less than 40 ° C, the viscosity will be too small under extreme pressure (the surface pressure has risen considerably locally due to the pressure applied during molding), and the lubrication effect will not be sufficient, resulting in insufficient workability. If the temperature exceeds 120 ° C, the brazing property deteriorates, so the average particle size is 20 μm or less, the melting point
It is preferably 40 ° C or higher and 120 ° C or lower.

By using the brazing sheet manufactured as described above, good press working can be performed without applying a lubricant such as press oil during press molding. Then, in order to manufacture a heat exchanger using these molded products, these molded products are laminated, corrugated fins are arranged between the laminated members, and temporarily assembled by a jig.
Preheating is performed within a temperature range of 0 to 500 ° C for 1 hour, then flux is applied and dried, and then brazing is performed. The above preheating is to evaporate the wax and ensure the uniform wettability of the flux. If the temperature is lower than 200 ° C, the vaporization is insufficient and the wettability cannot be secured. Therefore, the range was limited to 200-500 ℃. Also, since heating for 1 hour or more is not economical, it is limited to within 1 hour.

The method of applying the flux may be a conventional method, such as a method of immersing the member in an aqueous solution in which the flux is dissolved, a method of applying the member by spraying, or the like.

[0018]

EXAMPLES The present invention will be specifically described below based on examples.

Example 1 An aluminum alloy ingot having the chemical composition shown in Table 1 was prepared by DC casting, and a brazing alloy was clad on both surfaces of the core alloy ingot so that the clad ratio on one side was 15%. Then, hot rolling, cold rolling and annealing were performed to prepare a brazing sheet having a plate thickness of 0.6 mm.

[0020]

[Table 1]

On the brazing sheet thus obtained, as shown in Table 2, organic lubricating particles were applied and dried to form a lubricating film, and then the formability was evaluated.

The lubricating particles are prepared by using commercially available powdered wax, water-dispersed wax and solvent-dispersed wax, and adding water or a solvent so as to obtain an appropriate particle diameter and concentration and pulverizing, stirring and mixing in a ball mill. It was adjusted. Upon mixing, a small amount of a commercially available dispersant or stabilizer was added as needed. The particle size was measured by observing the mixed liquid directly with an optical microscope and by a light scattering method.

The amount of wax deposited was measured by carbon count of fluorescent X-rays. The coating was performed on both sides simultaneously by the dip Ringer method and then dried with warm air.

The moldability was evaluated by the crack generation rate when 100 Drone cups shown in FIG. 1 were molded. The brazing sheet of the conventional example was coated with a lubricating oil for processing, but the brazing sheets of the examples of the present invention and the comparative examples were processed and evaluated without oiling.

The brazability was evaluated by assembling a test hollow structure (5) in which the cups produced in the moldability test were overlapped as shown in FIG. 2 and vacuum brazing was performed. The brazing conditions are a vacuum of 5 × 10 ^-5 Torr, a heating rate of 30 ° C /
After reaching 600 ° C. at min, it was held for 3 minutes. The evaluation was performed by the fillet forming condition of the cup mating surface, and the rate of occurrence of wax breakage for 100 tests was performed. Although the conventional material is degreased and washed before brazing, the invention and comparative examples were brazed without pretreatment. More workability,
The results of the brazability evaluation are summarized in Table 2.

[0026]

[Table 2]

As is clear from Table 2, according to the brazing sheet of the present invention, cracks do not occur during the forming process and almost no wax breakage occurs during brazing. On the other hand, the comparative brazing sheets No. 14 and No. 17 in which the amount of the organic lubricating particles adhered excessively had a high rate of wax breakage due to the large amount of wax remaining, and on the contrary, the comparative brazing sheets in which the amount adhered was too small No. 15 and No. 19 have good brazing properties but poor moldability. Claim 2
Comparative brazing sheets No. 13 and No. 18 that exceed the average particle size of the organic lubricating particles specified in 1 and the melting point of the wax are 40
The comparative brazing sheet No. 20 having a temperature of less than ℃ deteriorates the workability, while the comparative brazing sheet No. 16 having a melting point of the wax exceeding 120 ° C. has a significantly poor brazing property.

Example 2 An aluminum alloy ingot having the chemical composition shown in Table 3 was produced by DC casting, and a brazing alloy was clad on both sides of the core alloy ingot so that the clad rate on one side was 15%. , Hot rolling, cold rolling, annealing,
A 0.6 mm brazing sheet was prepared.

[0029]

[Table 3]

As shown in Table 4, the brazing sheet thus obtained was coated with organic lubricating particles and dried to form a lubricating film, and then the formability and brazing property were evaluated.

The lubricating particles were prepared in the same manner as in Example 1,
In addition, a small amount of a commercially available dispersant or stabilizer was added. Furthermore, the measurement of the particle size, the application of wax, and the measurement of the wax adhesion amount were performed in the same manner as in Example 1.

The moldability was evaluated by the crack generation rate when 100 Drone cups shown in FIG. 1 were molded. In the conventional example, lubricating oil for processing was applied, but in the examples of the present invention and the comparative examples, processing and evaluation were performed without applying oil.

To evaluate the brazability, a test hollow structure (5) was assembled by stacking the cups produced in the moldability test as shown in FIG. 2 and preheated under the preheating conditions shown in Table 4. Evaluation was performed by applying a flux after that (a part of which was not preheated) and then brazing. The brazing conditions were such that the temperature rising rate was 30 ° C / min and the temperature was maintained at 600 ° C for 10 minutes. Evaluation is based on the fillet formation on the cup mating surface.
The rate of occurrence of wax breakage for each test was performed. In the conventional example, degreasing and cleaning are performed before applying flux.
In the examples of the present invention and the comparative examples, preheating was performed without degreasing, flux was applied, and then brazing was performed. The evaluation results of the formability and brazing property are summarized in Table 4 together.

[0034]

[Table 4]

As is clear from Table 4, all the examples of the present invention exhibit excellent workability and brazing property. On the other hand, Comparative Example N exceeding the average particle size of the organic lubricating particles defined in claim 6
No. 13 and No. 18 were unable to secure sufficient processability due to wax falling off, and the melting point of the wax was too low. Comparative Example No. 22 also did not have sufficient processability, while the wax had a high melting point. In Comparative Example No. 16 which is too large, the wax cannot be sufficiently removed by preheating, and thus the brazing property is not sufficient. Further, in Comparative Examples No. 14 and No. 17, the workability is sufficient because the amount of wax deposited is excessive, but the amount of wax remaining during brazing is large and sufficient brazing properties are not obtained. Comparative Example No. 15
On the other hand, No. 19 has an insufficient wax adhesion amount, and conversely has insufficient workability. In Comparative Examples Nos. 20 and 21, the preheating temperature was too low and the preheating was not performed, so that the wax remained and sufficient brazing properties were not obtained.

[0036]

As described above, according to the present invention, a brazing sheet can be processed without applying a press oil, and after preheating, flux application and brazing are applied to reduce environmental pollution. Good brazing properties can be obtained without degreasing, which can be the cause, so that not only the productivity and quality stability of the Al heat exchanger manufactured by press molding and brazing process increase but also the environmental improvement effect. It can be expected to increase.

[Brief description of drawings]

FIG. 1 shows an example of a heat exchanger cup, (a)
Is a plan view and (b) is a sectional view.

FIG. 2 is a side sectional view showing a test hollow structure in which the cups of FIG. 1 are stacked.

FIG. 3 is a perspective view showing an example of a Delon cup type evaporator.

[Explanation of symbols]

 1 Sheet Member 2 Corrugated Fin 3 Cup with Heat Exchanger Exhaust Port 4 Exhaust Port 5 Hollow Structure for Testing 6 Cup without Exhaust Port 7 Exhaust Cylinder

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C10M 109/00 9159-4H C10N 20:00 A 20:06 Z 40:24 A (72) Inventor Hiroshi Kano 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Aluminum Co., Ltd. (72) Inventor Yoshito Inabayashi 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Aluminum Co., Ltd. (72) Inventor Nobuo Totsuka 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Pref., Technical Research Division, Kawasaki Steel Co., Ltd. (72) Masaki Mabuchi 1, Kawasaki-cho, Chuo-ku, Chiba, Chiba Pref. 72) Inventor Koichi Hashiguchi, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd.

Claims (7)

[Claims] 1. An adhering amount of organic lubricating particles of 5 to 1000 mg / m ^{2 on} one or both sides of a laminated material in which a skin material made of an Al—Si alloy is clad on one or both sides of a core material made of Al or an Al alloy. An aluminum alloy brazing sheet having excellent formability, characterized in that the lubricating layer is formed. 2. The organic lubricating particles have an average particle size of 20 μm.
The aluminum alloy brazing sheet according to claim 1, which is a wax having a melting point of 40 ° C. or higher and 120 ° C. or lower and having a melting point of 40 ° C. or higher and 120 ° C. or lower. 3. The aluminum alloy brazing sheet according to claim 2, wherein the organic lubricating particles have an average particle size of 2 μm or more. 4. An adhesion amount of organic lubricating particles is 5 to 1000 mg / m ^{2 on} one side or both sides of a laminated material in which a skin material made of an Al--Si alloy is clad on one side or both sides of a core material made of Al or Al alloy. The aluminum alloy brazing sheet formed by forming the lubricating layer of 1. is molded and combined with other members, then heated at a temperature of 200 to 500 ° C for less than 1 hour, then flux is applied and brazing is performed. And a method for manufacturing an aluminum heat exchanger. 5. A method for manufacturing an aluminum heat exchanger, which comprises molding the brazing sheet according to claim 4 and combining the brazing sheet with other members, and then brazing and heating in a vacuum. 6. The organic lubricating particles have an average particle size of 20 μm.
The method for producing an aluminum heat exchanger according to claim 4 or 5, which is a wax having a melting point of 40 ° C or higher and 120 ° C or lower. 7. The method for manufacturing an aluminum heat exchanger according to claim 6, wherein the organic lubricating particles have an average particle diameter of 2 μm or more.