JPH03155460A - Production of heat exchanger - Google Patents

Abstract

PURPOSE:To allow the execution of brazing of intricate shapes by interposing a mixture composed of metallic powder for brazing, binders consisting of acrylic resins or paraffinic wax and a flux to assembled joint parts and heating these parts. CONSTITUTION:After the respective parts of a heat exchanger are assembled, the compsn. for brazing contg. the metallic powder for brazing, at least one kind of the binders selected from the group of the thermoplastic acrylic resins which are carbonized at the brazing temp. and have high volatility or paraffinic wax and the flux for brazing is interposed in the joint parts and the joint parts are heated to produce the heat exchanger. The ratio of the binder/metallic powder for brazing is specified to 0.1/99 to 35/65 (by weight). The deposition of the compsn. for brazing is specified to 5 to 500g/m<2>. The joining of the heat exchanger having the intricate shapes and the many joining points is economically and satisfactorily executed.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method of manufacturing a heat exchanger, particularly a heat exchanger made of an aluminum alloy.

[Background of the invention]

When brazing parts made of aluminum or aluminum alloy (hereinafter simply referred to as aluminum alloy), if the aluminum alloy part has a simple shape and there are few joints, torch brazing using a brazing wire is sufficient. It is said that it can correspond to However, in cases where there are many joints and complex shapes, such as the case of joining tubes and fins in an aluminum alloy heat exchanger, it is difficult to deal with the above method, and in such cases, Possible brazing methods include vacuum brazing, brazing in an inert atmosphere, brazing using flux, and the like, using a plating sheet on which brazing material has been pasted together as a fin material, tube material, or header material. By the way, the brazing method using the above-mentioned brazing sheet is very effective in cases such as heat exchangers that have complex shapes and many joints, but the brazing material may be pasted in areas other than those required for brazing. It can be said that there is a lot of waste because
There is no doubt that it comes with something that costs more. Furthermore, since the entire surface is covered with brazing material,
It has also been found that there is a problem in that the wax erodes the base material during brazing heating, causing deformation of the base material. Furthermore, the plating sheet cannot be used as is for extruded pipes that cannot be laminated with brazing material.

[Disclosure of the invention]

From this point of view, the inventor of the present invention has conducted research and development on this issue, and has discovered that it is possible to use brazing filler metal powder as a means of providing brazing filler metal to complex-shaped joints without using a plating sheet. I thought it was effective. In this case, it has been realized that although it is not possible to uniformly supply and adhere the brazing powder to the joint portion using only the brazing powder, it is sufficient to use a mixture of the brazing powder and the resin binder. However, it has been found that this resin is not suitable for all types. That is, JP-A-56-1 obtained in the research process of the present invention.
In Japanese Patent No. 160869, fluoride flux powder and Zn powder having a particle size of substantially 1 to 200 μm are suspended in a liquid at a weight ratio of 4 to 9 to 6 to 1,
Additionally, carboxymethylcellulose is used as a binder.
, 5% by weight or less, and this suspension containing carboxymethylcellulose is applied to the surface of a bonding material made of an aluminum alloy, the bonding material is then dried, and then the bonding material is heated in an inert gas. Lower than the melting point, Zn
A brazing method for aluminum alloys has been proposed in which the brazing material is heated to a temperature higher than the melting point of the fluoride-based flux mentioned above to melt and join the aluminum alloys. When applied to brazing using powder as a brazing material, contrary to expectations, good brazing was not obtained. In addition, Japanese Patent Publication No. 58-31274 proposes a metal paste composition for brazing which contains metal powder, a water-soluble polymer compound having a carboxyl group in the side chain, and water as essential components, and the details thereof are as follows. In the explanation section, it is disclosed that the water-soluble polymer compound is a thermosetting acrylic resin (must not be a thermoplastic resin), and the metal powder is copper or nickel powder. , applying this technical idea to brazing using aluminum alloy powder such as Al-5i as a brazing material,
That is, when the thermosetting acrylic resin proposed in this technical concept was used as a resin binder, good brazing was not obtained, contrary to expectations. In other words, it has already been proposed to use resin as a binder when the brazing filler metal is a powder type. I tried applying it to brazing using it as a brazing material.
Possibly because the metal components of the brazing filler metals were significantly different, good brazing results could not be obtained with the techniques proposed so far. Therefore, the present inventor has determined that the brazing temperature is, for example, about 500
N650℃TEAR A It has been found that thermoplastic acrylic resins and paraffin waxes, which are more volatile than those that decompose and carbonize at brazing temperatures, are better as resin binders when the powder is used as brazing powder. In addition, when attempting to process materials coated with the above-mentioned brazing composition to form various parts, some resin binders used may peel off. It has also been found that it is sufficient to apply a chemical composition. The present invention has been achieved based on such knowledge,
It is an object of the present invention to provide a method for manufacturing a heat exchanger that allows easy brazing even when there are many joints or parts with complicated shapes, and has high manufacturing efficiency. An object of the present invention is to provide a method for manufacturing a heat exchanger equipped with fins and tubes by brazing using flux, in which after each part of the heat exchanger is assembled, metal powder for brazing is applied, Assembling the brazing composition containing at least one binder selected from the group of thermoplastic acrylic resins or paraffin waxes that are more volatile than carbonized at the brazing temperature and a brazing flux. This is achieved by a method for manufacturing a heat exchanger, which is characterized in that the heat exchanger is heated by interposing the heat exchanger in the joint portion. The ratio of binder/brazing metal powder is 0.1/9.
It is desirable that the ratio is 9.0 to 35/65 (weight ratio), and the amount of the brazing composition applied is 5 to 500 g/m2
It is desirable that ^1-Si alloy, ^! −
Metal powder for brazing, such as aluminum alloys with a lower melting point than the aluminum alloys to be joined, such as 51-Mg alloy, ^l-5i-Zn alloy, and ^1-Zn alloy, has an average particle size of about 10 to 200μ. − is desirable. Then, metal powder for brazing as described above and a binder such as a thermoplastic acrylic resin (for example, a homopolymer or copolymer of acrylic acid, acrylic ester, methacrylic acid, or methacrylic ester) or paraffin wax, Furthermore, KCl-LiC1 system, Zn
It is sufficient to mix and disperse a chloride-based flux such as C1□ type or a fluoride-based flux such as KF-^IF type in water or an organic solvent (preferably water), and then assemble this mixed and dispersed solution. (Stage before brazing heat exchanger) It is applied to the parts to be brazed by flowing down, coating, spraying, etc., and is used for specified brazing such as brazing in a vacuum atmosphere, an inert atmosphere, or an atmospheric atmosphere. All you have to do is braze it. Although the amount of flux added varies depending on the brazing atmosphere, the flux/brazing metal powder is 0.1/
It is sufficient if it is between 99.9 and 60/40.

[Example 1] ^1050 alloy was extruded to make tube 1, and fin 2 was obtained by corrugating ^7072 to this tube 1.
and the header 3 of the ^1050 extruded tube were combined as shown in FIG. Then, ^l-10 wt% Si alloy powder with an average particle size of 50 μ-, an acrylic acid ester homopolymer (thermoplastic) with a molecular weight of about 100,000, KF-^IF, and flux were mixed in a ratio of 95:5:5. (weight ratio), and this mixture 1
An aqueous solution prepared by adding 50 parts by weight of water to 00 parts by weight and dispersing the mixture is allowed to flow down to the joint between tube 1 and fin 2 and the joint between tube 1 and header 3, thereby reaching the desired position of tube 1. Apply the brazing composition. The amount of the brazing composition applied to the surface of the tube 1 was approximately 100 g/m'' (amount after drying). After drying, it was heated at 600°C x 5 w in a nitrogen gas atmosphere.
Brazing is performed under conditions of .

[Example 2] Example 1 was carried out in the same manner as in Example 1, except that a plating sheet made of ^3003 material clad with B^4045 on both sides was used as the header material.

[Example 31 In Example 1, the wax powder was ^l-5wt%Si-4
5wt% Zn alloy and flux RbF-^
The same procedure was performed except that the brazing temperature was IF and the brazing temperature was 550°C. [Example 4] In Example 3, C1 was used instead of RbF-^IF.
- Using LiC1, wax powder: binder: flux =
65=5:30 and 600℃×5+ in an atmospheric furnace
The same procedure was performed except that brazing was performed under *in conditions.

[Example 5] The amount of brazing composition in Example 1 was changed to approximately 30 g.
The same procedure was carried out with setting "/ra".

Example 6 The amount of brazing composition in Example 1 was increased to approximately 400%.
The same procedure was carried out with the length of 17 m''.

Example 7 The same procedure as in Example 2 was carried out except that paraffin wax was used as the binder.

[Comparative Example 1] A 0.1 mm plating sheet made by laminating B^4045 alloy on both sides of ^7072 alloy so that the thickness is 10% on each side was corrugated to form a fin, and a ^1050 alloy tube and a fin were made by corrugating. ^ B on both sides of 3003 material
Assemble a header made of plating sheet clad with ^4045 in the same manner as shown in Fig. 1, and attach KF-^I to this.
F. Apply flux and then 6 in nitrogen gas atmosphere.
Brazing was performed under the conditions of 00°C x 5ml.

[Comparative Example 2] The same procedure as in Example 1 was carried out except that carboxymethyl cellulose was used as the binder.

[Comparative Examples 3 to 7] The binder in Example 1 was vinyl chloride-based sugar bean (Comparative Example 3), epoxy resin (Comparative Example 4), polyethylene oxide (Comparative Example 5), and alkali salt of polyolefin (Comparative Example 6) , starch (Comparative Example 7) was used.

[Characteristics] The brazing properties of the heat exchangers obtained on each side, the degree of deformation of the fins, and the CASS test were conducted for 720 hours, and the maximum pitting depth of the tubes was investigated. The results are shown in Table 1.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an assembled state of a tube, a fin, and a header.

Claims (3)

[Claims] (1) A method for manufacturing a heat exchanger equipped with fins and tubes by brazing using flux, in which after each part of the heat exchanger is assembled, metal powder for brazing and brazing temperature are applied. A brazing composition containing at least one binder selected from the group of thermoplastic acrylic resin or paraffin wax, which is more volatile than carbonized, and a brazing flux is applied to the assembled joint. A method for manufacturing a heat exchanger, characterized by heating the heat exchanger. (2) In the method for manufacturing a heat exchanger according to claim 1, the ratio of binder/brazing metal powder is 0.
1/99.0 to 35/65 (weight ratio). (3) In the method for manufacturing a heat exchanger according to claim 1, the amount of the brazing composition deposited is 5 to 500 g/
Something that is m^2.