JP3160099B2 - Heat exchanger manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger used, for example, as a radiator for an automobile, a condenser of an air conditioner, or an evaporator.

[0002]

BACKGROUND OF THE INVENTION Conventionally, a heat exchanger made of aluminum or an aluminum alloy (hereinafter referred to as an aluminum alloy) is composed of a brazing sheet clad with a brazing material to form tubes (tubes) and fins, and assembling them into a predetermined shape. And it is manufactured by brazing.

[0003] By the way, in an aluminum alloy heat exchanger constituted by using a brazing sheet, the entire surface is A
Since it is covered with a brazing material made of an l-Si alloy or the like,
For example, the molten brazing material may erode the base material, significantly reducing the strength of the fins and tubes and causing deformation. Therefore, a coating of a brazing composition obtained by mixing an Al-Si alloy powder with a binder resin that is more volatile than carbonized at the brazing temperature is applied to the surface of the tube, and the tube is subjected to heat treatment to perform brazing. A heat exchanger has been proposed.

[0004]

DISCLOSURE OF THE INVENTION Incidentally, the above-mentioned proposed technology is extremely excellent and has been praised as compared with the conventional heat exchanger technology, but sometimes has a problem in heat exchange efficiency. Sometimes it was recognized that there was. As a result of intensive research into this problem, application of the brazing composition paint to the tube surface has been performed after a long tube is cut into a required length. Because, the applied paint itself may have somewhat closed the opening at the end of the tube, and in this case the flow of the refrigerant itself may be reduced,
They came to the knowledge that there would be a problem with heat exchange efficiency.

[0005] The present invention has been achieved based on such findings, and an object of the present invention is to provide an excellent heat exchange efficiency.
Another object of the present invention is to provide a technology with high production efficiency. An object of the present invention is to provide an extruding step of extruding a tube, a cooling step of cooling the elongate tube obtained by the extruding step to 0 to 100 ° C., and an elongate tube after the cooling step. An application step in which a coating of a brazing composition including a metal exhibiting a sacrificial anode effect on the surface, an Al-Si alloy, and a binder resin is applied, and after the application step, a long tube is reduced to a predetermined length. This is achieved by a method for manufacturing a heat exchanger, comprising: a cutting step of cutting, and a brazing step of brazing and combining a tube and a fin of a predetermined length after the cutting step.

The coating of a brazing composition containing a metal exhibiting a sacrificial anode effect, an Al-Si alloy, and a binder resin, which is applied to the surface of the elongated tube after the cooling step, is made of Al-Si-Zn. It is preferably a coating of a brazing composition containing a system alloy powder and a binder resin, and more preferably a coating containing an Al-Si-Zn system alloy powder, a binder resin and a flux.

[0007] That is, a problem that has sometimes occurred is:
Because the application work of the brazing composition paint was performed on the tube after being cut into a predetermined length, the long tube, the long one obtained by the extrusion process It was reminded that it would be better to apply the coating to the tube itself, and by doing so, the above-mentioned problem was solved, and a heat exchanger excellent in heat exchange efficiency was obtained.

Further, when the brazing composition paint is applied to a long tube immediately after extrusion molding, a coating film of the brazing composition is not formed well, and the coating with the fins is not formed. The brazing condition was not good, and the research on this was pushed forward.As a result, there was no problem when the temperature at the time of application was low, so the application work of the brazing composition paint was carried out by the extrusion molding process. It is important that the obtained long tube is cooled, and the problem of the brazing property has been solved. For example, the tube after the extrusion molding process usually has a temperature of about 300 to 600 ° C., which is cooled with water, mist,
It may be cooled by an appropriate means such as air cooling, and the cooling temperature may be about 0 to 100 ° C., preferably about room temperature to about 60 ° C.

Further, if the operation of applying the brazing composition paint is carried out in a long state, the application operation itself can be performed efficiently, which is advantageous in terms of cost. Metal powder of the brazing composition used in the present invention, for example, Al-Si-
The average particle size of the Zn-based alloy powder is preferably 10 to 200 μm. That is, when the average particle size of the brazing composition is less than 10 μm, the surface area is extremely large, so that the amount of the flux used for removing the oxide film at the time of brazing increases, and when the binder resin is added, On the other hand, if the average particle size of the brazing composition is too large to exceed 200 μm, the application itself becomes difficult, and the joining operation itself becomes difficult. It will be difficult. Even more preferably, the average particle size is 1
The thickness is from 0 to 100 μm.

For example, Zn is contained in Z
This is because n has an electrochemically low characteristic, so that a sacrificial anode effect is exerted, and the fins and tubes have high corrosion resistance. As a binder resin, it is more volatile than decomposed and carbonized at a brazing temperature, and has a molecular weight of 1,000 to 100,000.
Any acrylic resin may be used, such as polybutyl acrylate.

The mixing ratio of the brazing metal powder and the binder resin is such that the weight ratio of the brazing metal powder / binder resin is 1000/1 to 1/1, more preferably 20/100.
/ 1 to 2/1. As the flux, for example, KF
-AlF _3, those fluoride-based, such as _{RbF-AlF 3, KCl-LiCl} -NaF, CaCl 2 -KCl-
ZnCl ₂ , NaCl-KCl-LiCl-LiF-Z
_{nCl 2, ZnCl 2 -NaF-NH} 4 but there is a chloride-based, such as Cl, other various things may be used also. Incidentally, a fluoride type is more preferable.

The viscosity of the composition at the time of application is 1
It is good to be in the range of 0 cP to 100 cP. This is because, in a state where the viscosity is 10 cP or less, the powder has a large flowability and does not adhere well, and when the viscosity is 100 cP or more, it is difficult to apply the powder uniformly on the surface. Means for applying the brazing composition include, but are not limited to, a spray method and a flow coater method. That is, any coating method can be used as long as it can be applied to a long object.

The thickness of the coating film is about 10 to 200 μm after drying.
m is preferable. As a heat treatment method for brazing, various means such as brazing in a vacuum atmosphere or an inert atmosphere can be appropriately employed. Hereinafter, the present invention will be described specifically with reference to examples.

[0014]

【Example】

[Example 1] Width 20 mm, thickness 2 m by hot extrusion means
m, and water is sprayed on the long aluminum tube in the form of a mist,
The surface temperature of the aluminum tube was set to 40 ° C.

Thereafter, an alcohol solution obtained by mixing an JIS4343 alloy containing 4 wt% of Zn with an alloy powder having an average particle size of 30 ± 15 μm and an acrylic resin is sprayed on a surface of a long aluminum tube by a spray method. Thickness applied and dried. Thereafter, the long aluminum tube is cut into a predetermined length, assembled with fins,
A fluoride flux was applied to the joint.

In a nitrogen gas atmosphere, 600
A heat treatment was performed at about 3 ° C. for about 3 minutes to perform brazing to obtain an aluminum alloy heat exchanger. Example 2 An aluminum alloy heat exchanger was obtained in the same manner as in Example 1, except that the surface temperature of the aluminum tube before coating was 20 ° C.

Example 3 20 m wide by hot extrusion means
m, extruding a 2 mm thick aluminum tube,
It was wound around an iron core to form a coil, and the coil surface temperature was set to 40 ° C. by natural cooling. Thereafter, the same procedure as in Example 1 was performed to obtain an aluminum alloy heat exchanger.

Comparative Example 1 An aluminum alloy heat exchanger was obtained in the same manner as in Example 1, except that the coating operation was performed immediately after hot extrusion (surface temperature was 450 ° C.). Comparative Example 2 An aluminum alloy heat exchanger was obtained in the same manner as in Example 1, except that the coating operation was performed after cutting a long aluminum tube into a predetermined length.

[0019]

[Characteristics] The characteristics of the heat exchangers obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were examined. The results are shown in Table 1. Table 1 Occlusion of the hole in the tube Bonding condition with the fin Workability Example 1 0/1000 Good Good Example 2 0/1000 Good Good Example 3 0/1000 Good Good Comparative Example 1 0/1000 Poor Good Comparative Example 2 100 / 1000 good bad

[0020]

According to the present invention, an inexpensive heat exchanger having good heat exchange efficiency, good joining condition between the fin and the tube, excellent workability, and high efficiency can be obtained.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B23K 1/00 330 B23K 1/20

Claims (3)

(57) [Claims] An extruding step of extruding a tube, and an elongate tube obtained by the extruding step.
A cooling step of cooling to 0 to 100 ° C., and after the cooling step, a coating of a brazing composition containing a metal exhibiting a sacrificial anode effect, an Al-Si alloy, and a binder resin is applied to the surface of the long tube. A cutting step of cutting a long tube into a predetermined length after the coating step, and a brazing step of brazing and combining a tube and a fin of a predetermined length after the cutting step. A method for manufacturing a heat exchanger, comprising: 2. A coating of a brazing composition comprising a metal exhibiting a sacrificial anode effect, an Al-Si alloy, and a binder resin, which is applied to the surface of the elongated tube after the cooling step, is made of Al-Si-Zn. The method for producing a heat exchanger according to claim 1, wherein the coating is a coating of a brazing composition containing a base alloy powder and a binder resin. 3. A coating of a brazing composition containing a metal exhibiting a sacrificial anode effect, an Al-Si alloy, and a binder resin, which is applied to the surface of the elongated tube after the cooling step, is made of Al-Si-Zn. The method for producing a heat exchanger according to claim 1, wherein the coating is a coating of a brazing composition containing a base alloy powder, a binder resin, and a flux.