JPH03243295A - Brazing sheet and production of lamination type evaporator by using this sheet - Google Patents

Abstract

PURPOSE:To make improvement in brazing characteristic by specifying the contents of Mg in a core material and sheath material constituting the brazing sheet. CONSTITUTION:The contents of the Mg in the core material and sheath material constituting the brazing sheet which is constituted by forming the sheath material consisting of the Al alloy having the m. p. lower than the m. p. of the core material on at least one surface of the Al alloy core material and executing brazing in a nonoxidative atmosphere by using a non-corrosive fluoride flux are specified to <=0.03wt.%. The good brazed joint is obtd. with a small amt. of flux in this way and this method is particularly effective in the case of production of the evaporator of the lamination type having the joint part particularly in a heat exchanger.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a heat exchanger material and a method for producing the same, and in particular to an aluminum material that is effective for laminated type evaporators.
A brazing sheet made of a material and a manufacturing method, which has excellent brazing properties.

[Conventional technology]

The evaporator, which is a heat exchanger for car air conditioners, is a laminated type with a structure in which radiation fins (2) and plates (1) are laminated, and piping pipes (3) are provided on both sides of the plates, as shown in Figure 1. are becoming more common. This is because it has superior heat exchange performance compared to the serpentine type.

Brazeability is generally applied to the manufacture of such evaporators, but vacuum brazing, which does not use flux, has traditionally been used as the brazing method.

However, vacuum brazing has the disadvantage that its brazing properties are inferior to brazing properties that use flux, so there has been little progress in making materials thinner over the past ten years.

Conventionally, there has been a method of using chloride-based flux for flux brazing properties, but since the flux is corrosive, it was difficult to remove the flux inside the core with a laminated type evaporator. Brazeability was not adopted.

However, in recent years, a method of brazing in a non-oxidizing atmosphere using a non-corrosive fluoride flux has become popular. A feature of this method is that the flux is non-corrosive, so no post-treatment is required, making it ideal for brazing heat exchangers with internal joints, such as laminated evaporators.

Also, since it uses flux, it has excellent brazing properties.
The possibility of thinning parts is increasing.

[Problem to be solved by the invention]

A common non-corrosive fluoride flux is potassium fluoroaluminate complex.

However, the problem with this flux, and furthermore the problem with its brazing properties, is that the aluminum or aluminum alloy used for brazing is
If the l material contains Mg, the brazing properties will be poor. However, although it is possible to achieve some degree of brazing by increasing the amount of flux applied, it is also greatly affected by the shape of the joint at the joint.

There are particular problems especially when brazing a laminated type evaporator. That is, in the evaporator shown in Fig. 1, the material for the plate (1) is generally JI3.
3003 alloy (Al-0,05~0,2W1%Cu-
1.0~1.5%Mn) as the core material, and It on both sides.
A brazing sheet clad on both sides with a brazing material such as 34045 alloy (CAl-10w1%Si) is used.

In these alloys, Mg up to an upper limit of 0.05W1% (hereinafter simply referred to as %) is allowed as an impurity, but even this amount of Mg has an adverse effect on brazing properties. However, if you apply a large amount of flux as described above, there will be no problem with brazing, but since more flux residue remains inside the core, it falls off during use and flows into the air conditioner circuit, causing damage to the compressor and expansion. This is a problem because it has an adverse effect on the valve and the like.

[Means to solve the problem]

As a result of intensive study on the negative effect of Mg in Al material on brazing properties, we found that the cause of this is the reaction between flux components and Mg in Al material.
It has become clear that this is because lF4 changes into a compound such as KMgFl and loses its effect as a flux. The present invention was made based on the results of this study, and relates to a brazing sheet made of an Al material that improves brazing properties, and a method for manufacturing a laminated type Ninoku borator using the same.

That is, in the brazing sheet of the present invention, Al or A having a lower melting point than the core material is coated on at least one side of the Al or Al alloy core material.
In a brazing sheet formed of an alloy skin material and subjected to brazing in a non-oxidizing atmosphere using a non-corrosive fluoride flux, Mg content in the core material and skin material constituting the brazing sheet. It is characterized in that the amount is 0.03% or less.

Furthermore, the method for manufacturing the laminated type evaporator of the present invention includes Mg
Brazing in which an Al or Al alloy skin material with a Mg content of 0.03% or less and a melting point lower than that of the core material is formed on at least one side of an Al or Al alloy core material with a Mg content of 0.03% or less. After degreasing the sheet plate and corrugated fins, applying a suspension of fluoride flux and drying this, a laminated type evaporator is assembled, and then brazing is performed in a non-oxidizing atmosphere. It is.

[For production]

As mentioned earlier, Mg used as a material for Al material impairs brazing properties,
Mg in the core material of the brazing sheet also diffuses to the surface through the brazing material and reacts with the flux. In the case of a laminated type evaporator, brazing is the most difficult because the brazing sheets, which are plates and fins, are joined together, so they are twice as affected as other heat exchangers, so brazing is the most difficult.

By the way, as for the L and Al alloys constituting the brazing sheet, the skin material used as wax is generally It5434.
/'l-3i series such as CAl-7°5%Si) and It34045 alloy are mainly used as the core material, and It33003 alloy is mainly used as the core material. Note that the skin material is usually clad at a ratio of 3 to 20% of the total board thickness.

The reason why the Mg content is regulated to 0.03% or less in the present invention is that within this range there is almost no adverse effect on brazing properties. This limitation applies to both skin and core materials.

Next, manufacturing of the laminated type evaporator according to the present invention will be explained.

The brazing sheet of the present invention is molded into plates and corrugated fins of a predetermined shape using a press or the like, and then degreased.

Degreasing is usually carried out using an organic solvent such as trichloroethylene, trichloroethane or Freon, but etching using NaOH or a weak alkaline cleaner may also be used. Fluoride fluxes include KAl F4 and K2Al F.

・H20, K3kl F6, etc. alone or mixtures of potassium fluoroaluminate complexes, cesium fluoroaluminate complexes, mixtures of fluorides containing these as main components, and all other substances that are effective as fluxes. The above flux is used as a suspension in distilled water, ion-exchanged water, tap water, industrial water, an organic solvent, or the like as a solvent. The flux concentration varies depending on the brazing atmosphere, but it is generally good to be around 2-1Qv1%, and in this case, the amount of flux actually attached to the material is 1-5g/rrf.
If the amount of adhesion is less than this, it is difficult to braze.

The flux suspension is generally applied to the molded brazing sheet by spraying or dipping, but other methods may also be used. Drying after application is to evaporate the flux solvent, and is generally carried out in an oven at about 200°C, but other methods -
However, any method may be used as long as the solvent evaporates.

Next, these members are assembled into a laminated type evaporator, tightened with a jig, inserted into a non-oxidizing atmosphere, and heated to perform brazing. Nitrogen gas is usually used as the non-oxidizing atmosphere, but the dew point is -40°C or less and the oxygen concentration is 200p.
Any atmosphere may be used as long as an atmosphere of about pm or less can be obtained. The brazing heat may be maintained at a temperature higher than the melting temperature of the skin material and lower than the melting temperature of the core material for several minutes, but brazing is normally performed by maintaining it at 600° C. for 3 minutes.

The present invention is effective not only when a non-corrosive fluoride flux is used, but also when a chloride flux containing fluoride is used. It goes without saying that the manufacturing method of the present invention is suitable not only for laminated type evaporators but also for other heat exchanger materials.

〔Example〕

As shown in Table 1, JIS 3003 alloy or JIS
The Mg content of the core material made of 1050 alloy (Atl' 19.5% or more) and the skin material made of JIS 4045 alloy was varied, and this skin material was clad at a ratio of 10% to the total plate thickness to a thickness of 0. ．A brazing sheet of annealed material was produced using a normal manufacturing process. These brazing sheets were molded to produce a plate for the laminated type evaporator shown in FIG. 1, and 0.12 m thick fins made of JIS 3003 alloy were produced by corrugating.

These members were vapor degreased using freon and coated with flux. Flux is 70wt%KAl F<-3
1 to 10 wt% with 2 Al F 5-H20 to 0v1%
It was made into a suspension in concentrated ion-exchanged water and applied by spraying. After drying the water, these members were assembled and a laminated type evaporator shown in FIG. 1 was assembled using an assembly jig. This assembly should be kept at a dew point of -40°C or below.
It was inserted into a furnace in a nitrogen gas atmosphere with an oxygen concentration of 200 ppm or less, heated, and held at 600° C. for 3 minutes to perform brazing.

The brazability and amount of flux residue were examined for the evaporators with several parts of wax by external observation, and the pressure resistance strength was measured by a pressure test. These results are also listed in Table 1. In these results, the brazing property was evaluated as ○ if it was normal, and × if the fillet was extremely small or there was a break in the solder. Further, the amount of flux residue was evaluated as ○ for a small amount and × for a large amount.

As is clear from Table 1, the evaporators produced by the method Nα1-Nα6 of the present invention, which have a small amount of Mg in the core material and skin material, have good brazing properties and have a small amount of flux residue.
The overall evaluation was also good. On the other hand, comparative method section 7 where the Mg amount in either the core material or the skin material exceeds 0.03w1%
, magnetic 8 evaporators have poor brazing properties, and 1
In 1h9 and 11, even though the flux concentration was increased, the brazing performance was poor and leakage occurred in the pressure test. Also, comparative example Ntl
In the evaporator using IO1N1112, when the flux concentration was further increased, although the brazing property was good, there was a large amount of flux residue, and the overall evaluation was poor.

〔Effect of the invention〕

By setting the Mg content in the core material and skin material that make up the brazing sheet to 0.03v1% or less, brazing can be performed with a small amount of flux, especially for laminated type heat exchangers that have joints inside the heat exchanger. It has excellent industrial effects, such as being effective in manufacturing evaporators.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a laminated type evaporator. 1... Plate 2... Fin 3... Piping pipe

Claims (2)

[Claims] (1) An Al or Al alloy skin material having a lower melting point than the core material is formed on at least one side of an Al or Al alloy core material, and is brazed in a non-oxidizing atmosphere using a non-corrosive fluoride flux. A brazing sheet for use in a brazing sheet, characterized in that the Mg content in the core material and skin material constituting the brazing sheet is 0.03 wt% or less. (2) Al or A with Mg content of 0.03 wt% or less
l Mg content on at least one side of the alloy core material is 0.03
After degreasing the plates and corrugated fins made of brazing sheets formed with Al or Al alloy skin material having a melting point lower than that of the core material at wt% or less, a suspension of fluoride flux is applied and this is dried. A method for manufacturing a laminated type evaporator, which comprises assembling the laminated type evaporator and then brazing the laminated type evaporator in a non-oxidizing atmosphere.