JPS60255263A - Manufacture of lightweight and corrosion-resistant heat exchanger - Google Patents

Abstract

PURPOSE:To obtain a lightweight and corrosion-resistant heat exchanger by brazing an Al brazing foil to the surface of an Al extruded tube by using a noncorrosive flux, inserting corrugated fins between tubes bent in the shape of snake motion, and heating and joining them. CONSTITUTION:To the surface of an Al extruded tube 1 provided with plural partition walls 1a and holes 1b, Al brazing foil 3 whose elctrode potential is lower than that of the tube 1 and shows a sacrificial corrosion effect is brazed by using a noncorrosive flux 6. Subsequently, the tube 1 is bent in the shape of snake motion, and thereafter, corrugated fins 2 made of Al is inserted between adjacent tubes 1, both of them are heated to the melting temperature of the brazing foil 3, and the tube 1 and the fins 2 are joined through a brazing foil layer. In this regard, as for the flux 6, a fluoroaluminum acid potassium compound is used, and the thickness of the brazing foil 3 is set to 20-200mum. In this way, a lightweight and corrosion-resistant heat exchanger can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a method for manufacturing a light heat exchanger used in a vehicle-mounted air conditioner or the like.

[Prior Art] In the automobile industry, where improving fuel efficiency by reducing vehicle weight is an important technical issue, measures are being taken to increase the size of heat exchangers for on-board air conditioners 11. The general manufacturing method for this type of heat exchanger, such as a condenser or evaporator, is to first bend a multi-hole duplex for refrigerant flow extruded from lightweight metal such as aluminum or aluminum alloy into a serpentine shape to form the main body. to form;
In the gap between adjacent chews 1, do you apply solder to the surface of the tubes in advance? lli, W, wall thickness 0.16 ~
Insert a very thin aluminum alloy gate fin with a diameter of 0.18 mm, and fix it! This union U using 'i4
After fixing the structure, the entire structure is placed in a heating furnace and heated to the melting temperature of the brazing agent.
A method has been adopted in which the assembly is completed by combining the bulb and the fin. And as for the material of the fin, Dupu H size J
:Using an aluminum alloy with a strong tendency to oxidize (low electrode potential), the fins corrode before the fins under the corrosion-prone strips 1'1, so-called sacrificial!
There was a concern that the PF corrosion effect would be 11 tons.

If there is a hole in the cove, the function of the heat exchanger will be lost, but some wear and tear on the surface of the fins is not a big deal. By the way, the brazing agent that is applied to the surface of the fin in advance contains a large amount of silicon component as a melting heat depressant, and during brazing, this silicon component is mixed into the abrasive structure of the fin at high temperatures. to change the melting temperature of the fin itself to −tO)(I
As a result, the fins buckle or curve due to the pressure applied by the brazing IJ jig, which poses an obstacle to reducing the thickness of the fins.

On the other hand, from the perspective of corrosion prevention measures for the duplex, there are no fins at the bends of the duplex, and the damage caused by the fins as described above is a problem. Since Pl corrosion effects cannot be expected, it is necessary to take some kind of corrosion prevention measures for this part, such as preparing and installing a separate board for sacrificial corrosion, or applying a coating material that has sacrificial corrosion properties. The following method was considered, but it was impractical as it required a considerable amount of store-up (16 points).

As another tube corrosion prevention measure, a method has been devised in which the surface of the duplex is subjected to a dipping diffusion treatment, but this method requires an expense to dispose of the waste liquid from the treatment bath.

Furthermore, instead of applying the waxing agent for assembly to the extremely thin-walled fins, by cladding the duplex side, which is much thicker than the fins, with a brazing agent layer, 1)
The inventors of the present application have already attempted a method of avoiding the +A quality deterioration problem of heat exchangers due to the melting point lowering effect of the silicon component in the waxing agent as described above, but Unlike forming a wax layer, in the case of extrusion duplexing, when aluminum material clad with brazing agent is processed into a multi-hole tube shape, some of the brazing agent moves inside the holes of the tube. However, when soldering the duplex and fins, the soldering agent inside the hole melts, reducing the passage area of the hole. Generally, a highly corrosive common flux containing ZnCl2 as a component is used, which requires considerable effort for cleaning and removal.

[Object of the Invention] 5. The object of the present invention is to provide an improved method for manufacturing a heat exchanger with significantly improved pumice resistance and corrosion resistance.

[Structure of the Invention] The method for manufacturing the lightweight corrosion-resistant heat exchanger of the present invention includes extrusion processing using J.
: After forming an aluminum tube with a large number of holes and brazing an aluminum brazing foil having a greater ionization tendency than the dupe onto the surface of the dupe using non-corrosive flux, The tube is bent into a serpentine shape, a corrugate fin made of aluminum is inserted between adjacent duplexes, and the tube is heated to the melting temperature of the solder foil to connect the tube and the corrugate fin through the solder foil layer. The composition is to combine the two.

According to a preferred embodiment of the present invention, a potassium fluoroaluminate-based flux is used as the non-corrosive flux, and the thickness of the aluminum brazing foil is 20 to 20%.
200 μm, preferably 100 μm before and after, and made of aluminum] Ruge I ~ fins are 0
．． For plate thicknesses of 10mm or less.

[Efficacy of invention rJ! 1. The manufacturing method of the lightweight corrosion-resistant 111 heat exchanger described above 2 +14 31, 47 has the following effects.

b) In order to efficiently assemble the duplex as a flow path for the heat transfer medium and the fin for increasing the heat transfer surface, a layer of brazing agent is applied to the surface of the fin in advance. In this method, the brazing temperature exceeds the normal setting value in order to avoid the problem of components in the brazing agent migrating into the extremely thin fin material and causing buckling at the high temperature T of brazing IIY. In contrast, the method of the present invention uses a method in which a wax layer is applied in advance to the surface of a durable tube with a much thicker fin material. As a result, the thickness of the fins can be as thin as the lower limit of the normal design value, and the fins can be made lighter. By adding creativity to the brazing method, the following effects can be expected.

(1) By forming a waxing agent layer on the surface of the tube in advance, which has a greater tendency to ionize than the dielectric material, the waxing agent is formed into a foil shape, and then de-duped using non-corrosive bamboo flux. The brazing number is printed on the surface, and this brazing work is easy and reliable.The remaining flux has a non-corrosive effect and does not need to be removed at all. It is also possible to reuse the brazing with the fins in the process. Therefore this I
The trouble of applying flux to the I culm and the use of flux can also be omitted.

C) The wax foil applied to the duplex surface has a sacrificial corrosion function and is applied over the entire length of the tube, so it can be applied to the areas where corrosion is most likely to occur and where it covers and bends. Corrosion resistance can be greatly improved without any special post-processing.

2) The method of applying foil-shaped solder to the tube is different from, for example, the method of passing a duplex through molten solder.
A thicker solder layer can be formed, resulting in higher brazing strength, and a more evenly thick solder layer can be formed, minimizing the amount of brazing agent needed. can.

``Example'' Next, a method for manufacturing an eave fil corrosion-resistant VI heat exchanger of the present invention will be described based on an example shown in the drawings.

FIG. 1 is a perspective view of a heat exchanger for a refrigerating machine of an on-vehicle air conditioner manufactured by the manufacturing method of the present invention, and as seen in the perspective view of FIG. A plurality of partition walls 1a are provided inside along the direction to form a large number of holes 1b.
The main part of the heat exchanger is constructed by bending the flat duplex 1 which has been formed into a meandering shape once at a predetermined interval to form a rectangular panel shape as a whole.
Between the parallel parts of the plate 1, there is a very thin rugate fin 2 made of aluminum or aluminum alloy for increasing the heat transfer area.
is inserted, and the dupe 1 and the fins 2 are integrally brazed together by the bonding force of the molten portion of the solder foil 3 which has been previously attached to the surface of the dupe 1. At both open ends of the tube 10, there are pipe fittings 4 and 5 for connecting to the heat transfer medium piping.
has been done.

Next, the manufacturing method of the present invention will be explained step by step. First, a flat duplex 1 made of aluminum or aluminum alloy and having the above-described cross-sectional shape (see FIG. 2) is molded using an extrusion molding machine. This tube 1 is continuously supplied from the left to the right in FIG. A wax foil 3 rolled and pressed into a long thin plate shape approximately equal in width to J: is passed through a flux coating tank B filled with a 10% solution 6 of non-corrosive flux as a brazing aid. In addition to being pressed by a person, it is attached using a compression roller group C.

FIG. 4 shows a cross section of the tube immediately after the wax foil 3 has been applied by the roller group C.

10- The tube 1 with the wax foil 3 attached to both sides is then sent to the drying oven 1) to evaporate the moisture contained in the flux, and then to fix the wax foil 3 on the surface of the tube 1. The material is placed in a brazing furnace heated to 600-610°C. The inside of the furnace F is kept in a nitrogen gas atmosphere to prevent metal oxidation. The material of the brazing foil 3 is, for example, an aluminum alloy containing 10.0% I↑ element and 1.0% zinc, which has a greater tendency to ionize than the tube 1 (in other words, the electrode electrode 11 It's mean)
, select one that will reduce the sacrificial 1' + corrosion N1 effect on the tube 1.Also, the solder foil 30θ is good within the tested range of 20 to 20071 m; (Approximately 10 Izm was determined to be optimal in consideration of the strength of the solder joint with the fin 2, the corrosion effect on the tube 1, and the consumption of the solder.

Conventional fluxes include ZnCl2, NaCl, and C.
1. Types that contain LiF etc. have a strong corrosive effect on metals, and may cause residual filler after brazing.
There is a problem in that it requires a great deal of effort and expense to remove 1-x, and in the present invention, AlF2, 2^IFs, and K3 are used.
81 [Use a non-corrosive type of potassium fluoroaluminate consisting of 6 alone or a mixture thereof.

FIG. 5 shows a cross section of the tube 1 after the wax 3 has been brazed.

Tube 1 with wax foil 3 coated on the surface as described above
is then bent into a serpentine shape, and the fins 2 are removed to complete assembly as a heat exchanger. This tube 1
and fins 2 are heated for about 10 minutes in a nitrogen gas atmosphere at a humidity of 590 to 605°C. ■For the culm, wax foil 3 is attached to the surface of dupe 1 as described above. Since the flux used in the step remains, it can depend on its function, but 5% of the same type of flux remains.
It is more preferable to perform the solution application step beforehand. The thickness of fin 2 is the same as that of conventional fins, in which a layer of brazing agent is placed on the surface of the fin.
According to the method of
If the manufacturing method of the present invention is used, this kind of buckling phenomenon will hardly occur111, so even if a thin fin 2 is used, brazing is performed at 590 to 605°C at 11N and 10
It can withstand being strained under severe humidity conditions such as heating for minutes.

Therefore, when the thickness of the fin is varied in the range of 0.16 to 0.07 mm+, we investigated the thickness below which the buckling phenomenon starts to occur when soldering. Test I was conducted while comparing the manufacturing method of a heat exchanger and the manufacturing method of the present invention. Table 1 shows the 1st stroke data.

13- Table 1 Test results for fin brazing ○ No buckling is 0
．． Buckling definitely occurred when the fin thickness decreased to 12 mm or less, but when the manufacturing method of the present invention was used, the fin thickness was reduced to 0.
．． It was found that buckling occurred for the first time when the thickness decreased to 0.07 mIn or less, demonstrating that the manufacturing method of the present invention is greatly useful in turning the product into pumice.

Next, regarding the relationship between the manufacturing method of the heat exchanger and the corrosion resistance of the product, we conducted an evaluation test with @[1] on the bent portions of the tubes, which are most susceptible to corrosion. summarized in.

Table 2A Tube corrosion test results (present invention) 15- Table 2B Tube corrosion test results (conventional product)
The numbers in the component composition indicate the percentage revision.

In the test, three types of Chicove materials were used, and heat exchangers were made using the conventional manufacturing method and the manufacturing method of the present invention.
l) Corrosion test specified in 0201 (CASS test method)
I tried. As is clear from this table, products produced using the conventional method began to leak from the bent portions of the tube 300 hours after the start of dest, regardless of the material of the tube, whereas the product produced using the method of the present invention began to leak. According to Tess I~
No cold water or leakage was observed even after 700 hours had passed for any of the three materials tested, confirming their excellent corrosion resistance.

Although the above embodiment relates to a heat exchanger for an automatic internal air conditioner, it goes without saying that the present invention can also be applied to various heat exchangers having the same type of structure.

In addition, in the above-mentioned case, the wax foil 3 is applied to both the top and bottom sides of the tube 1, excluding both sides. However, as shown in the cross-sectional view of FIG. 6, it is also possible to provide the upper and lower two wax foils 3 over the entire circumference.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a heat exchanger manufactured by the manufacturing method of the present invention, Fig. 2 is a perspective view including a partial cross section of the bent shape of the tube, Fig. 3 is a schematic diagram of the process of the manufacturing method of the present invention, and Fig. 4 and FIG. 6 are cross-sectional views showing individual 1M embodiments of tubes coated with wax foil layers according to the manufacturing method of the present invention;
Figure 5 is a cross-sectional view of the tube after soldering the wax foil (=t tJ), and Table 1 shows the relationship between fin plate thickness and fin buckling when fins are soldered onto the tube. Related ↑ test data, Table 2 is test data on the relationship between the monthly rate of heat exchanger composition and tube corrosion.
Fin 3... Wax foil 6...:l] Corrosion flux solution A... Wax foil winding shaft B... Flux coating tank C... Roller group for pressing wax foil D... Drying oven
E... I am a furnace agent Kenji Ishiguro 18- ;1) Figure 1 Figure 5 Figure 2 Procedural amendment October 25, 1980 Commissioner of the Japan Patent Office 5-1, Indication of case 1988 patent Application No. 112233 2
, Title of the invention, Process for manufacturing a lightweight corrosion-resistant heat exchanger 3, Relationship with the case of the person making the amendment Patent applicant address 1-1 Showa-cho, Kariya-shi, Aichi Prefecture Name (4)
26) Representative of Nippondenso Co., Ltd. 1) Kengo (and 1 other person) 4. Agent 465 Phone: 052-773-24496;
For details to be amended 1. Name of the invention Method for manufacturing a lightweight corrosion-resistant 411 heat exchanger 2. Claims 1) An aluminum Chicove having a large number of holes is formed by extrusion processing, and the surface of the tube is coated from the Chicove. Brazing base aluminum brazing foil with electric potential II using non-corrosive flux IJ1. After that, bend the aluminum chicob into a serpentine shape and place aluminum 111 between adjacent chis. J] Insert the fins into the Lugay 1, heat the molten water 1131 of the wax target, and apply the fins to the Coop and the Lugay 1 through the solder foil layer. A method for manufacturing a lightweight corrosion-resistant heat exchanger having an f+ characteristic. 2) The non-corrosion 1 (l flux is a fluoroaluminium yield strength 1 shim type flux, and the eave eave corrosion resistance ↑1 heat exchanger according to claim 1). 3) @ The thickness of the aluminum brazing foil is 20 to 200 Iz.
Claim 1 If4 characterized in that m
Or the method for manufacturing a lightweight corrosion-resistant heat exchanger described in Section 2 3゜4)
[Made of aluminum] The plate thickness of the rugate fin is 0.10
A method for manufacturing a lightweight corrosion-resistant heat exchanger according to any one of claims 1 to 3, characterized in that the thickness is less than m1. 3. Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a method of manufacturing a heat exchanger that is excellent in lightweight and is used for air conditioners mounted on vehicles. [Prior Art] In the automatic mid-range vehicle W, where improving fuel efficiency by reducing vehicle weight by 1'+1 is an important technical issue, measures are being taken to reduce the weight of the heat exchanger for the vehicle air conditioner. The general manufacturing method for this type of heat exchanger, such as a condenser or evaporator, is as follows: 2- First, a multi-hole tube for refrigerant distribution made of lightweight metal such as aluminum or aluminum alloy is bent into a serpentine shape to form the main body. A lugate fin made of an extremely thin aluminum alloy with a wall thickness of 0.16 to 0.18 mm, whose surface is pre-coated with solder in the gap between adjacent chicoves. After inserting the wax and fixing this combined structure using a jig, the whole is placed in a heating furnace and heated to the melting temperature of the wax. The material used for the fins was an aluminum alloy with a lower electrode potential than the Chicove material, and under conditions where corrosion was more likely to occur, the fins would corrode earlier than the Chicove material. The fins were arranged so that a so-called sacrificial wing corrosion effect could be obtained.If a hole were formed in the fin, the function of the heat exchanger would be lost, but some wear and tear on the surface of the fin is not so important.By the way, The brazing material applied to the surface of the fin in advance contains a polycrystalline silicon component to lower the melting point. As a result, a phenomenon occurs in which the molten metal 1a of the fin itself is also lowered, so the twin is seated due to the pressure applied by the soldering jig.]
The ITI has become thicker, and this has been an obstacle to reducing the wall thickness of the fin. On the other hand, from the perspective of corrosion prevention measures for the tube, there are no fins at the bent portion of the tube, and the sacrificial corrosion effect of the fins as described above cannot be expected, so
It was necessary to take proper corrosion prevention measures, for example, methods such as preparing a separate board for sacrificial corrosion or applying a coating material with sacrificial corrosion properties were considered. However, it was poor in practical use in that it caused considerable hair loss. As another tube corrosion prevention measure, a method has been devised in which the tube surface is subjected to a zinc diffusion treatment, but this method requires expense in cleaning up the treatment bath waste. Furthermore, instead of attaching the brazing filler metal for assembly to the very thin-walled fins, by cladding the brazing filler metal layer on the tube side, which is much thicker than the fins, silicon in the filler metal as described above can be clad. The inventors of this application have already tried to avoid the problem of material deterioration of heat exchangers due to the effect of lowering the melting point of the components.

[Different from providing a brazing metal layer on the sheet H1, in the case of an extruded tube, when processing aluminum material clad with brazing material into a multi-hole tube shape, a part of the soldering material H is attached to the tube. When soldering the tube and fin together, the soldering material inside the hole melts and reduces the passage area of the hole. The flux used for this process is generally a highly corrosive common flux containing ZnCl2 as its main component, and therefore requires considerable effort to wash and remove. [Object of the Invention] An object of the present invention is to provide an improved method for manufacturing a heat exchanger with significantly improved light weight and corrosion resistance. [Configuration 1 of the Invention The method for manufacturing the eaves corrosion-resistant heat exchanger of the present invention involves forming an aluminum tube having a large number of holes by extrusion processing,
After brazing aluminum foil with a base electrode potential on the surface of the tube using non-corrosive bamboo flux, bend the aluminum tube in a serpentine shape and separate the adjacent tubes. An aluminum T1 Lugate fin is inserted between the tubes and the Lugate fins by heating to the melting temperature of the solder foil to bond the tube and the Lugate fins through the soldering foil layer. do. According to a preferred embodiment of the present invention, a potassium fluoroaluminate-based flux is used as the non-corrosive flux, and the thickness of the aluminum brazing foil is 20 to 20%.
The aluminum rugate fin has a thickness of 0.1 On+m or less. 6- "Effects of the Invention 1" - The method for manufacturing a lightweight corrosion-resistant heat exchanger having the configuration described above has the following effects. b) In order to efficiently assemble the tube with the tube as a flow path for the heat transfer medium and the fin to increase the heat transfer area, an adhesion layer of brazing metal is provided on the surface of the fin in advance. In the brazing method, the components of the brazing filler metal migrate into the core material of the fin, which is extremely thin, and in order to avoid the problem of buckling under high temperatures during brazing, the usual set m value is While we had no choice but to use thicker fin material,
In the method of the present invention, a brazing metal layer is applied in advance to the surface of the tube, which is much thicker and stronger than the fins, so the thickness of the fins is as thin as the lower limit of the normal design value. pumice formation is achieved. At that time, by adding creativity to the brazing method, the following effects can also be expected. (7) As a method of preparing a brazing material layer on the tube surface in advance, it is possible to prepare a brazing material layer on the tube surface.
ill! ': L brazing filler metal is formed into a foil shape and brazed to the surface of the cope without using non-corrosive flux.This brazing work is easy and reliable, and the remaining flux is removed from the non-corrosive flux. It has the effect that the corrosion effect is brought forward and it is completely unnecessary to remove it, and it is also possible to utilize the fin groove in the rear T culm (d'4-J'1ri' in the I culm). It is also possible to eliminate the trouble of flux application and the use of flux in the subsequent process. C) The wax foil applied to the tube surface has a sacrificial 1-1 corrosion function, and the entire length of B As a result, even the areas where corrosion is most likely to occur or where the cover is bent can be reliably treated without any special post-processing.
Corrosion resistance is greatly improved. 2) The method of applying foil-shaped solder to the tube is different from, for example, the method of passing the tube through molten solder.
Since a thicker brazing material layer can be formed, higher brazing results in higher assembly strength, and a more uniform thickness of the brazing material layer can be formed, minimizing the amount of brazing material used. I can do it. [Example 1] Next, a method for manufacturing an eave corrosion-resistant heat exchanger of the present invention will be explained based on an example shown in the drawings. Figure 1 shows an in-vehicle empty v! manufactured by the manufacturing method of the present invention. Im
FIG. 2 is a perspective view of a heat exchanger as a condenser for a refrigerator, and as seen in the perspective view of FIG. The main part of the heat exchanger, which has a rectangular panel shape as a whole, is constructed by bending the flat tubes 1 having the shapes 1b in a meandering manner at predetermined intervals. Alternatively, a very thin corrugated fin 2 made of aluminum alloy for increasing the heat transfer area is inserted, and the tube 1 and the fin 2 are formed by melting 1 of the solder foil 3 that has been previously attached to the surface of the tube 10.
They are integrally brazed together using opposing joining forces. Vibe joints 4 and 5 are brazed to both ends of the tube 10 for connection to heat transfer medium piping. Next, the manufacturing method of the present invention will be explained step by step. 1. First, a multi-hole flat tube 1 made of aluminum or aluminum alloy having the above-mentioned cross-sectional shape (see FIG. 2) is molded using an extrusion molding machine. This tube 1 is continuously supplied from the left side to the left side in FIG. , tube 1
A soldering foil 3 rolled and pressed into a long thin plate shape approximately equal to 11] is brazed in a flux coating tank B filled with a 10% solution 6 of non-corrosive Franks as a auxiliary agent.
It is passed through and attached using the compression roller group C. Figure 4 shows wax foil 3 applied by roller t+'C-C.
The cross section of the tube is shown immediately after the test. The tube 1 with the wax foil 3 attached to the bottom surface of the tube 1 is then sent to a drying oven to evaporate the moisture contained in the flux. The brazing, which is heated to 600-610°C, is passed through the furnace F. The inside of the furnace E is kept in a nitrogen gas atmosphere to prevent metal oxidation. As the material of the wax foil 3, silicon is used, for example. OW [%, 10W zinc
Like the aluminum alloy containing 1%, the electrode potential is less noble than Diko 11, and does it have a sacrificial corrosion effect on the tube 1? Select what you want to do. In addition, the thickness of the wax foil 3 is good within the tested range of 20 to 200/11;
Among them, a thickness of around 100 μm was determined to be optimal for brazing the fins 2 in consideration of strength, sacrificial corrosion effect on the tube 1, and consumption of the brazing material. The flux is conventional ZnCl2, NaCl, C
1. Type-b containing LiF etc. has a strong corrosive effect on metals, and brazing requires a great deal of effort and expense to remove residual flux after work.In the present invention, KAlF3, K281[5, ni3AIF
A non-corrosive type of potassium fluoroaluminate is used. Fig. 5 shows a cross section of the tube 1 after waxing the wax foil 3. The tube 1 has the wax foil 3 coated on its surface as described above.
is then bent into a meandering shape, and the fins 2 are attached to complete the assembly as a heat exchanger. The brazing process involves heating the tube 1 and the fins 2 in a nitrogen gas atmosphere at a temperature of 590 to 605°C for about 10 minutes. The flux used in the adhesion stage remains, so it can depend on its function, but 5 of the same type of flux
It is more preferable that the step of applying the % solution is performed beforehand. fin 2
According to the conventional method of providing an adhesion layer of brazing material on the fin surface, the thickness of
However, according to the manufacturing method of the present invention, this type of buckling phenomenon is almost impossible to occur. Even with the use of fins 2, the brazing can withstand severe drying conditions such as heating at 590 to 605° C. for 10 minutes during assembly. Therefore, when the wall thickness of the fin is varied in the range of 0.16 to 0.07 mm, the conventional brazing method is used to determine the thickness below which the buckling phenomenon begins to occur. A test was conducted to compare the manufacturing method of a heat exchanger with the manufacturing method of the present invention. Table 1 shows the test data. 13- Table 1 Fin brazing () Test results: O No buckling Buckling definitely occurred when the fin thickness decreased to 0.12u or less, but when the manufacturing method of the present invention was used, the fin thickness decreased to 0.
．． It was found that buckling occurred for the first time when the thickness decreased to 0.07 mm or less, and it was demonstrated that the manufacturing method of the present invention is greatly useful in reducing the weight of the product. Next, regarding the relationship between the manufacturing method of the heat exchanger and the corrosion resistance of the product, an evaluation test was conducted focusing on the bent portion of the tube where corrosion is most likely to occur. The results are summarized in Table 2 A1B. Table 2A Tube corrosion test results (invention) -15 = Table 2B Dupu's corrosion test book! ! (Conventional product) The component composition numbers in the table above indicate wt%.The 1° test used three types of tube materials, and produced heat exchangers using the conventional manufacturing method and the manufacturing method of the present invention. test method) was attempted. As is clear from this table, the product manufactured using the conventional method started to leak from the curved part of the tube 300 hours after the start of the test, regardless of the material of the tube, whereas the product of the present invention started leaking from the bent part of the tube. No refrigerant cracking was observed in any of the three materials tested using this manufacturing method, even after 700 hours, confirming its excellent corrosion resistance. Although the above-mentioned embodiment relates to a heat exchanger for an air conditioner installed in an automobile, it goes without saying that the present invention can also be applied to various heat exchangers having the same type of structure. In the above example, the wax foil 3 was applied to both the upper and lower surfaces of the duplex 1 except for both sides, but as seen in the cross-sectional view of FIG. It may be provided so as to open on the surface. In addition, in the above-mentioned example, as shown in Table 2A, the wax foil 3
By using an aluminum alloy containing 7n as the material for the fins 2, the electrode potential of the solder foil 3 and the fins 2 is lowered.
The electrode potentials of the wax foil 3 and the fins 2 may be lowered by using Sn instead of n. 4. Brief description of the drawings 17- Fig. 1 is a perspective view of a heat exchanger manufactured by the manufacturing method of the present invention, Fig. 2 is a perspective view including a partial cross section of the bent shape of Bucove, and Fig. 3 is a perspective view of a heat exchanger manufactured by the manufacturing method of the present invention. Figures 4 and 6 are cross-sectional views of separate embodiments of tubes coated with wax foil layers according to the manufacturing process of the invention;
FIG. 5 is a cross-sectional view of the duplex after the wax foil has been brazed. . In the diagram: 1... Flat dupe 2... Lugate fin 3... Brazed foil 6... Non-corrosive bamboo flux solution A... Waxed foil wound shaft B... Flux coating tank C.
...Roller group for pressing wax foil D...Drying oven E...
・Brazing is done by Kenji Ishiguro = 18-2 "Hiro: Nichi - iE i morning (method) % formula %] 1. Indication of incident Patent Application No. 112233 of 1988 2
, Name of the invention, Process for manufacturing light chain corrosion-resistant bamboo heat exchanger 3, Amendment 1, f1 Which relationship: 11 nights Applicant's address: 1-1 Showa-cho, Kariya-shi, Aichi Name (4)
26) II Hondenso Co., Ltd. 1 Representative Ministry 1) Ken I
(4. Agent 465 Phone: 052-773-244
96. Subject of amendment Column 7 for a brief explanation of the drawings in the Book of Ill. Contents of the amendment As shown in the attached sheet 1. Column for a brief explanation of the drawings, page 17, line 18 to page 18, line 4 [Figure 5 is a cross-sectional view of the duplex after brazing the wax foil, and Table 1 shows the fin plate thickness and fin buckling when attaching the fin to the duplex. Table 2 shows the test data for the relationship between heat exchanger configuration 4A1 and duplex corrosion.
[Fig. 7Y:゛Director of the Japan Patent Office 1, Indication of the matter PI 1982 Patent Application No. 112233 2, Title of the invention → 1￥I m M+ 1+1 ill <5 JA Instrument Iu PA3, Which ministerial case to amend? Related Patent Applicant Address 1-chome Showa-cho, Kariya-shi, Kanchi Prefecture [11] Name (
426) Nippondenso Co., Ltd. Representative To 1) Ken IY 4, Sototo 465 Tel: 052-773-241196
, Description subject to amendment 1, Name of the invention, Method for manufacturing a lightweight corrosion-resistant heat exchanger 2, Claims 1) An aluminum tube having a large number of holes is formed by extrusion processing, and the duplex is coated on the surface of the duplex. After brazing aluminum brazing foil with a more base electrode potential using a non-corrosive flux, the aluminum duplex was bent into a serpentine shape, an aluminum rugate fin was inserted between adjacent duplexes, and the A method for manufacturing a lightweight, corrosion-resistant heat exchanger, characterized in that the tube and the corrugated fin are joined via the wax foil layer by heating to the melting temperature of the wax foil. 2) The method for manufacturing a lightweight corrosion-resistant heat exchanger according to claim 1, wherein the non-corrosive flux is a potassium fluoroaluminate flux. 3) The thickness of the aluminum brazing foil is 20 to 200/1.
14) A method for manufacturing a lightweight corrosion-resistant heat exchanger according to claim 1 or 2, characterized in that the thickness of the aluminum fin is o, i
Claim 1 characterized in that it is less than or equal to omm.
A method for manufacturing a lightweight corrosion-resistant heat exchanger according to any one of items 1 to 3. 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method of manufacturing a heat exchanger that is excellent in light weight and is used in a vehicle-mounted air conditioner or the like. [Prior Art] In the automobile industry, where improving fuel efficiency by reducing vehicle weight is an important technical issue, measures are being taken to reduce the weight of heat exchangers for on-board air conditioners. The general manufacturing method for this type of heat exchanger, such as a condenser or evaporator, is as follows: 2- First, a multi-hole tube for refrigerant distribution made of lightweight metal such as aluminum or aluminum alloy is bent into a serpentine shape to form the main body. A very thin aluminum alloy lever with a wall thickness of 0.16 to 0.18 mm, the surface of which has been pre-coated with solder, is placed in the gap between adjacent levers 1. After inserting the I-fin and fixing this combined structure using the U1 jig, the entire structure is placed in a heating furnace and heated to the melting temperature of the wax to create a duplex and fin with one wax. Methods have been taken to complete the assembly. The material for the fins is Chicove material, aluminum with low electrode potential.
＼Alloy was used, and under conditions where corrosion is likely to occur, the fins were arranged in such a way that a so-called sacrificial corrosion effect was obtained, in which the fins corroded before the dupes. If there is a hole in the chicove, the function of the heat exchanger will be lost, but some wear and tear on the surface of the fins is not so important. By the way, the brazing filler metal that is preliminarily applied to the surface of the fins contains a large amount of silicon to lower the melting point.
At high temperatures, this silicon component migrates into the core of the fin, resulting in a phenomenon that lowers the melting temperature of the fin itself, so in the case of soldering, the fins tend to buckle due to the pressure applied to the jig. This is an obstacle to reducing the amount of meat on the fin. On the other hand, from the viewpoint of corrosion prevention measures for the duplex, there are no fins at the bent part of the duplex, and the sacrificial corrosion effect of the fins cannot be expected as in 41 above, so it is necessary to take some kind of corrosion prevention measures for this part. For example, methods such as preparing a separate container for sacrificial corrosion or applying a coating material with sacrificial corrosion properties have been considered.
It lacked practicality in that it was less than a 2Z store-up. As another Chicove corrosion protection lambda 1 measure, a method has been devised in which zinc diffusion treatment is not performed on the Teco-1 surface, but there is a problem in that it requires expense to clean up the treatment bath waste liquid. Furthermore, instead of applying the brazing filler metal for assembly to the very thin walled rugate fins, by cladding the fins with a layer of brazing filler metal on the much thicker duplex side of the fins, silicon in the filler metal as described above can be clad. The inventors of the present application have already attempted a method to avoid the problem of material deterioration in heat exchangers due to the effect of lowering the melting point of the components, but it is difficult to solve the problem of simple problems like fins! Unlike forming a filler metal layer on a flat sheet material, in the case of extruded edge cove, when aluminum material clad with filler metal is processed into a multi-hole tube shape, some of the filler metal fills the holes in the duplex. When soldering the tube and fin, the brazing material inside the hole melts and reduces the passage area of the hole. The flux used in this process is generally a highly corrosive common flux containing ZnCl2 as its main component, and therefore requires considerable effort to wash and remove. [Object of the Invention] The present invention provides an improved heat exchanger with significantly improved light weight and corrosion resistance! The purpose is to provide an IA manufacturing method. [Structure of the Invention] The manufacturing method of the lightweight corrosion-resistant 141 heat exchanger of the present invention is to form an aluminum FJ die plate with a large number of holes by extrusion processing, and to form an aluminum FJ die plate with a large number of holes on the surface of the dupe. After soldering aluminum foil with a low potential using a non-corrosive flux,
The aluminum tube is bent into a serpentine shape, an aluminum corrugated fin is inserted between the adjacent two tubes, and the tube is heated to the melting temperature of the wax foil to bond the duplex and the corrugated fins 1 to 1. The configuration is defined as joining through the solder foil layer. According to a preferred embodiment of the present invention, the non-corrosive bamboo flux is a fluleo[l aluminum uric acid potassium flux, and the aluminum brazing foil has a thickness of 2
The thickness is 0 to 200 μm, preferably around 100 μm, and the aluminum corrugated fin has a thickness of 0.110 mm or less. -〇- [Effects of the Invention] The method for manufacturing the eaves corrosion-resistant heat exchanger having the above configuration has the following effects. b) Duplicating the flow path of the heat transfer medium and brazing the fins to increase the heat transfer area will make assembly work more efficient.
In order to achieve this, a layer of brazing paste is pre-prepared on the surface of the fin, but the ingredients in the brazing metal migrate into the very thin core material of the fin, and the brazing process does not occur under the high temperatures of the time. In order to avoid the inconvenience of bending, it was necessary to use a fin material that is thicker than the normal design value, but in the method of the present invention, a fin material that is much thicker than the fin Since we used a method in which a layer of brazing material is applied in advance to the surface of a durable tube, the thickness of the fins can be as thin as 1/2 of the normal setting value, and the weight can be reduced. In this case, by adding creativity to the brazing method, the following effects can also be expected. In addition to forming a low-potential brazing filler metal into a foil shape, we used a non-corrosive ↑11 flux.
(Boo) - There is solder on the surface of the bulb, which makes the work easy and reliable, and there is no need to remove any remaining flux due to its non-corrosive properties. It is also possible to reuse it in the subsequent process of brazing with the fins.Therefore, it is possible to eliminate the trouble of flux application and the use of flux in this subsequent process. Ruro foil has a sacrificial corrosion function, and since it is applied over the entire length of the tube, it also protects the bent parts where corrosion is most likely to occur.
Reliably larger size without special post-processing like conventional methods]
Corrosion resistance is improved. 2) The method of applying foil-shaped solder to the tube allows for a thicker solder metal layer to be formed than, for example, the method of passing a duplex through molten solder, so that higher brazing is possible. Assembling speed is improved, a more even J9 brazing material layer is formed, and the amount of brazing material used can be kept to a minimum. [Example] Next, the manufacturing method of the light 84 corrosion resistant↑(I) heat exchanger of the present invention is shown in the figure and will be explained based on an example. FIG. 2 is a perspective view of a heat exchanger used as a heat exchanger for refrigerating machines, and as seen in the perspective view of FIG. The main part of the heat exchanger, which has a rectangular panel shape as a whole, is constructed by bending the flat tube 1 with holes 11) in a meandering manner at predetermined intervals. A rugate fin 2 made of aluminum or aluminum alloy 1 for increasing the heat transfer area is inserted between the tube 1 and the fin 2.
The tube 1 is integrally brazed and bonded by the melt bonding force of the solder foil 3 which has been applied to the surface of the tube 1 in advance. At both open ends of the tube 1 are pipe fittings 4 and 5 for connection to the heat transfer pipe.
is soldered. Next, the present invention! Step 81) 1. Form a multi-hole flat tube 1 made of aluminum or aluminum alloy with a cross-sectional shape (see Figure 2) using an extrusion molding machine. 1 is the third
The duplex 10 is continuously supplied from the left to the right in the figure, and on both surfaces of the duplex 10, an aluminum alloy brazing filler metal containing silicon and zinc is fed from the winding shaft A and is spread almost over the width of the tube 1. A wax foil 3 rolled and pressed into a thin plate of equal length is passed through a flux coating tank B filled with a 10% solution 6 of non-corrosive VL flux as a wax aging aid. It is attached using the pressing roller group C. FIG. 4 shows a cross section of the tube immediately after the wax foil 3 has been applied by the roller group C. The tube 1 with the wax foil 3 attached to both the top and bottom surfaces is then sent to a drying oven to evaporate the moisture contained in the flux. The solder foil heated to 600 to 610°C is passed through the ILJ furnace.The inside of the furnace E is kept in a nitrogen gas atmosphere to prevent oxidation of the metal.
For example, silicon can be used as a granule of 10. As with aluminum alloys containing 1% OW and 1.0 wt% zinc, the electrode potential is less noble than that of dupe 1, and does it have a sacrificial corrosion effect on dupe 1? Choose what you want to cover. In addition, the thickness of the brazing foil 3 is good within the tested range of 20 to 200 flIIl, but within that range, a thickness of around 10,071 m is a sacrificial value to the brazing [J strength, chip] 1 with the fin 2. 19-Corrosion effect and filler metal Hji 11'! It was judged to be optimal considering the quantity. Flux is conventional 7nC12, NaCl, KC
IC type products containing 1, 11, etc. have a strong corrosive effect on metals and require a great deal of effort and expense to remove residual flux after the soldering process. 1 (8lF2, K2AlF5,
Consisting of F6 alone or a mixture of these to K+8 1
1- Use a potassium fluoroaluminate-based non-corrosive tab. FIG. 5 shows a cross section of the duplex 1 after the wax foil 3 has been brazed. - The duplex 1 whose surface is covered with the wax foil 3 as described above is then bent into a serpentine shape, and the fins 2 are attached (pulled) to complete the assembly as a heat exchanger. 2 and 2 for about 10 minutes at a temperature of 590 = -605°C in an atmosphere of nitrogen gas.] In the process, wax foil 3 is placed on the surface of duplex 1 as described above. Since the flux used in the adhesion stage remains, it is preferable to pre-apply a 5% solution of the same type of flux, although it may depend on its IIJ+.The thickness of the fin 2 is different from that of the conventional fin According to the method of providing an adhesion layer of solder l on the surface, the buckling strength decreases at a minimum of 0.13
However, according to the cutting method of the present invention, this kind of buckling phenomenon almost never occurs.12- Therefore, even if thinner fins 2 are used, brazing
It can withstand exposure to severe temperature conditions such as heating at 590-605°C for 10 minutes during assembly. Therefore, when the wall thickness of the fin is varied in the range of 0.16 to 0.07 mm, the brazing method is used to determine the thickness below which the buckling phenomenon begins to occur. The manufacturing method of the exchanger and the manufacturing method of the present invention were compared and tested. Table 1 shows the test data. 13- Table 1 Examples of soldering fins (J test result Song ○ No buckling × Yes buckling) As is clear from this table, a brazing metal layer is not deposited on the surface of the fin in advance. Buckling definitely occurred when the fin wall thickness decreased to 0.12 mm or less, whereas in the case of the manufacturing method of the present invention, when the fin wall thickness decreased to 0.07 μ or less, 14-9 (It was found that buckling occurred for the first time, demonstrating that the manufacturing method of the present invention is greatly useful in reducing the weight of the product.) Next, we will discuss the relationship between the manufacturing method of heat exchangers and the corrosion resistance of the product. Tables 2 A and B summarize the results of an evaluation test focusing on the bent portion of the tube where corrosion is most likely to occur.Table 2A Tube corrosion test results (invention) Test results (conventional product) - 1 - The component composition numbers in the table indicate W1% J. 1 test was conducted using three types of tube materials 1, and the heat exchanger was Making, J I S D 02
The corrosion test (CASS test method) specified in 01 was attempted. -This table clearly shows that IX J: Sea urchin, products manufactured using the conventional method are tested at 3, regardless of the material of the tube.
After 00 hours, leakage started to occur from the bent part of the tube, whereas in the tube made by the manufacturing method of the present invention, there was no refrigerant leakage even after 700 hours with any of the three types of materials tested. No corrosion was observed, confirming the excellent corrosion resistance. The first embodiment relates to a heat exchanger for an air conditioner installed in an automobile, but the present invention can also be applied to various heat exchangers having the same type of structure.
Mamochiro/v. In addition, the wax foil 3 was applied to both sides of the sea urchin 10 except for the lower surfaces in the case described above. may be provided so as to be D on the entire circumferential surface. In addition, in the above-mentioned example, as shown in Table 2A, the wax foil 3
By using an aluminum alloy containing 7n as the material for the fins 2, the electrode potential of the solder foil 3 and the fins 2 is lowered.
It is also possible to lower the electrode potential of the wax foil 3 and the fins 2 by using Sn instead of n. 17-4. Brief description of the drawings Fig. 1 is a perspective view of a heat exchanger manufactured by the manufacturing method of the present invention, Fig. 2 is a perspective view including a partial cross section of a bent tube shape, and Fig. 3 is a perspective view of the heat exchanger manufactured by the manufacturing method of the present invention. 4 and 6 are cross-sectional views showing individual embodiments of tubes coated with a wax foil layer according to the manufacturing method of the invention, and FIG. FIG. 3 is a cross-sectional view of the tube after it has been attached. In the diagram: 1... Flat tube 2...] Lugate fin 3... Wax foil 6... No. 1 Corroded bamboo flux solution A... Wax foil-wrapped shaft B... Flux coating tank C
...Roller group for pressing wax foil D...Drying oven 1.
...Roui” Bannoro agent Kanji Ishiguro 18-

Claims (1)

[Claims] 1) An aluminum chicobe having a large number of holes is formed by extrusion processing, and a non-corrosive flux is applied to the surface of the aluminum brazing foil, which has a greater ionization tendency than the tube. After brazing, the aluminum tube is bent into a serpentine shape, aluminum corrugated fins are inserted between adjacent tubes, and the tube is heated to the melting temperature of the solder foil. A method for manufacturing a lightweight, corrosion-resistant heat exchanger, characterized in that the above-mentioned rugate fins and the above-mentioned rugate fins are joined together via the above-mentioned brazing foil layer. 2) The method for manufacturing a lightweight corrosion-resistant heat exchanger according to claim 1, wherein the non-corrosive flux is a potassium fluoroaluminate-based flux. 3) The thickness of the aluminum brazing foil is 20 to 200 μm.
A method for manufacturing a lightweight corrosion-resistant VL heat exchanger according to claim 1 or 2, characterized in that: 4) The plate thickness of the aluminum corrugated fin is 0.
A method for manufacturing a lightweight corrosion-resistant heat exchanger according to any one of claims 1 to 3, characterized in that the thickness is 10 mm or less.