JPS60255262A - Manufacture of lightweight and corrosion-resistant heat exchanger - Google Patents

Abstract

PURPOSE:To obtain a lightweight and corrosion-resistant heat exchanger by melting and plating an Al base brazing material to the surface of an Al extruding tube by using a noncorrrosive flux, inserting corrugated fins between tubes bent in the shape of a snake motion, and performing the brazing. CONSTITUTION:An Al tube 1 provided with plural partition walls 1a and holes 1b is extruded and formed, and an Al brazing material whose electrode potential is lower than that of the tube 1 is melted and plated to the surface of the tube 1 by using a noncorrosive flux 6. Subsequently, the tube 1 is bent in the shape of snake motion before or after the plating process, corrugated fins 2 made of Al are inserted between the tubes 1, both of them are heated to a melting temperature of the brazing material, and the tube 1 and the fins 2 are joined through a molten plating layer 3 of said brazing material. In this regard, as for the flux 6, a fluoro-aluminum acid potassium compound is used. In this way, a lightweight and corrosion-resistant heat exchanger can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a method for manufacturing a light weight heat exchanger used in a vehicle-mounted air conditioner or the like.

``Prior art'' In the automotive 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 the heat exchanger for this scale is to first form the main body by bending a multi-hole tube for refrigerant flow, which is extruded and formed from lightweight metal such as aluminum or aluminum alloy, into a serpentine shape.
The surface of the gap between adjacent tubes is coated with solder for brazing in advance, and the thickness N is 0.16~o, ia.
After inserting a very thin corrugated fin made of aluminum alloy with a diameter of around 1.2 mm, and fixing this combined structure using a jig, the whole was placed in a heating furnace and heated to the melting temperature of the brazing agent. J: Well, the tube and fin are bonded together by brazing! A method has been taken to complete the The material for the fins is aluminum alloy, which has a strong tendency to ionize the tube and has a low electrode potential.The fins will corrode before the tube under the corrosion-prone striations 11. So-called sacrifice 1! Efforts were made to obtain an i-enhancing effect. A hole in the tube will cause the heat exchanger to lose its function, but some wear and tear on the fin surface is not that important. By the way, the brazing agent applied to the surface of the fin in advance contains a large amount of silicon component as a melting point depressant. Move to
Since a phenomenon occurs that also lowers the melting temperature of the fin itself, the fin tends to buckle due to the pressure applied by the jig during brazing, which 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 above-mentioned corrosion effects due to the fins cannot be expected, so some kind of corrosion prevention measures should be taken at this part. For example, methods such as preparing a separate board for sacrificial corrosion or applying a coating material with sacrificial corrosion properties have been considered, but these methods are not practical as they would result in a considerable increase in cost. There was a lack of

Another tube corrosion prevention measure is to coat the tube surface with aluminum (
) A method of carrying out diffusion treatment has also been devised, but it has the disadvantage that it requires expense to clean up the waste liquid from the treatment bath.

Furthermore, instead of applying the waxing agent for assembly to the extremely thin corrugated fins, by cladding the waxing agent layer on the side of the tube, which is much thicker than the fins, the melting point of the silicon component in the waxing agent as mentioned above The inventor of the present invention and others have already attempted a method to avoid the problem of heat exchanger deterioration due to the descending effect, but unlike forming a solder layer on a simple flat sheet like a fin, extrusion processing In this case, when processing a sheet clad with brazing agent into a multi-hole tube shape, some of the brazing agent moves inside the holes of the tube, and the brazing between the tube and fins may sometimes be difficult. There were problems such as the waxing agent on the inside melting and reducing the passage area of the hole, and the flux used for this soldering was generally 7n.
Corrosion mainly composed of C12↑! Since the strong and common flux No. 1 was used, the cleaning and removal process required a considerable amount of effort.

[Object of the Invention] The present invention provides an improved heat exchanger with significantly improved weight and corrosion resistance! ! The purpose is to provide a way to send money.

[Structure of the Invention] The method for manufacturing the lightweight corrosion-resistant heat exchanger of the present invention involves forming an aluminum tube having a large number of holes by extrusion processing,
On the surface of the tube, an aluminum brazing agent having a greater ionization tendency than the tube 5 is hot-dipped using a non-corrosive flux, and the tube is bent into a serpentine shape either before or after the hot-dip coating. , insert aluminum [luger 1] fins between adjacent tubes, heat to the melting temperature of the brazing agent, and connect the duplex and the corrugated fins through the hot-dip plating layer of the brazing agent. The configuration 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.

Effect 1 of the Invention The method for manufacturing the lightweight corrosion-resistant heat exchanger having the above configuration has the following effects.

b) For the duplex as a flow path for the heat transfer medium and for the fins and solder pads to increase the heat transfer area, a layer of brazing agent is applied on the surface of the fins in advance in order to make assembly work more efficient. In the brazing method, the ingredients in the brazing agent migrate into the extremely thin fin material, which causes buckling under high temperatures during brazing. 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 tube that is much thicker and stronger than the fin. As a result, the thickness of the fins can be reduced to just the upper limit of the normal design value, and the weight can be reduced. At that time, by adding creativity to the brazing method, the following effects can also be obtained.

1) To prepare a layer of brazing agent on the tube surface in advance, a waxing agent with a higher ionization tendency than that of Dicove material is applied to the tube surface using a hot-dip plating method using non-corrosive flux. Since the remaining flux is not corrosive, there is no need to take the trouble of washing and removing it, and it is also possible to reuse it in the subsequent process of brazing the fins. . Therefore, the trouble of applying 7lux and the use of 7lux in the subsequent process can be omitted.

c) The plating layer of brazing agent applied to the tube surface has a sacrificial corrosion function and is applied over the entire curve of the U-tube, so even the curved parts where corrosion is most likely to occur can be treated without sacrificial corrosion. Corrosion resistance can be improved by a large amount without any special post-processing.

[Example] Next, a method for manufacturing a lightweight corrosion-resistant 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 as a condenser 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 to form a large number of holes 1b.
The main part of the heat exchanger is constructed by bending the flat tubes 1 formed with a meander shape at predetermined intervals to form a rectangular panel shape as a whole. [For increasing the heat transfer area of very thin aluminum alloy] Luge 1 to Fin 2
is inserted, and the tube 1 and the fin 2 are integrally bonded to each other by the melt-bonding force of the hot-dip plating layer 3, which is previously deposited on the surface of the Chicove 10.

Pipe joints 4 and 5 are brazed to both open ends of the tube 1 for connection to heat transfer medium piping.

Next, the manufacturing method of the present invention will be explained step by step. First, a flat tube 1 made of aluminum or aluminum alloy having the cross-sectional shape described above (see Fig. 2) is processed using an extrusion molding machine.
to form. This flat duplex 1 is shown in FIG.
It is continuously supplied from the left to the right, and is first fed into the flux coating device η1, where the surface is coated with a non-corrosive flux 6 as a brazing agent. The duplex 1 coated with flux 6 is then placed in a wax hot-dip plating device if? It is sent to B. The interior of plating equipment B is heated to a high temperature of 590 to 605°C by filling with nitrogen gas.
〇 - Prevent oxidation of waxing and deduping agents in the dry state. The plating method used in this case is to pass a duplex through a jet of molten solder. C is a flux injection nozzle, and D is a molten wax injection nozzle. Flux 6 is also used for conventional InCI2, NaCl, and Cl.
, rather than highly corrosive materials containing LiF, etc., A1 "4, K2 AIF, 3 Al [6 alone,
Alternatively, a non-corrosive potassium fluoroaluminate type material made of a mixture thereof is used. The brazing agent used here has a greater ionization tendency (lower electrode potential) than the IJ 13+ of BUUB 1, for example, silicon with a 10.
An aluminum alloy-based solder containing 0 wt% and i owt% of zinc is used.

FIG. 4 shows a cross section of the duplex 1 coated with a wax layer. The tube 1 whose surface is covered with the hot-dip plating layer 3 is then bent in a meandering manner at a predetermined interval to form the main body of the heat exchanger, the fins 2 are inserted into the tube gap, and the tube is pressed with a jig. 590-60
The assembly of the tube 1 and the fin 2 is completed by placing it in a heating furnace under a nitrogen gas atmosphere maintained at 5 DEG C. for about 10 minutes to melt the hot-dip plating layer 3. In the case of one culm, brazing between the duplex 1 and the fins 2 may depend on the function of the flux used in the step of attaching the hot-dip plating layer 3 to the surface of the tube 1, as described above. However, it is more preferable to pre-apply the T culm with a 5% solution of intercalated flux. According to the conventional method of providing an adhesion layer of brazing agent on the fin surface, the thickness of the fin 2 should be at least 0.12 mm due to the above-mentioned decrease in buckling strength caused by the silicon component in the brazing agent. However, according to the manufacturing method of the present invention, this type of buckling phenomenon is almost impossible, so
Even if thinner fins 2 are used, brazing can withstand exposure to severe humidity 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 - 0.07n+m, the conventional thermal The manufacturing method of the exchanger and the manufacturing method of the present invention were compared and tested. Table 1 is the dest data.

Table 1 Test results for fin brazing: O: No buckling: X: Buckling: As is clear from this table, a brazing layer is preliminarily applied to the surface of the fin. 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 mm or less, It was found that buckling occurred for the first time, and it was demonstrated 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, an evaluation test was conducted focusing on the curved portion of the chicove where corrosion is most likely to occur. The results are summarized in Tables A and B.

Table 2A Tube corrosion test results (present invention) 13- Table 2B Deupe corrosion test results (conventional product) The numbers for material compositions in the above table indicate correction percentages.

In the test, three types of tube materials were used, and heat exchangers were made using the conventional manufacturing method and the manufacturing method of the present invention.
The corrosion test (CASS test method) specified in 01 was attempted.

As is clear from this table, the product produced using the conventional method started to leak from the bent part of the tube 300 hours after the start of the test, regardless of the material of the duplex, whereas the product produced using the method of the present invention started to leak. No refrigerant leakage was detected even after 70 (l ff, ! i time) with any of the three types of materials tested, and rot I! 111 Bamboo's excellent quality I was able to recognize it.

The embodiments in section 10-c [) relate to a heat exchanger for an air conditioner mounted on an automobile, but it goes without saying that the present invention can be similarly applied to various heat exchangers having the same type of structure. In addition, in the embodiment described in Section 1,
However, after bending the dihove 1 into a serpentine shape, I melted the brazing agent 3 on the surface of the dihove 1 using non-corrosive flux. Hot-dip plating may also be used.

[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 dicove, and Fig. 3 is a schematic illustration of the first step of the manufacturing method of the present invention. Figure 4 is a cross-sectional view of a U-Tadzicove coated with one layer of wax, and Table 1 shows the 4 coats of wax applied to the fins on the tube! Table 2 shows test data on the relationship between the fin plate thickness and fin buckling when the heat exchanger is used, and Table 2 shows the test data on the relationship between the heat exchanger structural monthly rate and corrosion of the tube. In the figure 1... Di 1-B 2... Fin 3... Hot-dip plating layer... Non-corrosion 111 flux A...
Flux applicator B: Brazing dip plating equipment C
...Flux casting nozzle D...Melting wax injection nozzle agent Kenji Ishiguro 16- Figure 2 Procedure sum 3. i] Nisa 1 October 25, 1980 [I Mr. Commissioner of the Patent Office) False. 1. Indication of the incident 1982 Patent Application No. 112232 2
, Name of the invention, Process for manufacturing light, heavy, and corrosion-resistant + 1L heat exchanger 3, Person making the amendment, Past, etc. Special agreement applicant I Address: 1-1 Showa-cho, Kariya City, Aichi Prefecture Name (
426) Nippondenso Co., Ltd. Representative 1) Kengo (
(1 other person) 4. Sototo 465 Phone: 052-773-24496,
Complementary i [object I'll If iti all '1113j: and drawings, +?
'J O 6 A) Description 1, Name of the invention Method for manufacturing a light and heavy corrosion-resistant heat exchanger 2, Claims 1) An aluminum tube having a large number of holes is formed by extrusion processing, and the surface of the tube is An aluminum brazing material having a base electrode potential is hot-dipped using a non-corrosive flux from the Chicove, and either before or after the melted F2t Megging process, the Dicove is bent into a serpentine shape, and aluminum is placed between adjacent tubes. A lugate fin made by the solder metal is inserted and heated to the melting temperature of the brazing material to join the lugate fins to the soldering material through the molten plated layer of the solder material. Manufacturing method for light, heavy and corrosion resistant 1!1 heat exchanger. 2) A method for producing a lightweight corrosion-resistant heat exchanger according to claim 1 or 2, wherein the non-corrosive flux is potassium fluoroaluminate-based flux. 3. Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a method for manufacturing a heat exchanger with excellent pumice properties for use in vehicle-mounted air conditioners/drivers. [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 to first bend a multi-hole tube for refrigerant flow into a serpentine shape, which is extruded from light 1II metal such as aluminum or aluminum alloy, and then create a main body. formed 1
! , a wall thickness of 0.16 to 0, with solder for brazing C on the surface of the gap between adjacent duplexes in advance.
．． A very thin rugate fin made of aluminum alloy with a diameter of 18 mm or less is inserted, and this combined structure is fixed using a jig, and then placed in a heating furnace and heated to the melting temperature of the brazing filler metal. As a result, the method of completing the assembly of the dupe and fin by brazing has been changed. The material for the fins is an aluminum alloy, which has a more base electrode potential than the other Chicove materials, and under conditions where corrosion is more likely to occur, the fins corrode before the Chicoves, so-called 'l! ! It was arranged so that the corrosion effect was reduced by 1q. If there are holes in the fins, the function of the heat exchanger will be lost, but some wear and tear on the fin surfaces is not so important. By the way, the wax (A) that is preliminarily applied to the surface of the fins contains a large amount of silicon component to lower the melting point. As a result, a phenomenon occurs that also lowers the melting temperature of the fin itself.
The fins tend to buckle due to the pressing force applied to the J jig, and this has been 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 no corrosion effect can be expected, it is necessary to take some kind of corrosion prevention measures for this part, such as preparing and installing a sacrificial board separately or applying a sacrificial corrosion coating material. Although it was considered, it was impractical due to the considerable increase in cost. As another tube corrosion prevention measure, a method has been devised in which zinc diffusion treatment is applied to the duplex surface, but this method requires an additional expense in cleaning up the waste liquid from the treatment bath. Furthermore, instead of attaching the brazing filler metal for assembly to the extremely thin corrugated fins, by cladding the brazing filler metal layer on the duplex side, which is much thicker than the fins, the silicon content in the brazing filler metal is reduced as described above. The inventor of the present application and others have already tried to avoid the problem of material deterioration in heat exchangers due to the melting point lowering effect, but there is a difference between providing a brazing material layer on a simple flat sheet I such as a fin, and extrusion. Processing 4- In the case of a dupe, when processing the solder metal clad sheet 1 into a multi-hole tube shape, a part of the solder H moves inside the hole of the dupe, causing the solder to bond between the dupe and the fins. There was a problem that the brazing material inside the hole melted when the hole was drilled, reducing the passage area of the hole.
The flux used for this brazing is generally IrI [1! Since a common flux with strong IT properties was used, the cleaning and removal process required a considerable amount of effort. [Object of the Invention 1] An object of the present invention is to provide an improved method for manufacturing a heat exchanger with significantly improved pumice resistance and corrosion resistance. [Configuration 1 of the Invention The method for manufacturing the lightweight corrosion-resistant heat exchanger of the present invention involves forming an aluminum tube having a large number of holes by extrusion processing,
On the surface of the duplex, an aluminum brazing material having a base electrode potential is hot-dip plated on the tube using a non-corrosive flux, and the tube is bent into a serpentine shape either before or after the culm of the hot-dip plating, Made of aluminum between adjacent duplexes] Luge 1
3, comprising inserting fins and heating the tube to the melting temperature of the wax to join the tube and the fins through the molten plating layer of the wax; According to a preferred embodiment of the present invention, as the non-corrosive bamboo flux, full aluminum
Use 1 series flux. "Effect of the invention" The method for manufacturing the eave-suspended corrosion-resistant TII heat exchanger having the above configuration is as follows:
It produces the following effects. b) In order to efficiently assemble the tube, which serves as a flow path for the heat transfer medium, and the fin, which increases the heat transfer area, with a single piece of solder, a layer of wax is applied on the surface of the fin in advance. In this method, components in the filler metal migrate into the core material of the thin-walled fin, causing the appearance of buckling at high temperatures at t lt. In contrast, in the method of the present invention, a layer of brazing material is applied in advance to the surface of a tube that is much thicker and stronger than the fin. As a result, the thickness of the fins can be reduced to the lowest limit of the normal design value.In this case, by adding creativity to the brazing method,
The following effects can also be expected. (1) A brazing material layer is prepared on the surface of the tube in advance, and then a brazing material with a lower electrode potential than the dupe material is applied to the dupe surface using a hot-dip plating method using a non-corrosive flux. Since the residual flux is not corrosive, there is no need to take the trouble of cleaning and removing it, and brazing with the fins as a post-process can be reused in the process. It is. Therefore, the trouble of applying flux and the use of flux in the subsequent process can be omitted. c) The brazing filler metal plating layer applied to the duplex surface has a sacrificial corrosion function and is applied over the entire surface of the tube, so even the curved parts where corrosion is most likely to occur will be protected. There is no need to perform special post-processing as in the past.
This ensures that a wide corrosion-resistant VF is created. [Example 1] Next, a method for manufacturing a corrosion-resistant heat exchanger of the present invention will be explained based on an example shown in the drawings. FIG. 1 is a perspective view of a heat exchanger as a refrigerator for a vehicle air conditioner manufactured by the manufacturing method of the present invention, and the fluid flow shown in the perspective view of FIG. By bending the flat tube 1 in which a plurality of partition walls 1a and a large number of holes 11) are formed inside along the direction in a meandering manner at predetermined intervals, a rectangular panel shape is obtained as a whole. The main part of the heat exchanger is composed of a heat exchanger, and between the parallel parts of the flat tube 1 there is a very thin heat transfer area increasing river made of aluminum or aluminum alloy.
A fin 2 is inserted, and the tube 1 and the fin 2 are integrally brazed together by the bonding force of the molten part of the hot-dip plating layer 3, which is previously deposited on the surface of the tube 1. Pipe joints 4 and 5 are brazed to both open ends of the pipe 1 for connection to heat transfer medium piping. Next, the manufacturing method of the present invention will be explained step by step. First, a multi-hole flat tube 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 flat tube 1 is continuously supplied from the left to the right in FIG. is applied. The tube 1 coated with the flux 6 is then fed into a wax hot-dip plating apparatus B. The interior of the plating apparatus B is filled with nitrogen gas to prevent the brazing material and dupe material, which are at a high temperature of 590 to 605 DEG C., from being oxidized. The plating method used in this case is to pass a chicobe through a jet of molten wax. C is an injection nozzle that injects flux using high-pressure air, and D is a molten wax injection 14 device that pumps up molten wax using a built-in pump to form a jet of molten wax. Flux 6 also uses conventional 2nC12, NaC1,
Rather than a highly corrosive material containing KCI, liF, etc., a non-corrosive potassium fluoroaluminate-based material consisting of ^1[4, K2AlF5, K2AlF5 alone, or a mixture thereof is used. The brazing material used here is 100% lower than the tube October rate! I have a low potential, for example, 10.0wt% silicon and 1.0w zinc.
An aluminum alloy-based solder containing t% is used. FIG. 4 shows a cross section of the tube 1 coated with a wax plating layer. The tube 1 whose surface is covered with the hot-dip plating layer 3 is then bent in a meandering manner at a predetermined interval to form the main body of the heat exchanger, the fins 2 are inserted into the tube gap, and the tube is pressed with a jig. 590-605
The assembly of the tube 1 and the fins 2 is completed by exposing the tube 1 and the fin 2 to a heating furnace for about 10 minutes in a nitrogen 10 gas atmosphere maintained at a temperature of 10°C to avoid melting the hot-dip plating layer 3. In this brazing process between the chipcove 1 and the fins 2, the flux used in the step of attaching the hot-dip plating layer 3 to the surface of the chipcove 1 remains as described above, so it is possible to depend on its function. However, it is more preferable to pre-apply a 5% solution of the same type of flux. According to the conventional method of providing an adhesion layer of brazing filler metal on the fin surface, the wall thickness of the fin 2 needs to be kept at a minimum of 0.113 mm due to the aforementioned decrease in buckling strength due to the silicon component in the brazing filler metal. However, according to the manufacturing method of the present invention, this kind of buckling visual image is almost impossible to occur.
Even if a thinner fin 2 is used, it can withstand exposure to severe temperature conditions such as heating at 590 to 605°C for 10 minutes during brazing (assembly). Therefore, the thickness of the fin is reduced to 0. When the brazing thickness is varied in the range of 16 to 0.07 mm, the buckling phenomenon occurs. Test 1 was conducted while comparing the manufacturing method of the invention. Table 1 shows the test data. Table 1 Test results for fin brazing ○ No buckling , on the surface of the fin 12
- By depositing a soft wax material layer (in the conventional manufacturing method, buckling definitely occurred when the fin wall thickness decreased to 0.12111 m or less, but when applied to the manufacturing method of the present invention, teeth,
It was found that buckling only occurred when the fin wall thickness decreased to 0.07 mm or less, proving 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. Go to Table 2 Tube corrosion test results (invention) -13 = Table 2B Tube corrosion test results (conventional product)
The figure for the monthly interest rate composition shows W1%. The test used three types of Chicove materials, and made heat exchangers using the conventional manufacturing method and the manufacturing method of the present invention.
The corrosion test (CASS test method) specified in 01 was attempted. As is clear from this table, the products manufactured using the conventional method showed no signs of leakage after 300 hours from the start of the test (irrespective of the material of the tube) (while the products manufactured using the conventional method began to leak from the bent part of the tube, In the case of the product produced using the above method, no refrigerant leakage was observed even after 700 hours in any of the three types of materials tested, demonstrating its excellent corrosive properties. The example relates to a heat exchanger for an air conditioner installed in an automobile, but it goes without saying that the present invention can be similarly applied to various heat exchangers having the same type of structure. In the above embodiment, the brazing agent 3 is applied by hot-dip plating before bending the duplex 1 into a serpentine shape, but after bending the tube 1 into a serpentine shape, a non-corrosive flux is applied to the surface of the tube 1. The brazing agent 3 may be melted into 42. In addition, in the above-mentioned example, as shown in Table 2A, the brazing agent 3
By using an aluminum alloy containing 7n as the material for the fins 2, the electrode potential of the brazing filler metal 3 and the fins 2 is lowered.
The electrode potentials of the brazing material 3 and the fins 2 may be lowered by using 3n instead of n. 15-4. 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 a heat exchanger manufactured by the manufacturing method of the present invention. FIG. 4, which is a schematic illustration of the process of the invention manufacturing method, is a cross-sectional view of a tube coated with a brazing layer. In the diagram: 1...Tube 2...Fin 3...Hot-dip plating layer 6...Non-corrosive flux A...Flux coating equipment B...Brazing hot-dip plating equipment C.
...Flux injection nozzle D...Melting wax injection tA device agent Kenji Ishiguro B) Replace drawing Figure 3 with the attached one. 16- Procedure 1j11-: Mountain (H type) 1981-1 October 31st 2, Name of invention Process for manufacturing light and heavy corrosion-resistant heat exchanger 3, Person making amendment Case and conclusion Characteristics Applicant Address Aichi Prefecture 1-1 Showa-cho, Kariya City Name (4)
26) Nippondenso Co., Ltd. Representative: 1) Nori Ayame 4, Agent: 465 Telephone: 052-773-24496,
Column 1 of the brief explanation of the drawings in the document Ill that is the subject of the amendment. Figures 1 to 4 on page 16, line 3 are cross-sectional views of the tube on which the brazing layer has been applied, and Table 1 is Brazing the fins to the tube 1
Table 2 shows test data on the relationship between fin plate thickness and fin buckling, etc. when avoiding heat exchangers, and test data on the relationship between heat exchanger component monthly rate and tube corrosion. "Figure 4 is a cross-sectional view of a duplex with a brazing layer coated on it. 1. -2~ Tewa ■ Valley Ti, -iF 1. Indication of Incident Patent Application No. 1988 112232 No. 2
, Name of the invention, Process for manufacturing a lightweight corrosion-resistant heat exchanger 3, Relationship with the Ministry case for amendment Patent applicant address: 1-1-11 Showa-cho, Kariya-shi, Aichi Prefecture Name:
(426) Nippondenso Co., Ltd. Representative: 1) Kengo 4, Hito Dai 465 Phone: 052-773-244
96, Full text of the specification to be amended and drawings τ'・ 811 Benmin 8) Description 1, Name of the invention Method for manufacturing a lightweight corrosion-resistant heat exchanger 2, Claims 1) Extrusion processing involves a large number of An aluminum tube with a hole is formed, and the surface of the tube is hot-dip plated with an aluminum brazing filler metal whose electrode potential is lower than that of the duplex using non-corrosive flux. In either case, the tube is bent into a serpentine shape, an aluminum rugate fin is inserted between adjacent tubes, and the tube and the rugate fin are heated to the melting temperature of the wax H to separate the tube and the rugate fin. A method for manufacturing a lightweight, corrosion-resistant heat exchanger, characterized in that the heat exchangers are bonded via a hot-dip plating layer of the solder. 2) The method for manufacturing a lightweight corrosion-resistant heat exchanger according to claim 1 or 2, characterized in that the non-corrosive flux is a potassium fluoroaluminate flux. 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. ] Nden”J-
Or, the general manufacturing method for this type of heat exchanger such as an evaporator is to first form the main body by bending a multi-hole tube for refrigerant flow extruded from lightweight metal such as aluminum or aluminum alloy into a serpentine shape. let me,
The gap between adjacent tubes has a wall thickness of 0.16 to 0.18, with the surface coated with solder for brazing in advance.
After inserting a very thin aluminum alloy coal gate fin with a diameter of around 2 mm and fixing this combined structure using a jig, the whole is placed in a heating furnace and heated to the melting temperature of the brazing filler metal. Accordingly, a method has been adopted in which the assembly of the tube and fin is completed by brazing. The material for the fins is an aluminum alloy whose electrode potential is less noble than that of the tube material, so that under conditions where corrosion does not occur, the fins corrode before the tube, which is the so-called sacrificial corrosion effect. He was being healed. A hole in the tube will cause the heat exchanger to lose its function, but some wear and tear on the fin surface is not that important. By the way, the brazing material that is applied to the surface of the fin in advance contains a large amount of silicon component to lower the melting point, and this silicon component migrates into the core material of the fin at high temperatures during soldering. As a result, a phenomenon occurs that lowers the melting temperature of the fins themselves, and the fins tend to buckle due to the pressure applied by the brazing jig, which is an obstacle to reducing the thickness of the fins. = 3- On the other hand, from the perspective of corrosion prevention measures for the tube, there are no fins at the bends of the tube, and J
: Rusai! l! l Since no corrosion effect can be expected, this is the part! υIt is necessary to take appropriate corrosion prevention measures, such as preparing a separate board for sacrificial corrosion and removing it, or applying a coating material that has corrosion resistance.2-7 Which method? was considered, but it was impractical as it caused quite a bit of hair loss. As another tube corrosion prevention measure, a method has been devised in which the surface of the tube is subjected to a dipping diffusion treatment, but this method has the disadvantage of requiring an expense to clean up the waste liquid from the treatment bath. Instead of applying brazing filler metal for assembly to the fins with a thickness of just λ9, I decided to clad the brazing filler metal layer on the much thicker side of the fins. , a method to avoid the problem of material deterioration of the heat exchanger due to the melting point lowering effect of the silicon component in the brazing filler metal has already been attempted by the inventor of the present application. However, it is responsible for providing the solder IJIPi on a simple flat sheet 1-44 like a fin, and in the case of an extruded tube, when processing a sheet clad with brazing material into a multi-hole tube shape, the brazing material A part of the solder metal moved inside the hole of the tube, and when the tube and fin were brazed, the brazing material inside the hole melted, reducing the passage area of the hole. Furthermore, since the flux used for this brazing is generally a highly corrosive common flux containing 1nc12 as its main component, it requires considerable effort to wash and remove it. “Objective of the Invention 1 The present invention provides a method for improving corrosion resistance such as light ωtIl.
It is an object of the present invention to provide an improved method for manufacturing a heat exchanger. [Structure of the Invention] The manufacturing method of the eaves heat exchanger of the present invention is to form an aluminum tube with a large number of holes by extrusion processing, and to apply an electrode potential on the surface of the tube. A base aluminum brazing filler metal is hot-dip plated using a non-corrosive flux, and either before or after this hot-dip plating process, the tube is bent into a serpentine shape, and an aluminum corrugated plate or fin is interposed between adjacent tubes. The tube may be inserted into the soldering material, and heated to the melting temperature of the soldering material to join the tube and the fins through the melt-plated layer of the soldering material.A preferred embodiment of the present invention According to the above-mentioned non-corrosive flux, a fluoroaluminium-based flux is used. (a) Brazing material is applied to the surface of the fin in advance in order to efficiently assemble the former J. The method of providing an adhesion layer will prevent the components of the brazing filler metal from migrating into the thin core material of the fin, causing buckling at high temperatures during brazing. In order to avoid this, it was necessary to use a fin material with a thickness that exceeds the normal design value. Deposit the wax ttA layer 1! Because of this method, the thickness of the fins can be as thin as the lower limit of the normal design value, and the weight can be reduced. At that time, by adding creativity to the brazing method, the following effects can also be expected. 1) By preparing a brazing material layer on the tube surface in advance, a filler material with an electrode potential lower than that of Dicove was applied to the tube surface by hot-dip plating using a non-corrosive flux. Since the remaining flux is not corrosive, there is no need to go to the trouble of cleaning and removing it, and the brazing with the fins as the III culm can be reused in the process. It is. Therefore, the trouble of applying 7 lux to this tlI culm and the use of flux can be omitted. 7- C) The waxy plating layer that adheres to the tube surface has a sacrificial corrosion function, and is applied to the entire surface of the tube with D, so even the bent parts where corrosion is most likely to occur will be protected. , the corrosion resistance is reliably achieved without any special post-processing as in the prior art. [Example] Next, a method for manufacturing a lightweight corrosion-resistant 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 as a condenser 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 installed () inside and a large number of holes 1 are installed.
By bending the flat tube 1 formed with b in a serpentine shape at a predetermined interval, the main part of the heat exchanger having an overall rectangular panel shape is constructed.
- Between the parallel parts of the duplex 1, a very thin walled heat transfer area increasing rugate fin 2 made of aluminum or aluminum alloy is inserted, and the tube 1 and the fin 2 are connected to the duplex 1. The solder wire 1 is integrally bonded by the bonding force of the melted portion of the hot-dip plating layer 3, which is previously deposited on the surface. Pipe fittings 4 and 5 are soldered onto both open ends of the tube 1 for connection to heat transfer medium piping. Next, the manufacturing method of the present invention will be explained step by step. First, a multi-hole flat tube 1 made of aluminum or aluminum alloy having the above-described cross-sectional shape (see FIG. 2) is molded using an extrusion molding machine. This flat tube 1 is continuously supplied from the left to the right in FIG. is applied. The duplex 1 coated with the flux 6 is then sent to a wax hot-dip plating apparatus B. The inside of the plating apparatus B is filled with nitrogen gas to prevent the brazing material and tube material, which are at a high temperature of 590 to 605 degrees Celsius, from being oxidized. In this case, the plating method is based on passing a tube through a jet of molten solder. C is an injection nozzle that uses high-pressure air to spray flux, and D is a built-in pump that pumps up molten wax to form a jet of molten wax. It is a J4 stomach pack. Flux 6 also contains conventional 7nC12, Na1l, KCI, 1. i
It is not a highly corrosive material that contains ingredients such as 81.
[4. A non-corrosive type of potassium fluoroaluminate consisting of K2AlF5 and 3AIFB alone or a mixture thereof is used. The brazing material used here is an aluminum alloy-based brazing material whose electrode potential is less noble than that of the material of the tube 1, for example, containing 10.0 wt% silicon and 1.0 wt% curved lead. FIG. 4 shows a cross section of the duplex 1 to which a solder plating layer has been applied. The tube 1 whose surface is covered with the hot-dip plating layer 3 is then bent in a meandering manner at a predetermined interval to form the main body of the heat exchanger, the fins 2 are inserted into the tube gap, and the tube is pressed with a jig. 590-60
The assembly of the tube 1 and the fins 2 is completed by exposing the tube 1 and the fin 2 to a heating furnace under a nitrogen 10 gas atmosphere maintained at 5° C. for about 10 minutes to melt the hot-dip plating layer 3. In the tube 1 and fin 2, the flux used in the step of attaching the hot-dip plating layer 3 to the surface of the tube 1 remains in the culm, so it depends on its function. However, it is more preferable to pre-apply a 5% solution of the same type of flux. According to the conventional method of providing an adhesion layer of brazing filler metal on the fin surface, the thickness of the fin 2 must be at least 0.131 m due to the above-mentioned decrease in buckling strength caused by the silicon component in the brazing filler metal. However, according to the manufacturing method of the present invention, this type of buckling phenomenon almost never occurs, so even if thinner fins 2 are used, brazing can be performed at 590 mm during assembly. It can withstand exposure to severe humidity regulations such as heating at ~605°C for 10 minutes. Therefore, when the wall thickness of the fin was varied in the range of 0.16 to 0.07 mm, buckling during brazing t)11
- Tests were conducted comparing the conventional heat exchanger manufacturing method and the method No. 1 of the present invention to determine the thickness below which the phenomenon begins to occur. Table 1 shows the test data. Table 1 Fin wax UTJ test results ○ No buckling
- Let's be cool! With layer A applied, buckling definitely occurred when the fin thickness decreased to 0.12 mm or less in the conventional manufacturing method, but when layer J was applied to the manufacturing method of the present invention,
It was found that when the fin wall thickness decreased to 0.07 mm or less, the seat mark appeared for the first time, proving that the manufacturing method of the present invention is extremely 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 Tables A and B. 13- Table 2A Tube corrosion test results (invention) 14- The numbers in the material composition in the table above indicate wt%. Test t- used three types of tube materials, one using the conventional manufacturing method and the other according to the invention. A heat exchanger was made using the manufacturing method, and JIS
A corrosion test (CASS test method) specified in DO201 was attempted. As is clear from this table, products made using the conventional method were tested at the start of the test, regardless of the material of the tube.
After 00 hours, leakage began to occur at the bent part of the duplex, whereas in the case of the manufacturing method of the present invention, no leakage occurred after 700 hours for any of the three types of materials tested. However, no refrigerant leakage was observed, confirming its excellent corrosion resistance. It goes without saying that the present invention can be similarly applied to various heat exchangers, and in the above embodiment, the brazing agent 3 is applied by hot-dip plating before bending the Chicove 1 into a serpentine shape. , after bending the Chico 11 into a serpentine shape, the surface of the tube 10 may be hot-dip plated with a wax 113 using a non-corrosive flux. 3
By using an aluminum alloy containing 70 as the material for the fins 2, the electrode strength of the brazing filler metal 3 and the fins 2 is increased.
The electrode potential of the brazing material 3 and the fins 2 may be lowered by using 3n instead of n. 16-4. 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 the bent shape of the tube, and Fig. 3 is a perspective view of the heat exchanger manufactured by the manufacturing method of the present invention. Figure 4 is a cross-sectional view of a tube coated with a brazing layer. In the figure 1...Tube 2...Fin 3...Hot-dip plating layer 6...Non-corrosive flux A...Flux coating device B...Brazing hot-dip plating device C.
... Flux whispering nozzle D ... Molten wax injection installation agent Kenji Ishiguro B) Replace drawing No. 3 with the attached one. 17-

Claims (1)

[Scope of Claims] 1) An aluminum tube having a large number of holes is formed by extrusion processing, and an aluminum brazing agent having a greater ionization tendency than the tube is applied to the surface of the tube using a non-corrosive flux. The tube is bent into a serpentine shape either before or after the molten metal culm, an aluminum corrugated fin is inserted between adjacent tubes, and the tube is heated to the melting temperature of the brazing agent. A method for manufacturing a lightweight, corrosion-resistant heat exchanger, characterized in that the above-mentioned dicove and the above-mentioned rugate fin are combined via the hot-dip plating layer of the solder. 2) The method for producing a lightweight corrosion-resistant heat exchanger according to claim 1 or 2, wherein the non-corrosive flux is potassium fluoroaluminate-based flux.