JP2002267382A - Method of manufacturing brazing structure for aluminum heat exchanger - Google Patents

Abstract

(57) [Summary] [Problem] An Al heat exchanger brazing that uses both bare materials for fin material and tube material to perform brazing to reduce costs and reduce deviations from the current process. A method of manufacturing a structure is provided. SOLUTION: A fin material and a tube material made of a bare material of an Al-based material are assembled into a shape of a brazing structure, and a space to be close to a portion to be a joint between the fin material and the tube material and to be spatially close to the portion. The brazing material of a predetermined shape represented by a continuous elongated shape such as a wire is integrally incorporated at a position continuous with the brazing material, and the whole is heated to a brazing temperature to melt the brazing material, and the molten brazing material is melted. The fin material and the tube material are selectively supplied to a portion to be a joint, cooled to solidify the molten braze, and brazed to the fin material and the tube material.
The brazing material is integrated with the fin material or the tube material before combining the fin material and the tube material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum heat exchanger used for an automobile or the like, for example, a parallel flow type condenser or a serpen type evaporator, and more particularly, to a fin material and a tube material. And a method for producing a brazed structure of a heat exchanger by brazing.

[0002]

2. Description of the Related Art In general, heat exchangers for automobiles are often formed by combining fins and tubes, such as a parallel flow type condenser or a serpen type evaporator. In such a heat exchanger,
Generally, the refrigerant is circulated in the tube and the heat is radiated from the fins. Therefore, in order to avoid the occurrence of poor heat conduction due to the gap between the tube and the fin, the tube and the fin are sufficiently tightly joined. Brazing is a common joining method for aluminum heat exchangers.

Conventionally, in the manufacture of an aluminum heat exchanger as described above by brazing, one side or both sides of pure aluminum or an aluminum alloy (hereinafter, these are collectively referred to as an aluminum-based material). It is usual to use a so-called brazing sheet in which an Al-Si-based brazing material is clad. That is, a brazing sheet as described above (hereinafter, referred to as a “cladding material”) is used as one of a fin and a tube, and the other is a bare aluminum-based material (hereinafter, referred to as a “bare material”) that is not clad with a brazing material. These are assembled into a heat exchanger structure, and the assembly is charged into a heating furnace, and the whole is appropriately brazed at a temperature higher than the eutectic melting temperature of the brazing material and lower than the melting temperature of the core material. It is a common method to braze the tube and the fin by heating to a temperature. Here, if the whole assembly is heated to the above-mentioned brazing temperature in the heating furnace, the brazing material on the surface of the clad material is melted and becomes a fluid state, and the joint between the fin and the tube is formed by capillary action. The molten wax is supplied to a portion to be formed, and the molten wax solidifies at that portion to form a fillet, and the fin and the tube are joined by the fillet. In heating the brazing, it is usual to use a flux such as a fluoride or to heat in a vacuum without using a flux.

Recently, instead of using a clad material for one of the fin and the tube as described above, a method of using a bare material for both the fin material and the tube material has been strongly desired. The reason is that
There are three main reasons.

That is, the first reason is that the thickness of the fin material or the tube material can be reduced by using a bare material instead of the clad material. In recent years, there has been a strong demand for lighter and more compact heat exchangers for automobiles as one of the measures to address global environmental issues, and there is also a demand for lower cost by reducing the weight used for fin materials and tube materials. Therefore, there is a strong demand for a reduction in the thickness of the fin material and the tube material.

In recent years, various improvements have been made to reduce the thickness of the clad material as it is, for example, manufacturing methods such as a core material composition, a brazing material composition, a rolling ratio, and an annealing temperature. For example, in a brazing sheet fin material (cladding fin material) used for a capacitor,
It has become possible to reduce the thickness to about 0.1 mm. However, there is a limit to the reduction in the thickness of the clad fin material, which is considered to be far inferior to the thickness limit achievable with the bare fin material. The reason is that there is an unavoidable problem when using the clad fin material, that is, erosion, that is, the problem of erosion of the core material by the molten solder. That is, erosion is phenomenally
It is known as 1) erosion of the molten solder along the grain boundary of the core material, 2) solid solution of the core material component in the molten solder, and 3) solid-phase diffusion of the brazing material component into the core material, As a result of such erosion, the substantial thickness of the core material is reduced. Here, the high-temperature strength of the fin material is largely determined by the core material, so if the cladding fin material is severely eroded and the substantial thickness of the core material is extremely reduced, the fins will not be seated during brazing heating. It causes buckling and product failure. In recent years, as a demand for thinner fin materials, a fin plate thickness of about 50 μm has been required. It is considered that a reduction in the thickness of the fin material by using a bare material instead of the material is advantageous.

Next, as a second reason, there is a demand for reducing the amount of brazing material used. As the clad fin material as described above, it is generally necessary to use a double-sided clad material in which a brazing material is clad on both sides of the core material, and in a brazing structure using such a double-sided clad fin material, The brazing material on both sides is melted by heating, and the flow of the molten brazing due to the capillary phenomenon forms a fillet in a portion to be a joint, but among the brazing materials clad on both sides of the core material, the fillet is The brazing material contributing to the formation is at most about one half of the fin height of the clad on the joint side in contact with the tube. That is, in the clad fin material, a large amount of brazing material clad in a portion that does not contribute to fillet formation, that is, in a portion where no brazing material is required.

This point will be described with reference to FIG. 7. FIG. 7 shows a state in which a clad fin material 20 formed into a corrugated shape and a tube material 22 are combined and heated before brazing. In this case, the corrugated clad fin material 20 and the tube material 22 come into contact with the outer surface of the tube material 22 at the corrugated peak portion 20A of the clad fin material 20, and that portion becomes a joint by brazing heating. Here, of the brazing material 24 clad on the surface of the cladding fin material 20, the brazing material 24a near the outer surface (convex curved surface) of the corrugated peak 20A.
Contributes to the formation of a fillet in the joint portion, but the brazing material 24b near the inner surface (concave curved surface) of the corrugated peak portion 20A (this is indicated by hatching in FIG. 7)
Can hardly contribute to the formation of fillets in the joints, so that it can be said that about half of the clad brazing material was originally unnecessary. Therefore, it can be interpreted that the clad fin material is in principle added with the brazing material cost that should be unnecessary in principle. Therefore, it is desired to reduce the unnecessary cost by using a bare metal. Also, the buckling phenomenon caused by erosion as described above is usually seen not in the joint but in the straight part between them, but that part is the place where the originally unnecessary brazing material is clad as described above, Therefore, buckling often occurred due to erosion by a brazing material that was originally unnecessary.

A third reason is a difference in material manufacturing cost between the clad material and the bare material. In the case of the clad material, a sealing process for hot-pressing the core material and the brazing material is required in the manufacturing process, and the production yield is generally lower than that of the bare material due to variations in the clad ratio and the like. For this reason, the clad material is actually more expensive than the bare material, and there is a demand for cost reduction by using a bare material instead of the clad material.

[0010] By the way, as a typical example of a technique which has been realized so far, for example, the Nobel brazing method (for example, US Patent No. 5,100,048, US Patent No. 5,190,596, Sugihara) Atsushi: Light metal welding, 32 (1994), 435) is known. This method uses a mixed powder of a non-corrosive fluoride-based flux powder and a Si powder (Nocolok Si flux; Nocolok Si flux).
l Flux), which is actually a paste-like flux with an acrylic binder added. In the above-mentioned U.S. patent, an example in which the method is applied to a parallel flow type capacitor is introduced.A heat exchange structure is formed by a combination of bare aluminum and an aluminum alloy tube coated with Nokolocsil flux and a bare fin. Make up. In this case, in principle, Al in the tube material and S in the Nokolocsil flux are heated by brazing in a nitrogen atmosphere furnace.
i causes eutectic melting of a binary system of Al-Si and a multi-system of Al-Si-X, which acts as a filler and forms a fillet at the joint between the fin and the tube. The method allows the use of bare fin material.

[0011]

In applying the above-mentioned Nobel brazing method, there are the following problems.

That is, in the application process of Nocolok Syl flux, it is necessary to install new equipment which has not been used in the current general brazing method, and it is necessary to use a new special binder material. is necessary. According to the technique introduced in the above-mentioned U.S. Patent, first, nocoloc sill flux is suspended in alcohol to form a slurry, and an acrylic binder is added to the slurry to improve adhesion to the tube. The coating is performed by immersing the tube in a bath of the composition, followed by a process of drying and baking in a step of vertically pulling up the tube on which the flux is applied, and a Nocoloc sill flux-coated tube is obtained. can get. Many other techniques similar to the Nobel brazing method are introduced (for example, JP-A-2000-141083, JP-A-11-192582, JP-A-11-245080,
Japanese Patent Application Laid-Open No. H11-258991), but in any of these methods, various binder materials are used for the same purpose, that is, for the purpose of improving adhesion.
It is considered that a method using such a binder material requires equipment similar or similar to the Nobel brazing method.

As described above, with the Nobel brazing method or a technique similar thereto, it is necessary to install new equipment that is unnecessary with the current general brazing method, and to install new equipment that has not been used conventionally. There is a problem that the use of the binder material increases the cost of the final brazed product.

Therefore, as a method of replacing a clad material which is currently used as a fin material or a tube material with a bare material, the deviation from the current process is small and the raw material cost, the production cost, the capital investment and the like are included. There is a strong demand for the development of a method that reduces the total cost.

The present invention has been made in view of the above circumstances, and a bare material is used in place of a clad material used as a fin material or a tube material in a generally applied method of manufacturing a heat exchanger by a brazing method. As a method to be used, that is, as a bare method, the process is simple and there is little deviation from the current process, existing equipment can be used as a facility, and without using a special material such as a binder material. It is another object of the present invention to provide a brazing method with a low total cost, that is, a method of manufacturing a brazing structure for an aluminum heat exchanger.

[0016]

In order to solve the above-mentioned problems, according to the present invention, an assembly for a heat exchanger structure is basically formed by using bare materials for both a fin material and a tube material. In manufacturing, an Al-Si-based brazing material having a predetermined shape represented by a wire as a brazing supply source is integrally incorporated into the assembly, and the molten brazing at the time of brazing by the brazing material is originally used. The brazing is selectively supplied only to the portion that needs to be brazed, that is, only the portion that is to become a joint.

More specifically, a method of manufacturing a brazing structure for an aluminum heat exchanger according to the first aspect of the present invention is a method for manufacturing a brazing structure for a heat exchanger, wherein the fin material and the tube material are both made of an aluminum-based bare material. While being assembled into a body shape, A is located at a position close to and spatially continuous with the part to be a joint between the fin material and the tube material.
An assembly for a brazing structure is manufactured by integrally incorporating a brazing material of a predetermined shape based on l-Si, and the entire assembly is heated to a brazing temperature to melt the brazing material and to melt the brazing material. Is selectively supplied to the portion to be the joint, and then cooled to solidify the molten braze, thereby brazing and joining the fin material and the tube material.

The method for manufacturing a structure for an aluminum heat exchanger according to the present invention is most effective when the fin material is formed in a corrugated shape. Claim 2 stipulates this.

According to a second aspect of the present invention, in the method for manufacturing a brazing structure for an aluminum heat exchanger according to the first aspect, the fin material is formed in a corrugated shape in advance, and the corrugated fin material is An assembly for a brazing structure is assembled so that a top surface of a mountain portion contacts an outer surface of a tube material.

Further, in the method according to the second aspect of the present invention, wherein a corrugated fin material is used, a method of incorporating a brazing material having a predetermined shape into the fin material, There is a method in which a brazing material is integrated with the material in advance. Claims 3 and 4 define the former, and claims 5 and 6 define the latter.

That is, according to a third aspect of the present invention, in the method for manufacturing a brazing structure for an aluminum heat exchanger according to the second aspect, a groove is formed at a top of a peak of the corrugated fin material, Prior to assembling the assembly,
The brazing material is disposed in the groove, and in this state, the corrugated fin material and the tube material are assembled into a shape of a brazing structure for a heat exchanger.

According to a fourth aspect of the present invention, there is provided the method for manufacturing a brazing structure for an aluminum heat exchanger according to the third aspect, wherein the brazing material has a continuous elongated shape, and the continuous elongated shape is used. In disposing the brazing material having a shape in the groove of the corrugated fin material, the longitudinal direction of the brazing material is positioned so as to be orthogonal to the continuous direction of the ridges of the fin material, and the grooves of the plurality of ridges are formed. A common brazing material is arranged in the inside.

According to a fifth aspect of the present invention, in the method for manufacturing a brazing structure for an aluminum heat exchanger according to the second aspect, prior to assembling the assembly, a brazing material is previously adhered to the outer surface of the tube material. The present invention is characterized in that a corrugated fin material and a tube material are assembled into a shape of a brazing structure for a heat exchanger in this state by welding and integrating.

According to a sixth aspect of the present invention, there is provided a method for manufacturing a brazing structure for an aluminum heat exchanger according to the fifth aspect, wherein the brazing material has a continuous elongated shape, and the continuous elongated shape is used. In joining and integrating the brazing material of the shape to the outer surface of the tube material, one end face in the width direction of the tube material is attached so that the length direction of the brazing material is orthogonal to the continuous direction of the ridges of the corrugated fin material. It is characterized by being arranged.

Here, as the continuous long-shaped brazing material,
It is appropriate to use a wire with a constant cross section,
Claim 7 defines this.

According to a seventh aspect of the present invention, in the method for manufacturing a brazing structure for an aluminum heat exchanger according to the fourth or sixth aspect, the continuous elongated brazing material has a sectional shape and a sectional size. Are characterized by using a constant wire-shaped brazing material in the length direction.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for manufacturing a heat exchanger structure according to the present invention, the fin material and the tube material are:
Bare material of pure aluminum or aluminum alloy, that is, a material that is not clad with brazing material may be used, and its specific type and component composition are not particularly limited, but generally, a tube of a heat exchanger is conventionally used. Alternatively, it is desirable to use a material used as a bare material of a fin or a material used as a core material of a brazing sheet (cladding material) for a heat exchanger. For example, a pure aluminum alloy such as 1050 alloy, 1100 alloy, or the like, or It is desirable to use an Al-Mn alloy such as 3003 alloy and 3203 alloy. On the other hand, as the brazing material, an Al-Si based alloy known as a brazing material for aluminum, for example, a 4043 alloy, a 4343 alloy, or the like may be used.

Generally, the fin material is generally corrugated in advance and is formed in a corrugated shape (corrugated shape in cross section). Such a corrugated fin material is brazed to a tube material. In this case, it is normal to braze the top of the peak to the outer surface of the tube material,
Therefore, a portion where the top surface of the peak of the corrugated fin material and the outer surface of the tube material are in contact with each other is a joint portion. On the other hand, the tube material has only to form a hollow portion through which a temperature medium (usually a cooling medium) flows, and its specific shape does not matter, but when it is combined with a corrugated fin material, it is generally used. Is a flat shape that forms a long plate when the tube material is viewed two-dimensionally, and a corrugated fin material is applied to the flat surface (wide surface), and the ridge is continuous with the longitudinal direction of the tube material. It is normal to combine them so as to be perpendicular to the (internal medium distribution direction).

Furthermore, the shape of the brazing material is that, when assembling the assembly for the brazing structure, the brazing material is close to the joint portion between the fin material and the tube material and is spatially continuous with the portion. When the brazing material is melted by disposing it at a position, it may be shaped so as to be able to selectively supply molten brazing to a portion to be a joint, but when using a corrugated fin material as described above, It is desirable that the brazing material has a continuous long shape represented by a wire shape. Here, the continuous elongated brazing material is preferably such that the dimension and shape of the cross section orthogonal to the length direction are constant in the length direction, and thus the continuous length having a constant cross section in the length direction. The use of the brazing material in the form of a rule can ensure the uniformity of the size of the fillet formed by brazing, as will be described later. The cross-sectional shape of the continuous elongated brazing material is not particularly limited, and may be any cross-sectional shape such as, for example, a circle, an oval, a quadrangle, a flat quadrilateral, and a triangle. Can be obtained most easily and at low cost. Here, among the continuous elongated brazing materials, those having a small difference between the major axis and the minor axis of the cross section can be generally referred to as a wire shape. Further, the cross-sectional dimension of the continuous elongated brazing material may be appropriately determined according to the amount of the brazing material to be supplied.

In combining the fin material and the tube material as described above, in the present invention, an assembly for a brazing structure is prepared by integrally incorporating a brazing material having a predetermined shape. As a specific method for incorporating the brazing material, as described above, a method of integrating the brazing material with the fin material in advance before assembling, and a method of integrating the brazing material with the tube material in advance before assembling. There is a way.

As a method of using a corrugated fin material and previously integrating a brazing material with the fin material, as described in claim 3 and as shown in FIG. A groove 5 is formed at a position corresponding to the vicinity of the fin material width direction end at the top of the plurality of peaks 3, and a continuous long brazing material 7 typified by a wire is disposed in the groove 5. It is preferable that the brazing material 7 having a continuous elongated shape such as a wire shape is perpendicular to the direction A in which the plurality of ridges 3 of the fin material 1 are continuous (therefore, in the direction B in which the plurality of ridges 3 are arranged). (Parallel direction).

Here, the shape and size of the groove 5 formed at the top of each peak 3 of the corrugated fin material 1 are basically such that a continuous elongated brazing material can be fitted into the groove and play is large. It may be determined so that it is not too long. If the play of the brazing material with respect to the groove is too large, the brazing material may move and fall off from the fin material, which may hinder subsequent assembly work of the fin material and the tube material. Therefore, it is preferable to adjust the groove shape to the same as or slightly larger than the diameter of the brazing material so that the groove shape matches the cross-sectional shape of the brazing material and the gap between the brazing material and the brazing material is as small as possible.

The step of forming the grooves in the peaks of the corrugated fin material may be before or after corrugating the fin material (before assembling with the tube material), and is not particularly limited. Also, the method for forming the groove may be appropriately selected, but usually, in the long plate-like stage before processing the fin material into a corrugated shape,
Punching is performed at regular intervals in the length direction to form a large number of holes (through holes) whose center-to-center distance matches the pitch of the peaks of the corrugated fin material. It is desirable to carry out corrugation so as to be located at the top of the portion, and in this case, the above-mentioned holes are located at the top of each mountain portion and have a groove shape, and a groove for receiving a continuous elongated brazing material Will function as

As described above, by applying the method of forming the groove after corrugation by punching at the stage before corrugating the fin material, deformation of the fin material can be prevented, and application to the current line is easy. Becomes That is, in general, the fin material is extremely thin, having a thickness of 0.1 mm or less, and has low strength. Therefore, the fin material is easily deformed by processing. And the shape of the joint may vary, which may adversely affect brazing properties. On the other hand, such a problem can be avoided by punching a flat fin material before corrugating. Also, the punching process before corrugating can be easily adopted as a pre-process of the process by the current corrugating machine, and it is not necessary to change the equipment from the existing equipment.

On the other hand, the position where the groove is formed in the peak portion of the corrugated fin material is a position near the end in the width direction of the fin material, specifically, the end position of the louver generally formed on the plate surface of the fin material. It is preferable to set an intermediate position between the end positions in the fin material width direction. This is for the following reasons. That is, in general, the fins of the heat exchanger are generally subjected to so-called louver processing for cutting the plate surface into a louver shape in order to improve the heat exchange efficiency. It is desirable to avoid such a louver processing part. Also, if a groove is formed near one end in the width direction of the fin material and the brazing material is arranged in the groove, the brazing material itself is inevitably near one end in the width direction of the fin material. However, if the brazing material is arranged in this way, during the heating for brazing, the assembly for the brazing structure is moved to the side where the brazing material is arranged in the width direction of the fin material. Arranging so that the end is located upward and the opposite widthwise end is located downward (so that the direction in which the ridges of the fin material are continuous is vertical) can prevent the molten solder from flowing into the joint. This is advantageous in terms of uniform supply.

This point will be described in more detail.
Generally, the flow behavior of the molten solder during brazing is affected by the force of sucking the molten solder into the gap between the fin and the tube by capillary action and the force of the downward dripping by gravity due to the capillary action of the former. Although it has been confirmed that the molten solder can be raised to a height of about 20 mm only by the suction force alone, in practice, the flow behavior of the molten wax differs depending on the viscosity of the molten wax and the shape of the joint. In order to stably supply the molten solder to the joint portion stably, it is desirable to utilize not only the suction force due to the capillary action but also the gravity effect. Then, as described above, a groove is formed near the width direction end of the fin material, and the brazing material is arranged in that portion,
In addition, if heating is performed for brazing by arranging the part so that it is located above, the flow-down effect due to gravity acts in addition to the capillary phenomenon on the molten solder, and it is uniform and stable over the entire length of the joint part To supply molten solder.

Next, before assembling the brazing structure assembly, the brazing material is integrated with the tube material in advance, and then the tube material is integrated with the corrugated fin material to form the brazing structure assembly. A method for creating the image will be described.

As a method of previously integrating the brazing material into the tube material, as described in claim 5, and as shown in FIG.
A method in which the brazing material 7 is integrated on the outer surface of the brazing material 7 is applied. As the brazing material 7, a continuous elongated material such as a wire is used in the same manner as described above. It is preferable to arrange the tube member 9 at the center of one end surface 9A in the width direction along the length direction.

Here, for example, apatite cement or the like may be used as an adhesive for bonding the brazing material to the tube material. In the case of welding, laser welding, electron beam welding, or the like may be used as a welding method. it can. In the case of the above-mentioned method using an adhesive, it is necessary to use an adhesive capable of withstanding the brazing temperature, but in practice, the brazing material is placed at a predetermined joining position until the brazing starts melting and flowing. It is sufficient if it stays. On the other hand, of the latter welding methods, laser welding enables local rapid heating and cooling, and therefore, according to laser welding, only the vicinity of the contact interface between the brazing material and the tube material is instantaneously and locally. It becomes possible to join and integrate the brazing material into the tube by welding. However, since laser welding requires high equipment costs, a method using an adhesive is sufficient for practical use.

The joining position of the continuous long brazing material such as a wire to the tube material is preferably at the end face in the width direction of the tube material as described above. This is because it is preferable to form the groove near one end in the width direction of the fin material when a continuous long brazing material such as a wire is arranged in the groove of the fin material as described above. For the same reason. That is, a continuous elongated brazing material is arranged on one end face in the width direction of the tube material and combined with the fin material, and when the obtained brazing structure assembly is heated by brazing, the side on which the brazing material is located is If the assembly is arranged above and heated, the molten solder flows down not only by the force of the capillary action but also by the effect of gravity, and the molten solder can be supplied uniformly to the entire joint portion. It is.

Here, as shown in FIG. 3, when only one continuous long brazing material 7 such as a wire is arranged on one end face 9A in the width direction of the tube material 9, one of the brazing materials 7 is used. It is preferable to dispose the brazing material at the center of the end face (the center in the thickness direction of the tube material). That is, since the joint portion between the tube material and the fin material is located on both sides in the thickness direction with respect to one tube material, when the brazing material is joined to the end surface in the width direction of the tube material, the brazing temperature is increased. In this case, it is necessary for the molten brazing filler metal to flow from the end face in the width direction of the tube material to both sides in the thickness direction. Therefore, in order to uniformly supply the molten brazing material to the joints on both sides in the thickness direction of the tube material, the brazing material before melting needs to be positioned at the center position in the tube material thickness direction at the widthwise end surface of the tube material.

When a continuous elongated brazing material such as a wire is arranged on one end face in the width direction of the tube material, two brazing materials may be arranged and joined in parallel on one end face. . In this case, according to the thickness of the tube material and the long diameter of the continuous elongated brazing material, the two brazing materials may be arranged and joined at positions symmetrical with respect to the center in the thickness direction of the tube material. In this way, one brazing material serves as a supply source of the molten brazing material to one side in the thickness direction of the tube material, and the other brazing material supplies a molten brazing material to the other surface side in the thickness direction of the tube material. Source.

As described above, a continuous long brazing material represented by a wire is integrated into a fin material, or a similar brazing material is integrated into a tube material. To produce an assembly for a brazing structure according to a conventional method. The main parts of the assembly assembled in this manner are shown in FIGS.

After assembling the assembly for the brazing structure,
Brazing heating is performed on the entire assembly. This
At the time, such as the method known as Nokolock brazing method
Brazing with flux according to
Vacuum brazing can be performed without using flux.
And of course. In the former case, for example, KAlF
_Four , K_ThreeAlF₆Non-corrosive fluoride composed of a mixture such as
The powder of the system flux is suspended in water to form a slurry.
Spray-applied to the brazing structure assembly and allowed to dry.
For example, with an oxygen concentration of 50 ppm and a dew point of −40 ° C.
The whole assembly for the brazing structure in a plain atmosphere brazing furnace
May be heated to the brazing temperature.

When the assembly is heated to the brazing temperature in this manner, the brazing material is melted, and the molten brazing material is selectively applied to a portion to be a joint, that is, a portion where the fin material and the tube material are in contact with each other. Supplied. The situation at this time will be described in more detail. As shown in FIGS. 1 and 2, a groove 5 is formed at the top of the ridge 3 of the fin material 1 and a continuous long shape represented by a wire is formed at the groove 5 When the brazing material 7 is arranged, the brazing material 7 is located in the immediate vicinity of a portion where the top surface of the ridge 3 of the fin material 1 and the outer surface of the tube material 9 are in acute contact (a portion to be a joint). Therefore, the molten solder is sucked into the sharp joint by capillary action at the time of brazing heating, and in addition to the suction force due to the capillary action, the flow-down effect due to gravity acts, and the molten solder is continuously melted. The wax flows into the sharp joint,
The molten solder is supplied over the entire length in the length direction of the acute joint. On the other hand, on the back side (the side having a concave curved surface) of the ridge of the fin material, since the suction force due to the capillary phenomenon is smaller than that of the acute-angled joint portion, molten solder hardly flows. Therefore, the molten solder is selectively supplied only to the portion to be a joint. After that, if the brazing structure assembly is cooled to solidify the molten braze, a fillet is formed uniformly over the entire joint portion and no brazing material is present at portions where brazing is unnecessary. You can get the body.

On the other hand, as shown in FIGS. 3 and 4, when the continuous long brazing material 7 typified by a wire is integrally joined to the end face 9A at one end in the width direction of the tube material 9, the brazing is performed. In some cases, the molten solder flows from the end face of the tube material to both sides in the thickness direction of the tube material due to gravity, and then the molten solder is formed into a capillary at a portion where the fin material and the tube material contact at an acute angle (a portion to be a joint). While being sucked in by the phenomenon, it flows downward along the part due to the effect of gravity, and the molten solder is supplied uniformly over the entire length of the part to be a joint. At this time, almost no molten solder is supplied to the portion on the back side (concave curved side) of the ridge of the fin material or to an intermediate position between the joints on the surface of the tube material. That is, it was selectively supplied. Then, when the whole brazing structure assembly is cooled in the same manner as described above, the molten brazing solidifies, and a brazing structure in which a fillet is formed uniformly at the joint portion can be obtained.

[0047]

EXAMPLE 1 As an alloy of a fin material, Al-Mn-based alloy, which is frequently used as a core material in a conventional fin cladding material, is considered as Al-1.1% Mn-0.3%. Si-0.
A 1% Fe-1.1% Zn alloy (with an impurity concentration of Ti or the like suppressed to 0.1% or less) was used. After casting, the alloy was hot-rolled, subjected to intermediate annealing at a temperature higher than the recrystallization temperature, and finally cold-rolled to a final thickness of 50% to a thickness of 120 µm.
Further, the obtained plate material was finished into a thin plate for a fin material having a width of 22 mm by slit processing. The alloy composition and the conditions of the thermomechanical treatment in the production are adjusted for the purpose of improving the high-temperature buckling resistance, and Zn is added for the purpose of improving the corrosion resistance. However, it goes without saying that manufacturing conditions such as alloy composition, intermediate annealing, and final rolling ratio may be set to conditions other than the above depending on the intended strength level and corrosion resistance.

Before forming a groove for brazing material wire on the fin material thin plate, as shown in FIGS. 5A and 5B, at regular intervals in the longitudinal direction, as shown in FIGS. Punching of a predetermined size was performed. The spacing, shape and size of the punched holes will be selected according to the specifications of the corrugating machine and the shape and size of the brazing wire, respectively. In this embodiment, the punching interval is 17 mm and the punched hole shape is rectangular. R on the long side of
, And the punch size is r = 0.3
0.6 mm and a length of 2.8 to 3.1 mm. The position of the groove in the fin width direction was 1.5 mm from one end in the width direction in order to avoid a louver processed portion.

The punched fin material was corrugated to obtain a corrugated fin having a groove at a position where a joint with a tube was formed as shown in FIG. 6C. In this example, a prototype was obtained with a fin pitch of 4 mm and a fin height of 16 mm in the corrugated shape.
Of course, these numerical values can be changed to a size according to the purpose, and in that case, the punching interval is usually changed according to these changes.

A wire-like brazing material made of 4045 alloy having a diameter of 0.8 to 1.2 mm is mechanically fitted into the groove of the corrugated fin obtained as described above, and integrated,
This was assembled with a flat extruded tube of 1100 alloy having a total thickness of 5 mm to produce an assembly for a brazing structure. The 1100 alloy extruded tube used here was subjected to Zn spraying for the purpose of improving corrosion resistance. However, the present invention is not limited to this, and various combinations of conventionally used tube materials and fin materials can be applied as they are. It is possible.

Next, a flux was applied to the above-mentioned assembly for a brazing structure and dried in the following manner. That is, a non-corrosive fluoride-based flux powder mainly composed of a mixed composition of KAlF ₄ and K ₃ AlF ₆ is suspended in water to obtain a weight concentration of 3%.
% Slurry and spray-applied to the assembly for brazing structure (applying amount of about 3 g / m ² ) at 150 ° C. × 5 mi
The slurry was dried by heating n. Subsequently, brazing was performed by heating at 600 ° C. × 5 min in a nitrogen atmosphere brazing furnace having an oxygen concentration of 50 ppm and a dew point of −40 ° C.
The assembly for the brazing structure was arranged so that the width direction of the fins was vertical so that the side on which the wire-shaped brazing material was provided was positioned upward in the furnace. After cooling to room temperature, the brazing condition was observed. As a result, a sound fillet was formed over the entire length of the joint between the fin and the tube, and it was confirmed that brazing was performed with good brazing properties. The upper and lower ends (widthwise both ends) of the fin having a width of 22 mm had substantially the same fillet size, and it was confirmed that the flow state of the molten solder was normal. Note that the brazing material was not attached to the portion (concave curved portion) on the back side of the ridge of the fin material, and it was confirmed that the molten brazing material was selectively supplied.

As described above, in this embodiment, since the supply of the brazing material is a selective supply to a portion required for forming the fillet, the amount of the brazing material used in the case of using the conventional clad fins is reduced. , It was confirmed that brazing could be performed with about half the amount of brazing material used, and that the amount of brazing material used could be significantly reduced.

Example 2 The same 1100 alloy extruded tube (5 mm in total thickness) as used in Example 1 was placed at the center of one end face in the width direction and a wire brazing material made of 4045 alloy along the length direction. Was bonded and integrated with apatite cement. This is a corrugated fin material made of the same material as that used in Example 1, that is, Al-Mn having a plate thickness of 50 to 120 μm.
By assembling with the alloy fin material, an assembly for a brazing structure was prepared.

Next, a flux was applied and dried in the same process as in Example 1, and then the flux was applied in a nitrogen atmosphere brazing furnace.
Heating was performed at 0 ° C. × 5 min, and brazing was performed. In addition, in the furnace, the width direction of the tube was arranged vertically so that the wire-shaped brazing material was positioned on the upper surface side.

When the state of brazing was observed after brazing, it was confirmed that a sound fillet was formed over the entire length of the contact portion between the fin and the tube, and good brazing properties were exhibited. Also, as in Example 1, it was confirmed that the amount of the brazing filler metal used could be significantly reduced.

Embodiment 3 In Embodiments 1 and 2 described above, 4045 alloy was used as the brazing material wire, and flux was applied and dried at the time of brazing. Recently, however, the flux was wrapped in a 4045 alloy thin plate. The prepared flux cored wire can also be obtained relatively easily, so in Example 3, a brazing structure was formed using the flux cored wire. That is, a brazing structure was prepared according to Examples 1 and 2 using a flux cored wire having a diameter of 1.6 mm and containing a non-corrosive fluoride-based flux at a filling rate of about 30%. Specifically, first, the flux cored wire and the fin were integrated by mechanical fitting in the same manner as in Example 1, and then combined with a tube. Similarly, after being integrated by bonding, this was combined with the fin, and the first and second embodiments were used.
Thus, two types of assemblies for a brazing structure according to the present invention were obtained.

Next, brazing was performed by heating at 600 ° C. for 5 minutes in a nitrogen atmosphere brazing furnace according to the same steps as in Examples 1 and 2, except for the steps of applying and drying the flux. When observing the brazing condition, a sound fillet was formed over the entire length of the contact portion between the fin and the tube in any of the structures.
It was confirmed that good brazing properties were exhibited as in Example 2.

[0058]

According to the present invention, it is possible to prepare an assembly for a brazing structure by using a bare material for both the fin material and the tube material and to perform brazing. Such effects can be obtained.

(1) In the clad fins used in the current method, erosion occurs as an unavoidable problem, and it is difficult to reduce the thickness of the clad fins. The high temperature buckling resistance can be improved, so that the thickness of the fins and tubes can be reduced, the cost of the heat exchanger can be reduced, and the weight of the heat exchanger can be reduced. Here, as a method for evaluating high-temperature buckling resistance, evaluation based on a sag amount (sag amount) by a sag test is generally well known. The sag amount in the sag test is as follows.
Mechanically, it is expressed by the equation of equal deflection of a cantilever, and the amount of sag increases in proportion to [1 / t ² ] with respect to the plate thickness t. FIG. 6 shows the relationship between the fin material thickness and the sag amount for the clad fin and the bare fin for [1 / t ² ]. As is clear from FIG. 6, it can be confirmed that the amount of sag is extremely smaller in the bare fin than in the clad fin.

(2) In the case of the current brazing method using the clad fins, there is inevitably an extra brazing material clad at an unnecessary portion which does not contribute to the formation of a fillet. In this case, it is possible to selectively supply the brazing material to a necessary portion, so that the amount of brazing used can be significantly reduced as compared with the case of the current method, and the cost of the heat exchanger can be reduced.

(3) The clad material used in the current method is inevitably expensive due to the characteristics of its production. In the present invention, however, the clad material is replaced with a bare material to thereby reduce the heat exchanger. Cost reduction becomes possible.

Further, in the case of the method of the present invention, the steps are relatively simple, the deviation from the current step is small, and therefore, the increase in equipment cost and production cost is small. While addition of a material is necessary, the present invention does not require the use of a special binder material, and thus can avoid an increase in cost due to the use of a new material.

Regarding the brazing property, the same level of brazing property as that of the method using the existing clad material can be sufficiently ensured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of an example of a state where a wire brazing material is fitted into a fin material and integrated according to the method of the present invention.

FIG. 2 is a perspective view showing an example of a state where the fin material of FIG. 1 is combined with a tube material.

FIG. 3 is a perspective view showing an example of a state where a wire brazing material is joined and integrated with a tube material according to the method of the present invention.

FIG. 4 is a perspective view showing a main part of an example of a state where the tube material of FIG. 3 is combined with a fin material using the tube material.

FIGS. 5A and 5B are schematic diagrams for explaining a method of forming a groove in a fin material by punching and further corrugating the fin material according to the first embodiment of the present invention. FIG. (B) shows a hole formed by punching, and (c) shows a fin material after corrugation.

FIG. 6 is a graph showing the sag amount (sag amount) of the fin material in the sag test with respect to [1 / t ² ] related to the thickness t of the fin material.

FIG. 7 is a schematic longitudinal sectional view for explaining a state of a brazing material in a heat exchanger brazing structure assembly using a current clad fin material.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Corrugated fin material 3 Mountain part 5 Groove 7 Brazing material 9 Tube material

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Claims (7)

[Claims] 1. A fin material and a tube material, both of which are made of a bare material made of an aluminum material, are assembled into a shape of a brazing structure for a heat exchanger, and the fin material and the tube material are close to a portion to be a joint between the fin material and the tube material. At a position spatially continuous with the portion, a brazing material of a predetermined shape based on Al-Si is integrally incorporated to produce an assembly for a brazing structure,
The whole assembly is heated to the brazing temperature to melt the brazing material, and the molten brazing material is selectively supplied to the portion to be the joint, and then cooled to solidify the molten brazing material, thereby forming the fin material. A method of manufacturing a brazing structure for an aluminum heat exchanger, comprising brazing a tube material to a tube material. 2. The method for manufacturing a brazing structure for an aluminum heat exchanger according to claim 1, wherein the fin material is formed in a corrugated shape in advance, and a top surface of a peak of the corrugated fin material is formed. Assembling the brazing structure assembly so as to contact the outer surface of the tube material,
A method for producing a brazing structure for an aluminum heat exchanger. 3. The method for manufacturing a brazing structure for an aluminum heat exchanger according to claim 2, wherein a groove is formed at a top of a peak of the corrugated fin material, and the assembly is assembled before the assembly. Disposing the brazing material in a groove, and assembling the corrugated fin material and the tube material into a shape of a brazing structure for a heat exchanger in that state, the brazing structure for an aluminum heat exchanger, Production method. 4. The method for manufacturing a brazing structure for an aluminum heat exchanger according to claim 3, wherein the brazing material is a continuous long-shaped brazing material, and the continuous long-shaped brazing material is corrugated. When the brazing material is arranged in the groove of the fin material, the length direction of the brazing material is positioned so as to be orthogonal to the continuous direction of the ridges of the fin material, and the brazing material common to the grooves of the plurality of ridges is provided. And a method for manufacturing a brazing structure for an aluminum heat exchanger. 5. The method for manufacturing a brazing structure for an aluminum heat exchanger according to claim 2, wherein a brazing material is bonded and integrated to an outer surface of the tube material in advance by assembling or welding prior to assembling the assembly. A method of manufacturing a brazing structure for an aluminum heat exchanger, comprising assembling the corrugated fin material and the tube material into a shape of a brazing structure for a heat exchanger in that state. 6. The method for manufacturing a brazing structure for an aluminum heat exchanger according to claim 5, wherein the brazing material is a continuous long-shaped brazing material, and the continuous long-shaped brazing material is a tube. In joining and integrating with the outer surface of the material, the brazing material is disposed on one end face in the width direction of the tube material such that the length direction of the brazing material is orthogonal to the continuous direction of the ridges of the corrugated fin material. A method for manufacturing a brazing structure for an aluminum heat exchanger. 7. The method for manufacturing a brazing structure for an aluminum heat exchanger according to claim 4, wherein a cross-sectional shape and a cross-sectional dimension are constant in a length direction as the continuous elongated brazing material. A method for manufacturing a brazing structure for an aluminum heat exchanger, comprising using the wire-shaped brazing material described above.