JP7196285B2 - Brazing tube, manufacturing method thereof, and heat exchanger - Google Patents

Description

TECHNICAL FIELD The present invention relates to a brazing tube, its manufacturing method, and a heat exchanger.
This application claims priority based on Japanese Patent Application No. 2019-058262 filed in Japan on March 26, 2019, the contents of which are incorporated herein.

BACKGROUND ART An aluminum alloy heat exchanger is known which has flat multi-hole tubes, fins and header pipes as main components and is constructed by brazing these components.
In order to manufacture this type of heat exchanger, a powder brazing composition is provided which is a mixture of Si powder for brazing, a fluoride-based flux, and a binder consisting of a resin and a solvent. Further, a method of manufacturing a heat exchanger at low cost has been proposed by brazing flat multi-hole tubes coated with the above-mentioned powder brazing composition on the front and back surfaces, fins and header pipes. (For example, see Patent Document 1 and Patent Document 2).

Japanese Patent Laid-Open No. 7-227695 (A) Japanese Patent Application Laid-Open No. 2004-330233 (A)

By using the brazing powder composition and the heat exchanger described in Patent Documents 1 and 2, selective corrosion does not occur at the brazed joint between the flat multi-hole tube and the fins, resulting in high reliability. Thus, a heat exchanger with a high heat resistance and high industrial practicality is obtained.
When the above-described brazing powder composition is applied to a flat multi-hole pipe, the powder brazing composition is applied to the front surface or the back surface because the portion of the flat multi-hole pipe that contacts the fins is the front surface or the back surface.
By applying the powdered brazing composition to the front and back surfaces of the flat multi-hole pipe, part of the components contained in the powder brazing composition diffuse to the front surface side or back surface side of the flat multi-hole pipe during brazing, forming a sacrificial anode layer. to form Due to the presence of this sacrificial anode layer, a sacrificial anti-corrosion effect can be obtained, and selective corrosion of the brazed portion can be suppressed.

Conventionally, when a brazing powder composition is applied to a multi-hole flat pipe, it is common practice to apply the composition to the front and back surfaces of the pipe using an applicator such as a bar coater or a roll coater. This is because the parts that come into contact with the fins are the front and back surfaces of the flat tube, the brazing composition can be applied uniformly at a desired speed by these coating devices, and the coating is suitable for mass production.

By the way, heat exchangers are being further reduced in size and weight, and measures to further improve the reliability of brazed portions are required. From this point of view, further improvement in the reliability of the brazed part using the powder brazing composition was investigated. may progress.
Unlike the flat and wide front and back sides, the side surfaces of the flat multi-hole pipe have curved portions and narrow side surfaces, so the brazing composition can be evenly applied to the side surfaces of the flat multi-hole pipe. I have a problem that is difficult to do.
For example, there is a problem that the brazing composition cannot be uniformly applied to curved and narrow side surfaces using a bar coater or a roll coater. In particular, it is difficult to evenly apply the brazing composition to the corners, which are the boundaries between the front and back surfaces and the side surfaces of the flat multi-hole pipe, and which are also curved surfaces.

In addition, in the structure for joining flat multi-hole tubes and fins applied to heat exchangers, a structure is known in which the flat multi-hole tubes are inserted into slit-shaped holes formed in the fins to position them and brazed. It is In this structure, since it is necessary to insert the flat multi-hole pipe into the slit-shaped hole, it is necessary to insert the flat multi-hole pipe while sliding it along the inner edge of the hole. In this case, if the brazing composition is applied to the side surface of the multi-hole flat pipe with an uneven thickness, there is a problem that the brazing composition peels off when it is rubbed against the inner surface of the hole.

The present invention has been devised in view of these circumstances. It is an object of the present invention to provide a brazed tube and a method for manufacturing the same.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a brazing tube in which the brazing composition is less likely to peel off even when it is inserted into the holes of the fins to form a combined structure with the fins, and to provide a method for producing the same.
An object of the present invention is to provide a heat exchanger comprising a brazing tube as described above.

The present invention has the following aspects.

(1) An aluminum or aluminum alloy brazing material comprising a flat tube body having a front surface, a back surface, and short side surfaces, and having a brazing composition layer formed on the front surface side, the back surface side, and the short side surface. A tube, wherein a first brazing composition layer having a thickness of 5 to 30 μm is formed on the short side surface, and includes corner portions extending from the front surface to the short side surface and portions extending from the back surface to the short side surface. A second brazing composition layer having a thickness of 0.5 to 15 μm is formed on the back side corner portion, a main brazing composition layer is formed on the front surface and the back surface, and the first brazing Brazing wherein the composition layer, the second brazing composition layer, and the main brazing composition layer contain at least one of Si powder, Zn-containing flux, and Zn-free flux, and further contain a binder A brazing tube characterized by being a composition layer .

( 2 ) The brazing tube according to (1), wherein the main brazing composition layer contains Si powder: 1-5 g/m ² .

( 3 ) The brazing tube according to (1) or (2) above, wherein the main brazing composition layer contains Zn-containing flux: 3-20 g/m ² .

( 4 ) The brazing tube according to any one of (1) to ( 3 ) above, wherein the main brazing composition layer contains 1 to 10 g/m ² of Zn-free flux.

( 5 ) The brazing tube according to any one of (1) to ( 4 ) above, wherein the main brazing composition layer contains a binder: 0.2 to 8.5 g/m ² . .

( 6 ) The brazing tube according to any one of (1) to ( 5 ) above, wherein the tube main body comprises an extruded multi-hole tube having a plurality of flow paths therein.

( 7 ) One or more of Si powder, Zn-containing flux, and Zn-free flux are sprayed from an air spray device facing the short side of a flat tube body having a front surface, a back surface, and a short side surface. and further spraying a brazing liquid composition containing a binder and a solvent to form a first brazing composition layer having a thickness of 5 to 30 μm on the short side, and a surface from the surface to the short side Manufacture of a brazing tube characterized by forming a second brazing composition layer having a thickness of 0.5 to 15 μm on the side corner portions and the back side corner portions of the portion extending from the back surface to the short side surface. Method.

( 8 ) The brazing tube according to (7) , characterized in that a main brazing composition layer containing Si powder: 1 to 5 g/m ² is formed on the front surface and the back surface of the tube body. Production method.

( 9 ) The above-mentioned (7) or (8) , characterized in that a main brazing composition layer containing Zn-containing flux: 3 to 20 g/m ² is formed on the front surface and the back surface of the tube body. A method of manufacturing a brazed tube.

( 10 ) Any one of the above ( 7 ) to ( 9 ), wherein a main brazing composition layer containing 1 to 10 g/m ² of Zn-free flux is formed on the front surface and the back surface of the tube body. A method for manufacturing a brazing tube according to any one of the above.

( 11 ) The above ( 7 ) to ( 10 ), wherein a main brazing composition layer containing a binder: 0.2 to 8.5 g/m 2 is formed on the front surface and the back surface of the tube body. A method for manufacturing a brazing tube according to any one of .

( 12 ) The brazing tube according to any one of (1) to ( 6 ) above and a fin having an elongated hole through which the brazing tube is inserted ; A heat exchanger in which a tube is inserted and the brazing tube and the fins are brazed together, wherein the brazing tube and the fins are joined together by a fillet that is a melted and solidified product of the brazing composition layer. A heat exchanger characterized by being brazed.

With the brazing tube according to the present embodiment, it is possible to prevent the brazing composition from peeling off on the short side surfaces of the flat tube main body, and to ensure reliable brazing properties on the short side surfaces of the tube main body. This embodiment provides a brazing tube in which the brazing composition is less likely to peel off even when it is inserted into the holes of the fins to form a combined structure with the fins, so that the brazing tube can be reliably brazed. can.

The brazing tube according to this embodiment employs a configuration in which a brazing composition layer having a suitable thickness is provided on each of corner portions and short side surfaces, which are boundary portions between the front and back surfaces and the short side surfaces. As a result, peeling of the brazing composition can be prevented when assembling the fins and the flat tube, and reliable brazing can be achieved at corner portions and short side surfaces. Further, it is possible to provide a brazing structure in which the fins do not collapse even when the tube body is bent and used, and the quality of the brazed portion is excellent.
A brazed heat exchanger comprising a brazing tube with a brazing composition layer of suitable thickness as described above would have a high quality brazed part and the tube body would be inserted into the through holes of the fins. It is possible to provide a heat exchanger in which the fins are unlikely to be deformed even when the tubes are fitted together, and the fins are unlikely to collapse even when the tubes are used with the tubes bent.

1 is a cross-sectional view of a brazing tube of a first embodiment according to this form; FIG. FIG. 2 is a perspective view showing an example of a heat exchanger in which fins are brazed to the tubes shown in FIG. 1; FIG. 4 is a partial cross-sectional view showing a joint portion between tubes and fins in the same heat exchanger. FIG. 3 is a partial cross-sectional view showing a state before brazing in the heat exchanger shown in FIG. 2; FIG. 3 is a partial cross-sectional view showing a state after brazing in the heat exchanger shown in FIG. 2; FIG. 3 is an explanatory view showing an example of a state in which a tube without a brazing composition layer on its corner portion is inserted into a hole of a fin when assembling the heat exchanger shown in FIG. 2 ; FIG. 3 is an explanatory diagram showing an example of a state in which a tube having a brazing composition layer on its corner portion is inserted into a hole of a fin when assembling the heat exchanger shown in FIG. 2 ; FIG. 2 is an explanatory diagram showing a state in which a brazing composition is being applied to the brazing tube shown in FIG. 1 by an air spray device; 8 is a graph showing an example of friction that occurs when the tube is inserted into the hole of the fin in the state shown in FIG. 7; 7 is a graph showing an example of friction that occurs when the tube is inserted into the hole of the fin in the state shown in FIG. 6; 4 is a photograph showing an example of a state of application of a brazing composition applied to a short side surface of a multi-hole flat tube by an air spray device.

An example of an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In the drawings used in the following explanation, in order to make the features easier to understand, the characteristic parts may be enlarged for convenience, and the dimensional ratios of each component may differ from the actual tubes and heat exchangers. not necessarily the same.

"First Embodiment"
FIG. 1 shows the cross-sectional structure of a flat tube 22 applied to the heat exchanger 11 shown in FIGS. It consists of a tube body 12 made of material.
The heat exchanger 11 of the first embodiment is used for applications such as heat exchangers for indoor/outdoor units of room air conditioners, outdoor units for HVAC (Heating Ventilating Air Conditioning), and heat exchangers for automobiles. It is an all-aluminum heat exchanger with

The tube 22 shown in FIG. 1 shows a state before brazing, in which the outer peripheral surface of the tube body 12 placed horizontally is coated with a brazing composition layer.
The tube body 12 includes a wide surface wall 12A, a back wall 12B, short side walls 12C, 12C connecting the left and right end sides thereof individually, and a plurality of partition walls partitioning the inside of the tube body 12 into a plurality of flow paths 12D. 12E. In this example, all of the plurality of channels 12D are formed to have a similar rectangular cross-sectional shape, and in the example shown in FIG. 1, 26 channels 12D are formed in the tube body.
Note that the tube main body 12 shown in FIG. 1 is just an example, and the width, thickness, flatness (ratio of width and thickness) of each part, and the shape and number of the flow paths 12D can be set arbitrarily. can be done.

In other words, the tube body 12 is formed in a flat shape having a wide flat front surface (upper surface) 12a and a wide rear surface (lower surface) 12b, and flat short side surfaces 12c, 12c connecting the two ends individually. ing. A corner portion 12f formed in an arc shape with a predetermined curvature is formed in the tube body 12 from the widthwise end of the front surface 12a to the short side 12c. A corner portion 12g formed in an arc shape with a predetermined curvature is also formed in the portion extending to the end. A portion of the short side 12c, excluding the upper and lower corner portions 12f and 12g, is formed in a planar shape facing the front surface 12a and the rear surface 12b substantially perpendicularly.
The shape of the short side surface 12c is not particularly limited, and may be a curved surface or an inclined surface.

A main brazing composition layer 15 comprising a coating film of a brazing composition having a composition described later is formed on the front surface 12a and the back surface 12b of the tube body 12 shown in FIG. A first brazing composition layer 16 having a composition described later is formed on the outer side of the short side 12c of the tube body 12, and a second brazing composition layer 16 having a composition described later is formed on the outer side of the corner portions 12f and 12g. A composition layer 17 is formed.
In this embodiment, the main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 are made of the brazing composition having the same composition as described later. are different.

FIG. 2 shows the overall structure of the heat exchanger 11 shown in FIG. 1, which is constructed by brazing the plurality of tubes 22 shown in FIG. show.
As shown in FIG. 2, the heat exchanger 11 is composed of a pair of header pipes 14 vertically spaced apart from each other and arranged vertically in parallel, and vertically spaced between the pair of header pipes 14 horizontally. A plurality of tubes 22 (tube bodies 12) joined substantially perpendicularly to the header tubes 14, and a plurality of tubes brazed to the front surface 12a or rear surface 12b of the tube bodies 12 for dissipating heat to the outside air. of fins 13.

A supply pipe 18</b>A for supplying refrigerant to the tubes 22 via the header pipes 14 is connected to one upper end portion of the pair of left and right header pipes 14 . A collection pipe 18B for collecting the refrigerant that has passed through the tube 22 is connected to the lower end of the other header pipe 14 . Tubes 22, fins 13, header pipe 14, supply pipe 18A, and recovery pipe 18B are all made of aluminum or an aluminum alloy.

FIG. 3 is a partial cross-sectional view of heat exchanger 11 taken along a plane orthogonal to the length direction of tube 22 . As shown in FIG. 3, a plurality of (26 in this embodiment) refrigerant flow paths 12D are formed inside the tube main body 12 that constitutes the tube 22 and are aligned along the width direction. Further, as shown in FIG. 3, a plurality of slit-shaped holes 19 having a shape corresponding to the cross-sectional shape of the tube 22 are horizontally formed in the fins 13 at predetermined vertical intervals. As shown in FIG. 3, these holes 19 are formed from the left end to near the right end of the fins 13, and the deepest part of the holes 19 is located slightly forward of the right end of the fins 13. .

Tubes 22 are fitted into these holes 19, and the individual tubes 22 are fixed to the plurality of fins 13 by brazing. The length of the hole 19 formed in the fin 13 (horizontal length shown in FIG. 3) is slightly shorter than the width of the fin 13, and the tube 22 inserted into the hole 19 has a short side surface on one side in the width direction. 12c is inserted to the deepest part of the hole 19 and brazed.

4 and 5 are partial cross-sectional views taken along the longitudinal direction of the tubes 22 in the heat exchanger 11 shown in FIGS. 2 and 3, and FIG. 4 shows the state before brazing. , and FIG. 5 shows the state after brazing. A plurality of fins 13 are arranged in parallel along the length direction of the tube 22 (along the left-right direction in FIGS. 4 and 5), and the tube 22 is inserted through each hole 19 .
The plurality of fins 13 are arranged parallel to each other at regular intervals. The fin 13 has a bent portion 20 bent to one side in the thickness direction of the fin 13 along the peripheral portion of the hole portion 19 . The bent portion 20 is formed by a processing method such as burring, for example.

As shown in FIG. 5, the tubes 22 and the fins 13 are arranged so that the tubes 22 are skewered and pass through the plurality of fins 13 arranged at regular intervals, and the fins 13 and the tubes 22 are individually fixed by brazing.
In the state before brazing shown in FIG. 4, the gap between the bent portion 20 formed in the hole portion 19 of the fin 13 and the front or back surface of the tube 22 is formed to be approximately 10 μm or less. If the gap is too large, the amount of melted brazing filler metal will be insufficient in the brazing process, which will be described later, and this may cause brazing failure.

In the fins 13 of the present embodiment, as shown in FIG. through-holes may be provided, and the tube 22 may be passed through these through-holes. In this configuration, compared to the state shown in FIG. 3 , the tube 22 exists only inside the through hole, and one widthwise end of the tube 22 does not protrude outside the fins 13 .
As described above, there is no particular limitation on the position where the tube 22 penetrates the fins 13, and any joint position or joint shape that ensures good thermal conductivity by brazing the fins 13 and the tube 22 may be used.

The main components of the heat exchanger 11 are described in more detail below.
<<Fins and their constituent materials>>
As shown in enlarged view in FIGS. 4 and 5, the fin 13 has a plate-like substrate 3 and a hydrophilic film 1 coated on the first surface 3a and the second surface 3b of the substrate 3. preferably.
The base material 3 of the fin 13 is made of an alloy mainly composed of pure aluminum such as JIS 1050 series or JIS 3003 series aluminum alloy. Further, the base material 3 may be made of an aluminum alloy obtained by adding about 2% by mass of Zn to a JIS3003 series aluminum alloy.
The base material 3 of the fins 13 is produced by melting the aluminum alloy by a conventional method, and processed through a hot rolling process, a cold rolling process, a pressing process, and the like. In addition, the manufacturing method of the base material 3 is not particularly limited in the present invention, and a known manufacturing method can be appropriately adopted.

<<Constituent material of header pipe>>
The aluminum alloy forming the header tube 14 is preferably an aluminum alloy based on an Al--Mn system. For example, it is preferable to contain Mn: 0.05 to 1.50%, and as other elements, Cu: 0.05 to 0.8% and Zr: 0.05 to 0.15%. can.

<<Tube configuration>>
As shown in FIG. 1, the tube 22 before brazing has a tube body 12 and brazing composition layers 15, 16, 17 formed on its outer peripheral surface.
The tube main body 12 is made of, for example, an alloy mainly composed of pure aluminum such as JIS1050 series or JIS3003 series aluminum alloy. As an example, Si: 0.10 to 0.60%, Fe: 0.1 to 0.6% by mass, Mn: 0.1 to 0.6% by mass, Ti: 0.005 to 0.2% by mass, Cu: Less than 0.1% by mass, the balance is made of an aluminum alloy consisting of aluminum and unavoidable impurities, and is produced by extruding these aluminum alloys.

<<Constituent Material of Main Brazing Composition Layer 15>>
The main brazing composition layer 15 formed on the tube body 12 before brazing shown in FIGS. 1 and 4 is a coating film applied at least to the portion where the fins 3 are joined by brazing.
The main brazing composition layer 15 includes, for example, Si powder: 1-5 g/m ² , Zn-containing flux (KZnF ₃ ): 3-20 g/m ² , Zn-free flux: 1-10 g/m ² and a binder (for example, acrylic resin): 0.2 to 8.5 g/m ² . A liquid brazing composition is formed by adding an appropriate amount of solvent to these components.

The constituent materials of the brazing composition forming the main brazing composition layer 15 are described below.
<Si powder>
The Si powder reacts with Al constituting the tube main body 12 during brazing to form brazing that joins the fins 3 and the tube main body 12. During brazing, the Zn-containing flux and the Si powder melt to form a brazing liquid. .
Zn in the flux is uniformly diffused into this brazing liquid, and spreads uniformly over the front and back surfaces of the tube body 12 . Since the diffusion rate of Zn in the brazing liquid, which is a liquid phase, is significantly higher than the diffusion rate in the solid phase, Zn is uniformly diffused on the tube surface and the back surface, and the Zn concentration in the plane direction of the tube surface and the back surface is increased. almost uniform. As for the diffusion in the depth direction from the surface of the tube body 12, since Si becomes a eutectic with Al to lower the melting point, Zn diffuses in a state of eutectic composition on the surface of the tube body 12. A Zn melt diffusion layer having a predetermined thickness is formed on the front surface side and the rear surface side of the tube body 12 . Since this Zn fusion diffusion layer becomes a sacrificial anode layer, the corrosion resistance of the brazed portions on the front side and the back side of the tube body 12 can be improved.
In this embodiment, since the brazing composition layers 16 and 17 are also formed on the short side surfaces of the tube body 12, the Zn and Si contained in these brazing composition layers 16 and 17 do not diffuse. A sacrificial anode layer is also formed on the short side surface of the tube body 12 .

<Si powder coating amount: 1 to 5 g/m ² >
If the amount of Si powder applied is less ^than 1 g/m ² , brazing formation may be insufficient. It is not preferable because the thickness of the Therefore, the content of Si powder in the main brazing composition layer 15 is preferably 1-5 g/m ² .
<Si powder particle size: maximum particle size: D (99): 30 μm or less>
If the particle size of the Si powder is 30 μm or less in D(99), it is possible to form a uniform Zn fusion diffusion layer. There is a possibility that the diffusion layer cannot be formed. Therefore, the particle size of the Si powder is preferably 30 μm or less at the maximum particle size D(99). Note that D(99) is the particle diameter of particles that accumulate from particles having a small volume ratio and form 99% of the total. All of these values can be measured by a laser light scattering method.

<Zn-containing flux, Zn-free flux>
The Zn-containing flux has the effect of forming Zn melt diffusion layers on the front and back sides of the tube body 12 during brazing, thereby improving pitting corrosion resistance. In addition, it has the effect of destroying the oxide film on the outer surface of the tube 3 during brazing, promoting the spread and wetting of the braze, and improving the brazeability. Since this Zn-containing flux has higher activity than a Zn-free flux, good brazeability can be obtained even with relatively fine Si powder. One or more of KZnF ₃ , ZnF ₂ and ZnCl ₂ can be used as the Zn-containing flux. A non-Zn containing flux may be added to the Zn containing flux.

Fluoride-based fluxes and potassium fluoroaluminate-based fluxes as Zn-free fluxes are fluxes containing KAlF ₄ as the main component, and various compositions with additives are known. Examples include a composition of K ₃ AlF ₆ +KAlF ₄ (K _1-3 AlF _6-4 ), Cs _(x) K _(y) F _(z) , and the like. In addition, a fluoride-based flux (for example, a potassium fluoroaluminate-based flux) to which a fluoride such as LiF, KF, CaF ₂ , AlF ₃ , or K ₂ SiF ₆ is added can also be used. Addition of fluoride-based flux (for example, potassium fluoroaluminate-based flux) in addition to Zn flux contributes to improvement in brazeability.

<Amount of flux applied: 3 to 20 g/m ² >
If the coating amount of the Zn-containing flux is less than 3 g/m ² , the potential difference in the heat exchanger 11 will be low, and the sacrificial effect may not be exhibited. In addition, insufficient removal of the oxide film on the surface of the tube body 12 may lead to poor brazing. On the other hand, if the coating amount exceeds 20 g/m ² , the potential difference becomes excessive, the corrosion rate increases, and there is a possibility that the anti-corrosion effect due to the presence of the Zn fusion diffusion layer will be short-lived. Therefore, the amount of Zn-containing flux applied is preferably 3 to 20 g/m ² . Zn-containing flux can use _KZnF3 as an example. The non-Zn containing fluxes described above can be added in addition to the Zn containing fluxes.

<Binder application amount: 0.2 to 8.5 g/m ² >
The brazing composition layer 15 may contain a binder in addition to Si powder and Zn-containing flux. An example of the binder is an acrylic resin.
The binder has the effect of fixing the Si powder and Zn-containing flux necessary for forming the Zn melt ^- diffusion layer to the front and back surfaces of the tube 22. Sometimes Si powder and Zn flux fall off from the tube main body 12, and there is a possibility that a uniform Zn fusion diffusion layer is not formed. On the other hand, if the coating amount of the binder exceeds 8.5 g/m ² , there is a risk that the brazeability will be degraded due to the binder residue, and a uniform Zn fusion diffusion layer will not be formed. Therefore, it is preferable that the coating amount of the binder is 0.2 to 8.5 g/m ² . Note that the binder usually evaporates due to heating during brazing.

The method of forming the brazing composition layer 15 consisting of Si powder, flux and binder is not particularly limited in this embodiment, and may be spray method, shower method, flow coater method, bar coater method, roll coater method, or brush. Appropriate methods such as a coating method, an immersion method, and an electrostatic coating method can be used.

<<Materials Constituting the First and Second Brazing Composition Layers>>
The first brazing composition layer 16 and the second brazing composition layer 17 formed on the side surface of the tube body 12 shown in FIG. 1 basically constitute the main brazing composition layer 15. made of the same material as the That is, it contains one or more of Si powder, Zn-containing flux, and non-Zn-containing flux, and further contains a binder. Alternatively, it contains one or more of Si powder, Zn-containing flux, and non-Zn-containing flux, and further contains a binder and a solvent.
However, the first brazing composition layer 16 and the second brazing composition layer 17 are individually formed to desired thicknesses as described below. The first brazing composition layer 16 is desirably formed to a thickness in the range of 5-30 μm. The second brazing composition layer 17 is desirably formed with a thickness in the range of 0.5 to 15 μm.

A first brazing composition layer 16 is a brazing coating formed on the short sides of the tube body 12 . During brazing, this coating melts and solidifies to fix the short side surface of the tube body 12 to the innermost side of the hole 19 of the fin 13 by brazing.
The second brazing composition layer 17 is a brazing coating formed on the short side corners of the tube body 12 . During brazing, this coating melts and solidifies to braze and fix the corner portions of the short side surfaces of the tube body 12 to the innermost sides of the holes 19 of the fins 13 .
Without these first and second brazing composition layers 16 and 17, the fixing force for brazing the short sides of the tube body 12 to the fins 13 is insufficient.

For example, there is known a configuration in which a part of the heat exchanger is bent into an L shape in plan view and accommodated in the outdoor unit in response to the demand for downsizing and compactness of the outdoor unit. When a portion of the heat exchanger is bent into an L shape in plan view, if the short side of the tube body 12 is insufficiently brazed to the innermost side of the hole 19 of the fin 13, A part of the plurality of fins 13 may collapse at the bent portion. If the first and second brazing composition layers 16 and 17 provided on the short side of the tube body 12 are sufficiently thick, the fins 13 can be sufficiently secured by brazing. Therefore, even when the tube main body 12 is bent into an L shape in plan view, the bending process can be performed without causing the fins to collapse.
In the case of a structure in which the tube main body 12 is bent into an L-shape, for example, in order to prevent buckling or the like of the tube main body 12, a configuration having a low oblateness is adopted by reducing the number of refrigerant passages in the tube main body 12. .

When the second brazing composition layer 17 is absent or too thin, the tube body 12 is inserted into the hole 19 of the fin 13 and the corner of the tube body 12 is rubbed against the opening of the hole 19. , the insertion resistance increases, and there is a risk of causing trouble when inserting the short side of the tube main body 12 into the hole 19 .

When assembling the heat exchanger 11 shown in FIGS. 2 and 3, it is necessary to insert the eight tube bodies 12 vertically aligned as shown in FIG. be. Even if the plurality of fins 13 are aligned and arranged precisely, the holes 19 of the fins 13 may be slightly displaced vertically or horizontally due to manufacturing errors or the like.
In addition, the eight tube bodies 12 shown in FIG. 2 are manufactured with precision, all of them have a uniform thickness, and all the holes formed in the header tube 14 for inserting the tubes are uniformly formed at accurate positions. Even if it is, it is conceivable that the tube bodies 12 arranged vertically adjacent to each other may be slightly displaced due to manufacturing errors of each part.

As described above, if the holes 19 of the fins 13 and the ends of the tube body 12 are misaligned even a little, when inserting the ends of the tube body 12 into the holes 19 as shown in FIG. The corner portion of 12 is inserted while rubbing the inner peripheral edge of the opening of the hole portion 19 .
Here, if the fins 13 are made of aluminum or an aluminum alloy, and the tube 12 is also made of aluminum or an aluminum alloy, aluminum rubs against each other.
Rubbing between aluminum is a rubbing with a large frictional resistance among rubbings between metals, so the frictional resistance fluctuates greatly when the tube body 12 is inserted into the hole 19, and depending on the situation, a thin fin may be formed at the time of fitting. 13 may be deformed.
In this regard, if brazing composition layers 17, 17 of appropriate thickness are provided at the corners of the tube body 12 as shown in FIG. The resistance is less than the frictional resistance of , and smoother insertion work is possible.

Therefore, it is desirable that the second brazing composition layer 17 is formed with a thickness in the range of 0.5 to 15 μm. If the thickness of the brazing composition layer 17 is less than 0.5 μm, the effect of reducing the frictional resistance during insertion is insufficient. When the thickness of the brazing composition layer 17 exceeds 15 μm, the brazing composition layer 17 is too thick at the corner portions, and when the tube body 12 is inserted into the hole 19 , the brazing composition layer 17 is not thick enough. There is a possibility that the problem of peeling may occur.

FIG. 4 shows a vertical cross-section of the tube body 12 inserted into the holes 19 of the fins 13. The main brazing composition layer 15 of the tube body 12 faces the tube body 12 at the bends 20 of the fins 13. It is located between the portion (the facing surface 20 a ) and the tube body 12 . The main brazing composition layer 15 is solidified in a state filled between the opposing surface 20a and the tube body 12 by cooling after heating (brazing heating) at around 600° C., as shown in FIG. The fins 13 and the tube body 12 are joined by forming a fillet 15A. Further, the brazing composition layers 16 and 17 formed on the short side surfaces of the tube body 12 and the corner portions thereof become fillets 15A after brazing, and the short side surfaces of the tube body 12 are formed on the innermost side of the hole portion 19. Join the side and the corner part side.

The main brazing composition layer 15 is formed on the areas contacting the fins 13 , ie, on the front surface 12 a and the back surface 12 b of the tube body 12 . In addition, Si and Zn contained in the main brazing composition layer 15 before brazing are diffused toward the tube body 12 at the brazing temperature, and the surface layers of the front and back surfaces of the tube body 12 contain Si and Zn. Form the anode layer.
In addition, Si and Zn contained in the brazing composition layers 16 and 17 are also diffused to the short side and corner portion sides of the tube body 12 during brazing, and a sacrificial anode layer containing Si and Zn is formed in these portions. Form. Therefore, a sacrificial anode layer can be formed on the entire circumference of the tube body 12 after brazing.

<<Method of Forming Brazing Composition Layer>>
The method of forming the primary braze composition layer 15 and the first and second braze composition layers 16, 17 on the tube body 12 will now be described.
The method of forming the main brazing composition layer 15 consisting of Si powder, flux, and binder is not particularly limited in this embodiment. A liquid brazing composition obtained by adding a solvent to Si powder, flux, and binder may be applied by the following method and dried.
Coating can be performed by an appropriate method such as a spray method, a shower method, a flow coater method, a bar coater method, a roll coater method, a brush coating method, an immersion method, or an electrostatic coating method. By these methods, the main brazing composition layer 15 can be formed in the required range of the front surface 12a and the back surface 12b of the tube body 12 with the required coating amount.
For example, the main brazing composition layer 15 can be formed over substantially the entire surface 12a and back surface 12b of the tube body 12 .

Next, as shown in FIG. 8, an air spray coating device 30 is installed at a position a predetermined distance from the short side 12c of the tube body 12, and the liquid brazing composition is applied to the short side 12c and the corners 12f and 12g. Spray on.
The brazing liquid composition used here is a brazing liquid composition obtained by adding a necessary amount of solvent to the aforementioned Si powder, Zn-containing flux (KZnF ₃ ), and binder (for example, acrylic resin). means things.
Alternatively, the aforementioned Si powder, Zn-containing flux (e.g., _KZnF3 ), non-Zn-containing flux, and binder (e.g., acrylic resin) are mixed with a required amount of solvent to form a liquid having a desired viscosity for the air spray method. means a liquid brazing composition of
Alternatively, it means a liquid brazing composition obtained by adding a necessary amount of a solvent to the aforementioned Si powder, a non-Zn-containing flux, and a binder (for example, an acrylic resin) to obtain a liquid with a desirable viscosity for an air spray method.

A coating device 30 shown in FIG. 8 includes a spray gun 32 having a nozzle 31 at its tip, an introduction pipe 33 for supplying liquid in the middle of the flow path of the spray gun 32, and is an air spray type coating device to which an air supply device is connected.
Using this applicator 30, as shown in FIG. 8, the liquid brazing composition is spray-coated on the short side of the tube body 12 to form a first brazing composition layer 16 and a second brazing composition layer. 17 can be formed. As a specific example of the coating device 30, an air spray valve coating device manufactured by Sanei Tech Co., Ltd. can be used.
Adjust the vertical position of the nozzle 31 with respect to the short side 12c of the tube body 12, adjust the position of the nozzle 31 forward and backward, and adjust the injection pressure to adjust the amount of coating on the short side 12c and the amount of coating on the corners 12f and 12g to the desired range. can be adjusted to

After that, the tube bodies 12 are inserted into the holes 19 of the fins 13 arranged in parallel and fitted, assembled in a state similar to that shown in FIG. 2, and brazed.
Brazing is carried out in a heating furnace for several minutes at a temperature above the melting point of the brazing composition layers 15, 16, 17, eg, 580 to 620°C. The heating melts the brazing composition layers 15, 16, 17 into a brazing liquid. This brazing liquid flows into the gaps between the tube body 12 and the bent portions 20 of the fins 13 to fill these gaps. In addition, the brazing liquid described above also flows into the gap on the short side of the tube body 12 fitted at the innermost position of the hole 19 to fill the gap.

Subsequently, by cooling, as shown in FIG. 5, the brazing liquid solidifies to form a fillet 15A. The tube main body 12 and the fins 13 are joined by these fillets 15A.
In the portions where the brazing composition layers 15, 16, 17 are melted, Si and Zn in the flux are diffused by brazing, and in addition to the front and back surfaces of the tube body 12, Zn melt diffusion layers (sacrificial anode layers) are formed on the short side surfaces. ) is formed.

In this embodiment, after the main brazing composition layer 15 is formed, the first and second brazing composition layers 16 and 17 are formed. These may be formed simultaneously.
For example, after the brazing composition layers 16 and 17 are formed on the short side surfaces of the long tube body 12 made of an extruded material by means of the applicator 30 while it is being conveyed, the main brazing composition is applied to the front and back surfaces using a bar coater or a roll coater. A layer 15 may be formed. Further, the main brazing composition layer 15 is formed on the front and back surfaces using a bar coater or roll coater, and the brazing composition is continuously applied to the short sides by a coating device 30 provided adjacent to the bar coater or roll coater. Layers 16 and 17 may be formed. After forming these composition layers on a long tube body 12 made of an extruded material, the tube body 12 is cut to a required length to obtain a brazing tube 22 for a heat exchanger.

<< effect >>
According to the structure of this embodiment, the heat exchanger 11 can be configured by combining and brazing the tube 22 having the brazing composition layers 15, 16, 17 and the plurality of fins 13. FIG. In this case, the fins 13 can be reliably brazed to the front and rear surfaces of the tube body 12 by the brazing composition layers 15 provided on the front and back surfaces of the tube body 12 . Moreover, the brazing composition layers 16 and 17 provided on the short sides of the tube body 12 allow the short sides of the tube body 12 to be reliably brazed to the fins 13 . Therefore, the entire tube main body 12 can be reliably brazed to the fins 13 with sufficient joint strength. That is, high quality brazing can be performed in the heat exchanger 11 .
In addition, when the tube body 12 is inserted into the hole 19 of the fin 13 for assembly, the brazing composition layer 17 provided at the corner of the tube body 12 reduces the friction when rubbing the inner peripheral edge of the hole of the fin 13, Smooth insertion of the tube body 12 into the portion 19 is enabled.
Therefore, when assembling the tube 22 and the fins 13, the fins 13 can be assembled without deformation. Further, when fitting the tube main body 12 into the holes 19 of the fins 13 , the fitting work can be performed while suppressing peeling of the brazing composition layer 17 .

If brazing is performed using the brazing composition layers 15, 16, and 17 described above, Zn is added to the short side 12c side, the corner portion 12f side, and the corner portion 12g side, as well as the front and back sides of the tube 12. It can be diffused and a sacrificial anode layer can be formed all around the tube 12 . Since the portion where the sacrificial anode layer is formed corrodes not as pitting but as surface corrosion, it is possible to provide a structure in which through-holes due to corrosion are less likely to occur in the tube 12 .
In addition, by forming the sacrificial anode layer around the entire circumference of the tube main body 12, it is possible to provide the heat exchanger 11 having an anti-corrosion structure that can suppress corrosion of the brazed portion adjacent to the sacrificial anode layer.

It should be noted that the main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 may contain Si powder and Zn-containing flux.
The primary braze composition layer 15, first braze composition layer 16 and second braze composition layer 17 may also include Si powder, Zn-containing flux and non-Zn-containing flux.

Primary brazing composition layer 15, first brazing composition layer 16 and second brazing composition layer 17 may comprise non-Zn containing fluxes.
The primary brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 may comprise Zn-containing flux.

The primary brazing composition layer 15, first brazing composition layer 16 and second brazing composition layer 17 may also include Zn-containing fluxes and non-Zn-containing fluxes.

The main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 may each have different compositions.
When any one of the main brazing composition layer 15, the first brazing composition layer 16 and the second brazing composition layer 17 is formed as a layer that does not contain Si powder, brazing sheets, brazing rods, etc. With use, brazing material can be supplied to the joint.

The main brazing composition layer 15 may contain Si powder and a Zn-containing flux, and the first brazing composition layer 16 and the second brazing composition layer 17 may contain Zn-containing flux.
Also, the main brazing composition layer 15 contains Si powder, a Zn-containing flux and a non-Zn containing flux, and the first brazing composition layer 16 and the second brazing composition layer 17 contain a Zn-containing flux and a non-Zn containing flux. A Zn-containing flux may be included.

The primary brazing composition layer 15 may contain a non-Zn containing flux and the first brazing composition layer 16 and the second brazing composition layer 17 may contain Si powder and a Zn containing flux.
Also, the main brazing composition layer 15 contains a non-Zn containing flux, and the first brazing composition layer 16 and the second brazing composition layer 17 contain Si powder, a Zn containing flux and a non-Zn containing flux. may contain.

The main brazing composition layer 15 may contain a Zn-containing flux, and the first brazing composition layer 16 and the second brazing composition layer 17 may contain Si powder and a Zn-containing flux.
Also, the main brazing composition layer 15 comprises a Zn-containing flux and a non-Zn-containing flux, and the first brazing composition layer 16 and the second brazing composition layer 17 comprise Si powder, a Zn-containing flux and a non-Zn-containing flux. A Zn-containing flux may be included.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.
<<Preparation of sample>>
From an aluminum alloy plate material containing Si: 0.4 to 0.6% by mass, Mn: 1.0 to 2.0% by mass, Zn: 1.0 to 3.5% by mass, and the balance being inevitable impurities and Al Ten fins each having a length of 100 mm, a width of 20 mm, and a thickness of 0.1 mm were prepared. 25 rows of slit-shaped holes (width 1.6 mm, length 18 mm) were formed in these fins at regular intervals, and flat multi-hole pipes (tubes) described below were fitted into these holes, and heat was applied. An exchanger mini-core body was fabricated.

A flat multi-hole tube made of an aluminum alloy containing 0.3 to 0.5% by mass of Si, 0.2 to 0.4% by mass of Mn, and the balance being inevitable impurities and Al was prepared. This flat multi-hole tube has a width of 17 mm, a thickness of 1.5 mm, and a corner portion having a radius of curvature of 0.3 mm at the boundary between the front and back surfaces and the short side surface.

In Examples 1 to 10, 51 to 60 and Comparative Examples 1 to 4, 22 to 24, Si powder: 3 g/m ² and Zn-containing flux (KZnF ₃ ) were applied to the front and back surfaces of the multi-hole flat tube using a bar coater. : 6 g/m ² and acrylic resin as a binder: 1 g/m ² dispersed in a solvent to form a brazing liquid composition and dried at 150°C for 5 minutes to form a main brazing composition layer.

In Examples 11 to 20, 61 to 70 and Comparative Examples 5 to 8, 25 to 28, Si powder: 3 g/m ² and Zn-containing flux (KZnF ₃ ) were applied to the front and back surfaces of the flat multi-hole tube using a bar coater. : 5 g/m ² , Zn-free flux (K _1-3 AlF _6-4 ): 1 g/m ² , acrylic resin as binder: 1 g/m ² , dispersed in a solvent. , 150° C. for 5 minutes to form the main brazing composition layer.

In Examples 21 to 30, 71 to 90 and Comparative Examples 9 to 12, 22 to 27, a non-Zn-containing flux (K _1-3 AlF _6-4 ) was applied to the front and back surfaces of the multi-hole flat tube using a bar coater: A brazing liquid composition in which 9 g/m ² of acrylic resin as a binder and 1 g/m ² of acrylic resin as a binder were dispersed in a solvent was applied and dried at 150° C. for 5 minutes to form a main brazing composition layer.

In Examples 31-40, 91-100 and Comparative Examples 13-16, 37-40, a Zn-containing flux (KZnF ₃ ): 9 g/m ² was applied as a binder using a bar coater to the front and back surfaces of the flat multi-hole tube. 1 g/m ² of acrylic resin in a solvent was applied and dried at 150° C. for 5 minutes to form a main brazing composition layer.

In Examples 41-50, 101-110 and Comparative Examples 17-20, 41-44, a Zn-containing flux (KZnF ₃ ): 5 g/m ² , non-Zn Containing flux (K _1-3 AlF _6-4 ): 4 g/m ² , Acrylic resin as binder: 1 g/m ² , dispersed in a solvent A brazing liquid composition is applied and dried at 150° C. for 5 minutes. to form a primary brazing composition layer.

Next, a brazing composition was applied by spraying to the short side of the multi-hole flat tube using an air spray valve device manufactured by Sanei Tech Co., Ltd., as shown in FIG. When applying, the multi-hole flat tube may be fixed and the air spray valve device may be moved while applying, or the air spray valve device may be fixed and the multi-hole flat pipe may be moved while applying. At this time, the flat multi-hole tube was fixed and the air spray valve device was moved while applying. In addition, an air spray valve device having a discharge opening diameter of 0.2 mm was used.

In Examples 1 to 10, 71 to 80, 91 to 100 and Comparative Examples 1 to 4, 29 to 32, 37 to 40, Si powder and Zn-containing flux (KZnF ₃ ), and after applying a brazing liquid composition in which an acrylic resin as a binder is dispersed in a solvent (a mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol), drying (150° C. for 5 minutes). Thus, a brazing tube having its outer peripheral surface coated with the first and second brazing composition layers was obtained.
The applied liquid brazing composition consisted of 30 parts Si powder (D(99) particle size 10 μm), 60 parts Zn-containing flux ( _KZnF3 powder: D(50) particle size 2.0 μm), and 10 parts acrylic resin binder. , and 100 parts of a mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol as solvents.

In Examples 11-20, 81-90, 101-110 and Comparative Examples 5-8, 33-36, 41-44, Si powder and Zn-containing flux (KZnF ₃ ), a Zn-free flux (K _1-3 AlF _6-4 ), and an acrylic resin as a binder dispersed in a solvent (a mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol). After applying the product, the product was dried (150° C.×5 minutes) to obtain a brazing tube whose outer peripheral surface was coated with the first and second brazing composition layers.
The applied liquid brazing composition consisted of 30 parts Si powder (D(99) particle size 10 μm), 50 parts Zn-containing flux ( _KZnF3 powder: D(50) particle size 2.0 μm), and Zn-free flux (K _1-3 AlF _6-4 powder: from 10 parts D(50) particle size 2.0 μm), 10 parts acrylic resin binder, 100 parts mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol as solvent It is a brazing liquid composition.

In Examples 21 to 30 and Comparative Examples 9 to 12, a non-Zn-containing flux (K _1-3 AlF _6-4 ) and an acrylic resin as a binder were applied to the short side of the multi-hole flat tube by the above-described method. A mixture of methoxy-3-methyl-1-butanol and isopropyl alcohol) was applied and then dried (150°C for 5 minutes) to obtain the first and second brazing compositions. A brazing tube with a layer covering the outer circumference was obtained.
The applied liquid brazing composition consisted of 90 parts of Zn-free flux (K _1-3 AlF _6-4 powder: D(50) particle size 2.0 μm), 10 parts of acrylic resin binder, 3-methoxy -A liquid brazing composition consisting of 100 parts of a mixture of 3-methyl-1-butanol and isopropyl alcohol.

In Examples 31 to 40, 51 to 60 and Comparative Examples 13 to 16, 21 to 24, Zn-containing flux (KZnF ₃ ) and acrylic resin as a binder were applied to the short sides of the flat multi-hole pipe by the above-described method. A mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol) was applied and dried (150° C. for 5 minutes) to form the first and second brazing compositions. A brazing tube having an outer peripheral surface coated with a material layer was obtained.
The applied liquid brazing composition consisted of 90 parts of Zn-containing flux ( _KZnF3 powder: D(50) particle size 2.0 μm), 10 parts of acrylic resin binder, 3-methoxy-3-methyl-1- A brazing liquid composition comprising 100 parts of a mixture of butanol and isopropyl alcohol.

In Examples 41-50, 61-70 and Comparative Examples 17-20, 25-28, Zn-containing flux (KZnF ₃ ), Zn-free flux (K _1-3 AlF _6-4 ) and acrylic resin as a binder are dispersed in a solvent (a mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol). minutes) to obtain a brazing tube having its outer peripheral surface coated with the first and second brazing composition layers.
The applied liquid brazing composition consisted of 50 parts of Zn-containing flux (KZnF ₃ powder: D(50) particle size 2.0 μm) and 50 parts of Zn-free flux (K _1-3 AlF _6-4 powder: D(50) particle size 2.0 μm), 10 parts of an acrylic resin binder, and 100 parts of a mixture of 3-methoxy-3-methyl-1-butanol and isopropyl alcohol as a solvent.

Tables 1 to 3 show the thickness of the coating film applied to the short sides and the thickness of the coating film applied to the corner portions in Examples 1 to 50 and Comparative Examples 1 to 15.

After applying the liquid brazing composition, it is dried by heating at 150° C. for 5 minutes to volatilize the solvent, and the outer peripheral surface is covered with the previous main brazing composition layer and the first and second brazing composition layers. A brazed tube was obtained.

When manufacturing a brazing tube, the thickness (μm) of the first brazing composition layer formed on the short side of the flat multi-hole tube by the air spray valve device and the short side of the flat multi-hole tube A plurality of brazing tubes were manufactured by changing the thickness (μm) of the second brazing composition layer formed on the corner portions of the tubes. The thickness of each brazing composition layer was adjusted by the injection pressure of the air spray valve device, the distance between the nozzles from the short side of the multi-hole flat tube, and the injection position.
A heat exchanger mini-core body was assembled by fitting brazing tubes coated with a brazing film into the holes formed in the 25 fins arranged in parallel as described above.
This heat exchanger mini-core body was observed to investigate the presence or absence of deformation of the fins, and to investigate peeling of the paint film that occurred when the fins and tubes were fitted.

For the presence or absence of fin deformation, after assembling the heat exchanger mini-core body, a sample in which the fins did not deform at all was judged as Pass A, and a sample in which a part of the fins (bent, broken, or other deformation occurred) was judged to pass. It was judged as disqualified B.
Regarding the peeling of the paint film when fitting the fin and the tube, the sample with no peeling of the paint film was judged as pass A, and the sample with the peeling of the paint film over an area of 1 mm square or more was judged as fail B. It was judged.

The assembled heat exchanger mini-core bodies were brazed by heating to 600° C. for 3 minutes in a brazing furnace in a nitrogen gas atmosphere.
Regarding the heat exchanger obtained by brazing, the center part of the tube in the length direction is bent 90 degrees so that it becomes an L shape in plan view, and the brazed part of the fin is separated from the tube at the bent part. It was confirmed whether or not the fin collapsed due to Samples in which the fins did not collapse were judged as pass A, and samples in which the fins collapsed at even one place were judged as fail B.
The above results are summarized in Tables 1 to 6 below.

As in the samples of Examples 1 to 110, the results of which are shown in Tables 1 to 6, the thickness of the coating film made of the brazing composition formed on the short side of the flat multi-hole tube was in the range of 5 to 30 μm. If so, it was found that the fins do not collapse during bending. The samples of Comparative Examples 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43 are samples with a coating thickness of 3 μm of the brazing composition, but the brazing composition layer is too thin. Therefore, the brazing strength was insufficient, and the fins collapsed during bending. The samples of Comparative Examples 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44 are samples with a brazing composition coating thickness of 32 μm, but the brazing composition layer is too thick. Therefore, stress was applied to the fins during bending, causing the fins to collapse.
It was found that if the thickness of the coating film on the short side corners of the flat multi-hole pipe is in the range of 0.5 to 15 μm, the fins are not deformed when the fins and the flat multi-hole pipe are fitted. However, as in the samples of Comparative Examples 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, and 42, the coating film peeled off at a coating thickness of 17 μm, and Comparative Examples 1, 5, 9, As with samples 13, 17, 21, 25, 29, 33, 37, and 41, when the coating thickness was 0.3 μm, deformation of the fins occurred when the fins and the flat multi-hole tube were fitted.
From this, it can be estimated that the thickness of the coating film on the short side corners of the flat multi-hole pipe is preferably in the range of 0.5 to 15 μm in order to prevent peeling of the coating film and deformation of the fins. .

From these test results, the thickness of the first brazing composition layer formed on the short side of the flat multi-hole pipe is preferably in the range of 5 to 30 μm, and the thickness of the second brazing composition layer formed on the corner portion of the short side is desirable. It has been found that a thickness range of 0.5 to 15 μm is desirable for the thickness of the brazing composition layer.

FIG. 9 shows the results of brazing the corners of a tube with a brazing composition layer applied to the corners as shown in FIG. 4 is a graph showing the results of measurement of changes in the coefficient of friction when the coating composition layer and the aluminum alloy plate forming the fins are rubbed against each other.
FIG. 10 shows the results of measuring the corners of a tube with no brazing composition layer applied to the corners as shown in FIG. FIG. 5 is a graph showing the results of measurement of changes in coefficient of friction when an aluminum alloy and an aluminum alloy forming a fin rub against each other. FIG.

In the results shown in FIG. 9, among the three lines showing the measurement results, the dashed-dotted line indicates the coefficient of friction, the solid line indicates the vertical load, and the dotted line indicates the frictional force.
In the results shown in FIG. 10, among the three broken lines showing the measurement results, the solid line showing a relatively stable value shows the vertical load, and the one-dot chain line and the dotted line, which fluctuate greatly up and down, show the coefficient of friction and the friction force, respectively. indicates

As is clear from a comparison of the results shown in FIG. 9 and the results shown in FIG. 10, fitting a tube provided with a brazing composition layer at the corners as shown in FIG. It can be seen that fitting work can be performed with little variation in both force and coefficient of friction. That is, it can be assumed that the fitting operation of the tube can be performed without deforming the fins.
On the other hand, from the results shown in FIG. 10, when a tube without a brazing composition layer at the corner portion is fitted into the hole of the fin, a large frictional fluctuation occurs. It can be seen that there is a high possibility that the fins will be deformed in this case, assuming that force is applied to fit the tube into the hole.
From these comparisons, when fitting the tube body 12 into the holes 19 of the fins 13, the fitting work can be performed more smoothly if the second brazing composition layer 17 is formed on the corner portion of the tube body 12. I understand. Therefore, there is an effect that the tube main body 12 can be attached without causing deformation of the fins 13 when the tube main body 12 is fitted.

FIG. 11 is a photograph showing an example of the application state of the brazing composition applied to the short side of the multi-hole flat tube by an air spray device.
As shown in FIG. 11, it can be seen that a brazing composition layer capable of completely covering the short sides and corner portions of the multi-hole flat tube can be formed by the air spray device.

According to the brazing tube of one aspect of the present invention, it is possible to prevent the peeling of the brazing composition on the short side surfaces of the flat tube main body, and ensure reliable brazing properties on the short side surfaces of the tube main body. Further, even when the tube is inserted into the holes of the fins and combined with the fins, it is possible to provide a brazing tube that makes it difficult for the brazing composition to peel off and enables reliable brazing.

REFERENCE SIGNS LIST 11 heat exchanger 12 tube body 12A surface wall 12a surface (upper surface)
12B back wall 12b back (lower surface)
12C side wall 12c short side 12d corner 12D channel 12E partition wall 13 fin 14 header pipe 15 main brazing composition layer 16 first brazing composition layer 17 second brazing composition layer 19 hole 20 bent Part 22 Brazing tube 30 Application device 31 Nozzle 32 Spray gun 33 Introduction pipe

Claims (12)

A brazing tube made of aluminum or an aluminum alloy, comprising a flat tube body having a front surface, a back surface and short side surfaces, wherein a brazing composition layer is formed on the front surface side, the back surface side and the short side surfaces. hand,
forming a first brazing composition layer having a thickness of 5 to 30 μm on the short side;
A second brazing composition layer having a thickness of 0.5 to 15 μm is formed on the front side corner portion extending from the front surface to the short side surface and the back side corner portion of the portion extending from the back surface to the short side surface,
A main brazing composition layer is formed on the front surface and the back surface, and
said first brazing composition layer, said second brazing composition layer and said main brazing composition layer comprising at least one of Si powder, Zn-containing flux and non-Zn-containing flux; , a brazing composition layer containing a binder . 1. The first brazing composition layer, the second brazing composition layer and the main brazing composition layer all contain Si powder: 1-5 g/m ² . Brazing tube according to . The first brazing composition layer, the second brazing composition layer, and the main brazing composition layer all contain Zn-containing flux: 3 to 20 g/m ² . 3. The brazing tube according to 1 or 2 . The first brazing composition layer, the second brazing composition layer, and the main brazing composition layer all contain a Zn-free flux: 1 to 10 g/m ² . Item 4. The brazing tube according to any one of items 1 to 3 . The first brazing composition layer, the second brazing composition layer and the main brazing composition layer all contain a binder of 0.2 to 8.5 g/m ² . Brazing tube according to any one of claims 1-4 . The brazing tube according to any one of claims 1 to 5, wherein the tube main body is made of an extruded multi-hole tube having a plurality of flow paths inside. From an air spray device installed facing the short side of a flat tube body having a front surface, a back surface and a short side,
A brazing liquid composition containing at least one of Si powder, Zn-containing flux, and Zn-free flux, and further containing a binder and a solvent is sprayed to form a first brazing material having a thickness of 5 to 30 μm on the short side surface. A second brazing layer having a thickness of 0.5 to 15 μm is applied to a front side corner portion extending from the front surface to the short side surface and a back side corner portion extending from the back surface to the short side surface. A method for producing a brazing tube, characterized by forming a composition layer. 8. The method of manufacturing a brazing tube according to claim 7, wherein a main brazing composition layer containing Si powder: 1-5 g/m ² is formed on the front surface and the back surface of the tube body. A brazing tube according to claim 7 or 8 , characterized in that a main brazing composition layer containing Zn-containing flux: 3-20 g/m ² is formed on the front surface and the back surface of the tube body. Method. A main brazing composition layer comprising a Zn-free flux: 1-10 g/m ² is formed on the front surface and the back surface of the tube body according to any one of claims 7-9 . A method of manufacturing a brazed tube. 11. The method according to any one of claims 7 to 10 , characterized in that a main brazing composition layer containing a binder: 0.2 to 8.5 g/m ² is formed on the front surface and the back surface of the tube body. method of manufacturing a brazing tube. A brazing tube according to any one of claims 1 to 6 and a fin having an elongated hole through which the brazing tube is inserted, wherein the brazing tube is inserted through the elongated hole. , a heat exchanger in which the brazing tube and the fins are brazed, wherein the brazing tube and the fins are brazed by a fillet that is a molten solidified product of the brazing composition layer A heat exchanger characterized by:

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