JP2011021824A - Heat exchanger and method of forming extension part of fin of the heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger increasing a fin pitch. <P>SOLUTION: The heat exchanger is equipped with: a plurality of fins 1 juxtaposed at predetermined intervals; and a pipe penetrating through the fins 1 and expanded to be coupled to the fins 1. The shape of a hole 11 of the fin 1 through which the pipe penetrates is a circle, and the periphery of the circle is a collar part 13 formed orthogonally to a flat part 12 of the fin 1 and along the pipe. An extension part 14 extended from part of an edge of the collar part 13 is made to abut on the fin 1 adjacent to the fin 1 of the collar part 13. The erected shape of the extension part 14 from the edge of the collar part 13 is formed to have approximately the same arcuate shape as that of the collar part 13, and the height H of the extension part 14 is formed to be higher than that h of the collar part 13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

    The present invention relates to a heat exchanger and a method for forming a fin extension portion of the heat exchanger, and more particularly, to a heat exchanger capable of increasing a fin pitch and a method for forming a fin extension portion of the heat exchanger. .

2. Description of the Related Art Conventionally, for example, there is a heat exchanger that can take a fin pitch more than the height of the collar portion (for example, see Patent Document 1).
The fin pitch of this heat exchanger can be made large by the height of the protrusion protruding from the edge of the collar portion. (See FIG. 9 of Patent Document 1).
Japanese Patent Laid-Open No. 10-238981

    However, in the above heat exchanger, there is a problem that the height of the protrusion is small and the fin pitch cannot be increased.

    An object of this invention is to provide the formation method of the extension part of the heat exchanger and the fin of a heat exchanger which were made to remove said problem.

    The heat exchanger of the present invention is a heat exchanger comprising a plurality of fins arranged side by side with a predetermined interval, and a pipe that penetrates the fins and expands and is coupled to the fins. The shape of the hole of the fin through which the pipe passes is a circle, and the circumference of the circle is a collar portion formed so as to be perpendicular to the flat portion of the fin and along the pipe. An extension part extending from a part of the edge part of the part abuts on a fin adjacent to the fin of the collar part, and the rising shape of the extension part from the edge part of the collar part is that of the collar part. It is formed in an arc shape substantially the same as the arc shape, and the height of the extending portion is formed higher than the height of the collar portion.

    Further, the heat exchanger according to claim 2 is the heat exchanger according to claim 1, wherein an extension portion bent toward the outside of the collar portion is formed at the tip of the extension portion.

    Moreover, the formation method of the extension part of the fin of the heat exchanger of Claim 3 forms the convex part which presses a press member on one surface of a metal member, and protrudes from said one surface; The convex portion formed in this pressing step is a concave portion when viewed from the surface opposite to the one surface of the metal member, and the concave portion includes a closed portion facing the opening portion of the concave portion, and the closed portion of the closed portion. The wall is connected to the edge and is opposed to the wall, the shape of the opening of the recess is a circle, the cross-section of the recess is substantially U-shaped, and the blocking portion and the wall have a curved portion. After the pressing step, the punching step of punching the closed portion of the concave portion in an arc shape leaving a tongue-like portion in a plan view on the closed portion of the concave portion, and after the punching step From the wall portion, the tongue portion is folded so that the tongue portion is positioned on an extension line of the wall portion. The extending step for forming the extending portion, and the boundary between the extending portion and the wall portion formed in the extending step have a circular cross section, and the shape of the extending portion is: It is formed in the substantially same circular arc shape as the circular arc shape of the said wall part.

    According to a fourth aspect of the present invention, there is provided a method of forming a fin extension portion of a heat exchanger, wherein a pressing step of pressing a pressing member on one surface of a metal member to form a convex portion protruding from the one surface; The convex portion formed in the pressing step is a concave portion when viewed from the surface opposite to the one surface of the metal member, and the concave portion includes a closed portion facing the opening portion of the concave portion, and the closed portion of the closed portion. The wall is connected to an edge portion and is opposed to the wall portion, and the cross-section of the concave portion is substantially U-shaped, and the blocking portion and the wall portion are connected via a curved portion, and the pressing step Thereafter, in a plan view, the punching step of punching out the blocking portion of the recess in an arc shape leaving a tongue-like portion in the closing portion of the recess, and after the punching step, the tongue-like portion is on the extension line of the wall portion An extending step of folding the tongue-like portion so as to be positioned and forming an extending portion extending from the wall portion; The length of the extending portion formed in the extending step in the direction orthogonal to one surface of the metal member is longer than the length of the wall portion in the direction orthogonal to one surface of the metal member. It is what.

    Moreover, the formation method of the extension part of the fin of the heat exchanger of Claim 5 forms the convex part which presses a press member and protrudes from said one surface on one surface of a metal member, The convex portion formed in this pressing step is a concave portion when viewed from the surface opposite to the one surface of the metal member, and the concave portion includes a closed portion facing the opening portion of the concave portion, and the closed portion of the closed portion. The wall is connected to an edge portion and is opposed to the wall portion, and the cross-section of the concave portion is substantially U-shaped, and the blocking portion and the wall portion are connected via a curved portion, and the pressing step Thereafter, a punching step of punching out the closed portion of the recessed portion leaving a tongue-like portion having a protruding portion on the distal end side in a plan view on the closed portion of the recessed portion, and after the punching step, the protruding portion A folding step of bending the direction away from the recess, and after this folding step, Serial in which tongue has a extension step of forming the extending portion extending from the wall portion by folding the tongue so as to be positioned on the extension of the wall portion.

    Further, the method for forming the fin extension portion of the heat exchanger according to claim 6 includes a pressing step of pressing the pressing member on one surface of the metal member to form a protrusion protruding from the one surface. The convex portion formed in this pressing step is a concave portion when viewed from the surface opposite to one surface of the metal member, and the shape of the opening of the concave portion is a circle. After the pressing step, the convex portion A punching step of punching out the closing portion of the concave portion in an arc shape while leaving the first tongue-like portion and the second tongue-like portion in plan view in the closing portion, and in this punching step, A gap is formed between the tip and the tip of the second tongue-like portion, and the first tongue-like portion and the second tongue-like portion are in a symmetrical positional relationship through the gap in plan view. Yes, after the punching step, the first tongue portion and the second tongue portion are respectively located on an extension line of the wall portion. An extension step of folding the first tongue and the second tongue to form a first extension and a second extension extending from the wall, and the extension The boundary part between the first extension part and the wall part and the boundary part between the second extension part and the wall part formed in the process have a circular cross section and the first extension part. The shape of the protruding portion and the second extending portion is formed in an arc shape that is substantially the same as the arc shape of the wall portion.

    Moreover, the formation method of the extension part of the fin of the heat exchanger of Claim 7 forms the convex part which presses a pressing member and protrudes from said one surface on one surface of a metal member, The convex portion formed in this pressing step is a concave portion when viewed from the surface opposite to the one surface of the metal member, and the concave portion includes a closed portion facing the opening portion of the concave portion, and the closed portion of the closed portion. The wall is connected to an edge portion and is opposed to the wall portion, and the cross-section of the concave portion is substantially U-shaped, and the blocking portion and the wall portion are connected via a curved portion, and the pressing step A punching step of punching out the closing portion of the recess leaving a first tongue-like portion and a second tongue-like portion in plan view in the closing portion of the recess, and in the punching step, the first tongue A gap is formed between the tip of the second portion and the tip of the second tongue-like portion. The first tongue portion and the second tongue portion are in a symmetrical positional relationship, and after the punching step, the first tongue portion and the second tongue portion are respectively the wall portions. The first tongue and the second tongue are folded so as to lie on the extension line of the first extension and the second extension extending from the wall. And a delivery process.

    According to the heat exchanger according to claim 1, the rising shape from the edge portion of the collar portion of the extending portion extending from a part of the edge portion of the collar portion is substantially the same arc shape as the arc shape of the collar portion. Because it is formed, cracks can be prevented from occurring at the boundary part between the collar part and the extension part, and the height of the extension part is added to the height of the collar part at the part that regulates the fin interval. At the same time, the height of the extending portion can be formed higher than the height of the collar portion, and the fin interval can be made larger.

    Further, according to the heat exchanger according to claim 2, in addition to the effect of the invention according to claim 1, the overhanging portion bent toward the outside of the collar portion is formed at the tip of the extension portion. Therefore, when manufacturing the heat exchanger by laminating the holes of the fins in alignment and inserting the pipe into the hole and expanding the pipe, it is bent toward the outside of the collar part at the tip of the extension part Since the extended portion is provided, the extended portion can be prevented from entering the hole of the laminated fin, and the extended portion is bent toward the outside of the collar portion at the tip of the extended portion. Therefore, the strength of the extending portion can be improved.

    Further, according to the method of forming the fin extension portion of the heat exchanger according to claim 3, the boundary portion between the extension portion and the wall portion in the extension step is circular in cross section and Since the shape is formed in an arc shape that is substantially the same as the arc shape of the wall portion, it is possible to prevent the boundary portion between the extension portion and the wall portion from being cracked, and the portion that regulates the fin interval By adding the height of the tongue portion to the height of the wall portion, it is possible to manufacture the fins of the heat exchanger that can increase the fin interval.

    According to the method for forming the fin extension portion of the heat exchanger according to claim 4, the pressing that presses the pressing member and forms the convex portion protruding from the one surface on one surface of the metal member. The protrusion formed in the step and the pressing step is a recess when viewed from the surface opposite to the one surface of the metal member, and the recess includes a closing portion facing the opening of the recess, and the blocking The wall portion is connected to the edge of the portion and is opposed to the wall portion, and the cross section of the concave portion is substantially U-shaped, and the blocking portion and the wall portion are connected via a curved portion, After the pressing step, in a plan view, the punched portion for punching out the closed portion of the concave portion in an arc shape leaving a tongue-like portion in the closed portion of the concave portion, and after the punching step, the tongue-like portion is an extension of the wall portion. An extension work that folds the tongue-like part so as to be positioned on a line and forms an extension part extending from the wall part And the length of the extending portion formed in the extending step in the direction orthogonal to the one surface of the metal member is longer than the length of the wall portion in the direction orthogonal to the one surface of the metal member. That is, since the cross section of the concave portion in the pressing step is substantially U-shaped, the tongue-shaped portion is formed when the tongue-shaped portion in the extending step after the pressing step is folded to form the extending portion extending from the wall portion. It is possible to prevent cracks from occurring at the boundary between the wall and the wall, and to increase the gap between the fins by adding the height of the tongue to the height of the wall. Possible heat exchanger fins can be produced.

Further, according to the method for forming the fin extension portion of the heat exchanger according to claim 5, since the cross section of the recess in the pressing step is substantially U-shaped, the tongue-like portion in the extension step after the pressing step Heat exchanger that can increase the fin interval by adding the height of the tongue-shaped portion to the height of the wall portion to form the extending portion that extends from the wall portion by folding When the heat exchanger fins are stacked when the heat exchanger is manufactured, the protruding portion prevents the tongue from entering the hole through which the adjacent fin pipe passes. be able to.
As a result, it is possible to prevent a trouble from occurring in the step of expanding the pipe and bringing it into close contact with the fin through the hole formed by punching the closed portion of the recess in the punching step.

    Moreover, according to the formation method of the extension part of the fin of the heat exchanger of Claim 6, the boundary part and 2nd extension part of the 1st extension part and wall part which were formed in the extension process The boundary between the wall and the wall is such that the cross-section is a circle (for example, the boundary between the first extension and the wall and the outside and the inside of the boundary between the second extension and the wall And forming the boundary portion to be a circle.) Therefore, it is possible to prevent the boundary portion from being cracked, and to prevent the fin interval from being increased. In addition, the height of the first extension part (second extension part) is added to the height, so that the fins of the heat exchanger having a large fin interval can be manufactured.

    Moreover, according to the formation method of the extension part of the fin of the heat exchanger of Claim 7, since the cross section of the recessed part in a press process is substantially U shape, it is the 1st in the extension process after a press process. When forming a first extension part (second extension part extension part) that extends from the wall part by folding the tongue part (second tongue part), the first tongue part (second extension part) Can be prevented from cracking at the boundary portion between the wall portion and the first tongue portion (second tongue portion) in the extending step by extending from the wall portion. In order to form the first extension part (second extension part extension part) that performs the first tongue-like part (second tongue-like part) at the height of the wall part, the part that regulates the fin interval The fins of the heat exchanger that can increase the gap between the fins can be manufactured.

An embodiment of the heat exchanger of the present invention will be described with reference to the drawings.
In FIG. 1, E is a heat exchanger. As is well known, the heat exchanger E has a plurality of fins 1 arranged in parallel with a predetermined interval, and fins 1 that penetrate through the fins 1 and are expanded. And a pipe (meander-like refrigerant pipe) 2 coupled to the. The thickness of the fin 1 is, for example, about 0.1 mm to about 1 mm.
In addition, in FIG. 1, the linear part of the pipe 2 is shown in figure, and the U-shaped pipe which connects the linear part and the linear part of the pipe 2 is not illustrated.

The shape of the hole 11 of the fin 1 through which the pipe 2 penetrates is a circle (the diameter of the circle is, for example, about 7 mm) as shown in FIG. The collar portion 13 is formed so as to be orthogonal to the pipe 2 (see FIG. 3).
Reference numeral 14 denotes an extended portion that extends from a part of the edge of the collar portion 13, and the extended portion 14 is adjacent to the fin 1 (fin 1 </ b> A in FIG. 1) of the collar portion 13. (The fin 1B in FIG. 1) is held in contact with the fins 1, 1,...
And the rising shape from the edge part of the collar part 13 of the extension part 14 is formed in the substantially same arc shape as the arc shape of the collar part 13, as shown in FIG.3, FIG6 and FIG.7, and the extension part The height H of 14 is, for example, 0.6 mm to 4.8 mm. The height h of the collar portion 13 is, for example, 1.2 mm. Note that the height H of the extended portion 14 may be formed higher than the height h of the collar portion 13.
Reference numeral 15 denotes an overhanging portion. The overhanging portion 15 is formed by being bent toward the outside of the collar portion 13 on both sides of the tip of the extending portion 14.

Therefore, according to the heat exchanger E described above, the rising shape of the extended portion 14 extending from a part of the edge portion of the collar portion 13 from the edge portion of the collar portion 13 is substantially the arc shape of the collar portion 13. Since they are formed in the same arc shape, it is possible to prevent the boundary portion between the collar portion 13 and the extending portion 14 from being cracked, and the portion that regulates the fin interval is set to the height h of the collar portion 13. By adding the height H of the extending portion 14, the fin interval can be made larger. That is, the fin pitch can be increased.
Moreover, since the extension part 15 bent toward the outer side of the collar part 13 is formed at the tip of the extension part 14, as shown in FIG. 2, the holes 11, 11,. When the pipe 2 (FIG. 1) is inserted into the holes 11, 11... And the pipe 2 is expanded with a punch (not shown) to manufacture the heat exchanger E, the tip of the extension portion 14. Since there is an overhanging portion 15 that is bent toward the outside of the collar portion 13, even if the extending portion 14 is slightly inclined toward the hole 11 side of the fin 1, In addition, the extension portion 15 is bent toward the outer side of the collar portion 13 at the tip of the extension portion 14, so that the strength of the extension portion 14 can be improved. You can plan.

The above-mentioned heat exchanger E can be made as follows.
On one surface of a metal member (for example, aluminum), a pressing member (not shown) is pressed to form a convex portion that protrudes from the one surface [pressing step (see FIGS. 4A and 4B)].
The convex portion formed in this pressing step is a concave portion 1a when viewed from the surface opposite to one surface of the metal member, and the shape of the opening portion of the concave portion 1a is a circle. It consists of a closed portion 1b that faces the opening, and a wall portion 1c (collar portion 13) that is connected to the edge of the closed portion 1b and faces it, and the cross section of the recess 1a is preferably substantially U-shaped. The blocking portion 1b and the wall portion 1c (collar portion 13) are connected via the bending portion R.

After the pressing step, the closed portion 1b of the concave portion 1a is provided with a first tongue-like portion 14 'having projecting portions 15 and 15 on the distal side and a projecting portion 15 and 15 on the distal side in plan view. The closing portion 1b of the concave portion 1a is punched with a punch (not shown) leaving the second tongue-shaped portion 14 'having [see the punching step in FIGS. 5 (a) and 5 (b)].
In this punching step, a gap S is formed between the tip of the first tongue 14 'and the tip of the second tongue 14', and the first tongue is seen through the gap S in plan view. 14 'and 2nd tongue-like part 14' have a symmetrical positional relationship [refer to pressing process Drawing 5 (b)].

After this punching step, the overhanging portions 15, 15, 15, and 15 are bent using a mold (not shown) in a direction away from the recess 1a [bending step (see FIGS. 6A and 6B)].
After this bending step, the molds C, D, D (FIG. 5) are arranged so that the first tongue portion 14 ′ and the second tongue portion 14 ′ are located on the extension lines of the wall portion 1c (collar portion 13). 7) to fold the first tongue portion 14 ′ and the second tongue portion 14 ′ and extend the first extension portion (extension portion) 14 extending from the wall portion 1c (collar portion 13). And a second extension part (extension part) 14 are formed [see extension process FIGS. 8A and 8B]. The molds D and D are provided with voids (not shown) for receiving the overhang portions 15 and 15.
In addition, the boundary part of the 1st extension part 14 and wall part 1c (collar part 13) formed in this extension process, and the boundary of the 2nd extension part 14 and wall part 1c (collar part 13) are formed. The section has a circular cross section, and the shapes of the first extension portion 14 and the second extension portion 14 are formed in substantially the same arc shape as the arc shape of the wall portion 1c (collar portion 13). .
As shown in FIG. 2, the fins 1 manufactured in this way are stacked so that the holes 11, 11,... Of the fins 1 coincide with each other, and the pipe 2 (FIG. 1) is inserted into the holes 11, 11. After the insertion, the pipe 2 is expanded with a punch (not shown) to manufacture the heat exchanger E.

    Therefore, according to the method for forming the fin extension portion of the heat exchanger described above, since the cross section of the recess 1a in the pressing step is substantially U-shaped, the first tongue shape in the extension step after the pressing step When the first extension part (second extension part extension part) 14 extending from the wall part 1c (collar part 13) by folding the part (second tongue-like part) 14 'is formed, the first It is possible to prevent the boundary portion between the tongue-like portion (second tongue-like portion) 14 ′ and the wall portion 1 c (collar portion 13) from cracking, and the first tongue-like portion in the extending step In order to form the 1st extension part (2nd extension part extension part) 14 which folds (2nd tongue-like part) 14 'and extends from wall part 1c (collar part 13), fin space | interval is formed. The fin of the heat exchanger that can increase the interval between the fins by adding the height of the first tongue-like part (second tongue-like part) to the height of the wall part to be regulated It can be produced. As a result, the heat exchanger E having a large fin pitch can be obtained.

In the manufacturing process of the heat exchanger E described above, a plurality of first tongue portions 14 ′ and second tongue portions 14 ′ are formed in the closing portion 1b of one recess 1a. However, the present invention is not limited to this, and one tongue-like portion 14 ′ may be used. Usually, in the heat exchanger E, since there are a plurality of holes 11 through which the pipe 2 is passed through one fin, if one tongue-like portion 14 ′ is provided for each hole 11, the fin interval It is because it can hold.
Further, in the manufacturing process of the heat exchanger E described above, the extended portion 15 that is bent toward the outside of the collar portion 13 is formed at the tip of the extended portion 14, but in the present invention, However, the present invention is not limited thereto, and in some cases, the overhanging portion 15 may be punched in the punching process so as not to be formed.

FIG. 1 is a schematic cross-sectional view of a heat exchanger according to an embodiment of the present invention. FIG. 2 shows a process of manufacturing the heat exchanger of FIG. 1, and is a schematic cross-sectional view showing a state in which fins are stacked with the fin holes aligned. FIG. 3 is a schematic perspective view of the single fin of FIG. 2 as viewed obliquely from above. 4A and 4B show the manufacturing process of the fins. FIG. 4A is a schematic cross-sectional view showing a state in which the concave portion is formed by the pressing process, and FIG. 4B is a cross-sectional view of FIG. It is a schematic plan view. FIG. 5A is a schematic cross-sectional view showing a state of being punched by the punching process, and FIG. 5B is a schematic plan view of FIG. 5A. FIG. 6A is a schematic cross-sectional view showing a state in which a part of the member left by the punching process is raised, and FIG. 6B is a schematic plan view of FIG. 6A. FIG. 7 is a schematic cross-sectional view of a state before the mold is introduced in order to raise the extending portion extending from a part of the edge portion of the collar portion formed in FIG. FIG. 8A is a schematic cross-sectional view showing a state in which an extended portion extending from a part of the edge portion of the collar portion formed in FIG. 6A is raised, and FIG. FIG. 9 is a schematic plan view of FIG.

E Heat exchanger 1 Fin 2 Pipe 11 Hole 12 Flat part 13 Collar part 14 Extension part

Claims (7)

A plurality of fins arranged side by side with a predetermined interval;
A heat exchanger provided with a pipe penetrating through the fin and expanded and coupled to the fin,
The shape of the hole of the fin through which the pipe passes is a circle,
The circumference of this circle is a collar portion formed so as to be perpendicular to the flat portion of the fin and along the pipe,
The extended portion extending from a part of the edge of the collar portion abuts on the fin adjacent to the fin of the collar portion,
The rising shape from the edge of the collar portion of the extension portion is formed in an arc shape substantially the same as the arc shape of the collar portion,
The heat exchanger is characterized in that a height of the extending portion is formed higher than a height of the collar portion. The heat exchanger according to claim 1, wherein an extension portion that is bent toward the outside of the collar portion is formed at a tip of the extension portion. A pressing step of pressing a pressing member on one surface of the metal member to form a protrusion protruding from the one surface;
The convex portion formed in this pressing step is a concave portion when viewed from the surface opposite to one surface of the metal member, and the concave portion includes a closed portion facing the opening portion of the concave portion and an edge of the closed portion. The concave portion has a circular shape, the concave portion has a substantially U-shaped cross section, and the blocking portion and the wall portion are interposed via a curved portion. Connected,
After the pressing step, a punching step of punching out the closed portion of the concave portion in a circular arc shape, leaving a tongue-like portion in the closed portion of the concave portion,
After this punching step, an extending step of folding the tongue-like portion to extend from the wall portion so that the tongue-like portion is located on an extension line of the wall portion;
The boundary portion between the extending portion and the wall portion formed in the extending step has a circular cross section, and the shape of the extending portion is formed in an arc shape substantially the same as the arc shape of the wall portion. A method for forming an extended portion of a fin of a heat exchanger. A pressing step of pressing a pressing member on one surface of the metal member to form a protrusion protruding from the one surface;
The convex portion formed in the pressing step is a concave portion when viewed from the surface opposite to the one surface of the metal member, and the concave portion includes a closed portion facing the opening portion of the concave portion, and an edge of the closed portion. The cross section of the concave portion is substantially U-shaped, and the blocking portion and the wall portion are connected via a curved portion,
After the pressing step, the punching step of punching the closed portion of the concave portion in an arc shape, leaving a tongue-like portion in a plan view on the closed portion of the concave portion,
After this punching step, an extending step of folding the tongue-like portion to extend from the wall portion so that the tongue-like portion is located on an extension line of the wall portion;
The length of the extending portion formed in this extending step in the direction orthogonal to one surface of the metal member is longer than the length of the wall portion in the direction orthogonal to one surface of the metal member. A method for forming a fin extension portion of a heat exchanger. A pressing step of pressing a pressing member on one surface of the metal member to form a protrusion protruding from the one surface;
The convex portion formed in this pressing step is a concave portion when viewed from the surface opposite to one surface of the metal member, and the concave portion includes a closed portion facing the opening portion of the concave portion and an edge of the closed portion. The cross section of the concave portion is substantially U-shaped, and the blocking portion and the wall portion are connected via a curved portion,
After the pressing step, a punching step of punching out the closed portion of the concave portion leaving a tongue-like portion having a projecting portion on the distal end side in a plan view on the closed portion of the concave portion;
After this punching step, a bending step of bending the overhanging portion in a direction away from the concave portion;
After this bending step, an extending step of forming an extending portion that extends from the wall portion by folding the tongue-like portion so that the tongue-like portion is positioned on an extension line of the wall portion;
A method of forming a fin extension portion of a heat exchanger. A pressing step of pressing a pressing member on one surface of the metal member to form a protrusion protruding from the one surface;
The convex portion formed in this pressing step is a concave portion when viewed from the surface opposite to one surface of the metal member, and the shape of the opening portion of the concave portion is a circle,
After the pressing step, a punching step of punching out the closed portion of the concave portion in an arc shape, leaving the first tongue-like portion and the second tongue-like portion in plan view in the closed portion of the concave portion;
In this punching step, a gap is formed between the tip of the first tongue-like portion and the tip of the second tongue-like portion, and in plan view, the first tongue-like portion and the The second tongue is in a symmetrical positional relationship,
After the punching step, the first tongue and the second tongue are placed so that the first tongue and the second tongue are positioned on the extension line of the wall, respectively. An extension step of folding and forming a first extension part and a second extension part extending from the wall part;
The boundary part between the first extension part and the wall part and the boundary part between the second extension part and the wall part formed in the extension step are circular in cross section, and The shape of the extension part of 1 and the 2nd extension part is formed in the arc shape substantially the same as the arc shape of the said wall part. The formation method of the extension part of the fin of the heat exchanger characterized by the above-mentioned. A pressing step of pressing a pressing member on one surface of the metal member to form a protrusion protruding from the one surface;
The convex portion formed in this pressing step is a concave portion when viewed from the surface opposite to one surface of the metal member, and the concave portion includes a closed portion facing the opening portion of the concave portion and an edge of the closed portion. The cross section of the concave portion is substantially U-shaped, and the blocking portion and the wall portion are connected via a curved portion,
After the pressing step, a punching step of punching out the closed portion of the recess leaving the first tongue-like portion and the second tongue-like portion in a plan view on the closed portion of the recessed portion;
In this punching step, a gap is formed between the tip of the first tongue-like portion and the tip of the second tongue-like portion, and in plan view, the first tongue-like portion and the The second tongue is in a symmetrical positional relationship,
After the punching step, the first tongue and the second tongue are placed so that the first tongue and the second tongue are positioned on the extension line of the wall, respectively. An extension step of folding and forming a first extension part and a second extension part extending from the wall part;
A method of forming a fin extension portion of a heat exchanger.

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