JPS6160221A - Formation of thin metallic plate - Google Patents

Abstract

PURPOSE:To obtain a hole made in the wall enabling the close contact sufficiently with a tube expansion of the pipe which is inserted into a rise wall hole by piercing the apex of a projecting part with re-drawing the projecting part which is formed with bulging to the cylinder, etc. having the prescribed height in case of forming the wall hole rising to the one side part of a plate face on the inner peripheral edge of the hole part. CONSTITUTION:A projecting part 11A is formed with a bulging formation on the thin metallic plate 10 of Al alloy, etc. to be made the fin plate of a heat exchanger. It is then worked to the projecting part 11B of a drum head circular or conical shape having the prescribed height H1 by performing more than one time of re-drawing work. Thereafter the re-drawing work is performed so as to make the height of the projecting part less than 85% of H1 and the projecting part 11C of a circular or conical cylindrical shape having the height H2 is made. With said re-drawing work numerous plate folds 18 are radially formed along the radial direction on the plate surface of the base end periphery of the projecting part 11C. The apex 19 of the projecting part 11C is then subjected to a piercing work and an aperture part 20 is formed. The rising wall hole 3 having the plate folds 18 and a collar part 4 on the inner peripheral edge can be thus formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applied to an inner periphery of an aluminum alloy fin plate of a heat exchanger, such as a hole for inserting a tube! The present invention relates to a method of forming a standing wall hole having a collar in a thin metal sheet.

2. Description of the Related Art In general, in a fin plate type heat exchanger, as shown in FIG. 4, a fin plate 1 made of an aluminum alloy or the like is made of copper or aluminum alloy, through which a cooling medium or heat medium, such as Freon, flows. It is necessary to form an upright wall hole 3 for inserting the tube 2 made of aluminum. The rise I in this rise wall hole 3! (partially empty)
The fin plate 4 is brought into close contact with the tube 2 to improve heat conduction from the tube 2 to the fin plate 1, and at the same time, the height of the collar portion 4 allows the fin plate 1A to be in close contact with the other fin plate 1A that is parallel to the fin plate 1A. It also plays the role of regulating the interval between. The tip of the collar portion 4 is usually processed to form a flared portion 5 with a curved cross section to prevent other fin plates 1A from biting into it.

Conventionally known processing methods for forming the upright wall holes 3 of the fin plate 1 as described above include (a) one-way drilling method, (b) burring method, and (c) ironing method.

For example, the draw one method of (A) above is shown in FIGS. 5(A) to (F
), first stretch forming (A) is performed, followed by several stages of re-drawing (B) and (C), then piercing (D), followed by burring (
A part of the collar is formed by E), and finally a flared part is formed by flaring (F). In addition, the burring method (b) above can be used, for example, in FIGS. 6(A) to (
As shown in C), a hole is first formed by piercing (A), followed by burring (B) and flaring (C). Furthermore, in the ironing method (c), as shown in FIGS. 7(A) to (D), for example, piercing (A) and burring (B) are performed in the same manner as the burring method, and then ironing is performed. The tip of a portion of the collar is thinned by (C), and finally a flaring process (D) is applied.

All of these processing methods have piercing, burring, and flaring in common, and the drilling in these processes is important because it determines the height of the empty part and the spacing between adjacent fin plates. This is a contributing factor.

Problems to be Solved by the Invention By the way, when actually assembling the fin plate in which the upright wall holes are formed as described above as a heat exchanger, after inserting a tube made of a steel pipe or an aluminum alloy pipe into the upright hole, In order to bring the outer peripheral surface of the tube into close contact with a portion of the collar of the rising wall hole, the tube is usually expanded from the inside. In this tube expansion process, a considerable force is applied from the tube to the rising wall hole, and tensile stress acts on the rising wall hole in the circumferential direction. When the tube is expanded to a large extent in order to achieve sufficient adhesion, the upright wall hole expands and deforms due to tensile stress, and eventually breaks, which may make it impossible to obtain sufficient adhesion between the fin plate and the tube. In other words, in home room coolers, etc., the thickness of the fin plate is 0.10~
G, 121, which is extremely thin and a soft aluminum plate is used to obtain sufficient workability, so the strength of the upright wall hole is low, and when the tube is expanded to a large extent, tensile stress in the circumferential direction In some cases, the inner peripheral edge of the hole expands and deforms without being able to withstand the pressure, and eventually a portion of it breaks, causing the tube to rise and not be sufficiently tightly attached to the wall hole, resulting in a decrease in heat exchange efficiency.

This invention was made in view of the above circumstances, and even when the strength of the upright wall hole is increased and the expansion ratio of the tube inserted through the upright wall hole is increased, the upright wall hole may expand and deform or break. It is an object of the present invention to provide a method for forming a rising wall hole in a thin metal plate, which effectively prevents the tube from being damaged and is always in sufficient contact with the tube.

Means for Solving the Problems The method of the first invention involves performing overhang molding on the thin metal plate when forming a rising wall hole in a thin metal plate having a wall rising to one side of the plate surface at the inner peripheral edge of the hole. A convex portion having a predetermined height is formed on the surface of a thin metal plate, and then the convex portion is re-drawn so that its height is 85% or less of the height of the previous step, In addition to processing the convex part into a cylindrical or elliptical shape, radial wrinkles are generated on the plate surface around the base end of the convex part, and a hole is formed by piercing the top surface of the convex part. This is a characteristic feature.

Further, the method of the second invention is similar to the first invention, in which gold 1i1
After forming a convex part on the surface of the thin metal plate by overhanging the +l plate, the convex part is re-drawn once or twice or more to form a truncated cone shape or a truncated conical shape having a predetermined width. The convex part is shaped like a truncated elliptical truncated cone, and then the convex part is re-drawn so that its height is 85% or less of the previous height to form a cylindrical or elliptical cylindrical shape. This is characterized by processing the protrusion into a protrusion, creating radial wrinkles on the plate surface around the proximal end of the protrusion, and further piercing the top surface of the protrusion to form a hole.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION The method of the present invention will be described in detail below with reference to FIGS. 1 to 3.

Figures 1(A) to (D) and Figures 2(A) to (D) show the method of the present invention step by step. As shown in FIG. 2(A), a convex portion 11A is formed by stretch molding on a metal thin plate 10 such as an aluminum alloy thin plate that is to become a fin plate of a heat exchanger. For example, this overhang molding is shown in Figure 3 (
Normally, a spherical-headed punch 12 and die 13 as shown in A) are used to form a spherical-headed convex portion 11A, but when ultimately forming an elliptical cylindrical rising wall hole, The convex portion 11A having an elliptical head may be formed using a punch having an elliptical head.

Next, as shown in FIG. 1(B) and FIG. 2(B), re-drawing is performed once or twice or more to form a truncated conical shape or a truncated elliptic truncated conical shape to a predetermined height. The convex portion 11B is processed to have Hl. This re-drawing process is performed, for example, as shown in Figure 3 (B
) A punch 14 and a die 15 having a truncated conical shape or a truncated elliptic conical shape may be used. In addition, this re-drawing process obtains a predetermined height Hl depending on the height of the empty portion of the rising wall hole to be finally obtained (i.e., depending on the spacing between adjacent fin plates in the case of a fin plate for a heat exchanger). Do this an appropriate number of times, one or more times.

After that, as shown in Fig. 1 (C) and Fig. 2 (C), re-drawing is performed to reduce the forming height so that the height of the convex portion becomes 85% or less of Hl, and a cylinder with a height H2 is formed. The convex portion 11C is shaped like a cylinder or an elliptic cylinder. That is, for example, in Figure 3 (
Using the punch 16 and die 17 shown in C), the molding height Hl at the stages of FIGS. 1(B) and 2(B) is
A cylindrical or elliptic cylindrical convex portion 11G having a height H2 that is 85% lower than that of the cylindrical portion is formed. By applying the re-drawing process to reduce the molding height in this way, many plate wrinkles are formed radially along the radial direction on the plate surface around the base end of the cylindrical or elliptical convex portion 11C. be done. Note that the forming height H2 of the re-drawing process is the height Hl of the previous stage.
When the height exceeds 85% of Hl, almost no radial plate wrinkles 18 occur, and therefore the forming height H2 is 85% of Hl.
It is necessary to do the following.

In this way, radial plate wrinkles 18 are formed on the plate surface around the proximal end.
After forming a cylindrical or elliptical convex portion 11G having a shape, a known piercing process is performed on the top surface 19 of the convex portion 11C, as shown in FIG. 1(D) and FIG. 2(D). The hole 81S20 is formed as shown in FIG.

This process creates radial plate wrinkles 18 on the surrounding plate surface.
This means that a rising wall hole 3 having a collar portion 4 on the inner peripheral edge is formed. Therefore, after this, by performing burring processing as necessary and further performing flaring processing as necessary, a rising wall hole having a flared portion 5 (see Fig. 4), which is normally required for a fin plate for a heat exchanger, can be obtained. can get. Of course, depending on the application, the burring or flaring process of Piercing II can be omitted.

In the above explanation, after the stretch forming shown in FIGS. 1(A) and 2(A), re-drawing shown in FIGS. 1(B) and 2(B) is performed to obtain a predetermined height. The convex portion 11A of Hl was formed, and then the re-drawing process shown in FIG. 1(C) and FIG. 2(C) was performed to reduce the forming height. If the height of the collar part 4 can be small, the re-drawing process shown in Fig. 1 (8) and Fig. 2 (B) can be omitted, and the height of Fig. ) to obtain a convex part with a height Hl, and immediately after that, the convex part shown in Fig. 1 (
C), molding height decrease (H1 → H2) shown in Figure 2 (C)
A re-drawing process may be performed to generate radial plate wrinkles 18.

Effect: The upright wall hole 3 formed as described above, that is, the plate wrinkles 1 along the radial direction on the plate surface (plane part) around the hole.
In the upright wall hole 3 where 8 is formed, the strength around the hole is structurally increased by the radial plate wrinkles 18. Therefore, even if the tube 2 made of a steel pipe or an aluminum alloy pipe is inserted into the upright wall hole 3 and the tube 2 is sufficiently expanded as shown in the fourth section, the periphery of the upright wall hole 3 will be expanded and deformed. This effectively prevents the tube from bending or breaking, and therefore the tube 2 can be brought into close contact with the collar portion 4 of the upright wall hole 3.

Furthermore, especially when the method of the present invention is applied to a fin plate for a heat exchanger, the radial plate wrinkles 18 around the rising wall holes 3 of the fin plate generate turbulence in the fluid flowing between the adjacent fin plates 1. It also serves to promote heat transfer between the fluid and the fin plate.

Effects of the Invention As is clear from the above explanation, the method of this invention has the following effects:
A rising wall hole with high strength around the hole can be formed, and therefore, when a tube is inserted into the rising wall hole formed by the method of this invention and the tube is expanded, the surrounding area of the rising wall hole is expanded. This effectively prevents deformation or breakage, so make sure to fully cover the tube and the empty part of the rising wall hole! can be made l. Therefore, if the method of the present invention is applied to forming a fin plate for a heat exchanger, the tube and the collar part of the rising wall hole can be sufficiently tightened to improve heat transfer between them and improve the heat exchange efficiency. Can be done. In addition, when applied to fin plates for heat exchangers as described above, the radial plate wrinkles around the upright wall holes generate turbulence in the fluid passing between the fin plates, improving heat transfer between the fluid and the fin plates. Therefore, the heat exchange rate can be further improved.

[Brief explanation of drawings]

Figures 1 (A) to (D) are oblique W1 views of a gold ml plate to show step by step each step of the method of the present invention, and Figures 2 (A) to (
D) is also a cross-sectional view of a gold IA fermentation plate to show step by step each step of the method of this invention, and FIGS. 3(A) to (C) are the steps of FIGS. 1(A) to (C), respectively. FIG. Fig. 4 is a line cross-sectional view showing a conventional normal rising wall hole in a fin plate of a heat exchanger, Figs. 6th WU (A)-(C)
7A to 7D are schematic diagrams showing step-by-step a conventional burring method, and FIGS. 7A to 7D are schematic diagrams showing step-by-step an ironing method as a conventional method. 3...Rising wall hole, 4...Rising wall (empty part)
, 10... metal thin plate, 11A, 11B, 11C...
・Protrusion, 18... Board wrinkles. Applicant Sky Aluminum Co., Ltd. Agent Patent Attorney Yutaka 1) Hisashi Take (one idiot) Figure 1 (A) (B) Figure 2 (C) (D) (C) (D) Figure 5 (A) Yo f ====) Yo (Fh = "1000th Figure 6 (A) □ Figure 7 (A) -=-=-≠ (El)-" Ninishikon

Claims (2)

[Claims] (1) When forming an upright wall hole in a thin metal plate with a wall rising to one side of the plate surface at the inner circumferential edge of the hole, the thin metal plate is stretched to form a predetermined height on the plate surface of the thin metal plate. A convex portion is formed, and then the convex portion is re-drawn so that its height is 85% or less of the height of the previous step, and processed into a cylindrical or elliptical convex portion. A method for forming a thin metal sheet, the method comprising: generating radial wrinkles on the plate surface around the base end of the convex portion, and further performing piercing on the top surface of the convex portion to form a hole. (2) When forming a rising wall hole in a thin metal plate having a wall rising to one side of the plate surface at the inner peripheral edge of the hole, the thin metal plate is subjected to overhang molding to form a convex portion on the plate surface of the thin metal plate, Subsequently, the convex portion is redrawn once or twice or more to form a convex portion in the shape of a truncated conical or truncated elliptic cone having a predetermined height, and then the convex portion is drawn again. Re-drawing is performed so that the height is 85% or less of the previous height, forming a cylindrical or elliptical convex part, and creating radial wrinkles on the plate surface around the base of the convex part. 1. A method for forming a thin metal sheet, the method comprising: generating a hole, and further piercing the top surface of the convex portion to form a hole.