JPH11222823A - Curved external facing panel and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity, quality stability, and workability. SOLUTION: This external facing panel 1 for an elevated road is made of a metallic flat sheet by sheet metal working and roughly constituted of both right and left side folded steps 2, 3 mutually cranked in a line symmetry and an intermediate curved part 4 therebetween. A number of slits 5, 5' having no opened edge are bored in a folded fashion so as to stride over both sides. The external facing panel 1 for an elevated road is parallelly arranged in the longitudinal direction of a ballast part in a state extended down at the side end of the ballast part of the elevated road.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curved exterior plate for covering a structure or an apparatus such as an elevated road, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In an elevated road, the bottom surface of a roadbed is exposed from the ground. Also, a vehicle 37 traveling on an elevated road 38
There is also a problem that noise such as leaks out from the bottom of the track floor. Therefore, from the viewpoint of improving aesthetics and preventing noise,
Conventionally, as shown in FIG. 6, there has been an elevated road exterior plate (hereinafter, also simply referred to as a road exterior plate) that covers the lower part of the roadbed. By the way, as shown in FIG. 21, the conventional road exterior plate 1c is configured such that a curved intermediate roll portion 4c and first and second bent step portions 2c, 3c which are bent are separated. And thereafter, as shown in FIG.
These are welded to form an integral structure.
Conventionally, the road exterior plate 1c having such a structure is provided with the gap 3
0 and was arranged side by side in the longitudinal direction of the roadbed portion 31.

[0003]

However, in the above-mentioned conventional road exterior plate 1c, as described above, separate members are formed by roll bending or bending, and these are welded to each other. Because it is formed by
It takes a lot of time and effort to manufacture, and is not suitable for mass production.
There is a drawback that the welded portion may be damaged due to insufficient strength, and rust easily occurs. Further, there is also a problem that the appearance is poor due to the welded structure, and it is difficult to produce a stable quality.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a curved exterior plate which is suitable for mass production, is excellent in quality stability, and is easy to construct, and a method of manufacturing the same.

[0005]

In order to solve the above-mentioned problems, the invention according to the first aspect is directed to a method in which a metal plate is replaced with an optional first material.
According to the curved armor plate of the structure or the device formed by bending and bending along the direction of the above, by bending the crank along the first direction, at least a folding step having two folds The bent step formed at one place is also curved along the first direction, and the bent step has a large number of through holes having no open edge. It is characterized in that they are formed at a predetermined interval from each other along the direction of (1).

The invention according to claim 2 relates to a curved exterior plate for exteriorizing an elevated road, wherein the exterior plate is formed by bending and bending a metal plate material in a first direction. Both end portions facing each other in a second direction orthogonal to the direction,
The first and second bent steps having two folds are formed by crank folding substantially line-symmetrically to each other. Each of the bent steps has a large number of through holes having no open edge. Are formed at predetermined intervals from each other along the first direction.

According to a third aspect of the present invention, there is provided the curved exterior plate according to the first or second aspect, wherein all or a part of the through hole is bent by straddling at least any one of the folds. It is characterized by a bent hole.

[0008] The invention described in claim 4 is based on claim 1,
The curved exterior plate according to 2 or 3, wherein all or a part of the through hole is a slit that is long in a second direction orthogonal to the first direction.

According to a fifth aspect of the present invention, there is provided the curved armor plate according to the second aspect, wherein the bent height of the first bent step is larger than the bent height of the second bent step. Are different from each other by the thickness of the metal plate.

According to a sixth aspect of the present invention, there is provided the curved exterior plate according to the second or fifth aspect, wherein the through hole formed in the first bent step portion and the second bent step portion are provided. Are formed at substantially the same interval, and 1 /
It is characterized by being formed shifted from each other by 2/5.

[0011] The invention according to claim 7 is based on claim 2,
The curved exterior panel according to 5 or 6, wherein the exterior panel is in a downwardly hanging state or an upwardly standing state at a side end of the roadbed portion of the elevated road, and in a longitudinal direction of the roadbed portion. Are arranged side by side, and the first bent step portion of any one exterior plate and the second bent step portion of the exterior plate arranged adjacent thereto are overlapped and connected. It is characterized by:

Further, the invention according to claim 8 relates to a method for manufacturing a curved exterior plate according to claim 1, wherein any one of the metal plate materials is used.
A first procedure of punching and forming a large number of through-holes having no open edge at a portion where the bent step portion is to be formed along the direction of the above, and the predetermined portion of the metal plate material along the first direction. A second step of forming a bent step portion having two folds by crank folding, and a third step of performing a curved roll bending of the metal plate material after the first and second steps. It is characterized by becoming.

According to a ninth aspect of the present invention, there is provided a method for manufacturing a curved exterior plate according to the second aspect, wherein a large number of the through-holes having no open edges at both end portions of the metal plate are stamped and formed. A second procedure of crank-folding both side ends of the metal plate material substantially line-symmetrically to form first and second bent steps having two folds; And a third procedure of bending the metal plate material after the second procedure into a curved roll.

[0014]

In the curved exterior plate according to the present invention, the bent portion and the bent step portion have an integral structure by bending and bending the metal plate material. When making this curved exterior plate,
A large number of through-holes that do not have open edges in advance in the bent step,
Along the direction to be curved, it is formed at a predetermined interval from each other, so that the opening does not occur at the upper and lower ends of the bent step, and when there are multiple bent steps, No variation occurs between the bent steps. In addition, no deformation occurs during transport. Therefore, it is suitable for mass production, and has excellent quality stability and ease of construction. In addition, it is preferable that all or a part of the through-hole is a bent hole that is bent by straddling at least one arbitrary fold, and is a slit that is long in a direction orthogonal to the bending direction. Is preferred. Further, in the curved exterior plate for exteriorly covering an elevated road according to claim 2, the through holes are arranged so as to be displaced in the bending direction between the first and second bent steps. In this case, no gap is formed due to polymerization of the through holes, so that it is easy to prevent rainwater from entering, and the workability is improved.
In addition, if the first and second bending steps are configured such that the bending height is changed by substantially the thickness of the plate, the surfaces of the road exterior plates adjacent to each other can be substantially flush with each other at the time of installation. In addition, the workability is improved, and the beauty of the appearance can be ensured.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. The description will be specifically made using an embodiment. FIG. 1 is a perspective view showing the overall structure of a road exterior plate according to an embodiment of the present invention, and FIG.
FIG. 3 is a sectional view taken along line BB of FIG. 1, and FIG.
FIG. 5 is an enlarged partial cross-sectional view showing the bending height of the left and right bending steps of the road exterior plate, and FIG. 5 is a top view of FIG. As shown in FIG. 1 to FIG.
A metal plate material (FIG. 2) having a thickness t of two flat plates, which is formed by sheet metal processing, and bent step portions 2 and 3 formed on both right and left sides thereof;
A central curved portion 4 having a large area sandwiched therebetween, and an intermediate curved portion 4
The upper and lower end portions are bent and formed, and are roughly constituted by mounting portions 11 and 12 which also serve as parting edges.

The center curved portion 4 and the bent steps 2 and 3 on both sides thereof
Means that the curved surfaces are simultaneously bent by a roll bending process described later. As shown in FIG. 2, the left and right bent steps 2 and 3 are formed such that both side ends of a metal plate opposing each other in a width direction orthogonal to the bending direction are crank-folded substantially line-symmetrically with each other. The vertical fold pieces 6, 6 which have two folds, are bent right below the middle curved portion 4, and are defined by the two inner and outer folds 40, 41 (40 ', 41'). ′ And horizontal bent pieces 7 and 7 ′ which are bent substantially horizontally from the lower end and are defined by outer folds 41 (41 ′) and side edges 42 (42 ′) of the metal plate material. It is schematically configured. Note that the vertical bent pieces 6, 6 'and the horizontal bent pieces 7, 7' are named for convenience in FIG. 2, and are not in a vertical state and a horizontal state, respectively, at the time of installation. The upper and lower mounting portions 11 and 12 have a shape as shown in FIG. 3, and are formed by bending in a separate bending step later.

As shown in FIG. 4, if the bending height of the right bending step 2 is h ₁ and the bending height of the left bending step 3 is h ₂ , h ₁ ≒ h in this example. ₂ + t is set, only minute RyakubanAtsu t are formed higher height h ₁ bent towards the right of the bent step portion 2 (the set to h ₂ ≒ h ₁ + t, RyakubanAtsu by the amount of t may be set higher the height h ₂ bent towards the left side of the bent stepped portion 3). This is because, as shown in FIG. 8, the adjacent road exterior plates 1 and 1 are attached to the right bent step 2 at the time of assembly.
Are superposed on each other in a superimposed state. If the dimensions are not as described above, a difference occurs in the height of the intermediate curved portions 4 and 4 of the adjacent road exterior plates 1 and 1, which impairs the appearance and workability. This is to prevent a problem from occurring.

As shown in FIG. 1, slits 5 and 5 'which do not have an open edge at the side edge 42 of the metal plate material (horizontal bent pieces 7 and 7') are provided in the bending step portions 2 and 3 on both right and left sides. ,... Are formed at a substantially same pitch p along the curved longitudinal direction. The slits 5, 5 ', ... in this example are
As shown in the figure, the bent hole extends in a direction perpendicular to the bending direction, and has a bent hole extending between the vertically bent pieces 6, 6 'and the horizontally bent pieces 7, 7'.

According to an experiment conducted by the inventor of the present applicant, when the slits 5, 5 ',... Are opened to the side edges 42 of the metal plate material (horizontal bent pieces 7, 7'),
If the slits are notched, the roll bending process of the left and right bent steps 2 and 3 is good in accuracy, but it is easily deformed at the time of conveyance, and is not suitable for practical use. On the other hand, the bending step 2,
If the slits 3 are not provided with the slits 5, 5 ',..., The curved shape varies on both the left and right sides, and a mouth opening occurs at the upper and lower ends of the bent steps 2, 3, which is inconvenient. Therefore, as in this example, a bent slit 5 having no open edge is used.
If 5 ′,..., No variation occurs in the curved shape on both the left and right sides, and no mouth opening occurs at the upper and lower ends. In addition, deformation during transportation is unlikely to occur.

As described above, a large number of slits 5, 5 ',... Are formed in the left and right bent steps 2, 3 at substantially the same pitch p, as shown in FIG. In addition, the slit 5 of the right bent step 2 and the slit 5 'of the left bent step 3 are formed so as to be shifted from each other by approximately 1 / 2p. This is because if there is no deviation in pitch when the left and right bent steps 2 and 3 of the two road exterior boards 1 to be assembled adjacently overlap, the slits 5, 5 ',... This is because it occurs.

Next, with reference to FIGS. 6 to 8, an example of mounting the road exterior plate 1 having the above configuration will be described. Elevated road 3
8 is a bridge pier 36, a bridge girder 32, and a bridge 3 as shown in FIG.
3. It comprises a roadbed section 31, a central separation wall 34, a sound insulation wall 35, and the like. The road exterior plate 1 of this example is, as shown in FIG.
And by being arranged in the longitudinal direction of the roadbed section 31,
The lower part of the side end of the roadbed portion 31 is exteriorized. This road exterior plate 1
At the position of the bridge girder 32, the mounting portions 11 and 12 are attached in a state of contact with the roadbed portion 31 and the bridge girder 32 as shown in FIG.
7, the left and right bent steps 2 and 3 are arranged in the longitudinal direction of the roadbed 31 as shown in FIG. The left and right bent steps 2 and 3 are connected to each other by overlapping each other. The slits 5, 5 ', ... of the superimposed left and right bent steps 2, 3 are:
As described above, they are displaced from each other by 1 / 2p. Further, as shown in FIG. 8, a caulking material 8 is applied to the overlapping portion to prevent leakage. Also, as shown in FIG.
Leakage prevention measures by caulks 9 and 10 are also applied to the abutting portions between the track members 1 and 12 and the floor 31 and the bridge girder 32.

Next, with reference to FIGS. 12 to 16, a method of manufacturing the road exterior plate 1 having the above-described configuration will be described. First, as shown in FIG. 12, a flat metal plate material 1 having a plate thickness t.
6 Both ends (positions to be bent steps 2 and 3 on both left and right sides)
Then, the slits 5 and 5 'are punched and punched by press working. At this time, the slits 5, 5 ',... Are arranged at the pitch p as described above, and the slits 5 and 5'
The holes are drilled with a displacement of about 1 / 2p in the longitudinal direction. The upper and lower ends of the metal plate 16 are attached to the mounting portions 11 and 12.
Edges 17 and 18 for forming are cut and formed.

Next, both ends of the metal plate 16 are crank-folded substantially line-symmetrically to form bent steps 2 and 3 each having two folds.

Next, a roll bending machine 15 shown in FIG.
Thus, the curved roll bending of the intermediate portion 4 'and the bending step portions 2 and 3 on both the left and right sides are simultaneously performed. That is, as schematically shown in FIG. 13, between the upper roll 13 and the lower rolls 14, the metal plate 16 having slits 5, 5 ′,.
And the upper roll 13 and the lower roll 14 are engaged with each other to perform a roll bending process, thereby forming a roll-bent road exterior plate member 1 ′. As described above, by providing the slits 5, 5 ',..., The bending steps 2, 3 on both the left and right sides can be easily and accurately performed.
The curved shape of the intermediate curved portion 4 and the curved step portions 2 and 3 on the left and right sides can be formed relatively easily in a desired shape by ordinary roll bending technology.

Finally, as shown in FIG. 15, predetermined mounting portions 11 and 12, which also serve as parting edges, are bent at the upper and lower edges 17, 18 of the road exterior plate member 1 'by a bending machine (not shown). Form. Thus, the road exterior board 1 of this example is
Is produced.

Next, the roll bending machine 15 used in this embodiment will be described with reference to FIGS. The roll bending machine 15 is a general one except for the upper roll 13 and the lower rolls 14 and 14.
, A pair of roll stands 25, 25, one upper roll 13 and two lower rolls 14, 14 supported by the roll stands 25, 25, and an upper roll 1
Lifting means 26, 26 for raising and lowering 3 to adjust the gap between the lower rolls 14, 14, an upper roll driving motor 27 connected to the upper roll via a transmission mechanism, and a transmission mechanism And a lower roll driving motor 28 connected to the lower roll, and these are mounted on a base table 29.

The upper roll 13 and the lower roll 14 have a special shape for simultaneously bending the left and right bent steps 2 and 3 and the middle curved portion 4 of the metal plate 16. That is, as shown in FIG. 17, the upper roll 13 has a diameter d ₁
And an enlarged diameter portion 20, 20 ′ having a diameter d ₂ , d ₂ ′ fixed on both sides by screws 23. On the other hand, the lower roll 14 includes a elongated cylindrical portion 21 of diameter d _3, and 'reduced diameter portion 22, 22' that the diameter d ₄ are formed on both sides, d _4, is formed on the side end cylindrical portion 21 And enlarged portions 24, 24 'having the same diameter. The dimensions of each of the diameters d ₁ , d ₂ , d ₂ ′, d ₃ , d ₄ , d ₄ ′ depend on the shape of the bent steps 2, 3 on the left and right sides formed by bending and the curvature of the intermediate bending section 4. It is determined in consideration of the shape and the thickness t.

In order to perform a curved roll bending on the metal plate 16 using the roll bending machine 15 having the above configuration,
The upper roll 13 and the lower roll 14 are arranged facing each other as shown in FIG. 19, and slits 5, 5 ',
... The road exterior plate member 1 'having the perforated and bent steps 2 and 3 formed therein is inserted, and as shown in FIG. 20, the upper roll 13 is moved (downward) to the lower rolls 14 and 14 side. Motor 2
When the power of 7 and 28 is transmitted from the upper roll 13 to the lower roll 14, the lower roll 14 rotates and drives the upper roll 13 so that the intermediate portion 4 'and the bending step portions 2 and 3 on both the right and left sides are simultaneously roll-formed. Is done.

As described above, according to the road exterior plate 1 of this embodiment, the flat metal plate material 16 is bent and bent so that the center bending portion 4 and the bending step portions 2 on both sides thereof are formed.
3 are integrally formed, and when the road exterior plate 1 is manufactured, a large number of slits 5, 5 ',. Since they are formed at predetermined intervals along the direction to be bent, the curved shape does not vary between the left and right bent steps 2, 3, and No mouth opening occurs at the upper and lower ends. No deformation occurs during transport. Therefore, it is suitable for mass production, and can improve quality stability and ease of construction.

Further, according to the roll bending machine 15 of this embodiment, it is possible to smoothly perform the roll bending on the road exterior plate material 1 'having the bent steps 2 and 3 whose both ends are crank-folded. it can. Therefore, the left and right bent steps 2 and 3 and the intermediate curved portion 4 that are curved and rolled can be formed at the same time.
In particular, since slits 5, 5 ',... Are provided in the left and right bending steps 2, 3 for roll bending and bending, highly accurate curved roll bending can be performed.

Although the embodiments of the present invention have been described in detail with reference to the drawings and the like, the specific configuration is not limited to the above-described embodiment, and changes in design and the like can be made without departing from the gist of the present invention. Even if there is, it is included in the present invention. For example,
In the above-described embodiment, the slits 5 and 5 are configured to straddle the vertical bent pieces 6 and 6 'and the horizontal bent pieces 7 and 7'.
6 ', or a zigzag configuration including them. The slits need not necessarily be bent holes, but may be formed in the vertically bent pieces 6, 6 'or in the horizontally bent pieces 7, 7'. Further, as long as there are many through-holes having no open edge, the present invention is not limited to slits, and may be square holes, round holes, or elliptical holes. In the above-described embodiment, the bending heights of the left bending step 3 and the right bending step 2 are different from each other by the thickness of the metal plate. If there is no particular problem in terms of aesthetics, the left and right bending heights may be the same.

In the above-described embodiment, the slit 5 of the right bent step portion 2 and the slit 5 'of the left bent step portion 3 are set so as to be displaced by approximately 1 / 2p. The range of the shift amount is 1 / 2p to 1 / 5p. However, the shift amount is optional, or may be 0 if there is no particular problem in terms of waterproofness.

The road exterior plate 1 of the above-described embodiment has a shape in which the outside of the road has a concave curved surface (FIG. 6), but the curved shape is not limited to this. For example, as shown in FIG. 10, the road exterior plate 1 a in which the outer side of the road has a convex curved surface can exhibit a beautiful feeling, or as shown in FIG. 11, has both a convex curved surface and a concave curved surface. Even with the shape 1b, another beauty can be exhibited. Of course, FIG.
Curved shapes other than FIGS. 10 and 11 may be used.

Further, in the above-described embodiment, the exterior plate is installed so as to hang downward at the side end of the underpass of the elevated road. Road exterior boards can also be applied. Further, in the above-described embodiment, the curved exterior plate is used as the road exterior plate, but the curved exterior plate of the present invention is not limited to this, and is also useful as an exterior plate of a structure such as a building or an apparatus. It is.

[0035]

As described above, according to the curved exterior plate of the present invention, the bent portion and the bent step portion are integrally formed by bending and bending the flat metal plate material. At the time of manufacturing this curved exterior plate, a large number of through-holes having no open edge are formed at predetermined intervals along the direction to be curved in the bent step portion. Therefore, the opening does not occur at the upper and lower ends of the bent steps, and when there are a plurality of bent steps, no variation occurs between the bent steps. In addition, no deformation occurs during transport. Therefore, it is suitable for mass production, and can improve quality stability and ease of construction.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an overall configuration of a road exterior plate according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a partial sectional view showing a bending height of left and right bent steps of the road exterior plate.

FIG. 5 is a top view of FIG. 1;

FIG. 6 is a schematic diagram showing an elevated road on which the road exterior plate is provided.

FIG. 7 is a side view as seen from the direction of arrow D in FIG. 6;

FIG. 8 is a cross-sectional view showing a shape of a superposed portion of a bent step portion on both right and left sides.

FIG. 9 is a cross-sectional view showing an outline of a connection structure between the road exterior plate, a roadbed portion, and a bridge girder.

FIG. 10 is a schematic diagram showing a shape of a road exterior plate according to a modified example of the embodiment and showing an elevated road provided with the road exterior plate.

FIG. 11 is a schematic diagram showing a shape of a road exterior plate according to another modified example of the embodiment, and showing an elevated road provided with the road exterior plate.

FIG. 12 is a diagram for explaining a method for manufacturing a road exterior plate according to one embodiment of the present invention, and is a plan view illustrating a configuration of a metal plate material.

FIG. 13 is a view for explaining the method for manufacturing the road exterior plate, and is a side view of an upper roll and a lower roll.

FIG. 14 is a diagram for explaining the method for manufacturing the road exterior plate, and is a perspective view showing the configuration of the road exterior plate member.

FIG. 15 is a view for explaining the method for manufacturing the road exterior panel, and is a partially cutaway sectional view showing the configuration of the completed road exterior panel.

FIG. 16 is a perspective view showing an external configuration of a roll bending machine used in the embodiment.

FIG. 17 is a front view of an upper roll constituting the roll bending machine.

FIG. 18 is a front view of a lower roll constituting the roll bending machine.

FIG. 19 is a schematic diagram showing upper and lower rolls and a metal plate inserted between the rolls in the roll bending machine.

FIG. 20 is a partial cross-sectional view showing a bent state of the left and right bent steps by the same roll and lower roll.

FIG. 21 is a perspective view for explaining the structure of a conventional road exterior plate.

FIG. 22 is a sectional view of a conventional road exterior plate.

[Explanation of symbols]

1, 1a, 1b Road exterior plate (elevated road exterior plate) 2 Right bent step (first bent step) 3 Left bent step (second bent step) 4 Middle bent part 5,5 'slit 13 upper roll 14 lower roll 15 roll bending machine (processing device for elevated road exterior plate) 16 metal plate material 19,21 cylindrical portion 20,20' enlarged diameter portion 22,22 'reduced diameter portion 31 roadbed portion 32 Bridge girder 38 Elevated road

Claims (9)

[Claims] 1. A curved armor plate of a structure or device formed by bending a metal plate material along an arbitrary first direction, wherein the metal cladding is crank-folded along the first direction. By 2
At least one bent step having two folds is formed, and the formed bent step is also curved along the first direction, and the bent step has an open edge. Many through holes that do not have
A curved armor plate formed at predetermined intervals from each other along the first direction. 2. A curved exterior plate for covering an elevated road, wherein the exterior plate is formed by bending a metal plate material in a first direction, and a second plate orthogonal to the first direction. The opposite side ends in the direction are crank-folded substantially line-symmetrically to each other to form first and second bent steps having two folds. Each bent step has A curved exterior plate, wherein a large number of through-holes having no open edge are formed at predetermined intervals from each other along the first direction. 3. The curved exterior plate according to claim 1, wherein all or a part of the through hole is a bent hole that is bent by straddling at least one of the folds. . 4. The method according to claim 1, wherein all or a part of the through hole is the first hole.
The curved exterior plate according to claim 1, wherein the slit is a slit that is long in a second direction orthogonal to the direction of (b). 5. The bending height of the first bending step is:
The curved armor plate according to claim 2, wherein the bent height of the second bent step portion is different from the bent height of the metal plate member by substantially the thickness of the metal plate material. 6. The through hole formed in the first bent step portion and the through hole formed in the second bent step portion are formed at substantially the same interval, and are formed at a distance of one-half of the interval. 3. The semiconductor device according to claim 2, wherein the two are shifted from each other by 2/5.
Or the curved exterior plate according to 5. 7. The exterior plate is disposed side by side at a side end of the floor of the elevated road in a downwardly hanging state or in an upwardly standing state, and is arranged side by side in the longitudinal direction of the roadbed. Wherein the first bent step portion of the first exterior plate and the second bent step portion of the exterior plate disposed adjacent thereto are overlapped and connected. Item 7. The curved exterior plate according to item 2, 5 or 6. 8. The method for manufacturing a curved exterior plate according to claim 1, wherein the plurality of through-holes having no open edge at a portion where the bent step portion is to be formed along any one direction of the metal plate material. A first procedure of punching and forming a hole, and a second procedure of crank-folding the predetermined portion of the metal plate material along the first direction to form a bent step having two folds. And a third step of bending the metal plate material after performing the first and second steps in a curved roll bending process. 9. The method for manufacturing a curved exterior plate according to claim 2, wherein a first step of punching and forming a large number of the through holes having no open edges at both side ends of the metal plate; A second procedure of crank-folding both side end portions of each of the first and second sections substantially symmetrically with each other to form first and second bent steps having two folds; and completing the first and second procedures. A third step of bending the metal plate material into a curved roll.