Description
Title of Invention
SANDWICH METAL SHEET
Technical Field
[OOOI ]
The present invention relates to a sandwich metal sheet.
Background Art
[0002]
Steel sheets having a light weight, a high rigidity and a high strength, and
good processability are widely demanded in various uses such as automobile
members, casings of home electrical appliances, and components of office
15 automation equipment. Further, these days, the amount of C02 emission is strictly
regulated as a measure against global warming; in particular, in the uses of
transporters (e.g. automobiles, trucks, buses, vehicles, etc.), not only is weight
reduction particularly highly needed in order to reduce the amount of C02 emission,
but also rigidity, impact resistance (collision safety), and processability are
20 demanded at a high level. As a solution to such demands, for example as disclosed
in Patent Literatures 1 to 3, a sandwich metal sheet in which a truss structure body is
sandwiched by metal sheets is proposed. The sandwich metal sheet can be used as
panels that form flat surfaces and curved surfaces of transporters. The truss
structure body is a structure body in which trnsses (cones or pyramids) formed of
25 metal frames are arranged in a matrix configuration, and is a mechanically
advantageous structural framework.
[0003]
Specifically, in the technology disclosed in Patent Literature 1, a lattice
body in which a lattice of tetragons or hexagons is formed is successively mountain-
30 folded and valley-folded along diagonal lincs of the lattice, and thereby a truss
structure body is hbricated. Then, both surfaces of the truss structure body are
sandwiched by metal sheets; thus, a sandwich metal sheet is fiibricateci.
[0004]
In the technology disclosed in Patent Literature 2, metal wires arc uscd to
fabricate a truss structure body, and both surfaces of the truss structure body are
5 sandwiched by metal sheets; thus, a sandwich metal sheet is fabricated.
[OOOS]
In the technology disclosed in Patent Literature 3, a truss structure body is
fabricated using a lattice body that includes a plurality of straight members arranged
in a lattice configuration and contact points arranged at the points of intersection of
10 the straight members and rotatably directing the straight members. Then, the truss
structure body is sandwiched by metal sheets; thus, a sandwich metal sheet is
fabricated.
Citation List
15 Patent Literature
[0006]
Patent Literature 1 :
Patent Literature 2:
Patent Literature 3:
Summary of Invention
Technical Problem
[0007]
These sandwich metal sheets satisfy the demand for weight reduction; but in
25 all of them, only one truss structure body is placed between the metal sheets, and
therefore there has been a problem that, when the sandwich metal sheet is folded, a
strength reduction of the folded portion, molding failure, and external appearance
failure may occur. Specifically, when the sandwich metal sheet is folded, one metal
sheet, that is, the metal sheet on the outside of folding experiences tensile
30 deformation, and the other metal sheet, that is, the metal sheet on the inside or
folding experiences compressive deformation. At this time, the truss cannot
reinforce the metal sheet that experiences tensile deformation. This is because tlie1.e
is no member that reinforces the tensile deformation portion betwccn vcrtices on the
bottom surface side of the truss. Therefore, the tensile deformation portion
stretches largely. 'l'hat is, the metal sheet on the tensile deformation side deforms
5 locally in a large degree. In association with this, the angle of the top vertex of the
truss increases. Hence, the truss is squashed. That is, the folded portion (comer
portion) of the sandwich metal sheet is squashed. Consequently, the strength of the
folded portion may be reduced rapidly (strength reduction), and accordingly the
folded portion may be broken (molding failure). Furthermore, since the sheet
10 thickness of the folded portion is different from the sheet thickness of the other
portion and the truss is squashed, the external appearance is poor (external
appearance failure). When, for example, the sandwich metal sheet is used to mold a
square U-shaped member like a frame of an automobile, the folded portion of the
sandwich metal sheet may be squashed. If the folded portion is squashed, in
15 addition to the problem of the external appearance failure of the comer portion of the
frame, there is a possibility that a strength reduction of the frame itself will occur and
impact resistance (collision safety) cannot be ensured. That is, the sandwich metal
sheets disclosed in Patent Literatures 1 to 3 have not been satisfactory in any of
rigidity, impact resistance (collision safety), and processability.
20 [0008]
Thus, the present invention has been made in view of the problems
mentioned above, and an object of the present invention is to provide a novel and
improved sandwich metal sheet that can improve the strength of the folded portion,
moldability, and external appearance.
25
Solution to Problem
[0009]
In order to solve the above problems, according to an aspect of the present
invention, there is provided a sandwich metal sheet including: a core layer including
30 a first truss structure body and a second truss structure body in which trusses formed
of frames are arrailged in a matrix configuration; a first metal sheet provided on one
surrace ol the core laycr and joincd to at lcast a vertex of thc first truss structure
body; and a second metal sheet provided on another surface of the core layer and
joincd to at least a vertex ol'the second truss structurc body. The first tluss structure
body is joined to at least one of the second truss structure body and the second metal
5 sheet, and the second truss structure body is joined to at least one of the first truss
structure body and the first metal sheet.
[OOl 01
The frame may be formed of a metal.
[OOlI]
10 At least one of the first truss structure body and the second truss structure
body may be fabricated by molding a metal sheet.
[OO 121
At least one of the first truss structure hody and the second truss structure
body may he fabricated by molding a punched metal.
15 [0013]
The frame may be formed of a resin.
[00 141
Vertices of the first truss structure body may be joined to the first metal
sheet and the second metal sheet, and vertices of the second truss structure body may
20 be joined to the first metal sheet and the second metal sheet, and each of the vertices
is placed between vcltices of the first truss structure hody.
[00 151
A vertex of the second truss structure hody may be placed at a center
between vertices of the first truss structure body.
25 [0016]
The sandwich metal sheet may include at least one resin layer formed on at
least one of a surface on a side of thc core layer of the first metal sheet and a surface
on a side of the core layer of the second metal sheet.
[0017]
30 A total thiclmess of the at least one resin layer may substantially coincide
with a thickness of the core layer.
LOO 1 81
The at least one resin laycr may be formed or a tlicrn~oplasticre sin.
[00191
The second truss structurc body may be stacked on the first truss structure
5 body, and a vertex of thc first truss structure body and a vertex of the second truss
structure body may be joined together.
[0020]
The sandwich metal sheet may include at least one resin layer formed on at
least one of a surface on a side of the core layer of the first metal sheet, a surface on a
10 side of the core laycr of the second metal sheet, and a joint portion oT the first truss
structure body and the second tmss structure body.
[0021]
A total thickness of the at least one resin layer may substantially coincide
with a thickness of the core layer.
15 [0022]
The at least one rcsin layer may be formed of a thermoplastic resin.
[0023]
At least one of a distance between vertices joined to the first metal sheet and
a distance between vertices joined to the second metal sheet may be more than or
20 equal to 0.4 times and less than or equal to 4.0 times a total thickness of the sandwich
metal sheet.
[0024]
At least one of a distance between vertices joined to the first metal sheet and
a distance between vertices joined to the second metal sheet may satisfy the
25 condition of Mathematical Formula (1) below,
0.57 i w/h i 3.7111 (1)
where w represents the distance between vertices joined to the first metal
sheet or the distance between vertices joined to the second metal sheet,
h represents a distance between the first metal sheet and the second metal
30 sheet, and
a represents a rate of change in a joint angle of the core layer and the first
metal sheet or the second mctal sheet at a time of folding processing.
[OO25]
A joint angle of the core layer and the first metal sheet or the second lnctal
sheet may be 60 to 150°.
5 100261
According to another aspect of the present invention, there is provided a
sandwich metal sheet including: a core layer including a truss structure body in
which trusses formed of metal frames are arranged in a matrix configuration; a first
metal sheet provided on one surface of the core layer and joined to a first vertex
10 included in the truss structure body; a second metal sheet provided on another
surface of the core layer and joined to a second vertex included in the truss structure
body; and at least one resin layer formed on at least one of a surface on a side of the
core layer of the first metal sheet and a surface on a side of the core layer of the
second metal sheet.
15
Advantageous Effects of Invention
[0027]
As described above, according to the present invention, the squashing of the
truss is suppressed, and accordingly the strength of the folded portion, moldability,
20 and external appearance are improved. Consequently, the sandwich metal sheet of
the present inventiolr can improve the rigidity, impact resistance (collision safety),
and processability over conventional sandwich metal sheets, while satisfying the
need for weight reduction. Therefore, the sandwich metal sheet of the present
invention can be used for not only panels that form flat surfaces and curved surfaces
25 of transporters etc. but also structure members of which collision safety is demanded.
Brief Description of Drawings
[0028]
[FIG. 11 FIG. 1 is a side view schematically showing a sandwich metal sheet
30 according to a first embodiment of the prcscnt invention.
[FIG. 21 FIG. 2 is a perspective view sche~nalicallys howing a core layer.
[FIG. 31 FIG 3 is a plan view schcmahcally showing the core layer.
[FIG. 41 FIG. 4 is a perspcctive view schematically showing a truss.
(FIG. 51 FIG. 5 is a plan view schematically showing another example of the truss.
[FIG. 61 FlG 6 is a perspective vlew schematically showing another example of the
5 truss.
[FIG. 71 FIG. 7 is a perspective view schematically showing another example of the
truss strncture hody.
[FIG. 81 FIG. 8 is a plan view illustrating a method for producing a truss structure
hody.
10 [FIG. 91 FIG. 9 is a side view schematically showing a sandwich metal sheet
according to a second embodiment of the present invention.
[FIG. 101 FIG. 10 is a side view schematically showing another example of the
sandwich metal sheet according to the second embodiment of the present invention.
[FIG. 111 FIG. 11 is a side view schematically showing a sandwich metal sheet
15 according to a third embodiment ofthe present invention.
[FIG. 121 FIG. 12 is a side view schematically showing a sandwich metal sheet
according to a fonrth embodiment of the present invention.
[FIG. 131 FIG. 13 is a side view schematically showing a sandwich metal sheet
according to a fifth embodiment of the present invention.
20 [FIG. 141 FIG. 14 is a side view illustrating the problems that a conventional
sandwich metal shccl has.
Description of Embodiments
100291
25 Hereinafter, (a) preferred embodiment(s) of the present invention will be
described in detail with reference to the appended drawings. In this specification
and the appended drawings, structural elements that have substantially the same
function and structure are denoted with the same reference numerals, and repeated
explanation of these structural elements is omitted.
30 [0030]

The present iilventors minutely investigated the problems that a
conventional sandwich metal sheet has, and have found sandwich metal sheets 1 I to
15 according to first to fifth embodiments. First, the problems that a conventional
sandwich metal sheet has are described based on FIG. 14.
5 [0031]
A sandwich metal sheet 100 is an example of the conventional sandwich
metal sheet. The sandwich metal sheet 100 includes metal sheets llOa and 110b
and a truss structure body 120 that is a core layer. The metal sheets 1 lOa and 1 lob
are provided on both surfaces of the truss structure body 120. The truss structure
10 body 120 is a structure body in which trusses (cones or pyramids) 120a formed of
metal frames 122 are arranged in a matrix configuration. The truss 120a may have,
for example, a regular tetragonal pyramid shape. In this example, the top vertex
121a of the buss 120a is joined to the metal sheet llOa, and the vertex (hereinafter,
the vertex on the bottom surface side of each truss may be referred to as a "bottom
15 vertex") 121b on the bottom surface 121c side is joined to the metal sheet 110b.
The angle O7 represents the joint angle of the truss 120a and the metal sheet 110a.
Here, the joint angle O7 of the truss 120a and the metal sheet llOa is found by the
following procedure. That is, a cross section that passes through ihe joint point of
the metal sheet 11 Oa and the truss 120a (herein, the top vertex 121 a of the truss 120a)
20 and is perpendicular to the metal sheet llOa is defined. Then, the lines of
intersection of the cross section and the buss 120a are specified, and the angle
determined by the lines of intersection and the joint point is taken as the joint angle
07.
[0032]
25 When, due to folding the sandwich metal sheet 100 like this, a portion
(tensile deformation portion) 1lOc of the metal sheet llOb to which the bottom
surface 121c of the truss 120a is joined experiences tensile deformation and a portion
(compressive deformation portion) of the metal sheet 1 lOa to which the top vertex
121a oC the truss 120a is joined experienccs compressive defonnation (compressive
30 defonnation toward the surface of the metal sheet 110a), the truss 120a cannot
reinforce the tensile deformation portion 1lOc sufficiently. This is because there is
no member that reinforces thc tensile deformation portion ll0c between vertices
121b of the botto~n surface 120c of the truss. Thereforc, the tensile deformation
portion 110c of the metal sheet 1 10b stretches largely. That is, the mctal sheet 1 10b
deforms locally in a large degree. In association with this, the joint angle 8, of the
5 truss 120a becomes very large. Hence, the truss 120a is squashed. 'hat is, the
folded portion (corner portion) of the sandwich metal sheet 100 is squashed.
Consequently, the strength of the folded portion may be reduced (strength reduction),
and accordingly the folded portion may be broken (molding failure). Furthermore,
since the sheet thickness of the folded portion is different from the sheet thickness of
10 the other portion and the truss 120a is squashed, the external appearance is poor
(external appearance failure). The present inventors minutely investigated such
problems, and have found sandwich mctal sheets 11 to 15 according to first to fifth
embodiments.
[0033]
15 For example, as shown in FIG. 1 and FIG. 11, in the sandwich metal sheets
11 and 13 according to the first and third embodiments, a vertex 41 of a first truss
structure body 40 is joined to at least a first metal sheet 20a, and a vertex 51 of a
second truss structure body 50 is joined to at least a second metal sheet 20b.
Further, the first truss struchue body 40 is joined to at least one of the second truss
20 structure body 50 and the second metal sheet 20b, and the second truss structure
body 50 is joined to at least one of the first truss structure body 40 and the first metal
sheet 20a. Therefore, the number of vertices joined per unit area of the first metal
sheet 20a and the second metal sheet 20b is made larger than in the past. Thereby,
the strength of the folded portion, moldability, and external appearance are improved.
25 [0034]
For example, in the first embodiment, as shown in FIG. 1, the vertices 41
and 51 of the first truss structure body 40 and the second truss structure body 50 are
joined to both of the first metal sheet 20a and the second metal sheet 20b, and the
position of the vertex of the second truss structure body 50 is placed between vertices
30 of the first truss structure body 40. Thereby, the number of vertices joined per unit
area of the first inctal sheet 20a and the second metal sheet 20b is made larger than in
thc past.
[0035]
In the third cmbodimcnt, as shown in FIG 11, the first truss structure body
40 is joined to the first metal sheet 2021, and the second truss structure body 50 is
5 joined to the second mctal sheet 20b. The top vertex 41a of the first truss structure
body 40 and the top vertex 51a of the second truss structure body 50 are joined
together in a core layer 30a. Therefore, the sizes of the first truss structure body 40
and the second truss structure body 50 are made smaller than the size of the
conventional truss structure body, and hence the number of vertices joined per unit
10 area of the first metal sheet 20a and the second metal sheet 20b is made larger than in
the past. Each embodiment will now be described in detail.
[0036]
a. First embodimeno
(2-1. Overall configuration of the sandwich metal sheet>
15 First, an overall configuration of a sandwich metal sheet 11 according to a
first embodiment is described based on FIG. 1. The sandwich metal sheet 11
includes a core layer 30 and metal sheets 20 provided on both surfaces of the core
layer 30. In the embodiment, the metal sheets 20 may be distinguished by referring
to one metal sheet 20 as a first metal sheet 20a and the other metal sheet 20 as a
20 second metal sheet 20b.
[0037]
(2-2. Configuration ofthe metal sheet)
The type (material) of the metal that forms the metal sheet 20 is not
particularly limited. A preferred example of the metal sheet 20 is a steel sheet, but
25 other types of metal sheets are possible. That is, examples of the metal that forms
the metal sheet include steel, aluminum, titanium, magnesium, copper, and nickel,
alloys of these, and the like. The type of the steel sheet is not particularly limited.
Examples of the steel sheet that can he used in the embodiment include surfacetreated
steel sheets such as steel sheets for cans such as tinplate, a thin tin-plated steel
30 sheet, an electrolytic clvomic acid-treated steel sheet (tin-free stecl), and a nickelplated
steel sheet, hot dipped steel sheets such as a zinc-hot-dipped steel sheet, a
zinc-iron alloy-hot-dipped steel shcct, a zinc-alumirlum-magllcsium alloy-hot-dippcd
stccl sheet, an aluminum-silicon alloy-hot-dipped stecl sheet, and a lead-tin alloyhot-
dipped steel sheet, and electroplated stccl sheets such as a zinc-electroplatcd steel
sheet, a zinc-nickel-electroplated steel sheet, a zinc-iron alloy-electroplated steel
5 sheet, and a zinc-chromiunl alloy-electroplated steel sheet, cold rolled steel shcets,
hot rolled steel sheets, and stainless sleel sheets. In the case where welding is not
performed, the steel sheet may be a surface-treated steel sheet such as a painted steel
sheet, a printed steel sheet, or a film laminated steel sheet.
[0038]
10 The first metal sheet 20a and the second metal sheet 20b may he different
fiom each other. Specifically, in uses in which folding processing, drawing
processing, etc. are needed, the core layer 30 may be sandwiched between steel
sheets with different strengths; and soft steel may be used for a surface with a small
curvature radius that is hard to process, and high tensile steel or the like may be used
15 for the other surface in order to ensure strength. A known surface treatment may be
performed on the surface of the metal sheet 20 in order to improve adhesive strength
or corrosion resistance. Examples of such a surface treatment include chromate
treatment (reaction type, application type, and electrolysis), non-chromate treatment,
phosphate treatment, organic resin treatment, and the like, but are not limited to these.
20 Preferred thicknesses of the metal sheet 20 are 0.2 mm to 2.0 mm. If the thickness
of the metal sheet 20 is less than 0.2 mm, buckling may be likely to occur during
folding processing. On the other hand, if the thickness of the metal sheet 20 is more
than 2.0 mm, the weight reduction effect is likely to be insufficient. From the
viewpoint of weight reduction, the thickness of the metal sheet 20 is preferably 1.0
25 mm or less.
100391
The thickness tl of the first metal sheet 20a and the thickness tz of the
second metal sheet 20b may not be the same as long as the weight reduction effect is
not impaired; one of them may be made thicker, and thereby it becomes easy to avoid
30 the buckling and breaking of the outer layer of the steel sheet during hard processing.
Preferred ratios between thc thicknesses of the first metal sheet 20a and the second
metal sheet 20b (the thickness tz of the second metal sheet 20blthe thickness tl of the
first metal sheet 20a) arc more than or cqual to 0.8 and lcss than or equal to 1.2.
[0040]
(2-3. Configuration of the core layer)
5 The core layer 30 includes, as shown in FIG. 2 and FIG. 3, a first truss
structure body 40 and a second truss structure body 50. The first truss structure
body 40 is, as shown in FIG 2, a structure body in which trusses (cones or pyramids)
40a formed of frames 42 are arranged in a matrix configuration. The truss 40a is, as
shown in FIG. 2 and FIG. 4, in a regular tetragonal pyramid shape. The truss 40a
10 has five vertices 41. In the following description, the vertices 41 may be
distinguished by referring to the top vertex as a top vertex 41a and the vertex 41 on
the bottom surface side as a bottom vertex 41b.
[0041]
The material that forms the frame 42 is not particularly limited. For
15 example, the frame 42 may be formed of a similar metal to the metal sheet 20, or
may be formed of a resin. Here, the resin that forms the frame 42 is not particularly
limited, but is preferably a thermoplastic resin, for example. Examples of the
thermoplastic resin include a general-purpose resin, a general-purpose engineering
plastic, and a super engineering plastic. Examples of the general-purpose resin
20 include polyethylene, polypropylene, polystyrene, and polyvinyl chloride.
Examples of the general-purpose engineering plastic include a polyamide, a
polyacetal, a polycarbonate, a modified polyphenylene ether, and a polyester.
Examples of the super engineering plastic include an amorphous polyarylate, a
polysulfone, a polyethersulfone, polyphenylene sulfide, a poly(ether ether ketone), a
25 polyimide, a polyetherimide, and a fluorine resin.
(00421
Resins arc inferior to metals in strenglh. Hence, in the case whcrc the
sandwich metal sheet 11 is used in hard processing (processing of largely folding
etc.), the frame 42 is preferably formed of a metal. However, in the case where the
30 sandwich metal sheet 11 is used for a panel member that does not need folding or a
member for light processing, the frame 42 may be formed of either a metal or a resin.
By forming the frame 42 out of a resin, the effects of improving ihe heat insulating
properlies and insulating properties of the sandwich metal sheet 11 and reducing thc
weight ol the sandwich metal shcet 11 are expected. In particular, by forming the
franie 42 out of a super engineering plastic, the heat resistance (e.g. heat resistance to
5 temperature of 150°C or more) of the sandwich metal sheet 11 is particularly
improved. Further, by forming the frame 42 out of a fiber-reinforced resin (a
material in which a fiber material such as carbon fibers or glass libers is contained in
the resin mentioned above), the strength of the frame 42 can be increased.
[0043]
10 It is also possible to stack a truss structure body made of a resin on a surface
of the sandwich metal sheet 11. In this case, the surface lubricity and heat
insulating properties of the sandwich metal sheet 11 can be further improved.
[0044]
The top vertex 41a of the truss 40a is joined to the first metal sheet 20a, and
15 the bottom vertex 41b is joined to the second metal sheet 20b. The joint angle 011
of the truss 40a and the first metal sheet 20a is preferably 60 to 150". This is
because, when the joint angle 011 is 60 to 150°, the sandwich metal sheet 11 is
resistant to shear deformation and compressive deformation in the sheet thickness
direction.
20 The shear delormation in the embodiment refers to shear deformation
occurring when forcc is applied in a direction parallel to the sandwich metal sheet 11,
and the compressive deformation in the sheet thickness direction refers to
compressive deformation occurring when force is applied in a direction
perpendicular to the sandwich metal sheet 11. In the embodiment, since the frames
25 42 of the truss 40a are joined to the surfaces of the first metal sheet 20a and the
second metal sheet 20b with inclination, the strength to shear deformation is
increased. If the joint angle Oil is less than 60°, since the number of trusses 40a in
the core layer 30 is increased, the mass of the sandwich metal sheet 11 is increased.
The~efore, this is not prcfcrable from the viewpoint of weight reduction.
30 Furthermore, the resistance to shear deformation of the sandwich metal sheet 11 may
be reduced. On the other hand, if the joint angle OIl is more thin 150°, the
sandwich metal sheet 11 may be vulnerable to compressive derormation in the sheet
thicliness dircction. In the casc where it is desired to rnalie thc sandwich metal
sheet 11 resistant particularly to compressive deformation in the shcet thickness
direction, the joint angle 011 may be set to 60 to 90". In the case where it is desired
6 to make the sandwich metal sheet 11 resistant particularly to shear deformation, the
joint angle ell may be set to more than 90" to 150'. In this case, the sandwich
metal sheet 11 can be further reduced in weight. In the case where the joint angle
Oil is set to approximately 150°, the sandwich metal sheet 11 may be a little
vulnerable to compressive deformation in the sheet thickness direction; thus, as
10 described in the second embodiment described later, it is preferable that a resin layer
21 be formed on the surface of the first metal sheet 20a. In this case, the joint point
is reinforced by the resin layer 21, and accordingly the sandwich metal sheet 11 is
made resistant to compressive deformation in the sheet thickness direction.
100451
15 Here, the joint angle 011 is found by the following procedure. That is, a
cross section that passes through the joint point of the first metal sheet 20a and the
truss 40a (herein, the top vertex 41a of the truss 40a) and is perpendicular to the first
metal sheet 20a is defined. Then, the lines of intersection of the cross section and
the truss 40a are specified, and the angle determined by the lines of intersection and
20 the joint point is taken as the joint angle OI1. The magnitude of the joint angle 811
may vary depending on how to define the cross section; it is preferable that the joint
angle 0l1 satisfy the condition prescribed in the embodiment however the cross
section is defined. FIG. 4 shows an example of the joint angle 011.
100461
25 Further, the joint angle 812 of the truss 40a and the second metal sheet 20b is
preferably 60 to 150". The reason is similar to the reason described in regard to the
joint angle ell. In the case where it is desired to make the sandwich metal sheet 11
rcsistant particularly to compressive deformation in the sheet thiclcness direction, the
joint angle 012 may be sct to 60 to 90". In the case where it is desired to make the
30 sandwich metal sheet 11 resistant particularly to shear deformation, the joint angle
may be set to more than 90" to 150°. In tliis case, the sandwich inctal sheet 11
can be further reduced in weight. In the case whcrc the joint augle 0 , 2 is sct to
approximately 150°, as described in the second embodiment described later, it is
preferable that a resin layer 21 be formed on the surface of the second metal sheet
20b. In this case, the joint point is reinforced by the resin layer 21.
5 [0047]
Here, the joint angle 012 is found by the following procedure. That is, a
cross section that passes through the joint point of the second metal sheet 20b and the
truss 40a (herein, the bottom vertex 41 b of the truss 40a) and is perpendicular to the
second metal sheet 20b is defined. Then, the lines of intersection of the cross
10 section and the truss 40a arc specified, and the angle determined by the lines of
intersection and the joint point is taken as the joint angle OI2. The magnitude of the
joint angle QI2 may vary depending on how to define the cross section; it is preferable
that the joint angle OI2 satisfy the condition prescribed in the embodiment however
the cross section is defined.
15 [0048]
The angle OI1 between the frame 42 of the truss 40a and the bottom surface
41c of the truss 40a is preferably approximately 30 to 60°, and more preferably
approximately 45 to 60°. The height of the truss 40a, that is, the height (thickness)
of the first truss structure body 40 is not particularly limited, but is preferably more
20 than or equal to 1 mm and less than or equal to 5 mm in view of the processability
and the like of the sa~idwichm etal sheet 11.
[0049]
The trusses forming the first truss structure body 40 may be also an n-gonal
pyramidal truss 60a shown in FIG. 5. The n-gonal pyramidal truss 60 has a top
25 vertex 61a, bottom vertices 61b, and frames 62. When n = 3, the n-gonal pyramidal
truss is a trigonal pyramidal truss 70a shown in FIG. 6. The trigonal pyramidal truss
70a has a top vertex 71a, bottom vertices 71b, and frames 72. The angle Olq
between the frame 72 and thc bolton1 surface 71c of the trigonal pyramidal truss 70a
is preferably approximately 30 to 60°, and more preferably approximately 45 to 60'.
30 This similarly applies to the 11-gonal pyramidal truss 60. FIG. 7 shows a truss
s!ructurc body 70 in which trigonal pyramidal t~usscs7 0a are arranged in a matrix
configuration. 'The most preferred shape ol: the truss 40a is thc regular tctragonal
pyramid shown in FIG. 4.
[0050l
The second truss structure body 50 is, as shown in FIG. 2, a structure body
5 in which trusses (cones or pyramids) 50a formed of frames 52 are arranged in a
matrix configuration. The second truss structure body 50 has a similar
configuration to the first truss structure body 40. That is, the truss 50a is, as shown
in FIG. 2 and FIG. 4, in a regular tetragonal pyramid shape. The truss 50a has five
vertices 51. In the following description, the vertices 51 may be distinguished by
10 refcrring to the top vertex as a top vertex 51a and the vertex 51 on the bottom surface
side as a bottom vertex 51b.
[005l]
The material that forms the frame 52 is not particularly limited. For
example, the frame 52 may be formed of a similar material to the frame 42. The
15 effect by each material is similar to the effect described in regard to the frame 42.
[0052]
The top vertex 5la of the truss 50a is joined to the first metal sheet 20a, and
the bottom vertex 51b is joined to the second metal sheet 20b. The top vertex 51a is
placed between top vertices 41a of the first truss structure body 40. The top vertex
20 51a is preferably placed at the center between top vertices 41a of the first truss
structure body 40. The bottom vertex 51b is placed between bottom vcrtices 41b of
the first truss structure body 40. The bottom vertex 51b is preferably placed at the
center between bottom vertices 41b of the first truss structure body 40.
[0053]
25 Thus, in the first embodiment, the top vertex 41a of the first trirss structure
body 40 and the top vertex 5 la of the second truss structure 50 are joined to the first
metal sheet 20a, and the bottom vertex 41b of the first truss structure body 40 and the
bottom vertex 51b of the second truss structure 50 are joined to the second metal
sheet 20b. The flat surface (virtual flat surface) passing through the'joint points of
30 the first truss sttucture body 40 and the second truss structure body 50, and the fxst
metal sheet 2023 forms one surface of the core layer 30. Further, the flat surface
(virtual flat surljce) passing through the joint points of thc first truss structL1re body
40 and the sccond truss structure 50, and the second metal sheet 20b forms the other
surfacc of the core layer 30. The thicliness of the core layer 30 is determined as the
distance between the surfaces of the core layer 30. The thickness of the core layer
5 30 is substantially equal to the height of the first truss structure body 40 (or the
second truss structure body 50). Also in each embodiment described later, the
surfaces and thickness of the core layer are similarly defined.
[0054]
The joint angle 021 of the truss 50a and the first metal sheet 20a is preferably
10 60 to 150°. The reason is similar to the reason described in regard to the joint angle
OL1. In the case where it is desired to make the sandwich metal sheet 11 resistant
particularly to compressive deformation in the sheet thicliness direction, the joint
angle 821 may be set to 60 to 90'. In the case where it is desired to make the
sandwich metal sheet 11 resistant particularly to shear deformation, the joint angle
15 821 may be set to more than 90" to 150°. In this case, the sandwich metal sheet 11
can be further reduced in weight. In the case where the joint angle is set to
approximately 150°, as described in the second embodiment described later, it is
preferable that a resin layer 21 be formed on the surface of the first metal sheet 20a.
In this case, the joint point is reinforced by the resin layer 21.
20 [0055]
The method for finding the joint angle 02, is similar to thc inethod for
finding the joint angle 811. That is, a cross section that passes through the joint
point of the first metal sheet 20a and the truss 50a (herein, the top vertex 51a of the
truss 50a) and is perpendicular to the first metal sheet 20a is defined. Then, the
25 lines of intersection of the cross section and the truss 50a are specified, and the angle
determined by the lines of intersection and the joint point is taken as the joint angle
02,. The magnitude of the joint angle 021 may vary depending on how to define the
cross section; it is preferable that the joint angle 021 satisfy the condition prescribed
in the embodiment however the cross section is defined. FIG. '4 shows an example
30 orthe joint angle 821.
[0056]
Furthcr, the joint angle 022 of the truss 50a and the second metal sheet 20b is
preferably 60 to 150'. The reason is similar to the reason described in regard to the
joint angle 811. In the case where it is desired to make the sandwich metal sheet 11
resistant particularly to compressive deformation in the shect thickness direction, the
5 joint angle 022 may be set to 60 to 90'. In the casc where it is desired to make the
sandwich metal sheet 11 resistant particularly to shear deformation, the joint angle
@22 may be set to more than 90" to 150°. In this case, the sandwich metal sheet 11
can be further reduced in weight. In the case where the joint angle 822 is set to
approximately 150°, as descrihed in the second cnlbodiment descrihed later, it is
10 preferable that a resin layer 21 be formed on the surface of the second inetal sheet
20b. In this case, the joint point is reinforced by the resin layer 21.
[0057]
Here, the joint angle 822 is found by the following procedure. That is, a
cross section that passes through the joint point of the second metal sheet 20h and the
15 truss 50a (herein, the bottom vertex 51h of the truss 50a) and is perpendicular to the
second metal sheet 20b is defined. Then, the lines of intersection of the cross
section and the truss 50a are specified, and the angle determined by the lines of
intersection and the joint point is taken as the joint angle 022. The magnitude of the
joint angle 822 may vary depending on how to define the cross section; it is preferable
20 that the joint angle satisfy the condition prescribed in the embodiment however
the cross section is defined.
[0058]
As shown in FIG. 4, the angle 823 between the frame 52 of the truss 50a and
the bottom surface of the truss 50a is preferably approximately 30 to 60°, and more
25 preferably approximately 45 to 60'. The height of the truss 50a, that is, the height
(thickness) of the second truss structure body 50 is not particularly limited, but is
prefcrahly more than or equal to 1 mm and less than or equal to 5 mm in view of the
processability of the sandwich metal sheet 11, etc. The truss 50a may be the trusses
shown in FIG. 5 to FIG. 6.
30 [0059]
Thus, in the sandwich metal sheet 11 according to the first embodiment,
since the vertex 51 of thc second truss stlucture hody 50 is placed betwecn vertices
41 of the first truss structure body 40, the number of vertices in contact per unit area
of the first metal sheet 20a and the second metal sheet 20b is made larger than in the
past. Thereby, the strength of the folded portion, moldability, and external
5 appearance are improved.
[0060]
More specifically, as shown in FIG. 1, when, due to folding the sandwich
metal sheet 11, a portion (tensile deformation portion) 20c of the second metal sheet
20b with which the bottom surface of the truss 40a is in contact experiences tensile
10 deformation and a portion (compressive deformation portion) of the first metal sheet
20a with which the top vertex 41a of the truss 40a is in contact experiences
compressive deformation (compressive deformation toward the surface of the first
metal sheet 20a), the tensile deformation portion 20c is reinforced by the bottom
vertex 51b placed between bottom vertices 41b of the bottom surface 41c. In other
15 words, since the tensile deformation portion is divided by the bottom vertex 51b,
local tensile deformation is suppressed. Consequently, the change in the joint angle
011 is suppressed. That is, the squashing of the truss 40a is suppressed. Therefore,
also the squashing of the folded portion (corner portion) of the sandwich metal sheet
11 is suppressed. Consequently, the strength of the folded portion is improved, and
20 the breaking of the folded portion is suppressed. Furthermore, since the difference
between the sheet thickness of the folded portion and the sheet thickness of the other
portion is reduced, the external appearance is improved. Thus, the strength of the
folded portion, moldability, and external appearance are improved.
[0061]
25 Here, the distance WL~be tween the top vertices 41a and 51a joined to the
first metal sheet 20a is preferably more than or equal to 0.4 times and less than or
equal to 4.0 times and more preferably more than or equal to 1.0 time and less than
or equal to 1.8 times the total thiclcness of the sandwich metal sheet 11 (= h + tl + tz,
where h represents the distance between the first metal sheet 20a and the second
30 metal sheet 20b). Similarly, the distance WLZ between the bottom vertices 41 b and
51b joined to the second metal sheet 20b is preferably more than or equal to 0.4
times and less than or equal to 4.0 times and rnorc preferably more than or cqual to
1.0 time and less than or equal to 1.8 times the total thickness of the sandwich metal
sheet 11. When the distances Wr.1 and WI,l between vertices are values in these
ranges, the angle change of the top vertex 41a of the truss 40a is suppressed more
5 greatly. Consequently, the strength of the folded portion is further improved, the
breaking is suppressed more greatly, and the external appearance is further improved.
PO621
It is still more preferable that at least one of the distances WLI and WLZ
between vertices satisfy the condition of Mathematical Formula (1) below.
10 0.57 5 wlh 5 3.7la (1)
In Mathematical Formula (I), w represents the distance WI,~o r W Lb~et ween
vertices, h represents the distance between the first metal sheet 20a and the second
metal sheet 20b, and a represents the rate of change in the joint angle during folding
processing (the joint angle on the compressive deformation side). The rate of
15 change a is calculated by the following procedure. That is, the amount of change in
w at the time when the sandwich metal sheet 11 is folded with a certain curvature
radius is calculated by geometric calculation, and the result is used to calculate the
amount of change in the joint angle. Then, the amount of change in the joint angle
is used to calculate the rate of changea. The rate of change a is expressed by
20 Mathematical Formula (2) below.
a = tan (8'12)ltan (812) (2)
In Mathematical Formula (2), 8' represents the joint angle after folding
processing, and 0 represents the joint angle before folding processing.
[0063]
25 In the case where, for example, the sandwich metal sheet 11 is folded with a
curvature radius substantially equal to the total thickness of the sandwich metal sheet
I1 (in the case of what is called hard processing), a = 1.5. In the case where the
sandwich metal sheet 11 is folded with a curvature radius of approximately twice the
total thickness of the sandwich metal sheet 11, a = 1.25. In the case where the
30 sandwich metal sheet 11 is used as a panel member that does not need folding or is
gently folded (that is, in the case of light processing), a is almost 1. Thus, the rate
of changc n is determined depending on how to process the sandwich metal sheet 11.
Therc is no case where a is less than I. This is because, while values of n of less
than 1 mean that the joint angle on the compressive dcfoimation side becomes
smaller than the value before folding processing, there is no case where such an
5 event occurs.
[0064]
Further, wlh represents tan (012) (0: the joint angle on the con~pressive
deformation side among 011 to 814) The lower limit value of0.57 is the value of tan
(6012). That is, if wih is less than 0.57, the number of trusses 40a in the core layer
10 30 is increased, and accordingly the mass of the sandwich metal sheet 11 is increased.
Therefore, this is not preferable from the viewpoint of weight reduction.
Furthermore, the resistance to shear deformation of the sandwich metal sheet 11 may
be reduced. The upper limit value of 3.7 is the value of tan (15012). That is,
according to Mathematical Formula (2) above, it is undesirable for the joint angle
15 after folding processing to be more than 150". This is because, if the joint angle is
more than 150°, the resistance to compressive deformation in the sheet thickness
direction may be reduced
[0065]
Of the core layer 30, portions between the vertices of the first truss structure
20 body 40 and the second truss structure body 50 form gap layer portions directly
joined to the first metal sheet 20a and the second metal sheet 20h, and the
compression resistance is reduced in the portions. Consequently, during the
processing (for example, during the folding) of the sandwich metal sheet 11, the first
metal sheet 20a or the second metal sheet 20b may cave into the gap portion of the
25 core layer 30. Thus, from the viewpoint of preventing the caving-in of the first
metal sheet 20a and the second metal sheet 20b, the distance WLb~e tween vertices is
preferably less than or equal to 30 times and more preferably less than or equal to 10
times the thickness tl of the first metal sheet 20a. Similarly, the distance Wm
between vertices is preferably less than or equal to 30 times and more preferably less
30 than or equal to 10 times ihe thickness t2 of the second metal sheet 20b.
[0066]
The core layer 30 and the metal sheet 20 arc joined together by an adhesive.
'Shc adhcsivc is not particularly limited, and an adhesive used for a sandwich metal
sheet in which a truss structure body is used for a core layer can be used without
problems in the cinbodiment. However, from the viewpoint of cnsuring the heat
5 resistance and durability of thc adhesive, a structural adhesive in which an epoxy
resin is used as the matrix is preferable, and particularly a one-component heatsetting
adhesive in which a hardener is mixed in advance is more preferable in terms
of handleability. From the viewpoint of ensuring thc weldability of the sandwich
metal sheet 11, an electrically conductive adhesive is preferable. Examples of the
10 electrically conductive adhesive include an adhesive in which a prescribed amount of
a metal powder such as aluminum powder, nickel powder, or iron powder is added to
an adhesive like that described above. The core layer 30 and the metal sheet 20
may he joined together also by brazing, seam welding, or the like.
[0067]
15 (2-4. Method for producing the truss structure body)
Next, a method for producing the first truss structure hody 40 and the
second truss structure hody 50 is described. First, the case where the frames 42 and
52 are each a metal frame is described. As shown in FIG. 8, a wire net 200 is
prepared. The wire net 200 is a sheet-like member in which frames 201 are
20 distributed in a net configuration, and has a large number of opeuings 202.
Although the opening 202 is a square in FIG. 8, the shape of the opening 202 is not
limited to a square. The type of the wire net 200 is not particularly limited.
[OOSS]
For example, the wire net 200 may be a wire net fabricated by weaving
25 metal wires in a net configuration (hereinafter, such a wire net may be referred to as
a "knitted wire net"). In this case, the metal wire forms a f~ame20 1. The method
for weaving metal wires is selected preferably with consideration of the ductility of
the metal wire. For example, in the case where the ductility of the metal wire is low,
the metal wire may be broken during folding processing. Hence, a wire net in
30 which the point of intersection of a warp wire and a weft wire of the uire net (the
intelsection portion) is 1;ot fixed may be fabricated; thereby, displacement
deformation between metal wires occurs at the point of intersection, and breaking
can he prevented. Thus, in the case where the ductility of the ~nelal wire is low, it
may be inappropriate to fix the point of intersection of metal wires by welding.
However, in this case, since the intersection portion oT frames 201 forms the vcrtex
5 of the first truss structure body 40 and the second truss structure body 50, the
strength of the vertex is reduced. In the case where the point of interscction is
joined by a joining material such as an adhesive, a joining material having
deformability capable of withstanding displacement deformation during folding
processing is preferably used because thc shape of the truss structure body can be
10 maintained while the breaking of the metal wire is prevented. However, when the
angle of the mountain fold and the valley fold of the wire net 200 is set to an acute
angle, there is still a high possibility that the frame 201 and the welded portion will
be broken.
[0069]
15 The wire net 200 may be also a wire net fabricated by forming a large
number of punched holes in a metal sheet (what is called a punched metal). In this
case, the metal portion between punched holes (what is called a "bar") forms a frame
201. The wire net 200 may be also a wire net fabricated by forming a large number
of notches in a metal sheet and then extending the metal sheet in a direction crossing
20 the length direction of the notch (that is, expanding the notch) (what is called an
expanded metal). In this case, the metal portion between expanded notches forms a
frame 201. In the case where the wire net 200 is a punched metal or an expanded
metal, the first truss structure body 40 and the second truss structure body 50 are
fabricated by molding a metal sheet.
25 [0070]
The wire net 200 is preferably formed of, among the knitted wire net, the
punched metal, and the expanded metal mentioned above, the punched metal or the
expanded metal. The wire net 200 is more preferably formed of the punched metal.
The reason is as follows. That is, in the case where the wire net 200 is formed of
30 the lmitted wire net, it is necessary to knit a wire net, and therefore the production
cost of the wire net 200 (the cost of the source ma!erial) is increased. In addition,
since thc interscction portion of frames 201 forms the vertex or the first truss
structure body 40 and the second truss structure body 50, the strcngth of the vertex is
reduced. This is because the frames 201 forming a vertex may shift lrom each other.
As a method to solve the problem, it may be possible to weld the intersection portion
5 of frames 201. Flowever, in the case where thc intersection portion of frames 201 is
welded, when the wire net 200 is alternately mountain-folded and valley-folded, the
frame 201 and the welded portion may be broken. In particular, when the angle of
the mountain fold and the valley fold is set to an acute angle, the frame 201 and the
welded portion are highly likely to be broken.
10 [0071]
On the other hand, the punched metal and the expanded metal are fabricated
by simply molding a metal sheet, and are therefore lower in production cost than the
knitted wire net. In addition, the strength of the vertex is ensured.
[0072]
15 Furthermore, in the case where the wire net 200 is formed of the punched
metal, various shapes of punched metal can be fabricated by simply changing the
structtu-e (shape, thickness, size, etc.) of the hole of the punching of the metal sheet.
Consequently, the first truss structure body 40 and the second truss structure body 50
with various shapes can be fabricated at low cost. Furthermore, in the case where
20 the wire net 200 is formed of the punched metal, the intersection portion of frames
201 is flat, and thcrcfore the strength of the vertex is improved. On the other hand,
the expanded metal is formed by forming notches in a metal sheet and then extending
the metal sheet. Therefore, concavity and convexity are formed in the intersection
portion of frames 201. Since the intersection portion forms the vertex of the first
25 truss structure body 40 and the second truss structure body 50, the strength of the
vertex may be slightly reduced. As a method to lessen such concavity and
convexity, a method of pressing the expanded metal may be possible; but this method
needs an additional step of pressing, and leads to an increase in production cost. In
addition, due to the pressing of the expanded metal, processing strain occurs in the
30 concave-convex portion of the expanded metal. Consequently, during truss
molding, the concave-convex portion, that is, the portion that forms each of the
vertices 41 and 5 1 of the first truss structurc body 40 and the second truss structurc
body 50 may be broken (for example, the vertices 41 and 51 or their vicinity nlay be
cracked). If the sandwich metal sheet 11 is fabricated using a cracked truss
structurc body, the following problem may arise. That is, when shear force is
5 applied to the sandwich metal sheet 11, stress may be concentrated in the cracked
portion, and the frame of the truss structure body may be completely cut from the
cracked portion. Thus, in the case where the first truss structure body 40 and the
second truss structurc body 50 are fabricated using the expanded metal, as described
in the second embodiment, the joint points of the first truss structure body 40 and the
10 second truss structure body 50, and the first metal sheet 20a and the second metal
sheet 20b may be protected with a resin layer 21. Thereby, even when either or
both of the first truss structure body 40 and the second truss structure body 50 are
cracked, the cracked portion can be buried in the resin layer 21. In this case, even
when shear force is applied to the sandwich metal sheet 11, it is less likely that stress
15 will be concentrated in the cracked portion. Consequently, the cutting of the frames
42 and 52 is suppressed.
[0073]
Subsequently, the wire net 200 is alternately mountain-folded and valleyfolded
at straight lines A and B (straight lines connecting diagonal lines of the
20 openings 202); thus, the first truss structure body 40 and the second truss structure
body 50 are fabricated. By this method, it is possible to fabricate a first truss
structure body 40 and a second truss structure body 50 in which the trusses 40a and
50a are in a trigonal pyramid shape, a regular tetragonal pyramid shape, or a
tetragonal pyramid shape.
25 100741
In the case where the frames 42 and 52 are each a resin frame, a mold of the
first truss structure body 40 and the second truss structure body 50 may be prepared,
and the mold may be used to fabricate the first truss structure body 40 and the second
truss structure body 50.
30 [0075]
(2-5. Method for producing the sandwich metal sheet)
Next, the first truss str~~ctubrcod y 40 and the second truss structure body 50
are superimposed so that the vertex 5 1 of the second truss structure body 50 is placed
between vcrtices 41 of the first truss structure body 40. Thereby, the core layer 30
is fabricated. Subsequently, an adhesive is applied to both surfaces of the core layer
5 30, and the metal sheet 20 is adhered to both surfaces of the core layer 30. The
adhesion is performed by applying pressure to the metal sheet 20 toward the core
layer 30 side at normal temperature or in a heated condition. Thereby, the sandwich
metal sheet 11 is fabricated.
[0076]
10 Thus, by the first embodiment, the vertex 51 of the second truss structure
body 50 is placed between vertices 41 of the first truss structure body 40; hence,
when, for example, the portion to which the bottom surface 41c of the truss 40a is
joined (the tensile deformation portion) experiences tensile deformation, the tensile
deformation portion is reinforced by the vertex 5 1 of the second truss structure body
15 50. Therefore, the squashing of the truss 40a is suppressed, and accordingly the
strength of the folded portion, moldability, and external appearance are improved.
Consequently, the sandwich metal sheet of the present invention can improve the
rigidity, impact resistance (collision safety), and processability over conventional
sandwich metal sheets, while satisfying the need for weight reduction. Therefore,
20 the sandwich metal sheet of the present invention can be used for not only panels that
form flat surfaces and curved surfaces of transporters etc. but also structure members
of which collision safety is demanded.
[0077]
<3. Second embodiment>
25 (3-1. Overall configuration of the sandwich metal sheet>
Next, a second embodiment is described based on FIG. 9 and FIG. 10. A
sandwich metal sheet 12 according to the second embodiment is a sandwich metal
sheet in which a resin layer 21 is added to the sandwich metal sheet 11 according to
the first embodiment.
30 [00751
Specifically, the resin layer 21 is provided on each of a surface of the first
metal shect 20a (the surface on the core layer 30 side) and a surface of the second
metal sheet 20b (the surface on tllc core layer 30 side). In the embodiment, the
resin layers 21 may be distinguished by referring to the resin layer 21 on the first
mctal sheet 20a as a first resin layer 21a and the resin layer 21 on the second metal
5 sheet 20b as a second resin layer 21b. Either one of the first resin layer 21a and the
second resin layer 21b may be omitted.
100791
The vertices of the first truss structure body 40 and the second truss
structure body 50 have sunk in the resin layer 21, and are joined to the first metal
10 sheet 20a and the second metal sheet 20b. Thus, in the second embodiment, the
joint points of the first truss structure body 40 and the second truss structure body 50,
and the first metal sheet 20a and the second metal sheet 20b are protected by the
resin layer 21.
[0080]
15 The type of the resin that forms the resin layer 21 is not particularly limited,
but is preferably a thermoplastic resin in terms of processing etc. Examples ol the
thermoplastic resin include a general-purpose resin, a general-purpose engineering
plastic, and a super engineering plastic. Examples of the general-purpose resin
include polyethylene, polypropylene, polystyrene, and polyvinyl chloride.
20 Examples of the general-purpose engineering plastic include a polyamide, a
polyacetal, a polycarbonate, a modified polyphenylene ether, and a polyester.
Examples of the super engineering plastic include an amorphous polyarylate, a
polysulfone, a polyethersulfone, polyphenylene sulfide, a poly(ether ether ketone), a
polyimide, a polyetherimide, and a fluorine resin.
25 [0081]
By forming the resin layer 21 out of the thermoplastic resin described above,
the joint point can be reinforced. Specifically, the peel strength between the first
truss structure body 40 and the second truss structure body 50, and the first metal
sheet 20a and the second inctal sheet 20b can be improved. The resin layer 21
30 functions also as an adhesive that joins the first buss structure body 40 and the
second truss structure body 10, and the first metal sheet 20a and the second metal
shcct 20b. Therefore, in the second embodiment, it becomes possible to eliminate
the need for the adhesive used in the first embodiment. Fui-thennore, the first illctal
sheet 20a and the second metal sheet 20b, and the lirst truss stxucture body 40 and
the second truss structure body 50 can be joined by simply forming the resin layer 21
5 on the surfaces of the first metal sheet 20a and the second metal sheet 20b.
Therefore, the productivity of the sandwich metal sheet 12 is improved.
[0082]
When the resin layer 21 is formed of a general-purpose engineering plastic
or a super engineering plastic, further reinforcement effect is obtained. Specifically,
10 the deformation of the vertex of the first truss structure body 40 and the second truss
structure body 50 can be suppressed. Therefore, when the sandwich metal sheet 12
is folded, the strength of the folded portion can be further improved. Further, when
the resin layer 21 is formed of a super engineering plastic, the heat resistance (e.g.
heat resistance to temperature of 1 50°C or more) of the sandwich metal sheet 12 is
15 improved. The resin that forms the resin layer 21 may be either a foam material or
a bulk material.
[0083]
The thickness tal of the first resin layer 21a and the thickness ta2 of the
second resin layer 21b are not particularly limited. However, as shown in FIG. 10,
20 the sum total of the thicknesses t a ~an d ta2 (i.e. the total thickness of the resin layers
21) may be made to substantially coincide with the distance between the first metal
sheet 20a and the second metal sheet 20b (= h).
[0084]
By making the total thickness of the resin layers 21 substantially coincide
25 with the distance between the first metal sheet 20a and the second metal sheet 20b,
the strength of the sandwich metal sheet 12 to compressive deformation in the sheet
thickness direction can be further improved. Here, also a sandwich metal sheet in
which the space between the first metal sheet 20a and the second metal sheet 20b is
filled only with resin has a large strength to compressive deformation. However,
30 this sandwich metal sheet has very weak strength to shear deformation. This is
because the interfaces between the first metal sheet 20a and the second metal sheet
20b, and the resin laycr are flat. On the other hand, in the saildwich metal sheet 12
according to the second embodiment, a large nutnbcr of joint points described abovc
are formed at the interfaces between thc first metal sheet 20a and the second metal
sheet 20b, and the resin layer. Furthermore, the frames 42 and 52 of the first truss
5 structure body 40 and the second truss structure body 50 are joined to the surfaces of
the first metal sheet 20a and the second metal sheet 20b with inclination. Therecore,
the sandwich metal sheet 12 also has a large strength to shear deformation.
Furthermorc, the first metal sheet 20a and the second metal sheet 20b are held by not
only the first truss structure body 40 and the second truss structure body 50 but also
10 the resin layer 21. Hence, the first metal sheet 20a and the second metal sheet 20b
are less likely to shift in the thickness direction of the sandwich metal sheet 11 (less
liltely to sink in the thickness direction) during the cutting of the sandwich metal
sheet 1 1.
[0085]
15 (3-2. Method for producing the sandwich metal sheet)
The sandwich metal sheet 12 can be fabricated by the following steps.
First, the core layer 30 is fabricated by similar steps to the first embodiment.
Subsequently, a resin sheet is stacked on the surface of the first metal sheet 2021, and
thereby the first resin layer 21a is formed on the surface of the first metal sheet 20a.
20 Similzu steps are performed to form the second resin layer 21b on the surface of the
second metal sheet 20b. Subsequently, the first resin layer 21a and the second resin
layer 21b are subjected to heating or the like to soften the iirst resin layer 21a and the
second resin layer 21b. Subsequently, the core layer 30, and the first metal sheet
20a and the second metal sheet 20b are joined. At this time, the first truss structure
25 body 40 and the second truss structure body 50 push aside the first resin layer 21a
and the second resin layer 21b, and come into contact with the first metal sheet 20a
and the sccond metal sheet 20b. After that, the first resin layer 21a and the second
resin laycr 21b are subjected to cooling or the like to harden the first resin layer 21a
and the sccond resin layer 21b. Thereby, the first truss structure body 40 and the
30 second truss structure body 50 are joined to the first metal sheet 20a and thc second
metal sheet 20b. That is, the first resin layer 21a and the second resin layer 21b
function as an adhcsive. from ihe viewpoint of further ensuring joining
strcngth, a joining method similar to the method of the first embodiment may be
further performed.
[0086]
5 <4. Third embodiment>
(4-1. Overall configuration of the sandwich metal sheet)
Next, a third embodiment is described based on FIG. 11. A sandwich metal
sheet 13 according to the third embodiment is a sandwich metal sheet in which the
core layer 30 of the sandwich metal sheet 11 according to the first embodiment is
10 replaced with a core layer 30a.
lo0871
The core layer 30a is a structure in which the first truss structure body 40
and the second truss structure body 50 are stacked. The top vertex 41a of the first
truss structure body 40 is joined to the top vertex 51a of the second truss structure
15 body 50, and the bottom vertex 41b of the first truss structure body 40 is joined to the
first metal sheet 20a. On the other hand, the bottom vertex 51b of the second truss
structure body 50 is joined to the second metal sheet 20b. The first truss structure
body 40 and the second truss structure body 50 are joined together by the adhesive
described above (or brazing, seam welding, or the like). Although the shapes of the
20 first truss structure body 40 and the second truss structure body 50 are the same in
FIG. 11, they may bc different from each other.
[0088]
When the sandwich metal sheet 13 and the conventional sandwich metal
sheet 100 are compared with the same total thickness, the size of the first truss
25 structure body 40 and the second truss structure body 50 (specifically, the size of the
trusses 40a and 50a forming the first truss structure body 40 and the second truss
structure body 50) is smaller than the size of the conventional truss structure body (in
the example of FIG. 11, half of the conventional one). Therefore, the number of
vertices 41 and 51 joined per unit area of the first metal sheet 20a and tbc second
30 metal sheet 20b is made largc~th an in the past, and thus the strength of the folded
poition, moldability, and external appearance of the sandwich metal sheet I1 are
improved.
[0089]
Here, the joint angle 0s of the truss 40a and the first metal sheet 20a is
preferably 60 to 150'. The reason is similar to thc reason described in regard to Lhe
5 joint anglc 011. In the case where it is desired to make the sandwich metal sheet 13
resistant particularly to compressive deformation in the sheet thickness dircction, the
joint angle (35 may be set to 60 to 90". In the case where it is desired to make the
sandwich metal sheet 13 resistant particularly to shear deformation, the joint angle Bs
may be set to more than 90" to 150'. In this case, the sandwich metal sheet 13 can
10 be further reduced in weight. In the case where the joint angle 05 is set to
approximately 150°, as described in the fourth embodiment described later, it is
preferable that a resin layer 21 be formed on the surface of the first metal sheet 20a.
In this case, the joint point is reinforced by the resin layer 21.
[0090]
15 Herc, the joint angle 05 is found by the following procedure. That is, a
cross section that passes through the joint point of the first metal sheet 20a and the
truss 40a (herein, the bottom verlex 41b of the truss 40a) and is perpendicular to the
first metal sheet 20a is defined. Then, the lines of intersection of the cross section
and the truss 40a are specified, and the angle determined by the lines of intersection
20 and the joint point is taken as the joint angle 0s. The magnitude of the joint angle 05
may vary depending on how to define the cross section; it is preferable that the joint
angle O5 satisfy the condition prescribed in the embodiment however the cross
section is defined.
[0091]
25 The joint angle 06 of the truss 50a and the second metal sheet 20b is
preferably 60 to 150°. The reason is similar to the reason described in regard to tbe
joint angle 01,. In the case where it is desired to make the sandwich metal sheet 13
resistant particularly to compressive deformation in the sheet thickness direction, the
joint angle 86 may be set to 60 to 90°. I11 the case where it is desired to make the
30 sandwich mctal sheet 13 resistant particularly to shea~d eformation, the joint angle 06
may be set to more than 90" to 150'. In this case, the sandwich metal sheet 13 can
be further rcduccd in weight. In the case where the joint angle Oh is set lo
approximately 150°, as described in the fourth embodiment described latcr, it is
preferable that a resin layer 21 be formed on the surface of the second metal sheet
20b. In this case, the joint point is reinforced by the resm layer 21.
5 [0092]
Here, the joint angle 06 is found by the following procedure. That is, a
cross section that passes through the joint point of the second metal sheet 20b and the
truss 50a (herein, the bottom vertex 51 b of the truss 50a) and is perpendicular to the
second metal sheet 20b is defined. Then, the lines of intersection of the cross
10 section and the truss 50a are specified, and the angle determined by the lines of
intersection and the joint point is taken as the joint angle 06. The magnitude of the
joint angle O6 may vary depending on how to define the cross section; it is preferable
that the joint angle 06 satisfy the condition prescribed in the embodiment however the
cross section is defined.
15 [0093]
Here, the distance WL, between bottom vertices 41b joined to the first metal
sheet 20a is preferably more than or equal to 0.4 times and less than or equal to 4.0
times and more preferably more than or equal to 1.0 time and less than or equal to
1.8 times the total thickness of the sandwich metal sheet 11. Similarly, the distance
20 WL2 between bottom vertices 5 lb joined to the second metal sheet 20b is preferably
more than or equal to 0.4 times and less than or equal to 4.0 timcs and more
preferably more than or equal to 1.0 time and less than or equal to 1.8 times the total
thickness of the sandwich metal sheet 11. When the distances WL~an d W L ~
between vertices are values in these ranges, the strength of the folded portion,
25 moldability, and external appearance of the sandwich metal sheet 13 are further
improved.
[0094]
It is more preferable that at least one of the distances WL1a nd W Lb~et ween
vertices satisfy the condition of Mathematical Formula (1) described above. From
30 the viewpoint of preventing the caving-in of the first metal sheet 20a and the second
metal sheet 20b, the distance Wid! between vertices is preferably less than or equal to
30 timcs and more preferably less than or equal to 10 timcs the thickness t, of the
first metal shcct 20a. Similarly, the distance WL2 between vertices is preferably less
than or equal to 30 timcs and more preferably less than or equal to 10 times the
thicltness tz of the second metal sheet 20b.
5 [0095]
(4-2. Method for producing the sandwich metal slieet)
The sandwich metal sheet 13 can be fabricated by the following steps.
First, the first truss structure body 40 and the second truss structure body 50 arc
fabricated by similar steps to the first embodiment. Then, the top vertex 41a of the
10 first truss stmcture body 40 and the top vertex 51a of the second truss structure body
50 are joined together, and thereby the core layer 30a is fabricated. The method h r
joining may be similar to the method for joining the first metal sheet 20a and the
second metal sheet 20b, and the core layer 30. After that, similar steps to the first
embodiment are performed; thus, the sandwich metal sheet 13 is fabricated
15 [0096]
15. Fourth embodiment>
(5-1. Overall configuration of the sandwich metal sheet>
Next, a fourth embodiment is described based on FIG. 12. A sandwich
metal sheet 14 according to the fourth embodiment is a sandwich metal sheet in
20 which a resin layer 21 is added to the sandwich metal sheet 13 according to the third
embodiment.
[0097]
Specifically, the resin layer 21 is provided on each of a surface of the first
metal sheet 20a (the surface on the core layer 30 side), a surface of the second metal
26 sheet 20b (the surface on the core layer 30 side), and the joint portion of the first
truss structure body 40 and the second truss structure body 50. In the embodiment,
the resin layers 21 may be distinguished by referring to the resin layer 21 on the first
metal sheet 20a as a first resin layer 21a, the resin layer 21 on the second metal sheet
20b as a second resin layer 21 b, and the resin layer 21 on the joint portion of the first
30 truss structure body 40 and thc sccond truss structure body 50 as a third resin layer
21c. Ally one of the first resin layer 21a, the second icsin layer 21b, and the third
resin layer 21c may be omitted.
[0098]
The bottom vertices 41 b and 5 1 b of the first truss structure body 40 and the
second truss structure body 50 have sunk in the first resin layer 21a and the sccond
5 resin layer 21b, and arc joined to the first metal sheet 20a and the second metal shcct
20b. Further, the top vertices 41a and 51a ol: the lirst truss structure body 40 and
the second truss structure body 50 have sunk in the third resin layer 21c, and are
joined to each other. Thus, in the fourth embodiment, the joint points of the first
truss structure body 40 and the second truss structure body 50, and the first metal
10 sheet 20a and the second metal sheet 20b are protected by the first resin layer 21a
and the second resin layer 21b. Further, also the joint point of the first truss
structure body 40 and the second truss structure body 50 is protected by the third
resin layer 21c.
[0099]
15 The resin that forms the resin layer 21 is not particularly limited, and the
resin layer 21 may be formed of a similar resin to the second embodiment. In this
case, a similar effect to the second embodiment is obtained. Furthermore, an
adhesive for joining the first truss structure body 40 and the second truss structure
body 50 together is not needed. Furthermore, the peel strength between the first
20 truss structure body 40 and the second truss structure body 50 can be improved.
Moreover, the first lruss structure body 40 and the second truss structure body 50 can
be joined together by simply forming the third resin layer 21c on the top vertices 41a
of the first truss structure body 40. Therefore, the productivity of the sandwich
metal sheet 14 is improved.
25 [OlOO]
The thickness tal of the first resin layer 21a, the thickness ta2 of the second
resin layer 21b, and the thickness ta3 of the third resin layer 21c are not particularly
limited. I-Iowcver, the sum total of the thicknesses tal, ta2, and ta3 (the total
thickness of the resin layers 21) may be made to substantially coincide with the
30 distance between the first metal sheet 20a and the second metal sheet 20b. By
making the total thiclmess of rhc resin layers 21 substantially coincide with the
distance between the lirst metal sheet 20a and the second metal sheet 20b, the
strength of the sandwich metal sheet 12 to compressive deformation in thc sheet
thiclaess direction can be further improved. Furthermore, the first metal sheet 20a
and the second metal sheet 20b are held by not only the first truss structure body 40
5 and the second truss structure body 50 but also the resin layer 21. IIence, the first
metal sheet 20a and the second metal sheet 20b are less likely to shift in the thickness
direction of the sandwich metal sheet 15 (less likely to sink in the thicliness
direction) during the cutting of the sandwich metal sheet 15.
[OlOl]
10 (5-2. Method for producing the sandwich metal sheet)
The sandwich metal sheet 14 can be fabricated by the following steps.
First, the first truss structure body 40 and the second truss structure body 50 are
fabricated by similar steps to the first embodiment. Then, the top vertcx 41a of the
first truss structure body 40 and the top vertex 5 la of the second truss structure body
15 50 are joined together, and thereby the core layer 30a is fabricated. Specifically, a
resin sheet is stacked on the top vertices 41a of the first truss structure body 40.
Subsequently, heating or the like is performed to soften the resin sheet.
Subsequently, the second truss structure body 50 is pushed from on the resin sheet to
the first truss structure body 40, and thereby the top vertex 41a of the first truss
20 structure body 40 and the top vertex 51a of the second truss structure body 50 are
brought into contact. Subsequently, the resin sheet is subjected to cooling or the
like to harden the resin sheet. Thereby, the first truss structure body 40 and the
second truss structure body 50 are joined to each other. The resin sheet forms the
third resin layer 21c. However, from the viewpoint of further ensuring joining
25 strength, a joining method similar to the method of the first embodiment may be
further performed. After that, similar steps to the third embodiment are performed;
thus, the sandwich metal sheet 14 is fabricated.
[O 1021
<6. Fifth embodiment>
30 (6-1. Overall configuration of the sandwich metal sheet>
Next, a iifth embodiment is described based on FIG. 13. A sandwich metal
sheet 15 according to the fifth embodiment is a sandwich metal sheet in which the
core layer 30 is formed only of the first truss structure body 40 and the space
between the first metal sheet 20a and the second metal shcet 20b is filled with a resin
layer 21. That is, in the fifth embodiment, the first mctal sheet 20a is joined to tllc
6 top vertex 41a of the first truss structure body 40 (a first vertex), and the second
metal shect 20b is joined to the bottom vertex 41b of the first truss structure body 40
(a second vertex). The resin layer 21 is provided on the surfaces on the core layer
30 side of the first metal sheet 20a and the second metal sheet 20b.
[0103]
10 The resin that forms the resin layer 21 is not particularly limited, and the
resin layer 21 may be formed of a similar resin to the second embodiment. The
thickness of the resin layer 21, however, substantially coincides with the distance
between the first metal sheet 20a and the second metal sheet 20b (= h). In the fifth
embodiment, the strengths to shear deformation and compressive deformation in the
15 sheet thickness direction are larger than in a sandwich metal sheet in which the space
between the first metal sheet 20a and the second metal sheet 20b is filled only with
resin. However, since the number of truss structure bodies is small, the strengths to
shear deformation and compressive deformation in the sheet thickness direction are
smaller than in the sandwich metal sheet 12 shown in FIG. 10.
20 [0104]
Further, the first metal sheet 20a and the second metal sheet 20b are held not
only by the first truss structure body 40 but also by the resin layer 21. Hence, the
first metal sheet 20a and the second metal sheet 20b are less likely to shift in the
thickness direction of the sandwich metal sheet 15 (less likely to sink in the thickness
25 direction) during the cutting of the sandwich metal sheet 15.
[0105]
Although in the example of FIG. 13 the thickness of the resin layer 21
substantially coincides with the distance between the first metal sheet 20a and the
second metal sheet 20b (= h), the thickness of the resin layer 21 may also be smaller
30 than the distance between the first metal sheet 20a and the second metal sheet 20b (=
h). In this case, the resin layer 21 is formed on each (or either one) of the surface of
the first metal sheet 20a and the surface of the second metal sheet 20b, and the total
thiclmess ofthe resin laycr(s) 21 is smaller than the distance between the first metal
sheet 20a and the second metal sheet 20b (= h).
10 1061
5 (6-2. Method for producing the sandwich metal sheet)
The sandwich metal sheet 15 can be fabricated by the following steps.
First, the first truss structure body 40 is fabricated by similar steps to the first
embodiment. Subsequently, a resin sheet is staclted on the surface of the first metal
sheet 20a, and thereby the resin layer 21 (the first resin layer 21a) is formed on the
10 surface of the first metal sheet 20a. Similar steps are performed to form the resin
layer 21 (the second resin layer 21b) on the surface of the second metal sheet 20b.
Here, the total thickness of the first resin layer 21a and the second resin layer 21b
substantially coincides with the distance between the first metal sheet 20a and the
second metal sheet 20b (= h). It is also possible to fonn the resin layer 21 only on
15 the surface of the first metal sheet 20a (or the second metal sheet 20b) and make the
thickness of the resin layer 21 substantially coincide with the distance between the
first metal sheet 20a and the second metal sheet 20b (= h). The total thickness of
the resin layer(s) 21 may also be smaller than the distance between the first metal
sheet 20a and the second metal sheet 20b (= h).
20 [0107]
Subsequenlly, the first resin layer 21a and the second resin layer 21b are
subjected to heating or the like to soften the first resin layer 21a and the second resin
layer 21b. Subsequently, the core layer 30, and the first metal sheet 20a and the
second metal sheet 20b are joined. At this time, the first truss structure body 40
25 pushes aside the first resin layer 21a and the second resin layer 21b, and comes into
contact with the first metal sheet 20a and the second metal sheet 20b. The first
resin layer 21a and the second resin layer 21b are combined, and a resin layer 21
formed of a single layer is formed. After that, the resin layer 21 is subjected to
cooling or the like to harden the resin layer 21. Thereby, the first truss structure
30 body 40 is joined to the first mclal sheet 20a and the sccond metal sheet 20b. That
is, the first resin layer 21a and tile second resin layer 21b function as an adhesive.
However, Srom the viewpoint of further cnsuriilg joining strength, a joining method
similar to the method of the first e~nbodiment may be further performed. By thc
above steps, the sandwich metal sheet 15 is fabricated.
[Examples]
5 [0108]
(Example 1)
(Fabrication o'the sandwich metal sheet)
In Example 1, the first truss structure body 40 and the second truss structure
body 50 were fabricated by the following production method. That is, an expanded
10 metal in which a large number of square openings were formed (material: SPCC (JIS
G 3141); the thickness of the frame: 0.8 mm) was prepared, and the expanded metal
was press-molded with a mold provided with a V-shaped trench; thereby, one row of
regular tetragonal pyramidal trusses 40a was fabricated. Then, the expanded metal
was press-molded repeatedly with a similar mold, and thereby a first truss structure
15 body 40 in which trusses 40a are arranged in a matrix configuration was produced.
Also a second truss structure body 50 having the same structure as the first truss
structure body 40 was fabricated by similar steps.
[0109]
Then, the first truss structure body 40 and the second truss structure body 50
20 were superimposed so that the vertex 51 of the second truss structure body 50 was
placed between vertices 41 of the first truss structure body 40. Specifici~llyt,h e first
truss structure body 40 and the second truss structure body 50 were superimposed so
that the top vertex 5 la of the second truss structure body 50 was placed at the center
between top vertices 41a of the first truss structure body 40 and the bottom vertex
25 51b of the second truss structure body 50 was placed at the center between bottom
vertices 41b of the first truss structure body 40. Thereby, the core layer 30 was
fabricated. Subsequentll: a plurality of types of cold rolled steel sheets with
difTerent thiclu~esses( metal sheets 20) were prepared, and the metal sheets 20 were
used to fabricate a plurality of types of sandwich metal sheets 11 in which the
30 distances WLI and WL2 between vertices were 0.35, 0.40, 1.0, 1.4, 1.8, 4.0, and 4.5
times the total thicltness of the Sandwich metal sheet 11 (Examples). The metal
sheets 20 and the core layer 30 were joined by an adhesive (epoxy-based).
[OllO]
In each sandwich metal sheet 11, the thicknesses of the first metal sheet 20a
and the second metal sheet 20b were set equal to each othel; and the distances WI,~
5 and WL2 between vertices were sct to 10 times the thickness of the metal sheet 20 (i.e.
the first metal sheet 20a or the second metal sheet 20b).
[0111]
(Folding test)
A folding test was performed by the following method. Specifically, with
10 the distance between supporting points set to 100 mm, the test piece was pushed in
up to 50 mm by a punch 5R. Then, the change in the angle of the top vertex of the
tmss of the folded portion, that is, the joint angle ell was measured by visual
inspection. Consequently, it was found that the change in the joint angle fJll in the
case where the distances WLI a nd WI,~be tween vertices were 0.40, 1.0, 1.4, 1.8, and
15 4.0 times the total thickness of the sandwich metal sheet 11 was smaller than the
change in the joint angle 011 in the case where the distances WL,1a nd W Lb~et ween
vertices were 0.35 and 4.5 times the total thickness of the sandwich metal sheet 11.
Further, it was found that the change in the joint angle ell in the case where the
distances WL1 and Wlz between vertices were 1.0, 1.4, and 1.8 times the total
20 thickness of the sandwich metal sheet 11 was smaller than the change in the joint
angle €Il1 in the casc where the distances WL1 and WLZ between vertices were 0.40
and 4.0 times the total thickness of the sandwich metal sheet 11.
[OllZ]
When the folded portion of each sandwich metal sheet 11 was observed by
25 visual inspection, the caving-in of the metal sheet 20 to the core layer 30 was hardly
seen.
[0113]
Consequently, it has been found that the strength of the folded portion,
moldability, and external appearance are improved more when the distances WLa~n d
30 WL2 between vertices are more than or equal to 0.4 times and lcss than or equal to
4.0 times the total thickness of thc sandwich metal sheet 11. It has also been found
that the distances Wti and W Lb~et ween vertices are more preferably inore than or
equal to 1.0 time and less than or equal to 1.8 times thc total thickness of the
sandwich mctal sheet 11. It has also been found that the metal sheet 20 hardly
caves into the core layer 30 when the distances WLI and W1.2 betwcetl vertices are
5 less than or equal to 10 times the thickness of the mctal sheet 20.
[0114]
Next, as Comparative Example 1, a sandwich metal sheet 100 (Comparative
Example 1) in which only the first truss structure body 40 was used for the core layer
30 was fabricated. The distances WL~an d Wu between vertices of the sandwich
10 metal sheet 100 were 0.40 times the total thickness of the sandwich metal sheet 100,
and were 10 times the thickness of the metal sheet 20 (i.e. the first metal sheet 20a or
the second metal sheet 20b). A similar folding test to Example 1 was performed,
and it has been found that the change in the joint angle €I7of the sandwich metal
sheet 100 according to Comparative Example is larger than the change in the joint
15 angle 011 of each of the sandwich metal sheets 11 according to Example 1, and the
metal sheet 20 caves into the core layer 30. From the above results, it has been
found that, in the sandwich metal sheet 11 according to Example, the strength of the
folded portion, moldability, and external appearance are improved over the sandwich
metal sheet 100 according to Comparative Example.
20 [0115]
(Example 2)
A core layer 30a according to Example 2 was fabricated by joining together
the top vertices 41a and 51a of the first truss structure body 40 and the second truss
structure body 50 fabricated in Example 1. Subsequently, a plurality of types of
25 cold rolled steel sheets with different thicknesses (metal sheets 20) were prepared,
and the metal sheets 20 were used to fabricate a plurality of types of sandwich metal
sheets 13 in which the distances W1.1 and Wl,z between vertices were 0.35, 0.40, l .O,
1.4, 1.8, 4.0, and 4.5 times the total thickness of the sandwich metal sheet 13
(Examples). The joining of the metal sheet 20 and the core layer 30a and the
30 joining of the first truss structure body 40 and the second truss structure body 50
were performed by a similar method to Example 1. In each sandwich metal sheet
13, the thiclacsses of the first metal sheet 20a and the second metal sheet 20b were
set equal to each other, and the distances WLI a nd W Lb~et ween vertices were sel to
10 times the thickness of the metal sheet 20 (i.e. the Grst metal sheet 20a or the
second metal sheet 20b).
5 [0116]
Next, as a core layer of Comparative Example 2, a truss structure body
having a size of the tmss of twice the size of the truss 40a was prepared. After that,
similar steps to Example 2 were performed; thus, a sandwich metal sheet 100
according to Comparative Example 2 was fabricated. The distances WLI and Wt2
10 between vertices ofthe sandwich metal sheet 100 were 0.40 times the total thickness
of the sandwich metal sheet 100, and were 10 times the thickness of the metal sheet
20 (i.e. the first metal sheet 20a or the second metal sheet 20b). A similar folding
test to Example 1 was performed on each of the sandwich metal sheets 13 and 100.
Consequently, similar results to Example 1 were obtained.
15 [0117]
(Example 3)
Sandwich metal sheets 11 in which the distances WL1 and W Lb~e tween
vertices were 0.40 times the total thickness of the sandwich metal sheet 11 and were
30 times and 35 times the thickness of the metal sheet 20 (i.e. the first metal sheet
20 20a or the second metal sheet 20b) were fabricated by a similar production method to
Example 1. Then, a similar folding test to Example 1 was perfornlcd, and the
folded portion was observed by visual inspection. Consequently, when the
distances W,,, and W Lb~et ween vertices were 30 times the thickness of the metal
sheet 20, a little caving-in of the metal sheet 20 to the core layer 30 was seen.
25 Further, when the distances W L ~an d WL2 between vertices were 35 times the
thickness of the metal sheet 20, further caving-in of the metal sheet 20 to the core
layer 30 was seen. Consequently, it has been found that, from the viewpoint of
preventing the caving-in of the metal sheet 20, the distances WI,, and WLZ between
vertices are prelerably less than or equal to 30 times and more preferably less than or
30 equal to 10 times the thickness of the metal sheet 20. A similar experiment was
performed on the sandwich metal sheet 13 of Example 2, and similar results were
obtained.
[0118]
Thc prelerred embodiment(s) of the present disclosure hasthave bccn
described abovc with refercnce to the accompanying drawings, whilst the prescnt
5 disclosure is not limited to the above examples. A person skilled in the art may find
various alterations and modifications within the scope orthe appended claims, and it
should be understood that they will naturally come under the technical scope of the
prescnt disclosure.
[0119]
10 For example, although in the above embodiments the core layer 30 is
fabricated using two bodies of the first truss structure body 40 and the second truss
structure body 50, the core layer 30 may be fabricated using three or more truss
structure bodies.
Reference Signs List
[0120]
10 sandwich metal sheet
20 metal sheet
20a first metal sheet
20 20b second metal sheet
2 1 resin layer
21a first resin layer
21b second resin layer
21c third resin layer
25 30,30a core layer
40 first truss structure body
4 1 vertex
50 second truss structure body
5 1 vertex
30
CLAIMS
Claim 1
A sandwich metal sheet compnsing:
a core layer including a first truss structure body and a second truss structulc
5 body in which trusses formed of frames are arranged in a matrix configuration;
a first metal sheet provided on one surface of the corc layer and joined to at
least a vertex of the iirst truss structure body; and
a second metal sheet provided on another surface of the core layer and
joined to at least a vertex of the second truss structure body,
10 wherein the first truss structure body is joined to at least one ol' the second
truss structure body and the second metal sheet, and
the second truss structure body is joined to at least one of the first truss
structure body and the first metal sheet.
15 Claim 2
The sandwich metal sheet according to claim 1, wherein the frame is formed
of a metal.
Claim 3
20 The sandwich metal sheet according to claim 2, wherein at least one of the
first truss structue body and the second truss structure body is fabricated by molding
a metal sheet.
Claim 4
25 The sandwich metal sheet according to claim 3, wherein at least one of the
first truss structure body and the second truss structure body is fabricated by molding
a punched metal.
Claim 5
30 The sandwich metal sheet according to claim 1, wherein the frame is fo~.ined
of a resin.
Claim 6
The sandwich metal sheet according to any one of claiius 1 to 5,
wherein vertices of the kirst truss structure body arc joined to the first metal
5 sheet and the second metal sheet, and
vertices of the second truss stiucture body are joined to the first metal sheet
and the second metal sheet, and each of the vertices is placed between vertices of the
first trnss structure body.
10 Claim 7
The sandwich metal sheet according to claim 6, wherein a vertex of the
second truss structure body is placed at a center between vertices of the first truss
structure body.
15 Claim 8
The sandwich metal sheet according to claim 6 or 7, comprising at least one
resin layer formed on at least one of a surface on a side of the core layer of the first
metal sheet and a surface on a side of the core layer of the second metal sheet.
20 Claim 9
The sandwich metal sheet according to claim 8, wherein a total ihickness of
the at least one resin layer substantially coincides with a thickness of the core layer.
Claim 10
25 The sandwich metal sheet according to claim 8 or 9, wherein the at least one
resin layer is formed of a thermoplastic resin.
Claim 11
The sandwich metal sheet according to any one of claims 1 to 5,
30 wherein the second truss structure body is stacked on the first truss structure
body, and
a vertex of the first truss structure body and a vertex of the sccond truss
structure body are joined togethcr.
Claim 12
5 The sandwich metal sheet according to claiin 11, comprising at least one
resin layer formed on at least one of a surface on a side of the core layer of the first
metal sheet, a surface on a side of the core layer of the second metal sheet, and a
joint portion of the first truss structure body and the second truss structure body.
10 Claim 13
The sandwich metal sheet according to claim 12, wherein a total thickness
of the at least one resin layer substantially coincides with a thickness of the core layer.
Claim 14
15 The sandwich metal sheet according to claim 12 or 13, wherein the at least
one resin layer is formed of a thermoplastic resin.
Claim 15
The sandwich metal sheet according to any one of claims 1 to 14, wherein at
20 least one of a distance between vellices joined to the first inetal sheet and a distance
between vertices joined to the second metal sheet is more than or equal Lo 0.4 times
and less than or equal to 4.0 times a total thickness of the sandwich metal sheet.
Claim 16
25 The sandwich metal sheet according to any one of claims 1 to 15, wherein at
least one of a distance between vertices joined to the first metal sheet and a distance
between vertices joined to the second metal sheet satisfies the condition of
Mathematical Formula (1) below,
0.57 5 wih 5 3.71a (I)
30 where w represents the distance between verticcs joined to the first mctal
sheet or the distance between vei?lccs joined to the second illeta1 sheet,
11 rcpreseiits a djsta~lceb etween the first metal sheel and the second metal
sheet, 2nd
a represents a rate of clsange in a joint aiigle of the core layer and the first
metal sheet or the second metal sheet at a time of folding processing.
5
Claim 17
The saiidwich ineiai sl~eeatc cording to any one of claims 1 to 16, wllereiil a
joint angle of the core layer and the first metal sheet or the second illeta1 sheet is 60
to 150'.
10
Claim 18
A sandwich metal sheet comprising:
a core layer including a tn~ss structure body in which trusses formed of
metal frames are arranged in a matrix configuration;
15 a fist metal sheet provided on one surface of the core layer and joined to a
first vertex included in tl~etr uss structure body;
a second metal sheet provided on another surface of the core layer and
joined to a second vertex included in the truss structure body; and
at least one resin layer formed on at least one of a surface on a side of the
20 core layer of the first metal sheet and a surface on a side of the core layer of the
second metal sheet.