FRONT FLOOR PANEL
Technical Field
This invention relates to a front floor panel. Specially, the present invention
5 relates to a fiont floor panel that configures a platform of an automotive body.
Background Art
Most of the present automotive bodies are configured with monocoque bodies,
each of which is formed by integrating a frame and a body that typically constitute a
10 frame body, and the lower part of the body has a structure called a platform.
Figure 19 is an explanatory view schematically showing a structure of a platform
102 of an automotive body 10 1 in a simplified form.
As shown in this drawing, the platform 102 of the automotive body 10 1 is
disposed in a part corresponding to the conventional frame. A dash panel 103 and
15 a fi-ont floor panel 104 of the platform 102 are joined to each other with respective
edge portions overlapped on each other, and the front floor panel 104 and a rear
floor panel 106 are joined to each other with respective edge portions overlapped on
each other.
A dash upper panel 103a and a dash lower panel 103b of the dash panel 103
2 0 are joined to each other with respective edge portions overlapped on each other.
The dash panel 103 is a partition wall between an engine compartment in which an
engine is placed and a cabin for vehicle occupants.
The front floor panel 104 has a floor tunnel 104a, upright flanges 104b
disposed left and right, and plane portions 104c disposed left and right. The floor
2 5 tunnel 104a provides a space for storing a propeller shaft and various kinds of piping
in the center in the automotive width direction. The upright flanges 104b disposed
left and right are joint portions for being joined to left and right side sills 105 having
a closed section structure. The left and right plane portions 104c connects the floor
tunnel 104a and the upright flanges 104b disposed left and right.
30 A rear floor front panel 106a and a rear floor rear panel 106b of the rear floor
panel 106 are joined to each other with respective edge portions overlapped on each
other.
The fiont floor panel 104 is required to have bending stiffhess and torsional
stiffhess enough to suppress elastic deformation of a body due to a static load
received fiom a mounted component such as a front seat and a load to the body £kom
'four tires while running. Furthermore, the front floor panel 104 is required to
5 suppress occurrence of noise and vibration while running as much as possible so as
to avoid uncomfortableness to the occupants, and to reduce weight to improve he1
efficiency of the automobile.
In order to meet such requirements, the art to obtain high stifiess and
excellent noise and vibration characteristics without increasing the weight of a front
10 floor panel by providing an convex-concave shape in a region that is to be the plane
portion of the fiont floor panel is known.
For example, Patent Document 1 discloses the art of reducing
uncornfortableness to occupants and increasing stifiess of the floor panel by
increasing the resonance frequency of a floor panel, by forming convex portions on
15 the floor panel, each of which is configured by combining the identical isosceles
triangles so that a plane thereof has a particular angle.
Patent Document 2 discloses an insulator capable of securing sufficient
stiffiess without increasing the sheet thickness by forming a number of convex
portions by embossing a heat insulator that is provided on a dash panel fiont surface
2 0 or a lower part of a floor panel, with the convex portions having hexagonal shapes in
plan view and the longitudinal sections which pass vertices forming a diagonal and
are arc-shaped, and by arranging the convex portions so that flat sheet portions do
not pass rectilinearly among the convex portions.
Patent Document 3 discloses the invention that reduces the sheet thickness of
2 5 the floor panel while increasing stiffness with respect to the automobile width
direction of the floor panel, by providing a bulged part that crossed with the floor
tunnel and is oriented to the automobile width direction in the floor panel having the
floor tunnel extended longitudinally in the central part of the automobile width
direction.
30 The conventional technologies disclosed by Patent Documents 1 to 3 each
aims at increasing stiffness, and noise and vibration characteristics by providing an
convex-concave part in the entire front floor panel or the center of the plane portion.
However, according to the research of the present inventors, the advantageous effect
of increasing stiffness to such an extent that can reduce the sheet thickness of a floor
panel cannot be obtained by using the technology disclosed in Patent Document 1,
the manufacturing cost inevitably increases since a number of convex portions are
5 formed in the sheet material by using the technology disclosed in Patent Document 2,
and further, the technology disclosed in Patent Document 3 has the problem of an
increase in stifhess anisotropy toward the end portions at the front and the rear of
the floor panel.
Non Patent Document 1 and Patent Documents 4 to 9 do not necessarily
10 relate to front floor panels, but disclose sheet materials or panels for automotive
component members including convex-concave parts that can reduce stifiess
anisotropy each by providing the identical shapes and areas for both top surfaces of
convex-concave shapes that protrude in the up and down directions from the
reference plane, and making the second moment of area large in every cross section.
15
Prior Art Documents
Patent Document
Patent Document 1 : Japanese Patent Laid-Open No. 2009-286249
Patent Document 2: Japanese Patent No. 4402745
2 0 Patent Document 3: Japanese Patent Laid-Open No. 2002-302071
Patent Document 4: Japanese Patent Laid-Open No. 201 1-27248
Patent Document 5: Japanese Patent Laid-Open No. 20 1 1 - 10 1893
Patent Document 6: Japanese Patent Laid-Open No. 201 1- 1 10847
Patent Document 7: Japanese Patent Laid-Open No. 20 1 1 - 1 10954
2 5 Patent Document 8: Japanese Patent Laid-Open No. 20 1 1 - 1 10983
Patent Document 9: Japanese Patent Laid-Open No. 20 1 1-230 174
Non Patent Document
Non Patent Document 1 : CD-ROM of transactions of the JSME, p. 102- 107, The
Japanese Society of Mechanical Engineers, The 20" Mechanical DesigdSystems
3 0 Lecture Meeting
Summary of the Invention
Problem which the Invention is to Solve
Adopting the convex-concave parts disclosed in Non Patent Document 1, and
Patent Documents 4 to 9 on front floor panels may achieve high stiffiess without
increasing the weights of the front floor panels. In fact, it is conceivable that if the
5 front floor panel could be formed into the convex-concave shape by press forming
that is conventionally used, and particularly if the convex-concave part could be
formed in a bottom dead center of press forming, the front floor panel having the
convex-concave part could be efficiently manufactured.
However, as a result of the research of the present inventors, even if the
10 convex-concave parts are formed on the entire surface of the front floor panel made
of a metal (for example, made of steel), it is actually impossible to manufacture the
floor panel by press forming, because an extremely high forming load is necessary
for press forming. Therefore, it is conceivable to limit the portion to be formed
into the convex-concave part so as to be able to form the shape of the convex-
15 concave part without the forming load when press forming, for example, becoming
excessively large, but the method for achieving desired stiffhess and noise and
vibration characteristics is not even implied by any of the documents.
Further, as described above with reference to Figure 19, the front floor panel
104 not only has the floor tunnel 1044 the upright flanges 104b disposed left and
2 0 right and the left and right plane portions 104c, but also has a front end portion 104d
joined to a lower end portion of the dash lower panel 103b, a rear end portion 104e
joined to a front end of the rear floor front panel 106% and the upright flanges 104b
disposed left and right at both side portions joined to the leR and right side sills 105.
Therefore, depending on the forming method of the convex-concave part, the fiont
2 5 floor panel may have stifhess anisotropy, and desired stifhess and noise and
vibration characteristics are not achieved in the direction in which the stiffness is
low.
Means for Solving the Problem
30 The present invention is based on the technical idea of substantially
eliminating stiffness anisotropy of a front floor panel limiting a region in which an
convex-concave part is formed as much as possible, by forming the convex-concave
' part in each of shapes (shapes shown in Figures 3 to 6 and Figures 10 to 12), which
differ from the convex-concave parts disclosed by Patent Documents 4 to 9 and will
be described later, to be loop-shaped by including joint portions to hems of the floor
tunnel and side sills, instead of forming the convex-concave part in parts of centers
5 or entire region of the plane portions of the fiont floor panel as disclosed in Patent
Documents 1 and 3.
The present invention is provided as the following items (1) to (15).
(1) A front floor panel of a metal of an automotive body including a floor
tunnel formed to be oriented in a longitudinal direction of the automotive body in a
10 center in an automotive width direction of the automotive body, upright flanges
disposed left and right formed at a left and right end portions in the automotive
width direction to be joined to side sills, and a left and right plane portions formed
between the upright flanges disposed leR and right and a left and right longitudinal
wall portions of the floor tunnel,
15 the fiont floor panel having an convex-concave part described below that is
formed in a loop-shaped area including an outer edge portion of the plane portion,
and having a flat sheet-shaped portion formed in a remaining area except for the
loop-shaped area;
wherein the convex-concave part: when based on three reference planes that
2 0 are a first reference plane, an intermediate reference plane, and a second reference
plane that are three surfaces sequentially arranged in parallel to be spaced fiom one
another, a first unit area and a second unit area that are virtual squares are spread all
over with the intermediate reference plane as a reference, and one of two directions
along two sides orthogonal to each other of the virtual square is defined as a lateral
2 5 direction, whereas the other one is defined as a longitudinal direction,
the first unit area is divided into three at an optional ratio of A:B:A in the
lateral direction, namely, is divided into first divided areas that are two areas divided
at a ratio A, and a second divided area that is one area divided at a ratio B,
the second unit area is divided into three at an optional ratio of A:B:A in the
3 0 longitudinal direction, namely, is divided into second divided areas that are two
areas divided at the ratio A, and a first divided area that is one area divided at the
ratio B,
with the intermediate reference plane as a reference, the first unit areas and
the second unit areas are alternately disposed with respect to the longitudinal
direction and the lateral direction respectively, a first reference area having a
substantially I shape formed of the adjacent first divided areas, and a second
5 reference area having a substantially I shape formed of the adjacent second divided
areas are included,
the convex-concave part is a shape part that has a first area protruding toward
the first reference plane fiom the first reference area, and a second area protruding
toward the second reference plane fiom the second reference area defined on the
10 intermediate reference plane,
the first area has a first top surface obtained by projecting the first reference
area into the first reference plane at either unity or reduction magnification, and a
first side surface that connects an contour of the first top surface and an contour of
the first reference area, and
15 the second area has a second top surface obtained'by projecting the second
reference area into the second reference plane at either unity or reduction
magnification, and a second side surface that connects an contour of the second top
surface and an contour of the second reference area.
(2) The fiont floor panel according to item (I), wherein the convex-concave
2 0 part has two or more rows of areas having the substantially I shapes in the outer
edge portion. At this point, in the case of having two rows of the substantially I
shapes, for example, the substantially I shapes may be continuously disposed one by
one in the width direction to make two rows, or 0.5, one and 0.5 of the substantially
I shapes may be continuously disposed in the width direction to make two rows in
25 total.
(3) The fiont floor panel according to item (2), wherein an area of the loopshaped
area is fiom 40% to 85% of an area of the plane portion. However, if the
load performance of a pressing machine is higher, the upper limit value 85% will
increase.
30 (4) The fiont floor panel according to any one of items (1) to (3), wherein one
or two or more of the convex-concave parts are formed annularly in a partial area of
a remaining plane portion except for the loop-shaped area.
(5) The front floor panel according to any one of items (1) to (3), wherein one
or two or more of the convex-concave parts are formed rectilinearly in a partial area
of a remaining plane portion except for the loop-shaped area.
(6) The front floor panel according to item (9, wherein the two or more
5 convex-concave parts formed rectilinearly intersect each other.
(7) The front floor panel according to any one of items (1) to (6), wherein the
first reference area and the second reference area are configured by each connecting
the first divided areas and the second divided areas, and thereafter, deforming parts
of corner portions of both of the first divided areas and the second divided areas into
10 circular arc shapes in such a manner that areas of both of the first divided areas and
the second divided areas 'do not change.
(8) The front floor panel according to any one of items (1) to (7), wherein an
inclination angle 01(") of the first side surface to the intermediate reference plane
and an inclination angle 02(') of the second side surface to the intermediate
15 reference plane are respectively 10" to 90".
(9) The front floor panel according to any one of items (1) to (8), wherein at
least parts of the first reference plane, the intermediate reference plane and the
second reference plane that are sequentially arranged are respectively formed of
parallel curved surfaces.
20 (10) The front floor panel according to any one of items (1) to (9), wherein
the convex-concave part is formed by press-forming a metal sheet.
(1 1) The front floor panel according to item (lo), wherein the metal sheet is a
steel sheet with a sheet thickness t (mm) before forming of at most 0.65 mm.
(12) The front floor panel according to item (lo), wherein the metal sheet is
2 5 an aluminum alloy sheet with a sheet thickness t (mm) before forming of 0.5 rnm to
2.0 mm.
(13) The front floor panel according to any one of items (9) to (12), wherein a
ratio (Llt) of a length L (mm) of one side of the unit area composed of the virtual
square, and the sheet thickness t (mm) is 10 to 2000.
30 (14) The front floor panel according to any one of items (9) to (13), wherein
when a length of a short side of a rectangular shape formed of the area divided at the
ratio B is defined as BL (mm) with respect to the length L (mm) of the one side of
the unit area composed of the virtual square, 0.2L I BL 5 0.6L is satisfied.
(15) The front floor panel according to any one of items (9) to (14), wherein a
ratio (Hl/t) of a projection height H1 (rnm) of the first area and the sheet thickness t
5 (rnm), and a maximum inclination angle €I1(') formed of the first side surface and the
intermediate reference plane satisfy a relationship of 1 5 (Hllt) 5 -3€11 + 272, and a
ratio (H21t) of a protrusion height H2 (mm) of the second area and the sheet
thickness t (mrn), and a maximum inclination angle €I2(') formed of the second side
surface and the intermediate reference plane satisfy a relationship of 1 I (H21t) 5
10 -3€12+272.
Note that in regard with the arts disclosed in Patent Documents 4 to 9, the
improvement in stiffhess by the convex-concave part in the front floor panel
according to the present invention is much higher than the improvement in stiflhess
by the convex-concave parts that isotropically increase the stiffhess of the sheet
15 materials or the panels for automotive component members disclosed in Patent
Documents 4 to 9. Accordingly, in order to reduce the sheet thickness of the sheet
materials or the panels for automotive component members disclosed in Patent
Documents 4 to 9, the convex-concave part has to be formed in wider region of the
sheet materials or the panels for automotive component members.
20 More particularly, the present invention can increase stifhess of an aluminum
alloy sheet with a sheet thickness of 0.3 mm 15.4-fold to 22.9-fold, for example.
In contrast with the above, the invention disclosed by Patent Document 4
only increases stiffhess of an aluminum alloy sheet with a sheet thickness of 0.4 mm
approximately three-fold at most,
25 the invention disclosed by Patent Document 5 only increases stiffhess of an
aluminum alloy sheet with a sheet thickness of 0.3 mm approximately 3.2-fold, and
stiffhess of an aluminum alloy sheet with a sheet thickness of 0.9 mm approximately
8.4-fold,
the invention disclosed by Patent Document 6 only increases stiffhess of an
3 0 aluminum alloy sheet with a sheet thickness of 0.4 rnrn approximately 1.7-fold to
3.9-fold,
the invention disclosed by Patent Document 7 only incretises stiffness of an
aluminum alloy sheet with a sheet thickness of 0.9 mm approximately 7.1-fold,
the invention disclosed by Patent Document 8 only increases stiffness of an
aluminum alloy sheet with a sheet thickness of 0.9 mm approximately 9.7-fold, and
further,
the invention disclosed by Patent Document 9 only increases stiffness of an
aluminum alloy sheet with a sheet thickness of 0.3 mm approximately 3.2-fold.
Effect of Invention
According to the present invention, it is possible to provide the front floor
provided, which can be reliably press-formed without the load when press forming
becoming excessively large, can obtain desired stifiess, and noise and vibration
characteristics for all directions since there is little stifhess anisotropy, and is
formed from a lightweight metal sheet.
Brief Explanation of the Drawings
Figure 1 is an explanatory view schematically showing a formation region of
a convex-concave part in a front floor panel according to the present invention in a
simplified form.
Figure 2A is an explanatory view showing the formation region of the
convex-concave part.
Figure 2B is an explanatory view showing the formation region of the
convex-concave part.
Figure 2C is an explanatory view showing the formation region of the
convex-concave part.
Figure 2D is an explanatory view showing the formation region of the
convex-concave part.
Figure 3 is a partial plan view showing a convex-concave part of example 1.
Figure 4 is a partial enlarged view of a cross section taken along the A-A line
in Figure 3.
Figure 5 is a perspective view showing a convex-concave part of the example.
Figure 6 is an explanatory view showing the convex-concave part of the
example.
Figure 7 is a graph showing a stifiess improvement ratio of a convexconcave
part by a cantilever of the example.
5 Figure 8 is an explanatory view showing a test procedure of the example.
* Figure 9 is a graph showing a result of the example.
Figure 10 is an explanatory view showing a convex-concave part in an
example.
Figure 11 is an explanatory view showing a convex-concave part in an
10 example.
Figure 12 is an explanatory view showing a minimum unit of the convexconcave
part.
Figure 1.3A is an explanatory view showing an analysis model X in which the
convex-concave parts are formed in edges (hatching portions in Figures 1 and 13A)
15 of the plane portions of the fiont floor panel shown in Figure 1.
Figure 13B is an explanatory view showing an analysis model Y in which the
convex-concave parts are formed in the centers (parts except for the hatching
portions in Figure 1, a hatching portion in Figure 13B) of the plane portions of the
fiont floor panel shown in Figure 1.
20 Figure 13C is an explanatory view showing an analysis model Z in which the
convex-concave parts are formed into C-shapes in the edges of the plane portions of
the fiont floor panel shown in Figure 1.
Figure 14 is a graph showing effectiveness of forming the convex-concave
part into a loop shape with respect to the analysis models X to Z.
25 Figure 15A is a graph showing a relationship of a width of the convexconcave
part and stiffness of the front floor panel.
Figure 15B is a graph showing the relationship of the width of the convexconcave
part and stiffhess of the fiont floor panel.
Figure 16 is a graph showing an analysis result of bending stifhess of
3 0 analysis models X, X-1 and X-3.
Figure 17A is an explanatory view showing an analysis model C in which the
convex-concave parts are formed in the edges and intermediate portions (hatching
portions in Figure 17A) of the plane portions of the front floor panel shown in
Figure 1.
Figure 17B is an explanatory view showing an analysis model D in which the
convex-concave parts are formed in the edges and the centers (hatching portions in
5 Figure 17B) of the plane portions of the front floor panel shown in Figure 1.
Figure 18 is a graph showing an analysis result of bending stiffness of the
analysis models C, D and X.
Figure 19 is an explanatory view showing a schematic structure of a platform
of an automotive body in a simplified form.
10
Description of Embodiments
Below, the present invention will be described. Note that in the following
explanation, Figure 19 that is referred to as the conventional drawing will be also
referred to as necessary. Further, in the present description, none of the
15 expressions of shape, such as "square", are limited to the narrow concepts of
geometry; rather, such expressions include shapes that can be generally recognized
as those shapes; for example, shapes that would naturally be allowed include shapes
wherein the sides are somewhat curved, so-called fillets wherein a round and the like
needed for molding is created in a corner part, a surface, and the like, and shapes
2 0 provided with a so-called curvature. In addition, the expression 'cparallel" is not
limited to the narrow concept of geometry and may be anything that can generally
be recognized as being parallel.
Figure 1 is an explanatory view showing a formation region of a convexconcave
part 1 1 1 in a front floor panel 1 10 according to the present invention with a
2 5 part of the formation region in a simplified form. Figures 2A to 2D are explanatory
views schematically showing other examples of the formation region of the convexconcave
part 1 1 1. Here, the front floor panel 1 10 of Figure 1 corresponds to a fiont
floor panel 104 at an automotive main body lower part shown in Figure 19.
The front floor panel 110 has a floor tunnel 104% upright flanges 104b
3 0 disposed left and right, and left and right plane portions 104c, similarly to the
conventional fiont floor panel 104 shown in Figure 19. Namely, the front floor
panel 1 1 O is a panel of a metal that forms a part of a platform 102 of an automotive
body.
The floor tunnel 104a forms a space for storing, for example, a rear end
portion of a transmission and a propeller shaft, and further, various kinds of piping ,
5 in a center in an automotive width direction.
The upright flanges 104b disposed left and right are respectively formed at
left and right end portions in the automotive width direction. The upright flange
104b works as a welding margin for joining the front floor panel to a longitudinal
wall surface of a sill inner panel 105b of a side sill 105 of a closed section structure.
10 The left and right plane portions 104c are formed between the upri'ght flanges
104b disposed left and right and left and right longitudinal wall portions of the floor
tunnel 104a. The plane portion 104c is provided with a front seat and the like via a
seat cloth member not illustrated.
The platform 102 is configured by overlapping and joining respective edge
15 portions of a dash panel 103 and the aforementioned fkont floor panel 104 onto each
other, and overlapping and joining respective edge portions of the front floor panel
104 and a rear floor panel 106 onto each other.
The dash panel 103 is configured by overlapping and joining respective edge
portions of a dash upper panel 103a and a dash lower panel 103 b onto each other.
2 0 The dash panel 103 forms a partition wall between an engine compartment and a
cabin. Further, the rear floor panel 106 is configured by overlapping and joining
respective edge portions of a rear floor front panel 106a and a rear floor rear panel
106b onto each other.
In the front floor panel 1 10, the convex-concave parts 1 1 1 are formed into
2 5 loop-shapes in loop-shaped areas (areas shown by hatching in Figure 1) including
eight outer edge portions 104f in total of the respective left and right plane portions
104c.
The convex-concave part 11 1 is formed into the loop-shape as shown in
Figures 1 and 2A, and as shown in Figure 2B, one or two or more convex-concave
3 0 parts 1 1 1-1 may also be formed into loop-shapes in a partial area of a flat sheetshaped
portion. Further, as shown in Figure 2C, one or two or more convexconcave
parts 1 1 1-2 may be formed rectilinearly in a partial area of the flat plateshaped
portion, and in this case, as shown in Figure 2D, convex-concave parts 1 1 1-3
and 1 1 1-4 that are formed rectilinearly may be formed so as to intersect each other.
In the present invention, by adding a convex-concave shape to a part of the front
floor piinel, other flat portions remain, and therefore, the present invention is
5 effective for attachment or the like of a member such as a cloth member.
The present invention is a front floor panel which is increased in stifiess by
the convex-concave shape which will be described as follows, and since forming the
convex-concave shape on an entire surface is difficult depending on the kind of a
metal, and stifhess and the sheet thickness of the flat sheet, due to the complicated
10 shape of the convex-concave shape of the present invention as described above,
stifhess is increased as a whole by forming the convex-concave parts in a part of the
front floor panel, in the loop-shape in the example shown in Figure 1, for example.
More specifically, the front floor panel of the present invention can be manufactured
by pressing an ordinary flat sheet with use of a die in which the convex-concave
15 shape of the present invention is formed only in the loop-shaped portion of a certain
area in a perimeter of the front floor panel, when described with the example shown
in Figure 1. In this case, warm pressing that performs pressing after heating a flat
sheet, or a hot stamping method may be adopted. For pressing, the front floor
panel can be formed by press forming that uses a pair of dies, and as the specific
2 0 manufacturing method, preparation of dies and the like, any method that is known in
the field can be used. Note that the convex-concave shape also can be formed by
the other plastic deformation methods than press forming, such as roll forming that
uses a pair of forming rolls in which desired convex-concave shapes are engraved on
surfaces thereof, for example.
2 5 (Convex-concave shape of the Present Invention)
The convex-concave shape of the present invention is formed by combining a
first reference area and a second reference area, as will be described later with
reference to Figures 3 to 6. The first reference area and the second reference area
each presents a substantially I shape. As a form thereof, various forms can be
3 0 taken as shown in examples that will be described later. For example, as in
example 1 of the convex-concave part which will be described later, a contour shape
in which a longitudinal bar portion and lateral bar portions of the I shape have the
same widths may be adopted, or as in example 2 of the convex-concave part, a
contour shape in which a width of the longitudinal bar portion of the I shape is larger
than widths of the lateral bar portions may be adopted. Further, as shown in
example 3 of the convex-concave part, fillets may be provided at comer portions in
5 the substantially I-shaped contour.
The convex-concave part of the present invention is formed by spreading two
kinds of unit areas of the first unit area and the second unit area all over, and a state
in which a virtual square forming the unit area is divided into three in a lateral
direction shows a state in which the square is divided by two straight lines which are
10 drawn from two points that divide one side in the lateral direction forming the
square into three, and are parallel with one side in a longitudinal direction, and three
areas are formed side by side in the lateral direction.
A state in which the virtual square forming the unit area is divided into three
in the longitudinal direction shows a state in which the square is divided by two
15 straight lines which are drawn from two points that divide one side in the
longitudinal direction forming the square into three, and are parallel with one side in
the lateral direction, and three areas are formed side by side in the longitudinal
direction.
A first top surface and a second top surface that are respectively formed of
2 0 surfaces on a first reference plane and a second reference plane can be formed of
regions which protrude in opposite directions to an intermediate reference plane
from the first reference plane and the second reference plane. As shapes of the
protruded regions, dome shapes, ridge shapes, conical shapes and the like are cited
as examples, but the shapes of the protruded regions are not limited to them.
2 5 Further, in addition thereto, from the protruded region, the region may be protruded
in an opposite direction (a direction to the intermediate reference plane) to the
protruded direction.
The first reference area and the second reference area in the front floor panel
1 10 having the convex-concave part 1 1 1 may be configured by connecting a first
3 0 divided area and a second divided area respectively, and thereafter, deforming parts
of corner portions of both of them into circular arc shapes in such a manner that
areas of both of them do not change.
. Here, the comer portions mean corner portions to be convex comers in a
contour line of the first reference area, and corner portions to be convex comers in a
contour line of the second reference area. Since the comer portions of convexconcave
shape of the front floor panel 110 having the convex-concave part 11 1 can
5 be formed into smooth shapes, forming of the convex-concave part 11 1 becomes
easy, and expansion of range of application and improvement in a design quality are
achieved.
As shown in Figure 4, in the front floor panel 11 0 having the convex-concave
part 1 11, an inclination angle el(") of a first side surface relative to the intermediate
10 reference plane, and an inclination angle e2(0) of a second side surface relative to the
intermediate reference plane are preferably within a range of 10 to 90' in order to
obtain the convex-concave shape having excellent stiffhess improvement while
ensuring formability.
If the inclination angle el(") of the first side surface or the inclination angle
15 €I2(")o f the second side surface is less than lo0, it becomes difficult to make the
projection heights of the respective first area and second area large, and stiffiess
improvement ratio is reduced. Further, when the inclination angle el(") of the first
side surface or the inclination angle 02(0) of the second side surface exceeds 90°, it
becomes difficult to form the convex-concave shape.
20 Note that in the case of press-forming a metal sheet, upper limit values of the
inclination angle el(") of the first side surface and the inclination angle O2p) of the
second side surface are more preferably at most 70' from the viewpoint of
formability. Accordingly, the inclination angle 8 1 (") of the first side surface and
the inclination angle 82(O) of the second side surface are more preferably 10 to 70°.
25 The first side surface and the second side surface are formed of a plurality of
surfaces. All of the surfaces do not have to have the same inclination angles, and
the different inclination angles may be formed depending on the regions. However,
all of the inclination angles are preferably within the aforementioned preferable
range.
30 At least some or all of the first reference plane, the intermediate reference
plane and the second reference plane that are sequentially arranged in the front floor
panel 1 10 having the convex-concave part 1 1 1 are preferably formed of parallel
curved surfaces. Thereby the front floor panel 1 10 having the excellent convexconcave
part 11 1 having high stifiess can be deformed into various shapes, and the
range of application of the front floor panel 1 10 is expanded.
In the front floor panel 110, the convex-concave part 11 1 is preferably
formed by press-forming a metal sheet. In this case, besides cold press forming,
warm pressing and hot stamping method that perform press forming after the
temperature of the metal sheet is raised may be adopted.
By applying plastic deformation such as press forming such as embossing and
roll forming to a metal sheet, the convex-concave part 11 1 is easily formed. Even
when press forming is performed after the temperature of the metal sheet is raised
like warm pressing and a hot stamping method, the convex-concave part 1 1 1 can be
easily formed. Therefore, when the front floor panel 1 10 is formed from a metal
sheet, the convex-concave part 11 1 is relatively easily formed. Various metal
sheets that are plastically deformable, such as an aluminum alloy sheet, a steel sheet
and a copper alloy sheet are exemplified as the metal sheet.
In manufacturing the front floor panel 11 0, casting, cutting and the like can
be adopted, besides the above described plastic deformation.
The front floor panel 1 10 may be formed from other materials than a metal as
long as the front floor panel 1 10 has the convex-concave part 1 1 1. The front floor
panel 11 0 also can be formed from a resin sheet, for example. The convex-concave
part 1 1 1 of the front floor panel 1 10 made of a resin is formable by injection
forming, hot pressing or the like. Since the front floor panel 11 0 made of a resin
has less limitation in forming than the front floor panel 110 made of a metallic
material, flexibility in design is improved.
A sheet thickness t (mm) before forming of the metal sheet that is a starting
material of the front floor panel 1 10 having the convex-concave part 11 1 is
preferably at most 0.65 mm in the case of a steel sheet, and is preferably 0.5 to 2.0
mm in the case of an aluminum alloy sheet. If the sheet thickness of the metal
sheet of an aluminum alloy sheet is less than 0.5 mrn, there is a risk that the stifkess
that will be required as the front floor panel will be insufficient, and if the sheet
thickness of the metal sheet of an aluminum alloy sheet exceeds 2.0 mm, there is a
risk that forming of the convex-concave part 11 1 will become difficult.
A ratio (Llt) of a length L (mm) of one side of the unit area such as the first
unit area and the second unit area, and the sheet thickness t (mrn) of the metal sheet
in the fiont floor panel 1 10 having the convex-concave part 1 1 1 is preferably 10 to
2000. If the ratio (Llt) is less than 10, there is a risk that forming of the convex-
5 concave part 11 1 will be difficult, whereas if the ratio (Llt) exceeds 2000, there is a
risk that the suficient convex-concave part 1 11 cannot be formed, and stiffiess that
is required as the fiont floor panel will be insufficient.
When a length of a short side of a rectangular shape that is formed of an area
divided at a ratio B is designated as BL (mm) with respect to the length L (mm) of
10 the one side of the square, in the fiont floor panel 1 10, a relationship of 0.2L I BL 5
0.6L is preferably satisfied. If the relationship of 0.2L I BL I 0.6L is not satisfied,
there is a risk that forming of the convex-concave part 1 11 will be difficult.
It is preferable in the front floor panel 1 10 having the convex-concave part
1 1 1 that a ratio (Hllt) of a projection height H1 (mrn) of the fxst area and the sheet
15 thickness t (rnm), and the maximum inclination angle el(") formed of the first side
surface and the intermediate reference plane satisfy a relationship of 1 I (Hllt) I
-3e1 + 272, and a ratio (H2lt) of a projection height H2 (mm) of the second area and
the sheet thickness t (mm), and the maximum inclination angle 82(") formed of the
second side surface and the intermediate reference plane satisfy a relationship of 15
2 0 (H2It) 1-302 + 272.
If the above described ratio (Hllt) is less than 1, there is a risk that the effect
of improving stifiess by forming the first area will not be sufficiently obtained, and
if the above described ratio (Hllt) exceeds -3e1 + 272, there is a risk that forming of
the convex-concave part 11 1 will be difficult. Similarly, if the above described
2 5 ratio (H2lt) is less than 1, there is a risk that the effect of improving stiffhess by
forming the second area will not sufficiently obtained, and if the above described
ratio @It) exceeds -3e2 + 272, there is a risk that forming of the convex-concave
part 11 1 will be difficult.
Next, examples 1 to 3 of the convex-concave part will be described.
30 (Example 1 of Convex-concave part)
A fiont floor panel 110 having a convex-concave part 20 according to an
example of the present invention will be described with reference to Figures 3 to 6.
Here, the convex-concave parts 20 shown in Figures 3,4 and 6 are views in which
part ofthe convex-concave parts 111,111-1,111-2,111-3 and 111-4 shown in
Figures 1 and 2 is enlarged to make a detailed structure thereof understandable.
Accordingly, the numbers and dimensions of the respective unit areas are not limited
5 to those illustrated in the respective drawings.
Figure 3 is a partial plan view showing the convex-concave part 20 of
example 1. In Figure 3, portions that are contours of a first area 21 and a second
area 22 in the intermediate reference plane and do not appear as external shape lines
are shown by broken lines. The same applies to Figure 5 that will be described
10 later.
Figure 4 is a partial enlarged view of an A-A section of Figure 3, and Figure
5 is a perspective view showing the convex-concave part 20 of example 1.
Figure 6 is an explanatory view showing the convex-concave part of example
1. Figure 6 shows a shape of the convex-concave part 20 of the fiont floor panel
15 1 10 by disposition of a first reference area 213 and a second reference area 223 with
an intermediate reference plane K3 as a reference. The same applies to Figures 10
and 11 that will be described later.
The fiont floor panel 1 10 having the convex-concave part 20 as shown in
Figures 3 to 6 has the stiffness increased by having the convex-concave part 20.
20 The convex-concave part 20 is configured as enumerated below.
The convex-concave part 20 is defrned with three reference planes that are a
first reference plane K1, the intermediate reference plane K3 and a second reference
plane K2 as references. The first reference plane K1, the intermediate reference
plane K3 and the second reference plane K2 are sequentially disposed in parallel to
2 5 be spaced in a sheet thickness direction (a longitudinal direction in Figure 4), as
shown in Figure 4.
As shown in Figure 6, the intermediate reference plane K3 is defined as the
plane in which fust unit areas 23 1 and second unit areas 232 that are virtual squares
are spread all over. One of two directions along sides of the virtual square is
3 0 defined as a lateral direction (an X direction), and the other one is defined as a
longitudinal direction (a Y direction).
The first unit area 23 1 is divided into three at a ratio of A:B:A = 1 : 1 : 1 with
respect to the lateral direction (the X direction). Two areas divided at a ratio A are
defined as first divided areas 2 14, and one area divided at a ratio B is defined as a
second divided area 224.
The second unit area 232 is divided into three at a ratio of A:B:A = 1 : 1 : 1 with
respect to the longitudinal direction (the Y direction). Two areas that are divided at
the ratio A are defined as the second divided areas 224, and one area divided at the
ratio B is defined as the first divided area 214.
In the intermediate reference plane K3, the first unit areas 23 1 and the second
unit areas 232 are alternately disposed in the longitudinal direction and the lateral
direction. An area having a substantially I shape that is formed of the adjacent first
divided areas 214 is defined as the first reference area 213, whereas an area having a
substantially I shape that is formed of the adjacent second divided areas 224 is
defined as the second reference area 223.
The convex-concave part 20 includes the first area 2 1 and the second area 22
as shown in Figures 3 to 5. The first area 21 is formed so as to protrude toward the
first reference plane K1 fiom the first reference area 2 13 that is defined on the
intermediate reference plane K3. The second area 22 is formed so as to protrude.
toward the second reference plane K2 fiom the second reference area 223 defined on
the intermediate reference plane K3.
The first area 2 1 is formed of a first top surface 2 11 and a first side surface
212. The first top surface 2 1 1 is formed by projecting the first reference area 2 13
into the first reference plane K1 at either unity or reduction magnification. The
first side surface 212 is formed by connecting a contour of the first top surface 21 1
and a contour of the first reference area 2 13.
The second area 22 is formed of a second top surface 22 1 and a second side
surface 222. The second top surface 221 is formed by projecting the second
reference area 223 into the second reference plane K2 at either unity or reduction
magnification. The second side surface 222 is formed by connecting a contour of
the second top surface 22 1 and a contour of the second reference area 223.
As shown in Figure 4, the three reference planes that are the first reference
plane K1, the intermediate reference plane K3 and the second reference plane K.2 in
example 1 are planes that are parallel with one another. Further, the first top
surface 2 11 has a sheet thickness center thereof located in a position corresponding
to the first reference plane K1, and the second top surface 221 has a sheet thickness
center thereof disposed in a position corresponding to the second reference plane K2.
5 A distance formed of the first reference plane K1 and the intermediate reference
plane K3 is designated as the projection height H1 (mm), and a distance formed of
the second reference plane K2 and the intermediate reference plane K3 is designated
as the projection height H2 (mm).
Further, in example 1, the shapes and the dimensions of the first area 2 1 and
10 the second area 22 are the same, but only the protruding directions thereof differ.
The projection height H1 (mm) of the first area 21 and the projection height H2
(mm) of the second area 22 are both 1.5 rnm.
Further, a starting material of the front floor panel 110 having the convexconcave
part 20 of example 1 is a flat sheet made of an aluminum alloy with a sheet
15 thickness t = 0.30 mm.
The convex-concave part 20 is formed by press forming using a pair of dies.
Note that the convex-concave part 20 may be formed by other plastic deformation
methods than press forming, such as roll forming using a pair of forming rolls in
which desired convex-concave shapes are engraved on surfaces, for example.
20 As shown in Figure 4, the inclination angle €I1(") of the first side surface 212
relative to the intermediate reference plane K3, and the inclination angle 02(0) of the
second side surface 222 relative to the intermediate reference plane K3 are both 30".
The first side surface 2 12 and the second side surface 222 have no bent portion but
are formed continuously by one plane.
25 As shown in Figure 6, a length L of one side of the first unit area 23 1 and the
second unit area 232 with the intermediate reference plane K3 as the reference in
example 1 is 24 mm.
A ratio (Llt) of the length L (mm) of the one side of the first unit area 23 1 and
the second unit area 232 and the sheet thickness t (mm) of the aluminum alloy sheet
3 0 is 80, and is within a range of 10 to 2000.
With respect to the length L (mm) of the one side of the first unit area 23 1
and the second unit area 232, a length BL of a short side of the rectangular shape
formed of the area divided at a ratio B is 8 mm, and is within a range of 4.8 S BL 5
14.4.
A ratio (Hllt) of the projection height H1 (mm) of the first area 21 and the
sheet thickness t (mm) is 5. Further, the inclination angle 8, formed of the first
side surface 212 and the intermediate reference plane K3 is 30°, and -3e1 + 272 =
182. Accordingly, the relationship of 1 S (Hllt) 5 -3e1 + 272 is satisfied.
Similarly, a ratio (H2tt) of the projection height H2 (mm) of the second area
22 and the sheet thickness t (mm) is 5. Further, the inclination angle €I2 that is
formed of the second side surface 222 and the intermediate reference plane K3 is
30°, and -3e2 + 272 = 182. Accordingly, the relationship of 1 S (H2lt) I -3e2 +
272 is satisfied.
The front floor panel 11 0 of example 1 has the convex-concave part 20 in the
peculiar shape as described above. Namely, the convex-concave part 20 has the
first area 21 that protrudes toward the first reference plane K1 from the first
reference area 2 13 defined with the intermediate reference plane K3 as the reference,
and the second area 22 that protrudes toward the second reference plane K2 from the
second reference area 223 defined on the intermediate reference plane K3. The
first area 2 1 is formed of the first top surface 2 1 1, and the first side surface 2 12 that
is formed by connecting the contour of the first top surface 2 11 and the contour of
the first reference area 2 13. Further, the second area 22 is formed of the second top
surface 22 1, and the second side surface 222 that is formed by connecting the
contour of the second top surface 22 1 and the contour of the second reference area
The first area 2 1 and the second area 22 are formed of the first top surface
21 1 and the second top surface 221 that are disposed in positions separated in the
thickness direction of the front floor panel 1 10, and the first side surface 2 12 and the
second side surface 222 that are disposed to intersect in the thickness direction of the
fiont floor panel 110. As such, in the convex-concave part 20, most of the sheet
material is disposed in the positions separated from a neutral plane in the sheet
thickness direction of the front floor panel 110, such as a top surface portion.
Therefore, by having many portions separated from the neutral plane, the material is
effectively used as a strength member, and therefore, both stiffhess and energy
absorption characteristics can be significantly improved.
Further, an area of the first reference area 213 and an area of the second
reference area 223 are the same. Further, the inclination angles 8, and €I2th at are
5 formed of the first side surface 212 and the second side surface 222 with respect to
the intermediate reference plane K3 are made the same, and the projection heights
H1 and H2 of the first area 21 and the second area 22 are made the same.
Therefore, shapes of the first area 2 1 and the second area 22 that protrude to a front
and a back of the front floor panel 110 are also the same. Accordingly, stiffness
10 can be improved more effectively.
Further, attendant with the increase in the stiffness, it is also possible to
obtain the effect of improving damping characteristics; in addition, the concaveconvex
shape makes it possible to obtain the effect of suppressing sound
reverberations.
15 In order to quantitatively determine the stiffhess increase effect of the front
floor panel 110 of example 1, a bending stifkess evaluation of a cantilevered beam
was performed by FEM analysis, and bending stifkess evaluation by a three-point
bending test was performed.
FEM Analysis]
20 In order to quantitatively determine the stiffhess increase effect and the
energy absorption characteristics of the front floor panel 1 10 of example 1, FEM
analysis was performed and bending stiffness evaluation of a cantilevered beam was
performed.
In the FEM analysis on the bending stiffness evaluation of a cantilevered
2 5 beam, one ends (Zl, 23) were designated as fixed ends, while the other ends (22,
24) were designated as free ends, and a deflection amount of the front floor panel
1 10 that was a test piece at the time of exerting a load of 1N onto a central portion of
the other ends (Z2,Z4) that are the free ends was obtained.
The test piece has a rectangular shape of 120 mrn by 120 mm, and the shapes
3 0 of the convex-concave part 20 shown in example 1 were formed on the entire
surface for the purpose of explanation. The convex-concave shape was formed by
changing an angle formed of one side of the test piece and one side of the virtual
square in the above described unit area to the respective directions of 0, 15,30,45,
60,75 and 90". Further, the sheet thickness t after sheet forming was designated as
0.274 rnm by taking the increase in the surface area into consideration. Note that
the fix*.e., d end Z1 and the fiee end 22 shown in Figure 3 show the fixed end and the .
5 fiee end in the direction of 0 degrees, and the fixed end 23 and the fiee end 24 show
the fixed end and the fiee end in the direction of 90".
The evaluation was performed by comparing the amount of deflection
obtained by conducting the same FEM analysis on the flat sheet shaped original
sheet whereon the concave-convex part 20 is not formed.
10 Figure 7 is a graph showing the stiffness improvement ratio of the convexconcave
part of a cantilevered beam of example 1, tind shows the result of the FEM
analysis with the above described angle plotted on the horizontal axis and the
improvement ratio of the bending stiffness plotted on the vertical axis.
As shown in the graph of Figure 7, it has become clear that the improvement.
15 ratio (PI, P2) of stifiess in the 0" direction and the 90" direction are 22.9 and the
highest, the improvement ratio (P3) of stiffhess in the 45" direction is 15.4 times,
and the lowest, and the shape of the convex-concave part 20 of example 1 has a very
high improvement ratio of stiffhess in any direction of the forming directions.
[Three-Point Bending Test]
20 Figure 8 is an explanatory view showing a test procedure of the three-point
bending test of example 1.
As shown in Figure 8, in the three-point bending test, a test piece 3 1 having
the convex-concave shape of the present invention was disposed on two fulcrums W
configured by disposing two cylindrical support members lying on their sides in
2 5 parallel so that an inter-fulcrum distance S = 120 mrn is satisfied, a load was exerted
on a center in a lengthwise direction of the test piece 3 1 by a pressing jig J in a flat
sheet shape with a front end section forming a semicircle, and a displacement
amount of the test piece 3 1 was measured. Evaluation was made by performing a
similar three-point bending test with respect to the original sheet in a flat sheet shape
3 0 without forming the convex-concave shape, and comparing the load-displacement diagrams.
The test piece 3 1 was an A1050-0 material with the shape before forming
being 100 rnm x 150 mm, and the sheet thickness F0.3 mm, and the convexconcave
part 20 shown in example 1 was formed on the entire surface as a matter of
convenience. The forming direction of the convex-concave shape in the test piece
5 3 1 is similar to the cases of the 0" direction and the 45" direction in the FEM
analysis in the above described cantilever.
Figure 9 is a graph showing a result of the three-point bending test of
example 1, and is a load-displacement diagram with the load obtained fkom the
result of the three-point bending test plotted on the ordinate and the displacement
10 plotted on the abscissa.
In the same drawing, a solid iine X shows a measurement result in the case of
the convex-concave shape being provided in the 45" direction, a solid line Y shows
a measurement result in the case of the convex-concave shape being provided in the
0" direction, and a solid line Z shows a measurement result of the original sheet in a
15 flat sheet shape.
As shown by the graph of Figure 9, in the solid line X, the inclination angle at
startup is 12.1 times as compared with the solid line 2. Accordingly, it has been
clear that the bending stiffhess in the case of the convex-concave shape being
provided in the 45" direction is improved to be 12.1 times as compared with the
2 0 original sheet in a flat sheet shape. Further, in the solid line Y, the inclination
angle at startup becomes 15.4 times as compared with that of the solid line Z.
Accordingly, it has been clear that the bending stiffhess in the case of the convexconcave
shape being provided in the 0" direction is improved to be 15.4 times as
compared with that of the original sheet in a flat sheet shape.
25 Further, a product of the load and displacement is an energy amount (work
load) that deforms the test piece 3 1. Therefore, as shown in the load-displacement
diagram of Figure 9, it has been found out that in the solid line X and the solid line
Y, the energy amounts required for deformation are high as compared with that of
the solid line Z. Accordingly, it has been clear that the convex-concave shape of
3 0 example 1 significantly improves in the energy absorption amount with respect to
the original sheet in a flat sheet shape.
(Example 2 of Convex-concave part)
Figure 10 is an explanatory view showing a convex-concave part in example
2, and is a view expressing a convex-concave shape with the intermediate reference
plane K3 as a reference.
As shown in Figure 10, example 2 is a modification of the fiont floor panel
5 1 10 having the convex-concave part 20 of example 1.
The fkont floor panel 1 10 having the convex-concave part 20 that is expressed
with the intermediate reference plane K3 as a reference shown in Figure 10 is an
example in which the ratio of divisions in the first unit area 23 1 and the second unit
area 232 are changed.
The first unit area 23 1 is divided into three at a ratio of A:B:A = 1 :2: 1 in the
lateral direction. An area divided at a ratio A is defined as the first divided area
214, and an area divided at a ratio B is defined as the second divided area 224.
The second unit area 232 is divided into three at a ratio of A:B:A = 1 :2: 1 in
the longitudinal direction. An area divided at a ratio A is defined as the second
divided area 224, and an area divided at a ratio B is defined as the first divided area
214.
Note that the fkont floor panel 1 10 having the convex-concave part 20 of
example 2 has the first area 21 and the second area 22 that protrude respectively to
the first reference plane K1 and the second reference plane K2 fkom the first
reference area 2 13 and the second reference area 223 that are defined based on the
intermediate reference plane K.3 shown in Figure 10. The other configuration is
similar to that of example 1.
Example 2 exhibits an operational advantage similar to example 1.
(Example 3 of Convex-concave part)
Figure 1 1 is an explanatory view showing the convex-concave part 20 in
example 3.
As shown in Figure 1 1, example 3 is such that in the fkont floor panel 1 10
having the convex-concave part 20 of example 2, after the first reference area 2 13
and the second reference area 223 are defined with the intermediate reference plane
K3 as a reference, parts of the corner portions of both of them are deformed into
circular arc shapes in such a manner that the areas of both of them do not change.
More specifically, as shown in Figure 1 1, four convex corner portions a1
formed of a contour line of the first reference area 2 13, and four convex comer
portions a2 formed of the second reference area 223 are all deformed into circular
arc shapes.
5 In example 3, the convex-concave shape that protrudes to the first reference
plane K1 and the second reference plane K2 ftom the first reference area 2 13 and the
second reference area 223 shown in Figure 1 1 is formed. The other configuration
is similar to example 1.
Since in example 3, the shape of the corner portions of convex-concave of the
10 front floor panel 110 having the convex-concave part 20 is made smooth, forming is
facilitated, and expansion of use and improvement in a design quality are achieved.
Example 3 has an operational advantage similar to those of example 1 with
respect to the other configuration.
Figure 12 is a view explaining the minimum convex-concave part 20 that
15 exhibits the advantage as the convex-concave shape of the present invention.
Namely, the convex-concave shape of the present invention increases stifiess by a
plurality of unit areas being arranged, and to what extent at the minimum the unit
areas are arranged to obtain the advantage of the present invention will be described
with reference to Figure 12.
20 As shown in Figure 12, the convex-concave part 1 1 1 of the present invention
needs to have two or more rows of the areas each having the substantially I shape.
Namely, the loop-shaped convex-concave part 11 1 shown in Figure 1 can obtain
minimum necessary stiffhess if the convex-concave part 1 1 1 has two or more rows
ofthe areas each having at least the substantially I shape. More preferably, the
2 5 area of the loop-shaped convex-concave part 11 1 is formed to be at least 40% of the
area of the plane portion 104c. As the disposition method of the substantially I
shapes in this case, the substantially I shapes may be continuously disposed one by
one in the width direction to make two rows, or 0.5 of the substantially I shape, one
substantially I shape, and 0.5 of the substantially I shape may be disposed
3 0 continuously in the width direction to make two rows in total, when the convexconcave
part has two rows of the substantially I shapes, for example.
The sheet thickness of the conventional fiont floor panel made of steel is
approximately 0.65 mm. Since the fiont floor panel 110 according to the present
invention has the loop-shaped convex-concave part 1 11 in the plane portion 104c,
and therefore, has high stifhess, even if the sheet thickness is made as thin as
approximately 0.55 mm, the front floor panel 110 has stiffhess equivalent to that of
the conventional fkont floor panel without using an additional steel member.
Since in the fkont floor panel 110, the convex-concave part 1 11 is formed at
the forming bottom dead center in the press process, and the convex-concave part
1 1 1 is formed on a part of the plane portion 104c, instead of a whole of the plane
portion 104c, the forming load required upon press forming is prevented fkom
becoming extremely high, and the convex-concave part 11 1 can be formed at the
forming bottom dead center in the press process, whereby the fkont floor panel 1 10
having the convex-concave part 11 1 can be efficiently manufactured.
Further, since in the fkont floor panel 1 10, the convex-concave part 1 1 1 is
formed in the loop-shaped area including an outer edge portion 104f of the plane
portion 104c, the stiffhess of the front floor panel 1 10 in which the convex-concave
part 1 1 1 is formed does not have anisotropy, and therefore, desired stiffhess and
noise and vibration characteristics can be reliably obtained.
Example 1
The present invention will be described more specifically with reference to an
example. In the present example, the present invention is applied to a steel sheet,
but the present invention is not limited to this, and can be applied to any of the
materials that are known in the present technical field including the aforementioned
aluminum. Accordingly, the advantage of the present invention is also provided in
the case that the present invention is applied to an aluminum alloy sheet, for
example, and is similar to the case in which the present invention is applied to a
steel sheet. Therefore, explanation of the case of the present invention being
applied to an aluminum alloy sheet will be omitted.
Figure 13A is an explanatory view showing an analysis model X in which the
convex-concave part 1 11 is formed on edges (hatching portions in Figures 1 and
13A) of the plane portions 104c of the fkont floor panel 1 10 shown in Figure 1.
Figure 13B is an explanatory view showing an analysis model Y in which the
convex-concave part 11 1 is formed in centers (portion except for the hatching
portion in Figure 1, a hatching portion in Figure 13B) of the plane portions 104c.
Figure 13C is an explanatory view showing an analysis model Z in which the
convex-concave part 1 1 1 is formed into C-shapes in the edges of the plane portions
104c.
The analysis models X to Z shown in Figure 13A to Figure 13C were
analyzed under the conditions listed as follows.
The sheet thicknesses of the analysis models X to Z: 0.55 mm
The areas of the convex-concave parts 1 1 1 formed in the analysis models X
to Z: 43% of the plane portion 104c in each of them
The shapes of the convex-concave parts 1 11 formed in the analysis models X
to Z: the convex-concave part 20 shown in Figure 3
The convex-concave shapes 1 11 of the analysis models X to Z: A:B:A =
1:1:1,01 =e2=300,H1 =H2= 1.1 mm,theLengthLofonesideoftheunitarea=
16.1 mm (can be obtained fiom Figures 4 and 12)
In the analysis models X and Z, the widths of the formed convex-concave
parts 11 1 were Wl = 36 mm (two rows of substantially I shapes), and W4 = 72 mm
(four rows of substantially I shapes). Further, in the analysis model Y, the convexconcave
parts 11 1 are formed in centers of the plane portions 104c in a range of W2
= 146 mm and W3 = 340 mm.
The analysis method and the evaluation item: torsional stiffness in the
direction of the circled number 1 in Figure 1, and torsional stiffness in the direction
of the circled number 2 by a static implicit method (FEM) were evaluated. The
following evaluation was similarly performed.
Figure 14 is a graph showing effectiveness of forming the convex-concave
part into a loop-shape with respect to the analysis models X to Z.
As shown in the graph of Figure 14, the torsional stiffhess of the analysis
model X with the convex-concave parts 11 1 formed in the loop-shaped areas was
the highest irrespective of torsional directions. The torsional stiffhess of the
analysis model Y with the convex-concave parts 1 1 1 formed in the centers of the
plane portions 104c was the lowest, and the torsional stiffness of the analysis model
Z with the convex-concave parts 1 11 formed into the C-shapes in the plane portions
104c was between that of the analysis model X and that of the analysis model Y.
The torsional stiffness of the analysis model X was higher by 16% in the
direction of the circled number 1 in Figure 1, and was higher by 24% in the direction
of the circled number 2 as compared with the torsional stiffiess of the analysis
model Y.
In contrast with this, the torsional stiffness of the analysis model Z was higher
by 5% in the direction of the circled number 1, and was higher by 16% in the
direction of the circled number 2 as compared with the torsional stiffhess of the
analysis model Y, but was less favorable than that of the analysis model X, and the
torsional stiffiess of the analysis model X was higher by 10% in the direction of the
circled number 1, and was higher by 7% in the direction of the circled number 2 as
compared with the torsional stiffness of the analysis model Z.
As shown in the graph of Figure 14, it is indicated that the analysis model X
has the torsional stiffhess that exceeds that of the analysis models Y and Z with
respect to both the directions of the direction of the circled number 1 and the
direction of the circled number 2, and forming the convex-concave part 1 11 into a
loop-shape by including the edges of the plane portion 104c is effective.
Example 2
The analysis model X in which the substantially I shapes which form the
convex-concave part 1 1 1 in the edges (the hatching portions in Figures 1 and 13A)
of the plane portions 104c of the fiont floor panel 1 10 were constructed in two rows,
an analysis model X-1 in which the substantially I shapes were constructed in one
row, and an analysis model X-3 in which the substantially I shapes were formed in
three rows were compared. The constraint conditions and the torsional directions
were designated as the same as in example 1. The detailed conditions of the
analysis models X, X- 1 and X-3 will be shown.
The sheet thicknesses of the analysis models X, X-1 and X-3: 0.55 mm
The areas of the convex-concave parts formed in the analysis models X, X- 1
and X-3: 43% of the plane portion 104c in each
The convex-concave shapes 1 1 1 of the analysis models X, X-1 and X-3:
A:B:A = 1:l:l
The heights of the convex-concave shapes 1 1 1 of the analysis models X and
X-1: H1 = H2 = 1.1 mm
The height of the convex-concave shape 1 1 1 of the analysis model X-3 : H1=
H2 = 0.75 mm
(In the case of three rows of the substantially I shapes, it was considered as
difficult to form H1= H2 = 1.1 rnm fiom the viewpoint of formability, and therefore,
the height that satisfies €I1 = €I2 = 30" as shown in the example 1 of the convexconcave
shape 1 1 1 was adopted)
The schematic shapes of the analysis models X, X- 1 and X-3 : width W 1
formed similarly to the analysis model X in Figure 1 = 36 mm
Figure 16 is a graph showing an analysis result of torsional stifiess of the
analysis models X, X-1 and X-3.
As shown in the graph in Figure 16, the torsional stiffhess of the analysis
model X (two I shapes) was the highest. The reason why the torsional stifiess of
the analysis model X-1 (one I shape) is low is that since anisotropy becomes high,
there exist the directions in which the torsional stifiess becomes approximately the
same as that of the flat sheet. The reason why the torsional stiffhess of the analysis
model X-3 (three I shapes) is lower as compared with that of the analysis model X
(two I shapes) is that since the height (HI and H2) of the convex-concave of X-3 is
lower as compared with that of X, a second moment of area is reduced. Like this,
as the number of I shapes increases, the height of the convex-concave part 1 1 1
becomes lower, and therefore, the analysis model X that is formed of the two I
shapes had the highest torsional stiffness.
Example 3
Torsional stiflhess was analyzed similarly to example 1 with respect to the
front floor panel with a sheet thickness of 0.55 rnm, in which the widths of the edges
of the plane portion 104c were designated as 24, 36 and 48 rnm, where the convexconcave
part 1 1 1 was formed with A:B:A = 1 : 1 : 1,01 = €I2 = 30°, and the number of
the substantially I shapes included in the width direction was designated as two, and
the fkont floor panel with a sheet thickness of 0.65 mm in which the convex-concave
part 1 1 1 was not formed.
Figure 15A is a graph showing a relationship of the width of the convexconcave
part, and the torsional stifiess in the direction of the circled number 1, of
the fkont floor panel. Figure 15B is a graph showing a relationship of the width of
the convex-concave part, and the torsional stiffness in the direction of the circled
number 2, of the fkont floor panel.
As shown in the graphs in Figure 15A and Figure 1 5B, it has been found out
that the width is designated as at least 32 mm (at least 40% of the plane portion
104c), that is, the areas having the substantially I shapes are arranged in two rows
with respect to the width direction of the plane portion 104c of the fiont floor panel
1 10, whereby the sheet thickness of the fkont floor panel is reduced by 0.1 mm and
can be reduced to 0.55 mm.
Example 4
Figure 17A is an explanatory view showing an analysis model C in which the
convex-concave parts 1 1 1 are formed in the edges (hatching portions in Figures 1
and 17A) of the plane portion 104c of the fkont floor pane 1.1 0 shown in Figure 1.
Figure 17B is an explanatory view showing an analysis model D in which the
convex-concave parts 1 1 1 are formed in the edges and the centers (hatching portions
in Figure 17B) of the plane portion 104c of the fkont floor panel 1 10 shown in
Figure 1.
The analysis model C shown in Figure 17A is a model in which the convexconcave
parts 11 1-2 that are formed rectilinearly in partial areas of the flat sheetshaped
portions as shown in Figure 2C are connected to the loop-shaped convexconcave
parts 11 1, and the analysis model D is a model in which the convexconcave
parts 1 1 1-2 are not connected to the loop-shaped convex-concave parts 1 1 1.
The analysis models C and D were compared with the analysis model X.
The constraint conditions and the torsional directions are similar to those in
examples 3 and 4.
Details of the analysis models C, D and X will be shown as follows.
The sheet thicknesses of the analysis models C, D and X: 0.55 rnrn
The area of the convex-concave parts 1 11 formed in the analysis model X:
43% of the plane portion 104c
The areas of the convex-concave parts 1 1 1 formed in the analysis models C
and D: 48% of the plane portion 104c in each
5 The convex-concave shapes 1 1 1 of the analysis models C, D and X: A:B:A =
1:1:1,01 = 82 = 30°, HZ = H2 = 1.1 mm
The schematic shapes of the convex-concave parts 11 1 of the analysis models
C, D and X: refer to Figure 4
The width W 1 forming the convex-concave part 1 1 1 : 36 mm (the
10 substantially I shapes are in two rows), W5 = 80 mm
Figure 18 is a graph showing an analysis result of the torsional stiffhess of the
analysis models C, D and X.
As shown in the graph of Figure 18, the torsional stiffness of the circled
number 2 in the analysis models C and D is improved by approximately 1 to 2%
15 more than the torsional stifkess of the analysis model X. This is considered to be
because the direction in which the convex-concave part 1 1 1-2, which is formed
rectilinearly, extends is the direction that increases the torsional stiffhess of the
circled number 2.
We claim:
1 .' A front floor panel of a metal of an automotive body having a floor tunnel
formed to be oriented in a longitudinal direction of the automotive body in a center
5 in an automotive width direction of the automotive body, upright flanges disposed
left and right formed at a left and right end portions in the automotive width
direction to be joined to side sills, and a left and right plane portions formed between
the upright flanges disposed left and right and a longitudinal wall portions of the
floor tunnel disposed left and right characterized in that,
10 the front floor panel has an convex-concave part described below that is
formed in a loop-shaped area including an outer edge portion of the plane portion,
and has a flat sheet-shaped portion formed in a remaining area except for the loopshaped
area;
wherein the convex-concave part: when based on three reference planes that
15 are a first reference plane, an intermediate reference plane, and a second reference
plane that are three planes sequentially arranged in parallel to be spaced from one
another, a first unit area and a second unit area that are virtual squares are spread all
over with the intermediate reference plane as a reference, and one of two directions
along two sides orthogonal to each other of the virtual square is defined as a lateral
2 0 direction, whereas the other one is defrned as a longitudinal direction,
the first unit area is divided into three at an optional ratio of A:B:A in the
lateral direction, as a result, is divided into first divided areas that are two areas
divided at a ratio A, and a second divided area that is one area divided at a ratio B,
the second unit area is divided into three at an optional ratio of A:B:A in the
2 5 longitudinal direction, as a result, is divided into second divided areas that are two
areas divided at the ratio A, and a first divided area that is one area divided at the
ratio By
with the intermediate reference plane as a reference, the first unit areas and
the second unit areas are alternately disposed with respect to the longitudinal
3 0 direction and the lateral direction respectively, a first reference area having a
substantially I shape formed of the adjacent first divided areas, and a second
reference area having a substantially I shape formed of the adjacent second divided
areas are included,
the convex-concave part is a shape part having a first area protruding toward
the first reference plane from the first reference area, and a second area protruding
5 toward the second reference plane from the second reference area defined on the
intermediate reference plane,
the first area has a first top surface obtained by projecting the first reference
area into the first reference plane at either unity or reduction magnification, and a
first side surface that connects a contour of the first top surface and a contour of the
10 first reference area, and
the second area has a second top surface obtained by projecting the second
reference area into the second reference plane at either unity or reduction
magnification, and a second side surface that connects a contour of the second top
surface and a contour of the second reference area.
15
2. The front floor panel according to claim 1,
wherein the convex-concave part has two or more rows of areas having the
substantially I shapes in the outer edge portion.
2 0 3. The front floor panel according to claim 2,
wherein an area of the loop-shaped area is at least 40% of an area of the plane
portion.
4. The front floor panel according to any one of claims 1 to 3,
25 wherein one or two or more of the convex-concave parts are formed annularly
in a partial area of the flat sheet-shaped portion.
5. The front floor panel according to any one of claims 1 to 3,
wherein one or two or more of convex-concave parts are formed rectilinearly
3 0 in a partial area of the flat sheet-shaped portion.
6. The front floor panel according to claim 5,
wherein the two or more convex-concave parts formed rectilinearly intersect
each other.
7. The front floor panel according to any one of claims 1 to 6,
wherein the first reference area and the second reference area are configured
by connecting the first divided areas and the second divided areas respectively, and
thereafter, deforming parts of corner portions of both of the first divided areas and
the second divided areas into circular arc shapes in such a manner that areas of both
of the first divided areas and the second divided areas do not change.
8. The fiont floor panel 'according to any one of claims 1 to 7, wherein an
inclination angle 01(") of the first side surface to the intermediate reference plane
and an inclination angle 02(") of the second side surface to the intermediate
reference plane are respectively 10" to 90".
9. The fiont floor panel according to any one of claims 1 to 8,
wherein at least parts of the first reference plane, the intermediate reference
plane and the second reference plane that are sequentially arranged are respectively
formed of parallel curved surfaces.
10. The fiont floor panel according to any one of claims 1 to 9,
wherein the convex-concave part is formed by press-forming a metal sheet.
1 1. The fiont floor panel according to claim 10,
wherein the metal sheet is a steel sheet with a sheet thickness t (mm) before
forming of at most 0.65 mm.
12. The front floor panel according to claim 10,
wherein the metal sheet is an aluminum alloy sheet with a sheet thickness t
(rnm) before forming of 0.5 mm to 2.0 rnm.
13. The fiont floor panel according to any one of claims 9 to 12,
wherein a ratio (Llt) of a length L (mm) of one side of the unit area composed
of the virtual square, and the sheet thickness t (mm) is 10 to 2000.
The fkont floor panel according to any one of claims 9 to 13,
wherein when a length of a short side of a rectangular shape formed of the
area divided at the ratio B is defined as BL (mm) with respect to the length L (mm)
of the one side of the unit area composed of the virtual square, 0.2L i BL i 0.6L is
satisfied.
The fkont floor panel according to any one of claims 9 to 14,
whereid a ratio (Hllt) of a projection height H1 (mm) of the first area and the
sheet thickness t (mm), and a maximum inclination angle el(") formed of the first
side surface and the intermediate reference plane satisfy a relationship of 1 i (Hllt)
I -3e1 + 272, and a ratio (H21t) of a projection height H2 (rnm) of the second area
15 and the sheet thickness t (mm), and a maximum inclination angle e2(0) formed of the
second side surface and the intermediate reference plane satisfy a relationship of 1 s
(H2lt) i -38, + 272.