DESCRIPTION
TITLE OF INVENTION
SKELETAL COMPONENT FOR AUTOMOBILE AND FRONT PILLAR LOWER
INCLUDING THE SAME
TECHNICAL FIELD
1000 11
The present invention relates to a skeletal component for automobile
constituting an automobile body (hereafter, also simply referred to as a skeletal
component), in particular relates to a skeletal component such as a front pillar lower
outer that is assumed to receive a collision load in a specified direction.
Furthermore, the present invention relates to a front pillar lower that includes a front
pillar lower outer as a skeletal component.
BACKGROUNDART
[0002]
In an automobile body, for example, a front pillar and a side sill are each a
complex of skeletal components. The front pillar is arranged on a front side of the
body, extending in a vertical direction. The side sill is arranged in a lower part of
the body, extending in a front-back direction. A lower end portion of the front
pillar and a fore end portion of the side sill are coupled to each other. Here, for a
front pillar, a structure divided into upper and lower parts may be employed. In this
case, a skeletal component complex as the upper part of the structure is called a front
pillar upper, and a skeletal component complex as the lower part is called a front
pillar lower. A lower end portion of the front pillar upper and an upper end portion
of the front pillar lower are coupled to each other.
[0003]
The front pillar lower includes, for example, a front pillar lower outer
(hereafter, also simply referred to as an outer), a front pillar lower inner (hereafter,
also simply referred to as an inner), and a front pillar lower reinforcement (hereafter,
also simply referred to as a reinforcement), as skeletal components. The outer is
arranged on an outer side in a car-width direction. The inner is arranged on an inner
side in the car-width direction. The outer and the inner are coupled to each other,
forming a closed section all over the front pillar lower in a longitudinal direction.
The reinforcement is arranged between the outer and the inner to improve the
strength of the front pillar lower. Among them, the outer is bent into an L shape
along its longitudinal direction, and has a hat-shaped cross section all over the outer
in its longitudinal direction.
[0004]
FIG. 1A and FIG. 1B are schematic diagrams illustrating an example of a
front pillar lower outer as a skeletal component. In these drawings, FIG. 1A is a
plan view, and FIG. 1B is a cross sectional view taken along a line A-A of FIG. 1A.
For ease of understanding the shape of the front pillar lower outer, in FIG. 1 A, a side
on which the front pillar lower outer is coupled to a side sill is denoted by reference
character S, and a side on which the front pillar lower outer is coupled to a front
pillar upper is denoted by reference character U. In addition, in FIG. 1 A, a forward
side in a traveling direction of an automobile is denoted by reference character F, and
a rearward side in the traveling direction is denoted by reference character B. In
FIG. 1 B, an inward side in a car-width direction is denoted by reference character I,
and an outward side in the car-width direction is denoted by reference character 0.
[0005]
As illustrated in FIG. 1 A, a front pillar lower outer 10 includes a bent portion
13 that is bent into an L shape along the longitudinal direction (see a zone enclosed
by a chain double-dashed line in FIG. lA), and a first region 14 and a second region
15 that are connected to each of the opposite ends of the bent portion 13. The first
region 14 extends in a straight manner from the bent portion 13 toward the rearward
side B in the traveling direction of the automobile, and is coupled to the side sill.
The second region 15 extends in a straight manner upward from the bent portion 13,
and is coupled to the front pillar upper.
[0006]
In addition, as illustrated in FIG. 1 B, the cross-sectional shape of the outer 10
is in a hat shape all over the outer 10 in its longitudinal direction, namely, all over the
outer 10 from the side U on which the outer 10 is coupled to the front pillar upper to
the side S on which the outer 10 is coupled to the side sill. For this reason, the bent
portion 1 3, the first region 14, and the second region 15 constituting the outer 10
each include a top panel portion 1 Oa, a first vertical wall portion 1 Ob, a second
vertical wall portion 1 Oc, a first flange part 1 Od, and a second flange part 1 Oe. The
first vertical wall portion lob is connected to the entirety of a side portion that is the
inside of the bending of either side portions of the top panel portion 1 Oa. The
second vertical wall portion 10c is connected to the entirety of a side portion that is
the outside of the bending of either side portions of the top panel portion 1Oa. The
first flange part 10d is connected to the first vertical wall portion lob. The second
flange part 10e is connected to the second vertical wall portion 1 Oc.
[0007]
The front pillar lower is a skeletal component complex assumed to receive a
collision load from the forward side of the body. For this reason, the front pillar
lower outer 10 is a skeletal component assumed to receive a collision load along an
extending direction of the first region 14 coupled to the side sill.
[0008]
Japanese Patent Application Publication No. 201 1-37291 (Patent Literature I),
Japanese Patent No. 5 103959 (Patent Literature 2), and Japanese Patent Application
Publication No. 20 13-1 4 1928 (Patent Literature 3) disclose prior arts relating to the
front pillar. In a front pillar of Patent Literature 1, on an inner side in a car-width
direction of a pillar outer portion (equivalent to the outer) constituting a lower part in
a vertical direction, a pillar reinforcing member (equivalent to the reinforcement) is
attached. The pillar reinforcing member is provided in its fore portion with a highstrength
portion having a strength higher than those of the other portions. Patent
Literature 1 describes that this makes it possible to secure a strength required against
a collision load from a forward side of a body while reducing the weight of the front
pillar.
[0009]
Front pillars of Patent Literature 2 and Patent Literature 3 have closed section
structures. In the front pillar of Patent Literature 2, a reinforcement is constituted
by an upper portion, a center portion attached on a lower side of the upper portion,
and a lower portion attached on a lower side of the center portion. The attachment
between the upper portion and the center portion is accomplished with end portions
of both the portions overlapped. This is also the case with the attachment between
the center portion and the lower portion. The bonding strength of the attachment
between the center portion and the lower portion is set to be lower on a fore side than
on a rear side. Patent Literature 2 describes that this makes it possible to improve
the productivity of reinforcements even in the case where the reinforcements are
produced from a high-tensile steel plate.
[OO 1 01
In the front pillar of Patent Literature 3, guiding means is provided by making
use of a reinforcement. The guiding means has an inclined surface at a position
facing a front wheel of an automobile. At the time of small offset collision, the
inclined surface guides the front wheel toward the rear outer side of a body. Patent
Literature 3 describes that this makes it possible to suppress deformation of the front
pillar effectively while securing the stiffness of the front pillar at the time of small
offset collision.
CITATION LIST
PATENT LITERATURE
1001 11
Patent Literature 1 : Japanese Patent Application Publication No. 201 1-37291
Patent Literature 2: Japanese Patent No. 5 103959
Patent Literature 3: Japanese Patent Application Publication No. 201 3- 14 1928
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[OO 1 21
As mentioned previously, a front pillar is a skeletal component complex for
an automobile body, and a front pillar lower constituting a lower part of the front
pillar includes an outer as a skeletal component. The front pillar lower also
includes a reinforcement and an inner. For such a front pillar lower, there is a
demand for weight reduction from the viewpoint of fuel efficiency, as well as a
demand for an improved collision-resistance property from the viewpoint of safety.
[0013]
In the front pillar of Patent Literature 1 described above, in order to secure the
strength while reducing the weight, the high-strength portion is provided in the fore
portion of the pillar reinforcing member. Here, when the front pillar receives a load
at the time of frontal collision, part of the load is transmitted to a side sill. Since the
front pillar of Patent Literature 1 includes the high-strength portion in the fore
portion of the front pillar, the front pillar has tolerance for collision loads. This
causes only the side sill to deform significantly without causing deformation of the
front pillar deform. In this case, less energy can be absorbed by the front pillar,
resulting in a decrease in collision-resistance property of the front pillar.
[00 1 41
In the front pillar of Patent Literature 2 described above, a reinforcement is
constituted by divided portions: an upper portion, a center portion, and a lower
portion, which are attached with end portions of them overlapped. In the case of
this front pillar, production costs increases in producing the reinforcement as the
number of attachment spots and members increase. In addition, the attachment with
overlapping hinders the reduction of weight.
[OO 1 51
In the front pillar Patent of Literature 3 described above, the guiding means is
provided by making use of the reinforcement, and at the time of small offset collision,
the guiding means guides a front wheel of an automobile toward the rear outer side
of the body. However, such an effect is exerted only when the front wheel turns to
a traveling direction at the time of the collision, and the width of the front wheel is
not excessively larger than the width of the front pillar in a car-width direction. In
short, if the front wheel turns obliquely at the time of the collision, or if the width of
the front wheel is large, it is difficult to expect such an effect, and the front pillar
receives a load. For this reason, it is necessary to suppress the entry of a front
wheel by improving the collision-resistance property of a front pillar lower even in
the case where guiding means is provided in a reinforcement.
[0016]
Patent Literatures 1 to 3 described above mention the improvement of the
collision-resistance property and the reduction of the weight of a front pillar by
modifications of the shape, plate thickness, configuration, and the like of a
reinforcement. However, as to the front pillars of Patent Literatures 1 to 3
described above, no attention is paid to the shape, plate thickness, configuration, and
the like of a front pillar lower outer, which is a skeletal component. There are
demands for further improved collision-resistance properties and further reduced
weights of front pillar lowers.
[00 1 71
The present invention is made in such circumstances. The objective of the
present invention is to provide a skeletal component for automobile and a front pillar
lower that includes a front pillar lower outer as the skeletal component, the skeletal
component having the following property:
Reducing the weight while improving the collision-resistance property.
SOLUTION TO PROBLEM
[OO 1 81
A skeletal component for automobile according to an embodiment of the
present invention is bent into an L shape along its longitudinal direction, and has a
hat-shaped cross section all over the skeletal component in its longitudinal direction,
and
the skeletal component includes a bent portion that includes an arc-shaped
portion on the inside of the bending and an arc-shaped portion on the outside of the
bending, and a first region and a second region that extend from each of the opposite
ends of the bent portion, the skeletal component being assumed to receive a collision
load in the extending direction of the first region.
The skeletal component is constituted by attaching a first member that is
arranged on the first region side and a second member that is arranged on the second
region side.
An attachment line of the first member and the second member is arranged in
a predetermined zone between a first boundary on the first region side and a second
boundary on the second region side.
The first boundary is a straight line that connects an end, on the first region
side, of the arc-shaped portion on the inside of the bending, and an end, on the first
region side, of the arc-shaped portion on the outside of the bending.
The second boundary is a straight line that runs from an end, on the second
region side, of the arc-shaped portion on the inside of the bending along the
extending direction of the first region.
The plate thickness of the first member is larger than the plate thickness of the
second member.
[00 191
In the skeletal component for automobile described above, it is preferable that
the second boundary is a straight line that connects an end, on the second region side,
of the arc-shaped portion on the inside of the bending, and an end, on the second
region side, of the arc-shaped portion on the outside of the bending.
[0020]
In the skeletal component for automobile described above, it is preferable that
a ratio tllt2 between a plate thickness tl of the first member and a plate thickness t2
of the second member is 1.2 or more.
[002 11
In the skeletal component for automobile described above, it is preferable that
the skeletal component is a front pillar lower outer, the first region is coupled to a
side sill, and the second region is coupled to a front pillar upper. A front pillar
lower according to an embodiment of the present invention includes the front pillar
lower outer.
ADVANTAGEOUS EFFECTS OF INVENTION
[0022]
The skeletal component for automobile according to the present invention and
a front pillar lower that includes a front pillar lower outer as the skeletal component
have the following remarkable advantageous effect:
Reducing the weight while improving the collision-resistance property.
BRIEF DESCRIPTION OF DRAWINGS
[0023]
[FIG. 1 A] FIG. IA is a plan view schematically illustrating an example of a front
pillar lower outer, as a skeletal component.
[FIG. lB] FIG. 1B is a cross sectional view taken along a line A-A of FIG. 1A.
[FIG. 21 FIG. 2 is a plan view schematically illustrating an example of a front pillar
lower outer, as a skeletal component according to the present embodiment.
[FIG. 31 FIG. 3 is a plan view illustrating a more preferable range for a
predetermined zone where an attachment line is arranged.
[FIG. 41 FIG. 4 is a plan view schematically illustrating the outline of a collision test.
[FIG. 5A] FIG. 5A is a plan view illustrating a front pillar lower outer of
Comparative Example 1 used in the collision test.
[FIG. 5B] FIG. 5B is a plan view illustrating a front pillar lower outer of
Comparative Example 2 used in the collision test.
[FIG. 5C] FIG. 5C is a plan view illustrating a front pillar lower outer of Inventive
Example of the present invention 1 used in the collision test.
[FIG. 5D] FIG. 5D is a plan view illustrating a front pillar lower outer of Inventive
Example of the present invention 2 used in the collision test.
[FIG. 5E] FIG. 5E is a plan view illustrating a front pillar lower outer of Inventive
Example of the present invention 3 used in the collision test.
[FIG. 5F] FIG. 5F is a plan view illustrating a front pillar lower outer of Inventive
Example of the present invention 4 used in the collision test.
[FIG. 6A] FIG. 6A is a drawing illustrating the results of the test, illustrating
absorbed energies in the collision test.
[FIG. 6B] FIG. 6B is a drawing illustrating the results of the test, illustrating the
volumes of the outers.
[FIG. 6C] FIG. 6C is a drawing illustrating the results of the test, illustrating
absorbed energies per unit volume.
[FIG. 7A] FIG. 7A is a schematic diagram illustrating the shape of a blank as
Comparative Example 3 used in press forming, the shapes of metal plates before trim
processing used for the fabrication of the blank.
[FIG. 7B] FIG. 7B is a schematic diagram illustrating the shape of a blank as
Comparative Example 4 used in press forming, the shapes of metal plates before trim
processing used for the fabrication of the blank.
[FIG. 7C] FIG. 7C is a schematic diagram illustrating the shape of a blank as
Inventive Example of the present invention 5 used in press forming, the shapes of
metal plates before trim processing used for the fabrication of the blank.
[FIG. 7D] FIG. 7D is a schematic diagram illustrating the shape of a blank as
Comparative Example 5 used in press forming, the shapes of metal plates before trim
processing used for the fabrication of the blank.
[FIG. 81 FIG. 8 is a diagram illustrating the areas of blanks removed in the trim
processing for Inventive Example of the present invention 5, and Comparative
Examples 3 to 5.
DESCRIPTION OF EMBODIMENTS
[0024]
To achieve the above objective, the present inventors conducted intensive
studies through a variety of tests. As a result, the following findings were obtained.
[0025]
For example, in the case of a front pillar lower outer, increasing the plate
thickness thereof enables the suppression of entry of a front wheel at the time of
frontal collision, and thus it is possible to improve the collision-resistance property of
a front pillar lower. However, only simply increasing the plate thickness results in
an increase in mass of the front pillar lower outer accordingly, hindering the
reduction of weight. Considering the above, the compatibility between the
collision-resistance property and the weight reduction is needed.
LO0261
The front pillar lower outer is bent into an L shape along its longitudinal
direction. The cross-sectional shape of the front pillar lower outer is in a hat shape
all over the front pillar lower outer in the longitudinal direction. In the case of such
an outer, in order to withstand a collision load imposed by a front wheel at the time
of frontal collision, the axial crushing performance of a first region may need to be
increased along mainly the front-back direction of a body, namely a direction in
which a side sill extends. For this reason, an effective configuration of the outer has
the plate thickness which is larger on a first region side that is coupled to the side sill
than on a second region side that is coupled to a front pillar upper.
[0027]
Here, a configuration is effective in which a first member is arranged on the
first region side, a second member having a plate thickness than that of the second
member is arranged on the second region side, and these first member and second
member. Then, an attachment line between the first member and the second
member may be arranged in a predetermined zone of a bent portion connecting the
first region and the second region. This enables the compatibility between the
collision-resistance property and the weight reduction.
[0028]
Hereafter, an embodiment of the present invention will be described with
reference to the drawings. Here, as a skeletal component for automobile, a front
pillar lower outer that constitutes a front pillar lower will be described by way of
example.
[0029]
FIG. 2 is a plan view schematically illustrating an example of a front pillar
lower outer, as a skeletal component according to the present embodiment. A front
pillar lower outer 10 according to the present embodiment illustrated in FIG. 2 has,
as with the front pillar lower outer illustrated in FIG. 1, a hat-shaped cross section all
over the front pillar lower outer 10 in its longitudinal direction (see FIG. 1B
described above).
[0030]
As illustrated in FIG. 2, the front pillar lower outer 10 is bent into an L shape
along its longitudinal direction. The outer 10 includes a bent portion 13 that is bent
into the L shape along its longitudinal direction (see a zone enclosed by a chain
double-dashed line in FIG. 2), and a first region 14 and a second region 15 that are
connected to each of the opposite ends of the bent portion 13. The first region 14
extends in a straight manner from the bent portion 13 toward the rearward side in the
traveling direction of an automobile, and is coupled to the side sill. The second
region 15 extends in a straight manner upward from the bent portion 13, and is
coupled to a front pillar upper. The outer 1 O is a skeletal component assumed to
receive a collision load along an extending direction of the first region 14 coupled to
the side sill.
[003 1 ]
The outer 10 is constituted by attaching the first member 1 1 and the second
member 12. The attachment of the first member 1 1 and the second member 12 can
be performed by, for example, butt welding. The first member 11 is arranged on a
first region 14 side, namely on a side sill side. The second member 12 is arranged
on a second region 15 side, namely on a front pillar upper side. The reason for
constituting the outer 10 in this way with the first member 11 and the second member
12 is to make the plate thickness of the front pillar lower outer 10 differ between the
side sill side and the front pillar upper side.
[0032]
In the outer 10 according to the present embodiment, the plate thickness of the
first member 1 1 on the side sill side (first region 14 side) is larger than the plate
thickness of the second member 12 on the front pillar upper side (second region 15
side). Since the plate thickness on the first region 14 side coupled to the side sill is
made larger, the axial crushing performance of the first region 14 is increased. This
can improve the collision-resistance property of the outer 10 with high efficiency.
Meanwhile, since the plate thickness on the second region 15 side coupled to the
front pillar upper is smaller, it is possible to achieve the weight reduction. This
does not interfere with the collision-resistance property because the plate thickness
on the second region 15 side contributes less to the axial crushing performance of the
first region 14.
[0033]
In order to exert the above effects, an attachment line L between the first
member 1 1 and the second member 12 is arranged in a predetermined zone that is
specified in the bent portion 13. This predetermined zone is a zone between a first
boundary 16 on the first region 14 side and a second boundary 17 on the second
region 15 side. The specific mode thereof will be described below.
[0034]
The bent portion 13 includes an arc-shaped portion 1 Of on the inside of the
bending (see a bold line portion in FIG. 2) and an arc-shaped portion log on the
outside of the bending (see a bold line portion in FIG. 2). The arc-shaped portion
1 Of on the inside of the bending refers to an arc-shaped edge portion on the inside of
the bending of the first flange part 1 Od. The arc-shaped portion log on the outside
of the bending refers to an arc-shaped edge portion on the outside of the bending of
the second flange part 10d.
[0035]
A first boundary 16 is a straight line that connects an end IOfl, on the first
region 14 side, of the arc-shaped portion 1 Of on the inside of the bending, and an end
1 Ogl, on the first region 14 side, of the arc-shaped portion 1 Og on the outside of the
bending (see a bold dotted line in FIG. 2). A second boundary 17 is a straight line
that runs from an end 10f2, on the second region 15 side, of the arc-shaped portion
1 Of on the inside of the bending along the extending direction of the first region 14
(see a bold line in FIG. 2). The attachment line L of the first member 11 and the
second member 12 is arranged in a predetermined zone between such a first
boundary 16 and second boundary 17 (see in the hatched zone in FIG. 2). By
arranging the attachment line L in the predetermined zone of the bent portion 13 in
this way, it is possible to achieve the weight reduction of the outer 10 while
maintaining the collision-resistance property.
[0036]
If the attachment line L is arranged to be closer to the side sill side (first
region 14 side) than the first boundary 16, a zone on the first region 14 side, which
has a large plate thickness, is narrowed. In this case, the axial crushing
performance of the first region 14 decreases, resulting in a decrease in collisionresistance
property of the outer 10. On the other hand, if the attachment line L is
arranged to be closer to the front pillar upper side (second region 15 side) than the
second boundary 17, a zone having a large plate thickness is widened to the second
region 15 side, and thus a little improvement of the collision-resistance property is
expected. However, in this case, the axial crushing performance of the first region
14 hardly changes because there is no change in the plate thickness of the first region
14. This rather hinders the weight reduction significantly due to widening the zone
having a large plate thickness.
[0037]
FIG. 3 is a plan view illustrating a more preferable range for the
predetermined zone where the attachment line is arranged. As illustrated in FIG. 3,
it is preferable that a second boundary 17' is a straight line that connects an end 10f2,
on the second region 15 side, of the arc-shaped portion 1 Of on the inside of the
bending, and an end 10g2, on the second region 15 side, of the arc-shaped portion
1 Og on the outside of the bending (see a bold dotted line in FIG. 3). The attachment
line L of the first member 1 1 and the second member 12 is arranged in a
predetermined zone between such a first boundary 16 and second boundary 17' (see
in the hatched zone in FIG. 3). This enables the securement of the collisionresistance
property of the outer 10 while achieving further weight reduction.
lo0381
In the outer 10 according to the present embodiment, the plate thickness on
the first region 14 side coupled to the side sill is made larger, which makes the axial
crushing performance increased, enabling the improvement of the collisionresistance
property with high efficiency. Moreover, since the plate thickness on the
second region 15 side coupled to the front pillar upper is smaller, it is possible to
achieve the weight reduction. Therefore, the compatibility between the collisionresistance
property and the weight reduction is enabled.
[0039]
In addition, the outer 10 according to the present embodiment, the attachment
line L between the first member 11 and the second member 12 is arranged in the
predetermined zone that is specified in the bent portion 13. This can improve stock
utilization for the outer 10 as compared with the case where the attachment line L is
arranged in a straight-shaped portion of the first region 14 (side sill side) or the
second region 15 (front pillar upper side).
[0040]
In the outer 10 according to the present embodiment, the plate thickness on
the first region 14 side coupled to the side sill is made larger, which makes the axial
crushing performance increased. For this reason, there is no case where only the
side sill significantly deforms at the time of frontal collision as with the front pillar of
Patent Literature 1 described above, and it is possible to cause the front pillar lower
and the side sill to deform in a good balance to absorb a collision load. In addition,
the improvement of the collision-resistance property is not limited at the time of
small offset collision as in the case of Patent Literature 3 described above, and it is
possible to improve the collision-resistance property even when a front wheel turns
obliquely at the time of collision or when the front wheel has a large width.
[004 1 ]
Preferably, a ratio tllt2 between a plate thickness tl (mm) of the first member
and a plate thickness t2 (mm) of the second member is 1.2 or more. This enables
further improvement of the collision-resistance property, enabling the achievement
of the weight reduction. The upper limit of the plate thickness ratio tllt2 is not
specified. However, when the plate thickness ratio tllt2 exceeds 2.0, the
attachment by butt welding or the like becomes difficult. For this reason, the plate
thickness ratio is preferably set to 2.0 or less.
[0042]
The front pillar lower outer according to the present embodiment is a press
formed product. The components thereof, the first member and the second member,
may be attached before press forming or after press forming. In a method for
producing the outer by the former scheme, a so-called tailored blank is used. In this
case, the tailored blank is obtained by subjecting a first blank (metal plate) and a
second blank (metal plate) that have plate thicknesses different from each other, to
butt welding. Press forming is performed on this tailored blank, whereby a formed
product of the outer can be obtained. As necessary, the formed product is finished
by trimming, restriking, and the like.
[0043]
In contrast, in a method for producing the outer by the latter scheme, press
forming is performed on a first blank (metal plate) to obtain a first member formed
into a desired shape. Separately, press forming is performed on a second blank
(metal plate) to obtain a second member formed into a desired shape. The first
member and the second member are attached by butt welding, whereby the outer can
be obtained. In this case, trimming, restriking, and the like are performed, as
necessary, on the first member and the second member before the attachment, or on
the complex after the attachment.
LO0441
The front pillar lower according to the present embodiment includes the outer
according to the present embodiment described above. This front pillar lower is a
closed section structure and includes also a reinforcement and an inner. For this
reason, the collision-resistance property is improved by the reinforcement as well as
the outer, and the achievement of the weight reduction also becomes possible.
Furthermore, since the stock utilization for the outer is improved, it is possible to
reduce production costs of front pillar lowers.
[0045]
The present invention is not limited to the embodiments described above, and
various modifications may be made without departing from the spirit and scope of
the present invention. For example, the skeletal component is not limited to a front
pillar lower outer, and may be a rear-side outer or the like as long as it is a
component that is bent into an L shape along its longitudinal direction and assumed
to receive a collision load along the extending direction of the first region. In
addition, each of the first member and the second member constituting the skeletal
component does not necessary have a constant thickness.
EXAMPLES
[0046]
[Collision Test]
For the front pillar lower outer according to the present embodiment, a test for
confirming a collision-resistance property at the time of frontal collision was
conducted by the FEM analysis.
[0047]
FIG. 4 is a plan view schematically illustrating the outline of the collision test.
FIG. 4 illustrates a front pillar lower outer 10, and an impactor 51. In the collision
test by the FEM analysis, a free end portion of the first region 14 of the outer 10,
namely the free end portion on the side sill side was fixed to restrain the
displacement of the free end portion. In this state, the impactor 5 1 was caused to
flmove
at a speed of 15 kmlh in a horizontal direction and collided with the bent
portion 13 of the outer 10. Then, the impactor 5 1 was caused to stop at the time
when the amount of entry of the impactor 5 1 into the outer 10 reached 100 mm.
[0048]
At this point, an energy absorbed by the outer 10 with the entry of the
impactor 5 1 into the outer 10 was determined. This energy absorbed by the outer
10 was divided by the volume of the outer 10, whereby an absorbed energy per unit
volume was calculated.
[0049]
FIG. 5A to FIG. 5F are plan views illustrating front pillar lower outers used in
the collision test. In these drawings, FIG. 5A and FIG. 5B illustrate Comparative
Examples 1 and 2, respectively. FIG. 5C, FIG. 5D, FIG. 5E, and FIG. 5F illustrates
Inventive Examples of the present invention 1, 2, 3, and 4, respectively.
[0050]
In Comparative Examples 1 and 2, and Inventive Examples of the present
invention 1 to 4, the attachment line L was arranged at the following positions.
- Comparative Example 1 (see FIG. 5A): in a straight-shaped portion of the
first region 14 (on the side sill side)
- Comparative Example 2 (see FIG. 5B): in a straight-shaped portion of the
second region 15 (on the front pillar upper side)
- Inventive Example of the present invention 1 (see FIG. 5C): on a straight
line that connects a center 10fc of the arc-shaped portion 1 Of on the inside of the
bending, and a center 1 Ogc of the arc-shaped portion log on the outside of the
bending
- Inventive Example of the present invention 2 (see FIG. 5D): on a straight
line that runs from an end 10f2, on the second region 15 side, of the arc-shaped
portion 1 Of on the inside of the bending along the extending direction of the first
region 14
- Inventive Example of the present invention 3 (see FIG. 5E): on a straight
line that connects the end 10f2, on the second region 15 side, of the arc-shaped
portion 1 Of on the inside of the bending, and an end 10g2, on the second region 15
side, of the arc-shaped portion log on the outside of the bending
- Inventive Example of the present invention 4 (see FIG. 5F): on a straight
line that connects an end 1 Ofl, on the first region 14 side, of the arc-shaped portion
1 Of on the inside of the bending, and an end 1 Ogl, on the first region 14 side, of the
arc-shaped portion log on the outside of the bending
LO05 11
In each of Inventive Examples of the present invention 1 to 4, and
Comparative Examples 1 and 2, the first member 11 on the first region 14 side (side
sill side) was formed of a metal plate A, and the second member 12 on the second
region 15 side (front pillar upper side) was formed of a metal plate B. The metal
plate A was a high-tensile steel plate equivalent to JAC780Y of The Japan Iron and
Steel Federation Standard (JFS Standard), and the plate thickness tl thereof was 1.5
mm. The metal plate B was a high-tensile steel plate equivalent to JAC98OY of
The Japan Iron and Steel Federation Standard (JFS Standard), and the plate thickness
t2 thereof was 1.2 mm. The plate thickness ratio tllt2 was 1.25.
[0052]
FIG. 6A to FIG. 6C are drawings illustrating the results of the test. In these
drawings, FIG. 6A illustrates absorbed energies in the collision test. FIG. 6B
illustrates volumes of the outers. FIG. 6C illustrates absorbed energies per unit
volume. From the results of FIG. 6A to FIG. 6C, the following facts are shown.
[0053]
As illustrated in FIG. 6A, in Comparative Example 1, since the attachment
line was arranged in the straight-shaped portion on the side sill side, the absorbed
energy was poor. In contrast, in Inventive Examples of the present invention 1 to 4,
since the attachment lines were arranged in the predetermined zone specified in the
present embodiment, the absorbed energy was good. In addition, in Comparative
Example 2, since the attachment line was arranged in the straight-shaped portion on
the front pillar upper side, the absorbed energy was good.
[0054]
Here, the absorbed energy in the collision test varies according to the plate
thickness, and the absorbed energy tends to increase as a zone having a large plate
thickness is widened. For this reason, the absorbed energy of Comparative
Example 2 was slightly better than the absorbed energies of Inventive Examples of
the present invention 1 to 4.
[0055]
As illustrated in FIG. 6B, the outer of Comparative Example 2 had a
significantly large volume. For this reason, as illustrated in FIG. 6C, as to the
absorbed energy per unit volume, Inventive Examples of the present invention 1 to 4
were better than Comparative Example 2. In short, from the results illustrated in
FIG. 6B, the outers of Inventive Examples of the present invention 1 to 4 had
weights significantly lighter than that of Comparative Example 2. Therefore, it was
clarified that the outer according to the present embodiment is good from the
viewpoint of compatibility between the weight reduction and the collision-resistance
property in a good balance.
[0056]
[Stock Utilization]
In the case where the front pillar lower outer according to the present
embodiment was formed from a tailored blank, the stock utilization for the blank was
investigated.
[0057]
FIG. 7A to FIG. 7D are schematic diagrams illustrating the shapes of blanks
used in press forming, the shapes of metal plates before trim processing used for the
fabrication of the blanks. In these drawings, FIG. 7A, FIG. 7B, and FIG. 7D
illustrate Comparative Examples 3,4, and 5, respectively. FIG. 7C illustrates
Inventive Example of the present invention 5. In each of FIG. 7A to FIG. 7D, the
shape of a blank 61 used in press forming is illustrated by chain double-dashed lines,
the shapes of a first metal plate 62 and a second metal plate 63 before the trim
processing used in the fabrication of the blank 61 is illustrated by solid lines, and the
attachment line L is illustrated by a bold line. Both of the first metal plate 62 and
the second metal plate 63 before the trim processing were formed into a rectangular
shape. A zone 62a in the first metal plate 62 to be removed in the trim processing
and a zone 63a in the second metal plate 63 to be removed in the trim processing are
hatched.
[0058]
As illustrated in FIG. 7A, in Comparative Example 3, a single metal plate (the
first metal plate 62) was used as a blank for press forming, rather than a tailored
blank. As illustrated in FIG. 7B, in Comparative Example 4, the attachment line L
was arranged in the straight-shaped portion on the side sill side. As illustrated in
FIG. 7D, in Comparative Example 5, the attachment line L was arranged in the
straight-shaped portion on the front pillar upper side. In contrast, as illustrated in
FIG. 7C, in Inventive Example of the present invention 5, attachment line L was
arranged in the predetermined zone specified in the present embodiment.
[0059]
FIG. 8 is a diagram illustrating the areas of blanks removed in the trim
processing for Inventive Example of the present invention 5, and Comparative
Examples 3 to 5. As illustrated in FIG. 8, Inventive Example of the present
invention 5 had the least removal area of blank. Therefore, it was clarified that,
with the outer according to the present embodiment, it is possible to improve the
stock utilization of a blank.
INDUSTRIAL APPLICABILITY
[0060]
The present invention is effectively applicable to a skeletal component for
automobile, and a front pillar lower including a front pillar lower outer as the skeletal
component.
REFERENCE SIGNS LIST
[0061]
10: front pillar lower outer (skeletal component),
10a: top panel portion,
lob: first vertical wall portion,
10c: second vertical wall portion,
10d: first flange part, 10e: second flange part,
1 Of: arc-shaped portion on inside of bending,
1 Of1 : end on first region of arc-shaped portion on inside of bending,
1 Of2: end on second region of arc-shaped portion on inside of bending,
1 Ofc: center of arc-shaped portion on inside of bending,
log: arc-shaped portion on outside of bending,
1 Ogl : end on first region of arc-shaped portion on outside of bending,
10g2: end on second region of arc-shaped portion on outside of bending,
1 Ogc: center of arc-shaped portion on outside of bending,
1 1 : first member,
12: second member,
1 3: bent portion,
14: first region,
15: second region,
16: first boundary,
17, 17': second boundary,
5 1 : impactor,
6 1 : blank,
62: first metal plate,
62a: zone in first metal plate to be removed by trim,
63: second metal plate,
63a: zone in second metal plate to be removed by trim,
L: attachment line
We claim:
1. A skeletal component for automobile that is bent into an L shape along its
longitudinal direction, and has a hat-shaped cross section all over skeletal component
in its longitudinal direction, wherein
the skeletal component comprises a bent portion that includes an arc-shaped
portion on an inside of bending and an arc-shaped portion on an outside of the
bending, and a first region and a second region that extend from each of opposite
ends of the bent portion, the skeletal component being assumed to receive a collision
load in an extending direction of the first region,
the skeletal component is constituted by attaching a first member that is
arranged on the first region side and a second member that is arranged on the second
region side,
an attachment line of the first member and the second member is arranged in a
predetermined zone between a first boundary on the first region side and a second
boundary on the second region side,
the first boundary is a straight line that connects an end, on the first region
side, of the arc-shaped portion on the inside of the bending, and an end, on the first
region side, of the arc-shaped portion on the outside of the bending,
the second boundary is a straight line that runs from an end, on the second
region side, of the arc-shaped portion on the inside of the bending along the
extending direction of the first region, and
a plate thickness of the first member is larger than a plate thickness of the
second member.
2. The skeletal component for automobile according to claim 1, wherein
the second boundary is a straight line that connects an end, on the second
region side, of the arc-shaped portion on the inside of the bending, and an end, on the
second region side, of the arc-shaped portion on the outside of the bending.
3. The skeletal component for automobile according to claim 1 or 2, wherein
a ratio tlIt2 between a plate thickness tl of the first member and a plate
thickness t2 of the second member is 1.2 or more.
4. The skeletal component for automobile according to any one of claims 1 to 3,
wherein
the skeletal component is a front pillar lower outer, and
the first region is coupled to a side sill, and the second region is coupled to a
front pillar upper.
5. A front pillar lower comprising the skeletal component for automobile
according to claim 4.