Static structures (e.g. – buildings) – Machine or implement
Reexamination Certificate
2000-09-20
2003-07-15
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
Machine or implement
C052S749100, C052S749100, C052S749100, C052S749100, C052S749100
Reexamination Certificate
active
06591576
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a structural member having a closed section, and an apparatus and a method for producing the structural member. More particularly, the invention relates to a structural member formed of a plate-like work and having a channel-shaped sectional portion and two closed sectional portions for which both side walls of the channel-shaped sectional portion are commonly shared, and an apparatus and a method for producing a structural member having such a closed section.
2. Description of Related Art
A bumper reinforcement which constitutes an automobile bumper has been known as this type of the structural member. As has been disclosed in Japanese Patent Publication Laid-Open No. Hei 10-278706, the bumper reinforcement is attached and fixed by inserting the tip end portion of the side members of an automobile into the channel-shaped sectional portion, and this is bent or curved in compliance with the shape of a bumper which constitutes a part of the design of the automobile.
Referring to
FIG. 17
, the channel-shaped sectional portion
51
of a bumper reinforcement is defined by the bottom wall
60
formed substantially at the middle of a plate-shaped work W′ (FIG.
11
), and boundary walls (side walls)
61
each forming a boundary to a closed sectional portion
52
formed by bending the plate-shaped work from the respective ends of the bottom wall
60
. Also, the closed sectional portion
52
is defined by the boundary walls
61
, a longitudinal inner side wall
62
located at the automobile side when the plate-shaped work is bent from the respective ends of the boundary wall
61
and attached to and fixed at a side member, a vertical outer side wall
63
located outside the automobile in the vertical direction when the plate-shaped work is bent from the longitudinal inner side wall
62
and attached to and fixed at the side member, and a longitudinal outer side wall
65
located at the opposite side of the automobile when being bent from the vertical outer side wall
63
, causing the side edges of the work to overlap on the bottom wall
60
of the channel-shaped sectional portion
51
and being attached to and fixed at the side member. The respective sidewalls
60
,
61
,
62
,
63
, and
65
are formed to be planar, and the walls adjacent to each other are bent to be approximately perpendicular to each other Further, the names of these bottom wall
60
, boundary wall
61
, longitudinal inner side wall
62
, vertical outer side wall
63
, and longitudinal outer side wall
65
are used as only reference in order to describe a structural member having a closed section in the invention, but they do not intend to limit the patterns in use. It is noted that the longitudinal direction, vertical direction or the inside and outside positions may differ in compliance with actual applications.
When producing such a bumper reinforcement, generally, as shown in FIG.
11
through
FIG. 18
, plate-shaped work W′ is prepared (FIG.
11
), and the position which falls between the boundary wall
61
and the longitudinal inner side wall
62
of the work W′ is bent to form so as to secure the shape of work W
11
(FIG.
12
). Also, the position which falls between the bottom wall
60
of the work W
11
and the boundary wall
61
is bent to form it to secure the shape of the work W
12
in which the channel-shaped sectional portion
51
is formed (FIG.
13
), and the position which falls between the longitudinal inner side wall
62
and vertical outer side wall
63
of the work W
12
is bent into a form so as to secure the shape of work W
13
(FIG.
14
). Next, the position which falls between the vertical outer side wall
63
and the longitudinal outer side wall
65
is slightly bent into a form so as to secure the shape of work W
14
(FIG.
15
). Thereafter, the position which falls between the vertical outer side wall
63
and the longitudinal outer side wall
65
is completely bent so that the side edges of the work W
14
are caused to overlap on the bottom wall
60
of the channel-shaped sectional portion, thereby securing the shape of work W
15
(
FIG. 16
) Further, a process of forming the work W
11
through W
15
shaped as shown in FIG.
12
through
FIG. 16
from the plate-shaped work W′ is carried out by press-forming so that the respective bent portions form almost perpendicular ridge lines. The width of the plate-shaped work W′ is set so as to form adequate intervals so that end faces Wa, Wa at both side edges which are caused to overlap on the bottom wall
60
of the channel-shaped sectional portion
51
are not buckled by being brought into contact with each other. The work W
15
bent as shown in
FIG. 16
is finally curved or bent along its length in compliance with the design of an automobile bumper and is formed to the shape of work W
16
(see FIG.
18
). However, in order to evade various problems such as warping, undulating, or opening of the side edges of the work W
15
, which may occur in the lengthwise bending or curving process, after the work W
11
through W
15
is bent so as to become straight or linear in its lengthwise direction in the respective steps shown in FIG.
12
through
FIG. 16
, the side edges of the work W
15
are welded to the bottom wall of the channel-shaped sectional portion where the side edges of the work W
15
are caused to overlap each other (FIG.
17
). In the final process of a series of steps, the structural member is generally bent, along its length at a fixed curvature radius R
1
, by press-forming from a shape shown with the chain line in
FIG. 18
to a shape shown with a solid line therein, whereby the structural member is formed to the shape of work W
16
.
On the other hand, Japanese Patent Publication Laid-Open No. Sho 59-39422 discloses a method for producing a box-shaped structural member constructed so that a plate-shaped material which is shaped like a channel by a bottom wall and both side walls is set in a channel-shaped sectional portion of a die, both side walls are folded and bent while applying an axial force thereto by a rotating bending punch, the end faces of the free end portions are opposed to each other, and the tip end faces opposed to each other are welded to each other.
That is, in the invention described above, a production method has been researched and developed, in which both end faces of the free end portions are run into each other at the middle point in the width direction by folding a plate member, an upper die and a lower die are used to process as described above, wherein since a material folded to be like a channel in advance is folded and bent, the angle of the free end portions become inevitably large at the corner portion, and the free end portions may fall down inside. That is, the tip end faces of the free end portions are run into each other in the process of formation, wherein the free end portions may become horizontal before they are completely worked, or if the free end portions are pressed to the end, they are caused to fall down inside. That is, it is difficult to fold and bend the work to a desired shape, and no actual application has been brought about. This is described therein (from page 1, 5
th
line in the right lower column, of the Publication to Page 2, 3
rd
line in the right upper column thereof).
Therefore, the aforementioned invention has been made in view of the above situations, wherein, in the embodiment thereof, a stopper is provided on the folding and bending surface of a bending punch rotatably supported on the upper wall of a die via a pin, and as the bending punch is turned downward, the free end portions are pressed to the side wall of the channel-shaped sectional portion by the stopper (that is, an axial force is applied to the bending portion), and it is described that the free end portions are folded and bent to become horizontal in this state.
However, in those prior arts described above and shown in FIG.
11
through
FIG. 18
, in order to evade problems such a
Furuhata Takayuki
Iida Masataka
Ishihara Sadao
Matsukura Takanori
Takeuchi Masahiko
Friedman Carl D.
Horton Yvonne M.
Pillsbury & Winthrop LLP
Toyota Jidosha & Kabushiki Kaisha
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