Vehicle bed edge manufacturing process

Details Vehicle bed edge manufacturing process Vehicle bed edge manufacturing process

2000-07-06

2002-02-19

Hughes, S. Thomas (Department: 3726)

Metal working

Method of mechanical manufacture

Structural member making

C072S379600, C029S417000

Reexamination Certificate

active

06347454

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an improved one-piece ribbed floor pan for a vehicle bed, such as a truck bed, and the related process of manufacture.
BACKGROUND OF THE INVENTION
A box of a vehicle, such as a pickup truck, is illustrated in FIG.
1
. This box conventionally includes a horizontally enlarged floor or bed assembly
12
which extends sidewardly between and is joined to generally parallel and upwardly extending side panels or walls
13
. The side panels
13
conventionally have wheelwell housings
14
formed therein, the latter typically projecting at least inwardly a small extent into the interior of the box. The front end of the floor assembly
12
is also rigidly joined to an upwardly-projecting front wall or panel
15
, the latter extending between and being rigidly fixed to the side panels
13
. The rear of the box is normally closed by a rear-panel
16
, the latter conventionally being an openable tailgate
16
which is conventionally hingedly joined to the box and can swing into an open generally horizontal position wherein it is substantially flush with the floor assembly to provide access to the interior of the box.
This box, and specifically the floor or bed assembly
12
, conventionally includes a horizontally enlarged main bed member
17
, commonly referred to as the floor pan, which defines the actual floor of the box and extends lengthwise between the front and rear ends of the box, and has a width which normally substantially spans the width of the opening between the wheelwell housings. This main floor pan
17
is supported on a front cross rail
18
, several intermediate cross rails
19
, and a rear cross rail or sill member
21
, the latter all extending transversely under the pan and being fixedly secured thereto, such as by spot welding. Some of these cross members, such as the front rail
18
, the frontmost intermediate rail
19
and the rear sill
21
are typically fixedly secured to the vehicle frame (not shown) in a conventional manner.
The bed assembly
12
also normally includes secondary bed or floor pan members
22
, the latter being positioned adjacent and fixedly joined to opposite longitudinal edges of the main floor pan
17
so as to occupy the regions of the bed disposed forwardly and rearwardly of the wheelwell housings
14
.
In the pickup box as conventionally constructed, the main floor pan
17
is provided with stiffening ribs
23
which project upwardly from the pan, with a plurality of such ribs being generally uniformly sidewardly spaced apart across the width of the pan and extending longitudinally of the pan over a majority of the length thereof. These ribs, which are deformed upwardly from the pan to define a downwardly-opening channel-like cross section, generally extend rearwardly from adjacent the front free edge of the main pan
17
but the ribs normally terminate in tapered rib ends
24
which merge downwardly into the planar profile of the pan
17
at a location disposed close to but spaced forwardly a small distance from the rear free edge
25
of the pan. The rear edge portion of the main pan
17
, namely the flat portion thereof which is free of the ribs, is then normally seated within a shallow recess formed in the top wall of the rear sill member
21
so as to be substantially flush with the upper surface of the sill member, with the rear pan and sill member then being suitably fixedly secured together, such as by spot welding. This arrangement enables the groovelike regions defined between adjacent ribs
23
to freely open outwardly through the rear end of the bed assembly, and hence prevent creation of pockets or recesses which would collect dirt or moisture. The secondary pan members
22
also conventionally have stiffening ribs
23
formed therein and extending longitudinally of the bed, with the stiffening ribs
23
in the secondary pan members
22
again typically terminating short of the front and rear edges of the respective pan member.
FIG. 2
illustrates therein another conventional prior art box of a vehicle, such as a pickup truck, wherein the parts thereof corresponding to
FIG. 1
have been identified by the same reference numerals but with the addition of a prime (′) thereto. The bed assembly
12
′ of
FIG. 2
again includes an enlarged main bed member or portion
17
′ which extends longitudinally throughout the length of the bed and defines the region which extends generally transversely between the wheelwell housings of the vehicle. The bed assembly
12
′ also again includes secondary bed members or portions
22
′ which occupy the regions of the bed disposed forwardly and rearwardly of the wheelwell housings
14
. In this prior art construction, however, the main bed portion
17
′ and the secondary portions
22
′ are all integrally formed in one piece and, as is generally conventional, are provided with downwardly depending flanges which project generally longitudinally along the side edges and also along the edge of the wheelwell openings for permitting securement to the adjacent side panels or wheelwell housings. The stiffening ribs associated with both the main and secondary portions
17
′ and
22
′, respectively, again are formed such that the ends thereof terminate in longitudinally spaced relation from the longitudinal end edges, particularly the rear edge of the bed.
A bed assembly having the structure described above has, for a very long time, been constructed using individual members which have been stamped utilizing large forming presses. That is, the floor pan
17
(
FIG. 1
) or
17
′,
22
′ (
FIG. 2
) as well as the cross rails
18
,
19
and
21
have been conventionally formed from flat steel sheets by positioning a precut steel sheet in a forming press which deforms the sheet to define the desired cross section of the finished member. This stamping or press-forming technique, however, even though extensively utilized for many years, possesses recognized disadvantages which have nevertheless been long tolerated in view of the belief that this was the best manner of constructing the bed assembly.
More specifically, the current and almost universally utilized technique of stamping the pan has resulted in limitations which have restricted optimum construction of the pan. For example, to stamp the floor pan
17
of
FIG. 1
, a large rectangular sheet must be precut in accordance with the size of the desired pan being stamped. The sheet is initially of excess width so as to provide portions along opposite edges of the sheet which can be used for clamping the sheet and holding it in position when the sheet is positioned within the press and subjected to the stamping operation. Further, during the actual stamping operation, the material of the sheet is physically deformed by the stamping die so as to permit creation of the longitudinal ribs. This necessarily results in significant changes in thickness of the sheet material due to the deformation which is caused during the rib formation process. Not only does the sheet undergo significant changes in thickness, but this change in thickness is also of varying amounts at different locations across the rib, or through the cross section of the sheet containing the ribs, so that the resulting stamped floor pan has a sheet thickness which has significant variation therein. This thickness variation can in some instances be as much as 40% to 50%. This stamping process has also been observed to result in bends or corners which are inconsistent in terms of both material thickness and included angle, and have provided a finished exterior appearance which permits such irregularities to be visually observed. This stamping operation also requires, after the pan has been stamped, that the pan be subjected to a further stamping or cutting operation which is effective for removing the clamping strip portions on opposite sides of the sheet, which strip portions are disposed of as scrap.
In view of the inherent but inconsistent thickness reductions which occur during forming o

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