Truck bed and method of manufacture

Land vehicles: bodies and tops – Bodies – Body shell

Reexamination Certificate

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Details

C052S797100, C296S182100

Reexamination Certificate

active

06170905

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the construction of a truck bed, such as a pickup truck bed, and in particular relates to an improved construction of the bed floor and rear cross rail, and an improved constructional method.
BACKGROUND OF THE INVENTION
A box of a truck, 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 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 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 topwall 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 groove-like 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.
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 main floor pan
17
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, even though extensively utilized for many years, and which in fact is still in use, 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, and particularly with respect to the main floor pan
17
, 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 main floor pan
17
, 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 of the pan by the stamping or pressing process, the pan must also be initially formed from a sheet material of greater thickness than desired so as to compensate for the expected thickness reductions which occur during the stamping operation. This increases the overall weight of the pan. Further, in view of the significant size of the main floor pan and the fact that it is deformed or stamped in basically a single pressing operation, this also necessitates utilization of an extremely large and high-capacity forming press in order to accommodate both the size of the sheet and the significant pressing force encountered during the simultaneous deformation of the numerous ribs which extend longitudinally thereof. Further, these stamping operations necessarily can normally be successfully carried out only if lower strength and softer sheet steels are utilized since harder and higher strength steels will typically split or crack if subjected to severe deformation of the type encountered in the conventional pan stamping operation.
To improve on the above described truck bed structure and the forming method thereof, the assignee of this application developed the improved truck bed structures and forming methods as disclosed in U.S. Pat. No. 5,188,418, U.S. Pat. No. 5,544,932, and PCT published application WO 93/19972. All are assigned to Pullman Industries, the assignee hereof, and are herein incorporated by reference.
In said U.S. Pat. No. 5,188,418, a truck bed is disclosed including a floor pan having strengthening ribs constructed by a roll forming process. A rear sill member cooperates with the rear edge

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