Patent Application
20080053341
The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:
The pallet 10 of the invention, broadly considered, comprises an upper generally rectangular plastic sheet 12 and a lower generally rectangular plastic sheet 14. Sheets 12 and 14 are preferably formed of a polyethelene material and may have a thickness of approximately 0.070 inches. In overview, each is formed in a vacuum thermoforming operation and the upper and lower sheets, while still in a heated fusible condition, are brought together to selectively fused portions of the upper sheet to portions of the lower sheet to form the pallet.
Upper sheet 12 includes a main body portion 16, corner pillars 18, intermediate transverse pillars 20, intermediate longitudinal pillars 22, and a central pillar 34.
Main body portion 16 is generally planar and includes transverse peripheral ribs 36, longitudinal peripheral ribs 38, central transverse ribs 40 and central longitudinal ribs 42.
Main body portion 16 further includes rectangular areas 44 defined in the four quadrants of the sheet between the ribs and the pillars. Each area 44 includes a plurality of upwardly opening, downstanding bosses 46 arranged in staggered rows. Each boss 46 includes a top wall 46a and an annular sidewall 46b.
Each pillar is hollow, opens in the upper face of the main body portion of the upper sheet and has a generally truncated, pyramidal configuration.
Corner pillars 18 include an annular side wall 18a and a bottom wall 18b.
Intermediate transverse pillars 20 include an annular side wall 20a and a bottom wall 20b.
Intermediate longitudinal pillars 22 include an annular side wall 22a and a bottom wall 22b.
Central pillar 24 has a compound configuration and includes a downstanding outer annular wall 24a, an upstanding inner annular wall 24b joined at its lower annular end to the lower annular end of outer wall 24a and positioned concentrically within the outer wall, and a top wall 24c.
Lower sheet 14 includes a main body portion 48, raised portions 50, corner pillars 52, intermediate transverse pillars 54, intermediate longitudinal pillars 56, and a central pillar 58.
Main body portion 48 has a generally planar configuration and includes transverse peripheral ribs 60, longitudinal peripheral ribs 62, central transverse ribs 64 and central longitudinal ribs 66.
Raised portions 50 are arranged in quadrants corresponding generally to the quadrants of the areas 44 of the upper sheet and each includes a rectangular top wall 68 elevated above the level of the main body portion and a plurality of spaced upstanding legs 70 connecting the corners of the top wall to the main body portion. The legs 70 splay outwardly from the respective top wall so as to give each raised portion 50 a truncated pyramidal overall configuration. Each top wall 68 includes a plurality of upstanding bosses 72 arranged in staggered rows. Each boss 72 includes an annular side wall 72a and a top wall 72b.
All of the lower sheet pillars extend upwardly from the main body portion, are hollow, have a generally truncated pyramidal configuration, and open in the lower face of the main body portion.
Comer pillars 52 have an annular side wall 52a and a top wall 52b.
Intermediate transverse pillars 54 have an annular side wall 54a and a top wall 54b.
Intermediate longitudinal pillars 56 have an annular side wall 56a and a top wall 56b, and have a triangular cross-sectional configuration sized and configured to nest in a V groove 22c defined in an outboard region of the annular wall 22a of the respective downstanding pillar 22.
Central pillar 58 has an annular side wall 58a and a top wall 58b.
In typical twin sheet practice, each of the upper and lower sheets 12 and 14 is formed in a vacuum thermoforming operation and the upper and lower sheets while still in a heated fusible condition are brought together to selectively fuse portions of the upper sheet to portions of the lower sheet to form the pallet.
Specifically, the upper sheet is thermoformed to the configuration seen in
As the sheets are brought together while still in a heated fusible condition, corner pillars 18 are positioned inboard of respective corner pillars 52; intermediate transverse pillars 20 are positioned inboard of respective intermediate transverse pillars 54; intermediate longitudinal pillars 22 are positioned inboard of respective intermediate longitudinal pillars 56 with pillars 56 nesting in respective V grooves 22c; central pillar 24 is positioned telescopically over central pillar 28; the side walls of the corner pillars 18 fuse with the adjacent side walls of respective corner pillars 52; the side walls of intermediate transverse pillars 20 fuse with the adjacent side walls of respective intermediate transverse pillars 54; the side walls of intermediate longitudinal pillars 22 fuse with the adjacent side walls of intermediate longitudinal pillars 56; the inner annular side wall of central pillar 24 fuses with the annular wall of central pillar 58; the annular side wall of each corner pillar 18 further fuses with the corner defined by the intersection of adjacent side walls 74 of the adjacent raised portion 50; the annular side wall of each intermediate transverse pillar 20 further fuses with the corner defined by the intersection of adjacent side walls 74 of a first raised portion 50 as well as with the corner defined by the intersection of adjacent side walls 74 of an adjacent raised portion 50; the annular side wall of each intermediate longitudinal pillar 22 further fuses with a corner defined by the intersection of adjacent side walls 74 of a first raised portion 50 as well as with the corner defined by the intersection of adjacent side walls 74 of an adjacent raised portion 50; the outer annular wall of the central pillar 24 fuses with corners defined by the intersection of adjacent side walls 74 of all four raised portions 50; the upper walls of the pillars of the lower sheet fuse with the underface of the main body portion of the upper sheet; the lower walls of the pillars of the upper sheet fuse with the upper face of the main body portion of the lower sheet; ribs 36, 38, 40, and 42 of the upper sheet fuse with ribs 60, 62, 64, and 66 of the lower sheet; and the bosses 46 of the upper sheet intermesh with the bosses 72 of the lower sheet with the lower walls of the bosses 46 fusing with the upper face of the top walls 68, the top walls of the bosses 72 fusing with the underface of the areas 44 of the main body portion of the upper sheet, and the side walls of the bosses 46 and 68 also fusing at their interfaces.
Note that ribs are provided on the annular side walls of each of the pillars which intermesh when the sheets are brought together to increase the fused contact area and that further rib configurations are provided on the bottom and top walls of the pillars for meshing with the various ribs 36, 38, 40, 42, 60, 62, 64, 66 in the main body portions of the upper and lower sheets to again increase the fused contact area. Note that the truncated pyramidal configuration of the various upstanding and downstanding portions of the upper and lower sheets allow the sheets to fit together like a jigsaw puzzle with truncated pyramidal surfaces fusing with inverted truncated pyramidal surfaces for maximum fusion interface area and maximum pallet strength.
Following the fusion of the upper sheet to the lower sheet, substantially the entire areas of the side walls 74 of the lower sheet are suitably cut away to form generally rectangular openings 76 which in turn define the legs 70. Note that the legs 70 are formed at the corners formed by the intersection of the adjacent side wall 74 so that, in the completed pallet, the downstanding pillars of the upper sheet are actually fused to legs 70.
It will be seen in the completed pallet the pillar structures defined by the respective fusion of the upper and lower pillars are spaced apart in a manner to be aligned with the openings 76 in the side walls 74 so that the aligned openings 76 and the aligned spaces between the pillar structures coact to define forklift passages extending both transversely and longitudinally of the pallet for use in known manner to facilitate transport of the pallet.
It has been found that the pallet of the invention, by virtue of its simple construction and its use of thin plastic sheeting, can be produced at a cost that renders the pallet feasible for use in one-way applications where the pallet, after fulfilling an initial shipping or material handling assignment, is not reused, but rather is destroyed or recycled after the single use.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.
