Molded Pallet

Abstract

A molded pallet with ranks of parallel top and bottom cavities which are dimensional counterparts of each other in reverse, each top and bottom cavity having a common side wall and each top and bottom cavity having coplanar end walls.

Description

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates generally to molded pallets, and particularly to molded pallets having freedom from distortion and great strength.

2. Prior Art

Plastic materials have great appeal for use in the molding of pallets because they are strong, are light weight, do not require repair and maintenance as wood pallets require, need not therefore be frequently replaced, and are low in cost. The rewards of great strength are sought by a variety of intricate designs. In DeLuca U.S. Pat. No. 3,140,672 strength and lightness of weight is attained by cross-ribs interconnecting the legs. In Leitzel U.S. Pat. No. 3,187,691, a variety of oblique ribs impart strength. In Sullivan U.S. Pat. No. 3,199,496, a variety of circular frustum legs are used. In Sullivan U.S. Pat. No. 3,199,468, the coupling of pallets for extra strength is resorted to. Carlson U.S. Pat. No. 3,359,929 provides concentric squares as the basis for improving strength. Toot U.S. Pat. No. 3,424,110 uses ribs defining rectangles, with radial ribs intersecting. While these various forms have strengthened the pallets beyond the strength achieved by the basic deck with legs, greater strength, freedom from distortion, freedom from cracking is still sought.

SUMMARY OF THE INVENTION

It has been found that a molded pallet of great strength can be attained by forming a pallet whose deck has co-equal, opposite, parallel top and bottom cavities arranged in ranks. The cavities on one side equal in volumetric capacity the cavities on the opposite side. In addition, the top and bottom cavities share end walls which extend transversely of the pallet from the top to the bottom of the deck. The walls of the cavities, the floors of the top cavities and the roofs of the bottom cavities all have the same thickness. The cavities extend across the top and the bottom of the sheet except for the provision of deeper cavities defining legs, adjacent cavities have common side walls. It has been found that this construction provides great strength, freedom from breakage and splintering, flexibility and virtual indestructibility.

DRAWINGS

These objects and advantages as well as other objects and advantages are shown by the drawings in which:

FIG. 1 is a perspective view of the pallet,

FIG. 2 is a vertical section taken on the line 2--2 in FIG. 1, looking in the direction of the arrows,

FIG. 3 is another vertical sectional view across a leg, looking in the direction of the arrows; and

FIG. 4 is a partial perspective view of an area of the pallet showing the end walls of the top and bottom cavities lying in the same plane.

PREFERRED EMBODIMENT

Referring now to the drawings in detail, for optimum strength, the plastic pallet is molded of high density polyethylene, although other strong plastic materials may be used. Thus it is resistant to many corrosive chemicals, is resistant to moisture, and relatively free from cracking under stress. In size 40 .times. 48 .times. 6 inches, one-fourth inch thick it can sustain a static load of at least 25,000 pounds. It is relatively light weight, in comparison to conventional wooden pallets, so that it can be carried by hand. It can be designed with any chosen number of legs, so as to permit four-way entry by a fork truck. Its inherent strength is derived mainly from the positioning of the ranks of cavities with respect to each other, and the legs are merely incidental for convenience in handling. The choice of material makes the pallet suitable for use under a wide range of temperature conditions. It can thus be steam cleaned to conform to F.D.A. requirements.

The pallet is molded to have a flat sheet defining a load-bearing deck 11. The sheet 11 is provided with a plurality of elongated top cavities 13. The margins of these top cavities 13 define the top deck surface 10. The bottom surfaces of the floors 14 of these top cavities 13 define the deck base 12. The top cavities 13 define between them, corresponding inverted bottom, elongated bottom cavities 15. The top cavities 13 and the bottom cavities 15 are substantially dimensionally equal. The top deck surface 10 beside the top cavities 13 define the top surfaces of the roofs 16 of the bottom cavities 15.

The top cavities 13 and the bottom cavities 15 are arranged parallel to each other in ranks across the pallet.

Transverse end walls 17 serve for both the top and bottom cavities 13, 15. These end walls lie in the same general plane, and define ends of the ranks of cavities 13, 15, extending transversely across the deck 11. The end walls 17 extend from the top surface 10 to the deck base 12.

Large cavities 18 defining legs are formed in the deck 11 and extend below the deck deeper than the cavities 13. The legs 18 interrupt the ranks. The cavities 13 may be approximately 1.75 inches deep from the upper surface of the deck 11 to the bottom surface of the top cavity 13. The legs 18 are deeper, preferably 6 inches deep from the top of the deck to the bottom of the leg 19. Thus the cavities 13 are spaced, above a surface upon which the pallet rests, sufficiently for the fork of a lift to pass under the deck plate 12. The legs 18 are preferably positioned three on the longer side of the pallet with a space between the outer legs of 30 inches, and the center leg of 8 inches wide leaving two 11-inch spaces for the standard fork. The walls of the pallet may be one-quarter inch thick so as to provide sufficient strength and rigidity.

For accomplishing release from a mold, the top cavities 13, and the bottom cavities 15 have non-parallel walls, i.e., the walls of the top cavities 13 converge downwardly from the top surface 10 and the walls of the bottom cavities 15 diverge downwardly from the top surface 10 forming cavities having a truncated triangular cross-section. The top surface of the floor 14, and the bottom surface of the roof 16 have the same area. The altitudes of the top and bottom cavities 13, 15 are equal.

The legs 18 converge downwardly from the top surface 10 providing a capability for nesting. The altitudes of each of the cavities 13, 15 are the same.

By virtue of this construction, the material of the deck 11 is distributed so as to locate the centroidal axis 4--4 of the deck vertical cross-section (at any point where the section does not cut through a leg cavity but only through a plurality of top and bottom cavities), substantially midway between the top deck surface 10 and the deck base 12. In this manner of construction, great resistance to distortion or deflection of a generally planar object such as the pallet deck is attained.

Claims

I claim:

1. A pallet comprising:

a. a sheet of rigid material,

b. a plurality of separate linear cavities in the top and bottom of the sheet, extending across the sheet substantially the full length thereof,

c. the top and bottom adjacent cavities being dimensional counterparts of each other in reverse,

d. each top and bottom cavity having a continuous side wall in common with each other,

e. a rank of top and bottom equal cavities in parallelism with each other extending at least partly across the sheet,

f. the material defining the cavities disposed to place the centroidal axis of the material substantially midway between the top surface and bottom surface of the material defining the cavities,

g. the margin of the top cavities defining a top deck surface, and the bottom surfaces of the floors of the top cavities defining a deck base,

h. the top and bottom cavities having generally coplanar end walls extending from the top deck surface to the bottom surface of the deck base.

2. A pallet comprising:

a. a device according to claim 1, and

b. deeper cavities in the top of the sheet defining legs.

3. A pallet comprising:

a. the device according to claim 1, and

b. a plurality of ranks of cavities extending at least partly across the sheet.

4. A pallet comprising:

a. the device according to claim 2, and

b. the deeper cavities in the top of the sheet defining legs, spaced sufficiently far apart to receive a fork of a fork lift between them.

5. A pallet comprising:

a. the device according to claim 1, and

b. the sheet and cavities having the same general wall thickness.