DE69618777T2 - PLATE WITH PLASTIC FEET - Google Patents

Abstract

A plastic pallet having an upper platform (12) structure and a plurality of modular plastic legs (16) of box configuration fused to and extending downwardly from the underside of the platform structure. In one embodiment, the modular plastic legs (16) are formed of upper and lower molded plastic parts fused together to form the box configuration (16) and each further including a central column structure (30, 130) positioned within an outer skirt (24, 124) defined by upper and lower parts. In another embodiment, the modular plastic legs are formed of left and right molded plastic parts fused together along a generally vertical seam line (215) to provide the box configuration, and the upper ends of the legs are seated in downwardly opening pockets (228) provided in the lower face of the platform structure. In either embodiment, the pallet may also include a base structure (14) positioned beneath, and fused to the lower ends of the legs to form a double-faced pallet. The platform structure and base structure have a twin sheet configuration.

Description

Background of the invention

The present invention relates to pallets used for storing, packaging and handling materials, and in particular to such pallets provided with plastic feet according to the present invention.

Pallets are traditionally made from wood. However, wooden pallets have a number of disadvantages. For example, they are subject to breakage and therefore cannot be reused for long periods of time. Because wooden pallets are damaged when exposed to wind and weather, they must be stored indoors when not in use and therefore take up a significant amount of valuable floor space in warehouses. In an effort to solve some of the problems associated with wooden pallets, plastic pallets have been developed and used with a degree of success.

In a particularly successful embodiment of plastic pallet construction, a top wall or platform is made by welding or fusing top and bottom plastic panels together to form a reinforced double wall or "double panel" structure.

Some pallets consist of a single top wall forming a load-bearing platform, with a number of feet extending downwardly from the platform to support it in a spaced relationship to a supporting surface on which the feet rest. Other pallets consist of two walls, the first forming an upper platform structure and the second forming a lower base structure, with a number of feet or spacers separating the two. In both of the foregoing types of pallet, referred to as single-sided and double-sided pallets respectively, the feet are distributed over the underside of the platform structure in a number and density sufficient to adequately support the weight that can be expected to be borne by a particular pallet construction when in use in the manner intended. For example, in a rectangular pallet, typically nine feet are provided, one at each corner of the pallet, one in the middle of each side of the pallet and one in the middle of the pallet.

The feet are typically made by molding a large downwardly extending projection into both the upper and lower plastic panels of the dual panel structure at any location where a foot is desired. The foot projection of the upper panel fits into and is welded to that of the lower panel, and the resulting foot extends downwardly, substantially below the bottom surface of the platform structure.

A disadvantage of this design is that the pallet must be manufactured on a mold that can only produce a pallet having a predetermined arrangement of feet. Therefore, producing a range of different pallets optimized for specific applications and having different numbers and arrangements of feet requires the pallet manufacturer to invest in a large number of different molds. In addition, the foot structures are necessarily made of a plastic material of the same thickness as that of the platform structure, so that the structural requirements and problems of the foot structures cannot be addressed individually, but must be addressed taking into account the often divergent structural requirements and problems of the platform structure.

International patent application WO 94/26600 describes a plastic handling pallet having a base and a means for spacing the base from a supporting surface, such as the floor, wherein both the base and the spacing means (i.e. the feet) are made of solid plastic.

A disadvantage of this design is that the pallet is very expensive and heavy due to the fact that its elements are made of solid plastic.

Summary of the invention

The present invention is directed to providing an improved pallet structure that is lightweight, strong, durable, maintenance free, relatively inexpensive, and can be used in all weather conditions or is weather resistant.

The present invention is further directed to providing an improved pallet structure having a modular construction in which pallet platforms and foot units, each of standard design, are manufactured separately and can be assembled together to produce pallets in a wide variety of configurations.

The plastic pallet of the present invention comprises a platform structure having a substantially planar bottom surface and a number of individual feet extending downwardly from the bottom surface in a spaced relationship. Each foot comprises a modular plastic structure in the form of a box having a substantially planar upper portion, a substantially planar lower portion, and an annular portion connecting the upper and lower portions together and maintaining the upper and lower portions in a spaced relationship. The feet are firmly attached to the platform structure by fusing the upper portions of each foot to the bottom of the platform structure with the feet in a spaced relationship. This modular construction allows the structural requirements of the feet to be addressed in detail, thus facilitating the creation of an extremely stable yet relatively inexpensive pallet structure.

According to a further feature of the present invention, the annular portion of each foot has an outer skirt or rim portion, and each foot further has a column structure disposed within the rim portion and interconnecting the upper and lower planar portions. This arrangement provides for an extremely stable foot structure and further provides a foot structure that will survive even near complete destruction of the outer rim portion of the foot by a forklift or the like.

According to a further feature of the invention, each foot is made of first and second plates of plastic material which are welded or fused together to form the assembly in the form of a box. This special construction enables the feet to be manufactured quickly and inexpensively.

According to a further feature of the invention, the first plastic plate is shaped to form a first planar main body portion and a first annular skirt portion extending therefrom to define a first annular surface, the second plastic sheet defining a second planar main body portion and a second annular surface corresponding in shape and size to the first annular surface. The first and second sheets are welded together at their respective annular surfaces to form a hollow box-like foot having first and second main body portions spaced apart from each other by the annular skirt portion. The resulting foot is secured to the platform structure by welding one of the main body portions to the underside of the platform structure. The pallet thus formed includes feet which can be economically manufactured separately from the platform by a vacuum forming process and thereafter welded to the platform in the number, shape and spacing required to give the pallet sufficient strength for a particular pallet application.

According to a further feature of the present invention, the first plastic sheet comprises an upper plate, the first annular skirt portion extending downwardly from the first main body portion so that the first annular surface faces downwardly, and the second plastic sheet comprises a lower plate and further comprises a second annular skirt portion extending upwardly from the second main body portion so that the second annular surface is formed by an upwardly facing upper annular edge of the second edge portion. This construction enables the upper and lower plates to be manufactured in the form of two identical pieces, with corresponding advantages in terms of manufacturing economy.

According to a further feature of the present invention, the pallet further comprises a substantially planar base structure, the top of which is fused or welded to the main body portion of the lower plate of the foot, so that the foot, in cooperation with the other feet, separates the platform structure and the base structure from each other to form passageways therebetween for the entry of material handling equipment. The pallet thus manufactured is of the double-sided type in which the base structure, rather than the feet themselves, contacts a supporting surface on which the pallet rests.

According to another feature of the present invention, a foot comprises an upper plastic plate having an upper surface secured to the lower surface of the pallet platform wall and a hollow upper lug opening into and extending downwardly from the upper surface and a lower plastic plate having a hollow lower lug opening into and extending upwardly from a lower surface of the lower plate. The upper and lower lugs contact one another and are fused or welded together so as to join the upper and lower plates together. The foot thus formed is well suited for manufacture by a vacuum forming process and the cooperating lugs provide considerable strength to the foot.

According to a further feature of the present invention, the upper lug comprises an annular side wall and a bottom wall, and the lower lug comprises an annular side wall, the side walls having a substantially equal height. In joining the upper and lower plates, the side walls of the upper and lower lugs are welded together, the bottom wall of the upper lug being welded to an upper surface of the lower plate, and the upper wall of the lower lug being welded to a lower surface of the upper plate. By welding the upper and lower plates together in this manner, the lugs cooperate to form a central column structure which contributes significantly to the overall crush resistance of the base structure.

According to a further feature of the present invention, the upper plate further comprises an upper, annular, downwardly extending skirt portion in surrounding relation to the upper lug, and the lower plate further comprises a lower, annular, upwardly extending skirt portion in surrounding relation to the lower lug, a lower annular edge of the upper skirt portion being welded to an upper annular edge of the lower skirt portion. This arrangement creates a box-like foot structure, with the annular skirt portions and lugs interconnecting the upper and lower surfaces of the foot, thereby providing the foot with increased rigidity and resistance to compression.

According to a further feature of the present invention, the side walls of the upper and lower lugs are tapered in a complementary manner to provide an angled interface therebetween and the side walls are welded together at this angled interface. The tapered arrangement of the side walls of the lugs provides an improvement in both the manufacturability of the feet and their strength.

According to a further feature of the present invention, the side walls of the upper and lower lugs have grooves running the length of the angled interface so that when the side walls are welded together, the grooves are aligned to form a hollow stiffening column running between the upper and lower surfaces of the foot along the angled interface at the epicenter of the foot structure. This stiffening column provides a further significant increase in the crush resistance of the foot with only a small increase in the amount of plastic material required to manufacture the foot.

According to a further feature of the present invention, a number of spaced downwardly opening pockets are provided in an underside of the platform structure, each foot being a hollow, closed box-like arrangement and comprising an upper wall structure, and the upper wall structure of each foot being inserted into a respective pocket and welded or fused to the plastics material of the platform structure forming that pocket. This arrangement provides a pallet which can be manufactured in a cost-effective manner and which enables a range of pallet sizes to be manufactured from a single platform structure, simply by varying the characteristics of the feet which are welded to the platform structure.

According to a further feature of the present invention, the upper wall structure of each foot is sized and shaped to match the size and shape of the respective pocket so that it fits snugly within that pocket. This arrangement provides a positive attachment between the platform and the foot and optimizes the shear strength of the pallet.

According to a further feature of the present invention, the platform structure comprises a double plate structure consisting of upper and lower thermoformed plastic plates which are selectively fused or welded together, with the pockets in the lower plastic plate. This special construction provides a simple and convenient means of forming the pockets to accommodate the feet.

According to a further feature of the present invention, each foot is made from first and second thermoformed plastic parts welded together. This arrangement provides a simple and inexpensive means of providing the feet.

According to a further feature of the present invention, the plastic parts of each foot are welded together along a seam line which lies in a substantially vertical plane. This arrangement facilitates the assembly of the feet and provides excellent strength of the feet.

According to a further feature of the present invention, the pallet further comprises a base structure; a number of spaced, upwardly opening pockets are provided in a lower surface of the base structure; and each foot comprises a lower wall structure having a shape and size corresponding to the shape and size of a corresponding pocket of the base structure, being received in that pocket and being welded to the plastics material of the base structure forming that pocket. This arrangement provides a convenient and inexpensive means of producing a double-sided pallet having excellent strength properties and very good flexibility.

According to a further feature of the present invention, the base structure comprises a dual plate structure made from upper and lower thermoformed plates which are selectively welded together, with the upwardly opening pockets formed in the lower plastic plate. This arrangement provides a simple and effective means of providing the upwardly opening pockets.

The present invention further provides an improved double-sided plastic pallet comprising a substantially planar platform structure defining a top surface forming a surface for supporting an article and a bottom surface; a substantially planar base structure forming a lower pallet support surface and a top surface; and a plurality of hollow feet having a closed box-like configuration disposed between the platform and base structures and each comprising an upper wall structure welded to the bottom of the platform structure and a lower wall structure welded to the top of the base structure. This arrangement provides a double-sided plastic pallet with high strength, cost-effective production and a wide range of applications.

Short description of the drawings

Fig. 1 shows a perspective view of a double-sided pallet according to a first embodiment of the invention;

Fig. 1A shows a perspective view of a single-sided pallet according to the first embodiment of the invention;

Fig. 2 shows a side view of the pallet according to Fig. 1;

Fig. 3 shows a perspective view of a foot used in the pallet according to the invention;

Fig. 4 is a cross-sectional view taken along line 4-4 in Fig. 3;

Fig. 5 is a cross-sectional view taken along line 5-5 in Fig. 3;

Fig. 6 is a cross-sectional view taken along line 6-6 in Fig. 3;

Figs. 7A and 7B are perspective views of an upper and lower half, respectively, used in the construction of a foot of the pallet;

Fig. 8 shows a perspective view of a double-plate plastic pallet according to a second embodiment of the invention, comprising a base structure, a platform structure and a number of feet arranged between the base and the platform structure;

Fig. 9 is a fragmentary cross-sectional view taken along line 9-9 in Fig. 8;

Fig. 10 shows a plan view of the pallet with the platform structure removed;

Fig. 11 shows a plan view of the base structure;

Fig. 12 shows a bottom plan view of the platform structure;

Fig. 13 is a perspective view showing the base structure and some feet;

Fig. 14 shows a partial bottom plan view of the platform structure;

Figs. 15 and 16 are top views of feet used in the pallet according to the invention;

Fig. 17 shows a partial perspective view of the platform structure from below;

Fig. 18 shows a joint view of the feet from below;

Fig. 19 is a side view showing the use of the pallet according to the invention in a shrink-wrapping type procedure;

Fig. 20 shows a detailed view within the circle 20 of Fig. 19;

Fig. 21 shows a partial detailed view showing a modified form of the pallet according to the second embodiment; and

Fig. 22 shows a plan view of the modified pallet according to Fig. 21.

Detailed description of the preferred embodiments

A first embodiment of the pallet according to the invention is shown in Figs. 1 to 7; a second embodiment of the pallet according to the invention is shown in Figs. 8 to 20; and a modified form of the pallet according to the second embodiment is shown in Figs. 21 and 22.

As shown in Fig. 1, the pallet 10 according to the first embodiment of the invention consists essentially of an upper platform structure 12, a lower base structure 14 and feet 16 arranged therebetween and fixedly connected to the platform structure 12 and the base structure 14. The pallet 10 can have any desired shape and size with any desired number of feet 16. A representative Pallet as used in industry is rectangular and has nine feet, one foot at each corner of pallet 10, one at the center of each of the four sides, and one at the center of pallet 10. Feet 16 are spaced apart to form passageways 18 through pallet 10 for forklift access. Passageways 18 are accessible from all four sides of pallet 10 and are of sufficient size to accommodate the tines or forks of a forklift (not shown) or similar material handling device for lifting and moving pallet 10.

An alternative form of pallet according to the present invention is shown in Fig. 1A and is identical to the form described above in all respects except that the pallet 10' is of the single-sided type and as such has no base structure. Feet 16' are attached to the underside of the platform structure 12' and rest directly on a supporting surface. It should be noted that as in the first embodiment described, the spaces between the feet 16' form passageways 18' for forklift entry which are accessible from all four sides of the pallet 10'.

As shown in Figures 3-7, each foot 16 is formed from an upper plastic plate 20 and a lower plastic plate 120 which are welded together to form a box-like structure. The plates 20, 120 are manufactured in cooperation with vacuum forming molds (not shown) as described in U.S. Patent No. 5,401,347. The forming process involves heating the plates 20, 120, which are flat as a starting material, and using a vacuum to form each plate into conformity to corresponding molds. While the plates 20, 120 are still in a heated, flowable state, the molds are brought together to bring the plates 20, 120 into contact with one another and weld them together along selected surfaces.

It should be noted that in the embodiment of the foot 16 as described and illustrated herein, the upper plate 20 and the lower plate 120 are identically formed pieces and that, to this extent, the distinction between the plates 20 and 120 as upper and lower plates is entirely arbitrary and is made here only for the purpose of description. To emphasize this fact, the reference numerals assigned to the components forming the lower plate 120 differ from those associated with the components of the upper plate 20, only in their first digit. It should also be noted that any description of a feature of the upper plate 20 also refers to the corresponding feature of the lower plate 120.

As best seen in Figure 7A, the top plate includes a substantially planar top wall member 22 and a skirt or rim member 24 extending downwardly from the periphery thereof. The vertical dimension of the rim portion 24 varies along the periphery so that the lower, distal edge 24A of the rim portion 24 has a stepped or notched configuration. The distal edge 24A is flared outwardly to form a flange 26, the lower portion of which forms an annular connecting surface 27 extending around the entire periphery of the rim member 24.

In order to give greater rigidity to the resulting foot structure, the edge portion 24 is provided with a number of vertically extending channels 28 which project inwardly from the outer surface of the edge portion 24.

A hollow boss 30 extends downwardly from the upper wall member 22 and has a generally frustoconical shape with an annular side wall 32 and a generally flat bottom wall 34. The boss 30 is offset toward one end of the upper plate 20 and a flat 36 is formed on the side of the boss 30 facing the end of the upper plate 20, opposite the direction of the offset. The flat 36 extends straight downwardly on the frustoconical portion of the boss 30 and a groove 38 extends along the centerline of the flat 36, projecting toward the inner or concave side of the boss 30.

As noted, the lower plate 120 is identical to the upper plate 20 but is oriented in an inverted position so that the skirt 124 extends upwardly from the periphery of a planar bottom wall portion 122 and flares outwardly at a distal edge 124A to form a flange 126, the lower portion of which forms an annular connecting surface 127, with the lug 130 extending from the bottom wall portion 122 in an offset, interlocking relationship with the downwardly extending lug 30.

In the final step of the method of making the feet described above, the upper plate 20 and the lower plate 120 are aligned and brought together in the confronting relationship shown in Figures 7A and 7B so that the grooved lower and upper edges of the skirts 24, 124 are assembled in an interlocking relationship with the joint surfaces 27, 127 registering and being welded together along substantially the entire circumference of the flanges 26, 126. The lugs 30, 130 also matingly interlock with the flats 36, 136 in planar contact with each other and being welded together along the angled interface therebetween. When the parts are so engaged, the grooves 38, 138 are aligned with each other, forming a hollow stiffening column 40, best seen in Figures 4 and 6, extending along the angled interface.

The tabs 30, 130 preferably have an equal height, which height is equal to the combined height of the skirts 24 and 124, so that the distance between the upper wall portion 22 and the lower or bottom wall portion 122 is completely bridged. In this arrangement, when the lower and upper plates 20, 120 are joined together to weld the skirts 24, 124, the bottom wall 34 of the tab 30 is disposed in contact with and welded to the top of the bottom wall portion 122, and the upper wall 134 of the tab 130 is similarly disposed in contact with and welded to the bottom of the upper wall portion 22.

The plastic foot 16 manufactured in this manner has a top surface formed by the top wall portion 22 of the top plate 20, a bottom surface formed by the bottom wall portion 122 of the bottom plate 120, an annular skirt or shell formed by the skirts 24, 124 welded together, a central support or column structure formed by the tabs 30 and 130 welded together and cooperating with the annular skirt to form an annular space therebetween, and a further stiffening column structure 40 at the epicenter of the foot.

To manufacture a single-sided pallet 10' using the feet 16 according to the present invention, the mounting surfaces formed by the top surfaces of the upper wall portions 22 are suitably welded to a number of downwardly facing mounting surfaces formed on the underside of the platform structure 12'at spaced apart positions as shown in Fig. 1A. To produce a double-sided pallet 10, the undersides of the lower wall portions 122 are suitably welded to a top of the platform structure 14 at spaced apart positions as shown in Fig. 1.

While the particular plastic material used to make the pallet of the invention is not critical, it has been found that excellent results can be obtained by using a high density polyethylene having a density of about 0.950 grams per cubic centimeter.

The pallet 210 according to the second embodiment of the present invention is a double-sided pallet of dual plate construction. In particular, the pallet 210 includes an upper platform structure 212, a lower base structure 214, and a number of modular feet 215, 216, 217, and 218 that interconnect the platform structure and the base structure. The platform structure 212, the base structure 214, and the feet 215-218 are made of an organic polymer material, such as polyethylene. The platform structure 212 and the base structure 214 are preferably of dual plate construction using two plastic plates that are vacuum formed and welded or meshed together at different points to provide additional structural rigidity.

The platform structure 212 is formed of an upper plastic plate 219 and a lower plastic plate 220. The upper plate 219 has a series of rows of downwardly extending lugs 219a and the lower plate 220 has a series of rows of upwardly extending lugs 220a. The downwardly extending and upwardly extending rows of lugs are arranged in an interlocking manner and are welded together at the interface of the interlocking lugs to form rows of column lugs. The rows of columns may, for example, extend parallel to the longitudinal and transverse side edges 212a, 212b of the platform structure. Further details of the manner in which the lugs of the upper and lower plates are welded together to form the column structures are set forth in U.S. Patent Nos. 5,390,467, 5,401,347, and 5,470,641 and U.S. Patent Application Serial No. 08/426,876, filed April 24, 1995.

The peripheral edges 219b and 220b of the upper and lower plates are welded together to form a downwardly extending peripheral lip or rim 222 which defines a downwardly opening groove 224 extending completely around the periphery of the platform structure. The lip or rim 222 is made by bringing the peripheral edge portion 220b of the lower plate upwardly into proximity with the peripheral edge portion 219b of the lower plate and bending the edge portions of the plates downwardly together. The rim 222 is formed by a downwardly extending outer edge portion 220c of the lower plate 220 and a downwardly extending outer edge portion 219c of the upper plate 219. The edge portions 219c, 220c are selectively spaced from one another near their upper regions to define circumferentially spaced gaps 226 therebetween for structural rigidity and are continuously welded together at an interface 228 adjacent their lower regions.

The upper and lower plates 219, 220 are also configured at circumferentially spaced positions around the periphery of the platform structure to form downwardly opening recesses or pockets 228 to receive respective feet 215, 216, 217 and 218. In particular, corner pockets 228a are formed at each corner of the platform structure; longitudinal pockets 228b are formed along each longitudinal edge 212a of the platform structure; transverse pockets 228c are formed along each transverse edge 212b of the platform structure; and a central pocket 228d is formed in a central portion of the platform structure.

The base structure 214 is made of upper and lower plastic plates 230, 232 which define downwardly extending rows of lugs 230a and upwardly extending rows of lugs 232a, respectively, which are interlockingly arranged and welded together at their interlocking interfaces to form rows of columns similar to the rows of columns in the platform structure, but arranged in rows extending substantially parallel to the longitudinal and transverse edges 214a and 214 of the base structure. The base structure 214 may consist of a single, continuous structure, or may include cutouts 214c, as shown, to give the base structure an open, grid-like arrangement.

The top plate 230 is further configured to form upwardly opening recesses or pockets 234 corresponding in number and circumferential arrangement to the downwardly opening pockets 228 in the platform structure and arranged to receive the lower ends of the feet 215-218. In particular, corner pockets 234a are formed at each corner of the base structure, longitudinal pockets 234b are formed along each longitudinal edge 214a of the base structure; transverse pockets 234c are formed along each transverse edge 214b of the base structure; and a central pocket 234d is formed in a central region of the base structure.

The feet 215 through 218 have a modular closed box-shaped construction, and each includes a left half 215a, 216a, 217a and 218a and a right half 215b, 216b, 217b and 218b welded together along a respective weld line 215c, 216c, 217c and 218c. The lower end of each foot 215 is adapted to be inserted or inserted into a corresponding pocket 234a of the base structure; the upper end of each foot 215 is adapted to be inserted or inserted into a corresponding corner pocket 228a of the platform structure; the lower end of each foot 216 is configured to fit within a pocket 234c on the transverse edge of the base structure; the upper end of each foot 216 is configured to fit within a transverse pocket 228c of the platform structure; the lower end of each foot 217 is configured to fit within a corresponding transverse pocket 234b of the base structure; the upper end of each foot 217 is configured to fit within a transverse pocket 228b of the platform structure; and the upper and lower ends of the foot 218 are configured to fit in pockets 228d, 234d, respectively.

The outer wall 216f of each foot 216 is stepped inwardly at 216g to define a recessed upper wall portion 216h which is stepped inwardly with respect to the lip or rim 222 so as not to encroach upon the groove 224 and not to interfere with access to the groove 224. The outer wall 217f of each foot 217 is stepped inwardly at 217g to define a recessed upper wall portion 217h which is stepped inwardly with respect to the lip or rim 222 so as not to encroach upon the groove 224 and not to interfere with access to the groove 224. The outer longitudinal side 215f of each foot 215 is stepped inwardly at 215g to form an upper recessed wall portion 215h which extends inwardly from the lip or rim 222 so as not to encroach upon the groove 224, and the outer transverse side 215i of each foot 215 is stepped inwardly at 215j to define a recessed upper wall portion 215k which is stepped inwardly with respect to the lip or rim 222 so as not to encroach upon the groove 224. The central foot 218 extends between central pockets 228d and 38d to support the central region of the pallet. The upper ends of the feet 215, 216, 217 and 218 are welded in position within the corresponding upper pockets 228, and the lower ends of the feet 215, 216, 217 and 218 are welded in position in the corresponding lower pockets 234. It will be appreciated that the inwardly stepped configuration of the feet prevents the upper ends of the feet from over-encroaching on the groove 224 so that access to the groove 224 is unimpeded at any point along the perimeter of the platform structure.

The pockets 234a-234d in the top of the base structure 214 have a substantially identical rectangular, tapered truncated pyramid-like configuration, and each of the feet 215-218 have a rectangular, tapered footprint of a truncated pyramid-like configuration, with dimensions such as to fit snugly within a corresponding pocket 234. In addition, the outer feet 215-217 have projecting ledge structures to enable the outwardly facing sides of the feet to be positioned substantially flush with the outer perimeter of the base structure. In particular, the feet 217 have ledges 217j designed to rest on the top of the plate 230 outside the longitudinal edge of the respective pocket 234b; the feet 216 have strips 216j intended to bear on the upper surface of the plate 230 outside the transverse edge of a corresponding pocket 234c; and the corner feet 215 have strips 215j and 215k intended to bear on the upper surface of the plate 230 outside the longitudinal and transverse edges of the corresponding pocket 234a.

The upper ends of the feet 215 to 218 have varying profiles, and the corresponding pockets 228a to 228d of the platform structure have shapes and configurations designed to individually and firmly receive the upper ends of the corresponding feet.

In particular, the upper end 218d of the central foot 218 has a simple truncated pyramidal configuration and is seated in a central pocket 228d of corresponding size and configuration; the upper end of each transverse foot 216 is seated in a corresponding pocket 228c and includes large area beveled surfaces 216l, 216m and 216n abutting against large area beveled surfaces 220d, 220e and 220f of a pocket defined by the bottom plate 220 of the platform structure and further includes a small area beveled surface 216p abutting against a small area beveled surface 220j seated on the inwardly facing side of a boss 220h formed in the bottom plate 220 of the platform structure; the upper end of each longitudinal foot 217 is seated in a corresponding pocket 228b and includes large area beveled surfaces 217l, 217m and 217n abutting against large area beveled surfaces 220k, 220l and 220m of the pocket and further includes a small area beveled surface 217p abutting against a small area beveled surface 220n formed on the inwardly facing side of a boss 220p formed in the bottom plate 220 of the platform structure; and the upper end of each corner foot 215 is seated in a corresponding pocket 228a and includes large area beveled surfaces 215l and 215m abutting against large area beveled surfaces 220q and 220r of the pocket, and further includes small area beveled surfaces 215n and 215p abutting against small area beveled surfaces 220s and 220t formed on the inwardly facing sides of a rectangular boss 220u formed in the bottom plate 220 of the platform structure.

It can be seen that in the completed pallet, the upper and lower ends of the feet are positioned in the respective pockets in the platform structure and in the base structure, and that the plastic material of the feet is fused or welded to the plastic material of the platform structure and the base structure at the interfaces between the different surfaces of the upper and lower ends of the feet and the different surfaces defining the pockets.

12 and 13 illustrate the manner in which the pallet of the invention is used to facilitate the shrink wrapping of an article, such as article 238, positioned on top of the platform structure. In particular, article 238 is shrink wrapped in place on platform structure 212 by using a plastic film web 240 in the form of a bag which is positioned in a covering relationship over the article after its lower peripheral edge 240a is folded upwardly into downwardly opening groove 224 so that the lower edge 240a of the film web is firmly secured to the platform structure and inadvertent detachment of the film web from the platform structure and exposure of the article is prevented. If desired, as shown in Figure 20, a flat sanitizing film sheet 241 may be positioned on the platform structure prior to placing the article 238 on the platform structure, after which the article 238 may be placed on the platform structure over the film sheet 241, the bagged sheet 240 may be placed over the article, and the lower peripheral edges 240a and 241a of the bagged film and the flat film may be folded up together into the downwardly opening groove 224.

In the modified embodiment of the pallet shown in Figures 21 and 22, the upper and lower plates 219' and 220' of the platform structure 212' are configured to form transversely extending cavities 242 located within the foot pockets 228' and extending parallel to the transverse side edges 212b' of the platform structure, and a tubular steel beam 248 is disposed in each cavity 242 to provide greater rigidity to the platform structure and pallet. Preferably, the upper and lower plates are further configured to have longitudinally extending cavities 250 extending parallel to the longitudinal side edges 212a' of the platform structure within the foot pockets 228, and longitudinally extending tubular steel beams 252 are disposed in the cavities 250 so as to cooperate with the beams 248 to form a rectangular support structure extending along the periphery of the platform structure within the feet.

The pallet structures described provide a cost effective pallet construction; they allow a single platform structure and/or a base structure with different sized feet to be used to provide a range of pallet sizes; they allow excellent crush resistance due to the closed box configuration of the feet; they provide excellent shear resistance in both major directions achieved by having the pocket side walls enclose the top and bottom ends of the feet; and they provide a freely downward opening groove around the entire perimeter of the platform structure to facilitate shrink wrapping of articles on the pallet.

While preferred embodiments of the invention have been shown and described in detail, it will be understood that numerous changes may be made to the illustrated embodiments without departing from the scope of the invention.

Claims (23)

1. A plastic pallet (10, 10', 210) comprising a substantially planar plastic platform structure (12, 12', 212, 212') having a bottom surface and a number of individual feet (16, 16', 215 to 218) extending downwardly from the bottom surface in a spaced-apart relationship, the feet (16, 16', 215 to 218) being fixedly secured to the bottom surface of the platform structure (12, 12', 212, 212'), characterized in that: a number of spaced, downwardly facing mounting surfaces are defined on the underside of the platform structure (12, 12', 212, 212'); each foot (16, 16', 215, to 218) consists of a modular plastic structure in the form of a hollow, closed box, having an upper portion forming an upwardly facing mounting surface (22, 2151-p, 2161-p, 2171-p, 218d), a lower portion disposed underlying the upper portion, and an annular portion interconnecting the upper and lower portions to complete the foot assembly in the form of a hollow, closed box; and the feet (16, 16', 215 to 218) are firmly attached to the platform structure (12, 12', 212, 212') by positioning the upwardly facing attachment surfaces (22, 2151-p, 2161-p, 2171-p, 218d) of each foot (16, 16', 215-218) adjacent to a corresponding downwardly facing attachment surface on the underside of the platform structure (12, 12', 212, 212') and sealing or fusing the upper portion of each foot (16, 16', 215-218) to the underside of the platform structure (12, 12') at the interface of the attachment surfaces. 2. Plastic pallet (10, 10') according to claim 1, characterized in that the annular portion of each foot (16, 16') has an outer edge portion (24, 124); and that each foot (16, 16') further has a central inner column (30, 40, 130) which is arranged within the outer edge portion (24, 124) and connects the upper (22) and lower (122) portions together. 3. Plastic pallet (10, 10', 210) according to claim 1, characterized in that each foot (16, 16', 215-218) is made of first (20, 215a, 216a, 217a, 218a) and second (120, 215b, 216b, 217b, 218b) plates of plastic material which are welded or fused together to form the arrangement in the form of a hollow box. 4. Plastic pallet (210) according to claim 3, characterized in that the plastic parts of each foot (215-218) are welded or fused together along a seam line (215c, 216c, 217c, 218c) which lies in a substantially vertical plane. 5. Plastic pallet (10, 10') according to claim 3, characterized in that: the first molded plastic sheet (20) forms a first planar main body portion (22) and an annular edge portion (24) extending from the main body portion (22), defining a first annular surface (24); the second plastic sheet (120) defines a second planar main body portion (122) and a second annular surface (124) corresponding in shape and size to the first annular surface (24); and the first (20) and second (120) plates are welded or fused together at their respective annular surfaces (24, 124). 6. Plastic pallet (10, 10') according to claim 5, characterized in that: the first upper plastic plate (20) has an upper projection (30) opening into the top (22) of the main body portion (22) and an annular side wall (32) extending downward from the main body portion (22); the second lower plastic plate (120) has a lower projection (130) opening into the bottom (122) of the main body portion (122) and an annular side wall portion (132) extending upwardly from the main body portion; and the annular side wall portion (132) of the lower extension (130) is welded or fused to the annular side wall portion (32) of the upper extension (30). 7. Plastic pallet (210) according to one of claims 1 to 6, characterized in that a number of spaced, downwardly opening pockets (228, 228') are provided in a lower side of the platform structure (212, 212'), the upper wall structure (2151-p, 2161-p, 2171-p, 218d) of each foot (215-218) being inserted into a corresponding pocket (228, 228') and being welded or fused to the plastic material of the platform structure (212, 212') which forms this pocket (228, 228'). 8. Plastic pallet (210) according to claim 7, characterized in that the upper wall structure (2151-p, 2161-p, 2171-p, 218d) of each foot (215-218) has a shape and a size that corresponds to the shape and size of the corresponding pocket (228, 228') so that it fits snugly within this pocket (228, 228'). 9. Plastic pallet (210) according to one of claims 1 to 8, characterized in that the platform structure (212, 212') has a double plate structure consisting of upper (219, 219') and lower (220, 220') thermoformed plastic plates which are selectively fused or welded together. 10. Plastic pallet (210) according to claim 9, if dependent on claim 7 or 8, characterized in that the pockets (228, 228') of the platform structure (212, 212') are formed in the lower plastic plate (220, 220'). 11. Plastic pallet (210) according to claim 9 or 10, characterized in that: the upper (219, 219') and lower (220, 220') plates are held in a vertical, spaced apart, parallel relationship in a central portion of the platform structure (212, 212'); and the peripheral edges (219b, 220b) of the upper (219, 219') and lower (220, 220') plates are welded or fused together to form a downwardly extending peripheral edge (222) having a downwardly extending opening groove (224) near the periphery of the platform structure (212, 212'). 12. Plastic pallet (210) according to claim 11, characterized in that the edge (222) is produced by bringing the peripheral edge portion (220b) of the lower plate (220, 220') upwards into the vicinity of the peripheral edge portion (219b) of the upper plate (219, 219') and bending the edge portions of the plates downwards together. 13. Plastic pallet (210) according to one of claims 1 to 12, characterized in that the feet (215-217), which are arranged spaced apart from one another along the circumference of the platform structure (212, 212'), have an outwardly facing wall structure (215f, 215i, 216f, 217f) with an upper section (215h, 215k, 216h, 217h) which is drawn inwards with respect to the lower section. 14. Plastic pallet (210) according to claim 13, characterized in that the lower portion of the wall structure (215f, 215i, 216f, 217f) of each foot (215-217) is arranged approximately flush with the outer periphery of the platform structure (212, 212'). 15. Plastic pallet (210) according to claim 13 or 14, characterized in that: the platform structure (212, 212') forms a circumferentially extending downwardly extending edge (222) defining a downwardly opening groove (224) extending along the circumference of the platform structure (212, 212'); and the upper portion of the wall structure (215h, 215k, 216h, 217h) of each foot (215-217) is spaced inwardly from the edge (222) so that it cannot penetrate into the area of the groove (224). 16. A plastic pallet (210) according to claim 15, characterized in that the groove (224) extends around the periphery of the platform structure (212, 212') outside the feet (215-217) and in an outwardly spaced relationship to the outwardly facing surfaces (215f, 215i, 216f, 217f) of the feet (215-217). 17. Plastic pallet (10, 210) according to one of claims 1 to 16, characterized in that: the pallet (10, 210) further comprises a substantially planar base structure (14, 214); and a bottom surface of the foot (16, 215-218) is fused or welded to a top surface of the base structure (14, 214) such that the foot (16, 215-218), in concert with the other feet (16, 215-218), separates the platform structure (12, 212) and the base structure (14, 214) to form passageways therebetween for the entry of material handling equipment. 18. Plastic pallet (210) according to claim 17, as far as it relates to one of claims 13 to 16, characterized in that: the base structure (214) has a size and shape that approximately corresponds to the size and shape of the platform structure (212, 212'); and lower portions of the outwardly facing wall structure (215f, 215i, 216f, 217f) of the feet (215-217) are arranged approximately flush with the outer periphery of the base structure (214). 19. Plastic pallet (210) according to claim 17 or 18, characterized in that: a number of spaced apart, upwardly opening pockets (234) are arranged in an upper surface of the base structure (214); and each foot (215-218) comprises a lower wall structure having a size and shape corresponding to the shape and size of a corresponding pocket (234) of the base structure and received in said pocket (234) being fused or welded to the plastic material of the base structure (214) forming said pocket (234). 20. Plastic pallet (210) according to one of claims 17 to 19, characterized in that the base structure (214) has a double plate structure consisting of upper (230) and lower (232) thermoformed plates which are selectively fused or welded together. 21. Plastic pallet (210) according to claim 20, as far as dependent on claim 19, characterized in that the upwardly opening pockets (234) of the base structure (214) are formed in the upper plastic plate (230). 22. A method of manufacturing a plastic pallet (210) of the type having a platform structure (212, 212') and a number of circumferentially spaced arranged feet (215-217) extending downwardly from the platform structure (212, 212'), the method comprising: Heat forming upper (219, 219') and lower (220, 220') plastic plates; selectively fusing or welding central main body portions of the plates (219, 219', 220, 220') together to form a central platform portion (212, 212') for the pallet (210); and fusing peripheral edge portions (219b, 220b) of the plates (219, 219', 220, 220') together to form a downwardly extending peripheral edge (222) defining a downwardly extending and opening groove (224) near the periphery of the platform structure (221, 212'). 23. A method for packaging an article (238), comprising the steps of: Making a pallet (210) by heat forming upper (219, 219') and lower (220, 220') plastic panels, optionally fusing or welding central main body portions of the panels (219, 219', 220, 220') together to make a platform structure (212, 212'), fusing or welding circumferential edge portions (219b, 220b) of the panels (219, 219', 220, 220') together to form a downwardly extending circumferential edge (222) defining a downwardly opening groove (224) near the periphery of the platform structure (212, 212'), and providing a number of circumferential spaced apart feet (215-217) extending downwardly from the platform structure (212, 212'); Placing the object (238) on the platform structure (212, 212'); and Shrink wrapping the article (238) on the platform structure (212, 212') using a plastic film sheet (240) by placing the film sheet (240) in a covering relationship over the article (238) and folding a lower edge (240a) of the film sheet (240) upward into the downwardly opening groove (224).