EP0824462B1

EP0824462B1 - Pallet with plastic legs

Info

Publication number: EP0824462B1
Application number: EP96912985A
Authority: EP
Inventors: Lyle H. Shuert
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-04-24
Filing date: 1996-04-23
Publication date: 2002-01-23
Anticipated expiration: 2016-04-23
Also published as: EP0824462A4; JPH11514315A; AU710867B2; DE69618777T2; DE69618777D1; CA2215601A1; CA2215601C; EP0824462A1; WO1996033919A1; AU5562596A; ATE212312T1

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

This invention relates to pallets used to package, store, and handle materials and more specifically to such pallets having plastic legs according to the invention.
Pallets have traditionally been formed of wood. Wood pallets, however, have many disadvantages. For example, they are subject to breakage and thus are not reusable over extended periods of time. Wood pallets, as they will deteriorate if left exposed to the elements, must be stored indoors when not in use and so take up a considerable amount of valuable floor space in the warehouse. In an effort to solve some of the problems associated with wood pallets, plastic pallets have been developed and employed with some degree of success.
In one generally successful form of plastic pallet design, an upper panel or platform is formed by fusing together upper and lower plastic sheets to form a reinforced double wall or "twin sheet" structure.
Some pallets consist of a single upper panel constituting a load-bearing platform with a plurality of legs extending downward from the platform to maintain it in spaced relation to a support surface on which the legs rest. Other pallets consist of two panels, the first constituting an upper platform structure and the second a lower base structure, with a plurality of legs or spacers separating the two. In both of the foregoing types of pallets, referred to as single faced and double faced pallets respectively, the legs are distributed over the undersurface of the platform structure in a number and density sufficient to adequately support the weight likely to be carried by a particular pallet design when used in its intended manner. For example, for a rectangular pallet, there will typically be nine legs with one located at each corner of the pallet, one midway along each of the pallet sides, and one at the center of the pallet.
The legs are typically formed by molding at each location where a leg is desired a large downwardly extending protrusion in both the upper and lower plastic sheets of the twin sheet structure. The leg protrusion of the top sheet fits inside of and is fused to that of the lower sheet, and the resulting leg extends downwardly substantially below the lower surface of the platform structure.
A disadvantage of this construction is that the pallet must be fabricated on a mold that can only produce a pallet having one predetermined configuration of legs. Thus, the production of a range of different pallets optimized for specific applications and having different numbers and patterns of legs requires the pallet fabricator to invest in a large number of different molds. Further, the leg structures are of necessity formed of the same thickness plastic material as the platform structure so that the structural requirements and concerns of the leg structures may not be individually addressed but, rather, must be address in consideration of the often divergent structural requirements and concerns of the platform structure.
The international Application WO 94/26600 discloses a plastic handling pallet comprising a base and a means for spacing the base from a supporting surface such as the ground, both the base and the spacing means (i.e. the legs) being made from solid plastic.
A disavantage of this construction is that the pallet, on account of its elements made from solid plastic, is quite heavy and expensive.

Summary of the Invention

This invention is directed to the provision of an improved pallet structure that is lightweight, strong, durable and maintenance free, relatively inexpensive, and provides all-weather performance.
This invention is further directed to the provision of an improved pallet structure that is of modular construction wherein pallet platforms and leg units, each of a standard design, are formed separately and may be assembled to form pallets of a wide variety of configurations.
The plastic pallet of the invention comprises a platform structure having a generally planar underface and a plurality of individual legs extending downwardly from the underface in spaced relation. Each leg comprises a modular plastic structure of box configuration including a generally planar upper portion, a generally planar lower portion, and an annular portion interconnecting the upper and lower portions and maintaining the upper and lower portions in spaced relation. The legs are secured to the platform structure by fusing the upper portions of each leg to the underface of the platform structure with the legs in spaced relation. This modular construction allows the structural requirements of the legs to be individually addressed so as to facilitate the provision of an extremely strong and yet relatively inexpensive pallet structure.
According to a further feature of the invention, the annular portion of each leg comprises an outer skirt portion and each leg further includes a column structure positioned within the skirt portion and interconnecting the upper and lower planar portions. This arrangement provides an extremely strong leg structure and further provides a leg structure that will survive even total decimation of the outer skirt portion of the leg by a forklift truck or the like.
According to a further feature of the invention, each leg is formed of first and second sheets of plastic material fused together to provide the box configuration. This specific construction allows the legs to be quickly and inexpensively manufactured.
According to a further feature of the invention, the first plastic sheet is molded to define a first planar body main portion and a first annular skirt portion extending therefrom to define a first annular surface, and the second plastic sheet defines a second planar main body portion and a second annular surface corresponding in size and configuration to the first annular surface. The first and second sheets are fused together at their respective annular surfaces to form a hollow box-like leg having first and second main body portions spaced apart by the annular skirt portion. The resulting leg is secured to the platform structure by fusing one of the main body portions to the underside of the platform structure. The pallet thus formed has legs that may be economically produced by a vacuum forming process separately from the platform and thereafter fused to the platform in the number, the configuration and the spacing required to give the pallet sufficient strength for a particular pallet application.
According to a further feature of the invention, the first plastic sheet comprises an upper sheet with the first annular skirt portion extending downwardly from the first main body portion such that the first annular surface faces downwardly, and the second plastic sheet comprises a lower sheet and further includes a second annular skirt extending upwardly from the second main body portion such that the second annular surface is defined by an upwardly facing upper annular edge of the second skirt portion. This construction allows the upper and lower sheets to be formed as two identical pieces, with attendant benefits in manufacturing economy.
According to a further feature of the invention, the pallet further includes a generally planar base structure, an upper surface of which is fused to the main body portion of the lower sheet of the leg so that the leg, in coaction with other legs, separates the platform structure and base structure to define passageways therebetween for the entry of material handling equipment. The pallet thus produced is of the double faced type in which the base structure, rather than the legs themselves, contacts any supporting surface on which the pallet rests.
According to yet another feature of the invention pallet, a leg comprises an upper plastic sheet having an upper face secured to the underside of the pallet platform panel and a hollow upper boss which opens in the upper face and extends downwardly therefrom, and a lower plastic sheet having a hollow lower boss which opens in a lower face of the lower sheet and extends upwardly therefrom. The upper and lower bosses contact one another and are fused together to connect the upper and lower sheets. The leg formed in this manner is well suited to a vacuum molding production process, and the coacting bosses give the leg significant strength.
According to a further feature of the invention, the upper boss includes an annular side wall and a bottom wall, and the lower boss includes an annular side wall, with the side walls being of generally equal height. In connecting the upper and lower sheets, the side walls of the upper and lower bosses are fused together, the bottom wall of the upper boss is fused to an upper surface of the lower sheet, and the top wall of the lower boss is fused to a lower surface of the upper sheet. By fusing the upper and lower sheets together in this manner, the bosses coact to provide a central column structure which contributes greatly to the overall crush-resistance of the leg structure.
According to yet another feature of the invention, the upper sheet further includes an upper annular downwardly extending skirt in surrounding relation to the upper boss and the lower sheet further includes a lower annular upwardly extending skirt in surrounding relation to the lower boss, with a lower annular edge of the upper skirt fused to an upper annular edge of the lower skirt. This arrangement creates a box-like leg structure with the annular skirts and bosses connecting the upper and lower faces of the leg and thereby providing the leg with superior rigidity and crush resistance.
According to a further feature of the invention, the side walls of the upper and lower bosses taper in a complementary fashion to define an angled interface therebetween and the side walls are fused together at this angled interface. The tapered configuration of the boss side walls provides improvement in both manufacturability of the legs and in the strength thereof.
According to still another feature of the invention, the side walls of the upper and lower bosses have grooves running along the length of the angled interface such that when the side walls are fused together, the grooves are aligned to form a hollow stiffening column which runs between the upper and lower surfaces of the leg along the angled interface at the epicenter of the leg structure. This stiffening column provides a further significant increase in the crush resistance of the leg with only a small increase in the amount of plastic material required to manufacture the leg.
According to a further feature of the invention, a plurality of spaced downwardly opening pockets are provided in a lower face of the platform structure; each leg has a hollow closed box configuration and includes an upper wall structure; and the upper wall structure of each leg is fitted into a respective pocket and is fused to the plastic material of the platform structure defining the pocket. This arrangement provides a pallet which may be inexpensively produced and which allows a range of pallet sizes to be produced from a single platform structure simply by varying the characteristics of the legs that are fused to the platform structure.
According to a further feature of the invention, the upper wall structure of each leg has a size and shape corresponding to the size and shape of the respective pocket so as to fit snugly within that pocket. This arrangement provides a positive securement as between the platform structure and the leg and optimizes the shear strength of the pallet.
According to a further feature of the invention, the platform structure comprises a twin sheet structure formed of upper and lower thermoformed plastic sheets selectively fused together and the pockets are formed in the lower plastic sheet. This specific construction provides a ready and convenient means of providing the pockets for receipt of the legs.
According to a further feature of the invention, each leg is formed from first and second thermoformed plastic parts fused together. This arrangement provides a ready and inexpensive means of providing the legs.
According to a further feature of the invention, the plastic parts of each leg are fused together along a seam line lying in a generally vertical plan. This arrangement facilitates ready assembly of the legs and provides excellent leg strength.
According to a further feature of the invention, the pallet further includes a base structure; a plurality of upwardly spaced opening pockets are provided in an upper face of the base structure; and each leg includes a lower wall structure having a size and shape corresponding to the size and shape of a respective base structure pocket, is received in that pocket, and is fused to the plastic material of the base structure defining that pocket. This arrangement provides a convenient and inexpensive means of providing a double face pallet having excellent strength characteristics and excellent versatility.
According to a further feature of the invention, the base structure comprises a twin sheet structure formed of upper and lower thermoformed sheets selectively fused together and the upwardly opening pockets are formed in the upper plastic sheet. This arrangement provides a ready and efficient means of providing the upwardly opening pockets.
The invention further provides an improved double face plastic pallet including a generally planar platform structure defining an upper face providing an article support surface and an underface; a generally planar base structure defining a lower pallet support face and an upper face; and a plurality of hollow legs of closed box configuration positioned between the platform and base structures and each including an upper wall structure fused to the underface of the platform structure and a lower wall structure fused to the upper face of the base structure. This arrangement provides a double face plastic pallet providing high strength, inexpensive manufacture, and versatility.

Brief Description of the Drawings

FIGURE 1 is a perspective view of a double faced pallet according to a first embodiment of the invention;
FIGURE 1A is a perspective view of a single faced pallet according to the first embodiment of the invention;
FIGURE 2 is a side view of the pallet of FIGURE 1;
FIGURE 3 is a perspective view of a leg used in the invention pallet;
FIGURE 4 is a cross-sectional view taken on line 4-4 of FIGURE 3;
FIGURE 5 is a cross-sectional view taken on line 5-5 of FIGURE 3;
FIGURE 6 is a cross-sectional view taken on line 6-6 of FIGURE 3;
FIGURES 7A and 7B are perspective views of upper and lower halves, respectively, utilized in constructing the pallet leg;
FIGURE 8 is a perspective view of a twin sheet plastic pallet according to a second embodiment of the invention including a base structure, a platform structure, and a plurality of legs interposed between the base and platform structures;
FIGURE 9 is a fragmentary cross-sectional view taken on line 9-9 of Figure 8;
FIGURE 10 is a plan view of the pallet with the platform structure removed;
FIGURE 11 is a plan view of the base structure;
FIGURE 12 is a bottom plan view of the platform structure;
FIGURE 13 is a perspective view showing the base structure and some of the legs;
FIGURE 14 is a fragmentary bottom plan view of the platform structure;
FIGURES 15 and 16 are top views of legs employed in the invention pallet;
FIGURE 17 is a bottom fragmentary perspective view of the platform structure;
FIGURE 18 is a composite bottom view of the legs;
FIGURE 19 is a side elevational view showing the utilization of the invention pallet in a shrink-wrapping methodology;
FIGURE 20 is a detail view taken within circle 20 of Figure 19;
FIGURE 21 is a fragmentary detail view showing a modified form of the second embodiment pallet; and
FIGURE 22 is a plan view of the modified pallet of Figure 21.

Detailed Description of the Preferred Embodiments

A first embodiment of the invention pallet is shown in Figures 1-7; a second embodiment of the invention pallet is shown in Figures 8-20; and a modified form of the second embodiment pallet is shown in Figures 21 and 22.
As seen in Figure 1, the pallet 10 of the first embodiment of the invention is comprised essentially of an upper platform structure 12, a lower base structure 14, and legs 16 located between and secured firmly to platform structure 12 and base structure 14. Pallet 10 may be of any desired shape and size with any desired number of legs 16. A representative pallet as used in industry is rectangular and includes nine legs, one leg positioned at each corner of pallet 10, one midway along each of the four sides, and one in the center of pallet 10. Legs 16 are spaced from one another to define forklift entry passages 18 passing through pallet 10. Passages 18 are accessible from all four sides of pallet 10, and are of sufficient size to receive the tines of a forklift (not shown) or a similar material handling device for lifting and moving pallet 10.
An alternative form of the pallet of the present invention is depicted in Figure 1A and is identical to the above-described form in all respects except that pallet 10' is of the single faced type and as such does not include a base structure. Legs 16' are fixed to the bottom of platform structure 12' and rest directly upon a supporting surface. Note that, as in the first described form, the spaces between legs 16' define forklift entry passages 18' accessible from all four sides of pallet 10'.
As depicted in Figures 3-7, each leg 16 is formed from an upper plastic sheet 20 and a lower plastic sheet 120 which are bonded together to form a box-like structure. Sheets 20, 120 are formed in coaction with vacuum forming molds (not shown) as described in U.S. Patent No. 5,401,347. The forming process involves heating sheets 20, 120, which as raw stock are flat, and using vacuum pressure to bring each sheet into conformance with respective molds. While sheets 20, 120 are still in a heated flowable state the molds are brought together to place sheets 20, 120 in contact and fuse them together along selected surfaces.
It should be noted that in the embodiment of leg 16 described and depicted herein, upper sheet 20 and lower sheet 120 are identically molded pieces, and as such the distinction between sheets 20 and 120 being upper and lower respectively is purely arbitrary and used herein for descriptive purposes only. To emphasize this fact, the reference numerals assigned to the components making up lower sheet 120 differ from those assigned to the components of upper sheet 20 only in their leading digit. It should also be noted that, unless otherwise stated, any description of a feature of upper sheet 20 applies also to the corresponding feature of lower sheet 120.
As best seen in Figure 7A, upper sheet 20 includes a generally planar top panel 22 and a skirt 24 extending downwardly from the periphery thereof. The vertical dimension of skirt 24 varies around the periphery so that the lower, distal edge 24A of skirt 24 has a stepped or notched configuration. The distal edge 24A is flared outward to form a flange 26, the bottom of which defines an annular bonding surface 27 running around the entire periphery of skirt 24.
To add greater stiffness to the resulting leg structure, skirt 24 is formed with a plurality of vertically extending channels 28 which project inward from the outer surface of the skirt 24.
A hollow boss 30 extends downwardly from top panel 22 and is generally frustoconical in shape, having an annular side wall 32 and a substantially planar bottom wall 34. Boss 30 is offset toward one end of upper sheet 20 and a flat 36 is formed on the side of boss 30 facing toward the end of upper sheet 20 opposite the direction of the offset. Flat 36 runs straight down the frustrum of boss 30, and a groove 38 passes along the center line of flat 36, projecting toward the inner or concave side of boss 30.
As noted, lower sheet 120 is identical to upper sheet 20 but is oriented in an inverted position so that skirt 124 extends upwardly from the periphery of a planar bottom panel 122 and flares outward at distal edge 124A to form a flange 126, the bottom of which defines an annular bonding surface 127, and boss 130 extends upwardly from bottom panel 122 in staggered, meshing relation to downwardly extending boss 30.
In the final step of the leg forming process described above, upper sheet 20 and lower sheet 120 are aligned in the mutually opposed relationship depicted in Figures 7A and 7B and brought together so that the notched lower and upper edges of skirts 24, 124 fit together in a meshing relationship, with bonding surfaces 27, 127 in registry and fused to one another around substantially the entire circumference of flanges 26, 126. Bosses 30, 130 also fit meshingly together, with flats 36, 136 in planar contact with one another and fused together along the angled interface therebetween. When so mated, grooves 38, 138 are aligned with one another to define a hollow stiffening column 40, best seen in Figures 4 and 6, running along the angled interface.
Bosses 30, 130 are preferably of equal height, that height being equal to the combined height of skirts 24 and 124 so as to completely span the distance between top panel 22 and bottom panel 122. In this configuration, when upper and lower sheets 20, 120 are joined to fuse skirts 24, 124, bottom wall 34 of boss 30 is placed in contact with and fused to the upper surface of bottom panel 122 and the top wall 134 of boss 130 is likewise placed in contact with and fused to the lower surface of top panel 22.
The plastic leg 16 thus formed includes an upper face defined by the top panel 22 of upper sheet 20, a lower face defined by the bottom panel 122 of lower sheet 120, an annular skirt or shell defined by the fused together skirts 24, 124, a central pillar or column structure defined by the fused together bosses 30, 130 and coacting with the annular skirt to define an annular space therebetween, and a further stiffening column structure 40 at the epicenter of the leg.
To form a single faced pallet 10' utilizing the invention legs 16, the attachment surfaces formed by the upper faces of the top panels 22 are suitably fused to a plurality of downwardly facing attachment surfaces define on the lower surface of platform structure 12' at spaced locations as seen in Figure 1A. To form a doubled faced pallet 10, the lower surfaces of the bottom panels 122 are suitably fused to an upper surface of platform structure 14 at spaced locations as seen in Figure 1.
Whereas the particular plastic material utilized to form the invention pallet is not critical, it has been found that excellent results may be obtained by the use of a high density polyethylene having a density of approximately 0.950 grams per cubic centimeter.
The pallet 210 of the second embodiment of the invention is a double faced pallet of twin sheet construction. Specifically, pallet 210 includes an upper platform structure 212, a lower base structure 214, and a plurality of modular legs 215, 216, 217, and 218 interconnecting the platform structure and the base structure. Platform structure 212, base structure 214, and legs 215-218 are formed of organic polymeric material such as polyethylene. Platform structure 212 and base structure 214 preferably are of a twin sheet construction employing two plastic sheets which are vacuum formed and fused or knitted together at various points to add structural rigidity.
Platform structure 212 is formed of an upper plastic sheet 219 and a lower plastic sheet 220. Upper sheet 219 has a series of rows of downwardly extending bosses 219a and lower sheet 220 has a series of rows of upwardly extending bosses 220a. The downwardly extending and upwardly extending rows of bosses are arranged in interdigitated fashion and fused together at the interface of the interdigitated bosses to form rows of boss columns. 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 bosses of the upper and lower sheets are fused together to form the column structures are shown in U.S. patent Nos. 5,390,467, 5,401,347 and 5,470,641 and in U.S. Patent application Serial No. 08/426,876 filed April 24, 1995.
The peripheral edges 219b and 220b of the upper and lower sheets are fused together to define a downwardly extending peripheral lip 222 defining a downwardly opening groove 224 extending totally around the periphery of the platform structure. Lip 222 is formed by bringing peripheral edge portion 220b of the lower sheet upwardly into proximity with the peripheral edge portion 219b of the lower sheet and bending the sheet edge portions downwardly together. Lip 222 is constituted by a downwardly extending outer edge portion 220c of lower sheet 220 and a downwardly extending outer edge portion 219c of upper sheet 219. Edge portions 219c, 220c are selectively spaced apart proximate their upper regions to define circumferentially spaced voids 226 therebetween for structural rigidity and are continuously fused together adjacent their lower regions at an interface 228.
Upper and lower sheets 219, 220 are also configured at circumferentially spaced locations around the periphery of the platform structure to define downwardly opening recesses or pockets 228 to receive respective legs 215, 216, 217, and 218. Specifically, corner pockets 228a are defined at each corner of the platform structure; longitudinal side pockets 228b are defined along each longitudinal side edge 212a of the platform structure; lateral side pockets 228c are defined along each lateral side edge 212b of the platform structure; and a central pocket 228d is defined in a central portion of the platform structure.
Base structure 214 is formed of upper and lower plastic sheets 230, 232 respectively defining downwardly extending rows of bosses 230a and upwardly extending rows of bosses 232a which are interdigitally arranged and fused together at their interdigitated interfaces to form rows of columns similar to the rows of columns in the platform structure but arranged in rows extending generally parallel to the longitudinal and transverse side edges 214a and 214b of the base structure. Base structure 214 may comprise a single, continuous structure or may, as shown, include cutouts 214c to give the base structure an open grate configuration.
Upper sheet 230 is further configured to define upwardly opening recesses or pockets 234 corresponding in number and circumferential disposition to the downwardly opening pockets 228 in the platform structure and arranged to receive the lower ends of legs 215-218. Specifically, corner pockets 234a are defined at each corner of the base structure; longitudinal side pockets 234b are defined along each longitudinal side edge 214a of the base structure; lateral side pockets 234c are defined along each lateral side edge 214b of the base structure; and a central pocket 234d is defined in a central region of the base structure.
Legs 215-218 are of a modular closed box construction and each includes a left half 215a, 216a, 217a, and 218a and a right half 215b, 216b, 217b and 218b fused together along a respective fuse or seam line 215c, 216c, 217c, and 218c. The lower end of each leg 215 is configured to nest or seat within a respective base structure pocket 234a; the upper end of each leg 215 is configured to nest or seat within a respective platform structure corner pocket 228a; the lower end of each leg 216 is configured to nest within a respective base structure lateral side edge pocket 234c; the upper end of each leg 216 is configured to nest within a respective platform structure lateral side pocket 228c; the lower end of each leg 217 is configured to nest within a respective base structure lateral side pocket 234b; the upper end of each leg 217 is configured to nest within a respective platform structure lateral side pocket 228b; and the upper and lower ends of leg 218 are configured to seat respectively in pockets 228d, 234d.
The outboard wall 216f of each leg 216 is stepped inwardly at 216g to define a recessed upper wall portion 216h which is stepped inwardly with respect to lip 222 so as not to encroach upon groove 224 and not to interfere with access to groove 224. The outboard wall 217f of each leg 217 is stepped inwardly at 217g to define a recessed upper wall portion 217h which is stepped inwardly with respect to lip 222 so as not to encroach upon groove 224 and so as not to interfere with access to groove 224. The longitudinal outboard face 215f of each leg 215 is stepped inwardly at 215g to define an upper recessed wall portion 215h spaced inwardly from lip 222 so as not to encroach on groove 224 and the transverse outboard face 215i of each leg 215 is stepped inwardly at 215j to define a recessed upper wall portion 215k spaced inwardly with respect to lip 222 so as not to encroach upon groove 224. Central leg 218 extends between central pockets 228d and 38d to support the central region of the pallet. The upper ends of the legs 215, 216, 217, and 218 are fused in position within the respective upper pockets 228 and the lower ends of the legs 215, 216, 217, and 218 are fused in position in the respective lower pockets 234. The inwardly stepped configuration of the legs will be seen to avoid encroachment of the upper ends of the legs with groove 224 so as to not impede access to the groove 224 at any point around the circumference of the platform structure.
The pockets 234a-234d in the upper face of base structure 214 have an essentially identical rectangular bevelled configuration in the manner of a truncated pyramid, and each of the legs 215-218 has a rectangular bevelled footprint of a truncated pyramidal configuration sized to nest snugly in a respective pocket 234. In addition, the outer legs 215-217 have ledge structures to enable the outboard faces of the legs to be positioned essentially flush with the outer perimeter of the base structure. Specifically, legs 217 have ledges 217j adapted to rest on the upper face of sheet 230 outboard of the longitudinal edge of the respective pocket 234b; legs 216 have ledges 216j adapted to rest on the upper face of sheet 230 outboard of the transverse edge of a respective pocket 234c; and corner legs 215 have ledges 215j and 215k adapted to rest on the upper face of sheet 230 outboard of the longitudinal and transverse edges of the respective pocket 234a.
The upper ends of legs 215-218 have varying profiles and the respective platform structure pockets 228a-28d have shapes and configurations adapted to individually and firmly accommodate the upper ends of the respective legs.
Specifically, the upper end 218d of central leg 218 has a simple truncated pyramidal configuration and seats in a central pocket 228d of corresponding size and configuration; the upper end of each transverse side leg 216 seats in a respective pocket 228c and includes large area bevelled surfaces 216l, 216m, and 216n seating against large area bevelled pocket surfaces 220d, 220e, and 220f defined by the platform structure lower sheet 220 and further includes a small area bevelled surface 216p seating against a small area bevelled surface 220j defined on the inboard face of a ridge 220h formed in platform structure lower sheet 220; the upper end of each longitudinal side leg 217 seats in a respective pocket 228b and includes large area bevelled surfaces 217l, 217m, and 217n seated against large area bevelled pocket surfaces 220k, 2201, and 220m and further includes a small area bevelled surface 217p seating against a small area bevelled surface 220n defined on the inboard face of a ridge 220p formed in platform structure lower sheet 220; and the upper end of each corner leg 215 seats in a respective pocket 228a and includes large area bevelled surfaces 215l and 215m seating against large area bevelled pocket surfaces 220q and 220r and further includes small area bevelled surfaces 215n and 215p seating against small area bevelled surfaces 220s and 220t defined on the inboard faces of a right angle ridge 220u formed in platform structure lower sheet 220.
It will be understood that, in the completed pallet, the upper and lower ends of the legs are positioned in the respective pockets in the platform structure and in the base structure and the plastic material of the legs is fused to the plastic material of the platform structure and base structure at the interfaces between the various surfaces on the upper and lower ends of the legs and the various surfaces defining the pockets.
Figures 12 and 13 illustrate the manner in which the invention pallet is utilized to facilitate the shrink-wrapping of an article such as the article 238 positioned on the upper face of the platform structure. Specifically, article 238 is shrink-wrapped in position on the platform structure 212 utilizing a plastic film sheet 240 of bag configuration which is positioned in covering relation over the article whereafter its lower peripheral edge 240a is tucked upwardly into the downwardly opening groove 224 so as to firmly secure the lower edge 240a of the film sheet to the platform structure and preclude inadvertent separation of the film sheet from the platform structure and inadvertent exposure of the article. If desired, and as shown in Figure 20, a flat sanitizing film sheet 241 may be positioned over the platform structure prior to placement of the article 238 on the platform structure, whereafter article 238 may be placed on the platform structure over film sheet 241, bag sheet 240 may be fitted over the article, and the lower peripheral edges 240a and 241a of the bag film and the flat film may be tucked upwardly together into the downwardly opening groove 224.
In the modified form of the pallet seen in Figures 21 and 22, the upper and lower sheets 219' and 220' of the platform structure 212' are configured to define laterally extending cavities 242 positioned inboard of the leg pockets 228' and extending parallel to the platform structure lateral side edges 212b', and a tubular steel beam 248 is positioned in each cavity 242 to add structural rigidity to the platform structure and to the pallet. Preferably the upper and lower sheets are further configured to provide longitudinal cavities 250 extending parallel to the platform structure longitudinal side edges 212a' inboard of leg pockets 228' and longitudinally extending tubular steel beams 252 are positioned in the cavities 250 so as to coact with the beams 248 to define a rectangular beam structure extending around the perimeter of the platform structure inboard of the legs.
The described pallet structures provide an inexpensive pallet construction; allow a single platform structure and/or base structure to be utilized with various size legs to provide a range of pallet sizes; provide excellent compressive strength by virtue of the closed box configuration of the legs; provide excellent shear strength in both primary directions by virtue of the pocket side walls capturing the upper and lower ends of the legs; and provide an unimpeded downwardly opening groove around the entire perimeter of the platform structure to facilitate shrink wrapping of articles on the pallet.
Whereas preferred embodiments of the invention have been illustrated and described in detail, it will be apparent that various changes may be made in the disclosed embodiments without departing from the scope or spirit of the invention.

Claims

A plastic pallet (10, 10', 210) comprising a generally planar plastic platform structure (12, 12', 212, 212') having an underface and a plurality of individual legs (16, 16', 215-218) extending downwardly from the underface in spaced relation, the legs (16, 16', 215-218) being fixedly secured to the underface of the platform structure (12, 12', 212, 212'), characterized in that :

a plurality of spaced downwardly facing attachment surfaces are defined on the underface of the platform structure (12, 12', 212, 212');

each leg (16, 16', 215-218) comprises a modular plastic structure of hollow closed box configuration including an upper portion defining an upwardly facing attachment surface (22, 2151-p, 2161-p, 2171-p, 218d), a lower portion positioned in underlying relation to the upper portion, and an annular portion interconnecting the upper and lower portions to complete the hollow closed box leg configuration; and

the legs (16, 16', 215-218) are fixedly secured 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 leg (16, 16', 215-218) adjacent a respective downwardly facing attachment surface on the underface of the platform structure (12, 12', 212, 212') and fusing the upper portion of each leg (16, 16', 215-218) to the underface of the platform structure (12, 12', 212, 212') at the interface of the attachment surfaces.
A plastic pallet (10, 10') according to claim 1, characterized in that the annular portion of each leg (16, 16') comprises an outer skirt portion (24, 124); and in that each leg (16, 16') further includes a central inner column (30, 40, 130) positioned within the outer skirt portion (24, 124) and interconnecting the upper (22) and lower (122) portions.
A plastic pallet (10, 10', 210) according to either claim 1 or 2, characterized in that each leg (16, 16', 215-218) is formed of first (20, 215a, 216a, 217a, 218a) and second (120, 215b, 216b, 217b, 218b) sheets of plastic material fused together to provide the hollow box configuration.
A plastic pallet (210) according to claim 3, characterized in that the plastic parts of each leg (215-218) are fused together along a seam line (215c, 216c, 217c, 218c) lying in a generally vertical plane.
A plastic pallet (10, 10') according to claim 3, characterized in that :

the first molded plastic sheet (20) defines a first planar main body portion (22) and an annular skirt portion (24) extending from the main body portion (22) defining a first annular surface (24) ;

in that the second plastic sheet (120) defines a second planar main body portion (122) and a second annular surface (124) corresponding in size and configuration to the first annular surface (24);

and in that the first (20) and second (120) sheets are fused together at their respective annular surfaces (24, 124).
A plastic pallet (10, 10') according to claim 5 characterized in that :

the first upper plastic sheet (20) includes an upper boss (30) opening in the upper surface (22) of the main body portion (22) and an annular side wall (32) extending downwardly from the main body portion (22) ;

in that the second lower plastic sheet (120) includes a lower boss (130) opening in the lower surface (122) of the main body portion (122) and an annular side wall portion (132) extending upwardly from the main body portion ;

and in that the annular side wall portion (132) of the lower boss (130) is fused to the annular side wall portion (32) of the upper boss (30).
A plastic pallet (210) according to any one of claims 1 to 6, characterized in that a plurality of spaced downwardly opening pockets (228, 228') are provided in a lower face of the platform structure (212, 212'), the upper wall structure (2151-p, 2161-p, 2171-p, 218d) of each leg (215-218) being fitted into a respective pocket (228, 228') and fused to the plastic material of the platform structure (212, 212') defining that pocket (228, 228').
A plastic pallet (210) according to claim 7, characterized in that the upper wall structure (2151-p, 2161-p, 2171-p, 218d) of each leg (215-218) has a size and shape corresponding to the size and shape of the respective pocket (228, 228') so as to nest snugly within that pocket (228, 228').
A plastic pallet (210) according to any one of claims 1 to 8, characterized in that the platform structure (212, 212') comprises a twin sheet structure formed of upper (219, 219') and lower (220, 220') thermoformed plastic sheets selectively fused together.
A plastic pallet (210) according to claim 9 when depending on either claim 7 or 8, characterized in that the pockets (228, 228') of the platform structure (212, 212') are formed in the lower plastic sheet (220, 220').
A plastic pallet (210) according to either claim 9 or 10, characterized in that :

the upper (219, 219') and lower (220, 220') sheets are maintained in vertically spaced parallel relation in a central portion of the platform structure (212, 212') ;

and in that the peripheral edges (219b, 220b) of the upper (219, 219') and lower (220, 220') sheets are fused together to define a downwardly extending peripheral lip (222) defining a downwardly opening groove (224) proximate the periphery of the platform structure (212, 212').
A plastic pallet (210) according to claim 11, characterized in that the lip (222) is formed by bringing the peripheral edge portion (220b) of the lower sheet (220, 220') upwardly into proximity with the peripheral edge portion (219b) of the upper sheet (219, 219') and bending the sheet edge portions downwardly together.
A plastic pallet (210) according to any one of claim 1 to 12, characterized in that the legs (215-217) spaced about the periphery of the platform structure (212, 212') include an outboard wall structure (215f, 215i, 216f, 217f) having a lower portion and an upper portion (215h, 215k, 216h, 217h) recessed inboard with respect to the lower portion.
A plastic pallet (210) according to claim 13, characterized in that the lower portion of the wall structure (215f, 215i, 216f, 217f) of each leg (215-217) is positioned approximately flush with the outer perimeter of the platform structure (212, 212').
A plastic pallet (210) according to either claim 13 or 14, characterized in that :

the platform structure (212, 212') defines a peripheral downwardly extending lip (222) defining a downwardly opening groove (224) extending around the perimeter of the platform structure (212, 212') ;

and in that the upper portion of the wall structure (215h, 215k, 216h, 217h) of each leg (215-217) is spaced inboard from the lip (222) so as not to encroach upon the groove (224).
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 of the legs (215-217) and in outwardly spaced relation to the outboard surfaces (215f, 215i, 216f, 217f) of the legs (215-217).
A plastic pallet (10, 210) according to any one of claim 1 to 16 wherein :

the pallet (10, 210) further includes a generally planar base structure (14, 214) ;

and in that a lower surface of the leg (16, 215-218) is fused to an upper surface of the base structure (14, 214) so that the leg (16, 215-218), in coaction with other legs (16, 215-218), separates the platform structure (12, 212) and base structure (14, 214) to define passageways (18) therebetween for the entry of material handling equipment.
A plastic pallet (210) according to claim 17 when depending on any one of claims 13 to 16, characterized in that :

the base structure (214) has a size and configuration approximating the size and configuration of the platform structure (212, 212') ;

and in that lower portions of the outboard wall structure (215f, 215i, 216f, 217f) of the legs (215-217) are positioned approximately flush with the outer perimeter of the base structure (214).
A plastic pallet (210) according to either claim 17 or 18, characterized in that :

a plurality of spaced upwardly opening pockets (234) are provided in an upper face of the base structure (214) ;

and in that each leg (215-218) includes a lower wall structure having a size and shape corresponding to the size and shape of a respective base structure pocket (234), is received in that pocket (234), and is fused to the plastic material of the base structure (214) defining that pocket (234).
A plastic pallet (210) according to any one of claims 17 to 19, characterized in that the base structure (214) comprises a twin sheet structure formed of upper (230) and lower (232) thermoformed sheets selectively fused together.
A plastic pallet (210) according to claim 20 when depending on claim 19, characterized in that the upwardly opening pockets (234) of the base structure (214) are formed in the upper plastic sheet (230).
A method of forming a plastic pallet (210) of the type including a platform structure (212, 212') and a plurality of circumferenrially spaced legs (215-217) extending downwardly from the platform structure (212, 212'), the method comprising :

thermoforming upper (219, 219') and lower (220, 220') plastic sheets;

selectively fusing central main body portions of the sheets (219, 219', 220, 220') together to form a central platform section (212, 212') for the pallet (210); and

fusing peripheral edge portions (219b, 220b) of the sheets (219, 219', 220, 220') together to form a downwardly peripheral lip (222) defining a downwardly extending opening groove (224) proximate the periphery of the platform structure (221, 212').
A method of packaging an article (238) comprising :

forming a pallet (210) by thermoforming upper (219, 219') and lower (220, 220') plastic sheets, selectively fusing central main body portions of the sheets (219, 219', 220, 220') together to form a platform structure (212, 212'), fusing peripheral edge portions (219b, 220b) of the sheets (219, 219', 220, 220') together to form a downwardly extending peripheral lip (222) defining a downwardly opening groove (224) proximate the periphery of the platform structure (212, 212'), and providing a plurality of circumferentially spaced legs (215-217) extending downwardly from the platform structure (212, 212');

placing the article (238) on the platform structure (212, 212'); and

shrink-wrapping the article (238) on the platform structure (212, 212'), utilizing a plastic film sheet (240), by placing the film sheet (240) in covering relation over the article (238) and tucking a lower edge (240a) of the film sheet (240) upwardly into the downwardly opening groove (224).