AU707915B2

AU707915B2 - Lightweight plastic pallet

Info

Publication number: AU707915B2
Application number: AU19482/97A
Authority: AU
Inventors: Helge Grande; Oddbjorn Gronnevik; Rolf Kotterheinrich
Original assignee: Borealis AS
Current assignee: Borealis AS
Priority date: 1996-01-11
Filing date: 1997-01-10
Publication date: 1999-07-22
Anticipated expiration: 2017-01-10
Also published as: NO960910L; AU1948297A; EP0876284A1; WO1997025250A1; CA2242721A1; CN1208386A; NO960910D0

Description

WO 97/25250 PCT/N097/00009 1 LIGHTWEIGHT PLASTIC PALLET FIELD OF INVENTION This invention relates to a lightweight plastic pallet, in particular a pallet having integrated sheet-like pallet legs or runners.

PRIOR ART Pallets are included as a part of the goods that are to be transported and/or stored on them, and therefore it is important for the pallet to be lightweight, but strong and rigid at the same time. Plastic pallets have the advantages over wooden pallets that they are lightweight, that they do not absorb moisture, and that they can be cleaned/disinfected, is which is decisive in fields where hygiene is important, e.g., in the food industry.

European Patent No. EP-0 400 640 discloses a plastic pallet that is assembled from a top deck and a bottom deck with runners, or from a deck and runners. The components are formed with legs that are inserted into one another during assembly. Mechanical fasteners in the form of metal plates having die-cut notches, nails or the like can be employed to ensure that the components hold together.

Swiss Patent No. CH-685549 A5 discloses a plastic pallet that is injection molded in two components, namely, a top deck and a bottom deck comprising posts and runners. The top deck and the bottom deck, both having reinforcing ribs, are butt-welded together so that the side edges and ribs are welded together against one another. Directly within all four side edges and along the center line longitudinally there are in the ribs semicircular openings into which steel pipes or flat rods can be jammed for mechanical reinforcement of the pallet. The plastic pallet is preferably fabricated from polyethylene.

Swedish Patent SE 501,539 relates to an injection molded pallet runner, preferably comprising two or three separate, hollow, closed channels along its entire length. The runner is lightweight, while rigid. It can be fastened by its top to suitable posts, which again are fastened to the bottom WO 97/25250 PCT/N097/00009 2 of a pallet deck.

International Application WO 93/18906 relates to a blow-mold device for producing one-piece, externally smooth, double-walled plastic plates with internal spaces formed during blow-molding. The high bending resistance of the manufactured plate makes it suitable for making plastic pallets.

Prior art plastic pallets are fabricated by injection molding of components that are then joined together. The components will typically have reinforcing ribs at required i0 places in order to attain a lightweight rigid construction. In the injection molding of such large objects, very large and expensive injection molding tools are used that require large injection molding machines having great clamping forces. Consequently, it would be desirable to be able to make plastic pallets by a simpler and more economical method. A possible means of attaining this object is to thermoform the pallet from an extruded plastic sheet or from a parison, like the blow molding of large objects such as barrels, gasoline tanks, etc. To attain a lightweight and rigid construction it is often desirable to employ a coextruded multilayer structure where one of the layers is at least partially foamed. For instance, US Patent No. 4,874,649 discloses a method for the blow molding of a coextruded parison comprising at least two layers, one of which, perhaps more, is at least partially foamed.

Applicant's contemporary Norwegian patent application NO-A-960128, the disclosure of which is hereby incorporated by reference, relates to a pallet manufactured by thermoforming a parison of the type disclosed in US Patent 4,874,649. This parison is formed into a pallet deck and spacer and runner components, which are assembled in a subsequent separate operation. Thus, a lightweight, however strong and rigid construction, is attained. The pallet may be reinforced by introducing rigid sections into cavities formed between the pallet deck and spacers.

For many purposes especially lightweight pallets, often of a smaller size than standard normal sized pallets, are desired. It has now been found that it is possible to fabricate a lightweight pallet having pallet legs and runners of WO 97/25250 PCT/N097/00009 3 a simplified construction compared with the pallet disclosed in Applicant's above mentioned patent application.

The pallet's smooth and even surface makes it very simple and easy to clean and disinfect. The pallet is therefore especially well suited for use in the food industry and allied industries. The pallet has a great strength/weight ratio because of its design. As a result, it is well suited for purposes where low weight is important, e.g. in air freight, and where manual handling of pallets occur frequently.

SUMMARY OF THE INVENTION The present invention provides a pallet made of a thermoplastic material, the pallet comprising a deck and legs disposed underneath the deck. The pallet deck has top and bottom surfaces and a set of opposed longitudinal sides and a set of opposed transverse sides, and sheet legs integrated with the deck and disposed along at least one of said set of sides of the pallet deck. The pallet is fabricated by thermoforming an extruded thermoplastic parison having a monolayer or multilayer structure into one predominantly flat article having a set of opposed longitudinal sides and a set of opposed transverse sides, and then bending at least one of said set of sides of the article into a position perpendicular to the main part thereof to form the sheet legs, and affixing the sheet legs into said position.

The invention also provides a pallet, made of a thermoplastic material, comprising a deck and at least two runners disposed underneath said deck. The pallet deck, having top and bottom surfaces, and the runners, being in the shape of a cross member having a upward-facing runner post in each end thereof, are fastened by a top surface of said runner posts to the bottom of the pallet deck. The pallet deck is produced by thermoforming an extruded plastic parison having a monolayer or multilayer structure into one predominantly flat article. The runners are produced separately by thermoforming an extruded parison identical to the one used in the production of said pallet deck into a predominantly flat article and bending the end parts of this article into a position perpen- P:\OPER\AXD\19482-9725 5/5/99 -4dicular to the main part thereof to obtain the runners having upward-facing posts.

The invention further provides a method of manufacturing a plastic pallet comprising a deck and legs disposed underneath said deck for supporting said deck, the method comprising the steps of: producing in a mold and extruded parison, while hot, into a prdominantly flat article comprising a pallet deck, said pallet deck comprising top and bottom surfaces, substantially parallel, opposed longitudinal sides, and substantially parallel, opposed transverse sides, said predominantly flat article further comprising a plurality of sheet legs, one said sheet leg disposed along and integral with at least each said longitudinal side or each said transverse side of said pallet deck, removing said flat article from said mold, rotating said sheet legs while integral with said pallet deck into a position perpendicular to said top surface of said 20 pallet deck, and affixing said sheet legs into said position perpendicular to said top surface, said sheet legs affixed in said position for supporting said pallet deck.

4a BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective sketch of a fabricated pallet comprising sheet legs and a leg structure consisting of blockshaped posts located in the center longtitudinally.

Fig. 2 indicates the principle of constructing the sheet legs.

Figs. 3 and 4 are sectional views showing alternative designs of the plate-shaped legs.

Fig. 5 is a sectional view through the center longitudinally of a pallet having legs consisting of deep-drawn posts.

Fig. 6 is a sectional view through a block-shaped pallet leg of an alternative design.

Fig. 7 is a perspective sketch of a pallet deck and runner components prior to joining together.

Fig. 8 is a sectional view through a part of the pallet deck and spacer and runner components fastened to the bottom of the deck along its center longitudinally.

Fig. 9 is a top view of a pallet where the pallet deck has raised sections.

.Fig. 10 is a side view of the pallet in Fig. 9.

DETAILED DESCRIPTION OF THE INVENTION The present pallet is manufactured by a process that comprises a number of steps. The first step consists in extruding a parison, preferably as disclosed in the above mentioned US 4,874,649. The extrudate can have various wall thicknesses around its periphery, obtained by the use of an extrusion die of a suitable configuration. Thus, different parts of the pallet can be given different wall thicknesses. The extruded parison is flattened, and, when still hot, shaped in a mold to a substantially flat article. Parts of the article can be given a desired shape, e.g. profiled structures, deep-drawn posts, etc. by utilizing combinations of compressed air and vacuum.

-When the parison is laid flat, those parts of the insides forced into contact with each other will become welded torl ,o WO 97/25250 PCT/N097/00009 gether and form a double sheet. The principles of extrusion and forming are well known to persons skilled in the art.

In its simplest embodiment the parison consists of a homogeneous (solid) material. In order to make the extruded structure lighter, the parison can be coextruded with several layers, where at least one layer is at least partially foamed.

Present-day coextrusion technology permits a number of options for the shape and structure of the parison. For instance, the extruded structure can in one specific embodiment of the invention consist of a foamed plastic layer having a solid skin on just one side thereof. The foamed layer should preferably have a closed-cell structure, however, this is not an obligatory feature. In practice, a foam having a density of down to about 100 kg/m 3 can prove useful. The skin will form the pallet's outsides, so that a wear-resistant and easy-to-clean surface is attained.

In another specific embodiment of the invention, the extruded structure comprises a foamed layer having a solid skin on both sides, or optionally multiples of such a multilayer structure. Such a sandwich structure will, it is common knowledge, have high torsional rigidity and produce a lightweight construction. The foam layer typically comprises about of the sheet structure's thickness, and each skin layer about 15%, more preferably about 80% and about 10%, respectively. When the foam has a closed-cell structure, in some cases it can even constitute the entire wall thickness. The foam can have a density within the range of from the density of a solid material down to as far as it is practicable possible to produce a stable polymer foam. There has to be very good adhesion between the foam and the skin layer in order to attain an optimal rigid structure. Consequently, the foam and skin have to be coextruded in such a way that an integrated multilayer structure is produced.

Suitable materials for producing the extruded parison having a monolayer or multilayer structure comprise in principle all extrudable thermoplastics having sufficient rigidity. Especially suited thermoplastics are polyolefins such as polyethylene (PE) and polypropylene polyvinyl chloride (PVC), acrylonitrile butadiene (ABS), styrene plastics, poly- WO 97/25250 PCT/N097/00009 6 amides (PA) and polycarbonates Among these, polyolefin materials are preferred. However, there is nothing to prevent the foam material and the skin layer(s) from being made of different materials. For instance, an inside layer of high density polyetylene (HDPE) and an outside layer of ultrahigh molecular weight high density polyethylene (HMW-HDPE) and an intermediate layer of a foamed polyethylene will comprise a suited structure. Another structure has an inside layer of PP homopolymer, an outside layer of PP block copolymer, and an intermediate layer of foamed PP. Of course, other structures are also possible and fall within the scope of the invention.

The materials constituting the solid part of the extruded multilayer structure can, if desired, be reinforced with cut glass fibers and/or long glass fibers in the direction of extrusion.

During extrusion of the parison and forming of the components of the pallet, manufacturing waste will be produced which, for economic reasons, should be returned to production.

This can be done by incorporating the waste material into one or more layers in the coextruded multilayer structure. Consequently, in a practical embodiment of the invention, it will be advantageous to use materials that can be mixed with one another. Polyolefin materials are excellently suited in this respect, especially certain types of polypropylene (PP) and high-density polyethylene (HDPE). Smaller amounts of glass fibers in the skin layers can after grinding of the material be re-extruded and without problems included in the skin layers, and even in the foam layer(s).

It is also possible to add to the thermoplastics crosslinking agents in order to crosslink the material in the pallets produced. The disadvantage is that this kind of manufacturing waste cannot be recycled. Another disadvantage is that the pallets then as a rule can be joined together only mechanically, though there do exist silane-based crosslinking agents that can be crosslinked after the finished pallet has been made.

Because articles made from plastic materials have a slippery surface, and especially articles made from polyolefins like HDPE and PP, it will often be desirable to add to WO 97/25250 PCT/NV097/00009 7 the pallet deck a friction-increasing material. This can be done by extruding on the outside of the parison an extra layer with a friction material in a width from narrow strips to a continuous facing around the entire periphery of the parison or around parts of its periphery. The friction material on the top of the pallet deck will prevent goods from sliding off the pallet, while the friction strips on the bottom will prevent the pallet from sliding easily off truck forks when the pallet is being handled. Alternatively, the friction material coating may be applied onto the pallet deck of already fabricated pallets. This can easily be performed by extrusion coating, for instance by conveying the pallets underneath a stationary extruder in a coating line.

Preferably, the friction material is applied to the pallet in the form of parallel, raised longitudinal sections having a height of about 1 mm and in a width from narrow strips to a continuous facing. When the pallet is fabricated from a polyolefin material, a suitable friction material is selected among polyolefin-containing materials such as EVA, EBA and the like.

It is of course possible to add to the plastic materials the additives and auxiliary agents that are customary for thermoplastics, such as antistatic agents, heat and UV stabilizers, colorants, etc. The various layers of the multilayer structure can be of dissimilar colors, as desired. It is also possible that pallets intended for dissimilar purposes can have different colors.

The pallet deck and the sheet pallet legs along the sides of the pallet are formed in one forming step into one predominantly flat article. The side parts of this article are then brought into a position perpendicular to the main sheet and fastened, e.g. by welding, in this position. The fastened side sheets will thus constitute one set of integrated pallet sheet legs made from the same sheet structure as the rest of the article, i.e. the pallet deck.

In one embodiment of the pallet, it has sheet legs only along two opposite sides. To stabilize the legs it may be convenient to provide runners fastened to the bottoms of two corresponding opposite sheet legs. This is particularly appro- WO 97/25250 PCT/N097/00009 8 priate when the sheet legs have openings cut through their edges, e.g. three separate sheet legs along each longitudinal side of the pallet and runners fastened to the bottoms of each pair of opposite sheet legs in the transverse direction of the pallet.

In its simplest embodiment the pallet has sheet-like legs both along its longitudinal and transverse sides, and no legs in the center on the bottom. The sheet-like legs are joined together in the corners where they meet to obtain a rigid construction. The fields of use of such a pallet will normally not require any additional pallet legs.

Any combination of sheet-like legs in the longitudinal and/or transverse directions of the pallet is contemplated by the present invention.

When the pallet shall carry greater loads, additional legs intended for carrying the substantial part of the load must be provided, usually fastened to the bottom of the pallet deck at equal distances from and parallel to the sheet legs.

Such legs may be of various constructional designs.

Detailed description of drawings Preferred embodiments of the pallet will now be explained in more detail with reference to the attached drawings.

Fig. 1 shows one particular embodiment of the finished pallet, i, with the pallet deck, 2, sheet legs, 3, and leg members comprising more block-shaped pallet legs, of which only one is seen in the figure.

Fig. 2 demonstrates the principle of forming the sheet legs. During the forming of the parison V-shaped grooves, 5, are impressed into the sheet in its whole length in the direction of extrusion and/or in its transverse direction at specific distances from the side edges of the sheet.

These grooves are given a bottom angle of approximately 90 and a suitable depth; however, the wall thickness in the bottom of the grooves must be sufficient to avoid that the material break during the subsequent manufacturing steps. After that the formed sheet has been removed from the mold, the side parts, 3, of the sheet are bended along the V-shaped grooves WO 97/25250 PCTJNO97/00009 9 until a position perpendicular to the main sheet and then fastened in this position. This operation is indicated by the dotted lines in figure 2. Thus, the main sheet, 2, will constitute the pallet deck and the side parts, 3, will constitute the sheet legs. The thickness of the main sheet, 2, is preferably greater than the thickness of the side sheet parts, 3.

This difference in thicknesses is achieved by regulating the circumferential thicknesses of the parison, as explained above, and make the final dimension adjustments in the forming tool. This thickness difference will contribute to obtain a rounded off transitional part between the pallet deck and the sheet legs.

The pallet normally requires openings in the sheet legs to allow truck forks to be easily inserted so the pallet can be easily lifted and transported. Figure 3 shows one embodiment of the sheet legs, 3, provided with approximately rectangular openings having rounded off corners. Obviously, the openings can be of any suitable shape. Another embodiment of the sheet legs is shown in figure 4, where said openings are expanded out through the bottom edge of the side sheet, resulting in three separate sheet legs, optionally two interspaced sheet legs. The desired openings in the side sheets are marked during the forming in the mold by impressing the contours of the openings and after the pallet has been formed the indicated parts are forced out.

In the embodiment of the pallet shown in figure i, posts which will constitute one set of pallet legs are deepdrawn in the bottom of the pallet deck in its center longitudinally and parallel to the sheet legs. In fig. 1 only one post at one end of the pallet can be seen. Normally, there are three deep-drawn posts evenly distributed along the center line of the pallet, one post at each end of the pallet and one in the middle. This is indicated in figure 5, which is a sectional view which runs through the pallet at section A-A in figure 1. The posts, 4, can be deep-drawn in one operation to their final depths, thus constituting one set of final blockshaped pallet legs. The disadvantage of deep-drawing said pallet legs to full depths is that the wall thicknesses in the bottom corners of the posts will become small. The properties WO 97/25250 PCT/N097/00009 of the material from which the pallet is manufactured determine the allowed deep-draw ratios, wall inclinations, shape of corners, etc. The problems related to deep-drawing thermoplastics are common knowledge to persons skilled in the art.

An optional embodiment of the block-formed pallet legs is shown in figure 6. Each post, 4, is deep-drawn to a depth less than the final depth, for example to half the height of the final pallet leg. To the bottom of said halfsized post, 4, a separately produced block, 6, is then fastened in a particular operation. In principle, such blocks may be of any shape and produced from any material, provided that they can be permanently fastened to the bottoms of the half-sized posts. The blocks, 6, must have such a height that they, when combined with the deep-drawn posts, 4, produce pallet legs of correct heights. The advantages of this embodiment is that the necessary deep-draw ratios of the posts become smaller, and the pallet legs will become stronger.

Instead of using such blocks, all of them can be replaced by one runner component, such as the one, 9, shown in fig. 7. This runner component consists of a cross member, having two or more upward-facing posts, 11, which are fastened by their tops to the bottoms of the posts, 4, deep-drawn in the deck, 2.

In another embodiment similar runner components may be fastened to the bottom surfaces of sheet legs along opposite sides of the pallet. The height of a possible deep-drawn leg structure in the center of the pallet must then be adapted to the particular design of the runner. Such a runner may be similar to the runner, 9, shown in figure 7. In a preferred embodiment half-sized posts, 4, as shown in figure 6, are deep-drawn in the bottom of the deck, and the runners are furnished with a center post that matches post 4 of the pallet, while the posts at the ends of the runners must have a height adapted to the sheet legs, 3. Thus, the bottom part of the cross member of the runner component, 10, will face the floor.

Figure 7 shows an embodiment of the pallet where a continuous U-shaped profile, 7, is thermoformed in the bottom side of the deck in the whole length thereof in its center longitudinally and parallel to the sheet legs, 3. The upper WO 97/25250 PCT/N097/00009 11 spacer component, 8, is fastened by its cross member, 10, to the bottom of the U-shaped profile, 7. The lower runner component, 9, is fastened by the tops of its posts, 11, to the bottom of the matching posts, 11, on the upper spacer component, 8. Each spacer and runner is manufactured in a particular operation by forming a parison into a cross member, 10, with posts, 11.

Fig. 8 is a sectional view through the finished pallet, i, at section B-B in Fig. 7. The section runs through the i0 pallet deck, 2, the U-shaped profile, 7, and posts, 11, on the upper spacer component, 8, and lower runner component, 9. The U-profile, 7, is formed into a channel, 12, and two closed hollow spaces, 14. The upper spacer component, 8, is shaped so that a channel formed on the top of the cross member and longitudinally has the same width as the channel, 12, in the bottom of the U-profile. Consequently, a closed channel, 12, extending longitudinally along the pallet is created when the pallet deck, 2, and the upper spacer component, 3, are joined together. The channel's length, width and depth can be made to fit the requirements. The U-profile, 7, and the upper spacer component, 8, are formed so that each channel, 12, is sealed at each end so that a closed hollow space is created. Optionally, the forming can be such that the channel is open at both ends. The lower runner component, 9, is in principle formed like the upper spacer component, 8, but so that the cross member, 10, constitutes the surface facing the floor. Each post on the upper spacer component, 8, and lower runner component, 9, is formed as a symmetric profile so that two like-shaped hollow spaces, 15, and a channel, 13, are created, that will also create a closed hollow space. The shape of the pallet's posts can differ designwise from that sketched in Fig. 8 by variations in the dimensions of the channel, 12, and hollow spaces, 13 and 15. However, the bearing walls in the posts must be formed so that a sufficiently rigid structure is attained.

A suitable stiffening section can be inserted into the channel, 12, in Fig. 8, to ensure that the pallet does not deflect at its center under great stress. Preferably, sections made of a lightweight metal, plywood, reinforced thermoset WO 97/25250 PCT/N097/00009 12 plastics GRP), or other suitable plastic materials or composites are used in order to keep down the pallet's unloaded weight.

As mentioned above, pallets having sheet legs along two opposite sides may have runners fastened to the bottoms of corresponding pairs of opposite legs. Such runners are made by laying flat the extruded parison and shaping it into a flat, double sheet. During this forming there are impressed V-shaped grooves at a certain distance from each end, as l0 explained above. Finally, the end parts are bent along said V-shaped grooves into a desired angle 90 0) to the main cross member and fastened in such a position. Each runner is then fastened by the top surfaces of its ends to the bottoms of the appropriate sheet legs of the pallet. However, this embodiment involves a number of welding operations for each pallet: the integrated sheet legs of the pallet are fastened in their correct positions by welding, as explained above; the end parts of each runner are welded in their correct positions, usually in a perpendicular position, to the cross member; and finally the runner are fastened by its end top surfaces to the bottom surfaces of said sheet legs. To simplify the assembly of such a pallet the sheet legs of the pallet may be deleted and each runner fastened by the top surfaces of its ends directly to the bottom of the pallet deck.

The individual components of the pallet can be jointed together most expediently by welding, preferably by butt welding, but other methods of joining like extrusion welding, the use of glue or adhesive, and mechanically joining, can also be employed.

The pallet deck can have a flat surface or a profiled surface. A particularly preferred embodiment of a pallet having a profiled deck is shown in figures 9 and Fig. 9 is a top view of a pallet, i, having channels, 16, impressed into the pallet deck, thus creating raised sections, 17, running in the transverse direction of the pallet.

Fig. 10 is a side view showing the longitudinal side of the pallet in Fig. 9.

The dimensions of such raised sections and impressed channels, i.e. their lengths, widths and heights, can be chos- WO 97/25250 PCT/N097/00009 13 en freely within the physical limits set by the extruded parison and the forming conditions. The bottom of the pallet deck may be given a similar design as the top surface of the deck, or it may be kept even. In principle, the raised sections in the top and bottom surfaces of the pallet deck may run in any direction, also in different directions. In the particular embodiment of the pallet shown in Figs. 9 and 10 the width of each raised section is about 35-40 mm, and the distance between any two adjacent raised sections, i.e. the width of the l0 impressed channels, is of approximately the same magnitude.

The height of each raised section is about 10 mm.

It should be obvious that in principle the top surface, optionally also the bottom surface, of the pallet deck can be given any shape or design of patterns: the only restriction being the technical conditions mentioned above. All such designs are comtemplated by the present invention.

Pallet decks having raised sections may provide a simplified unloading of the goods that they carry. For instance, the pallet indicated in Figs. 9 and 10 allows specifically designed forks to be inserted into the channels in the upper pallet deck underneath the goods, which may then be removed as one unit from the pallet by the use of an adequate lifting device. This is particularly useful when unloading unit loads, such as goods shrink-wrapped in plastic films, bottle crates, etc.

In the foregoing preferred embodiments of the pallet have been explained in reference of pallets having a rectangular shape. Obviously, the pallets may be of a square shape or any other suitable geometrical shape. Further, references to longitudinal sides and transverse sides of the pallet can be interchanged without deviating from the scope of the invention.

The above description is provided for a clearer understanding of the principles of the invention. Variations in designs and embodiments of the present pallets based on the technical concepts explained above are considered being within the scope of the present invention.

P:\OPER\AXD\19482-97,125 -5/5/99 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers or steps.

a *aa.

a a.

a. -4, 21

Claims

4. A pallet according to claim 3, wherein said separately produced leg structures comprise blocks which are fastened to said bottom surface of said block-shaped posts.
5. A pallet according to claim 3, wherein said separately produced leg structures comprise a separately thermoformed runner component shaped as a cross-member having at least two upward-facing runner posts, and said runner component is fastened by a top surface of said runner posts to said bottom surfaces of said pallet deck.
6. A pallet according to claim 1, comprising one set of sheet legs, and further comprising a thermoformed U-shaped profile in the bottom surface of said pallet deck in the whole length thereof in its center longitudinally and parallel to said sheet S"t °legs, and fastened to the bottom of said U-shaped profile, one separately manufactured pallet leg structure comprising an upper spacer component and a lower runner component; said upper spacer *9eo component comprising a cross member having downward-facing 20 posts; and said lower runner component comprising a cross member having upward-facing posts; said upper spacer component being fastened by its cross member to a bottom surface of said U- shaped profile; and said lower runner component being fastened by top surfaces of its upward-facing posts to bottom surfaces of ~25 the matching downward-facing posts on said upper spacer component.
7. A pallet according to claim 6, wherein at least one of said i$ upper spacer component and said U-shaped profile facing said spacer component are formed with a longitudinal recess so j(/ P:\OPER\AXD\ 19482-97.125 5/5/99 -16- that a straight open channel is created between said upper spacer component and said deck, into which a stiffening section may optionally be inserted.
8. A pallet according to any one of claims 1 to 7, which the sheet legs include openings to allow truck forks to be inserted.
9. A pallet according to claim 8, which said openings are expanded out through the bottom edge of said side sheets to create at least two interspaced sheet legs. The pallet of claim 9, wherein one runner component is fastened to a bottom of each pair of said sheet legs along opposite sides of said pallet deck, each said runner component being produced separately and comprising posts of heights adapted to the sheet legs. *e
11. A pallet made of a thermoplastic material, the pallet comprising a deck and at least two runners disposed underneath 20 said deck, said pallet deck having top and bottom surfaces, said runners being in the shape of a cross member having a upward- facing runner post in each end thereof; said runners being oooq fastened by a top surface of said runner posts to said bottom of said pallet deck; said pallet deck having been produced by 25 thermoforming an extruded plastic parison having a monolayer or .545 multilayer structure into one predominantly flat article, said runners having been produced separately by thermoforming an extruded parison identical to the one used in the production of said pallet deck into a predominantly flat article and bending ,the end parts of said latter article into a position C1K o f~i P:\OPER\AXD\ 19482-97.125 5/5/99 -17- perpendicular to the main part of said latter article to obtain said runners having upward-facing posts.
12. A pallet according to any one of claims 1 to 11, wherein said parison is extruded from a thermoplastic selected from polyolefins, PVC, ABS, styrene plastics polyamides (PA) and polycarbonates (PC).
13. A pallet according to any one of claims 1 to 12, wherein said extruded structure is a coextruded integrated multilayer structure comprising at least one foamed plastic layer having a solid skin on both sides thereof.
14. A pallet according to any one of claims 1 to 13, wherein said extruded structure comprises at least one polyolefin material.
15. A pallet according to claim 12, 13 or 14, wherein said thermoplastic is reinforced with a reinforcing material selected 20 from cut glass fibres and long glass fibres.
16. A pallet according to any one of claims 1 to 15, wherein at S S least said top surface of said deck is furnished with a plurality of parallel, raised longitudinal sections made of a friction material.
17. A pallet according to claim 16, wherein the parallel, raised longitudinal sections have a height of about 1 mm and a width of from narrow strips to a continuous facing. i^ l r /I P:\OPER\AXD\19482-97.125 515/99 -18-
18. A pallet according to any one of claims 1 to 15, comprising a friction material extruded onto said top surface of said plastic pallet deck.
19. A pallet according to one of the preceding claims, wherein said top surface, and optionally also said bottom surface, of said pallet deck being profiled with impressed channels and raised sections of desired dimensions.
20. A pallet substantially as hereinbefore described with reference to the drawings.
21. A method of manufacturing a plastic pallet comprising a deck and legs disposed underneath said deck for supporting said deck, the method comprising the steps of: producing in a mold an extruded parison, while hot, into a predominantly flat article comprising a pallet deck, said pallet deck comprising top and bottom surfaces, substantially parallel, o* 20 opposed longitudinal sides, and substantially parallel, opposed transverse sides, said predominantly flat article further comprising a plurality of sheet legs, one said sheet leg disposed along and integral with at least each said longitudinal side or each said transverse side of said pallet deck, 25 removing said flat article from said mold, r~r rotating said sheet legs while integral with said pallet deck into a position perpendicular to said top surface of said pallet deck, and affixing said sheet legs into said position perpendicular V l/ 0 to said top surface, said sheet legs affixed in said position t i P:\OPER\AXD\ 19482-97.125 5/5/99 -19- for supporting said pallet deck.
22. The method of claim 21, further comprising the step of forming in said bottom surface of said pallet deck at least two pallet deck posts, said pallet deck posts to function as load-carrying pallet legs, said pallet deck posts being situated at a longitudinal center of said bottom surface of said pallet deck and parallel to one said sheet leg.
23. The method of claim 22, wherein in said forming step said pallet deck posts are block-shaped and are deep-drawn to a depth less than the final height of the plastic pallet, the method further including the step of fastening to a bottom surface of said block-shaped posts separately produced leg structures, said leg structures being of a height that when fastened to said pallet deck posts pallet legs of a desired height are obtained.
24. The method of claim 23, wherein in said fastening step said ,ooo separately produced leg structures comprise blocks which are 20 fastened to said bottom surface of said block-shaped pallet deck posts. 99*S *°°99 The method of claim 23, wherein in said fastening step said separately produced leg structures comprises a separately 25 thermo-formed runner component shaped as a cross-member having 9e. at least two upward-facing runner posts, and wherein said runner component is fastened by a top surface of said runner posts to said bottom surfaces of said pallet deck posts. P:\OPER\AXD\19482-97.125 5/5/99
26. The method of claim 21, wherein one set of sheet legs is produced and wherein said method further comprises the step of thermo-forming a U-shaped profile in the bottom surface of said pallet deck in the whole length thereof in its centre longitudinally and parallel to said sheet legs, and fastening to the bottom of said U-shaped profile one separately manufactured pallet leg structure comprising upper and lower runner components, said upper runner component comprising a cross member having downward-facing posts, and said lower runner component comprising a cross member having upward-facing posts, and said upper runner component is fastened by its said cross member to a bottom surface of said U-shaped profile and said lower runner component is fastened by top surfaces of its said upward-facing posts to bottom surfaces of matching said downward-facing posts on said upper runner component. S27. The method of claim 26, wherein at least one of said upper runner component and said U-shaped profile facing said upper 5555 runner component are formed with a longitudinal recess, so that 20 a straight open channel is created between said upper runner component and said pallet deck, into which a stiffening section may optionally be inserted.
28. The method of claim 21 wherein said sheet legs include openings to allow truck forks to be inserted. S
29. The method of claim 28 wherein said openings are expanded out through the bottom edge of said side sheets to create at least two interspaced auxiliary sheet legs. 'V P:\OPER\AXD\19482-97.125 5/5/99 -21- The method of claim 29 wherein one runner component is fastened to a bottom of each pair of said sheet legs along opposite sides of said pallet deck, each said runner component being produced separately and comprising posts of heights adapted to the sheet legs.
31. The method of claim 21 wherein in said producing step said parison is extruded from a thermoplastic selected from polyolefins, PVC, ABS, styrene plastics, PA and PC.
32. The method of claim 31 wherein in said producing step said parison is a coextruded integrated multilayer structure comprising at least one foamed layer having a solid skin on both sides.
33. The method of claim 31 wherein said thermoplastic material is at least one polyolefin material. 0
34. The method of claim 31 wherein said thermoplastic material 20 is reinforced with a material selected from cut glass fibers and long glass fibers.
35. The method of claim 21 wherein in said producing step a polyolefinic material having a high coefficient of friction is coextruded onto at least a part of the periphery of said parison.
36. The method of claim 21 further comprising the step of SI applying sections made of a friction material to the plastic S allet by extrusion coating said friction material onto said 3(pallet by extrusion coating said friction material onto said y P:\OPER\AXD\19482-97.125 6/5/99 -22- pallet deck of the plastic pallet.
37. The method of claim 35 wherein in said applying step said friction material is applied to said pallet deck as parallel, raised longitudinal sections of approximately 1 mm height and a width of from narrow strips to a continuous facing.
38. A method substantially as hereinbefore described with reference to the drawings. DATED this SIXTH day of MAY 1999 Borealis A/S by DAVIES COLLISON CAVE Patent Attorneys for the applicant(s) 9* S* *o* z