Pultrusion pallet

Abstract

A pallet made of pultrusion preferably includes a main deck and cross-members having unidirectional fibers and glass or fiber mat therein. The main deck and cross-members are assembled by many various means, including a unitary design or attached through the use of structural adhesives, brackets, rivets, and the like. A pair of fastening devices are provided to secure the goods to the pallet.

Description

FIELD OF THE INVENTION

The present invention relates to a fiber reinforced pultruded pallet, and a method for making the same.

BACKGROUND OF THE INVENTION

The common wooden and plastic industrial pallets are generally known in the art. Such pallets, however, have several shortcomings in regards to both the limitations of their uses, and their manufacture. Wooden pallets are heavy and difficult to manufacture. They are typically constructed by sandwiching wooden blocks between two similar decks or surfaces. The surfaces may either be made of a continuous sheet, or more commonly, have a plurality of wooden boards typically arranged in a parallel manner. In general, the surfaces and blocks are stacked or arranged to provide apertures suitable for access by the forks of a forklift truck or pallet jack from at least one side. Since the aesthetic appearance of a pallet may not outweigh the cost, it may include scrap or recycled wood. Often, the size variations in the wooden boards may lead to inconsistent dimensions. Inconsistent dimensions may impede an automated manufacturing process.

By its nature, the wood may be subject to swelling, warping, shrinkage, splintering, deterioration and fungal or bacterial growth after exposure to moisture and other elements. If the wooden pallets are assembled with nails, this may lead to the further problems of potential cargo damage from loose nails, rust formation and the hazardous and/or sanitation problems accompanying the corrosion. Many manufacturing environments require a level of sanitation that wooden pallets simply can not provide.

Attempts to overcome the drawbacks of wooden pallets with plastic pallets have been faced with similar shortcomings. Prior art designs of plastic pallets have had to deal with issues such as the trade off between the cost and weight bearing capability. Typically, plastic pallets designed with a significant weight bearing capability have tended to be both heavy and expensive. In the same manner, inexpensive plastic pallets have had both strength and durability issues. Certain thermoplastic pallets have utilized steel support and reinforcing structures encapsulated in the plastic material. The incorporation of steel with the pallet adds to the cost of construction, and creates an additional step in the manufacturing process.

It is therefore desirable to provide a long-life pallet with outstanding physical attributes that is relatively inexpensive and can be manufactured with relative ease. Specifically, it is desirable to provide a pallet that meets and exceeds stringent standards, including the needs and requirements of the USDA, FDA, NSF and Grocery Manufacturers Association (GMA).

SUMMARY OF THE INVENTION

In various embodiments, the present invention provides a pallet having a main deck and a plurality of supporting cross-members, all made from a monolithic piece of material via a pultrusion process. The pultruded pallet includes a thermosetting resin with reinforcing fibers therein. Preferably, at least a portion of the pultruded pallet includes a fiber orientation commonly referred to as veil, or woven roving material, along with unidirectional fibers aligned substantially parallel to the main deck and the connecting cross-members. In certain embodiments, additional end support members can be pultruded separately and secured to the main deck with structural adhesive or metal or composite brackets. In an alternate embodiment, the main deck is pultruded as a single planar piece, and the supporting cross-members and end support members are separately pultruded and attached.

In another embodiment, the present invention provides a pallet with a deck area having a plurality of individually pultruded components. The pallet includes similar support cross-members and end support members, however, instead of a single piece main deck, the pallet comprises individual pultruded pieces arranged to form a frame with a deck having the shape of a conventional pallet. The individual components are connected together with structural adhesive, metal rivets, composite brackets, metal brackets, or the like.

In yet another embodiment, the present invention provides a system for shipping goods. The system includes a pallet comprising a pultruded main deck and a plurality of pultruded structural supporting cross-members. A pair of fastening devices is provided and configured to secure goods placed on the pallet. In preferred embodiments, the deck, cross-members, and fastening members comprise a fiber reinforced thermosetting resin. Preferably each fastening member includes two extension brackets telescopically coupled to one another for coordinated slidable movement to provide a variable length. At least one retaining strap is provided and configured to secure the fastening devices to the goods and/or the pallet.

In still another embodiment, the present invention provides a method of making a pultruded pallet having a thermosetting resin and a plurality of unidirectional aligned fibers therein. Continuous strands of glass, woven roving or fiber mat veil are oriented as desired through a guide plate and saturated and combined with a resin matrix by a resin impregnator. The saturated mixture includes resin, fillers, pigment, and catalyst in addition to any other additives required. A resin impregnator optimizes the complete saturation of the reinforcements and feeds the material into an array of tooling that removes excess resin and shapes the material prior to entering a die. Once in the die, and under proper heat, the glass/mat resin matrix polymerize with the thermosetting resin. The mixture is pulled through a shaped frame die to form a monolithic deck having a plurality of longitudinal cross-members extending therefrom. Additional end support members are separately pultruded and attached with structural adhesive, metal rivets, composite brackets, metal brackets, or the like.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a top perspective view of an assembled pallet made in accordance with a first embodiment of the present invention;

FIG. 2 is an exploded perspective view of the pallet of FIG. 1;

FIG. 3 is a top perspective view of an assembled pallet made in accordance with a second embodiment of the present invention;

FIG. 4 is an exploded perspective view of the pallet of FIG. 3;

FIG. 5 is a top perspective view of an assembled pallet made in accordance with a third embodiment of the present invention;

FIG. 6 is an exploded perspective view of the pallet of FIG. 5;

FIG. 7 is a top perspective view of an assembled pallet made in accordance with a fourth embodiment of the present invention;

FIG. 8 is an exploded perspective view of the pallet of FIG. 7;

FIG. 9 is a perspective view of a pallet system according to the present invention; and

FIG. 10 is a magnified perspective view of a fastening device as shown in the pallet system of FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements.

As shown in FIG. 1 and generally referenced by the number 20, the pallet of the present invention has four peripheral edges 22 defining a perimeter. Preferably each edge 22, or side, is disposed at a substantially right angle, thereby forming a rectangular shape. In one preferred embodiment, the pallet is constructed having the industry standard size and dimensions, which is currently 40 by 48 inches (1.0 by 1.2 m), although it may be made in any desired size or shape. FIG. 2 depicts an exploded perspective view of the pallet 20 of FIG. 1, showing the individual components spaced apart from each other, which comprise a substantially planar main deck 24 having a plurality of integral supporting cross-members 26a, 26b extending therefrom as a monolithic pultruded component 28. In various embodiments, the pultruded component 28 comprises a center cross-member 26a and two side cross-members 26b. The cross-members 26a, 26b can be of various forms, including “I” and “T” shapes as shown. In certain other embodiments, the cross-members may have a tubular, rectangular, or “C” type shape. Preferably, two opposing pultruded end caps, or end support members 30, are attached to the main component 28 for additional strength. In these embodiments, the end support members 30 are mechanically attached to the main deck 24 and/or connecting cross-members 26a, 26b with structural adhesive, metal rivets, composite brackets, metal brackets, or the like.

The end support members 30 can have various designs and can be manufactured using various methods of fabrication, depending on the desired uses. The end support members 30 as shown in FIGS. 1 and 2 are created by forming one or more substantially rectangular or tube shaped members 31 via a pultrusion manufacturing process. For example, a long pultruded tube is cut to an appropriate length as a tubular support member 31 for secondary assembly to the pallet deck 28 and/or the cross members 26. In another embodiment, as depicted in FIGS. 3 and 4, the end support members 32 are created by first manufacturing a pultruded component having a channel, such as member having a substantially “C” shaped cross-section. The “C” is then cut to an appropriate length for secondary assembly to the pallet. In yet another embodiment, as shown in FIGS. 5 and 6, the pallet has an end support system including a plurality of end support members 34. In various embodiments, the end support members 34 are created by first manufacturing a “flat stock” pultruded sheet (not shown) similar in shape as the main deck 24. These flat stock sheets can typically be many inches wide (for example, 48″). The flat stock sheet is then cut into the appropriate widths for secondary assembly to the main pallet component 28. In still another embodiment, the end support members 34 can be created by manufacturing a special designed lineal pultrusion, having unique features such as tapered edges 36. The tapered edges 36 provide easy access for entry and exit of the pallet openings for hand operated pallet jacks.

FIGS. 7 and 8 illustrate still another embodiment of the present invention, providing a pallet 20 with a deck area having a plurality of individually pultruded components. The pallet includes similarly designed support cross-members 38a, 38b and end support members 40, however, instead of a single piece main deck, the pallet comprises individual pultruded members 42 arranged to form a frame with a deck having the shape of a conventional pallet. The individual components are connected together with structural adhesive, metal rivets, composite brackets, metal brackets, or the like.

As shown, the cross-members 26a, 26b and end support members 30 forming the bottom of the pallet have a substantially planar bottom surface for the secure placement of the pallet on the ground or other resting surface. This also allows for the stable stacking of the pallet onto a similarly designed pallet. Preferably, the end supports 30, 32, 34, 40 are of a sufficient size having apertures 44 defining a space suitable for access by the tines, or forks, of a forklift truck or pallet jack from any of the four sides 22 of the pallet 20. The current industry standard is to provide an aperture 44 with a separation distance of about 3.5 inches. The apertures 44 may be punched, pierced, or drilled through the main deck as known in the art.

FIG. 9 illustrates the pallet shipping system 50 according to various embodiments of the present invention. The shipping system preferably includes a pultruded pallet 20, as described above. As shown, the pallet comprises substantially rectangular, or tube shaped, cross members 26a, 26b. A pair of pultruded fastening devices 52 is provided and configured to secure goods that are placed on the pallet deck 28. For purposes of illustration, FIG. 9 depicts a plurality of glass sheets 66 that are aligned and stacked on the pallet 20 for shipment. Each fastening device 52, as further illustrated in FIG. 10, preferably includes first and second extension brackets 54, 56. In one presently preferred embodiment, the extension brackets 54, 56 are telescopically coupled to one another for coordinated slidable movement. The brackets 54, 56 can be adjusted to provide a variable length, depending upon the type and size of goods 66 being shipped. As should be understood, depending upon the type of goods being shipped, the interior side of the brackets (not shown) may require certain padding materials so as to not damage the goods contained therein.

In various embodiments, the fastening members 52 are secured to the goods 66 using one or more retaining straps. Suitable retaining straps are widely known in the art and should be made of materials strong enough to withstand the stresses of moving and lifting a loaded pallet. As shown in FIG. 9, a first retaining strap 60 is wrapped around the fastening devices 52 and the goods 66. A second retaining strap 62 is wrapped around the fastening devices 52 and the pallet 20. In one embodiment, the retaining straps 62 are wrapped through, or anchored with, the center tubular cross-member 26a. It should be understood that the retaining straps can be used having a wide range of orientations, all of which are within the scope of the present invention. In various embodiments, the fastening devices 52 may be equipped with protruding retaining members 58. As shown in FIGS. 9 and 10, the retaining members 58 are disposed in the corner regions of the extension brackets 54, 56. The retaining members can alternatively be secured in a variety of locations configured to prevent the retaining straps 62 from sliding or shifting. In various other embodiments, the extension brackets 54, 56 are pultruded and formed with a recess 66, or groove, configured to secure the retaining strap 60 in place and prevent movement.

Each component of the pallet 20, including the combined main deck 24, cross-members 26a, 26b, end support members 30, 32, 34, and fastening devices 52, is preferably a formed pultrusion that includes a thermosetting resin with reinforcing fibers therein. Pultrusion is a process known in the art used to create fiber reinforced polymeric composite materials. The preferred pultrusion composition of the present invention includes a thermosetting resin, various inert fillers, fiber reinforcements which typically consist of glass and veil mat fibers, a polymerization initiator, and lubricants.

The term “thermosetting resin”, as used herein, refers to plastics (e.g., organic polymers) that are cured, set, or hardened into a permanent shape. Curing is an irreversible chemical reaction typically involving molecular cross-linking using heat or irradiation (e.g., UV irradiation). Curing of thermosetting materials can be initiated or completed at, for example, ambient or higher temperatures. The cross-linking that occurs in the curing reaction is brought about by the linking of atoms between or across two linear polymers, resulting in a three-dimensional rigidified chemical structure. Common resins may include urethanes, polyesters and vinyl esters. Resins may be selected depending on the specific pallet design, load capacity, and other requirements.

The reinforcing fibers used in the present invention preferably include inorganic fibers, more preferably the fibers include glass fibers. The fibers include both individual fibers or rolls of fiberglass mats, or veils. One common fiber mat is woven roving material. The woven roving material may contain various grades of bidirectional, or weaved, organic and/or inorganic fibers. As used herein, the general term “fiber” refers to individual filaments, fibers and fiber bundles. Both individual fibers and fiber bundles can have a substantially greater width as well as height as compared to the individual filaments or fibers. Preferably, the woven roving comprises one of a high-strength fiber, a high-strength fiber in a polymer composite matrix, a high-strength fiber in a metal matrix, a high-strength metallic band, and a high-strength metallic wire.

Some non-limiting examples of inorganic fibers include E glass, S glass, high silica fibers, quartz, boron, silicon carbide, silicon nitride, alumina, and titanium carbide. Other materials for the woven roving layer include any and all pitch- and polyacrylonitrile (PAN)-based carbon fibers including standard modulus grades, intermediate modulus grades, high modulus grades, and ultra-high modulus grades. Some examples are Thomel P-25, Magnamite AS4, Torayca M30 and T1000, Magnamite IM7, Torayca M40J, Thornel P-55S; Torayca M60J; and Thornel P120. Additional materials for the woven roving layer include any and all grades of aramid, meta-aramid, and para-aramid fiber, for example Twaron, Kevlar 29, 129, 49, and KM2. Also, any and all grades of other polymeric fibers, for example, Spectra 900, Spectra 1000, Dyneema SK60, polyphenylene sulfide, polyetheretherketone, Vectran HS, Vectran M, polyimide, polyetherimide, and polyamide-imide. Also, any and all grades of polybenzimidazole-based fiber, including Zylon-AS and Zylon-HM. Also, any and all grades of metallic banding, wire, or fiber, including steel alloys, aluminum alloys, and titanium alloys.

Where the woven roving includes a composite material, the binding matrix may include any and all grades of thermosetting and thermoplastic polymers. Some examples include epoxy, polyester, vinyl ester, polyurethane, silicone, butyl rubber, phenolic, polyimide, bismaleimide, cyanate ester, polyetheretherketone, polyphenylenesulfide, polysulfone, polyethylene, polypropylene, polycarbonate, polyetherimide, polyethylenesulfide, acrylic, acylonitrile butadiene styrene, and nylon.

Various embodiments of the present invention preferably incorporate the use of high tensile strength glass filaments in the form of a woven roving material mixed in the resin. Preferably the fibers are woven in a bidirectional pattern with untwisted roving strands, drawn in a substantially parallel orientation. In one embodiment, the main deck additionally includes uni-directional aligned fibers which extend substantially the entire length of main deck and in the pultruded cross-members of the pallet. Typical lengths of the continuous fibers will have a range of about 40 to about 48 inches, corresponding to the length and width of the pallet, respectively.

The main deck 24 has a generally planar load bearing surface upon which objects and goods may be positioned for transport and storage. Preferably, the main deck 24 has a plurality of openings 46 in the mid-side regions. These openings 46 are designed to create the appropriate amount of airflow through the pallet, and they additionally reduce the pallet weight. The openings may be punched, pierced, or drilled through the main deck as known in the art.

A number of indentations and projections such as ridges and channels may be formed in the top of the upper deck, with complementary features being defined in the opposite surface, as desired. These ridges and channels are preferably arranged as providing additional strength, support and resistance to flexing, bending or buckling of the main deck. They may also allow for the drainage of any liquids which may accumulate thereon. Alternate embodiments may include further channels directing fluid to the sides of the pallet. It should be noted that the number, orientation, size and shape of the ridges and channels can be varied in many alternate configurations for optimized strength and air flow. The configuration of the channels and ridges is intended to increase the load bearing strength of the pallet while minimizing the creation of any area that may be subject to structural failure or weakness. Of course, the main deck may also have a continuous surface without apertures if so desired.

In another embodiment, the load bearing surface may have a texture or an etched pattern thereon which would act as a non-skid surface to prevent objects from sliding during transport. Alternatively, any suitable type of friction tape or friction coating may be applied or laminated to the load bearing surface in order to help prevent movement of objects on the pallet.

As previously discussed, one preferred embodiment includes the pultruded main deck 24 constructed having continuous, uni-directional aligned reinforcing fibers which extend substantially parallel to and run along with the direction of the cross-members 26. The reinforcing fibers used for the deck and cross-members will preferably contain a mixture of about 40-60% by weight continuous uni-directional fibers, and about 10-30% by weight veil mat or woven roving. The continuous, uni-directional fiber alignment provides exceptional strength and support, and increases the stability and load bearing strength. In addition, the fiber combination and alignment provides superior material properties such as a compressive strength greater than 200 MPa, a flexural strength greater than 200 MPa, a flexural modulus greater than 10 GPa and an Izod impact lengthwise of 20.

The thickness and density of the pultruded materials may be varied depending on the load characteristics and strength requirements of the pallet. In one preferred embodiment, the decks have a gradient-type surface thickness, with edges and other high stress point areas having the thickest regions. It is preferable that the thickness of the pultruded main deck 24 and cross-members 26 averages between about 2 and 7 millimeters, more preferably between about 3 and 5 millimeters.

Like with most thermoset polymeric materials, the pultruded pallet is inert compared with many thermoplastic polymers. The pultruded pallet has excellent resistance to chemicals, including strong solvents. The heat deflection temperature is generally above 200° C., and like other thermoset materials it has superior dimensional stability. Combined with uni-directional aligned glass fibers, the pultruded pallet has a preeminent strength to weight ratio of about 200. Material benefits include a light weight modular design that is OHSA compatible. The thermoset resin may contain various functional fillers; non-limiting examples include: fire retardants, colorants, carbon fiber, metal fiber, and biodegradation agents, etc. Additionally, the pallet is recyclable to itself as a filler. It is designed for food compliance (FDA, USDA, and NSF) and is not moisture or odor absorbent. The pallet also has the capability of being fitted with RFID technology.

Focus is now directed to the method of making a pultruded pallet 20 of the present invention having a unitary main deck 24 with supporting cross-members 26a, 26b. The pultrusion process involves pulling raw materials through a heated steel forming die using a continuous pulling device as known in the art. According to one preferred method, reinforcement materials such as continuous strands of glass, woven roving or fiber mat veil are oriented as desired through a guide plate into a preferred formation. The fibers are then saturated and combined with a resin matrix by a resin impregnator. The saturated resin mixture includes resin, fillers, pigment, and catalyst in addition to any other additives as required. The resin impregnator optimizes the complete saturation of the fiber reinforcements and feeds the material into an array of tooling that removes excess resin and shapes the material prior to entering a die. Once in the die, and under proper heat, the glass/mat resin matrix polymerizes with the thermosetting resin forming a deck with unidirectional fibers extending parallel along the frame as it is pulled through the rectangular frame die to form a single piece deck with a plurality of longitudinal cross-members extending there from. The pultruded main deck is preferably formed with one die although multiple dies and construction options could be employed. The resulting pultrusion is then cut to the desired size. Additional end support members 30, 32, 34, 40 are separately pultruded and attached with structural adhesive, metal rivets, composite brackets or the like.

The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Claims

1. A pultruded pallet comprising:

a substantially planar deck having a plurality of parallel structural supporting cross-members extending substantially perpendicular therefrom, the deck and extending cross-members being integrally formed from a monolithic piece of pultruded material.

2. A pallet according to claim 1, wherein the pultruded material comprises a fiber reinforced thermosetting resin including at least one of a glass mat, fiber mat, and woven roving material.

3. A pallet according to claim 2, wherein the thermosetting resin comprises a mixture of about 40 to about 60% by weight of continuous uni-directional fibers and from about 10 to about 30% by weight of veil mat or woven roving material.

4. A pallet according to claim 1, wherein the deck has an average thickness of between about 3 and about 5 millimeters.

5. A pallet according to claim 1, wherein the deck comprises a plurality of spaced apart apertures.

6. A pallet according to claim 1, wherein the plurality of extending cross-members comprises a center member and two side members.

7. A pallet according to claim 1, further comprising at least one pultruded end cap mechanically fastened to the deck and disposed-perpendicular to the cross members.

8. A pallet according to claim 7, wherein the at least one pultruded end cap comprises a substantially “C” shaped cross-section.

9. A pallet according to claim 1, further comprising a pair of elongated fastening devices configured to secure goods placed on the deck.

10. A pallet according to claim 9, wherein the fastening devices comprise first and second pultruded extension brackets configured to cooperate with one another to provide a variable length.

11. A pallet according to claim 10, wherein the extension brackets are telescopically coupled to one another for coordinated slidable movement to provide a variable length.

12. A pallet according to claim 9, wherein the fastening devices further comprise at least one protruding retaining member.

13. A pallet according to claim 9, wherein the fastening devices further comprise at least one groove or recess formed therein.

14. A pallet according to claim 9, further comprising at least one retaining strap configured to secure the fastening devices to goods placed on the pallet.

15. A system for shipping goods, the system comprising:

a pallet comprising a pultruded main deck and a plurality of pultruded structural supporting cross-members;

a pair of pultruded fastening devices configured to secure goods placed on the pallet; and

at least one retaining strap,

wherein the deck, cross-members, and fastening members comprise a fiber reinforced thermosetting resin and the at least one retaining strap is configured to secure the fastening devices to the goods.

16. A system according to claim 15, wherein the main deck and cross-members are integrally formed from a monolithic piece of pultruded material.

17. A system according to claim 15, wherein the main deck and cross-members are separately pultruded and mechanically fastened having a rectangular frame.

18. A system according to claim 15, further comprising a second retaining strap configured to secure the fastening devices to the pallet.

19. A system according to claim 18, wherein at least one of the supporting cross-members comprises a tubular cross-section the second retaining strap is wrapped around the fastening devices and passes through the cross-member.

20. A system according to claim 15, wherein the thermosetting resin comprises a mixture of about 40 to about 60% by weight of continuous uni-directional fibers and from about 10 to about 30% by weight of veil mat or woven roving material.

21. A system according to claim 15, wherein the pallet comprises at least one pultruded end cap mechanically fastened to the main deck and disposed perpendicular to the cross members.

22. A system according to claim 15, wherein each fastening member comprises two extension brackets telescopically coupled to one another for coordinated slidable movement to provide a variable length.

23. A system according to claim 15, wherein the fastening devices further comprise at least one protruding retaining member or recess configured to secure the at least one retaining strap.

24. A system according to claim 15, wherein the goods comprise sheets of glass.

25. A method of making a pultruded pallet, comprising:

preparing and blending a resin mixture;

aligning reinforcement materials through a guide plate into a predetermined formation and saturating the reinforcement materials with the resin mixture;

passing the saturated reinforcement materials through a frame die and pultruding an elongated monolithic component; and

cutting the monolithic component to a desired size.

26. A method according to claim 25, further comprising:

pultruding an elongated end cap component;

cutting the end cap component to a desired size; and

mechanically fastening the end cap to the monolithic pallet component.

27. A method according to claim 25, wherein the monolithic component comprises a deck having a plurality of parallel structural supporting cross-members extending substantially perpendicular therefrom.