This disclosure relates to pallets for shipping goods, and more particularly to a corrugated paperboard pallet.
Pallets are said to move the world. Eighty percent of commerce ships on Pallets. The pallet industry is estimated at greater than $30 B worldwide. More than 500 million pallets are manufactured in the US each year, with 1.8 billion pallets in service in the US alone.
Pallets can be made from various materials; however, wood pallets currently comprise about 80% of the market. More than 40% of worldwide hardwood lumber currently goes toward the manufacturing of wood pallets. Other materials used for pallet manufacturing include plastic, metal, and corrugated paperboard.
Recent regulations regarding infestation and contamination are creating a surge in interest and use of non-wood pallet alternatives. A small, but fast growing segment is the use of corrugated paperboard pallets. Many desire to replace conventional wooden pallets with corrugated pallets: increasing ability to recycle, lowering pallet weight, eliminating product contamination, reducing pallet storage volume, and reducing pallet related injuries.
Many different designs of corrugated paperboard pallets have been developed to date. Despite the potential advantages of corrugated pallets, most have suffered from several different deficiencies. These deficiencies include low strength and stiffness, high use of corrugated paperboard, resulting in high material costs, along with high overhead, assembly labor and freight costs. The inherent inability to readily produce and distribute corrugated pallets in sufficiently high volume has also been of critical importance.
Accordingly, a new corrugated pallet is needed that can provide increased strength and stiffness for use in widespread shipping, minimize corrugated use for low material costs, and that can be readily produced for the high volume consumables market, while reducing logistics costs.
The present disclosure provides a corrugated paperboard pallet that has high strength and stiffness and is produced using a minimal amount of paperboard material, reducing material costs. The corrugated pallet provides strong and stiff load support, utilizing fully recyclable corrugated paperboard. The pallet reduces costs by utilizing only two flat blanks and by minimizing the amount of material required. The corrugated pallet further enables high volume production by uniquely being completely machine assemblable with a low cost machine on site at a shipping facility. The pallet is constructed from only two die cut blanks. Of unique importance, the blanks may be shipped knock down flat directly from a corrugator to a shipper for simple and rapid assembly on site. The design of the corrugated pallet enables 100% machine assembly using a relatively compact, low cost, and reliable assembly machine. These factors enable the corrugated pallets to be readily produced in high volume for future widespread use.
The corrugated paperboard pallets are produced from two flat blanks which comprise a pallet top and a pallet bottom. The blanks are each folded to produce only two parallel, vertically extending, double thickness ribs, three horizontal panels, two vertical sidewalls, and two horizontal flaps. The ribs of the pallet top and the pallet bottom lock each other from opening in the center of the pallet by intersecting perpendicularly with notches. The intersection of the ribs prevents any of the ribs from flattening out. The horizontal flaps lock the ribs from opening at the edges of the pallet by intersecting perpendicularly with notches. The vertical sidewalls comprise vertical flaps that open inward defining fork passages whereby the vertical flaps lock the horizontal flaps from opening.
We have found that it is desirable to have only two ribs as opposed to three or more per blank in a corrugated paperboard pallet for several reasons. One reason is that having only two ribs can greatly simplify the construction of an assembly machine to assemble the pallets. Machine assembly of the pallet can be accomplished by clamping a blank on opposite sides of a rib to be formed and bringing opposite sides together. Using more than two ribs per blank will require both horizontal sides of a single rib to move. This makes assembly very complicated, expensive and less reliable. With only two ribs per blank, one side of each rib may be held fixed such that motion is not required on both sides. We have found that if a pallet could be designed to be structurally sound using only two ribs per blank, this would dramatically simplify the construction of a pallet assembly machine.
A second reason that the use of only two ribs per blank in a corrugated pallet design is preferable is because it reduces the area of corrugated board used in the pallet. We have found that a design with two ribs per pallet blank can reduce raw material costs by 20% per pallet when compared to a corrugated pallet design with four ribs per pallet blank. We have found that it is possible to meet the requirements of at least 70% of the shipping market, namely fast moving consumables, with a two rib per blank pallet by using features described herein.
A pallet is used for shipping and supporting loads above floor level by vertically transferring load from the pallet top to the pallet bottom. The notches in the ribs are preferably dimensioned so that the tops of the bottom ribs contact the underside of the pallet top, and the bottom edges of the top ribs contact the top side of the pallet bottom, optimizing vertical support of the pallet top against vertical loads of the cargo placed on the pallet. An additional benefit of the vertical flaps of the sidewalls is that they define the outer edges for easy fork entry either by a forklift or pallet jack operator. In a further embodiment, the vertical flaps of the sidewalls can provide additional transfer of load between the pallet bottom and the pallet top. These vertical flaps increase the working load capacity and rating of the corrugated paperboard pallet.
Pallets support loads at rest, allow loads to move while supported on forks, and they can also support loads in motion by the pallet moving over rollers. Additionally, loads may move relative to a pallet when the pallet is being loaded and unloaded. For these reasons, it is preferable that the top and bottom surfaces be smooth. In an additional embodiment of the present disclosure, the adjacent panels of the three horizontal panels of the pallet top and the pallet bottom abut each other without overlapping and the ribs are locked without the use of adhesive. Particularly, it is desirable to have panels that do not overlap on the top and bottom surfaces of the pallet. With the horizontal panels abutting without overlapping, no protruding ledges are produced that could hang up motion of loads on the pallet during loading and unloading. Likewise, the pallet's smooth surfaces enable ease of travel over rollers, if and when required.
It is desirable to eliminate the use of adhesive in the pallet assembly because adhesives increase costs, increase complexity, and reduce reliability of the pallet assembly machinery and they can make the pallet assembly messy. It is preferable to lock the vertically extending ribs of the pallet without the use of adhesives. This can be accomplished without overlapping horizontal panels through the use of the locking center and edge notches of the corrugated pallet.
It is desirable to make as strong a pallet as possible, but at the same time, it is desirable to minimize the amount of paperboard used, in order to minimize raw material cost. One of the most difficult loading conditions of a corrugated pallet is an unbalanced weight distribution, causing torsion or bending. Handling these conditions using minimal material in the pallet is a goal of corrugated paperboard pallet design. In yet a further embodiment of the present disclosure, the strength and torsional stiffness are greatly increased in these loading conditions by overlapping the corners of the horizontal flaps over the pallet top and the pallet bottom and locking into the pallet top and the pallet bottom from the top and bottom surfaces of the pallet. These corner straps have been found to increase the torsional stiffness and strength of the corrugated pallet by more than 85%. Locking into the top and bottom makes the top and bottom surfaces at the corners not smooth, however the increased load capacity and structural integrity gained outweighs this deficiency. Prior art methods of locking a pallet top to a pallet bottom through the use of straps that locked on the sidewalls, instead of the top and bottom surfaces of the pallet, resulted in flat pallet blanks that were not rectangular and had protruding elements. We have found that these protruding elements on the blanks make shipping the blanks difficult and unreliable because they are very easily damaged in shipping, even when blanks are shipped in stacks. Designs with these protruding elements require greater areas of material and more waste. The protruding elements can easily snag, making them incompatible with simple and reliable machine assembly of the pallet. The present disclosure uniquely overcomes these issues by utilizing the corners of the horizontal flaps overlapping the pallet top and the pallet bottom and locking into the pallet top and the pallet bottom from the top and bottom surfaces of the pallet.
In all conditions where the pallet is not being lifted, the load is being transferred from the top surface of the pallet to the bottom surface of the pallet, typically residing on the floor. This transfer of load is facilitated by the vertical ribs, vertical sidewalls, and vertical flaps. The compression strength of the vertical members directly impacts the ability to transfer load.
Because of the pallet design, the rib direction and sidewall direction are both the same; therefore, the higher compression strength direction of the corrugated paperboard can be utilized advantageously. Accordingly, the higher compression strength direction of the paperboard, the cross machine direction, preferably aligns vertically in these sections and is perpendicular with the direction of the ribs across the pallet tops and bottoms. In an additional embodiment of the present disclosure, the cross machine direction of the corrugation of the pallet top and the pallet bottom is made perpendicular to the direction of their respective ribs.
Besides high torsion stiffness, strength for lifting unbalanced loads, locking the pallet top to the pallet bottom provides other benefits. These benefits include reliability and resistance against the pallet loosening from vibration during shipping. Having a portion of the horizontal flaps to overlap the pallet top and pallet bottom of the pallets and lock in from the top and bottom surfaces of the pallet, whether at the corners or other positions along the edge, greatly increases the structural strength and reliability of the pallet. In further embodiments, the added locking of the pallet top to the pallet bottom can occur in any locations along the sidewall edges. In this embodiment, the horizontal flaps lock the ribs from opening at the edges of the pallet by intersecting perpendicularly with notches in the rib ends, and a portion of the horizontal flaps overlap the pallet top and the pallet bottom and lock into the pallet top and the pallet bottom from the top and bottom surfaces of the pallet.
The distributed load carrying capacity of a corrugated paperboard pallet is a function of the plate bending stiffness of the top and bottom surfaces and also primarily the rib and sidewall support that transfers load between the pallet top and pallet bottom. It is desirable to minimize the number of vertical ribs and use only two vertical ribs per pallet top and per pallet bottom so that paperboard use is minimized along with costs, as well as simplifying assembly machine construction. Fewer vertical ribs resultantly and undesirably increases the span between ribs, but we have found that a two rib per top and bottom pallet design can meet the needs of the majority of shipping requirements if the width of the ribs are correctly proportionate to the width of the pallet sidewalls, and if the corrugated board has a sufficient non-crushed total flute thickness. In an additional embodiment of the present disclosure, the pallet top and the pallet bottom each have a non-crushed total flute thickness of greater than 5.6 mm, and each of the pallet top and the pallet bottom has an outside width of the ribs that is greater than ⅛th the outside width of their respective sidewalls.
In the construction of corrugated paperboard pallets, it is desirable to design the pallet so that it maintains integrity throughout shipping and handling conditions. We have found that one way to accomplish this goal is to design the pallet to utilize a multiple series of locks. For instance, one set of folds is locked by a lock, then a second lock prevents unlocking or disassembly of the first lock and so on. In this way, the pallet is not easily disassembled nor is it likely to fail in use. In an additional embodiment, portions of each blank engages the other blank to form locks that hold the pallet top and the pallet bottom in an integral locked-together pallet, and at least some of the locks arranged in series of at least three locks, such that a first lock is in tum locked against disengaging by a second lock, and the second lock is in turn locked against disengaging by a third lock. These locks in series are preferably geometrical mechanical locks, meaning that they can lock without the use of added adhesives.
In yet a further embodiment of the present disclosure, the blanks are folded together to produce the pallet whereby folds are locked from opening by serial geometric mechanical locks having a series of greater than two. In the pallet shown, there are four locks in series holding the pallet together. The top blank ribs are locked from opening by the bottom blank ribs. The top blank horizontal flaps lock the bottom blank ribs from opening. The top blank vertical flaps lock the top blank horizontal flaps from opening. The corner straps hold the pallet top and bottom together, thereby locking the top blank vertical flaps from opening.
The present disclosure and its many advantages and features will become better understood upon reading the following detailed description of the preferred embodiments in conjunction with the following drawings, wherein:
Turning to the drawings, wherein like reference characters designate identical or corresponding parts,
A schematic drawing of the pallet 30 of
A schematic drawing of the pallet 30 of
The pallet bottom 50 of the pallet 30 of
The pallet top 70 of the pallet 30 of
A schematic drawing of the pallet bottom 50 and pallet top 70 of the pallet 30 of
One end of the pallet 30 of
Once aligned, the pallet top 70 and pallet bottom 50 are compressed together. A schematic drawing of the pallet bottom 50 and pallet top 70 of the pallet 30 of
A schematic drawing of the pallet 30 of
A schematic drawing of the pallet 30 of
The final assembly step is locking the corners of the pallet 30. A schematic drawing of the pallet 30 of
Corrugated paperboard is constructed with two directions: machine direction which is the direction it is pulled during fabrication and cross machine direction which is perpendicular to it, and is the axial direction of the flutes inside the corrugated paperboard. A schematic drawing of the pallet bottom 50 of the pallet 30 of
Although many corrugated pallets are designed using a high amount of corrugated paperboard, the present disclosure even provides substantial savings compared to lighter two-piece type corrugated pallets. A comparison of the corrugated paperboard use per pallet between the prior art two piece pallet and the present disclosure is shown in
One of the most significant benefits of the present disclosure is that the blanks can be shipped flat and be easily assembled on site at a shipper, compared to prior art corrugated pallets that must be preassembled at an outside plant due to complexity. This greatly increases the number of pallets that can be shipped per truckload. The blanks may also be shipped directly from a corrugator or sheet plant to a product shipper without secondary transportation and logistics. A bar chart shown in
Besides the cost savings, the present disclosure also provides a stronger and stiffer pallet with increased reliability. A bar chart shown in
All relative and directional references (including: upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, side, above, below, front, middle, back, vertical, horizontal, and so forth) are given by way of example to aid the reader's understanding of the particular embodiments described herein. They should not be read to be requirements or limitations, particularly as to the position, orientation, or use unless specifically set forth in the claims. Connection references (e.g., attached, coupled, connected, joined, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other, unless specifically set forth in the claims.
It will be further understood by those skilled in the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to examples containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations).
While various aspects and examples have been disclosed herein, numerous modifications and variations of the described preferred embodiment will be apparent to those skilled in the art. Accordingly, the various aspects and examples disclosed herein are for illustration purposes and are not intended to be limiting, with the true scope and spirt being indicated by the following claims.
This application is a continuation of U.S. patent application Ser. No. 14/580,923, filed 23 Dec. 2014 and entitled “CORRUGATED PALLET,” which is a continuation of International Application No. PCT/US2013/000137, filed 20 May 2013 and entitled “CORRUGATED PALLET,” which claims the benefit of U.S. Provisional Patent Application No. 61/823,380, filed 14 May 2013, and the benefit of U.S. Provisional Patent Application No. 61/664,827, filed 27 Jun. 2012, all of which are hereby incorporated by reference in their entireties.
Number | Date | Country | |
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61823380 | May 2013 | US | |
61664827 | Jun 2012 | US |
Number | Date | Country | |
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Parent | 14580923 | Dec 2014 | US |
Child | 15420567 | US | |
Parent | PCT/US2013/000137 | May 2013 | US |
Child | 14580923 | US |