Patent Publication Number: US-6659019-B2

Title: Folding pallet-stacking device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The invention is related to U.S. application Ser. No. 09/420,431, filed Oct. 12, 1999, now U.S. Pat. No. 6,530,476, entitled “Pallet Stacking Device,” which is assigned to the assignee of the invention. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The invention relates to a pallet-stacking device which maximizes the vertical stacking capability of adjacent pairs of loaded pallets. 
     2. Background Information 
     Bottle-carrying crates or “carriers” are typically stacked in vertical sets on top of pallets to create three-dimensional “container arrays.” For example, bottle carriers filled with blow-molded plastic bottles are often stacked in perhaps three to seven layers atop a given pallet. Such bottle carriers typically define bottle seats in an upper surface within which to receive the base portion of each bottle, and recesses in a lower surface within which to receive the tops of the bottles carried in the next-lower bottle carrier. Alternatively, cardboard or molded-plastic tier sheets are often used to separate each bottle carrier layer. Such a pallet loaded with stacked bottle carriers is conveniently handled by a forklift for shipment or storage. 
     Because vertical space in a warehouse is significantly less expensive than floor space, it is desirable to stack fully-loaded pallets vertically as high as possible. However, various problems arise in stacking loaded pallets directly on top of other fully loaded pallets, including those associated with the possible uneven loading of the top layer of exposed container tops by the three horizontally-spaced slats that typically define the bottom surface of a wooden pallet; and the resulting stack of pallets frequently lacks the desired stability. 
     Under one prior art approach to increase the stacking capacity of fully-loaded pallets, as taught in U.S. Pat. No. 5,016,761 to Stoddard et al., a “top cap member” is secured on top of the loaded pallet to provide a stable supporting surface for another pallet. The top cap member is formed from a monolithic plastic sheet of uniform thickness that is deformed to provide raised lands on its upper surface and corresponding dimples on its lower surface (the dimples being positioned to receive the tops of containers forming the uppermost layer of the loaded pallet). The presence of the underside dimples makes sliding the top cap member laterally across the uppermost layer of container tops more difficult when preparing the loaded pallet for stacked storage or display. 
     According to another prior art approach, as taught in U.S. Pat. No. 5,894,804, a two-ply, pliable separator sheet is used to separate the layered pallets. The upper surface includes raised nubs while the lower surface includes corresponding concavities. Because the sheet is pliable, the nubs that engage the underside of the upper pallet collapse under its weight to thereby ensure that the pallet&#39;s load is not borne exclusively by the nubs. The separator sheet&#39;s other, noncollapsed nubs form a “raised barrier” resisting sliding movement of the upper pallet relative to the lower pallet. The lower ply material is also said to have a relatively greater coefficient of friction than that of the upper ply material, to thereby allow the lower surface to “grip” the cargo loaded on the lower pallet. Unfortunately, the pliable aspect of such separator sheets makes handling and storage of such sheets more difficult, while the “grippy” lower ply makes it more difficult to slide the sheet across the top of the lower pallet prior to stacking the upper pallet on top of the sheet. Still further, the use of two materials necessarily increases the cost and complexity associated with production of such separator sheets. And, lastly, the pliable nature of such separator sheets limits the stability of the resulting pallet stack because the sheet can only serve to prevent splaying of the lower pallet&#39;s cargo and does not otherwise serve to improve the quality of the surface upon which the upper pallet rests. 
     SUMMARY OF INVENTION 
     It is an object of the invention to provide a durable pallet-stacking device that is useful in optimizing the height to which loaded pallets can be vertically stacked. 
     It is also an object of the invention to provide a durable pallet-stacking device that improves the quality of the surface upon which an upper pallet of a stack of pallets rests. 
     Yet another object of the invention is to provide a pallet-stacking device that can be used to improve the stability of adjacent stacks of loaded pallets and, yet, can assume a more compact form for storage between uses. 
     Under the invention, an article or device for use in stacking adjacent pairs of pallets loaded, for example, with stacked container arrays includes a pair of interconnected sections. Each section of the device has a generally flat bottom surface adapted to rest on top of a respective loaded pallet, for example, the container tops of an uppermost layer of the container array. Each section of the device also has a top surface that includes a plurality of raised surface features on which to support another pallet, and a first edge including a plurality of hinge components from the group consisting of a first hinge component and a second hinge component. By way of example only, in an exemplary embodiment, the first and second hinge components respectively include a pivot pin and a pin grip that, preferably, are formed such that the two sections can be snapped together when one section is disposed at a predetermined angle, such as a 90° angle, relative to the other section. In accordance with a feature of the invention, an uppermost portion of each raised surface feature of each section lies within a respective first reference plane, with the first reference plane being in a substantially parallel-spaced relation to the bottom surface; and the hinge components of the sections cooperate to interconnect the sections for relative pivoting movement about a pivot axis that lies beneath the respective first reference plane of each section. 
     Most preferably, the surface features of the top surface include a plurality of raised portions or lands separated by a plurality of lowered portions or valleys. In an exemplary embodiment, the raised portions extend in a direction generally perpendicular to the pivot axis, with the resulting parallel-spaced raised lands extending substantially across a longitudinal dimension of the section. In accordance with another feature of the invention, the surface features of the first section are preferably complementary to the surface features of the second section, and the pivot axis preferably lies between the first reference plane defined by the raised lands and a second reference plane that intersects the lowermost portions of the valleys on the top surface of each section. In this manner, the raised portions of the first section oppose the lowered portions of the second section when the first section is pivoted on top of the second section, thereby providing the folded device with a compact form that is well suited for stacked storage. Most preferably, the first and second sections have a substantially identical shape to facilitate manufacture and lower the cost of the device using, for example, two identical, injection-molded plastic sections. 
     In accordance with yet another feature of the invention, the hinged edge of each section also includes one or more respective edge features that together cooperate to restrict relative pivoting movement of the first and second sections about the pivot axis, thereby improving device rigidity when opened. While the invention contemplates any suitable combinations of edge features for restricting such relative pivoting movement, an exemplary embodiment includes lateral features defined on the pin grips of one section that resiliently engage side surfaces defining the cut-out region of the other section adjacent to the pivot pin. The exemplary embodiment also includes cooperating edge features that define a detent, for example, a tongue and slot arrangement, for locking the first section relative to the second section about the pivot axis when the bottom surface of the first section is substantially coplanar with the bottom surface of the second section. The exemplary embodiment further includes cooperating edge features that abuttingly engage as the bottom surface of the first section is urged into a substantially coplanar relationship with the bottom surface of the second section. 
     In accordance with still another feature of the invention, each section of the device further includes a small lip extending along a second edge that is opposite the hinge, and that projects downwardly beneath the bottom surface of the section. The lip advantageously prevents longitudinal sliding movement of the device after the device is positioned atop and across a pair of adjacent loaded pallets, while the otherwise generally flat bottom surface of the device facilitates the lateral insertion, removal and alignment of the device atop and across the loaded pallets. The device further includes a plurality of handles that are integrally defined in each section, preferably along each longitudinal edge of the device. The handles further facilitate the lateral insertion and removal of the device and, when defined in each section such that the handles of the first section are generally aligned with the handles of the second section when the first section is pivoted on top of the second section, the handles conveniently facilitate handling of the folded device. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a perspective view of a pair of adjacent stacked pallets employing a folding pallet-stacking device in accordance with the invention; 
     FIG. 2 is a perspective view of the device of FIG. 1, showing with the device&#39;s first section pivoted roughly halfway toward the open position relative to the second section; 
     FIG. 3 is an enlarged view of a hinge formed by the respective hinge components of the first and second sections of the device when positioned as illustrated in FIG. 2; 
     FIG. 4 is an enlarged view of the hinge shown in FIG. 3 once the device&#39;s two sections are fully opened to thereby place the bottom surfaces of the two sections into a substantially coplanar relationship; 
     FIG. 5 is a top plan view of the device when the device is fully opened; 
     FIG. 6 is a side elevational view of the device when the device is fully opened; 
     FIG. 7 is a bottom plan view of the device when the device is fully opened; 
     FIG. 8 is an end view of the opened device, better illustrating the parallel-spaced lands and valleys defined in the top surface of each section; and 
     FIG. 9 is an end view of the device from the same vantage point as that of FIG. 8, but with the first section of the device now pivoted on top of the second section. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is an illustration of a pair of adjacent stacks  10 , 12  of pallets  14  that are each loaded with multi-layer container arrays  16  using conventional bottle carriers  18 . In accordance with the invention, a first foldable pallet-stacking device  20  is positioned between the first and second vertical tiers  22 , 24  of pallets  14  to thereby impart substantially greater stability to resulting pallet stacks  10 , 12 , while a second and identical foldable pallet-stacking device  20  is placed atop the second tier  24  of pallets  14  in anticipation of receiving yet another stacked tier of loaded pallets (not shown). As seen in FIG. 1, under the invention, the device  20  advantageously promotes load stability by laterally tying together the adjacent stacks  10 , 12  of pallets  14 . 
     Referring to FIGS. 2-9, the device  20  includes two sections  26 , 28  that are pivotally interconnected along a pivot axis  30  by a plurality of hinge components  32 , 34  that are defined in a respective first edge  36  of each section  26 , 28 . As seen in FIG. 2, the pivotal interconnection of the device&#39;s first and second sections  26 , 28  allows the device  20  to be conveniently folded about the pivot axis  30 . As discussed below, the top surfaces  38  of each section  26 , 28  cooperate with the relatively-high position of the pivot axis  30  to thereby provide the resulting folded device  20  with a generally rectangular cross-section that is itself well suited for stacked storage, as illustrated in FIG.  9 . 
     Returning to FIGS. 1-7, each section of the exemplary device  20  includes a grid structure  40  that is conveniently formed of any suitable injection-molded plastic such as a polypropylene. As best seen in FIGS. 6,  8  and  9 , the lower portions of the grid structure  40  define a generally flat bottom surface  42  on each section  26 , 28 . The generally flat bottom surface  42  is thus adapted for easy sliding placement atop a given tier of adjacent pallets  14 , and is preferably free of any raised or lowered portions which otherwise might make it more difficult or tedious to align the device  20  atop the two adjacent pallets  14 . However, a small, downwardly-projecting retaining lip  44  is preferably defined on the bottom of each section  26 , 28  along a second edge  46  opposite the first edge  36 , thereby defining a pair of such retaining lips  44  on opposite longitudinal ends of the opened device  20 , as best illustrated in FIGS. 6 and 7. The retaining lips  44  advantageously prevent longitudinal sliding movement of the device  20  once the device  20  is positioned atop and across a tier  22 , 24  of loaded pallets  14  while otherwise permitting lateral insertion and removal of the device  20 . The retaining lips  44  further advantageously facilitate alignment of the device  20  atop and across the loaded pallets  14 . 
     As best seen in FIGS. 2-4 and  8 , the grid structure&#39;s vertical ribs  50  are of varying heights and thus the tops of the vertical ribs  50  cooperate together to define the top surface  38  on each section  26 , 28  that is characterized by a plurality of parallel-spaced raised portions or lands  52  that together define a first reference plane  54  that is in parallel-spaced relation with the section&#39;s generally flat bottom surface  42 , with the lands  52  being separated by a plurality of lowered portions or valleys  56 . It will be appreciated that the grid structure&#39;s pattern of vertical ribs  50  and cross-ribs of each section  26 , 28  further serve to provide the device  20  with enhanced structural rigidity and integrity while otherwise serving to reduce the overall weight of the device  20 . The open nature of the grid structure  36  further advantageously permits device cleaning and drainage. 
     While the lands  52  and valleys  56  on the top surface  38  of each section  26 , 28  may be of any suitable configuration, in the exemplary device  20  as shown in FIGS. 2 and 8, the lands  52  each extend in a direction generally perpendicular to the pivot axis  30 , with the resulting parallel-spaced lands  52  extending substantially across a longitudinal dimension of the section  26 , 28 . These parallel-spaced, coplanar lands  52  provide a stable support surface upon which the next tier  24  of pallets rests (as illustrated in FIG.  1 ). 
     And, as seen in FIGS. 2 and 8, in order for the device  20  to assume a compact form when the first section  26  is folded or pivoted atop the second section  28 , the top surface features (the lands  52  and the valleys  56 ) of the first section  26  are complementary to the surface features of the second section  28 , and the pivot axis  30  of the device  20  lies between the first reference plane  54  defined by each section&#39;s lands  52  and a second reference plane  58  that intersects the lowermost portions of the valleys  56  defined on each section&#39;s top surface  38 . In this manner, the lands  52  of the first section  26  oppose the valleys  56  of the second section  28  when the first section  26  is pivoted on top of the second section  28 , resulting in the compact form illustrated in FIG. 9 that is well suited for stacked storage. 
     Most preferably, the first and second sections  26 , 28  have a substantially identical shape to facilitate manufacture of the device  20  using, for example, two identical, injection-molded plastic halves. Thus, to manufacture the exemplary device  20 , a single mold is advantageously used to make each of the two sections  26 , 28 , which are thereafter pivotally interconnected to each other along their respective first edges  36 . 
     As best seen in FIGS. 3-5 and  7 , while the invention contemplates any suitable hinge construction by which to pivotally interconnect the first  26  section with the second section  28 , the hinge components of each section of the exemplary device  20  include pivot pins  32  that extend across a respective cut-out region  60  of the first edge  36 , and projecting pin grips  34 . The pin grip  34  preferably includes an opening  62  by which to removably-secure or “snap” the pin grip  34  about the pivot pin  32 , thereby facilitating assembly of the device  20 , for example, when the first section  26  is disposed roughly at a 90° angle with respect to the second section  28  (as illustrated in FIG.  2 ). It will be appreciated that the hinge components of each section  26 , 28  are intended to cooperate such that the first section  26  can be pivoted relative to the second section  28  between a first, “device-open” position, with the first section&#39;s bottom surface  42  nominally coplanar with that of the second section  28  (as illustrated in FIG.  1 ), and a second, “device-folded” position, with the first section&#39;s bottom surface  42  in a substantially parallel relation with the bottom surface  42  of the second section  28 . 
     In order to increase the rigidity of the device  20  when opened, for example, to facilitate automated movement of the device  20 , each pin grip  34  of the exemplary device  20  includes a pair of oppositely- and laterally-extending fingers  64  that resiliently engage corresponding side surfaces  66  of the cut-out region  60 . The hinged edge  36  of each section  26 , 28  also includes a plurality of tongues  68  and corresponding slots  70  that define a series of “snap-fitting” detents along the hinge of the device  20  that operate to lock the first section  26  relative to the second section  28  about the pivot axis  30  when the bottom surface  42  of the first section  26  is substantially coplanar with the bottom surface  42  of the second section  28 . As seen in FIG. 4, the device  20  further includes cooperating edge features  72 , 74  that abuttingly engage as the bottom surface  42  of the first section  26  is urged into a substantially coplanar relationship with the bottom surface  42  of the second section  28 , thereby further serving to maintain the coplanarity of the sections  26 , 28  of the opened device  20 . 
     As best seen in FIGS. 5 and 7, the grid structure  34  of each section  26 , 28  of the device  20  further serves to define a pair of integral handles  76 , whereby the opened device  20  is provided with handles  76  on each of its lateral edges  78  to facilitate handling of the device  20 , including its placement atop a given tier  22 , 24  of adjacent pallets  14 . The handles  76  are preferably defined in each section  26 , 28  such that, upon the folding of the device  20  for storage, the handles  76  of the first section  26  are generally aligned with the handles  76  of the second section  28 , thereby further facilitating handling of the folded (closed) device  20 . 
     While one embodiment of the invention has been illustrated and described, it is not intended that this embodiment illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and various changes may be made within the scope of the appended claims. For example, while the pallet-stacking device is illustrated in FIG. 1 as separating each layer of loaded pallets, it will be appreciated that the device can conveniently be used to separate vertical pairs of loaded pallets to thereby facilitate use of a twin forklift that is capable of simultaneously lifting and transporting two vertically-stacked pallets, whereby the pallets are moved more quickly and efficiently about the warehouse.