Abstract:
Stacking apparatus comprising a contour plug and an insert for stacking and securing a stack of irregularly contoured items. Contour plug and insert fit between two stacked items to hold them in alignment and prevent shifting; the insert has a loop for receiving a restraining strap. The stacking apparatus remains with a stacked product from manufacture to final delivery.

Description:
BACKGROUND INFORMATION  
         [0001]    1. Field of the Invention  
           [0002]    The invention relates to the field of handling elongate or unwieldy items, such as light-gage steel trusses and wall panels. More particularly, the invention relates to an apparatus for stacking such items and bundling the stack, and to a method of stacking and bundling such items for transportation.  
           [0003]    2. Description of the Prior Art  
           [0004]    Long and unwieldy products such as light-gage steel trusses and wall panels are fragile and subject to bending out of plane during manufacture and shipping. Metal trusses, which, when properly installed and braced, function as structural elements, may be particularly fragile. Such items are also very difficult and hazardous to handle. The shapes of such trusses and wall panels are often complex shapes having multiple planes, rather than simple rectangular or cylindrical shapes, and this makes it very difficult to stack or bundle them. Long trusses made of light-gage steel, for example, can flex to the degree that they become entangled in one another. It is difficult to know in advance if and what distortion of the stack or bundle of such items will occur when one item is moved or adjusted. As a result, attempts to stack and bundle such items often result in sliding or tumbling stacks of these long or large items. This creates a risk of injury to those in the vicinity of the stacks and as well as a risk of overstressing or breakage from distortion or damaging of the items themselves, thereby reducing their value and/or utility, even to the point of rendering them useless.  
           [0005]    Typically, such products are stacked and bundled together with metal strapping that is fastened to the products with self-tapping screws. In the case of trusses, the strapping is often constructed of scrap pieces truss webs, but other types of metal, woven, or adhesive strapping can be used. Stacking trusses is particularly difficult because a set of trusses often includes trusses of graduated sizes such that one outer beam or “chord” of the trusses can be stacked one atop the other, while one or more other chords do not stack on top of each other. Even when tightly bundled, irregularly shaped trusses or panels can shift within the bundle, causing the bundle to become unbalanced or unstable. For this reason, stacking and loading bundled products such as trusses or wall panels can be a very hazardous operation, and, consequently, handling such products becomes a time-consuming operation, as great care and additional measures must be taken to ensure the safety of the personnel handling the products during manufacture and loading, as well as to protect the products from damage during shipping and unloading.  
           [0006]    Attempts to simplify and improve the safety of handling very long or large and unwieldy products have focused on devices or systems for shipping and transportation. These include building frames or cribs to hold and support the items being shipped on a truck bed. This, of course, increases the cost of shipping and handling of such products, and has often proved to be ineffective. Furthermore, such devices or systems are typically operable only at the loading or shipping site, and are thus ineffective in improving the stability of the stack and safety of handling the products at the point of manufacture, as well as at the point of delivery.  
           [0007]    Miller (U.S. Pat. No. 4,496,270; (issued 1985) attempted to solve the problem of forming stable loads of elongate products on the flat bed of a truck by providing a pair of so-called “chain caps” that fit around two sides of an elongate product, such as an I-beam. These chain caps have an inner contour that conforms to the regular outer shape of the product, and an outer contour with ridges and spaces that allows the chain caps to fit one into the other when stacked one atop another. At least one pair of chain caps is fitted onto an item. The chain caps provide space for a tie bar to be inserted between the caps of items that are arranged side-by-side in horizontal rows, so as to prevent the stacked load from shifting in a direction perpendicular to the longitudinal axis of the tie rod. Several horizontal rows of beams are stacked upon each other, creating an array of horizontal and vertical rows. A restraining strap is passed around the bundle of items to encompass the vertical and horizontal rows to a bundle and is then fastened to each side of the vehicle. This prevents the load from shifting side-to-side.  
           [0008]    One of the disadvantages of the chain caps disclosed by Miller is that the caps must be arranged at the same location on each item to be stacked, in order for the caps to fit into one another and to provide a channel to receive the horizontal tie bars. A further disadvantage is that the caps are not suitable for supporting and stabilizing a load of irregularly-shaped or triangular items, such as, for example, light-gage steel trusses or wall panels. In many instances, the trusses or panels to be shipped will vary in size. Most often in cases where the product varies in size or length, the largest elongate item is positioned at the bottom with smaller items on top, decreasing in length or size as a stack is assembled. Generally, one plane of each item will be stacked above another parallel plane below. In other words, at least one plane is commonly and vertically stacked. It is imperative for the stacking devices that they be positioned to accommodate and support the trusses or panels. Miller requires proximity above and/or below each item to stabilize the different shapes. Furthermore, it is unduly time-consuming to have to fit two pieces of the chain cap onto each item and position it precisely so that it will stack properly with vertically adjacent items. Also, the caps are bulky and, accordingly, require a lot of material. No mention is made in the prior art of handling items of varying lengths.  
           [0009]    What is needed, therefore, is apparatus for safely and quickly stacking elongate and/or large unwieldy items such as trusses and wall panels, and for shipping and unloading such items. What is further needed is such apparatus that will provide a means for bundling and securing a stack of items. What is yet further needed is such apparatus that can be used to stack the items at the point of manufacture, that is versatile and adaptable to different types of loading or transportation conditions, easy to use, and cost-efficient with respect to time required to use the apparatus and material required to make the components of the apparatus. Finally, what is needed is apparatus that will stay with the items from the point of manufacture to the construction site.  
         SUMMARY OF THE INVENTION  
         [0010]    It is an object of the present invention to provide apparatus for stacking elongate or large and unwieldy items. It is a further object of the invention to provide such apparatus for securing and/or bundling such stacked items that will stay with the items from the point of manufacture to the point of delivery at the construction site. It is a yet further object to provide such apparatus that will allow the stacked items to be safely loaded on a transportation vehicle and will secure the items against shifting during transportation.  
           [0011]    The objects are achieved by providing apparatus that includes at least a support means and a restraining means. The support means is a contour plug having an outer contour that conforms to the contours of the items to be stacked or bundled. The restraining means is an insert that also conforms in shape to the items to be stacked, but further provides a securing means through which a restraining strap can be passed to hold the stacked items in place. The use of a combination of numerous yet inexpensive plugs and fewer yet more costly inserts allows the items to be stacked more cost-effectively and efficient with respect to material and labor costs than is possible with other conventional devices. An advantage of the apparatus according to the invention is that the contour plugs are less costly to manufacture than the inserts and can be used as needed to stack the items. These contour plugs, then, can be used directly at the point of manufacture to stack the products as they come off the production line, thereby reducing the risks from shifting or tumbling items or stacks of items and increasing the quality of the product by reducing the likelihood of bending, overstressing, or breakage of the new product.  
           [0012]    As mentioned above, the contour plug has a contour that conforms to the contours of those surfaces of the items that are stacked one atop the other. In a particular embodiment of a plug which will be shown and discussed later, the contour plug fits down into a channel of the irregularly-shaped truss that extends along one long side of the truss and which, because of its irregular geometry, makes the item very difficult to stack. The contour plug fills out that portion of the channel with plug material, thereby providing support and rigidity to the truss, as well as providing a base onto which another item can be stacked. A number of contour plugs can be fitted between any two stacked items, depending on the flimsiness of the items and the need to provide some rigidity to the items so that they are less likely to flex and become disengaged from one another.  
           [0013]    In a further embodiment of the invention, the stacking apparatus also includes a universal plug that may be used to support items of two different shapes that cross each other in a stack. For example, where one formed steel member crosses a member of a different formed shape, a universal plug having a lower part with the contour of the lower member, but a deformable upper part, is fitted onto the lower member where another member crosses it. The upper part of the universal plug adapts in shape to the contour of the upper member and, because it is firmly attached to the form-rigid lower part of the plug, provides a secure base for seating the upper member on top of the lower member.  
           [0014]    The contour plug according to the invention is made of extruded polystyrene, although other materials such as corrugated cardboard, wood, rubber, plant or animal fiber, or other synthetic materials can be used, as long as they are suitably stiff and strong to support the weight of the items being stacked without losing their ability to fit between and provide support for the items. In the case of the extruded polystyrene universal plug, the plug has material of two different densities, a higher density foam is used for the form-rigid lower part of the plug that fits into the contour of an item and a softer, lower-density foam for the upper part that will compress under the weight of the upper item, yet not cause the upper item to bend or buckle.  
           [0015]    The insert is used to secure the stacked items to a bundle. The insert in the preferred embodiment is made of thermoformed plastic, although other suitable materials, such as metal or woven carbon fibre/epoxy, can be used. Like the contour plug, this insert has an outer shape that conforms to the contours of the items being stacked. In one embodiment, the insert is formed as a planar sheet that is provided at its initial point of use as a stack of inserts. Each end of the sheet has a loop for receiving and holding a restraining means. The insert is folded in half upon itself, so that the loops of each end are placed one atop the other. The insert, when it is folded in this way, is a hollow shape that has a lower contour that corresponds to the upper outer contour and an upper contour that corresponds to the lower outer contour of the item being stacked. The insert is then placed on top of a first item, and a second item stacked on top of the insert. Because of the way the insert fits into the contours of the bottom item and the upper item, it holds the items securely in position. The double loop now extends outside of the stack and provides a means through which a restraining strap is insertable. Ideally, a set of two inserts is used at each end of a stack of items. For example, assuming a 12-high stack of trusses, a first insert is inserted between the first and second, and a second insert between the eleventh and twelfth items. Depending on the shape and flexibility of the items, more inserts may, of course, be used in the stack to provide additional stability. The loops for receiving the restraining strap of the inserts extend to the side of the stack that will be the outer side when the stack is bundled for shipping and transportation. A restraining strap is insertable through the loops and around the stack to secure it to a bundle. If the items are long and slender, for example, several stacks may be secured to a single bundle by aligning the stacks so that the insert loops of the respective outer stacks extend beyond the respective outer sides of the bundle. The strap can then be secured to the sides of a transport vehicle to secure the load on the vehicle.  
           [0016]    Each bundle of stacked items can now be safely handled from the point of manufacture to its final destination, including during intermediate stages at a storage facility, at a loading dock, on a truck bed, etc. The bundle can be lifted manually or with a fork-lift, or mechanically with a lifting crane that grabs the bundle by the loops. To ensure that the inserts do not pull out of the bundle when so lifted, the seating of the inserts within the stack can be reinforced by placing a plug in the hollow space of the insert. This prevents the insert from flattening during lifting and pulling out of the stack.  
           [0017]    The multi-piece stacking apparatus according to the invention offers distinct advantages over single-piece means for stabilizing a load. The less expensive plugs can be used randomly throughout the stack. That is to say, the plugs need not be aligned one above the other. Ideally, two plugs are used, one toward each end of an elongate item, and three or more may be used if the item is particularly long or particularly flexible and requires additional stabilization. The inserts, on the other hand, are used primarily to secure a stack to a bundle, and fewer of these will typically be used than of the plugs. Nevertheless, additional inserts can be used if particularly arduous shipping conditions are foreseeable.  
           [0018]    When stacking trusses, one or more plugs can be inserted on each chord of the truss. It is within the scope of the invention to use plugs not only between the chords of stacked trusses, but also between the inner beams or “webs”. Typically, it will not be necessary to provide plugs between the webs, since, when the trusses are stacked with plugs between the chords, the webs are automatically held in the proper alignment. Depending on the particular size, shape, flexibility of the truss, however, it may be desirable to insert “web” plugs between stacked trusses.  
           [0019]    When several bundles are to be stacked and secured on atop the other or beside each other, the inserts can easily be shifted within the stacks so as to properly align the loops for receiving a restraining strap. This is particularly advantageous when securing two bundles of trusses to a truck bed. The bundles can be placed in a complementary spatial arrangement that allows the chords of the trusses that extend along on the outer edges of the truck bed to be aligned in parallel to each other. This allows the restraining strap that secures the bundles to the truck bed to be inserted through the loops in a substantially vertical direction that is also perpendicular to the axis of the chord from which the insert loop extends. This reduces the lateral force exerted on the bundle and reduces the risk of the stack shifting within the bundle. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a cross-sectional view of a partial bundled stack of items, showing plugs and an insert according to the invention inserted in the stack of items that are bundled together by means of a restraining strap.  
         [0021]    [0021]FIG. 2 is a perspective view of a plug according to the invention.  
         [0022]    [0022]FIG. 3 shows the Preferred Embodiment of the insert according to the invention and how it is folded to provide the proper contour to provide a form-positive fit between two stacked items and double-strength loops for receiving a restraining strap.  
         [0023]    [0023]FIG. 4 shows a side view of a stack of items stacked according to the invention and ready for bundling.  
         [0024]    [0024]FIG. 5 is a cross-sectional view of a universal plug according to the invention.  
         [0025]    [0025]FIG. 6 is a plan view of a truck bed loaded with two bundles of trusses secured according to the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]    [0026]FIGS. 1 and 4 illustrate a stack formed by stacking apparatus  10  according to the Preferred Embodiment of the invention in combination with a stack of items  1 . The apparatus  10  comprises a contour plug  3  and an insert  2  for stacking and bundling the items  1 . The items  1  used in the FIGURES as a means to illustrate the stacking apparatus  10  are, by way of example, irregularly shaped light-gage steel trusses. As can be seen in the cross-sectional view of the stack shown in FIG. 1, these items  1  have an irregular upper contour  1 ′ and an irregular lower contour  1 ″ that make such items difficult to handle and stack. When stacking the items  1  one atop the other, the contour plug  3  is inserted between two vertically adjacent items  1  to keep the items  1  properly stacked. Depending on the length of the particular items  1  being stacked, several contour plugs  3  may be inserted at different locations, spaced apart along the length of the item  1 . To secure the stack of items  1  to a bundle, one or more inserts  2  are inserted in the stack. A stack of twelve items  1  having inserts  2  is shown in FIG. 4 as an illustration. Of the inserts  2 , one is a first insert  2 C and another one a second insert  2 D. The first insert  2 C is inserted between a first item  1 A and a second item  1 B. The insert  2 C has a restraining loop  2 A through which a restraining strap  4 , such as is conventionally used to bundle items for shipping and handling, may be passed to secure the stack to a bundle. See FIG. 1. The ends of the restraining strap  4  may be secured to each other to form an individual bundle of items, or to a transport vehicle, such as the flat-bed of a truck, to secure the bundle for transportation. The second insert  2 D is inserted between an eleventh item and a twelfth item, arranged analogously to the first insert  2 C, with the loops extending to the same side as the loops  2 A. As best seen in FIG. 6, in the Preferred Embodiment, the loops  2 A of the first inserts  2  are arranged along the side of the stack that will be along the outer edge of the truck bed when loaded for shipping.  
         [0027]    Although the contour plugs  3  are shown in FIG. 4 as being aligned in a column between the inserts  2 , it is not necessary to align them in this manner. In the Preferred Embodiment, the contour plugs  3  are placed approximately one below the other to provide the greatest rigidity and stiffness at the location where the restraining strap applies a compressive force to the bundle. It is an advantage of the stacking apparatus  10  according to the invention, however, that the contour plugs  3  do not have to be precisely aligned one below the other, because the restraining strap  4  is held by the inserts  2  and not by the contour plugs  3 . Also shown in FIG. 4 is a configuration in which only two inserts  2 C,  2 D are placed toward one end of the stack. Depending on the number of items  1  in a stack and the shipping and transportation conditions, the insert  2  may be inserted in intermediate locations in addition to those at the top and bottom of the stack. Furthermore, more than two straps can be used to restrain a stack to a bundle, and additional inserts will accordingly be placed in the stack.  
         [0028]    The contour plug  3  is shown in detail in FIG. 2. In the Preferred Embodiment of the stacking apparatus  10  according to the invention, the contour plug  2  is an extruded polystyrene component, although other suitable materials may be used, such as corrugated cardboard or other paper products, fiber products, rubber, wood, or other natural or synthetic materials that possess sufficient rigidity and form-retaining strength to maintain a substantially form-positive fit with the items  1  when they are stacked. As can be seen, the contour plug  3  is shaped to provide a positive fit with the upper contour  1 ′ of a second item  1 B and the lower contour  1 ″ of a third item  1 C. The contours of the irregularly-shaped item  1  are used to advantage on the contour plug  3  to provide a plug that holds the items in position and prevents shifting of the items in the axial direction. For example, ridges and grooves on the contour plug  3  correspond to respective grooves and ridges on the items  1 B and  1 C and provide a secure seating surface for the third item  1 C that is placed on top of the contour plug  3 . The contour plug  3  has a length dimension L that is sufficiently large to prevent the items  1  from shifting or canting axially out of position.  
         [0029]    [0029]FIG. 3 shows the insert  2 . In the Preferred Embodiment, the insert  2  is a thermoformed plastic sheet with a loop  2 A at each end of the sheet. Other suitable materials, such as corrugated cardboard or other paper products, stamped sheet metal, other synthetic materials, or other materials with sufficient strength and rigidity, may be used. As indicated by the dashed lines in FIG. 3, the insert  2  is folded to form a hollow shape that corresponds to the upper contour  1 ′ of the first item  1 A and the lower contour  1 ″ of the second item  1 B. In the Preferred Embodiment, the restraining loop  2 A is shown as a rectangular opening that is adapted to receive a restraining strap  4 . In other embodiments, the contours of the restraining loop  2 A are formed as a handgrip to allow workers to grab and lift a stack of items  1  bundled according to the invention. In another embodiment, the restraining loop  2 A is formed as a large cylindrical or oval loop to enable a mechanical hoisting device to grab onto the bundle.  
         [0030]    [0030]FIG. 5 shows a cross-sectional view of a universal plug  3 ′ having a lower part  3 C and an upper part  3 D. The universal plug  3 ′ is made of extruded polystyrene with the lower part  3 C having a density greater than that of the upper part  3 D. In the Preferred Embodiment, the density of the lower part  3 C and of the contour plug  3  is approximately 2.2 lb/ft 3 . The contour of the bottom part  3 C of the universal plug  3 ′ provides a form-positive fit with the item  1  it is placed into, and the upper part  3 D, which is formed of a softer deformable material, conforms somewhat to the contour of the item that is placed on top of it. In other words, the upper part  3 D has a density that allows it to be easily compressed by the item  1  that is stacked on top of it, without causing the item  1  to bend or buckle. This universal plug  3 ′ is of particular use, for example, when items of different shapes and sizes are stacked on top of each other. The stiffer bottom part  3 C provides good support and seating base for the upper item and the softer deformable upper part  3 D, which is attached to the lower part  3 C, holds the upper item in position. As stated earlier, it is within the scope of this invention to provide a contour plug  3  or a universal plug  3 ′ of different materials and densities, as long as the particular plug provides sufficient stiffness and a form-positive fit with at least the lower item to be stacked, in order to provide a secure seating for the item to be stacked on top of it.  
         [0031]    [0031]FIG. 6 illustrates an arrangement of two bundles of items  1  stacked according to the invention and secured to a flat-bed  9  of a truck. The item  1  is a truss formed of chords  7  and webs  8 . The items  1  have an irregular overall shape and have been divided into two bundles that can be arranged in a complementary arrangement on the truck bed  9 . As can be seen, plugs  3 , indicated by dotted lines, have been inserted between items  1  along the chords  7 . Depending on the configuration of the particular items  1  being handled, it may be desirable to use web plugs  3 A between items  1  along the webs  8 . The bundles are placed on the truck bed  9  so that the respective chords  7  of the items  1  that are perpendicular to the ends of the items  1  extend along the outer sides of the truck bed  9 . The inserts  2  of the two bundles have been aligned so that a restraining strap  4 , shown with dashed lines, is pulled across the two bundles and inserted through the loops  2 A of the respective inserts  2  as shown in FIG. 6. Thus, although each bundle is an irregular shape, the restraining strap  4  applies a substantially normal force across the bundles that does not apply a lateral force to one side of a bundle.  
         [0032]    The embodiment mentioned herein are merely illustrative of the present invention. It should be understood that variations in construction and use ofthe present invention may be contemplated in view of the following claims without straying from the intended scope and field of the invention herein disclosed.