Abstract:
A load container is formed of one or more plastic or plastic composite panels so that it is lighter than typical metal load containers and can be easily shipped and repaired. The load container can be part of a vehicle having a vehicle frame and at least one wheel supporting the vehicle frame by engaging the ground or a rail, for example. A load container frame is supported by the vehicle frame, and a plurality of the panels are secured to the load container frame with an edge of each panel adjacent an edge of another panel, possible with sealant or coupling media therebetween. Methods of making such wall panels and vehicles having load containers so formed as well as methods of repairing and assembling such load containers are also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims benefit to U.S. provisional application Ser. No. 60/404,065 filed on Aug. 16, 2002. 
     
    
     
       STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    1. Technical Field  
           [0004]    The present invention relates to load containers, and more particularly to load containers made of one or more generally plastic panels, and even more particularly to such load containers forming a part of transport vehicles.  
           [0005]    2. Description of the Related Art  
           [0006]    Containment devices, such as bins, hoppers and large silos, and large containers on transport vehicles, such as trucks and railcars, are often used to contain and transport bulk materials, such as powdered cement. Container trucks, for example, typically include a tractor which pulls a trailer having a load container fixed thereto. The load container is typically formed from a metal skin which defines a load container volume. The load, such as the powdered cement, is contained within the volume while being transported by the truck.  
           [0007]    The heavy metal load container increases the overall weight of the vehicle, and thus decreases the load capacity of the truck. Moreover, the increased weight reduces the fuel mileage of the vehicle, thus increasing operating costs for transporting the load. Non fluid loads being transported in the container can stick to the metal which complicates unloading the container. In addition, if a portion of the load container is damaged, the load container must be replaced or repaired.  
           [0008]    Replacing the damaged metal load container is very expensive. If the damage is minor, the damaged area can be cut out using a torch and a patch can be welded onto the exterior of the load container. If the load container had been transporting a powder or other explosive material, however, using a torch or welding equipment is extremely dangerous. Moreover, even with a patch, the repaired area is unsightly, and is a constant reminder of the prior damage.  
           [0009]    One known solution for reducing the weight of the load container is disclosed in U.S. Pat. No. 6,076,693 which discloses a molded, one piece, completely integral load container for transporting bulk materials. A large, molded, one piece, load container is extremely bulky and expensive to ship from the molder to a vehicle manufacturer for assembling with the vehicle. Moreover, if the load container is damaged, as in metal load containers, the entire container must be replaced or subject to unsightly repairs. Therefore, a need exists for a lightweight load container that can be easily shipped for assembling into a vehicle, and that can be easily repaired without leaving unsightly evidence of the repair.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention provides a vehicle having a load container which is lighter than typical metal load containers and which can be easily shipped and repaired. One or more plastic or plastic composite panels form a load container having a volume for containing a load, wherein each panel has at least one edge adjacent an edge of an adjacent panel.  
           [0011]    A general objective of the present invention is to provide a vehicle having a load container which is lighter than a metal load container having a similar volume and load capacity. This objective is accomplished by providing a vehicle having a vehicle frame supporting a load container frame onto which a plurality of plastic panels are secured to form a load container.  
           [0012]    Another objective of the present invention is to provide a load container vehicle suitable for use on existing roadways and railways. This is accomplished by the vehicle frame being a truck frame rotatably mounting a plurality of ground engaging wheels for contacting a ground surface, or a railcar frame rotatably mounting a plurality of rail engaging wheels riding one or more rails.  
           [0013]    Another object of the present invention is to provide a method of making a vehicle having a load container. This is accomplished by attaching at least one rotatable wheel and a load container frame to a vehicle frame, and then attaching a plurality of plastic panels in an edge to edge fashion to the load container frame to form the load container. Preferably, at least one of the panels is fixed to the load container frame by at least one bolt received in a countersunk hole formed in a surface of the plastic layer at the interior surface of the load container. The countersunk hole can be formed in the plastic layer so that the bolt(s) are capped by a non-metallic cap that is substantially flush with the interior surface of the load container.  
           [0014]    Another objective of the present invention is to provide a method for repairing a load container. This objective is accomplished by forming the load container using replaceable panels.  
           [0015]    Yet another objective of the present invention is to provide a composite wall panel, and method of making same, for use in making a load container. This is accomplished by pressing a reinforcement layer between two layers of plastic. In one preferred method this includes adhering a pre-pressed sheet to a reinforcement sheet and then pressing a plastic resin together with the adhered pre-pressed and reinforcement sheets so as to form a uniform homogenous composite. Preferably, the reinforcement sheet is metal and the sheet and resin are an ultra high molecular weight polyethylene, such as TIVAR®, preferably having a low coefficient of friction and other flow promoting properties. The plastic layers form the exterior and interior surfaces of the wall panel and thereby the load container. The reinforcement layer is preferably disposed entirely between the plastic layers so as not be exposed and thereby avoid corrosion.  
           [0016]    These and still other advantages of the invention will be apparent from the detailed description and drawings. What follows are preferred embodiments of the present invention. To assess the full scope of the invention the claims should be looked to as the preferred embodiments are not intended as the only embodiments within the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a side view of a vehicle incorporating the present invention;  
         [0018]    [0018]FIG. 2 is a perspective view of the vehicle of FIG. 1;  
         [0019]    [0019]FIG. 3 is a detailed cross-sectional view of a joint between the panels of FIG. 1;  
         [0020]    [0020]FIG. 4 is a detailed cross-sectional view of an alternative joint between panels of FIG. 1;  
         [0021]    [0021]FIG. 5 is a detailed cross-sectional view of another alternative joint between panels of FIG. 1;  
         [0022]    [0022]FIG. 6 is an exploded perspective view of a connection between the panels and load container frame of FIG. 1;  
         [0023]    [0023]FIG. 7 is a detailed cross-sectional view of an alternative joint between panels of FIG. 1; and  
         [0024]    [0024]FIG. 8 is a detailed cross-sectional view of a joint similar to that shown in FIG. 5 albeit for panels made of a reinforced plastic composite material. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    The present invention provides an improved plastic load container made of one or more plastic panels joined in an edge to edge fashion. The panels can be entirely plastic, or more preferably, can be a plastic composite having an internal reinforcement layer. The load containers can be used in stationary and transportable applications. For example, the load containers can be storage bins, hoppers, large silos or liners for silos. The load containers can also be part of a vehicle, including any transport machinery suitable for carrying loads, including but not limited to trucks and trailers having wheels engaging the ground or roadway and railcars in which the wheels engage one or more rails or tracks. The figures and the following description disclose a preferred load container vehicle.  
         [0026]    A vehicle  10 , described herein and shown in FIGS. 1 and 2 as a truck, includes a vehicle frame  12  supported by wheels  14  at one end and a tractor  16  at the other end. The vehicle frame  12  supports a load container  18  for containing a load, such as a powder, or other solid, a liquid, a gas, and the like. The load container  18  is formed from a plurality of generally non-metallic wall panels  20  supported by a load container frame  22  fixed to the vehicle frame  12 . Advantageously, the panels  20  can be formed from a plastic or reinforced plastic composite (as shown in FIG. 8) material having desirable weight and strength characteristics to reduce operating costs of the vehicle and having flow promoting properties to enhance unloading operations of the container. The term “plastic panel” is defined herein to mean a planar or non-planar wall having opposite face surfaces that are at least in part made of plastic, specifically including, but not limited to, entirely plastic and fibrous or metal reinforced plastic structures and composites.  
         [0027]    The vehicle frame  12  is preferably formed from steel members, as is known in the art, and can be detachable from the tractor  16 . If the vehicle frame  12  is detachable from the tractor  16  as shown in FIGS. 1 and 2, landing gear  30  or additional ground engaging wheels can be provided to support the other end of the vehicle frame  12 . Of course, the vehicle frame  12  can be fixed to a tractor to form an integral unit, such as a straight truck, without departing from the scope of the invention.  
         [0028]    The ground engaging wheels  14  are joined to the vehicle frame  12  using methods well known in the art. In the embodiment disclosed herein, a pair of ground engaging wheels  14  are rotatably mounted on each end of a pair of axles  24  fixed to the vehicle frame  12 . Of course, the number of wheels depends upon the desired load capacity of the vehicle body, and the frame can be supported by one or more wheels without departing from the scope of the invention.  
         [0029]    The load container  18  is supported by the vehicle frame  12 , and includes the plurality of panels  20  secured to the load container frame  22 . Preferably, the load container frame  22  is formed from spaced steel structural members  26  joined by cross members  28  which maintain the spacing between the structural members  26 . The cross members  28  and structural members  26  form a framework for attaching the panels  20  thereto. The members  26 ,  28  can be joined to the vehicle frame  12  and each other using methods known in the art, such as bolting, welding, and the like.  
         [0030]    The panels  20  are secured to the load container frame members  26 ,  28 , and in one preferred embodiment, are formed from a solid plastic material. Forming the panels from a High Density Polyethylene (HDPE) or more preferably from an Ultra High Molecular Weight Polyethylene (UHMW-PE), such as TIVAR® 88 and TIVAR 88-2 available from Poly Hi Solidur Inc. of Fort Wayne, Ind., is preferred for its high strength, light weight, and flow promoting characteristics. The TIVAR preferably has a low coefficient of friction, in the range of about 0.1 to 0.2, with a preferred dynamic coefficient of friction between about 0.1 and 0.15. Strengthening members (not shown), such as metal, glass fibers, and the like can be embedded in the panels  20  to provide additional strength, if required for a particular application. In addition, panel thickness can vary depending upon the particular application.  
         [0031]    As shown in FIG. 8, the panels  20  can be formed of as a uniform homogenous composite including a plastic layer  70 , a layer  72  of reinforcement material and another plastic layer  74 . The composite material is formed by pressing the reinforcement layer between two layers of plastic. The reinforcement layer  72  is disposed between the plastic layers  70  and  74 , and thus is not visible. The plastic layer  70  of the composite panel  20  forms an exterior surface  80  of the panel  20  and thereby of the load container  18  and the plastic layer  74  forms an interior surface  48  of the panel  20  and load container  18 .  
         [0032]    Preferably, the reinforcement layer  72  is expanded or perforated metal, however, fiberglass or other non-metal rigidifying materials could be used. In the case of a metal reinforcement layer, the plastic layers  70  and  74  preferably entirely encapsulate the reinforcement layer  72  to prevent corrosion from moisture within the load container or to its exterior. The plastic layers  70  and  74  are preferably an ultra high molecular weight polyethylene, such as TIVAR described above.  
         [0033]    In one preferred form, the plastic layer  70  is a pre-pressed plastic, preferably TIVAR, sheet. The pre-pressed plastic aids in forming the composite and helps provide a constant thickness of plastic on each side of the reinforcement layer, particular at the side that faces the bottom of the mold. Thus, in one preferred method, the pre-pressed sheet is inserted into the bottom of the mold. The sheet preferably has an adhesive backing, which could be an ultra high molecular weight adhesive tape, that allows the reinforcement to be adhered to the pre-pressed sheet either before or after it is placed into the mold. Plastic resin powder is than poured onto the reinforcement and pre-pressed sheet as needed to achieve the desired wall thickness of the composite panel. A top part of the mold is closed against the bottom part to enclose these materials. These materials are then heated and pressurized using a known pressing operation to form a uniform homogenous reinforced plastic composite. It should be noted that plastic layer  70  could be formed with powdered resin, rather than a pre-pressed sheet, provided suitable techniques were employed to ensure that the reinforcement layer was disposed between two plastic layers. Inserting spacers or risers between the bottom of the mold and the reinforcement layer would be one such technique.  
         [0034]    The composite panel construction of FIG. 8 offers several advantages over conventional steel skin and even some advantages over the plastic only panels described herein. The composite material, like the all plastic panels, does not corrode and is smoother at the interior of the load container  18  than conventional steel skins so as to reduce the occurrence of the load sticking to the panels, and thereby promote dispensing of the load in the load container. It is also stronger than steel skins and is stronger and has improved anti-sagging characteristics than plastic only panels. The composite panel can be configured for various strengths not only by changing the thickness of the plastic but also by changing the thickness, type or configuration of the reinforcement. The pressing operation forms a consistently thick, homogeneous monolithic panel, flat or of any mold formed non-planar configuration, such that there are no problems with expansion and contraction of different materials as would be the case if a separate metal reinforcement was simply mechanically mounted to the plastic.  
         [0035]    The following description is applicable for panels  20  having the plastic only or the reinforced plastic composite construction. As shown in FIGS.  1 - 3  and  8 , the panels  20  are arranged in an edge  32  to edge  32  relation forming a joint  36  between the panels  20 , and defining a volume for containing the load. Each panel  20  is formed using methods known in the art, such as molding, shaping, and the like, to provide a portion of an interior surface  48  of the load container  18  defining the load volume. The panels  20  can be planar or non-planar depending upon the desired load container shape and volume. For example, as shown in FIG. 2, an end panel  34  can be cup shaped to form an end of a closed container.  
         [0036]    Preferably, the panels  20  are formed such that the joints  36  between adjacent panels  20  are aligned with, or adjacent to, a load container frame member  26 ,  28  for attachment of the adjacent panels thereto. In the embodiment disclosed herein, the panels  20 ,  34  define an enclosed volume for carrying a powder, liquid, and or gas. Of course, the defined volume can have an open top or ends to accommodate bulky, solid materials without departing from the scope of the invention.  
         [0037]    Advantageously, if the load container panels  20 ,  34  are damaged, individual damaged panels  20 ,  34  can be removed and replaced to provide a repaired load container without obvious evidence of the repair. Moreover, each individual panel  20 ,  34  can be formed more easily than a larger, single piece, molded load container. In addition, shipping panels  20 ,  34  which form part of the load container  18  to a vehicle assembler or repair site is easier and less expensive than shipping an entire replacement load container molded as a single piece.  
         [0038]    If a fluid-tight load container is not required, such as when transporting a powder, adjacent edges  32  of adjacent panels  20  can abut one another to form the load container joint  36 , such as shown in FIG. 3. Of course, if a tighter joint  36  is requires, a tongue  38  in groove  40  construction, such as shown in FIG. 4, can be used. Advantageously, if a tongue and groove construction is used with at least some of the panels, not all of the panels need be secured to the load container frame  22 . To provide an even more impervious joint  36  for transporting fluids, such as a gas or liquid, a gasket  42 , or other sealant, such as a pourable caulk, can be provided between adjacent panels  20 , such as shown in FIG. 5. Of course, the panels  20  can be welded together to close the joint  36 .  
         [0039]    As shown in FIGS.  3 - 6  and  8 , the panels  20  are secured to the load container frame  22  using countersunk bolts  44  which do not protrude into the volume defined by the panels  20 . Preferably, each bolt  44  includes a cap  46  which is substantially flush with the load container interior surface  48  to minimize obstructions on the load container interior surface  48 . Most preferably, the cap  46  is formed from a flow promoting material, such as HDPE or UHMW-PE. Of course, protrusions into the volume may be desired when transporting fluid loads, for example ridges can be provided in load containers transporting slurries to minimize surging. Accordingly, bolts, and other structure can extend into the load container volume without departing from the scope of the invention. A nut  60  and washers  62 , preferably the washer adjacent to the nut  60  is steel and the other is plastic (such as TIVAR), are provided to secure the bolt  44  in place.  
         [0040]    In the embodiment disclosed herein, as shown in FIGS. 1 and 2, funnels  50  or hoppers formed in the bottom  52  of the load container  18  provide discharge ports for unloading the load container  18 . Each funnel  50  is formed from a flow promoting material, such as HDPE or UHMW-PE, and is joined to, and forms part of, the load container  18 . Preferably, support structure fixed to the truck and/or load container frame  12 ,  22  supports each funnel  50 . Most preferably, each funnel  50  is formed from panels  20 , such as used to form the load container  18 . Valves (not shown) fixed to each funnel bottom are provided to control the flow of material through each funnel  50 , as is known in the art. Although a plurality of funnels are disclosed, any number of funnels an be provided, as required for the particular application, without departing from the scope of the invention.  
         [0041]    In an alternative embodiment shown in FIG. 7, flanges  56  formed proximal the panel edges  32  can be provided for attachment to the structural members  26 ,  28 . Advantageously, bolts  58  extending through a pair of adjacent flanges  56  can be provided to draw the panel edges  36  together to form a tight joint  36  between the adjacent panels  20 .  
         [0042]    In another embodiment, at least a portion of the load container frame is disposed inside the container volume to provide a relatively smooth exterior load container surface. In this embodiment the countersunk bolts do not protrude outwardly from the panels. Preferably, caps are fixed to the countersunk bolt to provide the relatively smooth exterior load container surface.  
         [0043]    It should be appreciated that merely preferred embodiments of the invention have been described above. However, many modifications and variations to the preferred embodiments will be apparent to those skilled in the art, which will be within the spirit and scope of the invention. Therefore, the invention should not be limited to the described embodiments. To ascertain the full scope of the invention, the following claims should be referenced.