Abstract:
A smart polymer molded hybrid shipping container generally refers to large intermodal shipping container and their manufacture, and more particularly to a recyclable rotationally-molded RF (radio frequency) transparent thermoplastic polymer shell with a removable outer structural fabricated steel load bearing support frame capable of being integrated with an internally mounted geo-location detection system, date transmission communication devices, inner environmental sensors, data storage system, and power storage system. The smart polymer molded hybrid shipping container is designed to be 100% recyclable after useful life with a mechanically fastened exoskeleton steel frame that can be reused in the post manufacturing process. The smart polymer molded hybrid shipping container has a one piece molded shell with load bearing molded in floor system and outer polymer skin that is entirely weather resistant and non-corrosive.

Description:
[0001]    This invention relates generally to large intermodal shipping container and their manufacture, and more particularly to a recyclable rotationally-molded RF (radio frequency) transparent thermoplastic polymer shell with a removable outer structural fabricated steel load bearing support frame capable of being integrated with an internally mounted geo-location detection system, date transmission communication devices, inner environmental sensors, data storage system, and power storage system. 
       BACKGROUND OF INVENTION 
       [0002]    Large enclosed steel shipping containers are used for a number of purposes, one particular example being so-called intermodal shipping container. Intermodal shipping containers are hollow boxes, fabricated from entirely steel, made in standard sizes and provided with uniform lifting eyes. These containers can be easily lifted, moved, and secured so that they can be shipped by sea, air, or land. Intermodal containers typically manufactured from steel are heavy, expensive, prone to corrosion, and are environmentally difficult to recycle. These steel containers are also difficult to scan with standard x-ray technology from the outside and incapable of accepting RF transmissions into such a container without the use of an exterior antenna. It would be beneficial if such large containers could be made from a substitute material that is RF transparent such as thermoplastic polymers. It would also be beneficial if these containers were capable of integrating geo-location, sensing interior environmental conditions, and transmitting such information in a cost and power efficient manner without the utilization of an exterior antenna. If would also be beneficial if these units could be effectively scanned for any potential bio, chemical, or nuclear hazards prior, during, or after any utilization in a efficient and less costly manner. It would also be beneficial if these container units were environmentally friendly and capable of being easily recycled after useful utilization and product life cycle in a cost effective and efficient manner. 
         [0003]    Rotational molding is one known process for producing large hollow plastic products. Rotationally molded products have good strength and durability, and can achieve uniform wall thickness using relatively simple tooling. However, the required heating method is typically done by placing the mold inside a gas or oil fired oven during the molding cycle. This would be prohibitively expensive, be complex for large and rectangular shaped products such as intermodal shipping containers, and would result in uneven heat distribution around the polymer mold. After manufacture of the large thermoplastic polymer shell, a fabricated load bearing steel frame capable of being assembled encapsulating the polymer shell must be attached to the polymer shell to support the upper stack loaded containers. 
         [0004]    Accordingly, there is a need for a practical method of molding larger polymer containers and encapsulating the shell into a fabricated steel frame that can be removed for recycling after its useful life while also being RF transparent for data collection and transmission of useful digital and analog information for commercial and national security reasons without the use of exterior antennae. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The present invention addresses the above-mentioned need by providing a rotationally-molded thermoplastic polymer shipping container with encapsulated load bearing structural exoskeleton steel frame, an independent surface heated mold for producing such polymer-steel hybrid containers, and an apparatus and method for carrying out such molding. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The invention may be best understood by references to the following description taken in conjunction with the accompanying drawing figures in which: 
           [0007]      FIG. 1  is a side view of the container constructed in accordance with the present invention 
           [0008]      FIG. 2  is the top view of the container of  FIG. 1 ; 
           [0009]      FIG. 3  is an end view of the container of  FIG. 1 ; 
           [0010]      FIG. 4  is a perspective view of a partially assembled container of  FIG. 1 ; 
           [0011]      FIG. 5  is a side view of a mold for producing the container of  FIG. 1 ; 
           [0012]      FIG. 6  is the top view of the mold of  FIG. 5 ; 
           [0013]      FIG. 7  is the end view of the mold of  FIG. 5 ; 
           [0014]      FIG. 8  is a perspective view of the mold of  FIG. 5 ; 
           [0015]      FIG. 9  is a perspective view of the mold in an open position; 
           [0016]      FIG. 10  is a perspective view of the mold apparatus for use with the mold of  FIG. 5 ; and 
           [0017]      FIG. 11  is a perspective view of the hybrid polymer steel container with the internally mounted geo-location detection system, date transmission communication devices, inner environmental sensors and data storage system within a molded polymer shell encapsulated in the load bearing steel frame. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    Referring to the drawings wherein identical reference numerals denote same elements throughout the various views,  FIGS. 1-3  depict a polymer steel hybrid container  10 , the basic components of which are a plywood floor; a sub monocular floor; a roof  14 , a pair of spaced-apart side walls  16  and  18 , and a pair of spaced-apart end walls  20  and  22 ; a steel fabricated front frame; a steel fabricated rear frame; top rail; and lower bottom rail. In the illustrated example, the container  10  is designed for use as an intermodal shipping container suitable for being transported by ship, rail, or truck, and has a length between 20 to 48 feet, a height between 8 feet 6 inches and 9 feet 6 inches, and a width of 8 feet. The present invention is equally applicable to other types of containers. At least one of the end walls  20  or  22  is split vertically and hinged to create a pair of doors  24  and  26  which provide access to the interior of the container. 
         [0019]    The side walls  16  and  18 , end walls  20  and  22 , floor  12  and roof  14  of container  10  define a unitary polymer shell “S” which is thermally molded plastic of a high density or linear low density, virgin or recycled polyethylene, which is tough, waterproof, and corrosion resistant, using a rotational molding procedure, described in detail below. If desired the doors  24  and  26  may be made by cutting out one of the end walls  20  and  22  from the shell “S” and replacing it with separate molded pieces. In the illustrated example, the shell “S” is manufactured with a polyethylene resin containing a Ultraviolet inhibitor and color additive to retard aging and fading. The roof  14 , side walls  16  and  18 , end walls  20  and  22 , and monocular floor  12  is molded corrugated panels which in the illustrated example are approximately ⅜ inch thick. 
         [0020]    The floor  12  is integrally stiffened with a plurality of longitudinal and lateral molded floor beams  34 . Each of the beams are supported can be supported with an external steel channel for fastening plywood floor at joints. A finish floor  35  of 1⅛ inch marine grade plywood or similar approved material is laid over the tops of the floor beams  34  to provide a level load-bearing surface. 
         [0021]    The container  10  is encapsulated with a fabricated steel exoskeleton having top and bottom corner castings, corner posts, and horizontal attachment beams. The corner castings include a lifting eye of a known standard type in the industry, which provides purchase for lifting, moving, and securing the container  10 . The fabricated steel exoskeleton front and rear frame sections are connected to each other through the top and bottom rail sections. The rail sections are attached to the end frames with removable mechanical fasteners, suitable for load bearing and torque conditions. 
         [0022]    The container  10  is integrated with an enclosed electronic sensor package consisting of an internally mounted geo-location detection system, date transmission communication devices, inner environmental sensors and data storage system in the monocular floor system below the plywood deck in a water tight plastic enclosure casing. Internal antennae are installed in the upper roof section and connected with associated electrical wiring. 
         [0023]    The container  10  rests upon the fabricated steel exoskeleton and is mechanically attached internally to the front and rear steel frame sections and upper and lower rail sections with suitable mechanical fasteners. 
         [0024]      FIGS. 5-9  illustrate a rotational mold for manufacturing the shell “S” of the container  10  described above. The mold  40  is built up from a top panel  42 , a bottom panel  44 , spaced apart side panels  46  and  48 , and spaced-apart end panels  50  and  52 , which collectively form a mold space that defines the exterior dimensions of the shell “S” of the container  10 . The mold  40  includes mounting pads  54 , for example circular discs with protruding studs, on each end thereof for attaching the mold to a rotation inner support assembly (described below). The mold panels are made of a heat resistant, thermally conductive material such as aluminum, and may include stiffening ribs as shown on the outer surfaces. If desired the panels may be coated with a material such as polytetraflouroethylene (PTFE) on the interior surfaces thereof to improve the release characteristics. 
         [0025]    The side panels  46  and  48  are attached to the lower edges to the bottom panel by hinges  56  which allow them to fold down to an open position as shown schematically in  FIG. 9 . The side panels  46  and  48  are secured in the closed position by suitable clamps, such as the remotely-operated pneumatic side clamps  58  shown in  FIGS. 5-7 . The bottom panel  44  may be detached from the rest of the mold  40  for charging the mold  40  or removing the finished shell “S” (not shown in  FIGS. 5-7 ). The bottom panel is secured in the closed position by suitable clamps, such as the remotely-operated pneumatic to clamps  60  shown in  FIGS. 5-7 . The mold  40  is attached to an outer frame  58  allowing thermal expansion on all three axis while also being capable of dual axis rotation. 
         [0026]    The mold  40  has a plurality of surface mounted direct contact heaters  62  of suitable wattage attached to the exterior. An example of a suitable heater  62  would be 48 inch long electrical resistance heater rated for 240 volts AC. The size, number, and position of the heaters  62  may be varied to suit a particular application, and they may be arranged into any desired number of heating zones by appropriate arrangement of the electrical supply circuits, powered through rotating Commutator rings (not shown) of sufficient current carrying capability from the main electrical load power source. The heaters are insulated with a suitable fiberglass insulating cloth and covered with aluminum reflective strips to redirect heat back into the mold. The heaters  62  are attached to the panels with clamps  64  which hold the heaters  62  against the panel surface while allowing the heaters to expand and contract separately from the mold  40 . 
         [0027]      FIG. 10  illustrates a support assembly  74  for holding and manipulating the mold  40 . The support assembly  74  comprises an outer frame  76  supported by legs  78 . A pair of electrical Commutator rings  80  is mounted to opposite sides of the outer frames  76 , aligned along the first or “X” axis. The first rotators  80  may be any kind of actuator capable of rotating the mold  40 . In the illustrated example each of the first rotators  80  includes an electric motor  82  connected to a reduction gearbox  84 . An inner frame  86  has a plurality of cooling units  88 , for example water-cooled fans, and mounted around its periphery. A pair of second rotators  90  is mounted to opposite sides of the inner frame  86 , aligned along a second or “Y” axis perpendicular to the “X” axis. The second rotators  90  may be any kind of actuator capable of rotating the mold  40 . In the illustrated example each of the second rotators  90  includes an electric motor  92  connected to a reduction gearbox  94 , as well as mounting pad  96  for receiving the mating mounting pad  54  on the mold. The support assembly  74  may be mounted over a floor pit or similar structure (not shown) so as to accommodate the swing radius of the inner frame  86  and the mold  40  without excessively long legs  78 . The support assembly  74  also includes appropriate means for transferring electrical and/or pneumatic power to the inner frame  86  and the mold  40 . For example the first and second rotators  80  and  90  may incorporate slip ring connectors of a known type which allow an electrical current to pass from one rotating part to another. An upper and lower detachable oven  99  is attached to the inner frame to capture and reflect the radiant heat and rotate with the inner frame. This oven is attached with a pneumatic type piston cylinder and movable pin that locks the ovens to the rotating frame through 360 degree rotation. 
         [0028]    The molding process and steel frame attachment process proceeds as follows. First, the mold  40  is placed in the inner frame  86  and attached to the mounting pads  96  of the second rotators  90 . Electrical and/or pneumatic connections are made between the mold  40  and a control unit  98 , which may be a computerized temperature and speed control unit. The side panels  46  and  48  of the mold  40  are closed and locked with side clamps  58 . Optionally, the interior of the mold  40  is coated with a suitable release agent. It is then charged with the correct quantity of plastic polymer material, for example polyethylene powder and suitable additives such as ultraviolet inhibitors, color, or foaming materials. The top panel  42  then placed on the mold  40  and secured, for example with top clamps  60 . The top and lower insulating oven  99  are then lowered and raised respectively and the oven are attached to the inner rotating frame. The mold  40  is then ready for use. The mold begins to spin on its inners frame assembly  86 . The heaters  62  are supplied with electrical current as directed by the control unit  98  to heat the mold  40  to the appropriate temperature. This heat causes the plastic material to soften and melt inside the mold  40 . As the material is heated, the control unit  98  signals the first and second rotators  80  and  90  to rotate and tumble the mold  40  in a predetermined manner about the “X” and “Y” axis. This causes the liquefied plastic material to coat the interior of the mold  40 . After an appropriate time, the control unit  98  turns the heaters  62  off, raises and lowers the top and lower insulating ovens respectively, and starts the cooing units  88  to cool the mold. When the mold  40  has sufficiently cooled, the rotation is stopped with the top panel facing down. The clamps are removed and the top panel  42  removed. The side clamps  58  are released and the side panels  46  and  48  folded away from the part. This exposes the molded shell “S” so that it may easily be removed from the mold  40  and prepared for subsequent manufacturing steps. 
         [0029]    After the polymer shell “S” is removed, it is then coupled and mechanically fastened with the back door end frame, front door frame, top side rail, and lower side rail. The plywood floor is installed and mechanically fastened to the molded floor system. The electronic sensor package consisting of an internally mounted geo-location detection system, date transmission communication devices, inner environmental sensors and data storage system in the monocular floor system is installed below the plywood deck in a water tight plastic enclosure casing. Internal antennas are installed in the upper roof section and connected with associated electrical wiring. The complete unit is inspected and ready for shipment. 
         [0030]    The forgoing has described a plastic molded shell encapsulated in to a steel exoskeleton with an electronic sensor package consisting of an internally mounted geo-location detection system, date transmission communication devices, inner environmental sensors and data storage system and a method and apparatus for its production. While specific embodiments of the present invention have been described, it would be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.