Abstract:
A plastic corrugated case is provided. The case is made of at least one extruded sheet having, in an unfolded state, an extrusion direction and a transverse direction perpendicular to the extrusion direction. The sheet has a cross-sectional profile parallel to the transverse direction, the cross-sectional profile having a first section, and a second section different from the first section.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to plastic cases, and more particularly to plastic corrugated cases.  
         [0003]     2. Related Art  
         [0004]     Cases or boxes are often used to ship and display multiple smaller containers of a products. For example, motor oil is usually sold in one quart plastic containers that are shipped in cases that hold either 6 or 12 of the one quart plastic containers. These cases are usually constructed of corrugated cardboard. If the cardboard cases become wet through contact with rain or other liquid, they become very weak and often fail. Also, to be opened, the cardboard cases often must be cut with a knife. This can lead to accidental cutting of the product containers within the case.  
       BRIEF SUMMARY OF THE INVENTION  
       [0005]     In summary, embodiments of the invention provide a corrugated plastic case that has differing cross sections so that sections of the case that require more strength are stronger while sections requiring less strength use less plastic material.  
         [0006]     Particular embodiments of the invention provide a plastic corrugated case, having at least one extruded sheet having, in an unfolded state, an extrusion direction and a transverse direction perpendicular to the extrusion direction, the sheet having a cross-sectional profile parallel to the transverse direction, the cross-sectional profile having a first section, and a second section different from the first section.  
         [0007]     Other embodiments of the invention provide a one piece plastic corrugated case having, in an unfolded state, an extrusion direction. The case has a bottom panel having a cross-sectional profile perpendicular to the extrusion direction; a front panel attached to the bottom panel and having a cross-sectional profile perpendicular to the extrusion direction; a back panel attached to the bottom panel and having a cross-sectional profile perpendicular to the extrusion direction; a right side panel attached to at least one of the front panel, the back panel or the bottom panel and having a cross-sectional profile perpendicular to the extrusion direction; a left side panel attached to at least one of the front panel, the back panel or the bottom panel and having a cross-sectional profile perpendicular to the extrusion direction; and a top panel attached to at least one of the front panel, the back panel, the right side panel or the left side panel and having a cross-sectional profile perpendicular to the extrusion direction. The case is, in the unfolded state, a single piece of plastic, and at least one of the cross-sectional profiles changes along a direction perpendicular to the extrusion direction.  
         [0008]     Other embodiments of the invention provide a method of producing a plastic corrugated case. The method includes extruding a first sheet having, in an unfolded state, an extrusion direction and a transverse direction perpendicular to the extrusion direction. The extrusion causes the first sheet to have a cross-sectional profile parallel to the transverse direction, the cross-sectional profile having a first section, and a second section different from the first section. The method further includes folding the first sheet to form at least a part of the case; and attaching portions of the first sheet to other portions of the first sheet or to portions of a second sheet to maintain the case in a folded state.  
         [0009]     Further objectives and advantages, as well as the structure and function of preferred embodiments will become apparent from a consideration of the description, drawings, and examples. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The foregoing and other features and advantages of the invention will be apparent from the following, more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings wherein like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.  
         [0011]      FIG. 1  is a perspective view of an example of a first embodiment of a case according to the invention;  
         [0012]      FIG. 2  is a plan view of the case of  FIG. 1  in an unfolded state;  
         [0013]      FIG. 3  is a perspective view of a corner detail of the case shown in  FIGS. 1 and 2 ;  
         [0014]      FIG. 4  is a plan view of the corner detail shown in  FIG. 3 ;  
         [0015]      FIG. 5  is a plan view of a second embodiment of the invention; and  
         [0016]      FIG. 6  is plan view of a third embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     Embodiments of the invention are discussed in detail below. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. While specific exemplary embodiments are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without parting from the spirit and scope of the invention. All references cited herein are incorporated by reference as if each had been individually incorporated.  
         [0018]     The above described problems with cardboard boxes can be eliminated by using plastic corrugated cases in accordance with the invention. Such plastic corrugated cases can be made from extruded sheets of corrugated plastics. However, with sheets of corrugated plastic having a uniform cross section, in order to make particular sections of the plastic corrugated sheet strong enough, other sections of the plastic corrugated sheet will be stronger then necessary. This results in using more plastic material than necessary and, therefore, a higher cost than necessary. Particular embodiments of the invention solve this problem associated with plastic corrugated sheets having a uniform cross section by altering the cross section of the plastic corrugated sheet so that particular sections of the plastic corrugated sheet are provided with only as much material as those sections require in the finished case.  
         [0019]      FIG. 1  shows a case  1  in accordance with an exemplary embodiment of the invention.  FIG. 2  shows a sheet of corrugated plastic that can be folded to form case  1 . As shown in  FIG. 1 , case  1  has a bottom  10 , a top  20 , a front  30 , a back  40 , a left side  50  and a right side  60 .  
         [0020]     The sheet shown in  FIG. 2  has a bottom panel  100  that forms bottom  10  of case  1 . Top  20 , front  30  and back  40  are formed by top panel  200 , front panel  300  and back panel  400 , respectability. Attached to front panel  300  are right side panel  310  and left side panel  320 . Similarly, attached to back panel  400  are right side panel  410  and left side panel  420 . To assemble case  1 , right side panel  310  is folded along fold line  301  so that right side panel  310  forms a 90° angle with front panel  300 . Similarly, left side panel  320  is folded along fold line  302  such that left side panel  320  forms a 90° angle with front panel  300 . Front panel  300  is then folded along fold line  303  to form a 90° angle with bottom panel  100 . At this point, a lower edge of left side panel  320  rests near fold line  102  of bottom panel  100  and a lower edge right side panel  310  rests near fold line  101  of bottom panel  100 . Next, right side panel  410  is folded along fold line  401  to form a 90° angle with back panel  400  and left side panel  420  is folded along fold line  402  to form a 90° angle with back panel  400 . Back panel  400  is then folded along fold line  403  to form a 90° angle with bottom panel  100 . At this point, the lower edge of left side  420  rests on, or is proximate to, fold line  102  and a lower edge of right side panel  410  rests on, or is proximate to, fold line  101 . A right flap  110  is then folded along fold line  101  and secured to right side panels  310 ,  410 . Similarly, a left flap  120  is folded along fold line  102  and secured to left side panels  320 ,  420 . Right flap  110  and left flap  120  can be secured by, for example, plastic welding or an adhesive. In this assembled position, an edge  311  of right side panel  310  preferably contacts, and is adhere to, an edge  411  of right side panel  410 . Similarly, an edge  321  of left side panel  320  preferably contacts, and is adhered to, an edge  421  of left side panel  420 . At this point, case  1  is ready to be filled with product.  
         [0021]     After case  1  is filled with the product to be sold in case  1 , top panel  200  is folded along fold line  203  to form a 90° angle with back panel  400  and closes case  1 . Top panel  200  is secured in place by folding a front flap  210  along a fold line  204  and bonding front flap  210  to front panel  300  as shown in  FIG. 1 . A right side flap  220  is folded along a fold line  201  to form a 90° angle with top panel  200  and is bonded to right side panels  310 ,  410 . Similarly, a left flap  230  if folded along a fold line  202  to form a 90° angle with top panel  200  and is bonded to left side panels  320 ,  420 .  
         [0022]     Right flap  220  and left flap  230  are provided with a right handle  225 , and a left handle  235 , respectively. Handles  225 ,  235  can be folded away from right side  60  and left side  50 , respectively, to facilitate lifting of case  1 . In this example, handles  225  and  235  are provided with grooves  227  and  237 , respectively, to add strength to the handles.  
         [0023]     In accordance with the invention, particular areas of case  100  are strengthened to sustain the loads placed on case  1  during use, while other portions of case  1  do not require strengthening. In  FIGS. 2 and 3 , strengthened areas are shown by cross hatching. One example of strengthening in accordance with the invention is shown in  FIGS. 3 and 4 . In this example, the corrugated plastic cross section in strengthened areas  440  and  445  have thicker top and bottom panels and thicker webs between the panels. This thickening is provided by using, for example, different die sizes during the extrusion process. In addition to the thickening discussed above, left side panel  420  and left side panel  320  are further strengthened by grooves  425  and  325 , respectably. As shown in  FIG. 2 , similar grooves  315  and  415  are provided in right side panel  310  and right side panel  410 , respectably.  FIG. 3  also shows a strengthened area  240  in top panel  200 . Strengthened area  240  provides top panel  200  with added resistance to breaking or deforming at the point at which top panel  200  contacts the top edges of left side panels  320 ,  420 . Although  FIG. 3  only shows one end of case  1 , it is understood that the other end of case  1  can be similarly constructed.  
         [0024]     As can be seen from  FIG. 2 , the various strengthened areas in this example can be produced in a sheet of corrugated plastic whose cross section is not uniform in a transverse direction B but is uniform along an extrusion direction A. Because of this, the sheet of corrugated plastic shown in  FIG. 2  can be cut from a sheet of corrugated plastic produced by extrusion.  
         [0025]      FIG. 5  shows an alternate embodiment of the invention in which strengthened areas  440 ′ and  445 ′ are corrugated, and non-strengthened areas are thin solid plastic sheets. Depending on the intended use of the case, the embodiment shown in  FIG. 5  may provide sufficient strength while using less plastic.  
         [0026]      FIG. 6  shows an embodiment of the invention including a corner reinforcement  500  that can be formed during the extrusion process as a part of, in this example, left side panel  420  and can be bonded to back panel  400  during assembly of case  1 . Corner reinforcement  500  can provide added strength to the corners of case  1  and, thereby, allow reduction of the amount of plastic used in other sections of case  1  while maintaining the required strength. Similarly, a rib can be formed during extrusion on one or more of the panels in, for example, a central region of the panel to provide structural support for the case.  
         [0027]     In the examples shown in the Figures, the left and right ends of case  1  are designed to be the primary load carrying members in the case. However, depending on the intended use of the case, different sections can be made stronger as appropriate. Also, the case and bottles to be carried in the case can be designed together so that sufficient strength is provided by the combination of the case and the bottles.  
         [0028]     The various fold lines of the invention are preferably formed during the extrusion process so that no further scoring is necessary before assembly.  
         [0029]     The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art the best way known to the inventors to make and use the invention. Nothing in this specification should be considered as limiting the scope of the present invention. All examples presented are representative and non-limiting. The above-described embodiments of the invention may be modified or varied, without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described.