Abstract:
A self-supporting bladder for use in transporting or storing foods and liquids is manufactured by folding the ends of a cylindrical section and sealing the open portions of the folded cylinder, resulting in a bladder which supports itself when filled.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention concerns the manufacture and use of self-supporting bladders for use in transporting or storing foods and liquids.  
       BACKGROUND OF THE INVENTION  
       [0002]     It has long been desirable to transport foodstuffs, including grains and other solid foodstuffs and liquids such as cooking oils or potable liquids such as water or wine, in cost efficient, protective containers. It is also understood that these containers should serve to protect the foodstuffs against both physical damage and contamination. For example, U.S. Pat. No. 4,468,812 to Grosvenor discloses a flexible container with a fabric reinforced rubber body, with an internal lining. The fabric served to reinforce the rubber against physical damage, and the internal lining served to protect the transported product from outside influences, such as contamination by contact and reaction with the rubber body, or bacterial infiltration.  
         [0003]     The advent of the widespread use of standardized metal containers for shipping goods ultimately led to the use of internal container bags, or bladders, so that liquids could be shipped in such containers, as well as other foodstuffs needing protection from the environment. However, the use of flexible internal bladders in shipping containers resulted in additional engineering difficulties. As disclosed in U.S. Pat. No. 4,054,226 to Bjelland, et al., use of such flexible internal bladders resulted in undesirable shifting of cargo during shipping, and undesirable stresses on the internal bladders during loading and unloading of the cargo. Bjelland, et al. discloses one attempt to provide an internal framework to support such internal bladders, and also discusses other attempted solutions, such as the bulkhead arrangements disclosed in U.S Pat. Nos. 3,386,605 and 3,696,952.  
         [0004]     Although these approaches alleviate some of the concerns involved in using flexible protective bladders for bulk transportation, each of them requires additional hardware and space, adding expense and reducing the available volume for the shipped goods. Thus, these approaches add cost and reduce total shipping capacity.  
         [0005]     Further, because the bulkhead and other support methods must be used with flexible bladders in shipment, the bladders themselves must be filled or emptied in position. They do not have sufficient structural integrity to serve as stand-alone containers, nor do their structural limitations allow them to be moved in or out of the containers while full, or to be left full at a final destination without additional structural support.  
         [0006]     Accordingly, it is an object of the invention to provide a flexible bladder for use in containerized shipping which does not require additional structural support to maintain the structural integrity of the bladder while full.  
         [0007]     It is another object of the invention to provide a flexible bladder which maximizes the available shipping volume for liquid or solid foodstuffs carried within containerized volumes.  
         [0008]     It is a further object of the invention to allow such flexible bladders to be deposited while full at a shipping destination without loss of integrity and without risk of loss or contamination of the shipped goods.  
       SUMMARY OF THE INVENTION  
       [0009]     The invention comprises a flexible bladder which is constructed by beginning with a cylinder of flexible material. The cylinder may be formed by rolling an essentially rectangular section of flexible material into a cylindrical shape, and joining the ends to form a cylinder. In the preferred embodiment of the invention, the flexible material used is food grade PVC, such as linear low density polyethylene made by GSE Lining Technology, Inc., of Houston, Tex., with a coating to make it acceptable under FDA standards for transporting foodstuffs in direct contact.  
         [0010]     Further, if a cylinder is formed by rolling an essentially rectangular piece of material into a cylinder, it is preferred to join the ends of the material together by welding, such as by a wedge-weld. Those of skill in the art will recognize that other types of welds may be used, or other types of joins could be used, so long as the final join is tight, sufficiently strong for the purpose, and does not introduce a risk of contamination to the transported goods.  
         [0011]     Formed in this way, the cylinder will have opposing, essentially circular openings at a first end and second end. As used herein, the longitudinal axis of the cylinder is that axis parallel to a line drawn between the first open end and the second open end of the cylinder, and the radial axis is the axis perpendicular to the longitudinal axis.  
         [0012]     The invention may be embodied in one of two orientations. In the first orientation, the radial axis of the cylinder will form the long dimension of the final form, which is preferably an essentially rectangular parallelipiped, sized to fit the interior space of a container vessel for shipping, or, if to be used solely as a stand-alone container, sized to the desired dimensions. In the second orientation, the longitudinal axis of the cylinder will form the long dimension of the final form, which is preferably an essentially rectangular parallelipiped, sized to fit the interior space of a container vessel for shipping, or, if to be used solely as a stand-alone container, sized to the desired dimensions. Those of skill in the art will understand that the radius of the cylinder and its length along its longitudinal axis will be selected based on the desired orientation and the desired dimensions of the final form of the bladder.  
         [0013]     In either orientation, the construction of the bladder requires that the first open end and the second open end of the cylinder are folded to create a pair of opposed shaped openings, which can be closed with a shaped seal which are shaped to the formed shapes of the opening, and fixed in place by a sealing means, such as a weld. In the preferred embodiment, rod welds are used to seal the shaped seals into the ends of the cylinder.  
         [0014]     It will be recognized by those of skill in the art that the original cylinder will be formed by this process into a shape which is not cylindrical, but is preferably a portion of a rectangular parallelipiped. However, throughout this description, the word “cylinder” is used to refer to that portion of the structure which begins as a cylinder and is manipulated into other shapes and ultimately forms a portion of the body of the flexible bladder. This label is used not as a limitation to the form of the originally cylindrical body, but rather as a convenient label for a body which is at one point in cylindrical form but must be manipulated into other forms for the creation of the final flexible bladder.  
         [0015]     In the first orientation, the cylinder is folded by pressing inward and down from diametrically opposed points at the first open end of the cylinder, forming an essentially flat body comprised of four trapezoidally-shaped segments. The four trapezoidally-shaped segments comprise two pairs of segments, with each pair having its major bases essentially parallel and separated by an essentially rectangular gap, and its minor bases forming two of the sides of an irregular octagon. The bases of the first pair of trapezoidally-shaped segments are essentially orthogonal to those of the second pair.  
         [0016]     Folded in this way, the first open end of the cylinder is formed into an essentially rectangular open segment, bordered by the first pair of trapezoidally-shaped segments. It is preferable to trim these two trapezoidally-shaped segments (the two on the top of the folded cylinder, if it is laid flat on a surface) to remove triangular segments at the four ends of the two major bases of the trapezoidally-shaped segments. Removing this material makes it easier to fold the outer edges of the underlying, essentially orthogonal second pair of trapezoidally-shaped segments upward and inward, and removes excess material which would preclude such a fold from laying flat once made.  
         [0017]     A rectangular seal, shaped to match the form of the rectangular open segment bordered by the first pair of trapezoidally-shaped segments and sized to allow sufficient overlap with those segment to provide a sufficient seal against pressure from inside, once the bladder is completed. Preferably, the long edges of the rectangular seal are place under the long bases of the first pair of trapezoidally-shaped segments, so that the edges of the rectangular seal will be on the “inside” of the bladder. In this way, internal pressures will act to press the seal more tightly against the remainder of the bladder. The rectangular seal is preferably sized so that the length of its long axis is less than the distance between the short bases of the second pair of trapezoidally shaped segments, and preferably shortened from this distance by essentially the total length of the trimmed triangular-shaped segments previously cut from the first pair of trapezoidally-shaped segments. If, as is preferred, these triangular-shaped segments have been trimmed from the first pair of trapezoidally-shaped segments, an appropriately sized rectangular seal can simply be slid into position. Now the outer edges of the underlying, essentially orthogonal second pair of trapezoidally-shaped segments are folded upward and inward, covering the ends of the rectangular seal. At this juncture the seal can be sealed to the folded cylinder, preferably by the steps of heat sealing, buffing, and rod welding (or extrusion welding) the edges of the rectangular shaped opening in the folded cylinder to the rectangular seal, similarly sealing the folded-over flaps from the underlying, essentially orthogonal second pair of trapezoidally-shaped segments, and sealing the short diagonal segments between the folded-over flaps and the first pair of trapezoidally shaped segments.  
         [0018]     Those of skill in the art will recognize that it is possible to turn the folded cylinder over, exposing the remaining rectangular shaped opening, and to repeat the trimming and sealing process detailed above to insert a second rectangular seal. However, the two original rectangular openings were essentially orthogonal to each other, and the resulting shape of the bladder would approximate that of a twisted ball with flat ends. While such a shape is possibly useful and not beyond the scope of this invention, it is not the preferred result of an essentially rectangular parallelipiped.  
         [0019]     Accordingly, in the preferred embodiment, the folded cylinder is turned over and unfolded. Due to the presence of the rectangular seal and the effects of the prior folds, the unfolded cylinder will have a shape approximate to that of an open box. The sides of this structure are now refolded, to form the second open end of the cylinder into a shape with an essentially rectangular opening which parallels the shape of the first shaped seal. This folding is accomplished by trimming four essentially triangular-shaped segments from the edge of the second open end of the cylinder at the corners that are formed by pressing the wall of the cylinder into essentially the rectangular shape of the first shaped seal. The wall of the cylinder is then folded inward at approximately its midpoint parallel the long axis of the first shaped seal, forming the cylinder into a folded rectangle with essentially trapezoidally-shaped ends. This folding creates an essentially rectangular shaped opening at the second open end of the cylinder, which can be sealed by an appropriately sized, rectangular second shaped seal in effectively the same manner as the first shaped seal.  
         [0020]     Those of skill in the art will recognize that the bladder must be equipped with a vent and at least one inlet-outlet valve, to allow the bladder to be used for transporting foodstuffs. Because the first and second shaped seals in this first orientation form the intended top and bottom of the bladder, a vent, is preferably centered in the first or second shaped seal, which will then become the top of the bladder for operational purposes. Similarly, a ball valve, such as model number VSF204FP, manufactured by Banjo Corporation, can be used as an inlet-outlet valve. Those of skill in the art will recognize that an inlet-outlet valve may be positioned on the top of the bladder, or along the lower edge of one of the sides. Precise positioning of the vent and the inlet-outlet valve is a matter of preference and utility, and does not affect the scope of this invention. However, the vent and inlet-outlet valve must be appropriately positioned at least before the second shaped seal is sealed to the cylinder.  
         [0021]     Constructed as detailed above, the bladder thus formed will, when filled through the inlet-outlet valve, assume the shape of a rectangular parallelipiped, with sufficient structural integrity that no other framework is necessary to support it. As those skilled in the art will recognize, if it is appropriately sized it may be placed inside a shipping container and will thus allow maximum use of the space in such a container for transporting goods, will simultaneously protecting the goods from loss or contamination.  
         [0022]     In the second orientation, the cylinder is folded by first pressing it flat along its longitudinal axis, then folding a section of cylinder near the first open end to so that the first open end forms an essentially rectangular opening bordered by two essentially equilateral triangles, oriented so that the bases of the two triangles form the sides of the essentially rectangular opening. Similarly to the procedure described above, it is preferable to trim triangular shaped segments from the four ends of the bases of the two essentially equilateral triangles, to create a slot so that the first shaped seal may be more easily slid into position, and to facilitate the folding over of the edges at the flat ends of the essentially rectangular opening. A first shaped seal may then be slid into position. As before, it is preferable to position the first shaped seal so that its edges will be inside the bladder relative to the edges of the first open end of the cylinder, so that internal pressures will serve to enhance the seal.  
         [0023]     Similar to the procedure described above regarding the first orientation, the flat edges of the first open end of the cylinder are folded over flat against the first shaped seal, and the first shaped seal is preferably welded in place. Repeating this procedure at the second open end of the cylinder with a second shaped seal results in a bladder which, when filled, will form a rectangular parallelipiped with the first and second shaped seals forming the ends, rather than the top and bottom, of the bladder. As discussed above, those of skill in the art will recognize that it is necessary to appropriately position and install a vent and an inlet-outlet valve during construction of the bladder.  
         [0024]     Those of skill in the art will also recognize that different seal shapes may be used with modified folding techniques, to form different variations on the final shape of the bladder. For example, octagonal seals could be used to create an octagonally-shaped bladder, or triangular seals could be used to form triangular bladders, or other shapes could be used. These variations can be made without departing from the spirit of the invention. However, constraints of conventional shipping methods and structural integrity do not make such variations preferable. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]      FIG. 1A  is a side view of the beginning materials of a first embodiment of the invention  
         [0026]      Fig. 1B  is a oblique view of a cylindrical piece used in constructing a first embodiments of the invention.  
         [0027]      FIG. 1C  is an oblique view of the cylindrical piece of  Fig. 1B  during the construction process of a first embodiment of the invention.  
         [0028]      FIG. 2A  is an oblique view of the cylindrical piece of  Fig. 1B  during the construction process of a first embodiment of the invention.  
         [0029]      FIG. 2B  is an oblique view of the cylindrical piece of  Fig. 1B  during the construction process of a first embodiment of the invention.  
         [0030]      FIG. 2C  is an oblique view of the cylindrical piece of  Fig. 1B  during the construction process of a first embodiment of the invention.  
         [0031]      FIG. 2D  is an oblique view of a first embodiment of the invention in a partially constructed state.  
         [0032]      FIG. 3A  is an oblique view of a first embodiment during the construction process′ continuation from  FIG. 2D .  
         [0033]      FIG. 3B  is an oblique view of a first embodiment during the construction process′ continuation from  FIG. 3A .  
         [0034]      FIG. 3C  is an oblique view of the final assembly of a first embodiment.  
         [0035]      FIG. 4A  is a face view of the beginning materials of a second embodiment of the invention.  
         [0036]      FIG. 4B  is a oblique view of a cylindrical piece used in constructing a second embodiment of the invention.  
         [0037]      FIG. 4C  is an oblique view of the cylindrical piece of  FIG. 4B  during the construction process of a second embodiment of the invention..  
         [0038]      FIG. 4D  is an oblique view of the view of  FIG. 4C  proceeding further in the construction process of a second embodiment of the invention.  
         [0039]      FIG. 5A  is an oblique view of the view of  FIG. 4D  proceeding further in the construction process of a second embodiment of the invention.  
         [0040]      FIG. 5B  is an oblique view of the view of  FIG. 5A  proceeding further in the construction process of a second embodiment of the invention.  
         [0041]      FIG. 5C  is an oblique view of the view of  FIG. 5B  proceeding further in the construction process of a second embodiment of the invention.  
         [0042]      FIG. 5D  is an oblique view of the view of  FIG. 5C  proceeding further in the construction process of a second embodiment of the invention.  
         [0043]      FIG. 5E  is an oblique view of the final assembly of a second embodiment. 
     
    
     DETAILED DESCRIPTION  
       [0044]     Referring to  FIG. 1 , the beginning of construction of a first orientation of a bladder of the present invention is shown. An essentially rectangular strip of material  110 , such as food-grade PVC, is rolled into a cylindrical shape and formed into a cylinder  114  by wedge-weld  112 . Cylinder  114  has a first open end  115  and a second open end  117 . Cylinder  114  is then folded at first open end  115  by pressing inward at diametrically opposed positions  116 ,  118  and folds  120  are formed in the cylinder  114 .  
         [0045]     Referring to  FIG. 2 , further steps in the construction of the first orientation are shown. Folds  220  in cylinder  214  are completed, so that cylinder  214  lays essentially flat. The folding of cylinder  214  has formed a first pair of essentially trapezoidally shaped segments  222  and a second pair of essentially trapezoidally shaped segments  224 . Each pair of essentially trapezoidally shaped segments defines an essentially rectangular shaped opening; the first pair of essentially trapezoidally shaped segments  222  defines essentially rectangular shaped opening  226 , and the second pair of essentially trapezoidally shaped segments  224  defines essentially rectangular shaped opening  228 .  
         [0046]     It is preferable to trim essentially triangular shaped segments (not shown) from the ends  230 ,  232  of the first pair of essentially trapezoidally shaped segments  222 . Such trimming facilitates the folding of the ends  234 ,  236  of the second pair of essentially trapezoidally shaped segments  224 , and allows first shaped seal  238  to be easily slid into position under the edges of the first pair of essentially trapezoidally shaped segments  222 , as depicted by the directional arrow in  FIG. 2B ..  
         [0047]     With the first shaped seal  238  in position, the ends  234 ,  236 , of the second pair of essentially trapezoidally shaped segments  224  are folded over the first shaped seal  238 , as depicted by the directional arrow in  FIG. 2C . Rod welds  242  are made to sealably connect first shaped seal  238  to the first pair of trapezoidally shaped segments  222 , and to seal joins  240  between the ends  234 ,  236 , of the second pair of essentially trapezoidally shaped segments  224  and the first pair of essentially trapezoidally shaped segments  222 .  
         [0048]     Cylinder  214  can then be turned over and unfolded as shown in  FIG. 2D . The presence of first shaped seal  238  causes cylinder  214  to form the shape of a rectangular parallelipiped  244 , with the open top being the second open end  217  of cylinder  214 . Triangular segments  248 ,  250  (indicated by dashed lines) are trimmed from the “corners” of cylinder  214  to facilitate the folding of second open end  217  of cylinder  214 .  
         [0049]     Referring now to  FIG. 2D  and  FIG. 3 , cylinder  314  ( 214  of  FIG. 2 ) is folded again along fold lines  246  of  FIG. 2D , allowing cylinder  314  to lay in a folded flat shape and folding second open end  317  of cylinder  314  to form an essentially rectangular opening. Second shaped seal  338  may then be slid into position, as depicted by the directional arrow of  FIG. 3A . Second shaped seal  338  comprises vent hole  324  for positioning of a vent (not shown) and valve hole  326  for positioning of an inlet-outlet valve (not shown). As discussed previously, the positioning of vents and valves is a matter of engineering preference and needs of the particular application, and these hole positions are shown by way of example only.  
         [0050]     Second shaped seal  338  is positioned so that it lays under essentially trapezoidal end segments  316  and  318 , and flaps  320  and  322  are folded over the sides of second shaped seal  338 . As with the first shaped seal ( 238  of  FIG. 2 ), rod welds  328  seal the sides of the second shaped seal  338  to the cylinder  314 , and also seal joins at the comers.  
         [0051]     As shown in  FIG. 3C , when the bladder  330  is filled, it now forms an essentially rectangular parallelipiped.  
         [0052]     Referring to  FIG. 4 , the beginning steps to manufacture a second orientation of the invention are shown. A sheet  410  of material such as food-grade PVC is rolled into a cylinder  414  with a first open end  416  and a second open end  418 , and fixed in that shape with wedge welds  412 . Those skilled in the art will recognize that the circumference of cylinder  414  is limited by the size of sheet  410 , and that, if necessary to achieve the desired size for the final bladder, multiple sheets of material can be joined together, as by wedge-welding, to form a sufficiently large sheet. Cylinder  414  is then flattened along its longitudinal axis, as depicted by the directional arrows in  FIG. 4C . A section  420  of cylinder  414  is folded near first open end  416 , as depicted by the directional arrow of  FIG. 4D .  
         [0053]     Referring to  FIG. 5 , the first open end  516  of cylinder  514  is opened and one-half of the material  524  is folded back (as shown by the directional arrow of Fig. SA) along fold line A-A′, while the sides are folded inward to form essentially triangular segments  526 , which define a rectangular slot  528 .  
         [0054]     Triangular sections (not shown) are preferably trimmed off of the corners  530 ,  532  of the essentially triangular sections  526 , allowing room to easily slide first shaped seal  534  into position as depicted by the directional arrow of  FIG. 5B . With first shaped seal  534  in position in the first open end  516  of cylinder  514 , edges  536  and  536  are folded over first shaped seal  534  as depicted by the directional arrows of  Fig. 5C . Rod welds  540  are preferably used to seal the first shaped seal  534  into the first open end  516  of cylinder  514 , and to seal the joins between the essentially triangular sections  526  and edges  536  and  538 .  
         [0055]     Installation of the second shaped seal (not shown) involves repeating the steps depicted in  FIGS. 4D, 5A ,  5 B,  5 C, and  5 D and described above at the second open end ( 418  of  FIG. 4B ) of the cylinder  514 . As shown in  FIG. 5E , when filled the cylinder  514  will be formed into an essentially rectangular parallelipiped.  
         [0056]     As with the first orientation, a vent hole  542  and inlet-outlet valve hole  544  (or  546  if a lower-end position is used for the inlet-outlet valve) should be provided, and the appropriate internal hardware installed before the cylinder  514  is completely sealed.  
         [0057]     The above examples are included for demonstration purposes only and not as limitations on the scope of the invention. Other variations in the construction of the invention may be made without departing from the spirit of the invention, and those of skill in the art will recognize that these descriptions are provide by way of example only.