Abstract:
An improved lightweight container incorporates a thinner wall structure in an essentially octagonal container having a bottom member, a plurality of sidewalls, a spout, an upwardly converging neck member coupling the sidewalls of the spout, a handle molded into the container and a radiused transiting section between the sidewalls and the spout which eliminates weakened corner sections and improves overall strength to weight ratios.

Description:
RELATED U.S. APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 61/466,588 filed Mar. 23, 2011. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to containers for storage of liquids, granular materials and the like, and methods and apparatuses for forming the same. More particularly, the container of the present invention is a single piece blow-molded plastic container formed in a multi-sided configuration with modified corner radii, utilizing a smaller volume of raw material to obtain volumes and strength equivalent to the prior art. 
     DESCRIPTION OF THE RELATED ART 
     Blow-molded plastic bottles are well known for use for holding a wide variety of liquids such as milk, water and juice. The same types of containers may be used for granular materials. Containers of this type are manufactured in a variety of sizes, conventionally formed of a variety of thermoplastic materials. 
     Typical of these containers are those disclosed in U.S. Pat. No. 6,527,133, issued to McCollum et al.; U.S. Pat. No. 4,805,793, issued to Brandt et al.; and U.S. Pat. No. 6,237,792, issued to Skolnicki et al. 
     Containers of this type are relatively thin-walled, and are generally square or rectangular in cross-section, feature a molded handle, and typically have a finished weight of over 60 grams. Such weight of material is essential to maintaining sufficient strength for the container to withstand the industrial filling process, in particular, the loads imposed for securement of a closure, such as a cap, lid or screw top to the spout on the top of the container.  FIGS. 1A ,  1 B,  1 C and  1 D show top, front, side and bottom views, respectively of blow-molded containers formed according to the prior art. The typical prior art container is depicted in  FIGS. 1A-1D  incorporates a top  102 , a bottom  104  and spout  120 . Top  102  and bottom  104  are interconnected by sidewalls  106 , and includes a handle  122 . In the prior art, a relatively acute transition occurs at the top corner  130  of the top  102  of the container, where the top  102  joins the lower circumference of the spout  120 . Then, when the top  102  joins the sidewall  106 , a second relative abrupt transition occurs at upper corner  124 , generating a comparatively sharp angle between the top  102  and the sidewall  106 . Transitioning to the bottom section of the prior art container, a first intermediate corner  126  creates a first transition between the sidewall  106  and the bottom  128  of the container. A bottom corner  128  completes the transition between the sidewall  106  and bottom  104 . The combination of the corner transitions at intermediate corner  126  and bottom  128 , coupled with the substantial distance between intermediate corners  126  and  128  demand a substantial distribution of material to the bottom section of the container to provide the necessary strength. The same problem is evident at the top of the container  102 , where the top  102  of the container joins the sidewall  106  at upper corner  124 . These multiple spaced apart transitions often result in excessively thin walls at the transitions, thereby weakening the container. 
     More recently, containers have been created which incorporate ribs and other design features in the upper sidewalls of the container to increase mechanical strength, well at the same time decreasing the wall thickness of the finished container. By reducing the overall thickness of the container, substantial savings in materials cost can be realized. Newer containers utilizing these design methodologies have resulted in reductions in material required for each container, and corresponding reductions in material cost, of between five and seven percent. Such reductions in the typical production environment can result in substantial cost savings over time. 
     The existing containers, however, suffer from important limitations. Particularly, as known in the prior art, the manufacture of thin-walled thermoplastic containers utilizing the blow-molding techniques can create unacceptably thin wall dimensions near the top and bottom of the containers, where the tops and bottoms of the containers join the side walls. Excessive thinning in these areas weakens the overall container and reduces its ability to withstand the forces typically imposed during the filling process. To insure that sufficient wall thickness remains in these vital sections, the current containers require a minimum of approximately fifty-eight to sixty grams in weight. A need exists, therefore, for a container design and method of manufacture, which permits more even distribution of thermoplastic material throughout the wall of the container, while allowing significant reductions in the amount of material required to produce the container. 
     SUMMARY OF THE INVENTION 
     In summary, a thin-walled container in accordance with the present invention is formed having sidewalls, a bottom, a top having a neck, a handle, and a spout. The container has eight sides, and a smoothly tapered radius between the spout and the sidewall. To form the container, specialized round tooling is utilized in the die and its associated mandrel to achieve more even distribution of the thermoplastic material during the molding process. The resulting container displays a more efficient distribution of the materials along the sidewalls, top and bottom of the container, typically at a weight of fifty-two grams or less. 
     It is an object of the present invention, therefore, to provide a thin-walled container having an extremely light weight. Further, it is an object of the present invention to provide a thin-walled container having six or more sides and a specially radiused transition between the spout and sidewall of the container. 
     It is another object of the present invention to position the handle of the container to improve venting of the interior of the container during the pouring process. 
     It is another object of the present invention to provide a system for manufacturing the same volume of container as taught in the prior art, while maintaining the necessary structural integrity of the container to withstand the industrial filling process. 
     It is a further object of the present invention to provide and improved container having the same volume and fitting in the same standard case as taught in the prior art. 
     These, and other objects of the invention, will be apparent from the associated drawings and description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  us a top view of a prior art container, constructed according to the methods of the prior art. 
         FIG. 1B  is a front view of a prior art container, constructed according to the methods of the prior art. 
         FIG. 1C  is a side view of a prior art container, constructed according to the methods of the prior art. 
         FIG. 1D  is a bottom view of a prior art container, constructed according to the methods of the prior art. 
         FIG. 2A  is a front view of a first embodiment of the present invention. 
         FIG. 2B  is a side view of a first embodiment of the present invention. 
         FIG. 2C  is a bottom view of a first embodiment of the present invention. 
         FIG. 2D  is an alternate bottom view of a current embodiment of the present invention. 
         FIG. 2E  is an additional bottom view of another variant of a current embodiment of the present invention. 
         FIG. 3A  is a front view of the present invention. 
         FIG. 3B  is a side view of another embodiment of the present invention. 
         FIG. 3C  is a top view of another embodiment of the present invention. 
         FIG. 3D  is a bottom view of another embodiment of the present invention. 
         FIG. 4  is a diagram showing a die and mandrel according to an embodiment of the present invention. 
         FIG. 5  is a diagram showing a parison and a mold according to an embodiment of the present invention. 
         FIG. 6  is a top view of embodiments of the present invention held in a standard dairy crate. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The description which follows will be best appreciated by reference to the accompanying drawings. Although the invention is described in conjunction with the drawings, and a plurality of preferred embodiments is described, it will be appreciated that these descriptions are not intended to limit the invention to those embodiments. The invention includes a variety of alternatives, modifications and equivalents which may be included within the spirit and scope of the invention as defined by the appended claims. 
     The invention will be better understood by a full appreciation of the process of manufacture typically used in the art. A conventional blow-molding machine includes a loading station where pelletized thermoplastic material, such as polyethylene, may be introduced into a hopper or feed bin. The hopper, in turn, feeds the pelletized or granular thermoplastic materials, which is at room temperature, to a heater/drive system. Such a system typically includes a screw drive provided with one or more heating mechanisms or elements which gradually raise the temperature of the thermoplastic material to approximately 365° F. Once the material has attained this temperature, the material liquefies and becomes taffy-like in its consistency. The material is then introduced into the mold through a die and mandrel combination, whereby the thermoplastic material is evenly distributed in the mold. The blob of thermoplastic material which forms as it is extruded through the gauged opening between the die and mandrel is called a parison. Once the parison is formed the mold is closed around the parison possibly imparting the general shape of the interior of the mold onto the parison. This aids in distributing the material of the parison evenly throughout the interior of the mold when the mold is pressurized. The mold is then pressurized via the blow pin thereby forcing the parison to expand throughout the interior of the walls of the mold, and imparting to the material the finished shape of a container. To facilitate the molding process, the mold walls are cooled to approximately 30° to 40° F., to restore the liquefied thermoplastic material to solid state. Once the part has formed, the mold is opened and the part is removed from the mold. 
     Turning now to  FIGS. 2A-2E , a first embodiment of a container formed according to the present invention is disclosed. Container  10  consists of a top section  12 , a bottom  14  and a plurality of sidewalls. Eight sidewalls alternate in dimension, four being long sidewalls  16  and four being short sidewalls  18 . The top section  12  is configured with a spout  20  having an opening  21  by which material may be introduced into the interior of the container  10 . The container is molded as a single piece, and includes a handle  22  which is hollow and permits liquid and air to pass inside it. Preferably, the handle is configured adjacent to a short sidewall  18 , so that when the container is held for pouring, the center of mass is concentrated along the axis which intersects both the handle and the opposing short sidewall of the container. 
     In a first embodiment, the height of the container  10  is measured from the bottom of the container to the bottom of the spout is approximately 9.231 inches, for a container having a volume of approximately 234 cubic inches, essentially a one-gallon container. In this embodiment, a radius transition  24  is formed between the upper limit of the sidewalls  16 ,  18  and spout  20 . Preferably, the radius R has a dimension of approximately three inches, thereby providing a smooth transition between the sidewalls  16 ,  18  and spout  20  of the container  10  in comparison to the prior art. This area of transition may include one or more ribs  28  to provide additional strength to the container. The container  10  is blow-molded, and includes a single piece thin wall construction. The sidewalls, when viewed from above, form a generally octagonal configuration as seen in top or bottom plan views. The container  10  includes a bottom  14  which is interconnected to the sidewalls  16  and  18  and has a plurality of ribs  30 . In one example, the radius transition  24  in between the sidewalls  16 ,  18  and the spout  20  has a radius of approximately 3″ and a transition section length of about 2.5″ in a container having an overall height of approximately 10″. 
     A second embodiment of the invention as disclosed in  FIGS. 3A and 3B , which does not include the ribs  30  but does include the same upper radius transition  24 . Containers of either configuration may be formed with one or more volume control inserts  32  molded into one or more sides of the container to adjust the total internal volume of the container  10 . 
     Turning now to first embodiment of the invention as shown in  FIGS. 2A-E , it will be appreciated that the top section  12  of the container  10  incorporates an upper radius transition of radius R between the bottom of the spout  20  and the top of sidewalls  16  and  18 . The absence of the sharp transitions between the bottom of the spout and the container top, and the top of the sidewall in the container top results in increased strength while allowing for even distribution of the thermoplastic material, eliminating the sharp transitions of the prior art. The inclusion of rib  28  imparts additional strength to this vital section of the container. 
     Likewise, the intermediate corners  34  and bottom corners  36  are positioned closer than the corresponding transition corners in the prior art, resulting in a more even distribution of the thermoplastic material at those critical locations. As shown in  FIGS. 2C-2E , a variety of methods may be adopted for placement of strengthening ribs  30  on the bottom of the container to impart a higher degree of rigidity, utilizing a thinner bottom wall section than required by the prior art. A variety of planiforms may be selected as depicted in  FIGS. 2C-2E , each of which forms the desired function of imparting the necessary strength to the bottom of the container. 
       FIGS. 3A-3D  show a second embodiment of the invention, where the bottom  44  of the container  38  is provided with a plurality of impressions  40 ,  42  which may facilitate stacking of containers  38 .  FIGS. 3A , B, C and D show a first side view, a second side view, a top view and a bottom view, respectively of an embodiment of the invention showing impressions  40 ,  42  cast into the bottom  44  of container  38 . 
     It will be further appreciated that additional strength may be obtained by multiplying the number of sidewalls as shown in  FIGS. 2C and 3C . In each of the embodiments therein depicted, it will be appreciated that the container has eight sidewalls. The utilization of multiple sidewalls decreases the angles between the sidewalls, and the gentler radiuses therein incorporated allows for more even distribution of the thermoplastic material during the molding process. Embodiments of this disclosure have sidewalls arranged as opposing pairs where the distance between pairs of sidewalls is arranged so that two pairs of sidewalls are separated by a first distance and a third pair of sidewalls are separated by a second distance. The ratio of the first distance to the second distance is between about 1:1 to about 1:1.10, with the preferred ratio equal to about 1:1.06. 
     A further advantage of incorporation of the upper radius transition  24  is the improved pouring characteristics of the container. In a prior art, the sharp transitions between the top of the container and the spout and the upper part of the handle and the top of the container results in periodic difficulty in pouring from the container as liquid blocks movement of the contents of the container away from the handle, causing the contents of the container to pour in spurts, rather than in a continuous stream as air is admitted past the liquid. By utilization of the extended upper radius transition of the present invention, the contents of the container flow easily. In addition, the handle section is designed to be hollow and allow air to escape during poring due to its proximity to the spout to thereby mitigate splashing as liquid is pored from the container. It is also noted that the curved nature of the upper radius transition between the sidewalls and the spout permits the handle to be attached higher on the container proximate to the spout and have a smaller hole between the handle and the container, thereby improving the pouring characteristics as mentioned above and permitting the container to contain a greater volume of material. 
     Improved characteristics of containers produced according to embodiments of this invention are due at least in part to improvements to the equipment used to produce the containers, in particular the die and mandrel combination and the shape and size of the mold.  FIG. 4  shows a cross-sectional view of an extrusion mechanism  50  according to an embodiment of this invention. This extrusion mechanism  50  operates as part of a blow molding machine, where the extrusion mechanism  50  positions a circular mandrel  54  having an air passage  56  in a circular die  60  so that a predetermined die gap  66  exists between the mandrel  54  and the die  60  a predetermined die angle  64 . Thermoplastic material is forced into the extrusion mechanism  50  in the direction indicated by arrow “A”, flows around the mandrel  54  and through the die gap  66  to form a parison. A parison is typically a hollow tube or bulb of semi-molten material which extends past the mandrel into the volume which will be the cavity of the mold. Once the desired parison is created, the mold (not shown) closes around the parison so that air can be introduced into the air passage  56  to inflate the parison to fill the enclosing mold. The size and shape of the die angle  64  and die gap  66  with respect to the mandrel  54  can determine the exact proportions of the parison. In this case the die  60  and mandrel  54  are both circular. The first parameter is the die angle  64  which measures the angle of the die  60  with respect to the mandrel  54 . Die angles  64  can range from 0° to 30° or more particularly about 15°-18°. Using a die angle  64  of less than 30° allows the die gap  66  to be smaller. In the case of one gallon containers, a die gap  66  of between about 0.001″ and about 0.025″ or more particularly about 0.006″ produces a parison with the desired shape and size when the appropriate amount of material is forced through the die/mandrel combination. 
     In addition to the shape due to the die angle  64  and die gap  66 , as shown in  FIG. 5 , a parison can change shape when the mold is closed.  FIG. 5  shows a cross-sectional view of a parison  70  with a hollow core  72  inside a mold cavity  74  formed by the two parts of a two-part mold  76 ,  78  according to an embodiment of this invention. The parison  70  has elongated and formed an elliptical shape following closure of the mold halves  76 ,  78 . Embodiments of this invention use the elliptical shape of the parison  70  in combination with improved design of the mold cavity  74  to improve the quality of the finished container. By forming a container with an elongated or diamond shape, shown in  FIG. 5 , the walls of the mold  88  can be kept at a substantially small similar distance from the parison  70 . Replacing corners with short sidewall sections  80 ,  82 ,  84  and  86  and shaping the mold to mirror the shape of the parison improves the structural rigidity of the resulting blow molded container while maintaining overall container strength using less material. In addition, this design helps to avoid dented corners as the resulting container is used, thereby enhancing its appearance. The elongated parison  70  fits the mold cavity  74  more closely than a mold cavity having four symmetric sides. Shaping the interior of the mold to form an elongated shape similar to the parison  70 , where the distance from the parison to the mold wall  88  is substantially equal causes the parison  70  to mold to the interior shape of the mold when the interior of the parison is pressurized. Having the interior of the mold closely mirror the elongate shape of the parison will provide the strongest container for the least amount of material by distributing the material evenly and thereby providing uniform wall thickness. Typical gallon containers manufactured by blow molding can use a minimum of 58 grams of thermoplastic material to form successfully, with 61-64 grams being typical in manufacturing operations. Embodiments of this invention can manufacture gallon containers with desirable strength and appearance using less than about 55 grams of thermoplastic materials, or more preferably less than about 52 grams of thermoplastic material. 
       FIG. 6  shows a top view of embodiments of this invention held in a standard dairy crate. Dairy crates are cases constructed to hold multiple containers so that dairy crates with full containers may be stacked without damage to the containers or contents. Dairy crates are manufactured in standard configurations and it is an advantage of embodiments of this invention that these embodiments fit in a standard dairy crate. As shown in  FIG. 6 , a standard 4-gallon dairy crate  51  holds four 1-gallon containers  52  made in accordance with embodiments of this invention. 
     The above-described embodiments have been described in order to allow easy understanding of the present invention and do not limit the present invention. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structure as is permitted under the law.