Patent Publication Number: US-6708824-B2

Title: Stackable and nestable container

Description:
BACKGROUND OF THE INVENTION 
     Lightweight, plastic containers are used in myriad applications. However, certain applications demand or make desirable particular features of containers. For example, in the high-volume production of animal feed supplements and similar materials, it is desirable to provide containers which are nestable, particularly when empty, and are also vertically stackable when filled with the material for which the container is designed. Flowable animal feed supplements are often containerized at a relatively high temperature of the supplement material. Filling molded plastic containers at elevated temperatures of the material disposed in the containers tends to weaken the containers and prevent stacking the containers one on top of the other, since the lower-most or at least lower ones of the containers in the stack tend to deform under the weight of the containers stacked above. 
     Of course, prior to filling containers, it is desirable to minimize the space occupied by such items by nesting the containers one inside the other while also providing for easy separation of the containers as they are processed to be filled with the material they are to contain. Accordingly, certain engineering problems have persisted in the development of nestable and stackable containers used for various applications, including the application mentioned hereinabove. It is to overcome the problems associated with prior art containers that the present invention has been developed. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved nestable and stackable container, particularly one formed of molded plastic and being adapted to contain relatively high-density material, which may be loaded into the container at an elevated temperature. 
     In accordance with one aspect of the present invention, a nestable and stackable container is provided which comprises a molded plastic bucket or tub which includes, in combination, an improved sidewall configuration which adds strength to the container, particularly for applications wherein filled containers are vertically stacked one on top of the other. The container sidewall is also joined to a bottom wall of the container in a manner which allows transfer of forces acting on the container through the sidewall directly to a surface supporting the container in a manner which resists or reduces the likelihood of bulging of the container at the juncture between the sidewall and bottom wall. Moreover, the configuration of the sidewall also enhances the nestability and vertical stackability of the container. 
     In accordance with another aspect of the invention, a stackable and nestable container is provided which is preferably formed of molded plastic, includes a sidewall which is characterized by alternate, inwardly facing and outwardly facing channel portions, the channel portions being tapered, generally from a top edge of the container to a bottom edge of the container sidewall. Still further, the outwardly facing channel portions may be reinforced by a vertical, generally central rib extending along each of the outwardly facing channel portions. 
     Still further, the present invention provides a container with improved nestability provided by a sidewall with alternate inward and outward facing channel portions which are tapered from, generally, a top edge of the container toward a bottom wall of the container and with circumferentially-spaced nesting stops dimensioned to limit the amount of insertion of one container within the other. 
     Those skilled in the art will further appreciate the above-mentioned advantages and superior features of the container of the present invention upon reading the detailed description, which follows in conjunction with the drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1A is a side elevation showing plural, filled containers of the present invention vertically stacked one on top of the other; 
     FIG. 1B is a side elevation of plural ones of the container of the present invention nested one within the other when empty; 
     FIG. 2 is a side elevation of the container of the present invention on a larger scale; 
     FIG. 3 is a bottom plan view of the container; 
     FIG. 4 is a detail section view taken generally along the line  4 — 4  of FIG. 3; 
     FIG. 5 is a top plan view of the container of the present invention; 
     FIG. 6 is a detail section view taken generally along the line  6 — 6  of FIG. 5; and 
     FIG. 7 is a detail section view taken generally along the line  7 — 7  of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     In the description which follows, like parts are marked throughout the specification and drawing with the same reference numerals, respectively. The drawing figures may not be to scale in the interest of clarity and conciseness. 
     Referring to FIGS. 1A and 1B, there is illustrated an improved, nestable and stackable container in accordance with the invention and generally designated by the numeral  10 . In FIG. 1A, plural, filled containers  10  are shown stacked vertically one on top of the other. The containers  10  as shown in FIG. 1A may be separated by a thin partition, not shown, be each provided with a top cover, not shown, or be filled with a solid material  11  so that the containers may be vertically stacked by resting the bottom-most container  10  on a firm surface  13  while resting the intermediate container and the uppermost container on the solidified material of the container below and for which the containers have been filled, respectively. 
     As shown in FIG. 1B, the containers  10  may be, when empty, nested one within the other to substantially reduce the space occupied by the containers. 
     Referring now to FIGS. 2,  3  and  4 , each of the containers  10  includes a peripheral sidewall  12 , a bottom wall  14 , FIGS. 3 and 4, and a top edge delimited by a circumferential rim  16 , FIGS. 2 and 3. As shown in FIG. 4, the bottom wall  14  is joined to sidewall  12  by a curved transition portion  18  and, as shown in FIGS. 3 and 4, bottom wall  14  is reinforced by downwardly facing outer and inner circumferential concentric ribs  20  and  22 . Circumferentially-spaced, radially extending ribs  24 , FIGS. 3 and 4, extend from the rib  22  radially outwardly to the sidewall  12 . The height of ribs  20 ,  22  and  24  is such as to extend to a plane which is coplanar with surface  13  so that forces exerted on the bottom wall  14  are transferred through the ribs  20 ,  22  and  24  to a supporting surface for the container  10 . Still further, as shown in FIG. 4, the sidewall  12  includes a depending portion  12   a  depending below the point of tangency of the sidewall with the curved, intermediate or transition portion  18  to an edge  12   b  and which is coplanar with ribs  20 ,  22  and  24 , so that generally vertical forces acting on the sidewall  12  may also be transferred to a support surface, such as the surface  13 . 
     Referring further to FIGS. 2,  3  and  4 , the container  10  defines an interior space  15 , FIGS. 4 and 5, which may be filled with material to a top edge  17 , FIGS. 2 and 5, defined by the peripheral rim  16 . As shown in FIGS. 2,  3  and  5 , the sidewall  12  is characterized by alternating radially inwardly and outwardly facing channel portions  30  and  32 . Channel portions  30  are formed by circumferentially extending tapered wall segments  31 , FIG. 3, while channel portions  32  are formed by corresponding circumferentially extending spaced apart and tapered wall segments  33 . Wall segments  31  and  33  are joined by curved intermediate wall portions  34  and  35 , FIG.  3 . Channel portions  32  taper outwardly generally from rim  16  to sidewall bottom edge  12   b  and, accordingly, channel portions  30  taper inwardly from peripheral rim  16  to sidewall bottom edge  12   b . For a container having a diameter of approximately eighteen inches, a height of approximately eighteen inches and a capacity of approximately twenty-three U.S. gallons, sixteen sidewall channel portions  30  and  32  are provided, respectively. 
     Referring now primarily to FIGS. 5,  6  and  7 , container  10  is provided with opposed handle portions  39 , FIG. 5, which are formed integral with the peripheral rim  16  and are opposed about 180° degrees with respect to each other. Spaced apart openings  40  are provided in each handle portion  39  for securing a tote rope, or the like, not shown. A central radially extending handle reinforcing rib  41  is provided for each handle portion  39 , FIGS. 3 and 6. As shown in FIG. 5, peripheral rim  16  is not completely circular, but is characterized by somewhat linear segments  16   a , each of which is joined to an adjacent linear segment by a short curved segment  16   b . Linear segments  16   a  are aligned generally with the centerline of the tapered channel portions  32 . As shown in FIG. 7, peripheral rim  16  includes a down-turned flange  16   c  spaced from sidewall  12  about the circumference of the container  10 . Circumferentially spaced, axially extending, rib-like anti-nesting stops  42 , one shown in FIG. 7, extend from top edge  15  downwardly a pre-determined distance to a stop surface  42   a . Accordingly, when containers  10  are nested one within the other, as shown in FIG. 1B, the stop surfaces  42   a  of one container engage the top edge  17  of the container in which it is nested to limit the extent of such nesting and prevent one container from wedging or sticking inside another container. 
     Still further, the channel portions  32  are each reinforced by a central rib  44 , FIGS. 3 and 7, which extends downwardly from and is coplanar with each of the anti-nesting stops  42 , respectively, and preferably to the bottom edge  12   b  of sidewall  12 . Accordingly, wall segments  33  are reinforced by the ribs  44  and the anti-nesting ribs or stops  42 , respectively. Respective ribs  44  are provided coplanar with the respective ribs  41  also, see FIG. 6 by way of example. Moreover, by providing the tapered channel portions  30  and  32 , the sidewall  12  of container  10  is also reinforced against both radial bulging as well as axial buckling in the direction of central axis  10   a  of container  10 , when plural containers are stacked one on top of the other, as shown in FIG. 1A, and are full of relatively dense material at elevated temperatures, in particular. The depths or radial widths of the ribs  44  are preferably less than the depths of the channel portions  32  so as to not interfere with the nestability of the container  10 . 
     A container  10  having the capacity and general dimensions as mentioned above is preferably formed of relatively high-density polyethylene. The thicknesses as of the sidewall  12 , the bottom wall  14 , and the peripheral rim  16  are, preferably, approximately 0.125 inches to 0.130 inches and the stops  42  and ribs  44  are, preferably, approximately 0.10 inches thick. The container  10  may be formed as an integral structure in its entirety in substantially one operation by an injection molding process of a type well known. Thanks to the configuration of the sidewall  12 , the bottom wall  14 , and the stops and ribs  42  and  44 , the container  10  has demonstrated superior vertical stackability as compared with prior art containers having generally cylindrical sidewalls. The taper of the sidewall  12  with respect to a central axis  19  of the container  10  is, preferably, approximately four degrees outwardly from the bottom wall  14  to the peripheral rim  16 . 
     The manufacture and use of the container  10  is believed to be readily understandable to those of skill in the art based on the foregoing description. Although a preferred embodiment of a superior nestable and stackable container has been described herein, those skilled in the art will also recognize that various substitutions and modifications may be made without departing from the scope and spirit of the appended claims.