Abstract:
A reusable container, made of a thermoplastic material, with at least one filler and drain opening ( 18 ) in the top panel ( 20 ) and with a circumferential upper and lower stacking ring ( 12, 16 ). To permit reuse, direct stackability, good residual drainability as well as good manipulability of the container, this invention provides for the upper stacking ring ( 12 ) to have a slightly larger diameter than the lower stacking ring ( 16 ) and to feature on the inside of its upper rim a recess matching the diameter of the lower stacking ring ( 16 ) and on the outside a vertically protruding circular flange, so that, when stacked one container atop the other, the lower stacking ring of the upper container fits into the recess in the upper stacking ring of the barrel underneath and is snugly centered therein by the vertically protruding circular flange. This allows for the direct, multiple, secure stacking of the containers that are the object of this invention.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 09/555,011, filed Sep. 13, 2000, now U.S. Pat. No. 6,230,892, which is the U.S. National Stage designation of PCT/EP98/07554, filed Nov. 23, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to a reusable container made of a thermoplastic material, with at least one filler and drain opening in the top panel or container lid, and with an upper and a lower circumferential stacking ring. A similar thermoplastic container has been described for instance in DE-A 26 29 630. That earlier container, featuring thin extruded side walls, offers relatively poor stackability, its residual drainability is inadequate and it is not suitable for reuse. 
     SUMMARY OF THE INVENTION 
     It is the objective of this invention to eliminate such shortcomings by introducing a reusable container which is sturdy in design, permits direct multi-tiered stacking, offers good residual drainability and, in particular, allows for multiple use and facilitated manipulation. 
     According to the invention, this is accomplished by means of the characteristic features specified in patent claim  1 . By giving the upper stacking ring a slightly larger diameter than the lower stacking ring, providing a recess inside the top rim of the upper stacking ring which recess matches the diameter of the lower stacking ring, and incorporating on the outside a vertically protruding circular flange whereby, when stacked one container atop the other, the lower stacking ring of the upper container fits into the recess in the upper stacking ring of the container underneath and is snugly centered by the vertically protruding circular flange, it is possible for containers per this invention to be securely stacked in multiple tiers without requiring intermediate stacking pallets. Moreover, the larger diameter of the upper stacking ring facilitates the handling and manipulation of filled containers of this type. Various enhanced, advantageous design variations of this invention are specified in the subclaims. 
     The structural design of the container and the advantages it offers also make the container per this invention quite suitable for relatively hazardous liquids such as herbicides or pesticides, allowing multiple reuse. This novel reusable container may incorporate any of the following features and enhancements: 
     The upper rim at the top end of the collar of the upper stacking ring has a solid square cross section from the outside of which the circular flange protrudes vertically in the axial direction; 
     The collar of the upper stacking ring is slightly flared toward the outside; 
     The center section of the container body is fully cylindrical over a certain axial length while its upper and lower sections respectively connecting to the upper and lower stacking ring are slightly rounded and tapered; 
     The height (=axial length) of the rounded, tapered wall sections respectively connecting to the upper and lower stacking ring, i.e. to the respective collar to where the fully cylindrical section of the container wall begins, is approximately 110 mm (4.33″); 
     The maximum diameter of a manually manipulable i.e. portable container with a limited capacity of not more than 70 liters (18.5 gallons) is approximately 380 mm (15″) in the area of the fully cylindrical container wall or the outer edge of the upper stacking ring; 
     The top panel is essentially flat or slightly convex and is provided in the area of its flat perimeter with two mutually opposite, protruding bungs with gas-tight scalable bungholes; 
     The essentially flat or slightly convex (domed) top panel connects via a flared or rounded circular section at the junction of the upper stacking ring to the tapered section of the lower container wall; 
     The bottom panel is slightly sloped toward one side in such fashion that a depression (=trough) constituting a sump is formed underneath a drain bung; 
     In the area of the sump, the bottom panel is provided with at least three protrusions, slightly pointing inwards, serving to center the bottom end of a pump tube (e.g. a Micromatic filler and drain suction tube); 
     The center of the bottom panel is slightly convex or domed to facilitate residual drainage; 
     The center of the top panel is slightly concave to facilitate residual draining of an inverted container; 
     The container wall is a multilayered structure consisting of at least two or more different types of thermoplastic material (co-extrusion); 
     The container has a limited capacity of about 70 liters (18.5 gallons) and is provided with at least two handles in the upper stacking ring, so that the container is still manually manipulable i.e. portable; 
     A single, interchangeable-cavity blow mold according to this invention is capable, by inserting circular sections of different heights in the fully cylindrical part of the container wall, of producing containers of varying heights (same diameter, top and bottom panels) with a capacity for instance of 25 L, 30 L, 50 L, 60 L or 70 L (6.6, 7.9, 13.2, 15.9 or 18.5 gallons); 
     The collar of the lower stabilizing ring above the angled circular foot is provided with perforations (e.g. drilled holes) allowing the circular foot of a stacked container to be fastened to the upper stacking ring of a container underneath it, in that suitable fastening aids (such as wire clips or plastic cable ties) can be inserted through a perforation and a handle opening; 
     For fastening at least two side-by-side containers to one another, they are so positioned that their handle openings line up, permitting a length of a fastening aid (such as a clamping strap, a wooden lath or board) to be inserted through the handle openings for locking the containers together; 
     For more secure stacking during storage or transport, several containers stacked on a pallet can be fastened to one another or to the pallet itself by means of fastening aids inserted through the handle openings in the upper stacking ring and/or through the perforations in the circular foot; 
     As a particularly salient feature of the new blow mold for producing a reusable container per this invention, the two blow-mold parts are each provided with an attachment serving to punch out the handle openings in the upper stacking ring. The blow mold is designed as an interchangeable-cavity mold in which the mold parts for the fully cylindrical center section of the container are separated along a horizontal mold-parting plane permitting the production of different container sizes, having the same diameter but varying heights, by the simple process of exchanging and inserting the desired circular section. By inserting the desired circular center section it is thus possible to produce in one single blow mold different container sizes with capacities from 25 to 70 liters. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following explains and describes this invention in more detail with the aid of the design examples illustrated in the drawings in which: 
     FIG. 1 is a perspective view of a 50-liter bung-type container according to this invention; 
     FIG. 2 is a partly sectional side view of the reusable container per FIG. 1, with a Micromatic pump tube inserted; 
     FIG. 3 is a bottom view of the reusable container per FIG. 1; 
     FIG. 4 is a perspective view of the container according to this invention with a screw-on lid; 
     FIG. 5 is a partly sectional side view of a 60 liter screw-lid-type container; 
     FIG. 6 is a side view of a reusable 25 liter container; 
     FIG. 7 is a top view of the screw-lid-type container per FIG. 4; 
     FIG. 8 is a top view of a rectangular-base reusable container; 
     FIG. 9 is a partial, sectional side view of the top and bottom ends of two reusable containers stacked one atop the other; 
     FIG. 10 shows part of the upper stacking ring with a handle opening; 
     FIG. 11 is a partial, sectional side view of the top and bottom ends of two reusable containers stacked one atop the other and secured to one another; 
     FIG. 12 is a partial, sectional side view of the top and bottom ends of two reusable containers stacked one atop the other and secured in a different manner; 
     FIG. 13 is a top view of a pallet holding nine reusable containers; 
     FIG. 14 is a side view of palletized reusable containers; 
     FIG. 15 is a top view of a container with a square base; 
     FIG. 16 is a top view of a container with a hexagonal base; 
     FIG. 17 is a side view of a 70 liter screw-cap-type container; and 
     FIG. 18 is a partial, sectional view of the top end of a lidded container. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a preferred design example of a reusable thermoplastic container  10  according to this invention, in this case with a capacity of 50 liters (13.2 gallons) and with a height/diameter ratio H/D of 1.60. The upper rim of the drum incorporates as an integral part a circumferential stacking ring  12  (handling and transport ring) with two diametrically opposite handle openings  14 . The bottom rim of the container body is equipped with a corresponding support ring  16 . Built into the top panel  20  are two mutually opposite, internally threaded 2-inch bung fittings sealed with bungs  18 . 
     FIG. 2 is a partly sectional side view showing an inserted pump tube  62  (Micromatic tube) which extends all the way to the sump  66  on the bottom panel  64  underneath the bung. As can be seen in the illustration of the bottom panel  64  in FIG. 3, the sump area  66  is provided with four inward-protruding centering lugs  68  which center the lower end of the pump tube  62 , holding it positioned in the sump. 
     FIG. 4 shows a desirable design variant of the reusable container in the form of a small screw-lid-type barrel  22  with a capacity of 50 liters (H/D=1.60), in which case the top panel  20  is provided with only one large, central filler and drain opening which is closed with a threaded cap  24 . The threaded protruding fitting may be a 2-inch or 3-inch bung fitting with an internal thread and a matching bung with a corresponding external thread, or the fitting has a male thread and is closed with an internal-thread screw-on cap. The diameter may be about 80 mm (3.15″) (for a K 80 screw cap) up to 400 mm (15.75″) for large screw lids. Particular preference is given to the popular sizes with a diameter of 150 mm (5.9″), 220 mm (8.65″) or 250 mm (9.85″). 
     FIG. 5 illustrates a 60 liter screw-lid-type container (approx. diameter 380 mm (15″), approx. height 685 mm (27″), H/D ratio 1.75) with an interpositioned circular adapter section  70 . The reusable container may be produced from a transparent thermoplastic material (without the addition of any coloring) or, if opaque, with a transparent viewing strip  72 , ideally with a fill-level scale molded into the outer container wall. Where necessary, two outward-protruding, circumferential rolling profiles may be provided in the transitional part between the cylindrical wall and the rounded, tapered wall sections. 
     FIG. 6 depicts a small  25  liter reusable container with an H/D ratio of 0.97. 
     FIG. 7 is a top view of a screw-lid barrel  22  with one central filler and drain opening for the large screw lid  24 , while the upper stacking ring  12  is perforated in the area of the right-hand handle opening, as shown in the partial sectional illustration. 
     FIG. 8 is a similar top view of a special design variant of the reusable container per this invention in the form of a canister  26  with an L-shaped upper stacking ring  12 . The basic shape of this canister version  26  (L-ring jerrican) is essentially rectangular and the handle openings  14  are located opposite each other in the upper stacking ring  12  on the two long side walls while the filler and drain opening, closed off with the screw cap  28 , is positioned at the outer perimeter of the top panel  20  next to one of the two short side walls in between. In this case, in contrast to the lower stacking ring, the upper stacking ring  12  is not completely continuous but is interrupted by a cutout  30  in front of the filler and drain opening to permit unimpeded pouring of the liquid content. Where a large filler and drain opening is located in the center, the upper stacking ring as well will be circumferentially continuous. 
     FIG. 9 is a partial, sectional view of the corner areas of two containers one stacked atop the other. In this case, the upper container, with the horizontal contact surface  50  of the support ring  16  of the circular foot  48 , facing downward, rests on the horizontal, upward-pointing contact surface  36  of the angled rim  32  of the upper stacking ring of the lower container. The circular flange  38  (centering ring) protruding vertically from the outside of the angled rim  32  centers the circular foot  48  of the stacked barrel, preventing any lateral slippage of the barrels or drums for instance due to vibration during transport. When the containers are stacked directly one atop the other, there is no axial load on the vertically protruding flange  38  (no leverage). 
     Below the junction  42  of the collar  44  of the upper stacking ring, and again above the junction of the collar  46  of the lower support ring  16 , the container wall  40  recedes at a slightly oblique angle or is rounded over a height from about 100 mm (4″) to the cylindrical section of the drum body. The largest angle of inclination in this case is about 15 to 20. At the same time, the collar  44  of the upper stacking ring  12  (angle of inclination about 5 to 8) and the collar  46  of the lower stabilizing ring  16  are slightly sloped toward the outside. For increased radial rigidity, the upper edge, i.e. the angled rim  32  of the upper stacking ring is relatively thick and solid. The bottom surface of the angled rim  32  of the upper stacking ring  12  constitutes a wide, essentially horizontal or perhaps slightly sloped contact surface  34  for the lower claw of a barrel loader. The upper claw of the barrel loader engages on the inside of the angled rim  32  which, being an extension of the collar  44 , serves as a counter-support. 
     The partial view in FIG. 10 shows a handle opening  14  in the stacking ring  12 . According to the invention, the containers are preferably produced in one piece by a single-operation blow-molding process employing two header dies for shaping the two circumferential stacking rings while at the same time, still in the blow mold, two rotary punch dies punch out the handle openings in the upper stacking ring. 
     FIG. 11 illustrates one possible way to secure the containers per this invention for transport purposes. The collar of the lower stabilizing ring, above the circular foot  48 , is provided with several evenly spaced perforations  52 . These may be for instance simple drill holes but may also be horizontal slots already molded in when the circular foot  48  is formed by heading during the blow-molding process. It is thus possible to run for instance a retaining wire or, as shown here, cable ties  54  through the perforations  52  and the handle opening  14 , securely tying the two vertically stacked containers together. The containers are released by simply cutting the cable ties. 
     FIG. 12 shows another possible way to secure the containers per this invention for transport purposes, whereby the handle openings are lined up and a wooden lath  56  is inserted to lock the containers together. 
     FIG. 13 is a top view illustrating this fastening method applied to containers placed side by side on a base pallet  58 . 
     FIG. 14 depicts triple-tier direct stacking (i.e. without intermediate pallets) of 3×3×3=27 containers  10  stacked on a base pallet  58 , in which case the containers are secured especially against vibration during transport for instance by clamping straps  60  run vertically through the handle openings in the upper stacking ring down to below the deck of the pallet and, respectively, wrapped horizontally around the containers and attached to the pallet  58  proper. 
     When loading  60  liter containers per this invention (approx. diameter 380 mm [25″], approx. height 665 mm [26.18″]) into a 20-foot ISO container (DIN  668 ) accommodating 10 side-by-side ISO pallets (1140×1140 mm [45″×45″]), it is possible to load 9 containers in one plane of each ISO pallet which equals 27 containers when triple-stacked or 270 containers on 10 pallets, with a combined capacity of 16,200 liters (4,280 gallons). 
     Reusable containers according to this invention may have a container body with circular stacking and support rings yet with an essentially rectangular, square or hexagonal base. 
     FIG.  15  and FIG. 16 respectively show a square-base container  74  and a hexagonal-base container  76 . The rounded corners may also have a larger radius or curvature. 
     An extra-high container  78  with a capacity of about 70 liters (18.5 gallons) is depicted in FIG.  17 . On one side of its top panel, this tall container  78  is provided with a filler and drain bung fitting  80  (diameter 80 mm [3.15″]) with an external thread for a K 80 screw cap. It is equally possible to position the fitting  80  in the center of the top panel. 
     FIG. 18 shows a section of a special design version of a lidded container  82  according to this invention. In this case the detachable lid  84  is provided with a stacking ring  12  (and handle opening  14 ) and at least one lateral bung fitting  86 . Underneath the stacking ring  12  the lid  84  has an inverted-U-shaped peripheral lid flange  88  with an inlaid gasket or foamed-in circular seal  90 . The lid flange  88  rests on the lip of a wall flange  92  on the rim of the upper perimeter of the drum body. When closed, the lid flange  88  and the wall flange  92  are locked together in gas-tight and impermeable fashion by a clamping ring  94 . This lidded drum  82  is particularly suitable for multiple reuse for holding viscous or granular substances. 
     For multiple reuse, appropriately sturdy containers can be produced in larger sizes as required, for instance with a capacity of 100, 120, 150, 200 or 220 liters (26.4, 31.7, 39.6, 52.8 or 58.1 gallons). However, when filled, these containers can no longer be handled manually but must be manipulated preferably with the aid of mobile elevating platforms or forklifts with the necessary drum-loading equipment (‘parrot beak’). The features described may be easily substituted for one another and/or used in any combination. 
     LIST OF REFERENCE NUMBERS 
       10  Reusable container 
       12  Stacking ring 
       14  Handle opening 
       16  Support ring 
       18  Bung 
       20  Top panel 
       22  Screw-lid-type small drum 
       24  Screw-on lid 
       26  L-ring canister 
       28  Screw cap 
       30  Cutout ( 12 ) 
       32  Angled rim ( 12 ) 
       34  Lower contact surface for barrel loader 
       36  Horizontal contact surface ( 32 ) 
       38  Centering ring ( 32 ) 
       40  Container wall ( 10 / 22 / 26 ) 
       42  Junction ( 12 / 40 ) 
       44  Collar ( 12 ) 
       46  Collar ( 16 ) 
       48  Circular foot ( 46 ) 
       50  Contact surface ( 48 ) 
       52  Perforation (bore) 
       54  Fastening aid/cable tie 
       56  Fastening aid (board, lath) 
       58  Pallet 
       60  Clamping straps 
       62  Pump tube 
       64  Bottom panel 
       66  Sump 
       68  Centering lugs 
       70  Circular adapter section 
       72  Level-viewing strip 
       74  Rectangular-base container 
       76  Hexagonal-base container 
       78  Tall container 
       80  Filler/drain fitting 
       82  Lidded barrel 
       84  Barrel/drum lid 
       86  Bung fitting 
       88  Lid flange 
       90  Seal/gasket 
       92  Wall flange 
       94  Clamping ring