Abstract:
A steel drum having a cylindrical body with rolling hoops at about 1/3 and 2/3 of the height of the drum, the rolling hoops having a flattened outer surface and a diameter no greater than 231/4 inches, where the diameter of the cylindrical body is consistent except for the areas of the rolling hoops. Other than a reduced diameter rolling hoop and a retooled swedger, all dimensions of the drum, tools and materials for manufacture are the same as a standard steel drum.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of containers and more specifically steel drums for transporting materials. 
     BACKGROUND OF THE INVENTION 
     The fifty-five (55) gallon steel drum has long been a standard container for transporting materials. The standard 55 gallon steel drum has a head, a bottom and a cylindrical middle section with two rounded rolling hoops, one each at about 1/3 and 2/3 of the height of the drum. The standard 55 gallon drum measures 343/8 inches in total height and has a diameter of 2315/32 inches at the rolling hoops. 
     However, these dimensions have proven troublesome wherein the diameter at the rolling hoops does not allow the standard drums to be placed four (4) abreast in a standard ISO overseas shipping container. U.S. Pat. Nos. 4,921,116 to Troughton et al and 4,781,301 to LeBret et al both recognize this problem and provide alternative structures for dealing with it. 
     U.S. Pat. No. 4,921,116 describes a steel drum with two rolling hoops having narrowed diameters. The drum body section above the top rolling hoop and the section below the bottom rolling hoop are described as having a greater diameter than the middle section to adjust for reduced volume. However, the configuration of the &#39;116 patent requires major tooling and process modifications from those currently being employed to shape the upper and lower sections of the drum body to the greater diameter required. Additionally, larger covers and bottoms, as well as corresponding tooling, are required to seam the cover and bottom of greater diameter to match the increased diameter top and bottom sections of the body. 
     U.S. Pat. No. 4,781,301 describes a steel drum with a narrowed rolling hoop diameter having corrugated sides. To make up for a smaller diameter rolling hoop the drum of the &#39;301 patent includes additional corrugations across the drum body. However, the corrugations require additional processing, and additional material. Also, the added corrugations increase the problem areas when a full drum is dropped since the rounded rolling hoops tend to be the point of failure in a drop test. 
     Additionally, unless the diameter is small enough that the drums fit easily, the rounded rolling hoops of both the &#39;116 and &#39;301 patents have a tendency to ride-up on the hoops of adjacent drums when placed four (4) across in an ISO container. On the other hand, if the diameter is made small to avoid the rolling hoops from riding up on one another, additional bracing will be required in the ISO container. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a 55 gallon steel drum which will fit four (4) abreast in an ISO shipping container with minimum bracing in the ISO container. It is also an object to provide such a drum which has the volume and dimensions of a standard 55 gallon drum and can be made out of the same size pieces of material with the same equipment and process as the standard drum. 
     Other objects include a drum which has similar or superior performance characteristics to the standard drum and a rolling hoop which will bear against an adjacent hoop rather than stride it when packed tightly. 
     These and other objects are achieved with the metal drum of the present invention comprising a top, a bottom and a cylindrical body, said cylindrical body having thereon a rolling hoop having a substantially flattened face, wherein the diameter of the rolling hoop is not greater than 231/4 inches and is deformable from a circular to an elliptical configuration. As such, other than the shape of the swedger tooling, the material, equipment and processing currently involved in the manufacture of the drums of the prior art need not be modified to produce the drum of the present invention. 
     Moreover, the preferred drum has two rolling hoops, at about 1/3 and 2/3 of the height of the drum, as with the standard drum of the prior art making the drums of the present invention compatible with the drums of the prior art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The annexed drawings, in which like reference characters represent like parts, are intended to illustrate the present invention without limiting the invention in any manner whatsoever. 
     FIG. 1 is an elevation view in cross section of the standard 55 gallon drum of the prior art. 
     FIG. 2 is a partial elevation in cross section of the rolling hoop of the prior art drum in the area of A on FIG. 1. 
     FIG. 3 is an elevational view in cross section of the drum of the present invention. 
     FIG. 4 is a partial elevation in cross section of the rolling hoop of the drum of the present invention in the area of B on FIG. 3. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The prior art 55 gallon steel drum 2, as shown in FIG. 1, has a cover 4, a bottom 6 and a cylindrical body 8 therebetween. The cylindrical body 8 has two rolling hoops 10 at approximately one-third and two-thirds of the height of the drum 2. 
     The dimensions of the standard 55 gallon steel drum of the prior art include a height of 343/8 inches, diameter of the cylinder body of 221/2 inches and diameter of the rolling hoop of 2315/32 inches. The upper rolling hoop is 117/16 inches from the top of the drum 2 and the lower rolling hoop is 117/16 inches from the bottom of the finished drum 2 with 111/2 inches between the rolling hoops. 
     The cylinder body 8 is welded into a circular configuration from a sheet of cold rolled steel, generally 18 or 20 gauge ASTM 1060, commercial class 1, which is 353/4 inches high by 703/4 inches wide. Once the cylindrical body 8 is welded into a circular configuration, the rolling hoops 10 are then formed with a swedger to create an arcuate bump, as shown in FIG. 2, having a radius of about 1/2 inch so that the outer edge of the rolling hoop protrudes 7/16 of an inch beyond the cylinder body 8. The head 4 and bottom 6, each having a diameter of about 221/2 inches to fit within the top and bottom ends of the cylinder body 8, are then attached to the cylinder body 8 with a closed chime. 
     The preferred drum 12 of the present invention, shown in FIG. 3, is made from the same sheet of material having the same dimensions as the drum 2 of the prior art, i.e. 353/4 inches by 703/4 inches. The height of the preferred drum 12 is 343/8 inches and the cylinder body 18 has a diameter of 221/2 inches, as with the prior art drum 2. The head 4 and bottom 6 are the same size as with the prior art drum 2 since the cylinder body 8 of the present drum 12 is the same as the prior art. Similarly, the upper and lower rolling hoops 20 are placed at approximately 117/16 inches from the top and bottom of the finished drum 12, respectively, with 111/2 inches between the two rolling hoops 20. 
     However, the swedger tooling used to form the rolling hoops 20 of the present drum 12 is not arcuate as with the formation of the prior art rolling hoops 10. Rather, the swedger tooling used to form the preferred rolling hoops 20 of the present invention have a flattened face from about 1/2 inch to about 11/2 inches in width, and most preferred approximately 3/4 of an inch in width. The edges of the swedger tool adjacent the flattened area have a tight radius, only enough to avoid the material stress in forming a 90° corner, with 1/16 to 1/8 of an inch being preferred. 
     The flattened face swedger tool creates the preferred rolling hoop 20 formed on the drum 12 having a flattened portion 22, as shown in FIG. 4. The flattened portion 22 of the preferred rolling hoop 20 of the present invention is about 3/4 of an inch wide but only extends about 1/4 of an inch outwardly from the cylinder body 8. Therefore, although the rolling hoop 20 of the present drum 12 is wider than the rolling hoop 10 of the prior art drum 2, it does not extend as far outwardly, keeping the amount of steel used, the overall drum dimensions and drum volume consistent with the prior art drum 2. This modification, however, provides that the total diameter of the preferred drum 12 of the present invention at the rolling hoop 20 is about 231/4 inches. 
     Additionally, the flattened portion 22 of the rolling hoops 20 of the present drum 12 provides a bearing surface so that two adjacent drums 12 can be slid together in a tight environment bearing on the rolling hoops 20. This eliminates the problem of the prior art where the rounded rolling hoop 10 of one drum 2 would ride-up on the rolling hoop 10 of an adjacent drum 2 when packed tightly. 
     The aspect of a flattened rolling hoop 20 creating a bearing surface is especially important wherein the combined diameters of four (4) of the present drums 12 side by side, i.e. 93 inches, is slightly larger than the width of an ISO container, i.e. 92 inches. Moreover, the drum 12 of the present invention having flattened rolling hoops 20 allows for the circular configuration of the rolling hoops 20 of the drum 12 to be deformed into an elliptical configuration when placed four (4) across in a shipping container. The deformation of rolling hoop 20 upon tight packing minimizes the need for additional lateral bracing within the ISO container. 
     Additionally, the flattened section 22 of the rolling hoop 20 imparts additional stacking and dropping strength to the present drums 12. Due to the radial configuration of the prior art rolling hoop 10, the hoop 10 is more likely to collapse under stacking load or when dropped. However, due to the flattened section 22 the rolling hoop 20 of the present drum 12 resists collapse better than the rolling hoop 10 of the prior art drum 2. 
     Although alternative embodiments will be apparent to those skilled in the art reading the above disclosure, all such variations are intended to be included within the spirit and scope of the present invention, limited only by the appended claims. 
     All patents cited herein are incorporated by reference.