Patent Publication Number: US-5829624-A

Title: Protective shoe for open top metal containers

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention is directed to an improvement in metal containers and more particularly to round metal containers known as drums. 
     As shown in FIG. 1, what are known as &#34;open top&#34; metal drums have the configuration as generally shown at 10. The metal drum body 11 has a side wall 11A and a rounded rim 12 at the open end thereof which receives an open top or cover 13 having a planar surface 14 surrounded by an annular upwardly slanting surface 15 which blends into a rounded lip 16 forming approximately a 180° arc segment. The lip has a sealing gasket at an inside periphery (not visible in FIG. 1), and the radius of the lip is designed to approximately match the radius of the rim so that when the cover 13 is placed on the drum body 11 the upwardly slanting surface 15 is in a press-fit relationship with an inside diameter of the drum body near the rim 12, and the lip 16 fits over the rim 12. Thereafter a locking ring 17 formed of a rounded strip 18, facing ends 18a and 18b and lugs 19 and 20 at the ends 18a and 18b can be slipped over the lip 16 and rim 12 to seat the cover 13 on the top of the drum body 11. To complete the sealing operation, a bolt 21 having threads 21a is aligned through the aperture 20a of the lug 20 and is threaded into the threads 19a of the lug 19 by applying a tool to the head 21b of the bolt. Alternatively, a nut 9 shown in dashed lines may be applied on the threads 21a in lieu of the threads 19a in the lug 19. 
     The lugs 19 and 20 are welded at the ends 18a and 18b of the locking ring 17 in a position such that they are angled downwardly as shown at FIG. 1. 
     The locking ring 17 described above provides, in conjunction with the aforementioned gasket, a tight fluid proof seal between the cover and the drum or container body 11. However, in view of the gap shown by the arrow at 22 between ends 18a and 18b, there is a portion of the periphery of the lip 16 and rim 12 which is left uncovered. This can cause potential fluid leakage at this point. Moreover, the sealing pressure around the entire periphery of the drum is disrupted at the gap 22. 
     It is furthermore important that drums or containers of the type shown in FIG. 1 be designed to successfully pass what are known as &#34;drop tests&#34; wherein the drum body is filled with fluid, and then is dropped from predetermined elevations to determine whether damage will occur to the sealing integrity of the drum. It has been known in the past that leakage can occur at the gap 22 of the locking ring 17 as a result of the drop test, and deformation of the drum can occur at this point in view of the lack of a uniform distribution of the sealing pressure about the entire periphery of the drum or container. 
     It is also known that a sealing gasket which is typically applied inside the lip 16 of the cover 13 can be damaged at the gap 22, since this area of the gasket is not protected when the locking ring is placed on the drum, and thus this portion of the sealing gasket can be exposed to the elements. 
     It was previously known in the art as shown in FIG. 2 to fill in the gap 22 at the ends 18a and 18b of the locking ring by providing an overlapping smaller curvature section 23 which overlaps inside an extension section 24 of a larger curvature as shown in FIG. 2 . Thus the gap between the ends 18a and 18b is filled in by the overlapping sections. 
     With this system, however, there is the significant disadvantage that existing rings already on the market and in the field must be thrown away and replaced with the overlapping locking ring-type as described above. This is not a practical approach in view of the many millions of locking rings currently existing in the field which are in continual re-use. Moreover, the manufacturing expense for the overlapping locking ring described above is significant, which is an important consideration for a commodity item such as locking rings where profit margins are low. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to solve the sealing problems described above with a low cost solution which also is compatible with existing locking rings in the field. 
     According to the present invention, a container securing system and method is provided wherein a round container having an upper rounded rim at an open end thereof receives a cover at the open end, the cover having a rounded lip for substantially mating with and partially covering an upper portion of the rim when the cover is applied on the container. A locking ring formed of a rounded strip engaging the lip and rim around the periphery of the container is provided for sealing the cover on the container. The locking ring has first and second ends with a gap therebetween. The locking ring has a securement system for pulling the first and second ends of the locking ring towards each other when the locking ring secures the cover to the container. A protective shoe formed of a curved strip of material is positioned in the gap of the locking ring when the locking ring is securing the cover on the container. The protective shoe has a length in a peripheral direction around the drum which is greater than a length of the gap so that end portions of the strip overlap with portions of the ends of the locking ring. The protective shoe extends at least from a region at the top of the cover lip around the cover lip and around the bottom portion of the rim to a side wall of the container directly beneath the rim. 
     Other objects and advantages of the present invention will be apparent upon reference to the accompanying description when taken in conjunction with the following drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a prior art drum or container system having an open top cover retained by a prior art locking ring; 
     FIG. 2 shows a fragmentary rear view of a prior art locking ring attempting to solve fluid sealing problems existing in the prior art locking ring system of FIG. 1; 
     FIG. 3 is a perspective view showing a first embodiment of the invention employing a protective shoe which is compatible with existing locking rings to improve sealing for open top metal containers; 
     FIG. 4 is a fragmentary cross-sectional view taken along Section line 4--4 in FIG. 5 showing the invention of FIG. 3; 
     FIG. 5 is a sectional view taken along section line 5--5 of the first embodiment of the invention of FIG. 3; 
     FIG. 6A is a fragmentary cross-sectional view of a second embodiment of the invention; 
     FIG. 6B is a perspective fragmentary view of the second embodiment of FIG. 6A; 
     FIG. 7A is a cross-sectional fragmentary view of a third embodiment of the invention; and 
     FIG. 7B is a fragmentary perspective view of the third embodiment of FIG. 7A. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The first embodiment of the present invention is shown in FIG. 3. There, the same drum or container body 11 as FIG. 1 is provided having the same style of the rim 12 covered by an open top or cover 13 having the same type of lip 16 as in the prior art cover shown in FIG. 1. Such a drum can be, for example, a 30 gallon, 55 gallon, or 85 gallon drum, including what are known as &#34;salvage&#34; drums. Furthermore, the locking ring 17 is the same as in the prior art design shown in FIG. 1. However, according to the invention a protective shoe 25 is arranged as shown more clearly in FIGS. 4 and 5 over the lip 16 and rim 12 of the cover 13 and drum body 11, respectively. The protective shoe 25 is retained in this position by a spring force to be described hereafter. After application of the protective shoe 25, the locking ring 17 is then applied such that the gap 22 overlies and is centered over the protective shoe 25. Since the protective shoe 25 is longer than the gap 22, it covers the gap when the locking ring 17 is applied. Thereafter, the bolt 21 is threaded into the lug 19 and the locking ring is secured on the drum. 
     More particularly as shown in FIGS. 4 and 5, the protective shoe 25 has an optimum extension length in the peripheral direction of three to four inches with the preferred length being approximately 31/2 inches. As shown in the cross-sectional view of FIG. 5, the shoe has a substantially circular arc segment 25A lying to the upper left of the dashed line 26 of approximately a 180° arc. Thereafter, there is a straight section 25B indicated between the dashed lines 26 and 27. Thereafter there is a rounded section 25C followed by a short straight vertical section 25D. 
     As can be seen in FIG. 5, the protective shoe 25 covers over the exposed portion of the gasket 28 at the gap 22 extending below the lip 16. 
     Preferably the entire meandering length of the protective shoe from a top edge to a bottom edge is 1.75 to 2.5 inches with a preferred length of approximately 2 inches. 
     Preferably the protective shoe is constructed of 22 gauge steel such as cold roll carbon steel, although stainless steel can also be employed. The protective shoe should be no thicker than 20 gauge. 
     The radius of the 180° segment 25A is slightly smaller than the radius of the lip 16, so that a springy press-fit relationship can be obtained when the protective shoe is applied to the lip 16 and rim 12 with the cover on the drum prior to the application of the locking ring. Thus, the locking ring gap 22 can be centered over the protective shoe without the shoe moving around the periphery of the drum during the installation of the locking ring. 
     With the embodiment of FIGS. 3, 4 and 5, the prior art locking ring can be employed and the protective shoe can be retrofitted for use with existing locking rings, covers and drums in the field without modifications thereto. Furthermore, the fluid sealing capability and the ability to withstand drop testing is significantly increased by use of the protective shoe, since it fills in the gap and, the locking ring interacting and together with the protective shoe can then provide a continuous sealing pressure around the entire 360° periphery of the drum. The overall strength of the drum is significantly increased and the chance of leakage at the gap is significantly reduced. Furthermore, damage to the gasket 28 at the gap of the locking ring is eliminated. 
     Moreover, by providing the short straight section 25D, it can be seen that the locking ring will pull the protective shoe even tighter at the gap, since the edge 17A of the locking ring presses against the rounded portion 25C and clamps the short straight section 25D against the body side wall 11A of the drum 11. The protective shoe is thus securely held in position. 
     A second embodiment of the invention is shown in FIGS. 6A and 6B. Here, the protective shoe 29 of the invention is first fitted to the prior art locking ring 17 before the locking ring is applied to the drum body for securing the cover 13. As shown in FIG. 6B, the protective shoe 29 is positioned at the gap 22 between the ends 18A and 18B and is held there by a springy clamping force provided by the U-shaped lip 29A which clamps onto the upper edge 17B. Thus when the protective shoe 29 has not yet been applied, then the upper portion 29AA is bent inwardly slightly such that the leading edge of the upper portion 29AA is spaced from the lower portion 29AAA of the U-shaped lip by a distance which is slightly less distance than the thickness of the edge 1 7B at the top of the locking ring. Thus, when the protective shoe 29 is slipped onto the locking ring at the gap 22, it is retained at the gap. 
     As shown in FIG. 6A, between the U-shaped lip 29A and dashed line 30 is a substantially straight section 29B. Thereafter, between the dashed lines 30 and 31 an arc segment 29C is provided where the arc is approximately 150°. The radius of this arc segment is substantially the same as the radius of the drum ring 17 at this region. Thereafter, a second straight section 29D is provided between the dashed lines 31 and 32. Thereafter, a rounded section 29E is provided which then merges into a short vertical section 29F. The longitudinal extent in the horizontal direction of the protective shoe 29 is the same as that specified for the first embodiment. The preferred overall meandering length of the protective shoe from a top edge to a bottom edge, is approximately 21/4 inches within a range of 2 to 23/4 inches. The gauge is the same as the first embodiment. Sealing capabilities for this embodiment are similar to the first embodiment. 
     In a third embodiment of the invention as shown in FIGS. 7A and 7B, the protective shoe 33 is spot welded at the inside surface of the edge 16A of the lip 16 of the cover 13 prior to application of the cover on the drum body. A short vertical mounting section 33A is provided for this spot welding attachment. A horizontal transition section 33B is provided so that the curved arc segment portion 33C matches the exterior radius of the cover lip 16 so that a smooth transition without a gap or step occurs from the edge 16A to the protective shoe 33. The arc segment 33C extends from the horizontal portion 33B down to the dashed line 34 and represents an arc segment of approximately 60°. Thereafter, a straight section 33D is provided followed by a rounded section 33E and thereafter a short vertical section 33F. 
     The overall meandering length of the protective shoe from a top edge to a bottom edge is approximately 15/8 inch optimum and within a range from 11/2 inches to 13/4 inches. The vertical mounting section 33A is approximately 1/4 inch long and within a range of 1/8 inch to 3/8 inch. The length in a lateral direction around the periphery of the drum is the same as the first and second embodiments, as is the steel type. 
     With the third embodiment, since the protective shoe is made of a sufficiently thin material so as to be springy, when the drum cover 13 is applied onto the drum body 11, the protective shoe is bent slightly downwardly to allow the drum rim 12 to pass into the interior region defined by the lip 16 and the protective shoe 33. The protective shoe 33 to some extent springs back into place. In any event, the locking ring 17 which is then applied takes care of any temporary deformation which may have occurred in the protective shoe since the locking ring lower edge 17A pushes the short straight section 33F against the side wall 11A drum body 11 similar to the first and second embodiments. Of course when the locking ring is applied, it is positioned so that the gap 22 overlies and is centered with respect to the protective shoe 33. 
     Although various minor changes and modifications might be proposed by those skilled in the art, it will be understood that our wish is to include within the claims of the patent warranted hereon all such changes and modifications as reasonably come within our contribution to the art.