Abstract:
An improved drum ring and apparatus for forming the ring during sealing of a drum utilizes a depending open leg having an initial diameter larger than the head of the drum to be sealed and a cover associated therewith. The open leg is deformable about the drum cover and drum body curl by a segmented forming tool to seal said cover to said drum in a compressed condition.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to split locking rings, and assembly methods for those locking rings, used for closure of shipping drums or barrels with removable covers.  
         [0002]     Current methods for affixing removable covers and sealing gaskets to shipping drums make use of a container design which includes at its open end a drum curl of circular section, a removable cover having an upward and outward protruding flange of similarly arcuate shape as the drum curl, and a gasket suitable for compressing between the curl and cover. Contact and sealing of the curl and cover with the compressible gasket is facilitated by the use of a metal or plastic ring. The ring utilizes any of a variety of angled or tapered “U” or “V”-shaped sections opening radially inward toward the center of the drum. The inside surfaces of the ring simultaneously engage the bottom of the drum curl and the top of the drum cover tangentially. The ends of the locking ring are drawn circumferentially toward one another through the use of a threaded fastener or an over-center type locking buckle, thereby forcing the ring further over the drum curl and cover, and forcing these two members ever closer together, trapping and compressing the sealing gasket between them, thus closing the drum.  
       SUMMARY OF THE PRESENT INVENTION  
       [0003]     It is an object of the present invention to provide an improved combination closing ring design, and a device and system for assembling the closing ring onto the drum, that results in increased package reliability, and increased package manufacturing efficiency.  
         [0004]     These and other objects of the present invention are accomplished through the use of a drum ring which is only partially formed prior to placement on the drum and a drum sealing device the completes the formation of the drum ring on the drum and lid during the sealing process.  
         [0005]     These and other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiment of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     An apparatus for crimping rings on drum heads—embodying the features of the present invention is depicted in the accompanying drawings which form a portion of this disclosure and wherein:  
         [0007]      FIG. 1   aa  is a plan view of the prior art desired drum closure.  
         [0008]      FIG. 1   b  is a sectional view of the prior art drum closure assembly at fit up.  
         [0009]      FIG. 1   c  is a sectional view of the prior art drum closure assembly at closure;  
         [0010]      FIG. 1   d  is a plan view of the prior art drum closure joint;  
         [0011]      FIG. 1   e  is a sectional view of the prior art drum closure assembly and compression tool;  
         [0012]      FIG. 2   a  is a plan view of the present invention drum cover;  
         [0013]      FIG. 2   b  is a sectional view of the drum closure assembly at fit up;  
         [0014]      FIG. 2   c  is a sectional view of the drum closure assembly at compression;  
         [0015]      FIG. 2   d  is a sectional view of the drum closure assembly at closure  
         [0016]      FIG. 2   e  is a plan view of the drum closure bolt joint of the present invention;  
         [0017]      FIG. 3   a  is perspective view of the upper forming tool;  
         [0018]      FIG. 3   b  is a sectional view of the upper forming tool and drum closure assembly at fit up;  
         [0019]      FIG. 3C  is a sectional view of the upper forming tool and drum closure assembly at compression;  
         [0020]      FIG. 4   a  is a perspective view of the lower form tool retracted;  
         [0021]      FIG. 4   b  is a perspective view of the lower form tool retracted;  
         [0022]      FIG. 4   c  is a sectional view of the lower form tooling condensed;  
         [0023]      FIG. 5A  to  5 L is a sequential series showing movement of the major components of a closure machine incorporating the principles of the present invention;  
         [0024]      FIG. 6A  is an elevational view of the major components of a closure machine prior to compression of a drum closure assembly  
         [0025]      FIG. 6   b  is an elevational view of the major components of a closure machine with the gasket compressed by the lower hydraulic ram;  
         [0026]      FIG. 6C  is an elevational view of the major components of a closure machine with the lower form tool condensed;  
         [0027]      FIG. 6D  is an elevational view of the major components of a closure machine at closure;  
         [0028]      FIG. 6E  is a sectional view of the major components of a closure machine in accordance with this invention;  
         [0029]      FIG. 7  is a sectional view of the upper form tool with the drum gasket in compression; and  
         [0030]      FIG. 8A  to  8 D show an alternative embodiment for crimping the ring in place. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]     Referring to the Figures for a clearer understanding of the invention, prior art affixation of removable covers and sealing gaskets to shipping drums make use of a drum  100  which includes at its open end a drum curl  101  of circular section, a removable cover  103  having an upward and outward protruding flange of similarly arcuate shape as the drum curl, and a gasket  102  suitable for compression between the curl and cover as shown in  FIG. 1C . Contact and sealing of the curl and cover with the compressible gasket is facilitated by the use of a metal or plastic ring  10 . The ring  10  utilizes any of a variety of angled or tapered “U” or “V”-shaped sections opening radially inward toward the center of the drum as shown in  FIGS. 1B and 1C . The inside surfaces of the ring  10  simultaneously engage the bottom of the drum curl and the top of the drum cover tangentially as shown in  FIG. 1B . The ends of the locking ring are drawn circumferentially toward one another through the use of a threaded fastener  15  passing through threaded  11  and non-threaded metal lugs  12  affixed to the ends  13 ,  14  of the ring, thereby forcing the ring further over the drum curl and cover, and forcing these two members ever closer together, trapping and compressing the sealing gasket between them, thus closing the drum as shown in  FIG. 1C .  
         [0032]     In the description of the preferred embodiment like numbers will be used for components that are consistent with the prior art. It may be seen in  FIGS. 2B and 2A , that in the present invention, the closing ring assembly comprises of a metal ring  10  of approximate “L”-shape, threaded  11  and non-threaded metal lugs  12  affixed to the ends  13  of the ring, and a bolt  15  of diameter and threads to match the lugs. Ring  10  includes a top leg  16  of the “L” designed in accordance with conventional practice, its length, angles, bends and features selected to provide good package performance in tests for hydrostatic pressure and vertical drop. In as much as ring  10  is intended to be formed to a final configuration when used in conjunction with a drum  100 , an open leg  17  of ring  10  may be straight, slightly angled, or curved, depending on the desired final shape after forming, and compatibility with the tooling selected for use in the forming operation. The diameter generated by the configuration of open leg  17  must be such that when the ring assembly is drawn to minimum circumference, the ring still may be easily positioned over the top of a loosely assembled drum curl  101 , gasket  102 , liners where applicable, and cover  103  combination as shown in  FIG. 2   a . The length of open leg  17  is determined and selected such that upon completion of the forming operation onto the specific drum for which the ring is designed, a gap ranging from 1/32″ to ⅛″ is maintained between the end of leg  17  and drum body  100  as shown in  FIG. 2D .  
         [0033]     The assembly mechanism embodying this invention includes solid upper form tooling  20  shown in  FIG. 3A  to  3 C, segmented lower form tooling  30  as illustrated in  FIG. 4A  to  4 D* as well as associated actuators and controls required for the purposes of transforming “L”-shaped ring  10  into a “U” or “V”-shaped ring  10 , i.e. forming, closing or crimping the ring  10  onto the drum as exemplified in  FIGS. 5A  to  5 L.  
         [0034]     The configuration of upper form tooling  20  is specific to each application in that its diameter and its annular profile seat or contour precisely matches top leg  16  of ring  10 , selected as described above, for the package in question. During forming of the open leg  17 , the upper form tooling  20  is responsible for holding the closing ring  10  rigidly in place and on center with the drum, for maintaining the integrity of the profile of top leg  16 , and for transmitting an axial force to the package assembly which compresses together all the components of the package including drum curl  101 , drum liners, drum gasket  102 , and drum cover  103 .  
         [0035]     Lower form tooling  30  cannot be solid since at the completion of the ring forming operation, its inside diameter will by necessity be smaller than that of the drum body curl  101  as well as the outside diameter of the ring. Instead it must be sectional, so that it starts at a diameter large enough to envelop the outer diameter of the ring&#39;s open leg  17 , form it to a diameter which creates the gap described earlier between ring  17  and drum  100  body, and then return to a diameter large enough to allow it to be withdrawn from the diameter of the drum and completed ring. Like upper form tooling  20 , the configuration of the lower form tooling is specific to each application. Its minimum interior diameter and profile precisely match that of the formed ring in its completed configuration thus each segment  31  has a die face  32  formed on its inner profile for engagement with outer leg  17 . Two methods are disclosed as exemplary for moving lower form tooling  30  and the closing ring open leg  17  from its initial shape to its finished, formed shape, ie. open leg  17  may be either swaged or crimped into shape, with the method chosen to best suit the desired finished shape for each specific application  
         [0036]     The process for using this ring and ring closing or forming mechanism, hereafter referred to as the closure system, are described as follows: Ring  10  is manufactured in its “L”-shaped configuration. Lugs  12  are attached to ring ends  13 ,  14 . Bolt  15  is installed into the lugs and tightened to its final engagement. This assembly step represents the first innovation and improvement realized through the use of this closure system. Conventional rings require that the bolt cannot be assembled until the ring is positioned onto the drum. Pre-assembling the bolt to its final engagement overcomes the following disadvantages of the prior art:  
         [0037]     1) When not subjected to the interference and awkwardness generated by the body of a drum, bolt  16  insertion may be properly aligned and thus installed faster and more accurately. When installing the bolt on conventional rings, cross threading of bolt to lug is a persistent concern as shown in  FIG. 1D .  
         [0038]     2) Bolt  15  may be tightened to a mechanical preload, as is the common practice for all bolted joints. Conventional rings, when bolted at final assembly, leave a gap “D” in the mechanical joint that prevents the proper preloading of the bolt, and induces bending moment stresses and distortion “         ” into the bolt again as show in  FIG. 1D .  
         [0039]     In the present invention, with bolt  15  preloaded, and lugs  12  thus held together as a solid mechanical entity, the loading transmitted from the lugs  12  to the ring  10  is one of almost pure shear. No bending moments are induced on the joint from lug  12  to ring  10  and the joint is thus strengthened considerably.  
         [0040]     At fit-up, drum  100 , drum liners if required, gasket  102 , and cover  103  are all assembled and ring  10  is placed over drum cover  103 . Alternately, ring  10  may be pre-assembled onto a cover  103 , or onto a cover and permanently affixed gasket, and then placed onto a drum  100 . In either case, this assembly step represents the second innovation and improvement realized through the use of this closure system. Because conventional rings are, at initial assembly, smaller at their opening than the combined heights of the drum curl, liners, gasket and cover, the conventional ring has little ability to stay in place on the drum. Not until the cover and gasket are compressed, allowing the drum assembly to “sink” into the “U” or “V” of the ring, will the ring normally stay on the drum. Furthermore, conventional rings have little ability to assist in the alignment of the drum components. However ring  10  described in this invention successfully facilitates both of these goals. Top leg  16 , which is, at assembly, already secured with a diameter smaller than that of cover  103 , prevents the ring  10  from sliding off cover  103  and down around the body of the drum  100  to the floor. Open leg  17  of ring  10  simultaneously capture cover  103 , gasket  102  and curl  101  of the drum assembly and prevent their movement off center one from another. Thus fit up may occur well be for machine entry as shown in  FIGS. 5A  &amp; B and  6 A.  
         [0041]     The first step in the closure process is to compress the drum/gasket/cover/ring assembly to its desired finished height as shown in  FIGS. 5C  &amp; D and  6 B. This step represents the third innovation and improvement realized through the use of this closure system. With conventional rings, the gasket and liner compression forces are applied to the drum cover and transmitted through the cover to the gasket in an offset path. This is because the top surface of the cover must be left vacant to accept the ring as it moves radially into place. The amount of force that can be applied is limited by the ability of the cover to transmit that force. However the ring and mechanisms described by this invention allow more direct application of the required compressive force. The upper form tooling provides an annulus for the application of the force directly to the ring  10 ; the ring transmits the force to cover  103 ; cover  103  transmits the force to the gasket  102 ; gasket  102  compresses against drum curl  101 , all in a straight line through the body of ring  10  and cover  103  as shown in  FIG. 7 . Thus, a substantially higher compressive force, limited only by the strength of the drum curl  101 , may be applied to compress the gasket and other components to the desired height.  
         [0042]     With all components compressed to the desired finished height as in  FIGS. 5   c  and  6   b , ring  10  is then mechanically formed, i.e. closed. In applications where the swage method is employed, segments  31  of lower form tooling  30  come together to form a continuous die with a small gap left at one quadrant to accommodate lugs  12  as shown in  FIGS. 4B, 5E , and  6 C. This Swage Die is then moved axially toward upper form tooling as shown in  FIGS. 5   f - 5   i  and  6   d  . . . As open leg  17  of the ring  10  contacts the combined die face  32  of lower form tooling  30 , leg  17  is swaged inward toward the drum curl  101  creating a conventional “U” or “V”-shaped cross section. The distance inward that the edge of open leg  17  travels, and thus the closed dimension of the ring  10 , is established by the vertical distance the lower form tooling  30  is allowed to travel and the profile of die face  32 .  
         [0043]     This step represents the fourth and fifth innovations and improvement realized through the use of this closure system. Because the final dimensions of the Ring&#39;s “U” or “V”-shaped cross section can be controlled at assembly, slight variations in the compressed height of the other components may be compensated for. Two drums differing only by the use or absence of a 50 mil drum liner for example, can use the same split locking ring. The ring on the drum without the liner is simply closed to an appropriate, smaller dimension.  
         [0044]     Furthermore, because ring  10  is closed by forming it in the same direction, i.e. radially, as the compressive force that keeps the drum sealed in the completed package, the reliability and uniformity of the fit of the ring to the drum and cover is enhanced. With a conventional ring that is tightened circumferentially, the circumferential movement of the ring that reduces its diameter and increases its compressive force is resisted by the friction generated between the ring, and the cover and drum curl. The tighter the ring is pulled, the higher the contact forces between the ring and the cover and curl. And the higher the contact forces, the higher the frictional resistance becomes. The ring becomes its own worst obstruction to proper tightening. In some areas, typically near the lugs, the conventional locking rings fully engage the drum cover and curl. In other areas however, the frictional forces can prevent the conventional locking ring from fully engaging the drum components. Inadequate engagement results in lowered clamping forces at the curl/gasket/cover joint. In the closure system described by this invention, no frictional forces are created as the Open Leg is formed. In fact, no forces resisting the closing action are encountered other than the bending of the ring material which is uniform, predictable, and easily controlled by the form tooling and the actuators  33  that move it as shown in  FIG. 6 . With the ring forming complete, lower form tooling  30  retracts and expands to allow removal of the completed drum package as shown in  FIGS. 5J  to  5 L.  
         [0045]     In applications where the crimp method is employed, the segments  31  of lower form tooling  30  are pivotally mounted to upper tool  20  and come together to form a continuous die face  32  as open leg  17  is formed, rather than before as illustrated in  FIGS. 8A  to  8 C. The movement of segments  31  is a rotational combination of the axial and radial directions and may be effected by actuations cooperatively attached thereto. The result is the same. The ring is formed inwardly against the drum curl in the radial direction, free from frictional forces created by the force of the ring sliding against the drum cover and drum curl. And the degree of closure is controlled by the distance the crimping segments are allowed to rotate.  
         [0046]     A split, bolted locking ring that can be preassembled in mass production at a factory level, final formed in place using an automatic machine as the drum is produced, and then re-used like a conventional locking ring by the drum purchaser, represents a significant innovation in the shipping container industry. Manual closing of conventional split locking rings requires 15 to 20 seconds per package and may require two people. The exemplary machine pictured requires a maximum of one person to operate and final assembles a drum in approximately 8 seconds. The combination of the locking ring configuration and the forming equipment put forth in this invention successfully automates this assembly process, and simultaneously improves the reliability of the open head container package  
         [0047]     It is to be understood that the form of the invention shown is a preferred embodiment thereof and that various changes and modifications may be made therein without departing from the spirit of the invention or scope as defined in the following claims.