Drum closure system: closing ring, crimping machine and method of use

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

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.

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

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.

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.

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

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:

FIG. 1aa is a plan view of the prior art desired drum closure.

FIG. 1b is a sectional view of the prior art drum closure assembly at fit up.

FIG. 1c is a sectional view of the prior art drum closure assembly at closure;

FIG. 1d is a plan view of the prior art drum closure joint;

FIG. 1e is a sectional view of the prior art drum closure assembly and compression tool;

FIG. 2a is a plan view of the present invention drum cover;

FIG. 2b is a sectional view of the drum closure assembly at fit up;

FIG. 2c is a sectional view of the drum closure assembly at compression;

FIG. 2d is a sectional view of the drum closure assembly at closure

FIG. 2e is a plan view of the drum closure bolt joint of the present invention;

FIG. 3a is perspective view of the upper forming tool;

FIG. 3b is a sectional view of the upper forming tool and drum closure assembly at fit up;

FIG. 3C is a sectional view of the upper forming tool and drum closure assembly at compression;

FIG. 4a is a perspective view of the lower form tool retracted;

FIG. 4b is a perspective view of the lower form tool retracted;

FIG. 4c is a sectional view of the lower form tooling condensed;

FIG. 5A to 5L is a sequential series showing movement of the major components of a closure machine incorporating the principles of the present invention;

FIG. 6A is an elevational view of the major components of a closure machine prior to compression of a drum closure assembly

FIG. 6b is an elevational view of the major components of a closure machine with the gasket compressed by the lower hydraulic ram;

FIG. 6C is an elevational view of the major components of a closure machine with the lower form tool condensed;

FIG. 6D is an elevational view of the major components of a closure machine at closure;

FIG. 6E is a sectional view of the major components of a closure machine in accordance with this invention;

FIG. 7 is a sectional view of the upper form tool with the drum gasket in compression; and

FIG. 8A to 8D show an alternative embodiment for crimping the ring in place.

DESCRIPTION OF THE PREFERRED EMBODIMENT

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.

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. 2a. 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.

The assembly mechanism embodying this invention includes solid upper form tooling 20 shown in FIG. 3A to 3C, segmented lower form tooling 30 as illustrated in FIG. 4A to 4D* 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 5L.

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.

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'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

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:

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.

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.

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.

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 & B and 6A.

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 & D and 6B. 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.

With all components compressed to the desired finished height as in FIGS. 5c and 6b, 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 6C. This Swage Die is then moved axially toward upper form tooling as shown in FIGS. 5f-5i and 6d . . . 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.

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'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.

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 5L.

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 8C. 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.

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

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.

Claims

1. An improved ring construction for use in a drum closure assembly wherein the drum closure assembly includes a drum body curl, and a drum cover, said ring construction comprising and annular metallic strip having a generally L shape defined by an upper leg and a depending open leg, said upper leg partially overlying said drum cover and said depending leg extending below said drum body curl.

2. An improved ring construction as defined in claim 1 wherein said strip has a first and second ends which substantially abut at a joint.

3. An improved ring construction as defined in claim 2 wherein said open leg defines an inner diameter greater than the diameter of said drum cover and said drum body curl.

4. An improved ring construction as defined in claim 3 wherein said open leg is formable to conform to the shape of said cover and drum curl.

5. An improved ring construction as defined in claim 2 wherein said strip has a threaded lug affixed at said first end and a unthreaded lug affixed at said second end and further comprising a threaded bolt passing through said unthreaded lug and engaging said threaded lug to fix said strip and lugs in rigid mechanical engagement before and after drum closure.

6. An apparatus for sealing a drum using the ring construction of claim 1 comprising: an upper form tooling comprising an annular seat overlying said upper leg and a segmented lower form tooling comprising a plurality of segments movable radially and vertically relative to said upper forming tool.

7. Apparatus as defined in claim 6 wherein each segment had defined thereon a die face for engagement with said open leg such that said open leg is formed by said face into conforming relationship with said drum curl and cover.

8. Apparatus as defined in claim 7 wherein said drum closure assembly includes a gasket intermediate said drum curl and said drum cover and said apparatus further comprising an actuator for compressing said top form tooling, said upper leg, said drum cover, said gasket and said drum curl to a desired position.

9. Apparatus as defined in claim 8 further comprising at least one actuator operatively connected to said lower form tooling to urge said segments of said lower form tooling selectively between a retracted position and a condensed position.

10. An apparatus for sealing a drum wherein said drum has an open end with an annular drum curl formed thereon and a drum cover overlying open end and said drum curl, comprising: an upper forming tool defining a seat against which said drum cover and portion of a drum ring overlying said drum cover abut, a plurality of segments defining lower form tooling selectively movable between a retracted position and a condensed position wherein said segments each include a die face for engaging a portion of said drum ring extending below said drum curl for forming said drum ring to seal said drum.