Title of Invention

CLOSURE PLUG AND OVERSEAL

Abstract

A closure combination of a closure plug for shipping containers and a tamper evident, closure overseal, the closure plug (6, 45) and the overseal (20, 52) having hidden, complimentary, interlocking, snap-fit features (17, 49, 23, 56, 24, 57) and a frangible portion (26, 53a), to permit removal of the overseal from the plug, that is visible when the closure plug and the overseal are interlocked; the interlocking, snap-fit features may be internal or external of the closure plug but are hidden by the overseal skirt (22, 54) and the overseal is destroyed on removal from the closure cap.

Full Text

CLOUSURE PLUG AND OVERSEAL This invention is directed to a closure combination comprising a closure plug and a tamper evident, closure overseal for shipping containers; such as drums. BACKGROUND OF THE INVENTION In today's global political climate the security of drummed products is coming under ever closer scrutiny.- This, coupled with the need for normal tamper vigilance, is driving a trend toward the increased use of effective tamper indicating seals on all types of shipping containers. It has long been the practice to apply overseals of one kind or another with special hand and power tools which were able to crimp a metal portion of the overseal tightly around an upstanding opening neck designed to receive the seal This type of overseal is rather costly as are tools for their application. Moreover, the application step itself is quite labour intensive and relatively inefficient. Consequently a number of hand applied overseals have come forth which, to a certain degree obviate the above-mentioned application tools. These hand-applied overseals are for the most part easily snapped onto the container opening neck and usually almost as easily snapped off. While these plastic snap-on overseals serve to dress up a container such as a 55 gallon drum, giving the closure area a finished appearance and some added degree of cleanliness, there is still much to be desired in terms of drum security. To be effective such drum closure overseals need to meet a number of rather demanding criteria. Obviously the hand application has to be simple and relatively effortless to satisfy normal filling line speeds. Once the drum is shipped, of paramount importance is the ability of the overseal to guard against unauthorized access to the drum contents. This means that the overseal cannot be physically removed without destroying same or making such unauthorized access clearly noticeable and such that the overseal cannot be reapplied in unaltered form to the drum closure. In this regard, plastic, manually-applied overseals currently in general use for both steel and plastic drums are, for the most part, easily pried off in an undetected manner particularly when in a wanned state. In other words "easy-on easy-off'. Also of importance is the ability of the overseal to resist inadvertent damage during . handling and shipment. Commonly employed tamper detection devices such as frangible locking rings, shrink bands and the like found on consumer packages are not at all suited for use on 55 gallon drums. One can easily see that any inadvertent or accidental damage to the tamper resistant oversea! immediately raises the question, . has the drum security been breached or compromised in some wav or is ihi.s simply damage to be expected resulting from normal handling? This aspect dictates that any tamper detecting feature be sufficiently robust to remove any question of doubt as to whether unauthorized entry has in fact occurred. A performance criteria also of major importance is the ease with which the overseal can be removed from the underlying drum closure in an authorised manner such that subsequent replacement of the overseal is not possible. Normally this requires destruction of the overseal in some fashion to prevent reuse. In this regard the use of sharp cutting or puncturing implements is undesirable due to the likelihood injury or of accidental damage to the underlying closure. Thus, in addition to the overseal*s robust construction, hand removeability is yet another advantageous attribute. PRIOR ART Document DE-A-36 37 644 discloses a closure plug and tamper evident overseal combination for shipping containers (11), the closure plug (2) and the overseal (3) having hidden, complimentary, interlocking, snap-fit features (7, 8, 10) and a frangible portion (9) to permit removal of the overseal from the plug; the frangible portion being breaking notches (9) in half-shells (7); this leaves the overseal (3) visually undamaged when the notches have been broken, such that there is no immediate visual indication of tampering and it would be possible to reattach the overseal to the closure plug by use of an adhesive or the like. Close inspection of the overseal and cap would be required to detect such tampering. Also, the relative angular position of the plug and overseal is critical for fitting the one to the other as the half-shells (7) could foul the wrench attachments (5). Document US-A-5,996,S33 discloses a tamper evident dust cover (20) to engage the lip (80) of a for a drum bung (80) having a drum neck engaging locking ring (38) hinged to the cover sidewall (24); the cover has a diametral tear-off strip (35) to permit removal of the cover from the bung. Tear able' overseal s for closure plugs are also disclosed in documents US-A-1,771,012; US-A-2,760,671 and US-A-4,5203942. None of these documents disclose hidden snap-fit features between a closure plug and an overseal. OBJECT OF INVENTION It is an object of the present invention to provide a solution to the tamper-detection problems of the closure plug and tamper evident overseal combination as described in respect of document DE-A-36 37 644. STATEMENT OF INVENTION According to the present invention, in a closure combination of a closure plug for shipping containers and a tamper evident, closure overseal, the closure plug and the overseal have hidden, complimentary, interlocking, snap-fit features and a frangible portion to permit removal of the overseal from the plug; wherein the frangible portion is visible when the closure plug and the overseal are interlocked. Such a combination overcomes the above described prior art deficiencies because the overseal is so constructed that removal without destroying the overseal is virtually impossible. To apply the overseal to an upstanding container neck with the closure plug screwed in place, the overseal is pressed on top of the plug by hand causing the interlocking features of the overseal to snap-fit with the interlocking structure on the plug. The resulting interengagement is such that unauthorized removal of the overseal is prevented. Unlike other prior art arrangements the relative inaccessibility of the hidden interlocking features renders any kind of pry off tool quite useless. When it comes to removal in an authorized manner, manually tearing the visible frangible portion of the overseal results in the interengagement of the interlocking features being released and the overseal is easily removed. However, unlike the overseal of document DE-A-36 37 644, the overseal of the present invention is quite obviously destroyed and rendered completely unusable for resealing. According to an embodiment of the present invention, the visible frangible portion overlies, at least in part, the snap-fit features. According to another embodiment of the present invention, the closure plug comprises a cylindrical, cup-shaped body having a radially and circumferentially extending groove formed in the sidewall thereof, the overseal comprises a disc-like top surrounded by a peripheral, depending skirt with axially extending, resilient legs depending irom the top within the skirt; the distal end of each leg having a radially-extending foot designed for snap-tit, interlocking, engagement with the radial groove. According to a further embodiment of the present invention, the frangible portion is a diametrically extending tear strip in the overseal top. According to another, further embodiment of the present invention, the closure plug has axially extending wrench engaging lugs equi-spaced about the inner periphery of the plug sidewall and the space between lugs is at least as great as the width of the lugs; the groove is segmented and formed by a radial undercut at the base of each lug; and overseal leg feet extended radially outwardly to snap-fit under lugs into groove undercuts. According to a still further embodiment of then present invention, the groove opens radially outwardly from the plug sidewall and overseal leg feet extended radially inwardly to snap-fit into the groove. The present invention also extends to closure plugs and/or overseals in accordance with the combination of the present invention. The above and further features of the present invention are illustrated, by way of example, the following description and drawings. DRAWINGS Fig. 1 is a vertical cross sectional view of a closure combination in accordance with a first embodiment of the present invention; Fig. 2 is an enlarged fragmentary sectional view of the plug wrench engaging lug of the closure plug of Fig. 1; Fig. 3 is a top plan view of the closure plug of Fig. 1; Fig. 4 is a vertical cross sectional view of the closure overseal of Fig. 1: Fig. 5 is a bottom plan view of the overseal shown in Fig. 4; Fig. 6 is a vertical cross sectional view of a closure combination in accordance with a second embodiment of the present invention; Fig. 7. is a top plan view of the closure plug in Fig. 6; and Fig. 8. is a vertical cross sectional view of the closure overseal of Fig. 6. SPECIFIC DESCRIPTION In the embodiment shown by Figs 1 to 5. a wall 1 of a container, such as an industrial size plastic drum, has an upstanding neck 2 defining an internally threaded opening in the container wall. The neck 2 terminates at its upper end in an annular gasket seat 3a surrounded by an upstanding collar 4. Immediately beneath the collar 4 is a peripheral annular bead 5. A cup shaped closure plug 6, having a bottom wall 7 and an externally threaded sidewall 8, is screwed into the neck 2. The plug has a circumferentially enlarged head 9 with a gasket retaining groove 10 and resilient sealing gasket 11 on the undersurface thereof. Looking at the top surface of the plug in Fig. 3, there are a series of four equally spaced wrench engaging lugs 12 which are hollowed out as indicated at 13. Also, it can be seen that the width of the lugs 12 is slightly less than the width of the gaps 14 therebetween. Each lug has two radially extending wrench engaging surfaces 15 and a radially inwardly facing guide surface 16. The base of each lug 12, where it joins the plug bottom wall 7, is radially undercut to form a locking groove 17 designed to interlockingly engage the closure overseal in . a manner described hereinafter. The closure overseal 20 consists of an imperforate cap moulded of synthetic plastic resin having a disc-like top wall 21 surrounded by a peripheral depending skirt 22. A segmented collet depends from the central portion of the cap made up of a series of axially elongated leg segments 23 clearly shown in Fig. 4. Each segment terminates at its distal end in a radially outwardly projecting foot 24 having a bottom cam surface 25. A tear strip 26 is formed in the cap and is defined by a pair of score lines 27 extending diametrically across the top wall 21 so as to intersect the segmented collet shown, for purposes of illustration, with three of the segments 23 on one side of the. . tear strip 26 and three segments on the other side of the tear strip. As the score lines 27 approach the cap skirt 22 they diverge outwardly at 28 and continue across the skirt including the circumferentially enlarged portion 22a down to the skirt edge. A tearing ear 29 extends outwardly from either end of the tear strip and is provided with a raised outer edge bead 30 to facilitate gripping. In practice the plug 6 is screwed into the upstanding neck 2 of a shipping container. such as a blow moulded plastic drum, and tightened by a suitable plug wrench designed to exert a force against the wrench engaging surfaces 15 of the lugs 12. Tightening torque applied in this matter causes the gasket 11 to become compressed against the neck gasket seat 3 providing a leak proof liquid seal. The overseal 20 is then placed over the plug with the segmented collet generally axially aligned with the cental portion of the plug defined by the wrench engaging lugs. Simply pressing the overseal by hand onto the plug causes the camming surfaces 25 on the segment feet 24 to deflect the segments 23 radially inwardly upon forceful contact with the top of the wrench engaging lugs 12. As the segment feet move axially along the lug guide surfaces 16, the skirt free edge contacts the neck bead 5 causing the skirt enlargement 22a to expand thereover. In fully seated position the segment feet 25 snap into the wrench engaging lug grooves 17 expanding back out to their moulded position. This snap-fit interlocking engagement permanently secures the overseal to the plug and, of course, the plug to the container opening since the wrench engaging lugs are rendered inaccessible. In fact, as seen in Fig. 1, the segmented collet itself is inaccessible to any kind of pry off tool making unauthorized removal of the overseal extremely difficult, if not impossible, without destroying the overseal or certainly leaving very clear evidence of tampering. To assure the necessary security the accurate grooves 17 extend laterally and are disposed completely below the plug head top surface and open in an axial plane. The design of the closure plug and overseal is such that the overseal will snap-fit with the plug irrespective of their relative angular position. The overseal 20 is an interference fit on the container neck bead 5. To gain authorized access to the container contents one tearing ear 29 is grasped aided by the raised bead 30 and pulled outwardly separating the tear strip 26 along the score lines 28 and 27 from the rest of the cap. Removal of this top wall section allows the segmented collet to collapse; releasing the segment feet 25 from the grooves 17. This release condition occurs when the tearing action reaches the far side 4 of the top wall 21. At this point, the destroyed and released overseal simply lifts off of the neck 2 still in one piece so that loose cap fragments do not become a problem. Once the overseal is 10111 off. not only is there assurance against prior opening of the container but in addition the plug and surrounding gasket seat remain din free and uncontaminated. A second embodiment of the present invention is shown in Figs. 6 to S, wherein a shipping container 40 has an upstanding internally threaded neck 41 terminating in a gasket seat 42. An annular gasket retaining bead 42a is formed on the gasket seat 42 which is surrounded by an annular collar 42, circumferentially enlarged at bead 44. A closure plug 45, having a bottom wall 46 and an externally threaded sidewall 473 is screwed into the neck 41. The plug has a circumferentially enlarged head 48 formed with a radially outwardly opening groove 49 therearound. A sealing gasket 50 is retained on the plug immediately beneath the head 48. As seen in Fig. 7 the plug 46 also has a series of axially extending wrench engaging surfaces 51. A closure overseal 52 has a top wall 53 surrounded by a depending skirt 54 necked inwardly at its free edge 55. A segmented collet depends from the central portion of the overseal and is made up of a series of axially elongated segments 56 teaminating at their distal ends in radially inwardly projecting feet 57. As in the first embodiment, the seal 52 is formed with a tear strip 53 separating the segments 56 and having radially outwardly extending tearing ears 58, In this embodiment of the invention, the plug 45 is screwed into the neck 41 so as to compress the gasket 50 over the gasket retaining bead 42a and bring the groove 49 into horizontal alignment with the top of the neck enlargement 44. The tamper evident overseal 52 is then snapped onto the plug causing the segment feet 57 to expand outwardly and then engage within the groove 49 while at the same time and the inturned skirt edge 55 engages beneath the neck bead 44. The overseal 52 is an interference fit on the container neck bead 44. Thus, and as in the first embodiment, the interlocking structure is inaccessible to unauthorized removal and, of course, the tear strip and tearing ears facilitate removal as intended. Various other changes in or modifications of the closure combination of the present are possible; for example the number and spacing of the collet segments could vary. We claim: I A closure plug and tamper evident, closure ovsrseal combination for shipping containers :-the closure plug (6) comprising:- a cylindrical, cap-shaped body having axially-extending. wrench- . engaging lugs (12) about the inner periphery of the plug sidewall (8); and, a segmented, radially and circumferentially extending groove (17) formed in the sidewall (8) thereof; the oversea] (20) comprising:- axially extending, resilient legs (23), each having a radially-extending foot (24) designed for hidden, snap-fit interlocking, engagement with the radial groove (17); and a frangible portion (26) to permit removal of the oversea! from the plug and visible when the closure plug (6) and the oversea! (20) are interlocked; and further characterised in that the closure plug (6) has:- the radial groove formed by a radial undercut (17) at the base of each lug; the overseal (20) has:- leg feet (24) extending radially outwardly to snap-fit under lugs (12) into groove undercuts (17); whereby the overseal will snap-fit with the closure plug irrespective of relative angular position. 2. The combination of claim 1 and further characterised in that the visible frangible portion (26) overlies, at least in part, the snap-fit features (17, 23, 24). 3. The combination of claim 1 or claim 2 and further characterised in that the frangible portion is a diametrically extending tear strip (26) in the overseal top (21). 4 The combination of any of claims 1 to 3 and further characterised in that the lugs (12) are equi-spaced about the inner periphery of the plug sidewall (S) with the space between iues at least as great as the width of the lues. 5. The Combination of any of claims 1 to 4 and further characterised in that a segmented collet comprising a series of axially elongated leg segments (23) depends from a cap top (21); the distal end of each segment has a radially projecting foot (24) with a bottom cam surface (25) designed to radially deflect the leg segment when encountering a radial plug surface (9) as the overseal (20) is fitted into the closure plug (6). 6. The combination of claim 4 or claim 5 and further characterised in that the closure plug (6) has four wrench-engaging lugs (12). 7. The combination of claim 3 and claim 4 and further characterised in that three leg segments (23) depend from one side of the tear strip (26) and three leg segments from the other side of the tear strip. 8. The combination of any of claims 1 to 7 and for a shipping container (1) having a neck (2) and farther characterised in that the overseal top (21) is surrounded by a peripheral, depending skirt (22); which is an interference fit on a given container neck (2). 9. A closure plug for shipping containers and as claimed in any of claims 1, 4 or 6. 10. A tamper evident, closure overseal as claimed in any of claims 1, 2, 3, 4, 7 or 8. 11. A closure overseal as claimed in claim 10 and further characterised in that the overseal (20) is a synthetic plastic resin moulding, 12. A closure plug and tamper evident, closure overseal combination for shipping containers, substantially as herein described and illustrated with reference to the accompanying drawings. Dated, this 6th day of May, 2006. —-

Documents:

1606-CHENP-2006 AMENDED CLAIMS 19-06-2012.pdf

1606-CHENP-2006 AMENDED PAGES OF SPECIFICATION 19-06-2012.pdf

1606-CHENP-2006 CORRESPONDENCE OTHERS 12-06-2012.pdf

1606-chenp-2006 description (complete) 23-06-2008.pdf

1606-CHENP-2006 EXAMINATION REPORT REPLY RECEIVED 19-06-2012.pdf

1606-CHENP-2006 FORM-5 19-06-2012.pdf

1606-CHENP-2006 FORM.3 12-06-2012.pdf

1606-CHENP-2006 OTHER PATENT DOCUMENT 19-06-2012.pdf

1606-CHENP-2006 POWER OF ATTORNEY 19-06-2012.pdf

1606-chenp-2006-abstract.pdf

1606-chenp-2006-claims.pdf

1606-chenp-2006-correspondnece-others.pdf

1606-chenp-2006-description(complete).pdf

1606-chenp-2006-drawings.pdf

1606-chenp-2006-form 1.pdf

1606-chenp-2006-form 26.pdf

1606-chenp-2006-form 3.pdf

1606-chenp-2006-form 5.pdf

1606-chenp-2006-pct.pdf