IE83607B1 - A tamper indicating closure - Google Patents

Description

"A Tamper Indicating Closure" Introduction The present invention relates to a tamper indicating closure and in particular to a tamper indicating closure for a container of the type having a bored cylindrical externally threaded neck portion with an annular clipbead inward of the threaded portion and having a recess behind it, the type surmounting an outer threaded portion connected by an closure being of the comprising a cap inner weakened frangible portion to an inner tamper ring and said tamper ring having an inwardly directed lip for engagement over the clipbead and within the recess.

A particularly well known form of such tamper indicating closure has a frangible portion which comprises a series of short tabs interconnecting the main body portion and of the frangible portion between the Kain body portion and the the tamper ring and in which the remainder tamper ring is cut away to form a series of intermittent slits along the one circumference. this Unfortunately with well known form of closure, it is possible to manipulate the closure by moving it relative to the longitudinal axis of the neck to remove the closure and tamper ring without breaking the tabs thereby negating the tamper evidence. This can be done accidentally let alone deliberately.

Extrusion blow—moulding is the most common method for forming containers and bottles. Unfortunately, extrusion blow—moulding has certain disadvantages which cause problems in trying to provide a reliable tamper indicating closure. Firstly, by it's very nature, extrusion blow- moulding is not done to very tight tolerances and further, there is an inability to form sharp corners or undercuts. commonly available Unfortunately, many closure designs rely quite heavily on the accurate engagement between closure and container.

Further, they require a positive the the example of a tamper European Patent 589254 which will only work with a clipbead having a relatively sharp corner and thus it engagement of tamper ring under clipbead. this is of the closure is Unfortunately, dependent on degree of sharpness clipbead. One indicating described in Specification No. appears that the successful operation of this invention requires that the container be manufactured by the more expensive injection blowing process. Many closures get over some of the problems of having to have an inwardly directed lip on the tamper ring which is relatively substantial as this requires complex moulds by forming the tamper ring by a series of inwardly projecting spaced- apart lugs so as to give sufficient flexibility" to the the European Patent Specification 219946 is an example of this closure when it is being applied to container. construction in that the tamper ring is provided with a plurality of spaced-apart individual lugs in the inner surface to cooperate with the externally projecting clipbead.

UK Patent Specification No. 2295143 endeavours to address this pushed towards the inner tamper ring, the two interengage problent whereby as the outer threaded portion is so as to allow thenx to be screwed onto the container.

This obviously prevents the tabs being sheared but does not prevent bulging or axial movement of the tabs outward by this movement together of the outer threaded portion and the inner tamper ring.

US Patent Specification No. of the addresses the problem force required to apply the closure to the container. Unfortunately it requires a secondary post forming operation. This specification provides, on the tamper ring, another ring or a series of lugs connected to the tamper ring by a hinge so as to further engage under the clipbead. These pivot out of the way on application and then engage beneath the clipbead when the closure is being unscrewed.

A further problem with closures when the frangible portion comprises a series of short tags interconnected i11 the main body portion and the tamper ring is that there is a balance required between making the tabs so weak that they break when the cap is first applied or nmking them so strong that they fail to break on opening. This problem is exacerbated by the weakening effect of the tab when the closure is first applied as the tamper ring experiences resistance on the neck portion of the container as it is This between the outer threaded portion and the tamper ring and thus tends to crush the tab. being placed in position. then closes the gap This bulging or axial movement referred to above is clearly illustrated in US 4550843. The problem with this product Patent Specification No. is that this can cause rejection during the capping process.

It is has been discovered that it is vital to keep the tamper ring at 90° to this longitudinal axis and not to allow it "kick" to one side during removal.

Statements of Invention According to the invention, there is provided a tamper indicating closure for a container of the type having a bored cylindrical externally threaded neck portion with an annular clipbead inward of the threaded portion and having behind it, the of the type comprising a cap surmounting an outer threaded portion a recess closure being connected by a weakened frangible portion. to an inner tamper ring and said tamper ring having an annular surface terminating in an inwardly directed lip for engagement over the clipbead and within the recess, characterised in that the portion of the tamper ring between the inwardly directed lip and the radial force clipbead exerts a inwards on the clipbead with its annular surface against the clipbead. and wherein the weakened frangible portion tabs tamper ring comprises a series of short spaced—apart interconnecting the outer portion and the across an annular gap, the cross—sectional area of the tab decreasing front where it connects to one of the outer portion and the tamper ring to where it connects with the other in which the smallest cross— sectional area of the tab is where it connects to the outer portion. The advantage of the radial inward force on the clipbead is that the tamper ring cannot be kicked sideways or cocked, as it were, when being unscrewed and thus the weakened frangible portion will be broken when the closure is unscrewed, the tamper ring being securely anchored on the container.

The great advantage of having this tapered design as it where, is that it is relatively strong in compression and will thus closure is resist crushing and stress weakening as the still has a sheer and tension, placed in position while it weakened portion which, in breaks easily when the closure is twisted. It also has the great advantage of allowing a clean break between the withdrawn and the suitable where co—operating teeth are used as there is no portion tamper ring. This is particularly interference with said teeth when the closure is re- applied.

The advantage of the smallest cross-sectional area of the tab being where it connects to the outer portion is that the failure occurs on the withdrawn portion of the closure and thus there is no jagged edge to cause the user any discomfort or injury. It is very desirable that what is, in effect, the whole of the closure as far as the consumer or user is concerned is cosmetically clean and free from projecting tab remnants.

Ideally, the bore of the closure and a front semi—circular wall in the tab has a back wall forming an extension of cross-section. This is particularly advantageous as it allows for a number of small tabs to be provided using only simple side cores in a mould when formed by injection moulding.

Additionally, one of the outer portion and the tamper ring and project support lugs are provided connected to only into the annular gap. Again, this advantageously limits the crushing effect on the tab by weakening the tab as the outer portion and the tamper ring are forced together on added support and resist the tendency of the tabs to bulge application of the closure. The lugs provide outwards.

Preferably, the support lugs are connected to the tamper ring. Again, this leads to a smooth underneath part for the withdrawn portion of the closure.

In one embodiment of the invention, there are cooperating teeth between the outer portion and the tamper ring, which, when the closure is rotated in a closing direction, will engage to prevent the tabs breaking and, when rotated in the opposite direction, allow the tabs to break and wherein the spacing between. the outermost portion of a tooth and the opposite portion of the closure is less than the depth of the rest of the annular gap. This cooperates in, what is a well known way of voiding sheer of the tabs, the advantage of the hereinbefore support lugs as described.

In one embodiment of the invention, the bore diameter is .5% of the outer diameter with a tolerance i 0.85%. _6...

Since one is using plastics materials, this is one of the easiest ways of providing this inward force. This is efficient for securing the tamper ring in position in that the tamper ring is not alone a force fit on the clipbead but also is in a position whereby any attempt to unscrew the closure will almost certainly break the frangible portion. Preferably the tolerance is r 0.6%.

Ideally the inwardly directed lip forms a continuous ring.

This relatively robust closure. strengthens the tamper ring and provides a Preferably, the threaded portion is a tight fit on the neck portion. This again ensures that on unscrewing of the closure, the tamper ring cannot kick or pivot away from the neck of the closure. However, in many instances this is not possible in manufacture because of the need to provide the wide tolerances to allow the tamper rings to with the are well protected, it is slip over the clipbeads. the tabs However, because, present invention, possible to provide tighter tolerances for the threads.

In one embodiment of the invention, the closure is so dimensioned that the distance between the interior of the cap and the inwardly directed lip is just sufficient to allow the lip to engage over the clipbead to lie within the recess. All this does is further assist in ensuring that there is no play between. the tamper ring and the outer threaded portion of the closure to allow any relative movement therebetween. In conventional closures particularly with those that have relatively large clipbeads, there would not be sufficient clearance to allow application of the closure. Further, the invention provides the use of any of these closures in combination with a container which is manufactured from an extrusion A great advantage of blow-moulded plastics material. using extrusion. blow-moulding for the container‘ is it's relative cheapness.

Detailed Description of the Invention The invention will be more clearly understood from: the following description of an embodiment thereof given by way of example only’ with reference to the accompanying drawings in which:— Fig. l is an exploded side View of a closure according to the invention about to be screwed on to the neck portion of a container; Fig. 2 is a part sectional View of the closure on a container being screwed down onto the neck of the container; Fig. 3 is a view similar to Fig. 2 showing the closure fully screwed down onto the neck of the container; Fig. is a View similar to Figs. 2 and 3 showing the closure being removed from the container; Fig. is a View similar to Fig. 1 showing the closure totally removed from the container; Fig. 6 is an enlarged View of portion of Fig. 1; Fig. 7 is a sectional View in the direction. of the arrows VII—VII of Fig. 6; Fig. 8 is a sectional view in the direction of the arrows VIII—VIII of Fig. 6; Fig. 9 is a View similar to Fig. l of an alternative construction of closure according to the invention; Fig. 10 is an enlarged detail of the circled portion indicated by the reference letter W in Fig. 9; Fig. 11 is another detailed View of the portion circled in Fig. 9 and indicated by the reference letter W; Fig. 12 is a sectional view showing the closure of Fig. 9 partially screwed onto the neck of a container; Fig. 13 is an enlarged view of the portion circled in Fig. 9 and identified by the reference letter Q; Fig. 14 is a cross—sectional View in the direction of the arrows XIV—XIV of Fig. 13; Fig. 15 is a cross-sectional view in the direction of the arrows XV—XV of Fig. 13; Fig. 16 is an enlarged View of portion of an alternative construction of closure according’ to the invention; and Fig. 17 is an enlarged View again showing portion of a still further according to the invention. alternative construction of closure Referring to the drawings and initially to Figs. 1 to 8 thereof there is provided. a tamper indicating closure indicated generally by the reference numeral 1 for a container, not shown, having a bored cylindrical outwardly threaded neck portion indicated by the reference numeral 2. The tamper indicating closure 1 has an outer portion 3 terminating in a cap 4 and having internal threads 5 and is connected by a weakened frangible annular portion indicated by the reference numeral 6 to a tamper ring 7.

The frangible portion 6 is formed by a series of alternate slits forming an annular gap 8 and tabs 9. The tamper ring 7 has an annular surface 15 and an inwardly directed lip 10. threads clipbead 12 through a radiused lead in surface 13.

The neck portion 2 has 11 connecting with a Behind the clipbead 12 is a recess 14 for reception of the lip 10 as will be described hereinafter. The internal bore of the tamper ring 7 is less than the external diameter of the clipbead 12 and the threads 5 and 11 are a close fit on each other. Further, the closure 1 is so dimensioned that the distance between the outermost internal neck bore closing portion of the cap 4 and the inwardly directed lip is just sufficient to allow the lip 10 to engage over the clipbead 12 to lie within the dimension X as indicated in Fig. recess 14. The 3 is thus kept to a minimum.but is not critical.

It will be noted from Figs. 6 to 8 that the tabs 9 do not project across the whole of the depth of the gap 8 and are further thinner adjacent the outer portion 3 than the tamper ring 7 having a reducing cross—sectiona1 area from It will be noted that each tab 9 has a back wall forming an extension of the bore of the closure top to bottom. and a front semi-circular wall in cross section.

In use, the closure 1 is screwed onto the neck portion 2 in the normal manner until the lip 10 begins to engage the radiused lead in surface 13 and is pushed. up over the clipbead 12. it slips behind the clipbead 12 into the recess 14 as As the lip 10 is forced over the clipbead 12 shown in Fig. 3. Then the tamper ring 7 engages tight against the clipbead 12 because the internal bore of the tamper ring 7 is less than the external diameter of the clipbead 12 thus forming an interference fit thereon and exerts a positive radial force inwards. When the closure is unscrewed from the neck portion 2 the annular surface of the tamper ring 7 is held tight against the clipbead 12 because of this positive radial inwards force and the frangible portion 6 breaks easily.

It will be noted from Fig. 5 that because the tabs 9 are thinner adjacent the outer portion 3, they fracture where they meet the outer portion 3 and thus, the tabs 9 remain attached to the tamper ring 7. Further, the tapered It is relatively strong in compression resisting crushing and design produces a number‘ of beneficial effects. strength weakening, while at the same time, a clearly It is sheer and tension and it would break it will afford a clean break leaving the main body of the closure as it defined line of fracture is identified as it where. further weak in easily at it's weakest point. Further, where, i.e. the parts that people withdraw, having a cosmetically clean underneath surface which is free from projecting tab or tab remnants. the tab, The particular shape of what one would almost say was a conical design, allows a number of small tabs to be provided using only simple cores in a mould. It also ensures that the outer edge of the whole of the removed portion of the closure is relatively smooth. to 15 alternative Referring now to Figs. inclusive there is illustrated an construction of tamper indicating closure indicated. generally by the reference numeral 20. In these drawings, parts similar to those described with reference to the previous identified by the embodiment there is provided a frangible portion indicated drawings are same reference numerals. In this generally by the reference numeral 21. The frangible tabs 22 and the There is provided slits interconnecting portion 21 comprises a plurality of interconnecting the outer threaded portion 3 tamper ring 7. each tab 22 which form an annular gap 23, the slits are extended to project in a generally longitudinal direction -11.. with respect to the closure longitudinal axis and the remainder of the slit is inclined. to the axis to form cooperating teeth identified by the reference numerals 24 and 25 on the outer portion 3 of the closure 20 and tamper It will be noted that the spacing between the outermost portion of the tooth 25 and the ring ’7 respectively. opposite part of the outer portion 3 is less than the rest of the annular gap 23.

Fig. 10 shows the teeth 24 and 25 in the normal position when the closure 20 is in the position illustrated in Fig. 9. As portion 2 because of the fact that the lip 10 will begin the closure 20 is screwed. down onto the neck to bear against the radiused lead in surface 13, a certain pressure will be put onto the frangible portion 21. If the tabs 22 will begin to distort and the outer portion 3 will the pressure is sufficient, rotate somewhat relative to the tamper ring 7 until the teeth 24 and 25 engage. Further, the gap identified by the letter A will be quickly closed so that the tabs 22 further protect it from crushing. It will be appreciated that if the closure is unscrewed from the neck portion 2 that the closure will operate in the same way as the closure 1 and the tamper ring 7 will be fast on the clipbead 12 and the teeth 24 and 25 will smoothly disengage causing the tabs 22 to break as before.

It will be noted from Figs. 13 to 15, that the construction of tab 22 is different to that of the tab 9 of the previous embodiment in that the thinnest portion and thus the weakest portion of the tab 22 lies adjacent the tamper ring 7. the tabs portion 3 and not left on the tamper ring 7 as with the Thus when the frangible portion 21 is broken, 22 will be withdrawn with the outer previous embodiment. -12..

It will be appreciated that this embodiment in which the weakened frangible portion is so shaped that on a closing rotation of the closure, the frangible portion distorts to allow the outer threaded portion locate the tamper ring before the frangible portion breaks to rotate together and an opening rotation to disengage to permit the frangible portion to break is not required for every application but merely for those closing operations or machines where the closing torque is relatively severe.

Referring now to Fig. 16, there is illustrated portion of an alternative construction of closure indicated generally by the reference numeral 30 which is of substantially the same construction as that closure illustrated in Figs. 1 to 8. In this embodiment, there are provided support lugs 31 on the outer portion of in addition to the tabs 9, the tamper ring 7 which project into the annular gap 8.

On closing of the closure, as the tamper ring" 7 meets resistance on the externally threaded neck portion of the container, the gap 8 will be reduced and the tabs 9 will begin to distort. with the crushing or bulging of the tabs 9.

However, the support lugs 31 will now engage outer portion 3 preventing further It will be appreciated that the support lugs could be also placed on the outer portion 3 or there could be some support lugs on both the outer portion 3 and the tamper ring 7.

Referring to Fig. 17, there is illustrated portion of an alternative construction of closure, indicated. generally by the reference numeral 40 which is substantially similar in construction to the closure described with reference to Figs. 9 to 15 inclusive. In this embodiment, there are provided tabs 41 in which the smallest cross—sectional area of the tabs is where it connects with the outer portion 3. In this embodiment, there is provided a series of recesses 42 in the outer portion 3 and projecting teeth on the tamper ring 7. It will be noted that the -13.. spacing between the outermost portion of the teeth 43 and the interior of the recess 42 as identified by the letter B is less than the depth of the rest of the annular gap 23.

It has tolerances for the closure and specifically the bore or been found in practice that the manufacturing internal diameter 1D of the tamper ring 7 is critical.

For example, with a relatively common size of container neck with a nominal bead outside diameter OD of the order of 30 mm the 1D of the tamper ring varies between 29.8 to .3 mm i.e. i 0.25 mm about a nominal 1D of 29.55.

In general a nominal 1D for the tamper ring expressed in terms of the nominal OD of the bead is of the order of 0.985 bead OD i 0.0060 bead OD to i 0.0085 bead OD or expressed as a percentage 98.5% i 0.6% or i 0.85%.

The present invention is particularly suitable for use with containers formed by extrusion blow—moulding. The closure according to the present invention is injection moulded and will accommodate a wide range of container neck sizes and eliminates the need for very sharp undercut corner radiuses on the neck clipbead. This makes the mould easier to manufacture and the cap can be easily ejected from the mould unlike some current constructions.

It will be noted that the present invention utilises a continuously inwardly projecting tamper ring with a relatively small undercut and critically is dimensioned so that. the internal diameter of the vertical face of the tamper ring must be considerably stretched over the clipbead so that, even after application, a significant inward radial force is exerted. One of the great advantages of a small undercut on the tamper ring is that it eases the application of a cap on a bottling line.

Utilisation of the natural lasting effect of the material of the tamper ring, this enables a wide range of neck _ 14 - It should also be as it where, clipbead tolerances to be accommodated. noted that the stretch fit, of the tamper ring limits rotation sufficiently to aid breaking of tab on first removal of cap and in many instances, does not of the teeth for ratchet arrangement as described herein, although in certain other require the use elaborate situations, this may be useful. Further, it will be seen how the present invention has ensured that the tabs are relatively strong in compression and weak in sheer so that they will easily break when a cap is twisted while, under compression, they resist crushing and bulging which, if inwards, can further increase the torsional force required for application. Similarly, what is in effect a small upstand or downstand provided. by the support lugs, is advantageous in further limiting the crushing effect or tab weakening as described before. It will be appreciated that this feature may be used in conjunction with all the embodiments.

It is envisaged that the closure will be made of any suitable elastic or deformable material and that indeed and high used in the the common plastics such as polypropylene (PP) (HDPE) construction of such closures are very suitable. density polyethylene that are limited to the embodiments described which may be varied within the The invention is not hereinbefore scope of the claims.

Claims (1)

1. A tamper indicating closure for a container of the type having a bored cylindrical externally threaded neck portion with an annular clipbead inward of the threaded portion and having a recess behind it, the type surmounting an outer threaded portion connected by a closure being of the comprising a cap weakened frangible portion to an inner tamper ring and said tamper ring having an annular surface terminating in an inwardly directed lip for engagement over the clipbead and within the recess, characterised in that the portion of the tamper ring between the inwardly directed lip and the clipbead exerts a radial force inwards on the clipbead with its annular surface against the clipbead, and wherein the weakened frangible portion comprises a series of short spaced-apart tabs interconnecting the outer portion and the tamper ring across an annular gap, the cross—sectional area of the tab decreasing from where it connects to one of the outer portion and the tamper ring to where it connects with the other, in which the smallest cross—sectional area of the tab is where it connects to the outer portion. A closure as claimed in claim 1, in which the tab has a back wall forming an extension of the bore of the semi—circular wall in cross- closure and a front section. A closure as claimed in either claim 1 or 2, in which support lugs are provided connected to only one of the outer portion. and. the tamper ring and. project into the annular gap. A closure as claimed in claim 3 in which the support lugs are connected to the tamper ring. A closure as claimed in any preceding claim in which there are co-operating teeth between the outer portion and the tamper ring, which, when the closure is rotated in a closing direction, will engage to prevent the tabs breaking and, when rotated in the allow the tabs wherein the spacing between the outermost portion of opposite direction, to break and a tooth and the opposite portion of the closure is less than the depth of the rest of the annular gap. A closure as claimed in any preceding claim in which the bore internal diameter is 98.5% of the outer diameter of the clipbead with a tolerance i 0.85%. in claim 6 in which the A closure as claimed tolerance is i 0.6%. A closure as claimed in any preceding claim, in which the inwardly directed lip forms a continuous ring. A closure as claimed in any preceding claim in which the threaded portion is a tight fit on the neck portion. A closure as claimed in any preceding claim, in which the closure is so dimensioned that the distance between the interior of the cap and the inwardly directed lip is just sufficient to allow the lip to engage over the clipbead to lie within the recess. A closure as claimed in any preceding claim in combination with a container which is manufactured from.an extrusion blow—moulded plastics material. A closure described herein with 1 to 9 of substantially as reference to and as illustrated in