TAMPER-EVIDENT RING ASSEMBLIES

Abstract

A tamper-evident, single use, ring assembly, is assembled from first and second interengaging broken rings (1, 2). The first broken ring (1) is of a first material and the second broken ring (2) is of a second material. A break in the ring of the first material is offset circumferentially from a break in the ring of the second material. The assembly of the rings forms a closed ring assembly which can be cut through in the region of the break in the ring of the first material to open the ring assembly. At least one of the rings (1, 2) of the ring assembly is resiliently stressed in its assembled state such that, upon cutting through of the ring assembly, the confronting ends of the assembly move apart.

Claims

1. A tamper-evident, single use, ring assembly, assembled from first and second interengaging broken rings, the first broken ring being of a first material and the second broken ring being of a second material, a break in the ring of the first material being offset circumferentially from a break in the ring of the second material, whereby the assembly of the rings forms a closed ring assembly which can be cut through in the region of the break in the ring of the first material to open the ring assembly, at least one of the rings of the ring assembly being resiliently stressed in its assembled state such that, upon cutting through of the ring assembly, the confronting ends of the assembly move apart.

2. A ring assembly according to claim 1, in which the first material is metal and the second material is a plastics material.

3. A ring assembly according to claim 1, in which the first ring is resiliently stressed in its assembled state.

4. A ring assembly according to claim 1, in which said at least one of the rings of the ring assembly is resiliently stressed in its assembled state such that, upon cutting through of the ring assembly, the confronting ends of the assembly move apart in a direction with a major component perpendicular to the plane of the ring.

5. A ring assembly according to claim 1, in which the first ring defines a circumferential recess in which the second ring is at least partly received and the first ring is of approximately C shaped cross-section.

6. A ring assembly according to claim 5, in which the first ring has projections extending inwardly into the interior of the C cross-section and the second ring has corresponding formations on its exterior for engaging the projections to retain the second ring secured to the metal ring.

7. A ring assembly according to claim 5, in which the second ring is of generally constant cross section but has a different cross-section in the region of the break in the first ring.

8. A ring assembly according to claim 1, in which the second ring and the first ring can be snap-fitted together.

9. A ring assembly according to claim 1, in which the second ring is disposed around the outside of the first ring.

10. A ring assembly according to claim 1, in which the second ring and the first ring have interengaging formations for preventing relative rotation of the rings.

11. A ring assembly according to claim 1, in which, at the break in the first ring, the ends of the first ring are spaced apart from one another by a distance of more than 1.5 mm.

12. A ring assembly according to claim 1, in which, at the break in the second ring, the ends of the ring are adjacent to one another and/or overlap one another.

13. A ring assembly according to claim 1, further comprising one or more items through which the ring assembly passes to retain the one or more items on the ring assembly.

14. A ring assembly according to claim 13, in which the one or more items comprise one or more keys and/or one or more fobs.

15. A ring pre-assembly for making a tamper-evident, single use, ring assembly according to claim 1, the ring pre-assembly comprising first and second interengaging broken rings, the first broken ring being of a first material and the second broken ring being of a second material, a break in the ring of the first material being offset circumferentially from a break in the ring of the second material, the pre-assembly of the rings forming an open ring one end of which is defined by an end portion of the first ring and the opposite end of which is defined by an end portion of the second ring, the end portions being interengageable to form the tamper-evident, single use, ring assembly according to claim 1.

16. A method of making a tamper-evident, single use, ring assembly, the method comprising the following steps: providing a ring pre-assembly comprising first and second interengaging broken rings, the first broken ring being of a first material and the second broken ring being of a second material, a break in the ring of the first material being offset circumferentially from a break in the ring of the second material, the pre-assembly of the rings forming an open ring one end of which is defined by an end portion of the first ring and the opposite end of which is defined by an end portion of the second ring, and ii. interengaging the end portions to form a closed ring assembly which can be cut through in the region of the break in the first ring to open the ring assembly, at least one of the rings of the ring assembly being resiliently stressed in its assembled state such that, upon cutting through of the ring assembly, the confronting ends of the assembly move apart.

17. A method according to claim 16, further including the step of passing one of the end portions of the ring pre-assembly through one or more objects before carrying out the step of interengaging the end portions.

18. A method according to claim 16, further comprising the subsequent step of cutting through the second ring in the region of the break in the first ring, the confronting ends of the assembly then moving apart to define an open ring assembly.

19. A method according to claim 16, in which the ring assembly formed is a tamper-evident, single use, ring assembly, assembled from first and second interengaging broken rings, the first broken ring being of a first material and the second broken ring being of a second material, a break in the ring of the first material being offset circumferentially from a break in the ring of the second material, whereby the assembly of the rings forms a closed ring assembly which can be cut through in the region of the break in the ring of the first material to open the ring assembly, at least one of the rings of the ring assembly being resiliently stressed in its assembled state such that, upon cutting through of the ring assembly, the confronting ends of the assembly move apart.

Description

[0031] By way of example an embodiment of the invention will now be described with reference to the accompanying schematic drawings, of which:

[0032] FIG. 1 is an isometric view of an open ring pre-assembly embodying the invention;

[0033] FIG. 2 is an isometric view of a closed ring assembly made from the pre-assembly of FIG. 1;

[0034] FIG. 3 is an isometric view of a metal ring forming part of the assembly of FIG. 2;

[0035] FIG. 4A is a sectional view of the metal ring;

[0036] FIG. 4B is an enlarged view of part of FIG. 4A;

[0037] FIG. 5 is a plan view of a ring of plastics material forming part of the assembly of FIG. 2;

[0038] FIG. 6A is a sectional view along the lines VI-VI of FIG. 5;

[0039] FIG. 6B is an enlarged view of part of FIG. 6A;

[0040] FIG. 7 is an isometric view of a modified form of the ring shown in FIGS. 5 to 6B, and

[0041] FIG. 8 is a schematic isometric view of part of a modified form of the assembly of FIG. 2, illustrating a modification that may be made to the assembly.

[0042] The tamper-evident, single use, ring assembly is shown in a pre-assembly, open, condition in FIG. 1 and in a fully assembled and closed condition in FIG. 2.

[0043] The ring assembly and the pre-assembly comprise a first ring 1 of metal, in this particular example stainless steel, and a second ring 2 of plastics material, in this particular example nylon. The ring 1 is shown in FIGS. 3 to 4B and the ring 2 is shown in FIGS. 5 to 6B.

[0044] Referring first to FIGS. 3 to 4B, the steel ring 1 is in the general shape of a circular ring, and is formed from steel plate. The cross-section of the ring is C shaped with an open channel 3 defined around the ring and facing outwards. There is a break in the ring which results in a gap 4 defined between opposite ends 5 and 6 of the ring; in one particular example of the invention the gap 4 has a width of 1.75 mm. Although the ring is shown in FIGS. 3 to 4B as lying in a single plane and that is the arrangement it is held in when the ring assembly is complete and closed, as shown in FIG. 2, the natural unstressed state of the ring is approximately that shown in FIG. 1; in this state the ring is slightly twisted with the ends 5 and 6 offset from one another in a direction parallel to the axis around which the ring extends and approximately perpendicular to the general plane in which the ring lies.

[0045] The open channel 3 in the ring has opposite sides 3a and 3b on which inwardly projecting lancings 7 are formed at intervals around the ring. The lancings 7 are formed by pressing partly cut-away portions of the sides 3a and 3b into the channel. In the particular example shown, there are seven pairs of lancings 7, each pair comprising a lancing on each opposite side 3a and 3b. FIGS. 4A and 4B are sectional views through a pair of lancings 7 and show the profiles of the inwardly projecting lancings. FIG. 4B is an enlarged view of the portion of FIG. 4A marked by the circle 8 and shows the profiles of the lancings 7 to a larger scale.

[0046] Also, visible in FIGS. 3 and 4A is a further lancing 9 in a bottom wall 3c of the channel 3. The lancing 9 is similarly formed by pressing a partly cut-away portion of the bottom wall 3c into the channel 3. In the particular example shown there are two diametrically opposite lancings 9 but the second lancing 9 is not visible in the drawings.

[0047] Referring now to FIGS. 5 to 6B, the nylon ring 2 is similarly in the general shape of a circular ring, and is dimensioned to fit in the channel 3 of the steel ring 1. There is a break in the ring 2 which results in a gap 11 defined between opposite ends 12 and 13 of the ring; in one particular example of the invention the gap 11 has a width of 2.0 mm.

[0048] The ring 2 is of constant cross-section around almost all of its circumference, that cross-section being most clearly seen in FIG. 6B which is an enlarged view of the portion of FIG. 6A marked by the circle 14. It can be seen that the ring is formed with triangular cross-section grooves 15a and 15b in its opposite sides, the cross-section of those grooves being matched to the profiles of the lancings 7.

[0049] At one position around the ring 2, shown near the bottom of FIG. 5, the ring cross section is enlarged and the grooves 15a and 15b interrupted. That enlarged portion is referenced 16 in FIG. 5 and in that region, which in this particular example has a width of 1.75 mm, the exterior cross-section of the nylon ring 2 is matched to the exterior cross-section of the steel ring 1.

[0050] Referring now also to FIG. 1, the ring assembly shown in FIG. 1 is in the form in which it is supplied as a pre-assembly to a user. It should be understood that FIG. 1 is a schematic view that does not show all the details of the design: in particular, the slight narrowing of the ring 2 from the enlarged portion 16 to the end 12 of the ring is not shown. In the form of the ring assembly shown in FIG. 1, the nylon ring 2 has been pressed into the steel ring 1 in which it is a snap fit, with the gaps 4 and 11 in the rings circumferentially offset from one another so that the end 12 of the nylon ring 2 projects circumferentially from the steel ring 1 and the end 6 of the steel ring projects circumferentially in the opposite direction from the nylon ring 2. In this position, five pairs of the lancings 7 engage in the grooves 15a and 15b in the nylon ring 2 and the lancings 9 dig into the inner circumference of the nylon ring.

[0051] Owing to the slightly twisted unstressed shape of the steel ring 2, the ends of the ring are offset from one another, making it easy to pass one end of the ring pre-assembly through one or more objects, for example one or more keys or fobs or other small objects, to which the ring assembly is to be attached as a security seal device. Once the ring has been passed through the one or more objects, the remaining part of the nylon ring 2 is pressed into the remaining adjacent part of the steel ring 1 to form the completed ring assembly shown in FIG. 2.

[0052] The steel ring is resilient and deforms to allow the inner part of the nylon ring 2 to pass the seven pairs of lancings 7 and retain the nylon ring 2 in the steel ring 1. The profile of the lancings 7 and the grooves 15a and 15b is such that they resist subsequent withdrawal of the nylon ring 2. The enlarged portion 16 of the nylon ring 2 is accommodated in the gap 4 in the steel ring 1 and thus results in the ring assembly having a continuous constant exterior cross section. The enlarged portion 16 also combines with the lancings 9 to prevent rotation of the rings 1 and 2 relative to one another.

[0053] If it is desired to separate the ring from the object(s) to which it is fixed, then the enlarged portion 16 of the nylon ring 2 can be cut, for example with a knife. Once cut, the internal stress in the steel ring 1 causes it to return to the approximately helical shape shown in FIG. 1. That provides a clear visual indication that the ring assembly has been cut.

[0054] The arrangement described above provides a very low-cost tamper evident ring seal that may be used in a variety of applications. The size of the ring assembly may be selected according to the application. In the particular example described above the diameter of the assembly is about 30 mm.

[0055] Whilst one particular embodiment of the invention has been described with reference to the accompanying drawings, many variations to that embodiment may be made within the scope of the invention. For example, FIG. 7 shows a modified form of nylon ring 2 that may be employed. In this case the profile of the ring shown in FIG. 6B is not continuous but is provided in seven distinct regions to define seven recesses 20 on each side of the ring 2, each recess being arranged to receive a respective lancing 7, which may in turn be dimensioned to extend along almost the entire length of the recess. An arrangement of this kind gives more resistance to rotation of one ring relative to the other and, if desired, the lancings 9 may be omitted.

[0056] FIG. 8 illustrates another modification that may be made to the ends of a nylon ring 2: instead of the ends facing each other on a plane perpendicular to the circumference of the ring, they may overlap with interengaging formations. In FIG. 8 overlapping ends 12 and 13 of a generally S shape are shown and it will be understood that, when those ends are housed in the channel of the steel ring 1, an especially secure joint is formed. Of course, alternative shapes, such as a Z shape could be employed instead.

[0057] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims.