GB2376209A

GB2376209A - Security marking of bolt seals

Info

Publication number: GB2376209A
Application number: GB0113974A
Authority: GB
Inventors: David Murrison; Peter Hodges
Original assignee: ACME SEALS Ltd
Current assignee: ACME SEALS Ltd
Priority date: 2001-06-08
Filing date: 2001-06-08
Publication date: 2002-12-11
Also published as: GB0113974D0

Abstract

A method of marking an article comprises securing to the article a cover having a transparent region overlying the part of the article that is to bear the marking, and marking the article subsequent to the application of the cover by means of a laser beam that is passed through the transparent region of the cover. The article may be a security bolt seal comprising a pin 12 and a bush 14 having a transparent cover 16. Marking 22 on bush 14 is applied by laser through the cover 16. The cover 16 may be marked by the laser at the same time as the bush 14.

Description

SECURITY MARKING The present invention relates to the application of security markings to articles so that their source may be verified.

Security bolt seals are passed through a hasp or aligned eyelets and are used in the same manner as padlocks to ensure that containers are not opened during transit.

Such security bolt seals comprise a pin that can be engaged in a bush or barrel. Once proper engagement has taken place, then the pin cannot be separated from the bush and one has to cut through the pin, typically by using an angle grinder or bolt cutter, to open the container. The bolt seal therefore acts not only as a security seal but also as an indicative seal in that the container cannot be opened without the pin or the bush being visibly damaged.

The stem of the pin and the bush both carry security markings which are recorded on documentation that accompanies the container. Should the bolt seal and bush markings not match each other or should they not match the accompanying documentation, then it can easily be ascertained that someone has tampered with the container. As the container cannot be opened while the bolt seal remains intact, agreement between the markings should also be a guarantee that the container has not been opened during transit.

Bolt seals are but one example of an article that carries a security marking, where it is important to ensure it is not possible to tamper with the marking itself. If, for example, one could change the markings on a bolt seal, then a seal could be removed and replaced by one carrying markings that match the original seal, giving the impression that the container had not been opened.

It has already been proposed to place a transparent protective covering over an identification marking to prevent it from being defaced. For example, it has been proposed to surround the bush of a bolt seal with a transparent sleeve that serves two functions. The first function is that it prevents the bush from being gripped directly, this being effective in preventing one known technique that can be attempted to separate the pin from the bush. The second is that it covers the marking on the bush and prevents it from being defaced. In the prior art, this complicated the manufacture of bolt seals in that the transparent bush had to be secured to the bush after it had been marked.

With a view to mitigating the foregoing disadvantage, the present invention provides a method of marking an article which comprises securing to the article a cover having a transparent region overlying the part of the article that is to bear the marking, and marking the article subsequent to the application of the cover by means of a laser beam that is passed through the transparent region of the cover.

If the transparent region of the cover is of glass, then the laser beam may pass through it without it being marked. It is however preferred to use a material that is itself marked at the same time as a marking is applied to the surface of the article. This offers double security in that in changing the marking on an article it would be necessary to change the corresponding marking on the cover and ensure that the two markings could be superposed without leaving evidence of tampering with either marking. In the case of the cover, this is particularly difficult because the original marking on the transparent region of the cover is not a surface marking but passes through the entire thickness of the material.

The invention has particular application to the manufacture of bolt seals but it will be clear that the same technique could be used to apply security markings to other articles, for example the serial numbers used to identify vehicles and expensive equipment.

In accordance with a second aspect of the invention, there is provided an article having an identification marking and a protective cover secured to the article and having a transparent region overlying the marking, wherein the marking is formed after the cover has been secured to the article by passing a laser beam through the transparent cover.

Preferably, the transparent region of the cover is formed of a material that is marked by the laser light used to apply the marking to the article, whereby the transparent region of the cover bears a marking identical with and in register with the marking on the article.

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of a bolt seal of the invention prior to engagement of the pin in the bush, Figure 2 is a similar view to that of Figure 1 showing the pin engaged in the bush, and Figure 3 is a similar view to Figure 2 with the transparent plastics sleeve surrounding the bush rotated into a different position.

The mechanism of the bolt seal shown in the drawings is generally conventional and need not be described in great detail within the present context, more particularly since a bolt seal is given only as an example of an article that carries security markings.

The illustrated bolt seal comprises a pin 12 and a bush 14. The pin 12 has a metal shank 12a surrounded by a plastics coating 12b that carries a first marking 20. the marking 20 may be applied in any of a variety of ways, including foil blocking, silk screen printing and laser marking. The end of the metal shank 12a has a taper 12c tapered and beyond the taper there is formed a groove 12d.

The bush 14 comprises a metal block 14a formed with a bore 14b dimensioned to receive the shank 12a with a close fit. An annular groove 14c is formed within the bore 14b and has positioned within it a resilient split ring 14d. When the pin 12 is pushed into the bush 14, the tapered end of the shank opens the split ring 14d and when the grooves 12d and 14c are aligned with one another the split ring close by virtue of its own resilience and prevents withdrawal of the pin 12 from the bush 14.

The bush 14 is surrounded by a sleeve 16 made of transparent plastics material. The sleeve 16 can freely rotate about the bush 14 and it cannot be gripped sufficiently tightly to prevent rotation of the bush 14 without being damaged and showing telltale marks.

As shown in Figure 2, the bush 14 also carries a marking 22 which matches the marking 20 on the pin 12. In the present invention, this marking is made after the sleeve 16 has been placed over the bush by illuminating the surface of the bush 14 with a laser beam that passes through the sleeve 16. Manufacture in this manner enables blank bolt seals to be marked after they have been fully assembled avoid the need to interrupt assembly for the marking of the bushes.

It is preferred that the plastics material of the sleeve 16 be marked during the laser marking of the bush so that, as shown in Figure 2, identical markings 22a and 22b

are formed on the bush 14 and the sleeve 16, respectively, that can be aligned perfectly when then sleeve 16 is rotated to be in correct register with the bush 14. As the sleeve is marked throughout its entire thickness, it is difficult to tamper with the markings so that neither the bush 14 nor the sleeve 16 shows any sign of interference and yet the markings 22a and 22b can be fully aligned with one another by rotating the sleeve about the bush.

It is preferred that the surface of the bush 14 be treated in a manner to facilitate laser marking, for example by the application of a coating or additive of a suitable material, such as an absorbent paint.

Claims

CLAIMS 1. A method of marking an article which comprises securing to the article a cover having a transparent region overlying the part of the article that is to bear the marking, and marking the article subsequent to the application of the cover by means of a laser beam that is passed through the transparent region of the cover.
2. A method as claimed in claim 1, wherein the transparent region of the cover is formed of a material that is itself marked at the same time as a marking is applied to the surface of the article.
3. An article having an identification marking and a protective cover secured to the article and having a transparent region overlying the marking, wherein the marking is formed after the cover has been secured to the article by passing a laser beam through the transparent cover.
4. An article as claimed in claim 4, wherein the transparent region of the cover is formed of a material that is marked by the laser light used to apply the marking to the article, whereby the transparent region of the cover bears a marking identical with and in register with the marking on the article.
5. An article as claimed in claim 4, wherein the article is a bolt seal formed of a pin and a bush and wherein the cover of constituted by a transparent sleeve surrounding the bush.
6. A bolt seal as claimed in claim 5, wherein the transparent sleeve is rotatable relative to the bush.

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7. A bolt seal constructed and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawings.