GB2320242A - Silicone rubber seal - Google Patents

Abstract

A silicone rubber seal or washer 20, for use primarily in tamper proof bottle closures, has at least one projection 24 on its inner surface 22, i.e. its bore, preferably extending at least 0.1mm towards the centre of the washer 20. The presence of these projections 24 reduces the tolerance to which the washer bore must be made. Also disclosed is a second type of silicone rubber washer 30, also for use primarily in tamper proof bottle closures, having at least one projection 34 on one, and preferably both of its flat faces 32. These projections 34 reduce friction between the washer 30 and any feeder transport means on which the washer 30 is moved. A method of making both types of washer 20 and 30, involving extruding a cylinder of rubber and subsequently slicing into individual washers 20 and 30 is also disclosed.

Description

WASHER The present invention relates to a washer and in particular to a silicone rubber washer.

One use for a silicone rubber washer is as a sealing washer in a closure assembly e.g. for a bottle.

In particular, such a closure assembly may be used in a tamper proof lid of e.g. a whiskey bottle. Typically, the design the closure assembly and the washer is such that the inside diameter of the washer needs to be very precise i.e. kept within a tight tolerance band (typically 18.40mm to 18.75mm), in order to ensure a friction fit of the washer over a particular fitting in the closure assembly.

In order to manufacture silicone rubber washers to within such a tight tolerance band, the practice has been to injection mould an elongate bar (or "stick") of silicone rubber and then to cut or part the stick into individual washers. With this process, the ends of the stick have to be scrapped since the injection moulding process leaves grease and scorch contamination on them.

One aim of the present invention is to provide a washer which mitigates the above need for such tight tolerances in production.

Accordingly, in a first aspect, the present invention provides a silicone rubber washer on the inside surface of which is at least one projection.

Preferably, the washer is a solid cylindrical washer and preferably the at least one projection is inwardly directed e.g. pointing towards the centre of the washer. By "inside surface" is meant the exterior surface of the bore of the washer.

Preferably, there are a plurality of projections and more preferably there are at least three projections. In some embodiments there may be 4, 5, 6, 7 or possibly even more projections. Preferably, the projections extend at least 0.lmm away from the inside wall of the washer, and possibly even 0.2 mm or more.

With such a washer according to the present invention, the inclusion of a surface undulation or projection on the inside bore reduces the need for such a tight tolerance on the diameter of the inside bore itself. When the washer is mounted over the closure assembly fitting, it is the protrusion or protrusions which provide the friction fit on the fitting. With a washer according to the present invention, manufacture to a tolerance of within + 0.4mm is typically acceptable.

As washers according to the present invention may be made to within a greater tolerance band, the use of methods other than the injection moulding of an entire stick is possible. For example, injection moulding of the individual washers is possible, as is punching out the individual washers from a sheet of silicone rubber.

However, in a preferred embodiment the washers of the present invention are fabricated by extruding (although they could be fabricated by injection moulding) a "stick" of silicone rubber and subsequently parting the individual washers from the stick. This reduces the amount of wasted silicone rubber and therefore leads to a cheaper and more efficient method of production.

In a further aspect the present invention provides a method of fabricating a silicone rubber washer including the steps of extruding a cylindrical rod of silicone rubber and subsequently slicing the cylindrical rod into individual washers, wherein the washers are as described above.

In the manufacturing process for the closure assemblies used for tamper proof lids of whiskey bottles, the washers are typically transported on feeders. Increased friction between the washer and the feeder can therefore lead to problems.

Therefore, in a further aspect the present invention provides a silicone rubber washer on at least one of the generally flat sides of which is at least one protrusion or surface undulation.

Preferably, there are a plurality of such protrusions e.g. 2, 3, 4, 5, 6, 7 , and preferably there is at least one protrusion (and more preferably a plurality) on each of the two flat sides of the washer.

By using such protrusions, the amount of the washer which contacts the feeder is reduced and therefore the friction between the washer and the feeder is correspondingly reduced.

Any or all of the above aspects may be incorporated in an embodiment of a washer according to the present invention.

As described above, one particular use for the silicone rubber washers is in the closure assembly of a tamper proof lid used for e.g. whiskey bottles.

Accordingly, in a further aspect, the present invention provides a tamper proof closure for a bottle including a sealing washer, wherein the washer is a washer according to one of the aspects of the invention described above.

Embodiments of the present invention will now be described with reference to the accompanying drawings in which: Fig. 1 is a top view of a prior art washer; Fig. 2 is a top view of a washer according to a first aspect of the present invention; Fig. 3 is a top view of a washer according to a further aspect of the present invention.

Fig. 4 is a cross-sectional view through a tamper proof closure for a whiskey bottle incorporating a washer according to the present invention; and Fig. 5 is a view from below of the tamper proof closure of Fig. 4.

Fig. 1 shows a prior art silicone rubber washer 2 which is generally cylindrical in shape. It has a flat side 4, an inside bore or surface 6 and an outside surface 8.

Fig. 2 shows a top view of a silicone rubber washer 20 according to a first aspect of the present invention. On the inside surface 22 of the washer 20 are a number of projections or undulations 24.

Preferably, these projections 22 extend more than 0.lmm away from the face of the inside surface 22.

Preferably the washer 20 has the following dimensions: The minimum inside diameter of the washer is approximately 17.5mm and the maximum inside diameter is approximately 18.8mm. The outside diameter is sized so as to fit inside the appropriate bottle closure. The thickness of the washer may be from approximately lmm upwards.

Fig. 3 shows a top view of a silicone rubber washer 30 according to a further aspect of the present invention. On the flat face 32 of the washer 30 are a number of projections or undulations 34. Similar projections may be located on the other flat face of the washer (not visible).

Washers as shown in Fig. 2 or Fig. 3, or indeed a single washer incorporating the features of the washers of Figs. 2 and 3, may be used in the closure assembly of Figs. 4 and 5.

Fig. 4 is a cross-sectional view from the side of a tamper proof closure (generally indicated 40) suitable for e.g. a whisky bottle. The closure 40 includes a neck portion 42 which fits inside the neck of a bottle (not shown). The closure 40 also includes a pouring portion 44 which, in use, rests on the top of the neck of the bottle. A suitable cap may be fitted over the pouring portion 44 and secured by the screw threads 46.

In order to seal the gap between the closure 40 and the bottle (not shown), a washer 48 according to any aspect of the present invention is provided. The washer 48 sits on top of the neck of the bottle in use.

The washer 48 has a number of protrusions on the inside bore of the washer. These protrusions contact the generally cylindrical neck portion 42 of the closure 40 and allow the fit between the outside of the neck portion and the inside bore of the washer to be a friction fit.

Fig. 5 shows a view from beneath of a closure 40 according to Fig. 4. The view is generally in the direction of arrow A. The fit of the washer 48 against the shoulder 50 between the pouring portion 44 and the neck portion 42 of the closure 40 can be more clearly seen.

The above embodiments of the present invention have been described by way of example only and various alternative features or modifications from what has been specifically described and illustrated can be made within the scope of the invention, as will be readily apparent to the person skilled in the art.

Claims (11)

CLAIMS:

1. A silicone rubber washer on the inside surface of which is at least one projection.

2. A washer according to claim 1, wherein the washer is a solid cylindrical washer and the at least one projection is pointing towards the centre of the washer.

3. A washer according to claim 1 or claim 2, including a plurality of projections.

4. A washer according to any one of the above claims in which the projection(s) extend at least 0.lmm away from the inside wall of the washer.

5. A silicone rubber washer on at least one of the generally flat sides of which is at least one protrusion or surface undulation.

6. A washer according to claim 5, including a plurality of such protrusions.

7. A washer according to claim 6, in which there is at least one protrusion on each of the two flat sides of the washer.

8. A method of fabricating a silicone rubber washer including the steps of extruding a cylindrical rod of silicone rubber and subsequently slicing the cylindrical rod into individual washers, wherein the washers are washers according to any one of the above claims.

9. A tamper proof closure for a bottle including sealing washers according to any one of claims 1 to 7.

10. A washer substantially as any one embodiment herein described with reference to the accompanying drawings.

11. A closure substantially as any one embodiment herein described with reference to Figs. 4 and 5 of the accompanying drawings.