A Threaded Closure

Abstract

A closure is provided and comprises a top plate and a sidewall depending therefrom. The interior of the sidewall has a screw thread formation comprising a plurality of thread segments. The thread segments collectively define an engagement surface for engagement with an external thread formation on an associated container. A notional helical top surface with a constant pitch extends along the formation, and at least some, but not all, of the segments include material offset from the notional helical top surface towards the top plate.

Claims

1. A closure comprising a top plate and a sidewall depending therefrom, the interior of the sidewall having a screw thread formation, the formation comprising a plurality of thread segments, the thread segments collectively define an engagement surface for engagement with an external thread formation on an associated container, a notional helical top surface with a constant pitch extends along the formation, at least some, but not all, of the segments include material offset from the notional helical top surface towards the top plate.

2. A closure as claimed in claim 1, in which top surface offset is formed by axial displacement of a segment.

3. A closure as claimed in claim 1, in which top surface offset is formed by additional material along at least part of the top surface of a segment

4. A closure as claimed in claim 1, in which the top surface offset is formed by one or more surface features.

5. A closure as claimed in claim 1, in which the formation has centre line with a constant helical pitch.

6. A closure as claimed in claim 1, in which the notional helical top surface is based on a notional formation having a standard thread pitch.

7. A closure as claimed in claim 6, in which the standard thread pitch is defined by two or more thread segments positioned towards the opposite end of the sidewall to the top plate.

8. A closure as claimed in claim 1, in which the notional helical top surface pitch is defined by two or more thread segments positioned towards the opposite end of the sidewall to the top plate

9. A closure as claimed in claim 1, in which only the final three segments in the formation have offset top surfaces.

10. A closure as claimed in claim 1, in which at least one of the segments has a first axial thickness and at least one of the segments has a second axial thickness which is greater than the first axial thickness and being increased in a direction towards the top plate so as to offset the top contact surface of the formation and compensate vertical displacement of the closure in use.

11. A closure as claimed in claim 10, in which the or each segment having the second axial thickness is provided only on one side of the sidewall.

12. A closure as claimed in claim 10, in which the or each segment having the second axial thickness is provided on the side of the sidewall on which the formation terminates at an axial level spaced furthest from the top plate.

13. A closure as claimed in claim 10, in which the second axial thickness is formed as an increase in height towards the top plate.

14. A closure as claimed in claim 1, in which approximately 0.1 mm of material is added to the top contact surface of one or more thread segments.

15. A closure as claimed in claim 1, comprising an inner seal and an outer seal.

16. A closure as claimed in claim 1, further comprising a pressure formation.

17. A closure comprising a top plate and a sidewall depending from the periphery thereof, the interior of the sidewall having a screw thread formation, the formation comprising a plurality of separate thread segments, at least one of the segments having a first axial thickness and at least one of the segments having a second axial thickness which is greater than the first axial thickness and being increased in a direction towards the top plate so as to offset the top contact surface of the formation and compensate vertical displacement of the closure in use.

18. (canceled)

19. A closure comprising a top wall and an annular skirt depending therefrom, the interior of the skirt has a screw thread formation for threaded engagement with an external thread formation on an associated container, the formation comprising a plurality of thread segments, in which the thread segments include two or more different segment profiles, and in which the closure comprises an outer seal for sealing against a container neck, and a pressure formation for pressing the outer seal against the neck.

20. A closure as claimed in claim 19, in which the thread segments collectively define an engagement surface for engagement with an external thread formation on an associated container, and in which a notional helical top surface with a constant pitch extends along the segments, and some of the segments include material offset from the notional helical top surface towards the top plate.

21. A closure as claimed in claim 19, in which the pressure formation is a pressure block, in which the pressure block is generally annular, and in which the pressure block is segmented or continuous.

22. (canceled)

23. (canceled)

24. (canceled)

25. (canceled)

26. (canceled)

27. (canceled)

28. (canceled)

Description

[0057] In the following description, all orientational terms, such as upper, lower, radially and axially, are used in relation to the drawings and should not be interpreted as limiting on the invention.

[0058] FIG. 6 illustrates the general principle of one embodiment of the present invention in which thread segments 109 in a restricted circumferential section (for example around about half of the circumference of the sidewall) are increased in height towards the top plate 102.

[0059] FIG. 7 shows part of a closure 201 formed in accordance with the present invention. The sidewall 203 includes some standard thread segments 209a and some increased height segments 209b with additional material 210. Adding thickness only on some thread segments provides compensation for displacement. In this embodiment the additional material increases the top contact surface by approximately 0.1 mm. In this way, this part of the thread path is offset over the standard thread pitch.

[0060] FIG. 8 shows a graph illustrating the axial displacement of the outer seal of the closure 1 compared with the closure 207 when subjected to elevated temperature and pressure. It can be seen outer seal displacement in the closure 207 is greatly reduced, leading to a reduced risk of leakage in use.

[0061] FIGS. 9 and 10 show two further embodiments in which closure thread segments 309b, 409b include additional material 310, 410.

[0062] FIG. 11 shows an exterior view of a closure 501 formed in accordance with a further embodiment and having a top wall 502 and a side skirt 503. The skirt 503 has a plurality of external ribs 500.

[0063] FIGS. 12A to 12D show sections of closures 601, 701, 801, 901 formed in accordance with the present invention and illustrating different options for providing a thread formation having a top contact surface which is partially non-helical.

[0064] In the closure 601 FIG. 12A additional material 610 is added to some of the segments 609b. This means that the top surface of segments 609a without additional material align with the notional helical line 612, whereas the top surface of segments 609b with the additional material project above the line 612.

[0065] The same effect as with adding material onto a thread segment to provide material extending beyond the notional helical top surface line can also be achieved via some additional bars, ramps, dots etc: see FIGS. 12B, C and D.

[0066] In FIG. 12B the closure 701 has some thread segments 715 with lateral thread projections 716, 717

[0067] In FIG. 12C the closure 801 has some segments 820 with multiple point axially extending projections 821, 822, 823.

[0068] In FIG. 12D the closure 901 has some thread segments 825 with a single point extension 826.

[0069] Alternatively or additionally, the additional material could be in the form of a wave etc. (not shown). Furthermore, individual threads (in some embodiments only the three top threads are of highest relevance) can be shifted upwards towards the top plate; this would result in thread segments with top contact surfaces above the notional helical line, and also a non-helical centreline e.g. some segments (principally at or towards the end of the thread formation (closest to the top plate) would be above a notional centreline define by a majority of the thread segments (particularly those at the start of the thread formation).

[0070] Having the new offset feature (bars etc.) can also have the beneficial effects of: 1) providing secondary venting (additionally venting channels); 2) minimize friction since the thread does not have full contact with the neck; 3) further weight saving, since the amount used for the bumps/bars is less than putting additional material onto the whole thread segment.

[0071] FIGS. 13 to 15 relate to the incorporation of a pressure block feature.

[0072] The pressure block functions to centre the closure onto the neck, thereby vertical movement is further reduced.

[0073] In FIG. 13 the closure 1001 has a pressure block comprising a plurality of arcuate block segments 1030 extending radially inwards from the sidewall 1003; each of the segments has a circumferential extent corresponding to an underlying thread segment 1009. The thread segments are also separated by axial vent channels 1050.

[0074] In FIG. 14 the closure 1101 has a pressure block comprising block segments 1135. In this embodiments there are three block segments provided above each thread segment 1109.

[0075] In FIG. 15 the closure 1201 has a pressure block comprising a complete annulus 1240.

[0076] Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiments shown and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.