A METHOD OF FORMING A CLOSURE

Abstract

A method of forming a bi-injected closure, comprising the steps of: forming a cap with a top plate and a depending sidewall, in a first injection moulding phase using a first mould part, the cap formed so as to include one or more external sealing areas; changing the first mould part for a second mould part, the second mould part sealing against the or each sealing area on the cap; and forming an outer ring around the cap sidewall whilst the second mould part is sealed against the sealing area/s in a second moulding phase.

Claims

1. A method of forming a bi-injected closure, comprising: forming an inner cap with a top plate and a depending cylindrical sidewall in a first injection moulding phase using a first mould part, the sidewall of the inner cap formed so as to include two external sealing support areas, the sealing support areas comprising radial steps which flank a portion of the sidewall onto which an outer ring is to be formed; changing the first mould part for a second mould part, the second mould part sealing against the sealing areas on the sidewall of the inner cap so as to delimit a cavity for the outer ring; and forming the outer ring around the sidewall of the inner cap whilst the second mould part is sealed against the sealing support areas in a second moulding phase, a material for the outer ring being injected between the two sealing support areas.

2-5. (canceled)

6. A method as claimed in claim 1, in which each of the sealing areas is generally flat or is angled, or is a chamfer, or is a radius.

7. A method as claimed in claim 1, in which each sealing area has a width in the range of 0.1 mm to 0.3 mm.

8. A method as claimed in claim 1, in which the closure is demoulded along a main axis thereof after the second moulding phase.

9. A method as claimed in claim 1 in which in the first moulding phase the material is injected generally axially.

10. A method as claimed in claim 1, in which in the second moulding phase the material is injected generally laterally.

11. A method as claimed in claim 1, in which the first and second mould parts are portions of a mould and part of the mould is rotated between the first and second moulding phases.

12. A method as claimed in claim 11, in which the inner cap carried on a core mould part is rotated.

13. A method as claimed in claim 12, in which the core mould part is rotated approximately 90 degrees.

14. A method as claimed in claim 1, in which the sidewall of the inner cap is formed so as to include one or more anti-rotation ribs on an exterior of the sidewall.

15. A method as claimed in claim 1, in which the outer ring is formed so as to include one or more ribs on an exterior of the outer ring.

16. A method as claimed in claim 1, in which the inner cap is formed from polyethylene.

17. A method as claimed in claim 1, in which the outer ring is formed from a thermoplastic elastomer material.

18-35. (canceled)

36. A method as claimed in claim 1, in which at the end of the sidewall of the inner cap and opposite the top plate an inclined wall section is provided and extends radially outwards.

37. A method as claimed in claim 36, in which at the end of the inclined wall section an axial wall section depends and defines a radial step.

Description

[0045] The present invention is more particularly shown and described, by way of example, with reference to the accompanying drawings, in which:

[0046] FIG. 1 is a section of a closure formed in accordance with the present invention;

[0047] FIG. 2A is a section of the inner cap part of the closure of FIG. 1;

[0048] FIG. 2B is a section of the ring part of the closure of FIG. 1;

[0049] FIG. 3 is a section of the closure of FIG. 1 shown fitted to a container neck;

[0050] FIGS. 4 to 8 illustrate the steps in a method according to the present invention;

[0051] FIG. 9 shows part of a closure formed in accordance with the present invention; and

[0052] FIGS. 9A and 9B show magnified areas 1 and 2 of FIG. 9 respectively.

[0053] Example embodiments are described below in sufficient detail to enable those of ordinary skill in the art to embody and implement the systems and processes herein described. It is important to understand that embodiments can be provided in many alternate forms and should not be construed as limited to the examples set forth herein.

[0054] Accordingly, while embodiments can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples. There is no intent to limit to the particular forms disclosed. On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be included. Elements of the example embodiments are consistently denoted by the same reference numerals throughout the drawings and detailed description where appropriate.

[0055] The terminology used herein to describe embodiments is not intended to limit the scope. The articles “a,” “an,” and “the” are singular in that they have a single referent, however the use of the singular form in the present document should not preclude the presence of more than one referent. In other words, elements referred to in the singular can number one or more, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including,” when used herein, specify the presence of stated features, items, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, items, steps, operations, elements, components, and/or groups thereof.

[0056] Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealized or overly formal sense unless expressly so defined herein.

[0057] Referring first to FIG. 1 there is shown a closure generally indicated 10. The closure 10 comprises an inner closure 15 and an outer ring 20.

[0058] The inner cap 15, also shown in FIG. 2A, comprises a generally disc-shape top plate 25 and a generally cylindrical sidewall 30 which depends from the periphery of the top plate 25.

[0059] An internal annular sealing projection 35 depends from the underside of the top plate 25 and the inner surface of the sidewall 30 is provided with internal screwthread formations 40. The exterior of the sidewall is provided with a plurality of circumferentially spaced axial anti-rotation ribs 36

[0060] At the end of the sidewall opposite the top plate 25, an inclined wall section 45 is provided and extends radially outwardly.

[0061] At the end of the wall section 45 an axial wall section 47 depends and defines a radial, flat step 46.

[0062] The section 47 merges into an annular tamper-evident band 50 which is provided with an annular bead 55 on its interior surface.

[0063] At the top of the sidewall a curved intermediate wall section 31 extends and merges into the top plate 25. At the intersection of the wall section 31 and the sidewall a flat radial section 32 is defined.

[0064] The ring 20 is generally annular with a main annular sidewall section 21 which at one end has an inclined terminus 22 shaped to correspond to the sidewall step 45. The exterior surface of the section 21 is provided with a plurality of axial ribs 23 and on the interior of the ring a plurality of grooves 24 are formed at the end closest to the terminus 21 corresponding to the ribs 36.

[0065] As shown in FIG. 3, in use the closure 10 is fitted to a container neck 60 by screwthread engagement between the sidewall threads 40 and corresponding thread 64 on the neck. The inner ceiling skirt 35 fits into the bore of the neck 60 to form a ceil against its interior surface and the bead 55 passes under a neck transfer bead 62 so that upon first opening when the closure is unscrewed the tamper-evident band 50 remains on the neck finish and is released from the sidewall step 45, for which purpose a plurality of frangible bridges 51 interspersed and defined by slits.

[0066] FIGS. 4 to 8 illustrate a method according to the present invention by which a closure of the type shown in FIGS. 1 to 3 could be manufactured.

[0067] In FIG. 4 a mould generally indicated 170 is shown in a closed position a female or upper mould part 175 is closed onto an inner core 180 to define a mould cavity 177 corresponding to the inner cap 115. A plastics material, in this embodiment polyethylene, is injected into the mould in an axial direction X, in this embodiment with the gate generally in the centre of what will become the top plate 125.

[0068] In FIG. 6 the mould has been opened. The newly formed inner cap 115 remains on the core 180 whilst the mould part 175 is withdrawn axially. The mould is then rotated, for example 90 degrees, and a new female mould part 185 is closed onto the inner cap, as shown in FIG. 6A.

[0069] The cavity into which the second material is injected is delimited by two closure zones A, B. The mould part closes onto the closure in the closure zones; there is direct compression on the inner cap.

[0070] In this position the mould part 185 is partly supported by sealing areas A and B shown in FIG. 6B. The mould part 185 is supported principally at zones A and B. The metal mould part 185 seals against the cap steps 132, 146. The steps 132, 146 help to delimit the cavity into which material flows to form the ring 120.

[0071] With the mould in the closed position shown in FIG. 6A and 6B the material for the bi-injected ring 120 is now introduced in a lateral direction Y by a lateral nozzle.

[0072] The outer ridges 136 on the cap sidewall are shown and it can be seen that the material of the ring flows around the ridges 136 to form the correspondingly shaped grooves 124 which help to promote bonding between the two materials.

[0073] In FIG. 7 the mould is shown opened, with the mould part 185 withdrawn axially i.e. simple demoulding in the principal axis of the workpiece. The core 180 is then stripped to release the closure as shown in FIG. 8. The closure 110 is then ejected from the mould ready for use.

[0074] In this embodiment the closure 110 is post-mould processed to introduce slits to define frangible bridges and thus creates the tamper-evident band at the free end of the sidewall.

[0075] FIGS. 9, 9A and 9B show a magnified view of part of a closure 210 formed according to a further embodiment. In this embodiment the inner closure 215 has two support zones: support 1 is a flat radial step 296 located between the top plate and the sidewall, immediately adjacent one end of the ring; support 2 is an angled step 297 immediately adjacent the other end of the ring 220 and just above the point along the sidewall where frangible bridges 295 are formed. In other embodiments, for example, support 1 is an angled step 296a and support 2 is a flat step 297a, as also shown in the drawings. The zones give a good metal/plastic closure when the mould is closed and the mould part presses onto the supports.

[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.