Description

METHOD FOR PRODUCING SUCH A METAL CLOSURE WITH SEPERATE DISC AND RING FROM A SINGLE CLOSURE BLANK

Technical Field

[0001] The present invention concerns a metal closure having a sidewall and separate disc, which forms the top plate of the closure.

Background Art

[0002] A closure comprising a plastic sidewall and a metal disc is well known and a closure of this type is commonly referred to as a "combo closure". Conventionally, the sidewall or "ring" is made from a pkstic material by injection moulding. This plastic ring defines threads, which cooperate with similar threads on a container neck. A tamper evident band is defined at the free end of the "ring" and joined thereto by frangible bridges. The frangible bridges are designed to break upon opening of the closure, to indicate to a user of the closure / container package that the closure has been opened previously. Sealing compound is conventionally applied to the metal disc to form a seal between the metal disc and the mouth of the container. Patent Citation 0001 : US 6662958 B (CROWN, CORK & SEAL TECHNOLOGIES CORPORATION). 2003-12-16. relates to such a closure. An advantage of this type of closure is that the tamper evident band breaks before the seal between the metal disc and the container is broken, giving a user confidence that the contents within the container has not been subject to tampering.

[0003] The 2-piece closure design allows the breaking of the container seal to be controlled. The initial twisting of the closure "ring" activates the tamper-evident feature, such as breaking a tamper-evident band, whilst the disc remains sealed to the container. Thereafter, a further feature may be provided on the closure "ring" to prise the disc from the container, thereby breaking the seal between the disc and the container to equalise any difference between the internal pressure in the container and the external environment. This 2-stage opening reduces the torque required to open the closure and allows the closure to be removed more easily.

[0004] Disadvantages of the arrangement described in Patent Citation 0002: US 6662958 B -. are that the combination of metal and plastic material makes the closure more difficult to recycle. Also, the recent increase in pkstic raw material costs makes the

closure relatively expensive to manufacture and the pkstic "ring" prevents the use of the closure on packages, which are subjected to a retort process. [0005] Combo closures having a metal ring confining a glass top plate (or disc) are well known in the prior art and are used for home preserving. However, these closures are also made from two materials (metal and glass), which must be recycled separately. [0006] Patent Citation 0003 : EP 1686070 A (PLATO PRODUCT CONSULTANTS). 2006-08-02. describes a "combo" closure comprising a disc and a ring shaped element. A "special feature" is described, which reduces the torque required to unscrew the closure from a container. The closure described in this document utilises a separate, annular gasket, which enhances the seal between the closure and the container to which the closure is affixed.

Disclosure of Invention

[0007] If an all-metal equivalent of the known "combo closure" were provided, this would allow a user to gain the benefit of reduced opening torques, whilst a package incorporating the closure may pass through a retort process as currently used for one-piece metal twist closures. Such an all-metal "combo" closure would be easier to recycle as it is substantially composed of only one material. Furthermore, if the closure were manufactured from a conventional metal, twist closure shell, existing capping equipment may be used to apply the closure to the container.

[0008] The cost of manufacturing such an all-metal closure requires efficient use of metal raw material to reduce wastage. A problem arising from manufacture of a metal version of a "combo" closure comprising a metal ring and a metal disc is that if both these metal components are produced from separate pieces of material, the amount of wastage is significant. Alternatively, if a "disc" is simply cut from the top plate of a conventional metal closure blank, this disc will not be constrained by the remaining "ring". This is because the "disc" will be able to pass through the resulting hole in the "ring" will be too large to constrain the aforementioned disc.

[0009] Accordingly, the present invention provides a method of manufacture for a metal closure having separate disc and a circumferential ring, including the steps of

- drawing a closure blank from a sheet of metal, the closure blank having a top plate and a sidewall depending from the periphery thereof,

- cutting the sidewall of the closure blank adjacent to the top plate to produce a disc and a circumferential ring both having a cut edge.

[0010] The closure according to the invention is made predominantly from metal (except for a small quantity of sealing compound), which improves a user's ability to recycle the closure after it is no longer needed. Lugs may be provided at the edge of the ring opposite the disc according to conventional processes.

[0011] Preferably, a curl is formed at the free edge of the closure bknk prior to separation of the sidewall (ring) from the top plate (disc). A curl protects the cut edge of the closure bknk, preventing injury etc. and provides rigidity to the ring upon separation of the sidewall from the top pkte.

[0012] The sidewall of the closure bknk is cut adjacent to the top pkte, to provide a ring and a separate disc. The closure bknk may be cut using any conventional process e.g. kser cutting. The disc thus produced, will have the same diameter as the ring. Therefore, the cut edge of the disc is hemmed or curled to reduce its outside diameter and thereby allow it to be inserted into the ring.

[0013] Alternatively, the sidewall of the closure bknk may be separated from the top pkte by the known process of "clip trimming". This process requires that the top of the sidewall (adjacent to the top pkte) is first drawn to a smaller diameter by a first punch and die and then severed by a second punch part having a sharp corner and a diameter between that of the die and the first punch part. This technique is most commonly used for trimming metal container bodies or for trimming thin aluminium Roll On Pilfer Proof (ROPP) closures. The advantage of this technique is that the diameter of the disc is reduced and the subsequent hemming of the disc is not required.

[0014] In one embodiment of the invention, the disc is supported in the ring so that the cut edges of both the ring and the disc are proximate one another and then the cut edges of the ring and the disc are loosely curled together. This embodiment has the advantage that the ring requires no retention features because the loose curl loosely retains the disc within the ring, whilst allowing the disc both axial and rotational movement.

[0015] Finally, in another embodiment of the invention, an alternative bknk configuration is proposed which allows the disc and the rink to be loosely curled together as discussed above, but in this embodiment the external surface of the bknk may be printed or treated before separating into a disc and ring. The disc and ring may then be assembled as described above, but in this embodiment, both the external surface of the disc and the ring is already printed or treated.

[0016] Tamper evidence may be provided on the 2-piece metal closure by taking advantage of the feet that the ring and the disc are independent and move separately upon initial opening of the closure. Thus initially, when the ring is twisted by a defined amount,

the disc remains sealed to the container and does not move. A frangible bridge or kbel may be secured to the disc and the ring and upon an attempt to remove the closure, the relative movement of the ring relative to the disc breaks the frangible bridge or kbel, giving a visual indication that an attempt has been made to remove the closure from the container.

Brief Description of Figures in the Drawings The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[fig.]Figure 1 shows a cross sectional view of a 2-piece closure attached to a container, indicating (by a circle) the area illustrated in all detailed cross section views included in the accompanying Figures;

[fig.]Figure 2 shows a detailed cross section view of a portion of the 2-piece closure according to a first embodiment of the invention having a disc and a ring, the cut edge of the ring is curled to constrain the disc therein and retention features are formed in the ring to locate the disc in its desired position;

[fig.]Figure 3A shows a schematic side section view through a closure bknk, conventionally used to make a one-piece closure, but which is suitable for use in the invention;

[fig.]Figure 3B shows the schematic side section view of the closure bknk of [fig.] Figure 3A after a curl has been formed at the free edge of the closure skirt, indicating where the top may be cut from the side wall of the closure to form a disc and a ring;

[fig.]Figure 3C shows a schematic side section view of the closure bknk shown in [fig.]Figure 3B after the top and side wall of the closure have been severed to form a disc and a ring;

[fig.]Figure 3D shows a schematic side section view of the modified closure bknk shown in [fig.]Figure 3C after formation of a curl around the cut edge of the disc;

[fig.]Figure 4A shows a schematic side section view of the modified closure bknk shown in [fig.]Figure 3C according to another embodiment of the invention in which the closure curl (on the ring) is flattened and the disc is inverted before insertion into the ring;

[fig.]Figure 4B shows a schematic side section view of the modified closure bknk shown in [fig.] Figure 4 A with the disc inverted, inserted into the ring and supported against the flattened curl;

[fig.]Figure 4C shows a schematic side section view of the modified closure bknk

shown in [fig.] Figure 4B after formation of a curl at the cut edge of the ring;

[fig.] Figure 4D shows a detailed cross section view of a portion of the finished 2-piece closure according to the alternative embodiment of the invention. In this arrangement, retention features are formed in the ring to locate the disc in its desired position and with the closure tightened onto a container to form a seal between the disc and the container;

[fig.] Figure 4E shows the same portion of the 2-piece closure shown in [fig.] Figure 4D after the ring has been unscrewed, the retention feature has lifted the disc from the container and the seal between the disc and the container has been broken;

[fig.]Figure 5 is a schematic view of the punch and die arrangement used for "Clip trimming" the closure to separate the sidewall and top plate, whilst reducing the outside diameter of the top plate / "disc". The portion of the tooling utilised in the enhanced view (see [fig.]Figure 5A) is indicated by the circle labelled "A".

[fig.]Figure 5A is an enhanced view of a portion of the tooling shown in [fig.]Figure 5;

[fig.]Figure 6A shows a schematic side section view of the ring shown in [fig.]Figure

3C after the top and sidewall of the closure have been severed;

[fig.]Figure 6B shows a schematic side section view of the ring shown in [fig.]Figure

6 A after formation of a ring curl at the cut edge of the ring;

[fig.]Figure 6C shows a schematic side section view of a metal closure according to the invention after the disc has been inserted into the ring shown in [fig.] Figures 6 A and 6B;

[fig.] Figure 6D shows a detailed cross section view of a portion of the finished 2-piece closure shown in [fig.] figure 6C, with the closure tightened onto a container to form a seal between the disc and the container. In this arrangement, there are no retention features and the disc is free to move axially within the ring;

[fig.] Figure 6E shows the same portion of the 2-piece closure shown in [fig.] Figure 6D after the ring has been unscrewed, the lugs on the ring have lifted the disc from the container and the seal between the disc and the container has been broken. By using the method illustrated in [fig.]Figures 6A to 6E, there is no need to invert the disc 10' or the ring 20'. Furthermore, the lugs 26 are formed in the closure curl 25, which has a greater work-hardening than the ring curl 28, formed at the cut-edge of the ring 20'.

[fig.]Figure 7 shows a detailed cross section view of a portion of the 2-piece closure according to a second embodiment of the invention having a disc and a ring, where the cut edges of the disc and the ring are loosely curled together, allowing the disc space to move both axially and rotationally within the ring;

[fig.]Figure 8A to [fig.]Figure 8D show a similar schematic progression to that shown in [fig.]Figure 3A to [fig.]Figure 3D and [fig.]Figure 4A to [fig.]Figure 4C for the second embodiment of the invention shown in [fig.]Figure 7; and [fig.]Figure 9A to [fig.]Figure 9D show a similar schematic progression to that shown in [fig.]Figure 8A to [fig.]Figure 8D for a modification to the second embodiment of the invention shown in [fig.] Figure 7 allowing the external surface of the closure blank to become the external surface of the 2-piece closure.

[0018] All same or similar components in the figures have been labelled using the same or similar reference numerals respectively.

[0019] Referring to [fig.]Figure 1, which is primarily included to illustrate the location of the various detailed views in the remaining figures, a package comprises a threaded container 3 and a 2-piece closure 1' having a disc 10' and a peripheral ring 20'.

[0020] [fig.]Figure 2 shows a detailed view of part of the package illustrated in [fig.]Figure 1. The 2-piece closure comprises a metal disc 10'; whose cut edge is protected by a curl 15 and a circumferential ring 20'. The disc 10' is trapped within the ring by two curls 25, 28 at the opposed axial ends of the ring 20'. A retention feature, or features 27 are provided to position the disc 10' loosely within the ring 20', whilst allowing the disc 10' freedom to move both axially and rotationally relative to the ring 20'. The retention feature 27 may take the form of a plurality of lugs spaced around the circumference of the ring 20' or alternatively may be provided by a circumferential bead, either full or segmented. A channel 12 is provided about the inside periphery of the disc 10' and this channel is used to hold sealing compound 50. The provision of the channel 12 ensures the proper location of the sealing compound to interlace with the neck of the container 3 and also reduces the quantity of sealing compound 50, because of its better and more accurate distribution.

[0021] [fig.]Figures 3A to [fig.]3C show a schematic progression for manufacture of the

2-piece metal closure shown in [fig.]Figure 2. First a conventional closure blank 1 for a one-piece metal closure is drawn from a sheet of metal (see [fig.]Figure 3A). The closure blank has a top plate 10 and sidewall 20, which depends from the periphery of the top plate 10. A recess 12 for sealing compound may be defined adjacent the periphery of the top plate 10, but this is not essential.

[0022] The free-edge of the sidewall 20 is formed into a closure curl 25, making a one-piece metal closure shell 1. The closure shell 1 may be cut at line A-A (see [fig.]Figure 3B) by conventional techniques, such as rotary cutting, laser cutting or clipping. Cutting the closure blank 1 along line A-A separates the closure blank into two separate

components, a disc 10' and a ring 20' (as shown in [fig.]Figure 3C). The cut edge of the disc 10' is rolled into a curl 15 and the curl 15 both provides cut edge protection and reduces the outside diameter of the disc 10' so that it can fit into the ring 20', through the raw cut-edge of the ring 20' (see [fig.]Figure 3D). The raw cut edge of the ring 20' may then also be curled to provide both cut edge protection and to constrain the disc 10' within the ring 20' (as illustrated in [fig.]Figure 2). Once the disc 10' is constrained within the ring 20', the position of the disc may be more closely controlled by the provision of retention feature or features 27.

[0023] Referring to [fig.]Figure 4A, the manufacturing process may be modified by flattening the closure curl 25' prior and inverting the disc 10' or the ring 20' and assembling the disc 10' in the ring 20'. As shown in Figure 4B, in this arrangement, the disc 10' is supported by the flattened curl 25'. At this stage, sealing compound 50 is inserted into the channel 12. Lugs or similar conventional means for securing the closure to the container (not shown) may be provided in the curl 28 or in the ring 20'.

[0024] The flattened curl of the modified closure shown in [fig.] Figure 4 A to [fig.]4E has the advantage that conventional belt capping systems, having one or more belts, which contact the top surface of the closure, may be used to apply the modified 2-piece closure to the container 3. Referring to [fig.] Figure 4D, when the closure is tightly applied to the container 3, the flattened curl 25' urges the disc 10' towards the mouth of the container and the interaction between the container threads 35 and the closure lugs 26 or the like, tighten the seal formed by the sealing compound 50 and the container 3.

[0025] Referring to [fig.]Figure 4E, upon opening the closure, the lugs 26 ride past the container thread 35 the retention feature 27 engages with the disk curl 15, lifts the disk 10' and breaks the seal between the sealing compound 50 and the container 3. Upon initial turning of the closure on the container 3, the disc 10' remains sealed to the mouth of the container 3 whilst the ring turns and lifts slightly. This relative movement between the disc 10' and the ring 20' may be use to trigger some form of tamper evidence. For example, a frangible bridge (such as a paper label) may be anchored to both the ring 20' and the disc 10' and the relative movement of the ring 20' relative to the disk 10' may sever the frangible bridge giving a visible indication that an attempt has been made to open the package.

[0026] Figures 5 and 5A illustrate how the punch and die arrangement used for "clip trimming" may be used to sever the top plate 10 from the sidewall 20 of a closure blank 1 to form a ring and a disc of reduced diameter. Part of the sidewall 20 of a

closure bknk 1 is first drawn to a smaller diameter by a first punch part 70 and a die 80. The closure 1 is held by the location ring 85, whilst the reduced diameter part of the closure bknk 1 is then severed from the remainder of the sidewall 20 by a second punch part 75 defining a sharp corner 72 and having an outside diameter between that of the die 80 and the first punch part 70. Using such a method, the diameter of the disc is reduced and subsequent hemming of the periphery of the disc is not needed to reduce the diameter of the disc to fit inside the ring.

[0027] In another embodiment, after cutting from the disc, the cut edge of the ring 20' is provided with a ring curl 28, to protect the cut edge of the ring 20' (as shown in [fig.] Figures 6 A and 6B). The ring 20' is then flexed to allow the previously formed disc 10' to be inserted into the ring 20' from below (as shown in [fig.]Figure 6C). Finally, the disc 10' is retained within the ring 20' by forming lugs 26 (as shown in [fig.]Figure 6D). The steps of inserting the disc 10' into the ring 20', forming the ring curl 28 and forming the lugs 26 may be carried out in any sequence to produce the closure shown in [fig.]Figure 6D. Also, optionally, the disc 10' may be inserted into the ring 20' from above, which may be advantageous as there is no need to flex the ring 20'

[0028] The closure shown in [fig.]Figures 6D and 6E is simikr to that illustrated and described with respect to [fig.]Figures 4D and 4E, but without any retention feature. Referring to [fig.] Figure 6D, when the closure is tightly applied to the container 3, the ring curl 28 urges the disc 10' towards the mouth of the container and the interaction between the container threads 35, the lugs 26 and the ring curl 28, tighten the seal formed by the sealing compound 50 against the container 3. Upon opening (see [fig.] Figure 6E) the closure 1', the lugs 26 ride past the container thread 35, whilst the disc 10' remains sealed to the mouth of the container 3. The ring 20' continues to turn and lift until the lugs 26 engage with the disc curl 15. The lugs 26 lift the disc 10' and break the seal between the sealing compound 50 and the container 3. Thus, the closure "lifts" and then "pops", as the seal between the disc 10' and container 3 is broken.

[0029] [fig.]Figure 7 illustrates another embodiment of the invention, in which the cut edge of the ring 20' and disc 10' are loosely curled together. This embodiment also removes the need for a separate retention feature to control the position of the disc 10' within the ring 20'.

[0030] [fig.]Figure 8A to [fig.]6D show a progression for manufacture of the 2-piece metal closure shown in [fig.]Figure 7. A metal bknk, comprising a top 10 and a sidewall 20 is drawn from a sheet of metal and the closure bknk is again severed along line A-A producing a bknk for a disc 10' and a ring 20'. The closure bknk shown in [fig.]

Figure 8A may be decorated with a coating, lacquer or some other decoration 60 prior to severing along line A-A. Decorating the closure blank rather than the separate disc 10' and ring 20' of [fig.]Figure 8B is advantageous, because the closure blank is easier to handle, than the separate ring 20' and disc 10'. The problem associated with providing decoration on the external surface of the closure blank shown in [fig.] Figure 8A is that when the disc 10' and ring 20' are formed and assembled (see [fig.]Figure 8B to [fig.] 8D) the decoration 60 is located on the internal surface of the disc 10' and will not be seen by a user of the closure before first use. However, this disadvantage may be turned to an advantage, if the disc 10' is used to provide prize information etc., which is only required upon opening the closure.

[0031] A modification to the closure blank provided in [fig.]Figure 8A is illustrated in [fig.] Figure 9A. In this arrangement, the external surface of the closure blank may be decorated before forming the disc 10' and ring 20' (see [fig.]Figure 9B) and the decoration 60 will then be located on the external surface of the disc 10' (see [fig.] Figure 9B to [fig.]9D). The manufacturing method used to produce the embodiment shown in [fig.]Figure 7 is thereafter the same.

[0032] Referring to [fig.]Figure 8A and [fig.]Figure 9A a closure blank is drawn in a single piece from a sheet of metal. The closure blank is then severed between the top 10 and sidewall 20 to form a disc 10' and ring 20' (see [fig.]Figure 8B and [fig.]Figure 9B). Referring to [fig.]Figure 8C and [fig.]Figure 9C the cut edge of the disk 10' is hemmed (the start of a loose curl 15 is formed) to reduce the external diameter of the disc 10' so that it fits into the cut edge of the ring 20'. Also, one axial end of the ring 20' is formed into a curl 25.

[0033] As illustrated in [fig.]Figure 8D and [fig.]Figure 9D the hemmed disc 10' is inserted into the ring 20' and supported therein so that the cut edge of the disc 10' and ring 20' are proximate. The cut edge of the ring 20' is then curled loosely around the hemmed edge of the disc 10' to form a 2-piece closure as illustrated in the detailed cross section views of [fig.]Figure 7 and [fig.]Figure 9E. In this arrangement, the disc 10' is constrained loosely within the ring 20' by the loose curl 15, 28. The loose curl 15, 28 is designed to allow the disk 10' rotational movement as well as a limited degree of axial movement.

[0034] The embodiment illustrated in [fig.]Figure 9A to [fig.]9Eshows one further modification, which may be applied to any of the embodiments of the invention described previously. It can be seen that the ring 20' illustrated in [fig.]Figure 9A to [fig.]9E has a transition 29 by which the diameter of the ring 20' may be reduced, making the

finished closure more compact. Preferably, in any of the embodiments of the invention described above, sealant 50 is applied in the groove 12 of the disc 10', prior to assembly of the disc 10' in the ring 20'. This eases manufacture, because the disc 10' is easier to control and handle when separate than when assembled in the ring 20'.