Bottle cap and method of production and related apparatus

Abstract

Disclosed herein is a bottle closure comprising a cylindrical body with an open end and a closed end, and a fracture line formed in the cylindrical body extending from the open end toward the closed end, the fracture line having decreasing ultimate tensile strength from the open end to the closed end and being configured to fracture from the open end toward the closed end on application of a critical applied stress.

Description

BOTTLE CAP AND METHOD OF PRODUCTION AND RELATED APPARATUSField

[0001] The invention relates to a bottle closure, in particular for wine, foodstuffs and pharmaceutical, a related of production process, and an tools for use in fabricating such a bottle closure.Background

[0002] The invention generally relates to a bottle closure, and in particular wine ROPP (roll on pilfer proof), foodstuffs and pharmaceutical. Bottle closures are commonly manufactured using a deep redrawing process where a metal blank is progressively shaped using a punch, which is typically referred to by those skilled in the art as a porno and a redraw-ring.

[0003] Figure 1 is a simplified illustration of a typical metal wine bottle closure 100 after redrawing and before subsequent forming and application of the bottle closure 100 to a bottle. The bottle closure 100 includes an end cap portion 102 and a skirt portion 104.

[0004] A typical wine bottle with closure applied thereto is illustrated in Figure 2. The bottle closure 200 generally includes: a threaded end cap 202 which seals over the open end of a bottle 203, a skirt 204 extends downward from an open end of bottle 203 over a neck of bottle 203, a tuck-under 206 retains at least the skirt 204 on bottle 203 to provide tamper evidence, and a frangible portion or bridge region 210 between end cap 202 and skirt 204. The frangible portion 210 consists of breakable metal bridges designed to fracture upon initial opening of the closure. Frangible portion 210 allows a user to twist 202 to break the connection between end cap 202 and skirt 204, such that end cap 202 can be removed from bottle 203 whilst skirt 204 is retained on bottle 203 by tuck-under 206.

[0005] It is important that skirt 204 is retained around the neck of the bottle on removal of end cap 202 to provide the tamper evidence security. If skirt 204 could be easily removed such as with removal of end cap 202, then it would be possible to remove the entire closure including end cap 202 and skirt 204 and tamper with the contents of the bottle before replacing the closure. However, one shortcoming of retaining skirt 204 around the neck of the bottle is that itbecomes cumbersome to recycle the bottle after use. This is because skirt 204 must first be removed from the bottle so that the bottle can be recycled.

[0006] Removal of skirt 204 from bottle 203 can be achieved with a specialised removal tool. Typically, the removal tool is in the form of a blade or other sharp object which is inserted between the neck of bottle 203 and an internal facing surface of skirt 204. Skirt 204 can then be pried from bottle 203. However, this approach is time consuming, labour intensive, and can result in injury to a user. Other options include crushing the bottle with skirt attached, and then subjecting the crushed material to a separation process to separate glass and metal. However, this is costly since it involves machinery to carry out the crushing and separation processes.

[0007] In any case, whilst redrawing / forming process is an economical method of mass-producing such bottle closures, this traditional approach has a number of drawbacks.

[0008] One issue is that the resultant bottle closure has varying thickness, with the bottle closure being thicker towards the bottom as the metal blank is drawn through the die. One method of addressing this issue is to provide a blank with excess metal to account for this increase in thickness. However, this approach adds to the overall cost of the process. Another issue that arises is in situations where a coating is applied to the blank (e.g. an ornamental coating may be applied to a surface of the blank that forms the exterior surface of the bottle closure, or a functional coating may be applied to a surface of the blank that forms an internal surface of the bottle closure), is that the coating can be damaged during the drawing process. This can have a deleterious effect on both visual appearance and / or on the performance of the coating.

[0009] It is an object of the invention to address at least one shortcoming of the prior art and / or provide a useful alternative.Summary of Invention

[0010] In a first aspect of the invention, there is provided a bottle closure comprising:a cylindrical body with an open end and a closed end, anda fracture line formed in the cylindrical body extending from the open end toward the closed end, the fracture line having decreasing ultimate tensile strength from the open end to the closed end and being configured to fracture from the open end toward the closed end on application of a critical applied stress.

[0011] In an embodiment, the critical applied stress to initiate the fracture is greater than a stress to propagate the fracture.

[0012] In an embodiment, the fracture is a crack. Preferably, the fracture is a brittle crack. More preferably, the crack is self-propagating.

[0013] In an embodiment, the fracture is not a tear. The skilled person understands that a tear is a form of ductile material breakage characterized by significant plastic deformation before breakage. In contrast, the fracture of the present invention is a brittle fracture which is characterised by sudden and rapid breakage with little or no plastic deformation.

[0014] In an embodiment, the fracture line is formed in a cylinder wall portion of the cylindrical body. Preferably, the fracture line extends from the open end toward the closed end in a direction that is substantially parallel with an axis of the cylindrical body.

[0015] In an embodiment, the fracture line is formed on an inward facing surface of the cylindrical body, for example, on an inward facing surface of a cylinder wall portion of the cylindrical body. By inward surface, it is generally meant the surface that contacts a bottle to which the bottle closure is applied.

[0016] In embodiment, the cylindrical body or cylinder wall portion thereof is configured to adopt an open position on or after propagation of the fracture from the open end towards the closed end. In one form, the cylindrical body or cylinder wall portion thereof is configured to move to the open position. Preferably, the cylindrical body or cylinder wall portion thereof is configured to move to the open position under internal spring force or tension or restoring force. By way of example, tension within the cylindrical body or cylinder wall portion thereof acts as a spring force to move the cylindrical body or cylinder wall portion thereof to the open position on or after propagation of the fracture from the open end towards the closed end.

[0017] By open position, it is generally meant that separated edges of the cylindrical body or cylinder wall portion thereof, being formed on or after propagation of the fracture from the open end towards the closed end, move to a position where they are spaced apart from one another.

[0018] In an embodiment, the ultimate tensile strength decreases by about 10 to 40% from the open end to the closed end. Preferably the ultimate tensile strength decreases by about 12%.More preferably, by about 14%. Most preferably, by about 15%. Alternatively, or additionally, the ultimate tensile strength decreases by up to about 35%. More preferably, by up to about 30%. Most preferably, by up to about 25%. In one example, the ultimate tensile strength decreases by about 18% up to about 22%.

[0019] In an embodiment, the ultimate tensile strength decreases by at least 35 MPa from the open end to the closed end. Preferably, the ultimate tensile strength decreases by at least 40 MPa. More preferably, the ultimate tensile strength decreases by at least 50 MPa. Most preferably, the ultimate tensile strength decreases by at least 60 MPa.

[0020] In an embodiment, the decreasing tensile strength can be approximated using linear regression model of the form: FTu(d) = -Ad + Fintiai, where Fru(d) is the ultimate tensile strength as a function of distance, A is the gradient, D is the distance from the open end toward the closed end, and F initial is the critical applied stress to initiate the fracture along the fracture line.

[0021] In one form of the above embodiment, A has a value of from about 0.5 to about 0.9. Preferably A has a value of from about 0.55. More preferably, from about 0.6. Most preferably, from about 0.65. Additionally, or alternatively, A has a value of up to about 0.85. More preferably, A has a value of up to about 0.8. Most preferably, A has a value of up to about 0.75. In one example, A has a value of about 0.7 + / - 10%.]

[0022] In an embodiment, the critical applied stress is from about 80 MPa up to about 120 MPa. Preferably, the critical applied stress is from about 85 MPa. More preferably, the critical applied stress is from about 90 MPa. Most preferably, the critical applied stress is from about 95 MPa. Additionally, or alternatively, the critical applied stress is up to about 115 MPa. More preferably, the critical applied stress is from about 110 MPa. Most preferably, the critical applied stress is from about 105 MPa. In one example, the critical applied stress has a value of about 100 MPa + / - 10%.

[0023] In an embodiment, the fracture line has increasing depth from the open end toward the closed end.

[0024] In an embodiment, the fracture line has a depth of from about 10 % to about 65 % of a thickness of the cylindrical body.

[0025] In an embodiment, the fracture line has decreasing width from the open end toward the closed end.

[0026] In an embodiment, the fracture line tapers inward from the open end toward the closed end at an angle of from about 0.1° up to about 1°. Preferably, the angle is from about 0.12°. More preferably, from about 0.14°. Most preferably from about 0.15°. Alternatively, or additional the angle is up to about 0.9°. More preferably, up to about 0.8°. Most preferably, up to about 0.7°.

[0027] In an embodiment, the fracture line tapers outward from the closed end toward the open end at an angle of from about 0.1° up to about 1°. Preferably, the angle is from about 0.12°. More preferably, from about 0.14°. Most preferably from about 0.15°. Alternatively, or additional the angle is up to about 0.9°. More preferably, up to about 0.8°. Most preferably, up to about 0.7°.

[0028] In an embodiment, a width of the fracture line at its widest point, e.g., adjacent the open end is from about 0.30 mm to about 1 mm. Preferably, the width is from about 0.55 mm. More preferably, the width is from about 0.6 mm. Most preferably, the width is from about 0.65 mm. Additionally, or alternatively, the width is up to about 0.9 mm. More preferably, the width is up to about 0.85 mm. Even more preferably, the width is up to about 0.8 mm. Most preferably, the width is up to about 0.75 mm. In one example, the width is about 0.7 mm + / - 10%.

[0029] In an embodiment, a width of the fracture line at its narrowest point e.g., toward the closed end is from about 0.03 mm to about 0.15 mm. Preferably, the width is from about 0.04 mm. More preferably, the width is from about 0.05 mm. Most preferably, the width is from about 0.06 mm. Additionally, or alternatively, the width is up to about 0.12 mm. More preferably, the width is up to about 0.1 mm. Even more preferably, the width is up to about 0.09 mm. Most preferably, the width is up to about 0.8 mm. In one example, the width is about 0.077 mm + / - 10%.

[0030] In an embodiment, the fracture line comprises of an inner channel nested within an outer channel.

[0031] In an embodiment, the inner channel tapers inward from the open end toward the closed end at an angle of from about 0.1° up to about 0.25°. Preferably, the angle is from about 0.12.More preferably, from about 0.14°. Most preferably from about 0.15°. Alternatively, or additional the angle is up to about 0.23°. More preferably, up to about 0.21°. Most preferably, up to about 0.19°.

[0032] In an embodiment, the inner channel tapers outward from the closed end toward the open end at an angle of from about 0.1° up to about 0.25°. Preferably, the angle is from about 0.12. More preferably, from about 0.14°. Most preferably from about 0.15°. Alternatively, or additional the angle is up to about 0.23°. More preferably, up to about 0.21°. Most preferably, up to about 0.19°.

[0033] In an embodiment a width of the inner channel at its widest point, e.g., adjacent the open end is from about 0.1 mm to about 0.25 mm. Preferably, the width is from about 0.11 mm. More preferably, the width is from about 0.12 mm. Most preferably, the width is from about 0.14 mm. Additionally, or alternatively, the width is up to about 0.225 mm. More preferably, the width is up to about 0.2 mm. Most preferably, the width is up to about 0.175 mm. In one example, the width is about 0.145 mm + / - 10%.]

[0034] In an embodiment, a width of the inner channel at is narrowest point, e.g., toward the closed end is from about is from about 0.03 mm to about 0.095 mm. Preferably, the width is from about 0.04 mm. More preferably, the width is from about 0.05 mm. Most preferably, the width is from about 0.06 mm. Additionally, or alternatively, the width is up to about 0.09 mm. More preferably, the width is up to about 0.085 mm. Most preferably, the width is up to about 0.08 mm. In one example, the width is about 0.077 mm + / - 10%.]

[0035] In an embodiment, the outer channel tapers inward from the open end toward the closed end at an angle of from about 0.3° up to about 1°. Preferably, the angle is from about 0.4°. More preferably, from about 0.5°. Most preferably from about 0.6°. Alternatively, or additional the angle is up to about 0.9°. More preferably, up to about 0.8°. Most preferably, up to about 0.7°.

[0036] In an embodiment, the outer channel tapers outward from the closed end toward the open end at an angle of from about 0.3° up to about 1°. Preferably, the angle is from about 0.4°. More preferably, from about 0.5°. Most preferably from about 0.6°. Alternatively, or additional the angle is up to about 0.9°. More preferably, up to about 0.8°. Most preferably, up to about 0.7°.

[0037] In an embodiment, a width of the outer channel at its widest point, e.g., adjacent the open end is from about 0.5 mm to about 1 mm. Preferably, the width is from about 0.55 mm. More preferably, the width is from about 0.6 mm. Most preferably, the width is from about 0.65 mm. Additionally, or alternatively, the width is up to about 0.9 mm. More preferably, the width is up to about 0.85 mm. Even more preferably, the width is up to about 0.8 mm. Most preferably, the width is up to about 0.75 mm. In one example, the width is about 0.7 mm + / - 10%.

[0038] In an embodiment, a width of the outer channel at its narrowest point, e.g., toward the closed end is from about 0.03 mm to about 0.15 mm. Preferably, the width is from about 0.04 mm. More preferably, the width is from about 0.05 mm. Most preferably, the width is from about 0.06 mm. Additionally, or alternatively, the width is up to about 0.12 mm. More preferably, the width is up to about 0.1 mm. Even more preferably, the width is up to about 0.09 mm. Most preferably, the width is up to about 0.8 mm. In one example, the width is about 0.077 mm + / - 10%.]

[0039] In an embodiment, the fracture line is a score line.

[0040] In an embodiment, the fracture line is a score line on an inward facing surface of the cylindrical body.

[0041] In an embodiment, the fracture line extends from the open end at least partially toward the closed end. By way of example, the score line may extend a quarter the length of the body, or a third the length of the body, or up to half the length of the body.

[0042] In an embodiment, the bottle closure further comprises:an end cap portion defining the closed end;a skirt portion defining the open end, wherein the skirt portion comprises the fracture line.

[0043] Preferably, the fracture line is on an internal facing surface of the skirt portion.

[0044] In forms of the above embodiment, the skirt portion is attached to the end cap portion via a frangible connection. Preferably, the frangible connection is configured to break at a lower applied stress than the critical applied stress.

[0045] In embodiments in which the skirt portion is attached to the end cap portion via a frangible connection, it is preferred that the fracture line extends from the open end toward the frangible connection or to a location on the skirt portion adjacent the frangible connection. The frangible connection is generally in the form of a weakening, e.g., in the form of perforations, around a circumference of the bottle closure. It is preferred that the fracture line terminates about 0.4 to 1.0 mm below the frangible connection. This spacing between the end of the score line relative to the frangible connection is important since if this spacing is insufficient, it can compromise the integrity of the frangible connection, and / or interfere with thread and tuck under formation during rolling.

[0046] In embodiment, the skirt is configured to adopt an open position on or after propagation of the fracture from the open end towards the closed end. In one form, the skirt is configured to move to the open position. Preferably, the skirt is configured to move to the open position under internal spring force or tension or restoring force.

[0047] In an embodiment, the bottle closure is a roll-on pilfer-proof (ROPP) bottle closure.

[0048] In an embodiment, the bottle closure is a metal bottle closure, such as an aluminium bottle closure. Preferably, the aluminium bottle closure is coated, for example, with a powder coating and / or lacquer and / or varnish.

[0049] In an embodiment, the cylindrical body has an average wall thickness (which may, in relevant embodiments, be a wall thickness of the skirt portion) with a variation in wall thickness of 20% or less of the average wall thickness. Preferably, the variation in wall thickness is 15% or less. More preferably, the variation in wall thickness is 10% or less. Most preferably, the variation in wall thickness is 8% or less.

[0050] In an embodiment, the cylindrical body has an average wall thickness (which may, in relevant embodiments, be a wall thickness of the skirt portion) with a Is standard deviation of 2% of the average wall thickness or less as determined from measuring the average wall thickness of a plurality of such bottle closures (for example, at least 10 such bottle closures). Preferably, the Is standard deviation is 1.8% or less. Most preferably, the Is standard deviation is 1.6% or less.

[0051] In an embodiment, the cylindrical body has an average wall thickness (which may, in relevant embodiments, be a wall thickness of the skirt portion) with a 2c standard deviation of 4% of the average wall thickness or less as determined from measuring the average wall thickness of a plurality of such bottle closures (for example, at least 10 such bottle closures). Preferably, the 2c standard deviation is 3.8% or less. Most preferably, the 2c standard deviation is 3.5% or less.

[0052] In an embodiment, the cylindrical body has an average wall thickness (which may, in relevant embodiments, be a wall thickness of the skirt portion) of 0.240 mm or less. Preferably, the average wall thickness is 0.230 mm or less. More preferably, the average wall thickness is 0.225 mm or less. Most preferably, the average wall thickness is 0.220 mm or less. Additionally or alternatively, the average wall thickness is about 0.200 mm or greater. Preferably, the average wall thickness is about 0.205 mm or greater. Most preferably, the average wall thickness is about 0.210 mm or greater. In one example, the average wall thickness is from about 0.210 mm to about 0.225 mm.

[0053] In a second aspect of the invention, there is provided a method of forming a bottle closure, for example, according to the first aspect of the invention and / or embodiments thereof and / or forms thereof, from a metal blank, the method comprising:a multi-step drawing process comprising:a scoring draw step with a redraw ring and porno having a scoring blade mounted therein, wherein during the scoring draw step, the method comprises introducing the fracture line onto a wall of the cylindrical body with the porno having the scoring blade mounted therein; andan ironing draw step comprising ironing the wall of the cylindrical body and altering the morphology of the fracture line such that the fracture line has decreasing tensile strength from the open end toward the closed end.

[0054] In an embodiment:the clearance between an internal wall of the redraw ring used in the scoring draw step and an external wall of the porno used in the scoring draw step is about or less than a thickness of the wall of the cylindrical body; and / orthe clearance between an internal wall of a redraw ring used in the ironing draw step andan external wall of a pomo used in the ironing draw step is about or greater than a thickness of the wall of the cylindrical body.

[0055] In an embodiment, the clearance between the internal wall of the redraw ring and the external wall of the pomo is up to about 5 to 15% greater than the thickness of the wall of the cylindrical body.

[0056] In an embodiment, the scoring draw step is before or at the penultimate draw step and the ironing draw step is the final draw step of the multi-step draw process.

[0057] In an embodiment, the method further comprises an initial draw step prior to the scoring draw step comprising drawing the metal blank to form a first preform, and wherein the scoring draw step comprises drawing the first preform or a preform derived therefrom.

[0058] In an embodiment, the clearance between an internal wall of the redraw ring used in the initial draw step and an external wall of the pomo used in the initial draw step is about or less than a thickness of the wall of the cylindrical body.

[0059] In an embodiment, the ironing draw step flattens the fracture line, such that:the fracture line has increasing depth from the open end toward the closed end; and / or has decreasing width from the open end toward the closed end.

[0060] In an embodiment, the scoring draw step introduces a fracture line comprising an inner channel nested within an outer channel.

[0061] In an embodiment, the fracture line is a score line.

[0062] In a third aspect of the invention, there is provided a method of forming a bottle closure, for example, according to the first aspect of the invention and / or embodiments thereof and / or forms thereof, comprising:a first draw step of drawing a metal blank with a first redraw-ring and a first pomo to form a first preform;a second draw step of drawing the first preform or a preform derived therefrom with a second redraw-ring and a second pomo having a blade mounted therein to form a second preform having the fracture line therein; anda third step of drawing the second preform with a third redraw-ring and a third pomo to iron a wall of the second preform and alter the morphology of the fracture line to form the bottle closure with the fracture line having decreasing tensile strength from the open end toward the closed end.

[0063] In an embodiment of the second or third aspects, the metal blank is a coated metal blank, for example, with a powder coating and / or lacquer and / or varnish.

[0064] In an embodiment:the first redraw-ring and the first pomo are sized to provide a clearance therebetween that is about or less than a wall thickness of the metal blank; and / orthe second redraw-ring and the second pomo are sized to provide a clearance therebetween that is about or less than a wall thickness of the first preform or preform derived therefrom; and / orthe third redraw-ring and the third pomo are sized to provide a clearance therebetween that is about or greater than a wall thickness of the second preform.

[0065] In a fourth aspect of the invention, there is provided a redraw-ring for use in a drawing method to form a bottle closure from a metal blank or preform, the redraw-ring comprising: a body having a circular aperture bounded by a peripheral wall through which the metal blank or preform can be extruded;wherein the peripheral wall comprises:a leading edge which bounds the circular aperture and which has an convex surface that is inwardly curved toward the circular aperture;a straight portion which bounds the circular aperture such that the circular aperture has constant diameter over a length of the straight portion; anda relief portion which bounds the circular aperture such that the circular aperture has increasing diameter in a direction away from the straight portion.

[0066] In an embodiment:the inwardly curved surface has a radial curvature, and the radial curvature has a radius of curvature of about 0.5 to about 5 mm; ora multi-radii convex surface, wherein each radius in the multi-radii convex surface has a radius of curvature of from about 0.1 mm to about 5mm; and / orthe straight portion extends from the curved surface of the leading edge, and wherein the length of the straight portion is about 0.1 mm to about 5 mm; and / orthe relief portion extends from the straight portion, and wherein the relief portion is angled away from the straight portion at an angle of from about 2° up to about 45°; orthe relief portion extends from the straight portion in the form of a concave recess.

[0067] In an embodiment, the radius of curvature is from about 0.6 mm, preferably from about 0.7 mm, most preferably from about 0.8 mm. Alternatively, or additionally, the radius of curvature is up to about 1.4 mm, and most preferably about 1.3 mm.

[0068] In an embodiment, the length of the straight portion is from about 0.1 mm, preferably from about 0.4 mm, most preferably from about 0.3 mm. Alternatively, or additionally, the radius of curvature is up to about 5 mm, more preferably about 4 mm, and most preferably about 3.5 mm.

[0069] In an embodiment, the relief portion is angled away from the straight portion at the angle of from about 2°, most preferably 5°. Alternatively, or additionally, the relief portion is angled away from the straight portion at the angle of up to about 45°, preferably 8°, most preferably 6°. In one example the relief portion is angled away from the straight portion at the angle of from about 5° + / - 10%.

[0070] In an embodiment, the redraw ring further comprises a second straight portion which bounds the circular aperture such that the circular aperture has constant diameter over a length of the further straight portion extending from the relief portion.

[0071] In a fifth aspect of the invention, there is provided a porno for use in a drawing method to form a bottle closure from a metal blank, the porno having a cylindrical body comprising: a shaft having a porno head located at one end thereof;a detachable sleeve mountable to the shaft, the detachable sleeve comprising a first end configured to be seated on the porno head, a second end, and an open channel extending from the first end to the second end,wherein the open channel has an opening that runs at least a portion of a length of the detachable sleeve and terminates at an open end at the second end;wherein the channel is configured to hold an insert therein with a portion of the insert extending outward of the channel; anda cover mountable to the shaft and configured to abut the second end of the sleeve to retain the sleeve in position on the shaft and cover the open end.

[0072] In an embodiment, the insert is a blade, and the porno further comprises the blade, the blade being locatable within the channel, and wherein the portion of the insert extending outward of the channel is a cutting edge of the blade.

[0073] It is preferred that the blade comprises a cutting portion and a spacer portion, the spacer portion being located proximally to the porno head relative to the cutting portion. In this way, when forming the bottle closure e.g., according to the second or third aspects of the invention, the fracture line does not extend the full length of the bottle closure toward the closed end. In particular, the score line will only be present on the portion intended to form the skirt portion of the bottle closure, beneath the intended location of any frangible connection, and not present on the portion intended to form the end cap portion. This spacing is important since if this spacing is insufficient, it can compromise the integrity of the frangible connection, and / or interfere with thread and tuck under of the end cap portion.

[0074] In one form of the above embodiment, the cutting edge is in the form of a wedge having an angle of from about 15° to about 120°. Preferably from about 30°. More preferably, from about 40°. Most preferably from about 50°. Additionally or alternative, the angle is up to about 100°. More preferably up to about 90°. Even more preferably up to about 80°. Most preferably up to about 70°. In one example, the angle is about 60° + / - 10%.

[0075] In an embodiment, the retaining portions are inwardly curved wall portions of the channel.

[0076] In an embodiment, the porno further comprises one or more removable retaining elements locatable within the channel to retain the blade within the channel.

[0077] In an embodiment, the base has a contact surface, and the perimeter of the contact surface is in the form of a convex curvature in a direction away from the contact surface.

[0078] In one form of the above embodiment, the convex curvature is a radial curvature with a radius of from about 0.5 mm to about 4 mm.

[0079] In a sixth aspect of the invention there is provided the use of an redraw-ring of the fifth aspect of the invention and / or embodiments thereof and / or forms thereof, and / or the porno of the sixth aspect of the invention and / or embodiments thereof and / or forms thereof, to form a bottle closure according to the first aspect of the invention and / or embodiments thereof and / or forms thereof, or in a method according to the second or third aspects of the invention and / or embodiments thereof and / or forms thereof.

[0080] Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and / or combined with other pieces of prior art by a skilled person in the art.

[0081] As used herein, except where the context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers or steps.Brief Description of Drawings

[0082] Further aspects of the present invention and further embodiments of the aspects described in the preceding paragraphs will become apparent from the following description, given by way of example and with reference to the accompanying drawings.

[0083] Figure 1 is an illustration of a wine bottle closure according to the prior art.

[0084] Figure 2 is an illustration of the wine bottle closure of Figure 1 after application to a wine bottle.

[0085] Figure 3A is an illustration of a wine bottle closure according to one aspect of the invention applied to a wine bottle with the end cap removed.

[0086] Figure 3B is an illustration showing the skirt portion of the wine bottle closure of Figure 3A splitting on application of a force thereto.

[0087] Figure 4 is a cross-sectional view of the redraw-ring for use in a first draw step in accordance with one embodiment of the invention.

[0088] Figure 5 is a close-up view of Section B of the redraw-ring used in a first draw step of Figure 4.

[0089] Figure 6 is a cross-sectional view of the porno for use in a first draw step in accordance with one embodiment of the invention.

[0090] Figure 7 is a cross-sectional view of the redraw-ring for use in a second draw step in accordance with one embodiment of the invention.

[0091] Figure 8 is a close-up view of Section C of the redraw-ring for use in a second draw of Figure 7.

[0092] Figure 9 is a cross-sectional view of the porno for use in a second scoring draw step in accordance with one embodiment of the invention

[0093] Figure 10 is a cross-sectional view of blade retaining sleeve along line B-B of the pommel of Figure 9.

[0094] Figure 11 is a close-up view of section D illustrating the blade arrangement of the blade retaining sleeve of Figure 10.

[0095] Figure 12 are images providing a non-limiting illustration of potential cutting blades for use in the devices and methods of the invention.

[0096] Figure 13 is a cross-sectional view of the redraw-ring for use in a third draw step in accordance with one embodiment of the invention.

[0097] Figure 14 is a close-up view of Section B of the redraw-ring for use in a third draw step of Figure 13.

[0098] Figure 15 is a cross-sectional view of the porno for use in a third draw step in accordance with one embodiment of the invention.

[0099] Figure 16A and 16B are annotated photographs showing a score line located on an internal facing surface of a bottle closure formed according to the method described above after (a) the scoring during second draw, and (b) the final ironing draw.

[0100] Figure 17 is a graph plotting ultimate tensile strength (UTS) against distance for (i) a closure without introducing score line and (ii) a closure formed including a scoring draw step.

[0101] Figure 18 is a roughness surface plot showing the variation in score line depth from the base of the skirt / open bottom end to the closed end of a closure according to one embodiment of the invention.

[0102] Figure 19 is a plot showing the width and depth of the score line from the base of the skirt / open bottom end to the closed end of a closure according to one embodiment of the invention.

[0103] Figure 20 is a perspective view of a cutting blade in accordance with an embodiment of the invention.Description of Embodiments

[0104] The invention broadly relates to methods and tooling for producing a bottle closure, and a bottle closure produced using such methods and apparatus. The inventor has devised a bottle closure, such as a roll-on pilfer-proof (ROPP) closure, that can easily be removed from a bottle to permit separate disposal of the bottle closure and the bottle. This is advantageous, for example, from a recycling perspective where the bottle closure and bottle are formed from different materials (e.g., aluminium and glass respectively).

[0105] As discussed in the background section, conventional ROPP closures include a tamper-evident band, in the form of a skirt, that remains attached to the bottle neck after initial opening. In many cases, the skirt is difficult or impossible to remove without tools, creating an inconvenience for consumers and industrial users who require full separation for recycling or quality testing.

[0106] European patent publication EP 0047854 which published 24 March 1982 discloses a screw closure including a vertical weakening line on an inside surface of the screw closure forthe purpose of facilitating separation of the skirt portion of the screw closure from a bottle. In particular, EP 0047854 contemplates that a user will return the used bottle with skirt located around a neck thereof, and that the skirt will be manually or mechanically removed via machine or tool. However, the screw cap of EP 0047854 is not suitable for commercial-scale production of closures with consistent and reliable tool-free removal. The score’s geometry and depth are not defined, nor is the wall thickness controlled, making uniform separation unpredictable. Additionally, maintaining circularity and structural consistency when applying scoring as described in EP 0047854 is not feasible in a commercial-scale production process.

[0107] Notably, the screw closure disclosed in EP 0047854 does not appear to have been successfully commercialised. The inventors believe that failure to commercialise this product may be for a plurality of reasons including issues of aesthetics (with the weakening line being at least partially visible on the exterior surface of the skirt) and / or high failure rate (whether due to issues of premature fracturing of the skirt during high speed automated affixation of the screw closure to a bottle, or jamming of the capping machinery due to warping circularity of the screw closure due to the method of forming the screw closure with vertical weakening line).

[0108] The inventors have devised a process for producing a bottle closure with a fracture line to permit easy and consistent, tool -free skirt removal by a user that avoids the issues of EP 0047854 and which exhibits significant advantages.

[0109] The bottle closure comprises cap portion and a skirt portion. In a preferred form of the skirt portion comprises a fracture line configured to propagate a fracture in the cylindrical body to split the bottle closure from a first end of the skirt portion distal from the end cap portion toward a second end of the skirt portion proximal to the end cap. In this way, the bottle closure can be easily removed from a bottle.

[0110] Advantageously, the bottle closure of the invention provides a toolless means for removing the skirt portion from the bottle to permit a user to easily dispose of the bottle for recycling. Furthermore, no changes to the bottle itself are necessary to accommodate the bottle closure of the invention, e.g. the bottle closure can be applied to existing bottles.

[0111] The skilled person will appreciate that a variety of means may be employed as the fracture line. For example, the fracture line may be in the form of a structural weakness or a stress concentrator on the bottle closure, a non-limiting disclosure of which includes an etchedchannel, or a series of holes or keyways and the like. Each of these can be introduced during the method of formation, and typically in prior to a final redraw step to form the bottle closure.

[0112] In use, the bottle closure is applied to a bottle to cover a bottle mouth. To open the bottle, a user un-twists the end cap 202 portion which causes the frangible portion to break and allows continued turning of the cap portion to unscrew the cap portion from the bottle, this is exactly the same mechanic as any standard ROPP closure. With the end cap removed; the user is able to access the internal contents of the bottle via the mouth of the bottle. The cap portion can be screwed back onto the bottle if desired, e.g. if there is wine or other liquid left in the bottle, retaining all the functionalities and features of a standard ROPP closure.

[0113] When a user plans to dispose of the bottle, e.g. when the bottle is empty, the user is able to grip the skirt portion around the neck of the bottle and apply a downward force on the skirt portion (e.g. away from the mouth of the bottle) to slide the skirt portion along the neck and over at least a portion of the shoulder of the bottle (e.g. a flared neck portion). As the skirt portion rides over at least a portion of the shoulder of the bottle, the skirt portion is subjected to an outward force and the fracture line causes a crack to propagate from the lower end of the skirt (e.g. the skirt portion adjacent the shoulder of the bottle / distal from the mouth of the bottle) toward the upper end of the skirt (e.g. the skirt portion proximal to the mouth of the bottle).

[0114] Once the crack has propagated and split the skirt portion from the lower end of the skirt portion to the upper end, the skirt portion can then be easily removed by a user from the bottle.

[0115] It is preferred that fracture initiator is configured to break at a higher applied stress than that required to break the frangible portion. This is to reduce the likelihood that the skirt will inadvertently split on opening the bottle.

[0116] A bottle closure according to one or more embodiments of the invention is illustrated in Figures 3A and 3B.

[0117] Figures 3A and 3B provide an illustration of a user removing the skirt portion 306 of a wine bottle closure 308 from a bottle in which a cap end portion 309 has already been removed. In particular, with reference to Figure 3A, a user’s hand grips the body of wine bottle 302 whilst the other user’s other hand grips skirt portion 306 of wine bottle closure 308 around a neck 310 of wine bottle 302. Downward arrow 312 illustrates the direction that the user moves skirtportion 306 to effect removal of skirt portion 306. In this embodiment, skirt portion 306 includes a fracture line in the form of score line 313 (illustrated as a dashed line, noting that this is not externally visible) on an internal surface of skirt portion 306. Score line 314 is essentially a channel that is etched into internal surface of skirt portion 306. Although only a single score line is illustrated, the skilled person will appreciate that multiple score lines may be used. Score line 313 runs from the lower edge 314 of skirt portion 306 at least partially toward the upper edge 315 of skirt portion 306, and preferably the full length of skirt portion 306. However, the skilled person will appreciate that score line 313 may run only a portion of the distance between the lower edge and the upper edge of skirt portion 306.

[0118] Advantageously, score line 306 has decreasing tensile strength from the lower edge 314 of skirt portion 306 towards the upper edge 315 of skirt portion 306. This may be achieved in a number of ways, for example, by increasing the depth of score line 313 from lower edge 314 of skirt portion 306 to upper edge 315 of skirt portion 306 and / or altering the width of score line 313 from lower edge 314 of skirt portion 306 to upper edge 315 of skirt portion 306, such by narrowing the width of score line 313 to act as a stress concentrator. In this way, the user must provide an initial force to overcome the tensile strength at lower edge 314 of skirt portion 306 to initiate the fracture, and then, due to the decreasing tensile strength of score line 313, the fracture essentially self-propagates or propagates under lower applied stress along score line 313.

[0119] As best shown in Figure 3B, skirt portion 306 is moved downward over shoulder of wine bottle 302, the skirt portion is subjected to an initial outward force 316 which overcomes an initial ultimate tensile strength of score line 313 causing skirt portion 306 to initially fracture at lower edge 314 of skirt portion 306 at score line 313. The fracture then essentially selfpropagates or propagates under lower applied stress along score line 313 due to the decreasing tensile strength of score line 313 toward the upper edge 315 of skirt portion 306. If the fracture does not self-propagate the entire length of score line 313, a user can provide an additional force (less than that required to cause the initial fracture) to complete the fracture. The fracture splits skirt portion 306 which allows skirt portion 306 to be unfurled and separated from wine bottle 302. The decreasing tensile strength offers a number of advantages, such as, permitting easier removal of the skirt and reduction in likelihood of user injury.

[0120] The inventors have found that the score line should generally be in the form of a channel etched into the internal surface of the skirt with increasing depth from the base of the skirt portion toward the top of the skirt portion, typically at a value in the range of from about 1 / 4 to about 1 / 2 the thickness of the skirt wall portion. Preferably the depth of the channel is about 2 / 5 the thickness of the skirt portion. If the channel depth is too shallow, then the increased resistance to fracture propagation may make it difficult for the fracture to propagate and split the skirt whereas if the channel depth is too deep then the skirt may be split unintentionally. In view of the foregoing, it is important that the bottle closure skirt has a uniform wall thickness. If the bottle closure includes portions which are too thick, then this can impede or prevent fracture or propagation. On the other hand, if the bottle closure includes portions which are too thin, then this could lead to the bottle closure inadvertently fracturing, e.g., when jostled such as during transport.

[0121] Likewise, the length of the score line should extend at least from the open end of the cap defined by the skirt toward the opposite end of the skirt being careful of not interfere with the frangible bridge region / tamper evident band.

[0122] The method generally includes forming the fracture initiator into the metal blank or preform prior to a final step of deep drawing the blank or preform to form the bottle closure.

[0123] The method of forming the bottle closure of the invention will now be generally described below with relation to the standard industry approach to forming a standard bottle closure (without a score line).

[0124] Broadly, the standard approach to forming a bottle closure includes taking a metal blank (e.g., aluminium), typically in the form of a 91 to 93 mm (ideally 92.6 mm) diameter circular sheet with thickness of 0.225 mm in the case of a wine bottle closure, and then forming this into a bottle closure through a sequence of redraw processes using a redraw-ring and a pommel.

[0125] The redraw-ring is a circular aperture with circular cross-section over which the metal blank is placed before being stamped with the porno to redraw the metal blank into the shape of a bottle closure. During the redraw process, the redraw-ring and porno head are moved relative to one another such that the porno head projects through the circular aperture thus forming the metal blank to form the bottle closure.

[0126] In a typical bottle closure forming process three such redrawing steps are used, whereby each redraw-ring in the process has successively smaller circular apertures with the final extrusion step forming the bottle closure. The pornos used in each successive step likewise decrease in diameter with the corresponding redraw-ring to maintain the same effective clearance between the internal walls of the circular aperture and the external walls of the porno.

[0127] In more detail, the first redraw step forms the metal blank into a first bottle closure preform having a first internal diameter and first height, for example an internal diameter of 51.54 mm and a height of 28 mm; the second extrusion step forms the first bottle closure preform into a second bottle closure preform having a second internal diameter and a second height, for example an internal diameter of 38.54 mm and a height of 45 mm; the third extrusion step forms the second bottle closure preform (or a derivative thereof if there are additional intervening extrusion steps) into the bottle closure which has a standard internal diameter of 29.35 mm and a height of 60.1 mm. The skilled person will appreciate that these sizes are indicative sizes and that the actual size may vary depending on the process steps and intended end use. The skilled person will also appreciate that additional intervening extrusion steps may be used.

[0128] During the standard redraw process the clearance between the internal walls of the circular aperture of the redraw-ring and the external wall of the porno is about 0.32 mm. This clearance is important for reducing friction on the metal blank and preforms during the redraw process which would otherwise damage any lacquer and / or varnish and / or coatings that are on the metal blank or perform.

[0129] With reference to the screw closure discussed in EP 0047854, this discloses a process in which a score line is introduced into the closure on the final draw step. In contrast with this approach, the inventors have devised a three-step re-draw process which introduces a score line into the closure on the second draw step. The skilled person will appreciate that processes including more than three draw steps may be used, in which case, the score line may be introduced on an intermediate draw step, such as the penultimate draw step. The inventors have surprisingly found that this approach provides a number of advantages over prior processes, and in particular, those of EP 0047854 as will be described below.

[0130] Broadly, the method of the invention relates to a three-step re-draw process. The method is generally described below for forming an ROPP closure suitable for application to a standard sized wine bottle, but may be adapted for bottles of different sizes.

[0131] The draw-steps of the invention each make use of a specially designed redraw-ring and porno as generally illustrated in Figures 4 to 15.

[0132] One descriptive embodiment of a three-step draw process is described below.

[0133] The first draw step comprises taking a flat circular aluminium blank with a thickness typically of about 0.225 mm and diameter of 88.5 mm and subjecting this to a draw step over a draw height of about 33 mm to form a first phase of closure preform using an redraw-ring and porno as described below. Typically, the aluminium blank includes a coating, such as a lacquer or varnish, with a thickness of about 0.010 mm. In such cases, the total thickness of the coated aluminium blank is about 0.235 mm.

[0134] Figure 4 is a cross-sectional view of the redraw-ring. Figure 5 is a close-up view of Section B of Figure 4. Figure 6 is a cross-sectional view of the porno.

[0135] The redraw-ring 400 comprises a circular aperture 402 with internal diameter ID bounded by a peripheral wall 404 over a height thereof and through which the metal blank or preform can be redraw using the corresponding porno Figure 6. Peripheral wall 404 has a convex surface 406 that curves inwardly toward circular aperture 402. The convex surface may be a mono-radial or a multi / compound radii surface. Following from convex surface 406 is a straight portion 408 of length L which bounds circular aperture 402 such that circular aperture 402 has constant diameter over a length of straight portion 408. Following from straight portion 408 is a relief portion 410 which bounds circular aperture 402 such that circular aperture 402 has increasing diameter in a direction away from straight portion 408. Following relief portion 410 is another straight portion 412 which extends a remainder of the height of peripheral wall 404 of extrusion die 400.

[0136] Porno 600 generally comprises a porno head 602 attached at one end of a porno shaft 604. Porno shaft 604 includes mounting structure 606 to permit porno 600 to be mounted to a press (not illustrated). Porno 600 includes a slight taper, increasing in diameter from base 608 totop 610. Pomo 600 also includes a convex perimeter 612 around the flat base 608. This combination of features has been found to improve the drawing process.

[0137] The inventors have found that the combination of an redraw-ring having an initial convex curvature (which may be a mono-radial or a multi / compound radii surface), followed by a straight portion, and relief in combination with a pomo sized to provide a clearance with redraw-ring that is about the thickness of the blank is useful to provide an ‘ironing’ effect during the draw process which provides a preform and / or closure with highly consistent wall thickness. This contrasts with the conventional process which utilises a standard radial ring and punch with a clearance of about 0.32 mm, being substantially greater than the standard thickness of 0.225 mm for the aluminium blank thickness, 0.235 mm in the case of a coated aluminium blank.

[0138] By way of example, the inventors have compared the thickness of closures prepared in accordance with the method of the invention from the open end of the closure towards the closed end of the closure with that of standard commercially available closures. The results for a plurality of such closures are summarized in Table 1 below:Table 1: Comparison of wall thickness of (i) closures formed according to the method of the invention, and (ii) standard commercially available closures

[0139] The closures formed according to the invention have an average thickness of about 0.213 mm, a maximum variation in average thickness of 0.013 mm (about 6.1% of the average thickness), and standard deviations in each thickness measurement of o = 0.003 mm (about 1.4% of the average thickness) and 2c = 0.007 mm (about 3.3% of the average thickness).

[0140] The standard commercially available closures have an average thickness of about 0.251 mm, a maximum variation in average thickness of 0.074 mm (about 29.5% of the average thickness), and standard deviations in each thickness measurement of o = 0.006 mm (about 2.4% of the average thickness) and 2c = 0.011 mm (about 4.4% of the average thickness).

[0141] The effect of the tight clearance is that the metal blank or preform is effectively held in a friction fit arrangement between the internal walls of the aperture of the redraw-ring and the external walls of the porno. This is generally considered to be undesirable since high levels of friction can generate heat and damage the metal blank or preform, particularly if that metal blank or preform includes some form of coating such as a lacquer or varnish as is the case when forming bottle closures. However, the inventors have found that providing a redraw-ring that comprises a leading convex edge, followed by a straight region, followed by a relief is effective for reducing the deleterious friction effects whilst also taking advantage of a beneficial ironing effect provided by the friction.

[0142] The inventors have found that the inwardly curved surface, particularly in the form of a radial surface with a radius of curvature of from about 0.5 mm to about 5 mm or a multi-radii convex surface reduces friction effects on the metal blank or preform as it is extruded through the aperture.

[0143] The inventors have found that the straight portion should have a length of from about 0.1 mm up to about 5 mm. This length is sufficient to impart an ironing effect onto the metal blank or preform as it is extruded through the aperture whilst avoiding excessive friction which could damage the extruded product.

[0144] The inventors have found that the relief portion is important for continuing to shape the metal blank or preform whilst minimizing friction and damage to any coating thereon. The relief portion is preferably angled away from the straight portion at an angle of from about 2 up to about 45 degrees.

[0145] The inventors have discovered that this combination of features provides an ironing effect which results in a bottle closure having highly consistent wall thickness. One advantage of this greater uniformity of thickness is that less metal is required to produce the bottle closure. This enables the use of a smaller metal blank to produce the bottle closure which reduces the cost of production. In particular, the inventors have found that a standard sized wine bottleclosure can be formed from a blank having a diameter of 88 mm or less rather than the standard 90-95 mm diameter blanks that are presently used.

[0146] Redraw-ring 400 has a height of 34.54 mm, an upper internal diameter 408 of 52.19 mm as measured at the straight portion 408, and a lower internal diameter of 52.5 mm as measured at the base. Convex surface 406 is a radial surface with a radius of 1.2 mm. Straight portion 408 has a length of 0.6 mm. Base 608 of porno 600 has a diameter of 51.71 mm and convex perimeter 612 with radiused edge of 2.5 mm, and a top 610 diameter of 51.76 mm. This combination of redraw-ring and porno provides a minimum clearance of 0.215 to 0.240 mm.

[0147] The first draw step provides a first preform having internal height of about 26 mm and internal radius of about 51.54 mm.

[0148] The second draw step takes the first preform and subjects this to a second draw over a draw height of about 44 mm and internal radius of about 38.54 using a redraw-ring and porno as will be further described below. In particular, the porno used in this step includes a blade containing cutting sleeve to introduce a score line during the drawing process to form a second preform.

[0149] Figure 7 is a cross-sectional view of the second redraw-ring. Figure 8 is a close-up view of Section C of Figure 7.

[0150] Redraw-ring 700 comprises a circular aperture 702 with internal diameter ID bounded by a peripheral wall 704 over a height thereof and through which the first preform can be extruded. Peripheral wall 704 has a convex surface 706 that curves inwardly toward circular aperture 702. Following from convex surface 706 is a straight portion 708 of length L which bounds circular aperture 702 such that circular aperture 702 has constant diameter over a length of straight portion 708. Following from straight portion 708 is a relief portion 710 which bounds circular aperture 702 such that circular aperture 702 has increasing diameter in a direction away from straight portion 708. Following relief portion 710 is another straight portion 712 which extends a remainder of the height of peripheral wall 704 of redraw-ring 700.

[0151] Figures 9, 10, and 11 illustrate a porno 900 that further comprises a blade retaining sleeve 901 for introducing a scoreline onto an internal surface of the closure during an intermediate draw step, e.g., the penultimate draw step, or the second draw step in the case of athree-step drawing process. Pomo 900 comprises a pomo head 902 attached at one end of a pomo shaft 904. Pomo shaft 904. Pomo shaft 904 is also be configured to permit blade retaining sleeve 901 to be mounted to the pomo adjacent pomo head 902. A cutting blade 907 is mounted with blade retaining sleeve 901. Pomo 900 includes a slight taper, increasing in diameter from base 914 to top 916. Pomo 900 also includes a convex perimeter 915 around base 914.

[0152] With reference to Figure 10 which provides a cross-sectional view of blade retaining sleeve 901 along line B-B of Figure 9, blade retaining sleeve 901 has a first end 908 configured to be seated against a rear surface of pomo head 902, a second end 910, and a channel 912 with open ends extending from first end 908 to second end 910. Channel 912 is configured to hold a blade 907 therein (illustrated). Pomo 900 further comprises a cutting ring 916 that is mountable to shaft 904 against second end 910 of blade retaining sleeve 901 to secure blade retaining sleeve W01 and cover an open end of channel 912 to thereby fixedly retain blade 907 within the channel.

[0153] Blade 907 may be retained directly within channel 912 via complementary structures of channel 912, e.g., channel 912 is shaped directly to accommodate and hold blade 907, or via blade retaining insert members which are locatable within channel 912 to secure blade 907 within channel 912.

[0154] Figure 11 is a close-up view of section D of Figure 10 and illustrates channel 912 which retain the blade. The use of such insert is advantageous since it controls projection of blade 907 from blade retaining sleeve 901, thus ensuring highly consistent score-lines during production. The blade rise 1004 is schematically illustrated. Also shown is that blade 907 has a three rounded cutting edges 1006, 1007, 1008. This arrangement also allows blade holder 901 and blade 907 to be quickly and accurately assembled together or disassembled, and blade 907 can be rotated or replaced once worn.

[0155] The cutting blade generally comprises a longitudinal body preferably having multiple cutting edges. This enables the cutting blade to be rotated to employ a new cutting edge when a current cutting edge becomes dulled, thus extending the overall useful life of the cutting blade. The skilled person will appreciate that a variety of different shaped cutting blades may be employed, for example triangular, square, star-shaped, tear drop shaped, diamond shaped, pentagonal, hexagonal, heptagonal, octagonal and the like. Figure 12 provides a non-limitingillustration of different cutting blade shapes. Figure 12 generally illustrates that the cutting blades have a rounded cutting edge, such as a radiused edge with radii of from about 0.02 mm to about 0.15 mm with blade angles of 15° to 120°. Typically, the blade is sized such that the cutting edge extends about 0.1 mm. Returning to Figures 9, 10, and 11, in this particular embodiment, cutting blade 907 has an equilateral triangular cross-section with three cutting edges 1006, 1007, 1008 having blade angles of about 60° and cutting edge radii of 0.1 mm.

[0156] Figure 20 is an illustration of a cutting blade 2000 in accordance with another embodiment. Cutting blade 2000 has an equilateral triangular cross-section with a spacer portion 2002 and a cutting portion 2004 having three cutting edges, of which two are shown 2006, 2008 with blade angles of about 60°. In use, the spacer portion is located proximally to the porno head relative to the cutting portion. In this way, when forming the bottle closure during the scoring draw, the fracture line does not extend the full length of the bottle closure toward the closed end. In particular, the score line will only be scored into the portion intended to form the skirt of the bottle closure and beneath the intended location of any frangible connection. That is, the scoreline will not be formed into the region of the cap near the closed end which is intended to form the end cap portion. This spacing is important since if this spacing is insufficient, it can compromise the integrity of the frangible connection, and / or interfere with thread and tuck under of the end cap portion.

[0157] Redraw-ring 700 has a height of 14 mm, an upper internal diameter 708 of 39 mm as measured at straight portion 708 of 1.97 mm length. Convex surface 706 is a radial surface with a radius of 0.9 mm. Base 914 of porno 900 has a diameter of 38.56 mm and convex perimeter 915 with radiused edge of 2 mm, and a top 916 diameter of 38.58 mm. This combination of redraw-ring and porno provides a minimum clearance of 0.21 to 0.22 mm which is less than the thickness of 0.225 mm for the aluminium blank or the 0.235 mm thickness in the case of a coated aluminium blank.

[0158] Cutting blade 907 is mounted within sleeve 901 of porno 900 such that it has a blade rise 1004 of 0.1 mm (i.e., projects 0.1 mm from the surface of porno 901). Accordingly, a tight clearance between the redraw-ring and the porno is important to ensure that a consistent score line can be imparted to an internal surface of the preform during the second draw step.

[0159] The second draw step provides a first preform having internal height of about 44 mm and internal radius of about 38.54 mm.

[0160] One issue with the introduction of the score line during a drawing process is that, during scoring, the blade applies an outward force onto preform / closure which deforms the preform / closure such that it has a slightly oval shape, that is, the preform / closure is no longer cylindrical. This is a particular issue for processes in which the score line is introduced on the final draw step. Closures are generally applied in high-speed manufacturing processes, and any deviation in shape can lead to misapplication of the closure and / or jamming of the machinery applying the closures. In the case where such closures are successfully applied to bottles, the deformation can result in the closure providing an ineffective seal leading to the contents of the bottle being exposed to air and spoiling.

[0161] The third draw step takes the second preform and subjects this to a third draw over a draw height of about 59.6 mm using a third redraw-ring and porno as generally described below to form the bottle closure. The third draw step provides an ironing effect which is important for addressing the deformation from the second scoring draw.

[0162] Figure 13 is a cross-sectional view of the redraw-ring. Figure 14 is a close-up view of Section B of Figure 13. Figure 15 is a cross-sectional view of the porno.

[0163] Redraw-ring 1300 comprises a circular aperture 1302 with internal diameter ID bounded by a peripheral wall 1304 over a height thereof and through which the second preform can be extruded. Peripheral wall 1304 has a convex surface 1306 that curves inwardly toward circular aperture 1302. Following from convex surface 1306 is a straight portion 1308 of length L which bounds circular aperture 1302 such that circular aperture 1302 has constant diameter over a length of straight portion 1308. Following from straight portion 1308 is a relief portion 1310 which bounds circular aperture 1302 such that circular aperture 1302 has increasing diameter in a direction away from straight portion 1308. In this case relief portion 1310 is in the form of a concave recess. Following relief portion 1310 is another straight portion 1312 which extends a remainder of the height of peripheral wall 1304 of redraw-ring 1300.

[0164] Porno 1500 generally comprises a porno head 1502 attached at one end of a porno shaft 1504. Porno 1500 includes a slight taper, increasing in diameter from base 1508 to top 1510. Porno 1500 also includes a convex perimeter 1512 around base 1508.

[0165] Redraw-ring 1300 has a height of 14 mm, an upper internal diameter of 29.9 mm as measured at straight portion 1308, and a lower internal diameter of 29.9 mm as measured at the base. Convex surface 1306 is a radial surface with a radius of 1.1 mm. Straight portion 1308 has a length of 1.66 mm. Base 1508 of porno 1500 has a diameter of 29.29 mm and convex perimeter 1512 with radiused edge of 1.2 mm, and a top 1510 diameter of 29.38 mm. This combination of redraw-ring and porno provides a minimum clearance of 0.26 mm which is greater than the thickness of 0.225 mm for the aluminium blank (noting that the thickness of 0.225 only accounts for the base aluminium blank and does not factor in the thickness of any coating applied thereto).

[0166] The third draw step provides a bottle closure having internal height of about 59.6 mm and internal radius of about 29.4 mm.

[0167] The inventors have found that a subsequent draw step after the scoring draw is important for ironing the closure to ameliorate the deformation that occurs during the scoring draw. The resultant closure is essentially circular in cross-section. This subsequent draw step is also important for affecting the morphology of the score line. In particular, during the subsequent draw step, the second preform is stretched under tension and ironed which causes elongation and flattening of the second preform, which likewise elongates and flattens the score line. However, the stretching and flattening is non-uniform with greater stretching and flattening of the closure occurring toward the closed end. The effect of this is that the score line has greater tensile strength at the open end toward the base the skirt portion with decreasing tensile strength toward the closed end of the closure.

[0168] Figures 16 to 19 report the results of a bottle closure formed according to the method generally described above.

[0169] Figure 16A and 16B are annotated photographs showing a score line located on an internal facing surface of a bottle closure formed according to the method described above after (a) the scoring draw, and (b) the final ironing draw.

[0170] After the scoring draw, the score line is essentially straight and parallel from the closed end (left) to the open end (right). In particular, the scoreline consists of a narrow inner channel which is formed by the rounded edge tip of the cutting blade, and a wide second outer channel formed by the lateral sides of the cutting blade. The narrow inner channel is essentially parallel0.00° ± 0.01°having an average thickness of about 0.10 mm ±0.01 mm. The wide second channel is widened slightly at a widening angle of 0.02° ±0.02° from an initial width of about 0.32 mm ± 0.1 mm.

[0171] After the final ironing draw, it is apparent that the score line becomes tapered with the width of the score line decreasing from the open end toward the closed end of the closure. After the third ironing draw, the inner channel has a width of about 0.15 mm adjacent the open end / base of the skirt and a width of about 0.08 mm adjacent the closed end of the closure, and a widening angle of about 0.16° ±0.01°. The outer channel has a width of about 0.69 mm adjacent the open end / base of the skirt and a width of about 0.39 mm adjacent the closed end of the closure, and a widening angle of about 0.62° ±0.02°.

[0172] Figure 17 is a graph plotting ultimate tensile strength (UTS) against distance for (i) a closure formed according to the general method above but without introducing score line and (ii) a closure formed according to the method above including the scoring draw step. Fracture testing was conducted at 5 mm intervals to determine the ultimate tensile strength to cause fracturing. In both cases, the results show a generally linear decrease in tensile strength according to (i) UTS = -0.66936X ± 151.91 (where X is the distance from the bottom of the closure, and the unit of force is MPa), and (ii) UTS= -0.6942X ± 101.8.

[0173] The slope of both equations remains similar, indicating that the mechanical integrity of the closure is maintained, but the scored band lowers the force required by approximately 50 MPa, allowing controlled skirt removal

[0174] Figure 18 is a roughness surface plot showing the variation in score line depth from the base of the skirt / open bottom end to the closed end of the closure. As can be seen, the score line depth increases from the base of the skirt / open bottom end to the closed end of the closure.

[0175] Figure 19 is a plot showing the width and depth of the score line. This plot shows that the width and depth of the score line is increases from the base of the skirt / open bottom end to the closed end of the closure. This appears to contrast with the photographs of Figure 16A and 16B. This difference is believed to arise because the score line at the base of the skirt / open bottom end is shallow, and due to this shallowness, the total width of the score line at the open bottom end is not captured by the measurement.

[0176] These results show that the score line is wider and deeper at the closed end than in comparison with the open end, correlating with the tensile testing results (e.g., areas with a deeper score line requires less force to initiate separation).

[0177] It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

CLAIMS1. A bottle closure comprising:a cylindrical body with an open end and a closed end, anda fracture line formed in the cylindrical body extending from the open end toward the closed end, the fracture line having decreasing ultimate tensile strength from the open end to the closed end and being configured to fracture from the open end toward the closed end on application of a critical applied stress.

2. The bottle closure of claim 1, wherein the critical applied stress to initiate the crack is greater than a stress to propagate the crack.

3. The bottle closure of claim 1 or 2, wherein the fracture line has increasing depth from the open end toward the closed end.

4. The bottle closure of any one of the preceding claims, wherein the fracture line has decreasing width from the open end toward the closed end.

5. The bottle closure of any one of the preceding claims, wherein the fracture line is a score line on an inward facing surface of the cylindrical body.

6. The bottle closure of any one of the preceding claims, further comprising:an end cap portion defining the closed end;a skirt portion defining the open end, wherein the skirt portion comprises the fracture line.

7. The bottle closure of any one of the preceding claims, wherein the bottle closure is a rollon pilfer-proof (ROPP) bottle closure.

8. A method of forming a bottle closure from a metal blank, the method comprising:a multi-step drawing process comprising:a scoring draw step with a redraw ring and porno having a scoring blade mounted therein, wherein during the scoring draw step, the method comprises introducing the fracture line onto a wall of the cylindrical body with the porno having the scoring blade mounted therein; andan ironing draw step comprising ironing the wall of the cylindrical body and altering the morphology of the fracture line such that the fracture line has decreasing tensile strength from the open end toward the closed end.

9. The method of claim 8, wherein:the clearance between an internal wall of the redraw ring used in the scoring draw step and an external wall of the porno used in the scoring draw step is about or less than a thickness of the wall of the cylindrical body; and / orthe clearance between an internal wall of a redraw ring used in the ironing draw step and an external wall of a porno used in the ironing draw step is about or greater than a thickness of the wall of the cylindrical body.

10. The method of claim 8 or 9, wherein:the scoring draw step is before or at the penultimate draw step and the ironing draw step is the final draw step of the multi-step draw process; and / orthe method comprises an initial draw step prior to the scoring draw step comprising drawing the metal blank to form a first preform, and wherein the scoring draw step comprises drawing the first preform or a preform derived therefrom; and / orwherein the ironing draw step flattens the fracture line, such that the fracture line has increasing depth from the open end toward the closed end; and / or has decreasing width from the open end toward the closed end.

11. A method of forming a bottle closure from a metal blank, the method comprising:a first draw step of drawing a metal blank with a first redraw-ring and a first porno to form a first preform;a second draw step of drawing the first preform or a preform derived therefrom with a second redraw-ring and a second porno having a blade mounted therein to form a second preform having the fracture line therein; anda third step of drawing the second preform with a third redraw-ring and a third porno to iron a wall of the second preform and alter the morphology of the fracture line to form the bottle closure with the fracture line having decreasing tensile strength from the open end toward the closed end.

12. The method of claim 11, whereinthe first redraw-ring and the first porno are sized to provide a clearance therebetween that is about or less than a wall thickness of the metal blank; and / orthe second redraw-ring and the second pomo are sized to provide a clearance therebetween that is about or less than a wall thickness of the first preform or preform derived therefrom; and / orthe third redraw-ring and the third pomo are sized to provide a clearance therebetween that is about or greater than a wall thickness of the second preform.

13. A redraw-ring when used to form the bottle closure of any one of claims 1 to 7 or when used in the method of any one of claims 8 to 12 to form a bottle closure, the redraw-ring comprising:a body having a circular aperture bounded by a peripheral wall through which a or the metal blank or preform can be extruded;wherein the peripheral wall comprises:a leading edge which bounds the circular aperture and which has a convex surface that is inwardly curved toward the circular aperture;a straight portion which bounds the circular aperture such that the circular aperture has constant diameter over a length of the straight portion; anda relief portion which bounds the circular aperture such that the circular aperture has increasing diameter in a direction away from the straight portion.

14. An redraw-ring for use in a drawing method to form a bottle closure from a metal blank or preform, the redraw-ring comprising:a body having a circular aperture bounded by a peripheral wall through which the metal blank or preform can be extruded;wherein the peripheral wall comprises:a leading edge which bounds the circular aperture and which has an convex surface that is inwardly curved toward the circular aperture;a straight portion which bounds the circular aperture such that the circular aperture has constant diameter over a length of the straight portion; anda relief portion which bounds the circular aperture such that the circular aperture has increasing diameter in a direction away from the straight portion.

15. The redraw-ring of claim 13 or 14, wherein:the inwardly curved surface has a radial curvature, and the radial curvature has a radius of curvature of about 0.5 to about 5 mm; ora multi-radii convex surface, wherein each radius in the multi-radii convex surface has a radius of curvature of from about 0.1 mm to about 5mm; and / orthe straight portion extends from the curved surface of the leading edge, and wherein the length of the straight portion is about 0.1 mm to about 5 mm; and / orthe relief portion extends from the straight portion, and wherein the relief portion is angled away from the straight portion at an angle of from about 2° up to about 45°; orthe relief portion extends from the straight portion in the form of a concave recess; and / or the redraw ring further comprising a second straight portion which bounds the circular aperture such that the circular aperture has constant diameter over a length of the further straight portion extending from the relief portion.

16. A porno when used to form the bottle closure of any one of claims 1 to 7 or when used in the method of any one of claims 8 to 12 to form a bottle closure, the porno having a cylindrical body comprising:a shaft having a porno head located at one end thereof;a detachable sleeve mountable to the shaft, the detachable sleeve comprising a first end configured to be seated on the porno head, a second end, and an open channel extending from the first end to the second end,wherein the open channel has an opening that runs at least a portion of a length of the detachable sleeve and terminates at an open end at the second end;wherein the channel is configured to hold an insert therein with a portion of the insert extending outward of the channel; anda cover mountable to the shaft and configured to abut the second end of the sleeve to retain the sleeve in position on the shaft and cover the open end.

17. A porno for use in a drawing method to form a bottle closure from a metal blank, the porno having a cylindrical body comprising:a shaft having a porno head located at one end thereof;a detachable sleeve mountable to the shaft, the detachable sleeve comprising a first end configured to be seated on the porno head, a second end, and an open channel extending from the first end to the second end,wherein the open channel has an opening that runs at least a portion of a length of the detachable sleeve and terminates at an open end at the second end;wherein the channel is configured to hold an insert therein with a portion of the insert extending outward of the channel; anda cover mountable to the shaft and configured to abut the second end of the sleeve to retain the sleeve in position on the shaft and cover the open end.

18. The porno of claim 16 or 17, wherein the insert is a blade, and the porno further comprises the blade, the blade being locatable within the channel, and wherein the portion of the insert extending outward of the channel is a cutting edge of the blade.

19. The porno of claim 18, wherein:the cutting edge is in the form of a wedge having an angle of from about 15° to about 120°; and / orthe porno further comprises one or more removable retaining elements locatable within the channel to retain the blade within the channel; and / ora base of the porno has a contact surface, and the perimeter of the contact surface is in the form of a convex curvature in a direction away from the contact surface.

20. The porno of claim 19, wherein:the retaining elements are inwardly curved wall portions of the channel; and / or the convex curvature is a radial curvature with a radius of from about 0.5 mm to about 4 mm.

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