Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D17/00—Rigid or semi-rigid containers specially constructed to be opened by cutting or piercing, or by tearing of frangible members or portions
  • B65D17/06—Integral, or permanently secured, end or side closures
  • B65D17/08—Closures secured by folding or rolling and pressing
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S220/00—Receptacles
  • Y10S220/906—Beverage can, i.e. beer, soda

Definitions

• This invention relates to a can end and a method of manufacture of such a can end.
• it relates to a can end which has improved performance characteristics .
• Containers such as cans which are used for the packaging beverages, for example, may contain a carbonated beverage which is at a higher than atmospheric pressure.
• Can end design has been developed to withstand this "positive" buckle pressure (sometimes also referred to as “peaking" pressure) up to defined minimum values (currently 90psi for carbonated soft drinks) under normal operating conditions before failure.
• Peaking pressure sometimes also referred to as “peaking” pressure
• failure of conventional can ends involves loss of the circular profile and buckling of the end which, ultimately, leads to eversion of the end profile.
• Abuse conditions may also arise when a container is dropped or distorted, or when the product within the container undergoes thermal processing.
• the can end shell (that is, the unseamed can end) of that patent includes a peripheral curl, a seaming panel, a chuck wall at an angle of between 30° and 60°, a narrow anti-peaking bead and a centre panel.
• the chuck wall is deformed at its upper end by contact with an anvil portion of the seaming chuck.
• the resulting profile provides a very strong double seam since the annulus formed by the seam has very high hoop strength and will resist distortion from its circular profile when subjected to thermal processing or when packaging carbonated beverages .
• Stiffness is also provided to the beverage can end by the anti-peaking or countersink bead.
• This is an outwardly concave bead comprising inner and outer walls, joined by a curved portion.
• this bead has walls which are substantially upright, although either may vary by up to +/- 15°.
• This patent uses a small base radius (best fit) for the bead, typically 0.75 mm or less .
• the width of the anti-peaking bead can be reduced by free drawing of the inner wall of the bead. This latter method avoids undue thinning of the bead as it is reworked.
• the resultant narrower bead optimises the stiffness of the can and, consequently, its resistance to buckling when attached to a can body having high internal pressure in the can.
• Can ends such as those described in the above patents have high hoop strength and/or improved buckle performance such that they resist deformation when subjected to high internal pressure.
• the buckle pressure of the end of EP-B-0828663 is well above the 90 psi can making industry minimum standard.
• This invention seeks to control the failure mode and to avoid catastrophic failure and leaking, whilst still achieving buck e pressure performance well above the industry stipulated pressure of 90 psi.
• a can end shell comprising a centre panel, a countersink bead, an inclined chuck wall portion, and a seaming panel, and further including one or more control features, each feature extending around an arc of part of the countersink bead and/or the chuck wall whereby the failure mode of the can end, when seamed to a can body, is controlled, and in which the or each control feature comprises one or more of: an expansion of the countersink bead, a shelf in the outer wall of the countersink, an indentation in the chuck wall, and/or coining.
• arc as used herein is intended to include a 360° arc, i.e. a control feature or features which extend around the whole circumference of the can end shell .
• inclined is not intended to be limiting and the inclined chuck wall may have one or more parts, any of which may be linear or curved, for example.
• a control feature such as a selectively weakened region, may be introduced onto the can end in a variety of different ways, all of which are intended to limit or prevent the concentration of strain. Control features or weakenings may be achieved by increasing the radial position of the outer wall of the countersink bead, a shelf in the countersink bead, an indentation in the chuck wall, or coining. Numerous variations are possible within the scope of the invention, including those set out below.
• a shelf in the countersink bead will be in the outer wall of the bead, and may be at any position up that wall. Clearly when the shelf is at the lower end of the outer wall it effectively corresponds to an expansion in the bead radius .
• a shelf or groove may be provided on any part of a radial cross-section through the bead but as the inner wall diameter position is often used as a reference for machine handling purposes and the thickness of the base of the countersink should ideally not be reduced, the outer wall is the preferred location.
• an indentation in the chuck wall should be made so that in the seamed can end, the indentation is positioned approximately at the root of the seam.
• the indentation should be made about half way up the chuck wall or in the upper half of the chuck wall, depending on the type of seam.
• the indentation may be made using radial and indent spacers to control the radial and penetration depth of the tool.
• a control feature may extend over a single arc behind the heel of the tab, centred on a diameter through the tab rivet and nose.
• the arc length may be anything up to 90° in order to encompass any "thin point" due to orientation relative to grain orientation.
• a control feature may comprise a combination of different types of control features, usually over at least a portion of the same arc of the can end such that, where the arcs are not fully circumferential, the different types are centred on the same can end diameter.
• the indentation in the chuck wall may extend over the same length of arc as the bead expansion, a longer or a shorter arc length, with the centres of the arcs being on the same end diameter.
• the countersink bead may have its base radius enlarged and then incorporate a control feature comprising a shelf in its outer wall.
• a control feature comprising a shelf in its outer wall.
• the arc length of the bead expansion (and, where present, the shelf) is less than the arc length of the chuck wall indentation, such that the bead expansion (and shelf) acts as a trigger for local peaking.
• control feature comprises an indentation or coined region on the chuck wall
• this may extend either internally or externally, or a combination of these around the arc.
• it is the side of the can end to which a tab is fixed which is referred to as “external” as this side will be external in the finished can.
• the indentation extends inwardly as otherwise it may be removed by the seaming tool during seaming.
• the end shell may additionally include coining of a shoulder between the inner wall of the countersink and the centre panel over an arc or pair of arcs.
• the control feature is preferably made in a conversion press but it may be made in a shell press or even in a combination of the shell and conversion presses providing that orientation of the end is not an issue.
• Figure 1 is a perspective view of a conventional beverage can end
• Figure 2 is a plan view of another type of beverage can end
• Figure 3 is a partial side section of the can end of figure 2, prior to seaming;
• Figure 4 is a partial side section of the can end of figure 2, after seaming to a can body;
• Figure 5 is a sectioned perspective view of a seamed can end having two types of control features .
• the can end of figure 1 is a conventional beverage end shell 1 comprising a peripheral curl 2 which is connected to a centre panel 3 via a chuck wall 4 and anti-peaking reinforcing bead or countersink 5.
• the centre panel has a score line 6 which defines an aperture for dispensing beverage.
• a tab 7 is fixed to the centre panel 3 by a rivet 8, as is usual practice. Beads 9 are provided for stiffening the panel.
• the can end of figure 1 when attached by seaming to a can body which is filled with carbonated beverage, for example, is typically able to withstand an internal pressure of 98 psi before buckling, 8 psi above the required minimum buckle pressure of 90 psi.
• an internal pressure of 98 psi before buckling, 8 psi above the required minimum buckle pressure of 90 psi When the pressure approaches and exceeds this value, the circular shape of the periphery of the end will distort and become oval. Eventually the centre panel will be forced outwardly so that the countersink "unravels" and flips over an arc of its circumference. Whilst a can which is buckled in such a manner is unlikely to be acceptable to a consumer, the can end itself is still intact, the tab 7 is still accessible and there is no compromise to the sealing of the container by such failure which could result in leaking of the contents.
• a container has an end which is, by virtue of its design, substantially stiffer and has greater hoop strength than that of figure 1, the buckle failure mode differs from that described above.
• a can end is that of EP-B-0828663, shown for reference in figures 2 to 4.
• the can end 20 is attached to a can body 21 by a double seam 22, as shown in figure 4.
• Inner portion 23 of the seam 22, which is substantially upright, is connected to a countersink bead 25 by a chuck wall 24.
• the countersink, or anti-peaking bead 25 has inner and outer walls 26 and 27, the inner wall 26 depending from the centre panel 28 of the end.
• a preferential "soft" peak is obtainable when the can end fails.
• the can end may fail at a lower buckle pressure, the softer, less explosive nature of the peak results in a failure mode without pin hole or tearing.
• the introduction of a control feature thus controls the failure mode and avoids concentration of the forces at a single point.
• the radial position of the outer wall 27 of the countersink bead may be increased;
• the chuck wall 24 may be coined or have indentations at or above approximately the mid-point such that this control feature is at the root of the seam 22 in the seamed can end (denoted as B');
• a shelf may be made in the outer wall 27 of the countersink bead.
• a type D region is at the lower part of the outer countersink wall, this may be equivalent to a type A control feature. Higher up the outer wall, a type D region takes the clear form of a shelf.
• the shell of figures 2 to 4 was modified by a local groove in the outer wall of the countersink.
• This groove was ideally adjacent the handle of the tab so that any failure of the can end would be away from the score. Positioning either side of the tab or, indeed, at any position around the countersink was also considered possible.
• the groove was typically about 8 mm in arc length and was positioned approximately half way down the outer wall of the countersink bead, in the form of a shelf . Computer modelling has showed that the provision of such a groove resulted in a failure mode similar to that of a conventional can end such as that of figure 1, with no leakage.
• Can ends were modified in the conversion press by expanding the countersink bead over a 60° arc at positions +/- 90° of the tab heel. These ends were then seamed onto filled cans and dropped vertically, tab end down, onto a steel plate, the sheet steel being inclined at 30°. This extreme test is non-standard and tested the cans for severe abuse performance.
• Can ends modified in this way were also tested by pressurising a can to which the end was seamed ("seamed end test”) . These results are shown in table 2. Whilst the cans all peaked on the indentation site and were still openable after peaking, only 25% survived testing without leaking on the peak location.
• the combination of a countersink bead expansion and indentation in the chuck wall increases the average height at which peaking occurs.
• the countersink bead expansion was found to act as a trigger and this combination of a trigger and chuck wall indentation controls the peaking better than a countersink bead expansion alone (example 1) .
• the chuck wall indentations comprised a indentation on each side of the tab, set at 90° to the tab.
• Spacer conditions were as in example 3, but with a 9 mm indent ring spacer (rather than 8.75 mm) .
• the countersink "trigger” comprised a single bead expansion within the arc of the chuck wall indentation and centred on the same diameter (arc mid-point) . This bead expansion was selected to trigger a peak within the chuck wall indentation as identified in example 2.
• the control can ends give very low survival figures in both drop tests and seamed end testing (SET), i.e. the control can ends leak when they peak.
• the chuck wall indentation alone gives good hot drop (100°F) and SET performance but seems to have higher incidence of score bursts during hot drop testing.
• the countersink (“c'sk”) bead trigger creates a very symmetric end shape from the hot drop test and is very effective in determining the peak location.
• the countersink trigger reduces the SET performance to 89 psi average, but this is believed to be attributable to the tooling used to create the indentations.
• “1” means yes and "0” means no, except in position in which 1 indicates the position of peak on the control feature.
• control features of the invention are particularly intended for use on beverage can ends which are to be fixed to a can body and thereby subjected to internal pressure.
• control features may be used on can ends having any chuck wall angle whether conventional (less than 15°) or larger, such as that of EP-B-0828663, i.e. 30° to 60°.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Rigid Containers With Two Or More Constituent Elements (AREA)
• Diaphragms For Electromechanical Transducers (AREA)
• Closures For Containers (AREA)
• Pressure Vessels And Lids Thereof (AREA)
• Wrappers (AREA)
• Cartons (AREA)
• Packages (AREA)
• Mechanical Pencils And Projecting And Retracting Systems Therefor, And Multi-System Writing Instruments (AREA)

Priority Applications (15)

Applications Claiming Priority (2)

Related Child Applications (3)

Publications (1)

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Citations (7)

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• 2002
  • 2002-04-22 EP EP02252800A patent/EP1361164A1/en not_active Withdrawn
• 2003
  • 2003-04-10 MX MXPA04010456A patent/MXPA04010456A/es active IP Right Grant
  • 2003-04-10 BR BRPI0309446-4A patent/BR0309446B1/pt active IP Right Grant
  • 2003-04-10 ES ES03722438T patent/ES2318126T3/es not_active Expired - Lifetime
  • 2003-04-10 AU AU2003229636A patent/AU2003229636B2/en not_active Expired
  • 2003-04-10 CA CA2482984A patent/CA2482984C/en not_active Expired - Lifetime
  • 2003-04-10 RU RU2004133891/02A patent/RU2319571C2/ru active
  • 2003-04-10 WO PCT/EP2003/003716 patent/WO2003089167A1/en not_active Ceased
  • 2003-04-10 DE DE60324910T patent/DE60324910D1/de not_active Expired - Lifetime
  • 2003-04-10 CN CNB038090155A patent/CN100393443C/zh not_active Expired - Lifetime
  • 2003-04-10 AT AT03722438T patent/ATE415217T1/de not_active IP Right Cessation
  • 2003-04-10 JP JP2003585908A patent/JP4280645B2/ja not_active Expired - Fee Related
  • 2003-04-10 EP EP03722438A patent/EP1497054B1/en not_active Revoked
• 2004
  • 2004-02-03 US US10/770,791 patent/US20040238546A1/en not_active Abandoned
  • 2004-10-18 ZA ZA2004/08419A patent/ZA200408419B/en unknown
• 2006
  • 2006-09-28 US US11/540,238 patent/US7370774B2/en not_active Expired - Lifetime

Patent Citations (7)

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