# Patent

## Title
Can end and method for fixing the same to a can body

## Abstract

A can end comprising a peripheral cover hook, a chuck wall dependent from a first point on the interior of the cover hook, an outwardly concave annular reinforcing bead extending radially inwards from a second point on the interior of the chuck wall, and a central panel supported by an inner portion of the reinforcing bead, characterized in that, a line connecting the first point and the second point is inclined to an axis perpendicular to the exterior of the central panel at an angle between 30° and 60°.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation of U.S. patent application Ser. No. 09/650,664, filed Aug. 30, 2000 now abandoned, which is a continuation of U.S. patent application Ser. No. 09/552,668, filed Apr. 19, 2000, now abandoned, which is a continuation of U.S. patent application Ser. No. 08/945,698, filed Nov. 21, 1997, which issued May 23, 2000 as U.S. Pat. No. 6,065,634, which is the U.S. National Phase of PCT/GB96/00709, filed Mar. 25, 1996, which claims priority to UK 9510515.1, filed May 24, 1995.


This invention relates to an end wall for a container and more particularly but not exclusively to an end wall of a can body and a method for fixing the end wall to the can body by means of a double seam.
U.S. Pat. No. 4,093,102 (KRASKA) describes can ends comprising a peripheral cover hook, a chuck wall dependent from the interior of the cover hook, an outwardly concave annular re-inforcing bead extending radially inwards from the chuck wall and a central panel joined to an inner wall of the reinforcing bead by an annular outwardly convex bead. This can end is said to contain an internal pressure of 90 psi by virtue of the inclination or slope of the chuck wall, bead outer wall and bead inner wall to a line perpendicular to the centre panel. The chuck wall slope D° is between 14° and 16°, the outer wall slope E is less than 4° and the inner wall slope C° is between 10 and 16° leading into the outwardly convex bead. We have discovered that improvements in metal usage can be made by increasing the slope of the chuck wall and limiting the width of the anti peaking bead.
U.S. Pat. No. 4,217,843 (KRASKA) describes an alternative design of can end in which the countersink has inner and outer flat walls, and a bottom radius which is less than three times the metal thickness. The can end has a chuck wall extending at an angle of approximately 24° to the vertical. Conversely, the specification of our U.S. Pat. No. 5,046,637 describes a can end in which the chuck wall extends at an angle of between 12° and 20° to the vertical.
The detailed description of our U.S. Pat. No. 4,571,978 describes a method of making a can end suitable for closing a can body containing a beverage such as beer or soft drinks. This can end comprises a peripheral flange or cover hook, a chuck wall dependant from the interior of the cover hook, an outwardly concave reinforcing bead extending radially inwards from the chuck wall from a thickened junction of the chuck wall with the bead, and a central panel supported by an inner portion of the reinforcing bead. Such can ends are usually formed from a prelacquered aluminum alloy such as an aluminum magnesium manganese alloy such as alloy 5182.
The specification of our U.S. Pat. No. 5,582,319 describes a can end suitable for a beverage can and formed from a laminate of aluminum/manganese alloy coated with a film of semi crystalline thermoplastic polyester. This polyester/aluminum alloy laminate permitted manufacture of a can end with a narrow, and therefore strong reinforcing bead in the cheaper aluminum manganese alloy.
Continuing development of a can end using less metal, whilst still permitting stacking of a filled can upon the end of another, this invention provides a can end comprising a peripheral cover hook, a chuck wall dependant from the interior of the chuck wall, an outwardly concave annular reinforcing bead extending radially inwards from the chuck wall, and a central panel supported by an inner portion of the reinforcing bead, characterised in that, the chuck wall is inclined to an axis perpendicular to the exterior of the central panel at an angle between 30° and 60°, and the concave bead narrower than 1.5 mm (0.060′′). Preferably, the angle of the chuck wall to the perpendicular is between 40° and 45°.
In a preferred embodiment of the can end an outer wall of the reinforcing bead is inclined to a line perpendicular to the central panel at an angle between −15° to +150 and the height of the outer wall is up to 2.5 mm.
In one embodiment the reinforcing bead has an inner portion parallel to an outer portion joined by said concave radius.
The ratio of the diameter of the central panel to the diameter of the peripheral curl is preferably 80% or less.
The can end may be made of a laminate of thermoplastic polymer film and a sheet aluminium alloy such as a laminate of a polyethylene teraphthalate film on an aluminium-manganese alloy sheet or ferrous metal typically less than 0.010 (0.25 mm) thick for beverage packaging. A lining compound may be placed in the peripheral cover hook.
In a second aspect this invention provides a method of forming a double seam between a can body and a can end according to any preceding claim, said method comprising the steps of:

    
    
        placing the curl of the can end on a flange of a can body supported on a base plate, locating a chuck within the chuck wall of the can end to centre the can end on the can body flange, said chuck having a frustoconical drive surface of substantially equal slope to that of the chuck wall of the can end and a cylindrical surface portion extending away from the drive surface within the chuck wall, causing relative motion as between the assembly of can end and can body and a first operation seaming roll to form a first operation seam, and thereafter causing relative motion as between the first operation seam and a second operation roll to complete a double seam, during these seaming operations the chuck wall becoming bent to contact the cylindrical portion of the chuck.
    
    





Various embodiments will now be described by way of example and with reference to the accompanying drawings in which:
FIG. 1 is a diagrammatic sketch of known apparatus for forming a double seam;
FIG. 2 is an enlarged sectioned side view of a known chuck and can end before seaming;
FIG. 3 is a sectioned view of a fragment of a known double seam;
FIG. 4 is a sectioned side view of a can end according to this invention before edge curling;
FIG. 5 is a sectioned side view of the can end of FIG. 4 on a can body before forming of a double seam;
FIG. 6 is a like view of the can end and body during first operation seaming;
FIG. 7 is a like view of the can end and body during final second operation seaming to create a double seam;
FIG. 8 is a fragmentary section of a chuck detail; and
FIG. 9 is a side view of the cans stacked one on the other.



In FIG. 1, apparatus for forming a double seam comprises a base plate 1, an upright 2 and a top plate 3.
A lifter 4 mounted in the base plate is movable towards and away from a chuck 5 mounted in the top plate. The top plate supports a first operation seaming roll 6 on an arm 7 for pivotable movement towards and away from the chuck. The top plate also supports a second operation seaming roll 8 on an arm 9 for movement towards and away from the chuck after relative motion as between the first operation roll and can end on the chuck creates a first operation seam.
As shown in FIG. 1 the chuck 5 holds a can end 10 firmly on the flange 11 of a can body 12 against the support provided by the lifter plate 4. Each of the first operation roll 6 and second operation roll 7 are shown clear of chuck before the active seam forming profile of each roll is moved in turn to form the curl of the can end and body flange to a double seam as shown in FIG. 3.
FIG. 2 shows on an enlarged scale the chuck 5 and can end 10. The can end comprises a peripheral curl 13, a chuck wall 14 dependent from the interior of the curl, an outwardly concave anti-peaking bead 15 extending inwards from the chuck wall to support a central panel 16. Typically the chuck wall flares outwardly from the vertical at an angle C about 12° to 15°.
The chuck 5 comprises a body 17 having a threaded bore 18 permitting attachment to the rest of the apparatus (not shown). An annular bead 19 projects from the body 17 of the chuck to define with the end face of the body a cavity to receive the central panel 16 of the can end. The fit of panel 16 in annulus 19 may be slack between panel wall and chuck.
The exterior surface of the projecting bead 19 extends upwards towards the body at a divergent angle B of about 12° to the vertical to join the exterior of the chuck body 17 which tapers off an angle A° of about 4° to a vertical axis perpendicular to the central panel. The outer wall of the chuck 5 engages with the chuck wall at a low position marked “D” within the 12° shaped portion of the chuck bead 15.
As can ends are developed with narrower anti-peaking beads the chuck bead 19 becomes narrower and more likely to fracture. There is also a risk of scuffing of the can end at the drive position D which can leave unacceptable unsightly black marks after pasteurisation.
FIG. 3 shows a sectioned fragment of a typical double seam showing a desirable overlap of body hook 21 and end hook 20 between the can end 10 and can body 12.
FIG. 4 shows a can end, according to the invention, comprising a peripheral cover hook 23, a chuck wall 24 extending axially and inwardly from the interior of the peripheral cover hook, an outwardly concave reinforcing or anti-peaking bead 25 extending radially inwards from the chuck wall, and a central panel 26 supported or an inner portion panel with 27. The panel wall is substantially upright allowing for any metal spring back after pressing. The chuck wall is inclined to an axis perpendicular to the exterior of the central panel at an angle C, between 20° and 60°; preferably between 40° and 45°. Typically the cross sectional radius of the antipeaking bead is about 0.5 mm.
Preferably the anti-peaking bead 25 is parallel sided, however the outer wall may be inclined to a line perpendicular to the central panel at an angle between −15° to +15° and the height h4 of the outer wall may be up to 2.5 mm.
This can end is preferably made from a laminate of sheet metal and polymeric coating. Preferably the laminate comprises an aluminium magnesium alloy sheet such as 5182, or aluminium manganese alloy such as 3004 with a layer of polyester film on one side. A polypropylene film may be used on the “other side” if desired.
Typical dimensions of the example of the invention are:















d5
overall diameter (as stamped)
65.83
mm


d4
PC diameter of seaming panel radius
61.54
mm


d3
PC diameter of seaming panel/chuck wall radius
59.91
mm


r1
seaming panel/chuck wall radius
1.27
mm


r2
seaming panel radius
5.56
mm


r3
concave radius in antipeaking bead
<1.5
mm


d2
maximum diameter of antipeaking bead
50.00
mm


d1
minimum diameter of antipeaking bead
47.24
mm


h2
overall height of can end
6.86
mm


h1
height to top of antipeaking bead
5.02
mm


h3
panel depth
2.29
mm


h4
outer wall height
1.78
mm


c
chuck wall angle to vertical
43°










From these dimensions it can be calculated that the ratio of central panel diameter of 47.24 mm to overall diameter of can end 65.84 is about 0.72 to 1.
For economy the aluminium alloy is in the form of sheet metal less than 0.010′′ (0.25 mm). A polyester film on the metal sheet is typically 0.0005′′ (0.0125 mm).
Although this example shows an overall height h2 at 6.86 mm we have also found that useful can ends may be made with an overall height as little as 6.35 mm (0.25′′).
FIG. 5 shows the peripheral flange 23 of can end 22 of FIG. 4 resting on the flange 11 of a can body 12 before formation of a double seam as discussed with reference to FIG. 1.
In FIG. 5 a modified chuck 30 comprises a chuck body 31 having a frustoconical drive surface 32 engaging with the chuck wall 24 of the can end 22.
The frustoconical drive surface is inclined outwardly and axially at an angle substantially equal to the angle of inclination C° of between 20° and 60°; in this particular example on chuck angle C of 43° is preferred. The drive surface 32 is a little shorter than the chuck wall 24 of the chuck body. The substantially cylindrical surface portion 33, rising above the drive surface 32, may be inclined at an angle between +4° and −4° to a longitudinal axis of the chuck. As in FIG. 2, this modified chuck 30 has a threaded aperature to permit attachment to the rest of the double seam forming apparatus (not shown).
In contrast to the chuck of FIG. 2 the modified chuck 30 is designed to drive initially on the relatively large chuck wall 32 without entering deeply into the anti-peaking bead 25. Further drive is obtained at the juncture of chuck wall 32 and cylindrical wall 33 as chuck wall of end 24 is deformed during 1st and 2nd operation seaming FIGS. 6 and 7. The chuck 30 shown in FIG. 5 has an annular bead of arcuate cross section but this bead is designed to enter the chuck wall without scratching or scuffing a coating on the can end; not to drive on the concave bead surface as shown in FIG. 2.
It will be understood that first operation seaming is formed using apparatus as described with reference to FIG. 1.
FIG. 6 shows the modified can end and chuck during formation of a first operation seam shown at the left of FIG. 2 as formed by a first operation roll 34 adjacent the interfolded peripheral flange of the can end and flange 11 body 12.
During relative rotation as between the can end 22 and first operation roll 34 the edge between the chuck drive wall 32 and cylindrical wall 33 exerts a pinching force between chuck 30 and roll 34 to deform the chuck wall of the can end as shown.
After completion of the first operation seam the first operation roll is swung away from the first operation seam and a second operation roll 38 is swung inwards to bear upon the first operation seam supported by the chuck 30. Relative rotation as between the second operation roll 38 and first operation seam supported by a chuck wall 30 completes a double seam as shown in FIG. 7 and bring the upper portion 24 of the chuck wall 24 to lie tightly against the can body neck in a substantially upright attitude as the double seam is tightened by pinch pressure between the second operation roll 38 and chuck 30.
Can ends according to the invention were made from aluminium alloy 5182 and an aluminium alloy 3004/polymer laminate sold by CarnaudMetalbox under the trade mark ALULITE. Each can end was fixed by a double seam to a drawn and wall ironed (DWI) can body using various chuck angles and chuck wall angle as tabulated in Table 1 which records the pressure inside a can at which the can ends failed:










TABLE 1









CAN END DATA















CHUCK
PRESSURE IN BAR (PSIG) TO FAILURE FOR



Material
Minimum
Wall
VARIOUS SEAMING CHUCK ANGLES B°















Sample
Thickness
Diameter
Angle



23° with
10°/23° with


Code
mm
D1 mm
“C”
23°
10°/23°
4°/23°
D. Seam Ring
D. Seam Ring


















A
ALULITE
52.12
21.13°
5.534
5.734
5.311
6.015
5.875



0.23 
(2.052′′)

(80.20)
(83.10)
(76.97)
(87.17)
(85.14)


B
5182
52.12
21.13°
5.599
5.575
5.381
5.935
5.895



0.244
(2.052′′)

(81.15)
(80.79)
(77.99)
(86.01)
(85.43)


C
5182
52.12
21.13°
6.004
5.910
5.800
6.224
6.385



0.245
(2.052′′)

(87.02)
(85.65)
(84.06)
(90.21)
(92.54)


D
ALULITE
51.92
21.13°
5.334
5.229
5.238
5.730
5.404



0.23 
(2.044′′)

(77.31)
(75.78)
(75.91)
(83.04)
(78.32)


E
5182
51.92
21.13°
5.555
5.514
5.354
5.895
5.930



0.224
(2.044′′)

(80.50)
(79.92)
(77.60)
(85.43)
(85.94)


F
5182
51.92
23°
5.839
5.804
5.699
6.250
6.435



0.245
(2.044′′)

(84.63)
(84.12)
(82.59)
(90.58)
(93.26)


G
ALULITE
51.92
23°


5.123



0.23 
(2.044′′)



(74.25)


H
5182
(51.92)
23°


5.474



0.224
(2.044′′)



(79.34)


I
5182
51.92
23°


5.698



0.245
(2.044′′)



(82.58)





All pressures on unaged shells in bar (psig). 5182 is an aluminium-magnesium-manganese alloy lacquered. The “ALULITE” used is a laminate of aluminium alloy and polyester film. 






The early results given in Table 1 showed that the can end shape was already useful for closing cans containing relatively low pressures. It was also observed that clamping of the double seam with the “D” seam ring resulted in improved pressure retention. Further tests were done using a chuck wall angle and chuck drive surface inclined at nearly 45°: Table 2 shows the improvement observed:












TABLE 2









h2
h3

Chuck Angles B°












Sample
mm
mm
h4

43° with


Code
(inches)
(inches)
mm (inches)
43°
seam ring





J
6.86
2.39
2.29 (0.09)
4.89 (70.9)
6.15 (89.1)



(0.270)
(0.094)


K
7.11
2.64
2.54 (0.10)
4.83 (70.0)
5.98 (86.6)



(0.280)
(0.104)


L
7.37
2.90
2.79 (0.11)
4.74 (68.7)
6.44 (93.3)



(0.290)
(0.114)









Table 2 is based on observations made on can ends made of aluminium coated with polymer film (ALULITE) to have a chuck wall length of 5.029 mm (0.198′′) up the 43° slope.
It will be observed that the container pressures achieved for samples J, K, L, 4.89 bar (70.9 psig), 4.83 bar (70.0 psig) and 4.74 bar (68.7 psig) respectively were much enhanced by clamping the double seam.
In order to provide seam strength without use of a clamping ring, modified chucks were used in which the drive slope angle C° was about 43° and the cylindrical surface 33 was generally +4° and −4°. Results are shown in Table 3.







TABLE 3







Results














CHUCK






ANGLES



SAMPLE

LINING
DRIVE/



CODE
MATERIAL
COMPOUND
WALL
PRESSURE















c
0.224
5182
with
43°
4.60 (66.7)


g
0.23
Alulite
with
43°/4°
5.45 (79.0)


h
0.224
5182
with
43°/4°
6.46 (93.6)


j
0.23
Alulite
without
43°/4°
5.91 (85.6)


k
0.244
5182
without
43°/4°
6.18 (89.6)


l
0.23
Alulite
without
43°/−4°
5.38 (77.9)


m
0.25
Alulite
without
43°/−4°
6.20 (89.8)


n
0.23
Alulite
without
43°/0°
6.11 (88.5)


o
0.25
Alulite
without
43°/0°
6.62 (95.9)





ALL PRESSURES IN BAR (PSIG) 






ALL CODES

    Reform Pad Dia. 47.24 mm (1.860′′) (202 Dia).
    6.86 mm (0.270′′) unit Depth h2 2.39 mm (0.094′′) Panel Depth


Table 3 shows Code “0” made from 0.25 mm Alulite to give 6.62 bar (95 psi) Pressure Test Result indicating a can end suitable for pressurised beverages. Further chucks with various land lengths (slope) were tried as shown in Table 4.







TABLE 4







CHUCK WALL ANGLE










43°/0° 1.9 mm LAND
43°/0° 1.27 MM LAND R.



SHARP TRANSITION
0.5 MM BLEND













WITH
NO.



VARIABLE
NO. D.SEAM
D.SEAM
D.SEAM
WITH D.SEAM


CODE
RING
RING
RING
RING





7
6.699 (97.08)
7.017
6.779
7.006 (101.54)




(101.7)
(98.24)


8
6.315 (91.52)
6.521
6.293
6.236 (90.37)




(94.5)
(91.2)


9
6.095 (88.33)
 6.30
6.238
6.719 (97.38)




(91.3)
(90.4)









ALL PRESSURES IN BAR (PSIG)
CODE

    
    
        7=0.25 mm Alulite, 47.24 mm (1.860′′) Reform Pad, 6.86 mm (0.270′′) h2 Depth, 2.38 mm (0.094′′) Panel; h4 depth=2.29 mm (0.09′′)
        8=0.23 mm Alulite, 47.24 mm (1.860′′) Reform Pad, 7.11 mm (0.280′′) h2 Depth, 2.64 mm (0.104′′) Panel; h4 depth=2.54 mm (0.10′′)
        9=0.23 mm Alulite, 47.24 mm (1.860′′) Reform Pad, 7.37 mm (0.290′′) h2 Depth, 2.90 mm (0.114′′) Panel; h4 depth=2.79 mm (0.11′′)
    
    


Table 4 shows results of further development to seaming chuck configuration to bring closer the pressure resistance of ring supported and unsupported double seams.
Table 4 identifies parameters for length of generally vertical cylindrical surface 33 on the seaming chuck 30, and also identifies a positional relationship between the chuck wall 24 of the end and the finished double seam. It will be understood from FIG. 7 shows that the forces generated by thermal processing or carbonated products are directed towards and resisted by the strongest portions of the completed double seam.
Table 5 shows results obtained from a typical seam chuck designed to give double seam in accordance with parameters and relationships identified in Table 4. Typically:—As shown in FIG. 8 the chuck comprises a cylindrical land of length ‘1’ typically 1.9 mm (0.075′′) and frustoconical drive surface 32 inclined at an angle Y°, typically 43°, to the cylindrical to which it is joined by a radius R typically 0.5 mm (0.020′′). Angle “X” is typically 90°.











TABLE 5










DIMENSIONS mm
PRESSURE












CODE
GAUGE
h2
h3
bar
(psi)















20
.23 mm
7.37 (.290′′)
2.36 (.093′′)
6.383
(92.6)


21
.23 mm
7.37 (.290′′)
2.36 (.093′′)
6.402
(92.8)





with compound


26
.23 mm
6.87 (.2705′′)
2.37 (.0935′′)
6.144
(89.88)


27
.23 mm
6.87 (.2705′′)
2.37 (.0934′′)
6.071
(88.0)





with compound


28
.23 mm
7.37 (.290′′)
2.36 (.093′′)
6.414
(93.0)


29
.23 mm
7.37 (.290′′)
2.84 (.112′′)
6.725
(97.5)


30
.23 mm
6.86 (.270′′)
2.37 (.0935′′)
6.062
(87.9)


31
.23 mm
6.86 (.270′′)
2.37 (.0935′′)
6.013
(87.2)


34
.25 mm
7.37 (.290′′)
2.87 (.113′′)
7.787
(112.9)


36
.25 mm
7.32 (.288′′)
2.34 (.092′′)
7.293
(105.8)


37
.25 mm
7.32 (.288′′)
2.34 (.092′′)
7.402
(107.3)





with compound


38
.25 mm
6.87 (.2705′′)
2.41 (.095′′)
7.077
(102.6)


516
.25 mm
6.35 (.250′′)
2.34 (.092′′)
6.937
(100.6)





with compound





All variables made from Alulite, 10 Cans per variable. 






The can ends may be economically made of thinner metal if pressure retention requirements permit because these can ends have a relatively small centre panel in a stiffer annulus.
FIG. 9 shows a can 12a, closed according to this invention, stacked upon a like can 12b shown sectioned so that stacking of the upper can on the lower can end is achieved by a stand bead 31a of the upper can fits inside the chuck wall 24 of the lower can end with the weight of the upper can resting on the double seam 34 of the lower can end.
The clearance between the bottom of the upper can body and lower can end may be used to accommodate ring pull features (not shown) in the can end or promotional matter such as an coiled straw or indicia.
Using the experimental data presented above, a computer programme was set up to estimate the resistance to deformation available to our can ends when joined to containers containing pressurised beverage. The last two entries on the table relate to a known 206 diameter beverage can end and an estimate of what we think the KRASKA patent teaches.

















TABLE 6








RATIO

CHUCK
RE-
INNER
OUTER
PREDICTED
ACTUAL




PANEL
OVERALL
CHUCK
WALL
INFORCING
WALL
WALL
CUT EDGE
THICK-


END SIZE
OVERALL
DIA
DIA:
WALL
LENGTH
RAD
HEIGHT
HEIGHT
Ø
NESS TO


Bead
DIA
d1
PANEL
ANGLE
L
r3
h3
h4
(*DENOTES
CONTAIN


OD:1D
mm
mm
DIA
° C.
mm
mm
mm
mm
ACTUAL)
PSI

























206-204
64.39
49.49
1.3010
33.07°
4.22
0.52
2.34
1.78
75.230
0.255



(2.535′′)
(1.9485′′)


(0.166′′)
(0.204′′)
(0.092′′)
(0.070′′)
(2.9618′′)


206-202
64.39
47.33
1.3604
42.69°
4.95
0.52
2.34
1.78
74.272
0.255



(2.535′′)
(1.8634′′)


(0.195′′)
(0.0204′′)
(0.092′′)
(0.070′′)
(2.9241′′)*


206-200
64.39
45.07
1.4287
50.053°
5.82
0.52
2.34
1.78
73.13
0.255



(2.535′′)
(1.7744′′)


(0.229′′)
(0.0204′′)
(0.092′′)
(0.070′′)
(2.9021′′)


204-202
62.18
47.33
1.3137
29.78°
3.96
0.52
2.34
1.78
73.767
0.24



(2.448′′)
(1.8634′′)


(0.156′′)
(0.0204′′)
(0.092′′)
(0.070′′)
(2.9042′′)


204-200
62.18
45.07
1.3796
40.786°
4.70
0.52
2.34
1.78
72.911
0.24



(2.448′′)
(1.7744′′)


(0.185′′)
(0.0204′′)
(0.092′′)
(0.070′′)
(2.8705′′)


202-200
71.98
45.07
1.597
30.266°
4.09
0.52
2.34
1.78
71.984
0.225



(2.834′′)
(1.7744′′)


(0.161′′)
(0.0204′′)
(0.092′′)
(0.070′′)
(2.834′′)


206 std
64.69
51.92
1.2461
15.488°
4.39
0.56
2.03
—
76.454
0.28



(2.547′′)
(2.044′′)


(0.173′′)
(0.022′′)
(0.080′′)

(3.010′′)*


KRASKA
64.39
—
—
15°
2.54
0.81
1.65
2.29
78.080
0.292


ESTIMATE
(eg 2.535′′)



(0.100′′)
(0.032′′)
(0.065′′)
(0.090′′)
(3.074′′)
(0.0115′′)





All experiments modelled on a notional aluminium alloy of yield strength 310 mpa 0.25 mm thick. The standard was also 310 mpa BUT 0.275 mm thick.

## Claims

1. A method of forming a double seam between a can body and a can end, said method comprising the steps of:
a) providing a can end having a circumferentially extending peripheral curl and a wall extending circumferentially and radially inward from said curl and an annular reinforcing bead extending radially inward from said wall, said reinforcing bead having an interior surface, said peripheral curl comprising a seaming panel and a radiused portion extending from said seaming panel to said wall, said wall inclined between about 20° and about 60° with respect to an axial centerline of said can end; 
b) placing said curl of said can end into contact with a circumferentially extending flange of a can body; 
c) providing a rotatable chuck having first and second circumferentially extending walls, said first and second walls forming a juncture therebetween; bringing said chuck into engagement with said can end so that said juncture of said first and second walls of said chuck contacts said inclined wall of said can end; 
d) rotating said chuck; 
e) performing a first seaming operation by placing a first seaming roll into contact with said can end curl while rotating said can end so as to partially deform said curl and said can body flange into a partial seam, said rotation of said can end during said first seaming operation driven by said rotating chuck through driving contact between said juncture of said first and second walls of said chuck and said inclined wall of said can end without driving contact between said chuck and said can end bead interior surface; 
f) performing a second seaming operation by placing a second seaming roll into contact with said partially deformed can end curl so as to further deform said curl and said can body flange so as to further form said seam.

2. The method according to claim 1, wherein said first and second seaming operations reform said can end inclined wall by bending a first portion of said inclined wall upward by an angle of at least about 16°.

3. The method according to claim 1, wherein as a result of said first and second seaming operations said can end inclined wall is reformed so that a first portion of said wall is oriented substantially cylindrically.

4. The method according to claim 1, wherein prior to performing said first seaming operation said wall of said can end is inclined between about 30° and about 50° with respect to said axial centerline of said can end.

5. The method according to claim 4, wherein as a result of said first and second seaming operations said can end inclined wall is reformed so that a first portion of said wall is oriented substantially cylindrically.

6. The method according to claim 4, wherein said first and second seaming operations reform said can end inclined wall by bending a first portion of said inclined wall upward by an angle of at least about 26°.

7. The method according to claim 1, wherein prior to performing said first seaming operation said wall of said can end is inclined between about 40° and about 45° with respect to an axial centerline of said can end.

8. The method according to claim 7, wherein as a result of said first and second seaming operations said can end inclined wall is reformed so that a first portion of said wall is oriented substantially cylindrically.

9. The method according to claim 7, wherein said first and second seaming operations reform said can end inclined wall by bending a first portion of said inclined wall upward by an angle of at least about 36°.

10. The method according to claim 1, wherein said first circumferentially extending wall of said chuck is oriented so as to be substantially cylindrical.

11. The method according to claim 10, wherein said substantially cylindrical first wall of said chuck is oriented so as to be inclined with respect to an axial centerline of said chuck by no more than about 4°.

12. The method according to claim 1, wherein the distance from the lowermost point on said annular bead to the uppermost point on said curl defines a height of said can end, and wherein as a result of said first and second seaming operations said can end inclined wall is reformed so that a first portion of said wall is bent upwardly so as to substantially increase said height of said can end.

13. The method according to claim 1, wherein said chuck second wall is inclined with respect to an axial centerline of said chuck that substantially matches said inclination of said can end wall, and wherein said rotation of said can end during said first seaming operation is aided by driving contact between said second wall of said chuck and said inclined wall of said can end.

14. A method of forming a double seam between a can body and a can end intended for use in packaging a carbonated beverage, said method comprising the steps of:
a) providing a can end having (i) a circumferentially extending peripheral cover hook, said peripheral cover hook comprising a seaming panel to be formed into a portion of said double seam during a seaming operation, (ii) an annular reinforcing bead, and (iii) a circumferentially extending wall extending from said seaming panel to said reinforcing bead, said wall comprising first and second wall portions, said first wall portion to be formed into another portion of said double seam during said seaming operation, said first wall portion extending from said seaming panel to a first location on said wall and comprising a radiused portion extending from said seaming panel, said second wall portion extending from said first wall portion at said first wall location to a second location on said wall that forms a transition with said reinforcing bead, whereby said first and second locations form end points of said second wall portion, and wherein a straight line extending between said first and second locations on said wall is inclined between about 20° and about 60° with respect to an axial centerline of said can end; 
b) placing said cover hook of said can end into contact with a circumferentially extending flange of a can body; 
c) providing a rotatable chuck comprising a first circumferentially extending wall, said chuck first wall being substantially cylindrical; 
d) bringing said chuck into engagement with said can end; and 
e) performing said seaming operation by placing one or more seaming rolls into contact with said peripheral cover hook of said can end while said can end rotates so as to deform said seaming panel of said cover hook and said first wall portion and said can body flange into said double seam, said seaming operation deforming said first wall portion such that at least a portion of said first wall portion after seaming is substantially cylindrical, said first location on said wall after said seaming operation forming the transition from said substantially cylindrical wall portion to said second wall portion, said line between said first and second locations on said wall remaining inclined between about 20° and about 60° with respect to said axial centerline after completion of said seaming operation.

15. The method according to claim 14, wherein during said seaming operation at least a portion of said can end wall first portion is reformed by bending upward by an angle of at least about 16°.

16. The method according to claim 14, wherein said line between said first and second locations on said wall of said can end is inclined between about 30° and about 50° with respect to an axial centerline of said can end prior to performing said seaming operation.

17. The method according to claim 16, wherein during said seaming operation at least a portion of said can end wall first portion is reformed by bending upward by an angle of at least about 26°.

18. The method according to claim 14, wherein said line between said first and second locations on said second wall of said can end is inclined between about 40° and about 45° with respect to an axial centerline of said can end.

19. The method according to claim 18, wherein during said seaming operation at least a portion of said can end wall first portion is reformed by bending upward by an angle of at least about 36°.

20. The method according to claim 14, wherein said substantially cylindrical first wall of said chuck is oriented so as to be inclined with respect to an axial centerline of said chuck by no more than about 4°.

21. The method according to claim 14, wherein the distance from the lowermost point on said annular bead to the uppermost point on said cover hook defines a height of said can end, and wherein as a result of said seaming operation at least a portion of said can end first wall portion is bent upwardly into said substantially cylindrical orientation so as to substantially increase said height of said can end.

22. The method according to claim 14, wherein
f) said annular bead has an interior surface thereof; 
g) said chuck further comprises a second wall, said first and second walls of said chuck form a juncture therebetween; 
h) said seaming operation comprises (i) performing a first seaming operation by placing a first seaming roll into contact with said can end cover hook while said can end is rotated so as to partially deform said cover hook and said first wall portion and said can body flange into a partial seam, and (ii) performing a second seaming operation by placing a second seaming roll into contact with said partially deformed can end cover hook so as to further deform said cover hook and said first portion and said can body flange so as to further form said seam; 
i) said rotation of said can end during said first seaming operation is accomplished by imparting driving contact between said juncture of said first and second walls of said chuck and said wall of said can end but without imparting driving contact between said chuck and said can end bead interior surface.

23. The method according to claim 14, further comprising the step of filling the can body with a carbonated beverage prior to performing said seaming operation.

24. The method according to claim 14, wherein said chuck further comprises a second chuck wall depending from said substantially cylindrical first chuck wall, said second chuck wall not being substantially cylindrical whereby said first and second chuck walls form a juncture therebetween, and wherein the step of bringing said chuck into engagement with said can end comprises bringing said chuck wall juncture into engagement with said can end wall proximate said first location on said can end wall.

25. The method according to claim 24, wherein the step of performing said seaming operation further comprises bending said first wall portion of said can end upwardly around said chuck wall juncture so as to permanently deform said first wall portion.

26. The method according to claim 14, wherein said wall of said can end is substantially frustoconical prior to performing said seaming operation.

27. The method according to claim 14, wherein said first and second portions of said wall of said can end lie along a substantially straight line prior to performing said seaming operation.

28. The method according to claim 14, wherein said line between the first and second locations on said second wall remains inclined between about 30° and about 50° after seaming.

29. The method according to claim 14, wherein said line between the first and second locations on said second wall remains inclined between about 40° and about 45° after seaming.

30. The method according to claim 14, wherein, in said step c) of performing the seaming operation, rotation of said can end is achieved without imparting driving contact between said chuck and a bottom interior surface of said reinforcing bead.

31. The method according to claim 14, wherein said chuck further comprises a second chuck wall depending from said substantially cylindrical first chuck wall, said second chuck wall being substantially frustoconical.

32. A method of forming a double seam between a can body and a can end intended for use in packaging a carbonated beverage, said method comprising the steps of:
a) providing a can end having (i) a circumferentially extending peripheral cover hook, said peripheral cover hook comprising a seaming panel to be formed into a portion of said double seam during a seaming operation and (ii) a circumferentially extending wall comprising first and second portion, said first wall portion to be formed into another portion of said double seam during said seaming operation, said first wall portion extending from said seaming panel to a first location on said wall and comprising a radiused portion extending from said seaming panel, said second wall portion extending from said first wall portion at said first wall location on said wall to a second location on said wall, whereby said first and second locations form end points of said second wall portion, said second wall location being the lowermost point of said wall, and wherein a straight line extending between said first and second locations on said wall is inclined between about 20° and about 60° with respect to an axial centerline of said can end; 
b) placing said cover hook of said can end into contact with a circumferentially extending flange of a can body; 
c) providing a rotatable chuck comprising a first circumferentially extending wall, said first chuck wall being substantially cylindrical; 
d) bringing said chuck into engagement with said can end; and 
e) performing said seaming operation by placing one or more seaming rolls into contact with said peripheral cover hook of said can end so as to deform said seaming panel of said cover hook and said first wall portion and said can body flange into said double seam, said first portion of said can end wall being pressed against said chuck first wall so that at least a portion of said first portion of said can end wall is bent upward through an angle of at least about 16°, said first location on said wall after said seaming operation forming the transition from said double seam to said second wall portion, said line between said first and second locations remaining inclined between about 20° and about 60° with respect to said axial centerline.

33. The method according to claim 32, wherein said line between said first and second locations on said wall of said can end is inclined between about 30° and about 50° with respect to said axial centerline of said can end prior to performing said seaming operation.

34. The method according to claim 33, wherein during said seaming operation at least a portion of said can end wall first portion is reformed by bending upward by an angle of at least about 26°.

35. The method according to claim 33, wherein said line between the first and second locations on said second wall portion remains inclined between about 30° and about 50° after seaming.

36. The method according to claim 32, wherein said line between said first and second locations on said wall of said can end is inclined between about 40° and about 45° with respect to said axial centerline of said can end prior to performing said seaming operation.

37. The method according to claim 36, wherein during said seaming operation at least a portion of said can end wall first portion is reformed by bending upward by an angle of at least about 36°.

38. The method according to claim 36, wherein said line between the first and second locations on said second wall portion remains inclined between about 40° and about 45° after seaming.

39. The method according to claim 32, wherein the can end further comprises a reinforcing bead extending radially inward from said second portion of said wall at said second wall location, the distance from a lowermost point on said annular bead to the uppermost point on said cover hook defines a height of said can end, and wherein said upward bending of said first portion of can end wall during said seaming operation substantially increases said height of said can end.

40. The method according to claim 32, wherein
f) said can end comprises an annular reinforcing bead extending radially inward from said wall, said annular bead having an interior surface thereof; 
g) said chuck further comprises a second wall, said first and second walls of said chuck form a juncture therebetween; 
h) said seaming operation comprises (i) performing a first seaming operation by placing a first seaming roll into contact with said can end peripheral cover hook while said can end is rotated so as to partially deform said cover hook and said first wall portion and said can body flange into a partial seam, and (ii) performing a second seaming operation by placing a second seaming roll into contact with said partially deformed can end cover hook so as to further deform said cover hook and said first wall portion and said can body flange so as to further form said seam; 
i) said rotation of said can end during said first seaming operation is accomplished by imparting driving contact between said juncture of said first and second walls of said chuck and said wall of said can end but without imparting driving contact between said chuck and said can end bead interior surface.

41. The method according to claim 32, further comprising the step of filling the can body with a carbonated beverage prior to performing said seaming operation.

42. The method according to claim 32, wherein said chuck further comprises a second chuck wall depending from said substantially cylindrical first chuck wall, said second chuck wall not being substantially cylindrical whereby said first and second chuck walls form a juncture therebetween, and wherein the step of bringing said chuck into engagement with said can end comprises bringing said chuck wall juncture into engagement with said can end wall proximate said second location on said can end wall.

43. The method according to claim 42, wherein said bending of said first wall portion during said seaming operation comprises bending said first wall portion upwardly around said chuck wall juncture.

44. The method according to claim 42, wherein said end includes an annular reinforcing bead extending from said second wall portion and, in said step e) of performing the seaming operation, rotation of said can end is achieved without imparting driving contact between said chuck and a bottom interior surface of said reinforcing bead.

45. The method according to claim 32, wherein the can end includes a reinforcing bead extending radially inward from said lowermost point of said second portion of the wall.

46. The method according to claim 32, wherein said wall of said can end is substantially frustoconical prior to performing said seaming operation.

47. The method according to claim 32, wherein said first and second portions of said wall of said can end lie along a substantially straight line prior to performing said seaming operation.

48. The method according to claim 32, wherein after said seaming operation said first and second portions of said can end wall intersect at an obtuse angle.

49. The method according to claim 32, wherein said chuck further comprises a second chuck wall depending from said substantially cylindrical first chuck wall, said second chuck wall being substantially frustoconical.

50. A method of forming a double seam between a can body and a can end intended for use in packaging a carbonated beverage, said method comprising the steps of:
a) providing a can end having (i) a circumferentially extending peripheral cover hook, said peripheral cover hook comprising a seaming panel to be formed into a portion of said double seam during a seaming operation, (ii) an annular reinforcing bead, and (iii) a circumferentially extending wall extending from said seaming panel to said reinforcing bead, said wall and said reinforcing bead forming a transition therebetween; 
b) placing said cover hook of said can end into contact with a circumferentially extending flange of a can body; 
c) providing a rotatable chuck comprising first and second circumferentially extending walls, said second chuck wall depending from said first chuck wall so as to form a juncture therebetween; 
d) bringing said chuck into engagement with said can end; and 
e) performing said seaming operation by placing one or more seaming rolls into contact with said peripheral cover hook of said can end while said can end rotates so as to deform said seaming panel of said cover hook and to bend a portion of said can end wall upwardly around said juncture of said chuck walls at a first location on said can end wall, a straight line extending from said first location on said can end wall to said transition between said can end wall and said reinforcing bead inclined between about 20° and about 60° with respect to said axial centerline both before and after said seaming operation.

51. The method according to claim 50 wherein at least a portion of said portion of said can end wall bent upwardly during said seaming operation is bent upward through an angle of at least about 16°.

52. The method according to claim 50, wherein said line extending from said first location to said transition is inclined between about 30° and about 50° with respect to said axial centerline of said can end both before and after performing said seaming operation.

53. The method according to claim 52, wherein at least a portion of said portion of said can end wall bent upwardly during said seaming operation is bent upward through an angle of at least about 26°.

54. The method according to claim 50, wherein said line extending from said first location to said transition is inclined between about 40° and about 45° with respect to said axial centerline of said can end both before and after performing said seaming operation.

55. The method according to claim 54, wherein at least a portion of said portion of said can end wall bent upwardly during said seaming operation is bent upward through an angle of at least about 36°.

56. The method according to claim 50, wherein at least a portion of said portion of said can end wall bent upwardly during said seaming operation is bent upward into a substantially cylindrical configuration.

57. The method according to claim 50, wherein said wall of said can end is substantially frustoconical prior to performing said seaming operation.

58. The method according to claim 50, wherein said first wall of said chuck is oriented so as to be inclined with respect to an axial centerline of said chuck by no more than about 4°.

59. The method according to claim 50, wherein said first wall of said chuck is substantially cylindrical.

60. The method according to claim 59, wherein said said second chuck wall being substantially frustoconical.

61. The method according to claim 50, wherein the distance from a lowermost point on said annular bead to the uppermost point on said cover hook defines a height of said can end, and said seaming operation increases said height of said can end.

62. The method according to claim 50, wherein
f) said annular bead has an interior surface thereof; 
g) said seaming operation comprises (i) performing a first seaming operation by placing a first seaming roll into contact with said can end curl while said can end is rotated so as to partially deform said cover hook and a first portion of said can end wall and said can body flange into a partial seam, and (ii) performing a second seaming operation by placing a second seaming roll into contact with said partially deformed can end cover hook so as to further deform said cover hook and said can end wall first portion and said can body flange so as to further form said seam; 
h) said rotation of said can end during said first seaming operation is accomplished without imparting driving contact between said chuck and said can end bead interior surface.