Note: Descriptions are shown in the official language in which they were submitted.
' CA 02112975 1999-O1-21
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METHOD AND APPARATUS FOR REFORMING CAN
BOTTOM TO PROVIDE IMPROVED STRENGTH
Description
Technical Field
The invention relates generally to a method and
apparatus for forming an improved, reformed can bottom, with a
result that the entire can is strengthened.
CA 02112975 1999-O1-21
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Typically, this method and apparatus are used for reforming
the bottoms of drawn and ironed beverage containers. The
reformed can bottom is an integral part of beer and beverage
cans, and increases the strength of those cans above that of
prior art cans.
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Buckqround Of The invention
Metal containers, and drawn or drawn and ironed
metal containers in particular, are among the most widely
used containers for pressurized carbonated beverages,
including such beverages as beer and soft drinks. Such
containers are also becoming increasinghy._popular for
food and other uses.
Drawn and ironed metal containers are made from
a disc of stock material which is converted into a
shallow "cup" with short side walls. The base of this
cup ultimately forms the bottom of the container, and the
short side walls of the cup become the elongated side
walls of the container.
The shallow cup is passed through a succession of
ironing rings. As the spacing between successive rings
becomes increasingly narrow, passage of the cup through
these successive rings decreases the sidewall thickness
and increases the height of the side walls.
The configuration of the bottom of such drawn and
ironed containers has, over the last several years, been
a topic of interest to both can manufacturers, packagers,
shippers, retailers and the ultimate consumer who
purchases products in such containers. This is because
the configuration of the bottom is a factor in the
ability of the container to resist its internal pressures
. and achieve adequate columnar strength, in addition to
adding stability to the can. These internal pressures
result from the weight, pressurization and carbonation of
the liquids in the container. Columnar strength is the
~ ability'of a container to resist axial loads imposed by
cans that are stacked upon other cans, as during traps-
po~ and . storage . '
Can manufacturers are constantly striving to
obtain high strength with relatively low weight.
Generally,' however, these goals are incompatible. Low
weight, and a lowering of material cost, is generally
achieved by reducing the thickness of the stock material.
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A reduction in stock material thickness, without more,
typically lowers the. strength of the container.
Retailers and consumers desire a container which is
stackable and which is of the lowest possible weight for
ease in handling.
The bottom shape of the container;.has been found
to be of importance in determining its strength. Issued
U.S. patents disclosing this importance include U.S.
Patent No. 4,685;582, issued to Pulciani, et. al., on
August 1l, 1987, and entitled "Container Profile With
Stacking Feature." This patent, which is assigned to the
assignee of the present invention, discloses a container
having an inverted dome-shaped bottom. Other U.S.
patents are also generally relevant. For example, U.S.
Patent Nos. 3,904,069, 3,979,009 and 4,412,627, disclose
containers having bottom wall constructions designed to
pe~cmit selected and controlled outward flexing or bulging
of the bottom wall when the container is sealed and
subjected to internal pressures developed by the con
tents.
Reforming of the bottom wall of a container of
the general type described in: this application has also
been described in an Claydon, et. al., U.S. Patent
No. 4,885,924. This reforming takes place by applying a
roller along the exterior transition wall 7 of the bottom
of the container, rather than along its interior:
However, when reforming the interior bottom wall to a
negative angle, as shown in Figure i0, a dedicated knock
out pad 46 is required., Additionally; due to material
t
spring-back, it is more difficult to control the ultimate
angle-of the interior bottom wall.
Jentzsch, et. al., U.S. Patent No. 5,105,973,
issued April 21; 1992; discloses a beverage container
having an interior bottom wall with a, negative angle. -
However, there is no disclosure of how this negative
angle is foryned.
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The present invention is provided to solve these
and other problems.
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~ummarv, Of The Invention
The invention is a method of and apparatus for
reforming the bottom of a metal container as, for
example, a drawn and ironed or a drawn beverage contain-
s er, and the container formed by this method and'appara-
tus. The container for wrich this method is..suitable may
have a longitudinal axis, typically a vertical axis, a
generally cylindrical side wall parallel with the
vertical axis, an outer annular wall, a convex U-shaped
portion, a preformed bottom wall including a center domed
portion, and an annular, substantially vertical wall
joining the domed portion and the convex U-shaped
portion. One aspect of the method comprises supporting
the container in a jig. The jig has a bottom peripheral
profile portion substantially corresponding in shape to
the outer annular wall of the container. The bottom
peripheral profile portion of the jig is then mated with
the outer annular wall. A reforming means, such as a
reforming roller is brought into engagement with the
substantially vertical wall: The reforming roller
rotates along the vertical wall and about an arcuate
path, affecting the angle of the substantially vertical
wall. The reforming roller farther reduces the radius of
curvature of the inner curved portion of the convex U
shaped portion.
According to one aspect of the invention, the
reforming means or roller affects the angle of the
substantially vertical wall, achieving a negative angle
from the vertical axis o~ the container.
i According to another aspect of the invention, the
reforming means or roller' is rotated about an arcuate
path equidistant from an axis that is coaxial with the
vertical axis of the container:
According to yet another aspect of the invention,
the refoz~aing means or roller has a peripheral configura
tion which, upon engagement with the substantially
vertical wall, reforms the substantially vertical wall to
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achieve the desired negative angle from the vertical axis
of the container.
In another aspect of the invention, an actuator
moves upwardly and towards the can to cause radial,
outward movement of a caroming surface. In this way, a
roller that moves as a result of the movement of this
caroming surface is caused to engage a substantially
vertical wall. This roller may pivot, about a horizontal
pivot point, from an inward non-engaging position to a
radially outward position where the roller engages the
substantially vertical wall.
In a further aspect of the invention, an annular
recess is formed in the radially outward portion of the
convex U-shaped portion, as by a roller, to further
increase the container's resistance to pressure.
This application is also directed to an apparatus
which can be used to practice the method of the inven-
tion, and the container formed by the method and appara-
tus of the invention. The apparatus reforms the bottom
wall of a container, and comprises means for supporting
the container for reforming and a reforming tool for
pressure engagement with the bottom wall to reform that
~ttom wall:
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Ar~ef Description Of The Drawings
Figure l is a top view of a pivoting apparatus
for reforming a can bottom in accordance with the
invention, and in a radially inward, non-engaging
position. . '
Figure 1A is a view of the apparatus..of Figure 1,
but with the rollers in a radially outward position and
engaging the wall of a container.
Figure 2 is a side-sectional view of the appara
tus of Figure l, and with a container shown in solid
lines above the apparatus and in phantom lines in place
for processing by the apparatus.
Figure 3 is a detail of a portion of the appara
tus of Figure 2, showing the pivot pin about which the
roller pivots.
Figure ~ is a top view of a second pivoting
embodiment of the apparatus in accordance with the
invention.
Figure 5 is a side-sectional view of the appara
tus of Figure 4, and with a container shown in solid
lines above the apparatus and in phantom lines in place
for processing by the apparatus.
Figure 6 is a top view of a third pivoting
- embodiment of the apparatus in accordance with the
invention.
Figur~ 7 is a side-sectional view of the appara-
tus of Figure 6, and with a, container shown in solid
lines above the apparatus and in phantom lines in place .
for processing by the apparatus:
'Figure s is a side perspective view of a
container which is suitable for treatment by the process
and apparatus,of the invention.
Figure 9 is an enlarged view of the lower left
hand corner of the container of Figure B, prior to
reforming.
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Figure 10 is an enlarged view of the lower left
hand corner of the container of Figure 8, after refor-
ming.
Figure ii is a top view of a non-pivoting embodi-
went of the apparatus in accordance with the invention.
Figure 12 is a side-sectional view~of the appara-
tus of Figure ii, and with a container shown in solid
lines above the apparatus and in phantom lines in place
for processing by the apparatus.
Figure 13 is a top view of a second non-pivoting
embodiment of the apparatus in accordance with the
invention.
Figure 14 is a side-sectional view of the appara
tus of Figure 13, and with a container shown in solid
lines above the apparatus and in phantom lines in place
for processing by the apparatus.
Figure 15 is a detail of the roller and bearing
of Figure 14, taken along lines 15-15 of Figure 13.
Figure 16 is a top view of a third non-pivoting
embodiment of the apparatus in accordance with the
invention.
Figure 17 is a, side-sectional view of the appara
tus of Figure 16, and with a container shown in solid
dines above the apparatus and in phantom lines in place
for processing, by the apparatus.
Figure i8 is a detail of the actuator and dove-
tail slide portion of a portion of the apparatus of
Figure 16, taken along lines l8-18 of Figure i6.
Figure 19 is a side-sectional view of a fourth
1 non-pivoting apparatus in accordance with the invention,
including a single roller, and with a container shown in
solid lines above the apparatus and in phantom lines in
place for processing by th.e apparatus.
Figure 20 is a photographic profile of a cross
section of a lower portion of a can reformed by a prior
art process.
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Figure 21 is a photographic profile of a cross-
section of a lower portion of a can reformed by the
process of the present invention.
Figure 22 is a photographic profile of a cross
section of a lower portion of a "control" can prior to
ref orming . - w
Figure 23 is an enlarged cross-sectional view of
an alternative embodiment of a bottom profile of a
container with improved resistance of internal pressure.
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patailed Deaorf~tion Of The Preferred Embodiment
This invention is susceptible of embodiment in
many different forms. . The drawings and specification
show a preferred embodiment of the invention. It will be
understood, however, that this disclosure i's to be
considered an exemplification of the principles of the
invention. The inventors do not intend to limit the
broadest aspect of the invention to the illustrated
embodiments.
According to one aspect of the invention, the
performance characteristics of a container, such 'as
formed by normal drawing and ironing procedures,, are
improved by reforming the bottom end wall of the
container from the initial configuration. This initial
configuration is disclosed in the above-mentioned '582
patent and is shown in Figure 8.
As described and shown in Figures 9 and l0 of co-
pending International Application No. PCT/US90/00451,
after the fluted container has been necked, flanged,
internally spray coated and externally printed, the
bottom profile or countersink area of the bottom wall is
reshaped. This is done by reforming the inner wall of
the countersink to further improve buckle resistance and
decrease can- .growth.
In the prior co-pending application, the finished
drawn and ironed container'of Figure ii is supported in
a suitable jig that' has an internal opening which
corresponds to the outer peripheral diameter of the
~,, , container. The jig .has a lower profile portion that
conforms to the-wcountersink wall portion at the bottom
wall of he container.
A plug-is inserted into the upper end of the
opening and securely held in the top of the container.
During processing, this container is rotated about its
axis: The bottom peripheral profile of the jig is in
extended contact with the container bottom. A reforming
roller is brought into engagement with the substantially
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vertical wall of the domed end of the container and is
supported on a shaft. That shaft is designed to be
rotated along an arcuate path around the center axis for
the container . The roller has a peripheral conf iguration
which defines a substantially vertical upwardly and
outwardly tapered wall having a generally_arcuate upper
portion. The inner wall of the countersink is reformed
to a more vertical profile while the dome is stretched to
a small degree. The outer wall is held to its original
configuration. Alternatively, the outer wall could also
be reformed with the inner wall, as will be explained
below.
It was found in the co-pending application that
this reforming operation significantly improves buckle
resistance and decreases the amount of can growth, i.e.,
the amount that the bottom end wall is elongated when
pressure is applied internally of the container.
The container produced according to the method
and apparatus described in the co-pending application
exhibited significantly greater column strength, i.e.,
resistance to crushing by vertical loads applied to the
container side wall: That container also exhibited
significantly less container growth during internal
pressurization and -improved buckle resistance. The
aonta'iner constructed in accordance with that invention
was thus capable of being produced from stock flat disc
material having a significantly reduced thickness.
The present invention is a further elaboration
and refinement upon the invention described in the co
' pending~applicat'ion. The invention is directed to a
container 20, such as a drawn or drawn and roved
container shown in Figure '8. Such containers are well
known in the art and are generally described and shown in
U:S: Patent No. 4,685,582, issued to the assignee of the
present application on August 111987. This container
20 is symmetrical about a vertical axis 22. A generally
cylindrical side wall 24 parallel with this vertical axis
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forms the panel on which graphics, such as a battler's
trademark, may be printed. An outer annular wall 26
forms a transitional portion between this side wall 24
and a convex, U-shaped portion 28 that defines a flange-
s like ridge. The outer annular wall 26 and iJ-shaped
portion 28 enable these cans to be stacked~.,_ In particu-
lar, the bottom of a first can may be securely nested
into the top of a second can.
The container 20 also includes a preformed bottom
wall 30 including a center domed portion 32. An annular,
substantially vertical wall 34 joins the domed portion 32
to the convex U-shaped portion 28. This "substantially
vertical wall," for the purposes of this application, has
an angle from the vertical of 0 to +5 degrees, and may be
as high .as +10 degrees. A positive angle is shown by
angle C in Figure 9:
Various kinds of appar~.tus may be used to effect
the method of reforming the container 20, as that method
is described and claimed in the present application. As
may be seen in Figures i-3, one such apparatus includes
a plurality of rollers 36. In a preferred embodiment,
three rollers 36 may be used. The use of three rollers
36 has advantages over the use of fewer rollers, for
example, a single roller. These rollers 36 are used to
contact the annular, substantially vertical wall 34. The
use of one roller would concentrate the force transferred
from the roller 36 to the wall 34 in a single direction.
In contrast, three rollers 36 will spread the force on
this wall 34 over three points, thus imposing a net force
~ of zero ~on the can. A 'greater number of rollers also
results in a faster cycle for reforming. In the case of
three rotating rollers vs. one rotating roller, and
assuming that the rollers are being rotated about the can
bottom at the same circumferential speed, the three-
roller apparatus should accomplish its task in approxi-
mately one-third of the time necessary for the one-roller
apparatus.
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As may be seen in Figure 2 , each of these rollers
36 is indirectly secured to a pivot plate 38. Securing
the rollers 36 are a bearing clamp 40 and a bearing 42.
Each of the pivot plates 38 are designed to pivot
around their respective pivot pin 44 (Figure l) .' In this
embodiment, this pivot pin 44 is verticall~r.-disposed. As
will be seen in other embodiments, however, other pivot
pins may instead be horizontally disposed.
A tooling head collar 46 provides a support
surface for a jig 48, or lower can support. This jig 48
is removable from the tooling head collar 46 and may be
interchanged with another jig having a different shape to
accommodate containers having various different lower end
conf igurations . The j ig provides radially inward support
to counter the outward force of the rollers.
Each jig 48 is manufactured to accommodate and
support a given size container 20. Accordingly, a bottom
peripheral profile portion 50 of the jig 48 substantially
corresponds in shape to the outer annular wall 26 of the
container 20. As will be explained below, this bottom
peripheral profile portion 50 of the jig 48 is mated with
the outer annular wall 26 of the container 20. In the
embodiment shown in Figure 2 , it may be seen that the
lowermost part 52 of this jig 48 also corresponds in
shape to the radially outermost region of the convex U-
shaped portion 28. In this way, the jig 48 provides
greater support around the circumference of the container
20.
Supporting the bearings 42 and enclosing portions
of the reforming ro3,lers 36 are bearing housings 54.
These :bearing housings 54 are fixedly secured to their
respective pivot plates 38. Thus, the motion of the
pivot plates 38 and the bearing housings 54 is synchro
nous.
Movement of the pivot plates 38 and bearing
housings 54 is facilitated by a vertically movable
actuator ball 56. As shown in Figure 2, this actuator
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ball 56 is positioned in a first, non-engaging position.
In this position, the actuator ball 56 merely abuts
against caroming surfaces 58 on the bearing housing 54.
Upward, vertical movement urges the actuator ball
56 to a second position in which it contacts arid pushes
upwardly on caroming surfaces 58. As a..'result of the
shape of these caroming surfaces 58, this upward movement
causes the bearing housing 54 and pivot plate 38 to pivot
together about the pivot pin 44 in a radially outward
direction. This pivoting movement continues until
rollers 36 contact the annular, substantially vertidal
wall 34.
The rollers 36, upon contact with this wall 34,
rotate rapidly to force the wall from its configuration
as shown in Figure 9 to that shown in Figure 10.
Particularly, Figures 9 and to depict a vertical Line V-
V. Vertical line V-V is coincident with the vertical
axis of container 20. Figure 9 shows a container 20
before reforming. In this Figure 9, the wall is substan-
tially vertical and may even have a so-called "positive"
angle. With reference to Figure 9, a positive angle is
one in which wall 34 angles upwardly and to the right of
line V-V: An example- of a positive angle appears as
angle C in Figure 9.
After contact by rollers 36, as described above,
this wall 34 is reformed and may achieve a 'negative angle
A. Additionally, the radius of curvature R is reduced.
The results of reforming are shown, for example, in
Figure i0. As a result of this negative angle and
~ reduced~radius, as will be described below, container 20
has enhanced physical characteristics:
One.advantage of the apparatus as shown in the
present embodiments is that it is adaptable for
containers having various bottom sizes. In many instan-
ces, one three-roller mechanism will be useful for
reworking the inner walls of several different sizes of
cans. To the extent that a roller mechanism may not be
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useful for a particular size can, an advantage of the
present agparatus is that one need only change its
rollers to enable the apparatus to rework the inner wall
of the container.
In the apparatus of Figures i-3, the pivot pin is
substantially vertically disposed. As '.result, the
pivoting of the bearing housing 54 and.the pivot plate 38
occur in a horizontal plane. Other embodiments, as
described below, will include horizontal pivot pins,
causing pivoting of the bearing housing and pivot plate
in a vertical plane.
As may be seen in greatest detail in Figures 2
and 3, the reforming rollers 36 have a perimeter portion
60 that is downwardly tapered. It is this downwardly
tapered configuration 60 which, when rollers 36 are
placed against the substantially vextical wall 34,
results in the reformation of that substantially vertical
wall 34 to a wall having a negative angle.
After the completion of the reforming, the
rollers 36 are retracted from the wall 34 and return from
the position shown in Figure lA to the original position
shown in Figure 2. Each pivot plate 38 and bearing
housing 54 assembly returns to this original position as
a result of pressure from a compression spring 62.
A slight modification of the reforming apparatus
described above is shown in Figures 4 and 5. Each of the
components of the embodiments of Figures i-3 are corre-
spondingly numbered in' Figures 4 and 5, except that the
reference numerals for the corresponding components in
'''~ 30 ~ the latter figures include the suffix "a." The only
component which differs significantly is the spring.
Spring 62 of Figures i-3 is an~-extension spring, whereas
spring 62a of Figures 4-5:is a compression'spring. As a
result, the apparatus'of Figures ~-5 works in a slightly
different manner than the apparatus o~ Figures i-3.
Particularly, in Figures i.-3, upon completion of refor-
ming, the rollers 36 are retracted from the wall 34 and
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returned to their original position as a result of both
applied pressure from an.extension spring 62 and retrac-
tion of the actuator ball 56. In Figures 4-5, upon
completion of the reforming, the rollers 36a are retrac-
ted from the wall 34 and returned to their original
position as a result of both applied pressure from a
compression spring 62a and retraction of actuator ball
56a.
Still another embodiment is shown in Figures 6
and 9. This embodiment also includes three rollers 64.
As may be seen in Figure 7, each of these rollers 64 is
indirectly secured to a pivot plate 66. Securing the
rollers 64 are a bearing clamp 68 and at least one
bearing 70.
Each of the pivot plates 66 are designed to pivot
around their respective pivot pin 72. As may be seen in
Figure 7, this pivot pin 72 is horizontally disposed. As
a result, the pivoting of the bearing housing 74 and the
pivot plate 66 occur in a vertical plane.
As in the embodiment of Figures i-3, the embodi-
ment includes a tooling head collar 76 to provide a
support' surface for a jig 78, or lower can support. This
jig 78 is also removable from the tooling head collar 76
and may be interchanged with another jig having a
different shape to accommodate containers having various
different lower end configurations:
Movement of the pivot plates 66 and bearing
housings 74 is facilitated' by a vertically movable
;actuator,80: As shown ire Figure 7, this actuator 80 is
30' positioned in a first, non-engaging position. In this
position, the actuator 80 merely abuts against caroming
surfaces 82 on'the bearing housing 74.
Upward, vertical movement urges the actuator 80
to a second .position in which it contacts and pushes
upwardly on caroming surfaces 82. As a result, this
upward movement causes the bearing housing 74 and pivot
plate 66 to pivot together about the pivot pin 72 in a
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vertical plane and a radially outward direction. This
pivoting movement continues until rollers 64 contact the
annular, substantially vertical wall 34 of container 20.
After the completion of the reforming, the
rollers 64 are retracted from the wall 34 and return from
the position shown in the dotted lines of Figure 7 to the
original position shown the solid lines of Figure ?.
Each pivot plate 66 and bearing housing 74 assembly
returns to this original position as a result of pressure
from a coil spring 84. This coil spring 84 encircles and
is held upon a retaining post 86. The coil spring 84 is
tensioned by compressing it between the top, abutting
surfaces of bearing housings 74 and hex nut 88 secured to
retaining post 86.
Still other embodiments of the present apparatus
are depicted at Figures ii-19. As will be seen, the
apparatus of these embodiments does not include a pivot
pin for moving the rollers into engagement with the
vertical wall 34 of the container 20. In many other
respects, however, these apparatuses are similar to those
shown in Figures i-~.
For example, the apparatus of Figure ii includes
three rollers 90 secured to a bearing housing 92 with a
bearing 94 and a bearing clamp 96. The solid lines of
Figure i2. show these rollers in a radially inward
position, where the rollers 90 do not contact the
annular, substantially vertical wall 34. These rollers
90-are movably from this position to a radially outward
position where the roller contacts the annular, substan
~ tially vertical wall 34.
Bearing' housings 92 are spring-biased. In
particular, a tensioned garter spring 98 (Figure
encircles the lower periphery of bearing housings 92. In
their first, non-engaging position, as shown in the
dotted fines of Figure 11, the'housings 92 and their
related rollers 90 are retained by the garter spring 98
in a radially inward position.
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The second position of the bearing housings 92 is
shown in the solid lines of Figure ii. The housings 92
attain this position when actuator 100 is moved upwardly
against caroming surfaces 102 of housing 92. This upward
movement of actuator 100 pushes housings 92 ~radially
outwardly until rollers 90 contact the annular, substan
tially vertical wall 34. Upon completion of treatment of
the wall 34 with rollers 90, the actuator 100 is with
drawn and garter.spring 98 urges the bearing housings 92
back into their first position.
As in the prior embodiments, the embodiment~of
Figures 11 and i2 includes a jig 104 to support the
container along a bottom peripheral profile portion 106
that substantially corresponds in shape to the outer
annular wall 26 of the container 20. As in the prior
embodiments, the perimeter 108 of the rollers 90 also
include a downw~.rdly tapered configuration which, when
placed against the substantially vertical wall 34,
reforms that wall 34 to achieve a negative angle relative
to the vertical axis of the container 20.
Another three-roller, non-pivoting embodiment of
the apparatus of the invention is shown 'in Figures i3-i5.
Ir, this embodiment, the spring 110 is horizontally
disposed and acts along a horizontal plane. In particu-
lar, spring 110 is in contact with the bearing housing
.;112' to bias, that housing 112 in a radially inward
direction:
The apparatus of Figure 13 also includes three
y rollers 114 secured to bearing housing 112 with a bearing
~ 116 and a bearing clamp -118. These rollers 114 are
movable from'their first position, as shown in Figures
i3-i5; to a.radially outward position where the rollers
114 contact the annular, substantially vertical wall 34
of container 20.
Upward movement of actuator 120 pushes housings
112 radially outwardly until rollers 122 contact the
annular, substantially vertical wall 34. Upon completion
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of treatment of the wall 34 with rollers 122, the
actuator 120 is withdrawn and spring 110 urges the
bearing housings 112 back into their first position.
Still another non-pivoting embodiment of the
apparatus of the invention is shown in Figures 16-18. In
this embodiment, however, conventional ro..llers are not '
used. Rather, four radially moveable or expandable
segments 124 are mounted to the apparatus for radial
movement towards and away from the container 20. In the
dashed lines of Figure i6, these segments 124 are shown
in their normal, radially inward position. They are held
in this position by a plurality of horizontally tensioned
springs 126.
Each of these segments 124, which are an alterna
tive type of roller means, may be secured to a housing
128. When~an actuator 130 is moved vertically upwardly
against caroming surfaces 132, housings 128 are pushed
radially outwardly, as -shown in the solid lines of Figure
16, until roller segments 124 contact the annular,
substantially vertical wall 34. Upon completion of
treatment of the wall 34 with roller segments 124, the
actuator 130 is withdrawn and springs 126 urge the
housings 128 back into their first position.
A final version of a non-pivoting embodiment of
the apparatus wis shown in Figure i9 . In this embodiment,
only one roller 3s used. This roller 134 has a substan
tially larger diameter than the rollers of the other
embodiments. In fact', the diameter of this roller 134 is
in excess of 8.0 percent of the distance between opposite,
facing'walls 34. This distance is referred to as "D" in
Bigots i9.
Again, this embodiment includes a compression
spring 136 which acts along a horizontal plane. Spring
136 is in contact with the housing 138 to bias that
housing~138 in a rightward direction. Roller 134 is
movable from its first position, as shown in Figure i9,
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to a radially outward position where the roller 134
contacts the annular, substantially vertical wall 34.
In the embodiment of Figure 19, actuator 140 is
vertically movable, as in the apparatus of the previously
described embodiments. The actuator 140 encircles a
dovetailed collar 142, and this collar '1.42 is fixed.
Housing 138, however, is horizontally movable when it is
contacted by the upwardly-moving actuator 140. The
horizontal movement of the housing 138 is guided by a
dovetail groove in collar 142.
Housing 138 abuts against camming~ surface 146.
In addition, with reference to the directions depicted in
Figure i9, spring 136 biases the housing 183 to the
right. Thus, housing 138 is moved to the right along the
caroming surface 146. This rightward movement of the
housing 138 continues until the periphery of roller 134
contacts the wall 34 of container 20. Reforming takes
place in the same manner as with a three-roller appara-
tus, but at only one point along the wall 34.
Upon completion of treatment ofvthe wall 34 with
roller 134, the actuator 140 is lowered and the weight of
the housing/roller combination moves that assembly back
onto the collar 142, i:e:, to the first position of the
device. This collar 142 acts as a limit on the downward
movement of the housing 138. Ln this embodiment and in
the others, it is preferred that. the actuator 140 rotate
at the same speed as housing:138
A comparison of Figures 9 and i0 wild disclose
the differences in. containers before and after bottom
' reforming in accordance with the method of the present
imrentionParticularly, Figure 9 shows a container
before bottom reforming: The.wall 34 in this figure is
substantially vertical and may, in fact, have a slight
positive angle: For the left portion of ' the container
shown in Figure 9, a wall 34 having a Might positive
angle would angle upwardly and to the right from vertical
line V-V. Referring to Figure a and stated differently,
WO 93/01903 ~~t~'~~J PCf/US92/06198
F~
-22-
when wall 34 has a positive angle, diameter D1 is greater
than diameter D2.
As stated above, the container of Figure a that
may be reformed in accordance with this invention is
generally symmetrical about a vertical axis '22. The
container includes a generally cylindrical. side wall 24
parallel with the vertical axis 22. The container 20
also includes an outer annular wall 26, a convex U-shaped
portion 28, a preformed bottom wall 30, including a
center domed portion 32 and an annular, substantially
vertical wall 34 joining the domed portion 32 and the
convex U-shaped portion 2s.
The method of the present invention may be
described with reference to the various apparatuses shown
in the figures, including the apparatus of Figures i-3.
The method comprises several steps. The container 20 is
supported on a jig 4.8: This jig 48 has a bottom peri-
pheral profile portion 50 substantially corresponding in
shape to the outer annular wall 26 of the container 20.
The bottom peripheral profile portion 50 of jig
48 is mated with the outer annular wall 26: Reforming
rollers 36 are brought into engagement with the substan-
dally vertical wall 34. The reforming rollers 36 rotate
along the vertical wall 34 and about an arcuate path.
Through this:action,,the reforming rollers 36 affect the
angle of the substantially vertical wall 34. In particu-
lar, the angle of the substantially vertical wall 34 is
changed to a negative angle from the vertical axis of the
container'20. ,
' 30 ~ ' In this embodiment, the outer wall 148 is held
against movement >by the bottom peripheral profile portion
50 of 'j g 48 while he reforming means s brought into
'~ contact with the inner, substantially vertical wall 34.
In another embodiment, the outer wall 148 may
instead not be held against movement by the bottom
peripheral profile ;portion 50. In this case, the
internal forming force of the reforming means may also
WO 93/01903 21 '~ ~ PGT/US92/06198
-23-
cause the outer wall 148 to be reformed simultaneously
with the reforming of vertical, inner wall 34, i.e.,
while the reforming means is being brought into contact
with the inner wall 34.
As may be seen in Figure lA, the reforming
rollers 36 of this apparatus are rotated about an arcuate
path equidistant from an.axis that is coaxial with the
axis 22 of the container. Alternatively, as may be
appreciated from a review of Figure 19 and the above
description of that figure, the reforming roller 134 of
that apparatus may be rotated about an arcuate path that
is equidistant from an axis that is not coaxial with the
axis 22 of the container 20. This occurs because in
order to contact wall 34, the roller 134 is shifted to
the right of its position as shown in Figure 19.
In one aspect of the preferred method, the roller
has a peripheral configuration which, upon engagement
with the substantially vertical wall, reforms the
substantially vertical wall to achieve a negative angle
from the vertical axis of the container. Rollers having
such peripheral conf igurations are shown in Figures 2, 5,
7, i2, 14, 17 and 19
In another aspect of the preferred method, an
actuator is moved upwardly and;towards the can to move a
camanfng surface and its housing in a radially outward
direction:' In this way, a roller movable with the
ramming surface engages the substantially vertical wall.
In still another, aspect of the: preferred method,
the roller pivots about,a horizontal pivot point. In
'' 30 ~particul~r, the apparatus may include a horizontal pivot
point about which the roller pivots from an inward non
engaging position to a radially outward position wherein
the roller engages the substantially vertical wall.
After this method of bottom reforming, as may be
seen in Figure la; the wall 34 exhibits a slight negative
angle A. The preferred angle A for an ANC-2A Gan should
be no more than approximately -4 degrees from the
WO 93/01903 ~~~ ~ PGTlUS92106198. .,,
~~~ -24-
vertical line V-V. It is believed that enhanced
container characteristics could be attained by providing
wall 34 with an angle of as much as -8 to -10 degrees.
For the left portion of the container shown in Figure 10,
a wall 34 having, a slight negative angle would angle
upwardly and to the left from vertical line V-V.
Referring to Figure 8 and stated differently, when wall
34 has a negative angle, diameter,Di would be less than
diameter D2. The value of the preferred negative angle
will vary with each different type of container.
The embodiments above largely discuss rollers'or
other reforming tools which are moved to contact the
inner wall of the container. It should be understood
that for purposes of the invention, the phrase 'bringing
a reforming tool means into pressure engagement with [an]
inner, annular bottom wall to reform [the] bottom wall"
also includes and contemplates the movement of the
container into engagement with the reforming tool. This
phrase also contemplates the rotation of the reforming
tool against the inner wall, the rotation of the inner
wall about the reforming tool, or a combination of both.
Containers treated by the methods or apparatus of
the present invention exhibit distinctly superior
characteristics when compared with prior art untreated
containers. Actual tests were conducted with so-called
"ANC-2A" cans, manufactured by American National Can
Company: These cans have the general configurations
shown in Figures 8 and 9, and were made with aluminum
having a gauge of: 0:12Q. Prior to treatment of these
' cans by~the method and apparatus of the invention, they
exhibited the following characteristics:
WO 93/01903 ~ ~ ~ ~ ~ ~ ~ PCT/US92/06i98
-25-
Table 1
ANC-2A Dome Profile
Dome Growth
Dome After 90 Buckle Plate
Depth PSIG Strength Thickness
Minimum .394 .052 98 ' .0120
Maximum .396 .060 99 .0120
Average .396 .054 98 .0120
,
Spec/Aim .394 .064 90 Ref.
+.004 Max. Min.
After treatment of these cans by the method and
one roller apparatus of the invention, they exhibited the
following characteristics:
Table 2
ANC Reformed Dome
Profile
Dome Growth
Dome After 90 Buckle Plate
Depth PSIG Strength Thickness
Minimum .398 .005 110 .0120
Maximum .401 006 113 .0120
Average ~ .400 :006 112 .0120
Spec/Aim N/A .064 9Q Ref.
Max. Min:
As
can
be
seen
from
a
comparison
of
these
Tables,
buckle'
strength
of
treated!
cans
increased
from
an
average
of
about
99
o
an
average
of
112.
The.,
growth
in
the
dome,
which
results
in
a
downward
extension
of
the
U-
shap~d
portion
28
of
the
container
of
Figure
9,
decreased
iaarkedly
from
an
average'of
0:055
to
0.006
inches.
When
these
same
tests
were
conducted
with
cans
produced
from
0.110
gauge
aluminum,
buckle
strength
increased
from
an
average
of
90
to
an
average
of
98.
Dome
growth
tests
after
90-PSIG
were
not.meaningful,
as
WO 93/01903 ~~~'~ ~J PGT/US92/0619~.."~
-26-
the non-reformed cans failed and buckled at 90 PSIG or
less.
A number of standard ANC-2A cans were reformed.
In the first set, the 'outside of the countersink was
reformed in accordance with a CMB method and its results
are shown in Table 3. A photographic prgfile of a lower
portion of one of these cans is shown in Figure 20.
Table 3
Body Strength
206/211 x 413 CMB
Reformed Dome
Cans
Dome Growth
Dome After 90 Buckle Plate
Depth PSIG Strength Thickness
Minimum .385 .008 104 .0120
Maximum .395 .012 109 .0120
Average .392 .010 106 .0120
Spec/Aim N/A .064 90 Ref.
Max. Min.
Vertical Crush Sidewall Thickness
Minimum 266 .0045
Maximum , 292 .0046
Average 279* .0046
Spec/Aim 250
Min.
- ,The second set of cans was reformed on the inside
of the countersink in accordance with the present
invention and its results are shown in Table 4. A
photographic profile of a lower portion of one of these
cans is shown in Figure 21.
CVO 93/01903 ~ ~ ~ ~ ~ ~ ~ , PCT/US92/06198
-27- _
Table 4
Body Strength
206/211 x 413 ANC
Reformed Dome
Cans
.
Dome Growth
Dome After 90 Buckle 'Plate
Depth PSIG Strength Thickness
Minimum .397 .003 104 .0120
Maximum .410 .007 114 .0120
Average .404 .004 110 .0120
Spec/Aim N/A .064 90 Ref.
Max. Min.
Vertical Crush Sidewall Thickness
Minimum 305 .0045
15
Maximum 321 .0047
Average 313-* ,.0046
Spec/Aim 250-
Min.'
WO 93/01903 ~ ~ PGT/US92/06198 ~,~
..
-2g-
Table 5
Body Strength
206/211 x 413 ANC-2A
Control Cans
Dome Growth
Dome After 90 Buckle 'Plate
Depth PSIG Strength Thickness
Minimum .396 .042 98 .0120
Maximum .398 .059 99 .0120
Average .397 .048 99 .0120
Spec/Aim .394 .064 90 Ref.
.004 Max. Min.
Vertical Crush Sidewall Thickness
Minimum 310 .0045
Maximum 322 .0046
Average 317* .0046
Spec/Aim 250
Min:
As
may
be
seen
by
a
comparison
of
these
Tables,
dome
growth
in
the
untreated
can
of
Table
5
averages
0.050
inches.
Both
reformed
cans
show
improvement,
but
the
gverage
dome
growth
of
the
-can
reformed
in
accordance
with
the
present
invention
is
significantly
superior
(0.005
vs.
0.01'0
inches).
Buckle
strength
is
also
somewhat
improved
(109
vs:
106).
Finally,
while
average
'
vertical
crush
of
the
present
reformed
cans
(
313
)
remains
virtually
the
same
as
the
GOntrol
can
(317);
average
vertical
crush
drops'significantly
(279)
after
reforming
by
the
CMB
method.
As
iaay
be
seen
by
a
comparison
of
Figures
20
and
21,
the
,can
that
has
been
reformed
in
accordance
with
the
present
invention
is
less
sharply
peaked
along
its
WO 93/01903 ~ ~ ~ ~ ~ PCT/US92/06198
f ~ .':; .': .1 ~8 k . .
w.'~':w bottom. As a result, this can will exhibit more stabi-
~~1~~'~r~illen moving along fill lines.
An alternative embodiment of the bottom profile
is disclosed in Figure 23. In this embodiment, addi
tional strength is achieved by reforming the outer wall
148'. Part of the buckle phenomenon is~that when the
countersink wall inverts, a countersink diameter change
takes place. Thus, a spun in annular recess 150 on the
outer wall 148' will increase the container's 20 resis-
tance to pressure. The annular recess 150 may be formed
continuously around the outer wall 148' or as a plurality
of segments spaced circumferentially around the outer
wall 148'. The annular recess 150 is preferably formed
by pressure engagement of the outer wall 148' with a
forming tool 152. The annular recess preferably has an
arcuate cross-sectional shape.
While the specific embodiments have been demon-
strated and described, numerous modifications come to
mind without markedly departing from the spirit of the
invention. The scope of protection is, thus, only
intended to be limited by the scope of the accompanying
Claims.
;.
.,
." .. .. , ,
~E;'~f~.at%'' .y ,.~ , ~., s . ~r~
W n. ..Y s.. ~i i : ,
