Reforming necked-in portions of can bodies

A method for reforming at least a portion of a multiple necked-in can body to provide at least an essentially right cylindrical-shaped portion adjacent a last necked-in portion by contacting at least the portion adjacent above and below the last necked-in portion with a rotating roll and providing relative movement of the periphery of the can body with respect to the rotating roll.

BACKGROUND 
This invention relates to a method of making a multiple necked can body, 
and more particularly to a method of reforming at least a portion of a 
multiple necked-in portion to provide at least an essentially right 
cylindrical-shaped portion adjacent the last necked-in portion. 
Methods of making two-piece cans by combining a drawn and ironed can body 
with a circular can end are well known. In these methods, the can user 
fills the can body and then typically attaches the can end to the can body 
by a method known in the trade as double seaming. With the ever-increasing 
use of such cans, particularly for packaging beverages, there has been an 
intensive effort made by the manufacturer to reduce the weight or amount 
of material in the can. 
One such effort has been in the direction of reducing the amount of metal 
in the can end by reducing the diameter of the open end of the can body 
which results in using less metal in the can end. The process of reducing 
the diameter of an open end of a tubular body is known as necking and is 
accomplished generally by one of two methods. In a spin-form method, the 
tubular body, such as a can body, for example, is placed upon a rotating 
mandrel and as the can body rotates, a tool is impinged against the 
periphery of portion of the body to be necked in. The tool is advanced 
inwardly toward the axis of the can body along an arc of predetermined 
radius until the desired reduction in diameter is achieved. In a push-form 
method, the closed end of the can body is mounted in a fixture in axial 
alignment with a female forming die. By axial movement of either the 
fixture or the forming die, the can body is moved into the forming die 
which is configured to neck a portion of the open end of the can body by 
forming the metal along an arc of predetermined radius until the desired 
diameter is reached. 
In either method there are limits as to the amount of diameter reduction 
that can be made in a single necking operation because the inward forming 
puts the metal in compression. Since the metal being formed in a can body 
is relatively thin, only a slight reduction in diameter can be made 
without causing the metal to wrinkle along the formed surface. 
It has been discovered, however, that by making separate, sequential 
necking steps, a far greater reduction in diameter can be made without 
wrinkling than if the necking were done in a single step. This discovery 
has led to methods known as multiple necking and further categorized by 
the number of necking steps employed, double necking and triple necking, 
for example. Multiple necking produces a portion, extending upwardly from 
a lower cylindrical portion of the can body, comprised of segments having 
progressively smaller diameters stacked one on another. The axial extent 
of such portion is commonly referred to as the stack height. An 
essentially right cylindrical portion extending upwardly from such 
segmented portion to the flange of the can body is commonly referred to as 
the neck. 
Although multiple necking is advantageous to achieve a maximal reduction in 
diameter and thus lessen the amount of metal required to make a can end, 
some disadvantages are introduced as well. For example, in a can of a 
given length, having a portion of the can of reduced diameter obviously 
decreases the volume available for the can contents. It is desirable, 
therefore, to keep the total extent or axial length of the necked-in 
portion, including the neck, to a minimum. This means that in each 
separately necked-in portion the smallest forming radius possible that can 
be used without wrinkling the metal should be employed, and the necked-in 
portion of the can should be confined to the smallest possible portion of 
can length adjacent the can end to be closed by double seaming. In the 
view of at least some packagers of carbonated beverages, however, the 
slightly rippled appearance resulting from necking to produce a multiple 
necked can detracts from the aesthetics of the package. Furthermore, some 
packagers of carbonated beverages believe that maximizing the neck length 
of a multi-necked can is advantageous in applying a commonly used 
multi-pack plastic carrier adjacent the ends of the cans. 
Heretofore, in providing a multiple necked can, it has been considered 
desirable to minimize the extent of the neck immediately adJacent the can 
bead because it was believed that the overall length of the necked-in 
portion would necessarily have to be increased for each added increment of 
neck. It may be seen that increasing the overall length by adding to the 
neck, without altering the configuration of the necked-in portions below 
the neck, would either necessitate an overall increase in the length of 
the can or lower the position on the can at which the multiple neck 
forming operation is begun. Neither of these alternatives is considered to 
be desirable in a multiple necked can. 
It would be desirable, therefore, to provide a method for making a 
multi-necked can body having a longer neck adjacent the annular bead of 
the double-seamed end without increasing the overall length of the 
necked-in portion of the can body. 
SUMMARY OF THE INVENTION 
In this invention a can body is multiple necked and at least a portion of 
the multiple necked-in portion is reformed thereafter. Such reforming may 
be accomplished before flanging of the open end of the can body, after 
flanging, during double seaming of a can end to the open end of the can 
body, or after double seaming. 
In the practice of a method of this invention, a multiple necked-in can 
body is supported axially and restrained from axial or lateral movement. A 
rotating roll adapted for lateral movement with respect to the can body 
contacts at least a portion of the can body adjacent above and below the 
last necked-in portion of the can body and relative movement of the 
periphery of the contacted portion with respect to the roll is provided. 
The rotating roll is adapted to at least reform the portion of the can 
body adjacent above and below the last necked-in portion into an 
essentially right cylindrical-shaped portion. Thus, an essentially right 
cylindrical-shaped neck portion is provided adjacent the bead on a 
double-seamed can without increasing the length of the stack height. 
The terms "essentially right cylindrical shape" and "essentially right 
cylinder" as used in reference to reforming a can body by a method of this 
invention are intended to mean the shape of the reformed portion after the 
reforming method is completed. It is well known that some materials 
exhibit spring-back characteristics. That is, after being formed into a 
particular shape and the forming force is removed, the material tends to 
return to its original shape which alters to some degree its formed shape. 
During the course of reforming a portion of a can body by a method of this 
invention, at least some part of the reformed portion may spring back, and 
thus the terms "essentially right cylindrical shape" and "essentially 
right cylinder" are intended to include the shape of the reformed portion 
after spring-back, if any, has occurred. 
In a further aspect of the invention, a portion of the can below and 
adjacent the second necked-in portion is reformed into a frustoconical 
portion having a substantially uniform inwardly curving wall section. 
As has been previously noted in forming a thin wall metal can body by 
necking, the amount of forming is limited by the susceptibility of the 
metal to wrinkling. It is apparent that thin metal sections are extremely 
sensitive to the amount of cold work that may be absorbed without 
wrinkling, cracking, fracture or otherwise generating a flaw in the formed 
metal. Since reforming a previously formed portion adjacent a necked-in 
portion inherently involves adding cold work in the reformed portion, 
reforming of such a portion has heretofore been avoided to prevent the 
likelihood of damage from the added cold work. It has been surprisingly 
discovered, however, that a previously formed portion of a thin wall metal 
can body can be reformed into an essentially right cylinder shape by a 
process of this invention. 
It is an object of this invention to provide a method for making a 
multi-necked double-seamed can having a neck adjacent the double-seamed 
bead of the can of a suitable length for applying a multi-pack carrier. 
It is also an object of this invention to provide a method of making a 
multi-necked can body closed with a can end by double seaming which 
assures that an essentially right cylinder neck portion is provided 
adjacent the can bead without increasing the overall height of the can. 
It is a further object of this invention to improve the aesthetics of a 
multi-necked can. 
These and other objects and advantages of the invention will be more 
apparent with reference to the following description of a preferred 
embodiment of the invention and the appended drawings.

DESCRIPTION OF A PREFERRED EMBODIMENT 
In the practice of a method of this invention, a multiple necked can body 
having the typical flanged and necked-in configuration shown in FIG. 1 is 
provided. The can body 10 includes first 12, second 14 and third 16 
necked-in portions or annular steps, an essentially cylindrical neck 17, 
and a flanged portion 18 which may be produced by either a push-form or 
spin-form process, both processes being known to those skilled in the art. 
Intermediate the necked-in portions 14, 16 is an outwardly projecting 
curved portion 15, and intermediate necked-in portions 12, 14 is an 
outwardly projecting curved portion 13. The dimensions relative to the 
necked-in portions 12, 14, 16, the outwardly projecting curved portions 
13, 15, the neck 17, and the flanged portion 18 will vary depending on the 
size of the can body, the wall thickness of the metal in the forming areas 
and the particular metal being formed, but generally the dimensions will 
be such as to assemble a can by double seaming as shown in partial cross 
section in FIG. 2. A bead 22 around the periphery of the open end of the 
can body 10 is formed of layers of metal of the can body 10 and circular 
end 20 by a process known as double seaming. It may be seen that most, if 
not all, of the neck 17 is incorporated into the can bead 22, and the can 
body portion 24 immediately adjacent the bead 22 is of a frustoconical 
shape and is a transition section between the third or last necked-in 
portion 16 and the neck portion 17 incorporated into the bead 22. A can of 
this embodiment is generally referred to as a short neck can since it 
embodies a minimal axial length of a formed neck portion 17 and little, if 
any, if the neck is below the can bead after double seaming. 
The difference between a can assembled with a can body reformed by a method 
of this invention and a can assembled with an unreformed can body may be 
seen by comparing FIG. 3 with FIG. 2. In FIG. 3, the transition portion 24 
adjacent and above the last necked-in portion 16, the last necked-in 
portion 16 and the outwardly projecting curved portion 15 adjacent and 
below the last necked-in portion shown in FIG. 2 have been reformed, as 
will be explained later, to produce an essentially right cylinder portion 
28 adjacent the can bead 22 which substantially lengthens neck 17 without 
increasing the overall axial length of the necked-in portion. 
Reforming of a previously formed portion of a can body of this invention 
will now be explained with reference to FIGS. 4, 5 and 6. 
Referring first to FIG. 4, a can body 10 is mounted on a support (not 
shown) that is adapted to rotate the can body about its longitudinal axis. 
A plug or seaming chuck 30, coaxially aligned with the can body and also 
adapted to provide the rotational drive force to rotate the can body about 
its axis, forcibly engages the can end 20 with the can body 10 and 
prevents axial and lateral movement of the can body. The can end 20, prior 
to double seaming, has an outwardly projecting annular flange 32 having 
sufficient extent to form a double-seamed bead 22 as shown in FIG. 3. 
A first seaming roll 34 is mounted adjacent the can body 10 and is adapted 
for rotation about a central axis parallel to the longitudinal axis of the 
can body, and the seaming roll is also adapted for lateral movement toward 
the can body as indicated by the directional arrow. To initiate forming 
the bead 22 (shown in FIG. 3), the seaming chuck 30 rotates the can body 
10 about its axis as the seaming roll is advanced toward the can body. As 
a result, an annular, planar surface 36 of seaming roll 34 contacts the 
upper surface of the can end flange 32 and causes the seaming roll 34 to 
rotate in the opposite direction, and with continued advancement of the 
seaming roll, the flange is directed into the curved, annular forming 
recess 38 of the seaming roll 34. 
Referring now to FIG. 5, the first seaming roll 34 is shown at the point of 
its furthest advance toward the can body. An annular surface 40, tapering 
inwardly toward the roll axis, is provided on seaming roll 34 to avoid 
contacting the outwardly projecting portion 15 during this initial seaming 
step. As may be seen, the forming recess 38 acts upon the can end flange 
32 and can body flange 18 to fold and form the flanges preparatory to 
completing the final forming of the bead 22 (shown in FIG. 3). 
After partial forming of the double seam as shown in FIG. 5, the first 
seaming roll 34 is retracted and a final seaming roll 42 is positioned 
adjacent the can body 10 as shown in FIG. 6. The final seaming roll 42 is 
adapted to rotate about its central axis which is parallel to the 
longitudinal axis of the can body 10, and the final seaming roll is also 
adapted to move laterally toward the can body as indicated by the 
directional arrow. In originating the final step in double seaming and 
reforming of a previously necked-in portion of the can body 10, the 
seaming chuck 30 again rotates the can body 10 about its axis as the 
seaming roll 42 is advanced toward the can body. An annular, planar 
surface 36 contacts an upper surface of the partially deformed can end 
flange 32 and causes the seaming roll 42 to rotate in the opposite 
direction, and the partially deformed can end flange 32 is directed into a 
curved annular forming recess 46 which is contoured to provide the 
finished form of the annular bead 22 (shown in FIG. 3). Projecting 
downward from the forming recess 46, an essentially right cylindrical 
reforming surface 48 is provided to bear against the outwardly projecting 
portion 15 and reform such surface into an essentially right cylindrical 
surface as the seaming roll 42 advances toward the can body axis. 
Referring now to FIG. 7, the final seaming roll 42 is shown at its point of 
furthest advance in forming the double-seamed annular bead 22 while 
reforming the outwardly projecting portion 15 (shown as dotted lines) into 
an essentially right cylinder portion 28 and an outwardly flaring 
transition portion 50 connecting with the second necked-in portion 14. 
By a method of this invention, a second portion of a multiple necked can 
body may be reformed as well as the portion adjacent the can bead, as may 
be seen with reference to FIG. 8. In FIG. 8, the final seaming roll 42 is 
shown at the completion of its lateral advance toward the can body 10. The 
can bead 22 has been formed by the seaming roll 42 in the same manner as 
has been previously described in reforming the portion adjacent the bead 
22 while double seaming a can end. It may be seen in FIG. 8 that the 
reforming surface 48 of the final seaming roll 42 extends downwardly from 
the annular bead forming recess 46 a sufficient distance to bear against 
both the outwardly projecting portion 15 and the outwardly projecting 
portion 13 (shown in dotted lines) as the roll 42 advanced laterally in a 
direction toward the can body. From the force of the reforming surface 48 
against the outwardly projecting portions 15, 13, and connecting necked-in 
portion 14 therebetween, the can body 10 has been reformed to provide an 
essentially right cylindrical-shaped portion 28 adjacent the bead 22 and a 
transition portion 50 flaring outwardly from the right cylindrical portion 
28 to the first necked-in portion 12. 
An essentially right cylindrical-shaped portion adjacent the bead of a 
closed can may also be provided by a process of this invention after the 
can has been closed by double seaming. Referring to FIG. 9, a can body 10 
is shown with a can end 20 double seamed to the can body to form a bead 22 
in a manner that has previously been described. The can body 10 is mounted 
on a support (not shown) that is adapted to rotate the can body about its 
longitudinal axis. A seaming chuck 30 coaxially aligned with the can body 
and also adapted to rotate the can body about its axis is impinged against 
the can end 20 with sufficient downward thrust to prevent any axial or 
lateral movement of the can body. It may be seen that the support system 
and seaming chuck 30 may be those that were employed in double seaming the 
can end to the can body. 
In this embodiment of producing an essentially right cylindrical-shaped 
portion of the can body adjacent the bead, a reforming roll 52 having an 
annular reforming surface 48 is provided and the roll is adapted to rotate 
about its axis which is parallel to the can body axis and it is also 
adapted for lateral movement toward the can body as shown by the 
directional arrow. In FIG. 9, the roll 52 is shown at the point of its 
furthest lateral advancement at the completion of its reforming action. 
Preparatory to reforming a portion of the can body by a process of this 
invention, the reforming roll 52 is positioned adjacent the can body 10 
but spaced apart therefrom so that it is not in contact with the can body 
as shown in dashed lines. With the can body 10 rotating about its 
longitudinal axis, the reforming roll 52 is advanced laterally toward the 
can body in a direction indicated by the arrow. It is to be noted that as 
roll 52 advances laterally, contact with the can bead 22 is avoided. With 
advancement of roll 52, the reforming surface 48 contacts the outwardly 
projecting portion 15 of the can body causing the reforming roll to rotate 
in the opposite direction, and portion 15 is reformed into essentially 
right cylindrical portion 28 adjacent the can bead 22 and a portion 50 
flaring outwardly from the essentially right cylindrical portion 28 to 
necked-in portion 14. It is evident that reforming roll 52 could be 
adapted to extend the reforming surface 48 a distance sufficient to bear 
against outward projection 13 and reform an additional necked-in portion 
of the can body, as has been previously described. 
A method of this invention also includes reforming necked-in portions of a 
multiple necked-in can body before or after flanging the open end of the 
can body. Referring now to FIG. 10, a can body 10 having first, second, 
third or last necked-in portions, as has previously been described, and a 
substantially cylindrical open-end portion 19 extending upward from the 
last necked-in portion 16 is supported on a platform (not shown). A plug 
30 has a portion 31 adapted to fit within the cylindrical open end 19 of 
the can body and an outwardly extending ledge 33 bearing upon the top edge 
of the can end to restrain the can body from axial movement. A cylindrical 
sleeve 37 adapted for axial movement independent of the plug 30 is 
provided to prevent lateral movement of the open-end portion 19. A 
reforming roll 52 having an annular reforming surface 48 is adapted to 
rotate about its axis and is also adapted for lateral movement with 
respect to the can body, as shown by the directional arrow. The plug 30 
and support platform are adapted to rotate with one or the other, or both, 
providing drive to rotate the can body 10 about its longitudinal axis. In 
FIG. 10, the roll 52 is shown at the point of its furthest lateral 
advancement at the completion of its reforming action. The position of the 
reforming roll 52 prior to contacting the can body 10 is adjacent to the 
can body but spaced away therefrom as shown by the dashed lines. 
Reforming of at least a portion of the multi-necked portion is accomplished 
in the same manner as has previously been described. In the embodiment 
shown in FIG. 10, the multiple necked portion shown in dashed lines is 
reformed into a generally arcuate portion 50. It may be noted that FIG. 10 
also shows how an allowance for spring-back may be made. The plug 30 is 
provided with a tapered surface 35 which allows the reforming roll 52 to 
be advanced laterally a greater distance inwardly into the can body than 
necessary to achieve the desired reformed contour. When the reforming roll 
is removed from contact with the can body, the reformed portion 50 springs 
back to assume the desired contour. 
Reforming a multi-necked portion of a flanged can body is as shown in FIG. 
11 and is the same in all respects as the description for reforming a 
multi-necked can body before flanging except plug 30 is adapted to 
accommodate the can body flange 18. Plug 30 in FIG. 11 includes a lower 
portion 31 adapted to fit within the can body open end. An upper portion 
of the plug includes a generally curved surface portion 39 adapted to 
substantially conform to the outwardly projecting flange 18 and an annular 
flange 41 extending downwardly at the outermost extent of the curved 
surface 39. The can body 10 is thus restrained by the plug 30 from axial 
or lateral movement. 
In the foregoing descriptions of modes of practice of this invention, the 
can body 10 is rotated about its longitudinal axis to provide peripheral 
movement of the multi-necked portion relative to the reforming roll. lt is 
evident that movement of the roll around the multi-necked portion of the 
can body could also be accomplished by holding the can body stationary and 
revolving the reforming roll around the can body. 
While the invention has been described in terms of preferred embodiments, 
the claims appended hereto are intended to encompass all embodiments which 
fall within the spirit of the invention.