Containers

In a method of forming a neck and flange at the open end of a thin cylindrical metal can body, the can body is held endwise under compression while an axial shortening force and a radial deforming force are applied to the can body sidewalls, by relative axial movement between the can body on the one hand and, on the other hand, an external forming tool and an internal tool edge which are kept at constant axial spacing from each other, so that the neck and flange are formed in free space without any need for internal or external tools shaped to the required profile; any desired shape can be obtained by varying the characteristics of the relative axial and radial motions.

This invention relates to containers; to components for such containers in 
the form of cylindrical one-piece metal can bodies having an open end 
terminating in an outwardly directed peripheral flange merging with a 
circumferentially-extending neck portion (the can body being hereinafter 
referred to as a "can body of the kind hereinbefore specified"); to 
methods of forming said neck and flange in a can body of the kind 
hereinbefore specified; and to apparatus for forming the said peripheral 
flange and neck portion. 
The purpose of the peripheral flange is usually to provide an element to 
which a can end is secured after the can has been filled, this securing 
being done by deforming the end flange of the can body together with a 
peripheral flange of the can end so as to form a double seam. The neck 
enables the flange, and therefore the can end, to be of smaller diameter 
than if there were no neck; usually the radial depth of the neck is such 
that the double seam has an external diameter no greater than that of the 
cylindrical side wall. In some types of metal container, such as those 
having reclosable lids of the so-called "lever" or "pry-off" type, the 
member seamed on to the end of the can body is usually a ring in which the 
lid engages. 
The end neck may serve another purpose, which is to provide a convenient 
means whereby a carrier can engage the container; such carriers are 
designed to hold a plurality of containers and may be of, for example, 
paperboard or a flexible plastics material. The type of carrier which 
engages the neck of a container of the kind with which this specification 
is concerned usually has a horizontal web in which there are a plurality 
of holes, the periphery of each hole engaging below the above-mentioned 
container double end seam so as to support the container wholly or partly 
thereby. Where the container body is necked, the neck can be so shaped as 
to provide some measure of support and/or restraint for the carrier web 
around the hole in the latter, and to assist in locking the container to 
the web until the user wishes to pull it away from the carrier. 
Various methods have been proposed for forming an end neck and flange on a 
one-piece can body. Some methods involve moulding the neck and/or the 
flange by means of circumferentially extending moulds. Other methods 
involve rolling or spinning the neck and/or flange, using an external 
spinning roll co-operating with an internal member within the can body. In 
these latter methods as known to us, the can body is supported rigidly by 
an internal mandrel or the like; the internal member may be a spinning 
roll or it may be the mandrel which supports the can body. In one such 
method the neck and flange are formed simultaneously in a can body 
supported internally and rigidly by a mandrel or chuck of an expaning 
type, the neck and flange profile being formed by external spinning rolls 
co-operating with this mandrel. 
In another method, the can body is supported internally by an anvil and 
endwise by a spinning pilot, the neck and flange being formed by a 
profiled, external spinning roll which deforms the can body into a groove 
formed on the pilot and anvil, the roll being moved axially of the can 
body. 
In all these previously-proposed methods the final profile of the neck and 
flange is determined by the profiles of the tool elements used for forming 
them, in that the tool elements (i.e., moulds, spinning rolls, mandrels, 
anvil etc. are provided with working surfaces profiled to conform with the 
required shape of the neck and/or the flange, and the metal of the can 
body is deformed into conformity with these profiles. It is thus 
necessary, if a different shape is required, to change the tools so as to 
provide differently profiled tool elements. 
A method such as that mentioned above, in which an expanding mandrel is 
used enables end flanges and neck portions to be produced reliably and 
economically even on can bodies made in the thinner and harder metals 
currently in favour, in particular double-reduced plate which is usually 
tinplate, but which may, for example, be mild steel or blackplate suitably 
treated but not necessarily plated with another metal. The present 
invention is also especially suitable for use with these thinner and 
harder materials. 
According to the invention, in a first aspect thereof, a method is provided 
for forming a peripheral end flange at an open end of a cylindrical metal 
can body and a neck merging with said flange, said method including 
supporting the can body endwise in axial compression, and applying a 
radial force to the can body by a forming member whilst effecting relative 
rotation about the axis of the can body between the can body and the 
forming member, and applying an axial shortening force to the can body so 
as to deform the can body in free space, whereby progressively to form 
said metal flange. 
Preferably, the method includes the steps of: supporting the can body 
endwise in axial compression between a bottom support element, coaxially 
engaging the bottom of the can body and defining a main axis, and an end 
support member engaging a terminal edge of the body coaxially at said open 
end, with a pilot element extending coaxially into said body through the 
end support member, and effecting relative rotation about said main axis 
between, on the one hand, said can body, bottom support member, end 
support member and pilot element and, on the other hand, an external 
forming member whilst effecting relative radial movement between said can 
body and said forming member, relative axial movement between said can 
body and forming element, and relative axial movement between said end 
support member and bottom support element, whereby to apply an axial 
shortening force to the body and to maintain said endwise support, a 
constant axial spacing being maintained between a circumferential first 
tool edge of the pilot element and a second tool edge of the forming 
member, whereby at least part of said neck and flange are formed in free 
space by said second tool edge deforming the can body about said first 
tool edge as fulcrum. 
It is implicit in the method of the invention in its preferred form as 
above defined, that the profiles or shapes of the neck portion and end 
flange in the finished can body are produced by deforming the metal of the 
workpiece progressively along the length of the end portion; in effect the 
second tool edge works its way along the sidewall end portion, forming the 
required profile therein with the first tool edge engaging the inside of 
the end portion to provide a fulcrum point for the deformation effected by 
the second tool edge. 
It will be realised that a fundamental feature of the method of the 
invention as above defined is that, by contrast with previously-proposed 
methods mentioned hereinbefore, the profile or shape of the neck portion 
and flange does not rely on the provision of one or more tool surfaces 
formed with the required profile, because in the present invention the 
shape does not have to be formed by bringing the material of the 
workpiece, e.g. by moulding, rolling or spinning, into intimate engagement 
and therefore conformity with such profiled tool surface or surfaces, but 
is formed instead, in free space. This does not, however, exclude the 
possibility, within the scope of the invention, of some portion of the 
profile being in conformity with a profile of a tool edge. In general, 
however, by the present invention, the material is wrought in a manner 
such that it deforms to a shape determined partly by the characteristics 
of the axial shortening force and radial force, and therefore of the 
various relative motions, to which the workpiece is subjected, i.e., the 
shape of the neck portion and end flange, for a workpiece of a particular 
metallic material having a given thickness, sidewall length and diameter, 
predetermined by suitable choice of velocity variation and relative timing 
of the radial motion between the second tool edge and the workpiece in 
relation to the axial motion between the workpiece and the first and 
second tool edges. 
It will be realised that in its preferred form as above defined the method 
of the invention, at any instant during the process, provides contact in 
only three places between the end portion of the workpiece and the tooling 
used for forming the neck portion and flange, viz. at the terminal edge, 
to provide radial restraint for the edge and to guide it in its axial 
motion; at a single point on the inside surface of the end portion, by the 
first tool edge; and at a single point on the outside surface of the end 
portion by the second tool edge. It follows that, by varying the 
characteristics of the relative motions for a given workpiece, the shape 
or profile to be given to the neck and flange can be changed at will. In 
practice a wide variety of such shapes can be produced without any need to 
change parts of the tooling as would be necessary where the required 
profile depends on tooling parts having particular profiles. 
Preferably, the first tool edge is kept stationary and the second tool edge 
is moved radially with respect to the workpiece, the workpiece being moved 
axially with respect to the first and second tool edges in a direction 
such that the axial distance between the latter and the terminal edge of 
the workpiece decreases to zero. 
According to the invention, in a second aspect thereof, apparatus is 
provided for forming a peripheral end flange at an open end of a 
cylindrical metal can body and a neck merging with said flange, said 
apparatus comprising end support means adapted to support said can body 
coaxially and endwise in axial compression and to apply an axial 
shortening force thereto, and an external forming member for applying a 
radial force to the can body, said end support means and forming member 
being arranged for rotation relative to each other about the axis of the 
support means. 
Preferably the apparatus comprises: a bottom support element for coaxially 
engaging the bottom of the can body and defining a main axis; an end 
support member coaxially opposed to the bottom support element, for 
engaging a terminal edge of the can body at said open end; a pilot member 
extending through the end support member towards said bottom support 
element and having a circumferential first tool edge; and an external 
forming member having a second tool edge facing towards the said main axis 
and disposed at a constant axial spacing from said first tool edge, said 
end support member and bottom support element being arranged for axial 
movement relative to each other whereby to apply an axial shortening force 
to the can body, and said end support member being arranged for axial 
movement past the pilot element, and said forming member and end support 
member being arranged for radial motion relative to each other. 
Preferably the bottom support element comprises a lift pad for supporting 
the end of the workpiece opposite said open end, and the end support 
member is a limit ring adapted to engage the terminal edge axially and to 
restrain it radially, said lift pad and limit ring being capable of axial 
movement independently of each other. 
The pilot member is typically a mandrel or chuck having a circular edge to 
give contact substantially in a single plane transverse to the workpiece 
axis between said edge (being said first tool edge), and the workpiece. 
The forming member is preferably a roller, rotatable about its own axis and 
having a simple circumferential edge profile defining said second tool 
edge. This latter edge may be such as to give contact substantially in a 
single plane, transverse to the workpiece axis, at any instant between 
said second tool edge and the end portion of the workpiece. There may be 
two or more of said second tool elements. 
The invention also includes within its scope a metal can body of the kind 
hereinbefore specified, made by a method according to said first aspect of 
the invention; and also includes within its scope a container comprising a 
said can body and having an end closure member seamed to the peripheral 
flange thereof.

Referring to FIG. 1, apparatus for forming a peripheral flange 10' and a 
neck portion 11 of a can body 12 includes end support means (hereinafter 
described) for supporting coaxially therewith, and in axial compression, a 
hollow metal workpiece 13 in the form of a cylindrical metal can body. The 
latter is of the kind comprising a thin cylindrical seamless sidewall 14 
having an end portion 15 (shown in chain-dotted lines); the end portion 15 
has a terminal edge 16 defining an open end 17 of the workpiece. The 
workpiece 13 includes an integral bottom wall (not shown in FIG. 1) which 
may be of any known shape such as the reverse-domed type, part of which 
can be seen at 18 in FIG. 2. The upper or open end of the cylindrical 
sidewall 14 of the workpiece 13 is in this example slightly flared in the 
end portion 15 to define a small initial flange 19. The workpiece 13 is 
preferably of double-reduced tinplate or chemically-treated mild steel or 
blackplate. 
The support means comprises an end support member in the form of a limit 
ring 20 having at its lower end an annular rebate 21 for engaging the 
terminal edge 16 and the flange 10, and a bottom support member in the 
form of a lift pad 22, not shown in FIG. 1 but provided as in the 
arrangement of FIG. 2 to support the bottom wall 18 of the workpiece from 
below. The lift pad 22 and the limit ring 20 are arranged for controlled 
movement in the direction of the axis 23 of the workpiece 13, 
independently of each other in a manner which will become clearer from the 
description hereinafter with reference to FIGS. 2 to 6. 
The apparatus also includes a pilot member in the form of the mandrel or 
chuck 24 extending through the limit ring 20, and within the hollow 
workpiece 13, towards the lift pad 22. In this example the chuck 24 
consists of a simple disc having a first peripheral tool edge 25 which is 
slightly radiused; and a forming member in the form of a necking roller 26 
having a second tool edge in the form of a simple radiused circumferential 
edge profile 27, at a constant axial spacing from the tool edge 25. The 
necking roller 26 is rotatable about its own axis 28 in known manner, and 
is also arranged for relative radial motion between itself and the main 
axis 23 which is common to the workpiece 13, the limit ring 20 and the 
lift pad 22. This relative motion is obtained by controlled radial 
movement of the roller 26 as indicated by the arrow 29. 
The limit ring 20 and the lift pad, the workpiece 13 and chuck 24 are 
rotatable together about the axis 23. 
The operation of the apparatus will be more clearly understood by reference 
to FIGS. 2 to 6. The workpiece 13 is supported on the lift pad 22 and 
raised thereby (FIG. 2) until the terminal edge 16 of the workpiece 
engages in the limit ring rebate 21 as seen in FIG. 3. The limit ring 20 
at this stage is at its uppermost position, and the workpiece 13 is out of 
contact with the chuck 24. 
The workpiece 13 is now supported coaxially, in axial compression, by the 
lift pad 22 and limit ring 20; the latter provides radial restraint for 
the terminal edge 16. It will also be seen that the chuck 24 lies 
internally of the workpiece 13 and that the sidewall 14 of the latter lies 
between the chuck 24 and the necking roller 26 outside the workpiece. 
With the lift pad 22, limit ring 20, chuck 24 and workpiece 13 rotating as 
a unit (as indicated by the arrow 31 in FIG. 1), the lift pad 22 and limit 
ring 20 are moved downwards as indicated by the vertical arrows in FIGS. 4 
to 6, so moving the workpiece 13 down with them relative to the tool edges 
25 and 27. 
During this axial motion the necking roller 26, rotating continuously about 
its own axis, is moved radially. These axial (vertical) and radial 
(horizontal) movements of the workpiece 13 and roller 26 respectively are 
timed so that a point 32 (FIG. 3) on the roller edge surface 27 first 
makes contact with the sidewall 14 of the workpiece 13 just where the 
lower extremity 33 (FIG. 6) of the neck portion 11 is to be. 
As the vertical downward movement of the workpiece continues, further 
horizontal movement of the necking roller 26 causes the metal of the 
workpiece end portion 15 to be deformed (FIG. 4) in free space by 
co-operation between the tool edge 27 of the roller and the tool edge 25 
of the chuck, the edge 25 engaging the internal surface of the workpiece 
in a common radial (vertical) plane with the point of contact 32 between 
the edge 27 and the outer surface of the workpiece. The tool edge 25 
serves as a fulcrum for the controlled deformation of the metal in free 
space, to form a frusto-conical neck profile 34. If the radial movement of 
the necking roller 26 is now stopped whilst axial motion of the workpiece 
13 continues, a cylindrical neck profile 35 will be formed (FIG. 5) above 
the profile 34. 
FIG. 5 represents the end of the forming operation, the limit ring 20 
having reached its lowest position and the whole of the end portion 15 of 
the workpiece 13 having been formed into the neck portion 11 and 
peripheral end flange 10, the top surface of the latter being defined by 
the position of the internal tool edge 25. 
It will be seen from the foregoing that the limit ring 20 serves not only 
to restrain the terminal edge 16 in the radial direction and apply an 
axial shortening force thereto, but also to guide it in its axial motion 
so as to keep the still-undeformed part of the workpiece (viz. 36 in FIG. 
4) steady in its initial state. It will be appreciated that, in order to 
achieve this, the provision of the initial flange 19 is desirable, though 
not necessarily required in all cases. 
Whilst the lift pad 22 moves steadily downwards through a distance X during 
the forming operation, the limit ring 20 moves downwards through a 
distance Y which is greater than the distance X. The velocity 
characteristic of the movement of the limit ring 20 is determined by the 
rate at which metal is drawn away axially therefrom, and will vary 
according to the neck and flange profile required. It will be understood 
that this variation can be predetermined, and closely controlled by any 
one of a number of known techniques for the control of tools. In the same 
way the predetermined characteristics of the radial motion of the necking 
roller 26 can be closely controlled. It is of course possible to provide a 
characteristic motion of the lift pad 22 such that it does not move at 
substantially constant velocity. By arranging the vertical and horizontal 
movements respectively of the lift pad 22 and limit ring 20 and of the 
roller 26 to have predetermined velocity characteristics and by timing 
these movements in a predetermined manner relative to each other, any 
desired neck and flange profile can be obtained. 
In this connection it is to be noted that the chuck 24, limit ring 20 annd 
necking roller 26 constitute a tool set which may readily be fitted as a 
simple modification to a standard machine of a known type for necking can 
bodies by spinning, or for seaming end members to can bodies. Such a 
machine includes the lift pad 22, together with drives for rotating the 
seaming roll and for moving it radially; for rotating the chuck and lift 
pad; for moving the lift pad up and down; and for moving the chuck up and 
down. Since such machines are well known in the art, they do not need to 
be described in detail here; it will readily be appreciated that the drive 
for moving the chuck up and down may be coupled instead to the limit ring 
20 so as to effect vertical movement of the latter instead of the chuck 
24. Coupling these various drives together so as to control the 
characteristics as discussed above may be performed in any known manner. 
There may, for example, be provided three timed cams controlling 
respectively the vertical movements of the lift pad and of the limit ring, 
and the radial or horizontal movement of the necking roller, all the cams 
being driven from a constant-speed motor. Alternatively a simple 
electrical control system of the numerical, magnetic, tape or "peg-board" 
types may be provided to control the various drives; these systems have 
the advantage of being very readily re-programmable to a new profile of 
neck and flange. 
It will be appreciated that, as discussed earlier herein, it is the 
characteristics of the various relative motions of the tool elements 20, 
22, 25, 27, together with the inherent characteristics of the material and 
dimensions of the workpiece 13 itself, that determine the final profile of 
the neck portion 11 and end flange 10. The workpiece makes no contact with 
the chuck 24 except at the tool edge 25, although the forming of the 
radiused portion 37 joining the flange 10 to the cylindrical upper part 35 
of the neck portion 11 is in this example assisted by the provision of the 
radiused tool edge 27 of the necking roller 26. 
FIG. 6 shows the limit ring 20 returned to its upper position and the 
necking roller 26 to its disengaged position, whilst the lift pad 22 
descends to enable the finished can body 12 to be removed. 
Referring now to FIG. 7, a conventional spin necking or can end seaming 
machine, having the various drives discussed hereinabove, has a pair of 
arms 70 each adapted to carry a spinning or necking roller 71. A necking 
head base member 72 which is rotatable by a tubular spinning or necking 
spindle 73 (the member 72 and spindle 73 being indicated by chain-dotted 
lines), has a necking and flanging tool 74 secured thereto. The tool 74 is 
adapted to the method described above with reference to FIGS. 1 to 6 and 
comprises essentially a ring 75, secured to the member 72 by a hollow nut 
76; a chuck 77 secured by means not shown to the ring 75; and a limit ring 
78 which is mounted coaxially around, and for axial movement with respect 
to the ring 75 and chuck 77. The limit ring 78 is secured by a nut 80 to a 
vertical actuating rod 81 which is movable (by suitable conventional 
means, not shown) axially through the member 72 and ring 75. The limit 
ring 78 is constrained against rotation relative to the ring 75 by webs 82 
of the latter engaging slots (not shown) in the limit ring, but is 
rotatable with the actuating rod 81, which extends up through the necking 
spindle 73. Thus the whole tool 74, with the base member 72, is rotatable 
by the necking spindle 73, but the limit ring 78 is also movable axially 
by the actuating rod 81, which gives full positive control of the movement 
of the limit ring 78. The lift pad 22 is supported on a base member 83 by 
compression springs 79. The base member 83 is movable up and down as 
explained hereinbefore with reference to FIGS. 2 to 6. The springs 79 
serve to pre-load the workpiece against the limit ring 78 by an amount 
such as to induce a friction torque greater than the frictional torque 
induced by resistance of the workpiece to the necking operation. 
Operation of the apparatus, comprising the machine having the necking tool 
74 and rollers 71 of FIG. 7, is generally as in the embodiment described 
already with reference to FIGS. 1 to 6. The use of two necking rollers is 
preferred. 
Referring to FIGS. 8 to 11, these show four only out of many possible 
profiles of neck portions and end flange which may be obtained by methods 
and apparatus such as those described above. A fifth such profile is that 
shown in FIG. 6. In the profile shown in FIG. 8, the neck portion consists 
of a cylindrical portion 85 joined to the main part of the can body 
sidewall 14 by a generally-radial portion 86. The outside diameter of the 
end flange 87 is substantially equal to that of the sidewall 14. 
The profile shown in FIG. 9 enables an end closure member of substantially 
smaller diameter than that of the sidewall 14 to be secured to the can 
body by means of the peripheral end flange 90, the latter being joined to 
the sidewall 14 through a relatively long frusto-conical neck portion 91. 
FIG. 10 shows a more conventional profile in which a peripheral end flange 
100 is a continuation of a neck 101 having a C-shaped cross-section. 
Finally, FIG. 11 illustrates one example of a profile in which the neck 
portion comprises more than one neck 110, 111, joined by a circumferential 
bead 112.