Spin flow necking cam ring

A method and apparatus for spin flow necking-in a D&I can is disclosed wherein an externally located free spinning form roll is moved radially inward and axially against the outside wall of the open end of a trimmed can. A spring-loaded interior support slide roll moves under the forming force of the form roll as the latter slides along a conical forming surface of a second free roll mounted axially inwardly adjacent the slide roll. To prevent damage to the metal caused by excessive pressure contact between the form and slide rolls, the slide roll is axially retracted via a cam ring which initially contacts the form roll during radially inward necking movement.

TECHNICAL FIELD 
The present invention relates generally to apparatus and methods for 
necking-in container bodies preferably in the form of a cylindrical 
one-piece metal can having an open end terminating in an outwardly 
directed peripheral flange merging with a circumferentially extending neck 
and, more particularly, to an improved spin flow necking process and 
apparatus. 
BACKGROUND ART 
When two-piece aluminum draw and iron (D&I) beverage cans were first made 
in the mid-1960's, the cans were quite different from today's cans. Not 
only were the cans 70% heavier, the shape was also different. Since the 
aluminum can was competing against the three-piece steel can which it 
would eventually supplant, it necessarily had the same shape. The size of 
the 12-ounce beverage can in the mid-1960's was 211.times.413. Therefore, 
the can body was not necked prior to a flanging operation in which an 
outwardly extending peripheral flange was formed at one end of the can 
body to receive, and be seamed to, a can end after filling with beverage. 
The 211 diameter configuration (can-maker's terminology referring to a 
diameter of 2 11/16") caused two major problems in the two-piece aluminum 
D&I can. The first problem was split flanges. Specifically, in the 
flanging operation, the metal was expanded from the 2.6" body diameter to 
a 2.8" flange diameter, i.e., a 7.7% increase. This obviously create 
circumferential tension in the flange which resulted in a tendency for it 
to split. Split flanges resulted in leakage from the can seams which was a 
major problem. The second problem related to conveying the flanged cans. 
When adjacent cans were allowed to touch, flange damage would occur and 
conveying jams were frequent because of the way the cans would tilt when 
in flange-to-flange contact which created clearance between the can 
bodies. 
Although many improvements were made to lessen the adverse impacts of the 
foregoing problems, the solution which emerged in the mid-1960's was the 
necking process Necking reduced the diameter of the open end of the can 
prior to flanging which allowed a smaller end (e.g., a 209 end which is 2 
9/16" diameter in can-maker's terminology) to be used. The resulting 
configuration greatly reduced the tendency for split flanges since the 
flange diameter in the necked can is only 2.3% greater than the body 
diameter. Necking also made conveying the cans easier since, with only 
slight flange overlap, the cans would contact body-to-body. Seamed 209 
cans could contact body-to-body without tilting. 
The necking process was instrumental in the subsequent success of the 
two-piece D&I beverage can. In the decade following the introduction of 
the 209 necked can, the three-piece steel can virtually disappeared from 
the can beverage market. 
In the late 1970's, the necking process was revisited as a means of 
achieving further lightweighting and reduced costs. If the cans were 
necked to a smaller diameter, then a smaller, lighter, less expensive can 
end could be used. During the following years, the industry moved from the 
209 neck to a 206 neck. By the mid-1980's, most commercial can-makers 
considered the 206 can to be industry standard. 
Three different necking processes were used to produce the 206 aluminum 
can. In one process, a four-stage die necking procedure resulted in each 
successively formed neck reducing the diameter by about 0.085". In this 
process, four distinct necks are formed on the can. This process is called 
"quad-neck." Another process is a six-stage die necking process whereby 
each step reduces the diameter about 0.055" and the necks blend together 
in a continuous profile. This process is called "smooth die neck." The 
third type of necking process is a combination of either two or three die 
necks followed by a spin necking operation. Each of the die necking 
operations reduces the diameter by about 0.075-0.110" and the spin necking 
operation reduces it by 0.110". The spin necking process smooths all but 
the first die neck which leaves one obvious neck that blends into a 
continuous profile. This process is called "spin necking." 
A renewed interest in cost competitiveness has resulted in the production 
of even smaller diameter can ends. As can-makers ponder the possibility of 
a 204 can end and smaller necks, they necessarily revisited the can design 
criteria. First and foremost, the capacity of the can must be maintained 
without changing the can height or diameter. This means that as the neck 
diameter decreases, the neck angle would ideally become greater so as to 
maintain the neck shoulder location and not encroach upon the volume of 
the can. A side benefit of a steeper neck angle is reduced metal usage. 
Can-makers typically employed thicker metal in the neck area of the can to 
facilitate necking and flanging. Therefore, a steeper, shorter neck means 
reduced length for the thicker metal which results in the reduced metal 
usage. A third advantage of a steeper neck is increased billboard, i.e., 
the cylindrical portion of the can available for customer graphics. 
An additional consideration in the selection of a necking process is the 
diameter reduction capability for each step. The greater the reduction, 
the fewer steps are needed, thereby reducing costs and streamlining the 
process. Aesthetics is also a consideration. Finally, ease of 
manufacturing is a factor which must be considered in selecting a necking 
process. Any other advantages can be lost if productivity in the necking 
tooling is diminished because of a more critical necking process. 
The foregoing considerations led to the development of a process now known 
in the industry as "spin flow necking." A particularly promising spin flow 
process and apparatus are disclosed in U.S. Pat. No. 4,781,047, issued 
Nov. 1, 1988, to Bressan et al, which is assigned to Ball Corporation and 
is exclusively licensed to the assignee of the present application, 
Reynolds Metals Company. The disclosure of this patent is hereby 
incorporated by reference herein in its entirety. It concerns a process 
where an externally located free spinning forming roll 11 is moved inward 
and axially against the outside wall C' of the open end C" of a rotating 
trimmed can C to form a conical neck at the open end thereof. With 
reference to FIG. 1, a spring-loaded holder or slide roll 19 supports the 
interior wall of the can C and moves axially under the forming force of 
the free roll 11. This is a single operation where the can rotates and the 
free roll 11 rotates so that a smooth conical necked end is produced. In 
practice, the can is then flanged. The term "spin flow necking" is used in 
this application to refer to such processes and apparatus, the essential 
difference between spin flow necking and other types of spin necking being 
the axial movement of both the external roll 11 and the internal support 
19. 
More specifically, the spin flow tooling assembly 10 depicted in FIG. 1 
(corresponding to FIG. 1 of the Bressan et al '047 patent, supra) includes 
a necking spindle shaft 16a rotatable about its axis of the rotation A by 
means of a spindle gear 16 mounted to the shaft between front and rear 
bearings (not shown). The slide roll 19 is mounted to the front end of the 
necking spindle shaft 16a through a slide mechanism 28, keyed to the 
shaft, which permits co-rotation of the roll 19 while allowing it to be 
slid by the necking forces described more fully below in the axially 
rearward direction B' away from the eccentric freewheeling roll 24 located 
adjacent the front face of the slide roll. The axially fixed idler roll 
24, having an axis of rotation B which is parallel to and rotatable about 
spindle axis A, is mounted via bearings 16b and 23 to an eccentrically 
formed front end of an eccentric roll support shaft 18. This shaft 18 
extends through the necking spindle shaft 16a. The spindle shaft 16 is 
rotated by the spindle gear 16 without rotating the eccentric roll support 
shaft 18. 
The outer forming roll 11 is mounted radially outwardly adjacent the slide 
and eccentric rolls 19,24. 
The container slide roll 19 is shaped with a conical leading edge 19a 
designed to first engage the open end C" of the container C to support 
same for rotation about spindle axis A under the driving action of the 
necking spindle gear 16 which may be driven by the same drive mechanism 
driving each base pad assembly 29 engaging the container bottom wall. 
Slide roll 19 is also free to slide axially but is resiliently biased into 
the container open end C" via springs 20 which may be of the compression 
type. 
In operation, the container open end C" engages and is rotated by the slide 
roll 19. The eccentric roll 24 is then rotated into engagement with a part 
of the inside surface of the container side wall C' located inwardly 
adjacent the open end C". With reference to FIGS. 2A-2E, the external 
forming roll 11 then begins to move radially inward into contact with the 
container side wall C' spanning the gap respectively formed between the 
conical faces 19a,24e of the slide and eccentric rolls 19,24. More 
specifically, the side wall C' of the spinning container body C is 
initially a straight cylindrical section of generally uniform diameter and 
thickness which may extend from a pre-neck (not shown) previously formed 
in the container side wall such as by static die necking. As the external 
forming roll 11 engages the container side wall C', it commences to 
penetrate the gap between the fixed internal eccentric roll 24 and the 
axially movable slide roll 19, forming a truncated cone (FIG. 2B). The 
side wall of the cone increases in length as does the height of the cone 
as the external forming roll chamfer 11c continues to squeeze or press the 
container metal along the complemental slope or truncated cone 24e of the 
eccentric roll 24 as depicted in FIG. 2C. The cone continues to be 
generated as the external forming roll 11 advances radially inwardly (the 
slide roll 19 continues to retract axially as a result of direct pushing 
contact from roll 11 through the metal) until a reduced diameter 124 is 
achieved as depicted in FIGS. 2C and 2D. As the cone is being formed, the 
necked-in portion 124 or throat of the container C conforms to the shape 
of the forming portion of the forming roll 11. The rim portions 123 of the 
neck which extend radially outwardly from the necked-in portion 124 are 
being formed by the complemental tapers 11b,19a of the forming roll 11 and 
the slide roll 19 to complete the necked-in portion. 
A plurality of spin flow necking tooling assemblies embodying the 
above-identified tooling, or the improvements according to the present 
invention described hereinbelow, may be incorporated in a multi-station 
spin flow necking machine of a type disclosed in patent application Ser. 
No. 929,932 being filed concurrently herewith and commonly assigned, 
entitled "Spin Flow Necking Apparatus and Method of Handling Cans Therein" 
incorporated by reference herein it its entirety. 
The above-described spin flow necking process, while producing a large 
diameter reduction in the open end of the container C (e.g., 0.350"), has 
various drawbacks when applied to two-piece aluminum can manufacture. One 
drawback, for example, is grooving of the neck at the initial point of 
contact between rolls 11,19 in FIG. 2B which occurs on the inside of the 
container as a result of the small radii on the forming roll pushing past 
and against the small radii on the slide roll as the forming roll moves 
radially inwardly and axially rearwardly during the necking process along 
the chamfer 24e of the eccentric roll. Due to the spring force 20 urging 
the slide roll 19 toward the eccentric roll 24, the metal caught between 
these colliding radii which are forcefully pressed together under spring 
bias, actually results in the grooving phenomenon on both the inner and 
outer surfaces of the neck. On the inside surface, this grooving results 
in metal exposure (i.e., wearing away of the protective coating) which 
often allows the beverage to "eat through" the container side wall C'. It 
has also been discovered that such grooving often results in actual 
cutting of the metal as the form roll 11 is radially inwardly advanced 
from the position depicted in FIG. 2B to that of FIG. 2C. 
As the form roll 11 moves into its radially inwardmost position depicted in 
FIG. 2E, the spring pressure acting against the slide roll 19 in the 
direction of the forming roll disadvantageously results in pinching of the 
end of the flange-like portion 123 and undesirable thinning of the metal. 
In some cases, particularly when necking a can to smaller diameters (e.g., 
204 or 202), the edge is sometimes thinned down to a knife edge. 
It is accordingly an object of the present invention to prevent grooving of 
the container side wall or neck during the spin flow necking process. 
Another object is to control the interaction of the outer form roll with 
the inner slide roll to ensure that the form roll acts directly on the 
metal at appropriate instances while preventing excessive interaction 
which may result in grooving. 
Still a further object is to prevent excessive thinning of the flange type 
edge by preventing excessive force from being applied to the edge by the 
form and slide rolls. 
Yet another object is to increase the spring force initially urging the 
slide roll towards the eccentric roll to allow a snug fit to occur between 
the container open end and the slide roll outer surface for improved 
support of the container open end on the slide roll during spin flow 
necking. 
DISCLOSURE OF THE INVENTION 
An apparatus for necking-in an open end of a container body comprises a 
first member and a second member mounted for engaging the open end of the 
container side wall along an inner surface thereof. Means is provided for 
rotating the container body and externally located means moves radially 
inward into deforming contact with an outside surface of the container 
side wall in a region thereof overlying an interface between the first and 
second members. Such contact between the externally located means with the 
side wall causes the contacted wall portion to move radially inwardly into 
a gap formed at the interface, caused by axial separation of the first and 
second members under the action of the radially inward advancing movement 
of the externally located means into the gap to thereby neck-in the side 
wall. In accordance with the invention, means, controlled by sensing 
radially inward movement of the externally located means, is provided for 
initiating gradual axial separation between the first and second members 
before the externally located means acts directly on both the first and 
second members through the contacted portion. 
In the preferred embodiment, the first member is a slide roll engaging and 
supporting the inside of the container open end. The slide roll is mounted 
for driven rotary motion about, and axial movement along, the container 
axis. The slide roll is resiliently biased into the container open end. 
The second member is an axially fixed roll mounted in axially inwardly 
spaced relation to the slide roll for engagement with an inside surface of 
the container side wall. The second roll has a conical end surface which 
faces the open end of the container and the slide roll includes a conical 
end surface facing the conical end surface of the axially fixed roll in 
opposite inclination thereto. The externally located means is a form roll 
having a peripheral deforming nose positioned externally of the container 
side wall and mounted for free rotary and controlled radial movement 
towards and away from the container. The form roll is biased for axial 
movement along an axis parallel to the container axis. The form roll 
deforming nose includes first and second oppositely inclined conical 
surfaces which are respectively opposed to the conical surfaces on the 
second roll and slide roll. 
The control means includes a cam follower surface mounted to contact one of 
the conical surfaces on the form roll during radial inward advancing 
movement thereof as the form roll initially contacts the conical surface 
on the second roll through the container side wall and before the form 
roll contacts the conical surface on the slide roll. Such contact between 
the form roll with the cam follower surface causes the slide roll to begin 
to axially move away from the second roll to thereby prevent pinching of 
the container side wall between the form and slide rolls. 
Such control means preferably includes a cam ring mounted to the slide roll 
radially outwardly adjacent therefrom. The cam follower surface is a 
conical surface which is located radially outwardly adjacent the conical 
surface of the slide roll and is disposed in a plane which is spaced 
closer to the opposing conical surface on the form roll, relative to the 
plane of the conical surface on the slide roll, by a distance slightly 
greater than the undeformed thickness of the container side wall. 
The cam follower surface and the conical surface of the form roll facing 
the cam follower surface are further arranged to produce the following 
motions: 
i) the form roll initially contacts the cam follower surface as it advances 
radially inwardly and toward the slide roll, via sliding contact with the 
conical surface of the second roll, so that the cam ring begins to axially 
move the slide roll away from the form roll to prevent pinching of the 
container side wall between the form and slide rolls; 
ii) as the form roll continues to radially inwardly advance it puts slight 
pressure on the container side wall extending between it and the slide 
roll so that the form roll is now pushing the slide roll directly through 
the container side wall and not through contact with the cam follower 
surface; and 
iii) further radially inward movement of the form roll causes it to 
re-contact the cam follower surface and thereby control the amount of 
clamping force and squeezing of the edge of the container side wall now 
extending between the form and slide rolls to prevent excessive spinning 
thereof. 
An annular clearance gap is formed between the conical surfaces of the 
slide roll and cam ring to receive the container side wall open end which 
is supported on the slide roll during necking. 
The slide roll and cam ring may also be of unitary construction. 
Preferably, however, these are separate members to enable the slide roll 
to be made of carbide to provide proper tooling surfaces while the cam 
ring is made of hardened tool steel. 
A method of spin flow necking-in an open end of a cylindrical container 
body is also disclosed. The method comprises the steps of positioning 
inside the container body an axially fixed roll engageable with the inside 
surface of the container body. The axially fixed roll has a sloped end 
surface which faces the open end of the container body. A slide roll is 
also positioned inside the container body which fits the inside diameter 
of the open end to support same. The slide roll has an end facing the 
sloped end surface of the axially fixed roll. The slide roll is supported 
for axial displacement away from the axially fixed roll. The slide roll 
end and the sloped end surface of the axially fixed roll define a gap 
therebetween. An outer form roll is positioned opposite the gap radially 
outwardly from the container body for axial displacement away from the 
axially fixed roll during contact with the sloped end of same. The form 
roll has a trailing end portion and a peripheral forming portion. As the 
container body spins, the form roll is advanced radially inwardly relative 
to the gap so that the trailing end portion presented by the roll and the 
sloped end surface of the axially fixed roll engage the container body 
between them while the trailing end portion of the form roll moves 
inwardly along the sloped end surface of the axially fixed roll to roll a 
neck into the container body. As the body continues to spin while the form 
roll moves inwardly, the slide roll is retracted axially until the roller 
has spun an outwardly extending portion on the end portion of the 
container body engaged between the slide roll and the roller. In 
accordance with the method of the invention, the axial retracting movement 
of the slide roll is controlled by contact between a surface of the form 
roll with a cam follower surface. 
The form roll has conical surfaces which are respectively engageable with 
the sloped end surface on the axially fixed roll and another sloped end 
surface on the slide roll. These form roll conical surfaces are smoothly 
connected with a curved forming surface extending therebetween and defined 
by a pair of small radii. The sloped end of the slide roll is also 
smoothly connected through another small radius to the axially extending 
surface thereof which is engageable with the inside surface of the 
container body. The cam follower surface operates to axially retract the 
holder as the small radius on the form roll approaches the small radius on 
the slide roll to thereby prevent pinching of the container side wall 
between these two small radii by allowing the radii to approach each other 
while maintaining separation therebetween by a distance slightly greater 
than the original thickness of the container side wall. 
Continued radially inward forming movement past a predetermined point at 
which the metal of the container side wall between the slide roll and the 
conical surface of the form roll has thickened will result in the form 
roll putting slight pressure directly on the metal. A gap opens between 
the form roll and cam follower surface so that the form roll is now 
pushing the slide roll directly through the metal and not through the cam 
follower surface. As the outermost end of the container side wall moves 
between the form roll and the slide roll, the form roll will once again 
contact the cam follower surface so that the rolling contact between the 
form roll and the slide roll does not excessively thin the edge of the 
open end. 
Still other objects and advantages of the present invention will become 
readily apparent to those skilled in this art from the following detailed 
description, wherein only the preferred embodiments of the invention are 
shown and described, simply by way of illustration of the best mode 
contemplated of carrying out the invention. As will be realized, the 
invention is capable of other and different embodiments, and its several 
details are capable of modifications in various obvious respects, all 
without departing from the invention. Accordingly, the drawing and 
description are to be regarded as illustrative in nature, and not as 
restrictive.

BEST MODE FOR CARRYING OUT THE INVENTION 
FIG. 3 is a schematic illustration of a spin flow necking assembly in 
accordance with the present invention. Therein, the functional components 
are substantially identical to the tooling components described in 
connection with FIG. 1, supra, except as noted hereinbelow. 
Spin flow necking assembly 100, as schematically depicted in FIG. 3, 
includes a cam ring 102 in the form of a cylindrical member having a 
conical face 104 extending at the same angle as the conical forming 
surface 19a on the slide roll 19' in spaced, radially outward adjacent 
relationship, such that the conical face or cam follower surface 104 
contacts the conical lead portion 11b of the form roll 11 before the small 
radius 106 between this lead surface and the forming surface 11a on the 
form roll exert force on the metal wrapped around the corresponding small 
radius 108 of the slide roll 19' in the manner discussed more fully below. 
Therefore, the cam follower surface 104 on the cam ring 102 is disposed in 
a plane P parallel to the plane P' of the slide roll chamfer 19a (FIG. 5 
only) and is spaced forwardly therefrom by approximately the initial metal 
thickness. The cam ring 102 is fastened to the slide roll 19' and rotates 
and moves with it. In the preferred embodiment of FIG. 3, rearward axial 
displacement of the cam ring 102 is transmitted to the slide roll 19' by 
the form roll 11 via nesting engagement of the rear face 102a of the cam 
ring against an annular mounting flange 110 projecting radially outwardly 
from the rear portion of the slide roll. 
The construction and operation of the cam controlled interaction between 
the form roll 11 and slide roll 19' is best understood through a 
sequential description of the spin flow necking process. Initially, with 
reference to FIG. 3, the container bottom 112 is loaded onto the base pad 
assembly 29 which retains the container C by vacuum applied in a known 
manner through a central hole 114. The container C is located on a raised 
circular plug 116 inside the countersink diameter of the bottom. An 
airtight seal is maintained on the outside tapered surface of the 
container bottom 112 with an elastic seal 118. The base pad assembly 29 is 
axially movable to advance the container into the tooling for forming and 
to remove the finished can for transfer to a flanging operation. The base 
pad assembly 29 dwells at both ends of its motion and has no axial 
movement during the forming process. The base pad is rotated by a main 
drive (not shown) and provides most of the rotative force on the container 
during the forming process. The main drive may also rotate the necking 
spindle assembly to ensure synchronous co-rotation. 
As mentioned above, the slide roll 19' is a cylindrical sleeve with a 
conical end 19a over which the open end C" of the container is positioned 
by the movement of the base pad. The slide roll 19' is supported by a 
rotating mandrel 120 driven by the main drive at the same rotative speed 
as the base pad assembly, as aforesaid. The slide roll is spring-loaded 
against a positive stop 122 and is pushed out of the open end of the 
container C by the form roll 11. The slide roll 19' is also rotated by the 
driven mandrel 120 upon which it slides. 
The eccentric roll 24 is a cylindrical roll which is smaller than the final 
neck diameter of the container. The working surfaces are the cylindrical 
outside diameter 25, the conical surface 24e and the connecting radius 
124. The conical angle of 24e determines the cone angle that is formed on 
the container. 
The form roll 11 is a cylindrical roll with a profiled outside diameter 
that forms the entire outside surface of the container neck area. It is 
free to rotate on an axis and is biased against a stop 126 with a light 
spring 12a. It is free to slide toward the open end of the container C 
against the light spring pressure. The axis on which it rotates is moved 
toward the container C to force the form roll 11 into contact with the 
container. It is free to seek an equilibrium position between the 
eccentric roll 24 and the cam ring/slide roll assembly. 
In FIG. 3, the base pad 29 is in the load position with a container C in 
place on the pad. The eccentric roll 24 is concentric with the slide roll 
19'. The slide roll 19' is against the forward stop 122 and the form roll 
assembly is in the `out` position. 
With reference to FIG. 4, the base pad assembly 29 has moved the container 
C onto the slide roll 19' and the eccentric roll 24 has rotated to contact 
the container at the neck location C". The form roll 11 has moved toward 
the container C and the form roll radius has contacted the container at 
the pre-neck location thereon. At this point, the rotating container C has 
also started both the eccentric roll 24 and form roll 11 to rotate. 
In FIG. 5, the form roll axis has moved radially inwardly closer to the 
container axis and has started to form the neck. The conical surface 24e 
on the eccentric roll 24 has forced the form roll 11 toward the open end 
C" of the container C. The form roll 11 has just touched the cam follower 
surface 104. The small radius 106 on the form roll 11 is very close to the 
small radius 108 on the slide roll 19' but does not pinch the metal 
between these two points. This is because the cam ring follower surface 
104 is positioned so these radii 106,108 may approach each other but stay 
separated by a distance slightly greater than the initial side wall 
thickness. This is presently understood to be a key feature in the 
elimination of metal exposure and neck cracks caused by excessive contact 
pressure between the two small radii 106,108 in the uncontrolled collison 
of the form roll 11 with the metal wrapped around the small radii 108 on 
the slide roll 19 in the prior spin flow necking process described 
hereinabove. In other words, since the form roll 11 contacts the cam 
follower surface 104 as the two radii 106,108 approach, such contact 
results in retraction or rearward axial sliding movement of the slide roll 
19' which permits the two radii to move past each other. 
In FIG. 6, the form roll 11 has penetrated further between the eccentric 
roll 24 and the slide roll 19'. The small radius 106 on the form roll 11 
is just passing the small radius 108 on the slide roll 19'. The rolls 
11,19' do not pinch the metal but have moved closer. As mentioned above, 
the form roll 11 is forcing the slide roll 19' back by contact between the 
form roll and the cam ring 102 instead of contact at this point between 
the form roll and the slide roll as occurred in the aforesaid prior spin 
flow necking process. 
In FIG. 7, the form roll 11 has continued its penetration and the small 
radius 106 is past the small radius 108 on the slide roll 19' (point A). 
At this point, the conical surfaces 19a,11b on the slide roll and the form 
roll, respectively, are opposite and parallel each other. The slide roll 
19' and cam ring 102' have been pushed to the left in FIG. 7. The 
combination of the metal thickening as a result of being squeezed between 
the form roll 11 and the eccentric roll 24 as the metal wraps around the 
forming surface 11a of the form roll, and the shape of the left or 
trailing conical surface 11b on the form roll, has reduced the relative 
clearance between the form roll and the slide roll so that the form roll 
is now actually putting slight pressure on the metal. 
In FIG. 8, the form roll 11 has now penetrated further into the gap between 
the eccentric and slide rolls 24,19'. The form roll 11 is clearly clamping 
the metal between it and the slide roll 19' and, as a result, a gap 130 
has opened up between the form roll surface 11b and the cam ring follower 
surface 104. The form roll 11 is now pushing the slide roll 19' directly 
in the axially rearward direction through its contact with the metal, and 
not through the cam ring 102. Since the small radii 106,108 between the 
form roll 11 and slide roll 19' have already "slipped" past each other 
without undesirable grooving of the metal therebetween, the direct 
interaction of the form roll in thinning and shaping the metal against the 
bias of the conical surface 19a on the slide roll is important to ensure 
proper necking and distribution of metal. 
In FIG. 9, the form roll 11 has now penetrated to its radially inwardmost 
position to complete the formation of the spin flow neck. During the 
entire forming process, between 20 to 24 revolutions of the container C 
are required, depending on the diameter, thickness and the amount of 
diameter reduction in the container end. The rolling contact between the 
form roll 11 and the slide roll 19' has thinned the edge of the flange 
slightly. Therefore, in accordance with a further feature of this 
invention, the form roll 11 now once again contacts the cam ring 102 to 
prevent further thinning of the flange area of the container C, i.e., gap 
130 has closed. 
In FIG. 10, as the base pad 29 begins to pull the container C back from the 
tooling, the eccentric roll 24 has moved to its concentric position and 
the form roll 11 has moved radially outward to clear the neck profile. The 
base pad 29 then moves back to its original load-unload position (FIG. 11) 
to be ready for the transfer wheel (not shown) to pick up the necked-in 
container and insert it into the flanging turret (not shown). 
From the foregoing description, it will be appreciated that the slide roll 
19' and cam ring 102 may be of unitary construction with an annular gap 
140 between the slide roll forming surface 19a and the cam ring follower 
surface 104 to initially receive the container open end C" which must 
engage the rearwardly extending axial surface 142 of the slide roll before 
necking begins (FIG. 4). Since the form roll 11 engages the container C 
only at one side, it will be appreciated that the container open C" end 
tends to be deformed into an oval shape when viewed in cross section in a 
direction parallel to the container longitudinal axis A. Therefore, it is 
important that the annular gap 140 between the forward end portion 144 of 
the cam ring 102 and slide roll 19' be sufficiently wide in the radial 
direction to prevent the container open end from contacting the rearwardly 
axially extending inner surface 146 (FIG. 5 only) of the cam ring which 
may cause the metal of the container to split. In practice, the groove is 
approximately 0.080" wide. 
Although the slide roll 19' and cam ring 102 may be of unitary 
construction, as aforesaid, it is preferred to form these elements as 
separate components in accordance with the preferred embodiment since the 
slide roll is preferably carbide metal while the cam ring is tool steel. 
As a practical matter, forming the cam ring and slide roll from carbide 
metal so as to be of unitary construction is not feasible since it is very 
difficult to machine the annular clearance gap 140 between the slide roll 
forming surface 19a and the cam ring follower surface 104 as aforesaid. 
Another advantage achieved with the cam ring 102 of the present invention 
is the ability to utilize a heavier spring 20 urging the slide roll 19' 
into its initial, axially forward position, in comparison with the initial 
spring force in the prior spin flow necking process. In the prior process, 
the initial spring force could not exceed 5 pounds since the greater the 
spring force, the more extensive the grooving will be. On the other hand, 
a greater spring force is desirable since the snugger the fit between the 
slide roll 19' and container open end C", the greater the control will be 
over the final neck diameter. With the cam ring 102 of the present 
invention, since grooving is no longer a problem, the spring pressure may 
be greater. In the preferred embodiment, the spring pressure is preferably 
now 5-8 pounds. 
In the preferred embodiment, the inner cylindrical surface 150 of the cam 
ring 102 is formed with an annular groove adopted to receive an O-ring 152 
as best depicted in FIG. 11 only. This O-ring 152 is engageable with an 
annular groove 154 formed in the outer cylindrical surface of the slide 
roll 19' located between the mounting flange 110 and the forming surface 
19a. The O-ring 152 prevents any relative axial sliding movement from 
occurring between the cam ring 102 and the slide roll 19'. In the 
alternative, the cam ring 102 and slide roll 19' may be screwed or bolted 
together. 
It will be readily seen by one of ordinary skill in the art that the 
present invention fulfills all of the objects set forth above. After 
reading the foregoing specification, one of ordinary skill will be able to 
effect various changes, substitutions of equivalents and various other 
aspects of the invention as broadly disclosed herein. It is therefore 
intended that the protection granted hereon be limited only by the 
definition contained in the appended claims and equivalents thereof.