Note: Descriptions are shown in the official language in which they were submitted.
~Technical Field 21 0 1 ~ ~ 2
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 x 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,
- 1 - ~
210~U~2
-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
21~v~
means of achieving further light weighting 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 .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 .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 .075 - .110" and the spin necking operation
reduces it by .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. Patent 4,781,047, issued November 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
~iv~v~2
~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 Figure 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 Figure 1 (corresponding to Figure 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
~1(J4~2
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 l9a 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 Figures 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 l9a,24e of the slide and eccentric
rolls 19,24. More specifically, the side wall C' of the spinning
2 ~ b 2
~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 (Figure
2B). The side wall of the cone increases in length as does the
height of the cone as the external forming roll chamfer llc
continues to squeeze or press the container metal along the
complemental slope or truncated cone 24e of the eccentric roll
24 as depicted in Figure 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 Figures 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 llb,19a of the forming
roll 11 and the slide roll 19 to complete the necked-in portion.
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
210~62
between rolls 11,19 in Figure 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 Figure 2B to that of Figure 2C.
As the form roll 11 moves into its radially inward most
position depicted in Figure 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
_ g
~U 4~2
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 in~ard 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
-- 10 --
21~4~2
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
~lV~2
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
- 12 -
b 2
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
- 13 -
~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
- 14 -
~lv~u~2
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.
Brief Description of Drawings
Figure 1 is a cross-sectional view of a prior spin flow
necking process;
Figures 2A-2E are enlarged, cross-sectional sequential views
depicting the spin flow necking forming sequence with the tooling
of Figure l;
25Figure 3 is a schematic representation of an improved spin
flow necking apparatus in accordance with the present invention;
Figure 4 is a schematic representation similar to Figure 3
- 15 -
~ ~ U~i b2
depicting the form roll radially inwardly moved into initial
contact with the container side wall to be necked;
Figure 5 is an enlarged, detailed sequential view depicting
the relative locations of the tooling components at the onset of
necking;
Figure 6 is a view similar to Figure 5 sequentially
depicting further relative positioning of the tooling components
as necking continues;
Figure 7 is similar to Figure 6 depicting further sequential
positioning of components;
Figure 8 is a view similar to Figure 7 depicting still
further sequential positioning;
Figure 9 is similar to Figure 8 depicting the locations of
the tooling components at the radially most inward position of
the form roll;
Figure 10 is a schematic representation depicting the
locations of the components after necking; and
Figure 11 is similar to Figure 10 after the base pad pulls
the container back from the tooling for unloading (loading).
Best Mode for CarrYinq out the Invention
Figure 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 Figure 1, supra, except
as noted hereinbelow.
Spin flow necking assembly 100, as schematically depicted
in Figure 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 l9a 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 llb of the form roll 11 before the small radius 106
between this lead surface and the forming surface lla 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 l9a (Figure 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 Figure 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.
- 17 -
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 Figure 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 _ooling 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 l9a 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
- 18 -
;~lV4~2
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 Figure 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 Figure 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
-- 19 --
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 Figure 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 Figure 6, the form roll 11 has penetrated further between
- 20 -
;~lV~L~b2
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 Figure 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
l9a,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 Figure 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 ha of the form roll, and the
shape of the left or trailing conical surface llb 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 Figure 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 llb and the cam ring follower surface 104.
~i~14~i~72
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 l9a on the slide roll is important to ensure proper
necking and distribution of metal.
In Figure 9, the form roll 11 has now penetrated to its
radially inward most 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 Figure 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 (Figure 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 l9a 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 (Figure 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
(Figure 5 only) of the cam ring which may cause the metal of the
container to split. In practice, the groove is approximately
.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
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~~onstruction is not feasible since it is very difficult to
machine the annular clearance gap 140 between the slide roll
forming surface l9a 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
15 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 Figure 11 only.
This O-ring 152 is engageable with an annular groove 154 formed
25 in the outer cylindrical surface of the slide roll 19' located
between the mounting flange 110 and the forming surface l9a. The
O-ring 152 prevents any relative axial sliding movement from
occurring between the cam ring 102 and the slide roll 19'. In
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~lU~U~
~~he 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 ir,vention fulfils 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.
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