Note: Descriptions are shown in the official language in which they were submitted.
W096/40457PCT~S3./09~33
,.
~ 21~477~
RESHAPED CONTAINER AND METHOD
AND APPARATUS FOR RESHAPING A CONTAINER
DESCRIPTION
Technical Field
The present invention generally relates to a
reshaped seamless container body and to a method and
apparatus for reshaping such a container body, and
more particularly, to a seamless drawn and ironed
beverage container body having portions of a side wall
expanded radially outward from an initial cylindrical
shape, and to a method and apparatus for expanding the
side wall of the container body.
Bach4Lo~,d of the Invention
15The present invention relates to reshaping the
- side wall of a drawn and ironed seamless container
body. Such container bodies are typically used for
~ beverages and are constructed from a single disc of
metal, sometimes referred to as a blank. The metal
disc is typically an aluminum alloy. The metal disc
is first formed into a cup having a bottom wall
W096/40457 PCT~S9G/03~
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~ 2- ~ ~ 9477~
~ ,.... .
portion and a side wall extending from the bottom wall
portion. The cup is then drawn and ironed to axially
extend the side wall and reduce the diameter of the
cup. The drawing and ironing process thins the metal
in the side wall. The side wall of the container body
formed in a drawing and ironing process has an initial
cylindrical shape, and extends from the bottom wall
portion to a neck portion at an open end of the
container body opposing the bottom wall portion. The
neck portion is often necked in to include a portion
of reducing diameter, and is provided with an
outwardly directed flange.
The resultant finished container is sometimes
referred to as a two-piece container. That is, the
container body, which was subjected to the drawing and
ironing process to form the bottom wall portion and
side wall extending from the bottom wall portion, is
the first piece of the container, and a container end
wall, which is typically double seamed to an open end
of the container body opposing the bottom wall
portion, is the second piece. Due to the large number
of containers made each year, the beverage container
industry is constantly striving to create two-piece
containers with the minimum amount of metal. The
metal disc used to form the container body for a
typical beverage container presently has a thickness
of approximately 0.0112 - 0.0114 inches. The side
wall is thinned to approximately one third of the
initial disc thickness.
One other type of metal container commonly found
is sometimes referred to as a three-piece container.
A three-piece container includes a first rectangular
piece of metal which is rolled into a cylindrical
shape to form the side wall or cylindrical portion of
the container. The sides of the rectangular piece are
then welded together to form a seam along the side
wall. The cylindrical portion of the three-piece
W096l40457 PCT~S~~i~'33~
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container thus has two open ends. A first end wall
and a second end wall are then double seamed to the
open ends of the cylindrical portion, as the second
and third pieces, respectively, of the three piece
container. The cylindrical portion of a three piece
container is typically many times thicker than the
side wall of a drawn and ironed container.
Several methods and apparatuses are known for
reshaping, or expanding radially outward, portions of
the cylindrical portion of a three-piece container.
One apparatus is disclosed in Japanese Patent Nos. 54-
150365 and 57-168737. This type of apparatus includes
an inner shaping mandrel with a plurality of forming
segments. The forming segments are cammed radially
outward to engage the inner surface of the cylindrical
portion of the three-piece container and expand at
least a portion of it radially outward.
Another apparatus for expanding portions of the
cylindrical portion of a three piece container is
disclosed in U.S. Patent No. 4,487,048 ("Frei"). Frei
is directed to forming beads in the cylindrical
portion of a three piece container. As disclosed in
Fig. 1 of Frei, a cylinder having two open ends is
placed over an inner roll which is provided with
embossing projections. Axial movement of an expanding
cone forces the projections radially outward into the
cylinder.
More recently, the cylindrical portion of three-
piece containers have been expanded using an internal
fluid pressure. The internal fluid pressure forces
the cylindrical portion of the three piece container
- radially outward into a mold or shell having a desired
configuration for the container.
~ Unlike the cylindrical portion of a three piece
container, the container body of a two piece container
includes an integral bottom wall portion. The bottom
wall portion inhibits movement of the metal in the
W096/40457 PCT~S3G/~39~3
; j ~4~ 2
side wall and makes it extremely difficult to cold
work the side wall to expand it beyond the initial
cylindrical shape. Additionally, a drawn and ironed
container body is extremely work hardened and brittle,
and the side wall of the container body has limited
ductility. Accordingly, the expansion techniques used
for three-piece containers have not been used for a
two-piece container body.
One method of reshaping or expanding the side
wall of a drawn and ironed container which is
disclosed in U.S. Patent No. 5,058,408 ("Leftault, Jr.
et al."), requires heat treatment of portions of the
side wall. In Leftault, Jr. et al., heat treatment of
the side walls of a drawn and ironed container was
found necessary to allow successful bulging of the
container side wall. Otherwise, the bulging operation
could exceed the formability capability of the metal
and cause catastrophic failure. The heat treatment is
applied for a sufficient time and at a sufficient
temperature to lower the yield strength of the side
walls at least 15~ to permit the subsequent bulging.
Portions of the side wall are preferably heated with
a conventional induction heating coil at a temperature
of about 450~-650~ F. for a time of about .25 to 10
seconds. The heat treatment causes recrystalization
of the metal in the side wall to a very fine grained
microstructure. After heat treatment, the side wall
is bulged by mechanical or electromagnetic bulging.
One apparatus for electromagnetic bulging is disclosed
in U.S. Patent No. 4,947,667.
SummarY of the Invention
The present invention provides an apparatus and
a method for reshaping or expanding radially outward,
portions of the side wall of a seamless drawn and
ironed container body with out the necessity of heat
treating the side wall. The present invention also
provides an apparatus and method for applying an axial
W096/40457 PCT~59 039X3
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compressive force to the container body to assist in
the reshaping operation. The present invention
further provides an apparatus and method for further
reshaping the expanded portions of the side wall by
deforming segments of such portions radially inwardly.
The axial compressing force and the radially inward
deformation are not necessarily confined to a seamless
drawn and ironed container body.
In accordance with one aspect of the present
invention an apparatus is disclosed which comprises a
shaping mandrel connected to a housing. The shaping
mandrel includes a plurality of expanding forming
segments, each of the forming segments having a
contacting surface for engaging an interior surface of
the side wall of the container body. The contacting
surface of each forming segment is highly polished to
a surface finish of 2-10 microns. Further, the
forming segments include a first curved corner surface
on a first side of the contacting surface and a second
curved corner surface on a second side of the
contacting surface opposed from the first side. The
first and second curved surfaces have a radius of
curvature of approximately 2-3 millimeters. Prior
forming segments, used to expand the cylindrical
portion of a three-piece container, included
contacting surfaces with a finish of 20-32 microns,
and relatively sharp radii of curvature on either side
of the contacting surface of approximately 0.5
millimeters. Use of such prior forming segments would
tear or rupture the side wall of a drawn and ironed
container body.
-The apparatus may further include an outer tool
connected to the housing for engaging an outer surface
-of the side wall of the container body during the
reshaping operation. The outer tool would apply a
radially inward force to a portion of the side wall to
deform radially inwardly segments in the side wall.
W096/40457 PCT~S3./~9~
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The outer tool can be stationary and expansion of the
forming segments of the inner shaping mandrel can move
portions of the side wall into contact with the outer
tool to form the radially inwardly deformed segments.
Alternatively, the outer tool can include means for
radially inward movement. Such means can be a c~mm;ng
mechanism for camming outer forming segments on the
outer tool radially inward.
The shaping mandrel of the apparatus includes an
actuator arm for providing radial outward movement of
the forming segments. The actuator arm includes a
plurality of camming surfaces for contact with the
forming segments. Axial movement of the actuator arm
cams the forming segments radially outward into
engagement with the interior surface of the side wall
of the container body.
The apparatus may further include a support
platform axially aligned with the shaping mandrel for
contacting the bottom wall portion of the container
body. The support platform may also include means for
applying a vacuum pressure between the support
platform and a bottom wall of said container body to
maintain contact between the support platform and the
bottom wall. This assists the support platform in
placing the container body over the shaping mandrel,
and removing the container body after the reshaping
operation. Further, the support platform may be used
to apply an axial compressive force to the container
body during the reshaping operation. A biasing spring
connected to the support platform may be used for
applying the axial force. The opposing end of the
container is pressed against the housing.
Additionally, the apparatus further includes a
removal sleeve connected to a guide post which is
connected to the housing. The removal sleeve contacts
a portion of the container body proximate the neck
portion. Axial movement of the removal sleeve affects
W096/40457 PCT/U~r-'09~3
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movement of the container body about the mandrel. The
removal sleeve includes a first clamping jaw and a
second clamping jaw. The first and second clamping
jaws are pivotly mounted to the removal sleeve for
engaging or clamping the neck portion of the container
body.
In another aspect of the invention, an apparatus
for reshaping a portion of a cylindrical side wall of
a container body is disclosed. The apparatus includes
a shaping mandrel connected to a housing. The shaping
mandrel includes a plurality of expanding forming
segments, each of said forming segments having a
contacting surface for engaging an interior surface of
said side wall. The apparatus further includes a
support platform axially aligned with the mandrel for
contacting a first end of the container body.
In yet another aspect of the invention, an
apparatus for reshaping a portion of a cylindrical
side wall of a container body is disclosed. The
apparatus includes a shaping mandrel connected to a
housing. The shaping mandrel includes a plurality of
expanding forming segments, each of the forming
segments having a contacting surface for engaging an
interior surface of the side wall. The apparatus
further includes an outer tool connected to the
housing for engaging an outer surface of the side wall
during a reshaping operation to apply a radially
inward force to the side wall.
In yet another aspect of the invention an
apparatus for reshaping a cylindrical side wall of a
container body is disclosed. The apparatus comprises
~ a flexible inner mandrel for placement in an interior
of a container body. The mandrel includes a generally
cylindrical centrally located channel having a first
diameter and an outer shaping surface for contacting
an inner surface of a side wall of the container body.
The side wall having an initial cylindrical shape.
W096/40457 PCT/U~ 3~3
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The apparatus further includes a plunger including a
plunger head. The plunger head has a second diameter
greater than the first diameter of the centrally
located channel of the mandrel wherein movement of the
plunger head through the channel forces at least a
portion of the outer shaping surface of the mandrel
radially outward into contact with the inner surface
of the side wall to expand at least a portion of the
side wall radially outward from the initial
cylindrical shape.
The outer shaping surface of the mandrel may
include an annular recessed channel. The mandrel is
preferably polyurethane or rubber.
One aspect of the method of the present invention
discloses reshaping a container body having an
integral bottom wall. The method includes the steps
of providing a container body which has been drawn and
ironed from a single metal disc, the container body
having a seamless side wall extending from a bottom
wall at one end, and having an opening at an end
opposing the bottom wall, the side wall having an
initial cylindrical shape. The method includes
applying a radially outward force to an inner surface
of the side wall of the drawn and ironed container
body to deform at least a first portion of the side
wall radially outward from the initial cylindrical
shape.
The applying a radial outward force step may
include inserting a shaping mandrel through the open
end of the container body, wherein the shaping mandrel
includes a plurality of forming segments for engaging
an interior surface of the side wall. Expanding the
forming segments radially outward to engage the
interior surface of the side wall and expand the side
wall radially outward. Collapsing the forming
segments of the shaping mandrel and removing the
container body from about the shaping mandrel.
W096/40457 PCT~SgG/~ 3
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~. .. , .. ~ ~s
The removing step may comprise engaging a portion
of the container body proximate the open end with a
removal sleeve and moving the container body axially
away from the shaping mandrel with the removal sleeve.
The applying a radial outward force step may
comprise deforming at least a portion of the side wall
radially outward until such portion has a mean average
diameter approximately 5-7~ greater than a mean
average diameter of the initial cylindrical shape.
The method may further comprise the step of
applying an axial compressive force to the container
body during the applying a radial outward force step.
This step may comprise engaging the open end of the
side wall against a stationary ring in a housing. The
method further includes providing a support platform
for engaging the bottom wall of the container body,
and moving the support platform axially towards the
container body to apply a compressive force to the
container body between the support platform and the
stationary ring.
The method may further comprise the step of
creating a vacuum pressure between the support
platform and the bottom wall of the container body to
maintain engagement between the bottom wall and the
support platform.
The method may further comprise the step of
applying a radially inward force to the deformed, or
expanded, portion of the side wall to further deform
the portion of the side wall radially inwardly. The
applying a radially inward force step may comprise
placing a stationary outer shaping tool proximate an
~ exterior surface of the side wall wherein the applying
a radial outward force step causes the exterior
~ surface of the side wall to engage the outer shaping
tool. Alternatively, the applying a radially inward
force step may comprise placing an outer shaping tool
proximate an exterior surface of the side wall and
W096/40457 PCT~S9~'~5~B3
~ 5 -10- 2194779
moving the shaping tool radially inward to engage the
side wall.
The method may further comprise the step of
applying a radially outward force to the side wall of
the container body to deform at least a second portion
of the side wall radially outward from the initial
cylindrical shape. This step can be done at the same
time as the first portion is being deformed, or it can
be done subsequent to forming the first portion in a
progressive reshaping operation.
In another aspect of the present invention a
method of reshaping a tubular element, such as side
wall of seamless drawn and ironed container body or
the cylindrical portion of a three-piece container is
disclosed. The method comprises the steps of
providing a tubular element having a first end and an
opposing second end, the tubular element having an
initial cylindrical shape. The method further
includes applying a radially outward force to the
tubular element to deform at least a first portion of
the tubular element radially outward from the initial
cylindrical shape and applying a radially inward force
to the first portion of the tubular element to further
deform the first portion of the tubular element.
A reshaped container of the present invention is
also disclosed. The reshaped container comprises a
seamless container body formed from a single disc of
metal. The disc of metal is preferably an aluminum
alloy. The container body includes a bottom wall
portion at a first end of the container body having a
first mean average diameter, and a cold worked side
wall portion extending from the bottom wall portion to
a neck portion at a second end of the container body.
The neck portion is utilized to attach a container end
to the container body. The side wall includes a first
portion having a second mean average diameter and a
second portion having a third mean average diameter
W096/40457 PCT~ 93~
~s~ - 2 1 94779
greater than both the first mean average diameter and
the second mean average diameter.
The neck portion may comprise a generally
frustoconical portion of reducing diameter and an
outwardly directed flange.
The side wall of the reshaped container may
include a third portion having a forth mean average
diameter less than the third mean average diameter
wherein the second portion is axially disposed between
the first portion and the third portion. The said
side wall may further include a fourth portion having
a fifth mean average diameter greater than the first
mean average diameter and greater than the second mean
average diameter and greater than the fourth mean
average diameter wherein the third portion is axially
disposed between the second portion and the fourth
portion.
The side wall may also include a plurality of
radially inwardly deformed segments spaced
circumferentially about the second portion. The
segments may extend axially along the second portion
of the side wall and have an outwardly concave arcuate
portion.
The third mean average diameter of said second
portion of the side wall is approximately 5-7~ greater
than the second mean average diameter of the first
portion.
In an alternative embodiment, a shaping mandrel
is provided with a first forming mechanism and a
second forming mechanism for expanding a portion of
the side wall of a container. In the broadest sense,
the first forming mechanism includes at least two
forming segments moveable from a first retracted
position to an expanded position. When in the
expanded position, the first forming segments are
circumferentially spaced apart and form gaps between
the first forming segments. The second forming
W096/404s7 PCT~S96~093~3
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mechanism includes a second forming segment moveable
from a retracted position to an expanded position.
The second forming segment is disposed or positioned
to be within a gap formed between the first forming
segments when in an expanded position.
In another embodiment having a first forming
mechanism and a second forming mechanism, the first
forming mechanism includes a plurality of forming
segments, preferably five, movable from a retracted
position to an expanded position, and the second
forming mechanism includes a plurality of second
forming segments, again preferably five, movable from
a retracted position to an expanded position. The
first forming segments and the second forming segments
are alternately arranged. As the first forming
segments are moved to an expanded position, the
segments become circumferentially spaced, which forms
gaps between consecutive first forming segments. The
second forming segments are configured to move into
the gaps between the first forming segments when in
the expanded position.
Each of the first forming segments and the second
forming segments include a contacting surface for
engaging the interior surface of the side wall of the
container. The contacting surfaces of the first
forming segments and the second forming segments can
be dimensioned to form a substantially contiguous
surface when both the first forming segments and the
second forming segments are in the expanded position.
In this manner, the first and second forming segments
may form a smooth expanded portion in the side wall of
the container without crease lines. Such crease lines
are typically formed when only the first forming
segments are utilized to expand the portion of the
side wall.
An actuator arm having a plurality of camming
surfaces for moving the plurality of first forming
W096/404s7 PCT~S9G/09~3
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segments from the retracted position to the expanded
position, and a plurality of camming surfaces for
moving the plurality of second forming segments from
the retracted position to the expanded position can be
used to effect such movement. That is, axial movement
of the actuator arm will cam the forming segments
radially outward. The camming surfaces can be
configured to move the first forming segments radially
outward at a greater rate than the second forming
segments.
In an alternative embodiment, the actuator arm
only includes a plurality of camming surfaces for
moving the second forming segments radially outward
from the retracted position to the expanded position.
In this embodiment, each of the second forming
se~ments can include a camming surface for moving, in
turn, a first forming segment from the retracted
position to the expanded position.
In a further embodiment of the invention, a
method is provided for expanding a portion of a
seamless container body. The method includes
providing a container body which has been drawn and
ironed from a single metal disc, to have a side wall
extending from a bottom wall at one end, and an
opening at an end opposing said bottom wall. The side
wall having an initial cylindrical shape and a initial
diameter. The container body is placed over a shaping
mandrel having a plurality of forming segments
moveable from a retracted position radially outward to
an expanded position, each of the forming segments
including a contacting surface for engaging an
interior surface of the side wall of the container
body. A lubricant is provided between the contacting
surfaces and the interior surface of the side wall.
The forming segments are moved from the retracted
position to the expanded position to drive the
contacting surfaces into engagement with the interior
W096/40457 PCT~S36/09~3
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surface of the side wall and expand a portion of the
side wall radially outward beyond the initial
diameter. In this method, the lubricant helps lower
the coefficient of friction between the contacting
surfaces of the forming segments and the interior
surface of the side wall. This enables the container
body to be expanded radially outward to a greater
extent than by forming with a higher coefficient of
friction. This is because the segments of the side
wall which abut the contacting surfaces of the forming
segments are not locked against the contacting
surfaces (as could happen with higher coefficients of
friction) and are able to stretch along with the
material in the gaps between the forming segments. If
the coefficient of friction is too high, then all of
the stretching occurs to the material of the side wall
in the gaps between the forming segments. The
coefficient should be less than about 0.1, and is
preferably in the range of 0.02 to 0.075. A
coefficient of 0.05 has been found to produce good
results. Utilizing an appropriate coefficient of
friction, it is possible to expand a portion of the
side wall to a diameter which is 4~ to 5~ greater than
the initial diameter of the container body without a
large number of failures (e.g. ruptured containers).
The container bodies used for food and beverages
are typically provided with a protective coating which
is applied to the interior surface of the container
body. This is preferably done by an airless spray
procedure. The lubricant can then be applied
externally over the protective coating and then be
washed off after the expanding operation.
Alternatively, the protective coating may include an
internal lubricant component, such as a carnauba wax.
The internal lubricant will then bloom to the surface
and affect the appropriate coefficient of friction.
W096/40457 PCT~S9~/~g9~
~ 15- 2 1 9 4 7 7 9
Further aspects of the invention are described in
the detailed description or shown in the Figures.
Brief Description of Drawinas
Fig. l discloses a cross-sectional view of an
apparatus of the present invention;
Fig. 2 discloses a cross-sectional view of
modified form of the apparatus of Fig. 1;
Fig. 3 discloses a top plan view of a removal
sleeve of the apparatus of Fig.2;
Fig. 4 discloses a cross-sectional view of an
alternative embodiment of the apparatus of the present
invention;
Fig. 5 discloses a top plan view of an outer ring
of the apparatus of Fig. 4;
Fig. 6 discloses a cross-sectior.11 view of a
further embodiment of the apparatus of the present
nvent1on;
Fig. 7 discloses a cross-sectional view of the
forming segments of the present invention;
Fig. 8 discloses an enlarged cross-sectional view
of the forming segment of the present invention;
Fig. 9 discloses the apparatus of Fig 1 with
modified forming segments;
Fig. 10 discloses a perspective view of a
reshaped container of the present invention;
Fig. 11 discloses a side view of the container of
Fig. 10;
Fig. 12 discloses a cross-sectional view taken
along the line 12-12 of Fig. 11;
Fig. 13 discloses a cross-sectional view taken
along the line 13-13 of Fig. 11;
Fig. 14 discloses a perspective view of an
alternative form of the container of the present
invention;
Fig. 15 discloses a side view of the container of
Fig. 14;
W096/40457 PCT~S3~'09~3
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Fig. 16 discloses a cross-sectional view taken
along the line 16-16 of Fig. 15;
Fig. 17 discloses a perspective view of an
alternative form of the container of the present
invention;
Fig. 18 discloses a side view of the container of
Fig. 18;
Fig. 19 discloses a cross sectional view taken
along the line 19-19 of Fig. 18;
Fig. 20 discloses a perspective view of an
alternative container of the present invention;
Fig. 21 discloses a side view of the c~ntainer of
Fig. 20;
Fig. 22 discloses a cross-sectional view taken
along the line 22-22 of Fig. 21;
Fig. 23 discloses a cross-sectional view of an
alternative embodiment of a shaping mandrel in an
expanded position;
Fig. 24 discloses a cross-sectional view of the
shaping mandrel of Fig. 23 in a retracted position;
Fig. 25 discloses a cross-sectional view of a
further alternative embodiment of a shaping mandrel in
a retracted position;
Fig. 26 discloses a cross-sectional view of the
shaping mandrel of Fig. 25 in an expanded position;
Fig. 27 discloses a perspective view of a shaping
mandrel in a retracted position;
Fig. 28 discloses a perspective view of the
shaping mandrel of Fig. 27 in an expanded position;
Fig. 29 discloses a perspective view of a
container placed on a shaping mandrel of a reshaping
apparatus including an outer forming tool;
Fig. 30 discloses a perspective view of an
alternative form of the container of the present
invention;
Fig. 31 discloses a side view of the container of
Fig. 30;
W096/40457 PCT~S96~99~3
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Fig. 32 discloses a top view of the container of
Fig. 30; and,
Fig. 33 discloses a bottom view of the container of
Fig. 30.
Detailed Descri~tion of Preferred Embodiments
While this invention is susceptible of
embodiments in many different forms, there is shown in
the drawings and will herein be described in detail
preferred embodiments of the invention with the
understanding that the present disclosure is to be
considered as an exemplification of the principles of
the invention and is not intended to limit the broad
aspect of the invention to the embodiments
illustrated.
Referring to Fig. 1, an apparatus 10 is disclosed
in cross-section for reshaping a container body 12.
The container body 12, is formed from a single disc of
metal, preferably an aluminum alloy such as an
aluminum 3004 H19 temper, and is drawn and ironed in
a conventional manner. The starting thickness of the
metal disc is approximately 0.0112 - 0.0114 inches,
and during the drawing and ironing process the side
wall thickness is reduced to approximately one third
of the starting thickness (i.e., about 0.004 inches).
The container body 12 includes a bottom wall 14 at one
end and a seamless side wall 16 extending from the
bottom wall 14. The side wall 16 extends to a neck
portion 18 which is proximate an open end of the
container body 12. For the container body 12
disclosed in Fig. 1, the neck portion 18 includes a
frustoconical portion 20 of reducing diameter and an
- outwardly directed flange 22. The flange 22 is
utilized to double seam a container end to the
- container body 12 in a conventional manner.
Unlike a three piece container body which has two
open ends and a welded side seam, the bottom wall 14
W096/404s7 PCT~S9"~93~3
~ 18- 2194779
of the container body 12 limits movement of the metal
in the side wall during the expansion operation.
Prior to the reshaping operation of the present
invention, the side wall 16 of the container body 12
has an initial cylindrical shape having an axial
length and a constant radius of curvature, measured
from the longitudinal axis of the container, along the
axial length. After the reshaping operation, at least
a portion of the side wall is expanded radially
outward from this initial cylindrical shape.
The reshaping apparatus 10 includes a shaping
mandrel 24 extending from a housing 26. The housing
26 is secured to a main frame 28 which may be
stationary, or part of a rotatable turret assembly
having a plurality of housings and shaping mandrels.
If part of a turret assembly, the mainframe may have
ten reshaping stations. Such assemblies can reshape
600 containers per minute.
The shaping mandrel 24 includes a plurality of
forming segments 30 spaced about an actuator or
expander arm 32. Each forming segment 30 includes a
radially outward surface 34 for contacting or engaging
the inner surface 36 of the container 12 side wall 16.
The forming segments 30 are preferably a hardened
steel, and are preferably coated with a material to
increase the wear capability of the contacting surface
34 of the segment 30 and to reduce friction between
the forming segment 30 and the inner surface 36 of the
container body 12 side wall 16. The coating material
may be, for example, chrome or titanium nitride,
although other materials may also be used. In the
testing apparatus initially utilized to reshape a
drawn and ironed seamless container, the forming
segments were coated with chrome.
Unlike the forming segments used in the past to
reshape the cylindrical portion of a three piece
container, the segments 30 of the apparatus 10 have
W096/40457 PCT/U~ v93~3
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. . .
been modified to enable expanslon of the side wall of
a drawn and ironed seamless container body.
Specifically, the contacting surfaces 34 of the
forming segments 30 have been polished to an extremely
smooth surface finish. In the past, the surface
finish, or rugosity, of the contacting surface was on
the order of 20-32 microns. For reshaping the thin
walled drawn and ironed aluminum alloy seamless
container, a surface finish of less than about 1
micron, and more preferably about 0.3 microns or less,
is required. When a coating is applied to the
contacting surface 34 of the forming segment 30, the
contacting surface 34 is first polished to a surface
finish of about 0.3 microns. The coating is then
applied and the contacting surface 34 is again
polished to a finish of about 0.3 microns. In
addition to providing a smoother contacting surface
34, the corners 38 on each side of the contacting
surface 34 have also been modified for enabling
expansion of drawn and ironed seamless container
bodies. In the prior art forming segment, the
contacting surface terminated at either side in a
relatively sharp corner having a radius on the order
of about 0.5 millimeters. Such corners, along with
the rougher contacting surface, would tend to rip the
brittle, work hardened aluminum of the container body
12. As shown in cross-section in Figs. 7 and 8, the
radii R2 of the corners 38 of the forming segments 30
have been significantly increased to about 2-3
millimeters, which is approximately twenty times
greater than the wall thickness of the side wall 16 of
the container body 12.
Referring again to Fig. 1, the container body 12
is positioned over the shaping mandrel 24 so that the
flange 22 abuts against a supporting ring 44 connected
to the housing 26. Referring only to the right side
of Fig. 1, the forming segment 30 is shown in a
WO ~/40457 PCT~S~C/~33~3
fr ~ 20- ~
~ i 94~79
collapsed or retracted position in which the
contacting surface 34 is spaced radially inward from
the inner surface 36 of the side wall 16. The forming
segment 30 includes a lip 46 at one end which is
secured in a channel 48 in the housing 26. The lip 46
is connected to a pin 64 which is positioned in a
spring 66. The forming segment 30 also includes a
first camming surface 50 and a second c~mm; ng surface
52 which abut against first and second camming
surfaces 54, 56 of the actuator 32. Plastic glide
pads 58, 60 are connected to the first and second
camming surfaces 50, 52 of the forming segment 30.
The first and second camming surfaces 50, 52 of the
forming segment 30, and the first and second camming
surfaces 54, 56 of the actuator are at an angle with
respect to the longitudinal axis 62 of the container
body 12.
In operation, as shown on the left side of Fig.
1, the actuator 32 has been moved axially away from
the bottom 14 of the container body 12. This axial
movement causes the camming surfaces 54, 56 of the
actuator 32 to cooperate with the camming surfaces 50,
52 of the forming segment 30 to move the forming
segment 30 radially outward toward the inner surface
36 of the side wall 16. The contacting surface 34 of
the forming segment 30 contacts or engages the inner
surface 36 of the side wall 16 of the container body
12, and expands a portion 68 of the side wall 16
radially outward from the longitudinal axis of the
container beyond the initial cylinder of the container
body 12.
During the expanding operation, the pin 64 is
also moved radially outward and compresses the spring
66. When the expanding of the portion 68 of the side
wall 16 is completed, the actuator 32 is moved axially
toward the bottom wall 14 of the container body 12 and
the spring 66 forces the pin 64 and forming segment 30
W096/40457 PCT~S9'fOg~3
-21- 21 94779
.:;.;, '. . j -:'
back into a collapsed or retracted position. The
container body 12 may then be removed from the shaping
- mandrel 24.
As shown in Fig. 1, a lower portion 70 of the
side wall 16 is not contacted by the forming segments
30 and maintains the mean average diameter of the
initial cylindrical shape of the side wall 16. The
expanded portion 68, however, after the operation has
a mean average diameter which is greater than the mean
average diameter of the lower portion 70.
As can be seen on the left hand side of Fig. 1,
the flange 22 of the container body 12, is pulled away
from the ring 44 during the reshaping operation.
The container body 12 of Fig. 1 is shown after
the reshaping operation in Figs. 10-13.
Referring to Fig. 2, a further modified container
reshaping apparatus 72 is disclosed. Fig. 2 discloses
elements for applying an axial load force to the
container body 12 during the reshaping operation, and
for removing the container body 12 from the shaping
mandrel 24 (not shown in Fig. 2) after the operation.
The apparatus 72 includes a container body
support structure 74 for applying an axial load force
to the container body 12. The structure includes a
housing 76 connected to a bottom platform support 78.
The platform support 78 is axially aligned with the
shaping mandrel 24 and abuts the bottom wall 14 of the
container body 12.
The platform support 78 is connected to a shaft
80 in the housing 76. The shaft 80 in turn, is
connected to a cam follower support bracket 82 which
includes a cam follower 84. The cam follower 84
follows a cam (not shown) which effects axial movement
of the platform support 78 during the reshaping
operation. Accordingly, it is preferred that the
entire apparatus 72 is part of turret assembly.
W096/40457 PCT~3~/033~3
~ 22- 7 ~ 9
The cam follower support bracket 82 is guided by
a plurality of pins 86 which are surround by springs
88. As the forming segments 30 of the shaping mandrel
24 are moved radially outward to engage the inner
surface 36 of the side wall 16, the cam follower is
cammed axially toward the bottom wall 14 of the
container body 12. The pins 86 remain stationary
while the cam follower support bracket 84 moves
axially toward the bottom wall 14 of the container
body 12 compressing the springs 88 and shaft 80 moves
with the cam follower support bracket 82 compresses
springs 90 positioned in a cavity 91 immediately back
of the platform support 78. These springs 90 are
preset to the required external load. In this manner,
the platform support 78 applies a spring biased
external load or force axially to the bottom wall 14
of the container body 12. The external load applied
to the bottom wall 14 keeps the flange 22 of the
container body 12 pressed against the ring 44 in the
housing 26 which contains the shaping mandrel 24. The
external load during the reshaping operation is
believed to assist in the expansion of the side wall
16. When the reshaping operation is completed, the
cam is relieved and the springs 88 force the cam
follower 82, and the platform support 78, in a
direction axially away from the container body 12.
Additionally, the support structure 74 includes
a hollow tube 92 extending from the platform support
78 for effecting a vacuum pressure between the
platform support 78 and the bottom wall 14 of the
container body 12. The tube 92 is connected to a hose
94 which is connected to a pump (not shown). The
vacuum pressure assists in maintaining contact between
the platform support 78 and the bottom wall 14 of the
container body 12. A plurality of O-rings 96 are
position around the tube 92.
W096/40457 PCT~S~ 3
~ 23- 2194779
The platform support 78 can be used for loading
and unloading the container body 12 from the shaping
mandrel 24. The vacuum pressure is particularly
useful for holding the container body 12 to the
platform support during the loading and unloading.
Fig. 2 also discloses a removal sleeve 98 for
moving the container body 12 axially away from the
shaping mandrel 24 after the reshaping operation. A
top view of the removal sleeve 98 is disclosed in Fig.
3.
The removal sleeve 98 includes a main body 100
mounted about two guide rods or posts 102. A first
and a second jaw or clamping element 104, 106 are
pivotly mounted to the main body 100 by pivots 108,
110. The jaws are designed to engage the neck portion
18 of the container body 12 and assist in removal of
the container body 12 from about the shaping mandrel
24.
In an alternative embodiment disclosed in Figs.
4 and 5, a reshaping apparatus 112 is disclosed with
an external tool 114 for providing radially inward
pressure to the expanded portions of the side wall 16.
The external tool is used to create radially inwardly
deformed segments in the expanded portions of the side
wall 16. Fig. 9 discloses the inner mandrel of the
apparatus of Fig. 4 with the outer ring and platform
support removed for clarity.
The external tool 114 includes a plurality of
external forming segments 116 made from hardened
steel. Each forming segment 116 includes an external
contacting surface for contacting or engaging an outer
surface 118 of the side wall 16 of the container body
12. The external forming segments 116 are aligned to
- contact portions of the side wall 16 of the container
body 12 which are in the gaps between the forming
segments 30 of the shaping mandrel 24.
W096/40457 pcT~ssGi!l993~
~ 24- 2 1 ~ 4 7 19 --
The external tool 114 includes an actuator arm
120 having a camming surface 122 which cooperates with
a camming surface 124 on the external forming segment
116. Movement along the direction of the longitudinal
axis of the container body 12, causes the actuator arm
120 to cam the external forming segment 116 radially
inward to deform a portion of the side wall 16
radially inwardly. The actuator arm abuts and
compresses a spring 126 partially held in a channel
128 in an upper portion 130 of the actuator arm.
After the external forming operation, the spring
forces the actuator arm 120 back to its initial
position.
The external forming segments 116 are connected
to pins 132 at one end 134 of the segments 116. The
pins are connected to springs 136. As the actuator
arm 120 is moved to its initial position after the
operation, the springs 136 force the external forming
segments 116 back to their initial positions.
Alternatively, the external forming segments 116
may be fixed in place, that is stationary, with
respect to the side wall 16 of the container body 12.
As the forming segments 30 of the shaping mandrel 24
move radially outward, portions of the side wall 16
are expanded radially outward into contact with the
external forming segments 116 allowing for
simultaneous radially inward deformation of the side
wall 16.
As disclosed in Fig. 5, the actuator arm 120 is
in the form of a ring which has the cross-sectional
shape shown in Fig. 4.
In the embodiment disclosed in Figs. 4, 5 and 9,
the forming segments 30 of the shaping mandrel 24
include a modified contacting surface 137. The
contacting surface 136 includes a first outwardly
convex arcuate portion 138, a second outwardly convex
arcuate portion 140 axially spaced from the first
W096/40457 PCT/U~ /OS3~3
~ 25- 2194719
arcuate portion 138, and a third outwardly convex
arcuate portion 142. These portions 138, 140 and 142
- form corresponding expanded portions in the side wall
16 of the container body as disclosed in Figs. 17-19,
and in Figs. 14-16 without the internally deformed
segments. It is evident that a large variety of
shapes can be formed by modifying the contacting
surface of the forming segments 30 or 116.
A perspective view of the shaping mandrel without
the outer ring in place is shown in Figures 27 and 28.
Figure 27 shows the forming segments 30 in a retracted
position. Figure 28 discloses the forming segments 30
in an expanded position. Figure 29 shows a
perspective view container placed over the shaping
mandrel with an external forming tool 114 surrounding
the container.
In an alternative embodiment, the actuator 24 and
the forming segments 30 of the shaping mandrel 24 can
be configured so as to progressively allow for
reshaping of the side wall 16 of the container body
12. That is, the actuator 24 and the forming segments
30 can be modified to include a dwell time in the
camming surfaces to allow, for example, expansion of
the first arcuate convex surface 138 before beginning
expansion of the second and third arcuate convex
surfaces 140, 142. This may decrease the overall
stress on the side wall 16 when forming more complex
shapes.
In another alternative embodiment, an expanding
apparatus 144 is disclosed in Fig. 6. The apparatus
144 includes a generally annular flexible mandrel 146,
formed from an elastic material such as rubber or
polyurethane, which is positioned in a container body
12. The container body 12 includes a side wall 16
having an initial cylindrical shape. In this
embodiment, the container body 12 does not include a
portion of reducing diameter in the neck portion 18 of
W096/404~7 PCT~9~0g~3
1~" 'S~ ,t ~ 26- 2 1 9 4 7 7 9
the container body 12. This is necessary to enable
insertion and removal of the mandrel 146 from the
container body 12 before and after the expanding
operation.
The mandrel 146 includes a hollow generally
cylindrical ch~nnel or bore 148 having a circular
cross section centrally located in the mandrel 146.
The mandrel 146 also includes an outer shaping surface
147 for contacting the inner surface 36 of the side
wall 16. The outer shaping surface 147 includes an
exterior annular recessed channel 150 which has
diameter which is less than the diameter of the
remaining portions of the outer shaping surface 147 of
the mandrel 146.
In operation, an expanding plunger or punch 152
is forced through the centrally located channel 148
axially toward the bottom wall 14 of the container
body 12. The plunger 152 includes a head portion 154
which has a diameter greater than the diameter of the
channel 148. Since the plunger head 154 has a
diameter greater than the centrally located channel
148, as the plunger head 154 moves axially toward the
bottom wall 14, the outer shaping surface 147 of the
mandrel 146 is moved radially outward into contact
with the inner surface 36 of the side wall 16 and
expands the side wall 16 radially outwardly. As the
plunger head 154 moves to a position axially aligned
with the annular recessed channel 150, the
corresponding portion of the side wall 16 is either
not expanded radially outward at all, or depending on
the depth of the annular channel 150, is expanded
radially outward to a lessor degree than other
portions of the side wall 16. In this manner, a
barrel shape similar to the shaping mandrel 24 of Fig.
4 can be affected. Because the radially outward
deformation or expansion of portions of the side wall
16 results from downward movement (i.e., axially
W096/40457 PCT~S~6/~ 3
~ 27- 2 1 94779
toward the bottom wall 14 of the container body 12) of
the plunger head 154, the expansion of the portions of
- the side wall 16 is carried out gradually rather than
all at once. That is, a portion of the side wall 16
proximate the neck portion 18 is expanded before a
portion of the side wall proximate the bottom wall 14.
As the plunger head 154 passes through any portion of
the channel 148, the mandrel 146 resumes its original
shape due to the elastic nature of the material.
During the expanding operation using a shaping
mandrel 24 with a plurality of forming segments 30,
the segments 30 separate as they move radially outward
and are spaced circumferentially as they contact the
inner surface 36 of the side wall 16. The side wall
16 is thus primarily stretched in the gaps between the
contacting surfaces 34 of the forming segments 30
during the expanding operation (However, as explained
below, proper lubrication between the contacting
surfaces of the forming segments and the interior
surface of the container to obtain an appropriate
coefficient of friction may assist in allowing
material of the side wall abutting the contacting
surfaces to also stretch). This also tends to form
crease lines 160 in the expanded portions of the side
wall 16 as disclosed in Fig. 10. Such crease lines
are not necessarily obtained using the elastic mandrel
146 of Fig. 6 (As explained below, a modified shaping
mandrel can be used to lessen or eliminate the crease
lines).
The outer shaping surface 147 of the mandrel 146
can have a variety of contours or shapes. This will
produce a corresponding variety of shapes in the side
wall 16 of the container body 12.
- As disclosed in Figs. 10-22, the resultant
container body 12 can have a variety of shapes. In
all instances, however, the side wall 16 of the
container body 12 includes at least one portion which
W096/40457 PCT/U'~033~
~ 28 9 4 7 7 5
has been expanded radially outward beyond the initial
cylindrical shape of the container body, and includes
a mean average diameter greater than the mean average
diameter of the initial cylindrical shape.
Additionally, ~uch portions also have a mean average
diameter which is greater than the mean average
diameter of the bottom wall portion 14 of the
container body 12. For container bodies which include
annular outward beading in the bottom wall portion 14,
the outermost portion of the beading is considered in
calculating the mean average diameter of the bottom
wall portion 14.
Referring to Fig. 10, the container body 12
includes a bottom wall portion 14 which has a first
mean average diameter 162. The side wall 16 of the
container body 12 includes a first portion 164 which
has a second mean average diameter approximately equal
to the mean average diameter 162 of the bottom wall
portion 14 and equal to the mean average diameter of
the initial cylindrical shape of the container body.
The side wall also includes a second portion 166 which
has been expanded radially outward. The second
portion 166 has a third mean average diameter 168
which is greater than the mean average diameter of the
first portion 164 and the mean average diameter 162 of
the bottom wall 14. Crease lines 160 are visible in
the second portion 166 from the forming segments 30 of
the inner mandrel 24. The material of the side wall
is primarily stretched in the gaps between the forming
segments during the reshaping operation.
An alternative container body is disclosed in
Figs. 14-16. This container body 12 includes a bottom
wall 14 having a first mean average diameter 170. The
side wall 16 includes a first portion 172 which has a
second mean average diameter approximately equal to
the mean average diameter 170 of the bottom wall
portion 14 and equal to the mean average diameter of
W096/40457 PCT~S9~,/033~
~ 29- 2 î 94779
the initial cylindrical shape of the container body.
The side wall 16 also includes a second portion 174
having a third mean average diameter 176 greater than
the mean average diameter of the first portion 172 and
the mean average diameter 170 of the bottom wall
portion 14. The side wall further includes a third
portion 178 having a fourth mean average diameter
approximately equal to the mean average diameter of
the first portion 172. The side wall further includes
a fourth portion 180 having a fifth mean average
diameter 182 approximately equal to the third mean
average diameter 176. The side wall further includes
a fifth portion 184 having a mean average diameter
approximately equal to the mean average diameter of
the first portion, and a sixth portion 186 having a
mean average diameter approximately equal to the third
mean average diameter. Finally, the side wall
includes a seventh portion 188 having a mean average
diameter approximately equal to the mean average
diameter of the first portion 172.
Figs. 17-19 disclose a further embodiment of a
container body 12 having a side wall 16 with first,
second and third expanded portions 190, 192, 194. The
side wall also include a plurality of inwardly deform
segments 196 spaced circumferentially about the side
wall 16.
Figs. 20-22 disclose a further embodiment of a
container body 12 having a side wall 16 with first and
second expanded portions 198, 200. The shaping
mandrel used to form this container body was
configured so that the forming segments were spaced a
greater than normal distance when contacting the side
wall 16. Slight wrinkles 202 can occur in the gaps
- between the forming segments.
As shown in cross-section in Figs. 23-24, an
alternative shaping mandrel 300 can be utilized with
the reshaping apparatus of the present invention for
W096/40457 PCT~ 3333
~ 30- ~194719
reshaping a container body. The shaping mandrel 300
includes a first forming mechanism in the form of a
plurality of first forming segments 302 which are
spaced about an actuator arm 304. The shaping mandrel
302 also includes a second forming mechanism in the
form of a plurality of second forming segments 306
which are alternately spaced about the actuator arm
304 between the first forming segments 302.
The first forming segments 302 are moveable from
a collapsed or retracted position (as shown in Fig.
24), generally having a diameter which is less than
the diameter of a container body to be expanded and
less than the diameter of the open end of the
container body which may be necked in, to an expanded
position generally having a diameter which is greater
than the initial diameter of the side wall of the
container body (as shown in Fig. 23). Similarly, the
second forming segments are also moveable from a
retracted position to an expanded position.
Each of the first forming segments 302 include a
contacting surface 308 for engaging the interior
surface of the container body. Each of the second
forming segments 306 also include a contacting surface
310 for engaging the interior surface of the container
body. As shown in Figure 24, the second forming
segments 306 are nested between the first forming
segments 302. However, as shown in Fig. 23, when both
the first and second forming segments 302, 306 are
moved to the expanded position, the combined
contacting surfaces 308, 310 are dimensioned to
provide a substantially contiguous surface
circumerentially around the expanded portion of the
side wall. This configuration helps eliminate or
prevent crease lines from forming on the edges 312,
314 of the first forming segments 302.
The actuator arm 304 includes a plurality of
camming surfaces 316 for c~mm~ ng or moving the
W096t40457 PCTtUS9~Og9~3
_ - ~ r ~ 31 - 2 1 9 4 7 7 9
plurality of first forming segments 302 radially
outward, and a plurality of camming surfaces 318 for
moving the plurality of second forming segments 306
radially outward. The c~mmi ng surfaces 3161 318 are
configured to allow the first forming segments to move
radially outward before the second forming segments
306. This can be simply done by adjusting the slopes
of the c~mm; ng surfaces 316 ~ 318.
In operation, the actuator arm 304 is moved
axially to cam the first forming segments 302 radially
outward from the retracted position to the expanded
position. The actuator arm also moves the second
forming segments 306 radially outward from the
retracted position to the expanded position. The
second forming segments 306 are positioned to move
into the gaps between the first forming segments 302
when expanded.
Figures 25-26 disclose a slightly modified
embodiment of a shaping mandrel 320 having a first
forming mechanism and a second forming mechanism. In
this embodiment, the second forming mechanism includes
a plurality of second forming segments 322 where each
second forming segment 322 includes an integral
camming surface 324. The integral camming surfaces
324 of the second forming segments 322 are utilized to
cam radially outward a plurality of first forming
segments 326 of the first forming mechanism from a
retracted position to an expanded position.
The actuator arm 328 includes a plurality of
camming surfaces for camming or moving the plurality
of second forming segments 322 radially outward from
a retracted position to an expanded position. As the
second forming segments 322 are moved radially
outward, the camming surfaces 324 of the second
forming segments 3221 in turn move the first forming
segments 326 radially outward. In both embodiments,
the contacting surfaces of the first and second
W096/40457 PCT/u~,G/~33~3
~ 32- 2 ~ 94779
forming segments can be polished to a surface
roughness of 0.3 microns.
Through initial testing, it is believed that the
friction between the contacting surfaces of the
forming segments and the interior surface of the side
wall of the container body plays an important role in
achieving optimal radially outward expansion. In the
expanding operations described above with respect to
the apparatuses disclosed in Figures 1, 4, and 9, the
shaping mandrel includes a plurality of forming
segments which are cammed radially outward to engage
the interior surface of the side wall. As the forming
segments move radially outward they become
circumferentially spaced apart and leave gaps between
consecutive forming segments. If the coefficient of
friction between the contacting surfaces of the
forming segments and the segments of the interior
surface of the side wall which abut the contact
surfaces is too high, then the material in such side
wall segments will effectively lock against the
contacting surfaces during the expansion operation.
That is, all of the stretching will be accomplished by
the material of the side wall in the gaps between the
forming segments. This limits the amount the side
wall can be expanded.
By providing a lubricant between the contacting
surfaces of the forming segments and the interior
surface of the side wall, the coefficient of friction
can be lowered to enable the material of the side wall
abutting the contacting surfaces to stretch
circumferentially, as well as slightly shrink axially,
during the expansion operation. This decreases the
stress on the material in the gaps, and allows for
greater expansion of the side wall. In affect, the
lower coefficient of friction is believed to allow the
material abutting the contacting surfaces to slip
against such surfaces.
W096/40457 PCT~ 33~3
~ P ~ - 33 9 7 7 9
The interior surface of the container body is
typically provided with an internal coating to protect
the product when filled. The lubricant can be
externally applied or sprayed onto the protective
5 coating before the expanding or reshaping operation.
This lubricant can then be washed away, or if not
harmful to the product, left in the container body.
Alternatively, the lubricant can be an incorporated as
an internal component of the protective coating. In
this form, the following coatings with internal
lubricants provide good expansion properties as well
as meet product protection requirements: Dexter-
Midland's CR023-142 (which includes 0. 5~ carnauba
wax); Dexter-Midland's CR023-144 (which includes 1.5~
carnauba wax); and Glidden's (ICI) 640-C-~96 (which
includes 0. 5~ carnauba wax). The Dexter-Midland
- CR023-144 permits the container to be stretched
farther than the other two coatings. However, the
Dexter-Midland CR023-142 and the Glidden coatings show
20 less dewetting during application of a respray, which
may be an important factor if respray of the coating
is determined to be necessary in the commercial
production of expanded containers.
In addition to the three coatings discussed,
25 initial testing has been performed with coatings
having either 5~ or 1. 5~ (by weight) of a Teflon
modified polyethylene wax as the internal lubricant.
The coating with the 1. 5~ lubricant allows for even
further stretching than the Dexter-Midland CR023-144.
30 However, this coating has not been tested as to
whether it meets the product protection requirements.
It has been found that a coefficient of friction
between the contacting surfaces of the forming
- segments and the interior surface of the side wall
35 should be less than about 0.1, and preferably in the
range of 0.02 - 0.075. A coefficient of 0.05 has been
found to give good results.
WO 96/40457 PCT/US96~0~3~3
r ~ 34- Z 1 9 4 7 7 9
Figures 30-33 discloses another embodiment of a
seamless container body 33 0 formed in accordance with
the present invention. The container body 330
includes a plurality of expanded portions 332,334,336
6 and a plurality of inwardly deformed portions 338.
The container disclosed in Figures 30-33 is
preferably formed from a drawn and ironed container
body having a side wall diameter of between 2.4770" to
2.4830" and a height of about 5.170" measured from the
support base to an outwardly directed flange at the
open end. The container body includes a frustoconical
necked-in portion. The side wall of the container
body prior to the expansion operation has a material
thickness of approximately 0. 0049" to 0. 0052", and
includes transition zones of increasing metal
thickness between the side wall and the junctures
340, 342 between the necked-in portion at one end and
the bottom portion at the opposite end, respectively.
These transitions can extend up to . 5 " into the side
wall area. As shown in Figure 30 and 31, the expanded
portions 336, 332 extend into the transition zones of
the side wall. The diameter of the expanded portions
332, 334, 336 are preferably 2 . 60 " which is an increase
in diameter of approximately 5~.
While specific embodiments have been illustrated
and described, numerous modifications come to mind
without markedly departing from the spirit of the
invention. The scope of protection is thus only
intended to be limited by the scope of the
3 0 accompanying claims.
