U.S. patent application number 11/811362 was filed with the patent office on 2008-12-11 for metal container with screw-top closure and method of making the same.
This patent application is currently assigned to Silgan Containers Corporation. Invention is credited to Gerald Baker, Matt R. Brown, Bill Kapolas, Seth Moore.
Application Number | 20080302799 11/811362 |
Document ID | / |
Family ID | 40094910 |
Filed Date | 2008-12-11 |
United States Patent
Application |
20080302799 |
Kind Code |
A1 |
Moore; Seth ; et
al. |
December 11, 2008 |
Metal container with screw-top closure and method of making the
same
Abstract
A food or drink container kit includes a metal container
including a round threaded neck having at least one integrally
formed thread. The kit also includes a metal press-on, twist-off
closure comprising a round skirt including a gasket material
located on at least a portion of the interior of the skirt, a seal
forming between the neck and skirt when the closure is placed on
the container and heated.
Inventors: |
Moore; Seth; (Oconomowoc,
WI) ; Brown; Matt R.; (Eau Claire, WI) ;
Baker; Gerald; (Wauwatosa, WI) ; Kapolas; Bill;
(Des Plaines, IL) |
Correspondence
Address: |
FOLEY & LARDNER LLP
777 EAST WISCONSIN AVENUE
MILWAUKEE
WI
53202-5306
US
|
Assignee: |
Silgan Containers
Corporation
|
Family ID: |
40094910 |
Appl. No.: |
11/811362 |
Filed: |
June 8, 2007 |
Current U.S.
Class: |
220/288 ; 215/44;
426/397; 426/407; 72/379.4; 72/46 |
Current CPC
Class: |
B65D 41/17 20130101;
B65D 7/04 20130101; B65D 41/0457 20130101; B65D 53/06 20130101 |
Class at
Publication: |
220/288 ; 215/44;
426/397; 426/407; 72/379.4; 72/46 |
International
Class: |
B65D 41/04 20060101
B65D041/04; B65B 55/02 20060101 B65B055/02 |
Claims
1. A food or drink container kit, comprising: a metal container
including a round threaded neck having at least one integrally
formed thread; and a metal press-on, twist-off closure comprising a
round skirt including a gasket material located on at least a
portion of the interior of the skirt, a seal forming between the
neck and skirt when the closure is placed on the container and
heated.
2. The container kit of claim 1, wherein the threaded neck
comprises a single continuous thread.
3. The container kit of claim 2, wherein a beginning of the single
thread and an end of the single thread overlap relative to a
vertical axis of the threaded neck.
4. The container kit of claim 1, wherein the threaded neck
comprises multiple independent threads.
5. The container kit of claim 1, wherein the threaded neck,
threads, closure, and gasket material are sized and configured so
that mating threads are formed in the gasket material when the
skirt is placed on the container and heated.
6. The container kit of claim 1, wherein the skirt of the closure
is smooth such that a metal structure of the skirt does not prevent
the closure from being pressed onto the threaded neck.
7. The container kit of claim 1, wherein the threaded neck
comprises metal that is about 0.007 inches to 0.009 inches
thick.
8. The container kit of claim 1, wherein the threaded neck
comprises metal that is about at least 0.007 inches thick.
9. The container kit of claim 1, wherein metal forming the threaded
neck and the at least one threads has been thinned less than about
12 percent.
10. The container kit of claim 1, wherein metal forming the
threaded neck and the at least one threads has been thinned less
than about 10 percent.
11. The container kit of claim 1, wherein the gasket material is a
plastisol material.
12. The container kit of claim 1, wherein the container body
further comprises a preservative coating lining its interior
surfaces.
13. The container kit of claim 1, wherein container and closure are
configured to maintain the seal during a thermal retort
process.
14. The container kit of claim 13, wherein the thermal retort
process is a process wherein the container with closure sealably
installed onto the threaded neck and at least partially filled with
perishable material is heated to a temperature of about at least
220 degrees with overriding pressure.
15. The container kit of claim 1, wherein the threaded neck
includes a top neck edge wherein metal of the top neck edge has
been curled toward the exterior of the threaded neck.
16. The container kit of claim 1, wherein the threaded neck
includes a top neck edge wherein metal of the top neck edge has
been curled toward the interior of the threaded neck.
17. The container kit of claim 1, wherein the threaded neck
includes a top neck edge wherein metal of the top neck edge has
been curled toward the interior of the threaded neck and wherein
the interior of the curl is sealed with a sealing compound.
18. The container kit of claim 1, wherein a top end of the
container includes a frusto-conical portion uniformly angling
toward a center of the container before forming a substantially
vertical structure from which the threaded neck is formed.
19. A method for creating a metal container of the type closable
with a press-on, twist-off closure, comprising: providing a blank
of material; forming a cup from the blank of material, the cup
having a closed cup end, side walls, and an open cup end; forming
the closed cup end to create a neck and a primary container
opening; forming at least one thread in the neck; and attaching a
bottom part to the open cup end to form a metal body that is closed
except for the primary container opening, such that once the metal
container is filled, once the press-on, twist-off closure is
pressed onto the neck, and once the container is heated, a seal is
formed between the closure and the metal container.
20. The method of claim 19, wherein the seal is formed by heating
the closure as it is pressed onto the neck and the seal is
maintained by processing the container.
21. The method of claim 19, further comprising coating the interior
of the container with a preservative material prior to filling the
container with food.
22. The method of claim 19, further comprising at least partially
filling the metal body with food through the primary container
opening.
23. The method of claim 19, further comprising pushing a press-on
twist-off closure onto the at least one thread formed in the
neck.
24. The method of claim 19, wherein the filled container is
suitable for use with a thermal retort process so that a seal may
be maintained during and after the thermal retort process.
25. The method of claim 24, wherein the thermal retort process is a
process wherein the container with closure sealably installed onto
the threaded neck and filled with food is heated to a temperature
of about at least 250 degrees.
26. The method of claim 24, wherein the thermal retort process is a
process wherein the container with closure sealably installed onto
the threaded neck and filled with food is heated to a temperature
of about at least 220 degrees for a time period of more than 20
minutes.
27. The method of claim 24, wherein the thermal retort process is a
process wherein the container with closure sealably installed onto
the threaded neck is heated to about 245 degrees Fahrenheit with
about 30 pounds per square inch of overriding pressure for a period
of at about 40 minutes and about a 3 pounds per square inch
differential between overriding pressure and internal pressure is
maintained.
28. A container made by the process of: filling a metal container
with food, the container comprising a preservative coating lining
interior surfaces of the container and a threaded neck having at
least one integrally formed thread configured to receive a closure;
pressing a press-on, twist-off closure onto the threaded neck, the
closure comprising an interior surface and a plastisol gasket
material lining at least a portion of the interior surface, wherein
the closure and the threaded neck are configured to maintain a seal
when subjected to a heating and cooling process such that the
plastisol gasket material lining the interior surface of the
closure resiliently engages the at least one integrally formed
threads; and heating the container to sterilize the food contained
within the container and to create a vacuum that provides a
physical force that helps securably hold the press-on, twist-off
closure onto the container.
29. A food or drink storage apparatus, comprising: a metal
container including a round threaded neck having at least one
integrally formed thread; and a metal press-on, twist-off closure
comprising a round skirt including a gasket material located on at
least a portion of the interior of the skirt, a seal forming
between the neck and skirt when the closure is placed on the
container and heated.
Description
BACKGROUND
[0001] The application generally relates to metal food containers.
The application relates more specifically to metal food containers
with screw-top closures and methods of making the same.
[0002] Metal containers are used to store a variety of materials
and objects. Some types of metal containers are used to store
perishable material such as organic material, solid food, food
having a liquid component, and liquids. These containers must often
meet a variety of requirements depending on their intended use. For
example, some containers must be able to withstand acidity of
certain levels such that the container's intended contents do not
compromise the container. Other containers must be able to
successfully store liquid such that manipulation of the container
during shipping and typical use do not cause the container to
deform, break an airtight seal, and/or leak the container's
contents. Yet other containers must be able to withstand food
cooking processes involving the container.
[0003] While some containers are filled with uncooked food or
pre-cooked food then sealed for later consumption, other containers
are filled with uncooked food, the container is sealed, and the
food is cooked or sterilized while sealed within the container.
This process is commonly called a thermal retort process. Thermal
retort processes often have certain advantages. First, cooking food
within the container is often faster than cooking food outside of
the container. Second, cooking the food inside the container helps
to sterilize the food and the container. Third, end-users often
appreciate pre-cooked food contents as preparation times are often
shorter and more convenient. Fourth, sealing food contents then
sterilizing via a thermal retort process helps maintain the seal
and preserves the food contents.
[0004] Many conventional containers used with thermal retort
processes use ends that may only be opened once and are not easily
reclosed or resealed. For example, some conventional containers
suitable for use with thermal retort processes are metal cans
having an end designed for use with a can-opener. Other
conventional containers suitable for use with thermal retort
processes are metal cans having "pop-tops", "pull tops",
convenience ends, or convenience lids. Thermal retort processes
present challenges to the design and manufacture of reclosable
and/or resealable metal cans. For example, the pressure and
temperature rigors of the thermal retort process may compromise the
seal with the thread structures. In addition, traditional methods
of making metal food containers are often incompatible with the
precise forming steps often required to create adequate reclosable
structures (e.g., screw-top threads).
[0005] Therefore, it is desirable to provide a metal container
having a reclosable feature. Further, it is desirable to provide a
reclosable metal container suitable for use with thermal retort
processes. Further, it is desirable to provide a reclosable metal
container having a screw-top that end-users may conveniently open
and reclose. Further, it is desirable to provide a reclosable metal
container having threads and a closure capable of withstanding a
thermal retort process.
[0006] What is needed is a container and/or method of making the
same that satisfies one or more of these needs or provides other
advantageous features. Other features and advantages will be made
apparent from the present specification. The teachings disclosed
extend to those embodiments that fall within the scope of the
claims, regardless of whether they accomplish one or more of the
aforementioned needs.
SUMMARY
[0007] One embodiment relates to a food or drink container kit. The
container kit includes a metal container including a round threaded
neck having at least one integrally formed thread. The container
kit also includes a metal press-on, twist-off closure comprising a
round skirt including a gasket material located on at least a
portion of the interior of the skirt, a seal forming between the
neck and skirt when the closure is placed on the container and
heated.
[0008] Another embodiment relates to a method for creating a metal
container with a press-on, twist-off closure. The method includes
providing a blank of material and forming a cup from the blank of
material. The cup has a closed cup end, side walls, and an open cup
end. The method further includes forming the closed cup end to
create a neck and a primary container opening and forming at least
one thread in the neck. The method yet further includes attaching a
bottom part to the open cup end to form a metal body that is closed
except for the primary container opening, such that once the metal
container is filled, once the press-on, twist-off closure is
pressed onto the neck, and once the container is heated, a seal is
formed between the closure and the metal container.
[0009] Another embodiment relates to a container made by a process.
The process includes filling a metal container with food, the
container comprising a preservative coating lining interior
surfaces of the container and a threaded neck having at least one
integrally formed thread configured to receive a closure. The
process further includes pressing a press-on, twist-off closure
onto the threaded neck, the closure comprising an interior surface
and a plastisol gasket material lining at least a portion of the
interior surface, wherein after heating the closure a seal is
created with the threaded neck, capable of withstanding a heating
and cooling process such that the plastisol gasket material lining
the interior surface of the closure resiliently engages the at
least one integrally formed threads. The process yet further
includes heating the container to sterilize the food contained
within the container and to create a vacuum that provides a
physical force that helps securably hold the closure onto the
container.
[0010] Another embodiment relates to a food or drink storage
apparatus. The storage apparatus includes a metal container
including a round threaded neck having at least one integrally
formed thread. The storage apparatus also includes a metal
press-on, twist-off closure comprising a round skirt including a
gasket material located on at least a portion of the interior of
the skirt, a seal forming between the neck and skirt when the
closure is placed on the container and heated.
[0011] Alternative exemplary embodiments relate to other features
and combinations of features as may be generally recited in the
claims.
BRIEF DESCRIPTION OF THE FIGURES
[0012] The application will become more fully understood from the
following detailed description, taken in conjunction with the
accompanying figures, wherein like reference numerals refer to like
elements, in which:
[0013] FIG. 1 is a perspective view of a metal container having a
threaded neck, according to an exemplary embodiment;
[0014] FIG. 2 is a side profile view of a metal container having a
threaded neck, according to an exemplary embodiment;
[0015] FIG. 3 is a close-up side profile view of the threaded neck,
according to an exemplary embodiment;
[0016] FIG. 4 is a close-up side profile view of the threaded neck
having a press-on twist-off closure installed, according to an
exemplary embodiment;
[0017] FIG. 5 is a partial sectional view of the container
threading having the closure installed, according to an exemplary
embodiment;
[0018] FIG. 6 is a partial sectional view of the container
threading having the closure installed, according to an alternative
embodiment;
[0019] FIG. 7A is a side profile view of a threaded neck, according
to an alternative embodiment;
[0020] FIG. 7B is a side profile view of a threaded neck having a
closure installed, according to an alternative embodiment;
[0021] FIG. 8 is a flow chart of a method of making the metal
container, according to an exemplary embodiment.
[0022] FIG. 9 is a side profile view of a metal container during
manufacturing, prior to forming threading into the container neck,
according to an exemplary embodiment.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0023] Before turning to the figures which illustrate the exemplary
embodiments in detail, it should be understood that the application
is not limited to the details or methodology set forth in the
following description or illustrated in the figures. It should also
be understood that the phraseology and terminology employed herein
is for the purpose of description only and should not be regarded
as limiting.
[0024] Referring generally to the figures, a metal container (i.e.,
a can) is shown having a threaded neck integrally formed from the
metal of the container body. The threads are formed to fit a
screw-top closure and the closure is a press-on/twist-off closure.
The container is suitable for use with a thermal retort process.
Referring still to the figures in general, a process of making a
metal container is provided so that the integrally formed threads
are formed from a relatively unworked or un-thinned portion of
metal once the majority of the container body has been formed.
[0025] Referring to FIG. 1, a perspective view of metal container 1
is shown, according to an exemplary embodiment. Metal container 1
includes a top end 2, a body 4, and a bottom end 6. Container 1 and
body 4 are shown as substantially cylindrical (i.e., the container
walls or piece forming body 4 are curvilinear). According to
various other embodiments, container 1 may take any number of other
container shapes as may be desirable for different applications or
aesthetic qualities. For example, container 1 may be formed to have
one or more angles that create a polygonal cross-section such as a
rectangular cross section. Container 1 and body 4 could also be
formed to have any number of edges, curves, and/or beads as may be
desirable for end-users and/or for structural integrity purposes.
Metal container 1 may be sized to store about eight ounces of
liquid contents or may be sized differently (e.g., less than eight
ounces, more than eight ounces, twelve ounces, sixteen ounces,
thirty two ounces, etc.).
[0026] According to an exemplary embodiment, the metal of container
1 is about 0.008 inches thick and is primarily made of tin plated
steel. According to various other exemplary embodiments, the metal
of container 1 is formed from steel having a working gauge range
from about 0.006 inches thick to about 0.013 inches thick, or other
available working ranges. According to various other alternative
embodiments, container 1 may be formed of aluminum, tin free steel,
and/or another metal material that may be used to form metal food
containers. The material of container 1 may also be more or less
thick along certain structures or locations of body 4. For example,
in the middle of the side walls of container body 4, the material
may be more thin than material closer to the top end or bottom
end.
[0027] The top of container 1 and container body 4 angles inward to
create a frusto-conical portion 8. A threaded neck 10 extends from
the frusto-conical portion 8. According to an exemplary embodiment,
frusto-conical portion 8 is angled around thirty-seven degrees from
the vertical surfaces of body 4 and sized so that the diameter of
the neck with a closure installed thereon is smaller than the
diameter of body 4. According to various other embodiments,
frusto-conical portion 8 is angled more or less than thirty-seven
degrees from vertical. This sizing and structure may create an
aesthetically pleasing container top, provide a user with increased
leverage for opening the screw-top, and/or prevent the container
top, threads, and closure from experiencing some amount of the
unavoidable contact that containers typically have with adjacent
containers or other structures during manufacture, shipping, and/or
use. According to other various exemplary embodiments,
frusto-conical portion 8 may not be present on the container, may
be characterized as a cone-shaped shoulder area, or may take any
other shape or size.
[0028] Referring to FIG. 2, a side view of metal container 1 is
shown, according to an exemplary embodiment. At bottom end 6 of
metal container 1, one or more bottom seal structures 21 may
fixably seal a bottom end piece to container body 4. According to
an exemplary embodiment, bottom seal structures 21 are a double
seam including folds of metal adjoining a container flange (e.g.,
92 shown in FIG. 9) and a bottom end piece (i.e., sanitary end) so
that a substantially hermetic seal is created.
[0029] Referring to FIGS. 2 and 3, detail of threaded neck 10 is
shown, according to an exemplary embodiment. Threaded neck 10 is
integrally formed from the metal of container I, container body 4,
and/or frusto-conical portion 8. Threaded neck 10 extends upward
from frusto-conical portion 8 along the vertical axis of container
body 4. The radius and height of threaded neck 10 is generally
determined based on the radius and depth of the closure with which
the threaded neck will be used. A lower ring 12 and one or more
thread 14 extend from threaded neck 10.
[0030] According to an exemplary embodiment, thread 14 is a single
thread conforming to the Glass Packaging Institute's (GPI) glass
finish designation number 465, last revised Feb. 5, 1999. According
to other alternative embodiments, different thread designations or
specifications may be used to create the container's threads (e.g.,
GPI glass finish designation number 2215, etc.).
[0031] Neck edge 16 will generally be curled or rounded to provide
a suitable sealing surface (e.g., uniform and having some
substantial diameter relative to the gauge of the container walls).
Neck edge 16 may also be curled or rounded to provide a suitable
surface for mouth contact or drinking. For example, neck edge 16 is
shown as a curled neck edge, curling to the exterior of threaded
neck 10. The exterior diameter of the neck and structures of the
neck may be appropriately sized to allow the closure to function
properly. According to an exemplary embodiment, the neck is sized
per certain threading specifications (e.g., GPI glass finish
designation number 2215, 465, etc.).
[0032] Referring to FIG. 4, a side view of metal container 1 is
shown, metal container 1 having closure 40 (e.g., cap, cover, top,
etc.) shown installed on a round threaded neck 10 of the previous
FIGS., according to an exemplary embodiment. Closure 40 includes a
closure top end 42, a round closure skirt portion 44 and a closure
bottom rim 46. When closure 40 is installed onto threaded neck 10,
closure bottom rim 46 is adjacent lower ring 12. Closure 40 may
have a diameter of 40 millimeters (e.g., shown as diameter "D" on
FIG. 4), but may be sized differently to fit differently sized or
configured threaded necks. According to one alternative embodiment,
closure 40 is a 48 mm diameter closure. According to an exemplary
embodiment, relatively deep closures may be desirable for use with
threaded necks having a single thread. According to an exemplary
embodiment, closure 40 has a closure style of "40 DER" that may be
described as having a diameter of 40 mm, a deep closure skirt, and
a vacuum safety button that requires a 20 inch Hg vacuum to verify
the seal is intact. According to various other exemplary
embodiments, the closure may include other tamper evidencing
features or no tamper evidencing features.
[0033] Referring to FIG. 5, a sectional view of threaded neck 10
and closure 40 are shown, according to an exemplary embodiment.
Closure 40 is a press-on, twist-off type metal closure (i.e.,
push-on/twist-off cap, etc.). A press-on, twist-off closure refers
to a closure that is initially coupled to a body by a press-on
(i.e., push-on) movement, but then is later removed or reattached
by a twisting motion. According to an exemplary embodiment, closure
skirt portion 44 is smooth such that closure skirt portion does not
have any threads or other metal structures that would prevent
closure 40 from being pressed onto the threaded neck or threads of
a container. According to various alternative embodiments, closure
40 may be a plastic closure or another closure other than
metal.
[0034] According to an exemplary embodiment, the metal of closure
40 is between about 0.006 inches and 0.008 inches thick. Closure
underside or interior surface 41, along at least some of the
closure skirt portion 44, is coated with a gasket or gasket
material 50. According to an exemplary embodiment, gasket 50 is a
plastisol material or compound applied to the top and side surfaces
of closure underside 41. Materials other than plastisol may serve
as the gasket. Plastisol may provide sufficient resistance to acids
of food products that may come into contact with the plastisol, may
permit hot-fill processes to produce a vacuum seal, and may
withstand a heat-based sterilization or cooking process. A
sufficient amount of the gasket material coats closure underside 41
such that the outer diameter of thread 14 is larger than the inner
diameter of gasket 50. The plastisol compound does not contain
preformed thread indents or receiving structures. Rather, steam or
another application of heat is used to soften the plastisol
material prior to pushing the material onto the threaded neck of
the container. The difference between the diameter of the gasket
material and the structures of threaded neck 10 cause the softened
gasket 50 to move and flow around thread 14 so that many portions
of threaded neck 10 are surrounded by gasket 50 such that the
interface(s) between threaded neck 10 and gasket 50 form a hermetic
seal. Following cooling of the plastisol, the plastisol stiffens or
hardens to create a resilient foam that may act to maintain the
hermetic seal with threads 14. The cooled plastisol may have a
semi-permanent or permanent impression of the structures of the
threaded neck such that the closure may be removed and/or reclosed
or resealed with a twist-off or twist-on motion.
[0035] According to an exemplary embodiment, gasket 50 specifically
comprises a plastisol compound that may be characterized as a "508
compound" or similar material. Gasket 50 may be a liquid applied
gasket or any other suitable gasket material.
[0036] Referring to FIG. 6, a sectional view of a threaded neck and
closure 40 is shown, according to an alternative exemplary
embodiment. In the embodiment shown in FIG. 6, neck edge 17 is
curled to the interior of the threaded neck. Sealing compound 61
may prevent a raw metal edge from exposure to moisture that may
rust and/or corrode the raw metal.
[0037] Referring to FIGS. 7A and 7B, a side view of a threaded
container neck having multiple independent threads is shown,
according to an alternative embodiment. Multiple independent
threads may allow the height of a closure to be decreased.
[0038] Referring to FIG. 8, a flow chart of a process of making and
using a metal container such as metal container 1 shown in the
previous FIGS. is shown, according to an exemplary embodiment.
Metal container 1 may be made using a variety of methods. For
example, metal container 1 may be formed using a drawn and ironed
manufacturing process, a drawn and redrawn manufacturing process,
and/or a variety of alternative manufacturing processes. According
to the embodiment shown in FIG. 8, a drawn and ironed process is
used to manufacture metal container 1. Raw material may come from a
source in a variety of forms. For example, raw material may come
from a metal supplier in a large coil. This coil may be upended or
otherwise moved into a position to be unreeled by an unreeler. The
unreeled metal from the unreeler may be fed into a lubricator.
Lubricant may be applied to the unreeled metal by a series of
rollers or otherwise. Lubricant improves the workability of the raw
material later in the process.
[0039] A blank may be formed from the lubricated raw material or
otherwise provided (step 802). The blank may be sized such that the
blank may be formed to create the container body. Blanks may be
formed using a variety of processes including cutting processes.
For example, the blanks may be formed using a press cut-activity. A
cupping press machine may cut a blank that is shaped like a disk.
Once a blank has been formed or otherwise provided, the blank is
formed into a cup (step 804). This cup forming activity may take
place within the same machine and close-in-time to the blank
cutting step. For example, a single machine may act in a double
action; a first action may cut the blank and a second action may
form the cup. A cup may then be ejected and advanced to the can
handling system.
[0040] The cup formed from the blank may be a relatively short or
squat cup. The bottom of the cup will be approximately the same
metal thickness as the original blank. The sides of the cup may be
worked slightly and may be thinner than the original metal of the
blank. Depending on the target height of the metal container, the
cup will be subjected to a drawn and ironed process that forms the
container body shape from the cup (step 806). The container body
shape may be formed using a machine generally referred to in the
art as a "bodymaker." This machine works or forms the cup with a
punch and ironing rings in a progression to form the shape and size
of the container's body walls. While this drawn and ironed process
allows the container to be formed to a height taller than the cup,
the ironing reduces the wall thickness and often results in the
walls being too thin and/or brittle to reliably form fine and
precise structures such as threads. The base of the formed
container, however, is still approximately the same metal thickness
as the original blank (i.e., the original cup base is still the
base of the formed container as of this step, and is relatively
unworked and un-thinned). This relatively unworked or un-thinned
container base may be reliably formed into the thread. So, the base
of the formed container shape, or the cup bottom, becomes the top
of the final container body and the container neck is formed using
the base of the formed container (step 808). During this step or
another step, the container neck may be cut to create the primary
container opening that the closure will cover. According to various
exemplary embodiments, the primary container opening may be cut
prior to forming the neck from the base of the formed
container.
[0041] After the neck has been formed and the primary container
opening has been cut, threading may be formed from the container
neck (step 810). The threading may be formed using an interior
press, an exterior press, and/or any other suitable thread forming
process. The threads may be formed to fit a press-on twist-off
closure. According to an exemplary embodiment, the thread or
threads may also be formed such that a threaded neck and thread
metal thickness of about at least 0.007 inches is maintained. In
addition to maintaining a certain thickness of the metal, it may be
important to maintain a certain low percentage of thinning. For
example, while the sides of the container may be thinned during the
drawing process down to about forty percent of the original
thickness of the blank, the metal used to form the threaded neck
and the threads should not be thinned by more than ten percent of
the original blank thickness. According to an exemplary embodiment,
no portion of the threaded neck and/or threads are thinned more
than 12 percent and maintain a thickness of about at least 0.007
inches. According to various alternative embodiments, greater
thinning percentages (e.g., thread thinning of greater than 12
percent, thinning of up to 30 percent, etc.) may be used to create
the threaded neck and/or threads. According to yet other various
embodiments, container wall and/or thread thickness may be less
than 0.007 inches.
[0042] According to various exemplary embodiments, the threading
will be thick enough and resilient enough to withstand various
typical thread forming and container handling processes. The
threading should be prominent enough so that when human applied
rotation of the closure relative to the container body occurs, the
threads provide enough leverage in the plastisol to break the
vacuum seal (e.g., around 20 inHg) holding the closure onto the
container body. The threading may thereby be configured to allow
the consumer easy initial access to the container contents and
thereafter allow the consumer to reclose the container with
sufficient thread-provided leverage and threading accuracy to
create a liquid-type seal (i.e., substantially watertight) upon
reclosure.
[0043] The container end opposite the neck (i.e., the can bottom
end) may be fixably enclosed (step 812) after a variety of steps in
the process. According to an exemplary embodiment, a container
bottom end part is attached to the container end opposite the neck
(i.e., the can bottom end shown in FIGS. 1 and 2) such that a
bottom most portion of the container body side walls and the edge
of a bottom end are interfolded together to create a fixed and
hermetic seal.
[0044] After both the top end and bottom end of the container are
formed, the container may be filled (step 814). While the open
container may be filled with any variety of materials or contents,
the container is filled with food according to an exemplary
embodiment. The food may be pre-cooked, partially pre-cooked,
warmed, or cool. According to an exemplary embodiment, the
container is hot-filled.
[0045] Once the container has been filled, the closure may be
pressed onto the threaded neck (step 816). Step 816 may include
heating the closure prior to and/or during the activity of pressing
the closure onto the threaded neck. According to an exemplary
embodiment, the closure is a press-on, twist-off closure lined with
a plastisol material. The plastisol may be partially fluid,
softened, and/or heated prior to pushing the closure onto the
threads such that the friction between the plastisol material and
the threaded structures is low enough to allow the closure to be
fully applied (i.e., installed, slidably installed, rotatably
installed) and/or formed around the threads (e.g., pressed onto the
threads). According to an exemplary embodiment, steam or hot air
may be applied to the closure to adequately soften the plastisol
material prior to pressing the closure onto the threads. According
to various exemplary embodiments, the steam temperature applied to
the closure is around 190 degrees Fahrenheit to 210 degrees
Fahrenheit.
[0046] The container may be subjected to a thermal retort process
(step 818). A thermal retort process may generally be characterized
as a process of subjecting the filled and closed container to a
cooking or sterilization process having different heat, time, and
pressure variables sufficient to substantially sterilize the
interior and contents of the food container. Some thermal retort
processes may be overpressure thermal retort processes where
pressure outside the container is substantially matched or slightly
exceeded relative to the pressure that builds on the inside of the
container due to heating a sealed container. Overpressure thermal
retort processes may generally include inserting a filled and
closed container (or group of containers) into a retort vessel that
heats the container via steam, water, or a combination of steam and
water and provides overpressure to prevent container deformation or
breakage due to pressure build-up inside the container.
[0047] During a thermal retort process, the container and the food
inside the container will be brought to a temperature of about at
least 200 degrees Fahrenheit. According to various exemplary
embodiments, a thermal retort process may include bringing the
container to a temperature of between 220 degrees Fahrenheit and
260 degrees Fahrenheit. According to yet other embodiments, a
thermal retort process includes bringing the container to a
temperature of at least 240 degrees Fahrenheit. According to a
preferred embodiment, the container and closure should be able to
withstand a thermal retort process of about 250 degrees Fahrenheit
with about 32 pounds per square inch of overriding pressure for a
period of about 45 minutes and a 3 pounds per square inch
differential between overriding pressure and internal pressure.
Processing step 818 may also include steps of controllably ramping
up temperature, cooking, and then controllably bringing temperature
down or dropping temperature so that a strong vacuum (e.g., 20 inHg
to 25 inHg,) is formed between the closure and container body that
substantially holds the closure onto the neck and maintains the
hermetic seal. According to various other exemplary embodiments, a
weaker or stronger vacuum may be created and maintained.
[0048] The specifications of the thermal retort process will vary
depending on the food being cooked, the machinery (e.g., retort
vessel) being used, the amount of agitation used with the heat, and
any number of other variables. It may be desirable to cook
different types of food to certain different minimum temperatures
for certain different minimum amounts of time to ensure
sterilization. A container and closure of the present application
should be able to withstand a variety of typical temperature, time,
and pressure levels such that the container may be considered
suitable for use with a thermal retort process for a wide variety
of foodstuffs, including, for example, adult nutritional drinks, to
those skilled in the art of food sterilization using a retort
process.
[0049] During the manufacturing process, the metal container may
also be washed and coated as required for workability, cleanliness
of the container, and longevity of the container surfaces when
subjected to container contents, liquids, and/or air.
[0050] Referring to FIG. 9, a profile view of a container body
prior to forming the threading is shown, according to an exemplary
embodiment. As discussed above with reference to the process of
FIG. 8, a container neck 90 will be formed using the base of the
formed cup or container shape. Container neck 90 may be formed
prior to or after cutting a primary container opening into the
container. Unformed container neck 90 may be taller than a formed
threaded neck as the forming process will generally shorten the
neck as it bends or otherwise uses the material of the neck in
shaping the thread or threads. Furthermore, excess material may be
cut or otherwise removed from the top of container neck 90 and/or
the edges may be rolled or folded over to create the outward or
inward rolls of FIGS. 5 and 6. Referring still to FIG. 9, bottom
end flanges 92 may be formed or created by machinery of the
container's manufacturing process to provide a beginning interface
or structure that a bottom end part may be interfolded with to
create a fixably attached and hermetically sealed (e.g.,
dry-sealed) bottom end.
[0051] According to one alternative embodiment, it may be desirable
to pre-coat the interior of a metal food container to ensure that a
thorough and even application of protective coating is applied to
the interior of the container. Using pre-coated blanks of material,
however, it may be desirable to form the container using a process
other than a drawn and ironed process described above. In this
process, a container may be formed using one or more steps to form
the basic shape of the container. More particularly, a metal
container using pre-coated material may be made by the process of
forming a container body from a blank of pre-coated metal, forming
a threaded neck from a top end of the container body to create an
integrally formed thread configured to receive a closure, and
filling the container body with foodstuffs. Once filled, the
process may further include pushing a closure onto the threaded
neck, the closure and the threaded neck creating a hermetic seal
when subjected to a heating and cooling process such that a
plastisol material lining the interior of the closure resiliently
engages the threads and a vacuum provides a physical force to hold
the closure onto the container top end.
[0052] According to various other exemplary embodiments, the
interior and/or exterior of the container are coated with a
preservative coating after the container is formed or substantially
formed. According to yet other exemplary embodiments, the container
is pre-coated and then coated with one or more post-forming coats.
Coating may be applied via spraying or any other suitable method.
Different coatings may be provided for different food applications.
The coating material may be a vinyl, polyester, epoxy, and/or other
suitable preservative spray. The coating, for example, may be a
spray epoxy such as PPG Z12215L, sold by PPG Industries, Inc.
According to other embodiments, the coating may be a coating such
as sold by Valspar Coatings (e.g., coating number 6256-069,
etc.).
[0053] According to various exemplary embodiments, a user of
various embodiments of a metal container described throughout this
application may open the container by applying an opening torque to
the closure, container body, and/or other structures of the
container to rotatably remove the closure. Using the thread indents
or molds created in the plastisol, the thread surfaces should be
able to slide along the interfacing plastisol such that the closure
is directed upward by the spiral or helix nature of the threads.
With enough twisting, the closure will be directed upward until the
hermetic seal between the closure and the container will be broken
and the vacuum inside the container will be released. If the
closure has a safety-button type incorporated, a safety-button
formerly depressed when the vacuum was maintained will pop-up to
indicate to the user that the seal has been broken.
[0054] According to any preferred embodiment, although the
container includes a closure at the top end, and a bottom end part
at the bottom end, the container embodies a 2-piece can in that one
continuous blank of material forms the container body, neck, and
threads and a vertical seam or weld line does not run down the side
wall of the container. According to various alternative
embodiments, the container may be a three-piece can wherein a flat
blank or sheet of material is shaped or bent until a first side and
a second side of the shaped sheet may be welded together.
[0055] As the container and the food inside the container are
heated, the inside of the container is sterilized so that the food
does not spoil. When the container begins cooling, the closure is
fixed to the threads by the plastisol cooling and a negative
pressure relationship or a vacuum that develops on the container
interior. As the plastisol cools, it hardens and forms around the
threads of the container and resembles a resilient foam. As the
container interior cools, a vacuum creates a physical force that
provides a seal between the closure and the rest of the container
interior.
[0056] It should be understood that the phrase "food" used to
describe various embodiments of this disclosure may refer to dry
food, moist food, liquid, or any other drinkable or edible
material, regardless of nutritional value.
[0057] According to various other embodiments, a container kit may
be provided utilizing various containers and closures described
herein.
[0058] While the exemplary embodiments illustrated in the figures
and described herein are presently preferred, it should be
understood that these embodiments are offered by way of example
only. Accordingly, the present application is not limited to a
particular embodiment, but extends to various modifications that
nevertheless fall within the scope of the appended claims. The
order or sequence of any processes or method steps may be varied or
re-sequenced according to alternative embodiments.
[0059] It is important to note that the construction and
arrangement of the container as shown in the various exemplary
embodiments is illustrative only. Although only a few embodiments
have been described in detail in this disclosure, those skilled in
the art who review this disclosure will readily appreciate that
many modifications are possible (e.g., variations in sizes,
dimensions, structures, shapes and proportions of the various
elements, values of parameters, mounting arrangements, use of
materials, colors, orientations, etc.) without materially departing
from the novel teachings and advantages of the subject matter
recited in the claims. For example, elements shown as integrally
formed may be constructed of multiple parts or elements, the
position of elements may be reversed or otherwise varied, and the
nature or number of discrete elements or positions may be altered
or varied. Accordingly, all such modifications are intended to be
included within the scope of the present application. The order or
sequence of any process or method steps may be varied or
re-sequenced according to alternative embodiments. In the claims,
any means-plus-function clause is intended to cover the structures
described herein as performing the recited function and not only
structural equivalents but also equivalent structures. Other
substitutions, modifications, changes and omissions may be made in
the design, operating conditions and arrangement of the exemplary
embodiments without departing from the scope of the present
application.
[0060] It should be noted that although the figures herein may show
a specific order of method steps, it is understood that the order
of these steps may differ from what is depicted. Also, two or more
steps may be performed concurrently or with partial concurrence. It
is understood that all such variations are within the scope of the
application.
* * * * *