U.S. patent application number 13/181659 was filed with the patent office on 2012-01-19 for controlled base flash forming a standing ring.
Invention is credited to Christopher Howe, George David Lisch, Kirk Edward Maki, Terry D. Patcheak.
Application Number | 20120012592 13/181659 |
Document ID | / |
Family ID | 45466126 |
Filed Date | 2012-01-19 |
United States Patent
Application |
20120012592 |
Kind Code |
A1 |
Lisch; George David ; et
al. |
January 19, 2012 |
CONTROLLED BASE FLASH FORMING A STANDING RING
Abstract
A blow-molded plastic container comprising a base portion having
a flexible standing ring radially extending therefrom. The flexible
standing ring is disposed about a lowest most portion of the
container and operable to support the container on a surface. The
flexible standing ring defines an annular groove thereabout that
collapses in response to internal vacuum forces and/or external
loading forces. The container further comprises a body portion that
extends from an upper portion to the base, such that the upper
portion, the body portion and the base cooperate to define a
receptacle chamber within the container into which product can be
filled.
Inventors: |
Lisch; George David;
(Jackson, MI) ; Patcheak; Terry D.; (Ypsilanti,
MI) ; Maki; Kirk Edward; (Tecumseh, MI) ;
Howe; Christopher; (Belleville, MI) |
Family ID: |
45466126 |
Appl. No.: |
13/181659 |
Filed: |
July 13, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61364827 |
Jul 16, 2010 |
|
|
|
Current U.S.
Class: |
220/660 ;
425/525 |
Current CPC
Class: |
B65D 1/0276 20130101;
B65D 2501/0036 20130101; B29C 49/4802 20130101; B29C 49/12
20130101; B29C 49/54 20130101; B29K 2023/065 20130101; B29C 49/04
20130101; B65D 79/005 20130101; B29K 2023/12 20130101; B29C
2049/622 20130101; B29L 2031/7158 20130101; B29C 2049/4807
20130101; B29C 49/06 20130101; B29K 2067/003 20130101 |
Class at
Publication: |
220/660 ;
425/525 |
International
Class: |
B65D 8/04 20060101
B65D008/04; B29C 49/54 20060101 B29C049/54 |
Claims
1. A blow-molded plastic container comprising: an upper portion; a
base portion having a flexible standing ring extending from a lower
portion thereof, said flexible standing ring being articulated
relative to said lower portion in response to at least one of
internal vacuum forces or external loading forces; and a body
portion extending from said upper portion to said base, said upper
portion, said body portion and said base cooperating to define a
receptacle chamber within said container into which product can be
filled.
2. The blow-molded plastic container according to claim 1 wherein
said flexible standing ring is integrally formed with said base
portion.
3. The blow-molded plastic container according to claim 1 wherein
said flexible standing ring comprises: a leg portion extending
downwardly from said lower portion of said base portion; a foot
portion extending from a terminal end of said leg portion, at least
a portion of said foot portion contactable with a surface
supporting the plastic container.
4. The blow-molded plastic container according to claim 3 wherein
said foot portion is generally orthogonal to said leg portion.
5. The blow-molded plastic container according to claim 3 wherein
said foot portion extending radially outwardly beyond said body
portion.
6. The blow-molded plastic container according to claim 3 wherein
said foot portion and said base portion together define an annular
groove extending continuously about said base portion.
7. The blow-molded plastic container according to claim 6 wherein
said annular groove is collapsible in response to at least one of
the internal vacuum forces and external loading forces.
8. The blow-molded plastic container according to claim 1 wherein
said flexible standing ring being articulated relative to said
lower portion in response to at least one of internal vacuum forces
or external loading forces is part of a first load response and
subsequent contact of said flexible standing ring with said lower
portion initiates a second load response, said second load response
being different from said first load response.
9. The blow-molded plastic container according to claim 1 wherein
said flexible standing ring is articulated between a first stage
load response and a second stage load response, said second stage
load response being different in terms of load capacity than said
first stage load response.
10. The blow-molded plastic container according to claim 1 wherein
said flexible standing ring is articulatable between a first load
response where said flexible standing ring is initially movable and
defines a first load resistance and a second load response where
said flexible standing ring contacts said base portion and defines
a second load resistance, said second load resistance being greater
than said first load resistance.
11. The blow-molded plastic container according to claim 10 wherein
said flexible standing ring further defines a third load response
where said flexible standing ring further contacts said base
portion and defines a third load resistance, said third load
resistance being greater than that second load resistance.
12. A mold for forming a plastic container having an integrally
formed standing ring, said mold comprising: a first mold portion;
and a second mold portion movable relative to said first mold
portion, said first mold portion and said second mold portion
together defining at least in part a mold cavity for molding a
plastic container, wherein said first mold portion and said second
mold portion together define a standing ring slot for forming a
standing ring on a base portion of the plastic container, said
standing ring slot being defined at an interface between said first
mold portion and said second mold portion.
13. The mold according to claim 12, further comprising: a vent slot
extending through said second mold portion, said vent slot being in
fluid communication with said mold cavity when said second mold
portion is in a first position relative to said first mold portion,
said vent slot being fluidly separated from said mold cavity when
said second mold portion is in a second portion relative to said
first mold portion.
14. The mold according to claim 12, further comprising: a positive
stop extending from at least one of said first mold portion and
said second mold portion, said positive stop forming a defining a
predetermined edge along a distal end of the standing ring.
15. The mold according to claim 12 wherein said standing ring slot
is adjustable.
16. The mold according to claim 12 wherein said standing ring slot
is adjustable in response to the addition of insert rings between
at least a portion of said first mold portion and said second mold
portion.
17. The mold according to claim 12 wherein said standing ring slot
is oriented at an angle greater than 0.degree. and less than
90.degree. relative to a longitudinal axis of said mold cavity.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/364,827, filed on Jul. 16, 2010. The entire
disclosure of the above application is incorporated herein by
reference.
FIELD
[0002] This disclosure generally relates to containers for
retaining a commodity, such as a solid or liquid commodity. More
specifically, this disclosure relates to a blown polyethylene
terephthalate (PET) container having a flexible standing ring
circumferentially surrounding its base for improved container
performance and reduced container weight.
BACKGROUND
[0003] This section provides background information related to the
present disclosure which is not necessarily prior art.
[0004] As a result of environmental and other concerns, plastic
containers, more specifically polyester and even more specifically
polyethylene terephthalate (PET) containers are now being used more
than ever to package numerous commodities previously supplied in
glass containers. Manufacturers and fillers, as well as consumers,
have recognized that PET containers are lightweight, inexpensive,
recyclable and manufacturable in large quantities.
[0005] Blow-molded plastic containers have become commonplace in
packaging numerous commodities. PET is a crystallizable polymer,
meaning that it is available in an amorphous form or a
semi-crystalline form. The ability of a PET container to maintain
its material integrity relates to the percentage of the PET
container in crystalline form, also known as the "crystallinity" of
the PET container. The following equation defines the percentage of
crystallinity as a volume fraction:
% Crystallinity = ( .rho. - .rho. a .rho. c - .rho. a ) .times. 100
##EQU00001##
where .rho. is the density of the PET material; .rho..sub.a is the
density of pure amorphous PET material (1.333 g/cc); and
.rho..sub.c is the density of pure crystalline material (1.455
g/cc).
[0006] Container manufacturers use mechanical processing and
thermal processing to increase the PET polymer crystallinity of a
container. Mechanical processing involves orienting the amorphous
material to achieve strain hardening. This processing commonly
involves stretching an injection molded PET preform along a
longitudinal axis and expanding the PET preform along a transverse
or radial axis to form a PET container. The combination promotes
what manufacturers define as biaxial orientation of the molecular
structure in the container. Manufacturers of PET containers
currently use mechanical processing to produce PET containers
having approximately 20% crystallinity in the container's
sidewall.
[0007] Thermal processing involves heating the material (either
amorphous or semi-crystalline) to promote crystal growth. On
amorphous material, thermal processing of PET material results in a
spherulitic morphology that interferes with the transmission of
light. In other words, the resulting crystalline material is
opaque, and thus, generally undesirable. Used after mechanical
processing, however, thermal processing results in higher
crystallinity and excellent clarity for those portions of the
container having biaxial molecular orientation. The thermal
processing of an oriented PET container, which is known as heat
setting, typically includes blow molding a PET preform against a
mold heated to a temperature of approximately 250.degree.
F.-350.degree. F. (approximately 121.degree. C.-177.degree. C.),
and holding the blown container against the heated mold for
approximately two (2) to five (5) seconds. Manufacturers of PET
juice bottles, which must be hot-filled at approximately
185.degree. F. (85.degree. C.), currently use heat setting to
produce PET bottles having an overall crystallinity in the range of
approximately 25%-35%.
SUMMARY
[0008] This section provides a general summary of the disclosure,
and is not a comprehensive disclosure of its full scope or all of
its features.
[0009] According to the principles of the present disclosure, a
blow-molded plastic container is provided having a base portion
having a flexible standing ring radially extending therefrom. The
flexible standing ring is disposed about a lowest most portion of
the container and operable to support the container on a surface.
The flexible standing ring defines an annular groove thereabout
that collapses in response to internal vacuum forces and/or
external loading forces. The container further comprises a body
portion that extends from an upper portion to the base, such that
the upper portion, the body portion and the base cooperate to
define a receptacle chamber within the container into which product
can be filled.
[0010] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples
in this summary are intended for purposes of illustration only and
are not intended to limit the scope of the present disclosure.
DRAWINGS
[0011] The drawings described herein are for illustrative purposes
only of selected embodiments and not all possible implementations,
and are not intended to limit the scope of the present
disclosure.
[0012] FIG. 1 is a side view of a plastic container constructed in
accordance with the teachings of the present disclosure;
[0013] FIG. 2 is an enlarged cross-sectional view of the base
portion of the container of FIG. 1;
[0014] FIG. 3 is a schematic view of the container with portions in
solid lines representing deformation of the container during a cool
down response from 83.degree. C. to 23.degree. C. and portions in
dashed lines representing the initial configuration;
[0015] FIG. 4A is a schematic view of the container illustrating
localized stress concentrations during the cool down response;
[0016] FIG. 4B is a schematic view of the container illustrating
localized displacement concentrations during the cool down
response;
[0017] FIG. 5 is a front view of a plastic container constructed in
accordance with the teachings of the present disclosure;
[0018] FIG. 6 is a side view of the plastic container of FIG.
5;
[0019] FIG. 7 is a graph illustrating the vacuum response (vacuum
(inHg) vs. volume displacement (cc)) of various containers
according to the principles of the present teachings having
sidewall thicknesses of t010, t015, and t030;
[0020] FIGS. 8A-8D are schematic views of the container with
portions in dashed lines representing deformation of the container
during a vacuum response wherein the base thickness is t014 in each
example and sidewall thickness varies from t015, t020, t025, to
t030, respectively;
[0021] FIGS. 9A-9I are schematic views of the container with
portions in dashed lines representing deformation of the container
during a filled cap top load response wherein the sidewall
thickness is t030 in each example and base thickness varies from
t014, t020, to t025, respectively, arranged in sets of threes for
each of the first stage, second stage, and third stage of
deformation, respectively;
[0022] FIG. 10 is a graph illustrating the cap top load response
for containers each having a base thickness of t014 and varying
sidewall thicknesses of t010, t015, and t030;
[0023] FIGS. 11A and 11B are schematic views of a mold for forming
the container of the present teachings shown in a retracted
position (FIG. 11A) and an extended position (FIG. 11B);
[0024] FIG. 11C is a schematic view, similar to FIG. 11A,
illustrating the positive stop of the mold;
[0025] FIG. 11D is a schematic view of a container formed in the
mold of FIGS. 11A-11C;
[0026] FIGS. 12A and 12B are schematic views of a mold for forming
the container of the present teachings shown in a retracted
position (FIG. 12A) and an extended position (FIG. 12B);
[0027] FIG. 12C is a schematic view of a container formed in the
mold of FIGS. 12A-12B having a positive stop;
[0028] FIG. 12D is a schematic view of a container formed in the
mold of FIGS. 12A-12B not having a positive stop;
[0029] FIGS. 13A and 13B are schematic views of a mold for forming
the container of the present teachings shown in a retracted
position (FIG. 13A) and an extended position (FIG. 13B) having a
tapered standing ring slot;
[0030] FIG. 13C is a schematic view of a container formed in the
mold of FIGS. 13A-13B;
[0031] FIGS. 14A and 14B are schematic views of a mold for forming
the container of the present teachings shown in a retracted
position (FIG. 14A) and an extended position (FIG. 14B) having a
triangular standing ring slot;
[0032] FIG. 14C is a schematic view of a container formed in the
mold of FIGS. 14A-14B;
[0033] FIGS. 15A and 15B are schematic views of a mold for forming
the container of the present teachings shown in a retracted
position (FIG. 15A) and an extended position (FIG. 15B) having an
adjustably-sized standing ring slot; and
[0034] FIG. 15C is a schematic view of a container formed in the
mold of FIGS. 15A-15B.
[0035] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION
[0036] Example embodiments will now be described more fully with
reference to the accompanying drawings. Example embodiments are
provided so that this disclosure will be thorough, and will fully
convey the scope to those who are skilled in the art. Numerous
specific details are set forth such as examples of specific
components, devices, and methods, to provide a thorough
understanding of embodiments of the present disclosure. It will be
apparent to those skilled in the art that specific details need not
be employed, that example embodiments may be embodied in many
different forms and that neither should be construed to limit the
scope of the disclosure.
[0037] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be
limiting. As used herein, the singular forms "a", "an" and "the"
may be intended to include the plural forms as well, unless the
context clearly indicates otherwise. The terms "comprises,"
"comprising," "including," and "having," are inclusive and
therefore specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. The
method steps, processes, and operations described herein are not to
be construed as necessarily requiring their performance in the
particular order discussed or illustrated, unless specifically
identified as an order of performance. It is also to be understood
that additional or alternative steps may be employed.
[0038] When an element or layer is referred to as being "on",
"engaged to", "connected to" or "coupled to" another element or
layer, it may be directly on, engaged, connected or coupled to the
other element or layer, or intervening elements or layers may be
present. In contrast, when an element is referred to as being
"directly on," "directly engaged to", "directly connected to" or
"directly coupled to" another element or layer, there may be no
intervening elements or layers present. Other words used to
describe the relationship between elements should be interpreted in
a like fashion (e.g., "between" versus "directly between,"
"adjacent" versus "directly adjacent," etc.). As used herein, the
term "and/or" includes any and all combinations of one or more of
the associated listed items.
[0039] Although the terms first, second, third, etc. may be used
herein to describe various elements, components, regions, layers
and/or sections, these elements, components, regions, layers and/or
sections should not be limited by these terms. These terms may be
only used to distinguish one element, component, region, layer or
section from another region, layer or section. Terms such as
"first," "second," and other numerical terms when used herein do
not imply a sequence or order unless clearly indicated by the
context. Thus, a first element, component, region, layer or section
discussed below could be termed a second element, component,
region, layer or section without departing from the teachings of
the example embodiments.
[0040] Spatially relative terms, such as "inner," "outer,"
"beneath", "below", "lower", "above", "upper" and the like, may be
used herein for ease of description to describe one element or
feature's relationship to another element(s) or feature(s) as
illustrated in the figures. Spatially relative terms may be
intended to encompass different orientations of the device in use
or operation in addition to the orientation depicted in the
figures. For example, if the device in the figures is turned over,
elements described as "below" or "beneath" other elements or
features would then be oriented "above" the other elements or
features. Thus, the example term "below" can encompass both an
orientation of above and below. The device may be otherwise
oriented (rotated 90 degrees or at other orientations) and the
spatially relative descriptors used herein interpreted
accordingly.
[0041] The present teachings provide for a container having a
flexible standing ring that effectively absorbs the internal vacuum
while maintaining its basic shape. The flexible standing ring can
be described as having an integrated base fold that is flexible in
the vertical direction (in a direction coaxial with a central axis
A-A of the container (FIG. 2)) and rigid in a radial direction (in
a direction orthogonal to the central axis A-A). The container of
the present teachings, unlike conventional containers, provided
increased vacuum performance thereby permitting thinner wall
thicknesses and reduced material consumption to be realized.
[0042] As will be discussed in greater detail herein, the shape of
the container of the present teachings can be formed according to
any one of a number of variations. By way of non-limiting example,
the container of the present disclosure can be configured to hold
any one of a plurality of commodities, such as beverages, food, or
other hot-fill type materials.
[0043] It should be appreciated that the size and the exact shape
of the flexible standing ring are dependent on the size of the
container and the required vacuum absorption. Therefore, it should
be recognized that variations can exist in the presently described
designs. According to some embodiments, it should also be
recognized that the container can include additional vacuum
absorbing features or regions, such as panels, ribs, slots,
depressions, and the like.
[0044] As illustrated throughout the several figures, the present
teachings provide a one-piece plastic, e.g. polyethylene
terephthalate (PET), container generally indicated at 10. The
container 10 comprises an integrated base fold flexible standing
ring design according to the principles of the present teachings.
Those of ordinary skill in the art would appreciate that the
following teachings of the present disclosure are applicable to
other containers, such as rectangular, triangular, hexagonal,
octagonal or square shaped containers, which may have different
dimensions and volume capacities. It is also contemplated that
other modifications can be made depending on the specific
application and environmental requirements.
[0045] As shown in FIGS. 1-6, the one-piece plastic container 10
according to the present teachings defines a body 12, and includes
an upper portion 14 having a cylindrical sidewall 18 forming a
finish 20. Integrally formed with the finish 20 and extending
downward therefrom is a shoulder portion 22. The shoulder portion
22 merges into and provides a transition between the finish 20 and
a sidewall portion 24. The sidewall portion 24 extends downward
from the shoulder portion 22 to a base portion 28 having a base 30.
An upper transition portion 32, in some embodiments, may be defined
at a transition between the shoulder portion 22 and the sidewall
portion 24. A lower transition portion 34, in some embodiments, may
be defined at a transition between the base portion 28 and the
sidewall portion 24.
[0046] The exemplary container 10 may also have a neck 23. The neck
23 may have an extremely short height, that is, becoming a short
extension from the finish 20, or an elongated height, extending
between the finish 20 and the shoulder portion 22. The upper
portion 14 can define an opening. Although the container is shown
as a drinking container (FIGS. 1-4B) and a food container (FIGS.
5-6), it should be appreciated that containers having different
shapes, such as sidewalls and openings, can be made according to
the principles of the present teachings.
[0047] As illustrated in FIGS. 1, 5 and 6, the finish 20 of the
plastic container 10 may include a threaded region 46 having
threads 48, a lower sealing ridge 49, and a support ring 51. The
threaded region 46 provides a means for attachment of a similarly
threaded closure or cap (not illustrated). Alternatives may include
other suitable devices that engage the finish 20 of the plastic
container 10, such as a press-fit or snap-fit cap for example.
Accordingly, the closure or cap (not illustrated) engages the
finish 20 to preferably provide a hermetical seal of the plastic
container 10. The closure or cap (not illustrated) is preferably of
a plastic or metal material conventional to the closure industry
and suitable for subsequent thermal processing.
[0048] Referring now to FIGS. 1-4, sidewall portion 24 of the
present teachings will now be described in greater detail. As
discussed herein, sidewall portion 24 can comprise various vacuum
features that effectively absorb at least a portion of the internal
vacuum while maintaining the container's basic shape. In some
embodiments, sidewall portion 24 can comprises one or more radially
disposed vacuum ribs 60. To this end, vacuum ribs 60 can each
comprise an inwardly directed rib member defining a reduced
container diameter section 62 and a plurality of lands 64 disposed
therebetween. Transition features or radiuses 66 can be disposed
between vacuum ribs 60 and adjacent lands 64. Vacuum ribs 60 can be
equidistantly spaced along sidewall portion 24. In response to
internal vacuum, vacuum ribs 60 can articulate about reduced
container diameter section 62 to achieve a vacuum absorbed posture.
However, it should also be understood that vacuum ribs 60 can
further provide a reinforcement feature to container 10, thereby
providing improved structural integrity and stability.
[0049] Still referring to FIGS. 1-4, container 10 can further
comprise an enlarged radially disposed vacuum rib 60' disposed
along sidewall portion 24, shoulder portion 22, and/or upper
transition portion 32. In this regard, enlarged vacuum rib 60' can
comprise an inwardly directed rib member defining a reduced
container diameter section 62'. Reduced diameter section 62' of
vacuum rib 60' can define a container diameter that is smaller than
the container diameter of reduced diameter section 62 of vacuum rib
60. Moreover, vacuum rib 60' can have a radiused curvature that is
greater than vacuum rib 60 for increased vacuum performance.
[0050] With particular reference to FIGS. 5 and 6, in some
embodiments, container 10 can comprise vertically oriented vacuum
panels 70 having transition surface 72 disposed therebetween.
Vacuum panels 70 can be generally equidistant spaced about sidewall
portion 24. While such spacing is useful, other factors such as
labeling requirements or the incorporation of grip features or
graphics may require spacing other than equidistant. The container
10 illustrated in FIGS. 5 and 6 can comprise eight (8) vacuum
panels 70. Lands, inclined columns, or transition surfaces 72 are
defined between adjacent vacuum panels 70, which provide structural
support and rigidity to sidewall portion 24 of container 10.
[0051] With particular reference to FIGS. 1-6, 8, and 9, container
10 further comprises a flexible standing ring 100 disposed radially
about base 30 and a center pushup feature 50 disposed centrally
along an underside of base 30. As described herein, flexible
standing ring 100 can be an integrated base fold feature that
provides a plurality of design advantages over convention prior art
base designs. In some embodiments, flexible standing ring 100
provides 1) increased volume displacement compared to other vacuum
absorbing features, 2) positive charge up while under filled and
capped vertical loading conditions, 3) improved distributed forces
along the base of the container during stacking, 4) rigid central
base pushup, 5) improved individual container stacking capability
(closure fits within base), and 6) securing shrink wrap label.
[0052] With particular reference to FIG. 2, flexible standing ring
100 can comprise a leg portion 102 extending downwardly from base
portion 28 that terminates at an outwardly directed foot portion
104. Leg portion 102 can downwardly extend from base portion 28 at
a position generally adjacent and inset from a land 106. The amount
of the inset of leg portion 102 can be dependent on the vacuum
absorption that is desired. Foot portion 104 can extend outwardly
from a terminal end of leg portion 102. In some embodiments, foot
portion 104 can be positioned orthogonal to leg portion 102.
However, in some embodiments, leg portion 102 and foot portion 104
can have any one of a number of relative orientations conducive
with container performance.
[0053] In some embodiments, foot portion 104 extends radially
outwardly such that a distal portion or toe portion 108 is radially
aligned with an overall shape or dimension of sidewall portion 24
and/or base portion 28 (as shown in FIGS. 1 and 2). However, in
some embodiments, toe portion 108 of foot portion 104 can extend
less than an overall shape or dimension of sidewall portion 24
and/or base portion 28 (as shown in FIGS. 5 and 6) or greater than
(not shown). In this regard, an underside surface 110 of foot
portion 104 forms a standing ring that provides a contact surface
between container 10 and any support structure thereunder. The
described structure of flexible standing ring 100 thus provides an
annular groove or slot 112 formed about the base of container 10.
The depth, height, and cross-sectional shape of annular groove 112
can be varied depending on structural, vacuum, and aesthetic
characteristics; however, it should be appreciated that flexible
standing ring 100 provides a means to accommodate internal vacuum
forces in container 10 while minimizing or at least decreasing
overall container weight.
[0054] Flexible standing ring 100 can be characterized, in some
embodiments, as an assembly having a downwardly and outwardly ring
member. This arrangement results in an annular groove disposed
above the ring member. The ring member further includes a lower
surface that contacts the support structure, such as counter,
packaging material, display shelf, and the like, and thus is
located along a base portion of the container. It should be
appreciated that variations of the present design of flexible
standing ring 100 exist.
[0055] With particular reference to FIGS. 3, 4A, and 4B, cool down
response of container 10, and in particular flexible standing ring
100, will now be described in detail. As seen in FIG. 3, cool down
response of container 10 can comprise a collapse or deformation of
container 10 and flexible standing ring 100 in response to internal
vacuum forces. To this extent, as illustrated by the solid lines in
FIG. 3, flexible standing ring 100 collapses in such a way that
foot portion 104 is permitted to articulate upward and, in some
embodiments, against an underside surface 114 (FIG. 2) of base
portion 28, thereby closing annular slot 112. The amount of
deflection of foot portion 104 may vary depending on size of
container, wall thickness of material, amount of internal vacuum
pressure, and the like. However, contact of foot portion 104 with
underside surface 114 of base portion 28 can lead to a second stage
of load response of container 10.
[0056] With reference to FIGS. 2 and 3, it should also be
appreciated that the cool down response of container 10 can further
include collapse or at least narrowing of the thickness of foot
portion 104 and/or leg portion 102. In this way, opposing walls of
foot portion 104 and/or leg portion 102 are forced together in
response to vacuum forces. This narrowing response further aids in
permitting articulations and collapse of flexible standing ring 100
as illustrated in FIG. 3.
[0057] With reference to FIGS. 4A and 4B, it can be seen that in
response to internal vacuum forces, container 10 exhibits localized
stresses in predetermined locations consistent with predictable and
manageable collapse of container 10. Moreover, actual displacement
of container 10 can be localized to a lower section of sidewall
portion 24 and base portion 28 (including flexible standing ring
100).
[0058] With particular reference to FIGS. 7-10, it should be
appreciated that vacuum response of container 10 and flexible
standing ring 100 can be dependent on wall thickness of sidewall
portion 24, base portion 28, and/or flexible standing ring 100. In
this regard, vacuum response of container 10 of FIGS. 5 and 6 is
illustrated in FIG. 7, whereby a thickness of center pushup 50 is
maintained throughout the several wall thickness variations.
Specifically, FIG. 7 illustrates that container 10, having a wall
thickness of t030 provides increased resistance to vacuum
deformation (in other words, greater vacuum was necessary to
achieve a particular volume displacement) compared to thinner wall
configurations. Similar vacuum response deformation is illustrated
in FIGS. 8 and 9, wherein the thickness of center pushup 50 is
maintained (t014) while a thickness of sidewall portion 24 varies
from t015, t020, t025, to t030.
[0059] Turning now to FIGS. 9A-9I, top loading response can be seen
for three variations of container 10 of FIGS. 5 and 6 each having
identical thickness of sidewall portion 24 and varying thickness of
base portion 28, specifically t014, t020, and t025, and filled with
a commodity and capped. The downward force is placed on top of
container 10 and generally exerted along axis A-A. Each set of
three figures (i.e. 9A-9C, 9D-9F, and 9G-9I) represents a different
stage of container deformation. Specifically, the first stage
(FIGS. 9A-9C) illustrates the container deformation response where
an underside slope of base 30 changes in response to a first
contact between a corner 120 of base portion 28 and foot portion
104 and deformation of flexible standing ring 100. A second stage
(FIGS. 9D-9F) illustrates the container deformation response where
an underside slope of base 30 changes in response to contact
between corner 120 of base portion 28 and the support surface upon
which container 10 rests--that is, corner 120 passing beyond foot
portion 104, and contacting the support surface and the deformed
flexible standing ring 100. Finally, a third stage (FIGS. 9G-9I)
illustrates the container deformation response where container 10
further contacts the support surface. A similar graph of filled and
capped top load response is illustrated in FIG. 10 for the
container of FIGS. 5 and 6 wherein center pushup 50 has a constant
wall thickness (t014) and varying thicknesses of sidewall portion
24 are presented (t010, t015, t030). As can be seen in FIG. 10, the
first stage is denoted at region 201, the second stage is denoted
at region 202, and the third stage is denoted at region 203.
[0060] According to the foregoing, it should be appreciated that
flexible standing ring 100 provides, in part, volume displacement
for purposes of vacuum reduction. Specifically, as seen in FIG. 2,
the amount of volume displacement can be calculated by multiplying
the radius R1 of container 10 by the height H1 of annular groove
112 and Pi. This amount of volume displacement is significant in
terms of alternative volume displacement strategies commonly used
in container design without the need to account for equivalent
fluid displacement.
[0061] The plastic container 10 has been designed to retain a
commodity. The commodity may be in any form such as a solid or
semi-solid product. In one example, a commodity may be introduced
into the container during a thermal process, typically a hot-fill
process. For hot-fill bottling applications, bottlers generally
fill the container 10 with a product at an elevated temperature
between approximately 155.degree. F. to 205.degree. F.
(approximately 68.degree. C. to 96.degree. C.) and seal the
container 10 with a closure (not illustrated) before cooling. In
addition, the plastic container 10 may be suitable for other
high-temperature pasteurization or retort filling processes or
other thermal processes as well. In another example, the commodity
may be introduced into the container under ambient
temperatures.
[0062] The plastic container 10 of the present disclosure is a blow
molded, biaxially oriented container with a unitary construction
from a single or multi-layer material. A well-known
stretch-molding, heat-setting process for making the one-piece
plastic container 10 can be used that generally involves the
manufacture of a preform (not shown) of a polyester material, such
as polyethylene terephthalate (PET), having a shape well known to
those skilled in the art similar to a test-tube with a generally
cylindrical cross section. An exemplary method of manufacturing the
plastic container 10 will be described in greater detail later.
[0063] An exemplary method of forming the container 10 will be
described. A preform version of container 10 includes a support
ring 51, which may be used to carry or orient the preform through
and at various stages of manufacture. For example, the preform may
be carried by the support ring 51, the support ring 51 may be used
to aid in positioning the preform in a mold cavity, or the support
ring 51 may be used to carry an intermediate container once molded.
At the outset, the preform may be placed into the mold cavity such
that the support ring 51 is captured at an upper end of the mold
cavity. In general, the mold cavity has an interior surface
corresponding to a desired outer profile of the blown container.
More specifically, the mold cavity according to the present
teachings defines a body forming region, an optional moil forming
region and an optional opening forming region. Once the resultant
structure, hereinafter referred to as an intermediate container,
has been formed, any moil created by the moil forming region may be
severed and discarded. It should be appreciated that the use of a
moil forming region and/or opening forming region are not
necessarily in all forming methods.
[0064] In one example, a machine (not illustrated) places the
preform heated to a temperature between approximately 190.degree.
F. to 250.degree. F. (approximately 88.degree. C. to 121.degree.
C.) into the mold cavity. The mold cavity may be heated to a
temperature between approximately 250.degree. F. to 350.degree. F.
(approximately 121.degree. C. to 177.degree. C.). A stretch rod
apparatus (not illustrated) stretches or extends the heated preform
within the mold cavity to a length approximately that of the
intermediate container thereby molecularly orienting the polyester
material in an axial direction generally corresponding with the
central longitudinal axis A-A of the container 10. While the
stretch rod extends the preform, air having a pressure between 300
PSI to 600 PSI (2.07 MPa to 4.14 MPa) assists in extending the
preform in the axial direction and in expanding the preform in a
circumferential or hoop direction thereby substantially conforming
the polyester material to the shape of the mold cavity and further
molecularly orienting the polyester material in a direction
generally perpendicular to the axial direction, thus establishing
the biaxial molecular orientation of the polyester material in most
of the intermediate container. The pressurized air holds the mostly
biaxial molecularly oriented polyester material against the mold
cavity for a period of approximately two (2) to five (5) seconds
before removal of the intermediate container from the mold cavity.
This process is known as heat setting and results in a
heat-resistant container suitable for filling with a product at
high temperatures.
[0065] Alternatively, other manufacturing methods, such as for
example, extrusion blow molding, one step injection stretch blow
molding and injection blow molding, using other conventional
materials including, for example, high density polyethylene,
polypropylene, polyethylene naphthalate (PEN), a PET/PEN blend or
copolymer, and various multilayer structures may be suitable for
the manufacture of plastic container 10. Those having ordinary
skill in the art will readily know and understand plastic container
manufacturing method alternatives.
[0066] It should be appreciated that additional manufacturing
processes can be used. For example, when blow molding bottles with
inset handles and when forming either a Champaign or PowerFlex
base, the molding process has often included the movement of the
base mechanism of the mold machine, wherein the base is inserted
into the bottle after the container has been formed. This action of
retracting the base mechanism of the mold during manufacturing has
generally been referred to as "Over-Stroke". It has been found that
the delayed timing of this action has resulted in the formation of
a standing ring in the form of molding flash. In many applications,
this molding flash is undesirable. However, as set forth herein, it
should be appreciated that this molding flash can be used to form a
standing ring for improved heel (or foot) stability. In many
conventional applications, this flash has been uncontrolled
resulting in an unstable and uneven platform on the container.
However, according to the principles of the present teachings, this
flash can be more closely controlled to define an even or flat
surface.
[0067] With particular reference to FIGS. 11A-11C, a portion of a
mold 210 according to the principles of the present teachings is
illustrated. Mold 210, in some embodiments, is an over-stroke type
mold having a first mold portion 212 and a second mold portion 214
that are movable relative to each other. It should be noted that
first mold portion 212 can be movable or stationary and, likewise,
second mold portion 214 can be stationary or movable, respectively.
At least in part, first mold portion 212 and second mold portion
214 together define an internal mold cavity 216 having a contour
generally following a final or intermediate contour shape of
container 10. Second mold portion 214 can comprise a vent channel
218 extending therethrough and in fluid communication with mold
cavity 216. More particularly, in some embodiments, vent channel
218 is positioned adjacent a vented slot portion 220 of mold cavity
216 that is sized and shaped to form standing ring 100.
[0068] In a first position of first mold portion 212 (e.g.
retracted in FIG. 11A), fluid communication is established between
mold cavity 216 and vent channel 218 such that molten plastic is
free to flow down and/or be blown down into vented slot portion
220. In some embodiments, molten plastic can be molded in such a
way that it does not initially contact the metallic portions of
mold cavity 216. However, first mold portion 212 can then be
actuated via schematically illustrated drive device 222 and
positioned in a second position (e.g. extended upward into mold
cavity 216 in FIG. 11B). In this way, the act of raising the first
mold portion 212, that can define a zero tolerance bearing surface
224 (FIG. 11C) with a positive stop 226 (FIG. 11C), generally
defining a flat surface, serves to urge or otherwise mold the
material within vent channel 218 into a predetermined standing ring
shape. Accordingly, as illustrated in FIG. 11D, a container 10
having a standing ring 100.
[0069] In some embodiments, formation of the standing ring can be
accomplished using at least two different methods. The first method
is the aforementioned Over-Stroke mechanism that can be used to
form a thin, generally upstanding, standing ring. Wherein the
second method can include the method described herein to form a
broader flat surface. Using the Over-Stroke mechanism, it is
desirable to incorporate a base design having a positive stop.
[0070] With particular reference to FIGS. 12A-12D, alternative
methods and molds can be used for forming standing ring 100. In
some embodiments, as illustrated in FIGS. 12A-12B, generally first
mold portion 212 is movable relative to second mold portion 214
between a retracted position (FIG. 12A) and an extended position
(FIG. 12B). The first mold portion 212 and the second mold portion
214 can together define a positive stop or no positive stop such
that the resultant container 10 can include a generally flat or
edge shaped standing ring 100 (see FIG. 12C) or a standing ring 100
having a generally inconsistent defined edge (see FIG. 12D).
[0071] In some embodiments as illustrated in FIGS. 13A-13C,
standing ring 100 can be generally tapered. This tapered shape can
be defined by forming a tapered slot 230 between first mold portion
212 and second mold portion 214. More particularly, in some
embodiments, tapered slot 230 can comprise a first tapered portion
232 extending from mold cavity 216 defining an angle relative to a
longitudinal axis A-A of the mold cavity 216. In some embodiments,
tapered slot 230 comprises a second tapered portion 234 extending
from first tapered portion 232. More particularly, second tapered
portion 234 can define an angle generally perpendicular to
longitudinal axis A-A. However, alternative angles can be used. In
this way, second tapered portion 232 can define a positive stop
(e.g. ledge) 236 that can be used to form a truncated or otherwise
shaped standing ring 100 (see FIG. 13C).
[0072] It should be recognized that alternative shapes of standing
ring 100 can be formed, such as a generally triangular shaped
standing ring 100 as illustrated in FIG. 14C. The generally
triangular shaped standing ring 100 can be formed by shaping slot
230 such that it defines an angled surface 240 extending from
second mold portion 214 and generally right-angled surfaces 242,
244 formed in first mold portion 212. In this way, right-angled
surfaces 242, 244 can define a positive stop (also indicated at
244).
[0073] Finally, with reference to FIGS. 15A-15C, in some
embodiments, the shape of the resultant standing ring 100 can be
varied by using one or more insertable rings or other members 250
within first mold portion 212 (or adjacent first mold portion 212).
In this way, the overall width, depth, and/or shape of standing
ring 100 can be easily changed.
[0074] It should be appreciated from the foregoing that some of the
advantages of the standing ring would include standing stability
and improved strength. According to the principles of the present
teachings, in some embodiments, the methods described herein and
illustrated would allow the preform to be blown into a positive
stop before the mechanism is raised into its final position. The
raising of the mechanism would squeeze the still pliable material
to be formed into the standing ring.
[0075] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not
intended to be exhaustive or to limit the invention. Individual
elements or features of a particular embodiment are generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and can be used in a selected embodiment, even if
not specifically shown or described. The same may also be varied in
many ways. Such variations are not to be regarded as a departure
from the invention, and all such modifications are intended to be
included within the scope of the invention.
* * * * *