U.S. patent application number 11/182127 was filed with the patent office on 2005-12-22 for container with structural ribs.
Invention is credited to Finlay, Patrick J., Haridas, Balakrishna, Payne, Michael T., Swindeman, Michael J..
Application Number | 20050279728 11/182127 |
Document ID | / |
Family ID | 26910354 |
Filed Date | 2005-12-22 |
United States Patent
Application |
20050279728 |
Kind Code |
A1 |
Finlay, Patrick J. ; et
al. |
December 22, 2005 |
Container with structural ribs
Abstract
A container is formed of a shell having a top section, a bottom
section and a central section connecting the top section and the
bottom section. At least a majority region of the central section
is provided with a plurality of structural ribs about its
periphery. The ribs are discontinuous in a circumferential
direction extending around the central section and have specific
structures in their shape, their orientation with respect to each
other and their longitudinal alignment to enable the container to
withstand deformation due to internal or external pressures. Each
rib has longitudinal angle of orientation is less than 90.degree.
relative to the vertical axis of the container.
Inventors: |
Finlay, Patrick J.; (New
Fairfield, CT) ; Payne, Michael T.; (Danbury, CT)
; Swindeman, Michael J.; (Middletown, OH) ;
Haridas, Balakrishna; (Mason, OH) |
Correspondence
Address: |
RYNDAK & SURI
30 NORTH LASALLE STREET
SUITE 2630
CHICAGO
IL
60602
US
|
Family ID: |
26910354 |
Appl. No.: |
11/182127 |
Filed: |
July 15, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11182127 |
Jul 15, 2005 |
|
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|
09790676 |
Feb 23, 2001 |
|
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60215754 |
Jun 30, 2000 |
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Current U.S.
Class: |
215/382 |
Current CPC
Class: |
B65D 2501/0036 20130101;
B65D 1/44 20130101; B65D 2501/0027 20130101 |
Class at
Publication: |
215/382 |
International
Class: |
B65D 090/02 |
Claims
What is claimed is:
1. A container comprising: a shell having an upper section, a lower
section and a central section having a ribbed portion, the central
section connecting said upper section and said lower section,
wherein at least a majority of said central section is provided
with the ribbed portion, the ribbed portion being defined by a
plurality of structural ribs distributed about its periphery, said
ribs being discontinuous in a circumferential direction extending
around said ribbed portion and said ribs reinforcing said central
section against at least one of internal and external pressures,
wherein said ribs are elongated and of the same shape, wherein all
of said ribs have substantially the same longitudinal angle of
orientation relative to a vertical axis of said shell, said
longitudinal angle of orientation being less than 90.degree., with
the longitudinal angle of orientation being linear relative to the
vertical axis, wherein the ribs are aligned in a plurality of rows
that are disposed at a same longitudinal angle of orientation
relative to the vertical axis, the ribs in one row are not aligned
vertically with ribs in an adjacent row, and wherein each of said
ribs has a depth that smoothly increases from each longitudinal end
to a maximum depth in its longitudinal middle.
2. A container according to claim 1, wherein ribs in each of said
plurality of rows are aligned vertically with ribs in each
alternate row of said plurality of rows.
3. A container according to claim 2, wherein each of said rows
comprises 5 to 16 ribs.
4. A container according to claim 2, further comprising 13 to 25 of
said rows.
5. A container according to claim 1, wherein said ribs comprise
elongated indentations in said central section.
6. A container according to claim 5, wherein at least one of said
ribs projects towards a central axis of said container with varying
depth.
7. A container according to claim 6, wherein the central section
has a cross-sectional diameter that is lesser than the
cross-sectional diameter of the lower section.
8. A container according to claim 1, wherein said shell is formed
of PET.
9. A container according to claim 1, wherein said shell has a
thickness of less than 0.010 in.
10. A container according to claim 1, wherein said shell has a
capacity of about 0.5 liter.
11. A container according to claim 1, wherein said shell is
blow-molded.
12. A container according to claim 1, wherein the majority region
of said central section comprises the entirety of said central
section.
13. A container comprising: a shell having an upper section, a
lower section and a central section having a ribbed portion, said
central portion connecting said upper section and said lower
section, wherein at least a majority of said central section is
provided with the ribbed portion, the ribbed portion being defined
by a plurality of structural ribs distributed about its periphery,
said ribs being discontinuous in a direction extending around said
ribbed portion and said ribs reinforcing said central section
against at least one of internal and external pressures, wherein
said ribs are elongated and of the same shape, and have a depth
that smoothly increases from each longitudinal end to a maximum
depth in its longitudinal middle, and wherein all of said ribs have
substantially the same longitudinal angle of orientation relative
to a vertical axis of said shell, and wherein said ribs are aligned
in a plurality of rows that are disposed at a same longitudinal
angle of orientation relative to the vertical axis of said shell,
and wherein said longitudinal angle of orientation is less than
90.degree. relative to the vertical axis, and the ribs in one row
are not aligned vertically with ribs in an adjacent row, and
wherein said central section is of a smooth surface in all areas
other than areas outside said ribbed area.
14. A container according to claim 13, wherein said ribs are
oriented 30.degree. relative to the vertical axis.
15. A container according to claim 13, wherein said ribs are
oriented 45.degree. relative to the vertical axis.
16. A container according to claim 13, wherein said ribs are
oriented 60.degree. relative to the vertical axis.
17. A container according to claim 16, wherein ribs in each of said
rows are aligned vertically with ribs in each alternate row of said
ribs.
18. A container according to claim 13, wherein said ribs comprise
elongated indentations in said central section.
19. A container according to claim 13, wherein said shell is formed
of PET.
20. A container according to claim 13 wherein said shell has a
thickness of less than 0.010 in.
21. A container according to claim 13, wherein said shell has a
capacity of about 0.5 liter.
22. A container according to claim 13, wherein said shell is
blow-molded.
23. A container according to claim 13, wherein said ribbed portion
of said central section comprises the entirety of said central
section.
24. A container comprising: a shell having an upper section, a
lower section and a central section connecting said top section and
said bottom section; and means disposed within said central section
for reinforcing said shell against external pressure and internal
pressure.
25. A container according to claim 24, further comprising means for
reinforcing said shell against axial stress.
26. A container according to claim 13, wherein the diameter of the
cross-section of the central section is lesser than the diameter of
a cross-section of the lower section.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a divisional of U.S. patent application Ser. No.
09/790,676, filed on Feb. 23, 2001, published as U.S. Patent
Publication No. 2001/0027978. This application also claims the
benefit of Provisional Application No. 60/215,754, filed Jun. 30,
2000.
FIELD OF THE INVENTION
[0002] The present invention relates to containers with structural
ribs to resist deformation due to internal or external forces. More
particularly, the present invention relates to beverage containers,
such as bottles, having non-continuous ribs formed in their
peripheral surfaces to resist deformation due to internal or
external pressures.
BACKGROUND OF THE INVENTION
[0003] Various containers are used to package liquids, such as
pressurized (e.g., carbonated) and unpressurized beverages. A
commonly-used container is a polyethylene terephthalate (PET)
bottle, which has been manufactured in various shapes and sizes.
PET bottles are popular because they are inexpensive, lightweight,
impervious to many gases and liquids and can be readily shaped into
various designs and sizes. However, unlike containers formed of
more rigid materials such as glass, PET containers can readily
deform at low internal or external pressures, especially when the
containers are thin-walled.
[0004] Certain PET containers or bottles have been designed with
continuous ribs in order to provide some rigidity. However,
although these ribs may perform satisfactorily when subject to
moderate external pressures, they can readily deform when subjected
to internal pressures, such as from the carbonation in certain
beverages (50-100 psi). For example, certain containers for bottled
water are provided with continuous ribs at the label panel area.
Although the bottles are formed of relatively thin PET to lighten
their weight, the continuous ribs add structural support at the
area to be grasped by the consumer. That is, even though the
containers are thin-walled, the pressure exerted by a consumer's
grasping will not deform the containers because of the
reinforcement provided by the continuous ribs. However, in some
instances these water bottles are pressurized, such as by the
addition of liquid nitrogen (up to about 40 psi), in order to
survive distribution. It has been found, however, that this
internal pressure tends to deform the continuous ribs over time. In
some instances, the bottles would deform so as to "wash out" the
continuous ribs. Improvements of this design have been attempted,
such as by providing the continuous ribs with fillet radii. These
modifications have achieved moderate success, but have not
satisfactorily prevented deformation due to internal pressure.
[0005] Discontinuous ribs have also been proposed for plastic
bottles for certain applications. U.S. Pat. No. 6,036,037 describes
a plastic bottle that includes vacuum panels and reinforced bands
above and below the vacuum panels. This particular bottle is for
use in a "hot fill" application in which liquids are stored and
sealed in the container while hot to provide adequate
sterilization. The containers are typically filled under slight
positive pressure and at temperatures approaching the boiling point
of water when capped. However, cooling of the liquid product in the
bottle usually creates negative internal pressure, which can
partially collapse the bottle. Accordingly, the bottles are
provided with six circumferentially spaced apart vacuum panels 3 in
a central area to be covered by a label. When the volume of the hot
product inside of the bottle shrinks during cooling, the faces of
the vacuum panels are drawn inwardly to compensate for the
reduction in pressure and prevent deformation of the other parts of
the bottle. In addition, cylindrical bands 6 are disposed above and
below the region of the vacuum panels 3. These bands 6 are formed
of one or two circumferential hoop ribs 7, each made up of six
recessed rib sections 8. These ribs provide hoop reinforcement to
ensure completely cylindrical surfaces above and below the region
of the vacuum panels, to which a label can be adhered. However,
these circumferential hoop ribs are for compensating against
negative internal pressure in conjunction with the vacuum panels
and are not designed for providing against positive internal
pressure.
SUMMARY OF THE INVENTION
[0006] It is, therefore, an object of the present invention to
provide a lightweight container having acceptable sidewall
rigidity.
[0007] It is further an object of the present invention to provide
a container having acceptable sidewall rigidity and being able to
withstand internal pressure without unacceptable deformation.
[0008] It is a further object to decrease the weight of a container
without sacrificing container performance and customer
acceptance.
[0009] It is yet another object of the present invention to provide
a container having structural elements that can have an
aesthetically pleasing appearance.
[0010] According to one aspect, the present invention relates to a
container including a shell having a top section, a bottom section
and a central section connecting the top section and the bottom
section. At least a majority region of the central section is
provided with a plurality of structural ribs about its periphery,
the ribs being discontinuous in a circumferential direction
extending around the central section.
[0011] According to another aspect, the present invention relates
to a container including a shell having a top section, a bottom
section and a central section connecting the top section and the
bottom section. At least a majority region of the central section
is provided with a plurality of structural ribs about its
periphery, the ribs being discontinuous in a direction extending
around the central section.
[0012] According to yet another aspect, the present invention
relates to a container including a shell having a top section, a
bottom section and a central section connecting the top section and
said bottom section, and means for reinforcing the shell against
external pressure and internal pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is an elevational view of a first embodiment of a
container according to the present invention.
[0014] FIG. 2 is a cross-sectional view along section line 2-2 of
FIG. 1.
[0015] FIG. 3 is a cross-sectional view along section line 3-3 of
FIG. 1.
[0016] FIG. 4 is a graph comparing stiffness of containers
according to the first and second embodiments with a conventional
container.
[0017] FIG. 5 is an elevational view of a container according to a
second embodiment of the present invention.
[0018] FIG. 6 is an elevational view of a container according to a
third embodiment of the present invention.
[0019] FIG. 7 is an elevational view of a container according to a
fourth embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] A container according to a first embodiment of the present
invention is shown in FIGS. 1-3. In this preferred embodiment, the
container is in the form of a bottle 10 having an upper section 12
and a lower section 16, both connected by a central section 14.
Upper section 12 includes a shoulder portion 18 and a neck 20. Neck
20 is threaded and is connected to shoulder portion 18. A cap (not
shown) closes the neck 20 to seal the container 10.
[0021] Lower section 16 and upper section 12 have similar
cross-sections, which are aligned vertically. In the depicted
embodiment, central section 14 has a cross-section of a lesser
diameter than that of the upper and lower sections. However, the
present invention is not limited to this embodiment and the upper,
central and lower sections can have similar cross-sections.
[0022] Central section 14 is provided with a plurality of ribs 22
for structural support. In this embodiment, ribs 22 are in the form
of axisymmetric indentations aligned in a plurality of rows
throughout the central section. A horizontal land 24 is provided
between each horizontally adjacent rib 22, such that the ribs are
not continuous in the circumferential direction around the central
section. In addition, vertical lands 26 are provided between each
row of ribs. Although the ribbed region of central section 14 is
most effective when it covers the entirety of the periphery of
central section 14 as shown in FIG. 1, the present invention is not
limited to this. A container having a ribbed region that covers the
majority of the periphery of central section 14 can perform
satisfactorily.
[0023] As shown in FIG. 2, each rib 22 projects internally toward
the central axis of the bottle in a manner that it varies in depth.
That is, the depth of each rib 22 smoothly increases from each end
in the horizontal direction to a maximum depth in the middle. With
this structure, stress carried by the rib can be spread out
throughout its length. Additionally, the blend radius 28 of each
rib 22, that is, the curvature of the rib in the vertical
direction, is smooth and preferably circular as shown in FIG.
3.
[0024] Depending on the height of central region 14 of container 10
and depending on the applications for which the container is
intended, the number of rows of ribs and the number and shape of
the ribs vary. In the first embodiment, when used with a 0.5 liter
bottle, 13 rows of ribs are provided, with 5 ribs in each row. Each
rib is about 1.2 in. long and has a maximum depth of 0.04 in.
Preferably, the ribs in one row are not aligned vertically with
ribs in adjacent rows. As shown in FIG. 1, ribs in every alternate
row are aligned vertically. This staggered arrangement improves the
structure of the container by insuring that at least one rib is
always activated when the container is squeezed.
[0025] The container of the first embodiment provides both
sufficient hoop stiffness or rigidity, that is, resistance to
crushing by a side load, as well as sufficient resistance to
deformation of the side wall due to internal pressure. For internal
pressure, the fundamental design concept employed uses the idea
that for a container under internal pressure, membrane (midplane)
stresses develop in the walls, just like a balloon under pressure.
In addition to these membrane stresses, there are also bending
stresses that develop depending on the thickness of the shell.
Thus, the total stress state due to internal pressure is a sum of
the membrane (or midplane) as well as the bending stresses. The
bending stresses usually influence the magnitude of the stress on
the outside and inside surfaces of the container. In containers
made from PET subject to internal pressure over long periods of
time, it is critical that the midplane (or membrane) component of
the stress state be minimized to eliminate creep rupture problems.
This is incorporated in the rib design geometry and dimensions of
this embodiment, wherein the parameters have been selected such
that in a thin walled PET shell, midplane stresses are maintained
below the yield strength of oriented and crystallized PET.
[0026] In addition, in this embodiment, because the hoop stiffness
is sufficiently great, the thickness of the plastic forming the
container can be reduced. In a typical PET bottle, the thickness of
the plastic is approximately 0.012 in., but with the structure of
the present invention the thickness of the plastic forming the
bottle can be reduced to less than 0.010 in., at least in central
section 14, and still maintain a comparable hoop stiffness. For
example, in the graph of FIG. 4, with a conventional
continuously-ribbed 0.50 liter bottle formed of 0.008 in. PET and
having a nominal diameter of 2.3 in. in the central section, it has
been found that the diameter of the bottle changes significantly
(that is, its side wall is displaced) at relatively low external
loads. By contrast, in a similarly dimensioned bottle provided with
ribs according to the first embodiment, this diameter changes
significantly less at much higher loads. The intermediate bands
support the hoop stiffness in the rib section and help transmit
axial stress from one row of ribs to the next.
[0027] It has been found with the structure according to the first
embodiment, midplane and bending stresses are significantly reduced
as compared with a conventional bottle with continuous ribs.
[0028] The arrangement of the ribs is not limited to that shown in
the first embodiment. For example, in the container 100 shown in
FIG. 5, although the general shape of the ribs 122 is similar to
that in the first embodiment, the size of the ribs is decreased,
and the number of rows of ribs and ribs per row is increased. For
example, for a 0.5 liter PET bottle, 25 rows of ribs with 16 ribs
per row are provided. Each rib has a length of about 0.5 in. and a
maximum depth of 0.04 in. As shown in the graph of FIG. 4, with the
second embodiment the stiffness of the container is even more
improved.
[0029] The number, size and shape of the ribs can be modified to
achieve the desired axial stiffness and external and internal
pressure resistance. Depending on the intended application of a
container being designed, the arrangement of the ribs can be
designed accordingly.
[0030] The orientation of the ribs is also not limited to that
shown in the first and second embodiments. That is, although the
ribs are shown in the first and second embodiments to be parallel
to the horizontal direction, they can be rotated up to 180.degree.,
relative to the horizontal direction and still achieve desired
results. For example, in the container 200 shown in FIG. 6, the
ribs 222 are rotated 45.degree. relative to the horizontal. In this
third embodiment, the ribs 222 need not be staggered in the
vertical and horizontal directions to achieve the desired
result.
[0031] In the container 300 of the fourth embodiment depicted in
FIG. 7, the ribs 322 are rotated 90.degree. relative to the
horizontal such that they are disposed vertically. In this
embodiment, alternate rows of ribs 322 are staggered as in the
first and second embodiments.
[0032] As described above, the containers are preferably formed of
PET, but can be formed of other materials including high- and
low-density polyethylene, polypropylene and polyvinyl chloride, for
example. PET containers are typically blow-molded. The blow-molding
process is well-known to those in the art and it is considered
unnecessary herein to explain the process in which a preform is
blow-molded in a conventional manner.
[0033] While the present invention has been described as to what is
currently considered to be the preferred embodiments, it is to be
understood that the invention is not limited to them. To the
contrary, the invention is intended to cover various modifications
and equivalent arrangements within the spirit and scope of the
appended claims. The scope of the following claims is to be
accorded the broadest interpretation so as to encompass all such
modifications and equivalent structures and functions.
* * * * *