U.S. patent application number 09/790072 was filed with the patent office on 2001-07-26 for footed container and base therefor.
This patent application is currently assigned to Crown Cork & Seal Technologies Corporation. Invention is credited to Cheng, Jizu J., Krich, Jeffrey D..
Application Number | 20010009244 09/790072 |
Document ID | / |
Family ID | 22350315 |
Filed Date | 2001-07-26 |
United States Patent
Application |
20010009244 |
Kind Code |
A1 |
Cheng, Jizu J. ; et
al. |
July 26, 2001 |
Footed container and base therefor
Abstract
A molded polymeric container that is shaped to exhibit superior
characteristics of light weighting, stability against toppling and
resistance to stress cracking includes a conventional cylindrical
body portion having a longitudinal axis and a circumferential
sidewall and a novel bottom portion. The bottom portion includes a
central pushup area of uniformity that is substantially uniform
within a spatial rotation about the longitudinal axis. The area of
uniformity has a radius R.sub.G. The bottom also includes a
plurality of support feet that surround and protrude downwardly
from the pushup area. Each of the support feet have a bottom
support surface with an inner point of contact and an outer point
of contact. The outer points of contact together define an outer
contact radius R.sub.OC. The bottom portion as a whole has a radius
of maximum width R.sub.BASE A plurality of ribs are positioned in
valleys between the support feet. Each of these ribs is positioned
between and helps define two of the support feet. At least one of
the ribs has a localized radius of curvature R.sub.C that
intersects an arc connecting inner points of contact of two
adjacent support feet. Advantageously, the radius of uniformity is
within the range of about 16% to about 26% of R.sub.OC; and R.sub.C
is within the range of about 70% to about 110% of R.sub.BASE.
Inventors: |
Cheng, Jizu J.; (Burr Ridge,
IL) ; Krich, Jeffrey D.; (Orland Park, IL) |
Correspondence
Address: |
Woodcock Washburn Kurtz
Mackiewicz & Norris LLP
46th Floor
One Liberty Place
Philadelphia
PA
19103
US
|
Assignee: |
Crown Cork & Seal Technologies
Corporation
|
Family ID: |
22350315 |
Appl. No.: |
09/790072 |
Filed: |
February 21, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09790072 |
Feb 21, 2001 |
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09444982 |
Nov 22, 1999 |
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6213325 |
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09444982 |
Nov 22, 1999 |
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09113586 |
Jul 10, 1998 |
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5988416 |
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Current U.S.
Class: |
215/375 ;
220/606; 220/608 |
Current CPC
Class: |
B65D 1/0284
20130101 |
Class at
Publication: |
215/375 ;
220/606; 220/608 |
International
Class: |
B65D 001/02 |
Claims
What is claimed is:
1. A molded polymeric container that is shaped to exhibit superior
characteristics of light weighting, stability against toppling and
resistance to stress cracking, comprising: a substantially
cylindrical body portion having a longitudinal axis and a
circumferential sidewall; and a bottom portion comprising: a
central pushup area of uniformity that is substantially uniform
within a spatial rotation about the longitudinal axis, said area of
uniformity having a radius R.sub.G; a plurality of support feet
surrounding and protruding downwardly from the pushup area, each of
the support feet having a bottom support surface with an inner
point of contact and an outer point of contact, said outer points
of contacting together defining an outer contact radius R.sub.OC;
said bottom portion further having a radius of maximum width
R.sub.BASE; a plurality of ribs positioned in said valleys between
said support feet, each of the ribs being positioned between and
helping to define two of the support feet, at least one of said
ribs having a localized radius of curvature R.sub.C that intersects
an arc connecting inner points of contact of two adjacent support
feet; and wherein said radius of uniformity is within the range of
about 16% to about 26% of R.sub.OC; and R.sub.C is within the range
of about 70% to about 110% of R.sub.BASE.
2. A container according to claim 1, wherein: said radius of
curvature R.sub.C defines an angle .alpha..sub.IC with respect to
said longitudinal axis; said at least one rib has a localized
radius of curvature R.sub.CG that intersects an outer boundary of
said area of uniformity, said radius of curvature R.sub.G defining
an angle .alpha..sub.G with respect to said longitudinal axis; and
and .alpha..sub.IC minus .alpha..sub.G is within a range of about
16.degree. to about 30.degree..
3. A container according to claim 1, wherein said radius of
uniformity is within the range of about 18% to about 24% of
R.sub.OC.
4. A container according to claim 1, wherein R.sub.C is within the
range of about 85% to about 100% of R.sub.BASE.
5. A container according to claim 2, .alpha..sub.IC minus
.alpha..sub.G is within a range of about 18.degree. to about
22.degree..
6. A container according to claim 1, wherein R.sub.OC is at least
about 70% of R.sub.BASE.
7. A container according to claim 6, wherein R.sub.OC is within the
range of about 72-75% of R.sub.BASE.
8. A container according to claim 1, wherein said rib has a varying
radius throughout its length.
9. A container according to claim 1, wherein said bottom portion
further has a dimension h.sub.OC that is defined as the height of
the rib directly above the circle that is defined by said outer
contact radius R.sub.OC, and wherein 3 h OC = .PI. Rbase Sin n ( 1
- Cos ) ( A - Roc Rbase ) where n=the number of feet in the bottom;
and A=a ring index, and wherein A is within a range of about 0.9 to
about 1.15.
10. A container according to claim 9, wherein ring index A is
within the range of about 0.95 to about 1.05.
11. A molded polymeric container that is shaped to exhibit superior
characteristics of light weighting, stability against toppling and
resistance to stress cracking, comprising: a substantially
cylindrical body portion having a longitudinal axis and a
circumferential sidewall; and a bottom portion comprising: a
central pushup area; a plurality of support feet surrounding and
protruding downwardly from the pushup area, each of the support
feet having a bottom support surface with an inner point of contact
and an outer point of contact, said outer points of contacting
together defining an outer contact radius R.sub.OC; and wherein
said bottom portion further has a dimension h.sub.OC that is
defined as the height of the rib directly above the circle that is
defined by said outer contact radius R.sub.OC, and wherein 4 h OC =
.PI. Rbase Sin n ( 1 - Cos ) ( A - Roc Rbase ) where n--the number
of feet in the bottom; and A=a ring index, and wherein A is within
a range of about 0.9 to about 1.15.
12. A container according to claim 11, wherein said bottom portion
further comprises a central pushup area of uniformity that is
substantially uniform within a spatial rotation about the
longitudinal axis, said area of uniformity having a radius R.sub.G
and said radius of uniformity is within the range of about 16% to
about 26% of R.sub.OC.
13. A container according to claim 11, wherein said bottom portion
further includes a plurality of ribs positioned in said valleys
between said support feet, each of the ribs being positioned
between and helping to define two of the support feet, at least one
of said ribs having a localized radius of curvature R.sub.C that
intersects an arc connecting inner points of contact of two
adjacent support feet; and wherein R.sub.C is within the range of
about 70% to about 110% of R.sub.BASE.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention This invention relates broadly to
the field of container making, and more specifically to blow molded
plastic bottles, such as the PET bottles that are in common use
today for packaging soft drinks such as soda. More specifically,
the invention relates to an improved footed container and bottom
therefor that exhibits superior characteristics of light weighting,
stability and resistance to stress cracking.
[0002] 2. Description of the Related Technology
[0003] During the last twenty-five years or so, there has been a
dramatic shift in the packaging of carbonated beverages,
particularly, soft drinks, away from glass containers and toward
plastic containers. The plastic containers initially took the form
of a two-piece construction, wherein a plastic bottle having a
generally hemispherical bottom was applied a separate base cup,
which would permit the bottle to be stood upright. The
hemispherical bottom was seen as the most desirable shape for
retaining the pressure generated by the carbonation within the
container. Pressures in such containers can rise to 100 p.s.i. or
more when the bottled beverage is exposed to the sun, stored in a
warm room, car trunk, or the like.
[0004] Such plastic containers represented a significant safety
advantage over glass containers when exposed to the same internal
pressures. However, the two-piece construction was not economical
because it required a post molding assembly step, and, also a
separation step prior to reclaiming or recycling the resins forming
the bottle and base cup.
[0005] During this period of development, various attempts were
made to construct a one-piece, self-supporting container that would
be able to retain the carbonated beverages at the pressures
involved. Such a one-piece container requires the design of a base
structure which will support the bottle in an upright position and
will not bulge outwardly at the bottom. A variety of designs were
first attempted, with most following one of two principal lines of
thought. One line of designs involved a so-called champagne base
having a complete annular peripheral ring. Examples of such bottles
are found in U.S. Pat. Nos. 3,722,726; 3,881,621; 4,108,324;
4,247,012; and, 4,249,666. Another variety of designs is that which
included a plurality of feet protruding downward from a curved
bottom. Examples of this variety are to be found in U.S. Pat. Nos.
3,598,270; 4,294,366; 4,368,825; 4,865,206; and, 4,867,323. In
recent years, the latter type of design has achieved primacy in the
marketplace.
[0006] Footed one piece bottles present certain problems, though,
that have not yet been worked out to the satisfaction of the
packaging industry and its customers. For example, the uneven
orientation of the polymer in the footed area of the bottom can
contribute to uneven post-filling expansion of either one or more
feet or the central portion of the bottom, creating what is
generally referred to as a "rocker." In addition, the presence of
the feet themselves and the need to force the oriented material
into the shape of the feet can create stress points in the
container bottom that can adversely affect container shape.
Container bottom designs that minimize stress and disorientation of
the polymer during molding, then are considered preferable.
[0007] Another concern in the design of container bottoms for one
piece containers is the possibility of stress cracking in the base.
The amount of stress cracking is related to the geometry of the
base. Relatively large radius curves in the base will reduce the
potential for stress cracking compared to a base with small radius
curves.
[0008] Yet another factor that is important in the design of such
containers is that of positional stability after filling and
pressurization of the container. It is preferable, from both a
bottler's and consumer's standpoint, for a filled container to be
as resistant to toppling as possible. The stability of a filled
container is closely related to the radius of its "outside standing
ring," i.e. the distance that the bottom contact surfaces of the
feet extend from the center axis of the container.
[0009] A further factor that must be taken into account in the
design of footed container bottoms is that of efficient
distribution of material within the article, so that the article is
as "light weighted" as possible given the necessary strength,
volumetric and stability requirements of the container. Light
weighting is in particular important economically for the
manufacturer of the container, since it directly impacts material
costs.
[0010] A need exists for an improved bottom design for a polymeric
one piece container that will optimize use of material relative to
strength, reduce the possibility of stress cracking, permit molding
with a minimum of stress and disorientation of the polymer
material, and exhibit superior resistance against toppling.
SUMMARY OF THE INVENTION
[0011] Accordingly, it is an object of the invention to provide an
improved bottom design for a polymeric one piece container that
will optimize use of material relative to strength, reduce the
possibility of stress cracking, permit molding with a minimum of
stress and disorientation of the polymer material, and exhibit
superior resistance against toppling.
[0012] In order to achieve the above and other objects of the
invention, a molded polymeric container according to one aspect of
the invention is shaped to exhibit superior characteristics of
light weighting, stability against toppling and resistance to
stress cracking. It includes a conventional cylindrical body
portion having a longitudinal axis and a circumferential sidewall
and a novel bottom portion. The bottom portion includes a central
pushup area of uniformity that is substantially uniform within a
spatial rotation about the longitudinal axis. The area of
uniformity has a radius R.sub.G. The bottom also includes a
plurality of support feet that surround and protrude downwardly
from the pushup area Each of the support feet have a bottom support
surface with an inner point of contact and an outer point of
contact. The outer points of contact together define an outer
contact radius R.sub.OC. The bottom portion as a whole has a radius
of maximum width R.sub.BASE. A plurality of ribs are positioned in
valleys between the support feet. Each of these ribs is positioned
between and helps define two of the support feet. At least one of
the ribs has a localized radius of curvature R.sub.C that
intersects a line connecting inner points of contact of two
adjacent support feet. Advantageously, the radius of uniformity is
within the range of about 16% to about 26% of R.sub.OC; and R.sub.C
is within the range of about 70% to about 110% of R.sub.BASE.
[0013] According to a second aspect of the invention, a molded
polymeric container that is shaped to exhibit superior
characteristics of light weighting, stability against toppling and
resistance to stress cracking includes a substantially cylindrical
body portion having a longitudinal axis and a circumferential
sidewall; and a bottom portion that includes a central pushup area;
a plurality of support feet surrounding and protruding downwardly
from the pushup area, each of the support feet having a bottom
support surface with an inner point of contact and an outer point
of contact, the outer points of contacting together defining an
outer contact radius R.sub.OC; and wherein the bottom portion
further has a dimension h.sub.OC that is defined as the height of
the rib directly above the circle that is defined by the outer
contact radius R.sub.OC, and wherein 1 h OC = .PI. Rbase Sin n ( 1
- Cos ) ( A - Roc Rbase )
[0014] where n=the number of feet in the bottom; and
[0015] A=a ring index, and wherein A is within a range of about 0.9
to about 1.15.
[0016] These and various other advantages and features of novelty
that characterize the invention are pointed out with particularity
in the claims annexed hereto and forming a part hereof. However,
for a better understanding of the invention, its advantages, and
the objects obtained by its use, reference should be made to the
drawings which form a further part hereof, and to the accompanying
descriptive matter, in which there is illustrated and described a
preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view of a container that is
constructed according to a preferred embodiment of the
invention;
[0018] FIG. 2 is a side elevational view of the container shown in
FIG. 1;
[0019] FIG. 3 is a bottom plan view of the container shown in FIGS.
1 and 2;
[0020] FIG. 4 is a diagrammatical depiction of certain features of
the invention as it is embodied in the Figures described above;
and
[0021] FIG. 5 is a cross-section taken along lines 5-5 in FIG.
4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0022] Referring now to the drawings, wherein like reference
numerals designate corresponding structure throughout the views,
and referring in particular to FIG. 1, a molded polymeric container
10 that is shaped to exhibit superior characteristics of light
weighting, stability against toppling and resistance to stress
cracking includes a conventional cylindrical body portion 12 having
a longitudinal axis 13, shown in FIG. 2. As is conventional,
container 10 includes a threaded finish portion 14, a tapered neck
portion 15 connecting the body portion 12 to the finish portion 14,
and a novel and advantageous bottom portion 16.
[0023] In the preferred embodiment, bottom portion 16 includes a
central pushup area 22 of uniformity that is substantially uniform
within a spatial rotation about the longitudinal axis 13. The area
of uniformity has a radius R.sub.G, as is shown in FIG. 4. One of
the principles of the invention is to maximize this relative size
of this area 22, which has the effect of promoting light weighting
of the container 10. Bottom portion 16 also includes a plurality of
support feet 18 that surround and protrude downwardly from the
pushup area 22. Each of the support feet 18 have a bottom support
surface 24 with an inner point of contact 26 and an outer point of
contact 28. The outer points of contact 28 together define an outer
contact radius R.sub.OC, also known as the outside standing ring of
the base. The bottom portion 16 as a whole has a radius of maximum
width R.sub.BASE. The larger the outside standing ring, the greater
the stability of the container is against tipping. In the preferred
embodiment, the outside standing R.sub.OC is within the range of
about 72% to about 75% Of R.sub.BASE.
[0024] A plurality of ribs 20 are positioned in valleys between the
support feet 18. Each of these ribs 20 is positioned between and
helps define two of the support feet 18. The ribs 20 are preferably
of varying radii of curvature along their length, from near the
pushup area 22 to where they taper into the sidewall 12 of the
container. At least one of the ribs 20 has a localized radius of
curvature R.sub.C at a point where it intersects an arc, with its
points equidistant from the axis 13, connecting inner points 26 of
contact of two adjacent support feet 18. Advantageously, the radius
of uniformity is within the range of about 16% to about 26% of
R.sub.OC; and R.sub.C is within the range of about 70% to about
110% of R.sub.BASE. More preferably, the radius of uniformity is
within the range of about 18% to about 24% of R.sub.OC; and R.sub.C
is within the range of about 85% to about 100% of R.sub.BASE. Also
within the ambit of the invention are ranges of the ratio of the
radius of uniformity R.sub.G to R.sub.OC having lower values of any
value between 16 and 20, and upper values of any value between 22
to 26. Further within the ambit of the invention are ratios of
R.sub.C to R.sub.BASE within a range that is any combination of a
values 70% to 130%.
[0025] As may further be seen in FIG. 4, the localized radius of
curvature R.sub.C defines an angle .alpha..sub.IC with respect to
the longitudinal axis 13. The rib 20 has a second localized radius
of curvature R.sub.CG at the point where it intersects the outer
boundary of the area of uniformity 22. The radius of curvature
R.sub.CG defines an angle .alpha..sub.G with respect to the axis
13, as may be seen in FIG. 4.
[0026] Advantageously, an angle that is visible in FIG. 4 and is
defined as .alpha..sub.IC minus .alpha..sub.G is within a range of
about 16.degree. to about 18.degree.,or, more preferably, within a
range of about 18.degree. to about 22.degree.. Ranges with lower
end values of between 16.degree. and 18.degree., and higher end
values of between 18.degree. and 22.degree. are also within the
ambit of the invention.
[0027] Referring now to FIGS. 4 and 5, it will be seen that the
bottom portion 16 further has a dimension h.sub.OC that is defined
as the height of the rib directly above the circle that is defined
by the outer contact radius R.sub.OC. This dimension h.sub.OC is
highly relevant to the control of optimal hoop stretch of the
container bottom during formation so that is matches as closely as
possible the stretch of the major diameter section of the
container. As may be seen in FIG. 5, which is a cross-section taken
along lines 5-5 in FIG. 4, the side walls of the feet form angles
with respect to the axis of the instant radius of the rib 20 at the
point where the vertical projection of the radius R.sub.OC
intersects the rib 20.
[0028] Optimally, according to one aspect of the invention it has
been determined that 2 h OC = .PI. Rbase Sin n ( 1 - Cos ) ( A -
Roc Rbase )
[0029] where n=the number of feet in the bottom; and A=a ring
index, and wherein A is within a range of about 0.9 to about 1.15.
More preferably, ring index A is within the range of about 0.95 to
about 1.05.
[0030] It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size and arrangement of parts within the
principles of the invention to the lull extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
* * * * *