U.S. patent number 3,831,745 [Application Number 05/201,873] was granted by the patent office on 1974-08-27 for container which is nestable without sticking.
This patent grant is currently assigned to Monsanto Company. Invention is credited to John H. Rump, Joseph E. Smith.
United States Patent |
3,831,745 |
Rump , et al. |
August 27, 1974 |
CONTAINER WHICH IS NESTABLE WITHOUT STICKING
Abstract
A nestable, cup-like container having special circumferentially
extending stacking means formed in its sidewall which includes two
sets of inwardly extending supporting projections, each set being
intermediate the other, one set extending inwardly further than the
other and serving as the primary means of support of a similar
container when nested therein, whereas the other set serves as a
secondary means of support for such a similar container.
Inventors: |
Rump; John H. (Lisle, IL),
Smith; Joseph E. (Palos Hills, IL) |
Assignee: |
Monsanto Company (St. Louis,
MO)
|
Family
ID: |
22747643 |
Appl.
No.: |
05/201,873 |
Filed: |
November 24, 1971 |
Current U.S.
Class: |
206/520 |
Current CPC
Class: |
B65D
1/265 (20130101) |
Current International
Class: |
B65D
1/22 (20060101); B65D 1/26 (20060101); B65d
021/02 () |
Field of
Search: |
;220/97C,97F
;229/1.5B |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lowrance; George E.
Attorney, Agent or Firm: Murphy; Michael J.
Claims
What is claimed is:
1. A nestable, thin walled, cup-like plastic container comprising a
circular bottom, a sidewall joined to said bottom at its peripheral
margin and tapering generally upwardly and outwardly to an upper
margin defining an open end and circumferential stacking means
forming a part of said sidewall, said stacking means comprising a
first series of circumferentially positioned inwardly extending
projections reversely tapered toward the container axis having
upper surface portions for supporting contact with portions of a
similarly configured container when nested therein and a second
series of projections intermediate said first series extending
inwardly in a reverse taper toward the container axis beyond said
first series, said second series having upper surface portions for
supporting contact with additional portions of said similarly
configured container, the length of the second series of
projections measured circumferentially of the container being no
greater than that of the similarly measured length of the first
series of projections.
2. The container of claim 1 wherein said second series of
projections are between three to eight in number and are
substantially equispaced circumferentially around the
container.
3. The container of claim 1 wherein said second series of
projections extend inwardly of the first series of projections by
an amount equal to from 1.5 to 13 times the extent of inward
projection of the first series of projections.
4. The container of claim 1 wherein said circumferential length of
the second series of projections is from 25 to 100 percent of that
of the first series of projections.
5. A plurality of thin walled, substantially identical, nested
thermoplastic cups forming a stack, each of said cups comprising a
base, an outwardly tapering sidewall extending upwardly from the
peripheral margin of the base to an upper margin defining an open
end and circumferential stacking means forming a part of said
sidewall, said stacking means comprising a first series of
circumferentially positioned inwardly extending projections
reversely tapering toward the cup axis having upper surface
portions in supporting contact with portions of the peripheral
margin of the next uppermost container in the stack and a second
series of projections intermediate said first series extending
inwardly in a reverse taper toward the cup axis beyond said first
series and having upper surface portions in supporting contact with
other portions of the peripheral margin of said next uppermost
container in the stack, the extent of circumferential contact
between the upper surface portions of the second series of
projections and the peripheral margin of said next uppermost
container being less than the extent of circumferential contact
between the upper surface portions of the first series of
projections and the peripheral margin of said next uppermost
container.
6. The container of claim 5 wherein the two sets of reversely
tapered intermediate portions interconnect the peripheral margin of
the container with the inwardly extending projections, the set of
reversely tapered portions connecting the most inwardly extending
projections being at an angle of from 6.5.degree. to 25.degree.
with the vertical, the other set of reversely tapered portions
being at an angle of from 2.degree. to 6.degree. with the vertical.
Description
BACKGROUND OF THE INVENTION
This invention relates to plastic containers and more particularly
to plastic containers which can be nested within and subsequently
freely separated from each other without sticking.
The increase in the sale of beverages dispensed via automatic
canteen devices has caused a sharp increase in the demand for
single use, expendable containers which are adapted for use in such
devices. However, problems have been encountered in designing
containers for such a use in that it is necessary for each
individual container to consistently readily drop by gravity from
the bottom of a stack into vending position when the beverage
purchaser puts his consideration into the dispensing device.
In general, these design problems have been overcome by
incorporating an annular, horizontally disposed shelf or step in
the cup intermediate its top and bottom margins or alternatively at
its bottom margin to permit the cups to nest in a relatively
friction-free manner. This shelf projects toward the interior of
the cup, serves to support an adjacent cup in nested relationship
and permits ready release of the lowermost cup from the next
succeeding cup in the stack, particularly when the cups are stored
in a vending dispenser. To form this horizontally disposed step or
shelf, the container is tapered inwardly opposite to the general
outward taper of the sidewall for a relatively short axial
distance. Thus, in U.S. Pat. No. 3,139,213, this shelf is shown
around the full periphery of the cup, and undoubtedly, such a
configuration which extends sufficiently inwardly toward the cup
axis as to provide maximum interference with full insertion of a
second container into the first represents the ideal in preventing
telescoping (supported surface of one cup proceeding beyond
supporting surface of another) when a stack of nested cups is
axially loaded, e.g. during handling, or when the total height of
the stack becomes too great. Unfortunately, when the shelf is
extended sufficiently inwardly in this manner, the reverse angle of
the tapered surface is so great as to interfere with the discharge
of the cup from the molding cavity, thus resulting in reduced
production rates, and at times distortion of the cup. In addition,
when such a continuous stacking ring having a relatively severe
reverse taper is employed, there is a significant tendency for the
Z-shaped area to fold on itself and collapse in accordion fashion
when the stack is loaded from above, which, of course, causes
undesirable frictional sticking of adjacent cups in the stack.
To alleviate these problems, it has been proposed, as disclosed in
British Pat. No. 1,015,351, and Australian Pat. No. 254,306 to
interrupt such a continuous support configuration, or in other
words, portions intermediate supporting shelf sections would be
uninterrupted parts of the cup sidewall. A somewhat different
interrupted configuration is disclosed in U.S. Pat. No. 3,091,360,
wherein support is obtained by the interference between a large
diameter surface at the base of a support lug of an inner,
supported container and a smaller diameter surface at the top of
such a lug of an outer, supporting container. In addition, the
spaces intermediate such lugs in the outer supporting container is
open to the atmosphere with respect to the inner supported
container, such openings allowing the chamber between adjacent
stacked cups to be vented. Though such configurations can function
admirably under certain conditions, they are not without
limitations. Theoretically, with the cup configurations of the
aforementioned British and Australian patents, it is possible for
the non-interfering portions of the cup intermediate the support
shelf portions to line up during nesting, especially if such
non-interfering portions extend around a substantial portion of the
cup periphery, and two such adjacent cups would accordingly jam
tightly against one another. Decreasing the extent of interruption
increases the susceptiblity of the cup to the collapsing and mold
removal problems mentioned previously. In addition, with any of the
interrupted configurations of the aforementioned patents, the load
bearing supporting surface is diminished to the extent of the
interruptions, and accordingly, the susceptability of cups within a
stack to telescope is increased for the application of a given
load.
SUMMARY OF THE INVENTION
Now, however, a new stacking ring configuration has been developed
which overcomes this dilemma of difficulties occurring in the prior
art.
Accordingly, it is a principal object of this invention to provide
nestable containers adapted for use in automatic dispensing
devices.
Another object of this invention is to provide nestable containers
adapted for use in automatic dispensing devices which are provided
with novel means to minimize contact between adjacent walls of
containers within a stack.
A further object of this invention is to provide nestable
containers adaptable for use in automatic dispensing devices which
can be produced at high rates with a minimum of distortion during
ejection from the forming molds.
An additional object of this invention is to provide containers of
the aforementioned variety having a stacking means therein which
gives good balance between ease of removal of the container from
the mold and resistance to telescoping.
A specific object of this invention is to provide a stacking ring
configuration in a thin walled, plastic container which provides
substantial support during stacking, does not collapse when axially
loaded under normal handling conditions, yet is readily released
from the mold in which it is formed.
Other objects of this invention will in part be obvious and will in
part appear hereinafter.
These and other objects are accomplished by providing a nestable,
thin walled, cup-like plastic container comprising a circular
bottom, a sidewall joined to the bottom at its peripheral margin
and tapering generally upwardly and outwardly to an upper margin
defining an open end and circumferential stacking means forming a
part of the sidewall, said stacking means comprising a first series
of circumferentially positioned, inwardly extending projections
having upper surface portions for supporting contact with portions
of a similarly configured container when nested therein and a
second series of projections intermediate the first series
extending inwardly beyond the first series having upper surface
portions for supporting contact with additional portions of the
similarly configured container, the length of the second series of
projections measured circumferentially of the container being no
greater than that of the similarly measured length of the first
series of projections.
BRIEF DESCRIPTION OF THE DRAWINGS
In describing the overall invention, reference will be made to the
accompanying drawings wherein:
FIG. 1 is a front, elevational view of a cup embodying the present
invention;
FIG. 2 is a horizontal, sectional view on an enlarged scale taken
along line 2--2 of FIG. 1;
FIG. 3 is a longitudinal, sectional view illustrating the manner in
which the portion of the cup seen in a sectional view taken along
the line 3--3 of FIG. 1 supports the next adjacent cup in a stack;
and
FIG. 4 is a view similar to FIG. 3 taken along the line 4--4 of
FIG. 1.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
Referring now to the drawings, there is illustrated in FIG. 1, a
nestable, thin walled, cup-like plastic container 10 comprising a
circular bottom 12 which may be raised inwardly as illustrated in
FIGS. 3 and 4 to provide improved resistance against outward
deformation when the container is full. Cup 10 further includes
sidewall 14 joined to a peripherally continuous margin 16 of bottom
12 and tapering generally upwardly and outwardly in a substantially
frustro-conical configuration to an upper margin 18 defining an
open end. Upper margin 18 is preferably provided with a rim 20, and
is of larger diameter than lower peripheral bottom margin 16.
Peripheral stacking means 22 is formed as an integral part of
sidewall 14 in the lower portion thereof. Stacking means 22
comprises a first series of reversely tapered intermediate portions
24 interconnecting peripheral margin 16 with a set of projections
26 at the upper end of each portion 24 which extend inwardly from
sidewall 14 a distance on the order of 0.07 inch. In the
illustrated embodiment, each portion 24 is at an angle of 6.degree.
with the vertical as defined by A in FIG. 4. To permit ease of
release of container 10 from its forming mold while at the same
time permitting projections 26 to provide a level of support in a
manner to be more fully described hereafter, A should be kept
within the range of from 2.degree. to 6.degree. with respect to the
axis of cup 10. Also provided as an integral part of
circumferential stacking means 22 is a second set of reversely
tapered intermediate portions 28 each of which lies adjacent an
intermediate portion 24. Portions 28 interconnect continuous
peripheral margin 16 with a series of projections 30 at the upper
ends thereof which extend inwardly from sidewall 14 a distance on
the order of 0.103 inch. Intermediate portions 28 in the
illustrated embodiment form an angle B with the vertical of
15.degree.. Angle B is perferably maintained within the range of
from 6.5.degree. to 25.degree. with respect to the axis of cup 10
for the same reasons given for holding angle A within the aforesaid
range. Each projection 30 extends inwardly toward the axis of cup
10 beyond projections 26, as is apparent from FIG. 2, and the total
circumferential length of projections 30 is less than that of the
similarly measured length of projections 26. Though angles A and B
are different in order to structurally strengthen stacking means 22
against an accordion type collapse, the upper surface of each
projection 26 and 30 preferably lies in a substantially common
horizontal plane 31 which is perpendicular to the axis of cup
10.
Referring now more particularly to FIG. 3, there is illustrated a
plurality of nested thermoplastic cups 10 forming a stack, each of
the cups being constructed as illustrated in FIGS. 1 and 2. Inner
or upper cup (FIG. 3) receives its primary support through contact
between the outer surface of its peripheral margin 16 with the
upper surface of each inwardly extending projection 30 in the
outer, lower cup. However, as illustrated in FIG. 4, the remaining
portions of the outer surface of peripheral margin 16 of the inner
or upper cup is also supported through interfering contact with the
surface of each projection 26, such that inner cup 10 is supported
about the full periphery of its margin 16. Thus, due to the
presence of shallow projections 26, in combination with deep
projections 30, it is impossible for one cup to telescope within
another, or for the supporting projections to line up with one
another such that an inner cup may fit completely within an outer
cup in an undesirable manner.
The above description and particularly the drawings are set forth
for the purpose of illustration only and is not to be taken in a
limited sense.
It has been found with the novel stacking means of the present
invention, that the total circumferential length of the series of
deep projections 30 should always be less than that of the series
of shallow projections 26 in order for the container to be readily
released from its forming mold. Moreover, it is preferred that this
circumferential length of projections 30 be maintained at a level
of from 25 to 100 percent of that of series 26. Since projections
30 provide the primary means of support of a nested container, it
is important that they provide more interference with such nested
container than that of projections 26. Accordingly, each projection
30 should always extend inwardly toward the axis of container 10 an
extent greater than that of a projection 26, and preferably by an
amount equal from 1.5 to 13 times the inward extent of each
projection 26. Furthermore, it is preferred that the number of deep
projections 30 around the circumferential length of the container
be from 3 to 8 and be substantially equally spaced from each
other.
The cups of the present invention may be injection molded or may be
formed from thermoplastic sheet material by causing a portion of
the sheet to be drawn or forced into a female mold cavity and
against the inner walls thereof. In this manner, upon conformation
of the sheet to the inner configuration of the mold cavity, the
plastic cup is cooled somewhat after which it is ejected from the
mold cavity. The difficulty or ease in which the cup is ejected
will depend to a large extent on the means used to eject the cup,
the tendency of the plastic to stick to the inner walls of the mold
cavity and the negative angles or projections within the female
molding cavity. In the present invention, we are concerned with
reducing the gripping action caused by the projections or annual
protruberances in the mold cavity which are used to form the
shoulders of the stacking ring of the cup, while at the same time
maintaining the release efficiency of the cups when in nesting
relationship prior to vending. It is found that the projections or
protruberances required in the mold or cavity to produce the
stacking means in the present cup offer a substantially reduced
resistance to the withdrawal or stripping of the cup from the
mold.
In general, the plastics used to form the cups of this invention
are thermoplastic materials which include polymers such as those
based on styrene, vinyl halide, vinylidene halide, vinyl acetate,
cellulose acetate or butyrate, ethyl cellulose, acrylic acid
esters, methacrylic acid esters, acrylonitrile, methacrylonitrile,
ethylene, propylene and higher olefins, isobutylene,
fluoro-olefines, and chlorofluoro-olefines, as well as copolymers,
interpolymers, graft polymers, and chlorinated and chlorosulfonated
polymers of the monomers corresponding to the above-mentioned
polymeric products and mixtures of the same. A particularly useful
material for forming these cups is a rubber-modified polystyrene or
polystyrene which preferably has incorporated therein a rubber
compound grafted or mechanically blended therein.
As previously indicated, the cups of the present invention find
application in beverage vending machines, such as coffee machines
and soft drink machines and wherever storage space dictates that a
plurality of cups in telescoping arrangement must be stored. The
cups have improved structural stability and can be easily dispensed
with little or no difficulty from the bottom of a stack while at
the same time presenting fewer manufacturing difficulties as
regards the molding operation and particularly the withdrawal of
the cup from the mold. Consequently, they may be produced at a high
rate and at a very low cost.
It is obvious that many variations may be made in the products set
forth herein without departing from the spirit and scope of this
invention, as hereinafter claimed.
* * * * *