U.S. patent application number 10/825497 was filed with the patent office on 2004-10-07 for plastic bucket and lid.
Invention is credited to von Holdt, John W. JR., von Holdt, John W. SR..
Application Number | 20040195252 10/825497 |
Document ID | / |
Family ID | 27792394 |
Filed Date | 2004-10-07 |
United States Patent
Application |
20040195252 |
Kind Code |
A1 |
von Holdt, John W. SR. ; et
al. |
October 7, 2004 |
Plastic bucket and lid
Abstract
A plastic bucket includes at least one undercut adjacent an
upper end of the bucket defined by a bucket wall which extends
upwardly and inwardly along a diagonal path. An annular, vertical
section may be provided at the upper end of the diagonal path.
Above the vertical section, the bucket wall extends radially
outwardly to create an annular, horizontal flange. In addition, an
uppermost annular rim may extend upwardly from the horizontal
flange and be located approximately midway between inner and outer
radii of the flange.
Inventors: |
von Holdt, John W. SR.;
(Niles, IL) ; von Holdt, John W. JR.; (Glenview,
IL) |
Correspondence
Address: |
BANNER & WITCOFF, LTD.
TEN SOUTH WACKER DRIVE
SUITE 3000
CHICAGO
IL
60606
US
|
Family ID: |
27792394 |
Appl. No.: |
10/825497 |
Filed: |
April 15, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10825497 |
Apr 15, 2004 |
|
|
|
10002346 |
Oct 25, 2001 |
|
|
|
10002346 |
Oct 25, 2001 |
|
|
|
09590227 |
Jun 8, 2000 |
|
|
|
09590227 |
Jun 8, 2000 |
|
|
|
09106485 |
Jun 29, 1998 |
|
|
|
6098833 |
|
|
|
|
09106485 |
Jun 29, 1998 |
|
|
|
08823193 |
Mar 24, 1997 |
|
|
|
5913446 |
|
|
|
|
08823193 |
Mar 24, 1997 |
|
|
|
08798511 |
Feb 10, 1997 |
|
|
|
08798511 |
Feb 10, 1997 |
|
|
|
08707746 |
Sep 4, 1996 |
|
|
|
08707746 |
Sep 4, 1996 |
|
|
|
08262916 |
Jun 21, 1994 |
|
|
|
Current U.S.
Class: |
220/659 |
Current CPC
Class: |
B65D 2401/25 20200501;
B65D 2543/00629 20130101; B65D 2543/00509 20130101; B65D 1/46
20130101; B65D 2543/00796 20130101; B65D 2543/00296 20130101; B65D
2543/00092 20130101; B65D 2543/00555 20130101; B65D 1/12 20130101;
B65D 43/0256 20130101; B65D 2543/0074 20130101; B65D 2543/00685
20130101; B65D 2543/00537 20130101 |
Class at
Publication: |
220/659 |
International
Class: |
B65D 025/28 |
Claims
What is claimed is:
1. An integrally molded plastic bucket having an upright, annular
bucket wall terminating in an annular lip to form an open bucket
mouth with a single annular undercut located adjacent the mouth at
the upper end of said bucket, said lip defined by a first upwardly
and radially inwardly extending wall section along a diagonal path,
a second wall section extending vertically upwardly from the first
section and a third wall section extending horizontally radially
outwardly from the second section, the improvement comprising, in
combination: first and second integrally molded pairs of spaced
ribs, each rib connecting respectively the third section of the lip
to the bucket wall or the first section of the lip, each pair of
ribs having opposed, laterally spaced edges, each pair of ribs also
spaced from the second section, each pair of ribs positioned on
opposite sides of the bucket mouth to provide first and second
handle cages; and an integrally molded handle, said handle
including a disc positioned between each pair of ribs in the
undercut, and fragible sprue connection from the first or second
wall section positioned in opposed relation to the space between at
least one pair of ribs, said handle section including at least one
handle retention disc connected to the sprue connection and said
handle further including a rod section connecting the discs.
2. The bucket and handle of claim 1 or claim 11 wherein the rod
section includes laterally projecting wings positioned intermediate
the opposite ends thereof.
3. The improvement of claim 1 wherein the ribs connect the third
wall section directly to the bucket wall.
4. The improvement of claim 1 including an upwardly extending
annular rim from the third wall.
5. The improvement of claim 1 or claim 11 wherein the first wall
has a thickness greater than the thickness of the bucket wall.
6. The improvement of claim 1 or claim 11 including a sprue
connection to each end of the handle.
7. The improvement of claim 1 or claim 11 wherein no ribs or rings
are formed on the container wall in the area of said undercut.
8. The improvement of claim 1 or claim 11 wherein the ribs forming
each cage include a vertical run.
9. The improvement of claim 1 wherein the ribs connect the third
wall section directly to the first wall section.
10. The improvement of claim 1 or claim 11 wherein the ribs forming
each cage include a vertical run with an inside surface opposing
one of said discs and each disc includes a bearing surface face
opposing the inside face of one of said cages.
11. In an integrally molded plastic bucket having an upright,
annular bucket wall terminating in an annular lip to form an open
bucket mouth with a single annular undercut located adjacent the
upper mouth at the end of said bucket, said lip defined by a first
upwardly and radially inwardly extending wall section along a
diagonal path and a second wall section extending horizontally
radially outwardly from the first wall section, the improvement
comprising, in combination: first and second integrally molded
pairs of spaced ribs, each rib connecting respectively the second
section of the lip to the bucket wall or the first section of the
lip, each pair of ribs having opposed, laterally spaced edges, each
pair of ribs also spaced from the first wall section, each pair of
ribs positioned on opposite sides of the bucket mouth to provide
first and second handle cages; and an integrally molded handle,
said handle including a disc positioned between each pair of ribs
and in the undercut, and a fragible sprue connection from the first
wall section positioned in opposed relation to the space between at
least one pair of ribs, said handle section including at least one
handle retention disc connected to the sprue connection and said
handle further including a rod section connecting the discs.
12. The improvement of claim 11 wherein the ribs connect the second
wall directly to the bucket wall.
13. The improvement of claim 11 including an upwardly extending
annular rim from the second wall.
14. The improvement of claim 11 wherein the ribs connect the second
wall section directly to the first wall section.
Description
CROSS RELATION TO RELATED APPLICATIONS
[0001] I This application is a continuation-in-part of Ser. No.
10/002,346 filed Oct. 25, 2001, pending; which is a continuation of
Ser. No. 09/590,227 filed Jun. 8, 2000, now abandoned; which is a
continuation of Ser. No. 09/106,485 filed Jun. 29, 1998, now U.S.
Pat. No. 6,098,833; which is a continuation of Ser. No. 08/823,193
filed Mar. 24, 1997, now U.S. Pat. No. 5,913,446; which is a
continuation in part of Ser. No. 08/798,511 filed Feb. 10, 1997,
abandoned; which is a continuation in part of Ser. No. 08/707,746
filed Sep. 4, 1996, abandoned; which is a continuation in part of
Ser. No. 08/262,916 filed Jun. 21, 1994, abandoned.
BACKGROUND OF THE INVENTION
[0002] Many designs of plastic buckets and lids are well-known, see
for example the following patents of John W. Von Holdt: U.S. Pat.
Nos. 4,375,948; 4,574,974; 4,512,494; 4,512,493; 4,452,382;
4,380,305; 4,308,970; and 4,210,258.
[0003] Many containers, such as cans for food, paint and other
solvents and chemicals have also been made of plastic, as shown in
the above-cited patents. However, plastic buckets of course lack
the strength of metal buckets, so that in many cases special
designs of the plastic buckets must be used to obtain, for example,
a desired level of hoop strength about the mouth of the plastic
bucket. This hoop strength is achievable in the prior art by
reinforcement in some manner of the mouth area of the plastic
bucket, typically involving an annular portion that projects
radially inwardly, which reinforces the bucket.
[0004] However, buckets of this design typically require a
collapsible core for their molding, which adds capital and
operating expense to the operation, and also tends to slow the
operation down. Likewise, collapsible cores are subject to failure
and other problems, which further slows the efficiency of the
operation.
[0005] In accordance with this invention, a plastic bucket is
provided which does not require manufacture by the use of a
collapsible core. At the same time, the bucket has a desired amount
of hoop strength, even a plastic bucket which is of the shape of a
conventional metal paint can.
DESCRIPTION OF THE INVENTION
[0006] By this invention, a plastic bucket defines an annular lip
and an attachable plastic lid. The lid defines a peripheral, outer
annular wall which defines an outer wall of an annular recess of
the lid. The bucket lip occupies the recess in locked, sealed
relation with the lid.
[0007] A principal object of the present invention is to provide a
unique design for the upper end of a plastic container comprising
an annular undercut section, an annular vertical wall portion above
the undercut section, an annular horizontal ledge above the annular
vertical wall, and an upright annular rim at the uppermost end of
the bucket which rim is positioned approximately centrally with
respect to the annular horizontal ledge.
[0008] In a preferred embodiment, the foregoing bucket is provided
with only a single undercut section which facilitates its molding
and permits it to be molded without use of a collapsible mold core,
preferably by using a mold of the type described in my U.S. Pat.
No. 4,375,948.
[0009] The foregoing novel bucket design has been proven by
extensive testing to afford surprisingly improved hoop strength and
stacking strength. Such improved strength characteristics are so
significant that it is possible with such a bucket design to
eliminate all external ribs or rings which are commonly used to
provide hoop strength such as shown in Holt U.S. Pat. No. 3,977,563
and Letica U.S. Pat. No. 4,349,119. The eliminating of all such
external ribs and or rings, as well as the elimination of any
internal ribs, provides an exceptionally clean and simple design
which is easy to mold and offers numerous advantages to the users
of such plastic buckets.
[0010] The present invention is not limited to the use of a single
undercut, but for most applications that is the preferred
embodiment. It is definitely preferred to mold the foregoing bucket
without use of a collapsible mold core, and my preferred mold is of
the type shown in my U.S. Pat. No. 4,375,948, but other molds may
possibly be used in certain applications.
[0011] The invention is also not limited to a design which has no
external or internal ribs, but my preferred embodiment has no
external ribs and preferably has no internal ribs because my unique
bucket design provides the desired hoop strength and stacking
strength without the need for the increased strength which such
ribs commonly provide. Nevertheless, certain alternative
embodiments which employ external or internal ribs will be
described herein.
DESCRIPTION OF THE DRAWINGS
[0012] Referring to the drawings,
[0013] FIG. 1 is a perspective view of a molded bucket and attached
lid in accordance with this invention;
[0014] FIG. 2 is an enlarged, fragmentary, transverse sectional
view through the bucket lip and the periphery of the lid of the
bucket, taken along line 2-2 of FIG. 1;
[0015] FIG. 3 is an enlarged, fragmentary, elevational view of the
lid and upper portion of the bucket of FIG. 1, showing a portion of
a tear strip;
[0016] FIG. 4 is a fragmentary, enlarged, longitudinal sectional
view of another embodiment of a bucket and lid;
[0017] FIG. 5 is a fragmentary, enlarged, elevational view of a
portion of the bucket of FIG. 4;
[0018] FIG. 6 is a vertical sectional view taken along the line 6-6
of FIG. 8 showing an alternative embodiment of the invention where
a single undercut is provided at the upper end of the container and
a plurality of internal reinforcing ribs are formed in the area of
the undercut but no external ribs are provided as in the earlier
embodiments;
[0019] FIG. 7 is an enlarged fragmentary view showing the upper end
of the container of FIG. 6;
[0020] FIG. 8 is a view looking upwardly along the line 8-8 of FIG.
7 showing a plurality of internal ribs spaced around the interior
wall of the container near the upper end thereof;
[0021] FIG. 9 is a fragmentary vertical section showing another
alternative embodiment of the invention having a single undercut at
the upper end and having an offset at the upper end of the undercut
as shown in the embodiment of FIG. 4, there being provided internal
ribs in the area of the undercut as in the embodiment of FIGS. 6-8
without the use of any external ribs in the undercut area, and
there being shown one of two bale ears for holding a molded
handle;
[0022] FIGS. 10 and 11 are top and side elevational views of a
bucket of the type generally described herein but showing the
addition of a plastic handle which is molded during the molding
operation to mold the bucket;
[0023] FIG. 12 is a fragmentary vertical section showing a
preferred embodiment of the present invention which is similar to
the embodiment of FIG. 4 and also to the embodiment of FIG. 9 but
it has no external or internal ribs because the bucket design
affords the necessary strength without such ribs;
[0024] FIG. 13 is a fragmentary perspective view showing an
interruption or slot formed in the radially outer portion of the
horizontal flange formed beneath the uppermost rim of the
bucket;
[0025] FIG. 14 is a fragmentary vertical section taken along the
line A--A of FIG. 13;
[0026] FIG. 15 is a side cross sectional view of the handle
construction depicted in FIG. 11 taken substantially along the line
15-15; and
[0027] FIG. 16 is an enlarged elevation of the handle construction
of FIGS. 15 and 11 as viewed in the direction of the arrow in FIG.
15.
[0028] Now, in order to acquaint those skilled in the art with the
manner of making and using my invention, I shall describe, in
conjunction with the accompanying drawings, certain preferred
embodiments of the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0029] Referring to FIGS. 1-3, a plastic bucket 10 having an
attached lid 12 is shown, each of the lid and bucket being
manufactured by injection molding from known plastic
compositions.
[0030] Bucket 10 is shown to comprise an annular lip 14 which
defines the bucket mouth across which lid 12 extends. Lid 12, in
turn, defines a peripheral, outer annular wall 16 which, with
annular, inner lid wall 18 and annular bridging wall 20, defines an
annular recess which is occupied by bucket lip 14 in locked, sealed
relation with lid 12.
[0031] Outer, annular lid wall 16 also defines a circumferential
tear strip 22, which extends almost completely about the
circumference of lid wall 16 or being continuous about that wall,
terminating at one end with a free handle 24 which is partly
surrounded by a space 26, so that handle 24 may be grasped and
pulled to cause circumferential tearing of the circumferential tear
line 28. Upon removal of tear strip 22, the remainder of outer wall
16 may be pried outwardly with relative ease for opening of the
lid.
[0032] Inwardly extending projections 30 are provided in known
manner, being intermittently spaced about the periphery of lid wall
16 or being continuous about that wall to engage the undersurface
of bucket lip 14, as shown in FIG. 2.
[0033] Thus, after removal of tear strip 22, the bucket lid is
readily opened and reclosed as desired.
[0034] Additionally, bucket 10 defines a plurality of outwardly and
diagonally extending ribs 32, which are an integrally molded part
of the bucket 10 and which intersect each other in criss-cross
relation. These ribs are positioned entirely around the periphery
of bucket 10, and serve to increase the hoop strength of the
bucket.
[0035] Also, bucket 10 is shown to define three outwardly
extending, integral rings 34 which intersect the diagonal ribs 32,
and thus also contribute to improving the bucket's hoop strength in
the vicinity of the bucket lip.
[0036] Thus, buckets 10 can be molded which, although made of
plastic, can have hoop strength that is comparable with metal
buckets, yet which are better than metal buckets in their
resistance to pop off of the lid, when the bucket is dropped and
the like. Appropriate fins or vanes 36 may be provided to
strengthen lid 12 as may be desired. Also, internal fins or vanes
38 may be provided to bucket 10 for a similar strengthening
purpose.
[0037] Also, it can be seen that bucket 10 defines only one
annular, diagonal undercut 39, so that rings 34 may be provided
without exceeding the main diameter of the bucket. This permits the
use of such a bucket in conventional filling machinery and the
like. Also, such a bucket, in which the inward extent of the
undercut 39 is no more than about one-quarter inch, or not over 6%
of the bucket diameter can be manufactured with a mold core which
is not collapsible, such as the mold shown in U.S. Pat. No.
4,375,948. The bucket of preferred designs as shown can be popped
off of the mold core.
[0038] Referring to FIGS. 4 and 5, a molded bucket 10a carries a
lid 12a which is of generally similar design to the previous
embodiment except as otherwise shown herein.
[0039] As before, lid 12a defines an outer annular wall 16a which,
in conjunction with inner annular wall 18a and annular bridging
wall 20a, defines an annular recess for the securance of bucket lip
14a.
[0040] In this particular embodiment, bucket lip 14a is carried
upon a flange 40 which extends outwardly and is carried by the
bucket. Flange 40 defines an annular recess 42 in which the lower
edge 44 of outer, annular lid wall 16a is "buried", to prevent one
who desires to open the container from prying the lid 12a off of
the bucket with a screw driver or the like. Thus, lid 12a is
permanently attached to bucket 10a until the removal of tear strip
22a is accomplished.
[0041] Tear strip 22a may be of similar design to tear strip 22 of
the previous embodiment. When it has been circumferentially removed
by tearing along tear line 28a in similar manner, the remaining
portion of outer, annular wall 16a is easily removed either with
the fingers or a screw driver. Inwardly extending projection 30a
may be continuous and annular, or it may be intermittent along the
circumference for easier opening of lid 12a.
[0042] A single undercut 39a is provided in bucket 12a also,
similar to the previous embodiment. This provides a recess in which
diagonal vanes or ribs 46 may be provided, extending in a diagonal,
criss-cross manner as illustrated by FIG. 5. This provides
significantly increased hoop strength to bucket 12a. Also, a label
48 may be placed over the criss-cross ribs 46 if desired by
automatic label applying machinery.
[0043] The resulting container is tamper proof because of the
required use of tear strip 22a to open it, and exhibits a high hoop
strength for avoiding inadvertent lid pop off when the container is
dropped or the like.
[0044] Reference is now made to the embodiment of FIGS. 6-8 where a
bucket or container 100 has a container wall 102 which slopes
inwardly at its upper end as best shown at 103 in FIG. 7 to provide
a single undercut area shown at 104. In this embodiment, no
external ribs are formed in the undercut area 104, but internal
ribs are provided as shown at 106. FIG. 8 shows the internal ribs
106 as being generally radial and spaced around the entire inside
circumference of the upper end of the bucket or container.
[0045] The upper end of the container 100 differs from the
container shown in FIG. 2 because it has an offset in the container
wall above the single undercut, generally as shown in FIG. 4. Thus,
referring to FIG. 7, the container wall 102 slopes inwardly at 103
to form the offset 104 and then extends upwardly again at 108 and
then outwardly to form an offset 110. Finally, the container wall
extends upwardly again at 112 to define the open mouth of the
container. The offset 110 provides an advantage in that it affords
increased hoop strength for the upper end of the container.
[0046] In order to facilitate the molding of a plastic bucket in
accordance with the present invention, and avoid the need for a
collapsible mold core, it is necessary to limit the magnitude of
the undercut such as shown, for example, at 104 in FIG. 7 or at
104' in FIG. 9, i.e., the amount that the wall shown at 108 in FIG.
7 is radially offset from the wall shown at 102. The deeper the
offset, the more difficult it is to mold a bucket without use of a
collapsible mold core.
[0047] Generally speaking, the magnitude of the undercut should not
exceed approximately 5% or 6% of the diameter of the container. For
example, with a larger container having a diameter of 12 inches, it
is preferable that the undercut not extend inwardly more than about
{fraction (3/4)} inch. However, for a smaller container, the
undercut may comprise a larger percentage of the diameter. For
example, with a container having a 2 inch diameter, it is
preferable that the undercut not extend inwardly more than
{fraction (3/8)} inch.
[0048] For most containers, it is preferred that the undercut not
exceed 3/8 of an inch, but for containers of larger size, such as
12 inch diameter, the undercut may extend inwardly as much as
{fraction (3/4)} inch. The critically important advantage of the
use of an undercut in the present invention is that by using only a
single undercut, and controlling the magnitude of the undercut, it
is possible to mold the container without use of a collapsible mold
core.
[0049] Reference is now made to FIG. 9 which shows an embodiment
similar to the embodiment of FIGS. 6-8 with corresponding
components identified with corresponding primed numerals. In FIG.
9, the container wall 102' slopes inwardly at 103' and then
upwardly at 108', and it then extends outwardly again at 110' to
form an offset for added hoop strength as in the prior embodiment.
The single undercut 104' has no external ribs, but internal ribs
are provided at 106' as in the embodiment of FIGS. 6-8. The
vertical wall portion 108' is somewhat longer than in the
embodiment of FIGS. 6-8. In addition, FIG. 9 shows one of two
opposed bale ears 122 which serve for mounting a handle as will be
described below. A similar bale ear is shown at 124 in FIG. 6, the
opposite one not being shown in FIG. 6 due to the section line 6-6
in FIG. 8.
[0050] FIGS. 10 and 11 show a further embodiment of a container
including a handle 130 which is pivotally connected to opposite
sides of the bucket as shown at 132. The bucket shown at 134 is
similar to the external rib embodiments described earlier herein,
the principal difference being the addition of the handle 130 which
can be molded during the molding of the bucket 134. A molding
process for manufacture of an integral handle and bucket is
suggested in U.S. Pat. No. 4,632,357 which is incorporated herewith
by reference. Applicant has devised a construction which enables
utilization of the process of Patent No. 4,632,357 with a bucket
design as set forth herein and, more particularly, in a preferred
embodiment comprising the design of FIG. 12.
[0051] Specifically, the handle 130 is integrally molded in
combination with the bucket 134 and then separated from the bucket
wall by turning the handle from side to side. Integral molding of
the component parts is enabled by virtue of the arrangement of the
mold wherein a sprue connection is effected between the bucket 134
and the handle 130. More specifically, referring to FIG. 15 as well
as FIGS. 11 and 16, there is molded integrally with the bucket 134
a first set of parallel ribs 400 and 402 on one side of bucket 134
and a second set 401, 403 on the opposite side of bucket 134. Ribs
400, 402 are separated from one another and define a space between
opposed edges 404 and 406. The ribs 400 and 402 are molded
integrally with the bucket 134 in the form as depicted in FIG. 15
in cross section. Thus, each of the ribs 400, 402 includes an
outward extending generally horizontal run or section 408, a
depending run or generally vertical section 410, and a connective
run or generally horizontal section 412 such that there is a space
between the depending vertical sections 410 and the side 414 of the
bucket 134. The ribs 400, 402 form a means for holding the handle
130 in contact with and connection to the bucket 134.
[0052] The ribs 400, 402 incorporate features of the preferred
embodiment as described with respect to FIG. 12 hereinafter. Thus
an annular flange 206 serves as run 408 or is extended optionally
as run 408 and connects with generally vertical or depending run
410. Depending run 410 is opposed to the annular notch formed in
the outside bucket wall 200 by inwardly angled wall 202 which
connects with vertical annular wall or hoop 204 that, in turn,
connects with horizontal flange 206. Connective run 412 then
attaches to bucket or container wall 200 or angled wall 202. In
this manner the annular recess defined by the serially connected
wall sections 200, 202, 204, 206 serves to protect the handle
connection and maintain the handle connection dimensionally within
the diameter of the container wall 200. This feature enables
maintaining of close side by side packing and display of containers
and also avoids the necessity of extra flanges and ribs to effect
creation of an integrally molded attached handle.
[0053] The handle 130 is integrally molded at the time the bucket
is molded by virtue of a plastic sprue connection 420 which
connects from the bucket molding chamber to a plastic flow
connection of the mold form for the handle 130. Thus, the sprue
connection 420 comprises a fragible molded section of the handle
130. Further, there is a molded, lead-in section 422 of the rod
forming the handle 130. A disc 424 is also integrally molded so as
to be formed on the inside of the ribs 400 and 402 between vertical
sections 410 and bucket wall 414. The handle 130 further includes
an elongate rod section 426 which extends between a disc 424
located behind one pair of ribs 400, 402 on one side of the bucket
134 to a disc 424 located behind a second pair of ribs 401, 403 on
the opposite side of the bucket 134. Intermediate the connecting
rod section 426 is a central grip section 428 which includes
laterally projecting ribs or wings 430 and 432.
[0054] The sprue connection 420 is provided with respect to one or
both sides of the bucket 134. Thus, when molding the bucket 134 by
injection molding, for example, molded plastic material is provided
for integral molding and simultaneous molding of the plastic bucket
134 as well as the handle construction 130 described. The sprue
connection 420 is fragible. Thus, twisting of the handle after
molding effects breaking of the sprue connection 420 and detachment
of lead-in section 422 from the bucket 134. The retention disc
member 424 retains the handle 130 in position between the ribs 400,
402 and 401, 403, as the case may be. As a result of the aforesaid
construction and the associated mold, a unitary molded plastic
bucket 134 and handle 130 may be provided.
[0055] Reference is again made to the embodiment of FIGS. 1-3, and
the embodiment of FIGS. 4-5. It should be understood that while the
radially inwardly projecting ribs 38 are shown only in FIG. 2 which
is part of the embodiment of FIGS. 1-3, the description of the
embodiment of FIGS. 4-5 indicates that the same features of the
embodiment of FIGS. 1-3 are included except as otherwise described,
so the intent is that the embodiment of FIGS. 4-5 may include the
internal radially inwardly projecting ribs shown at 38 in FIG.
2.
[0056] Reference is now made to FIG. 12, which shows a preferred
embodiment of the present invention. In FIG. 12, the upright
container wall 200 slopes inwardly at 202 and then upwardly at 204,
and it then extends outwardly again at 206 to form a horizontal,
annular flange which together with vertical section 204 affords
very substantial hoop strength and stacking strength. An uppermost
annular, vertical rim 208, designed to cooperate with a lid (not
shown) as generally shown in FIG. 2, extends up from horizontal,
annular ledge 206 from a radius which is approximately midway
between the inner and outer radii of the horizontal ledge 206.
[0057] FIG. 12 shows the uppermost, annular rim 208 being
positioned approximately midway between the inner and outer radii
of the horizontal, annular flange 206. The foregoing approximate
location of rim 208 relative to horizontal flange 206 is desirable
in many applications. However, there is a further consideration
which is that for optimum strength characteristics it has been
found desirable to locate the uppermost rim 208 so that the
radially inner wall of rim 208 is not radially inwardly of the
radially outer wall of vertical section 204. As shown in FIG. 12,
the radially inner wall of uppermost rim 208 is slightly radially
outwardly of the radially outer wall of vertical section 204, which
has proved to be a desirable relative position for uppermost rim
208. Thus, while the rim 208 may be located radially inwardly from
the position shown in FIG. 12, it preferably should not be located
so its radially inside wall is radially inwardly of the outside of
upright wall 204.
[0058] There are no outer ribs located in the section defined by
the undercut 202, as for example, in the embodiment of FIG. 2.
Also, there are no internal ribs radially inwardly of the undercut
wall 202 as in the embodiment of FIG. 2 or the embodiment of FIG.
9. The preferred design shown in FIG. 12 is free of external and
internal ribs. As explained previously, the design of the bucket
comprising undercut 202, vertical section 204, horizontal flange
206 and upper, vertical rim 208 provides unexpected strength
sufficient so that additional strength which the ribs afford is not
needed.
[0059] While the present invention is not limited to a bucket
having no external or internal ribs, the design shown in FIG. 12
which has no ribs is the preferred embodiment because it affords a
clean and simple design which is easy to mold and which is
extremely advantageous for certain applications such as for a
one-gallon plastic paint can. The preferred embodiment shown in
FIG. 12 has only a single undercut, which makes the bucket easier
to mold without using a collapsible mold core, but the present
invention may also be used with a bucket which has more than one
undercut.
[0060] It is highly desirable that the angle of the undercut wall
202, i.e., the angle the wall defines with the vertical, be
controlled so as not to exceed 45 degrees. If the foregoing angle
exceeds approximately 45 degrees, it may not be possible to mold
the bucket without using a collapsible mold core, especially if
more than one undercut is used as in Letica U.S. Pat. No.
4,349,119. The angle for the wall 202 is approximately 30 degrees,
as shown in FIG. 12, and a preferred range for such angle is
between approximately 30 degrees and 45 degrees. However,
satisfactory results may be obtained using an angle in the range of
20 degrees to 50 degrees.
[0061] I prefer a range of 30 degrees to 45 degrees for the angle
which diagonal wall 202 defines with a vertical. A smaller angle
can have disadvantages because if you wish to maintain the depth of
the undercut, a smaller angle means that the vertical height
component of the diagonal wall 202 will be greater, and in that
case the upright bucket wall 200 will have less height. Since the
upright wall 200 is often used for carrying a label, it may be a
disadvantage in some applications to reduce its height
significantly from what is shown in FIG. 12.
[0062] The general purpose of the undercut is to produce hoop
strength, and the vertical section 204 combined with the horizontal
flange 206 affords exceptional hoop strength to a degree which
permits elimination of external and internal ribs. As a result, if
one were to reduce the angle which diagonal wall 202 makes with a
vertical, one would in most cases not want to significantly reduce
the depth of the undercut shown in FIG. 12, and because in many
applications it is not desirable to substantially increase the
vertical height component of the diagonal wall 202, it is preferred
in such applications to avoid reducing the angle between diagonal
wall 202 and a vertical to much less than 30 degrees.
[0063] The combination of the undercut 202, upright or vertical,
annular section 204, horizontal, annular ledge 206, and uppermost,
annular rim 208 located approximately midway between the inner and
outer radii of ledge 206, affords surprisingly increased hoop
strength and stacking strength. FIG. 12 has the actual dimensions
of the bucket wall shown in inches. The dimensions shown are for a
one-gallon plastic bucket and will change for larger and smaller
buckets. While the invention is clearly not limited to particular
dimensions, the relative positioning and relative dimensions of the
structural components 202, 204, 206 and 208 are important, and the
particular design shown in FIG. 12 is considered a particularly
advantageous arrangement.
[0064] While no lid is shown in conjunction with the preferred
embodiment of FIG. 12, a lid of the general type including a tear
strip as shown in FIG. 4 may be used, although it is not necessary
that the lower edge of the lid wall be buried in the manner shown
in FIG. 4.
[0065] FIGS. 13 and 14 show an interruption or slot formed at 220
in the radially outer portion of annular, horizontal flange 206.
While such slot 220 will create a small amount of weakness, it
serves the purpose of providing room for someone to insert their
fingers beneath the outer wall of a lid for the purpose of removing
the lid. Accordingly, for many applications the minor reduction in
strength caused by the slot at 220 in the horizontal flange 206 is
acceptable in order to facilitate manual removal of a lid.
[0066] Another feature shown in FIG. 12 concerns the thickness of
the diagonal wall 202 and the vertical wall 204 compared to the
outermost bucket wall 200. As shown in FIG. 12, both the diagonal
wall 202 and the upright wall 204 are somewhat thicker than the
main bucket wall 200. The reason for increasing the wall thickness
of walls 202 and 204 is because the offset created by diagonal wall
202, while designed to increase hoop strength, will reduce stacking
strength. As a result, when such an offset is used to create a
substantial undercut, it is preferable that the wall 202, and in
some cases also the wall 204, be made of increased thickness
compared to main bucket wall 200 for the purpose of maintaining
stacking strength. In the foregoing manner, excellent hoop strength
and stacking strength may be obtained.
[0067] There are prior art patents which teach designs for plastic
buckets and which provide various structure for the purpose of
affording hoop strength and stacking strength. However, such prior
art patents do not teach the present invention and fall far short
of providing the advantages of the present invention, especially
with respect to the preferred embodiment shown in FIG. 12.
[0068] Letica U.S. Pat. No. 4,349,119 in FIG. 5 shows a bucket
design having a double undercut, one undercut being shown at 75 and
a second undercut being shown at 106. The second undercut shown at
106 makes molding more difficult, especially since the angle from
the vertical appears to exceed 45 degrees, and the Letica structure
is made commercially from a collapsible mold core.
[0069] In addition, Letica shows a plurality of external rings or
ribs 68, and generally the upper end of the Letica bucket differs
markedly from the present invention, as can readily be seen by
comparing FIG. 5 of Letica with FIG. 12 of the present
invention.
[0070] Buc U.S. Pat. No. 4,524,882 shows a bucket design in FIG. 4
having a single undercut at 15 and a so-called bridge member 18
which presumably provides hoop strength. However, the Buc design
fails to include any structure resembling the upright or vertical,
annular section shown at 204 in FIG. 12 of the present invention
which is located intermediate the undercut wall 202 and the
horizontal, annular ledge 206, and which contributes in a major way
to the hoop strength and stacking strength of the design shown in
FIG. 12. In FIG. 12, the combination of sections 204 and 206
provides an annular L-shaped structure which offers unexpected
advantages with respect to hoop strength.
[0071] In addition, the extreme upper end of the Buc bucket is
quite different from the FIG. 12 design since it provides upright
rim portions at the radially inner and outer edges of member 18 as
opposed to the FIG. 12 design where a single annular rim 208 is
approximately midway between the radially inner and outer portions
of horizontal, annular ledge 206. Also, the Buc patent is merely a
paper patent, and the design shown therein has never been used
commercially.
[0072] One further prior art patent is Holt U.S. Pat. No.
3,997,563. FIG. 1 of Holt appears to show an undercut, although
that structure is not shown in the other drawings. The upper end of
the Holt bucket is entirely different from the design shown in FIG.
12 of the present invention and it comprises in essence an upright
annular wall 10 with two annular rings or ribs 18 on the outside,
and an uppermost rim which extends up from the radially inner edge
of the ring 18. There is little if any similarity between the Holt
design and the FIG. 12 design of the present invention.
* * * * *