U.S. patent application number 09/734437 was filed with the patent office on 2002-06-13 for moulded plastic bulk container.
Invention is credited to Elvin-Jensen, Gavin J., Elvin-Jensen, Marc P..
Application Number | 20020070223 09/734437 |
Document ID | / |
Family ID | 24951696 |
Filed Date | 2002-06-13 |
United States Patent
Application |
20020070223 |
Kind Code |
A1 |
Elvin-Jensen, Marc P. ; et
al. |
June 13, 2002 |
Moulded plastic bulk container
Abstract
A molded plastic bulk container for the storage, transport and
handling of large quantities of bulk material such as fruit. The
container includes: (a) a base which may be internally concave; (b)
a number of walls, for example four, extending upwardly from the
base, wherein at least one, and preferably all, of the walls is
adapted to have an internally concave configuration under a neutral
load, i.e. when the container is empty.
Inventors: |
Elvin-Jensen, Marc P.;
(Allambie Heights, NSW, AU) ; Elvin-Jensen, Gavin J.;
(Noordhoeck, ZA) |
Correspondence
Address: |
TESTA, HURWITZ & THIBEAULT, LLP
HIGH STREET TOWER
125 HIGH STREET
BOSTON
MA
02110
US
|
Family ID: |
24951696 |
Appl. No.: |
09/734437 |
Filed: |
December 11, 2000 |
Current U.S.
Class: |
220/669 ;
220/675 |
Current CPC
Class: |
B65D 2519/00288
20130101; B65D 2519/00333 20130101; B65D 2519/0097 20130101; B65D
2519/00243 20130101; B65D 2519/00318 20130101; B65D 2519/00557
20130101; B65D 2519/00268 20130101; B65D 2519/00626 20130101; B65D
2519/00407 20130101; B65D 2519/0096 20130101; B65D 2519/00069
20130101; B65D 2519/00034 20130101; B65D 2519/00174 20130101; B65D
2519/00412 20130101; B65D 11/10 20130101; B65D 2519/00497 20130101;
B65D 21/0215 20130101; B65D 19/04 20130101; B65D 11/22
20130101 |
Class at
Publication: |
220/669 ;
220/675 |
International
Class: |
B65D 008/04; B65D
008/06 |
Claims
1. A molded plastic bulk container including (a) a base; (b) walls
extending upwardly from the base, wherein at least one of the walls
is adapted to have an internally concave configuration under a
neutral load.
2. The container claimed in claim 1, wherein the base has an
internally concave configuration under a neutral load.
3. The container claimed in claim 1, wherein the base is inclined
radially upwardly from its center towards a lower edge of each of
the walls.
4. The container claimed in claim 1, wherein the base includes
reinforcing ribs.
5. The container claimed in claim 1, wherein the at least one wall
includes a lateral ledge substantially along the top of the at
least one wall.
6. The container claimed in claim 1, wherein the container includes
four walls, each pair of adjacent walls separated by a corner
post.
7. The container claimed in claim 6, wherein the corner posts have
a hollow configuration.
8. The container claimed in claim 6, wherein the corner posts have
a substantially cylindrical configuration.
9. The container claimed in claim 6, wherein the corner posts have
a substantially constant cross section substantially along their
length.
10. The container claimed in claim 1, wherein the container is
stackable.
11. The container claimed in claim 6, wherein each corner post
includes a foot which is configured to sit on the top surface of a
corresponding corner post of a similar or identical vertically
adjacent container.
12. The container claimed in claim 1, wherein the at least one wall
includes no reinforcing ribs on the majority of its surface.
13. The container claimed in claim 1, wherein the at least one wall
includes no reinforcing ribs on its surface.
14. The container claimed in claim 1, wherein the at least one wall
is adapted to permit minimal flexing under a normal load.
15. The container claimed in claim 1, wherein the at least one wall
is adapted to be substantially rigid under a normal load.
16. The container claimed in claim 1, wherein the thickness of the
at least one wall is in the range 3 mm to 6 mm.
17. The container claimed in claim 3, wherein four planes extending
between the external surfaces of each pair of corner posts define
the boundaries of the cubed volume of the container and whereby the
external surfaces of the walls and the base do not extend beyond
the boundaries of the cubed volume of the container.
18. The container claimed in claim 6, wherein each of the four
walls hits an internally concave configuration.
19. The container claimed in claim 6, wherein the base and each of
the four walls have an internally concave configuration.
20. The container claimed in claim 1, wherein the container further
includes a planar lid.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates to a plastic container for storage,
transport and general handling of large quantities of bulk material
such as food products, including fruit.
BACKGROUND OF THE INVENTION
[0002] It is recognized that a primary aim of bulk containers is to
provide the most efficient ratio between the internal volume and
the cubed external volume ("the volume ratio"). According to
conventional wisdom, this is achieved with a container having
straight, planar sides and being of a square or rectangular
configuration. In smaller containers this is found to be an
effective design capable of achieving the stated aim.
[0003] However, in larger containers of the type considered in the
present case there is a need to resist the tendency of the
container's support surfaces to bow outwards under the considerable
load placed thereon. It has been generally considered that if the
walls and floor were to be permitted to bow outwardly then the
external dimensions of the container required to be maintained
within strict tolerances would be at variance with generally
accepted standards. This would inevitably lead to space problems in
storage, transport and general handling.
[0004] The most common method employed to address this problem is
to reinforce the walls and floor of the container with struts and
ribs which are effective to maintain the planar configuration of
the surfaces. These ribs are made of considerable thickness (e.g.,
about 40 mm) adequate to further impart sufficient rigidity to
resist the distortive forces of the load. Consequently, known
plastic containers have traditionally been made with deep
reinforcing ribs and walls and floors of considerable thickness to
resist the tendency to bulge. As space is taken up by the ribs the
resultant container has a volume ratio which is reduced relative to
the potential volume ratio if it was possible to overcome the
problem of bulging.
SUMMARY OF THE INVENTION
[0005] It is an object of the present invention to ameliorate the
aforementioned disadvantages of the prior art or at least provide a
useful alternative thereto.
[0006] Accordingly in one aspect of the invention there is provided
a molded plastic bulk container including:
[0007] (a) a base; and
[0008] (b) walls extending upwardly from the base,
[0009] wherein at least one of the base or one of the walls is
adapted to have an outwardly curved configuration under a neutral
load.
[0010] In line with conventional bulk containers, the container may
comprise a base with four walls and, optionally, a lid. The walls
may have equal dimensions. Where the container has four walls, a
first pair of opposing walls may have different dimensions compared
to a second pair of opposing walls. The first pair of opposing side
walls may be longer, higher or thicker than the second pair of
opposing side walls.
[0011] The container may be formed as a unitary structure. The
container may be made up of two or more separately formed
components. The separately formed components may be later affixed
together to form the container. The components may be attached by
sonics, heat or friction welding or press-fitting.
[0012] Preferably the container is integrally formed in a single
molding process. The container may be made using a variety of
plastics possessing the necessary properties of strength, abrasion
resistance, food contact safety, UV resistance and the like. An
example of a suitable polymer is high density polyethylene.
[0013] The base may be planar as in conventional bulk containers or
may have a curved configuration. The base may have an outwardly
curved configuration, whereby the surface of the base bulges or
bows outwardly thereby to define a substantially concave interior
surface.
[0014] Where the base is substantially planar, as in conventional
bulk containers, the base must necessarily be reinforced with
strengthening ribs. However, where the base has an internally
concave configuration the need for reinforcing ribs may be
substantially reduced, although not necessarily entirely dispensed
with, and the thickness of the base may also be substantially
reduced. Moreover, the internal volume of the container, and hence
its produce capacity, is increased by making available the area
below side edges of the base which are normally reserved for the
insertion of forklift tines. Accordingly, in a preferred embodiment
the container has an internally concave base whereby the depression
extends into the area intermediate the area reserved for insertion
of the forklift tines.
[0015] The concave base may be radially contoured to provide an
irregularly concave base. The base may have a central deep bowl
inclined radially upwardly towards the lower edge of each wall of
the container. Preferably, however, the base is made with minimal
thickness to save on material and is reinforced by ribs as is
conventional in the art. Where a concave base is used, the need for
reinforcing ribbing has been found to be reduced because of the
geometrically stronger shape of the concave base compared to the
conventional planar base.
[0016] The reinforcing ribs of the base may be in the form of a
square or rectangular grid pattern. The reinforcing ribs may be in
the form of circular or radiating ribs extending outwardly from a
center point of the base. The reinforcing ribs of the base may be a
combination of a grid pattern and a circular or radiating pattern.
Where a concave base is used, the reinforcing ribs may comprise a
series of circular ribs of ever increasing diameter extending away
from the center of the base. The concave base may comprise linear
ribs radiating outwardly from an area central to the base towards
the container walls.
[0017] Preferably, the reinforcing ribs are located on the
underside of the base. The underside of the base may be configured
to provide runners for forklift tines. The runners may be solid or
may be formed from reinforcing ribs. The runners may be
substantially planar along their length. The runners may include
upturned portions at one or both of their ends whereby to receive
and guide the tine onto the runner and reduce the likelihood of a
potentially damaging collision between the tine tip and another
portion of the container.
[0018] Some of the walls may be planar and reinforced with ribs as
is standard in the art. Preferably all of the walls are adapted to
have an outwardly curved configuration under a neutral load. A
normal load may be considered the load applied to the bearing
surfaces of the container including the base and the walls when the
container is full of produce. A neutral load may be considered the
load applied to the bearing surfaces of the container when the
container is empty.
[0019] The walls may be capable of flexing under a normal load. The
walls may be substantially rigid and inflexible whereby they have a
permanently outwardly curved configuration whether under load or
not.
[0020] As the force applied by a normal load has a tendency to urge
conventional planar walls into an outwardly curved configuration,
the molding of the walls with a permanent curved configuration may
achieve similar strength properties as obtained by a conventional
planar wall without the need for the reinforcing ribs required to
achieve the necessary strength properties for the walls. Moreover,
by having the walls in this curved configuration the walls may be
molded with a far smaller thickness than conventional planar walls
with ribs. For example, a conventional planar wall with ribs
generally has a thickness of about 40 mm and requires substantial
reinforcing ribbing. By contrast, a wall of the container of the
present invention may be formed having a thickness of less than 40
mm, such as 30 mm to 40 mm, or 20 mm to 30 mm, or 10 mm to 20 mm,
or 1 mm to 10 mm, preferably 3 mm to 6 mm and may require no
ribbing at all on the majority of its surface. The curved wall may
require no reinforcing ribs on its surface at all.
[0021] As the cubed volume of the container is critical and
generally must be rigidly constrained within certain standards, it
is preferred that the curved walls do not bow beyond the limit of
the cubed volume of the container.
[0022] Each adjacent pair of walls may be joined at their junctions
by corner posts. The corner posts may be partially or fully hollow,
or internally porous. The corner posts may be L-shaped, square
shaped, circular, rectangular, channel shaped or any other suitable
shape in cross section. Preferably the corner posts are hollow,
thereby to save on material costs. Preferably the corner posts are
circular in cross section. Preferably the corner posts have an
overall cylindrical configuration. The inventors have discovered
that a cylindrical corner post molded to be hollow by the use of
vertical inserts in the manufacturing process, provides a post
using a minimal amount of material, whilst possessing optimum
strength.
[0023] The corner posts may be of a substantially constant cross
section throughout their lengths. The corner posts may include top
and bottom surfaces which are complementary, whereby the bottom
surface is adapted to be seated on a complementary top surface. The
top and bottom surfaces of the corner post may include a variety of
complementary configurations well known to the person skilled in
the art. The top of each corner post may include a planar
part-circular support surface for seating a corner post base with a
corresponding circular configuration.
[0024] The top of the container may include an upstanding lip
extending totally or partially around the periphery of the
container. The lateral ribs may form corner ledges abutting the
base of the lip at each corner. The corner post base may include a
foot with an instep contoured to fit around the corner lip whereby
the foot fits snugly onto the corner post top surface and corner
lip.
[0025] Adjacent the top surface of each corner post there may be a
lateral ledge extending on one or both sides to improve the
stability of the upper portion of the container and to maintain the
curved structure overall. The lateral ledge may extend as bridges
between the corner posts. The lateral ledge may taper towards the
center of each adjacent wall. The lateral ledge may extend to a
point intermediate the length of the top of each adjacent wall.
[0026] Accordingly, in a preferred form of the invention the
container may comprise four outwardly curved walls and a minimally
reinforced internally concave base together with four hollow
cylindrical corner posts. Such a container represents a structure
having considerable strength, being lightweight, and requiring
lower amounts of material compared to prior art containers. It may
be apparent to a person skilled in the art that the geometry of
this shape of the container generates a volume or capacity
comparable to a conventional bin with generally flat, planar walls
and base.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The invention will now be described in the following non
limiting description of one embodiment of the invention, in
which:
[0028] FIG. 1 is a perspective view of the top side of a container
according to the invention;
[0029] FIG. 2 is a perspective view of the underside of the
container;
[0030] FIG. 3 shows side elevation part sections of the container
on the entry side and the foot side; and
[0031] FIG. 4 shows a part plan view and a part underside plan view
of the container.
DETAILED DESCRIPTION OF THE INVENTION
[0032] FIG. 1 shows an embodiment of the invention comprising a
bulk container integrally formed by a single molding process. The
container 1 includes a base 10, four walls 12a, 12b extending
substantially vertically therefrom and four corner posts 14
interposed at each of the junctions of each pair of walls 12a ,12b
and a continuous upstanding lip 16 extending around the periphery
of the upper region of the container 1.
[0033] The walls 12a, 12b curve outwardly. The lower edge 22 of
each of opposed walls 12a extends along an arc connected at either
end to feet 42 whereby the lower edge 22 lies in the horizontal
plane extending between the feet 42 as best shown in FIG. 2. The
lower edge 22 is configured to receive either individual corner
feet 42 or to receive a single longitudinal foot 23c extending
between the feet 42 along the sides of the container 1
corresponding to walls 12a. The longitudinal foot 23c has an
internal linear edge 23 and a curved outer edge 23a which generally
follows the contour of the wall 12a. Inset into the outer edge 23a
is a recess 23b to avoid transfer of loads onto the walls 12a,
12b.
[0034] The lower edge 24 of opposed walls 12b is raised, relative
to lower edge 22 to enable forklift tines (not shown) to be
received under the container 1. The lower edge 24 follows a similar
curved contour to the wall 12b, which contour is of a substantially
constant cross section extending from the lower edge 24 to the
upper edge 26b of the wall 12b.
[0035] The posts 14 are substantially hollow cylindrical structures
extending from a lower end 41 up to a top post surface 44. The top
post surface 44 is generally of a circular planar configuration
adapted to snugly receive a corresponding foot 42 of an identical
container 1 to be seated thereon when vertically adjacent
containers 1 are to be stacked one on top of the other.
[0036] To conform to the corner portion 18 of the lip 16, the foot
42 of each corner post 14 is provided with a recess in the form of
an instep 46 to enable vertically adjacent containers 1 to be
stably stacked one on top of the other.
[0037] Extending in the same plane as top post surface 44 are pairs
of laterally extending reinforcing ledges 48 which taper towards
the center area of the top wall edges 26a, 26b. The lateral
reinforcing ledges 48 improve the lateral stability of the top
region of the container 1 and provide a lateral bridge between the
top edges 26a, 26b and the upstanding lip 16 without requiring side
molds or inserts during the molding process.
[0038] The base 10 as best shown in FIGS. 2 and 3 includes a
central bowl region 2 extending radially upwardly to meet the walls
12a, 12b at their lower regions but above lower wall edges 22, 24.
The base 10 is gradually stepped whereby there is provided a steep
inclination region 4 towards the center 2 and a shallower
inclination in the outer regions 6 of the base 10 as shown in FIG.
3. The shallower region 6 is adapted to accommodate a pair of
opposed runners 8 extending in parallel direction adjacent opposed
walls 12a under the base 10.
[0039] The central area 4 of the base 10 includes reinforcing ribs
2a having a radiating pattern corresponding to the contour of the
bowl shaped base 10. The radiating pattern includes a series of
circular reinforcing ribs 2b of increasing diameter extending away
from the center portion 2 and linear reinforcing ribs 2c radially
extending outwardly from the center portion 2. The radiating
reinforcing ribs 2a extend to the lower edges 24 of walls 12b and
the internal edge 8a of each runner 8.
[0040] The central area 2 is configured to depend downwards to
within 12.5 mm of the plane occupied by the lowermost points of the
container 1, thereby to maximize the internal volume of the
container 1 and make use of the space between the runners 8.
[0041] Each runner 8 is formed from a rectangular grid pattern of
reinforcing ribs presenting a sufficiently smooth running surface
for forklift tines to slide underneath. The runners 8 have upturned
ends 9 thereby to facilitate the entry of a forklift tine.
[0042] The container according to the above described exemplary
embodiment of the invention has a range of superior properties
compared to conventional bulk containers.
[0043] In containers with internally planar surfaces, the produce
tends to apply forces of unequal distribution to the supporting and
wall surfaces whereby bruising or other damage to the produce is
likely to occur. The inky concave surfaces of the container of the
invention provide for a more even distribution of the forces
applied by the produce, thereby to minimize damage to the
produce.
[0044] The geometry of the corner posts being in the form of hollow
circular columns provides a structure more resistant to buckling
than the conventional L-shaped posts and is also most cost
effective with regard to capital costs for tooling.
[0045] The internal surfaces of the container are permitted to
"bulge" outwardly, thereby to take up the space intermediate the
corner posts which is normally lost in a conventional
container.
[0046] The bowl shaped base depending into the space normally
reserved under the base for insertion of forklift tines provides a
container with an increased capacity in that the volume ratio is
increased.
[0047] One embodiment of the invention also may provide an easily
stackable container which is not only convenient but may be
essential in particular commercial applications.
[0048] The preferred embodiment is considerably lighter than
conventional plastic bulk containers due to the use of less
material per unit.
[0049] The container of the invention may be easier to mold in
manufacture than conventional containers because the need for
reinforcing ribs for the side walls may be dispensed with, the
reinforcing ribs of the base may be substantially reduced in number
and depth and the cylindrical post construction may be easier to
form in the molding process than conventional post designs.
[0050] In particular, the cycle time involved in the manufacturing
process may be considerably shortened as the deep reinforcements of
conventional plastic bulk containers tend to slow down the cycle.
In fact, the elimination of the reinforcing ribs normally required
for the container walls may result in once cycle of the
manufacturing process being completely eliminated. That is the side
movement of the mold to release the reinforcing ribs on a
conventional plastic bulk container's walls may be dispensed
with.
[0051] It will be appreciated that many modifications and
variations may be made by those skilled in the art to the
embodiments described without departing from the spirit or scope of
the invention.
* * * * *