Note: Descriptions are shown in the official language in which they were submitted.
CA 02531935 2012-11-30
,
1
STACKABLE EGG-BOX, STACK OF EGG-BOXES
AND METHOD FOR DESTACKING SAID EGG-BOX
Field of the invention
[0001] The invention relates to an improvement in trays obtained by vacuum
moulding of a sheet of
plastic material and intended to be stacked one into the other. More
particularly, each of said trays
defines an egg-box into an opened position.
Background of the invention
[0002] It is known in the art to obtain trays by thermoforming techniques,
especially vacuum
moulding, and to stack them one into the other. It is also known to stack
trays defining an egg-box
into an opened position (see Applicant's Canadian Patent No. 2,028,229).
However, when trays are
stacked one into the other, friction and/or air lock may be created between
neighboring trays. Such
interlocking of trays involves that when a tray is picked up (or denested)
from the stack, one or
several neighboring trays may be simultaneously picked up. This drawback
becomes very important
when said stack of trays is intended to feed an automated packaging and/or
labeling apparatus,
especially an apparatus intended to fill egg-box trays with eggs. Indeed, when
the apparatus becomes
jammed, it has to be stopped and an operator must manually remove the trays
from the apparatus.
There is a substantial lost of productivity and of course substantial risks of
damaging the apparatus.
[0003] It is also known in Applicant's co-pending US application serial no.
10/934,400 to obtain
stackable tray by vacuum molding of a sheet of plastic material, said tray
comprising, in open
position:
a) a top and a bottom;
b) at least one receiving cavity opened upwardly; and
CA 02531935 2005-12-30
2
c) spacing means to keep, in a stack of trays, the top portion and the bottom
portion of
neighboring trays at distance from each other to thereby prevent interlocking
between
adjacent trays.
[0004] However, when such a tray defines an egg-box of large size, for example
for 18 eggs or
more, it appears that said box resulting from the folding of a cover portion
over a portion
provided with egg receiving cavities, does not present a level of rigidity
allowing to prevent
deformation of the box and to optimize the protection of its fragile content.
[0005] Therefore, there is a need for trays of the type as defined in co-
pending US application
serial no. 10/934,400 that can be stacked one into the other without creation
of air lock or friction
between neighboring trays, that can allow an easy removal of each tray from
the stack of trays and
whose box resulting from the folding of a cover portion over another portion
provided with egg
receiving cavities, will present a sufficient rigidity to protect adequately
its fragile content.
Summary of the invention
[0006] The Applicant has now discovered an innovative manner to interlock the
cover portion of
the tray with a base portion of said tray that is provided with receiving
cavities (especially egg
receiving cavities), to thereby overcome the drawback existing with prior art
trays.
[0007] More particularly, the invention relates to a stackable tray obtained
by thermoforming,
especially vacuum molding, of a sheet of plastic material. Said tray
comprises, in open position:
a) a top and a bottom;
b) at least one receiving cavity opened upwardly;
c) a hinge portion dividing said tray into a cover portion and a base
portion; said receiving
cavity being at least provided in said base portion;
d) spacing means to keep, in a stack of trays, the top portion and the
bottom portion of
neighboring trays at distance from each other to thereby prevent interlocking
therebetween; and
CA 02531935 2005-12-30
3
e) at
least one two-part locking means, each part being provided in the top of the
sheet and
positioned to engaged one into the other when the cover portion is folded over
the base portion
along the hinge portion to bring the tray into a closed position defining a
box. Preferably, the two-
part locking means comprises a first two-part locking means provided at an
intermediate portion
of the cover portion and base portion, and at least a second two-part locking
mans provided in a
peripheral portion of the cover portion and base portion.
100081 Advantages of said trays amongst others, are at least the following:
- resistant, good protection of the integrity of its contents, especially egg-
shells, during packaging,
storing and transport, even for large size boxes;
- light in weight and inexpensive to manufacture;
- may define a plate or bowl for receiving meals to be eaten by a traveler in
a public transport (e.g
jet planes, buses, trains, etc.);
- discourages the opening of the box by a customer in a grocery store;
- when in close position, has an interlocking system preventing accidental
opening of said box
and preferably cooperating with edge of the cover portion, base portion and
hinge portion to give
said box a substantial rigidity preventing deformation of the box and thereby
damage to its fragile
content;
[0009] Advantageously, according to a preferred embodiment, the invention also
relates to a tray
defining an egg-box obtained from a rectangular sheet of plastic and provided
with a plurality of
egg receiving cavities. Of course, other kind of boxes may be considered
within the field of the
invention. For example, said boxes may be a lunch box, a box for various
articles (food articles or
not), etc.
[0010] Advantageously, the sheet of plastic material may consist of any
appropriate thermoplastic
material. Preferably, the sheet can be made of polyethylene terephthalate. Of
course any
equivalent thermoplastic sheet that can be thermoformed, especially by vacuum
molding, may be
CA 02531935 2005-12-30
4
used. The thickness of said sheet may vary between wide limits so far it is
still possible to
embody said tray by thermoforming techniques such as vacuum molding.
Preferably, said
thickness may be of 14 mil. Preferably, a clear and transparent thermoplastic
sheet is used.
[0011] Said trays may be obtained by any usual thermoforming techniques such
as vacuum
molding (e.g. by forming a sheet of thermoplastic material under the action of
heat (e.g. by
thermal convection)) and a mechanical stress. Preferably said mechanical
stress may be obtained
by air vacuum created at the base of the mould thanks to air vacuum nozzles.
Such techniques are
well known to a skilled workman and do not necessitate any substantial
description in the present
disclosure.
[0012] Advantageously, according to another preferred embodiment, each egg
receiving cavity of
the base portion may be further provided with a set of at least three (more
preferably six) inwardly
projecting ribs for supporting an egg. Said ribs have a lower portion
substantially straight in the
bottom of the cavity and an upper portion curved to substantially fit with a
corresponding contour
of an egg.
[0013] Optionally, as in co-pending US application serial no. 10/934,400 and
according to
another preferred embodiment, the cover portion may be further provided with
egg receiving
cavities for the upper portion of eggs. Preferably, each of said receiving
cavity of the cover
portion may be further provided with a set of at least three (more preferably
six) inwardly
projection ribs allowing to minimize movement of an egg housed in said
cavities of the base
portion and cover portion. Advantageously, said ribs may have a portion
substantially straight
near the bottom of the cavity and a portion substantially curved to
substantially fit with a
corresponding contour of an egg.
[0014] Said ribs are preferably equidistant. However, they could be
distributed in a different way.
The side of compartment is such to receive an egg shell of predetermined size
(e.g. small,
medium, large, extra-large, etc. ). The egg shell is introduced in the
compartment and is supported
CA 02531935 2005-12-30
by ribs, rather than by the side wall or by the bottom. The egg shell is
advantageously at distance
from the bottom of said cavity.
[0015] The fact that the egg shell is retained by ribs is particularly
advantageous in order to
preserve the integrity of the egg shell. Indeed, any impact of the container
with an outside object
will prevent a direct impact on the egg shell, this later being at distance
from the bottom of the
container and from the side wall by ribs. Said ribs are not directly in
contact with the outside of
the container.
[0016] Advantageously, according to another preferred embodiment, spacing
means are stoppers
having a portion thereof provided with negative angle, an upper portion and a
lower portion, said
upper portion and lower portion of each stopper, when said tray is in open
position, facing
corresponding lower portion and upper portion of neighboring trays to keep a
gap between said
trays and prevent them to become interlocked.
[0017] A man skilled in the art was not encouraged to embody a molded article
by
thermoforming, especially vacuum moulding, while said article has negative
angles because the
risk of having this article locked on the mould. However, surprisingly, the
article can be easily
removed from the mould to thereby allow the manufacture of trays provided with
stoppers
allowing to space apart neighboring trays in a stack of trays (in open
position).
[0018] Advantageously, according to another preferred embodiment, the cover
portion and the
base portion are each provided with a peripheral flange, said flanges being
sized to fit one against
the other when the cover portion is folded over the base portion along the
hinge portion.
Optionally, said peripheral flanges may be further shaped to define at least a
second two part
locking means. Each part of said second two part locking means being provided
with at least one
protuberance engaging a corresponding cavity substantially perpendicularly to
the plane of the
original sheet.
CA 02531935 2005-12-30
6
[0019] Advantageously, according to another preferred embodiment, the cover
portion may be
further provided with at least one substantially flat surface for receiving
thereon a printed label, a
printed stamp or both. For example, said flat surface may support an
advertising label, and
information stamp (printed directly on the surface), or both. Optionally, said
label may be glued
on said surface (preferably inside the cover portion).
[0020] Optionally, as mentioned in Applicant's co-pending US application
serial no. 10/934,400,
the cover portion may be provided with at least one venting opening
(preferably four or eight
venting openings). These venting openings allow a good ventilation of the
inside of the box to
thus prevent the gathering of humidity therein and allow abetter preservation
of its content (e.g.
eggs). Preferably, according to a particularly preferred embodiment of the
present invention, said
venting openings may be provided in the cover portion and the base portion.
More preferably,
when venting opening are provided in the base portion, a venting channel may
be advantageously
further provided in the peripheral flange, said venting channel allowing to
make easier the fluid
communication of air between said venting opening and the interior of the box.
[0021] Optionally, as mentioned in Applicant's co-pending US application
serial no. 10/934,400,
said tray may be further provided with means for facilitating the denesting by
an automated
packaging and/or labeling apparatus. Preferably, said means may comprise
projecting members
provided on the outside of cavities near ends of the tray. More particularly,
projecting members
are provided by pair on the outside of each cavities near ends of the tray to
thus define a receiving
track for a denesting tool.
[0022] The invention also relates to a stack of trays as defined hereinbefore.
[0023] The invention further relates to a method for denesting trays from a
stack of empty trays to
feed an automated packaging and/or labeling apparatus, said method comprising
a step in which
trays are successively picked up from a stack of trays as defined
hereinbefore. Advantageously, a
tool (e.g. a fork like tool) which is part of a packaging and/or labeling
apparatus, engages the
CA 02531935 2005-12-30
7
track defined by the projecting members and denests a tray from the bottom of
the stack to feed
said apparatus.
Brief description of the drawings
[0024] Figure 1 is a top plan view of a preferred embodiment of a tray
according to the invention;
[0025] Figure 2 is cross sectional view of the tray of Figure 1 according to
line II-II;
[0026] Figure 2a is a cross sectional view of the tray of Figure 2 showing how
works spacing
means;
[0027] Figure 3 is a cross sectional view of the tray of Figure 1 (according
to line II-II and with its
cover portion tilted over the base portion);
[0028] Figure 4 is a cross sectional view of the tray of Figure 1 according to
line IV-IV showing a
preferred embodiment of a second two part locking means when said tray has its
cover portion
tilted over the base portion;
[0029] Figure 5 is a top plan view of a receiving cavity provided with ribs
according to the
invention;
[0030] Figure 6 is a partial view of a cavity containing an egg showing
distinct portion of the ribs
with respect to the contour of the egg;
[0031] Figure 7 is a partial view of the tray of Figure 1 showing a preferred
embodiment of a
hinge according to the invention.
100321 Figure 8 is a schematic view of a packaging / labeling machine picking
up trays from a
CA 02531935 2005-12-30
8
stack of trays according to the invention;
[0033] Figure 9 is a schematic view of a tool allowing to pick up the tray
from the stack;
[0034] Figure 10 is a top plan view of a variant of the tray of Figure 1;
[0035] Figure 11 is cross sectional view of the tray of Figure 1 according to
line II-II;
[0036] Figure 12 is a cross sectional view of the tray of Figure 11 showing
how works spacing
means;
[0037] Figure 13 is a cross sectional view of the tray of Figure 10 (according
to line and with
its cover portion tilted over the base portion);
[0038] Figure 14 is a cross sectional view of the tray of Figure 10 according
to line 1V-IV
showing a preferred embodiment of a second two part locking means when said
tray has its cover
portion tilted over the base portion.
Brief description of preferred embodiments as represented in the drawings
[0039] With reference to the enclosed drawings, there is represented in Figure
1 a particularly
preferred embodiment of the invention, that is a stackable tray 1 obtained by
vacuum molding of a
sheet of thermoplastic sheet, especially a transparent polyethylene
terephthalate sheet having a 14
mil thickness. This tray 1 comprises, in open position:
a) a top portion 3 and a bottom portion 5;
b) at least one receiving cavity 7 opened upwardly;
c) a hinge portion 33 dividing said tray 1 into a cover portion 21 and a
base portion
29; said receiving cavity 7 being at least provided in said base portion 29;
CA 02531935 2005-12-30
9
d) spacing means 9 to keep, in a stack S of trays 1, the top portion 3 and
the bottom
portion 5 of neighboring trays 1 at distance from each other to thereby
prevent
interlocking therebetween (especially frictional or pneumatic interlocking);
and
e) at least one first two-part locking means 41, each part 43, 45 being
provided in the
top 3 of the sheet and positioned to engaged one into the other when the cover
portion 21
is folded over the base portion 29 along the hinge portion 33 to bring the
tray 1 into a
closed position defining a box. In Figure 10 there is represented a alternate
variant of the
tray 1. All identical parts of this alternate tray have same reference numbers
than the tray
shown in Figure 1 except said reference numbers are now marked with a prime
symbol
(i.e. tray 1 becomes tray l', top portion 3 becomes top portion 3', etc.) in
order to avoid
repetitive statements and clarification purposes.
[0040] Advantageously, the tray represented in Figure 1 relates to a tray
defining an egg-box EB
provided with a plurality of egg receiving cavities 23. Of course, other boxes
may be considered
within the field of the invention. For example, said boxes may be a lunch box,
a box for various
articles (food articles or not), etc.
[0041] More particularly, as illustrated in the drawings, the egg-box EB may
comprise a base
portion 29 provided with the egg receiving cavities 23; a cover portion 21; a
hinge portion 33
defining a hinge 34 between the cover portion 21 and the base portion 29.
[0042] As illustrated in Figure 8 the hinge may merely consist in a fold made
in the thermoplastic
material. Alternatively, the hinge could be any well known variation of
plastic hinges. It is
preferred to have hinge 34 defined as a mere fold in the plastic material.
Such hinges are easy to
manufacture and inexpensive. They can be made by any appropriate technique
well known in the
art. For example, the plastic sheet may be partially cut or weakened to define
folding line 38.
[0043] As illustrated in Figures 1 and 6, each egg receiving cavity 23 may be
further provided
with a set of six inwardly projecting ribs 61 for supporting an egg E, said
ribs 61 having a lower
CA 02531935 2005-12-30
portion 63 substantially straight in the bottom of the cavity 23 and an upper
portion 65 curved to
substantially fit with a corresponding contour of an egg E.
[0044] Spacing means 9 may be provided in the base portion 29 between cavities
7, 23 and a
periphery 30 of said base portion 29. As illustrated in Figures, spacing means
9 may comprise
stoppers 111. These stoppers 111 are all provided with negative angle and are
provided with an
upper portion 113 and a lower portion 115.
[0045] First two-part locking means 41 according to the embodiment illustrated
in Figures 1 to 9
each have a part 43 provided in the cover portion 21 and a part 45 provided in
the base portion 29.
These parts engage one into the other to contribute to the improvement of the
structural stability
of the box to be obtained. Because said parts 43 and 45 are provided with
neutral or preferably
positive angles, there is no problem to repetitively open and close the cover
and mechanical
engagement of parts 45 into part 43 as illustrated ( or alternatively
according to any obvious
mechanical equivalent) is sufficient to contribute to the stiffness of the box
to be obtained.
Preferably, said first two-part locking means 41 are positioned in the bottom
of a cavity 42
extending across the width of the cover portion 21 to still further improve
the stiffness of the box
(once closed). Alternatively, spacing means 9 may be provided on the locking
means 41 (in the
case of the alternate embodiment of Figures 10 to 14) and/or in the base
portion 29 between
cavities 7,23 and a periphery 30 of said base portion 29 (in the case of both
embodiments). As
illustrated in the alternative embodiment of Figures 10 to 14, spacing means 9
comprise stoppers
91', stoppers 101' and stoppers 111. More particularly, said stoppers 91',
101' and 111 are all
provided with negative angle and have the following particulars:
= each stopper 91' has an upper portion 93' and a lower portion 95', said
stopper 91' being
provided in part 43' of the two part interlocking means 41';
= each stopper 101' has an upper portion 103' and a lower portion 105',
said stopper 101' being
provided in part 45 of the interlocking means 41; and
= each stopper 111' has an upper portion 113' and a lower portion 115'.
CA 02531935 2005-12-30
11
[0046] In a stack of tray according to the embodiment of Figure 1, the lower
portion 115 of a tray
1 rests on a corresponding upper portion 113 of another tray 1 positioned
underneath to thereby
prevent neighboring trays to become interlocked together by friction and/or
airlock. According to
the alternative embodiment of Figures 10, stoppers 91' have negative angles so
as in a stack S of
open trays l', its upper portion 93' supports the lower portion 95' of
corresponding first stoppers
91' of a neighboring tray l' to thereby further prevent neighboring trays to
become interlocked
together by friction and/or air lock. The tray of Figure 1 is particularly
preferred embodiment of
the invention. Indeed, it has been surprisingly found that it is possible to
obtain sufficient stiffness
of the box even though the first locking means is not snapped as in Figure 10.
This characteristic
also contributes to simplify the manufacturing of the tray.
[0047] The tray of Figure 1 is a particularly preferred embodiment of the
invention. According to
this embodiment, the interlocking means 41 is provided in a cavity 42 that
further provide
additional rigidity to the cover portion 21.
[0048] As illustrated in Figures 10 to 14, parts 43' and 45' may define a two
part snap fastener
where part 43 is sized to be snapped into a bore 44' defined in part 45'. When
the box is closed,
parts 43', 45' consolidate the structural rigidity of the resulting box. Of
course, even if
represented as being preferred on the kings of two part snap fasteners may be
used.
[0049] Furthermore, stoppers 91', 93' and 95' may have other geometric
configuration. Indeed,
geometric configuration illustrated in the drawings is only illustrative and
not limitative.
[0050] As illustrated in Figure 1, the cover portion 21 may be further
provided with at least one
substantially flat surface 121 for receiving thereon a printed label, a
printed stamp or both. For
example, said flat surface 121 may support an advertising label 123.
Alternatively information
stamp may be printed directly on the surface (example: CUP code and/or
peremption date), or
both. Optionally, said label 123 may be glued on said surface.
CA 02531935 2005-12-30
12
[0051] In order to close the box the following steps are carried out.
[0052] As illustrated in Figure 1, the base portion 29 and the cover portion
21 may be further
provided with venting means 130. Preferably, said means merely consist in a
deformation in the
rim of the box EB at the end of the base portion 29 of the tray 1 and at the
end of the cover
portion 21.
[0053] As illustrated in Figures 10 to 14, the cover portion 21 is provided
with two sets of locking
means 41, especially two sets of snap fasteners. Each fastener has a molded
portion that engages
(i.e. snaps) into a bore 44' upon closure of the cover portion 21 over the
base portion 29. The
locking means 41 allow the box to have increased rigidity, especially when the
size of the box is
such that it may be subjected to deformation increasing the risk of damage to
its content.
[0054] As illustrated in Figures 1 to 14, the cover portion 21 is provided
with two or three sets of
locking means 131, especially sets of friction fastener 133. Each fastener 133
has molded
protuberances 135, 137 that are substantially perpendicular to the plane of
the original sheet and
engages (with friction) one into the other upon closure of the cover portion
21 over the base
portion 29.
[0055] As illustrated in Figures 1 to 14, the cover portion 21 may be further
provided with pairs
of two parts fastener 141. Each fastener 141 has portions 143, 145 molded in
the plastic that
engages into the other upon closure of the cover portion 21 over the base
portion 29. As
illustrated, said portions 143 and 145 are substantially perpendicular to the
plane of the original
sheet.
[0056] The locking means 41, 131 and 141 are not limited to what is
illustrated in the drawings
and may extend to various other kinds of two part locking means known in the
art to be
equivalent two part locking means. Two part locking means 131 and 141
contribute to provided
CA 02531935 2005-12-30
13
additional rigidity to the resulting box.
[0057] As illustrated in Figures 1 to 14, the cover portion 21 and the base
portion 29 may be
provided with peripheral flanges 51 and 59 which when the cover portion 21 is
folded over the
base portion engages one into the other and cooperate with locking means 41,
131 and 141 to
provide additional rigidity to the box, especially the egg-box. Also,
additional rigidity may be
further obtained with recess 81 that are provided in thee wall of the cover
portion 21. As
illustrated, one part of the second two par locking means may be provided in
said recess.
[0058] In order to open the box, reversed steps are carried out.
[0059] As illustrated in Figures 8 and 9, said tray 1 may be further provided
with means 151 for
facilitating the denesting by an automated packaging and/or labeling
apparatus. Preferably, said
means may comprises projecting members 153 provided on the outside of cavities
23 near ends of
the tray 1. More particularly, projecting members 153 are provided by pair on
the outside of each
cavities 23 near ends of the tray 1 to thus define a receiving track 155 for a
denesting tool 161.
[0060] The invention also relates to a stack S of trays 1 as defined
hereinbefore.
[0061] The invention further relates to a method for denesting trays 1 from a
stack S of empty
trays 1 to feed an automated packaging and/or labeling apparatus, said method
comprising a step
in which trays are successively picked up from a stack S of trays 1 as defined
hereinbefore.
Advantageously, a tool 161 (e.g. a fork like tool) which is part of a
packaging and/or labeling
apparatus, engages the tracks 155 (on both sides of the tray 1) defined by the
projecting members
153 and denests a tray 1 from the bottom of the stack S to feed said
apparatus. Preferably, as
illustrated, there are 16 projecting members 153, eight on each side of the
tray 1.
The present invention is not limited to the preferred embodiments recited
hereinbefore and also
relates to any variation and equivalent that may appear to be obvious to a
skilled workman.
