Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PLASTICS MATERIAL CRATE
DESCRIPTION
The invention relates to a plastics material crate in particular for the
packing and transportation of fruit and vegetables.
At present there are different types of wooden, cardboard and plastic crates.
Wooden and cardboard crates jointly suffer from major disadvantages.
A first of these disadvantages is their permeability to water. This perme--
ability is particularly sensitive in the case of cardboard crates, whose
mechanical strength decreases considerably in the presence of moisture. In
all cases, the permeability of the wood and cardboard imposes covered storage
locations. In addition, it considerably changes the weight of the tare
constituted by each crate, contrary to the regulations in force, which impose
a fixed tare.
Another disadvantage of wooden and cardboard crates results from the multi-
plicity of components forming the same. Thus, apart from the wood or card-
board forming the main constituent of such crates, their assembly requires
the use of clips and/or glue. Moreover, they normally contain a waterproof-
ing agent, whose function is to reduce to the greatest possible extent their
permeability to water. In addition, paper labels are frequently clipped onto
the wooden crates. This multiplicity of components of wooden and cardboard
crates complicates their manufacture and consequently increases their cost.
Moreover, the operations necessary for the destruction of the crates after
use, with a view to the recycling of their constituent materials, is con-
sequently made much more complicated.
A third disadvantage common to wooden and cardboard crates relates to their
inflammable character and the resulting risks during their storage, no matter
whether they are empty or full.
3~ Finally, both wooden and cardboard crates leads to a considerable consumption
of wood in their manufacture, which is ecologically disadvantageous.
The stacking of crates during storage is made more difficult by the thickness
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of the crate bottom to the right of the angle posts.
To these disadvantages common to both wooden and cardboard crates are added
those specific to each of these materials.
In the case of wooden crates, the rough structure of the untreated wood from
which these pallets are made may damage the products placed in the crates,
particularly in the case of fruit.
In the case of cardboard crates, it has already been stated that their mech-
anical characteristics deteriorate very significantly in the presence of
moisture. It is pointed out that this moisture can come both from the
environment and the products transported in the crates.
Another disadvantage inherent in cardboard crates and uhich results from that
referred to hereinbefore, relates to the inadequate ventilation of the pro-
ducts transported in such crates. Thus, the limited mechanical strength of
cardboard crates prevents the formation of perforations therein. This has in
particular the consequence of cardboard crates being unusable for transport-
ing certain products requiring an effective ventilation.
Plastics material crates solve virtually all the problems encountered in
common by wooden and cardboard crates. However, these crates are at present
manufactured by injection moulded plastics material, i.e. using a discon-
tinuous process, which considerably increases costs.
The use of injection moulding also leads to the crate walls having a grid or
grating-like structure, which may damage the transported products, partic-
ularly in the case of fruit. The resulting crate sides are rigid and may
bruise the products when the latter are put into place.
Finally, the structure of the moulded plastics material crates gives them
~ertical overall dimensions comparable to those of wooden crates, when the
latter are stacked on pallets.
35 W0-A-92 09488 describes a process making it possible to manufacture by
extrusion plastics material crates. These crates are produced from at least
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one extruded plastics material section. In the part constituting the bottom
and the four sides of the crate, said section is in the form of a plastics
material strip in which are formed randomly shaped holes. Around each of the
said holes, a projecting portion is formed in the strip by thermoforming.
The resulting plastics material crates do not suffer from the disadvantages
of injection moulded plastics material crates. Thus, continuous manufacture
by extrusion makes it possible to considerably reduce costs and bring it to a
lower level than the costs involved with wooden and cardboard crates. In
addition, the structure of the crates give their sides a certain elasticity,
so that the transported products are not bruised. The vertical overall
dimensions of a stack of crates can be reduced compared with a stack of
wooden or moulded plastics material crates. An increase by approximately 10%
of the filling level can be achieved in this way.
In the crates described in W0-A-92 09488, the holes and projecting portions
surrounding them bring about an adequate ventilation of the transported
products and contributes to increasing the mechanical strength of the crate.
However, the products transported in such a crate can be damaged by the edges
or rims of holes formed in the sides and bottom of the crate and the outflow
of water and any other liquid present in the transported products is not
ensured in a reliable manner. Moreover, it is not possible to completely
avoid a dragging or sliding risk for said crates when they are placed on a
conveyor. Moreover, like all existing crates, those obtained by the process
Of W0-A-92 09488 are not mutually positioned during stacking.
The invention relates to a plastics material crate having the main charac-
teristics of the crate obtained by the process described in W0-A-92 09488 and
whose original design makes it possible to avoid any risk of damaging the
transported products, effectively ensures the outflow of liquids, avoids any
sliding of the crate when it is placed on a conveyor and facilitates the
relative positioning of the crates during their stacking, without increasing
the cost of the crates and without removing the other advantages inherent in
plastics material crates.
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According to the invention, this result is obtained by means of a plastics
material crate comprising a rectangular bottom, four sides and four hollow
angle posts, at least the bottom and the sides being formed in a plastics
material strip, which has holes, each of which is surrounded by a thermo-
formed, projecting portion, characterized in that the projecting portions areoriented towards the outside of the crate and at least two of these project-
ing portions are formed in the bottom of the crate, in the extension of at
least two of the four hollow angle posts, so as to permit the penetration of
the hollow angle posts in an adjacent, lower crate.
With certain plastics materials liable to be used for producing such a crate,
such as polypropylene, polyvinyl chloride, etc., the formation of projecting
portions by thermoforming in the bottom and sides of the crate, tends to
deform these planar portions in the direction of the thermoforming, i.e.
towards the outside of the crate. Therefore, when the crates are stacked,
the products placed in a random crate may be damaged by the edges or rims of
the holes formed in the bottom of the adjacent, upper crate. To obviate this
disadvantage, at least in the bottom of the crate, the strip has at least one
unperforated, thermoformed cambering located between the projecting portions
and oriented towards the inside of the crate.
As a function of the particular case, there can be a single camber or camber-
ing distributed over the entire surface between the projecting portions, or
there can be several bosses located between said projecting portions.
~oreover, the sides of the crate are advantageously elastic, so that products
placed in the crate are not bruised when being put into place.
In order to improve the mechanical strength of the sides of the crate, each
o~ them advantageously has an upper border bent towards the outside of the
crate by an angle of at least approximately 90.
In this case, the upper borders are advantageously interrupted substantially
~acing the hollow angle posts, so that vertical angle sections can be placed
in the angles of the crates during their stacking on pallets and adopting a
conventional procedure.
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According to an original feature, the crate is advantageously made from a
transparent or translucent plastics material. This feature makes it possible
to easily check the products contained in a stack of pallets and in partic-
ular establish the nature, size, state of advance, etc. thereof, which is an
essential advantage compared with existing crates.
During the transportation of certain products such as salads, it may be
necessary to prevent photosynthesis. This leads to the use of an opaque
plastics material, which can easily be obtained by tinting or colouring the-
translucent plastics material, without it being necessary to place a colouredprotective paper in the crate.
In a preferred embodiment of the invention, the bottom, sides and posts of
the crate are formed in the same extruded, cut and bent, plastics material
strip.
A preferred embodiment of the invention is described in greater detail
hereinafter relative to the drawings, wherein show:
0 Fig. 1 A perspective view showing a plastics material crate according
to the invention.
Fig. 2 A larger scale, vertical sectional view of the crate of fig. 1.
Fig. 3 A vertical sectional view diagrammatically and partly illustrating
the stack of three crates according to the invention.
Fig. 4 A perspective view showing a plurality of crates according to the
invention stored on a pallet and held at their outer angles by
vertical angle sections.
In fig. 1, reference 10 designates in general terms a crate made entirely
~rom plastics material, according to the invention. This crate is preferably
made by extrusion and/or calendering, e.g. from two extruded sections in
3S accordance with a process comparable to that described in W0-A-92 09488. As
a variant, the crate 10 can also be manufactured by extrusion and/or calender-
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ing from a single section in the form of a cut, perforated, thermoformed,
bent and welded, planar strip.
The plastics material crate of fig. 1 can also be injection moulded and then
thermoformed. However, the cost is then significantly higher, particularly
due to the discontinuous nature of such a process.
The crate 10 of fig. 1 comprises a substantially planar, rectangular bottom
12, four planar, rectangular sides, including two lateral sides 14 and two -
end sides 16, and four hollow angle posts 18.
The lateral sides 14 are parallel to one another and rise at right anglesfrom the two opposite lateral edges of the crate bottom 12. In comparable
manner, the end sides 16 are parallel to one another and rise at right
angles from the end edges of the bottom 12. The bottom 12 and sides 14, 16
are produced from a planar, plastics material strip of limited thickness
(e.g. between approximately 0.8 mm and approximately 2 mm).
As a function of the type of crate, the height of the lateral sides 14 can be
less (as illustrated in fig. 1) or equal to that of the end sides 16.
The hollow angle posts 18 rise vertically from the four angles of the rect-
angle formed by the crate bottom 12, along junctions between the lateral
sides 14 and the end sides 16, over a height equal to that of the latter. The
posts 18 are hollow, i.e. they are traversed over their entire height by a
vertical passage making it possible to reduce the weight and plastics mater-
ial quantity required in the manufacture of the crate, as well as the cost
of the latter.
Each of the hollow angle posts 18 has in horizontal section the shape of a
right angled triangle, whose hypotenuse can be rectilinear, as shown in fig.
1, or slightly inwardly curved. The two sides of the right angle formed by
this right angled triangle are in contact with the sides 14, 16 in the
corresponding angle of the crate. In the embodiment illustrated in fig. 1,
the hollow angle posts 18 are obtained by bending, in the same plastics
material strip as that in which are produced the bottom 12 and sides 14, 16
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of the crate.
Bearing in mind the thinness of the strip in which are produced at least the
bottom 12 and sides 14 of the crate 10, said planar portions have a certain
S flexibility or elasticity. As a result the products, such as fruit, placedin said crate are not bruised. Thus, it is mainly the sides of the crate
which deform and not the products contained therein.
The bottom 12 and sides 14, 16 of the crate 10 according to the invention are
traversed by holes 20, whose shape, dimensions and distribution can vary very
widely. In the embodiment illustrated in exemplified manner in figs. 1 and
2, the holes 20 are circular and are distributed in the form of a triangular
spacing network over the entire surface of the bottom 12 and sides 14, 16.
An unperforated zone is advantageously provided on at least one of the sides
14, 16, so as to permit a marking of the crate, e.g. by silk screen printing.
This obviates the need for the addition of another material to the plastics
material from which the crate is made.
As is illustrated in greater detail in fig. 2, each of the holes 20 is surr-
ounded by a projecting portion 22 obtained by the thermoforming of the strip
in which are produced the bottom 12 and sides 14, 16. More specifically, the
projecting portions 22 are oriented towards the outside of the crate with
respect to the plane formed by the bottom and sides thereof. In the case
where the holes 20 are circular, the projecting portions 22 e.g. have a
truncated cone shape. However, a different shape can be adopted without
passing outside the scope of the invention.
No matter whether the strip constituting the bottom 12 and sides 14, 16 of
the crate is obtained by extrusion, calendering or moulding, the projecting
portions 22 are always produced by thermoforming, so as to prestress the
plastics material. The holes 20 and projecting portions 22 surrounding the
same fulfil a large number of functions.
The first of these functions is the ventilation of the products transported
in the crates. It should be noted that this ventilation can be produced on
demand because the shape, size and distribution o~ the holes 20 can vary very
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considerably without having any effect on the mechanical strength of the
crate.
A second function fulfilled by the projecting portions 22 surrounding the
holes 20 is that of rigidifying the strip forming the bottom and sides of the
crate. This rigidification is particularly important in the bottom of the
crate, whose deformation must not be excessive when filled, so as to avoid
fruit or vegetables of a lower crate being damaged by the edges of the holes
20 when the crates are stacked. However, the rigidification of the sides 14
and 16 must not be excessive, so that they maintain an adequate flexibility
or elasticity so as not to bruise the fruit. For this reason, the density of
the holes 20 will generally be greater in the crate bottom 12 than on the
sides 14, 16.
Another function results from the orientation of the projecting portions 22
towards the outside of the crate. This feature ensures that the products
contained in the crate are not in contact with the edges of the holes 20.
This avoids any risk of the products being damaged by said edges. It should
be noted that the shapes and dimensions of the holes 20 can differ as a func-
tion of the type of product transported in the crate and in particular as afunction of the size of said product, so that the aforementioned damage risk
is completely avoided in all cases.
The holes 20 and the outward orientation of the projecting portions 22 surr-
ounding them also permanently facilitate the outflow of water and any other
liquid such as products used for treating fruit and vegetables and which are
vital for preserving the latter.
Moreover, the edges of the holes 20 formed at the lower end of the projecting
portions 22 in the crate bottom 12 avoid the sliding of the crate when placed
on a conveyor. This feature is important, because the packing of fruit and
vegetables usually takes place on conveyor belts and its absence would lead
to dragging or slipping risks.
3S ,`1Oreover, the presence of holes 20 reduces the weight of the crates and
reduces the quantity of plastics material used in their manufacture and
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consequently their cost.
As is shown in fig. 3, at each of its angles the crate bottom 12 has a hole
20a, which can have the same shape and size as the holes 20 or a different
shape and size. The hole 20a is placed in the extension of the vertical
passage formed in the hollow angle post 18 rising above said angle. This
hole 20a enables water and other liquids liable to penetrate the said posts
to flow out by gravity.
As for the holes 20, at least two of the four holes 20a located in the angles
of the bottom 12 are surrounded by an outwardly, i.e. downwardly projecting
portion 22a from the bottom 12.
As is diagrammatically illustrated in fig. 3, this arrangement makes itpossible to position and maintain the crates 10 above one another when
stacked. Thus, the projecting portions 22a of each of the crates 10 then
penetrate the vertical passage formed in the hollow angle post 18 of the
adjacent, lower crate.
As has already been indicated, an excessive downward deformation of the crate
bottom 12, when the crates are filled with products, might damage products
contained in the adjacent, lower crate when several crates are stacked.
However, the production of the projecting portions 22 by thermoforming tends
to bring about a deformation of this type when certain plastics materials are
used. It is therefore recommended, at least in the bottom 12 and, if approp-
riate, in the crate sides 14 and 16, to produce by thermoforming at least one
unperforated cambering between the projecting portions 22 and which is
oriented towards the inside of the crate.
In the embodiment illustrated in figs. 1 and 2, in which the aforementioned
cambering is also provided on the crate sides, it is in the form of a plur-
ality of bosses 24 located between the projecting portions 22 and oriented
towards the inside of the crate. Like the projecting poctions 22, said
bosses 24 can assume various shapes, which are not limited to the spherical
cap shape shown in fig. 2.
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As a variant, the cambering of the bottom 12 and optionally the sides 14 and
16 towards the inside of the crate can be distributed over the entire surface
located between the projecting portions 22.
As illustrated in figs. 1 to 4, each of the four sides 14 and 16 has an upper
border 26 bent towards the outside of the crate 10 by an angle of at least
approximately 90. This feature makes it possible to reinforce and rigidify
the sides 14 and 16. It also eliminates any cutting risk for persons handl-
ing the crates.
As is in particular s'nown in figs. 1 and 4, the upper border 26 of each of
the sides 14 and 16 is interrupted before the ends of said sides, substan-
tially facing the hollow angle posts 18. The interruption is preferably
progressive, i.e. bevelled or rounded in order to once again provide any risk
of cutting for persons handling the crates.
When the crates 10 are stacked on pallets, this feature makes it possible to
place at the angles of the thus formed stack four vertical angle sections 28
(fig. 4) facilitating the packaging of said plurality of crates, e.g. by
means of a not shown, flexible plastics material sheet.
Advantageously, the plastics material from which the crates 10 is produced is
a translucent or even transparent material, which facilitates the inspection
of the products stored or transported in the crates. Thus, this feature
makes it possible to easily check the nature of the products, their size,
their state of advance, etc.
As a variant, the plastics material from which the crates 10 are produced
can also be opaque. For this purpose, it is advantageously possible to use a
mass-tinted, translucent plastics material. This feature is advantageously
used in certain special cases of transporting products requiring a protection
against p'notosynthesis, such as certain salads. It then avoids the need for
pLacing a tinted protective paper in the crate.
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