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DESCRIPTION

The present invention regards · a structural element made of corrugated cardboard. The present invention also regards a structure made of corrugated cardboard comprising such element. The present invention was obtained with particular reference to the support structures, such as for example those adapted for the transport of goods, such as pallets, or those adapted to maintain products in a predetermined position, such as for example display units or box- shaped support masks or packaging masks. However, it can also be used in any other field, for example for obtaining anti- impact structures to be inserted into packagings etc.

As known the corrugated cardboard comprises at least one sheet of corrugated paper. It guarantees a given resistance to the folding if stressed orthogonally to the grooves of the corrugation. This structural capacity, alongside the ecologic characteristics thereof, led to numerous applications, even including making pallets .

However, the applicant observed that in order to meet the necessary loading capacity required of pallets or known structures made of corrugated cardboard, binding several layers of cardboard up to obtaining a considerable thickness is a consolidated trend.

Firstly, the applicant points out that the construction method of the prior art requires the use of a large amount of material, hence leading to the waste of resources and increase of costs.

The applicant also observes that the known structures require various assembly operations, given that it is required to cut the cardboard and join the various layers with respect to each other, hence increasing the production times and cost of the required machinery .

The applicant also observed that the structures thus made reveal considerable dimensions and require large storage spaces, thus reducing the convenience for the production thereof. For the same reason the shipment of said cardboard structures to the end users is possible solely for a small number of samples at a time, increasing the final cost thereof.

Thus, a general object of the present invention is to fully or partly overcome the problems of the prior art .

A preferred object of the present invention is to provide a structural element with a high bearing capacity considering a small amount of corrugated cardboard. A further preferred object of the present invention is to provide a structure made of corrugated cardboard that is easy and inexpensive to obtain.

Another preferred object of the present invention is to provide a structure made of corrugated cardboard that requires a small number of machines or parts thereof for the obtainment thereof .

Another preferred object of the present invention is to provide a structure made of corrugated cardboard that can be stored in small spaces and shipped in large amounts at a time.

According to a first general aspect thereof the present invention regards a structural element made of corrugated cardboard according to claim 1, i.e. a structural element made of corrugated cardboard characterised in that it comprises at least two layers of corrugated paper each having a corrugation parallel to a guide line thereof, wherein the guide lines of the corrugations of the at least two layers are inclined with respect to each other.

Actually, the applicant experimented that such arrangements allows considerably increasing the structural capacity of the element thus reducing the layers of cardboard required for bearing a predetermined load.

Preferably the structural elements according to the present, invention comprise at least one contour line (25, 55), inclined with respect to both said guide lines. For example such line may be a cutting or folding line which creates discontinuity in the corrugation or due to the fact that it interrupts it, like the cutting, or due to the fact that it breaks both guide lines, like the folding. This allows an easier comparison of the structural element with other elements to exploit the bearing capacity thereof, for example creating ribs within the box- shaped structures. In the latter case, the contour of said structural element is preferably substantially square-shaped or rectangular.

Generally, the inclination between said contour line and at least one of the guide lines is preferably comprised between 30° and 60°, and more preferably it is equal or substantially equivalent to 45°.

In some preferred embodiments, the layers of corrugated paper are arranged resting on each other in a predetermined plane, for example coinciding with one or more flat sheets, such as cover sheets.

According to a preferable general characteristic of the invention said at least two layers of corrugated paper belong to the same folded corrugated cardboard sheet. This allows providing for fewer construction steps for obtaining the structural element.

According to a second aspect thereof, the present invention comprises a structure according to claim 6, i.e. a structure made of corrugated cardboard, characterised in that it comprises at least one box- shaped portion comprising at least one structural element of the previously indicated type.

Thus, the box- shaped structure is much more resistant to loads and impacts, and thus much more reliable .

For example said structural element is arranged so as to transmit a predetermined load between at least two opposite sides of said box-shaped portion and/or so as to form a support plane. In case of transmission of loads it is preferably contained in at least one chamber thereof .

According to particularly advantageous embodiments said box- shaped portion and the at least one structural element are obtained by folding the same corrugated cardboard sheet according to at least one folding line. Thus, the sheet may be provided with a folding pattern and stored or shipped to the end consumer in non-folded form, so as to occupy least space possible and require lesser workforce, thus considerably reducing costs .

Said sheet preferably comprises at least one layer of corrugated paper with corrugations parallel to a predetermined guide line, wherein said at least one folding line is inclined with respect to said predetermined guide line by an angle substantially different from 90°, preferably such angle is comprised between 30° and 60°, more preferably it is substantially equivalent to 45° .

For example said structure obtained using the sheet comprises a plurality of folding lines which define at least two portions of corrugated cardboard intended to be superimposed to form the at least one structural element, preferably said portions are held in superimposed position by means of at least one tab inserted into a slot.

It is observed that preferred examples of structures according to the present invention include pallets and/or support masks and/or display units.

According to a third aspect thereof, the present invention regards a corrugated cardboard sheet according to claim 11, i.e. a corrugated cardboard sheet comprising at least one layer of corrugated paper with corrugations parallel to a predetermined guide line, said cardboard sheet comprising at least one folding line, characterised in that said at least one folding line is inclined with respect to said predetermined guide line by an angle substantially different from 90°, preferably such angle is comprised between 30° and 60°, more preferably it is substantially equivalent to 45° . Generally, it is preferable that said corrugated cardboard sheet comprises a plurality of folding lines inclined with respect to said predetermined guide line by an angle substantially different from 90° , preferably comprised between 30° and 60° , said folding being arranged according to a folding pattern which allows forming at least one box- shaped structure made of corrugated cardboard.

Such sheet is advantageously provided with one or more foldings for obtaining a predetermined structure, said structure does not require to be realised in a factory, but the sheet may be stacked to be stocked and shipped in an unfolded configuration and folded subsequently according to the folding lines provided for therein to form the structure solely when needed.

For example said folding pattern allows folding the sheet to form a pallet and/or a support mask and/or a packaging mask and/or a display unit comprising said at least one box-shaped structure.

For example said folding pattern allows forming at least two portions of sheet superimposable with the guide lines of the relative wave portions of the at least one layer of corrugated paper inclined with respect to each other, preferably substantially of 90° .

Said portions are superimposable for example to form at least one structural element contained in said at least one box- shaped structure, further preferably said folding pattern allows forming at least one cardboard flap foldable and positionable so as to hold at least some portions of the box- shaped structure and/or of the structural element in a folded configuration, wherein preferably said at least one flap can be coupled in a point of said box- shaped structure different from and comprised between the centre and the ends of said box- shaped structure. Said coupling for example occurs by inserting a tab in a slot. For example the point of coupling is between the centre and one of two ends, opposite according to a main longitudinal direction of the box- shaped structure. For example it is substantially two- thirds or three -fourths of the box- shaped structure according to said main longitudinal direction of development .

According to some preferred embodiments said sheet comprises a plurality of flaps foldable according to said plurality of folding lines to form said at least one box-shaped structure and/or said at least one structural element, wherein at least some of said flaps are foldable according to folding lines orthogonal with respect to each other, and wherein said flaps are intended to exploit at least the same retention point so as to be held in folded position, preferably said retention point is substantially in a position different from and comprised between the centre and the ends of the box-shaped portion, even more preferably said point is a retention point for all foldable flaps forming said box- shaped structure and/or said structural element, and it is preferably a cross-shaped slot.

According to a fourth aspect thereof, the present invention comprises a sheet according to claim 17, i.e. a corrugated cardboard sheet comprising at least one layer of corrugated paper with corrugations parallel to a predetermined guide line, said sheet comprising a plurality of cutting lines, characterised in that at least two of said cutting lines are inclined with respect to each other and said predetermined guide line is inclined with respect to both. Thus advantageously it is not necessary to provide special machines for implementing the invention but it can be obtained by shaping a conventional cardboard sheet by cutting it with the machines currently available in the market. For example the cutting may be of the punching, plotter, laser cutting type.

Further characteristics and advantages of the present invention shall be clearer from the following detailed description of the preferred embodiments thereof, provided with reference to the attached drawings and provided by way of non-limiting example, wherein:

Figure 1 schematically represents - in perspective view - a common corrugated cardboard sheet, in which some parts were removed for descriptive clarity purposes ;

figure 2 schematically represents - in perspective view - a structural element according to the present invention, in which some parts were removed for descriptive clarity purposes;

- figure 3 schematically represents a structure made of corrugated cardboard comprising the structural element of figure 2;

- figure 4 schematically represents a pallet made of corrugated cardboard comprising the structural element of figure 2 ;

- figures 5 to 10 schematically represent the steps of folding a punched corrugated cardboard sheet for obtaining the pallet of figure 4.

- figures 11 to 13 schematically represent the steps of folding a punched corrugated cardboard sheet for obtaining a second type of pallet;

- figure 14 represents - in an extremely schematic manner - a box-shaped support mask according to the present invention;

- figure 15 represents - in a schematic manner - a specific embodiment of a support mask like the one of figure 14; and

- figure 16 schematically represents a packaging mask according to the present invention.

With reference to figure 1 a common corrugated cardboard sheet 1 is shown, which can be used as a base for obtaining the present invention. The corrugated cardboard sheet 1 comprises at least one sheet of corrugated paper 5, commonly referred to as "wave", interposed between two flat paper sheets 10, commonly referred to as "covers" . The wave grooves develop parallel to a guide line L.

Figure 1 shows only one wave 5, actually even more than one corrugated sheet arranged each to form a layer of corrugated paper may be provided. The most common corrugated cardboard sheets have 1, 2 or 3 layers, and thus referred to as single, double or triple wave. In this case, the waves of a sheet have guide lines parallel with respect to each other. Hereinafter, reference shall be made to a single wave cardboard for the sake of simplicity, but this does not exclude the presence of more layers of corrugated paper.

With reference to figure 2 there is shown a structural element 15 according to the present invention obtained through two sheets of corrugated cardboard 1 like the ones of figure 1.

The structural element 15 comprises two layers of corrugated paper 5 obtained by superimposing the two sheets of corrugated cardboard 1. The waves 5 have a guide line LI and L2 thereof, inclined with respect to each other. Thus reference may be generally made to structural elements of the present invention as elements made of corrugated cardboard comprising at least two "crossed waves" .

Preferably the inclination a, measured for example between the projections of said guide lines on one of the cover planes 10, is substantially comprised between 45° and 135°, and it is preferably substantially equivalent to 90°.

In this case, two covers 10 are interposed between the layers of corrugated paper 5.

The corrugated cardboard sheets 1 are preferably arranged resting on each other, in a support plane which coincides with the internal cover sheets 10, with suitable means, for example through mechanical means, such as tabs inserted in slots, other cardboard parts that keep them adjacent, or by means of glue, preferably interposed between the two cardboard sheets 1.

Actually, the preferred embodiments of the structural element 15 are those in which a single sheet 1 is folded so as to obtain at least one superimposition of two parts forming the structural element 15 instead of superimposing two sheets 1. The advantages of this technique shall be clearer hereinafter when the pallet folding technique shall be illustrated in figures 5 to According to valid but more expensive embodiments, in that they would require special machines, there is provided for a sheet capable of previously containing the crossed waves, directly lying on each other or by interposing one or more flat paper sheets.

As observable, the structural element 15 is delimited by a contour 20, which interrupts the waves 5, and comprises at least one cutting line 25, or at least one folding line, or at least both, for example a square- shaped or rectangular perimeter. Said cutting or folding line is inclined with respect to both guide lines LI and L2 of the waves 5. Preferably the inclination is equivalent to an angle β comprised between 30° and 60°, more preferably equivalent or substantially equivalent to 45° .

With reference to figure 3, a box-shaped structure 30 of corrugated cardboard is shown comprising a structural element 15 like the one of figure 2. Some parts were removed for the sake of clarity.

The box- shaped structure 30 comprises a chamber 32 which contains the structural element 15, in particular it is traversed thereby, preferably so as to be divided into two sub-chambers 33 and 34. For example the structural element 15 forms a rib which traversed the box-shaped structure 30 at half the chamber 32, i.e. dividing it into two equal sub-chambers 33, 34. More generally, the structural element joins, with respect to each other, two opposite sides 36 and 37 of the box- shaped structure 30, one of which being intended to bear a load and the other being intended to be placed on the ground. Thus, the structural element transmits part of the load between the two sides of the box-shaped structure and contributes to increase the bearing capacity thereof.

The structural element 15 is shaped so as to comprise at least one tab 40 capable of being inserted in a corresponding opening 42, for example slot-shaped, preferably obtained on the side 36 intended to bear the load. It is also observed that the tab 40 has crossed waves, with guide lines both crossed with respect to the slot 42.

As observable in the illustrated example, the box-shaped structure 30 has main rectangular faces, which define a main direction of development X, coinciding with the long sides, the box-shaped structure further terminates at ends 51, opposite according to said development line X.

Figure 4 shows a structure 50 made of corrugated cardboard comprising the box- shaped structure 30 of figure 3 as a portion thereof, in particular a pallet is shown with two box- shaped structures 30 joined by a support plane 45 which joins the two sides 36 thereof.

The pallet 50 is obtained from a single corrugated cardboard sheet 60 shaped and folded as described hereinafter with reference to figures 5 to 10.

Figure 5 in particular shows the sheet 60 in an open configuration, in which the folding pattern is visible. It comprises a plurality of folding lines 55 and at least one wave (not visible) with the guide line thereof L inclined with respect to at least one of them by an angle substantially different from 90° , and preferably comprised between 30° and 60°, more preferably substantially equivalent to 45° . More generally it is preferable, like in the shown example, that the folding lines comprise at least two lines substantially orthogonal with respect to each other and both inclined with respect to said guide line L. Even more generally it is preferable that all the folding lines 55 are inclined with respect to the guide line L with respective angles substantially different from 90°, preferably comprised between 30° and 60° and even more preferably substantially equivalent to 45° .

The edge 20 comprises a plurality of punching lines 25, also inclined with respect to the guide line L like the folding lines, more preferably all the punching lines 25 are inclined with respect to the guide line L.

The folding lines 55 outline a rectangular central portion of the sheet 1 which corresponds to the support plane 45. Parallel to each of the short sides thereof, the folding lines 55 outline a flap 54 foldable to form three rectangular end portions 56, 57 and 58, intended to form parts of the respective box-shaped structures 30. The more distal portions 58 in particular are intended to form respective first structural elements .

Figure 6 shows the folding thereof to form the first semi -chamber 34 of one of the two box-shaped structures 30.

The distal end edge of the most distal portion 58 comprises two fins 60 and 61, inserted in respective retention slots 62 and 63 obtained on the plane 45. As observable, the slot 62 is cross-shaped.

The figure also shows that the folding lines 55, alongside the predetermined cutting lines, laterally outline - at the long sides of the plane 45 - a series of four flaps 65, 66, 67 and 68 foldable independently from each other. It is observed that the flaps 65 and 68 arranged at the end of the series have a different extension with respect to each other in the direction orthogonal to the long sides of the plane 45, while the other two flaps 66 and 67 have a different extension with respect to each other in the direction parallel to the long sides of the plane 45. Each of the latter flaps 66 and 67 can be folded to form three rectangular portions 70, 71, 72, 73, 74 and 75.

As observable in the sequence of figures 7, 8 and 9 they are intended to form each a part of the second semi-chamber 33 of each box-shaped element 30.

As observable in particular from figures 7 and 8, the longer flap 68 comprises two fins 78 and 79 inserted in the same retention slots 62 and 63 described above. Thus, the most distal portions 58 and 75 of the flaps 54 and 68 are superimposed forming part of the first structural element 15. The other part of such structural element 15 is obtained by superimposing the most distal portions 58 and 72 of the flaps 54 and 67.

In the sequence of figures 8, 9 and 10 it should be observed that the end flaps 66 and 69 are foldable each in three portions to form blocking fins of the box- shaped structure 30. In particular, the most distal portions 80 and 81 are inserted in a groove 83, formed in the box-shaped structure 30, for positioning thereof by means of respective end tabs 84 and 85 thereof in the cross-shaped retention slot 62. As observable, the most distal portions 80 and 81 of the flaps 66 and 69 form a second structural element 15' transverse to the longitudinal development plane of the box- shaped element 30, and thus also useful for bearing lateral impacts. Generally, it can be stated that some preferred embodiments of the present invention, including the shown one, exploit at least the same retention point 62 for a plurality of flaps 54, 66, 67, 68, 69 foldable according to directions orthogonal with respect to each other, wherein said retention point is substantially in a position different from and comprised between the centre 90 and the end 51 of the box-shaped portion 30. Preferably said point 62 is a retention point for all foldable flaps forming said box-shaped structure 30. The retention point preferably is arranged substantially at two-thirds or three-fourths of a side 36 longer than the box-shaped structure 30. Even more preferably such point corresponds to a cross-shaped retention slot.

Generally, it should be observed that the tabs of the two portions can be deemed adjacent inserted in the same slot as a single tab of the structural element 15 or 15' .

The two box- shaped structures 30 of the pallet 50 are obtained in the same manner.

As observable, the pallet 50 may advantageously be stored and/or shipped to a final consumer in form of an unfolded sheet, i.e. not folded, so as to occupy the least space possible. Actually, it is thus possible to stack a larger number of pallets 50, with respect to the previously folded pallets. Described here below are some alternative embodiments of the invention wherein equivalent or similar elements shall be indicated using the same reference numbers used above increased by 100 or by a multiple thereof.

With reference to figures 11 to 13 the sequence for folding a corrugated cardboard sheet 101 is shown for obtaining a second model of a pallet 150 different from the pallet 50 of figure 5 due to the fact that it comprises a support plane 170 which projects beyond one of the two box-shaped structures 130.

In order to obtain the pallet 150 the sheet 101 comprises a folding pattern which outlines a second central rectangle 145' arranged adjacent to the rectangle 145 and which can be folded on itself. Both are intended to form the support plane 170 and in particular the second rectangle 145' corresponds to the projecting part of the plane 171. It should be observed that the part of the plane 171 comprises crossed waves, and thus it is also a structural element according to the present invention, intended to form a support plane.

The remaining parts of the sheet substantially correspond to those of the previous example and thus shall not be addressed further hereinafter.

With reference to figure 14, a structure 230, in particular box-shaped is shown, which differs from the box- shaped structure 30 of figure 3 due to the fact that it comprises on at least one face 236 thereof at least one seat 280 for housing one or more predetermined objects (not illustrated) that the structure 230 is intended to support. Said housing seat 280 is preferably shaped so as to perfectly fit with the profile of at least part of said predetermined object. The box-shaped structure 230 comprises at least one structural element 215. It may be referred to as a "support mask" and it can for example be used for supporting objects passing in a production chain, or to maintain them in position in a packaging box, or as a display unit.

Figure 15 shows a specific example of a box- shaped support mask 330 traversed at the centre by a structural element 315 regarding which only the tabs projecting from the slots are observable. The face 336 comprises various housing seats 380.

Lastly, figure 16 shows a packaging mask 430, i.e. adapted to be inserted into packaging boxes for maintaining a packaged object in a predetermined position. In this case, the structural element 415 is made up of a pair of superimposed flaps which form a support plane 436, on which a housing seat 480 is obtained.

Generally, it should be observed that should the sheets of corrugated cardboard be used for obtaining the present invention have more than one wave, it is sufficient that at least one meets the aforementioned inclination requirements, however, it is not excluded that more than one of them meets such requirements, thus reinforcing the effect.

Generally, it should also be observed that the expression "substantially" should be intended as a 10% tolerance with respect to the indicated value, while the expression "substantially different" shall be intended to mean at least 10% more or less the indicated amount.

Obviously, the embodiments and variants described and illustrated up to now are purely by way of example and it shall be subjected, by a man skilled in the art, to meet specific and contingent needs, to numerous modifications and variants, for example including the combination of said embodiments and variants, all falling within the scope of protection of the present invention as defined by the following claims.