Stackable cardboard tray

Abstract: The tray comprises a base part, in the shape of a small cask, forming the bottom panel (1) of the tray with an upwardly extending peripheral flange (2) to which is attached one or more parts (3) that form the four sidewalls of the tray. Additional elements (4) may be added to the sidewalls to enhance structural stiffners. According to a further aspect of the invention, the plane of the bottom panel lies below the lower most edge (3a) of the sidewalls, providing a stepped portion which may be received into the open upper end of an underlying similar tray to provide a positive stacking means, the upper edge of the sidewalls (3c) of the underlying tray supporting the lower edge (3a) of the sidewalls of the overlying tray. The bottom panel and sidewalls may be formed from differing densities of cardboard.

Description: OBJECT OF THE INVENTION The present invention relates to a new type of tray or pile up box, made on the basis of compact cardboard, fundamentally intended for the transportation of perishable goods such as fruits and vegetables. The present invention specifically relates to a tray made on the basis of compact cardboard pieces joined by glue, of the type that are composed of a base, two larger walls and two smaller walls, wherein the said base has flanges at each of its corners that serve as joining for the corresponding lateral walls, the said flanges being longitudinally over-sized with the object to provide reinforced zones in the corners and walls of the box. A tray of said type is described in ES-U-252 456 on which the preamble of claim 1 is based. BACKGROUND OF THE INVENTION At the time of designing a new tray of the type mentioned above, a number of conditions that assure a good level of features must be considered and in this sense the tray must be resistant, easy to handle, to alow a good presentation of the product to be packed on it, and finally recycleable. Relating to the first condition, that refers to the resistance, the tray must be capable of holding the weight of the product without suffering any deformation on its bottom part, it must hold the stillness pile up, it must have a high compression capacity, in accordance with the weight to be hold and to the pile up number required, it must be capable of dynamic piling, meaning the vibrations and movements to which is going to be subject of, it must be capable of remisting the handling, stockage and transportation conditions, specially to the effects of the environmental humidity, that in the case of cold storage rooms on which this type of trays are place could reach the 90%. About the second condition, that is to say its handling, the tray must offer the possibility of being served mounted, as it is required by the small users, or as well as dismantled as it is required by the large users, that have their own places where it is desirable the use of small machines, light and with the greater automatation possible. Relating to the third aspect the tray must offer excellent conditions for high quality printing and finally, from the point of view of its recycability, it must devoid the elements that make this condition difficult as for example staples or any other non recycleable materials. There are today in the market two basic types of boxes or pile up trays, one is the one that the wood is the raw material, and the other is the one that uses cardboard. The trays of the first type, the ones made of wood, although they pass the first aspect that is the resistance they do not satisfy any of the other aspects priorly mentioned, because it is not easy to handle, neither offers the possibility of a high quality printing and it is not recycable at a lower cost. Within the second group, there are many types of well kown cardboard trays or made of any other similar material, generally from a plate properly shape, with folding lines that define the bottom of the tray, from which elongate the winds that, when forming the tray, will become the sides of the tray. This type of trays shows some problems for its manufacturing, owing to the difficulty of the operations needed for the construction of the tray and the joining between the adjacent edges of its sides on the corners of the tray. Furthermore, this type of trays are not resistant enough to the compression support that are going to be subject of when loaded with the goods and pile up. This weakness comes from the difficulty of making the foldings that show this type of trays, to do this operation, cardboard must be used specifically undulating cardboard, that besides offering a low level of resistance is highly absorbent to humidity, what means a quickly damage of the tray. In many cases, to reinforce the tray the method used is the placing of additional pieces, particulary placed on the corners. The faces of the tray are also reinforced with bended flanges over the faces of the tray. This procedure complicates and pull up the cost of production of the tray and, in most of the cases the trays do not gain the necessary resistance. Another problem inherent to the conventional trays formed by a single piece, focus on the fact that for the graphic printing over the mentioned trays, the entire tray must be passed through the printing machine even if the printing is very small or it must be printed on a very small zone of the tray. Patents GB-A-783 801 and FR-A-836 645 are known, relating to boxes for the transportation of different goods, made up by corrugated cardboard, the said boxes by means of the assembly and subsequent gluing of individual pieces make the box shape. ES-U-252 456 as the most pertinent prior art discloses a stackable tray for carrying goods especially perishable goods such as fruits and vegetables, of the type having a bottom wall and a peripheral wall including two side walls and two end walls which are higher than the side walls. It is in essence made from a single cardboard blank. Likewise and in the name of the same owner of the present invention, are known ES-2055 812 and ES-Utility model 1021847 which constitute further pertinent prior art documents with respect to the object of the present invention. This type of boxes or trays are structured by a base piece with small cask shape, being designed to be the bottom of the tray in which a rising double marginal flange is provided and to which at least another piece is joined, piece that is part of the side walls of the tray, walls that despite the fact could be made of two or four pieces, and even of other complementary pieces that work as the support for the vertical edges. In the trays of this type, the mentioned small cask is placed inside of the piece or pieces that form the side walls of the tray, overhanging with respect to the lower edge of the pieces that form the side walls of the tray, so that during the pile up between trays, the bottom part of each of them is assembled to the mouth. It foresees that the side walls of the tray could be provided with folding flanges, that will fold towards the inside of the tray and fixed by glue, intended to provide more resistance to the mentioned tray. The structuration of the multi-piece of the tray allows the use of pieces of different thickness, with the purpose of raising the mechanic resistance of the tray where needed. The pieces that form the side walls of the tray, could present in their lower edge separate notches and in their upper edge rising wings complementary to the others, and which are foreseen to fit together during the pile up of the trays. It foresees the possibility that the vertical edges of the tray would be arched and cross-section. It is also possible that the vertical edges of the tray would present a feather-edge shape. The bottom of the tray may be provided with inside marquetry rising to the outside, and the support plate cuold be glued to this rising marquetry covering the entire bottom. Likewise Spanish Utility Model 1021847 describes a tray that said presents correspondence with the vertex of its bottom wide bevels, presenting the marginal flange that determines the cask form for the mention bottom a height cosiderably higher in these bevels, while the side walls of the tray, that can be obtained from one or more pieces, also present a correspondance with these bevels, folds over themselves that determine on the corners of the tray a remarkable thickness because the resulting three layers of the wall. DESCRIPTION OF THE INVENTION The pile up tray that this invention presents has been designed and arranged in order to solve in a successful way the problems mentioned before. In order to do so and in a more specific way, the mentioned tray is characterised by the features of claim 1. Specifically the structuring of the tray is based on a specific realization on which five pieces take part, one that forms the bottom and the other four form the side walls, with the special particularity that two of these last ones, set up against each other, present in their edges elongations to provide wings from folding cross lines, which end up superposed and glued to the other sides of the tray , covering them totally. The mentioned sides in second place present elongations with folding wings shape in its edges, from folding cross lines, which end up superposed and glued to the edges of the sides of the tray mentioned in first place. The bigger sides of the tray are provided, along the upper edge with flanges bended and glued over the inside surface of the corresponding side, this bigger sides present in their edges the folding flaps, glued over the outside surface of the smaller side of the tray, covering it totally. The upper edge of the smaller sides is provided with rising wings, that are equal in shape and positioned with the notchs provide in the lower edge of the same sides, that can be inserted between themselves when piling up the trays, avoiding the movement of the trays when pile up. The wings that appear from the edges of the smaller sides present in their upper edge rising wings that correspond with the cuts provided on the bottom of the tray, next to the flanges of this bottom. These wings and cuts fit between themselves when piling up the trays, cooperating on the immobilization. As well as the bigger sides the small sides of the tray fold down to the level of the bottom of the cask, or what is the same, of the tray as a hole. According with the above specification, the procedure for the making of this type of tray consists of obtaining by forging the piece that forms the bottom of the tray, provided with correspondence with its edges with other marginal flanges that fold from the folding lines that limit the shape of the bottom, and at the same time by forging, the strips or pieces that must formed the lateral sides or walls of the tray, with its coresponding edge wings, provided with cross lines to fold. These strips or bands are glued along the flanges of the bottom. Later two of the opposite faces or sides are bent from the folding lines in a raising position, and at the same time the corresponding elongations are bent as wings, by its folding lines. Next the other two sides and their corresponding wings are bent as it was described before, until the wings of each side are superposed and glued to the adjacent edges of the adjoining sides. Finally it has been also foreseen the possibility that the bands corresponding to the faces of the tray will be slightly oversized, and provided in those portion corresponding to the bevels of the corners, with a double folding line at a medium level, such that the adaptation of these elongations of the sides to the strips of the bigger side walls and corresponding elongations of the same, the said oversize of the first force them to a inside deformation and consequent separation of the section corresponding to the second ones, that form one of the hollow columns forecast to facilitate the dovetail joint between trays, during the piling up of the same. Optionally this oversize of the strips could be considerably greater, so that by a folding of the same over the portion corresponding to the mentioned hollow columns, these become solid. With this a reinforcement during the pile up of the trays is obtained parallel with respect to the guiding effect that has been mentioned before. Additionally the bottom of the trays provide as well as the said bevels with wide noches which coincide in size and shape with the section of the hollow columns, which present an upper projection, preferably with trapezium isoscelic shape, intended to be placed in the notch of the next upper tray, in the pile up between trays. A important characteristic achieved with this invention is the optimization of the printing operation, because it is formed from different and independent pieces, which could be printed according to the wishes of the client and the necessities of the tray, that is to say that to the printing machine. DESCRIPTION OF THE DRAWINGS In order to provide a detailed description and to contribute to the complete understanding of the characteristics of this invention, a set of drawings is attached to the specification which, while purely illustrative and not fully comprehensive, shows the following: Figure 1.- Shows a perspective view of the basic components from which the stackable tray is obtain, according to the realization forecast for this purpose. Figure 2.- Shows a similar view of the last figure but showing the components glued between themselves. Figure 3.- Shows a perspective of a first glueing stage of the two end walls of the tray of figures 1 and 20. Figure 4.- Represents the final stage of the manufacturing process of the tray, once the respectives sides and flaps are folded and glued. Figure 5.- Shows a detail in section of the plane V of the figure 4 at a bigger scale. Figure 6.- Shows a detail in section of two trays according to the plane VI of the figure 4, just before being piled up. Figure 7.- Shows a similar view of the one in figure 6, showing the trays already piled up. Figure 8.- Finally shows, a detail in section by the plane A-B of the figure 4, showing two trays piled up. Figure 9.- Shows a quartering in perspective of a pile up tray manufactured according to one variant of realization modify with respect to the figures 1 to 8. Figure 10.- Shows the set of pieces of the last figure properly assemble, also according to a perspective view. Figure 11.- Shows the set of pieces from the last figure but during the intermediate stage of the manufacturing process. Figure 12.- Shows, also according to a perspective view, the tray at the final stage of the process. Figure 13.- Shows a enlarge detail of one of the corners of the tray of the figures 9 to 12. Figure 14.- Shows a detail in section of two trays piled up, also at the level of one of its vertex and according with the cutting line A-B of the figure 12. Figure 15.- Shows a detail in perspective of one of the corners of the box, similar to the one of the figure 13, but according with the variant of realization on which the column formed in the mentioned corner is solid. Figure 16.- Finally shows a detail in cross section of the set represented on the last figure according to the cutting line C-D of the mentioned figure. PREFERRED EMBODIMENT OF THE INVENTION The pile up tray according to the invention is obtained from a cardboard plate (11), of rectangular shape, with folding lines (12) and (13), parallel and next to the sides of the plate, that define a folding marginal flanges (14) and (15) placed arround the bottom wall (11), that will form the bottom of the tray to be built. In the angles of the bottom wall (11) there are folding wings (12a). The sides of the tray are formed from two strips (16) of cardboard, that constitute the two sides walls and another two strips (17) that form the two end walls. The side wall strips (16) present along their upper edges, longitudinal flanges (18) bent and glued over the inner surface, with it's extremities (18a) bevel cut. Both strips (16) and (17) present folding lines (19) with transversal way, that define the end flaps (20) on the strips (16) and (17). The end flaps (20) are bigger than the end flaps (21), and between each pair they have the same length as the strips (17). The manufacturing procedure consist of glueing the lower edge of the strips (16) in the marginal flanges (14) and of the strips (17) in the marginal flanges (15) (figure 2). Once this set is formed the next step consist of folding the strips (17) and their end flaps (21) (figure 3). Next the strips (16) are folded and then the end flaps (20), glueing the end flaps (21) on the inner surface of the edge of the strips (16) and the end flaps (20) over the outside surface of the end walls (17), which are totally covered (figure 4). The glue of the flaps could be done previously to the described operations, by using Thermoactive glue, or as well during the performance of the operations. THe described manufacturing process is very simple, outstanding that the process is carried out from five pieces of cardboard: The bottom wall (11), two strips (16) and two strips (17). This allows to obtain the bottom wall (11) with a different thickness of the strips (16) and (17), in function of the resistance to be supported. Also allows the realization of the printing process of the strips (16) and (17) in an easier way than over the known trays, because it allows the introduction of single strips, easy to handle, instead of the entire plate, as it happens with prior realizations, that present a lot of difficulties for its handling. With respect to the configuration of the obtained trays, it should be recalled that the strips (17) and their end flaps (21) present in their upper edge rising flaps (22) and (22a) respectively. On the lower edge of the mentioned sides there are notch (23) complementary in position and shape with the mentioned wings. Furthermore, the bottom wall (11) of the cask presents next to its corners openings (24) whose position correspond with the position of the flaps (22a) of the end flaps (21). Thanks to this disposition when piling up the trays, the flaps (22) assembled in the notchs (23) and the flaps (22a) in the openings (24) with the purpose of immobilize the pile up trays (figures 6, 7 and 8). It must be emphasized that the notchs (23)stay in a hide position, because the strips (17) are placed between the end flaps (20) by one side and the flanges (15) by the other side. This avoids the wings assembled with the notchs to leave the pile up positioning. On figure 6 it can be observed how the extremity (18a) the flange (18), the extremety of the flange (14) and the extremety of the flap (21) assemble, all of them glued over the inner surface of the strips (16). Thanks to this disposition, the strips (16) are reinforced by the described components. Concerning the strips (17), they are doubly reinforced by the flanges (15) and the end flaps (20). Definetively, the trays obtained present characteristics of resistance to efforts and commpresions that allow to pile them up one they are loaded, without danger of being deformed Finally and according to a particular embodiment of the tray, the one represented on figures 9 to 14, the bottom wall (11) of the cask presents next to its corners various recesses (25) of considerable size, while the flaps (21) in their section corresponding to the two folding lines (19) that limit the section corresponding to the mentioned bevel, other two folding intermediate lines (26), parallel to the last ones, and between themselves an upper elongation (27) and a lower and complementary notch (28), being also this section of the elongations (21) comprised between the folding lines (19) lightly oversized in its wide with respect to section also correspoding to the bevel of the flaps or elongations (20) limited by the folding lines (19) similar to the object that in the forming of the box and as it is seen specially on the figure 13, in the areas of the bevels are defined hollow columns, whose section coincide with the shape and size of the notchs (25) that are found in the cask or bottom wall (11) of the same, so that in the pile up between boxes and because at the same time it is seen in the section of the figure 14, the upper elongations (27) of the opening of each box, go across the notchs (25) of the box immediately above, until reaching the top of the notchs (28) of the stiffness columns of this last one, what makes easier considerably the handling of the pile up because it generates a self-centering positioning between the boxes or trays. Optionally the section of the strips (17) comprised between the folding lines (21), can be considerably more oversized and affected by the plurality of folds (29) that, as it is seen on figures 15 and 16, transform the mentioned columns of the vertical edges of the box in solid elements, what means, parallel to the mentioned guiding effect, a remarkable stiffnes of the tray structure at the level of the vertical edges , that improves the piling up conditions of the tray. It has also been forecast the existance in each of these folds (29) of a double bevel edge in its upper extremity, determinant for each of the folds of a angle supplement (30) and, for the column as a hole, of a "sharpening" that makes easier the hadling of the pile up of the tray. As regards the strips (17) they are doubly reinforced by the flanges (15) and by the flaps (20). The advantages of the trays according to the invention are: Simplification in the manufacturing process, with respect to the usual processes in which the start begins with forging plates, with folding lines that must be bent, assembling or glueing flanges, flaps or any other components. This simplification also affects to the way by which the means of assemblage by superposition are obtained much more simple than of the trays obtained by the other known manufacturing methods. Greater resistance to compression, particularly when the trays present arch vertical edges. This resistance can be increased by joining the strips glued to the inner side or outside of the edges of the tray, the folds (4a), or to the columns. Thanks to the arch vertical or bevelled edges it is possible to avoid hits and rubbing while handling the trays. A lower cost of the tray because it is possible to obtain the bottom piece of a specific quality and the walls of a greater quality, with the purpose of printing on its outside surface. The printing of the side walls, of the tray is easier and cheaper with respect to the printing of the sides of the trays of a single piece, because is much easier to handle with the bands than a piece of greater size, as it is the case of the known trays.

Claims: A stackable tray for carrying goods, especially for perishable goods, such as fruit and vegetables, of the type having a bottom wall (11) and a peripheral wall comprising two side walls (16) and two end walls (17), the end walls being higher than the side walls, characterised in that it is made of compact cardboard parts joined with glue, and the bottom wall (11) is provided with marginal flanges (14, 15) at its four sides, which marginal flanges are folded substantially perpendicular to the plane of the bottom wall (11), the parts (16) and (17) making up the peripheral wall of the tray being secured to the marginal flanges (14, 15) of the bottom wall, so that the bottom wall lies flush with the lower edges of the peripheral wall, in that the parts making up the side walls are provided on their upper edge with flanges (18) which are folded and secured to the inner side of said side walls, the said parts being also provided with end flaps (20) which are folded substantially perpendicular to the plane of said side walls and secured to the end walls, covering them entirely and thereby defining end walls of double thickness. A stackable tray for carrying goods as in claim 1, characterised in that the side walls (16) are provided, along the upper edge, with flanges (18) folded and glued onto the inner surface of the respective face, these side walls having folding end flaps (20) and their ends glued onto the outer surface of the end walls (17) of the tray which they cover entirely. A stackable tray for carrying goods, as in claims 1 and 2, characterised by the fact that the top edge of the end walls (17) is provided with projecting flaps (22), their shape and position corresponding with the notches (23) provided on the lower edge of said end walls and fitting into one another upon the trays being stacked. A stackable tray for carrying goods, as in claims 1 and 2, characterised by the fact that the wings (21) extending at the opposite longitudinal ends of the end walls (17) have projecting wings (22a) on their top edge which correspond in relation to cutoffs (24) provided on the bottom of the tray, next to its flanges. A stackable tray for carrying goods, as in claims 1 and 2, characterised in that the dish that makes up the bottom wall (11) of the box, at the chamfers on its corners, is provided with extensive notchings (25), and the wings (21) extending from the strips (17) and corresponding to the end walls, have their first sector comprised between fold-lines (19) which are slightly oversized with respect to the corresponding sector of the wings (20) extending from the strips (16) corresponding to the side walls of the box, said wings (21) being moreover provided at their sector comprised between the likewise aforesaid fold-lines (19) to have two further intermediate fold-lines (26), together with an upper extension (27), which is preferably shaped as an isosceles trapezoid, and a lower complementary notch (28), such that upon fixing said strips to each other and level with the chamfers on the corners of the tray two hollow columns are defined, which have an isosceles trapezoidal cross-section matching that of the notchings (25) which may be crossed by said upper extensions (27) of the columns of the box lying right beneath it, when the trays are stacked, and in that the shape of said extensions (27) which converge towards their free ends fosters their guidance and fitting into the notchings (25), and hence stacking between trays. A stackable tray for carrying goods, as in claims 5, characterised in that a plurality of folds are defined in the sector of the strips (17) corresponding to the end walls and comprised between the fold-lines (21) turning said hollow columns into solid columns, their cross-section also being that of an isosceles trapezoid, and in that the top end of said recesses (29) is affected by double chamfers (30) determining a "sharp" top end of each column, fostering even further their coupling into the respective notching (14) on the bottom of the tray lying right above, upon the trays being stacked.

Inventors: MARCH VILA FATIMA, MARCH VILA, FATIMA
Applicants: VIDECART SA, VIDECART, S.A.
Application year: 1993
Main classification: B65D5
IPC codes: B65D5