FR2747995A1 - Vacuum packaging of dry loose product - Google Patents

Abstract

The method uses a supple and impermeable package (18) which is placed inside an open cavity (12) of predetermined shape, before filling with the product (58), e.g. a dry bulk material with sharp edges or points. Before the product is poured into the package the inner walls and base of the latter are lined with semi-rigid panels (26-29,57), and a further panel (59) is placed on top of the product before the package is evacuated and sealed. The semi-rigid panels have rounded corners and are made from a material selected from a group comprising polypropylene, PVC and high-density polyethylene 250-350 mu thick. The package itself is made from polyethylene or polyethylene-polyamide-polyester material of thickness 100-140 mu , sealed with an internal pressure of 100-150 mb. The cavity (12) can be provided by a cardboard box (1).

Description

 The present invention relates to a process for packaging a product, under vacuum, in a flexible, airtight envelope, in particular a product in bulk and / or having aggressive edges or points for the envelope, in particular in dry form, consisting in placing the 'envelope opened in an open cavity, of determined shape, by pressing it against the internal faces of this cavity, to fill the envelope of the product, to evacuate the envelope and to close it tightly.

 Such a process is currently known, and widely used, in an implementation mode according to which the product is placed directly in contact with the waterproof envelope which comes to marry it closely during the vacuum drawing by applying a compression which freezes it. the assembly formed by the product and its envelope in the determined form which has been communicated to it by the cavity.

 In this currently known mode of implementation, the vacuum packaging process gives all satisfaction when it comes to packaging powdery or granular products in v rac, or even soft or flexible textured, with or without liquid, in volumes. which can range from a few hundred cubic centimeters to a cubic meter as soon as the thickness of the material constituting the envelope is appropriately chosen, depending on the nature of this material.

However, as soon as the product to be packaged has aggressive edges or points for the envelope, for example if it is a question of packaging in bulk a product at least partially produced by stamping sheet steel, or else of packaging individually or in arranged groups of products also having aggressive edges or points for the envelope, such as metal boxes or chain sprockets, the currently known mode of implementation of the aforementioned packaging process is no longer satisfactory to the extent where, if one wishes to avoid tearing of the envelope, it is necessary to considerably increase the thickness of the material constituting it, which affects its flexibility, that is to say the possibility of store and transport it in a reduced volume in an empty state, making it less easy to control the maintenance of the vacuum inside after filling since its relative rigidity té allows only a few changes in its appearance depending on whether it is placed internally under vacuum or at ambient pressure, and considerably increases the cost price.

 The object of the present invention is to remedy these drawbacks and, to this end, a method of packaging a product under vacuum, of the type indicated in the preamble, is proposed, characterized in that the envelope is internally semi-rigid walls respectively skirting said internal faces of the cavity before or, at the latest, during its filling with product and in that it is also covered with a semi-rigid wall before evacuating and seal the envelope.

 The semi-rigid walls thus inserted between the packaged product and the envelope make it possible to distribute thereon the stresses resulting from its application to the packaged product due to the evacuation, that is to say to avoid its damage by aggressive edges or points that this product may present.

 It thus becomes possible to package a product in bulk and / or having aggressive edges or points in an envelope made of a material which, if it came directly into contact with aggressive edges or points, would not resist them. One can even also condition such a product in dry form, that is to say in the absence of any liquid capable of playing a damping or lubricating role vis-à-vis the envelope and thus protect it. this to some extent.

 Thus, for the packaging of small mechanical parts produced by stamping steel sheet in the form of a rectangular parallelepiped of 400 mm by 400 mm by 246 mm, good results have been obtained by using an envelope made of a material chosen from a group comprising monolayer materials such as polyethylene or multilayer materials such as a polyethylene-lene-polamide-polyester complex, in a range of thicknesses between 100 sm and 140 zm, it being understood that this choice of materials could give satisfaction for other packaging dimensions and for other types of packaged products, and in any case constitutes only a non-limiting example which may be departed from while remaining within the scope of the invention.

 Preferably, in order to avoid damage to the envelope by the semi-rigid walls, these have rounded corners.

 Provision may be made for the semi-rigid walls to be joined to the envelope by various means, and for example by point bonding or point welding, but it is preferable to use for this purpose the mutual support of the packaged product and of the envelope, due to the weight of the product and its tendency to spread out if it is a loose product, during filling, then the effect of the vacuum notably after closing of the envelope. Thus, according to a preferred embodiment, the envelope is lined internally by placing the semi-rigid walls in abutment against it without using mutual securing means.

 The support of the semi-rigid walls against the envelope, in a precise relative arrangement facilitating the filling and avoiding in particular any risk that the product, if it is a bulk product, will creep between the walls semi-rigid and the envelope at the risk of subsequently damaging it during vacuuming can be favored if, according to a preferred embodiment of the present invention, at least some of the semi-rigid walls are produced by folding a semi-rigid band so that they are linked together; preferably, it is also provided for this purpose that the walls have free edges that are placed in mutual overlap by lining the envelope internally.

 Despite its advantages, the method according to the invention remains economical insofar as the semi-rigid walls can be made of a material chosen from a group comprising polypropylene, PVC, high density polyethylene, in a range of thickness between 250 mm and 350 mm, these choices having given all satisfaction for the previously indicated packaging dimensions but constituting, in the same way as these dimensions, only a non-limiting example which may be departed from without departing from the part of the present invention.

 Depending on the case, the cavity of determined shape can be formed, in which the envelope is placed to fill it, by a cardboard or the like in which the envelope is left after having closed it in a sealed manner. cardboard or the like "a box or case made of rigid or semi-rigid material, such as cardboard or wood, which can then be transported and stored, generally after having closed it after the envelope has been sealed, for protect the latter and the product it contains under vacuum. It is however also possible to constitute the cavity by a provisional support matrix, from which the envelope is extracted after having closed it in a sealed manner; after having extracted from the provisional support matrix the assembly formed by the envelope and the product that it contains under vacuum, as well as by the semi-rigid walls interposed between them, one can then either store and transport as is this assembly , or engage it in a box or the like, as defined above; in this case, the carton or the like can internally define said determined shape, communicated to the assembly formed by the envelope and the product that it contains under vacuum, in which case only one assembly is packaged per carton or the like, but it is possible to also plan to package several of these assemblies, preferably in a mutually juxtaposed state in a determined relative arrangement, inside a carton or the like of larger dimensions. The cardboard or the like, generally closed, can thus be used for transporting and storing one or more assemblies.

 It will be observed that the packaging according to the invention does not require the establishment of a high vacuum in the envelope, taking into account the materials compatible with the implementation of this process and more particularly the flexibility of these materials thus, obtained good test results by establishing a vacuum in the envelope, of the order of 100 to 150 millibars, it being understood that this value is only given by way of nonlimiting example.

 In particular, this v value is sufficient to detect a possible loss of vacuum, that is to say a possible contamination, when the packaged product must be kept in a sterile environment, in which case the assembly formed by the product, the semi-rigid walls and the envelope after having closed the latter in a sealed manner, without being obliged to have recourse to packaging in a tunnel or sterile chamber.

 Naturally, the method according to the invention applies more particularly to the packaging of a product having aggressive edges or points for the envelope, in particular of a bulk product and / or having aggressive edges or points for the envelope but it could also be used to vacuum package any product when it is not desired, for any reason, that the envelope be placed directly in contact with this product.

 Taking into account the originality that constitutes, for the assembly obtained by implementing the method according to the invention, the presence of semi-rigid walls between the conditioned product and the flexible, waterproof envelope, subjected to an internal depression, the present invention extends to such an assembly.

 Other characteristics and advantages of the method according to the invention and of the assembly obtained will emerge from the description, below, of a nonlimiting, but currently preferred example, of implementation of the method, as well as the attached drawings. which form an integral part of this description.

 Figure 1 illustrates, in a perspective view, different stages of this example of implementation of the method according to the invention, as well as the various components used for this purpose, namely a cardboard box an envelope, semi-walls rigid and a bulk product, presenting aggressive edges or points for the envelope.

 Figures 2 and 3 illustrate two embodiments of the envelope, in a perspective view similar to that of Figure 1 with section through a first vertical median plane identified in ll-ll in Figure 1, the envelope being assumed occupy an orientation in which it is open upwards, as is the case during the installation of the semi-rigid walls and of the product.

 FIG. 4 shows a plan view of a semi-rigid wall used in two copies in the case of this example of implementation, one of the copies being placed under the product and the other above.

 Figure 5 shows the development, flat, of a strip grouping several semi-rigid walls hinged together by bridges of material and intended to laterally wrap the packaged product.

 FIG. 6 shows a detail of this strip, identified in VI in FIG. 5.

 FIG. 7 shows a view of the assembly formed by the carton, the flexible envelope, the semi-rigid walls and the product packaged after the envelope is sealed but before the carton is closed, in section through a second median vertical plane referenced in VII-VII in Figure 1.

 FIG. 8 shows this same assembly, in a final phase preceding the closing of the carton, in section through the plane marked in II-II in FIG. 1.

 Figure 9 shows, in a perspective view, an alternative embodiment of the semi-rigid walls intended to laterally wrap the product.

 A standard cardboard box is designated by 1, in the shape of a rectangular parallelepiped, comprising a flat, rectangular wall, with a bottom 2, arranged horizontally and facing downwards for carrying out the process, and four flat side walls. , rectangular 3, 4, 5, 6 contiguous two by two and contiguous with the bottom 2, these side walls 3 to 6 then being oriented vertically and erect upwards from the bottom wall 2, and having, at the same level relative to it, a respective rectilinear upper edge, then horizontal, not referenced. The box 1 also comprises four flaps 7, 8, 9, 10 flat, rectangular, each of which is articulated on an upper edge of a respective side wall 3 to 6 so as to be able to occupy an open position of the box 1, wherein the flaps release a rectangular upper opening 11 thereof as illustrated in Figures 1, 7, 8, or a closed position of the opening 11, with mutual superposition of these flaps 7 to 10, which then form a flat, rectangular wall with a cover 112 as illustrated in phantom in Figure 8; the bottom wall 2 can itself thus be made up of four mutually superimposed flaps, in a manner not illustrated but well known to a person skilled in the art.

 The walls 2 to 6 of the carton 1 define an internal cavity 12 thereof, by a respective internal face 13, 14, 15, 16, 17, rectangular and planar. This cavity 12 is open upwards, through the opening 11, when the flaps 7 to 10 occupy their open position.

 To implement the present invention, there is placed inside the cavity 12 a flexible, waterproof envelope 18 having a shape and dimensions such that it best applies, flat, on the internal faces 13 to 17 from the cavity 12 and protrudes out of the latter, through the opening 11, through an upper zone 19 in which the casing 18 initially defines a rectangular opening 20 facing upwards and taking up the thickness of the material constituting the envelope 18 close, the shape of the upper opening 1 1 of the carton 1.

 More precisely, as it appears when it is engaged in the cavity 12 under conditions suitable for allowing the implementation of the present invention, the casing 18 has a substantially flat, rectangular bottom wall 21, taking up approximately the shape and dimensions of the internal face 13 defined by the bottom wall 2 of the carton 1, against which this wall 21 is applied substantially flat, and four side walls 22 to 25 also substantially flat and rectangular, applying substantially flat against the faces 14 to 17, respectively, and having dimensions which correspond to those of the latter in the horizontal direction; on the other hand, in the height direction, these side walls 22 to 25 have the same dimension greater than the vertical dimension of the faces 14 to 17, of a value greater than half the horizontal dimension of the faces 14 and 16 to allow the subsequent closing of the envelope 18.

 The walls 21 to 25 are sealed and connected to each other in a sealed manner, but can be produced in different ways.

 In an example illustrated in Figures 2, 7, 8, the side walls 22 to 25 are made in one piece, and defined by a flexible tubular sheath, obtained directly by extrusion, and the bottom wall 21 is attached to them by welding ; in another example illustrated in FIG. 3, the bottom 21 and side walls 22 to 25 are made in one piece, from a strip of which two edges are welded to form a tubular sheath similar to that which forms the walls side 22 to 25 in the example illustrated in Figure 2, so as to also define these side walls 22 to 25, before welding the sheath thus formed at one of its ends and folding it back on itself to form the bottom wall 21, according to a technique which is known in itself and will not be described further.

 To this end, as well as to allow subsequent sealing, with internal depression, the envelope 18 is made of a weldable material, in particular heat-weldable, as is the case with the aforementioned materials, namely the polyethylene or a pol ~ tethclene-polqamide-pol? ester complex, these examples being in no way limiting.

 After having thus lining the cavity 12 internally by means of the envelope 18, leaving the latter open upwards, through the opening 20 of its upper zone 19 projecting from the cavity 12, above the carton 1, its lateral walls 22 to 25 are lined internally with substantially flat, vertical lateral walls, respectively 26, 27, 28, 29, of respective rectangular general shape and which can be mutually independent or, preferably and as illustrated, formed by folding a strip 130 of a semi-rigid material, the development of which is flat is illustrated in FIG. 5 and a detail in FIG. 6.

 The strip 130, also of generally rectangular shape, defined by two comparatively long edges 445, essentially rectilinear and mutually parallel, and two comparatively short edges 54, 55, also rectilinear essentially and mutually parallel, if the we consider its development flat, has a rectangular central panel defining the wall 26, two intermediate panels, also rectangular, defining the walls 27 and 29, respectively disposed on either side of the panel defining the wall 26 and connecting to it. pan along a respective line of mutual articulation 30, 31, and two end panels 32, 33 each of which is articulated on one, respectively, of intermediate panels 27 and 29 along a respective line of articulation 34, 35.

The articulation lines 30, 31, 34, 35 are mutually parallel and parallel to the edges 54 and 55 of the strip 130. The articulation lines 30 and 31 are mutually spaced apart by a distance 1, defining the horizontal dimension of the wall 26, a few millimeters lower than the corresponding dimension of the face 14, and more precisely, of an unreferenced face, of the wall 22 facing the inside of the envelope 18 the articulation lines 30 and 3A, on the one hand, 31 and 35, on the other hand, are mutually spaced by a respective distance L, defining the horizontal dimension of the wall 27 or 29, respectively, a few millimeters less than the corresponding dimension of the face 15 or 17, respectively, and more precisely of a face, not referenced, of the wall 23 or 25, respectively, facing the inside of the envelope 18; on the other hand, each of the end panels 32, 33 has, perpendicular to the respective articulation line 34, 35, between this respective articulation line and a corresponding edge 54, 55, rectilinear and parallel thereto, of the strip 130, a dimension k less than that I which the pan defining the side wall 26 presents perpendicularly to the lines 30 and 3 1 but greater than half of this dimension I of the pan defining the wall 26.

 Thus, by folding the different panels at right angles along the lines 30, 31, 34, 35, the side walls 26, 27, 29 are directly formed, by a respective panel, and the panels 32 and 32 are formed by partial mutual superposition. 33 the side wall 28, as shown in FIG. 1. The fold lines 30, 31, 34, 35 then define rectilinear, vertical edges, identified by the same numerical references in FIG. 1, and the edges 44 and 45 of the strip 130 form free edges, respectively lower and upper, of the walls 26 to 29.

 The panels 32 and 33 can be simply superimposed, without mutual joining.

Not illustrated but easily understood by a
A person skilled in the art, it is however also possible to secure the panels 32 and 33 mutually, for example by gluing, welding, or mutual stapling. Such mutual stapling can, for example, implement the engagement of at least one tab of one of these panels 32 and 33 in a corresponding slot on the other of these panels, in a manner which may be easily deduced from the description below of an alternative embodiment of the walls 26 to 29 illustrated in FIG. 9.

 In the case of this variant, we find the embodiment of the side wall 28 in the form of two partially superimposed panels 32, 33, each of which is connected, by a respective line 34, 35 of folding at right angles, to another side wall respectively 27, 29; on the other hand, instead of being produced in one piece, the side wall 26 is also produced in the form of two partially superimposed panels 62, 63, which are in all points similar to panels 32 and 33 and are each connected by a respective line 30, 31 of folding at right angles, to one, respectively, of the side walls 27 and 29. Thus, the wall 27 is produced in a single piece with the sides 32 and 62, by folding a strip 6A, approximately rectangular, of semi-rigid material, and the wall 29 is made in one piece with the sides 33 and 63, by folding another strip 65, approximately rectangular, of semi-rigid material. It is then preferably ensured by mutual securing of the panels 32 and 33 and panels 132 and 133, respectively, the shape stability of the walls 26 and 28 which they constitute, and in particular a relative immobilization of the panels 32 and 33 partially superimposed and of the sides G2 and 63 partially superimposed, respectively, against a relative translation in the direction of mutual separation of the walls 27 and 29 and against a relative rotation. This mutual joining can be achieved by any of the aforementioned means with regard to a possible mutual joining of the sides 32 and 33 of the embodiment of the side walls 26 to 29 illustrated in Figures 1 and 5, in particular; ; there is illustrated in FIG. 9 a preferred mode of mutual securing, according to which the pan 32 carries integrally, in a single piece with it, two tongues 66, only one of which is visible in FIG. 9 and which protrude, in positions mutually offset in the direction of the height, on its edge 54 constituting an edge of the strip 64; each of these tongues 66 is engaged in a respective slot 67 which the pan 33 has parallel to its edge 55, constituting an edge of the strip 65, and which retains it due to the semi-rigidity of the material constituting the strip 65 and a conformation of the tongue 66 in arrowhead; likewise, the pan 63 has two tongues 68, at all points similar to the tongues 66, projecting from a straight edge 69 parallel to the edge 31 and forming an edge of the strip 65, and these two tongues 68 penetrate into a slot respective 70 that the pan 62 has parallel to a straight edge 71 parallel to the edge 30 and constituting an edge of the strip 64.

 The materials previously indicated as capable of constituting the semi-rigid walls, in particular 26 to 29, lend themselves particularly well to an embodiment of the fold lines 30 to 35 in the form of rectilinear non-perforating notches, arranged in line on one face of the strip 130 intended to be turned inward during folding, these notches alternating with non-notched areas according to a technique known to a person skilled in the art.

 It will be observed that this embodiment of the side walls 26 to 29 by folding a single strip 130 makes it possible to ensure continuity between them preventing any leakage of the product to be packaged 58, even if it is a product in bulk of small particle size, between the side walls 26 and 29 and the casing 18.

 To this effect also contribute the fact that the horizontal dimensions of the walls 26 to 28 are approximately identical to the horizontal dimensions of the respectively corresponding walls 22 to 25 of the envelope 18, at least if we refer to the face of these turned walls towards the inside of the envelope 18, and the fact that the material constituting the strip 130 has a certain elasticity, which tends to bring the sections defining the walls 26 to 29 in a coplanar relationship, so that the walls 26 to 29 are pressed against the walls 22 to 25 of the envelope 18 respectively, by pressing the latter against the walls 3 to 6 of the carton 1, respectively, that the walls 26 to 29 run as narrowly as possible, to the thickness of the 'envelope 18 close.

 It also follows from these two facts that the envelope 18 is maintained in a stable conformation, complementary to the shape of the cavity 12, before filling with product to be conditioned 58, without it being necessary to provide specific means for this effect, such as gluing or welding the semi-rigid walls 26 to 29 to the walls 22 to 25 of the envelope 18 respectively.

 In a different embodiment, according to which the walls 26 to 29 would not be produced by folding a single strip 130 but would be physically distinct, this complementarity of the shape of the envelope 18 and that of the cavity 12 could be ensured. by mutual joining, for example by spot bonding or spot welding, of the semi-rigid walls 20 to 29 and of the walls 22 to 25 of the envelope 18, respectively, or by using means of temporary retention of the semi-rigid walls 26 to 29, introduced through the opening 20 and removed after at least partial filling of the envelope 18 with product to be conditioned 58 and before tight closure of the envelope 18, or again by using the product to be conditioned 58 itself, of which would place a certain amount in the envelope 18 before putting in place the semi-rigid walls 26 to 29 by sliding them between them; in the latter case, a semi-rigid bottom wall 57, which will be described later, would be placed on the bottom wall 21 of the casing 18 prior to the introduction of the product to be packaged 8. Preferably, in this mode of embodiment according to which the walls 26 to 29 are physically distinct, that is to say are adjacent to each other by free edges, provision would also be made for mutual overlapping of the walls 26 to 29 at any junction between these free edges, d 'a way which will now be described with regard to the connection of these side walls 26 to 29 with bottom walls 57 and cover 59, in order to avoid leakage of the product packaged between the semi-rigid walls and l '' envelope 18.

 In the height direction, in order to ensure such overlap, the walls 26 to 29, that is to say the respective corresponding sides of the strip 130, measured between the edges 44 and AD, if one refers to the preferred embodiment which has been illustrated, have a dimension h slightly greater than the dimension that have vertically, internally, the respective zones of the side walls 22 to 25 of the envelope 18 which are attached to the walls 3 to 5, respectively, of the cardboard 1, that is to say in practice greater than the internal vertical dimensions of the cavity 12 to the thickness, comparatively negligible, near the envelope 18. This additional height may for example be on the order of 10 to 40 mm, it being understood that a different figure could be chosen without departing from the scope of the present invention, and in particular a higher figure.

Thus, as shown in FIGS. 7 and 8 and in accordance with the present invention, the side walls 26 to 29 are arranged inside the envelope 18, forming on each of them a respective lower rim 36 to 39, curved inwards on the bottom wall 21 of the casing 18 and pressing down on the face 13 of the bottom wall 2 of the carton 1 by means of this bottom wall 21, and, subsequently, forms on each of these side walls 26 to 29 a respective upper edge 40, 41, 42, 43 also turned towards example of the order of 25 mm, so as to be connected tangentially on the one hand to the corresponding edge 45 and elsewhere on the edges of the area in
V close to the tip 56. Thus, both the damage to the envelope 18 is avoided by the corners of the side walls 26 and 29 and the formation of the edges 36 to 43 is facilitated.

 Naturally, similar arrangements are found when, as illustrated in FIG. 9, the side walls 26 to 29 are produced by folding and, preferably, assembling two strips 64 and 65 of semi-rigid material.

 Also, in order to avoid damaging the envelope 18, the four corners of the strip 130, defined by connection of its edges 44 and 45 with its two other edges 5A, 55 are also rounded, convex, with a radius r1 which is for example of the order of 15 mm, it being understood that this figure is given by way of nonlimiting example.

 To implement the method according to the invention, after having placed the envelope 18 in the cavity 12 of the open cardboard 1, as indicated previously, and introducing the side walls 26 to 29 into the open envelope 18, under conditions such that the lower edges 36 to 39 are formed but without folding the upper edges 40 to 43, a bottom wall 57 is engaged by the open upper end 20 of ltenxeloppe 18, between the side walls 26 to 29 Figure 4 shows in plan.

 This bottom wall 57, semi-rigid like the walls 26 to 29 but produced independently of these, is substantially flat, of generally rectangular shape, and has dimensions in plane I and L approximately identical to the dimensions that present, at l inside the envelope 18, the bottom wall 21 thereof, and more precisely substantially equal, respectively, to the dimension separating the fold lines 30 and 31 and to the dimension separating the fold lines 30 and 34 or 31 and 35. Like the side walls 26 to 79, the bottom wall 57 has four rounded corners, convex and for example in a quarter circle with radius r2.

 Thus, the bottom wall 57 can be pushed from top to bottom, between the side walls 26 to 29, until it is placed substantially in flat contact with the bottom wall 21 of the casing 18, itself substantially in flat contact with the bottom wall 2 of the casing 1, except that the respective flanges 36 to 39 of the side walls 26 to 29 are inserted between the bottom wall 57 and the bottom wall 21 of the casing 18 at the periphery of the bottom wall 57, all around the latter, this mutual covering preventing leakage of product to be conditioned 58 between the bottom walls 57 and 21.

 In a variant not shown, the bottom face 57 could be made in one piece with one of the side walls 26 to 29, for example made of strip 130, or even form a continuous strip with two of them, of easily understood by a person skilled in the art who, then, would preferably provide such mutual recoveries in any zone in which two walls would be connected without being directly linked to one another.

 Next, the envelope 18, or more precisely the space delimited inside it by the side walls 26 to 29 and the bottom wall 57, is filled with the product to be packaged, for example in bulk, 58 by conventional methods, so that this product 58 is flush with the opening 11 of the carton 1.

 Then, in accordance with the present invention, there is on the product 58 a cover wall 59 at all points identical to the bottom wall 57 and that there is between the side walls 26 to 29 before folding the upper edge thereon. respectively 40 to 43 of these.

 Then, vacuum is drawn inside the envelope 18 and the product 58, by also conventional means, and the upper zone 19 of the envelope 18 is closed in a sealed manner, for example by welding, also in a conventional manner in order to obtain the assembly illustrated in FIG. 7 where it can be seen that the side walls 22 to 25 of the envelope 18 still have an upper zone projecting from the cavity 12, above the carton 1, but are welded to each other with folding of the projecting zones of the side walls 20 and 22 to form a beak so that half of each of them applies to the other half, and flat application of the side walls 23 and 25 one on top of the other, in both cases in the upper zone 19 of the envelope 18; 60 was designated as sealed mutual welding.

 Then, as shown in FIG. 8, the upper zone 19 of the envelope 18 is folded flat on the cover wall 59, in the form of a flat upper wall 61 of the envelope 18, then the carton 1 is closed. by folding down the flaps 7 to 10 on this upper wall 61 which is itself superimposed on the cover wall 59, with mutual overlap of the flaps 7 to 10 and mutual joining together to form the upper wall 112 of the carton 1.

 This can then be stored and transported without risk of damage to the envelope 18 by the bulk product 58.

 In a variant not illustrated but easily understood by a person skilled in the art, the various operations which have just been described begin not with the positioning of the envelope 18 inside a cavity 12 formed by a carton 1, but by positioning, under completely similar conditions, this envelope 18 in a cavity of shape and dimensions identical to those of the cavity 12 but defined by a provisional support matrix.

We find in this case all the steps of the process described above except that after having closed the upper zone 19 of the envelope 18 in a sealed manner and, optionally, formed the flat upper wall 61 thereof. on the cover wall 59, the assembly formed by the envelope 18, the product 58 which it contains and the semi-rigid walls 26 to 29, 57 to 59 are inserted from this matrix, inserted between this product 58 and the envelope 18 for, then, either store and transport this assembly as it is, or place it in a carton at the rate of one assembly per carton sized like carton 1, or of several assemblies per carton then dimensioned accordingly.

 In general, the invention is susceptible of numerous variants and these variants do not depart from its scope.

 These variants may relate in particular to the choice of materials constituting the carton 1 or the like, of the envelope 18, of the semi-rigid walls with which they are lined internally and of the packaged product, both in terms of the nature and thickness of the walls as regards cardboard or the like 1, the envelope 18 and the semi-rigid walls 26 to 29, 57, 59. These variants can also relate to the shape that is given to the envelope 18 by temporary or permanent positioning inside a cavity 12 prior to the installation of the semi-rigid walls 26 to 29, 57, 59 and to the filling with product to be conditioned 58, this shape being able not only to be parallelepipedal as has been described but also cylindrical with a polygonal or circular base, or even other, the number and the shape of the semi-rigid walls 26 to 29, 57, 59, folded and possibly assembled strips 130, 64, 65 which preferably constitute at least some of them as well as, where appropriate, of the walls 21 to 25 of the envelope 18 being if necessary adapted accordingly.

Claims (14)

1. Method for packaging a product (58), under vacuum, in a flexible, waterproof envelope (18), in particular a product (58) in bulk and / or having aggressive edges or points for the envelope (18), in particular in dry form, consisting in placing the open envelope (18) in an open cavity (12), of determined shape, by pressing it against internal faces (13 to 17) of this cavity (12), to fill the 'envelope (18) of the product (58), to evacuate the envelope (18) and to close the latter tightly,  characterized in that the casing (18) is lined internally with semi-rigid walls (26 to 29, 57) along respectively said internal faces (13 to 17) of the cavity (12) before or, at the latest, during its filling with product (58) and in that it is also covered with a semi-rigid wall (59) before evacuating and closing the envelope (18) tightly. 2. Method according to claim 1, characterized in that the semi-rigid walls (26 to 29, 57, 59) have rounded corners. 3. Method according to any one of claims 1 and 2, characterized in that the semi-rigid walls (26 to 29, 57, 59) are made of a material chosen from a group comprising polxpropxlene, PVC, polyethylene high density, in a thickness range between 250 Fm and 350 clam.  4. Method according to any one of claims 1 to 3, characterized in that the envelope (18) is lined internally by placing the semi-rigid walls (26 to 29, 57, 59) bearing against them, without using mutual solidarity means.  5. Method according to any one of claims 1 to 4, characterized in that at least some (26 to 29) of the semi-rigid walls (26 to 29, 57, 59) are produced by folding a strip semi-rigid (130) so that they are linked together.  6. Method according to any one of claims 1 to 5, characterized in that the walls (26 to 29, 57, 59) have free edges which are placed in mutual overlap by lining the envelope internally (18) . 7. Method according to any one of claims 1 to 6, characterized in that the envelope (18) is made of a material chosen from a group comprising polyethylene, polyethylene-polyamide-polyester complex, in a thickness range between 100 pm and 140 zm. 8. Method according to any one of claims 1 to 7, characterized in that one constitutes the cavity (12) by a cardboard (1) or the like, in which the envelope is left (18) after having tightly closed. 9. Method according to any one of claims 1 to 7, characterized in that the cavity (12) is constituted by a temporary support matrix, from which the envelope (18) is extracted after having closed it so waterproof. 10. Method according to claim 9, characterized in that one engages the envelope (18) in a carton or the like, after having extracted it from the provisional support matrix. 11. Method according to any one of claims 8 and 10, characterized in that said carton (1) or the like is closed after closing the envelope (18) in a leaktight manner. 12. Method according to any one of claims 1 to 11, characterized in that, by vacuum sorting, there is established in the envelope (18) a depression of the order of 100 to 150 millibars. 13. Method according to any one of claims 1 to 12, characterized in that one sterilizes the assembly formed by the product (58), the semi-rigid walls (26 to 29, 57, 59) and the envelope (12) after having closed the latter in a sealed manner. 14. An assembly obtained by implementing the method according to any one of claims 1 to 13.