Title:
Modular Container for Holding Ventilation-Sensitive Commodities
Kind Code:
A1


Abstract:
The invention relates to a modular container consisting of a plurality of elementary containers (1) stacked sequentially into one another. The elementary containers (1) comprise a recessed (5) [sic] base (4) for receiving a neck (2). Nesting elements (6, 7) assemble peripheral ramps (8, 9) in nested cooperation capable of assembling together the elementary containers (1) by rotating their axial junction, and end-of-travel stops (10, 11, 14, 15) of said rotation in snap-on cooperation which constitute means of locking the assembly of the elementary containers (1) from rotation, and which are capable of preventing spontaneous reverse rotation.



Inventors:
Bou-mezrag, Mohammed (Villeneuve la Garenne, FR)
Application Number:
12/227684
Publication Date:
05/21/2009
Filing Date:
05/23/2007
Primary Class:
Other Classes:
206/1.5, 206/509
International Classes:
B65D21/02
View Patent Images:
Related US Applications:



Primary Examiner:
COLLADO, CYNTHIA FRANCISCA
Attorney, Agent or Firm:
Charles Muserlain (Valley Cottage, NY, US)
Claims:
1. A modular container comprised of a plurality of elementary containers stacked sequentially into one another, the elementary containers comprising a recessed base of a revolution conformation to receive a neck of a similar structure, cooperating nesting elements being made respectively on the base and on the neck of the elementary containers (1) in order to constitute means of assembling the elementary containers with each other, wherein the nesting elements associate peripheral ramps in nested cooperation, which are able to assemble the elementary containers (1) with each other by rotation of their axial junction, and end-of-travel stops of said rotation in snap-on cooperation, which constitute locking means of the assembly in rotation of elementary containers with each other and which can prevent a spontaneous reverse rotation.

2. The modular container of claim 1, wherein the stops are integrated into the ramps and are in snap-on cooperation with them by snap-on in reaction to an elastic deformation of the nesting elements.

3. The modular container of claim 2, wherein the nesting elements are elastically deformable indifferently by means of the ramp and/or the stop of which they are a part, respectively.

4. The modular container of claim 1, wherein the ramps are made respectively recessed and/or projecting indifferently on one and/or the other of the base and/or the neck of the elementary containers.

5. The modular container of claim 1, wherein the stops are made respectively recessed and/or projecting indifferently on one and/or the other of the ramps respectively assigned to the base and/or to the neck of the elementary containers.

6. The modular container of claim 1, wherein the cooperation surface between the stops is spherical.

7. The modular container of claim 1, wherein the cooperation stops are formed by complementary snap-on reliefs that are made indifferently made at the end of the ramps for a tangential connection of the elementary containers between each other with respect to their revolution conformation, and/or by snap-on reliefs made indifferently on the axial and/or peripheral faces of the nesting elements, for a radial connection of the elementary containers to each other.

8. The modular container of claim 1, wherein a male nesting element is formed from a plate integrated by molding into the neck, said plate comprising a plurality of ramps radially distributed equally, at least one of which forms at least one stop, while a female nesting element is formed from recess of complementary shape integrated into the molding of the base.

9. The modular container of claim 8, wherein the ramps are arranged as grooves made in the section of the plate (12).

10. The modular container of claim 8 wherein the cooperating stops are respectively arranged as dome and cup and are indifferently of axial extension and/or of radial extension.

11. The modular container of claim 8 wherein the ramps are indifferently of circular or helicoidal extension.

12. The modular container of claim 8 wherein the ramps are helix shaped and constitute elements of axial thrust against the stops.

13. The modular container of claim 1 wherein the ramps are in plurality and are radially equally distributed and oriented along a generatrix of said conformation of revolution of the recess of the base and of the neck.

14. The modular container of claim 12, wherein the stops are formed by at least a bead and a groove that are made respectively at the end of one and/or the other of the ramps respectively made in the base and neck.

Description:

TECHNICAL FIELD OF THE INVENTION

The present invention is in the field of containers for holding ventilation-sensitive commodities, and more particularly containers that can be nested by stacking. An object of the invention is a modular container composed of a plurality of modules sequentially stacked and assembled successively into each other.

PRIOR ART

The packaging of ventilation-sensitive commodities is made somewhat problematic because of this sensitivity. Such commodities can be foodstuffs such as gassy liquid, or cosmetics and/or therapeutic products for example. These commodities are often held inside a hermetically closed container which allows them to be stored until they are consumed. Such containers in particular are formed by molding plastic material, such as blow molding or a similar molding technique. However, the consumption of the commodities after the container is opened may be extended over time, resulting in the risk of alteration of the commodity held in the container until it is emptied.

For this reason modular containers have been proposed that are comprised of a plurality of similar elementary containers assembled by sequentially stacking them into each other. Such a modular container is generally of an overall cylindrical conformation; the elementary containers that comprise it have a recessed base, in particular conical in shape, in order to receive by nesting a neck of complementary shape of an adjacent container. The assembly of the elementary containers two by two is accomplished, for example, by a flange, by a screwing means fitted at the end of their neck, or by nesting units cooperating respectively at the base and at the neck of the elementary containers. Reference can also be made to the documents EP1321370 (PICI, A), WO02/12077 (RAMJAN, RAMAN), DE 10232578 (CANAK M.), WO0236444 (NICHE EDGE Ltd), GB2303114 (JONATHAN DEREK & ROBINSON), FR818908 (VEREINIGTE LAUSITZER GLASWERKE AKTIENGESELLSCHAFT), which describe such modular containers.

One difficulty to be overcome is in the quick and reliable assembly of the elementary containers to each other. Indeed, the assembly methods must be easy to implement so that it does not constitute a totally unacceptable constraint for the consumer, while still being strong enough to make this assembly reliable. Moreover, these methods of assembly must be performed while taking into account the manufacturing constraints in molding elementary containers, while avoiding their resulting bulkiness that could interfere with the desired contact of the wall of the necks against the wall of the bases. Finally, this assembly must ensure the centering and successive strictly aligned extension of the elementary containers, without the risk of offsetting one elementary container from another that could result from the effect of the efforts made by the consumer to accomplish this assembly, in order to preserve an aesthetic, continuous line for the modular container.

More particularly, it was proposed in EP1321370 to provide the elementary containers with complementary stacking ribs in relief that extend peripherally respectively from their neck and their base. The stacking ribs in relief are ring shaped and are made to cooperate by axial thrust exerted by the user. Such axial thrust causes a radial deformation of the peripheral wall of the containers in order to permit the axial passage of one of the ribs inside the other rib. According to one variant, the stacking ribs are arc-shaped while being constructed as a bayonet type connection device.

Such arrangements do not achieve satisfactory ergonomics because of the efforts the user must make to assemble the elementary containers to each other, and/or movements the user must make to assemble and separate the elementary containers. Moreover, the methods used to assemble the elementary containers do not achieve a firmness that can provide a satisfactory overall sturdiness to the container, particularly when a bayonet type connection device is used. Furthermore, the assembly methods used result in significant stresses on the walls of the elementary containers, which are detrimental to the durability of the container and more particularly to the durability of the elementary containers that comprise it. These stresses make it impossible to ensure a strict centering of the elementary containers in each other, and as a result alter the aesthetic line of the container. These stresses also work against an ease of manipulation of the elementary containers in assembling them together. Finally, the ergonomics of the container is a deterrent for the user either because of the sense of fragility of the container, the walls of the elementary containers having to be malleable enough to enable their deformation, or because of the axial effort that the user must exert to counter the deformation of the revolution wall of the elementary containers, which is strong in this case. Although the variant consisting of using a bayonet type device can make the assembly of the elementary containers easier, it requires clearance in order to limit the stresses related to their assembly, which is not satisfactory because of the resulting slack between the elementary containers thus assembled.

OBJECT OF THE INVENTION

The purpose of the present invention is to propose a modular container comprised of a plurality of elementary containers stacked sequentially into one another, which offers a satisfactory solution to the difficulties described above. More particularly, the present invention seeks to allow an assembly and separation of the elementary containers with each other that is ergonomic and limits the stresses exerted on the revolution wall of the elementary containers, while still ensuring the reliability of the assembly thus obtained, the durability of the container both structurally as well as with respect to preserving its overall aesthetic line, irrespective of potentially very numerous repeated operations of assembly and separation of the elementary containers. The present invention also seeks to propose such a container whose offered advantages do not detract from its competitiveness, particularly by making it possible to achieve it at lower cost.

The modular container of the present invention is comprised of a plurality of elementary containers stacked sequentially into one another. The elementary containers comprise a recessed base of a revolution conformation to receive a neck of a similar structure. Cooperating nesting elements are made respectively on the base and on the neck of the elementary containers, in order to constitute means of assembling the elementary containers with each other.

According to the present invention, such a modular container is primarily recognizable in that the nesting elements associate peripheral ramps in nested cooperation, which are able to assemble the elementary containers with each other by rotation of their axial junction, and end-of-travel stops of said rotation in snap-on cooperation, which constitute locking means of the assembly in rotation of elementary containers with each other and which can prevent a spontaneous reverse rotation.

The assembly means associate axial nesting elements of the elementary containers, which are formed by the ramps, and radial nesting means of the elementary containers by elastic deformation, which are formed by the stops. These stops are in snap-on cooperation at the end of turning travel of the elementary containers with respect to each other in order to lock the assembly obtained by the axial nesting elements. These arrangements are such that the assembly of the elementary containers can be obtained by a freely turning movement with no stresses on them and particularly on their wall due to their axial junction. Such a movement is easily performed by the user without effort that could generate stresses on the revolution wall of the elementary containers. This absence of stresses preserves the container and ensures an ideal centering of the elementary containers with respect to each other, and as a result ensures that the aesthetic line of the modular container is obtained and preserved. The rotation movement achieving a centering and an axial junction of the elementary containers is achieved by their snapping on to each other by means of the stops, in order to lock their axial junction and prevent their spontaneous separation by reverse rotation. The surfaces of the stops in snap-on cooperation can be limited and freely made irrespective of the methods of axial junction by rotating the elementary containers, which makes it possible to adapt them in accordance with the desired effort to be employed by the user in assembling the containers, and/or in accordance with the desired sturdiness of the walls of the elementary containers. Thus the designers can easily adapt the structure and/or the sturdiness of the stops irrespective of the sturdiness of the revolution wall of the elementary containers.

Preferably, the stops are integrated into the ramps and are in snap-on cooperation with them by snap-on in reaction to an elastic deformation of the nesting elements. These arrangements are such that the snap-on nesting of the elementary containers results from an elastic deformation of the nesting elements, while preserving the revolution wall of the elementary containers which is excluded from such elastic deformation. The result is that the revolution wall of the elementary containers can be sturdy because there is no need for its deformation, its resistance to deformation being independent of the means of assembly of the elementary containers with each other.

More particularly, the nesting elements are elastically deformable indifferently by means of the ramp and/or the stop of which they are a part, respectively, in order to reduce as much as possible the stresses exerted on the revolution wall of the elementary containers during their assembly, or conversely, during their separation.

The ramps are made respectively recessed and/or projecting indifferently on one and/or the other of the base and/or the neck of the elementary containers.

The stops are made respectively recessed and/or projecting indifferently on one and/or the other of the ramps respectively assigned to the base and/or to the neck of the elementary containers. The cooperation surface between the stops is advantageously spherical or similar.

The stops have a restricted surface area compared to the total area of contact between two assembled elementary containers. The arrangement of placing stops in cooperation by means of spherical surfaces is obtained, for example, from the forming of stops respectively as spherical dome and cup, or in a similar way as a cylinder or equivalent. Such spherical shape gives the stops a cam arrangement that can progressively cause the elastic deformation used for locking the assembly of elementary containers to each other. The result is ease of manipulation for the user and a limitation of stresses that can be applied to the revolution wall of the elementary containers.

Over all, the nesting elements associate at least one male nesting element and/or at least one female nesting element which are made indifferently in the base and in the neck. The nesting elements and the elementary container that comprise them are advantageously of a single molded piece, the nesting elements being advantageously integrated by molding into the elementary container either in a single molding operation or by over-molding. The molding operations are for example injection molding or blow molding operations. One advantage of forming the stops by over-molding is in the easy dissociation between the respective materials forming the elementary container and the stops that it comprises. Such dissociation makes it possible to adapt, from the choice of the appropriate material, the sturdiness of the revolution wall of the elementary containers and the malleability of the stops to promote snap-on ease while still providing said snap-on with enough resistance to obtain the locking of the assembly obtained between the elementary containers.

When a plurality of nesting elements and/or a plurality of ramps and stops integrated in one of these nesting elements are used, the respective male and female arrangement of the nesting elements, ramps and/or stops are to be considered individually. The female nesting element is preferably made in the base in order to form a recess for receiving the male nesting element that is made in the neck, although this distribution does not prejudge the male or female nature of the ramp or ramps and of the stop or stops respectively integrated into the nesting elements. More particularly, the male and female nesting elements can be respectively provided with one or more ramps and stops which are indifferently projecting or recessed not only from one to the other of the nesting elements, but also from one to the other for the same nesting element.

More specifically, at least one male nesting element is made to project on the neck and integrates into its section at least one ramp and at least one stop, while at least one female nesting element is formed from a recess that receives the projection made in the base, and includes in the periphery at least one additional ramp and at least one additional stop which cooperate respectively with the ramp and with the stop. The cooperating ramps are respectively arranged indifferently as female ramp for receiving the other male ramp. The cooperating stops are respectively arranged indifferently at female stop for receiving the other male stop. These male and female arrangements of ramps, as well as stops, are preferably combined for the same ramp or the same stop.

The nesting elements and the elementary container that comprises them are advantageously of a single piece and are formed by molding at the same time. The stops can be formed indifferently by molding at the same time with the nesting elements and/or can be added thereto by gluing, welding, over-molding or other similar joining technique. However, to improve production it is preferable to form the nesting elements, composed of the ramp and the stop, at the same time by molding with the container.

The cooperating stops are formed by additional snap-on reliefs that are made indifferently at the end of the ramps for a tangential connection of the elementary containers between each other with respect to their revolution conformation, and/or by snap-on reliefs made indifferently on the axial and/or peripheral faces of the nesting elements, and particularly ramps, for a radial connection of the elementary containers to each other.

According to a first variation of embodiment, a male nesting element is formed from a plate integrated by molding into the base or preferably into the neck. This plate includes a plurality of ramps radially distributed equally, at least one and preferably all of which form at least one stop. A female nesting element is formed from a molded recess of complementary shape inversely integrated into the molding of the neck or base.

For example, the ramps are arranged as grooves made in the section of the plate whose edges in projection and the middle recess together constitute a ramp.

The cooperating stops are preferably respectively arranged as dome and cup and are indifferently of axial extension by being placed on the shoulders respectively formed by the plate and the recess, and/or of radial extension by being placed on the sections respectively of the plate and the recess, and more particularly on the sections of the corresponding ramps, particularly at the bottom of the groove. More particularly, the stops are made, individually or in combination, on the axial faces or on the peripheral faces of the ramps.

The ramps are indifferently of circular or helicoidal extension, but preferably are helix shaped and constitute elements of axial thrust against the stops. More particularly, the ramps are indifferently of circular or helicoidal extension. However, the ramps are preferably helix shaped in such a way that they constitute elements of axial thrust against the stops. The ramps are capable of progressively pushing against the stops made in axial snap-on relief during the relative rotation between the elementary containers. Such progressive compression contributes to preserving the walls of the elementary containers, and promotes the spontaneous cooperation of the stops at the end of rotation travel of the elementary containers with respect to each other. Moreover, the user exerts a progressive effort of rotation on the elementary containers until they are locked in assembly, which improves the ergonomics of the container.

According to a second variation of embodiment, there is a plurality of ramps that are radially equally distributed and oriented along a generatrix of said conformation of revolution of the recess of the base and of the neck. The nesting elements are primarily oriented along this generatrix, and can extend totally or partially along this generatrix, preferably continuously without excluding an embodiment by which the nesting elements are in discontinuous extension by sections. The nesting elements, and more particularly the ramps, comprise respective cooperating stops that extend tangentially to said conformation of revolution.

The cooperating stops are for example constituted by at least a bead and a groove that are made respectively at the end of one and/or the other of the ramps respectively made in the base and neck. This bead and this groove are particularly of cylindrical conformation in order to allow for cooperation of a type similar to a spherical shape. The revolution surfaces of the bead and groove extend over a range of more than 180° in order to obtain their snap-on cooperation. Because the cooperating stops are made in the periphery of the base and neck, the axes of extension of the bead and groove are parallel and radially off center with respect to the axis of revolution of the base and of the neck.

It will be noted that the conformation of the outer surface of the modular container, except for the conformation of the area of revolution that includes the neck and which cooperates with the base, can be of any kind, such as polygonal and/or circular.

Preferred but not limiting applications of the modular container of the invention are packaging of food, cosmetics and/or therapeutic commodities for example, or any other perishable commodity. Such commodities may be, indifferently, liquids, gassy and/or volatile or not, solids, pulverulent and/or in gelled and/or in paste form, powders, make-up, creams or similar commodities.

The commodities contained respectively in the elementary containers can be identical or different commodities from one elementary container to another. In the case of different commodities, they can be products intended to be mixed immediately before use, for example, or products of the same nature but having different characteristics, such as color and/or condition and/or texture, for example.

DESCRIPTION OF THE FIGURES

The present invention and details pertaining thereto will be better understood from the following description of variations of embodiment in relation to the figures in the appended plates, in which:

FIGS. 1 and 2 are representations of a modular container according to a first embodiment of the present invention, respectively in profile view and axial cross-sectional view.

FIG. 3 is an axial cross-sectional representation of an elementary container comprising a modular container represented in FIGS. 1 and 2.

FIG. 4 is a detail in radial cross section of a pair of elementary containers of the type illustrated in FIG. 3, assembled to each other.

FIG. 5 is a top view of the elementary container represented in FIG. 3.

FIG. 6 is a representation in profile of a modular container according to a second embodiment of the present invention.

FIG. 7 is a representation in profile of an elementary container comprising the modular container represented in FIG. 6.

FIG. 8 is a top view of the elementary container represented in FIG. 7.

FIG. 9 is a representation in profile of an elementary container comprising a modular container according to a third embodiment of the invention.

FIG. 10 is a top view of the elementary container represented in FIG. 9.

In the figures, a modular container is comprised of a plurality of elementary containers 1 sequentially nested axially into each other. The number of three elementary containers 1 as illustrated is not limitative with respect to the scope of the present invention, said number of elementary containers 1 being at least two. These elementary containers 1 are similar and are advantageously obtained by molding from the same mold.

Each elementary container 1 comprises a neck 2, particularly with provision made so that it can be fitted with a removable cap 3 as illustrated in FIG. 3. The neck 2 includes a zone that is over-all cylindrical in shape, which is extended by a conical zone. The base 4 of the elementary container is recessed, this recess 5 having a shape complementary to the shape of the neck 2 in order to allow the sequential nesting of a plurality of elementary containers 1 in each other in order to obtain the modular container of the invention.

The conical zones of the neck 2 and of the base 4 comprise respective cooperating nesting elements 6 and 7. Each of said nesting elements 6, 7 associates at least one ramp 8, 9 and one stop 10, 11 cooperating with a complementary ramp 8, 9 and stop 10, 111 of an adjacent elementary container 1. The stops 10, 11 are elastically deformable in order to constitute the means of locking the assembly of elementary containers 1 to each other. The axial assembly between the elementary containers 1 is obtained from their relative rotation by cooperation of the ramps 8, 9 with each other. The travel of this rotation is limited by the stops 10, 11 which are in snap-on cooperation with each other in order to lock the axial assembly of elementary containers 1, while preventing their spontaneous reverse relative rotation.

More particularly, the assembly, and by analogy the separation of the elementary containers 1 in reverse, are respectively obtained by a mono-directional relative turning movement of the elementary containers 1. Such movement, simple to accomplish for the user, achieves in a first stage an axial assembly of the elementary containers 1, then in a second stage and without breaking this movement, the locking of this assembly. The locking and unlocking of the assembly of elementary containers 1 is obtained by respective movements that are of limited range and require limited effort by the user. Because these efforts are limited, the elementary containers 1 are preserved, their relative centering is assisted during their assembly, and the ergonomics of the modular container is optimized while achieving a comfortable manipulation for the user. The assembly of the elementary containers 1 is obtained from a quick and reliable relative rotation of the elementary containers 1 irrespective of the effort made by the user. The individual locking of this assembly is free of forces that could alter the conformation and/or alignment of the elementary containers 1 with respect to each other, and/or that could weaken or even damage them.

According to a first variation of embodiment illustrated in FIGS. 1 to 5, there is a plurality of nesting elements 6, 7 equally distributed radially at the periphery of the base 4 and the neck 2, respectively. Each of these nesting elements 6, 7 forms a ramp 8, 9 and a stop 10, 11, and they extend along an overall orientation corresponding to a generatrix of the conical zones of the base 4 and the neck 2. This extension should be understood in the geometric sense of the term, these nesting elements 6, 7 having a width extending over an angular range. In FIG. 5 more particularly, there are three nesting elements 6, 7 for each base 4 and neck 2, distributed at 120° so as to reinforce the centering of the elementary containers 1 with each other. The nesting elements 6 of the neck 2 are placed so as to partially overlap the nesting elements 7 of the base 4. With reference to FIG. 4, the purpose of this partial overlap is to allow an axial insertion of the neck 2 of a elementary container 1 into the base 4 of another elementary container 1′ without having to provide effort to nest them into each other, then to assemble the elementary containers 1, 1′ by cooperative hooking between the ramps 8, 9 which are respectively made on the nesting elements 6, 7 of the neck 2 and the base 4.

In FIG. 4, the ramp 9 of the ramps 8, 9 is formed from a cavity made in the base 4 of the elementary container 1 and opening toward the bottom thereof, and the other ramp 8 projects onto the conical zone of the neck 2 of the other elementary container 1′. The ramp 8, which includes the projecting nesting element 6 equipping the neck 2, is in particular in the form of a tongue, while the other ramp 9 that includes the cavity nesting element 7 equipping the base 4 is in the form of a groove made in the thickness of the base 4. Each of the nesting elements 6, 7 extends over an angular range P1 between 50° and 70°, and more particularly over a range of 60°. The ramps 8, 9 extend more particularly over an angular range P2 of between 15° and 25°, and more particularly over a range of 21°. The angular range P3 of overlap of the nesting elements 6, 7 between those of the neck 2 and those of the base 4 is on the order of 40°. It should be noted that these figures are given by way of example and are not limitative with respect to the scope of the present invention.

The stops 10, 11 are made at the end of the ramps 8, 9 in order to lock the axial assembly obtained by the cooperative hooking of the ramps 8, 9 with each other. This position of stops 10, 111 offers a snap-on locking from their elastic deformation. One of the stops 10 is formed by a bead made at the end of the tongue 6, and the other stop 11 is formed as a groove made at the bottom of the recessed groove 9, in order to receive the respective bead 10. In order to assemble two elementary containers 1, 1′ to each other for forming the modular container of the invention, the neck 2 of one of the elementary containers I′ is inserted by sliding it into the base 4 of the other elementary container 1. It will be noted that the nesting elements 6, 7 extend over a similar angular range, and the axial insertion of the neck 2 into the base 4 is guided radially and does not require any effort. Then at least one of the elementary containers 1 and/or 1′ is rotated to insert the tongues 8 into the respective grooves 9. Again, this operation is achieved with no special effort. Finally, at the end of the rotational travel of the elementary container 1 and/or 1′, a stronger rotational thrust exerted by the user causes the stops 10, 111 to snap on to each other, thus locking the nesting assembly of the two elementary containers 1, 1′. In order to separate the elementary containers 1, 1′ from each other, these maneuvers are simply reversed.

According to a second variation of embodiment illustrated in FIGS. 6 to 10, the nesting elements 6, 7 are formed by a plate 12 in projection on the neck 2 for the nesting elements 6, and by a recess 13 of complementary shape for the nesting elements 7 in a cavity made in the base 4 of the elementary containers 1. The plate 12 comprises three ramps 8 that are radially equally distributed and are made in its section so as to extend peripherally from the corresponding nesting elements 6. The hollow 13 comprises corresponding ramps 9 of complementary shape. Each ramp comprises a stop 10, 11 the depth of which is axially oriented. Spherical dome-shaped stops 10 are made to project axially at the upper face of the plate 12, while cup-shaped stops 11 are recessed in the hollow 13.

More particularly, in the embodiment illustrated in FIGS. 9 and 10, the ramps 8, 9 are further equipped with complementary shaped stops 14, 15 whose depth is radially oriented.

The ramp arrangement of the nesting elements allows them to be used easily to cause advantageously a progressive elastic deformation of the nesting elements, and a spontaneous locking of the assembly after the release of the nesting elements without the user having to exert any special effort to obtain the locking. More particularly in the embodiment illustrated in FIGS. 6 to 8, the upper face of the plate 12 defines the limit of the front ramps 16 which are inclined with respect to the axis of the elementary container 1, in order to form a helix that can induce a pressure against the stops 10, 11 during the rotational assembly movement between two elementary containers 1.