EP1257482B1 - High energy shock absorbing wall structure and container using same - Google Patents

Description

Field of the invention

The field of the invention is that of transport of objects by container, that is to say in all cases where it is necessary to take precautions to guard against damage to objects transported. The invention relates in particular the containers constituting a protective envelope specific resistant to different aggression that may suffer transport packages during their trip, for example falls.

Prior art and problem

In the context of the transport of various objects, such as works of art, fragile objects or objects whose deterioration may give rise to risks for the environment, it is known to use transport containers with walls or damping parts, which, in case of shock or fall, absorb the energy due to the impact and avoid that the (or the object (s) is (are) damaged.

• Les conteneurs, du type « basse énergie », prévus pour résister à des chutes d'une hauteur inférieure au mètre. Si V est la vitesse du colis au moment de l'impact (V < 5 m/s). Dans cette catégorie de conteneurs, les masses sont généralement inférieures à la tonne. En conséquence, l'énergie d'impact est inférieure au kilojoule. Dans cette catégorie, se trouvent les conteneurs dimensionnés pour supporter les chutes inéluctables liées à la manutention, quelle qu'elle soit, des objets. L'impact est généralement absorbé par un dispositif amortisseur en matériau compressible, de type élastomère, placé à l'intérieur ou à l'extérieur du conteneur. L'écrasement de ce matériau protège l'objet à transporter.
• Les conteneurs, de type « moyenne énergie », doivent endurer des chutes dont la hauteur est supérieure au mètre (V > 5 m/s). Dans ce type de conteneur, la masse du colis, constitué par le conteneur et son contenu, peut atteindre plusieurs tonnes et l'énergie d'impact est comprise entre le kilojoule et le mégajoule.

There are currently three categories of containers, which are:

• Containers, of the "low energy" type, designed to withstand falls of less than one meter in height. If V is the speed of the package at the moment of impact (V <5 m / s). In this category of containers, the masses are generally less than one tonne. As a result, the impact energy is less than the kilojoule. In this category, there are the containers sized to withstand the inevitable drops related to the handling, whatever, of the objects. The impact is generally absorbed by a damping device of compressible material, elastomeric type, placed inside or outside the container. The crushing of this material protects the object to be transported.
• Containers of the "medium energy" type must withstand falls greater than one meter (V> 5 m / s). In this type of container, the mass of the package, consisting of the container and its contents, can reach several tons and the impact energy is between the kilojoule and the megajoule.

• Les conteneurs, de type « haute énergie », doivent supporter des chutes dont la hauteur est supérieure à la dizaine de mètres (V > 10 m/s). Les masses des colis peuvent alors atteindre plusieurs dizaines de tonnes et l'énergie d'impact est supérieure au mégajoule. Dans cette catégorie se trouvent les conteneurs dimensionnés pour supporter des chutes accidentelles lors de transports de type aérien. La structure d'un tel conteneur doit pouvoir se déformer, mais raisonnablement, à l'impact de la chute, de manière à ne pas endommager l'objet contenu. Un tel conteneur nécessite l'utilisation d'un amortisseur pour limiter le plus possible l'effet du choc vis-à-vis de l'objet transporté. L'absence de matériau de raideur intermédiaire entre le bois et le métal conduit généralement à choisir, par défaut, le bois comme matériau amortisseur. Le bois ayant un palier de compression relativement faible, le dimensionnement de ce type de conteneur conduit à avoir des épaisseurs importantes de bois pouvant dépasser le mètre, de manière à ce que l'écrasement de celui-ci ne soit pas totalement terminé à la fin de l'impact. En effet, dans ce cas, il n'y aurait plus d'amortisseur à la fin de l'impact.

In this category are the containers sized to be able to withstand accidental drops, related to the handling of the transported objects. The container has a structure dimensioned so as to be able to deform substantially to the impact of the fall to avoid damaging the transported object. In addition, it is necessary to add a damper to limit the shock transmitted to the object. This damper is placed inside or outside the container and is deformable material, for example wood or balsa.

• Containers, of the "high energy" type, must withstand falls greater than ten meters (V> 10 m / s). The masses of the packages can then reach several tens of tons and the impact energy is greater than the megajoule. In this category are containers designed to withstand accidental drops during air transport. The structure of such a container must be able to deform, but reasonably, the impact of the fall, so as not to damage the object contained. Such a container requires the use of a damper to minimize the impact of the impact vis-à-vis the object transported. The absence of intermediate stiffness material between the wood and the metal usually leads to choosing, by default, the wood as damping material. The wood having a relatively low compression bearing, the dimensioning of this type of container leads to having significant thicknesses of wood may exceed one meter, so that the crushing thereof is not completely completed in the end impact. Indeed, in this case, there would be more buffer at the end of the impact.

The main purpose of the present invention is to propose, for this last category of containers of the "high energy" type, walls or intermediate damping structures between solutions using wood and those using metals. In addition, we want to have a damping system adjustable according to the dimension of the container, that of the contained object and the shocks to endure.

On the other hand, WO-93 00845 discloses a damping structure. It is constituted mainly one or more layers consisting of at least one flat plate on which is plated or positioned a second bent plate, to form polygonal pads, as in cells used for storing eggs. he is mentioned that the inside of these hollow studs can be filled with gas or elastic material, these the latter can resume their form once they have been deformed.

Summary of the invention

For this purpose, a first main object of the invention is a damping wall structure of high-energy shock, consisting mainly of carrier structure in which are distributed regular metal studs, the density of studs in the supporting structure depending on the crush resistance to obtain. This resistance to crushing is also defined according to conditions of transport and objects transported.

In its preferred embodiment, the carrier structure is alveolar, the studs being placed in some cells.

In this patent document, the term "Plot" is used to express a solid piece and hard, exceeding in relation to two surfaces of the carrier structure between which this piece is placed.

Preferably, this alveolar carrier structure is a honeycomb structure.

One of the materials chosen to achieve this Alveolar bearing structure is aluminum.

In a special realization of the structure carrier, multiple layers are used superposed and alveolate, the studs being offset one against another, from one layer to another.

A second main object of the invention is a transport container that has to withstand significant falls and including at least one wall constituted, at least in part, of a wall defined in the previous paragraphs for cushion high energy shocks.

A particular achievement of this container is intended to carry the objects elongated, such as the fuel rods of nuclear center.

In this case, the container is the shape of a cylindrical body, closed to these two ends, whose walls of these are covered by a structure, as defined in the paragraphs above.

A holding cover can cover and maintain each damping structure.

List of Figures

• figure 1, en coupe, le principe d'un conteneur de transport à protection globale ;
• figure 2, un schéma de la répartition des plots, dans la structure alvéolaire selon l'invention ;
• figure 3, un plot utilisé dans la structure alvéolaire selon l'invention ;
• figure 4, en vue cavalière, une réalisation de la structure selon l'invention à plusieurs couches ;
• figure 5, en coupe, l'application de la structure selon l'invention à un conteneur destiné à transporter un objet allongé ; et
• figure 6, en vue cavalière, le conteneur représenté à la figure 5.

The invention and its preferred embodiments will be better understood on reading the following description, accompanied by several figures representing, respectively:

• Figure 1, in section, the principle of a transport container with overall protection;
• Figure 2, a diagram of the distribution of the pads in the honeycomb structure according to the invention;
• FIG. 3, a stud used in the honeycomb structure according to the invention;
• Figure 4, in a cavalier view, an embodiment of the structure according to the invention with several layers;
• Figure 5, in section, the application of the structure according to the invention to a container for transporting an elongate object; and
• Figure 6, in a cavalier view, the container shown in Figure 5.

Detailed description of a realization of the invention

Figure 1 shows in section, a container of the high energy type, according to the invention. He understands mainly a rigid structure 3 consisting of several relatively thick walls and forming a crate or box closed. Inside this one there are locking elements 2 to immobilize the object to be transported 1 positioned in the center of the container, optimally.

With reference to Figure 2, in fact, the wall structure according to the invention is constituted mainly of a carrier structure 4 alveolar, for example of the hexagonal type, of the honeycomb type.

This supporting structure 4 is made of metal, for example aluminum, and therefore does not have a mass, given the large number of spaces voids, constituted by the cells 6. It has for function to keep in place studs 5, distributed uniform way throughout the supporting structure 4. In the case shown in FIG. 2, studs 5 are arranged in a row so that these studs 5 are uniformly distributed, for example, for that each stud 5 is separated from another by three empty cells 6. The filling rate thus obtained is around 15%. It depends on the surface of pads relative to the total area.

It's easy to understand that density of studs 5 in the supporting structure 4 depends on several parameters concerning the conditions of possible drops of the container.

Indeed, the impact of the container on the ground or on any obstacle depends on the mass M of the container and the object to be protected, the impact velocity V, the working surface S of the container crushing and the acceptable thickness of the crash E of the damper. The damping surface can be characterized by a plastic compression bearing ideal for crushing σ _pal . The structure of the container and the object to be protected must be able to support an acceleration γ _max without crippling deformation. Using the following two approaches: γ max = σ pal xS M σ pal = MxV 2 2xSxE the range of values can be determined to define the plastic bearing of the damping material to be used. We therefore deduce that σ _pal is between 25 and 300 megapascals.

In addition, it defines a surface occupation rate or filling rate of the honeycomb structure: α = S damping pads Working container which corresponds to the density of the studs. For a surface occupation rate α of between 1/100 and 90/100, the plastic compression stage σ _pal = σ _e × α, where
σ _e is the elastic limit stress of the material constituting the damping pads, hence 0.01 σ e <σ pal <0,90 σ e . (The compression bearing of the structure is neglected).

By having a wide range of materials and adapting the occupancy rate to the conditions of fall or impact, it is possible to choose a damping material having a characteristic value σ _pal sought.

With reference to FIG. are metallic and can be of a cylindrical shape. It is also possible to consider using spherical shapes or adapted to the shape of cells 6 of the structure alveolar carrier 4. The height, or so generally, the dimensions of the studs 5 are adjusted in function of the efforts generated locally by crushing on impact. Lead, tin, steel, titanium are among the many metals that can be used in this type of wall. The choice of metal results, inter alia, from the structure pre-existing container and uses secondary or possible side of the damping wall, for example a "radiator" function, favoring heat exchange.

With reference to FIG. 4, an advantageous embodiment of the damping structure according to the invention consists of several layers. More precisely, several layers 7 _N , 7 _{N + 1} , ... carrying structures, symbolized by plates drawn in phantom, are superimposed. They each contain a number of pads 5, regularly distributed in the manner explained above. It should be noted that it is not necessary to superimpose the pads 5 _N of a layer 7 _N above the pads 5 _{N + 1} of the layer 7 _{N + 1} or layers directly adjacent thereto. On the contrary, it is essential to shift the pads 5 _{N + 1} in each layer 7 _{N + 1} relative to the positioning of the pads 5 _N of the adjacent layer 7 _N. Thus, the pads 5 _N of the layer 7 _N are offset by a distance equal to half the distance separating them, with respect to the pads 5 _{N + 1} of the directly adjacent layer 7 _{N + 1} . Thus, during an impact resulting in partial or total crushing of the damping structure, the studs 5 _N tend to deform the layer 7 _{N + 1} located just behind, at a place where there is no stud 5 _{N + 1} worn by the latter. Conversely, the studs 5 _{N + 1} will tend to deform the layer 7 _{N in} front, since no 5 _N stud will be directly opposite.

Thus, the characteristics of the damping structure thus formed result from the stacking of a number of layers 7 _N , 7 _{N + 1} , 7 _{N + 2} , ..., and the distribution of the pads 5 _N , 5 _{N + 1} , 5 _{N + 2} , ..., found in each of them.

In the case of application to a container, the protection of it may be only when the direction of impact is known to advance. Thus, it is possible to consider not cover only part of the sides of the container with a damping structure according to the invention.

For example and with reference to FIG. it is envisaged to build a container likely to carry an elongated object 10 whose length exceeds several meters. In this case, the notebook loads imposes to withstand an impact at a speed of 90 meters / second, the total mass of the container and its object being of the order of 20 tons, the diameter of the impact being of the order of 2 meters. This container mainly comprises a case 11, in which is placed the object 10, preferably doubled by a body outside 12. The whole is closed at its ends. These are each covered with a thickness determined of the damping structure defined previously and referenced 13. The latter may possibly be covered with a lid of 14. In the case of such a container, in using thirty layers of wall structure previously described, showing an occupancy rate plots of about 30%, these being of a diameter of about 5 mm and a height of about 10 mm, we obtain an effective crushing of about 20 cm. In other words, the thickness of the layer the protector is 30 cm, it is reduced after the impact, to a thickness of 10 cm. Together, the deformation of these pads due to acceleration resulting from the order of 2500 g jointly provokes an increase in the diameters of each stud. From this actually, these tend to occupy most of free space, beforehand.

It will be easily understood that for heavy containers, it is possible to experience falls consequent whose speeds are very important, especially greater than 100 meters / second.

The modular nature of the load-bearing structures used in the structure according to the invention, such as honeycomb plates, makes it easy to change the level of occupation of the studs or the nature of these studs. It is thus possible to play on the compression characteristic σ _e of the material constituting the studs and on their thickness to reach the desired plastic compression stage σ _pal .

Claims (8)

1. High energy impact shock-absorbing wall structure, chiefly made up of a bearing structure (4) in which metal blocks (5, 5_N, 5_N1) are regularly distributed, the density of the blocks in the bearing structure (4) being dependent upon the desired crush resistance.
2. Shock-absorbing wall structure according to claim 1, characterized in that the bearing structure (4) is cellular, the blocks (5, 5_N, 5_N1) being placed in some of the cells (6) of the bearing structure (4).
3. Shock-absorbing wall structure according to claim 2, characterized in that the cellular bearing structure (4) is a honeycomb structure.
4. Shock-absorbing wall structure according to claim 3, characterized in that the cellular bearing structure (4) is in aluminium.
5. Shock-absorbing wall structure according to claim 1, characterized in that the bearing structure (4) is a structure with several superimposed cellular layers (7, 7_N, 7_N+1, ...), the blocks (5, 5_N, 5_N1) being staggered relative to one another and from one layer to another.
6. Transport container which must withstand major falls, comprising at least one wall formed at least in part of a wall structure according to any of claims 1 to 5 to deaden high energy impacts.
7. Transport container according to claim 6, intended to transport an elongated object (10), formed of a cylindrical body (11) closed at its two ends, characterized in that the high energy impact shock-absorbing wall structures are walls (13) each covering one end of the cylindrical body (11).
8. Transport container according to claim 7, characterized in that it comprises a lid (14) covering the shock-absorbing wall structures.

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