EP0962741B1 - Device for provisionally connecting and pyrotechnically separating two non-metallic units - Google Patents

Description

Technical area

The invention relates to a device using a pyrotechnic expansion tube to separate two sets initially connected to each other.

Such a device can in particular be used in the aeronautics and space industries, for provisionally link two structural units and to order their separation in a very short time.

State of the art

When two metal assemblies initially connected to each other must be separated so irreversible, in a very short time and by means of a remote control, we commonly use pyrotechnic cutting devices integrated in the junction area between the two sets.

When you want to make a clean cut, that is to say with a release of dust also as small as possible, we usually use a cutting device including an expansion tube pyrotechnic.

The expression "pyrotechnic expansion tube" designates a waterproof and deformable metal tube, in which walks a detonating cord. Soft material such as silicone rubber is interposed between the detonating cord and envelope. Before firing, the envelope has an oblong section, for example shaped like an ellipse or flattened circle.

When the detonating cord is ignited, the shock wave which propagates at very high speed the along the tube distorts the envelope and tends to give it a substantially circular section.

Usually a cutting device pyrotechnic including an expansion tube pyrotechnic is used to cut pieces metal. For this purpose, it is mounted in a space formed between two metal parts or between two parts of the same metal part. The room (s) to cut are pre-machined, so that present an area of reduced thickness according to each desired cutting line. Expansion of the envelope caused by the firing of the detonating cord translated by cutting the part (s) according to the cutting line corresponding to the machined area.

Cutting devices of one or two pieces metallic by means of an expansion tube are described in particular in the documents US-A-3 486 410, US-A-3 453 960, US-A-3 698 281, FR-A-2 598,796 and EP-A-0 273 061.

The structural elements used in the aeronautics and space industries are made of more and more frequently in materials not metal. In particular, the materials used are often composite materials, i.e. materials formed from long fibers arranged in layers superimposed according to preferential orientations, embedded in a resin matrix.

When such non-metallic materials are currently in use, it is not possible to cut directly using an expansion tube pyrotechnic as we used to do in the case of metallic structures.

Indeed, the direct cutting of a non-material metallic, in particular of the composite type, by means of a cutting device incorporating an expansion tube pyrotechnics could cause pollution significant environmental impact as well as a decrease sensitive to the mechanical characteristics of the structures Attached. In particular, this decrease would origin of so-called "delamination" phenomena, that is to say a detachment of the layers of fibers to near the cutting line.

For this reason, when a pyrotechnic cutting must be integrated currently in a non-metallic structure, we interpose the two structural sets to separate a structure metal whose cutting is ordered using a pyrotechnic expansion tube. In other words, the separation is ensured by cutting one or more metal parts attached to the assemblies structural non-metallic material that we want to separate.

This classic arrangement complicates the structure and increases the cost.

Furthermore, it goes against one of the essential benefits provided by materials not which is the gain in mass. Indeed, the addition of metal parts in the area of connection between the two structural units to be separated results in a significant increase in the mass. This increase in mass has in particular for origins the metallic character of the parts added and the essential presence of fasteners ensuring the connection between the metal parts and the non-metallic parts. This is a drawback particularly disadvantageous in certain applications such as the space industry.

In addition, the pyrotechnic cutting of parts metal imposes to generate a shock relatively important. This shock is applied to the devices and sometimes very sensitive instruments found in proximity.

Statement of the invention

The subject of the invention is precisely a temporary connection and separation device pyrotechnic, allowing direct separation of non-metallic assemblies, and in particular assemblies made of composite material, by means of an expansion tube pyrotechnic, preserving the mechanical properties of these sets after their separation, limiting pollution and by significantly reducing the shock caused during separation.

According to the invention, this result is obtained by means of a temporary connection device and pyrotechnic separation comprising a tube pyrotechnic expansion mounted in a space provided in a connecting area between two sets to separate, characterized in that the two sets are provisionally fixed to each other in the area bonding, by gluing pieces of non-material metallic able to be peeled off by setting work of the pyrotechnic expansion tube.

The use of the collage technique for connect the two sets, before their separation, allows to temporarily fix to each other non-metallic parts and eliminates the need for cut the pieces in order to separate them, in all where significant efforts should not be initially transmitted between the two sets.

Therefore, a clean and neat separation of the two sets is ensured, generating a shock much lower than when cutting parts metal. The mechanical integrity of the two sets is thus preserved, after their separation. it also protects devices and instruments Embedded.

Finally, a significant gain in mass is obtained, due to the disappearance of metal parts in the junction area between the two sets.

In a first embodiment of the invention, the parts comprise at least one part bonded to adjacent parts of a first piece and a second piece arranged end to end end and belonging respectively to each of said sets. The pyrotechnic expansion tube is then housed in a space formed opposite the room connection, substantially opposite said part adjacent to the second room.

In a second embodiment of the invention, the parts include at least one first room and at least one second room belonging respectively to each of said sets. An end portion of the second part is then glued to an end part of the first part, beyond an adjacent part of the second room delimiting said space.

Each of these two embodiments of the invention can be applied to the case where a first of sets to be separated includes a single first piece, a first spacer and a support piece, the second set comprising a single second piece. The space in which the expansion tube is received pyrotechnic is then delimited between the room support, the first spacer and the adjacent part from the second room.

Each of the two embodiments of the invention can also be applied to the case where a first sets to be separated includes first two pieces and a first spacer connecting these first pieces, the second set including two second parts and a second spacer connecting these second rooms. The space in which the tube is received pyrotechnic expansion is then delimited between said adjacent parts of the second parts and between the first and second spacers.

In the latter case, second means of fixing connect the second parts to the second spacer in a location remote from said space.

When each of the sets includes two pieces, the first set can also include a first soul that connects the first two pieces in outside the first spacer and the second together can include a second soul that connects two second pieces apart from the second spacer and said space.

Preferably, one side of the first spacer facing said space is substantially aligned with an edge of each first piece.

In addition, the first fixing means advantageously connect each first part to the first spacer, near said space.

Brief description of the drawings

• les figures 1A et 1B sont des vues en coupe qui représentent schématiquement une première forme de réalisation du dispositif conforme à l'invention, respectivement avant et après la séparation, dans le cas où seules deux pièces non métalliques doivent être séparées ;
• les figures 2A et 2B sont des vues en coupe schématique qui représentent une variante de réalisation du dispositif des figures 1A et 1B, respectivement avant et après la séparation, dans le cas où deux paires de pièces non métalliques doivent être séparées ;
• les figures 3A et 3B sont des vues en coupe qui représentent schématiquement une deuxième forme de réalisation du dispositif conforme à l'invention, respectivement avant et après la séparation, dans le cas où seules deux pièces non métalliques doivent être séparées ; et
• les figures 4A et 4B sont des vues en coupe schématique qui représentent une variante du dispositif des figures 3A et 3B, respectivement avant et après la séparation, dans le cas où deux paires de pièces non métalliques doivent être séparées.

Various embodiments of the invention will now be described, by way of non-limiting examples, with reference to the appended drawings, in which:

• Figures 1A and 1B are sectional views which schematically represent a first embodiment of the device according to the invention, respectively before and after separation, in the case where only two non-metallic parts have to be separated;
• Figures 2A and 2B are schematic sectional views which show an alternative embodiment of the device of Figures 1A and 1B, respectively before and after separation, in the case where two pairs of non-metallic parts must be separated;
• Figures 3A and 3B are sectional views which schematically represent a second embodiment of the device according to the invention, respectively before and after separation, in the case where only two non-metallic parts have to be separated; and
• Figures 4A and 4B are schematic sectional views which show a variant of the device of Figures 3A and 3B, respectively before and after separation, in the case where two pairs of non-metallic parts must be separated.

Detailed description of several forms of preferred embodiments of the invention

In FIG. 1A, the references 10 and 12 denote two structural sets, initially fixed to each other and that we want to be able to separate by implementing separation means pyrotechnic. The device according to the invention, which provides both the provisional link between sets 10 and 12 and their pyrotechnic separation, is generally designated by reference 14.

In this embodiment, the first and the second structural assemblies 10, 12, include, respectively, a first non-metallic part 16 and a second non-metallic part 18.

The non-metallic material in which are formed parts 16 and 18 can be of different natures, without departing from the scope of the invention. A preferred application relates to the case where this material is a composite material, formed of layers of fibers long embedded in a resin matrix. Like this is well known to those skilled in the art, such parts can be obtained by draping layers of fibers impregnated with thermosetting resin, then polymerization of the resin.

In addition, parts 16 and 18 can be of various forms, without departing from the framework of the invention. In the case illustrated in FIG. 1A, the parts 16 and 18 are in the form of plates, of substantially uniform and equal thicknesses. These plates can be flat, curved, or have any other form suitable for the intended application.

In the embodiment illustrated in the Figure 1A, parts 16 and 18 are placed edge to edge, in line with one another. In in other words, parts 16 and 18 are in contact against each other by adjacent edges, which have complementary shapes. These edges adjacent lines define the dividing line 20 between the two sets 10 and 12, when the means of separation of the device 14 are implemented. This dividing line 20 can take a form any (straight, curved, broken or other), without depart from the scope of the invention.

In the embodiment shown in the Figure 1A, parts 16 and 18 are initially fixed to each other through a piece of connection 22, of a non-metallic material, glued simultaneously on adjacent parts of these parts 16 and 18 and forming part of the device 14 according to the invention.

More specifically, the connecting piece 22 is in the form of a band which overlaps the separation line 20 between parts 16 and 18, of so as to be glued simultaneously on faces of these parts located in the extension of one another. This strip can be of uniform thickness, as represented or not uniform. Preferably, the bonding surface of the connecting piece 22 on the first part 16 is significantly lower than the bonding surface of this piece 22 on the second Exhibit 18. However, the dimensions of the two surfaces are sufficient to ensure the connection desired initial between parts 16 and 18, taking into account of the adhesive used.

Like the one that makes up parts 16 and 18, the non-metallic material in which the connecting piece 22 can be of any kind, without departing from the scope of the invention. advantageously, it is a composite material formed of plies of long fibers embedded in a resin matrix polymerized.

The adhesive by means of which the connecting piece 21 is glued to the adjacent parts of the pieces 16 and 18 can also be of any kind, without depart from the scope of the invention. He is chosen so to ensure a satisfactory fixation, taking into account forces to be transmitted between the parts 16 and 18, before their separation. This adhesive can in particular be a polymerized resin of the same nature than that which goes into the composition of parts 16, 18 and 22, when these are made of materials composites.

In addition to the connecting piece 22, which provides the provisional link between sets 10 and 12, the device 14 according to the invention comprises means for pyrotechnic separation of these two sets.

These pyrotechnic separation means in this case include an expansion tube 24 pyrotechnic, a support piece 26 and a spacer 28. These last two pieces can be separated, or made in one piece, as shown.

The pyrotechnic expansion tube 24 is performed in the same way as in the devices applied to the cutting of metal parts. However, it has a reduced dimension adapted to the bonding bond between parts 16 and 18. It therefore generates a shock wave significantly less than the tubes used in the cutting devices metal parts. A detailed description of the tube 24 with pyrotechnic expansion is therefore not necessary.

To facilitate understanding, it is simply remembered that the expansion tube 24 pyrotechnic includes a metal casing 30 waterproof and deformable, a detonating cord 32 housed at the interior of the envelope 30, as well as a material flexible 34 interposed between the detonating cord 32 and the envelope 30. The flexible material 34 has in particular for function to center the detonating cord inside of the envelope. As an example, it can be carried out made of silicone rubber. Before firing, the envelope 30 has an oblong section, by example in the shape of a flattened circle or oval, like illustrated in Figure 1A.

The pyrotechnic expansion tube 24 is received in a space 36 formed between the support piece 26 and the part of the second part 18 on which is glued the connecting piece 22. This space 36 is also delimited on one side by a face 38 of the spacer 28. Specifically, the longer section of the envelope 30 is oriented parallel to the direction defined by parts 16 and 18 to be separated.

Support piece 26 and spacer 28 belong to the first structural set 10. They are fixed to the first part 16, so that the face 38 of the spacer 28 is aligned with the separation line 20, i.e. with the edges in contact of parts 16 and 18.

In the embodiment illustrated on the Figures 1A and 1B, the support piece 26 and the spacer 28 form a single piece, distinct from the first piece 16. This unique piece is attached to the first part 16 by fixing means such as bolts (not shown) whose location is illustrated schematically by the dashed line 40. This location is as close as possible to face 38 of the spacer, i.e. the dividing line 20.

The nature and thickness of the materials constituting the support piece 26 and the spacer 28 are such that these two pieces are practically non-deformable during the implementation of the tube 24 to pyrotechnic expansion. This result is obtained either in using non-deformable thickness materials limited, such as metals, either by using relatively soft but stronger materials thickness, such as non-metallic materials, as illustrated in Figures 1A and 1B. In this last case, it should be noted that as a variant, the part support 26 as well as the spacer 28 can be made in one piece with the first part 16. The fixing means schematized by the mixed line 40 are then no longer necessary.

In all cases, the face of the support piece 26 facing the second room 18 constitutes a substantially non-deformable surface, generally parallel to the second part 18 and on which takes supports the pyrotechnic expansion tube 24, during the firing of the detonating cord 32. Consequently, the expansion of the envelope 30 takes place entirely in direction of the second room 18, as illustrated schematically Figure 1B.

It should be noted that the thickness of the tube 24 to pyrotechnic expansion is substantially equal to the clearance mounting, at the width of the space 36, between the second part 18 and the supporting part 26. An element (not shown) can be attached to the part support 26, or formed directly on this part so to close the space 36 opposite the spacer 28, if this is necessary to prevent the escape of the tube 24.

As shown in Figure 1B, When the detonating cord 32 is ignited, the wave of resulting shock causes the envelope to expand 30, which tends to take a section which is substantially circular. Since the expansion tube 24 pyrotechnic is supported on a part 26 substantially undeformable, its expansion occurs essentially towards the second room 18. It is therefore applied in full to this second Exhibit 18.

The fact that the first part 16 is integral of the support piece 26, via the spacer 28 and symbolized fixing means by the mixed line 40, there is therefore a relative displacement between adjacent parts of parts 16 and 18, in a direction perpendicular to these parts. This relative displacement is illustrated by the arrow F in FIG. 1B. It has the effect of taking off the connecting piece 22. More precisely, given that the bonding surface of the connecting piece 22 on the first part 16 is substantially less than the one that connects parts 18 and 22, connecting piece 22 comes off from the first piece 16. The connecting piece 22, on the contrary, tends to remain stick to the second part 18. It can however take off also, without departing from the the invention.

This creates a clean, clean separation and perfectly localized of the two sets 10 and 12, without causing a significant shock.

In FIGS. 2A and 2B, a variant of the first embodiment of the invention, which has just been described with reference in Figures 1A and 1B. This variant concerns the case where the device 14 according to the invention initially connects two sets 10 and 12 which each include a pair of parts 16 and 18, respectively, of materials not of metal.

More specifically, the first set 10 then comprises two first parts 16, substantially parallel to each other. These pieces 16 form by example the skins of a sandwich structure whose soul is formed by a foam material 42, such as a honeycomb material. Near an edge of first pieces 16 forming the separation line 20 of device 14, the foam material 42 is replaced by a first spacer 28, substantially dimensionally stable. One face 38 of this spacer 28, facing outward from the first set 10, is aligned with the corresponding edges of the first parts 16 on the separation line 20.

In the embodiment shown, the spacer 28 is fixed between the parts 16 by fixing means (not shown) such as bolts, symbolized by the dashed line 40 and placed at proximity to the separation line 20.

It should be noted that as a variant, the first spacer 28 can also be made in one piece with the first pieces 16.

The second set 12 includes in this case two second parts 18, substantially parallel one to the other. These second parts 18 form, by example, the skins of a second sandwich structure whose core is formed by a cellular material 44, such as a honeycomb material. Next to edges of the second pieces 18 aligned with the line of separation 20 of the device 14 according to the invention, the cellular material is removed, to delimit a space 36 between the end parts of parts 18. Beyond this space 36, the cellular material 44 is replaced by a second spacer 46, the face of which 48 facing outwards from the whole 12 delimits also space 36. The second spacer 46 is substantially undeformable.

In the embodiment shown, the second spacer 46 is fixed between the second parts 18 by fixing means (not shown) such as bolts, symbolized by a dashed line 50. These fixing means are as far apart as possible of the separation line 20 and of the face 48 of the spacer 46.

Alternatively, the second spacer 46 can be carried out in one piece with the second parts 18. It can also be deleted, as well as the cellular material 44, the two parts then being directly next to each other beyond space 36.

In this variant embodiment of the figures 2A and 2B, the device 14 according to the invention comprises two connecting pieces 22, made of non-material metallic, glued on the adjacent parts of each of parts 16 and 18, when these parts are placed end to end or edge to edge along the line of separation 20, as illustrated in FIG. 2A. More precisely, the pieces 22 are glued to the faces parts 16 and 18 opposite respectively to spacer 28 and space 36, that is to say on the faces of these parts facing outwards from sets 10 and 12.

The device 14 also includes a tube 24 with pyrotechnic expansion, placed in space 36, that is to say between surfaces 38 and 48 of spacers and between the end parts of second parts 18.

As shown schematically in Figure 2B, the implementation of the pyrotechnic expansion tube 24 has the effect of separating the parties from each other terminals of the second parts 18, making them pivot around their materialized fastening means by the dotted line 50. The connecting pieces 22 are thus detached from the first pieces 16 (arrows F) and elements 10 and 12 separated from each other.

Figures 3A and 3B show schematically a second embodiment of the device 14 according to the invention. As in Figures 1A and 1B, FIGS. 3A and 3B relate to the separation of two unique pieces 16 and 18 belonging to two separate sets 10 and 12 originally linked and that we want to be able to separate. The general layout is therefore comparable to that described above with reference to Figures 1A and 1B, so that it a new detailed description will not be made.

Essentially, the embodiment of Figures 3A and 3B differs from the first in nature connecting means by which the assemblies 10 and 12 are fixed to each other, before implementation of the pyrotechnic expansion tube 24.

In the case of FIGS. 3A and 3B, the part of link 22 is deleted and the link between the parts 16 and 18 is ensured by direct bonding of a part end of the second part 18 on a part end of the first part 16, opposite to the spacer 28. Parts 16 and 18 are therefore not placed end to end or edge to edge, but overlap on a specific surface in order to ensure the connection mechanical desired, before separation.

The pyrotechnic expansion tube 24 then acts on part of the second room 18 adjoining its end part fixed by gluing on the first Exhibit 16.

As before (Figure 3B), the implementation work of the pyrotechnic expansion tube 24 separates the sets 10 and 12, taking off in this case the second part 18 of the first part 16. For this purpose, the tube 24 is supported on the support piece 26, linked to the first part 16 through the spacer 28.

Figures 4A and 4B show a variant of the second embodiment of the invention, applied in case each of sets 10 and 12 includes two parts 16 and 18 respectively.

The layout is essentially identical to the one previously described with reference to Figures 2A and 2B. It will therefore not be described again in detail.

According to the second embodiment of the invention described above with reference to Figures 3A and 3B, the connecting pieces 22 are removed and the end portions of the second parts 18 are glued directly to the parts end of the first pieces 16, on the faces of these.

The implementation of the expansion tube 24 pyrotechnic (Figure 4B) has the effect of taking off simultaneously the two parts 18 of the two parts 16 and, therefore, to separate sets 10 and 12.

In general, the device 14 according to the invention allows, in all cases, a separation direct from two sets 10 and 12 made of non-material of metal, and in particular of composite materials, according to a clear and well located separation line, in satisfactory conditions of cleanliness.

It should be noted that the simultaneous separation of two pairs of parts (Figures 2A and 2B and 4A and 4B) is preferable, where possible, due to the perfect symmetry then presented by the device. Indeed, the energy required to ensure separation is then minimal.

In all cases, the direct separation of non-metallic materials results in a decrease sensitive to the energy required for separation, by compared to the prior art in which metal intermediate pieces were cut. Therefore, the shock caused by the separation is very significantly reduced, which is an advantage important with regard to facilities and equipment possibly on board near the device.

Finally, when the device comprises two pairs of parts (Figures 2A and 2B and 4A and 4B), the dividing lines 20 can either be aligned with the same spacer 28, as shown, aligned with each of the spacers 28 and 46.

Claims (9)

1. Provisional linking and pyrotechnic separation device comprising a pyrotechnic expansion tube (24) installed in a space (36) provided in a linking zone between two assemblies (10, 12) to be separated, wherein the two assemblies (10, 12) are provisionally fixed to one another in the linking zone, by the bonding of nonmetallic material parts (16, 18, 22) which can be detached by an operation of the pyrotechnic expansion tube (24).
2. Device according to claim 1, wherein the parts comprise at least one linking part (22) bonded to adjacent portions of a first part (16) and a second part (18) arranged end to end and respectively belonging to each of said assemblies (10, 12), said space (36) being formed opposite to the linking part (22) substantially facing the adjacent portion of the second part (18).
3. Device according to claim 1, wherein said parts comprise at least one first part (16) and at least one second part (18) respectively belonging to each of said assemblies (10, 12), an end portion of the second part (18) being bonded to an end portion of the first part (16), beyond an adjacent portion of the second part (18) defining said space (36).
4. Device according to either of the claims 2 and 3, wherein a first (10) of the assemblies to be separated comprises a single first part (16), a first spacer (28) and a support part (26), the second assembly (12) comprising a single second part (18), said space (36) being defined between the support part (26), the first spacer (28) and the adjacent portion of the second part (18).
5. Device according to either of the claims 2 and 3, wherein a first (10) of the assemblies to be separated comprises two first parts (16) and a first spacer (28) linking said first parts, the second assembly (12) comprising two second parts (18) and a second spacer (46) linking said second parts, said space (36) being defined between said adjacent portions of the second parts (18) and between the first and second spacers (28, 46).
6. Device according to claim 5, wherein second fixing means (50) link the second parts (18) to the second spacer (46) at a location remote from said space (36).
7. Device according to either of the claims 5 and 6, wherein the first assembly (10) comprises a first core (42) linking the two first parts (16) outside the first spacer (28) and the second assembly (12) comprises a second core (44) linking the two second parts (18) outside the second spacer (46) and said space (36).
8. Device according to any one of the claims 4 to 7, wherein a face (38) of the first spacer (28) turned towards said space (36) is substantially aligned with an edge of each first part (16).
9. Device according to any one of the claims 4 to 8, wherein first fixing means (40) advantageously link each first part (16) to the first spacer (28) in the vicinity of said space (36).

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