Ammunition and explosives – Having reaction motor – Having separation means
Reexamination Certificate
1999-06-02
2001-06-26
Carone, Michael J. (Department: 3641)
Ammunition and explosives
Having reaction motor
Having separation means
C102S378000, C102S312000, C102S313000, C089S001150, C089S001140
Reexamination Certificate
active
06250227
ABSTRACT:
TECHNICAL FIELD
The invention relates to a device using a pyrotechnic expansion tube for separating two initially interconnected assemblies.
Such a device can in particular be used in the aeronautical and space industries for provisionally linking two structural assemblies and for controlling their separation in a very short time.
PRIOR ART
When two initially interconnected metallic assemblies have to be irreversibly separated in a short time and by remote control, use is currently made of pyrotechnic cutting devices integrated into the junction zone between the two assemblies.
When it is wished to carry out a clean cutting, i.e. with a minimum amount of dust being released, use is generally made of a cutting device including a pyrotechnic expansion tube.
The express “pyrotechnic expansion tube” designates a tight, deformable, metal tube, in which runs a detonating cord or fuse. A flexible material, such as silicone rubber, is interposed between the detonating fuse and the envelope. Prior to firing, the envelope has an oblong cross-section, e.g. in the form of an ellipse or a flattened circle.
When the detonating fuse is fired, the shock wave which propagates at a very high velocity along the tube deforms the envelope and tends to give it a substantially circular cross-section.
Conventionally a pyrotechnic cutting device including a pyrotechnic expansion tube is used for cutting metal parts. To this end it is installed in a space formed between two metal parts or between two portions of the same metal part. The part or parts to be cut are previously machined, so as to have a reduced thickness zone along each desired cutting line. The expansion of the envelope caused by the firing of the detonating fuse leads to the cutting of the part or parts along the cutting line corresponding to the machined zone.
Devices for cutting one or two metal parts by means of a pyrotechnic expansion tube are more particularly described in the documents U.S. Pat. Nos. 3,486,410, 3,453,960, 3,698,281, FR-A-2 598 796 and EP-A-0 273 061.
The structural elements used in the aeronautical and space industries are increasingly frequently made from nonmetallic materials. In particular, the materials used are often composite materials, i.e. materials formed from long fibres arranged in the form of superimposed sheets in preferred directions and embedded in a resin matrix.
When such nonmetallic materials are used, it is not possible at present to directly cut them by means of a pyrotechnic expansion tube, as is normally the case with metallic structures.
Thus, the direct cutting of a nonmetallic material, particularly of the composite type, by means of a cutting device incorporating a pyrotechnic expansion tube might give rise to significant pollution of the environment, as well as to a significant reduction in the mechanical characteristics of the adjoining structures. This reduction would lead to so-called delamination phenomena, i.e. a detachment or separation of the fibre sheets in the vicinity of the cutting line.
Thus, when a pyrotechnic cutting device has to be used at present in a nonmetallic structure, interposing takes place between the two structural assemblies to be separated of a metallic structure, whereof the cutting with the aid of a pyrotechnic expansion tube is controlled. In other words, the separation is ensured by cutting one or more joined metallic parts on the nonmetallic material structural assemblies which it is wished to separate. This conventional arrangement makes the structure more complicated and increases its costs.
It is also in opposition to one of the essential advantages resulting from nonmetallic materials, which is the weight gain. Thus, the addition of metallic parts in the junction or connection zone between the two structural assemblies to be separated leads to a non-negligible weight increase. This weight increase is particularly due to the metallic character of the added parts and the indispensable presence of fixing members ensuring the connection between the metallic parts and the nonmetallic parts. This is a particularly prejudicial disadvantage in certain applications, such as in the space industry.
The pyrotechnic cutting of metallic parts also makes it necessary to produce a relatively high shock. This shock is applied to the equipment and instruments, which are often of a very sensitive nature and located in the vicinity thereof.
SUMMARY OF THE INVENTION
The object of the invention is a provisional linking and pyrotechnic separation device making it possible to directly separate nonmetallic assemblies and in particular composite material assemblies by means of a pyrotechnic expansion tube, whilst maintaining the mechanical properties of these assemblies following their separation, whilst greatly limiting pollution and significantly reducing the shock produced during separation.
According to the invention, this result is obtained by means of a provisional linking and pyrotechnic separation device comprising a pyrotechnic expansion tube installed in a space provided in a linking zone between two assemblies to be separated, characterized in that the two assemblies are provisionally fixed to one another in the linking zone, by bonding nonmetallic material parts liable to be separated by the use of the pyrotechnic expansion tube.
The use of bonding for linking the two assemblies prior to their separation makes it possible to provisionally fix to one another nonmetallic parts and eliminates the need to cut the parts in order to separate them, in all cases where high forces or stresses must not initially be transmitted between the two assemblies.
Consequently, a clean and precise separation of the two assemblies is ensured, whilst producing a much weaker shock than during the cutting of metallic parts. The mechanical integrity of the two assemblies is consequently maintained after their separation, which also protects the embarked instruments and equipment.
Finally, a significant weight gain is obtained, due to the disappearance of metallic parts in the junction zone between the two assemblies.
In a first embodiment of the invention, the parts comprise at least one linking part bonded to adjacent portions of a first part and a second part arranged end to end and respectively belonging to each of said assemblies. The pyrotechnic expansion tube is then housed in a space formed opposite to the linking part and substantially facing said adjacent portion of the second part.
In a second embodiment of the invention, the parts comprise at least one first part and at least one second part respectively belonging to each of said assemblies. An end portion of the second part is then bonded to an end portion of the first part, beyond an adjacent portion of the second part defining said space.
Each of these two embodiments of the invention can apply to the case where a first of the assemblies to be separated comprises a single first part, a first spacer and a support part, the second assembly comprising a single second part. The space in which is received the pyrotechnic expansion tube is then defined between the support part, the first spacer and the adjacent portion of the second part.
Each of the two embodiments of the invention can also apply to the case where a first of the assemblies to be separated comprises two first parts and a second spacer linking said first parts, the second assembly comprising two second parts and a second spacer linking said second parts. The space in which is received the pyrotechnic expansion tube is then defined between said adjacent portions of the second parts and between the first and second spacers.
In the latter case, second fixing means link the second parts to the second spacer at a location remote from said space.
When each of the assemblies comprises two parts, the first assembly can also comprise a first core linking the two first parts outside the first spacer and the second assembly can comprise a second core linking the two second parts outside the second spacer and said space.
Preferably, one face of the first spacer turned towards
Aerospatiale - Societe Nationale Industrielle
Carone Michael J.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Semunegus Lulit
LandOfFree
Provisional linking and pyrotechnic separation device for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Provisional linking and pyrotechnic separation device for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Provisional linking and pyrotechnic separation device for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2469560