FR2957552A1 - Manufacturing heat insulation wall that is useful in aircraft, by forming panel having dimension that is equal to developed surface of wall and combining external and internal plates of panel by thermoforming press and using adhesive films - Google Patents

Abstract

The process comprises forming a panel (16, 17) having dimension that is equal to developed surface of a heat insulation wall (14), and combining external and internal plates of panel by thermoforming press and using adhesive films. The panel has a sandwich structure including external plates made of a thermoformable composite material, where an internal plate made of a thermoformable composite heat-insulating material is inserted between the external plates. The heat insulation wall comprises an assembly zone, and a radiating surface zone (19) arranged between assembly zone and common zone. The process comprises forming a panel (16, 17) having dimension that is equal to developed surface of a heat insulation wall (14), and combining external and internal plates of panel by thermoforming press and using adhesive films. The panel has a sandwich structure including external plates made of a thermoformable composite material, where an internal plate made of a thermoformable composite heat-insulating material is inserted between the external plates. The heat insulation wall comprises an assembly zone, and a radiating surface zone (19) arranged between the assembly zone and common zone. The thermoforming press comprises gap of variable height adapted to rub the internal plate at the assembly zone and to maintain insulating properties in surface of the wall. The thermoformable composite material is made of thermoplastic polyetherimide glass. The internal plate is constituted of a polyetherimide thermoplastic material that is present in the form of a polyetherimide foam or a honeycomb structure. An independent claim is included for a heat insulating separation wall.

Description

METHOD OF MANUFACTURING THERMALLY INSULATING PARTITION FOR A. CABINET. ELECTRICAL.NOTAMENT FOR AIRCRAFT, AND SEPARATION PARTITION

The invention relates to a method for manufacturing a thermally insulating separating partition of two volumes in which different temperatures prevail, for an electrical cabinet intended for the integration of equipment and electrical wiring, especially in an aircraft. It extends to partition walls made according to this manufacturing method. The electrical cabinets embedded in the aircraft are designed to perform several functions vis-à-vis the computers they integrate, among which a cooling function of these computers. For this purpose, and as for example described in the patent application WO2006 / 010840, these electrical cabinets comprise shelves composed of a rigid upper plate adapted to support the computers, and a rigid lower tray shaped dish with a bottom pierced with orifices, delimiting with the upper plate a box with an air passage communicating with a hot air exhaust system. In addition, a cold air supply network is adapted to deliver cold air over the upper tray of each shelf. According to this design, the cold air delivered above each shelf cools the computers positioned on the upper plate of said shelf, and the air thus heated enters the box formed by the trays of the upper level shelf, before being extracted to the hot air exhaust system. According to this principle, the upper plate of each shelf thus constitutes a physical partition wall between a hot air flow and a cold air flow, and this plate must therefore form a thermally insulating barrier in order, on the one hand, to guarantee optimum conditions for cooling the computers, and secondly, to avoid any condensation phenomenon in contact with this partition, which may damage the equipment. The current solution, in order to achieve this thermal insulation, is to stick on the upper plate a closed cell foam plate. This solution, however, has several disadvantages. Indeed, and first, the assembly of the foam plate on the rigid upper plate requires gluing means whose implementation is industrially difficult. In practice, this operation is in fact carried out according to a manual process which proves to be relatively expensive. In addition, there are risks of subsequent detachment of the foam plate, the consequence of which is a closure of the cold air supply passage, and therefore a very damaging interruption of the cooling of the computers positioned on the upper plate in cause. It should be noted, moreover, that such a deterioration of the upper plate causes significant repair costs, especially in the aeronautical field, because it requires an intervention inside the aircraft concerned and therefore an immobilization of the latter The present invention seeks to overcome these drawbacks and its main objective is to provide a method of manufacturing thermally insulating partitions for electrical cabinets, on the one hand leading to savings compared to the current manufacturing costs of such partitions, and on the other hand, guaranteeing a high reliability and durability of the products produced. Another object of the invention is to provide a manufacturing method for increasing the performance of partitions made in terms of thermal insulation. Another object of the invention is to provide a manufacturing method leading to a gain in mass at equal performance. For this purpose, the invention relates to a method of manufacturing a thermally insulating partition wall for an electrical cabinet, in particular for aircraft, said method consisting according to the invention: - to produce a panel of dimensions at least equal to the developed surface of the partition, having a sandwich structure composed of two outer plates of thermoformable composite material between which is inserted an inner plate thermoformable thermally insulating composite material, and to secure the outer and inner plates, and to conform the panel so to give it the final shape of the partition. According to the method of the invention, the insulating element is incorporated in the partition wall and no longer attached thereto, and the two functions of mechanical strength and thermal insulation are obtained by means of a single element. In other words, the industrial process which, at the present time, made it possible to produce the only rigid part of the insulating partitions such as the upper trays of the shelves of the electrical cabinets, leads, according to the method of the invention, to produce the rigid part. as well as the insulating part. The invention thus leads to a reduction in the cost of production as well as to a significant increase in the service life of the finished products, in particular because of the elimination of the risks of separation of the insulating layer of the said products. Furthermore, it has been found that, with equal insulation performance, the partition according to the invention makes it possible to obtain a significant gain in mass and greater rigidity. According to an advantageous embodiment of the invention, the joining of the outer and inner plates of the panel and the conformation of the panel are carried out by thermoforming. Moreover, according to this principle, the outer and inner plates of the panel are advantageously secured by means of adhesive films inserted between each of said outer plates and the inner plate. In the usual manner, the partitions contemplated by the invention comprise at least one assembly zone for fastening said partition during assembly of the electrical cabinet. In this case and advantageously according to the invention, the panel is conformed by means of a thermoforming press comprising a gap of variable height capable of allowing the internal plate to be crushed at each assembly zone, and to preserve said inner plate its thickness conferring its insulating properties at the other common surface areas of the partition. This embodiment makes it possible to obtain a partition whose entirety of the "useful" surface (surface in contact with volumes in which different temperatures prevail, thus having a function of separating and isolating said volumes) integrates a thickness of insulating element, and whose assembly areas have maximum rigidity and flatness and thus accept any mode of mechanical attachment or other, In addition, when the partition is shaped so as to include radiated surface areas of link between the assembly areas and the current areas of said partition, the air gap of the press advantageously has a variable height adapted so that each radiated area has a decreasing thickness of the current area to the assembly area. Advantageously according to the invention, the outer plates consist of a composite material consisting of thermoplastic polyetherimide glass. The inner plate is, for its part, advantageously made of a thermoplastic polyetherimide material in the form of a PEI foam or in the form of a "honeycomb" structure. The invention extends to a partition wall for an electrical cabinet intended for the integration of equipment and electrical wiring, particularly in an aircraft. According to the invention, this partition consists of a panel shaped so as to give it the final shape of said partition, having a sandwich structure composed of two outer plates of thermoformable composite material between which is inserted and secured an inner plate thermoformable thermally insulating composite material. In addition, as an exemplary embodiment, this partition wall may consist of an upper plate of a shelf further comprising a lower tray in the form of a bowl, said plates being adapted to delimit a box intended to be connected to a ventilation network, and having longitudinal edges of support and assembly of the upper plate on the lower plate. According to the invention, the inner plate of this upper plate then advantageously has a thickness which confers its insulating properties on the surface of said upper plate delimiting the box, and a minimum thickness obtained by crushing at the longitudinal edges. from this upper plateau. This partition wall can also consist of a partition wall of a box in two respective flow ducts of a hot air flow and a cold air flow, the said partition having longitudinal fixing flanges of the latter inside the box. According to the invention, the inner plate of this partition then advantageously has a thickness which confers on it its insulating properties at the level of the surface of the said partition wall of the two ducts, and a minimum thickness obtained by crushing at the level of the longitudinal flanges. of the latter. Moreover, when the partition wall has radiated surface areas of connection between the current zones and the longitudinal edges of said partition, each radiated zone advantageously has a decreasing variable thickness of the current zone of the partition towards its longitudinal edges, obtained by progressive crushing of the inner plate Other objects, features and advantages of the invention will emerge from the detailed description which follows with reference to the accompanying drawings which show by way of non-limiting examples two preferred embodiments thereof. drawings: FIG. 1 is a diagrammatic perspective view of an electrical cabinet, in particular for an aircraft, comprising shelves according to the invention, FIG. 2 is a perspective view, in exploded mode, of the two trays, of which an upper plate made according to the method of the invention, forming the shelves of this cabinet electric. FIG. 3 is a cross-section on an enlarged scale, through a plane A of FIG. 2, of the top plate according to the invention of one of these shelves; FIG. 4 is a representative perspective view of the elements constituting this upper plate, - Figure 5 is a partial view, in cross section, of a box divided into two longitudinal air flow ducts by a longitudinal partition made by a method according to the invention, - and FIGS. 6a and 6b are two representative diagrams of two steps of realization, according to the process according to the invention, of the upper plate represented in FIG.

The method according to the invention aims at the realization of partition walls of two volumes in which different temperatures prevail, such as two volumes in which a flow of hot air flows respectively and a flow of cold air, for a cabinet electrical 1 for the integration of equipment and electrical wiring, particularly in an aircraft, said cabinet comprising, as shown in Figure 1, two uprights 2, 3 between which are mounted shelves such as 4 and 5. In the usual way, one of the uprights 3 of the electrical cabinet 1 is adapted to form a cold air supply duct and comprises openings, such as 6, opening above each of the shelves 4, 5, so as to to allow the cooling of the material resting on said shelves. In addition, each of the shelves 4, 5 forms a box with a perforated bottom wall, adapted to communicate with a hot air exhaust duct formed inside the second upright 2 of the electrical cabinet. According to this design, the cold air delivered above each shelf 4 cools the computers positioned on said shelf, and the air thus heated enters the box formed by the shelf 5 of upper level; before being extracted to a hot air exhaust system. Also known per se, and in order to form a box, each shelf 4, 5 consists of two trays consisting of a lower plate 7 and an upper plate 14.

Each lower plate 7, made for example of a composite material, has the shape of a bowl with a bottom wall 8 pierced with orifices 8a, delimited, on the one hand by two longitudinal walls 9 each defining a rim upper support of the upper plate 14, and secondly by two transverse walls 10, 12 each pierced by an opening, respectively 11, 13 of air flow Each upper plate 14 consists, meanwhile, of a flat wall 15 delimited. - transversely, by two sections 16, 17 longitudinally inclined, adapted so that the opening 11 formed in one of the transverse walls IO of the lower plate 7 opens above the upper plate 14, and the opening 13 formed in the other wall transverse 12 of the lower plate 7 opens into the volume defined by said lower plate and the upper plate 14, - and, longitudinally, by two support flanges 18 on the edges of the longitudinal walls 9 of the lower plate 7, to which the plane wall 15 is connected by radiated surface side regions 19. In accordance with the invention, this upper plate 14 has a sandwich structure and is composed of: - d external plates 20, 21 of a thermoformable composite material 30 consisting for example of thermoplastic polyetherimide glass, - an inner plate 22 inserted between the two outer plates 20, 21 and made of a thermoformable composite material th hermetically insulating material such as a polyetherimide thermoplastic material in the form of a PE] foam or in the form of a "honeycomb" structure, two adhesive films 23, 24 each inserted between one of the plates 20, 21 and the internal plate 22 ..

In addition, this upper plate 14 is shaped so that: - the inner plate 22 has a normal thickness conferring its insulating properties on the entire surface of the flat wall, 15; a minimum thickness obtained by crushing at the longitudinal edges 18, a variable thickness at the level of the radiated surface areas 19 of connection between the plane wall 15 and the longitudinal flanges 18, obtained by a progressive crushing of the internal plate 22 Such an upper plate 14 is advantageously made by thermoforming a panel of dimensions at least equal to the developed surface of said upper plate, by means of a thermoforming press P to which each panel is fed after a preliminary step of heating carried out in an oven. As shown in FIGS. 6a and 6b, this thermoforming press P comprises, according to the invention, a matrix M and a punch Po adapted to delimit, in the closed position of said press, a gap of variable height - a gap a maximum value for forming the flat wall 15 of the upper plate 14, adapted to keep the inner plate 22 its maximum thickness, - a gap e2 of minimum value for forming the longitudinal flanges 18, adapted to crush the plate 22 in order to obtain flanges 18 having a maximum stiffness, in order to obtain a rigid attachment, for example mechanical, on the edges of the longitudinal walls 9 of the lower plate 7, and a gap of value decreasing from e2 to el for shaping the radiated surface areas 19 of connection between the flat wall 15 and the longitudinal flanges 18.

FIG. 5 represents another embodiment of partition wall according to the invention, consisting of a partition 27 for separating a caisson into two conduits 25, 26 for the respective flow of a flow of hot air and for a cold air flow.

As shown in FIG. 5, and in a manner similar to the upper plate described above, this partition 27 is composed of: a flat surface portion 28, effective separation of the two ducts 25, 26, at the level of which the inner plate 22 has a maximum thickness conferring its insulating properties, - longitudinal edges 29 for fixing inside the box, having a minimum thickness obtained by crushing the inner plate 22, - and radiated surface areas 30 of connection between the flat surface portion 28 and the longitudinal flanges 29, having a decreasing variable thickness obtained by a progressive crushing of the inner plate 22. Such partitions 27 may in particular be integrated in the podions of the uprights and / or the cross members of the cabinet in which the flow of hot air and the flow of cold air are conveyed together, and for example, if one refers to the electrical cabinet d W020061010840 written in the patent application, in amounts such as 2 forming a casing delimited by two end walls 2a, 2b.

Claims (2)

Revendications1. Method for manufacturing a partition (14, 27) thermally insulating separation of two volumes in which different temperatures prevail, for an electrical cabinet (1) intended for the integration of equipment and electrical wiring, particularly in an aircraft , said method being characterized in that: - a panel of dimensions at least equal to the developed surface of the partition (14, 27), having a sandwich structure composed of two external plates (20, 21) of composite material is produced; thermoformable between which is inserted an inner plate (22) thermoformable thermally insulating composite material, is secured to the outer plates (20, 21) and inner (22), and the panel is conformed to give it the final shape of the partition (14, 27), 2. Method according to claim 1 characterized in that the securing of the outer plates (20, 21) and inner (22) of the panel and the conformation of said panel are made by thermoferming. 2. Method according to claim 2 characterized in that one secures the outer plates (20, 21) and inner (22) of the panel by means of adhesive films (23, 24) inserted between each of said external plates and the internal plate. 4. Method according to one of claims 2 or 3 for manufacturing a partition (14, 27) having at least one assembly area (18> 29) for fixing said partition during assembly of the cabinet electrical (1), characterized in that the panel is conformed by means of a thermoforming press (P) having an air gap (el, e2) of variable height capable of allowing the internal plate (22) to be crushed level of each assembly zone (18, 29), and to keep the said inner plate its thickness conferring its insulating properties at the other common surface areas (15, 28) of the partition (14, 27). 5. Method according to claim 4 for manufacturing a partition (14, 27) shaped to have radiated surface areas "19, 30) for connection between the joining zones (18, 29) and the common zones (15, 28) of said partition, characterized in that the gap (el, e2) of the press (P) has a variable height adapted so that each radiated zone (19, 30) has a decreasing thickness of the current zone (15, 28) to the assembly area (18, 29). 6. Method according to one of the preceding claims characterized in that the outer plates (20, 21) consist of a composite IO material consisting of thermoplastic polyetherimide glass, 7. A method according to one of the preceding claims characterized in that the inner plate (22) is made of a thermoplastic polyetherimide material in the form of a PEI foam or in the form of a "honeycomb" structure. 8. Partition wall thermally insulating (14, 27) for an electrical cabinet (1) for the integration of equipment and electrical wiring, particularly in an aircraft, characterized in that it consists of a panel shaped to give it the final shape of said partition, having a sandwich structure 20 composed of two outer plates (20, 21) of thermoformable composite material between which is inserted and secured an inner plate (22) of thermally thermoformable composite material 9. A partition wall according to claim 8, consisting of an upper plate (14) of a shelf further comprising a lower tray (7) in the form of a bowl, the said trays being adapted to delimit a box intended for be connected a ventilation network, and having longitudinal edges (9, 18) of support and assembly of the upper plate (14) on the lower plate (7 ), characterized in that the inner plate (22) of the upper plate (14) has a thickness conferring its insulating properties on the surface (15) of said upper plate delimiting the box, and a minimum thickness obtained by crushing at the longitudinal edges (18) of this upper plate (14). 10. Separation partition according to claim 8 consisting of a partition (27) for separating a box (2) into two ducts (25, 26) for respective flow of a flow of hot air and a flow of cold air, said partition having longitudinal edges (29) for fixing the latter inside the box and being characterized in that the inner plate (22) has a thickness conferring its insulating properties at the level of the surface (28) of said partition wall of the two IO ducts (25, 26), and a minimum thickness obtained by crushing at the longitudinal edges (29) of the latter. 11. partition wall (14, 27) according to one of claims 9 or 10 having radiated surface areas (19, 30) connecting the common areas (15, 28) and the longitudinal flanges (18, 29). of said partition, characterized in that each radiated zone (19, 30) has a decreasing variable thickness of the current zone (15, 28) of the partition towards its longitudinal flanges (18, 29), obtained by progressive crushing of the inner plate (22).