FR2626212A1 - Method and device for moulding and curing a composite material for forming a reinforced skin panel - Google Patents

Abstract

The invention relates to a method and device for moulding a composite material. According to the invention, the moulding device comprises a skin mould 11 provided with a smooth curing surface 11' and a reinforcement mould 12 provided with a curing surface 12' in relief and with at least one ridge (edge) 15 and two cavities 16 running on either side of the intersecting edge, which serve both to mould and to cure the composite material 21, 22 in order to produce, as a single component, a simple skin panel and reinforcements, these two moulds forming two parts designed so as to be juxtaposed and to be closed up intimately, an inflatable moulding membrane 17 being housed in each of the cavities between the curing surfaces and serving, once inflated during the curing cycle, to compress the composite material against the curing surface 11' of the skin mould 11 and against the upper and side walls of the ridge (edge) 15 of the reinforcement mould 12. Application in particular to the manufacture of aircraft components.

Description

The present process uses molds
baking of composite material for the formation of a
covering panel reinforced with fibers impregnated with
resin. It allows to mold and cook in one
operation, and in a single block, a cladding panel
simple and reinforcements of various dimensions. More
offer great freedom in the installation of reinforcements, the
process allows integrat on of sleepers. Furthermore, it
eliminates the need for adhesives and mechanical fasteners. The
particularity of this process come from its two molds
the coating mold is used to form the coating, and the
reinforcement mold is used to form the reinforcements and to define
the cavities that separate them.

The present invention relates to a
new process based on the use of special molds
liers for molding and baking in one operation, and
in a single block, a cladding panel and ren
strong in composite.

The use of composite materials tends
to expand in the manufacturing of aircraft parts. The
composite materials usually consist of
interlaced reinforcing fibers and unidirectional fibers, such as fiberglass, graphite and
boron, and impregnated with ecoxid razors. They offer the double advantage of considerably reducing the use of mechanical fasteners, such as rivets, to fix as
covering panels to the structure, and form a
light but resistant set.The American patent
N 4 395 450 issued to Soeing on July 25
1983 is a good illustration of the use of this type of covering panel. In this particular case, the patent relates rather: the construction of structural elements
whose reinforced webs are interposed in a double cladding panel.

 The invention relates to a process using molds for manufacturing a simple covering panel having reinforcements produced by melting composite material. The reinforcements used to stiffen and consolidate the covering panel so that it can withstand the stresses imposed. They are characterized by their fallen edges and curved at their ends. Due to their configuration, it is difficult to mold the covering panel and the reinforcements in one piece, because the design of ordinary molds makes it impossible to extract the molded part. For this reason, the covering panel is manufactured separately. and the reinforcements, and are then joined together with an adhesive, generally by thermal process under pressure, although fasteners can also be used to fix the reinforcements to the covering panel.

 Another manufacturing method is to autoclave the covering panel and the reinforcements by forming them in molds designed expressly for composite materials. However, in addition to being bulky and difficult to handle, these molds are expensive and require special autoclaves.

 The present invention provides a novel process which uses molds to bake a fiber reinforced fiberboard covering panel.

 One of the characteristics of the present invention is the use of a new process according to which it is possible to cook without an autoclave, and with a better distribution of heat, a covering panel provided with reinforcements which is made up of reinforced reinforcing fibers and impregnated with resin.

 Another characteristic of the present invention uses a method and two molds for baking in a single unit a covering panel and these reinforcements, so as to eliminate the use of adhesives and mechanical fasteners for their connection.

 Another characteristic of this present invention is the use of two molds for baking a reinforced covering panel where the reinforcements are released on either side to facilitate access during inspection and repair work. tion.

 Another characteristic of the present invention is manifested by the use of a new process, including the two molds, according to which smooth internal and external surfaces are obtained by baking a composite material against the cooking walls of the molds.

Another feature of the present invention is the use of a process and two molds for baking a single reinforced composite facing panel. According to this method, inflatable molding membranes are inserted into the housings of one of the two molds to form the edges of the reinforcements. once the cooking is finished, the membranes are extracted and molded through the opening at the ends of the
According to these characteristics, the present invention provides a process using a reinforcing mold provided with at least one edge and two cavities which run along the edge on either side to form a reinforcement. According to the method, the composite laminate is placed on the reinforcement mold, then another laminate is placed on the coating mold. Then, the two wheels are juxtaposed so as to bring the material on the edge into contact with that on the coating mold. Next, the molding membrane is inflated in order to apply pressure to the material which runs along the walls of the reinforcing mold in order to hold it in place. The next step is cooking or material, at an appropriate temperature and pressure. When the cooking is finished, the molding membrane is removed by passing it through the opening left at the ends of these reinforcements.

 According to the general concepts of the present invention, these heating rods have been integrated into the molds to provide a temperature that meets the requirements for baking the composite material.

 According to another characteristic of the invention, the molds are used for baking the composite material in a single operation to form in a single block the coating and the reinforcements. The coating mold includes a smooth portion for baking the composite material to form the coating. The reinforcement mold comprises a part provided with at least one edge and at least two cavities which run along the edge. The two molds are juxtaposed in order to cook the composite material. The cavities each include an inflatable molding membrane which, during the baking cycle, compresses the composite material between the two molds.

 To better understand the concept of the invention, here is a brief explanation of the figures appended hereto.

 Figure 1 shows a cross section of a reinforcing mold and a coating mold intended for baking the composite material in order to form a reinforced coating panel.

 Figure 2 is an enlargement of Figure 1 showing the composite material deposited on the two molds.

 FIG. 3 represents a plan view of a section of airplane wing constructed with the reinforced covering panel produced using the present invention.

 FIG. 4 represents a sectional view 4-4 of FIG. 3.

 FIG. 5 represents a sectional view f, with the reinforced covering panel showing the passage of a crosspiece over a reinforcement in an appropriate mold.

 FIG. 6A shows a fragmented sectional view of a cylindrical mold designed for molding a panel, this reinforced composite coating intended for the construction of a fuselage.

 Figure 6C is an enlargement of part of Figure 6A.

 In the figures presented, in particular in FIGS. 1 and 2, the reference 10 shows the two molds used in the process described herein: the coating mold identified at 11 and the reinforcement mold identified at 12.

They allow cooking in a single block of the covering panel and composite reinforcements, as illustrated in item 9 of FIG. 4. Provided with cooking walls, items 11 ′ and 12 ′, they can be fixed by fasteners ordinary (not shown), like hinges, so as to juxtapose the cooking walls.

 As clearly illustrated in FIG. 1, the coating mold at item 11 has a cavity, item 13, intended to receive the material which will be baked on the baking wall at item 11 '. It is in this flat and shallow cavity that the laminate of fibers impregnated with resin 22 is placed.

 The reinforcement mold has machined or otherwise formed edges, marks 14 and 15, which are used to make the reinforcements. These edges have a flat surface, item 23, and side walls, item 23 ', which widen downwards so as to facilitate the removal of the material after baking. Between the edges identified in 14 and 15 is a cavity, reference 16, in which there is an inflatable molding membrane, reference 17.

Once inflated, the membrane compresses the zomposite material 21 against each of the walls of the cavity identified at 16, and against the wall of the coating mold when the two molds are juxtaposed.

 In order to ensure the distribution of heat to specific places in the cavities and these walls of the molds, the tubes have been provided with tubes or with heating elements, item 18. These may be constituted either by devices with integrated electrical resistance, either by conduits in which a heating flise circulates.

They are arranged at the places where the resin-impregnated fiber material must be cooked. This material could also be cooked by fully heating the cooking walls.

 In FIG. 2, there is a flat housing marked at 19 used to mold the material to form the ends of the reinforcements, mark 20.

 From a practical point of view, there are edges of composite laminates on the edges identified in 14 and in the housing identified in 19, and a panel of the same material, in the cavity identified in 13, which is retained by the erasing action. resin, by gravity, by suction, or by other means. The inflatable molding membrane identified at 17 is then placed in the cavity identified at 16. Thus, it is completely surrounded during the juxtaposition of the cooking walls of the molds.

Then, using a pump (not shown), the membrane is inflated to the proper pressure so that the membrane compresses the walls of the composite material. The heat is then distributed and external pressure is applied to the molds to ensure uniform pressure on all sides.

 During cooking, the parts which are in contact with the composite material, such as the wall marked at 23 of the edge marked at 15, and the adjacent wall of the coating, unite to form a solid block under the effect of the heat and pressure applied. Heat as well as internal and external pressure are applied for a specific period of time, according to the requirements of the cooking cycle. When the cooking is finished, the molds are opened after having allowed them to cool and the membranes, item 17, are removed through the opening located at the end of the reinforcements item 20.

 FIG. 4 illustrates a product molded according to the method described herein and shown in FIGS. 1 and 2. The reinforced covering panel illustrated in FIG. 4 enters into the construction of the wing marked at 30 in FIG. 3. FIG. 4 is a sectional view 4-4 of the wing presented in FIG. 3. It will be noted that, due to the type of construction of the wing, the outer surface has practically no fasteners.

 Figure 5 shows a modified version of the reinforced cladding panel. We note the presence of a passage, reference 32, at the level of the reinforcement, recce SI, to allow the addition of a cross-member, reference 33. This, in the form of an inverted T, also consists of a ma - composite material and is embedded on each side by pressure pads, item 34. In this configuration, there is a drop in these edges, item =, until the passage, item 32. Of course, there are other variants of this type of configuration.

 In Figures SA and 68, we find another configuration of the coating mold, reference 11 '' 'and of the reinforcement mold, reference 12' ''. As can be seen, the coating mold is cylindrical and can be divided into sections, while the reinforcing mold is formed of a set of sections whose edges are spaced laterally. The inflatable molding membranes are inserted in the housings marked at 42 between the edges marked at 40. These types of mold are used in the construction of aircraft fuselages.

 Although the molds identified in i and 12 herein are provided with integrated heating devices, they can still be placed in an autoclave for the cooking cycle and obtain the degree of heat and pressure that this operation requires. It is much more profitable to incorporate all of the following heating devices, because or one can thus erfeotuer - directly and in the same place the placement of the composite material, the molding and lqa baking. The process and the molds described herein allows. The ermation of the reinforcements of dimensions, thicknesses, this widths and this my varlets.

In addition, they allow the reinforcements to be placed parallel, which offers great freedom of arrangement. They also eliminate the need to trim the material forming the covering or the reinforcements, and make it possible to mold flat or curved surfaces. In addition, crossbars can be integrated during baking and end the use of fasteners and secondary bonding agents to obtain in a single operation and in one piece a covering panel and reinforcements. It is also possible to manufacture complete blocks used in the construction of aircraft parts or parts which are not necessarily intended for the aeronautical industry, for example floor or ceiling structures, walls and the like.

 The present invention provides for any obvious modification of the embodiments set out herein, provided that these modifications do not exceed the scope of the claims.

Claims (14)

 1.- Process for molding and baking in one  single block a single covering panel and this reinforcements  made of composite material, characterized in that it comprises  the following operations  a) make a reinforcing mold (12), the  relief surface includes at least one edge (15> and two  cavities (16) along the edge on either side  b) placing a composite material (21)  in the reinforcement mold, more precisely on the edges  (15) and in the cavities (16) which give the definite form  tive to the composite material constituting the reinforcements  c) place an inflatable molding membrane  (17) in each of the reinforcing mold cu cu, in i'in-  serer through the opening located at the end of the reinforcements.  the degree of heat and the level of pressure required.  in the reinforcement mold and the coating mold supplied-  g) baking the material (21, 22) which is  12 ') of the reinforcement mold and of the coating mold; and  the material (21, 22) against the walls this cooking (11 '  inflatable molding brane (so that it compresses  @) inflate to a suitable pressure the same  the upper wall of the edge is in contact with at least part of the material (22) forming the covering  coating (11) on the raised surface (12 ') or reinforcing mold (12) so that part of the material 21) on  e) juxtapose the smooth surface (11 '> of the mold  baking pan of the coating mold (11);  d) dispose of a composite material (22> on the  2.- Method according to claim 1, wherein several edges (15) and cavities (16) form the  relief surface or reinforcing mold (12), and the operation  b) includes insertion c an air-inflatable membrane  (17) in each of these cavities.  3.- Processed according to Revencication 2 in which the edges (15) are elongated and the operation comprises placing, along the length of the selvedge (21) of composite material on the edges and in the cavities, so that the walls of the cavities can form the edges of the reinforcements.  4.- Method according to claim 3, wherein the selvedges of composite material (21) are arranged in cavities (16) with a flat bottom to form the reinforcing bogs.  5.- Method according to claim 1, 2 or 3, wherein the selvedges of composite material (21) are arranged on edges (15> flared base.  6.- Method according to claim 1, wherein the configuration of the reinforcements is carried out by bringing into contact the part of the material (2 <) which is on the edge with the part of the material (22) which is on the smooth part of the coating mold.  7.- Method according to claim 1, wherein a drop exists on the edges (35) for the passage of sleepers (33) so as to allow the establishment thereof and the consolidation in one piece of reinforcements (31) of the crosspieces (33) and of the covering by bonding of the composite material during baking.  8.- Method according to claim 1, wherein the operation g> comprises the establishment of this heating sitar (18) integrated in the molds to regulate the cooking temperature.  9.- Molding device for a composite material, characterized in that it comprises a coating mold (11) provided with a smooth cooking surface (11 ') and a reinforcing mold (12) provided with a cooking surface in relief (12 ') and at least one edge (15) and two cavities (16) along the edge on either side, yes are used both for molding and for baking the composite material (21, 22 ) to produce in a single block a simple covering panel and reinforcements, these two molds forming two parts designed to be juxtaposed and will be tightly armed, an inflatable molding membrane (17) being housed in each of the cavities the cooking surfaces and serving, a bowl swollen during the cycle this cooking, to compri @ er the composite material against the cooking surface (11 ') of the coating mold (11) and against the upper (23) and side walls (23 '> of the edge (15) of the reinforcement mold (12)  10.- Device according to claim 9, wherein the reinforcing mold (12) comprises several edges (15) and cavities (16) forming the cooking surface in relief (12 ').  11.- Device according to the revencication ID, in which the reinforcement mold (12> comprises edges (15) in the lengthwise direction, thus ove cavities (16) with flat bottoms arranged on either side of the edges of so as to form the edges of the reinforcements forming an integral part of the reinforced covering panel.  12.- Device according to claim 11, wherein the reinforcing mold (12> comprises edges (15) whose shape is characterized, in cross section, by an inverted U whose top wall is flat and whose side walls are flare from the top.  13.- Device according to claims 9 and 10, comprising several heating devices (18) intended to heat the two molds  14.- Device according to claim 12, wherein the edges (35) of the reinforcing mold having a difference in level on a portion determined to allow the passage of sleepers (33), and the placing in place of the composite material in each of these breaks so that these crosspieces are integrated into the renroroe covering panel during cooking.