Process for manufacturing a part by injecting resin into a fiber preform

Abstract

A method of manufacturing a part by injecting resin into a fiber preform, comprising the following steps: d) forming the preform (200) in a mold (102) of a tool (100), the forming comprising the following substeps: d1) compacting the preform (200) d2) drying the preform (200); and e) injecting resin into the preform (200) and molding. Furthermore, the substep d2) of drying the preform (200) is carried out under a tarpaulin (128), the tarpaulin (128) being held in position by fixing the tarpaulin (128) to the tool (100) by at least one magnet (130), the tool (100) and / or the tarpaulin (128) comprising a ferromagnetic material for fixing said at least one magnet (130). Figure for abstract: Fig 1

Description

Title of the invention: Method for manufacturing a part by injecting resin into a fiber preform Technical field

[0001] The present invention relates to the manufacture of parts made of composite material and, more particularly, to the protection of such parts against contamination by pollution coming from the external environment.

[0002] More specifically, the invention relates to a method of manufacturing a part by injecting resin into a fiber preform. Previous techniques

[0003] An existing method for manufacturing a composite material is the resin transfer molding process, more commonly known as the "RTM process", from the English abbreviation Resin Transfer Molding. The RTM process allows the manufacture of a material comprising reinforcing fibers and a resin forming the matrix.

[0004] Document FR 3 068 640 describes a method for manufacturing a part by injecting resin into a preform made of woven fibers. The method presented firstly comprises the production of a preform by weaving fibers followed by cutting it to the desired dimensions.

[0005] In order to give it a particular shape, the preform is then subjected to a shaping step by humidification then positioning in the imprint of a mold of a tool. The preform then undergoes a forming step by pressurizing between the mold and a counter-mold.

[0006] Once compacted, the preform is dried, preferably by heating. Drying the preform removes residual water, preventing the formation of porosities and allowing the preform to stiffen.

[0007] After forming, a resin is injected to impregnate the preform and then molded to obtain the composite material part.

[0008] During the RTM process, there is a risk of pollution of the part by external contaminants.

[0009] Depending on the nature of the contamination, the final properties of the part may be modified, affecting its performance and potentially having serious consequences during its use.

[0010] In the aeronautics sector, the control of external pollution formed by foreign bodies or debris, known by the Anglo-Saxon terms "Foreign Object Debris" or "Foreign Object Damage" (FOD), is a major issue.

[0011] Conventionally, the preform drying step is therefore carried out under a tarpaulin. protection to avoid any external contamination.

[0012] The tarpaulin is generally made of fabric comprising polytetrafluoroethylene PTFE fibers.

[0013] One solution for holding the tarpaulin above the preform consists of using tape.

[0014] However, this technique itself carries a risk of contamination. The tape contributes significantly to fraying the edges of the tarpaulin fabric, releasing PFTE filaments that end up in the composite parts and result in costly scrap.

[0015] In addition, this technique is manual and an operator must ensure that the tarpaulin is correctly fixed, which lengthens the process.

[0016] Another solution is to place a weighted tarpaulin at its edges. The weight placed on the periphery tightens the tarpaulin.

[0017] The tension applied to the tarpaulin increases its wear rate due to the presence of angles or sharp edges on the mold of the tool used.

[0018] Furthermore, this does not guarantee repeatable positioning. Statement of the invention

[0019] The present invention therefore aims to overcome the aforementioned drawbacks and to provide a method for manufacturing a part made of composite material making it possible to limit contamination of the preform, in particular during drying, by pollution from the external environment.

[0020] The present invention relates to a method for manufacturing a part by injecting resin into a fiber preform, comprising the following steps:

[0021] d) forming the preform in a mold of a tool, the forming comprising the following sub-steps:

[0022] dl) compacting the preform;

[0023] d2) drying the preform; and

[0024] e) injection of resin into the preform and molding.

[0025] Furthermore, sub-step d2) of drying the preform is carried out under a tarpaulin, the tarpaulin being held in position by fixing the tarpaulin to the tooling by at least one magnet, the tooling and / or the tarpaulin comprising a ferromagnetic material for fixing said at least one magnet.

[0026] According to one characteristic, the tarpaulin can be held in position by the at least one magnet by fixing the tarpaulin to the tool, only the tool comprising a ferromagnetic material for fixing the at least one magnet.

[0027] Alternatively, the tarpaulin may be held in position by the at least one magnet per fixing the tarpaulin to the tool, only the tarpaulin comprising a ferromagnetic material for fixing the at least one magnet.

[0028] Alternatively, the tarpaulin may be held in position by the at least one magnet by attaching the tarpaulin to the tooling, the tooling and the tarpaulin comprising a ferromagnetic material for attaching the at least one magnet.

[0029] According to one embodiment, the at least one magnet can be integrated into the tarpaulin, the tooling comprising a ferromagnetic material for fixing the at least one magnet.

[0030] According to an alternative, the at least one magnet can be provided on an element independent of the cover and the tooling, the tooling comprising a ferromagnetic material for fixing the at least one magnet, and the cover being held between the magnet of the independent element and the tooling.

[0031] Advantageously, the independent element formed by the magnet may comprise a gripping means such as a handle.

[0032] According to another alternative, the at least one magnet can be attached to the tarpaulin by non-magnetic fixing means, for example by screwing or gluing, the tooling comprising a ferromagnetic material for fixing the at least one magnet.

[0033] According to another alternative, the tarpaulin may comprise a ferromagnetic material for fixing said at least one magnet, said at least one magnet being integrated into the tooling.

[0034] According to another alternative, the tarpaulin may comprise a ferromagnetic material for fixing the at least one magnet, the at least one magnet being attached to the tooling by non-magnetic fixing means, such as by screwing or gluing.

[0035] Advantageously, the tarpaulin can be held in position by fixing the perimeter of the tarpaulin on the mold of the tool by at least one magnet without contact with the preform.

[0036] Preferably, step e) is carried out in the mold of the tooling of step d).

[0037] Preferably, the preform drying sub-step is carried out under a polytetrafluoroethylene (PTFE) or polyethersulfone (PES) tarpaulin, such as polysulfone, more preferably under a woven polytetrafluoroethylene (PTFE) tarpaulin or a woven polyethersulfone (PES) tarpaulin, such as polysulfone.

[0038] Preferably, the manufacturing method comprises, prior to steps d) and e), the following steps:

[0039] a) producing the preform by weaving the fibers;

[0040] b) sizing the preform;

[0041] c) shaping the preform by:

[0042] - humidification of the preform; and

[0043] - positioning of the preform in the imprint of a mold of a tool identical or different from the mold of the tooling of step d).

[0044] Preferably, step e) comprises the following steps:

[0045] - partial opening of the tool, by moving the mold away from a counter-mold of the tools or vice versa;

[0046] - injection of resin into the tooling;

[0047] - closing the tool, by bringing the mold closer to the counter-mold or vice versa; And

[0048] - pressurizing and heating the impregnated preform between the mold and the counter-mold. Brief description of the drawings

[0049] The present invention will be better understood and other aims, advantages and characteristics will emerge from the detailed description which follows, comprising embodiments given purely for illustrative purposes and made with reference to the appended drawings, presented as non-limiting examples, which may serve to complete the understanding of the invention and the description of its implementation and, where appropriate, contribute to its definition, in which:

[0050] [Fig-1] is a schematic view of a tool for manufacturing a composite material according to one embodiment of the invention.

[0051] [Fig.2] is a schematic perspective view of a mold of the tooling illustrated in [Fig.l].

[0052] [Fig.3] is a block diagram illustrating the different stages of a manufacturing process of a part by injecting resin into a fiber preform.

[0053] [Fig.4] represents the mold of the tool illustrated in [Fig.2] on which is arranged a tarpaulin-covered fibrous preform according to one embodiment of the invention.

[0054] [Fig.5] in which a tarpaulin-covered fiber preform is arranged according to one embodiment of the invention.

[0055] It should be noted that, in the figures, the structural and / or functional elements common to the different embodiments may have the same references. Thus, unless otherwise stated, such elements have identical structural, dimensional and material properties.

[0056] In the description of the invention which will be made, the expression "at least one" used must be considered as equivalent to the expression "one or more". Detailed description of at least one embodiment

[0057] [Fig.l] illustrates a tool 100 for manufacturing a part made of composite material by injecting resin into a fiber preform according to one embodiment of the invention.

[0058] By fibrous preform is meant a reinforcement structure of a composite material before injection of a matrix, here the resin. The reinforcement structure is obtained from woven fibers.

[0059] The tool 100 comprises a mold 102 secured to a lower plate 104, and a counter-mold 106 secured to an upper plate 108.

[0060] In the example shown, the lower plate 104 forms a support base for the tooling, which can for example rest on the floor of a manufacturing workshop.

[0061] The mold 102 is located on an upper face of the plate 104 and comprises an imprint 110, better visible in [Fig.2].

[0062] In the example shown, the imprint 110 is that of a face of a fan blade, such as its extrados for example.

[0063] The imprint 110 is here oriented upwards and faces an imprint 112 of the counter-mold 106 located above the mold 102 and opposite the latter.

[0064] The imprint 112 is here that of another face of a fan blade, such as its intrados for example.

[0065] The mold 102 and the counter-mold 106 may be made of composite material incorporating carbon fibers, aluminum or even stainless steel in order to avoid oxidation of the preform 200.

[0066] The platen 108 and the counter-mold 106 are movable from an upper position, shown in [Fig.l], in which the tooling is open and the mold 102 and the counter-mold 106 are spaced apart from each other, and a nested or close position in which the tooling is closed and the mold 102 and the counter-mold 106 are engaged with each other.

[0067] We will now describe the different stages of an embodiment of a method for manufacturing a part made of composite material by injecting resin into a fiber preform, starting from [Fig.3].

[0068] In the example illustrated, the manufacturing method comprises a first step a) of producing a preform 200 by weaving fibers.

[0069] The weaving is carried out in three dimensions by means of a loom, for example of the Jacquard type. At the exit of the loom, the preform 200 is raw and has a generally flat shape and is bulged.

[0070] A following step b) of the method consists of sizing the preform 200, for example by cutting its floats with a water jet on a flat preform.

[0071] When the preform 200 is produced, it can be shaped in order to give it a shape, in this example a fan blade.

[0072] In the illustrated example, the manufacturing method comprises a step c) of shaping the preform 200 by positioning the preform 200 in the imprint of a mold.

[0073] In the example illustrated, step c) is implemented here using the tool 100 shown in Figures 1 and 2.

[0074] The preform 200 is therefore placed in the imprint 110 of the mold 102, preferably using the laser projection means 126.

[0075] In step c) the preform 200 is preferably moistened prior to its placement in the imprint 110 to make it more malleable.

[0076] According to an alternative, the preform 200 can be moistened after positioning in the mold 102 of the tooling 100.

[0077] A step d) consists of subjecting the preform 200 to forming.

[0078] In a first sub-step dl) of the forming step d), the preform 200 is compacted to the desired final geometry.

[0079] For this, the tool 100 is closed and put under pressure, for example between 5 and 10 bars.

[0080] Advantageously, the pressurization is carried out by locally pressing the zones the thickest of the preform 200. The remainder of the preform 200 is left in the free state.

[0081] In a second sub-step d2) following compacting, the preform 200 is dried under a tarpaulin.

[0082] A tarpaulin 128 is positioned above the preform 200 in order to avoid any risk of contamination of the preform 200.

[0083] The preform 200 is dried under a tarpaulin on the mold 102 of the tool 100.

[0084] Preferably, the drying of the preform 200 under a tarpaulin is carried out in an oven. ventilated. The assembly formed by the mold 102, the preform 200 and the tarpaulin 128 is placed in the ventilated oven.

[0085] Preferably, the ventilated oven is heated to a temperature of 100°C.

[0086] The moisture from the preform 200 is evacuated by the air blowing into the ventilated oven.

[0087] Drying the preform 200 makes it possible to eliminate the remaining water so as to avoid the porosities and stiffen the preform 200.

[0088] The tarpaulin 128 is held in position above the preform 200 by fixing the tarpaulin 128 to the tooling 100 by at least one magnet 130.

[0089] In the example illustrated in [Fig.4], the tarpaulin 128 is held by a plurality of magnets.

[0090] The protection of the preform 200 by the tarpaulin makes it possible to avoid pollution of the preform 200 and makes it possible to avoid oxidation of the preform 20 with water.

[0091] Fixing the tarpaulin using one or more magnets facilitates the positioning of the tarpaulin on the tooling, which is easily repeatable, and helps to reduce the risks of contamination by FOD and therefore the number of parts rejected in production. Wear of the tarpaulin is also limited, which makes it possible to limit the number of tarpaulins used.

[0092] The tarpaulin 128 is preferably made of polytetrafluoroethylene (PTFE) or polyethersulfone (PES), for example polysulfone. More preferably, the tarpaulin 128 is a woven tarpaulin made of polytetrafluoroethylene (PTFE) or polyethersulfone (PES), for example polysulfone.

[0093] The tarpaulin 128 can be held in position by fixing the periphery 132 of the tarpaulin 128 on the tooling 100 by the magnets 130. The positioning of the magnets 130 is advantageously carried out in non-useful zones of the tooling 100, advantageously on the mold 102, so that the magnets 130 are not in contact with the preform 200 so as not to risk contaminating the preform 200, as illustrated, around the imprint 110, on vertical sides of the mold 102.

[0094] In the example illustrated in [Fig.4], the plurality of magnets 130 is integrated into the cover 128. Advantageously, a hem is formed on the periphery 132 of the cover 128 in order to hold the magnets 130 in the cover 128.

[0095] In addition, the tooling 100 comprises a ferromagnetic material for fixing the magnets 130.

[0096] By ferromagnetic material is meant a material to which a magnet adheres.

[0097] The ferromagnetic material is, for example, a metallic material, a material ceramic or a mixture of these.

[0098] According to an alternative, the magnets 130 can be integrated into the tooling 100, in particular into the mold 102, and the tarpaulin can incorporate a ferromagnetic material.

[0099] The integration of the magnets 130 in the tarpaulin or in the tooling means that they do not have to be handled separately, which makes the installation of the tarpaulin easier and avoids the generation of FOD pollution by the magnets themselves.

[0100] According to another alternative embodiment, the magnets 130 can be attached to the tarpaulin, advantageously on its inner face intended to face the preform 200, by non-magnetic fixing means. The tooling 100 then comprises a ferromagnetic material to allow the fixing of the magnets 130.

[0101] Conversely, the magnets 130 may be attached to the tooling 100 by non-magnetic attachment means, and the cover 128 may comprise a ferromagnetic material.

[0102] For example, the magnets 130 are attached to the tarpaulin 128 by screwing or gluing.

[0103] With reference to [Fig.5], and according to another alternative embodiment, the magnets 130 can be arranged on an independent element 134 separate from the cover 128 and the tooling 100. The tooling 100 then comprises a ferromagnetic material. The cover 128 is held between the magnet 130 of the independent element 134 and the tooling 100 by fixing the magnets 130 on the ferromagnetic material.

[0104] Each independent element 134 comprising at least one magnet 130 may comprise a gripping means such as a handle in order to facilitate the handling, installation and removal of the magnets.

[0105] The geometry of the tarpaulin and the position of the magnets can be modulated so as to limit the tension of the tarpaulin, limit friction with the tooling 100 and thus increase its lifespan.

[0106] After drying in step d), the preform 200 is then ready for injection.

[0107] Preferably, the tarpaulin 128 is held in position above the preform 200. until the completion of step e) of resin injection detailed below.

[0108] Step e) which consists of injecting resin into the cavity of the tool 100 for the impregnation of the preform 200.

[0109] For this, the tool 100 is partially open, the counter-mold 106 being moved away from the mold 102 by a predetermined distance. This allows the supply of a volume of resin strictly necessary to wet the preform 200 and fill the final geometry of the part. During this resin injection operation, the mold 102 and the counter-mold 106 are preferably heated, and the resin as well.

[0110] The tool 100 is then closed and a pressure, for example of 3 to 10 bars, is applied by the cylinder 118 to the preform 200.

[0111] The temperature may be maintained at 160°C during injection and raised to 180°C for polymerization of the resin. The pressure is preferably maintained constant over the entire extent of the part during polymerization.

[0112] After polymerization, the tooling 100 is opened, the part is removed and the tooling 100 can be cleaned for a new manufacturing operation.

[0113] In the illustrated example, steps c), d) and e) are all carried out in the mold 102 of the tooling 100.

[0114] According to an alternative, step c) and / or step e) can be carried out in a mold of a tool different from the mold 102 of the tool 100 used in step d).

[0115] Of course, the different characteristics, variants and / or embodiments of the present invention can be associated with each other in various combinations to the extent that they are not incompatible or exclusive of each other.

Claims

Claims

1. A method of manufacturing a part by injecting resin into a fiber preform, comprising the following steps: d) forming the preform (200) in a mold (102) of a tool (100) comprising the following substeps: dl) compacting the preform (200); d2) drying the preform (200); and e) injecting resin into the preform (200) and molding, characterized in that the substep d2) of drying the preform (200) is carried out under a tarpaulin, the tarpaulin (128) being held in position by fixing the tarpaulin (128) to the tool (100) by at least one magnet (130), the tool (100) and / or the tarpaulin (128) comprising a ferromagnetic material for fixing said at least one magnet (130).

2. The method of claim 1, wherein said at least one magnet (130) is integrated into the tarpaulin (128) and the tooling (100) comprises a ferromagnetic material for fixing said at least one magnet (130).

3. Method according to claim 1, wherein said at least one magnet (130) is provided on an independent element (134) of the cover (128) and the tooling (100), the tooling (100) comprising a ferromagnetic material for fixing said at least one magnet (130), the cover (128) being held between the magnet (130) of the independent element (134) and the tooling (100), preferably the independent element (134) comprising a gripping means such as a handle.

4. The method of claim 1, wherein said at least one magnet (130) is attached to the tarpaulin (128) by non-magnetic fastening means, such as by screwing or gluing, the tooling comprising a ferromagnetic material for fastening said at least one magnet (130).

5. The method of claim 1, wherein the cover comprises a ferromagnetic material for fixing said at least one magnet (130), said at least one magnet (130) being integrated into the tooling (100).

6. The method of claim 1, wherein the cover (128) comprises a ferromagnetic material for fixing said at least one magnet (130), said at least one magnet (130) being attached to the tooling (100) by non-magnetic fixing means, such as by screwing or collage.

7. Method according to any one of the preceding claims, in which the tarpaulin (128) is held in position by fixing the periphery (132) of the tarpaulin (128) on the tooling (100), preferably on the mold (102) by said at least one magnet (130) without contact with the preform (200).

8. Method according to any one of the preceding claims, in which step e) is carried out in the mold (102) of the tooling (100) of step d).

9. Method according to any one of the preceding claims, in which the sub-step of drying the preform (200) is carried out under a tarpaulin (128) made of polytetrafluoroethylene (PTFE) or polyethersulfone (PES), such as polysulfone, more preferably under a woven tarpaulin made of polytetrafluoroethylene (PTFE) or under a woven tarpaulin made of polyethersulfone (PES), such as polysulfone.

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