Compacting wedges for fan case moulds

Abstract

A mold (300) for manufacturing a gas turbine fan casing made of composite material, comprising: a core mold (331), on which a fiber preform (310) of the fan casing is intended to be wound, the core mold comprising an annular wall and two side mold plates (330), the contour of the outer surface of the annular wall corresponding to the contour of the inner surface of the casing to be manufactured, and the contour of the side mold plates corresponding to the contour of the outer flange of the casing to be manufactured; a plurality of angled counter-mold sectors (321), which are assembled on the core mold in a sealed manner and are intended to close the mold and compact the fiber preform wound on the core mold; and at least one compacting wedge (320), which is placed between the fiber preform wound on the core mold and the associated angled counter-mold sectors, characterized in that the compacting wedge is carried on one of the side mold plates of the core mold and is intended to cover the top (312) of one of the outer flanges (311) of the casing to be manufactured.

Description

Technical Field

[0001] The present invention relates to the general field of manufacturing gas turbine casings and, more particularly, to a retaining casing for a gas turbine fan for an aircraft engine. Background Art

[0002] In gas turbine aircraft engines, the fan case has several functions. It defines the flow path of the air drawn into the engine, supports the abradable material facing the tops of the fan blades, supports optional sound wave absorbing structures for acoustic treatment at the engine inlet, and incorporates or supports a retention shroud. The latter constitutes a collector for trapped debris, such as ingested objects ejected by centrifugal action or fragments of damaged blades, to prevent them from passing through the case and reaching other parts of the aircraft.

[0003] Schemes for manufacturing fan casings made of composite materials have been proposed. For example, reference can be made to patent EP 1961 923, which describes the manufacture of a composite casing with evolving thickness, consisting in forming a fiber preform by superimposing layers of fiber textures and densifying the fiber reinforcements by means of a matrix. More precisely, the document provides for the three-dimensional weaving of the fiber texture using a winding mandrel, the fiber texture stack then being wound on an impregnation mandrel having an outer surface whose contour corresponds to the contour of the central part of the casing to be manufactured and two side molds (side flasks), the side molds corresponding to the casing fixing flanges. The fiber preform is held on the impregnation mandrel and, before polymerization, resin impregnation is performed.

[0004] For the impregnation of a fiber preform by a TRM (resin transfer molding) type injection method, it is known to position elements of a counter-mold on an impregnation mandrel, thereby forming an injection mold. Reference may be made, for example, to application WO 2013 / 060978, which discloses a resin injection mold mounted with angular sectors to close the impregnation mandrel. When closing the injection mold, compaction wedges may be used to maintain the compaction force on the preform. These wedges are particularly used to compact some flanges at the ends of the preform, which are vertical (or radial) and therefore have a compaction direction different from the axial compaction direction of the rest of the preform. These wedges also allow this to be avoided by placing the sectors directly in a radial closing direction, these same sectors not bending the flanges or causing them to buckle or shear.

[0005] At present, the compacting wedges are in contact, in the closed position, only with the counter-mold and with the sectors of the fiber preform, in particular at the future fixing flanges of the shell. Since the axial positioning of the angular sectors has a certain variability and the connection between the wedges and the sectors adds an additional variability, the final variability of the positioning of the wedges is very large. This directly affects the final thickness of the part to be manufactured in this area. Moreover, this is an area where a good control of the thickness is sought, since the flanges will be machined later. This control is also important for controlling the amount of carbon present in the final machined part, that is to say the amount of resin injected.

[0006] It is therefore desirable to have an injection mold, and in particular a new compaction wedge, which allows reducing the interaction between the angular sectors and the wedge to reduce the variability of the thickness of the preform at the future shell flange, adapting the amount of resin injected into the mold. Summary of the invention

[0007] The present invention relates to a mold, which is intended for manufacturing a gas turbine fan casing made of a composite material, comprising:

[0008] - a mandrel on which the fiber preform of the fan casing is intended to be wound, the mandrel comprising an annular wall, the contour of the outer surface of which corresponds to the contour of the inner surface of the casing to be manufactured, and two side templates, the contour of which corresponds to the contour of the outer flange of the casing to be manufactured;

[0009] - a plurality of angled counter-mold sectors intended to be assembled in a sealed manner on the mandrel and intended to close the mold and compact the fiber preform wound on the mandrel; and

[0010] - at least one compacting wedge, these wedges are intended to be placed between the fiber preform wound on the mandrel and the associated angled counter-mold sector,

[0011] It is characterized in that the compacting wedge is carried on one of the side plates of the core mold and is intended to cover the top of one of the outer flanges of the shell to be manufactured.

[0012] The mould according to the invention thus allows an improved positioning of the compacting wedge. By abutting against one of the side plates, the position of the wedge is more easily reproducible. In fact, by having the wedge always placed in the same position and bearing on one of the side plates, the relative positioning of the mould parts will be more precise and it will be easier to maintain a constant compaction force during the manufacture of several shells. This then allows an improved uniformity of the thickness of the parts manufactured by this mould.

[0013] By improving the thickness uniformity of parts made with the mold, it can also simplify or even eliminate the step of remachining the part after the resin is injected into the mold.

[0014] Furthermore, in order to place the compaction wedge on one of the side mold plates, it is possible to use a larger compaction wedge in the radial direction of the mold than in the prior art, or to reduce the extension of the outer flange in the radial direction and use the current compaction wedge. The advantage of reducing the size of the outer flange is that, in addition to improving the uniformity of the part thickness, it is also possible to reduce the amount of resin injected into the mold.

[0015] The mould according to the invention is therefore notable in that it allows reducing the variability in the thickness of the final part and reducing the amount of resin injected into the mould.

[0016] Another object of the invention is a method for closing an injection mold intended for manufacturing a gas turbine fan casing made of composite material, the mold comprising a core mold on which a fiber preform of the fan casing is intended to be wound, the core mold comprising an annular wall and two side mold plates, the contour of the outer surface of the annular wall corresponding to the contour of the inner surface of the casing to be manufactured, the contour of the two side mold plates corresponding to the contour of the outer flange of the casing to be manufactured, the mold also comprising a plurality of angled counter-mold sectors and at least one compacting wedge, the plurality of angled counter-mold sectors intended to close the mold and compact said fiber preform wound on the core mold, the method comprising:

[0017] - tightly assembled angled counter-mold sectors on the mold core; and

[0018] - Placing a compacting wedge on one of the side templates, the compacting wedge is positioned against the longitudinal face of the associated angled counter-mould sector and is intended to cover the top of the outer flange of the shell to be manufactured.

[0019] Another object of the present invention is a method for manufacturing a gas turbine fan casing made of a composite material, comprising:

[0020] - winding the fiber preform on a mandrel of a mold according to the invention;

[0021] - closing the mould according to the method of the invention;

[0022] - injecting the resin into the mould; and

[0023] - Demould the fan housing.

[0024] Another object of the invention is a gas turbine comprising a fan casing manufactured by the manufacturing method according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other characteristics and advantages of the invention will become apparent from the following description given with reference to the accompanying drawings, which show exemplary embodiments without any limiting character.

[0026] [ Figure 1 ] Figure 1 A gas turbine fan case is shown schematically and partially.

[0027] [ Figure 2A ] Figure 2A A cross section of a mold according to the prior art when closed is shown schematically and partially.

[0028] [ Figure 2B ] Figure 2B Shows Figure 2A A three-dimensional diagram of the mold.

[0029] [ Figure 3 ] Figure 3 The mold according to the invention is shown schematically and partially when closed. DETAILED DESCRIPTION

[0030] The present invention will be described below in conjunction with its application to the manufacture of a fan case in an aircraft gas turbine engine.

[0031] Figure 1 A perspective view of a fan casing 10 is shown, which can be manufactured using the mold and the method according to the invention. Such a casing is centered on a longitudinal axis XX and comprises an annular wall 11 delimited upstream by an upstream flange 12 and downstream by a downstream flange 13 (upstream and downstream being defined relative to the flow direction of the gas flow in the gas turbine). The inner surface 14 of the annular wall 11 is intended to define a flow path for sucking air into the gas turbine.

[0032] Figure 2A and Figure 2B A mold 200 according to the prior art is shown schematically and partially closed. Figure 2A is a cross-sectional view of the mold 200, Figure 2B It is a three-dimensional diagram of the mold 200.

[0033] Such a mold 200 can be used to impregnate a fiber preform 210 by the RTM molding method ("resin transfer molding") to manufacture, for example, Figure 1 The fan case 10 is shown. The fiber preform 210 may be produced by three-dimensional weaving of fibers such as carbon, glass, aramid or ceramic, and the impregnation matrix may be made of a polymer such as epoxide, bismaleimide or polyimide.

[0034] The mold 200 is rotatably mounted on a drive axis (not shown) centered on the axis XX and includes a core mold 231. The core mold 231 includes a barrel-shaped annular wall and two side mold plates (only one mold plate 230 is shown), and the fiber preform 210 is to be wound on the annular wall. The core mold 231 is held on its drive axis by spokes (not shown).

[0035] The side templates 230 form supports intended to receive the folded portion 211 of the preform 210 rolled onto a mandrel 231 and to form the upstream flange 12 and the downstream flange 13 of the fan casing 10 .

[0036] The mold 200 also includes a counter-mold and two compacting wedges 220, the counter-mold consisting of a plurality of angled counter-mold sectors 221 assembled in a sealed manner on a core mold 231. Figure 2A In the figure, only one angled counter-mold sector 221 with a compacting wedge 220 is shown.

[0037] According to the prior art, the compacting wedge 220 is placed between the fiber preform 210 wound on the mandrel 231 and the angled counter-mold sector 221 of the counter-mold. The angled counter-mold sector 221 bears against the flange 230. The compacting wedge 220 has the same height as the future flange 211 of the shell and therefore does not bear against the flange 230.

[0038] Figure 3 A cross-sectional view of a mold 300 according to the invention when closed is schematically and partially shown.

[0039] Similar to the mold 200 of the prior art, the mold 300 according to the invention can be used to impregnate a fiber preform 310 by a RTM (“resin transfer molding”) type method to manufacture, for example, Figure 1 The fan housing 10 is shown.

[0040] The mold 300 is rotatably mounted on a drive axis (not shown) centered on the axis XX and comprises a core mold 331. The core mold 331 comprises a barrel-shaped annular wall and two side templates (only one template 330 is shown) on which the fiber preform 310 is intended to be wound. The core mold 331 is held on its drive axis by means of spokes (not shown).

[0041] The side formwork 330 forms a support intended to receive the folded portion 310 of the preform 311 rolled onto a mandrel 331 and intended to form the upstream flange 12 and the downstream flange 13 of the fan casing 10 .

[0042] The mold 300 also comprises a counter-mold consisting of a plurality of angled counter-mold sectors 321 assembled in a sealed manner on a core mold 331 and at least one compacting wedge 320 .

[0043] Unlike the prior art, the compacting wedge 320 is placed between the fiber preform 310 wound on the core mold 331 and the angled counter-mold sector 321 of the counter-mold and bears against the side template 330. The angled counter-mold sector 321 also bears against the template 330.

[0044] Therefore, the compaction wedge 320 is larger than the future flange 311 of the housing, thereby covering the top 312. To this end, a compaction wedge with the same general dimensions as the current wedge can be used and the size of the outer flange can be reduced, or the size of the outer flange can be maintained and the size of the compaction wedge can be increased.

[0045] Thus, the relative positions of the compacting wedge 320 and the template 330 are more easily repeatable and thus allow limiting the thickness variations of the preform 310 during its compaction. Thus, the step of re-machining the part after the resin has been compacted and injected into the mold 300 is simplified or even eliminated.

[0046] Furthermore, in order to make the compacting wedge 320 bear on the side mold plate 330, a wedge larger than the prior art can be used, or a prior art wedge can be used and the size of the upstream flange 12 and the downstream flange 13 of the shell 10 to be manufactured can be reduced. By reducing the size of the flanges in this way, the amount of resin injected into the mold 300 can also be reduced.

[0047] If the preform 310 is intended to include two side templates, each angled counter-mold sector may have two compacting wedges intended to cover the tops of the two flanges.

[0048] Each angled counter-mold sector may also have at least two compacting wedges, which are intended to cover the top of the flange, in the case where the compacting wedges are left in place on the mold after compaction to close the mold and perform injection. For example, three compacting wedges may be used per angled counter-mold sector.

[0049] In the same case, each angled counter-mould sector may also have a compacting wedge intended to cover the top of one of the flanges.

[0050] In the same case, there may be more angled counter-mold sectors than compacting wedges. For example, the mold may include three compacting wedges and six angled counter-mold sectors.

[0051] There can also be only one compacting wedge. For example, this can be achieved when another mold is used for injection, or when the preform only comprises one side mold plate.

[0052] The manufacture of the fan housing 10 will now be described.

[0053] First, a fiber preform is wound on the mandrel 331 of the mold 300 according to the invention. Methods for winding fiber preforms, which are produced, for example, by three-dimensional weaving around a mandrel such as the mandrel 331 of the invention, have already been proposed and will not be described in more detail. For example, reference can be made to application WO 2012 / 140355, which proposes a machine for winding a fiber texture on an impregnation mandrel.

[0054] Once the preform has been wound on the core mold, the mold has to be closed in order to compact the preform. To do this, the angled counter-mold sectors have to be assembled on the core mold in a sealed manner and a wedge has to be placed on one of the side molds so as to cover the top of the future flange of the shell being manufactured. The compacting wedge is also positioned against the longitudinal face of the angled counter-mold sector. The wedge is therefore supported on one of the side molds and it is simply pushed onto the preform in order to obtain a lower positioning variability, i.e. a higher precision. The step of placing the wedge is therefore repeated for a plurality of wedges so as to be able to position the wedge against the longitudinal face of the angled counter-mold sector and to place each wedge on one of the side molds so that the top of the future flange of the shell being manufactured is covered by the wedge.

[0055] The wedges allow compaction in a direction substantially perpendicular to the preform, thus helping to avoid folding and buckling.

[0056] The polymerizable resin is then injected into the mold by pressure difference (by RTM molding), and the polymerizable resin is polymerized (for example, by heating or cooling, depending on the nature of the resin used). The fan housing thus manufactured can then be demoulded.

Claims

1. A mold, intended for use in manufacturing a gas turbine fan casing made of a composite material, comprising: - a mandrel on which the fiber preform of the fan casing is intended to be wound, the mandrel comprising an annular wall, the contour of the outer surface of which corresponds to the contour of the inner surface of the casing to be manufactured, and two side templates, the contour of which corresponds to the contour of the outer flange of the casing to be manufactured; - a plurality of angled counter-mold sectors intended to be assembled in a sealed manner on the mandrel and to close the mold and to compact the fiber preform wound on the mandrel; as well as - at least one compacting wedge intended to be placed between the fiber preform wound on the mandrel and the associated angled counter-mold sector, Therein, the compacting wedge is carried on one of the side plates of the core mold and is intended to cover the top of one of the outer flanges of the shell to be manufactured, and the compacting wedge is positioned against the longitudinal face of the angled counter-mold sector.

2. A method for closing an injection mold intended for manufacturing a gas turbine fan case made of composite material, the mold comprising a core mold on which a fiber preform of the fan case is intended to be wound, the core mold comprising an annular wall and two side mold plates, the contour of the outer surface of the annular wall corresponding to the contour of the inner surface of the case to be manufactured, the contour of the two side mold plates corresponding to the contour of the outer flange of the case to be manufactured, the mold also comprising a plurality of angled counter-mold sectors and at least one compacting wedge, the plurality of angled counter-mold sectors intended to close the mold and compact the fiber preform wound on the core mold, the method comprising: - Tightly assemble the counter-mold sectors on the mold core; as well as - Placing the compacting wedge on one of the side templates, the compacting wedge is positioned against the longitudinal face of the associated angled counter-mould sector and is intended to cover the top of the outer flange of the shell to be manufactured.

3. A method for manufacturing a gas turbine fan casing made of a composite material, comprising: - winding the fiber preform on the core mold of the mold according to claim 1; - closing the mould according to the method of claim 2; - injecting the resin into the mould; and - Demould the fan housing.

4. A gas turbine comprising a fan casing manufactured by the method according to claim 3.

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