Injection mold for fiber preform with adjustable counter-molds

Abstract

Injection mold for fiber preform with adjustable counter-molds A mold (300) intended to be used for the manufacture of a gas turbine revolution part (10) made of composite material comprises: - a mandrel (330) on which a fiber preform (310) is intended to be formed comprising an annular wall and two lateral flanges (332, 333), - a plurality of angular barrel counter-mold sectors (320) intended to compact a barrel preform portion (313) of the fiber preform (310) present on the mandrel, and - at least two radial edge counter-mold shims (322, 324) intended to compact radial edge preform portions (311, 312) of the fiber preform present on the mandrel, each angular barrel counter-mold sector (320) is divided into a first and a second part (321, 323) respectively in contact with a radial edge counter-mold wedge (322, 324).The first and second parts (321, 323) are connected to each other by an adjustment device (325) capable of adjusting a distance between said first and second parts in the axial direction (DA). Figure for the abstract: Fig. 3.

Description

Title of the invention: Injection mold for fiber preform with adjustable counter-molds Technical field

[0001] The present invention relates to the general field of the manufacture of rotating parts used in gas turbines or turbomachines, such as in particular gas turbine or turbomachine fan casings for aeronautical engines. Prior art

[0002] A gas turbine or turbomachine aircraft engine comprises rotating parts such as a fan casing. This fulfills several functions. It defines the air inlet stream into the engine, supports an abradable material opposite the tip of the fan blades, supports a possible sound wave absorption structure for acoustic treatment at the engine inlet and incorporates or supports a retention shield. The latter constitutes a trap retaining debris, such as ingested objects or fragments of damaged blades, projected by centrifugation, in order to prevent them from passing through the casing and reaching other parts of the aircraft.

[0003] The production of a fan casing made of composite material has already been proposed. For example, reference may be made to patent EP 1 961 923 which describes the manufacture of a casing made of composite material with varying thickness comprising the formation of a fiber preform by superimposed layers of a fiber texture and the densification of the fiber reinforcement by a matrix. More specifically, this document provides for the use of a take-up mandrel for the three-dimensional weaving of the fiber texture, the latter then being wound in superimposed layers on an impregnation mandrel having an outer surface whose profile corresponds to that of the central part of the casing to be manufactured and two lateral flanges corresponding to fixing flanges of the casing. The fiber preform is held on the impregnation mandrel and resin impregnation is carried out before polymerization.

[0004] To carry out the impregnation of the fiber preform by an RTM (“Resin Transfer Molding”) type injection process, it is known to position the elements of a counter-mold on the impregnation mandrel and thus form an injection mold. For example, reference may be made to application WO 2013 / 060978 which discloses the installation of angular sectors to close the resin injection mold on the impregnation mandrel. When closing the injection mold, compacting wedges may be used to maintain the compaction force on the parts of the preform intended to form the flanges of the casing which are vertical (or radial) and which therefore have a different compaction direction from the rest of the preform. These shims also prevent the sectors with a radial closing direction from bending the flanges or causing them to buckle or shear. Thus, the counter-mold is formed from the angular sectors and the compaction shims, the latter being held in position by the support of the angular sectors when the mold is closed.

[0005] The compacting shims are, in the closed position of the mold, in contact with the angular sectors of the counter-mold and the fiber preform, in particular at the level of the future fixing flanges of the casing. Given that the axial positioning of the angular sectors has a certain variability and that an additional variability is added by the junction between a shim and a sector, the final variability control of the positioning of the shim is important because it directly influences the final thickness of the part to be manufactured in this zone. This control is also important to control the quantity of matrix present in the final machined part, that is to say the quantity of injected resin.However, after several uses, the mold and / or the angular sectors of the counter-mold wear out so that when positioning the compacting wedges and the angular sectors against the fiber preform, the compacting force exerted between the fiber preform and the compacting wedges is reduced, which results in a greater quantity of resin in the preform after injection. This excess resin and the low volume rate of fibers can create a non-conformity at the flanges. It is therefore necessary to change the mold to avoid this non-conformity.

[0006] It is therefore desirable to have a solution allowing the useful life of an injection mold to be extended. Statement of the invention

[0007] For this purpose, the invention proposes a mold intended to be used for the manufacture of a gas turbine revolution part made of composite material comprising:

[0008] - a mandrel on which a fiber preform is intended to be formed comprising an annular wall extending in width in an axial direction and the profile of an external surface of which corresponds to that of an internal surface of the part to be manufactured and two lateral flanges extending from the annular wall in a radial direction and the profiles of which correspond to those of radial edges of the part to be manufactured,

[0009] - a plurality of angular barrel counter-mold sectors intended to be assembled tightly on the mandrel and to compact a portion of the barrel preform of the fiber preform present on the mandrel, and

[0010] - at least two radial edge counter-mold shims, the shims being intended to compacting preform parts of radial edges of the fiber preform present on the mandrel, the radial edge counter-mold wedges being held in position by support of at least one angular sector of the barrel counter-mold,

[0011] characterized in that each angular sector of the barrel counter-mold is divided into a first and a second part respectively in contact with a radial edge counter-mold wedge and in that the first and second parts are connected to each other by an adjustment device capable of adjusting a distance between said first and second parts in the axial direction.

[0012] By dividing each angular barrel counter-mold sector into two parts and connecting them together by an adjustment device, it is possible to adjust the distance between the first and second parts of each angular barrel counter-mold sector in order to compensate for wear on the parts of the angular barrel counter-mold sectors and / or the mandrel flanges. This greatly extends the service life of the mold.

[0013] According to a particular characteristic of the mold of the invention, at least one of the two radial edge counter-mold wedges comprises two distinct portions assembled together by screws so as to adjust their support on the radial edge preform parts of the fiber preform.

[0014] According to another particular characteristic of the mold of the invention, each angular sector of the barrel counter-mold further comprises a sole extending between the first and second parts at their internal face, the sole filling the space present between said first and a second part. The sole makes it possible to fill the space present between the first and a second part, which makes it possible to improve the sealing of the angular sector and to avoid the risk of pinching or expansion of the preform in the space present between these two parts. The sole preferably has a thickness of between 0.1 mm and 1 mm in order to avoid creating a step on the final part.

[0015] According to another particular characteristic of the mold of the invention, the adjustment device comprises a base secured to the sole, the base being present between the first and second parts of each angular sector of the barrel counter-mold and at least a first and a second screw, each screw being held in a thread present in the base, the end of the first screw being in contact with the first part and the end of the second screw being in contact with the second part.

[0016] According to another particular characteristic of the mold of the invention, each angular sector of the barrel counter-mold further comprises a first seal present between the sole and the first part and a second seal present between the sole and the second part. This makes it possible to reinforce the sealing of each angular sector of the barrel counter-mold. The first and second seals may be made of a material elastomer capable of withstanding temperatures between 150°C and 170°C.

[0017] The invention also relates to a method for closing a mold according to the invention, the method comprising:

[0018] - the placement of at least two radial edge counter-mold shims intended to compacting preform parts of radial edges of a fiber preform present on the mold mandrel,

[0019] - adjusting a distance between first and second parts of each angular sector of the barrel counter-mold so as to maintain each counter-mold wedge in contact with the radial edge preform parts of the fiber preform,

[0020] - the watertight assembly of the angular sectors of the barrel counter-mold on the mandrel.

[0021] The invention also relates to a method for manufacturing a part of revolution composite material gas turbine comprising:

[0022] - winding a fiber preform onto the mandrel of a mold according to the invention,

[0023] - closing the mold according to the closing method of the invention,

[0024] - injecting a resin into the mold,

[0025] - the transformation of the resin into a matrix, and

[0026] - the demolding of the revolution part.

[0027] Another object of the invention is a gas turbine comprising a fan casing manufactured by a manufacturing method of the invention. Brief description of the drawings

[0028] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof which are not limiting in nature.

[0029] [Fig-1] [Fig.l] represents, schematically and partially, a casing of gas turbine fan,

[0030] [Fig.2A] [Fig.2A] represents, schematically and partially, a section of a mold according to the prior art, when it is closed and comes out of production,

[0031] [Fig.2B] [Fig.2B] represents a perspective view of the mold of [Fig.2A],

[0032] [Fig.2C] [Fig.2C] represents, in a very schematic and partial manner, a section of the mold of [Fig.2A] after several uses,

[0033] [Fig.3] [Fig.3] represents, schematically and partially, a section of a mold according to an embodiment of the invention when it is closed and comes out of production,

[0034] [Fig.4] [Fig.4] represents, schematically and partially, a section of the mold of [Fig.3] after several uses,

[0035] [Fig.5] [Fig.5] schematically and partially represents a section of the mold of [Fig.4] after adjustment of the distance between parts of an angular sector barrel counter-mold in accordance with the invention. Description of the embodiments

[0036] The invention applies to the manufacture of a gas turbine revolution part made of composite material comprising an annular wall or barrel and radial edges extending on each side of the annular wall. The gas turbine may in particular be a turbomachine.

[0037] The invention will be described below in the context of its application to the manufacture of a fan casing for an aeronautical gas turbine engine.

[0038] [Fig.l] represents a perspective view of a fan casing 10 that can be manufactured using a mold and a method according to the invention. Such a casing is centered on a longitudinal axis XX and comprises an annular wall 11 extending in an axial direction DA parallel to the axis XX and delimited upstream by a first radial edge, here an upstream flange 12, and downstream by a second radial edge, here a downstream flange 13 (upstream and downstream being defined relative to the direction of flow of the air flow in the gas turbine or the turbomachine), the flanges 12 and 13 extending from the annular wall 11 in a radial direction DR. The internal surface 14 of the annular wall 11 is intended to delimit the air inlet vein in the gas turbine or turbomachine.

[0039] Figures 2A, 2B and 2C schematically and partially represent a mold 200 according to the prior art, when it is closed. Figures 2A and 2C are sectional views of the mold 200 and [Fig.2B] a perspective view of the mold 200. More specifically, [Fig.2A] represents the mold 200 leaving production and [Fig.2C] the mold 200 after several uses.

[0040] The mold 200 can be used for impregnation by a process of the RTM type (“Resin Transfer Molding”) of a fiber preform 210 in order to manufacture a fan casing 10 such as that shown in [Fig.l]. The fiber preform 210 used to manufacture the fan casing 10 can comprise carbon, glass, aramid or ceramic fibers. It can be produced by stacking layers or plies obtained by two-dimensional weaving. The fiber preform can also be produced by unidirectional fiber sheets, which can be obtained by automatic placement of fibers, or by filament winding. The preform is preferably produced directly in a single piece by three-dimensional weaving of a strip wound on the mandrel of the mold.

[0041] The impregnation matrix of the fiber preform may be made of polymer, for example epoxide, bismaleimide or polyimide.

[0042] The mold 200 is mounted on a drive axis (not shown) centered on the axis XX, and comprises a mandrel 230. The mandrel 230 comprises, in the direction axial DA an annular wall taking the form of a barrel 231 on which a fibrous preform 210 is wound, and in the radial direction DR two lateral flanges 232 and 233. The mandrel 230 is held on its drive axis by means of spokes not shown.

[0043] The lateral flanges 230 form a support intended to receive the folded parts or flange preform parts 211 and 212 of the preform 210 wound on the mandrel 230, and which are intended to form the upstream 12 and downstream 13 flanges of the fan casing 10.

[0044] The mold 200 also comprises a counter-mold composed of a plurality of angular sectors 221 assembled in a sealed manner on the mandrel 230, and compacting wedges 220 and 222. In FIGS. 2A and 2C, only one angular sector 221 with its two compacting wedges 220 and 222 are shown.

[0045] When the mold 200 leaves production, the compacting wedges 220 and 222 are held in position against the flange preform portions 211 and 212 of the fiber preform 210 by pressing the angular sector 221 on said compacting wedges 220 and 222 ([Fig.2A]).

[0046] After several uses, the angular sectors 221 of the mold 200 wear out and their length may vary, in particular decrease. A space 250 (shown in an exaggerated manner in [Fig.2C]) thus appears between the flange preform parts 211 and 212 of the fiber preform 210 and the compacting wedges 220 and 222 in the axial direction DA. This space 250 may fill with resin during the injection of resin into the mold 200 and create non-conformities in the thickness of the formed flanges (because these will have an excess thickness of resin or the fiber preform will bulge at this location). In order to avoid non-conformity, as soon as the molds 200 of the prior art are worn, they are sent for maintenance and / or replaced by a new mold.

[0047] [Fig. 3] represents, schematically and partially, a sectional view of a mold 300 according to an embodiment of the invention, when it is closed.

[0048] Like the mold 200 of the prior art, the mold 300 according to the invention can be used for impregnation by a process of the RTM type (“Resin Transfer Molding”) of a fiber preform 310 in order to manufacture a fan casing 10 such as that presented in [Fig.l].

[0049] The mold 300 comprises a mandrel 330. The mandrel 330 comprises an annular wall taking the form of a barrel 331 on which a fiber preform 310 is wound, and two lateral flanges 332 and 333. The mandrel 330 is held on its drive axis by means of spokes not shown.

[0050] The side plates 332 and 333 form a support intended to receive the folded parts or flange preform parts 311 and 312 of the preform 310 wound on the mandrel 330, and which are intended to form the upstream 12 and downstream 13 flanges of the fan casing 10.

[0051] The mold 300 also comprises a counter-mold composed of a plurality of angular barrel counter-mold sectors 320 assembled in a sealed manner on the mandrel 330, and at least two radial edge counter-mold shims, here two flange counter-mold shims 322 and 324, placed between the flange preform portions 311 and 312 of the fiber preform 310 and the angular sectors 320. Each angular barrel counter-mold sector 320 is intended to compact a barrel preform portion 313 of the fiber preform 310 present on the mandrel 330 while the flange counter-mold shims 322 and 324 are intended to compact flange preform portions 311 and 312 of the fiber preform present on the mandrel. The flange counter-mold wedges 311 and 312 are held in position against the flange preform portions 311 and 312 by support from the associated barrel counter-mold angular sector 320.

[0052] According to the invention, each angular sector of barrel counter-mold 320 is divided into a first part 321 and a second part 323 intended to be respectively in contact with the flange counter-mold shims 322 and 324. The first and second parts 321 and 323 are connected to each other by an adjustment device 325 capable of adjusting a distance between the first and second parts along the axial direction DA. More specifically, in the example described here, the adjustment device 325 comprises a base 3254 present between the first and second parts 321 and 322, two screws 3250 and 3252 each being engaged in a thread (not shown in [Fig. 3]) present in the base 3254. The screw 3250, one end 3251 of which is in contact with the second part 323 of the barrel counter-mold 320, makes it possible to adjust the position in the axial direction DA of the second part.Similarly, the screw 3252, one end 3253 of which is in contact with the first part 321 of the barrel counter-mold 320, makes it possible to adjust the position in the axial direction DA of the first part. By screwing or unscrewing the screws 3250 and 3252, the first and second parts 321 and 323 are moved away from or brought closer to each angular sector of the barrel counter-mold 320. A greater number of screws is of course possible. The number of screws per angular sector depends on the diameter of the part to be manufactured and, consequently, on the mold. If the mold comprises four angular sectors of 120°, each angular sector comprises at least 2 screws.

[0053] The adjustment device of the invention is not limited to the device 325 described previously. Any other adjustment device making it possible to adjust the distance between the first and second parts 321 and 323 of each angular sector of barrel counter-mold 320 can be used.

[0054] According to a particular characteristic, each angular sector of counter-mold of barrel 320 may further comprise a sole 328 extending between the first and second parts 321 and 323 at their internal face. The sole 328 makes it possible to fill the space present between the first and a second part 321 and 322, which makes it possible to improve the sealing of the angular sector and to avoid the risk of pinching or swelling of the preform in the space present between the first and a second part 321 and 323.

[0055] In the example described here, the base 3254 supporting the screws 3250 and 3252 is integral with the sole 328.

[0056] [Fig. 3] represents the mold 300 coming out of production while [Fig. 4] represents the mold 300 after several uses. In [Fig. 3], the first and second parts 321 and 323 of the angular sector of the barrel counter-mold 320 are new. The initial spacing between these two parts makes it possible to keep the flange counter-mold shims 322 and 324 pressing against the flange preform parts 311 and 312. The holding and compaction of the flange preform parts are then perfectly ensured.

[0057] On the other hand, in [Fig. 4], the wear of the first and second parts 321 and 323 of the angular sector of the barrel counter-mold 320 causes a loss of contact of the flange counter-mold shims 322 and 324 with the flange preform parts 311 and 312, a space 350 then being present between the shims and the flange preform parts.

[0058] Thanks to the angular sector of the barrel counter-mold in two parts connected together by an adjustment device, it is possible to adjust the distance between the first and second parts 321 and 323 of each angular sector of the barrel counter-mold 320. As illustrated in [Fig. 5], the spacing or space present between the first and second parts 321 and 323 is increased, in the example described here by an additional screwing of the screws 3250 and 3252, which makes it possible to fill the space 350 appearing after wear of the parts 321 and 323. The flange counter-mold shims 322 and 324 are then again in contact with the flange preform parts 311 and 312, which makes it possible to avoid deformation of the preform or the presence of resin between the shims and the flange preform parts.

[0059] According to a particular characteristic, each angular sector of barrel counter-mold 320 further comprises a first seal 326 present between the sole 328 and the first part 321 and a second seal 327 present between the sole 328 and the second part 323. This makes it possible to reinforce the sealing of each angular sector of barrel counter-mold. The first and second seals may be made of an elastomer material capable of withstanding temperatures between 150°C and 170°C.

[0060] The material used to produce the angular sectors of the barrel counter-mold, in particular the first and second parts of each sector, as well as the sole, can be chosen in particular from the following materials: aluminum, titanium and steel.

[0061] The manufacture of a fan casing 10 using a mold according to the invention is now described.

[0062] A fiber preform is first formed on the mandrel 331 of the mold 300 described previously. In the example described here, the preform is formed by winding a 3D woven strip. Methods have already been proposed for winding a fiber preform produced for example by three-dimensional weaving around a mandrel such as that of the invention, and will not be described in more detail. Reference may, for example, be made to application WO 2012 / 140355 which proposes a machine for winding a fiber texture onto an impregnation mandrel.

[0063] Once the preform is wound onto the mandrel, at least two flange counter-mold shims are placed opposite the flange preform portions of the fiber preform present on the mandrel. According to the invention, the distance between the first and a second portion of each angular sector of the barrel counter-mold is adjusted according to the wear observed in order to ensure the contact of each flange counter-mold shim in contact with the flange preform portions of the fiber preform.

[0064] The mold is then closed to compact the preform. To do this, the angular sectors are assembled on the mandrel in a sealed manner and resting on the counter-mold wedges so as to keep each counter-mold wedge in contact with the preform parts of the flanges of the fiber preform.

[0065] The flange counter-mold shims thus allow compaction in the axial direction while avoiding folds and buckling of the fiber preform while the barrel counter-mold sectors ensure compaction of the barrel preform part of the preform in the radial direction.

[0066] A polymerizable resin is then injected into the mold by a pressure differential (by an RTM type process). After injection, the resin is polymerized (by heating or cooling for example, depending on the nature of the resin used) in order to form a matrix in the porosity of the preform. The fan casing thus manufactured can then be demolded. According to one embodiment, at least one of the two radial edge counter-mold shims comprises two separate portions assembled together by screws so as to adjust their support on the radial edge preform parts of the fiber preform. This also makes it possible to compensate for the wear of the radial edge counter-mold shims and / or angular sectors of the barrel counter-mold.

[0067] Furthermore, the mold of the invention may comprise a mandrel having on its external surface a variable profile or several profiles making it possible to form a part of revolution having an internal and / or external surface of variable shape.

Claims

Claims

1. Mold (300) intended to be used for the manufacture of a gas turbine revolution part (10) made of composite material comprising: - a mandrel (330) on which a fiber preform (310) is intended to be formed comprising an annular wall extending in width in an axial direction (DA) and the profile of an outer surface of which corresponds to that of an inner surface (14) of the revolution part (10) to be manufactured and two lateral flanges (332, 333) extending from the annular wall in a radial direction (DR) and the profiles of which correspond to those of radial edges (12, 13) of the revolution part (10) to be manufactured, - a plurality of angular barrel counter-mold sectors (320) intended to be assembled in a sealed manner on the mandrel and to compact a barrel preform portion (313) of the fiber preform (310) present on the mandrel, and - at least two radial edge counter-mold shims (322, 324),the shims being intended to compact radial edge preform parts (311, 312) of the fiber preform present on the mandrel, the radial edge counter-mold shims being held in position by support of at least one angular barrel counter-mold sector (320), characterized in that each angular barrel counter-mold sector (320) is divided into a first and a second part (321, 323) respectively in contact with a radial edge counter-mold shim (322, 324) and in that the first and second parts (321, 323) are connected to each other by an adjustment device (325) capable of adjusting a distance between said first and second parts in the axial direction (DA).,

2. Mold according to claim 1, in which at least one of the two radial edge counter-mold shims comprises two separate portions assembled together by screws so as to adjust their support on the radial edge preform parts of the fiber preform.

3. A mold according to claim 1 or 2, wherein each angular barrel countermold sector (320) further comprises a sole (328) extending between the first and second parts (321, 323) at their internal face, the sole filling the space present between said first and a second part.

4. Mold according to claim 3, in which the sole (328) has a thickness of between 0.1 mm and 1 mm.

5. Mold according to claim 3 or 4, wherein the adjustment device (325) comprises a base (3254) integral with the sole (328), said base being present between the first and second parts (321, 323) of each angular sector of barrel counter-mold (320) and at least a first and a second screw (3250, 3252), each screw being held in a thread present in the base, the end (3251) of the first screw (3250) being in contact with the first part (321) and the end (3253) of the second screw (3252) being in contact with the second part (323).

6. A mold according to claim 3 or 4, wherein each angular barrel countermold sector (320) further comprises a first seal present between the sole (326) and the first part (321) and a second seal (327) present between the sole and the second part (323).

7. Mold according to claim 6, in which the first and second seals (326, 327) are made of an elastomeric material capable of withstanding temperatures between 150°C and 170°C.

8. A method of closing a mold according to any one of claims 1 to 7, the method comprising: - placing at least two radial edge countermold shims (322, 324) for compacting radial edge preform portions (311, 312) of a fiber preform (310) present on the mandrel (330) of the mold (300), - adjusting a distance between first and second portions (321, 323) of each angular barrel countermold sector (320) so as to maintain each countermold shim in contact with the radial edge preform portions of the fiber preform, - sealingly assembling the angular barrel countermold sectors (320) on the mandrel (330).

9. Method of manufacturing a gas turbine revolution part in composite material comprising: - winding a fibrous preform (310) onto the mandrel (330) of a mold (300) according to any one of claims 1 to 7, - closing the mold according to the method of claim 8, - injection of a resin into the mold, - the transformation of the resin into a matrix, and - the demolding of the revolution part (10).

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