FR3146821A1 - Manufacturing process of a turbine ring sector - Google Patents

Abstract

Method for manufacturing a turbine ring sector Method for manufacturing at least one turbine ring sector (300) made of composite material comprising: - producing at least one fibrous blank (10) by three-dimensional weaving, - cutting the outline of the fibrous blank (10), - shaping the fibrous blank (10) so as to obtain a fibrous preform having a shape close to that of the ring sector to be produced, - consolidating the fibrous preform, - loading the consolidated preform onto a support tool, - infiltrating the consolidated preform with a molten metal so as to obtain a raw ring sector made of composite material. When cutting the contour of the fiber blank (10), first and second notches (123, 124) are cut respectively in the first side edge (121) of the lower part (12) and in the second side edge (122) of the lower part (12). The fiber preform is suspended on the support tool by the first and second notches (123, 124). Abstract: Fig. 2.

Description

Manufacturing process of a turbine ring sector

The present invention relates to the manufacture of turbine ring sectors from ceramic matrix composite (CMC) material in which a fibrous preform is infiltrated with molten metal.

Various processes for manufacturing parts made of ceramic matrix composite material are known. The so-called "Pre-preg" process is known, in which threads pre-impregnated with carbon precursor resin are formed into sheets that are then draped to obtain a fibrous preform. The fibrous preform is molded, baked, and finally infiltrated with a metal (or a metal alloy) in the liquid state (molten infiltration technique: "MI" for "Melt-Infiltration"). The so-called "Slurry-Cast" process is also known, in which a woven fibrous preform can first be partially densified by gas, for example by chemical gas infiltration (CVI), then a ceramic powder is introduced into the pre-densified preform, for example by immersion in a suitable slip, and finally the preform is infiltrated with a molten metal (MI) in order to finalize the densification of the part. In either of the processes presented, the infiltration of the preform can be reactive, that is, the molten metal can react with a matrix phase already present in the preform.

Traditionally, due to the design of infiltration furnaces, preforms are infiltrated one after the other by holding them with a clamp, the preform being directly dipped into a bath of molten metal or brought into contact with it using a drain, the drain being for example a fabric, a felt, a mat, or any other porous material. The drain is brought into contact with the molten metal on the one hand, and the preform to be infiltrated on the other hand, the molten metal being transferred to the preform and infiltrated into it by capillarity using the drain.

This infiltration has several disadvantages, including:

- a risk of damage to the preform during installation (impact, fall, etc.),

- a risk of the part falling during the infiltration operation,

- a risk of deformation when tightening the clamp,

- lack of control over the positioning of the preform in its environment.

US2022170143 discloses a support tooling for porous preforms to be infiltrated by molten metal. This document describes preforms having notches used to suspend the preforms on the support tooling. However, in this document the notches are formed by machining after consolidation of the preforms. Such a machining operation is time-consuming and risks causing pollution of the preforms.

It would therefore be desirable to have a simple and economical solution to improve the manufacture of turbine ring sectors in composite material by infiltration with molten metal.

For this purpose, the present invention proposes a method of manufacturing at least one turbine ring sector in composite material comprising:
- producing at least one fiber blank by three-dimensional weaving between a plurality of layers of warp threads and a plurality of layers of weft threads, the fiber blank extending in a longitudinal direction and a transverse direction, the fiber blank comprising a lower portion extending in the transverse direction between first and second lateral edges, the lower portion being intended to form the annular base of the ring sector, and an upper portion extending in the transverse direction between first and second lateral edges, the upper portion being connected to the lower portion by a central portion, the upper portion comprising first and second deployment portions extending in the transverse direction between the central portion and respectively the first and second lateral edges of the upper portion, the first deployment portion being separated from the lower portion by a first separation, the second deployment portion being separated from the lower portion by a second separation, the first and second lateral edges of the lower portion being aligned respectively with the first and second lateral edges of the upper portion,
- cutting the outline of the rough outline,
- shaping the fiber blank by folding the first and second deployment portions towards the central portion so as to form first and second fixing flange preform parts and by curving the lower part so as to form an annular base preform part so as to obtain a fiber preform having a shape close to that of the ring sector to be produced,
- consolidation of the fibrous preform,
- loading the consolidated preform onto a support tool,
- infiltrating the consolidated preform with a molten metal so as to obtain a raw ring sector made of composite material comprising an annular base with first and second lateral edges respectively comprising first and second notches, a first fixing flange and a second fixing flange,
characterized in that, when cutting the outline of the fiber blank, the first and second notches are cut respectively in the first lateral edge of the lower part and in the second lateral edge of the lower part, and in that said at least one consolidated fiber preform is suspended on the support tool by the first and second notches.

The notches allow the preform to be suspended on the support tooling in a stable and balanced manner, with minimal contact between the preform and the tooling.

In the method of the invention, the notches are made at the same time as the cutting of the outline of the fiber blank. The production of the notches therefore has no impact on the manufacturing cost of the ring sector because it is included in the cutting operation of the fiber blank.

In addition, the notches serve as upstream/downstream keying devices for the raw ring sector.

According to a particular characteristic of the method of the invention, the first and second notches are respectively present in sacrificial portions, the sacrificial portions being eliminated after the infiltration of the consolidated preform by a molten metal. The cutting of the notches thus has no impact on the fibrous reinforcement of the final ring sector and, consequently, on the mechanical properties of the composite material ring sector. In addition, the quality of the final ring sector is improved because the points of contact between the support tool and the preform likely to cause defects in the part during infiltration by a molten metal are located outside the final part and are eliminated.

According to another particular characteristic of the method of the invention, the first and second notches are cut by laser beam or pressurized water jet.

According to another particular characteristic of the method of the invention, when cutting the outline of the fiber blank, third and fourth notches are cut respectively in the first lateral edge of the upper part and in the second lateral edge of said upper part, the third and fourth notches being cut simultaneously with the first and second notches. By simultaneously cutting the first and third notches in the first lateral edges of the lower and upper parts and the second and fourth notches in the second lateral edges of the lower and upper parts, the manufacturing method is simplified because it is not necessary to use a tool to protect the upper part of the fiber blank when cutting the notches.

According to another particular characteristic of the method of the invention, the first to fourth notches are respectively present in sacrificial portions, the sacrificial portions being eliminated after infiltration of the consolidated preform by a molten metal.

According to another particular characteristic of the method of the invention, the first to fourth notches are cut by laser beam or pressurized water jet.

According to another particular characteristic of the method of the invention, the support tool comprises a support comprising at least one suspension bar and at least one porous preform support, each support comprising a first part connected to said at least one suspension bar by a sliding connection and a second part extending from the first part, the second part of each porous preform support comprising two transverse arms extending in a second direction, each transverse arm comprising a projection extending in a first direction, the projections cooperating respectively with the first and second notches present on the preform.

According to another particular characteristic of the method of the invention, the second part of each preform support comprises an anti-tilt screw.

According to another particular characteristic of the method of the invention, the second part of each porous preform support comprises an adjustable stop present in the lower part of the second part.

There is a schematic perspective view illustrating the 3D weaving of a fiber blank for the manufacture of the blade of the ,

There is a schematic perspective view of the fibrous outline of the after cutting the outline of said blank in accordance with one embodiment of the invention,

There is a schematic perspective view of a fiber preform obtained from the fiber blank of the ,

There is a schematic perspective view of a raw ring sector in composite material obtained after infiltration by a molten metal of the preform of the ,

There is a schematic perspective view of a composite material ring sector obtained after machining the raw ring sector of the ,

There is a schematic perspective view of a support tool on which the preform of the ,

There is a schematic perspective view of a preform holder of the support tooling of FIG.

There is a schematic front view of the preform holder of the support tooling of the with a fibrous preform,

There is a schematic side view of the preform holder of the support tooling of the ,

There is a schematic cross-sectional view of a furnace for infiltration by molten metal using the support tooling of the .

The method of manufacturing turbine ring sectors of the invention begins with the production of one or more fibrous blanks by three-dimensional weaving between a plurality of layers of warp threads and a plurality of layers of weft threads.

There shows very schematically a fibrous blank 10 intended to form a fibrous preform of a turbine ring sector in composite material to be produced. The fibrous structure blank 10 is obtained, as schematically illustrated in the , by three-dimensional (3D) weaving carried out in a known manner using a jacquard-type loom on which a bundle of warp threads 50 has been arranged in a plurality of layers, the warp threads being linked by weft threads 60.

For weaving the fiber blank 10, ceramic fiber yarns may be used, for example SiC fiber yarns such as those marketed by the Japanese company Nippon Carbon under the name "Hi-Nicalon S", or carbon fiber yarns. The weave may be of the interlock type. Other three-dimensional weave weaves may be used, such as multi-plain or multi-satin weaves. Reference may be made to document WO 2006/136755.

The fibrous blank 10 is woven in a single piece, the blank extending in a longitudinal direction DL and a transverse direction DT. The fibrous blank comprises a lower portion 12 extending in the transverse direction DT between first and second lateral edges 121 and 122, the lower portion 12 being intended to form the annular base of the ring sector, and an upper portion 14 extending in the transverse direction DT between first and second lateral edges 143 and 144. The upper portion 14 is connected to the lower portion 12 by a central portion 16. The upper portion 14 comprises first and second deployment portions 141 and 142 intended to form fixing flanges of the ring sector. The first and second side edges 121 and 122 of the lower part 12 are aligned respectively with the first and second side edges 143 and 144 of the upper part 14.

The first deployment portion 141 extends in the transverse direction DT between the central portion 16 and the first lateral edge 143 of the upper part 14. The first deployment portion 141 is separated from the lower part 12 by a first disconnection 18.

The second deployment portion 142 extends in the transverse direction DT between the central portion 16 and the second lateral edge 144 of the upper part 14. The second deployment portion 142 is separated from the lower part 12 by a second disconnection 19.

Once the fiber blank 10 is woven and as illustrated in the , the outline of the blank is cut, for example using a laser beam or a pressurized water jet, so as to remove the floating threads present outside the woven mass (so-called "trimming" phase) and thus obtain a flat preform of a raw ring sector.

According to the invention, when cutting the flat preform, first and second notches 123 and 124 are cut respectively in the first and second lateral edges 121 and 122 of the lower part 12. In the example described here and illustrated in the , a third notch 145 is cut simultaneously with the first notch 123 in the first lateral edge 143 of the upper part 14 while a fourth notch 146 is cut simultaneously with the second notch 124 in the second lateral edge 144 of the upper part 14.

The cutting of the notches in the fiber blank 10 can be carried out for example by laser beam or pressurized water jet.

According to an alternative embodiment, when cutting the flat preform, only the first and second notches 123 and 124 are cut respectively in the first and second lateral edges 121 and 122 of the lower part 12. In this case, a tool is used to protect the first and second lateral edges 143 and 144 of the upper part 14 when cutting the notches 123 and 124 in order to avoid cutting the notches 145 and 146 in the upper part 14.

By simultaneously cutting the first and third notches 123 and 145 in the first side edges 121 and 143 of the lower 12 and upper 14 portions and the second and fourth notches 124 and 146 in the second side edges 122 and 144 of the lower 12 and upper 14 portions, the manufacturing process is simplified because it is not necessary to use tooling to protect the upper portion of the fiber blank when cutting the notches.

The method continues with the shaping of the fibrous blank 10 so as to obtain a fibrous preform 100 illustrated in the . The fiber preform 100 has a shape close to that of the ring sector to be produced and has a section substantially in the shape of an inverted π. The fiber blank 10 is shaped by folding the first and second deployment portions 141 and 142 of the fiber blank at 90° towards the central portion 16 so as to form first and second fixing flange preform parts 110 and 120 and by curving the lower part 12 of the blank so as to form an annular base preform part 130. The shaping of the fiber blank can be carried out by means of a shaping tool (not shown in the ) allowing the necessary radius of curvature and the desired orientation for the fixing flanges to be imposed on the deployment portions 141 and 142, as well as the desired curvature on the lower part 12. The shaping of the fiber blank may optionally include compacting in order to obtain a target fiber rate.

As illustrated in the , the notches 123, 145, 124 and 146 are respectively present in sacrificial portions 101, 102, 103 and 104 of the fiber preform 100 (delimited by the dotted lines on the ). The sacrificial portions 101, 102, 103 and 104 correspond to zones extending over the entire length of the preform in the longitudinal direction DL and over a width determined from an edge of the preform including the notches. The sacrificial portions 101 to 104 are eliminated at the end of the manufacture of the ring sector as explained below.

The fiber preform 100 is consolidated by chemical vapor infiltration (CVI) of a ceramic matrix phase in order to be able to retain its shape for the rest of the process.

The preform 100 is then loaded onto a support tool 200 with a view to its infiltration by a molten metal. On the , the support tool 200 comprises a support 201 comprising two suspension bars 210 and 220 each extending longitudinally in a first direction D1. The suspension bars 210 and 220 are fixed to a frame 230 by clamping members 231 so as to be kept spaced apart from each other in a second direction D2 perpendicular to the first direction D1. The frame 230 is fixed at its central portion to an interface rod 240 intended to be connected to a mass measuring device of a furnace as explained below.

The support tooling 200 further comprises at least one support 500 for holding the preform 100 during its infiltration with a molten metal. As illustrated in FIGS. 6 to 9 , the support 500 comprises a first portion 510 formed by a first ear 511 having an oblong hole 5110 and a second ear 512 having an oblong hole 5120. Each support 500 can be mounted on a suspension bar of the support tooling 200, for example the suspension bar 210, by placing the two ears 511 and 512 on one side and the other of the bar and by inserting a suspension pin 250 into the oblong holes 5110 and 5120 of the ears 511 and 512 ( ). Each support 500 is thus mounted on a suspension bar 210 by a sliding connection following a third direction D3, perpendicular to the first and second directions D1 and D2.

The support 500 further comprises a second part 520 extending from the first part 510. The second part 520 is intended to support the fiber preform 100. The second part 520 of each support 500 comprises a longitudinal arm 521 extending in the third direction D3 and two transverse arms 522 and 523 extending on each side of the longitudinal arm 521 in the direction D2. A first projection 5220 is mounted on the transverse arm 522 by means of a clamping screw 5222, the projection 5220 extending from the arm 522 in the direction D1 and having a free end 5221. A second projection 5230 is mounted on the transverse arm 523 by means of a clamping screw 5232, the projection 5230 extending from the arm 523 in the direction D1 and having a free end 5231. As illustrated in FIGS. 7 and 8, the free ends 5221 and 5231 of the first and second projections 5220 and 5230 are adapted to cooperate with respectively the second notch 124 and the first notch 123 present respectively on the lateral edges 122 and 121 of the annular base preform portion 130 of the preform 100.

As illustrated in the , the preform 100 is placed on the support 500 by engaging the free ends 5221 and 5231 of the projections 5220 and 5230 respectively in the notches 124 and 123, the preform 100 then being held in suspension by the free ends 5221 and 5231 (FIGS. 8 and 9). Removable adjustment shims 5223 and 5233 can be used to adjust the air gap of the projections 5220 and 5230 relative to the spacing between the notches 124 and 123 in the direction D2. The suspension of the preform 100 by the projections 5220 and 5230 does not require the presence of orifices on the legs of the preforms, which makes it possible to avoid operations of machining orifices in the preforms when these are not useful for fixing or maintaining the ring sectors.

According to an optional feature of the support 500, the latter may comprise an anti-tilt screw 524 whose threaded rod 5241 is screwed into an orifice 525 present on the upper part of the longitudinal arm 521. The head 5240 of the anti-tilt screw 524 blocks the tilting of the preform 100 ( ).

According to another optional characteristic of the support 500, the latter may comprise a fixed stop 526 present on the upper part of the longitudinal arm 521 in order to limit by point contact the translation of the porous preform in the direction D1.

Still according to another optional characteristic of the support 500, the latter may comprise an adjustable stop 527 present on the lower part of the longitudinal arm 521 in order to limit by point contact the rotation of the preform on the projections and thus position the preform along a vertical plane parallel to the direction D3 during the operations of infiltration of the preform with a molten metal. The adjustable stop 527 cooperates by screwing with an orifice 528 present on the lower part of the longitudinal arm 521.

In combination with the notches 124 and 123, the support 500 makes it possible to reliably hold a porous preform with only a few punctate contact points, which makes it possible to optimize the infiltration of the preform by a molten metal while facilitating and securing the loading of the preform onto the support tooling.

Once loaded onto the support tool 200, the preform 100 is densified by infiltration with liquid silicon (“Melt Infiltration”).

The support tooling can support a variable number of fiber preforms. The support tooling 200 described here can support up to eight fiber preforms. Of course, depending on the needs and dimensions of the support tooling of the invention, it can support a greater or lesser number of preforms. However, care will be taken to have an equivalent number of preforms and a symmetrical distribution of the latter on each suspension bar in order to balance the support tooling and not disturb the mass measurement during infiltration.

There shows a sectional view of a furnace 1 according to an embodiment of the invention that can be used in an infiltration method according to the invention. The furnace 1 comprises a hermetic enclosure 2 inside which are present a crucible 4 having an internal volume containing a molten metal 6, and a support tool 200 comprising a plurality of supports 500 each loaded with a fibrous preform 100 as described above.

The crucible 4 may be made of a ceramic material. The molten metal 6 may for example be silicon or a silicon alloy. The furnace 1 is here provided with an induction heating system 40 comprising an induction coil 42 and a susceptor 44 which are arranged around the crucible 4 and the preform 8 in the enclosure 2 of the furnace 1. The heating system further comprises, in a known manner, a high-frequency generator 36 connected to the coil 42 so as to generate a variable magnetic field using the coil. The susceptor 44 may for example be a graphite cylinder. The furnace 1 may further be provided with a vacuum pump 38 in fluid communication with the interior of the enclosure 2, so as to carry out the vacuum infiltration process. It will be noted that another type of furnace than that illustrated may be used, in particular the furnace may comprise a resistive heating system instead of an inductive system.

The oven 1 comprises a device for measuring the mass of the preforms 100 corresponding here to a scale 20 of the weighing type, from which the support tool 200 is suspended by means of the interface rod 240. In this example, the scale 20 is located outside the enclosure 2 of the oven 1, above the enclosure 2. Of course, other mass measuring devices can be used without departing from the scope of the present invention.

The furnace 1 further comprises a moving device comprising here a jack 24 having a rod 26 on which the crucible 4 is mounted. In this example, the jack 24 is located outside the enclosure 2 of the furnace 1, below the enclosure 2. In this way, the jack 20 makes it possible to move the crucible 4 with a vertical translation movement inside the enclosure 2 of the furnace 1, in particular in the direction of the preforms 100 present on the support tool 200. Thus, the crucible 4 is movable in vertical translation in the enclosure 2. In a variant not illustrated, the crucible can be fixedly mounted in the furnace, and the preform can be movable in vertical translation.

In the illustrated example, the furnace 1 also comprises a control system 28 for controlling the relative position between the preforms and the crucible, which is configured to control the jack 24 according to the change in the mass of the preforms 100 as measured by the scale 20. This control system 28 may be, for example, an automaton or a computer equipped with an input/output acquisition card. The control system 28 may receive electrical signals from the scale 20 as input, and send control signals as output to the jack 24.

The infiltration of the preforms 100 is carried out by bringing said preforms into contact with the molten metal 6 which may for example be silicon or a silicon alloy, the molten metal infiltrating the porosity of the preforms by capillarity. The contact may be direct, that is to say that the preforms are directly dipped in the bath of molten metal, or indirect by bringing the preforms into contact with one or more drains (not shown in the ) themselves in contact with the bath of molten metal which is then conveyed to the preforms by capillarity. The contacting or not of the preforms with the molten metal and, consequently, the control of the infiltration of the preforms by the molten metal are carried out by the control of the jack 24. The infiltration of the preforms 100 by the molten metal 6 ends when the scale 20 measures a predetermined mass gain corresponding to the desired level of densification for the preforms.

We then obtain parts, here raw ring sectors, in CMC material comprising a fibrous reinforcement densified by a matrix and having a shape similar to that of the preform 100 shown in the figure. . As illustrated in the , each raw ring sector 300 comprises an annular base 330 with first and second lateral edges 121 and 122 respectively comprising the first and second notches 123 and 124, a first fixing flange 310 with a free end comprising the third notch 145 and a second fixing flange 320 with a free end comprising the fourth notch 146. The notches 123, 145, 146 and 124 are respectively present in sacrificial zones 301 to 304 corresponding respectively to the sacrificial zones 101, 102, 103 and 104 of the fibrous preform 100.

The raw ring sector 300 is machined in order to eliminate the sacrificial zones 301, 302, 303 and 304. This gives the shape shown in the figure. a ring sector 400 made of composite material comprising a fibrous reinforcement constituted by the fibrous preform 100 without the sacrificial zones, the ring sector 400 comprising an annular base 430 whose internal face is intended to define a gas flow vein in a gas turbine and fixing flanges 410 and 420 extending from the external face of the annular base 430.

Claims (9)

Method for manufacturing at least one turbine ring sector (300) in composite material comprising:
- producing at least one fibrous blank (10) by three-dimensional weaving between a plurality of layers of warp threads (50) and a plurality of layers of weft threads (60), the fibrous blank extending in a longitudinal direction (DL) and a transverse direction (DT), the fibrous blank (10) comprising a lower portion (12) extending in the transverse direction between first and second lateral edges (121 and 122), the lower portion (12) being intended to form the annular base of the ring sector, and an upper portion (14) extending in the transverse direction between first and second lateral edges (143, 144), the upper portion (14) being connected to the lower portion (12) by a central portion (16), the upper portion comprising first and second deployment portions (141 and 142) extending in the transverse direction between the central portion (16) and the first and second lateral edges respectively side edges (143, 144) of the upper part (14), the first deployment portion (141) being separated from the lower part (12) by a first separation (18), the second deployment portion (142) being separated from the lower part (12) by a second separation (19), the first and second side edges (121, 122) of the lower part (12) being aligned respectively with the first and second side edges (143, 144) of the upper part (14),
- cutting the outline of the fibrous blank (10),
- shaping the fibrous blank (10) by folding the first and second deployment portions (141, 142) towards the central portion (16) so as to form first and second fixing flange preform parts (110, 120) and by curving the lower part (12) so as to form an annular base preform part (130) so as to obtain a fibrous preform (100) having a shape close to that of the ring sector to be produced,
- consolidation of the fibrous preform (100),
- loading the consolidated preform onto a support tool (200),
- infiltrating the consolidated preform with a molten metal so as to obtain a raw ring sector (300) made of composite material comprising an annular base (330) with first and second lateral edges respectively comprising first and second notches (123, 124), a first fixing flange (310) and a second fixing flange (320),
characterized in that, when cutting the outline of the fiber blank (10), the first and second notches (123, 124) are cut respectively in the first lateral edge (121) of the lower part (12) and in the second lateral edge (122) of the lower part (12), and in that said at least one consolidated fiber preform is suspended on the support tool (200) by the first and second notches (123, 124). The method of claim 1, wherein the first and second notches (123, 124) are respectively present in sacrificial portions (101, 104), the sacrificial portions being removed after infiltration of the consolidated preform with molten metal. A method according to claim 1 or 2, wherein the first and second notches are cut by laser beam or pressurized water jet. A method according to any one of claims 1 to 3, wherein, when cutting the outline of the fibrous blank (10), third and fourth notches (145, 146) are cut respectively in the first lateral edge (143) of the upper part (14) and in the second lateral edge (144) of said upper part, the third and fourth notches being cut simultaneously with the first and second notches (123, 124). The method of claim 4, wherein the first to fourth notches (123, 124, 145, 146) are respectively present in sacrificial portions (101, 104, 102, 103), the sacrificial portions being removed after infiltration of the consolidated preform with molten metal. A method according to claim 4 or 5, wherein the first to fourth notches are cut by laser beam or pressurized water jet. Method according to any one of claims 1 to 6, wherein the support tooling comprises a carrier (201) comprising at least one suspension bar (210) and at least one porous preform support (500), each support comprising a first part (510) connected to said at least one suspension bar by a sliding connection and a second part (520) extending from the first part, the second part (520) of each porous preform support (500) comprising two transverse arms (522, 523) extending in a second direction (D2), each transverse arm comprising a projection (5220; 5230) extending in a first direction (D1), the projections (5220, 5230) cooperating respectively with the first and second notches (123, 124) present on the preform (100). The method of claim 3, wherein the second portion (520) of each preform support (100) comprises an anti-tilt screw (524). The method of claim 3 or 4, wherein the second portion (520) of each porous preform support (500) comprises an adjustable stop (528) present in the lower portion of the second portion.