Wax model cluster and mold for manufacturing plurality of turbine engine elements by lost wax casting

Abstract

The invention relates to a wax pattern cluster around which a mould (1) for manufacturing a plurality of bladed turbine engine elements by lost wax casting is intended to be formed, the mould having a longitudinal axis (X), and comprises: a replica mold for the casting cup (2), a replica mold for the center injection port (3), a plurality of replica molds for the mold element (4), and a plurality of replica molds for the raw material supply duct (5) for the mold element (4). According to the invention, each replica mold of the raw material supply conduit (5) is connected to the replica mold of the mold element (4) via the replica mold of the fluid communication element (6a, 6b, 6c).

Description

Technical Field

[0001] The present invention relates to the field of manufacturing bladed elements for turbine engines, and more particularly for aircraft turbine engines, in clusters by means of the lost wax casting technique.

[0002] The term bladed element refers to both stationary blades and moving blades. Thus, each bladed element can be a sector comprising a plurality of moving blades, such as a low-pressure distributor sector, or a single stationary blade, such as a compressor or turbine impeller stationary blade.

[0003] The invention relates more particularly to the design of a model cluster and to the design of a mould intended to be formed around this model, the model being in particular made of wax, wherein the metal is intended to be cast in the mould in order to obtain a turbine engine component.

[0004] The invention thus provides a pattern cluster and a mould for obtaining at least one casting device independent of the turbine engine element to be formed, and a manufacturing method for the associated lost wax casting of a plurality of bladed elements.

[0005] The invention relates to all types of aircraft turbine engines, in particular turbojets and turboprops. Background Art

[0006] The lost wax casting technique for simultaneously manufacturing several bladed elements of aircraft turbine engines, ie, stationary or moving blades, such as impeller stationary blades, is well known in the prior art. For example, this technique is described in French patent application FR 3 061051 A1.

[0007] As a reminder, precise lost wax casting consists of producing in wax a model of each of the desired bladed elements by injection into a tool. The assembly of these models makes it possible to form a cluster which is subsequently dipped in different substances to form a ceramic mold of substantially uniform thickness around it. A cluster is also often referred to as a "cluster assembly" or "wax mandrel", although not all of its components must necessarily be made of wax or another sacrificial material.

[0008] The process continues by melting the wax which then leaves its impression in the ceramic mould, where the molten metal is poured via a casting cup assembled on a metal dispenser. After cooling the metal, the mould is broken and the metal part is separated and finished.

[0009] This technology offers the advantage of dimensional accuracy, making it possible to reduce or even eliminate some machining operations. In addition, it provides a very good surface finish.

[0010] In the field of lost wax casting, the principle of top or gravity casting of molten metal is known, which principle consists in casting the metal top into a cavity of a mold intended to form a turbine engine component. According to this principle, the molten metal is cast in a cup and then generally reaches an annular system for supplying a plurality of cavities intended to form the turbine engine component, as described in French patent application FR 2 985 924 A1.

[0011] Furthermore, in the field of lost wax casting, the principle of bottom casting of molten metal is known, which on the other hand consists in bottom casting the metal into a cavity of a mold intended to form a turbine engine component. Typically, the molten metal is cast in a cup, and then a specific pipe connected to the cup allows the metal to be injected from the bottom part of the cavity.

[0012] As the demand for parts produced by lost wax casting techniques increases, there exists a need to increase the production rate of these parts.

[0013] To this end, it has been envisaged to increase the cluster size without modifying the other components, so as to allow the production of an additional number of components while limiting the costs of implementing such an increase in size.

[0014] However, it has been observed that such a configuration does not provide satisfactory results, since increasing the cluster size without any other changes causes metal feed shortage, which generates microporous defects in the obtained parts. As a result, the obtained parts have a relatively large number of fractures and, therefore, a considerable scrap rate.

[0015] Therefore, there is a need to optimize the current lost wax casting technology, and in particular within the scope of the bottom casting principle using a model cluster. In particular, there is a need to make it possible to increase the number of blades manufactured without reducing the quality of the output parts, i.e. without reducing the metallurgical soundness of the produced turbine engine parts. Summary of the invention

[0016] The object of the present invention is to at least partially remedy the above-mentioned disadvantages associated with the technology of the prior art.

[0017] To this end, the invention relates to a cluster of wax models around which a mould for manufacturing a plurality of bladed turbine engine elements by lost wax casting is formed, the wax being intended to be removed by melting and replaced by injected metal, said model having a longitudinal axis X and comprising:

[0018] - a replica mould of the casting cup capable of allowing the molten metal to be injected into the mould;

[0019] - a replica of a central sprue extending along the longitudinal axis X and capable of fluid communication with the casting cup to receive the molten metal;

[0020] - a plurality of replicas of a mould element, each replica being intended to obtain one of the turbine engine elements, each mould element comprising a first upper end portion and a second lower end portion separated by a middle portion;

[0021] - A plurality of replicas of the material supply conduits of the mould element, capable of fluid communication with the central sprue, so as to allow bottom casting of the mould element.

[0022] According to the invention, each replica of the raw material supply conduit is connected to the replica of the mold element via a replica of the fluid communication element comprising a first communication element at the top, a second communication element at the bottom and a third communication element at the middle.

[0023] Furthermore, the invention makes it possible to implement a bottom casting making it possible to protect a fragile core that will be inserted in the various mould elements in order to form the duct with the bladed elements.

[0024] The invention also relates to a mould for manufacturing a plurality of turbine engine components, said mould having a longitudinal axis X and comprising:

[0025] - a casting cup capable of allowing the molten metal to be poured into the mould;

[0026] - a central filling port extending along the longitudinal axis X and in fluid communication with the casting cup to receive the molten metal;

[0027] - a plurality of mould elements, each intended to obtain one of the turbine engine elements, each mould element comprising a first upper end portion and a second lower end portion separated by a third middle portion;

[0028] - A plurality of material supply conduits of the mould element, in fluid communication with the central sprue, so as to allow bottom casting of the mould element.

[0029] According to the present invention, each raw material supply conduit is connected to the mold element via a fluid communication element, which includes a first communication element located at the upper portion, a second communication element located at the lower portion, and a third communication element located at the middle portion.

[0030] Furthermore, the present invention provides a novel and inventive method which makes it possible to at least partially resolve the disadvantages of the prior art.

[0031] In particular, and characterised in that several points of connection are implemented in order to convey the injected metal from the different raw material supply pipes to the mould elements, which makes it possible to provide a filling front of the mould elements both from the bottom to the top and in the middle, thereby limiting the turbulence of the injected metal flow when it reaches the position of the mould elements and therefore limiting the stresses exerted on the different parts during the metal casting process.

[0032] This embodiment therefore makes it possible to increase the number of bladed elements manufactured without reducing the quality of the resulting component, ie without reducing the metallurgical soundness of the turbine engine component produced.

[0033] The scrap rate of components cast in this way is therefore relatively limited, which leads to a reduction in production costs.

[0034] Moreover, this solution makes it possible to ensure a relatively efficient production rate compared to the prior art.

[0035] Finally, this implementation makes it possible to optimize size, and therefore production costs, by producing a greater number of parts via a single cluster model and mould.

[0036] According to a particular aspect of at least one embodiment of the invention, the mold comprises a central element, the axis of which coincides with the longitudinal axis X of the mold and which is attached to the central sprue.

[0037] Furthermore, a plurality of radial arms extend from the central element and contact the communication element located at the lower portion, such that each of the radial arms supports the second lower end portion of a different mold element.

[0038] In this way, the central element makes it possible to hold and strengthen the different parts of the mold during metal injection.

[0039] According to a particular aspect of at least one embodiment of the invention, the mold comprises sealing means arranged between said central element and said central injection port to create a mechanical seal during metal injection.

[0040] In this way, the central element is separated from the central sprue due to its tight mechanical connection with the metal during casting, the central element thus being able to fulfil its function of holding and reinforcing the different parts of the mould during metal injection.

[0041] According to a particular aspect of at least one embodiment of the invention, each of the raw material supply conduits of the mold element forms an angle of between 10° and 40° with the central sprue.

[0042] In this case, according to a particular aspect of at least one embodiment of the invention, each of the raw material supply conduits of the mold elements forms an angle of between 12° and 30° with the central injection port.

[0043] This makes it possible to obtain optimal filling of the mould elements by limiting turbulence during filling.

[0044] According to a particular aspect of at least one embodiment of the invention, the mold comprises between 8 and 32 mold elements, preferably 16 mold elements, which are regularly spaced circumferentially around the longitudinal axis X.

[0045] This therefore makes it possible to produce a large number of bladed elements while limiting the costs of implementing the production installation, since the elements are produced simultaneously.

[0046] According to a particular aspect of at least one embodiment of the invention, the mold component is a bladed turbine engine component.

[0047] According to a particular aspect of at least one embodiment of the present invention, the mold is made of ceramic.

[0048] The present invention also relates to a method for manufacturing a plurality of bladed turbine engine elements by lost wax casting, the method being implemented using a mold according to one of the embodiments cited above and / or using a cluster model according to the embodiments cited above, the method comprising the step of casting metal in the mold so that the wax melts to form at least the bladed turbine engine elements.

[0049] According to a particular aspect of at least one embodiment of the invention, the method further comprises a step for producing a material other than metal, in particular a ceramic, in order to form the mould. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The invention and the different advantages it offers will be more easily understood from the following description of an illustrative and non-limiting embodiment of the invention and from the accompanying drawings, in which:

[0051] Figure 1 shows a perspective view of a bladed turbine engine element intended to be obtained by implementing the method according to the invention, said bladed element being in the form of a low-pressure distributor sector;

[0052] Figure 2 A perspective view showing a mold for manufacturing a plurality of bladed turbine engine components by lost wax casting according to an embodiment of the invention, and

[0053] Figure 3 Shown according to Figure 2 Detailed perspective view of a mold portion of an embodiment of the present invention. Specific embodiments

[0054] Throughout the specification, any of the terms “upper”, “lower”, “top” and “bottom” should be understood to refer to the orientation according to the view in the drawings.

[0055] See also Figure 1 , shows an aircraft turbine engine low-pressure distributor sector 100. The sector comprises a plurality of blades 200 arranged between a first end 400 and a second end 600. The two ends 400, 600 form an outer angular sector and an inner angular sector, respectively, and each comprises a platform 800 delimiting a primary gas cycle jet 300. In addition to the platform 800 to which the aerodynamic function is attached, each end comprises conventional structures allowing the bladed element to be mounted on a turbine engine module.

[0056] The object of the present invention is therefore to manufacture a dispenser sector 100 by a lost wax casting method, using a mould 1 or using a wax cluster model around which the mould 1 is intended to be formed.

[0057] It should be pointed out that the choice of a low-pressure distributor sector is only one embodiment and that the invention also makes it possible to manufacture other turbine engine elements, which may be, for example, compressor or turbine rotating blades, or compressor or turbine stator blades, thereby producing these blades separately or in sectors comprising one or more blades.

[0058] First, in the method, a cluster of a model (not shown) is produced, also called a replica mold, around which a mold is formed. The cluster consists essentially of a sacrificial element made of wax.

[0059] The step of forming the mould is carried out in a material other than metal, and more particularly in ceramic. This forming step is carried out by dipping the wax model in a continuous bath. After drying, the mould 1 obtained has a general cluster shape and comprises mould elements.

[0060] Now refer to Figure 2 and Figure 3 An exemplary embodiment of a mold 1 according to the invention is described for producing a plurality of turbine engine components by lost wax casting, and in particular for producing bladed components.

[0061] In the following description, although the features mentioned are described with respect to the mould 1 , it will be understood that they apply similarly to the wax cluster-shaped model around which the mould 1 is intended to be formed.

[0062] like Figure 2As shown, the mould 1 comprises a casting cup 2 which is capable of allowing molten metal to be poured into the mould 1 .

[0063] The casting cup 2 has the shape of a cone of revolution with a central axis X, which therefore coincides with the central axis of the entire mold 1 .

[0064] It also has a peripheral edge 21 arranged on the outer periphery.

[0065] The mould 1 further comprises a central sprue 3 extending along the longitudinal axis X of the mould. The central sprue 3 is arranged in fluid communication with the casting cup 2 to receive the molten metal.

[0066] In this embodiment, the central injection opening 3 here takes the form of a hollow cylinder, so that it can be penetrated by the injected metal.

[0067] The mold 1 also comprises a plurality of mold elements 4 each intended to obtain one of the turbine engine components.

[0068] According to an embodiment, the mould comprises between 8 and 32 mould elements.

[0069] In the embodiment shown, the mould 1 comprises sixteen mould elements 4 , regularly spaced circumferentially around the longitudinal axis X. In the embodiment shown in FIG.

[0070] Each of these mould elements 4 comprises a first upper end portion 4a and a second lower end portion 4b separated by a third middle portion 4c.

[0071] In order to connect the mould element 4 to the central sprue 3 , the mould 1 comprises a plurality of raw material supply conduits 5 of the mould element 4 , which are formed in fluid communication with the central sprue 3 so as to allow bottom casting of the mould element 4 .

[0072] Thus, bottom casting of the metal is performed in the mould element.Molten metal is poured into the casting cup 2 in order to be delivered to the mould element 4 via a central sprue 3 and subsequently a raw material supply conduit 5 .

[0073] To this end, each raw material supply conduit 5 is connected to a different mold element 4 via fluid communication elements including a first fluid communication element 6a located at the upper part, a second fluid communication element 6b located at the lower part, and a third fluid communication element 6c located in the middle part.

[0074] In other words, for each mold element 4, the first fluid communication element 6a connects the raw material supply conduit 5 to the upper portion 4a of the mold element 4, while the second fluid communication element 6b connects the raw material supply conduit 5 to the lower portion 4b of the mold element 4, and the third fluid communication element 6c connects the raw material supply conduit 5 to the middle portion 4c of the mold element 4.

[0075] Thus, by implementing these three points of connection between the raw material supply conduit 5 and the mold element 4 for delivering the injected metal, a filling front of the mold element is provided first at the bottom, then in the middle and finally at the top, thereby limiting the turbulence of the injected metal flow when it reaches the position of the mold element and, therefore, limiting the stresses exerted on the different parts during the metal casting process. More specifically, by implementing these three points of connection between the raw material supply conduit 5 and the mold element 4 for delivering the injected metal, it was found that the areas where the flow velocity of the injected metal is greater than 1 m / s, corresponding to the factors that weaken the elements and, therefore, make them susceptible to fracture, are relatively reduced or eliminated.

[0076] Furthermore, this makes it possible to maintain a satisfactory quality of the component during cooling and solidification.

[0077] Furthermore, this solution enables savings in terms of material used and therefore production costs, due to the reduction in scrap and therefore in metal waste.

[0078] Such a solution can also achieve better yields.

[0079] According to the invention, and similarly, the wax cluster of the model comprises:

[0080] - A replica mold for casting the cup;

[0081] - a replica mold of a central sprue extending along the longitudinal axis;

[0082] - a replica mold of multiple mold elements;

[0083] - Multiple replicas of the material supply conduits of the mould element, capable of fluid communication with the central sprue to allow bottom casting of the mould element.

[0084] Here, and according to the invention, each of the replica molds of the raw material supply conduits is connected to the replica mold of the mold element via a replica mold of fluid communication elements, which include a first communication element located at the top, a second communication element located at the bottom and a third communication element located in the middle.

[0085] More specifically Figure 3 As shown, the mould also comprises a central element 7 , the axis of which coincides with the longitudinal axis X of the mould 1 and which is attached to the central sprue 3 .

[0086] More specifically, the central element 7 is arranged in succession to the central injection port 3 and also takes the form of a cylinder extending along the longitudinal axis X.

[0087] Furthermore, as shown, a plurality of radial arms 8 extend from the central element 7 and are in contact with the second fluid communication element 6 b of the lower portion, such that each of the radial arms supports the second lower end 4 b of a different mold element 4 .

[0088] In this way, the plurality of radial arms forms a base on which the mould elements are supported awaiting metal injection.

[0089] In other words, the central element 7 and the radial arms 8 make it possible to hold the mould elements, the raw material supply ducts and the central sprue and to strengthen them.

[0090] In order to seal these elements forming the base during the metal injection process, the mould also comprises sealing means arranged between the central element 7 and the central injection port 3 .

[0091] For example, these sealing means may comprise a ceramic plug to be inserted between the central element and the central injection port.

[0092] Embodiments of sealing means may also be provided between the radial arm and the second lower end portion 4 b of the mould element 4 .

[0093] Similarly, these sealing means between the radial arms and the second lower end portion 4b of the mould element 4 may for example consist of ceramic plugs to be inserted between the central element and the central injection port.

[0094] Furthermore, in order to obtain optimal filling by limiting turbulence during filling, each of the raw material supply ducts 5 of the mold element 4 forms an angle of between 10° and 40° with the central sprue 3, and more particularly in the present embodiment between 12° and 30°.

[0095] The illustrated embodiments are not restrictive and the present invention is not limited to the exemplary embodiments described above.

[0096] For example, an embodiment can be provided in which each of the raw material supply conduits forms an angle of 50° to 90° with the central injection port to feed the mold. In this supply mode, a filling without metallurgical defects is performed, for example in areas of thin thickness, making it necessary to seek filling of the elements upstream of the mold as early as possible. For example, for an angle of 60° to 85° between each of the raw material supply conduits and the central injection port, such a filling can be obtained as early as possible.

[0097] Specific needs may also require an angle of less than 10°, in which case the raw material supply duct is filled as in the standard case of equiaxed cluster filling.

[0098] For example, according to alternative embodiments of the present invention, the above principles may obviously be applied to any other type of adaptable cluster configuration.

[0099] Embodiments of any compatible materials other than wax and ceramic may also be provided for the steps of the methods associated with these materials.

Claims

1. A cluster of wax patterns around which a mould (1) is intended to be formed for manufacturing a plurality of bladed turbine engine components by lost wax casting, the wax being intended to be removed by melting and replaced by injected metal, the pattern having a longitudinal axis (X) and comprising: - a replica of the casting cup (2) capable of allowing the injection of molten metal into the mould (1); - a replica of a central sprue (3), extending along the longitudinal axis (X), said central sprue being able to be in fluid communication with the casting cup (2) to receive the molten metal; - a plurality of replicas of a mould element (4), each replica being intended to obtain one of the turbine engine elements, each mould element (4) comprising a first upper end portion (4a) and a second lower end portion (4b) separated by a middle portion (4c); - a plurality of replicas of the raw material supply conduit (5) of the mould element (4), capable of being in fluid communication with the central injection port (3) so as to allow the bottom casting of the mould element (4), Characterized in that each replica mold of the raw material supply pipeline (5) is connected to the replica mold of the mold element (4) via a replica mold of a fluid communication element (6a, 6b, 6c), and the fluid communication element includes a first communication element located in the upper part (6a), a second communication element located in the lower part (6b), and a third communication element located in the middle part (6c).

2. A mould (1) for manufacturing a plurality of turbine engine components, said cluster mould having a longitudinal axis (X) and comprising: - a casting cup (2) capable of allowing the molten metal to be poured into the mould (1); - a central sprue (3) extending along the longitudinal axis (X) of the mould (1), said central sprue being in fluid communication with the casting cup (2) to receive the molten metal; - a plurality of mould elements (4), each intended to obtain one of the turbine engine components, each mould element (4) comprising a first upper end portion (4a) and a second lower end portion (4b) separated by a third intermediate portion (4c); - a plurality of raw material supply conduits (5) of the mould element (4), in fluid communication with the central injection port (3) so as to allow bottom casting of the mould element (4), It is characterized in that each raw material supply pipeline (5) is connected to the mold element (4) via a fluid connecting element (6a, 6b, 6c), and the fluid connecting element includes a first connecting element located at the upper part (6a), a second connecting element located at the lower part (6b), and a third connecting element located in the middle part (6c).

3. The mold according to claim 2, characterized in that: The mould comprises a central element (7) whose axis coincides with the longitudinal axis (X) of the mould (1) and is attached to a central injection port (3), and a plurality of radial arms (8) extend from the central element (7) and are in contact with the connecting element located at the lower part (6b), so that each of the radial arms supports the second lower end portion (4b) of a different mould element (4).

4. The mold according to claim 3, characterized in that: The mould comprises sealing means arranged between the central element (7) and the central sprue (3) to create a mechanical seal during metal casting.

5. The mold according to any one of claims 2 to 4, characterized in that: Each of the raw material supply conduits (5) of the mould element (4) forms an angle of between 10° and 40° with the central injection port (3).

6. The mold according to any one of claims 2 to 5, characterized in that The mould comprises between 8 and 32 mould elements (4), preferably 16 mould elements (4), which are regularly spaced circumferentially around the longitudinal axis (X).

7. The mold according to any one of claims 2 to 6, characterized in that The mold element (4) is a turbine engine element with blades.

8. The mold according to any one of claims 2 to 7, characterized in that The mold is made of ceramic.

9. A method for manufacturing a plurality of bladed turbine engine components by lost wax casting, characterized in that Using a mold (1) according to any one of claims 2 to 8 and / or using a model cluster according to claim 1, the method is implemented, comprising the step of casting metal in the mold (1) to melt the wax to form at least a bladed turbine engine element.

10. The method according to the preceding claim, characterized in that The method further comprises the step of making a material other than metal, in particular a ceramic, to form the mould (1).

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