System and method for mounting parts intended to form a low-pressure turbine for a turbomachine

Abstract

The invention relates to a system (20) for mounting parts intended to form a low-pressure turbine for a turbomachine, comprising: - a plurality of detached parts (102) intended to be mounted with respect to one another, - a frame (200) to support the mounting of the detached parts, said frame comprising: - a base (210) to which at least one casing (10) is fastened, and - a centring column (220), positioned perpendicular to the base (210) and central to the casing (10), the detached parts (102) being mounted on the casing and / or on other detached parts, around the centring column, - at least one comparator apparatus (230) mounted on at least one control axis (Rn) extending between one of the detached parts (102) to be mounted and the centring column (220) in order to determine a central positioning of said detached part with respect to the centring column.

Description

DESCRIPTION TITLE: System and method for assembling parts intended to form a low-pressure turbine for a turbomachine TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a system for assembling various parts intended to form a low-pressure turbine for a turbomachine. It also relates to the method of assembling these parts.

[0002] The invention has applications in the field of aircraft turbomachinery and, in particular, in the field of low-pressure turbomachinery turbines to improve the performance of these turbines. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] A turbomachine typically comprises several stages through which a primary airflow and a secondary airflow pass. These stages generally consist of a fan, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine, and a nozzle. The low-pressure turbine, also called the LP turbine, extends around a rotational axis AA of the turbomachine and includes a distributor consisting of several fixed and several moving blades, mounted by their roots in disc recesses.

[0004] An example of a runner 101 of a conventional BP 100 turbine is shown in Figure 1. An example of an assembly of several conventional runners is shown schematically in Figure 2. A runner 101 generally comprises a disc 120 around the periphery of which several blades 110 are mounted. Each blade 110 has a blade 111 connected by a platform 112 to a central wall, or strut 113, which is radially extended by a foot 114. The BP turbine disc 120 has grooves, called slots, positioned regularly around the periphery of the disc and designed to receive the foot 114 of a blade 110. The disc 120's main functions are to transmit the torque from the blades 110 to the shaft of the BP 100 turbine (not shown in the figure), to position the blades in the secondary flow of the BP 100 turbine, and to ensure the support for sealing parts such as the 150 movable rings.

[0005] In a classic architecture, such as that of figures 1 and 2, the movable ring 150, also called a spacer, is held on the movable wheel 101 by a flange 154 and extends to a retaining ring 140. The movable ring 150, equipped with blades 152, has the function of ensuring the seal between the discs 120 thanks in particular to the blades 152 in interface with an abradable ring 162 fixed on the fixed vanes 160 of the opposite distributors.

[0006] Such an architecture presents drawbacks during assembly. Indeed, for the BP 100 turbine to perform at its best, it is important that some of the turbine components be as close to each other as possible, without, however, touching each other during assembly, as any contact between these components during assembly could seriously damage the BP 100 turbine. It is therefore crucial that the clearance between these components be controlled. One of the main clearances to control is that between the spacer blades 152 and the abradable rings 162. In fact, the smaller the clearance between the blades and the abradable rings, the higher the turbine's performance; but the smaller the clearance, the greater the risk of contact between the components during assembly. An example of the clearance J between the spacer blades 152 and the corresponding abradable ring 162 is shown in Figure 3.This clearance J is defined during the assembly of the various components that make up the BP 100 turbine, hereafter referred to as "spare parts." However, the abradable rings 162 have the particularity of being "floating," meaning that, while maintaining a roughly annular shape, they can move during installation, particularly in the horizontal plane (XZ). This has the effect of making the clearance J between the abradable ring 162 and all the runners 152 opposite said abradable ring uncontrollable during assembly. Indeed, the clearance J between the abradable ring 162 and each of the runners 152 opposite said abradable ring must be controlled, that is, conforming to a predefined clearance J (generally chosen to be as small as possible) that makes the position of the abradable ring fixed.If, during assembly, the play J is not controlled between the abradable ring 162 and each of the slicks 152, it may result in degradation of the parts due to contact between said parts, which would impact engine performance.

[0007] One of the techniques used to avoid this risk of contact during assembly is to define a safe clearance J, i.e. a clearance wider than necessary, which has a negative effect on the performance of the BP turbine.

[0008] Another technique used to achieve a controlled clearance J, generally chosen to be as small as possible between an abradable ring 162 and the opposing wipers 152, involves creating a tolerance chain to ensure sufficient clearance during assembly to prevent any contact between the abradable ring and each of the wipers, while remaining as small as possible to avoid impacting engine performance. This tolerance chain has a large number of links, i.e., various part and tooling tolerances combined to ensure minimal clearance between the abradable ring and each of the wipers. However, using such a tolerance chain with a high number of links results in a large tolerance chain, stemming from the sum of the various tolerances. This results in significant clearance between the wipers and the abradable ring and, consequently, reduced engine performance.

[0009] There is therefore a real need for a technology that allows control of the J clearance in order to minimize the play between the spare parts used in the assembly of a BP turbine. SUMMARY OF THE INVENTION

[0010] To address the aforementioned problems of maintaining controlled clearance during the assembly of spare parts for a low-pressure turbine, the applicant proposes a spare parts assembly system that ensures concentricity of the spare parts around a common central axis. This concentricity guarantees controlled clearance between the parts, regardless of the chosen clearance width, while minimizing the number of dimensional chain links. The applicant also proposes an assembly method utilizing this system.

[0011] According to a first aspect, the invention relates to a system for mounting parts intended to form a low-pressure turbine for a turbomachine, comprising: several spare parts, including at least one housing, intended to be mounted relative to each other; a support frame for mounting the spare parts, said frame comprising: a base on which at least one housing is fixed, and a centering column, positioned substantially perpendicular to the base and central to the housing; the parts detached parts being mounted on the casing and / or on detached parts other than the casing, around the centering column, at least one comparator device mounted on at least one control axis extending between one of the detached parts to be mounted and the centering column to determine a central positioning of said detached part relative to the centering column.

[0012] This mounting system allows for the concentric positioning of one or more spare parts around the frame column. The concentric positioning of these parts around a single axis passing through the frame column ensures that the clearance between any two of these spare parts is controlled, meaning it is perfectly consistent around the entire circumference of the parts. Furthermore, this concentric positioning reduces the number of dimensional chain links compared to conventional construction systems, as all the links typically used for the central positioning of spare parts are eliminated.

[0013] A person skilled in the art will understand that no separate parts are attached to the centering column of the support frame; the column's function is to define the central axis of the low-pressure turbine, parallel to the vertical Y-axis of the XYZ coordinate system. The centering column is an integral part of the support frame (whose function is to allow concentric assembly of the parts) and is not one of the separate components that make up the low-pressure turbine.

[0014] In the following description, the parts and their assembly are described using an orthonormal XYZ coordinate system relative to the turbine's construction position, not its operating position. The turbine is constructed around the vertical Y axis of a terrestrial orthonormal XYZ coordinate system; in operation, it will be positioned around the central AA axis of an aerial turbomachinery coordinate system. Therefore, the terms "above" and "below" should be interpreted along the Y axis, and the terms "in front" and "behind" along the horizontal X axis of the XYZ coordinate system.

[0015] In addition to the characteristics mentioned in the preceding paragraph, the mounting system according to one aspect of the invention may exhibit a or several of the following additional features, considered individually or in all technically possible combinations: the spare parts comprise at least one abradable ring positioned concentrically around the centering column, the concentricity of the abradable ring being obtained by means of a comparator positioned on at least two control axes extending between the abradable ring and the centering column; the spare parts comprise at least one spacer equipped with shims, the spacer being positioned concentrically around the centering column, the concentricity of the spacer being obtained by means of a comparator positioned on at least two control axes between one of the shims of the spacer and the centering column.The spacer's shims are positioned near the abradable ring with a predefined clearance of less than 0.9 mm between said shims and said abradable ring. Several comparator devices are installed in the same plane, each comparator device being mounted on a chosen control axis extending between the spare part to be mounted and the centering column. At least two control axes extending in the same plane between the spare part to be mounted and the centering column are successively equipped with the same comparator device. At least two control axes extending in the same plane between the spare part to be mounted and the centering column are simultaneously each equipped with a comparator device. The spare parts comprise at least one housing (10), a disc assembly (120) and moving blades (110), an abradable ring assembly (162) and fixed blades (160), and a spacer (150).

[0016] Another aspect of the invention relates to a method for assembling parts intended to form a low-pressure turbine for a turbomachine, comprising the following operations:

[0017] a) Installation of a support frame comprising a base and a centering column substantially perpendicular to the base,

[0018] b) Installation and fixing of at least one housing on the base of the frame, said housing extending around the centering column,

[0019] c) Assembly and fastening of at least one first spare part onto the casing,

[0020] d) Mounting of at least one first abradable ring equipped with fixed blades around the centering column,

[0021] e) Installation of at least one comparator device on at least one control axis extending between the first abradable ring and the centering column to position said first abradable ring concentrically with respect to the centering column,

[0022] f) Securing the first abradable ring by means of a locking element,

[0023] (g) Approach of at least one spacer around the centering column, said spacer being fitted with runners,

[0024] (h) Installation of at least one comparator device on at least one control axis extending between the spacer's lugs and the centering column to position said spacer concentrically with respect to the centering column,

[0025] i) Positioning of the first spacer using a placement tool and fixing of said spacer onto a low-pressure disc,

[0026] j) Reiteration of operations d) to i) for at least a second abradable ring equipped with fixed blades and at least a second spacer.

[0027] This process offers the same advantages as the previously defined system, ultimately resulting in a reduction in the number of ribbed chain links, and therefore less play and increased engine performance.

[0028] Advantageously, the process as defined above may include one or more of the following features: the operation i) of positioning the first spacer includes a first step of radial positioning and locking of the spacer (150) and then a second step of axial positioning of said spacer, before fixing on the low pressure disc. Operations e) and h) involve installing several comparator devices on several control axes extending in the same plane between the abradable ring, or spacer, and the centering column, with one comparator device mounted on each control axis. Alternatively, operations e) and h) involve installing a single comparator device on a control axis extending between the abradable ring, or spacer, and the centering column, with this single comparator device being moved successively along several selected control axes extending in the same plane between said abradable ring, or spacer, and the centering column. Spare parts other than the housing, abradable rings, and spacers may be mounted and secured between any of steps d) and j).during operation h), the spacer is positioned concentrically to the centering column so that said spacer and the abradable ring are concentric with each other, the swats of said spacer being positioned close to the abradable ring, with a predefined clearance of less than 0.9mm between said swats and said abradable ring. BRIEF DESCRIPTION OF THE FIGURES

[0029] Other advantages and features of the invention will become apparent from the following description, illustrated by the figures in which:

[0030] Figure 1, already described, schematically represents a radial cross-sectional view of a conventional low-pressure turbine wheel;

[0031] Figure 2, already described, schematically represents a partial radial cross-sectional view of a set of moving wheels of a conventional low-pressure turbine;

[0032] Figure 3, already described, schematically represents a radial cross-sectional view of part of a low-pressure turbine during assembly, in a traditional mounting system;

[0033] Figure 4 schematically represents a radial cross-sectional view of part of a low-pressure turbine during an assembly step, with an assembly system according to the invention;

[0034] Figure 5 schematically represents a radial cross-sectional view of part of a low-pressure turbine during another assembly step, with the assembly system according to the invention;

[0035] Figure 6 schematically represents a top view of part of a low-pressure turbine during assembly, with the assembly system according to the invention;

[0036] Figure 7 schematically represents an example of a comparator device used in the system and method of the invention;

[0037] Figure 8 schematically represents a radial cross-sectional view of part of a low-pressure turbine during yet another assembly step, with the assembly system according to the invention;

[0038] Figure 9 schematically represents a radial cross-sectional view of part of a low-pressure turbine during yet another assembly step, with the assembly system according to the invention;

[0039] Figure 10 schematically represents a radial cross-sectional view of a portion of a low-pressure turbine when an abradable ring and a spacer have been fitted with the mounting system according to the invention, and

[0040] Figure 11 represents, in the form of a functional diagram, the main steps of the assembly process according to the invention. DETAILED DESCRIPTION

[0041] An example of a method and system for assembling the components intended to form a low-pressure (LP) turbine is described in detail below, with reference to the accompanying drawings. This example illustrates the features and advantages of the invention. It should be noted, however, that the invention is not limited to this example.

[0042] In the figures, identical elements are identified by identical references. For the sake of readability, the size scales between represented elements are not respected.

[0043] An example of a mounting system 20 according to the invention is partially shown in Figure 4. Figure 4 shows a longitudinal cross-sectional view of one half of the mounting system of the invention (i.e., a cross-sectional view along the XY plane of the orthonormal coordinate system XYZ), the other half of the mounting system being substantially symmetrical with respect to the Y axis. This mounting system comprises a portion of a frame 200 including a base 210 and a centering column 220. The base 210 is a support extending in a plane XZ and placed and / or fixed to the ground. The centering column 220 is a pillar mounted perpendicular to the XZ plane of the base 210 and extending along the Y axis. The centering column 220 is crossed by the Y axis. The base 210 serves as a support for the housing 10 of the BP 100 turbine on which the various spare parts of the moving wheel 101 are successively mounted.

[0044] The casing 10 is a relatively rigid elementary part of the BP 100 turbine, on which are mounted the other spare parts 102 intended to form the moving wheels 101 of the BP 100 turbine. The casing 10 is fixed to the base 210 of the frame 200 via a fixing area 15. The casing 10 has a wall 12 in the shape of approximately a truncated cone, extending between a first diameter d1 (of which only the radius ri, i.e. half of d1 is shown in figure 4) and a second diameter d2 (of which only the radius r2, i.e. half of d2 is shown), the first diameter d1 being smaller than the second diameter d2. The housing 10 is installed around the centering column 220 so that the centering column 220 is positioned in the middle of the diameters d1, d2 of the truncated cone of the wall 12 of the housing 10. The housing 10 is positioned on the base 210 so that the truncated portion of first diameter d1 is in contact with the base 210.All the spare parts 102, that is to say the spare parts necessary for the construction of the moving wheels 101 of the BP 100 turbine, are mounted one after the other on the wall of the casing 10, starting with the spare parts 102 closest to the truncated portion 10a of first diameter d1, and ending with the spare parts 102 closest to the truncated portion 10b of second diameter d2. The mounting direction of the spare parts 102 such as the abradable ring 162 or the spacer 150 is shown schematically in Figure 4 by an arrow pointing towards the -Y direction of the XYZ coordinate system. For example, the disc 120 equipped with its movable blades 110, which is closest to the truncated portion 10a of first diameter d1, is mounted first and fixed indirectly on the housing 10, that is to say by means of connecting parts. 170; indeed, the movable blades 110 are mounted on the disc 120 prior to the assembly method of the invention, that is to say outside the housing 10; the assembly of the disc 120 and movable blades 110 therefore forms a single detached part 102 when it is mounted inside the housing 10. An abradable ring 162 equipped with these fixed blades 160 is then mounted above the assembly of the disc 120 and movable blades 110; indeed, the fixed blades 160 are mounted on the abradable ring 162 prior to the assembly method of the invention, that is to say outside the housing 10; The ring 162 and fixed blades 160 thus form a single spare part 102 when mounted inside the casing 10. A spacer 150 is then mounted in front of the abradable ring 162, substantially above the disc 120.

[0045] Some of the spare parts 102, for example the casing 10, can be mounted using a method commonly used in the manufacture of LP turbines. However, other spare parts 102 are mounted according to the method of the invention so as to be concentric around the centering column 220 and therefore around the Y-axis. These other spare parts include, in particular, the moving blade assemblies 110 and disc 120, the fixed blade assemblies 160 and abradable ring 162, and the spacers 150, although the mounting method of the invention is not limited to these parts. For example, depending on the LP turbine model 100, additional spare parts or even some of the spare parts already mentioned above can advantageously be mounted concentrically with respect to the centering column.Indeed, the main advantage of the system and mounting method of the invention is that it allows for concentric mounting of at least some of the spare parts 102 around the centering column 220. Such concentric mounting allows the spare parts, which are at least partially circular in shape, to be centered around the central column 220, thus ensuring concentric positioning of said spare parts all around the Y-axis. The system and mounting method of the invention are particularly advantageous for the abradable rings 162 and the spacers 150, as the clearance between said rings and the spacer flanges 152 must be minimized without any contact between them. Since the abradable rings are, by design, floating, controlling the clearance J between these two spare parts is essential to ensure the best possible performance of the low-pressure turbine. 100. This clearance, as small as possible but without risk of contact between the parts, is called "minimum clearance" or "controlled clearance"; this minimum clearance, with the system and method of the invention, is less than 0.9mm and preferably in the order of 0.7 or 0.8mm.

[0046] In the following description, the mounting of an abradable ring 162 and a spacer 150 will be described in detail, it being understood that the abradable ring 162 is equipped with fixed blades 160 and that other spare parts of the BP 100 turbine can also be mounted using the mounting method and system of the invention. Figure 5 shows a cross-sectional view of one half of a BP 100 turbine during assembly, using the mounting method and system of the invention. Figure 6 shows a top view of a BP 100 turbine during assembly in an example of the mounting system of the invention. These Figures 5 and 6 specifically illustrate the mounting of an abradable ring 162 in an example of the mounting system of the invention. According to the method of the invention, and as explained previously, the abradable ring 162 is mounted around the centering column 220 of the frame 200 and positioned on all the spare parts 102 already installed in the frame 200.The abradable ring 162 is first positioned so that the centering column 220 is generally at the center of said abradable ring. One or more comparator devices 230 are then used to fine-tune the centering of the abradable ring 162 on the centering column 220.

[0047] An example of a comparator device 230, more simply called a comparator, is shown schematically in Figure 7. This comparator Dial indicator 230 is a device for determining both the flatness of a part 102 and the distance L between a point on the part 102 and a predetermined central point O. In Figure 7, the dial indicator 230 is shown in a first position P1 and a second position P2. When it is in position P1, the arrow 231 of the dial indicator indicates a reference position. The dial indicator 230 is moved across the surface of the part 102 to be checked; if moving the dial indicator 230 across the part 102 does not cause the arrow 231 to move, then the part 102 is flat and perfectly positioned in the XZ plane; if moving the dial indicator 230 across the part 102 causes the arrow 231 to move (see arrow positioning) 231 in position P2 in the example of figure 7), then this means that part 102 is not correctly positioned in the XZ plane and that there is an offset or difference in level The angle along the Y-axis must be corrected; the angle K between the position of arrow 231 in position P1 and the position of arrow 231 in position P2 corresponds to the difference in elevation, or slope, of part 102 between positions P1 and P2. The distance referenced L in Figure 7 is the distance to be checked. It is determined by the required accuracy in the chosen area. In the case of the invention, when the chosen area is a functional area, the distance L is checked at least four times to determine the center of the abradable ring 162 and the spacer 150.

[0048] In the application to the abradable ring 162 (or spacer), the dial indicator 230 measures the location of the center of the abradable ring (or spacer) and compares it with the predefined position of the center T of the centering column 220. If the positions of these two centers are not identical, the dial indicator 230 indicates the adjustment value to be applied to center the abradable ring (or spacer) on the center T of the centering column. A correction, or adjustment, of the positioning of the abradable ring (or spacer) can then be made, and a new comparison between the new center of the abradable ring (or spacer) and the center T of the centering column is performed. Several adjustments and comparisons (also called checks) can be carried out successively until the positions of the two centers are identical.

[0049] The centering of the abradable ring 162 is checked and / or corrected by means of at least one comparator 230 positioned on one or more axes extending between said abradable ring 162 and the centering column 220. At least three axes, called control axes, referenced Rn and distributed in the XZ plane of the XYZ coordinate system, allow the centering of the abradable ring 162 to be checked. The control axes Rn are distributed in the XZ plane at angles from the central point T of the centering column 220 that are substantially identical to each other. These angles are, for example, 120° in the case of three control axes. In one embodiment of the invention, a single comparator 230 is used for the three control axes; The comparator 230 is then moved along each of the control axes, successively, one after the other until a perfect positioning of the abradable ring is obtained.Indeed, as long as the positioning of the abradable ring is not perfect, corrections to the positioning of said abradable ring are made and centering checks are repeated using the comparator.

[0050] In another embodiment, a comparator 230 is associated with each control axis Rn. The control procedure is identical to that described above for a single comparator, except that it is not necessary to move the comparator from one control axis to another. The control is performed successively for each control axis, using the comparator associated with each control axis.

[0051] In the example shown in Figure 6, the centering control of the abradable ring 162 is performed on four control axes Ri, R2, R3, and R4, distributed angularly and regularly in the XZ plane. In this example, each control axis Ri, R2, R3, and R4 is positioned at a 90° angle to the neighboring control axes, and each control axis Ri, R2, R3, and R4 is equipped with a dial indicator 230. Equipping each control axis with a dial indicator 230 simplifies the control operations by eliminating the need to move the indicator from one axis to another.

[0052] When the centering check of the scrubbable ring 162 is complete, the scrubbable ring 162 is considered to be perfectly positioned around the centering column 220. Its positioning is then locked by means of a locking element 240. This locking element 240 can, for example, be a clamp or a screw and nut assembly. Once the locking element 240 is mounted, the scrubbable ring 162 is locked and the next spare part 102 can be mounted. In the example shown in Figure 8, the following spare part is a spacer 150. Those skilled in the art will understand that one or more other spare parts may be mounted between the assembly of the abradable ring 162 and the assembly of the spacer 150. The spacer 150 is an annular part intended to be positioned between two consecutive discs 120 of the BP turbine, in particular to ensure a connection between these two discs 120.As explained previously, the spacer 150 is equipped with sealing strips 152. For performance reasons, these strips 152 must be positioned as close as possible to the abradable ring 162, without, however, coming into contact with it, either during assembly or when the BP 100 turbine is operating. To achieve this, the method of the invention proposes mounting the spacer 150 around the centering column 220, as previously done with the abradable ring 162. Considering the same mounting center, namely the central point T of the centering column 220, the spacer 150 and the abradable ring 162 are concentric, and the risk of contact between the strips 152 and the ring is eliminated. The abradable ring 162 is zero. Therefore, once the abradable ring is mounted around the center T of the centering column 220 and locked by means of the locking element 240, the spacer 150 can be installed by lowering it into the housing 10, parallel to the centering column 220. For this purpose, the spacer 150 is supported by a positioning tool 250, also called a tamping tool, which slides along the centering column 220 until it reaches a predetermined vertical position (i.e., along the Y-axis). The positioning tool 250 used to support the spacer 150 is a known tool that will not be described in detail herein. However, this placement tool 250 is complemented by at least one comparator 230 fixed to one end 250a of said placement tool, in combination with a radial adjustment and locking device 251.This comparator 230 and its operation are identical to those of the comparator described previously for mounting the abradable ring 162. Only the location of the comparator 230 used for mounting the spacer 150 differs from that used for mounting the abradable ring 162, since it is positioned at one end of the placement tool 250, on a control axis Pn parallel to the X-axis and passing through a shim 152. For mounting the spacer 150, the comparator 230 allows checking the centering of the shims 152 of the spacer with respect to the center T of the centering column 220.

[0053] As with the abradable ring 162, the centering of the slats 152 is checked on at least three control axes distributed angularly and regularly in the XZ plane. Alternatively, the centering of the slats 152 can be checked on four control axes distributed at 90° angles to the adjacent control axes. Similarly, as with the centering of the abradable ring 162, a single dial indicator 230 can be used and mounted successively on each of the control axes, or several dial indicators 230 can be mounted, each on a control axis, thus facilitating the checking operations.

[0054] Once the centering of the slats 152, and consequently of the entire spacer 150, has been checked, the positioning of the spacer 150 is radially locked (i.e., along the X-axis) by means of the radial adjustment and locking device 251; the axial positioning of the spacer 150 (i.e., along the Y-axis) can then be undertaken using the placement tool 250, said tooling The positioning of the spacer 150 is carried out in two stages: first, a positioning with radial locking, then a positioning with axial locking. The final position of the spacer 150 relative to the abradable ring 162 is shown in Figure 9. Once in its final position, the lower end 150a of the spacer can be fixed to the disc 120 using a conventional fastening method in the field of LP turbines.Once the spacer is fixed to the disc 120, the locking element 240 of the abradable ring 162 can be removed. Once the spacer and the abradable ring are fixed and the locking element 240 is removed, the abradable ring is free to move (the concentricity of the ring with the spacer is no longer maintained).

[0055] Once the centering of the spacer 150 has been checked, and before the placement tool 250 is moved vertically, the dial indicator 230 is removed to avoid any risk of interfering with the placement of the spacer.

[0056] Figure 10 shows the mounting system 20 of the invention after the abradable ring and the corresponding spacer, the mountings of which have been described in connection with Figures 4 to 9, have been mounted and fixed onto the spare parts 102 already mounted on the housing 10, and after the tools necessary for their mounting have been removed. This Figure 10 shows a state of the structure of the BP turbine 100 during assembly: other spare parts 102, and in particular other abradable rings 162 and spacers 150, can be mounted above the structure as shown in Figure 10 in order to produce all the runners of the BP turbine.

[0057] An example of the assembly method of the invention, schematically represented as a flowchart, is shown in Figure 11. The various operations of this assembly method 300 have already been described in the description of the assembly system 200. The flowchart in Figure 11 shows an example of a sequence of operations and / or steps 301 to 311 of the assembly method 300. In this example, the method 300 comprises a first operation 301 of positioning the frame 200 with its base 210 placed and / or fixed to the ground and its centering column 220 fixed on the base 210. The centering column 220 is positioned so as to be substantially perpendicular to the base 210 and parallel to the vertical Y axis of the XYZ coordinate system. The centering column 220 is positioned substantially at the center of the frame 200 and is designed to form the central axis of the BP turbine during its construction.

[0058] The process 300 includes a step 302 for assembling the casing 10; the casing 10 is designed, on the one hand, to form the basic structure of the BP turbine under construction, i.e., the structure on which the components 102 are mounted, and, on the other hand, to constitute the protective housing of the BP turbine once its construction is complete. The casing 10 is fixed to the base 210, as explained previously.

[0059] The process 300 then includes a step 303 of mounting the first spare parts 102 onto the housing 10, such as the fixed blade 110 and the disc 120 of the first stage of the BP turbine 100. An abradable ring 162 is then positioned, as explained previously, around the centering column 220, during a step 304. Steps 305 and 306 concern the installation and use of one or more dial indicators 230, as explained previously, to check and / or adjust the centering and flatness of the abradable ring 162 relative to the centering column 220. These steps 305 and 306 also include securing the abradable ring 162 by a locking element 240 when the positioning of said abradable ring is considered to be perfectly flat and centered.

[0060] The process 300 continues with steps 307 and 308 of installing a spacer 150 around the centering column 220, as well as the placement and use of one or more comparators 230, as explained previously, to check and / or adjust the centering of the spacer and, in particular, the spacer's flanges. A step 309 then consists of centering the spacer 150 on the centering column 220 using the comparators 230, and a step 310 consists of fixing the spacer 150 onto the lower vertical disc.

[0061] Only the operations or steps specific to process 300 are shown in the flowchart in Figure 11. Other steps or operations may occur during the assembly process without altering the principle of implementation of the invention. For example, intermediate spare parts 102 may be mounted at any time before, after, or between steps 304 to 306 of assembly of the abradable ring and / or steps 307 to 310 of the spacer assembly. Similarly, intermediate tooling and / or retaining parts may be installed or removed at any step, or between any steps, of the assembly process 300 shown in Figure 11.

[0062] A test 311 then consists of verifying whether all the spare parts 102 necessary for the construction of the BP 100 turbine, and in particular whether all the discs, all the blades, all the abradable rings, and all the spacers for all the stages of the BP turbine have been correctly installed. If any spare parts need to be installed, then the procedure is repeated from step 303. If, on the other hand, all the spare parts have been installed, then the construction of the BP 100 turbine is considered complete. The frame 200 and all the tooling can then be removed. The BP 100 turbine is ready to be assembled with the other components of the turbomachine.

[0063] Although described through a number of examples, variants and embodiments, the system and assembly method according to the invention include various variants, modifications and improvements which will be obvious to a person skilled in the art, it being understood that these variants, modifications and improvements form part of the invention.

Claims

DEMANDS

1. A mounting system (20) for parts intended to form a low-pressure turbine for a turbomachine, comprising: o several spare parts (102), including at least one housing (10) having a wall (12) in the shape of a substantially truncated cone, extending between a first diameter (d1) and a second diameter (d2), the first diameter (d1) being smaller than the second diameter (d2), the spare parts being intended to be mounted relative to each other, o a frame (200) for supporting the mounting of the spare parts, said frame comprising: ■ a base (210) on which at least the housing (10) is fixed, and ■ a centering column (220), positioned substantially perpendicular to the base (210) and central to the housing (10), the spare parts (102) being mounted on the housing and / or on spare parts other than the housing, around the centering column, said centering column forming a central axis of the turbine during its construction, o at least one comparator device (230) mounted on at least one control axis (Rn) extending between one of the spare parts (102) to be mounted and the centering column (220) to determine a central positioning of said spare part relative to the centering column.

2. Mounting system according to claim 1, characterized in that the spare parts (102) comprise at least one abradable ring (162) positioned concentrically around the centering column (230), the concentricity of the abradable ring being obtained by means of the comparator device (230) positioned on at least two control axes extending between the abradable ring (162) and the centering column (220).

3. Mounting system according to claim 1 or 2, characterized in that the spare parts (102) comprise at least one spacer (150) provided with tabs (152), the spacer being positioned concentrically around the centering column (220), the concentricity of the spacer (150) being obtained by means of the comparator device (230) positioned on at least two control axes between one of the slats (152) of the spacer (150) and the centering column (220).

4. Mounting system according to claims 3, characterized in that the abradable ring (162) and the spacer (150) are concentric, the lugs (152) of said spacer being positioned near the abradable ring (162) with a predefined clearance (J) of less than 0.9 mm.

5. A mounting system according to any one of the preceding claims, characterized in that it comprises several comparator devices (230) installed in the same plane (XZ), each comparator device being mounted on a control axis (R n ) chosen extending between the spare part (102) to be mounted and the centering column (220).

6. Mounting system according to any one of claims 1 to 5, characterized in that at least two control axes (Ri, R2) extending in the same plane between the spare part (102) to be mounted and the centering column (220) are successively equipped with the same comparator device (230).

7. Mounting system according to any one of claims 1 to 5, characterized in that at least two control axes (Ri, R2) extending in the same plane (XZ) between the spare part (102) to be mounted and the centering column (220) are simultaneously each equipped with a comparator device (230).

8. Mounting system according to any one of the preceding claims, characterized in that the spare parts (102) comprise at least one housing (10), a disc assembly (120) and movable blades (110), an abradable ring assembly (162) and fixed blades (160) and a spacer (150).

9. A method (300) for assembling parts intended to form a low-pressure turbine for a turbomachine, comprising the following operations: a) Installation of a support frame (200) comprising a base (210) and a centering column (220) substantially perpendicular to the base and forming a central axis of the turbine during its construction, b) Installation and fastening of at least one housing (10) on the base of the frame, said housing extending around the centering column (220), c) Mounting and securing at least one first spare part (102) onto the housing (10), d) Mounting at least one first abradable ring (162) equipped with fixed vanes (160) around the centering column (220), e) Installing at least one comparator device (230) on at least one control axis (Rn) extending between the first abradable ring (162) and the centering column (220) to position said first abradable ring concentrically with respect to the centering column (220), f) Securing the first abradable ring (162) by means of a locking element (240), g) Approaching at least one spacer (150) around the centering column (220), said spacer being equipped with swage strips (152), h) Installing at least one comparator device (230) on at least a control axis (Rn) extending between the spacer's lugs (152) and the centering column (220) to position said spacer (150) concentrically with respect to the centering column (220),i) Positioning the first spacer (150) using a placement tool (250) and fixing said spacer (150) onto a low-pressure disc (120), j) Repeating operations d) to i) for at least a second abradable ring (162) and at least a second spacer (150).

10. Assembly method according to claim 9, characterized in that the operation i) of positioning the first spacer comprises a first step of radial positioning and locking of the spacer (150) and then a second step of axial positioning of said spacer, before fixing on the low pressure disc.

11. Assembly method according to claim 9 or 10, characterized in that operations e) and h) comprise the installation of several comparator devices (230) on several control axes (Rn) extending in the same plane (XZ) between the abradable ring (162), or the spacer (150), and the centering column (220), a comparator device being mounted on each of the control axes.

12. A method according to claim 9 or 10, characterized in that steps e) and h) involve installing a single comparator device (230) on a control axis (R n ) extending between the abradable ring (162), or the spacer (150), and the centering column (220), the single comparator device (230) being moved successively on several control axes (Ri, R2, etc.) chosen extending in the same plane (XZ) between said abradable ring, or said spacer (150), and the centering column (220).

13. A method according to any one of claims 9 to 12, characterized in that spare parts (102) other than the housing (10), the abradable rings (162) and the spacers (150) can be mounted and fixed between any of the steps d) and j).

14. A method according to any one of claims 9 to 13, characterized in that, during operation h), the spacer (150) is positioned concentrically to the centering column (220) so that said spacer and the abradable ring (162) are concentric with each other, the slats (152) of said spacer (150) being positioned close to the abradable ring (162), with a predefined clearance (J) of less than 0.9 mm between said slats and said abradable ring.

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