BE1022882B1 - IMPACT TURNING OF AXUM TURBOMACHINE COMPRESSOR BLUM BLADE END ENDS - Google Patents

Abstract

The invention relates to a method for a single-piece bladed rotor (12), known as a “BLUM®”, for a low-pressure compressor of an axial turbomachine. The method comprises the following steps: (a) forging a rough circular rotor support (12) receiving each row (22) of vanes (24); (b) machining the raw support so as to radially thin it to form a circular wall receiving several rows (22) of blades (24); (c) machining blade stubs (24); (d) welding blade blades (24) to the stumps; (e) machining the radial ends of the vanes (24) by impact turning. The machining creates rough, concentric blade heads, which improves sealing. The invention further provides a rotor (12), the blades (24) of which have tooth tops arranged on a helical or helical.

Description

Description

IMPACT TURNING OF COMPRESSOR BLUM AUBES ENDS

AXIAL TURBOMACHINE

TECHNICAL FIELD The invention relates to the manufacture of a monobloc rotor axial turbomachine. More specifically, the invention relates to a method of adjusting and retouching the blade tips of a blum® compressor. The invention also relates to an axial turbomachine.

Prior art

An axial turbomachine comprises rotors forming hubs supporting several rows of blades. A row of vanes can be secured to its hub by cutting into the rough hub. Now, the same rotor generally supports several rows of blades; as an example of three to ten for low pressure and high pressure compressors respectively. In these cases, different disks can be made and then fixed to each other. This approach requires a large number of machining, and shows difficulties related to the concentricity of the disks.

According to an alternative, it is possible to produce a support drum on which the rows of blades are welded. The support drum has an interesting circularity. However, this solution does not ensure a required concentricity and / or circularity at the outer ends of the blades. Indeed, a blade welding process induces variations of blade positions. These variations are penalizing and must be corrected to ensure optimal operation with the outer casing, and in particular with its abradable seals.

US 2010/0175256 A1 discloses a method of retouching the outer ends of the vanes of a rotor. The rotor corresponds to an axial turbomachine rotor with several rows of vanes. The method provides retouching blade tips by milling, which allows to form rows of blades by controlling the circularity of the blade heads. However, this process is long because it requires careful machining. It is carried out with a tool of specific shape, whose life time is reduced because of its size. This increases the production costs of the corresponding rotor. Summary of the invention

TECHNICAL PROBLEM The invention aims to solve at least one of the problems posed by the prior art. More specifically, the invention aims to reduce the time required to improve the circularity of a row of vanes of a rotor. The invention also aims to simultaneously optimize the manufacturing costs of a bladed rotor and the circularity of the blade rows of a rotor.

TECHNICAL SOLUTION The subject of the invention is a method for manufacturing a rotor of an axial turbomachine, in particular a low-pressure compressor rotor, the rotor comprising at least one annular row of radially extending rotor blades, remarkable in that it comprises a step (e) machining the radial ends of the blades by turning.

According to an advantageous embodiment of the invention, the step (e) machining of the ends is a finishing step of the surfaces of the free ends of the blades which are oriented radially outwards.

According to an advantageous embodiment of the invention, during the step (e) machining of the ends, machining is performed using a cutting tool movable in translation and fixed in rotation relative to the lathe.

According to an advantageous embodiment of the invention, during the step (e) machining of the ends, the cutting speed is between 30 m / s and 150 m / s; preferably between 40 m / s and 70 m / s, possibly equal to 50 m / s.

According to an advantageous embodiment of the invention, during step (e) machining of the radial ends of the blades, the advance per revolution and / or the depth of pass is between 0.01 mm and 1.00 mm, preferably between 0.05 mm and 0.30 mm.

According to an advantageous embodiment of the invention, the method further comprises a step (a) forging a crude circular rotor support for receiving at least one or each row of blades.

According to an advantageous embodiment of the invention, the method further comprises a step (b) machining of the raw support so as to thin, possibly radially, a circular wall, in particular for receiving at least one row of blades. According to an advantageous embodiment of the invention, the method further comprises a step (c) machining blade stubs in the raw support.

According to an advantageous embodiment of the invention, the method further comprises a step (d) blade blades welding on the rotor, optionally on the stubs so as to form blades.

According to an advantageous embodiment of the invention, during step (d) blade welding, the welding is a friction welding, preferably an orbital welding.

According to an advantageous embodiment of the invention, the maximum outer diameter of the rotor is between 0.50 m and 1.50 m, preferably between 0.70 m and 1.10 m.

According to an advantageous embodiment of the invention, at least one or each blade has a thickness of less than 10.00 mm, preferably less than 5.00 mm, more preferably less than 3.00 mm, possibly less than 2.00 mm, or less than 1.00 mm. Optionally, the thickness is the average thickness.

According to an advantageous embodiment of the invention, at least one or each blade is higher radially than long axially, possibly at least twice. According to an advantageous embodiment of the invention, at least one or each blade has a general shape of rectangle, possibly twisted, and / or curved, and / or concave. The invention also relates to an axial turbomachine rotor, in particular an axial turbomachine compressor, comprising at least one annular row of rotor blades, each blade having a leading edge, a trailing edge; an intrados surface, and an extrados surface extending from the leading edge to the trailing edge, a free outer radial end surface joining the intrados surface to the extrados surface, characterized in that the radial ends of the blades present a roughness greater than the roughness of the intrados surfaces and / or the extrados surfaces of the blades. The roughness aspect is not essential to the invention, it can be replaced by at least one of the following advantageous modes. According to an advantageous embodiment of the invention, the ends of the blades of at least one or each row having teeth evenly spaced axially on the same blade and on each blade of the same row.

According to an advantageous embodiment of the invention, the ends of the blades have teeth profiled according to the circumference of the rotor, the teeth of at least one row of blades being generally aligned along the circumference of the rotor, and / or the teeth of the rotor. at least one row of vanes are arranged on a helical path.

According to an advantageous embodiment of the invention, the tips of the teeth of the blades of at least one or each row are arranged on a helical and / or a helical curve.

According to an advantageous embodiment of the invention, the rotor comprises several annular rows of blades, the support and the blades being made of titanium or titanium alloy.

According to an advantageous embodiment of the invention, the rotor is a drum with a radial attachment flange; and / or an annular partition having an increase in diameter and overall thickness, especially upstream.

According to an advantageous embodiment of the invention, the rotor forms a one-piece assembly with its blades.

According to an advantageous embodiment of the invention, the roughness Ra of the blade tips is greater than 3 μm, preferably greater than 5 μm, more preferably greater than 12 μm.

According to an advantageous embodiment of the invention, the rotor is a disc essentially comprising an annular row of vanes.

According to an advantageous embodiment of the invention, the pitch of the helix and / or of the helicoid is between 0.01 mm and 1.00 mm, preferably between 0.05 mm and 0.30 mm. The invention also relates to a turbomachine comprising at least one rotor manufactured according to a manufacturing method, remarkable in that the rotor is in accordance with the invention, and / or the rotor is manufactured according to a method according to the invention.

In general, the advantageous modes of each object of the invention are also applicable to the other objects of the invention. As far as possible, each object and each advantageous mode are combinable.

Advantages The invention makes it possible to produce blade tips that respect a particularly careful radial height. In this way, the functional clearances between the blade heads and the abradable ones can be reduced, which limits the leakage at the blade heads during the rotation of the rotor. Thus, the dynamic seal increases, as the performance of the turbomachine.

The choice of a cutting speed of order 50 m / s; or at least less than 500 m / s, preferably less than 200 m / s, limits the vibrations in the rotor. The latter would result in oscillations degrading the respect of the machining dimension, and the desired rendering. The choice of the cutting speed favors a certain cutting mode; or tearing chips; which makes the surfaces free of the blades rougher. In operation, the roughness limits leaks in blade heads and further improves the sealing. Reducing the cutting speed limits the rotational speed of the rotor. In corolla, the energy to rotate the rotor decreases as the hydraulic resistance against the blades decreases.

The benefits are also achieved thanks to the arched blade profiles, which limit their deformation due to cutting forces. The wedge angle of the blades also has an influence.

Brief description of the drawings

FIG. 1 represents an axial turbomachine according to the invention.

FIG. 2 is a diagram of a turbomachine compressor according to the invention.

Figure 3 outlines a tower on which is machined a rotor according to the invention.

Figure 4 outlines a diagram of the method of manufacturing a rotor according to the invention.

Description of the embodiments

In the following description, the terms inner or inner and outer or outer refer to a positioning relative to the axis of rotation of an axial turbomachine. The axial direction corresponds to the direction along the axis of rotation of the turbomachine.

FIG. 1 is a simplified representation of an axial turbomachine. It is in this case a double-flow turbojet engine. The turbojet engine 2 comprises a first compression level, called a low-pressure compressor 4, a second compression level, called a high-pressure compressor 6, a combustion chamber 8 and one or more levels of turbines 10. In operation, the mechanical power the turbine 10 transmitted via the central shaft to the rotor 12 sets in motion the two compressors 4 and 6. The latter comprise several rows of rotor blades associated with rows of stator vanes. The rotation of the rotor around its axis of rotation 14 thus makes it possible to generate an air flow and to compress it progressively until it reaches the combustion chamber 8. Reducing means can increase the speed of rotation transmitted. compressors.

An inlet fan commonly referred to as a fan or blower 16 is coupled to the rotor 12 and generates an air flow which splits into a primary flow 18 passing through the various aforementioned levels of the turbomachine, and a secondary flow 20 passing through an annular duct ( partially shown) along the machine to then join the primary flow at the turbine outlet. The secondary flow can be accelerated to generate a thrust reaction. The primary 18 and secondary 20 streams are annular flows, they are channeled by the casing of the turbomachine. For this purpose, the casing has cylindrical walls or ferrules which can be internal and external.

FIG. 2 is a sectional view of a compressor of an axial turbomachine such as that of FIG. 1. The compressor can be a low-pressure compressor 4. There can be seen a part of the fan 16 and the separation nozzle primary flow 18 and secondary flow 20.

The rotor 12 is here shown in section, only half is visible. It comprises several rows 22 of rotor blades 24, in this case three. The rotor 12 of the compressor has a drum shape, it has a central recess for shaft passage and the integration of the bearing. The annular wall, which may be generally tubular, supports the rows of blades 22. The drum forms a one-piece assembly with blades 24. Such a rotor 12 is also known by the name of BLUM® 12 for the contraction of the English expression " bladed drum ".

The low pressure compressor 4 comprises several rectifiers, in this case four, each containing a row of stator vanes 26. The rectifiers are associated with the fan 16 or a row of rotor vanes to straighten the flow of air, so as to convert the speed of the flow into static pressure. The stator vanes 26 extend substantially radially from an outer casing, and can be attached thereto by means of an axis. They are regularly spaced from each other, and have the same angular orientation in the flow. Advantageously, the blades of the same row are identical. Optionally, the spacing between the blades may vary locally as well as their angular orientation. Some blades may be different from the rest of the blades in their row.

Figure 3 shows a rotor 12 of low pressure compressor disposed on a digital lathe 28 for machining the radially outer faces of the ends of its blades.

The lathe 28 comprises a mandrel 30 holding the rotor 12 from the inside, and allowing it to be rotated in order to machine it. The mandrel 30 may comprise jaws (not shown) expandable to clamp against the rotor 12. Wedges may be added between the mandrel and the rotor 12 to not deform during tightening.

The lathe 30 may comprise a carriage 32 on which is fixed a cutting tool 34. A machining plate, for example ceramic such tungsten carbide, may be adapted to machine the titanium alloy rotor blades 24. This material can match that of the drum. The carriage 32 is movable in translation relative to the frame of the lathe 28; both parallel and perpendicular to the axis of rotation of the lathe. This axis coincides naturally with the axis 14 of the rotor 12. A programming unit moves the tool 34 along the desired profile of the surface of the envelopes of the rows 22 of blades. A tailstock may be employed in the case of an elongated and narrow rotor, for example for a high pressure compressor with ten rows 22, or more.

To perform the machining of the rows of blades, the rotor 12 is rotated and the tool 34 is brought closer to the blades. It cuts the blades 24 one after the other by removing a chip at each contact. The tool hits the blades one after the other while advancing axially and radially. The lathe then performs impact machining. The result is that the ends of the blades of a row 22 have portions of a helical surface. The pitch of the helix corresponds to the advance per revolution of the tool.

FIG. 4 shows a diagram of the manufacturing process of the turbomachine bladed rotor.

The method comprises the following steps, possibly carried out in the following order: (a) - Forging 100 of a raw circular rotor support receiving each row of blades. (b) - Machining of the raw support 102 so as to thin it, possibly radially. The machining makes it possible to form a circular wall, such as a circular web intended to receive at least one row of blades. (c) - Machining stubs 104, or blade roots, in the thickness of the circular wall. (d) - Welding 106 blade blades on the stubs. (e) - Machining the free radial ends of blades 108 by impact turning. (f) - Measurement of the circularity and / or concentricity 110 of the outer radial surfaces machined at the heads of blades above. Step (a) forging 100 makes it possible to form a crude circular rotor support. In a solid and solid piece, a hot recess is progressively made. An ogive tube with a central cavity takes shape. This operation can make it possible to make a through hole.

Then, the method performs the step (b) machining of the raw support 102 so as to thin radially on its generally tubular portion. Some areas may have thicknesses less than 20 mm, or less than 5 mm; possibly less than 2.50 mm or 2.00 mm, or 1.80 mm. The aforementioned thicknesses can form finite axial sections, or areas for stubs. This step also makes it possible to machine sealing strips, Greek letter forms Pi: π, radial stiffeners, internal leeks.

Optionally, the method comprises a step (c) machining blade stubs 104 in the raw support. The annular areas in extra thickness are cut by milling to remove plates, arcs of materials. According to a variant of the invention, the vanes can be integrally formed by milling from the zones in super-thicknesses. These can then comprise thicknesses greater than or equal to 4 cm, preferably greater than 8 cm, more preferably greater than 15 cm.

Optionally, the method comprises a step (d) of blade blade welding 106 on the stubs so as to form blades. The welding can be friction welding; for example an orbital welding. The step (e) machining of the ends 108 is a finishing step of the free ends of the blades, or final stage concerning them. During the step (e) machining of the ends 108, the machining is performed using a cutting tool movable in translation along the axis of rotation of the lathe, and perpendicular to the same axis. During the step (e) machining 108, the tool generally retains its orientation; and / or performs less than one turn. The cutting speed is of the order of 50 m / s, which offers a compromise between the speed of the machining, the vibrations, the state of surface. Step (f) measures 110 is optional. In case of non-compliance the method may provide for performing a machining step; having a corrective function. This step can be used to terminate the process; for example if the rotor is compliant.

Claims (20)

claims 1. A method of manufacturing a rotor (12) of an axial turbomachine (2), in particular a low-pressure compressor rotor (4), the rotor (12) comprising at least one annular row (22) of rotor blades (24) extending radially, characterized in that it comprises a step (e) machining the ends (108) radial blades (24) by turning. 2. Method according to claim 1, characterized in that the step (e) machining of the ends (108) is a finishing step of the surfaces of the free ends of the blades (24) which are oriented radially outwardly. 3. Method according to one of claims 1 to 2, characterized in that during the step (e) machining of the ends (108), machining is performed using a cutting tool (34) movable in translation and fixed in rotation relative to the turn (28). 4. Method according to one of claims 1 to 3, characterized in that during the step (e) machining of the ends (108), the cutting speed is between 30 m / s and 150 m / s; preferably between 40 m / s and 70 m / s, possibly equal to 50 m / s. 5. Method according to one of claims 1 to 4, characterized in that during the step (e) machining the ends (108) of the radial blades (24), the advance per turn and / or the depth of pass is between 0.01 mm and 1.00 mm, preferably between 0.05 mm and 0.30 mm. 6. Method according to one of claims 1 to 5, characterized in that it further comprises a step (a) forging (100) a crude circular rotor support for receiving at least one or each row (22). ) of blades (24). 7. Method according to one of claims 1 to 6, characterized in that it further comprises a step (b) machining (102) of the raw support so as to thin, possibly radially, a circular wall, in particular for receiving at least one row (22) of blades (24). 8. Method according to one of claims 1 to 7, characterized in that it further comprises a step (c) machining (104) blade stubs (24) in the raw support. 9. Method according to one of claims 1 to 8, characterized in that it further comprises a step (d) welding (106) blade blades on the rotor (12), optionally on the stubs so as to forming vanes (24). 10. The method of claim 9, characterized in that during step (d) welding (106) blades, the welding is a friction welding, preferably an orbital welding. 11. Rotor (12) for axial turbomachine (2), in particular an axial turbomachine compressor (4; 6), comprising at least one annular row (22) of rotor blades (24), each blade (24). having a leading edge, a trailing edge; an intrados surface and an extrados surface which extend from the leading edge to the trailing edge, a free outer radial end surface joining the intrados surface to the extrados surface, characterized in that the radial ends of the blades ( 24) have a roughness greater than the roughness of the intrados surfaces and / or the extrados surfaces of the vanes (24). 12. Rotor (12) according to claim 11, characterized in that the ends of the blades (24) of at least one or each row (22) have regularly spaced teeth axially on the same blade (24) and on each blade (24) of the same row (22). 13. Rotor (12) according to one of claims 11 to 12, characterized in that the ends of the blades (24) have teeth profiled according to the circumference of the rotor (12), the teeth of at least one row (22). ) blades (24) are generally aligned along the circumference of the rotor (12), and / or the teeth of at least one row (22) of blades (24) are arranged on a helical path. 14. Rotor (12) according to claim 13, characterized in that the tops of the teeth of the blades (24) of at least one or each row (22) are arranged on a helicoid and / or a helical curve. 15. Rotor (12) according to one of claims 11 to 14, characterized in that it comprises several annular rows (22) of blades (24), the support and the blades (24) being made of titanium, or made of titanium alloy. 16. Rotor (12) according to one of claims 11 to 15, characterized in that it is a drum with a radial attachment flange; and / or an annular partition having an increase in diameter and overall thickness, especially upstream. 17. Rotor (12) according to one of claims 11 to 16, characterized in that it forms a one-piece assembly with its vanes (24). 18. Rotor (12) according to one of claims 11 to 17, characterized in that the roughness Ra of the blade ends (24) is greater than 3 microns, preferably greater than 5 microns, more preferably greater than 12 microns. 19. Rotor (12) according to one of claims 11 to 18, characterized in that it is a disc comprising essentially an annular row of vanes (24). 20. Turbomachine (2) comprising at least one rotor (12) manufactured according to a manufacturing process, characterized in that the rotor (12) is according to one of claims 1 to 10, and / or the rotor (12) is manufactured according to a process according to one of claims 11 to 19.