Method for modelling the joining of a blade to a turbine engine rotor stub by orbital welding

Abstract

The invention relates to a method for modelling the joining (10) of a blade (4) to a stub (6) on a turbine engine rotor (2), by orbital-friction welding, which comprises the following step: determining a material consumption rate VCA as a function of the following orbital-friction welding parameters: eccentricity, frequency and pressure, and of a geometric parameter z of the section of the blade and of the stub at the junction; characterised in that the method further comprises the following step: determining a maximum thickness e max of the junction as a function of the determined material consumption rate VCA, the geometric parameter z being an average of the mean radii z sweeping across the section at the junction at any point i of the periphery of said section.

Description

METHOD FOR MODELING A BLADE JUNCTION TO A TURBOMACHINE ROTOR STUMP BY ORBITAL WELDING

[0001] The invention relates to a method for modeling a blade junction to a turbomachine rotor, and more particularly to a method for modeling a junction obtained by orbital friction welding of a blade to a stub on a turbomachine rotor. Prior art

[0002] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various carbon emission restrictions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new aircraft types and those already in operation, requiring the implementation of technological solutions to comply with current regulations. Civil aviation has been mobilizing for several years now to contribute to the fight against climate change.

[0003] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0004] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0005] This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as an essential complement to technological progress, aeronautical biofuels.

[0006] To this end, the invention is the result of technological research aimed at significantly improving aircraft performance and, in this sense, contributes to reducing the environmental impact of aircraft.

[0007] In this context, the invention relates to a method of modeling and orbital friction welding for producing a bladed disc (commonly referred to as "blisk") or a bladed drum (commonly referred to as "blum") for a turbomachine compressor.

[0008] Orbital friction welding is a welding process in which the parts to be joined are brought into contact under stress and welded by a circular motion generally defined by an eccentric, and accompanied by a uniform tangential speed, so as to generate friction and homogeneous heating at a weld junction between the two parts.

[0009] Linear friction welding is also known to be used, a welding process in which the necessary heat is created by a back-and-forth movement of the interfaces to be welded. However, orbital friction welding has several advantages over linear friction, for example, the relative movement between the two interfaces is continuous thanks to the circular friction movement, which provides better thermal homogeneity. Unlike linear movement for which the relative speed of the two parts becomes zero at each half-oscillation period. In addition, the cycle time of orbital welding is considerably lower than that of linear friction welding (respectively approximately 2 minutes compared to approximately 5 minutes).

[0010] Published patent document EP 2 535 516 A1 discloses a method of orbital friction welding of blades to a turbomachine rotor in which, once a material consumption is reached in a welding zone between the blade and the disc, the orbital movement is stopped at a reference position, and a forging force is exerted on the blade against the rotor in order to form the weld.

[0011] After welding, progressive machining adapting to the external surface of the blade is then carried out in order to remove the material from the interface which will have been pushed outwards during welding (commonly referred to as: "flash"), so as to avoid any projection linked to machining.

[0012] However, post-weld machining may reveal a weld junction of the blade with the rotor disc which may have structural defects and / or material health defects.

[0013] Published patent document EP 2 409 807 A2 discloses a method for manufacturing combined profiled blades and discs, in which each of the blades has a stub to be welded to the disc by linear friction. The document proposes a modeling of the linear welding process including an estimation of the material consumption rate "BOR" based on widths of the stub section measured along a linear oscillation direction.

[0014] However, the welding process disclosed by the document is related to linear friction welding and is not compatible with orbital welding, as it does not allow for accurate modeling of the orbital welding process to control the radial position of the welding zone and to obtain a welded joint that is sound and free from contaminants.

[0015] The invention aims to solve at least one of the problems posed by the prior art. More specifically, the invention aims to propose a solution making it possible to accurately model an orbital friction welding process of a blade to a rotor disk stub.

[0016] The invention is the result of technological research aimed at significantly improving aircraft performance and, in this sense, contributes to reducing the environmental impact of aircraft. For this purpose, the present invention relates to a method for modeling a blade junction to a stub on a turbomachine rotor, by orbital friction welding, comprising the following step:

[0017] determination of a material consumption rate VCA as a function of the following orbital friction welding parameters: eccentricity, frequency and pressure, and a geometric parameter of the blade and stub section at the junction;

[0018] remarkable in that the method further comprises the following step:

[0019] determination of a maximum thickness max of the junction as a function of the determined material consumption rate VCA, the geometric parameter z being an average of the mean radii z i scanning the section of the blade and the stub at the junction at any point on the periphery of said section.

[0020] Advantageously, the pressure comprises a forging pressure and / or a pressure applied during an orbital movement of the orbital friction weld.

[0021] According to an advantageous embodiment of the invention, the maximum thickness maxdetermined and the material consumption rate VCA determined are all the greater as the geometric parameter z is small and vice versa.

[0022] According to an advantageous embodiment of the invention, the average rays i sweeping the section of the blade and the stub at the junction at any point on the periphery of said section are strictly contained within said section.

[0023] According to an advantageous embodiment of the invention, the average rays i sweeping the section of the blade and the stub at the junction at any point on the periphery of said section completely sweeps said section.

[0024] According to an advantageous embodiment of the invention, the maximum thickness max determined and the determined material consumption rate VCA are smaller as the eccentricity decreases and vice versa.

[0025] According to an advantageous embodiment of the invention, the maximum thickness maxdetermined and the determined material consumption rate VCA are smaller as the frequency decreases and vice versa.

[0026] According to an advantageous embodiment of the invention, the determination of the maximum thickness max and the material consumption rate VCA is based on experimental orbital friction welding data, where for each welding operation the material consumption rate VCA is measured and correlated with the eccentricity, frequency, pressure and geometric parameter z.

[0027] According to an advantageous embodiment of the invention, the correlations of the experimental data are made in such a way as to provide a model for determining the rate of consumption of material VCA and possibly the maximum thickness max .

[0028] According to an advantageous embodiment of the invention, the model for determining the material consumption rate VCA and possibly the maximum thicknessmax involves the use of artificial intelligence.

[0029] The invention also relates to a method of orbital friction welding a blade to a stub on a turbomachine rotor to form a junction, comprising the following step:

[0030] determination of a material consumption rateVCA;

[0031] characterized in that the method further comprises the following step:

[0032] determination of a maximum thickness max of the junction as a function of the determined material consumption rate VCA and as a function of a geometric parameter z corresponding to an average of the average radii z i scanning the section of the blade and the stub at the junction at any point on the periphery of said section.

[0033] Advantageously, determination of the material consumption rate VCA corresponds to a measurement on the machine and / or the tool performing the orbital welding. Preferably, the determination of the maximum thickness max of the joint is also a function of the following orbital friction welding parameters: eccentricity, frequency and forging pressure, said parameters being determined by measurement on the machine and / or tooling performing the orbital welding.

[0034] According to an advantageous embodiment of the invention, the welding method further comprises a step of comparing the maximum thickness max determined with an interval of values ​​of the maximum thickness max predefined during a modeling process of the blade junction to the stub, said modeling process being according to the invention.

[0035] The invention also relates to a method for dimensioning a blade and a corresponding stub on a turbomachine rotor, intended to be joined by orbital friction welding, according to a maximum thickness. max of the predetermined junction, remarkable in that the sizing method includes an iteration of determining the maximum thickness max of the junction according to different dimensions of the junction, following a modeling method according to the invention.

[0036] According to an advantageous embodiment of the invention, the iteration of determining the maximum thickness max of the junction according to different dimensions of the junction is carried out while the eccentricity, frequency and pressure remain constant. Preferably, the pressure includes the pressure applied during the orbital movement and the forging pressure.

[0037] According to an advantageous embodiment of the invention, the different dimensions of the junction, in the iteration of determining the maximum thickness max of the junction, are selected to correspond to different values ​​of the geometric parameter z.

[0038] According to an advantageous embodiment of the invention, the iteration of determining the maximum thickness max of the junction following different dimensions of the junction is stopped when the maximum thickness max determined corresponds to the maximum thickness max of the predetermined junction with a given tolerance.

[0039] The measures of the invention are particularly advantageous in that the determination of the material consumption rate VCA, in particular as a function of the geometric parameter of the junction section, makes it possible to ensure an efficient and precise estimation of the maximum thickness. max of said junction.

[0040] Modeling the junction by determining its maximum thickness max , allows, from the design stage, to define an optimal dimensioning of the radial extents of the blades and the stubs so as to guarantee an optimal radial position of a welding plane of the junction before orbital welding. In addition, the contact section presented between the blades and the stubs is also dimensioned by means of a robust process so as to ensure homogeneity of the mixing of the material and thus obtain a healthy welded junction free of defects.

[0041] It is understood that each detail of an embodiment below may be combined with each other detail of the other embodiments.

[0042] Schematically illustrates a side view of a blade joined to a stub extending radially from a turbomachine rotor, having an orbital friction welded joint comprising a maximum thickness maxdetermined by a junction modeling method according to the invention;

[0043] Illustrates schematically a section of the blade and / or stump at the junction visible at the ;

[0044] Illustrates the junction section of the when determining an average radius A scanning said section from a point A on the periphery of said section;

[0045] Illustrates the junction section of the when determining an average radius B scanning said section from a point B on its periphery;

[0046] Illustrates a mapping of the amplitude of the average rays i sweeping the junction section at every point of its periphery;

[0047] Illustrates the joint section of the showing three marks for taking measurements of the maximum thickness of the welded joint, with two of these joint sections identical;

[0048] The is a first graph representing the evolution of the estimated thickness of the welded joint compared to actual measurement points of said thickness, following a local width of the junction section of the, and to a first reference positioned at 1 / 4 of a total extent of said section;

[0049] The is a second graph representing the evolution of the estimated thickness of the welded joint compared to actual measurement points, following a local width of the junction section of the, and to a second reference point positioned at half the total extent of said section;

[0050] There is a third graph representing the evolution of the estimated thickness of the welded joint compared to actual measurement points, following a local width of the junction section of the, and to a third mark positioned at 3 / 4 of the total extent of said section. Detailed description of the embodiments

[0051] In the following description, the terms "internal" and "external" 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, with lengths being measured axially. Widths are measured circumferentially. The radial direction is perpendicular to the axis of rotation. Upstream and downstream refer to the main flow direction of the flow in the turbomachine.

[0052] The dimensions of the figures are not to scale and in particular the thicknesses or radial dimensions are exaggerated to facilitate reading of the figures.

[0053] Schematically illustrates a side view of a blade 4 joined to a stub 6 extending radially from an outer surface 8 of a turbomachine rotor 2, having a junction 10 welded by orbital friction comprising a maximum thickness maxdetermined by a junction modeling method according to the invention.

[0054] It can be observed that the junction 10 has a diabolo or butterfly shape, with a wider peripheral end (along the radial direction) than its inner central part, this is due to a concentration of the excess material displaced during orbital welding. For this purpose, the maximum thickness max is measured at the peripheral end of junction 10.

[0055] The present invention proposes a modeling method and a method of dimensioning the blades 4 and the stubs 6 so as to allow the manufacture of a bladed disc for a turbomachine.

[0056] Preferably, the bladed disc is a mobile wheel intended to be arranged upstream of an air flow separation nozzle in a turbomachine. For this purpose, the external surface 8 corresponds to an air guide surface of a fluid stream along the turbomachine. Alternatively, the bladed disc may correspond to a drum-type rotor belonging to a high-pressure or low-pressure compressor.

[0057] Preferably, the bladed disc is a so-called “bi-material” disc comprising two different titanium alloys. For example, the blades 4 can be manufactured from a Ta6v alloy, and the rotor disc 2 from one of the following alloys: Ti17, Ti575, Ti1023.

[0058] Advantageously, the mixture of the two different titanium alloys (Ta6v and Ti17) presents easier machinability, and makes it possible to achieve a gain in mass compared to a solution based, for example, solely on a Ti17 alloy, this is notably due to a density of Ta6v which is slightly lower than that of Ti17.

[0059] Indeed, the Ti17 alloy was preferentially chosen for the disc part for its good HCF (High Cycle Fatigue) and LFC (Low Cycle Fatigue) fatigue characteristics. A Ti17 disc will also display a greater margin in burst speed than a Ta6v disc. For the blades, the Ta6v alloy was chosen because it provides the blades with a higher elongation at break (better impact resistance), and better crack propagation behavior which results in better durability in low energy impacts.

[0060] It can be seen that the junction 10 comprises a weld plane 10.1 illustrated in a central position relative to the maximum thickness max of said junction 10.

[0061] Advantageously, the determination of the e max makes it possible to control the radial position h of the welding plane 10.1 from the external surface 8 of the rotor 2, as well as to dimension the radial extent of the blade 4 and the stub 6, prior to the manufacture of the bladed disc.

[0062] In this regard, the method of modeling the junction 10 comprises a step of determining the maximum thickness max as a function of a material consumption rate VCA (which can be expressed in mm / s) which is presented at the contact interface between the blade 4 and the stub 6 during orbital friction welding.

[0063] The method of the invention makes it possible to determine the material consumption rate VCA analytically by an estimation as a function of a geometric parameter z of the section of the blade 4 and the stub 6 at the junction 10, and also as a function of the following orbital friction welding parameters: eccentricity (corresponding to the eccentricity of the orbital oscillation movement during welding); frequency (oscillation speed); and the pressure applied during the maximum axial consumption phase during the orbital movement. Advantageously, the welding parameters can be predefined as input setpoints on a welding machine prior to the execution of said welding.

[0064] The section of the blade 4 and the stub 6 at the junction 10 preferably corresponds to a flat section. Each stub 6 of the disc and the corresponding blade 4, which are intended to be welded by orbital friction, have an identical junction section.

[0065] Preferably, the analytical estimation of the material consumption rate VCA is based on experimental orbital friction welding data, for example by means of test specimens using the same orbital welding parameters, where for each welding operation the actual VCA speed is measured and correlated with the eccentricity, frequency, forging pressure and geometric parameter z. Preferably, by means of artificial intelligence. Thus, a model for determining the VCA speed can be defined.

[0066] It has been established that the maximum thickness maxand the determined material consumption rate VCA are all the greater as the geometric parameter z is small and as the eccentricity and / or frequency increases and vice versa.

[0067] Advantageously, the maximum thickness max determined by means of the modeling method of the invention makes it possible, prior to orbital welding, to control the radial position h of the welding plane 10.1, and thus to dimension the radial extent of each of the blade 4 and the stub 6.

[0068] Illustrates schematically the section 11 of the blade 4 and / or the stub 6 at the weld junction 10 visible in the. Preferably, the section 11 is identical for the blade 4 and for the stub 6 of the rotor 2.

[0069] Section 11 is modeled from an aerodynamic profile 4.1 of the blade 4, preferably, the latter includes a section widening by means of an excess thickness corresponding, more preferably, to the eccentric of the orbital oscillation movement during welding. The eccentric corresponds to the offset value of the tool (for holding the blade) and the disc relative to a reference center, making it possible to create the orbital oscillation movement. In other words, the eccentric corresponds to the distance between the axis of rotation of the tool and the central point around which it performs its orbital movement.

[0070] However, the excess thickness is not necessarily constant around profile 4.1; it may present variations around said profile 4.1.

[0071] It should be noted that prior to orbital friction welding, a sacrificial volume of material (extending essentially radially) is provided on each of the blades 4 and stubs 6 to be assembled. This sacrificial volume is caused to be extruded outside the contact interface between the sections 11, thus forming a burr, commonly referred to as: "flash", which will then be eliminated, to reach the profile 4.1 of the blade. However, non-homogeneous ejection of the flash along the periphery of the section to be welded risks causing the recirculation of local material inside the section to be welded and may prevent complete ejection of the contaminants created at the first moments of the weld and risks creating recesses in the welded joint, which is detrimental to the quality of the weld.

[0072] Advantageously, the widening of the contact section makes it possible to avoid the recirculation of the material (potentially harmful because it prevents the evacuation of impurities) towards narrower regions of the section of the final aerodynamic profile 4.1 of the blade and thus to ensure thermal homogeneity during welding, precisely in the final section 4.1 of the blade 4. Indeed, if we add an excess thickness at least equal to the value of the eccentric, this means that the points of the final aerodynamic surface 4.1 are always in contact during welding (between the stub and the blade). Unlike the points in this excess thickness which, by the orbital movement, are in contact with the opposite surface only during a part of the orbital oscillation movement.

[0073] Thus, during welding, at section 11, the resulting local VCA speeds are more homogeneous, which allows the blade profile 4.1 to be preserved more and a stronger joint to be obtained.

[0074] The modeled section 11 allows to determine the geometric parameter z. Indeed, z is an average of the average radii z i sweeping section 11 at every point of its periphery 11.1.

[0075] Each of the average rays i corresponds to an average length i of rays i,α extending entirely in the section 11 from a point i at the periphery 11.1 and sweeping said section 11. Preferably, the rays z i,α correspond to projections of the point on an entire portion of the periphery 11.1 which is opposite said point.

[0076] Advantageously, the evolution of the average rays ion the periphery of the section 11 to be welded physically represents the homogeneity of the length to be sheared during rotation (orbital movement during welding) and therefore the homogeneity of the material flow expelled in the flash along the contour of the blade. It is representative of the homogeneity of contaminant ejection from the weld.

[0077] In this regard, the determination of the geometric parameter z includes the determination of the mean radius z i for the plurality of points on the entire periphery 11.1.

[0078] Preferably, the determination of the geometric parameter is an automated process using a computer algorithm. In this respect, an algorithm applying a “ray tracing” type method can be adapted, the latter also being known under the English name “ray tracing”.

[0079] Advantageously, the inventors have wisely adopted an innovative approach by introducing the ray tracing technique, which is hitherto unknown in the field of mechanics. They realized that this is the optimal way to characterize the joint section intended for orbital friction, in order to arrive at a more accurate estimate of the material consumption rateVCAand therefore of the radial position (height) of the weld, and this prior to the orbital welding operation.

[0080] The ray tracing method on section 11 can be performed using the following steps:

[0081] - model a first section 11 (visible in) based on the final aerodynamic profile 4.1 of the blade with the addition of the overthickness (which shares the same value as that of the eccentric which is planned to be applied to the tool during orbital welding); and

[0082] - divide the periphery 11.1 evenly into several pointsi from which the raysz i,α will be projected, preferably at around 2000 points distributed evenly (this number may vary depending on the desired calculation precision); and

[0083] - project rays i,α which sweep the entire section 11 from a first point on the periphery 11.1, the number of rays z i,α projected preferentially depends on an angle α between 0.001° and 10°; and

[0084] - measure the average length i of all rays i,α projected from the first point; and

[0085] - repeat the ray projection step i,α as well as that of the measurement of the average length i , successively for all points on the periphery 11.1; and

[0086] - calculate the average length of all average lengthsz imeasured from each of the total points to arrive at the geometric parameter of the junction section.

[0087] Figures 3 and 4 illustrate an example of ray projectionz A,α etz B,α , respectively, from points A and B of the periphery 11.1.

[0088] These are two schematic examples of determining the average length i of all rays i,α using the ray tracing method described above.

[0089] The two points A and B correspond to the two points which respectively allowed the measurement of an average length A and an average length B . For this purpose, the determination of the geometric parameter z for section 11 corresponds to the calculation of the average of all the average lengthsz i , for example, 2000 average lengths including the average lengthsz A etz B .

[0090] Illustrates section 11 when determining an average radius A scanning said section 11 from a point A of the periphery 11.1.

[0091] It can be seen that from point A, a plurality of raysz A,α are projected onto a portion of the periphery 11.1 visible from said point A. In this configuration, the rays z A,α can be included between two extreme radii A,α tangents to the periphery 11.1.

[0092] The number of rays A,α projected can depend on the angle α chosen, the latter allows to establish the precision of determination of the average radius A For this purpose, the angle α can be between 0.001° and 10°.

[0093] The average ray A thus corresponds to the average of all projectionsz A,α .

[0094] Illustrates section 11 when determining an average radius Bscanning said section 11 from a point B of the periphery 11.1.

[0095] Preferably, the angle α is identical for all projections of the rays z i,α for the plurality of points on the periphery 11.1. Preferably, the number of points on the periphery 11.1 from which the rays will be projected is approximately 2000 points, this number being able to vary according to the desired calculation precision.

[0096] Similar to point A, the rays z B,α are projected from point B onto a portion of the periphery 11.1 visible at said point B. The average radius B corresponds to the average of all projectionsz B,α .

[0097] The geometric parameter z is therefore the average of all the mean radii z i (including medium rays) A etz B ,) points around the entire periphery 11.1.

[0098] The geometric parameter z corresponds to a geometric dimension that can be expressed in mm. Advantageously, this parameter z is the optimal dimension that best distinguishes the geometric shape of the section 11 and thus ensures a precise correlation between the welding parameters and the speed VCA. Indeed, the surfaces of the section 11 including the projected rays z i,α from each point can be assimilated to the mixing surface of the material during orbital friction welding (without being limited by any particular theory).

[0099] The geometric parameter zallows to take into account the specificities of orbital friction welding in the manufacturing process. Indeed, the friction force provided during welding rotates cyclically, which implies that a weld point at the end of section 11 (eg point A or B) sees a fraction of section 11 of the blade between the two extreme projected radii (z A,α ouz B,α ), these can therefore be assimilated to equivalent lengths of material to be sheared.

[0100] Moreover, the parameter z is relevant because it allows to take into account more the camber of the specific shape of the periphery 11.1, in a better way than the area of ​​said section 11 or the chord of its profile.

[0101] In order to further optimize the dimensions of the blade and the rotor stubs, the sizing method of the present invention makes it possible to act iteratively on the shape of the section 11 so as to achieve a maximum thickness max predefined, while the parameters of the orbital friction welding from which the VCA speed is predetermined remain constant.

[0102] Preferably, the shape of the section 11 is modified by acting on the excess thickness. For example, with reference to 1a, the excess thickness e can be retained, and a second excess thickness can further widen the narrowest regions of the section 11, i.e. widening at the ends 11.2, 11.3. The modification of the section 11 can be carried out manually by means of modeling software, or in an automated manner by a specific computer algorithm.

[0103] The modification of section 11 results in a change in the value of the geometric parameter z, which influences the determined VCA speed as well as the e max . In this configuration, for each new junction section established, the maximum thickness max is determined, and this iteratively until the said max determined corresponds to the e max initially predefined, with a tolerance of ±5%.

[0104] The last joint section modeled before stopping the iteration is the one that will be used for orbital welding of the blade to the disc, said section will be widened enough compared to the blade profile to ensure constant material mixing and VCA speed during welding, thus obtaining a welded joint with better structural quality and free of recesses and contaminants.

[0105] Advantageously, the dimensioning method of the invention therefore makes it possible to define both an optimal radial position of the welding plane and an ideal junction section. This is done prior to the manufacture of the bladed disc, so as to allow anticipation of the stresses that may be exerted on the junction following possible impacts of debris on the blades. Thus, the bladed disc obtained by orbital welding of the blades to the stubs dimensioned by the method comprises junctions positioned radially in an optimal manner, each of said junctions advantageously comprising improved structural and dimensional quality.

[0106] Advantageously, the welding method of the invention makes it possible, during the manufacture of the turbomachine bladed disc, to estimate the maximum thickness maxfor each orbital weld made between the blade and the stump, from the geometric parameter z, and by measuring the speed VCA and the forging pressure directly on the welding machine used.

[0107] The geometric parameter can be the one used when modeling the section to be welded, or measured on the blade and / or on the stub before the welding operation, for example, by means of an image recognition measurement.

[0108] Advantageously, the welding method of the invention makes it possible to validate the value of the maximum thickness max estimated during each weld without requiring a physical inspection of the part (eg by making cuts and micrographs) thus ensuring efficiency and considerable time savings during the manufacture of the bladed disc.

[0109] Preferably, the validation includes a comparison of the maximum thickness maxestimated with thickness values ​​between predetermined limit limits, for example, when modeling the junction. Advantageously, these limit limits make it possible to respect certain design criteria (e.g. critical threshold N1 / N2 for crack propagation, tolerance interval involving parametric and / or height and / or inclination variability of the junction, etc.).

[0110] Alternatively, the comparison of the e max determined (by measuring the VCA and the parameter z) during orbital welding can be carried out with the e max calculated during modeling, which makes it possible to quantify the influence of the actual welding parameters (measured on the machine) on the thickness of the modeled junction and thus validate the welds during the manufacture of the bladed disc without requiring destructive cutting of the bladed disc.

[0111] Preferably, the junction section S of each of the blades 4 and stub 6 comprises a total surface area greater than or equal to 200 mm2 and less than or equal to 7000 mm2, and more preferably between 2000 mm2 and 3000 mm2.

[0112] Illustrates a mapping of the amplitude of the average rays i sweeping the junction section at any point i of its periphery.

[0113] The scale visible to the right of the corresponds to the mapping of the evolution of the value of z i , this being normalized to 1, i.e. the maximum value of z i of section 11 is equal to 1.

[0114] It can be seen that the points i from the periphery 11.1 to the ends 11.2 and 11.3 of the section 11 have the averagesz i rays i,α launched from the said points which are the weakest compared to the averages i of rays i,αlaunched from points which are positioned between ends 11.2, 11.3.

[0115] Advantageously, the present invention makes it possible to model the welding process in order to accurately determine both the e max which is the maximum joint thickness on the welded joint profile and the material consumption rate VCA, upstream of carrying out the orbital welding operation.

[0116] The material consumption rate VCA is here determined analytically according to the present invention, as a function of the geometric parameter (parameterz), the value of the eccentric, the orbital oscillation frequency, and the pressure applied during the orbital movement. The maximum thickness max is then determined as a function of the previously determined speed VCA and the parameters z.

[0117] Advantageously, the geometric parameter is able to take into account specific details of the shape of the section, such as its camber, unlike a simple measurement of the area or widths or according to other methods of the prior art which are not able to take them into account. These details of the shape of the junction section which the geometric parameter is able to intrinsically take into account, make it possible to arrive with greater precision at a determination of the maximum thickness. max , then to the determination of the radial height of the welded joint.

[0118] Welds were made on the same machine and with constant welding parameters, i.e. eccentricity, oscillation frequency, forging speed and pressure which remain unchanged, only the shape of the sections which is modified.

[0119] Measurements of the thickness of welded joints were carried out on a large number of welds. These measurements showed that the variation profile of the thickness of the joint over the entire welded section depended only on the factors i whereas the overall amplitude of this thickness variation profile depended on the welding parameters.

[0120] As an indication, the maximum measured thickness of the welded joint from two identical sections 11 is equal to 0.97 mm, for a parameter z equal to 25 mm.

[0121] Illustrates the junction section 11 of the showing three measurement marks of the e max of the welded joint 11, with two of these identical joint sections 11. Each mark defines the total local width of the section, following the corresponding direction illustrated in dotted lines.

[0122] Figures 7A to 7C represent graphs showing the normalized evolution of the thickness of the joint of section 11 of the, measured on the welds made and estimated numerically using the parameter z.

[0123] This is a first graph representing the evolution of the estimated thickness of the welded joint (see plot S) compared to points P of actual measurements of said thickness, at the right of the first mark positioned at 1 / 4 of a total extent (along the profile chord) of section 11 visible at.

[0124] This is a second graph representing the evolution of the estimated thickness of the welded joint (see plot S) compared to points P of actual measurements of said thickness, at the right of the second mark positioned at 1 / 2 of the total extent of section 11 visible at.

[0125] This is a third graph representing the evolution of the estimated thickness of the welded joint (see plot S) compared to points P of actual measurements of said thickness, at the right of the third mark positioned at 3 / 4 of the total extent of section 11 visible at.

[0126] With reference to Figures 7A to 7C, the S plots are preferentially obtained by simulation provided by an artificial intelligence which bases the determination of the e max as a function of the material consumption rate VCA as well as as a function of the parameter z according to the present invention.

[0127] It can be observed that for each of the three measurement benchmarks, the difference (the margin of error) between the simulation (carried out upstream of the orbital welding) and the measurement of the e maxcarried out after the welding operation, is very minimal, which proves that the present invention makes it possible to ensure precise modeling of the section to be welded as well as a determination of the height of the weld which is the most exact and close to reality.

[0128] We can also observe a general bathtub shape of the S traces, this is due to the fact that at the peripheral ends of the welded joint, the thickness is wider than in the center, this is due to a concentration of the excess material displaced during orbital welding, giving a generally diabolo or straw shape to the welded joint (as visible in the).

[0129] It should be noted that the prior art does not provide any solution for estimating the maximum thickness of the welded joint or its dependence on the shape of the section.

[0130] In general, it is important to note that a configuration where two sections to be welded have a perfect circle shape allows for optimal orbital welding. This configuration ensures perfectly homogeneous and constant mixing, which guarantees a stable temperature rise of the materials. In addition, the circular shape of the sections allows for uniformity of friction over 360°, without any change in shape.

[0131] The inventors took the inventive step of introducing the ray tracing method described above, an unconventional technique in the field of mechanics, to characterize the junction section in order to take into account all directions of friction. Indeed, scanning the section with rays i,αlaunched from each of all points on its periphery, is similar to the movements of mixing material between the surfaces in contact during orbital welding, said movements being in all directions and over 360°.

[0132] This correlation between the mixing physics during orbital friction and the theoretical calculation of the parameterz, offers the possibility of predicting the behavior of material mixing even before orbital welding is carried out. Thus, the parameterz allows the welding results to be estimated with sufficient precision (VCA,e max ) at an early stage of the process (when modeling the shape of the joint section and before welding is carried out).

Claims

Method for modeling a junction (10) of a blade (4) to a stub (6) on a turbomachine rotor (2), by orbital friction welding, comprising the following step:determining a material consumption rate VCA as a function of the following orbital friction welding parameters: eccentricity, frequency and pressure, and a geometric parameter z of the section (11) of the blade (4) and the stub (6) at the junction (10);characterized in that the method further comprises the following step:determining a maximum thickness max of the junction (10) as a function of the determined material consumption rate VCA, the geometric parameter z being an average of the average radii z i scanning the section (11) of the blade (4) and the stub (6) at the junction (10) at any point on the periphery (11.1) of said section (11). The modeling method of claim 1, wherein the maximum thickness maxdetermined and the material consumption rate VCA determined are all the greater as the geometric parameter z is small and vice versa. Modeling method according to one of claims 1 and 2, in which the average rays z i sweeping the section (11) of the blade (4) and the stub (6) at the junction (10) at any point on the periphery (11.1) of said section (11) are strictly contained in said section (11). Modeling method according to one of claims 1 to 3, in which the average rays z i sweeping the section (11) of the blade (4) and the stub (6) at the junction (10) at any point on the periphery (11.1) of said section (11) completely sweeps said section (11). Modeling method according to one of claims 1 to 4, in which the maximum thickness maxdetermined and the determined material consumption rate VCA are smaller as the eccentricity decreases and vice versa. Modeling method according to one of claims 1 to 5, in which the maximum thickness max determined and the determined material consumption rate VCA are smaller as the frequency decreases and vice versa. Modeling method according to one of claims 1 to 6, in which the determination of the maximum thickness max and the material consumption rate VCA is based on experimental orbital friction welding data, where for each welding operation the material consumption rate VCA is measured and correlated with the eccentricity, frequency, pressure and geometric parameter z. Modeling method according to claim 7, in which the correlations of the experimental data are made so as to provide a model for determining the rate of consumption of material VCA and possibly the maximum thickness max . Modeling method according to claim 8, in which the model for determining the material consumption rate VCA and possibly the maximum thickness max involves the use of artificial intelligence. Method for orbital friction welding of a blade (4) to a stub (6) on a turbomachine rotor (2) to form a junction (10), comprising the following step: determining a material consumption rate VCA; characterized in that the method further comprises the following step: determining a maximum thickness maxof the junction (10) as a function of the determined material consumption rate VCA and as a function of a geometric parameter z corresponding to an average of the average radii z i scanning the section (11) of the blade (4) and the stub (6) at the junction (10) at any point on the periphery (11.1) of said section (11). The welding method of claim 10, further comprising a step of comparing the maximum thickness max determined with an interval of values ​​of the maximum thickness max predefined during a modeling method of the junction (10) of the blade (4) to the stub (6), said modeling method being according to one of claims 1 to 9. Method for sizing a blade (4) and a corresponding stub (6) on a turbomachine rotor (2), intended to be joined by orbital friction welding, according to a maximum thickness maxof the predetermined junction (10), characterized in that the dimensioning method comprises an iteration of determining the maximum thickness max of the junction (10) according to different dimensions of the junction (10), according to a modeling method according to one of claims 1 to 9. The sizing method of claim 12, wherein the iteration of determining the maximum thickness max of the junction (10) according to different dimensions of the junction (10) is carried out while the eccentricity, the frequency and the pressure remain constant. Dimensioning method according to one of claims 12 and 13, in which the different dimensions of the junction (10), in the iteration of determining the maximum thickness max of the junction (10), are selected so as to correspond to different values ​​of the geometric parameter z. Dimensioning method according to one of claims 12 to 14, in which the iteration of determining the maximum thickness max of the junction (10) according to different dimensions of the junction (10) is stopped when the maximum thickness max determined corresponds to the maximum thickness max of the junction (10) predetermined with a given tolerance.

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