FR2908678A1 - Blade shank processing device for e.g. automobile sector, involves shot blasting of internal edge of indent in shank of blade using shot blasting installation, where installation has sonotrode for propelling projectiles - Google Patents

Abstract

The method involves shot blasting of an internal edge of an indent in a shank (10) of a blade (9) by a shot blasting installation (12). The installation has a sonotrode (11) for propelling projectiles (1), and a processing chamber (30) closed in upwards and projected on a vibrating surface of the sonotrode. The projectiles have a core made of less noble material such as steel/uranium. The projectiles have density greater than or equal to 8 grams/cubic centimeter, hardness greater than/equal to 800 Vickers, and dimension less than/equal to 1.5 mm. The projectile is made of tungsten carbide. Independent claims are also included for the following: (1) an ultrasonic shot blasting installation comprising a shot blasting device (2) a device for processing a piece by shot blasting.

Description

The present invention relates to projectiles, devices and

  ultrasonic shot blasting equipment as well as parts processed by shot blasting. Ultrasonic blasting processes and installations are described in particular in French patents FR 2,815,280 and FR 2,815,281, using at least one sonotrode comprising a titanium body for moving projectiles intended to induce compressive stresses in the treated room. US 6,490,899 B2, US 6,343,495 B1, US 6,467,321 B2, US 6,336,844 B1, US 6,289,705 B1, US 6,508,093 B2, US 2003/0115922 A1, US 6,505,489 B2 and US Pat. US 6,536,109 B2 still relate to ultrasonic shot blasting.

  The projectiles used and described so far in these patents are mainly steel balls whose diameter is for example about 2 mm. The use of these projectiles does not allow to obtain a sufficient intensity of treatment on concave surfaces having a radius of curvature lower than that of projectibles or in the bottom of certain recesses.

  The present invention aims, in a first aspect, to overcome this disadvantage, and it achieves this through a projectile for use in a shot blast installation, including an ultrasonic shot blasting installation in which the projectile is propelled by at least one sonotrode, the projectile being characterized by the fact that it has: a hardness greater than or equal to 800 HV, preferably greater than or equal to 1300 HV, a density greater than or equal to 8 g / cm3, better than or equal to 12 g / cm3, and - a larger dimension less than or equal to 1.5 mm.

  The use of such a projectile makes it possible to treat areas that are difficult to access with conventional projectiles, having small radii of curvature, in particular less than 1.5 mm, the projectile nevertheless being able to acquire a kinetic energy large enough to generate the desired level of stress in the room and remaining compatible with the use of a sonotrode.

  The projectile is preferably substantially spherical, in particular with a maximum tolerance of plus or minus 60 m on its sphericity.

Preferably, the projectile comprises on the surface at least one non-ferrous material, advantageously tungsten carbide (WC). The projectile can be made entirely of tungsten carbide. Furthermore, the presence of iron in the conventional steel projectiles of the known shot blasting installations causes the formation on the treated part of a ferrous deposit and / or encrustations which must then be eliminated on pain of oxidation, which requires cleaning the piece after shot blasting. This cleaning operation is also called decontamination and is carried out in baths. For example, etching baths are used which lower the level of residual stresses and reduce the fatigue strength of the workpiece. The invention aims, in another aspect, to avoid this additional treatment and at the same time maintain the fatigue strength of the treated part. It achieves this by means of a projectile intended for use in a shot-blasting installation, in particular a shot-blasting installation in which the projectile is set in motion by at least one sonotrode, this projectile being characterized by the fact that it comprises on the surface at least one non-ferrous material and in that it has a density greater than or equal to 3 g / cm 3, better still greater than or equal to 12 g / cm 3. The non-ferrous material is advantageously tungsten carbide (WC). The invention further relates, in another of its aspects, independently or in combination with the foregoing, to a projectile for use in a shot blasting installation, in particular an ultrasonic blasting installation comprising at least one sonotrode, this projectile comprising: - a core of at least a first material, and - at least a second material different from the first in an envelope 25 surrounding the core. Such a projectile, composite, may allow for example to use, to achieve the core, a less noble material that used to achieve the envelope, which can help reduce costs. This can still make it possible to use for the core a material that is denser but does not have sufficient hardness.

Preferably, the second material has a hardness greater than that of the first, in particular a hardness of greater than or equal to 800 HV, better still greater than or equal to 2908678 3 1300 HV, and preferably also, the second material is a non-ferrous material, for example tungsten carbide (WC). The invention further relates, in another of its aspects, individually or in combination with the foregoing, to a blasting device comprising at least one sonotrode for moving at least one projectile, in particular a projectile as defined herein. above, this sonotrode having at least one face intended to come into contact with the projectile, this device being characterized by the fact that the sonotrode has a metal body, preferably made of titanium, coated with a deposit of a harder material than the base metal with a thickness greater than or equal to 0.5 mm, advantageously based on tungsten carbide. Such a device makes it possible to obtain a much greater resistance to wear (abrasion) of the sonotrode, in particular when using projectiles having the characteristics defined above, without harming the acoustic operation of the sonotrode.

The thickness is preferably greater than or equal to 0.75 mm, being between 0.9 mm and 1.1 mm, for example. The invention further relates, in another of its aspects, independently or in combination with the foregoing, to a device for treating at least one part by shot blasting, this device comprising at least one sonotrode for setting in motion at less a projectile, for example a projectile as defined above, this sonotrode comprising a body made at least partially of titanium, this device being characterized by the fact that the body is made at least partially, better entirely, made of forged titanium . The Applicant has indeed found that the forged titanium could be used for the manufacture of a sonotrode, which may allow for example to diversify the supply sources in case of shortage on the titanium obtained by rolling, used until now to make the sonotrodes. The invention is not limited in this particular aspect to sonotrodes used for ultrasonic shot blasting and can be applied to sonotrodes used for ultrasonic welding. The invention thus also relates to a sonotrode made at least partially forged titanium, considered alone.

According to another of its aspects, the invention also relates, independently or in combination with the foregoing, to a device for treating at least one part by shot peening, this device comprising at least one sonotrode and a chamber of treatment in which projectiles are set in motion by the sonotrode, this device being characterized in that the chamber comprises at least one wall or protrusion bearing against the workpiece. Such a device may have the advantage of allowing the use of projectiles of relatively small size without fear that they will engage for example in an opening of the treated part, such an opening being closed by the wall or protrusion of the aforementioned chamber and delimit the treatment areas, this having the advantage of avoiding masking / unmasking operations. The invention further relates, in another of its aspects, independently or in combination with the foregoing, to a device for treating at least one part by shot blasting, this device comprising at least one sonotrode and a treatment chamber in which the projectiles can be moved by the sonotrode, this device being characterized in that it comprises a filling element whose shape substantially matches that of a face of the workpiece located on the opposite side to the sonotrode . Such a filler may expedite the return of projectiles to the sonotrode or prevent some projectiles from returning to the sonotrode. The invention further relates, independently or in combination with the foregoing, according to another of its aspects, a shot blasting installation of a workpiece, comprising: at least one sonotrode, at least one projectile having a surface of a non-ferrous material, the vibration amplitude of the sonotrode being chosen so as to induce in the part to be treated stresses corresponding at least to an ALMEN intensity of F8A. The invention further relates, in another of its aspects, independently or in combination with the foregoing, to a device for blasting at least one workpiece, comprising a sonotrode for propelling projectiles onto the workpiece. this sonotrode having at least one cavity in which the workpiece is partially engaged. Thus, the workpiece is not engaged inside this cavity. The cavity is for example made on a substantially flat end face of the sonotrode.

Such a device makes it easier and faster to process parts with projecting parts, which may be partially engaged in the cavity of the sonotrode and reducing the processing time. The path between the vibrating surface of the sonotrode and the treated part can be shortened and the cavity can be made for example with inclined faces helping to direct the projectiles towards certain areas of the workpiece that would otherwise be more difficult to reach and / or helping to reduce the incidence of projectiles, thus increasing the impact force and reducing the treatment time. The invention also relates to a shot blasting installation comprising a sonotrode and at least one projectile as defined above. In such an installation, the sonotrode is for example excited at a frequency of between 10 and 60 kHz, for example a frequency of the order of 15 kHz, 20 kHz or 40 kHz. Furthermore, US Pat. No. 6,536,109 teaches treating a plurality of blade roots by shot blasting by placing them in an enclosure, the longitudinal axis of the blades being oriented parallel to the longitudinal axis of the sonotrode.

The invention aims, according to another of its aspects, to further improve the blade root treatment. It achieves this through a method of treatment in a shot blasting installation of at least one foot of a blade, the blade having a longitudinal axis, the blasting installation comprising a blasting device comprising a sonotrode having a longitudinal axis. and a plurality of projectiles moved by the sonotrode, the method being characterized by the fact that the foot is arranged so that the longitudinal axis of the blade is substantially perpendicular to the longitudinal axis of the sonotrode. It is possible to place against an end face of the blade root, located substantially opposite the blade, an elastically deformable tip.

Advantageously, it fills the space behind the side face of the foot opposite the sonotrode with a filling element whose shape substantially matches that of this face. The invention also relates, independently or in combination with the foregoing, to a workpiece treated in a shotblasting installation using at least one projectile as defined above, having a shot-blasted surface devoid of deposition or ferrous encrustations. and comprising at least one concave portion having a radius of curvature less than or equal to 1.5 mm, in particular less than or equal to 0.7 mm. The blasted surface preferably has an ALMEN intensity stress level greater than or equal to F8A. The invention further relates, independently or in combination with the foregoing, to a device for blasting a workpiece having cavities open radially outwardly around its periphery, this device comprising a processing chamber open on the sonotrode, this treatment chamber being traversed by a peripheral region of the part comprising the cells, the part being rotated relative to the sonotrode about an axis substantially parallel to the longitudinal axis of the sonotrode. The invention further relates, in another of its aspects, independently or in combination with the foregoing, to a device for blasting a workpiece comprising an annular groove at the periphery, in particular a groove having a cross section with a constriction , the device comprising a treatment chamber comprising side walls disposed on either side of the part, in particular side walls covering the lateral faces of the part, a bottom wall uniting the side walls, this bottom wall being crossed; by an opening opening on the sonotrode so as to allow projectiles to impact the sonotrode and be moved by it in the treatment chamber, the treatment chamber being arranged so that it can be traversed by the part, the latter being rotated about an axis substantially perpendicular to the longitudinal axis of the sonotrode. The invention further relates, in another of its aspects, independently or in combination with the foregoing, to a blasting device having a treatment chamber open on a sonotrode and a deflector for returning projectiles present in the treatment chamber and set in motion by the sonotrode to the surface to be treated. The deflector has for example a conical shape so as to treat a tubular wall, for example a through hole. The treatment chamber 5 may for example be defined between an upper part comprising the baffle and a lower part comprising the sonotrode. The invention also relates to a device for blasting a cylindrical piece provided at one end with a curtain, this device comprising a sonotrode and a treatment chamber traversed by the toothing, the part being rotated around an axis perpendicular to the longitudinal axis of the sonotrode, the treatment chamber comprising a deflector for returning projectiles to the bottom of the grooves formed between the teeth of the toothing. In a variant, the part is rotated about an axis substantially parallel to the longitudinal axis of the sonotrode and the treatment chamber 15 has inclined walls for returning projectiles to radially inner and radially outer faces of the teeth. the teeth. In another variant, the toothing is fully engaged in the treatment chamber, which may include a central conical deflector for returning projectiles to the radially inner surface of the teeth of the toothing and a peripheral deflector for returning projectiles to the radially outer surface of the teeth of the toothing. The part may be driven or not relative to the sonotrode, about a substantially parallel longitudinal axis thereof. The invention further relates, in another of its aspects, independently or in combination with the foregoing, to a device for blasting a workpiece comprising a tapping, this device comprising a sonotrode and a treatment chamber delimited at least partially by a deflector introduced into the tapping, the baffle having a wall inclined relative to the longitudinal axis of the sonotrode so as to return to a thread of the tapping projectiles. The axis of the sonotrode may be substantially parallel to the axis of the tapping. Means may be provided to cause relative movement of the deflector relative to the workpiece. The latter may for example be rotated about the longitudinal axis of the sonotrode.

The invention may be better understood on reading the following detailed description, non-limiting examples of implementation thereof, and on examining the appended drawing, in which: FIG. 1 schematically represents an example of a projectile 5 according to one aspect of the invention, FIG. 2 partially and schematically represents, in section, a part having a concave portion having a small radius of curvature, FIG. in a median plane of a composite projectile according to another aspect of the invention, - Figure 4 schematically and partially shows a shot blasting plant according to another aspect of the invention, - Figure 5 shows the detail. FIG. 6 is a diagrammatic and partial axial section of a sonotrode made in accordance with another aspect of the invention, FIGS. 7 and 8 schematically represent FIG. and partially a bladed blade blast installation according to another aspect of the invention, and - Figure 9 schematically and partially shows an example of a workpiece, - Figure 10 schematically shows an installation. blasting process which can be used to process the part of FIG. 9; - FIGS. 12 to 14 show other examples of a shot blasting plant; FIG. 15 is a schematic and partial representation of another example of a workpiece; FIGS. 16 to 18 show examples of shot blasting installations that can be used to process the part of FIG. 15, and FIGS. 19 and 20 show other examples of shot blasting installations.

PROJECTS According to one of its aspects, the invention relates to a projectile intended for use in a shot blasting installation comprising a sonotrode vibrating with ultrasonic frequencies by a suitable generator. This projectile can be characterized by a hardness greater than or equal to 800 HV, a density greater than or equal to 8 g / cm3, and a larger dimension less than or equal to 1.5 mm. FIG. 1 shows a projectile 1 corresponding to this definition, of substantially spherical shape, the largest dimension indicated above corresponding to the diameter d of the sphere. Preferably, the tolerance on the sphericity is better than plus or minus 60 m. Preferably, the hardness is greater than or equal to 1300 HV and the density greater than or equal to 12 g / cm3.

The projectile 1 is for example made entirely of tungsten carbide or any other material having the required hardness and density. The tungsten carbide comprises for example a cobalt or nickel binder. Preferably, the material used is a non-ferrous material, which has the advantages described above.

In an exemplary embodiment of the invention, the projectile 1 is a ball of diameter d equal to 0.91 mm of tungsten carbide (WC). Such a projectile is for example used in an ultrasonic blasting installation and propelled by the vibrating surface of a sonotrode whose amplitude of vibration is for example of the order of 60 to 80 m, so that The kinetic energy of the projectile impacting the workpiece can generate constraints, at the end of the treatment of the workpiece, of ALMEN intensity of at least F8A. The excitation frequency of the sonotrode is for example between 10 and 60 kHz, for example 20 kHz. The frequency can be chosen according to the characteristics of the area to be treated and the treatment criteria imposed for example.

The small size of the projectile 12 makes it possible to treat concave surfaces with a relatively small radius of curvature r, as illustrated in FIG. 2, for example having a radius of curvature r of less than or equal to 0.7 mm. According to another aspect of the invention, the projectile 1 can be composite, which has been illustrated in FIG. 3, with for example a core 2 of a first material and a wrapper 3 of a second material, preferably harder than the first and non-ferrous, the hardness of the second material being for example greater than or equal to 800 HV, better than or equal to 1300 HV, this second material being preferably tungsten carbide. The core may for example be steel, uranium, or any other material compatible with the deposition thereon of the second material and with obtaining compression stresses generated by shot blasting. Sonotrodes According to another aspect of the invention, as illustrated in FIGS. 4 and 5, the sonotrode 11 used to set the projectiles 1, in particular those of the aforementioned tungsten carbide, in motion, may comprise a body 4 made of titanium, coated on its side intended to be impacted by the projectiles by a deposition 5 of a material harder than titanium, to a thickness greater than or equal to 0.5 mm. Preferably, the outer surface of the deposit is taken up (rectified or machined), in order to return the sonotrode its initial shape. The material constituting the deposit 5 is, for example, tungsten carbide deposited on the titanium 15 by any suitable method, in particular by a process implemented by the French company TECHNOGENIA (Saint Joriez). The thickness e is, for example, greater than or equal to 0.75 mm, better still greater than or equal to 0.9 mm, for example of the order of 1 mm. According to another aspect of the invention, the body 4 of the sonotrode can be produced, independently of the presence or absence of the deposit 5, at least partially of forged titanium, for example titanium Ti 10.2.3. Indeed, forged titanium resists internal stresses induced during the operation of the sonotrode by ultrasonic vibrations. According to another aspect of the invention, illustrated in Figure 6, the vibrating face 7 of the sonotrode 11 which is impacted by the projectiles may have at least one cavity 8 in which is partially engaged the workpiece 93 to be treated. The vibrating face 7, with the exception of the cavity 8, is for example flat and oriented substantially perpendicular to the longitudinal axis X of the sonotrode 11. The portion of the part 9 which is engaged in the cavity 8 is for example a dawn foot or platform, a shoulder on a tree. The cavity 8 is for example limited by inclined walls 90 and 91 which may for example be arranged in a dihedron in the case where the portion of the treated part 9 is substantially straight.

The inclination of the walls 90 and 91 allows the projectiles to reach the opposite faces of the portion of the part 9 engaged in the cavity 8 with a lower incidence.

Shot-blasting installations The shot-blasting installations concerned by the invention comprise at least one sonotrode and at least one projectile set in motion by the sonotrode so as to impact the workpiece, directly or after reflection on at least one deflector, which can be constituted for example by a wall of the treatment chamber.

This projectile may be for example one of those defined above, being in particular made of tungsten carbide or steel or with a composite structure. The amplitude of vibration of the sonotrode is chosen for example so as to induce in the workpiece constraints corresponding to an intensity ALMEN greater than or equal to F8A. This amplitude is preferably between 1 m and 300 m. Depending on the nature and in particular the shape of the workpiece, the shot blasting installation may have various configurations. When the workpiece is for example a blade having a longitudinal axis Y, as illustrated in FIGS. 7 and 8, and comprising a foot 10 serving to fix it on an annular support, the blade 9 is preferably oriented with longitudinal axis Y substantially perpendicular to the longitudinal axis X of the sonotrode 11, which facilitates the treatment of the side faces 17 and 18 of the foot 10. Preferably, for such a part, the projectiles which are used are small balls in tungsten carbide with a diameter of less than or equal to 1.2 mm, for example of the order of 0.91 mm. The installation 12 advantageously comprises, in this example, a removable portion 13a supporting a filling member 14 having a portion 15 whose shape is adapted to that of the side face 17 opposite the sonotrode 11, a movable portion 13b and a portion fixed 13c placed above the sonotrode 11 at a distance less than the diameter of the projectile, preferably substantially equal to one third of the diameter of the projectile.

The fixed part 13c has the role of keeping the projectiles at rest on the sonotrode in order to make free the handling of the parts 13a and 13b without the risk of dispersing the projectiles outside the treatment chamber 30. Where appropriate, the part removable 13a may comprise a second filling element 19 having a portion 20 whose shape is adapted to that of the other side face 18, so as to allow the treatment of the side face 17 after the reversal of the movable portion 13b. The latter is held in place in a housing 22 defined in the example between two parts 24 and 25 can be displaced relative to each other, for example by a rotational movement as illustrated. The inner face of each of the parts 24 and 25 coming into contact with the blade 9 may be defined by a removable portion 26 whose shape is adapted to that of the blade 9, which allows changing the removable portion 26 to adapt the blade. installation to other rooms to be treated. The parts 24 and 25 may also comprise seals 27 in an elastically deformable material, these seals 27 being intended to seal the treatment chamber 30 in a projectile-tight manner. In particular, when the foot 10 has at least one opening in its face, end 33 opposite the blade 9, a tip 31 of an elastically deformable material can be applied against this end face 33 in particular to prevent the projectiles from crossing the aforementioned opening or openings. The tip 31 may be attached to the end of a support 32 made for example in a synthetic material resistant to impacts of the projectiles during the treatment time of the foot 10. Of course, the invention may be applicable to a lot of pieces.

In the example illustrated in FIGS. 9 and 10, the part 41 to be treated has cavities 40 distributed around its circumference. This part 41 can be rotated about an axis of rotation parallel to the longitudinal axis of the sonotrode 11, the cells 40 passing through a treatment chamber 42 closed by the sonotrode 11 and superiorly by a wall 43 30 may to be replaced by the sonotrode 11, so as to treat the opposite face of the room at the same time.

For a part having an annular groove 44 at its periphery, as illustrated in FIG. 12, the installation may for example comprise lateral walls 45 coming to cover laterally the workpiece and a bottom wall 47 connecting the walls 45 and closing the treatment chamber 44, this wall 47 being traversed by an opening 46 5 allowing the projectiles 1 set in motion by the sonotrode 11 to impact the workpiece. The latter may for example be rotated about an axis W perpendicular to the longitudinal axis X of the sonotrode. For treating the inner edge 49 of a bore 50 of a workpiece 51, as illustrated in FIG. 13, it is possible, for example, to provide a treatment chamber 50 which is closed above and which opens out inferiorly onto the vibrating face of the sonotrode 11. where appropriate, as illustrated in FIG. 14, it is possible to produce the treatment chamber with at least one central deflector 52, for example of conical shape, so that the projectiles, by bouncing on this deflector, can reach with a lower incidence edge 49. To treat a part 60 having for example a cylindrical shape end with a toothing 61 also called clutch or curvic, as shown in Figure 15, can be used for example one of the installations of Figures 16 18. In the configuration of FIG. 16, the part 60 is rotated about an axis K perpendicular to the longitudinal axis X of the sonotrode 4 and the treatment of grinding of the toothing 61 is performed by passing it through a treatment chamber 63 having a wall 64 inclined obliquely to return the projectiles from the vibrating surface of the sonotrode 11 to the bottom of the grooves formed between the teeth , the wall 64 being inclined for example substantially at 45 relative to the longitudinal axis X of the sonotrode 11. In the configuration of FIG. 17, the part 60 is rotated about an axis T which is parallel to the X axis of the sonotrode 11, the bottom of the grooves formed between the teeth of the toothing 61 facing the vibrating surface of the sonotrode 11.

The treatment chamber may comprise walls 66 inclined obliquely relative to the longitudinal axis X of the sonotrode, so as to return the projectiles 2908678 14 to the radially outer and radially inner faces 68 and 69, respectively, of the teeth of the toothing 61. In the configuration of FIG. 18, the sonotrode 11 is sufficiently wide to treat all of the toothing 61 at a time, the treatment chamber having for example at its center a conical deflector 62 making it possible to return the projectiles towards the face radially inner 69 of the part 60. The treatment chamber may also have a conical peripheral wall 70, for returning the projectiles to the radially outer face 68 of the part 60. The latter may be driven or not rotated around an axis 10 coincides with the longitudinal axis X of the sonotrode. FIG. 19 illustrates the possibility of treating a hole 73 as well as the two input faces 74 and 75 of the piece 72. FIG. 20 illustrates the possibility of blasting a tapping 78, introducing the In the interior thereof, a deflector 79 defining at least partially a treatment chamber, having a wall 80 inclined relative to the longitudinal axis X of the sonotrode 11, for directing the projectiles to the threads 81 of the tapping 78 In all the preceding examples, several sonotrodes can be used simultaneously to treat the same part. These different configurations can be applied in static mode. On the other hand, when the workpiece is rotated, it can be continuously or intermittently. A mixture of projectiles of different natures and / or dimensions can be used, if necessary. The invention is not limited to the examples which have just been described, and is applicable to all parts used in the aeronautics and automobile sectors, in particular blades, blades, turbines, gears. , threads, blade blade receiving cells, fasteners of all kinds, weld seams, connecting radii, dawn / vein, inter-disk pockets, etc. Throughout the description, including the claims, "expression 30" with a "shall be understood as being synonymous with" having at least one ", unless the contrary is specified.

The characteristics of the different examples of implementation of the invention can be combined with one another. In particular, the projectiles of FIGS. 1 and 3 may or may not be used in the examples of FIGS. 4 to 20.

The sonotrode of the example of FIGS. 4 to 5 may or may not be used in the examples of FIGS. 6 to 20.

Claims (14)

  A method of ultrasonically blasting a workpiece (51) by means of an installation comprising a sonotrode (11) and projectiles set in motion by the sonotrode, in which the inner edge (49) is etched away. a bore (50) of the workpiece (51), forming a higher closed treatment chamber and opening below the vibrating face of the sonotrode (11).   2. Method according to claim 1, wherein the hole is drilled and the input faces (74,75) of the piece.   3. Method according to claim 1 or 2, wherein a deflector is used to return the projectiles present in the treatment chamber and moved by the sonotrode to the surface to be treated.   4. Method according to claim 3, the deflector having a conical shape so as to treat a tubular wall, including a through hole.   5. Method according to claim 3 or 4, the treatment chamber being defined between an upper part comprising the baffle and a lower part comprising the sonotrode.   6. An ultrasonic shot blasting apparatus, comprising a device for blasting a cylindrical part provided at one end with a toothing, this device comprising the sonotrode and a processing chamber traversed by the toothing, the part being driven in rotation around an axis perpendicular to the longitudinal axis of the sonotrode, the treatment chamber comprising a deflector for returning the projectiles to the bottom of the grooves arranged between the teeth of the toothing.   7. An ultrasonic shot blasting apparatus comprising a device for blasting a cylindrical part provided at one end with a toothing, this device comprising the sonotrode and a processing chamber traversed by the toothing, the part being rotated around the teeth. an axis substantially parallel to the longitudinal axis of the sonotrode and the treatment chamber having inclined walls to return the projectiles to radially inner and outer faces of the teeth of the toothing. 2908678 17   8. An ultrasonic shot blasting apparatus comprising a device for blasting a cylindrical part provided at one end with a toothing, this device comprising the sonotrode and a processing chamber traversed by the toothing, the toothing being completely engaged in the chamber treatment, the latter comprising a central conical deflector for returning projectiles to the radially inner surface of the teeth of the toothing and a peripheral deflector for returning projectiles to the radially outer surface of the teeth of the toothing.   9. An ultrasonic shot blasting apparatus, comprising a device for blasting a workpiece comprising a tapping, this device comprising the sonotrode and a treatment chamber delimited at least partially by a deflector introduced inside the tapping, this deflector comprising a wall inclined relative to the longitudinal axis of the sonotrode so as to send the projectiles to a thread of tapping, means being provided to cause relative movement of the deflector relative to the workpiece.   10. Device for treating at least one part by shot blasting, this device comprising at least one sonotrode and a treatment chamber in which projectiles can be set in motion by the sonotrode, characterized in that it comprises at least a wall or protuberance (31) elastically deformable bearing against the workpiece.   11. Apparatus for blasting at least one workpiece, comprising a sonotrode for projecting projectiles on the workpiece, the sonotrode having at least one cavity (8) in which the workpiece (93) is partially engaged.   12. Shot blasting device comprising at least one sonotrode (11) for moving at least one projectile, this sonotrode having at least one face intended to come into contact with the projectile, characterized in that the sonotrode comprises a body (4). ) made of metal, in particular titanium, coated with a deposit (5) on the surface of a material harder than the base metal and having a thickness greater than or equal to 0.5 mm.   13. Shot blasting device comprising at least one sonotrode for moving at least one projectile, said sonotrode comprising a body made at least partially of titanium, characterized in that the body is made at least partially forged titanium. 2908678 18   14. A method of treating at least one foot (10) of a blade (9) having a longitudinal axis (Y) in a shot blasting installation, said shot blasting installation comprising a blasting device comprising a sonotrode (11) having a longitudinal axis (X) and a plurality of projectiles, characterized in that the foot of the blade is arranged so that the longitudinal axis (Y) of the blade is substantially perpendicular to the longitudinal axis (X ) of the sonotrode.