Patent Application
20080092616
The invention can be better understood from the following detailed description of non-limiting implementations thereof, and from an examination of the accompanying drawings, in which:
The rotary machine M shown in
By way of example, said machine M is a gas or steam turbine, for example an airplane engine, the rotor R of which has not been completely removed from the stator S.
The machine M is in its service environment, for example in a power station or on an airplane wing, when the invention is implemented in situ.
The machine M may also have been dismantled from an aircraft and placed on a cradle, not shown, which may, for example, apply to an airplane engine. The rotor R does not need to have been removed completely from the stator S.
Alternatively, the rotor R may have been removed completely from the stator S, but not completely dismantled.
The machine M may need to be shot peened in a predefined region, for example local shot peening treatment following detection of a crack or defect, or more complete treatment, for example of a leading edge.
In general, the region to be treated may be any region of the rotor R or stator S when the stator is present.
Said shot peening unit 1 comprises one or more generators 2 which supply one or more acoustic assemblies 3, each comprising one or more sonotrodes.
An acoustic assembly typically comprises a piezoelectric transducer (also known as a converter) which transforms an electric current delivered by the generator 2 into mechanical waves. The vibration amplitude of the piezoelectric transducer is amplified using one or more acoustic stages (also termed boosters) up to the last part of the stack that constitutes the sonotrode and that defines the vibrating surface. The sonotrode may be arranged to vibrate relatively uniformly over the whole of its vibrating surface.
Together with the treated part, the unit defines at least one treatment chamber containing projectiles, for example spherical beads with diameter in the range 0.3 mm [millimeters] to 5 mm. The density of the projectiles is, for example, in the range 2 g/cm3 [grams per cubic centimeter] to 16 g/cm3. The quantity of projectiles is, for example, in the range 0.2 g [grams] to 50 g. The hardness of the projectiles is, for example, in the range 200 HV [hardness Vickers] to 2000 HV.
Where appropriate, the generator 2 may be arranged to control drive means 5 for at least one acoustic assembly 3, as is described below, to displace the acoustic assembly relative to the machine M and to treat an extended region of the machine M.
The unit 1 may include optional means 6 for injecting compressed air into the treatment chamber or towards it, to initiate movement of the projectiles.
The unit 1 may also include detection means 7 that can prevent the operation of the acoustic assembly under certain conditions, for example when there is a risk of accidental departure of projectiles.
The unit 1 may be used to treat various regions of the machine M and, for example as shown in
Said edge 10 may be sharp, chamfered, and/or rayed or it may have undergone a repair treatment by machining and polishing.
In the example shown, the rotor R includes a central bore 21 which may have various profiles and which operates, for example, as a function of the nature of the machine.
In the example shown in
In
The projectiles 17 move in a treatment chamber 18 which is formed by the sonotrode 15, the region to be treated, and the elements 20 for forming a primary chamber.
The elements 20 for forming a primary chamber are produced from a metallic or non metallic material which allows projectiles to ricochet from them, for example steel, INCONEL®, aluminum, or a plastic material, for example a polyamide, a polyacetal, or polyethylene.
The acoustic assembly 3 is mounted on a support system 23 which is fixed on the machine M.
In the example shown, the support system 23 is fixed on the rotor R and more particularly in the central core 21.
The support system 23 may comprise a first portion 22 which is stationary relative to the rotor and a second portion 25 which can turn relative to the first portion 22 by means of a hinge 28 to allow the acoustic assembly 3 to be displaced relative to the machine M to treat an extended region thereof or to carry out several local treatments.
The first portion 22 of the support system 23 may comprise a mechanism 29 for fixing to the rotor R which may also, where appropriate, allow adjustment of centering to cause the hinge axis 28 to coincide with the axis of rotation X of the rotor.
The mechanism 29 may act by radial expansion or otherwise.
Displacement of the acoustic assembly 3 may be carried out manually, for example by the operator manually turning the second portion 25 relative to the first portion 22.
Displacement of the acoustic assembly 3 may also be motorized using the above-mentioned drive means which, for example, comprise at least one motor 33 housed in the first portion 22, as can be seen in
The second portion 25 supporting the acoustic assembly 3 may, for example, be driven via reduction gearing 34.
The motor 33 may also be housed in the second portion 25, as shown in
The motor 33 may, for example, be an electric motor powered by the generator 2 in a controlled manner to allow, for example, rotation of the acoustic assembly 3 about the axis of rotation X of the rotor at a predefined speed.
The unit 1 may comprise one or more detectors, not shown, to inform the generator 2 of rotation of the acoustic assembly 3 about the axis X, for example an encoder, which may be optical or magnetic, turning with the shaft of the hinge 28 or with the shaft of the motor 33.
The second portion 25, which supports the acoustic assembly 3, may be produced in a variety of manners as a function, for example, of the shape of the region to be treated.
In a variation, not shown, the drive means 5 comprise a screw or rack allowing axial displacement of the second portion 25 along the axis X.
In the example shown, the second portion 25 allows adjustment of the orientation of the longitudinal axis Z of the acoustic assembly 3 relative to the axis of rotation X, using curvilinear holes 35 and associated fixings 135.
In a variation, not shown, the support system 23 can also allow adjustment of the position of the acoustic assembly 3 along its longitudinal axis Z, for example by means of a rack or a screw.
The elements 20 for forming the primary chamber may come into contact with the treated part or may remain spaced therefrom during operation of the acoustic assembly 3, by a distance which is sufficiently low to prevent the existing clearance to permit the passage of projectiles 17.
The elements 20 for forming the primary chamber may be urged mechanically to bear against the part to be treated by one or more springs, where appropriate.
As indicated above, the unit 1 advantageously includes detection means 5 to detect a breach of security linked, for example, to poor positioning of a mechanical component of the unit.
Said detection means 5 may comprise several detectors located at multiple positions in the unit 1.
In the example under consideration, one or more of the elements 20 for forming the primary chamber comprise detection means 40 which are sensitive to the proximity of the treated part to prevent operation of the acoustic assembly 3 in the event that there is a risk of accidental exit of a projectile from the treatment chamber.
The detection means 40 may, for example, comprise at least one detector disposed at the end of an element 20 for forming the primary chamber and sensitive to the presence of the part to be treated.
As an example, it may be: a contactor, the contactor being actuated by the part to be treated when the element 20 for forming the primary chamber is correctly positioned; or a resistive sensor which is sensitive to electrical contact between the element for forming the primary chamber and the treated part; or an inductive sensor, for example a Hall effect sensor, sensitive to the magnetic field of the part to be treated when it is produced from a magnet material; or a capacitative, or an optical sensor, or otherwise.
The detection means 40 may supply an electric signal to the generator 2, which generator is arranged to indicate a defect in operation to the operator and to prevent operation of the acoustic assembly 3 in the event of poor positioning of at least one of the elements 20 for forming the primary chamber.
The support system 23 may also include detection means, not shown in the figures, which can detect correct positioning of the first portion 22 in the bore 21 of the rotor R.
These detection means may in particular be arranged to detect the position of the support system relative to the rotor to avoid any risk of a projectile passing through the clearance left between the support system 23 and the bore 21 of the rotor.
Said detection means comprise, for example, one or more contactors, not shown, which change state when bearing on the bore or on a rib 200 or the rotor R.
The unit may, as shown, include a secondary chamber 60 formed around the treatment chamber 18 to further reduce the risk of accidental loss of a projectile 17.
Said second chamber 60 may be defined by elements 61 for forming a secondary chamber which may, for example, be applied to the part to be treated M and/or the support system 23.
Said elements 61 for forming a secondary chamber may, where appropriate, include a return system 65, shown in
Like the elements 20 for forming the primary chamber, the elements 61 for forming the secondary chamber may be provided with detection means 63 to detect contact or approach of said elements 61 to the treated part and/or the support system 23.
The unit 1 may be arranged to prevent operation of the acoustic assembly 3 in the case of non detection of sufficient closure of the secondary chamber 60.
The detection means 63 are, for example, selected from resistive, inductive, capacitative, optical or other sensors or contactors.
The detection means 63 may be of the same nature as the detection means 40.
In one aspect of the invention, additional protection means may be employed to further reduce the risk of accidental loss of a projectile.
In the example shown, a safety barrier 70 is positioned in the bore 21 of the rotor behind the support system 23.
Said safety barrier 70 is, for example, arranged to be fixed on a portion in relief of the rotor, for example a rib 71 which projects into the bore 21 of the rotor.
In variations which are not shown, the safety barrier 70 may be arranged to be fixed on another portion in relief of the rotor, for example a groove, or even to be fixed in the bore 21 in the absence of a particular portion in relief thereof.
The safety barrier 70 may be fixed in the rotor R by locking elements 73, for example, which can be rotated, for example as showed in
The locking elements 73 may be displaced using tab handles 75, for example.
Rather than turning, the locking elements 73 may also be slidably mounted.
As an example,
The locking elements 76 may be displaced against the action of springs 82, as shown in
On turning the tab handle 94, the space between the end plate 92 and the body 91 and thus compression of the seal 90, may be altered, said compression resulting in a radial expansion which ensures that the safety barrier 70 is sealed in the bore 21.
The safety barrier 70 may be independent of the support system 23, as shown.
In a variation, the safety barrier 70 may be linked to the support system 23.
The safety barrier 70 may include detection means that are sensitive to proper positioning of the rotor R in the bore.
Said detection means comprise, for example, a contactor that changes state when bearing against the rib 71. A plurality of contactors may be linked together and circumferentially distributed on the safety barrier 70.
An electric cable, not shown, may connect the detection means of the safety barrier 70 to the support system 23 or the generator 2 so that the generator can prevent operation of the acoustic assembly if the safety barrier 70 is poorly positioned.
The unit 1 may comprise a system 80 for protection against external shocks which defines a space 81 containing the acoustic assembly 3.
The protection system 80 may optionally be impervious to projectiles and may, for example, comprise bars 85, a screen, and/or a shell formed from transparent thermoplastic material or glass.
The protection system 80 may, for example, be fixed on the rotor or the stator, or it may not be fixed to the machine but simply placed in front of it.
The protection system 80 may comprise, in its lower portion, a receptacle 88 for recovering projectiles and provided in its lower portion with a stopper 89 which may be opened to recover the projectiles.
The protection system 80 may be provided with means for detecting its correct position on the machine, said detection means comprising one or more contactors which changes state in contact with the machine M, for example.
Said fixing system comprises, for example, one or more elements for pressing tightly against the rotor R or the stator S.
As shown in
The closure means 100 may be displaced manually after positioning the acoustic assembly 3 in front of the appropriate region of the machine.
Where appropriate, a locking member controlled by the generator 2 may prevent the closure means 100 from being displaced while satisfactory closing of the treatment chamber 18 and possibly proper positioning of the other components of the unit have not been detected, said locking member being, for example, electromagnetically controlled by the generator 2.
In a further variation, the closure means 100 is displaced in a motorized manner by the generator 2 after verifying that all of the components of the unit are correctly installed.
The invention can treat a rotor including a plurality of peripheral recesses A as showed in
Said recesses A may each have a longitudinal rectilinear axis L, as can be seen in
The recesses A may have various shapes, for example a shape with a dovetail profile as shown in
The support system 23 may be fixed in a recess Af adjacent to the current recess Ac to be treated, as shown in
To this end, the fixing system 23 may comprise an arm 300 with an end 301 the profile of which is substantially complementary to that of the recess Af.
The fixing system 23 may comprise at least one slide 303 which can displace the acoustic assembly 3 axially along its longitudinal axis Z in order, for example, to adjust the distance separating the vibrating surface 16 of the sonotrode from the bottom 306 of the current recess.
In the example shown, the unit includes elements 132 for forming the primary assembly that can be seen in
Said elements 132 for forming the primary chamber may, for example, be applied against the flanks 310 of the rotor onto which the recesses A open.
In
The acoustic assembly 3 may comprise a sonotrode which extends over the whole length of the recess.
Using a single sonotrode is especially suitable when the longitudinal axis of the current recess Ac is rectilinear.
When a recess extends along a curvilinear longitudinal axis L, several sonotrodes 15 may be disposed side by side, as shown in
The acoustic assemblies may be fixed via a part 410 having through holes for passing the various stacks. These stacks may be fixed to the part 410 at a vibration node.
Where appropriate, the unit 1 may include chamber-forming elements 110 which define axially, relative to the longitudinal axis L, the treatment chamber inside the current recess Ac, as shown in
The acoustic assembly 3 may be kept stationary relative to the recess Ac during treatment thereof. In a variation, the acoustic assembly 3 may be mounted with the possibility of displacement relative to the support system to be able to be displaced relative to the current recess Ac.
Such displacement may, for example, allow the sonotrode to be engaged in the recess and to progressively treat it while it is being displaced, and while still following its longitudinal axis L.
When the sonotrode or sonotrodes are at least partially engaged in the current recess Ac, as shown in
The treatment chamber may be closed in the current recess Ac by means, for example, of one or more closure elements 130 which are applied to the flank or flanks of the current recess, as shown in
When the sonotrode remains outside the current recess, the treatment chamber may be defined by closure elements 131, e.g. for pressing against the rotor surface between the recesses, as shown in
When the current recess Ac includes a hole T, it may be plugged by a plugging element 140 which may be located in a variety of manners in the hole T, for example from the current recess or via the hole of an adjacent recess.
Where appropriate, the plugging element 140 includes detection means which can detect its correct positioning in the hole T. These detection means comprise, for example, a contactor that changes state when the plugging element 140 bears against the wall of the hole T or an adjacent wall. The generator 2 may be arranged to prevent the operation of the acoustic assembly or assemblies 3 in the event that it detects that the plugging element 140 is not positioned properly.
The treatment chamber may be defined by elements 141 for forming a primary chamber, which can define the treatment chamber around the hole T.
In all of the above examples, before operating an acoustic assembly 3, its vibrating surface 16 may be orientated upwardly or downwardly.
When the vibrating surface 16 is orientated upwardly, the projectiles 17 may reach the vibrating surface 16 under gravity, which can initiate their motion.
When the vibrating surface is orientated downwardly or obliquely, at least one air jet may be directed towards the projectiles 17 to initiate their movement and bring them into contact with the vibrating surface 16.
Any of the examples described above may include a means 6 for injecting air comprising, for example, a pressurized air inlet channel admitting air into an element for forming the primary chamber, for example, or elsewhere.
Air injection may be controlled by the generator 2, which has, for example, an outlet which can control a solenoid valve for admitting compressed air into the treatment chamber for a predefined period after starting operation of the acoustic assembly.
Where appropriate, a jet of air may be delivered constantly into the treatment chamber in order, for example, to cool one or more of the components of the unit.
A unit of the invention may include counter means for counting the projectiles before operating the acoustic assembly and after the treatment has been carried out.
Said counter means comprise, for example, a suction duct opening into the treatment chamber, via which the projectiles may be sucked in, said projectiles passing in front of a detector suitable for counting them, for example an optical sensor.
The invention is not limited to a particular shape of rotor or stator, nor to a particular region of the machine undergoing shot peening.
The expression “comprising a” should be understood as being synonymous with “comprising at least one” unless specified to the contrary.
Although the present invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
Although the present invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 06 54428 | Oct 2006 | FR | national |
