EP3105011B1 - System for clamping a part and method for sealing the inner casing of a low-pressure rectifier of a turbomachine - Google Patents

Description

GENERAL TECHNICAL FIELD AND PRIOR ART

The present invention generally relates to the clamping of parts.

It advantageously finds application in the field of aeronautics for the implementation of etching operations and / or abradable injection on inner rings of low pressure turbomachine rectifiers.

STATE OF THE ART

It is traditional to maintain parts in precise positions on work benches using reference flanges.

In particular known clamping systems with manual adjustment. Such a system comprises for example a holding pad which forms a first jaw and which is coupled to a clamping screw. Said clamping screw passes through said pad and is engaged in a reference support with respect to which it is desired to position the part during the intervention.

Such a manual system has the disadvantage of not allowing a uniform clamping of a flange to another and require long setting times.

Moreover, the force exerted on the part is not repetitive and can be highly variable from one operator to another.

Also known clamping systems with hydraulic or pneumatic control.

Clamping is done by hydraulic or pneumatic compression.

However, this presupposes having a large hydraulic or pneumatic energy storage and in particular the ability to have safety reserves to mitigate the case of a possible failure in the production of hydraulic or pneumatic pressure.

Energy management and maintenance of these systems is expensive.

Control and monitoring of the clamping pressure is also complex.

Furthermore, these techniques are poorly adapted to sealing and / or abradable injection operations on domestic shrouds of low pressure turbomachine rectifiers.

During these operations indeed, the rectifier must be rotated. A clamping by pneumatic or hydraulic energy would require to be able to accompany this rotation by winding the pipes of the hydraulic or pneumatic supply, which is particularly complex to organize.

In particular, the center of the rectifier can not be used to pass such pipes since it is used for other functions in these operations.

Among hydraulically or pneumatically controlled clamping systems, there are systems for which the control triggers the disengagement of the system (document EP 1 310 331 A2 ).

GENERAL PRESENTATION OF THE INVENTION

An object of the invention is to solve the problems of the state of the art and to propose a system that does not have the aforementioned drawbacks.

More particularly, the invention proposes a clamping system comprising a clamping jaw mounted on the axis of a pneumatic or hydraulic jack, wherein said jack is of a structure which, when the supply of said jack in pneumatic or hydraulic energy is cut off, drives the clamping jaw towards its clamping position, supplying said jack with pneumatic or hydraulic energy opposing said clamping, characterized in that it comprises locking means of the jack when the clamping jaw is in the released position.

The proposed clamping system keeps the workpiece clamped when the pneumatic supply is cut off. This eliminates various needs for power, energy storage, etc.

Clamping is made very reliable and safe for the operator.

In particular, the clamping is made repetitive, regardless of the flange.

Because it is made permanent, the system also requires no or few maintenance operations.

• positionnement sur un banc d'intervention de brides comportant un système de bridage du type précité,
• positionnement du redresseur sur ledit banc,
• enlèvement des moyens de verrouillage du vérin situés au niveau de la virole extérieure,
• serrage d'au moins une bride par coupure de son alimentation pneumatique ou hydraulique.

The invention also proposes a method for sealing and / or injecting abradable onto the inner shell of a low-pressure turbomachine rectifier, characterized in that it comprises the following steps:

• positioning on a flange intervention bench comprising a clamping system of the aforementioned type,
• positioning the rectifier on said bench,
• removal of the locking means of the jack located at the outer ring,
• clamping at least one flange by cutting off its pneumatic or hydraulic supply.

It also proposes a tool for sealing and / or injecting abradable on the inner shell of a low-pressure turbomachine rectifier, characterized in that it comprises an intervention bench and at least one flange comprising such a system. clamping.

PRESENTATION OF FIGURES

• La figure 1 représente schématiquement en perspective un redresseur basse pression de turbomachine ;
• La figure 2 illustre schématiquement le principe d'un système énergisé à serrage positif conforme à un mode de réalisation possible de l'invention ;
• La figure 3 illustre en perspective un exemple de réalisation pour le système de bridage de la figure 2 ;
• La figure 4 illustre un exemple d'utilisation pour le bridage de la virole intérieure ou de la virole extérieure d'un redresseur basse pression de turbomachine.

Other characteristics and advantages of the invention will emerge from the description which follows, which is purely illustrative and nonlimiting, and should be read with reference to the appended figures in which:

• The figure 1 schematically shows in perspective a low-pressure turbomachine rectifier;
• The figure 2 schematically illustrates the principle of a positive clamping energized system according to a possible embodiment of the invention;
• The figure 3 illustrates in perspective an exemplary embodiment for the clamping system of the figure 2 ;
• The figure 4 illustrates an example of use for clamping the inner ferrule or outer ferrule of a low-pressure turbomachine rectifier.

DESCRIPTION OF ONE OR MORE MODES OF REALIZATION OR IMPLEMENTATION

The rectifier R illustrated on the figure 1 comprises an inner ring VI, an outer shell VE and blades A assembled by welding to the outer shell VE.

These blades A are integral with the inner ring VI through an abradable surface AB.

The deposition of this abradable surface is performed during sealing and injection operations requiring clamping of the outer shell VE and the inner ring VI on a support structure of a response bench.

For this purpose, the inner ferrule VI and outer ferrule VE are held at several points by means of reference flanges.

To do this, it is proposed to use permanent clamping systems of the type of the system 1 illustrated in FIG. figure 2 .

Such a clamping system is a system comprising one or more springs 2 exerting on the piston 3 of a jack 4 a force which is used to perform said clamping.

A hydraulic / pneumatic circuit 10 is provided, but only to ensure the loosening of the clamping system 1, no power supply being necessary for clamping.

In the schematic example illustrated on the figure 2 , one or more spring (s) 2 is (are) compressed (s) between the piston 3 and the bottom 5a of the body 5 of the cylinder 4. The piston 3 is integral with the axis 6 of the cylinder, which opens out of the body 5. At its end opposite the piston 3, said axis 6 is itself integral with a clamping jaw 7.

A cam 8 is provided to lock the clamping jaw 7 and the axis 6 in a disengaged high position (release position). For this purpose, said cam 8 cooperates with a groove 9 that has the axis 6 and wherein it is possible to engage said cam 8 when the jaw 7 is in the high position.

The positioning of the cam on the cylinder 4 or disengagement is for example made manually.

When the cam 8 and the groove 9 are disengaged, the springs 2 push back the piston 3 of the jack 4. Said piston 3 moves inside the body 5 of the jack 4. The jaw 7, which moves with the piston 3, is movable in the direction of the descent along the arrow D to clamp the workpiece to be clamped.

The loosening is obtained by supplying pneumatic energy to the circuit 10 along the arrow E. A force is exerted against the piston 3, which is movable in the direction of the rise along the arrow M inside said body 5 and compresses the springs 2.

When the hydraulic / pneumatic power is cut off, the springs 2 exert their compressive force, but the jaw 7 remains in its upper loosening position if the cam 8 has been engaged in the groove 9.

It may further be provided that the displacement of the piston 3 and the axis 6 inside the body 5 of the jack 4 is done in a helical movement to rotate the jaw 7 90 degrees on itself when it moves to the loosening position. Such a helical movement facilitates the disengagement of the workpiece to be clamped.

Moreover, as represented on the figure 3 , the body 5 of the cylinder 4 may be associated with different means 11 (clamping jaws for example) which allow to fix the system 1 on a given support with precision.

The figure 4 illustrates the use of clamping systems of the type of the system 1 which has just been described to achieve the positioning of the VI and VE ferrules of a rectifier R on an intervention bank B.

The different reference flanges 1 are first fixed in a precise manner on the B bench thanks to the fastening means 11 ( Figure 3 ) that they comprise, the flanges 1 and the bench B constituting part of the interventional equipment.

Then the rectifier R is placed on said bench B.

The locking cams of the reference flanges 1 located at the external ferrule VE are then removed.

These reference flanges 1 are then tightened on the outer shell VE by cutting off the pneumatic pressure in the circuit.

VE ferrule being thus clamped, it then proceeds to clamp the inner ferrule VI.

The rectifier R is thus maintained in position on the intervention bench B, the sealing operations are performed on the inner surfaces of the inner shell and in the openings thereof.

The sealing is done for example by depositing an RTV silicone. It allows to create a sealing of the track before injection of the abradable material itself.

The polymerization of the abradable material is then carried out on openings of the inner ferrule.

The unclamping / unlocking of the different flanges 1 is then ensured by putting the different flanges under hydraulic / pneumatic pressure.

When the different cams 8 are repositioned, the hydraulic / pneumatic pressure can be cut again.

The reference flanges 1 can then be removed.

When the flanges 1 are not used, the cams 8 can be disengaged in order to limit the biasing of the springs 2.

It is understood that the energy thus required for performing the clamping is low.

Furthermore, the clamping performed is particularly reliable and is not dependent on the level of hydraulic / pneumatic pressure provided by the circuits.

It is repetitive, the tightening being the same regardless of the flange.

It is realized quickly and is effortless for the user who carries out the clamping.

It does not require significant hydraulic / pneumatic energy storage.

It requires very little maintenance.

Claims (8)

1. A clamping system (1) including a clamping jaw (7) mounted on the rod (6) of a pneumatic or hydraulic ram (10), wherein said ram is a structure which, when supply to said ram of pneumatic or hydraulic energy is cut off, drives the clamping jaw toward its clamping position, supply to said ram of pneumatic or hydraulic energy opposing said clamping, characterized in that it includes means (8) of locking the ram when the clamping jaw is in the release position.
2. The clamping system according to claim 1, characterized in that said ram includes a piston and at least one compression spring which acts against the piston, the clamping jaw being linked to said piston and being displaced, to accomplish its clamping, under the compression force of said spring(s).
3. The clamping system according to one of claims 1 to 2, characterized in that the structure of the ram is adapted so that the displacement of the clamping jaw between its clamping and release positions occurs in a helical movement.
4. The clamping system according to claim 3, characterized in that the rotation of the clamping jaw between the clamping and release positions is 90°.
5. A method of sealing and/or injection of abradable material on the inner ferrule (VI) of a low-pressure guide vane (R) of a turbine engine, characterized in that it includes the following steps of:

   - Positioning, on a work bench, clamps including a clamping system according to one of the preceding claims,

   - positioning the guide vane on said bench (B),

   - removing the locking means of the ram located at the outer ferrule (VE),

   - clamping at least one clamp by cutting off its pneumatic or hydraulic supply.
6. The method according to claim 5, characterized in that the clamping of the outer ferrule is carried out, then the clamping of the inner ferrule.
7. The method according to one of claims 5 or 6, characterized in that, after the sealing and/or polymerization operations, the clamps are unlocked by pneumatic or hydraulic supply.
8. Tooling for sealing and/or injection of abradable material on the inner ferrule of a low-pressure guide vane of a turbine engine, characterized in that it includes a work bench and at least one clamp including a clamping system according to one of claims 1 to 4.

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