EP2066871B1 - Securing apparatus of a turbine blade - Google Patents

Abstract

The apparatus (10) has a pressurizing medium provided for exerting a pressure force on a blade root (14) in a radial direction (37). The apparatus is designed such that the pressure force is exerted by a rotary movement of a rotary unit (31). A locking unit is arranged at the rotary unit such that a rotation of the rotary unit leads to locking of the locking unit. The locking of the locking unit leads to movement of pressure bars (36, 38). The apparatus is provided for installation of a groove in the blade root and/or a rotor.

Description

The invention relates to a securing device for the radial securing of a turbine blade, wherein a pressure means for exerting a compressive force on a turbine blade root is provided in the radial direction.

Blade fasteners of the above type are typically used to secure blades to a rotor of a turbine which revolve at high speed as the rotor rotates. Due to the fast rotation of the rotor, the associated blades are subjected to high centrifugal force. The blade root of the blades is therefore exposed to high forces and is strongly forced radially outward in the groove on the blade holder. In addition, the blades are exposed to strong vibration loads, so that it can come to the groove to mechanical damage, material fatigue, corrosion and migration of the blade root within the groove. For fixing the blade root within the groove, various solutions such as metal wedges, spring washers or sealing pieces are known. Although metal wedges produce locking of the associated blade root within a groove both axially and radially, with large blades it is difficult with such metal wedges that sufficient holding forces are generated in the radial direction during the rotation of the blade. Disc springs only generate radial holding forces and require additional effort for a locking in the longitudinal direction of the associated groove. Furthermore, complex measurements are required for disc springs during assembly. As a piece of sealing always two parts must be provided, the assembly beyond partially requires the processing of the parts by hand.

The FR 2 323 908 discloses a blade guard with a wedge-shaped pressure means.

In the JP 59 192801 discloses a movable over a screw blade guard.

The US 2,846,183 discloses a blade armature acting by means of spring forces.

The US 3,720,481 discloses a safety device for radial securing of a blade according to the preamble of claim 1.

The invention has for its object to provide a blade mounting a turbine in which over a long period of operation, a precise and low-vibration mounting of blades is ensured in associated blade holders.

The object is solved by the characterizing features of claim 1, by a securing device for radial securing of a turbine blade, wherein a pressure means for exerting a compressive force on a turbine blade root in the radial direction and a rotating means is provided and the securing device is designed such that by a rotational movement of the rotating means the pressure force is exercisable.

There are provided two displacement means which are designed to be movable relative to one another. Since, as already mentioned, a high force can be transmitted via a rotary movement, it is advantageous if two displacement means can be provided, which can be formed by the rotational movement to each other. As a result, the transferable pressure force on the turbine blade root in the radial direction increases even further.

The securing device is first inserted into a groove. In a next step, the rotating means is set in a rotational movement. Due to the rotational movement of the rotating means, the pressure medium is enabled to exert a compressive force. The compressive force finally achieves the effect that the turbine blade in radial Direction is being moved. As the blade root is inserted into blade holders, counter forces occur. The combination of compressive force and counterforce causes the turbine blade to be effectively held in the blade holder.

According to the invention it is proposed to generate the pressure force from the outside by a rotational movement of the rotating means. This is a significant design advantage, because now it is possible to insert a securing device without major resistance in a groove. The securing device can thereby be moved exactly to the intended places. The pressure force can then be generated easily by a rotary rotational movement of the rotating means.

Another advantage of the invention is that by a rotational movement of the rotating means, which points in an opposite direction, the pressure force can be reduced again and thus the securing device can be released from the turbine blade, resulting in a non-destructive expansion of the securing device.

Advantageous developments are specified in the subclaims.

It is essential to the invention that the pressure medium has a movably arranged pressure bar. This makes it possible to design the securing device by a structurally simple construction.

Furthermore, a displacement means is arranged on the rotation means such that a rotation of the rotation means leads to a displacement of the displacement means. This is a simple variant for moving a displacement means, which eventually leads to a movement of the pressure beam. Since very high forces can be transmitted via rotational movements, a very high force can be transmitted to the pressure medium via the displacement means and the rotation means, which in turn leads to a high pressure Compressive force on the turbine blade root in the radial direction leads.

In an advantageous development of the pressure bar is designed to be elastic. This makes it possible for a pressure force to be exerted on the turbine blade root in the radial direction during operation. In general, a high centrifugal force acts on the turbine blade root in the radial direction during operation. This means that a rigidly set pressure force on the turbine blade root would be lower. By a resilient pressure beam, the pressure force on the turbine blade root is maintained over a certain distance, although the turbine blade root moves away from the pressure beam.

In a further advantageous development, the securing device is provided for installation in a groove in a blade root and / or in a rotor.

FIG 1

eine teilweise aufgebrochene perspektivische Ansicht eines ersten Ausführungsbeispiels einer erfindungsgemäßen Schaufelbefestigung,

FIG 2

eine perspektivische Darstellung eines Turbinenschaufelfuß mit der Sicherungsvorrichtung,

FIG 3

eine perspektivische Darstellung der Sicherungsvorrichtung,

FIG 4

eine Querschnittsansicht eines Turbinenschaufelfußes mit der Sicherungsvorrichtung,

FIG 5

eine vergrößerte Darstellung der Sicherungsvorrichtung aus FIG 4,

FIG 6

eine perspektivische Darstellung der Sicherungsvorrichtung,

FIG 7

eine Querschnittsansicht einer nicht zur Erfindung gehörenden alternativen Ausführungsform einer Sicherungsvorrichtung,

FIG 8

eine perspektivische Darstellung der alternativen Ausführungsform der Sicherungsvorrichtung.

An exemplary embodiment of a blade attachment according to the invention will be explained in more detail below with reference to the attached schematic drawings. Show it:

FIG. 1

a partially broken perspective view of a first embodiment of a blade attachment according to the invention,

FIG. 2

a perspective view of a turbine blade root with the safety device,

FIG. 3

a perspective view of the securing device,

FIG. 4

a cross-sectional view of a turbine blade root with the safety device,

FIG. 5

an enlarged view of the securing device FIG. 4 .

FIG. 6

a perspective view of the securing device,

FIG. 7

a cross-sectional view of a not belonging to the invention alternative embodiment of a securing device,

FIG. 8

a perspective view of the alternative embodiment of the securing device.

In the figures, a blade attachment 10 is shown by a turbine, not further illustrated, in which a blade root 14 is supported on a blade holder 12 on a rotor of the turbine. The blade root 14 is part of a blade 16, from which an airfoil 18 protrudes substantially radially from the shaft and thus perpendicularly from the blade root.

The blade root 14 is designed with a fir tree-like profile 20 which is inserted into a curved groove 22 formed in the blade holder 12. At the bottom of the groove 22 is located between the inserted blade root 14 and the blade holder 12 a substantially over the entire length of the groove 22 extending recess 24 in the blade root 14, in which a securing device 30 is inserted.

The securing device 30 comprises, as in FIG. 3 The rotating means 31 can be moved in both rotational directions (clockwise or counterclockwise). The rotating means 31 further includes a first thread 32 and a second thread 33 counter-clockwise made to the first thread 32. On the first thread 32, a first displacement means 34 is arranged. The displacement means 34 has a bore into which the rotation means 31 projects. The displacement means 34 therefore comprises a complementary thread.

Accordingly, a second displacement means 35 is arranged on the second thread 33, which, like the first displacement means 34 has a bore with a corresponding thread. By rotating the rotation means 31, the displacement means 34 and 35 are either moved toward or away from each other, depending on which rotational direction the rotation means 31 is moved in. Between the first displacement means 34 and the second displacement means 35, a pressure medium designed as a pressure bar 36 is arranged. The pressure bar 36 is located between the first displacement means 34 and the second displacement means 35. Rotation of the rotating means 31 results in movement of the pressure means in a radial direction 37.

The pressure bar 36 may be formed U-shaped, wherein the two legs can be arranged in each case left and right of the rotating means 31. Conveniently, a second pressure bar 38, which may also be U-shaped, is disposed between the first displacement means 34 and the second displacement means 35.

In the FIG. 2 the bucket 16 can be seen in the installed state. The securing device 30 is arranged in a groove 39, wherein of the securing device 30 substantially only the rotating means 31 can be seen.

In the FIG. 4 a cross section through the blade 16 and the blade holder 12 is shown. The securing device 10 is mounted in a groove 39. By rotating the rotation means 31, the two pressure beams 38 and 36 are moved in the radial direction 37, whereby a force is exerted by the blade holder 12 on the blade root 14, thereby the turbine blade 16 is held firmly to the blade holder 12.

In the FIG. 5 is an enlarged view of the securing device 30 of the FIG. 4 shown. The operation and assignment of the reference numerals applies accordingly. The pressure bars 36 and 38 may be disposed at their ends in retaining grooves 40 and 41. This prevents the safety device from slipping out of the groove 39.

In the FIG. 6 is a perspective view of the securing device 30 can be seen. The rotating means 31 may be implemented as a square 44 at one end. As a result, tools can be easily arranged on the rotating means 31, so that a rotational movement can be transmitted to the rotating means 31.

In the FIG. 7 is an alternative not belonging to the invention embodiment of the securing device 10 can be seen. The difference to that in the FIGS. 2 to 6 described securing device 30 is that the securing device 30 is executed so to speak as a jack. For this purpose, the securing device 30 has a first upper bar 50 and a second upper bar 51, which is connected at one end to the first displacement means 46 and the second upper bar 51 is connected to the second displacement means 48. Accordingly, the securing device 30 has a first lower rod 52 and a second lower rod 53. The first lower rod 52 is connected at one end to the first displacement means 46, whereas the second lower rod 53 is connected at one end to the second displacement means 48.

The first upper rod 50 and the second upper rod 51 are connected at their other end together to a fitting key 54. Correspondingly, the first lower rod 52 and the second lower rod 53 are connected at their end to a lower fitting wedge 55. A rotation of the rotating means 31 leads via the oppositely formed threads 32 and 33 to a movement of the displacement means 46 and 48 to each other or away from each other. When the displacement means 46 and 48 are moved toward each other, the first upper rod 50 and the second upper rod 51 are moved in the radial direction, and the first lower rod 52 and the second lower rod 53 are moved in the radial direction 37. The pass wedges 54 and 55 will be Thus, on the one hand pressed against the blade root 14 and the other against the blade holder 12. The upper wedge 54 is located on the blade root 14 in a corresponding groove 56. The lower wedge 55 is applied to the blade holder in a corresponding groove 57 at. A displacement of the securing device 10 in the axial direction is thus effectively prevented.

In the FIG. 8 is a perspective view of the securing device of the FIG. 7 to see. The same reference numerals have the same meaning and the effect described. The first upper bar 50, the second upper bar 51, the first lower bar 52, and the second lower bar 53 may be attached to the shifting means 46, shifting means 48, to the wedge 54, as well as to the lower fitting wedge 55, by conventional connecting means such as screws or rivets be attached.

Claims (4)

1. Securing device (30) for radially securing a blade (16), a pressure means being provided for exerting a pressure force in the installed state upon a blade root (14) in the radial direction (37), a rotation means (31) being provided, and the securing device (30) being designed in such a way that the pressure force can be exerted as a result of a rotational movement of the rotation means (31) by means of a thread (32, 33), with two displacement means (34, 35) designed to be movable with respect to one another, characterized in that the pressure means has a movably arranged pressure beam (36, 38), a displacement means (34, 35) being arranged on the rotation means (31) in such a way that rotation of the rotation means (31) leads to a displacement of the displacement means (34, 35), the displacement of the displacement means (34, 35) leading to a movement of the pressure beam (36, 38).
2. Securing device (30) according to Claim 1, the rotation means (31) having a thread (32, 33) and the displacement means (34, 35) having a counterthread.
3. Securing device (30) according to Claim 2, the pressure beam (36, 38) being elastic.
4. Securing device (30) according to one of the preceding claims, the securing device (30) being intended to be installed in a groove (39) in a blade root (14) and/or in a rotor.

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