FASTENING OF A TURBINE BLADE WITH TREE-SHAPED ROOT IN A TURBINE ROTOR BY MEANS OF DEFORMABLE FIXATION WEDGE AND A SECURING ELEMENT

Abstract

 The invention relates to a fastening arrangement for a turbine blade (1) with tree-shaped root (10) in a rotor groove (20), wherein the root (10) at a radially inner side (11) comprises a recess (110). A deformable locking wedge (3) comprising a deformation groove (30) is inserted into the recess (110). The locking wedge (3) is in contact with a face (111) of the recess (110) and secured against axial displacement outwardly from the groove (20) by means of a securing element, namely a securing pin (4) detachably arranged in said rotor groove (20). Thus, the mechanical structure of the rotor groove (20) may be improved while preventing unwanted displacement of the blade (1) in the groove (20). The locking wedge (3) may comprise lamellas (31) for receiving the securing pin (4).

Description

Technical field

[0001] The invention relates to an arrangement of a turbine blade with a straight or circular tree-shaped root in a groove in a rotor of a turbine, in particular a steam or gas turbine.

[0002] The invention also relates to a turbine, in particular a steam or gas turbine, in which at least some of the turbine blades are arranged in this manner.

Background art

[0003] Several different types of arrangement and securing of a turbine blade with a straight or circular tree-shaped root in a groove in a turbine rotor are currently known. For example, U.S. 4,762,775 discloses an arrangement of a blade with a circular tree-shaped root where adjacent blades are interconnected by a shaped lock formed at the root base and the blade is secured by a pin which extends over the entire width of the root base of one blade to the root base of the adjacent blade. This pin is fixedly mounted in an aperture in the root base of the first blade and is loosely received in an aperture in the root base of the adjacent blade which allows the adjacent blades to vibrate independently of one another. The disadvantage of this solution is above all the fact that the apertures for the pins are provided in high stress regions of blades, and thus weaken their structure.

[0004] EP 1643082 describes an arrangement of a turbine blade with a circular tree-shaped root, in which a widening longitudinal groove is provided at the tip of a blade root. In the groove is mounted a wedge-shaped bent spring which is mounted with its end folds in radial grooves in a rotor, whereas its straight ends rest against the faces of the blade root, by which means it prevents the turbine blade from undesirable movement in the direction of the axis of the turbine rotor. The disadvantage of this solution is the limited capability of cushioning some of the forces acting on the blade, which may cause unwanted displacement of the blade in the groove. In addition, it is not possible to check the condition of the bent spring during installation and after it and confirm that it has not been damaged during installation. A further disadvantage is the fact that it is quite difficult to predefine the compressive force applied to each turbine blade and to make sure that the same compressive force is applied to all the turbine blades.

[0005] Furthermore, an arrangement of a turbine blade is known from practice in which a wedge is arranged in the bottom of a groove in a rotor to secure the turbine blade. A metal hook is arranged on the wedge towards the tip of the turbine blade root, whereby the opposite ends of the hook are curved to opposite sides, one of them being mounted in a transverse groove formed at the tip of the blade root, the other constituting a support surface for the outer face of the wedge. The drawback of this solution is a low level of cushioning some components of forces acting on the blade, which may cause unwanted displacement of the blade in the groove.

[0006] The aim of the invention is to provide an arrangement of a turbine blade with a straight or circular tree-shaped root in a groove in a turbine rotor, which would not suffer from the drawbacks of the types of arrangement which have been used so far.

[0007] In addition, the aim of the invention is a turbine in which at least some of the turbine blades are arranged in this manner.

Principle of the invention

[0008] The aim of the invention is achieved by an arrangement of a turbine blade with a straight or circular tree-shaped root in a groove in a rotor of a turbine, in particular a steam or gas turbine, whose principle consists in that at the tip of the root of the turbine blade at least from one side of the turbine blade a recess is formed from the outer side and within the space of the recess, between the tip of the root of the turbine blade and the bottom of the groove in the rotor, a locking wedge deformed in a controlled manner is inserted with an overlap in the radial direction, whereby the locking wedge is on its inner side over its entire width provided with a deformation groove and is in contact with the face of the recess at the tip of the root of the turbine blade and from the outer side is secured against axial displacement outwardly from the groove in the rotor by means of a securing element arranged demountably in the groove in the rotor or extending to the groove in the rotor.

[0009] To achieve mutual fitting and uniform surface contact, it is preferred that a recess with a bearing surface for the locking wedge is provided in the bottom of the rotor groove.

[0010] In a preferred embodiment of an arrangement of a turbine blade in a groove in a turbine rotor, the securing element is formed by a securing pin, which is arranged in a radial aperture in the bottom of a groove in the rotor, and the locking wedge is provided with a means which extends to the space between the pin and the tip of the root of the turbine blade and secures the securing pin against unwanted movement in the radial direction. Such a means is, for example, a pair of lamellas, which, after installation, are bent to the space above the top of the securing pin.

[0011] To facilitate the assembly and, in case of need, also disassembly, it is advantageous if the locking wedge is provided with an elevated bearing surface on its lower and/or upper surface, whereby the radial overlap of its mounting in the space between the tip of the root of the turbine blade and the bottom of the rotor groove is realized only in the space of the bearing surface/surfaces.

[0012] In addition to the arrangement of the turbine blade, the aim of the invention is also achieved by a turbine, especially a steam or gas turbine, having turbine blades with a straight or circular tree-shaped root mounted in a groove in the turbine rotor, whose principle consists in that at least some turbine blades are arranged in the manner according to the invention.

Description of drawings

[0013] In the drawings, Fig.1 schematically shows a part of a sectional view of a steam turbine rotor with turbine blades arranged in exemplary embodiment of the arrangement of the turbine blade according to the invention with a locking wedge and a securing pin; Fig. 2 schematically shows a detail of this embodiment of the arrangement of the turbine blade and Fig. 3 schematically shows a view of the locking wedge and the securing pin of Figure 2 in the direction of the axis of the turbine rotor.

Examples of embodiment

[0014] An arrangement of a turbine blade in a groove in a rotor according to the invention will be further described with reference to a variant of arrangement of terminal turbine blade of a steam turbine with a circular tree-shaped root, which is schematically shown in different views in Fig. 1 to Fig. 3. However, as is obvious to the person skilled in the art, this arrangement can also be used without further adaptations for the arrangement of a moving blade with a straight tree-shaped root, or the elements used may be created and/or arranged in a manner different than shown and described.

[0015] The turbine blade 1 of the turbine is provided in its lower part with a well-known tree-shaped root 10 with conical contact surfaces 100. The tree-shaped root 10 is arranged in a groove 20 of a corresponding shape in the turbine rotor 2. To secure the turbine blade 1 against undesirable displacement in the direction of the axis of the rotor 2 of the turbine (arrow A), recesses 110 are formed from the outer side on both sides of the tip 11 of the tree-shaped root 10, that is, from the side of the inlet and outlet, and within the space of these recesses 110 between the tip 11 of the root 10 of the turbine blade 1 and the bottom 21 of the groove 20 in the rotor 2 locking wedges 3 deformed in a controlled manner are inserted, with overlap in the radial direction. These locking wedges 3 are on their inner side along their entire width provided with a deformation groove 30, which increases their deformability. The locking wedges 3 are in contact with the faces 111 of the recesses 110. Preferably, but not necessarily, the deformation grooves 30 are widening continuously towards the end of the locking wedges 3. From the outer side, the locking wedges 3 are secured against unwanted movement in the direction of the axis of the turbine rotor 2 by a securing element demountably arranged in the groove 20 in the rotor 2 or extending to the groove 20 in the rotor 2. In the shown variant of embodiment, the securing element is a securing pin 4 arranged in a radial aperture 40 formed in the bottom 21 of the groove 20 in the rotor 2. Preferably, the locking wedge 3 is on the outer side against which rests the securing pin 4 provided with a suitably shaped bearing surface, which is rounded in the shown variant of embodiment. Preferably, it is provided at the same time with a means which extends to the space between the securing pin 4 and the surface of the recess 110 and secures the securing pin 4 against undesirable movement in the radial direction (arrow B). In the illustrated variant of embodiment, this means is formed by a pair of lamellas 31 arranged on the outer side of the locking wedge 3. Between the lamellas 31, there is sufficient space for insertion of the securing pin 4 into the radial aperture 40 in the bottom 21 of the groove 20 in the rotor 2. After insertion of the securing pin 4, these lamellas 31 are bent towards each other and above the top of the securing pin 4. In other embodiments not shown, a securing means can be, for example, a suitable rigid projection on the outer side of the locking wedge 3, or, alternatively, the locking wedge 3 and the securing pin 4 may be connected by a suitable shaped lock or a connecting element, such as a bolt, a pin, etc. The illustrated variant in which the locking wedge 3 is secured from the outer side by the securing pin 3 seems to be the most appropriate in terms of manufacturing, mounting and reliability, but in other embodiments other structural elements and measures can be used - for example, as a securing element it is possible to use a bolt which passes from the outer side askew into a skew aperture in the bottom 21 of the groove 20 in the rotor 2, etc. Alternatively, the securing pin 4 can be inserted in an aperture arranged in the wall of the groove 20 in the rotor 2 such that it extends directly or askew at least over a part of the width of the groove 20, etc.

[0016] In the embodiment shown, the locking wedge 3 is provided with an elevated contact surface 32 on its upper surface, whereby radial overlap in the arrangement of the locking wedge 3 in the space between the tip 11 of the root 10 of the turbine blade 1 and the bottom 21 of the groove 20 in the rotor 2 only occurs on this contact surface 32. However, this embodiment is not a necessary condition and the elevated contact surface 32 can be formed in other variants of embodiment also or only on the lower surface of the locking wedge 3. In other variants of embodiment, the contact surface 32 is formed by the entire upper and/or by the lower surface of the locking wedge 3.

[0017] In order to ensure mutual fitting and uniform surface contact, it is preferable, but not necessary, if a recess 210 is provided in the bottom 21 of the groove 20 in the rotor 2 with a bearing surface for the locking wedge 3.

[0018] In the illustrated variant of embodiment, the locking wedge 3 is on its inner side, on the upper and lower surfaces, provided with a chamfer 33, which facilitates the insertion of the locking wedge 3 into the space between the tip 11 of the root 10 of the turbine blade 1 and the bottom 21 of the groove 20 in the rotor 2. In other variants, however, the chamfer 33 may be formed only on one surface of the locking wedge 3, or it may be formed on at least one side surface of the locking wedge 3, or it does not have to be formed at all.

[0019] Due to its location, the locking wedge 3 cushions components of forces acting on the turbine blade 1 on its surface which is in contact with the face 111 of the recess 110 and reliably prevents displacement of the turbine blade 1 in the direction of the axis of the turbine rotor 2. Moreover, due to its controlled deformation, occurring during insertion, the locking wedge 3 pushes the contact surfaces 100 of the root 10 of the turbine blade 1 into contact with the respective surfaces of the groove 20 in the rotor 2, thereby fixing the turbine blade 1 also in the radial direction. Compared to the known method of securing, this radial compressive force is lower and the turbine blade 1 is not inserted in the rotor 2 on tight.

[0020] The arrangement and securing of the turbine blades 1 is then performed in a position with the paddle of the turbine blade 1 directed downwards, whereby each turbine blade is inserted into the respective groove 20 in the rotor 2 and aligned radially according to the blading plan. Once aligned axially, the locking wedge 3 is inserted into the space between the tip 11 of the root 10 of the turbine blade 1 and the bottom 21 of the groove 20 in the rotor 2, until it contacts the face 111 of the recess 110. Then the securing element is arranged and, if necessary, it is secured against unwanted movement in the radial direction - in the illustrated variant of embodiment, by bending the lamellas 31 on the outer side of the locking wedge 3 above it, etc.

[0021] The described method of the arrangement and securing of a turbine blade 1 can be combined with other well-known methods, when, for example, on the opposite sides of one turbine blade 1 different methods are used.

[0022] In the case of a turbine, especially a steam or gas turbine, at least a part of the moving blades 1 arranged in the grooves 20 in the rotor 2 are arranged in this manner. This applies particularly, but not necessarily, to terminal turbine blades 1.

List of references

[0023] 

1

turbine blade

10

tree-shaped root of the turbine blade

100

contact surface of the tree-shaped root of the turbine blade

11

tip of the tree-shaped root of the turbine blade

110

recess at the tip of the tree-shaped root of the turbine blade

111

face of the recess at the tip of the tree-shaped root of the turbine blade

2

rotor of the turbine

20

groove in the rotor of the turbine

21

bottom of the groove in the rotor of the turbine

210

recess in the bottom of the groove in the rotor of the turbine

3

locking wedge

30

deformation groove of the locking wedge

31

lamella of the locking wedge

32

contact surface of the locking wedge

33

chamfer of surface of the locking wedge

4

securing pin

40

radial aperture for the securing pin

Claims

1. An arrangement of a turbine blade (1) with a straight or circular tree-shaped root (10) in a groove (20) in a rotor (2) of a turbine, in particular a steam or gas turbine, characterized in that at the tip (11) of the root (10) of the turbine blade (1) at least from one side of the turbine blade (1), a recess (110) is formed from the outer side and within the space of the recess, between the tip (11) of the root (10) of the turbine blade (1) and the bottom of the groove (20) in the rotor (2) a locking wedge (3) deformed in a controlled manner is inserted with an overlap in the radial direction, whereby the locking wedge (3) is on its inner side over its entire width provided with a deformation groove (30) and is in contact with a face (111) of the recess (110) at the tip (11) of the root (10) of the turbine blade (1) and from the outer side is secured against the axial displacement outwardly from the groove (20) in the rotor (2) by means of a securing element arranged demountably in the groove (20) in the rotor (2) or extending to the groove (20) in the rotor (2).

2. The arrangement according to claim 1, characterized in that a recess (210) for the locking wedge (3) is formed in the bottom (31) of the groove (20) in the rotor (2).

3. The arrangement according to claim 1, characterized in that the securing element is formed by a securing pin (4) arranged in a radial aperture (40) in the bottom (21) of the groove (20) in the rotor (2) and the locking wedge (3) is provided with a means which extends to the space between the securing pin (4) and the tip (11) of the root (10) of the turbine blade (2) and secures the securing pin (4) against movement in the radial direction.

4. The arrangement according to claim 3, characterized in that the means extending to the space between the securing pin (4) and the tip (11) of the root (10) of the turbine blade (1) and securing it against movement in the radial direction is a pair of lamellas (31) arranged on the outer side of the locking wedge (3).

5. The arrangement according to claim 1, 3 or 4, characterized in that the locking wedge (3) is provided on its lower and/or upper outer surface with an elevated contact surface (32), whereby the radial overlap of its arrangement in the space between the tip (11) of the root (10) of the turbine blade (1) and the bottom (21) of the groove (20) in the rotor (2) of turbine is realized only in the space of the contact surface/surfaces (32).

6. A turbine, especially a steam or gas turbine, having turbine blades (1) with a straight or circular tree-shaped root (10) arranged in a groove (20) in a rotor (2) of a turbine, characterized in that at the tip (11) of the root (10) of at least some turbine blades (1), a recess (110) is formed from the outer side and within the space of the recess, between the tip (11) of the root (10) of a turbine blade (1) and the bottom of the groove (20) in the rotor (2) a locking wedge (3) deformed in a controlled manner is inserted with an overlap in the radial direction, whereby the locking wedge (3) is on its inner side along its entire width provided with a deformation groove (30) and is in contact with the face (111) of the recess (110) at the tip (11) of the root (10) of the turbine blade (1) and from the outer side is secured against the axial displacement outwardly from the groove (20) in the rotor (2) by means of a securing element arranged demountably in the groove (20) in the rotor (2) or extending to the groove (20) in the rotor (2).

7. The turbine according to claim 6, characterized in that a recess for the locking wedge (3) is formed in the bottom of the groove in the rotor.

8. The turbine according to claim 6, characterized in that the securing element is formed by a securing pin (4) arranged in a radial aperture (40) in the bottom (21) of the groove (20) in the rotor (2) and the locking wedge (3) is provided with a means which extends to the space between this securing pin (4) and the tip (11) of the root (10) of the turbine blade (2) and secures it against movement in the radial direction.

9. The turbine according to claim 8, characterized in that the means which extends to the space between the securing pin (4) and the tip (11) of the root (10) of the turbine blade (1) and secures it against radial movement is a pair of lamellas (31) arranged on the outer side of the locking wedge (3).

10. The turbine according to claim 6, 8 or 9, characterized in that the locking wedge (3) is on its lower and/or upper outer surface provided with an elevated contact surface (32), whereby the radial overlap of its arrangement in the space between the tip (11) of the root (10) of the turbine blade (1) and the bottom (21) of the groove (20) of the rotor (2) is realized only in the space of the contact surface/surfaces (32).

Drawing