EP1944466A1 - Coupling of two rotor blades - Google Patents

Abstract

The rotor blade (2) has cover plates (12) at an upper end of a turbine blade (2a), and a coupling element (4). A gap is provided between individual cover plates, where the cover plates have a recess (18) at a side, which faces the adjacent cover plates. The recess forms a hollow space together with the recess of the adjacent cover plates, where the hollow space is designed for receiving the coupling element. The coupling element and recess are designed in such a manner that the coupling element is fitted into the hollow space with active game. An independent claim is also included for a device for coupling two rotor blades.

Description

The invention relates to a blade with a cover plate at an upper end of an airfoil. In addition, the invention relates to a device for coupling two blades, comprising two cover plates of the blades, which are spaced from each other by a gap and each having a recess into which a gap bridging the coupling element is inserted.

In turbomachines, particularly steam turbines, blades of a first row of blades are hit by high-velocity gas or superheated steam, which drives the blades to momentum by momentum transfer. If steam turbines are to operate a large portion of their operating time in a partial load range, they usually include a control stage for improving the efficiency. In this, the hot steam from several valves is simultaneously directed to the first row of blades. At a partial load operation, the steam flow is not uniformly reduced in all valves, but it is successively throttled individual valves, with other valves are fully flowed through with superheated steam.

During a rotation of the blades, these move through the steam flows from the differently controlled valves, so that the blades go through sectors of different vapor flows within a revolution. The consequent load change on the blades in the axial direction and tangential direction can stimulate them to vibrate through which the blade material is heavily stressed. Generally meets the load change frequency with a natural vibration of the blade together, so there is resonance, which can lead to the destruction of the blades.

To combat these dangerous vibrations blades of a control stage are usually performed very strong by a thickening of the blade profile. However, this gain can significantly degrade the efficiency of the turbomachine. From the CH 666 326 A5 It is known to damp the blade vibrations by means of a damper wire which is passed through cover plates of the rotor blades and connects the rotor blades in packages. The disadvantage here has been found that the damper wire is clamped form-fitting and is subjected to thermal expansion of the blade ring with a bending stress and shear stress, which can lead to a rupture of the damper wire.

It is the object of the present invention to provide a highly durable device for coupling two blades, with which a swinging of the blades can be effectively reduced.

This object is achieved by a device for coupling two blades of the type mentioned, in which the coupling element rests on tangentially to each other angled contact surfaces on the cover plates and the cover plates is tangentially supported against each other. By supporting the sector load on several, especially all blades are distributed and is collected by the entire blade ring. In the effect of centrifugal force during operation of the blades, which presses the coupling element in the recesses radially outward, the coupling element - compared to a conventional clamped wire - statically determined over the contact surfaces on the cover plates and the cover plates in Press tangential direction apart, whereby the mutual support and transfer of tangential forces is achieved.

mit ½ dω = Umfangsgeschwindigkeit.The invention is based on the consideration that a tangential force F _t on a blade in a partial load operation depends on the power P of the partial load operation, the angular velocity ω of the blade and the circular arc ε of the inflow segment, from which the superheated steam flows onto the blade: $$F_i\square \frac{\mathrm{<figure-callout\; id="2"\; label="P\; d"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">P\; </figure-callout>}}{\frac{d}{}}$$

with ½ dω = peripheral speed.

Based on the fact that the blade is loaded in the inflow segment within a circular arc ε by pressure of the superheated steam and outside the Anströmsegments not, the blade is exposed within a revolution of an approximately rectangular force function. A Fourier transformation of this rectangular force function shows that above all low-frequency vibrations of the turbine assembly are excited. Frequency calculations have shown that a stiffening of the blades at the blade tips or in the region of the cover plates lead to a shift of the natural oscillations to higher natural frequencies, so that these higher-frequency natural oscillations are less excited by the sectional flow of superheated steam.

The invention is therefore based on the further consideration that a mechanical load on the blades not only by a vibration damping by energy extraction by Friction is useful, but by a stiffening in the radially outer region, whereby a vibration-exciting energy transfer from superheated steam can be significantly reduced to the blades. Any existing friction elements can be spared in their load and wear can be reduced.

Due to the indirect support on the coupling elements used can be dispensed with a direct support of the cover plates against each other, whereby an expensive processing of the cover plates for the purpose of direct support is avoided. In addition, abrasion of contact surfaces and assembly costs can be reduced. The recesses are expediently introduced into mutually facing sections of the cover plates and are advantageously facing each other.

The coupling element rests on tangential to each other angled contact surfaces on the cover plates, wherein the Anwinkelung may be small, but should always be> 0 °, in particular> 5 °. It can go up to 180 °, so that the contact surfaces are exactly opposite, parallel surfaces. The contact surfaces can merge seamlessly, e.g. as part of a spherical surface or a surface of an ellipsoid of revolution. They can both be part of the contact element or each contact surface can be part of one of the recesses. The coupling element can support the two cover plates by a tangential positive connection with the cover plates against each other.

Advantageously, the recesses are bag-shaped. As a result, the recesses can be easily made with contact points for tangential support.

In a further advantageous embodiment of the invention, the recesses each comprise an obliquely oriented to the tangential direction contact surface for the mutual interaction on both sides simultaneous contact with the coupling element. At a pressure of the cover plates against each other, the coupling element can push away the contact surface a little bit obliquely elastic, whereby a hard beating cushioned or can be completely prevented. In addition, the coupling element can be pushed deeper into the recess by the pressure, whereby a slight damping by friction is made possible. An oblique orientation to the tangential direction is an orientation with an angle greater than 5 °, in particular greater than 10 ° to the tangential direction.

In a further advantageous embodiment of the invention, the two recesses form a radially tapering inner wedge in the common interaction. A pressed by the centrifugal force to the outside coupling element can thus achieve a wedge effect, which presses the cover plates against each other and thus form a stable association. The radial direction can be seen in relation to the blades.

In particular, oblique contact surfaces can be easily produced when the recesses are tapered inward. The recesses may be conical, whereby a simple production can be achieved. Also conceivable are round or spherical recesses.

A simple production of the coupling element combined with a good support and damping effect can be achieved if the coupling element is conically shaped on both sides in the tangential direction.

The supporting and damping effect can be further improved if the recesses conical with a Inner cone angle are executed and an outer cone angle of the coupling element is greater than the inner cone angle.

If the coupling element abuts against a contact surface of the recess with an edge or if an edge of the recess rests against an outer surface of the coupling element, then there is the risk that a shoulder is incorporated into the contact surface or outer surface by non-elastic deformation, which results in desired mobility of the contact surface Counteracts coupling element in the recess. Such a risk can be reduced or eliminated if the coupling element has a contact surface convexly curved in the direction of the recess interior for engagement with an inner surface or contact surface of a recess. For example, the coupling element can be designed as an ellipsoid of revolution or a part thereof.

A good suspension and damping of the blades can be achieved when the coupling element linearly in the recess, in particular in both recesses, rests. In particular, both the recess and the coupling element are rotationally symmetrical. The contact between the two is expediently annular, in particular circular, around the coupling element.

An undesirable shouldering on the coupling element can be avoided if the recess has an outer edge which is spaced from the coupling element by a gap. A contact between the coupling element and a contact surface of the recess may be a distance away from the edge of the contact surface. In particular, both recesses are identically shaped.

In order to be able to absorb a sufficient force between the two cover plates, the coupling element must have a corresponding one Have size. As a result, a thickening of the cover plates in the region of the recesses may be necessary. A radially outwardly directed thickening makes it difficult to attach structures to the radially outer side of the cover plate, which are provided to a seal between the cover plate and the turbine housing. An arrangement of a coupling element between the cover plates without thickening can be achieved if the coupling element has a longitudinal direction which is oriented in a gap longitudinal direction, in particular in an axial gap longitudinal direction, which can be tilted at a rhomboid angle to the axial direction of the blade. The gap longitudinal direction extends between the cover plates. It can be achieved an extended support in the form of a surface or line with a narrow in the radial direction of the blade recess.

Particularly simple to manufacture and inexpensive, the coupling element may be, if it is cylindrical.

If the recess is a groove, in particular corresponding to the coupling element, then it can easily be produced in the cover plate. Advantageously, the groove is closed at one end by a limiting element and open at the other end. By the limiting element from falling out of the coupling element can be prevented from the groove. In the open side, a corresponding limiting element of the adjacent cover plate engage and secure it against falling out of the coupling element.

A good sealing of the cover plate against a turbine housing can be facilitated if the cover plate has a bump-free radial outer surface, in particular a cylindrical radial outer surface. sealing Structures can be placed on the outer surface without complex adaptation.

Blades with the coupling element according to the invention are easier to use in the radial direction of a blade holder of a rotor than in the axial direction, for example, with known Christmas tree connections. For this purpose, the device advantageously comprises two blade roots of the blades with a connecting means for radial insertion into a blade holder of a rotor. In particular, the blade root or its connecting means is held by a tapping on the blade holder.

The invention is also directed to a blade ring for a turbomachine having a bandage of blades, wherein each adjacent cover plates of the blades are supported by a device as described above in operation tangentially against each other. It can support the entire blade ring in itself and a load of a steam steel on one or a few blades can be distributed over the entire blade ring.

The invention will be explained in more detail with reference to exemplary embodiments, which are illustrated in the drawings.

• FIG 1 bis 3 zwei Laufschaufeln mit einem Kopplungselement jeweils in einer teilgeschnittenen Ansicht von vorne, von der Seite und von oben,
• FIG 4 eine Detaildarstellung aus FIG 1,
• FIG 5 eine Detaildarstellung mit einem alternativen Kopplungselement,
• FIG 6 zwei andere Laufschaufeln mit shärischen Ausnehmungen und einem alternativen Kopplungselement,
• FIG 7 die Laufschaufeln aus FIG 5 mit einem weiteren Kopplungselement und
• FIG 8 bis 10 zwei weitere Laufschaufeln mit einem zylindrischen Kopplungselement jeweils in einer teilgeschnittenen Ansicht von oben, von der Seite und von vorne.

Show it:

• 1 to 3 two blades with a coupling element in each case in a partially sectioned view from the front, from the side and from above,
• FIG. 4 a detailed view FIG. 1 .
• FIG. 5 a detailed representation with an alternative coupling element,
• FIG. 6 two other blades with shallow recesses and an alternative coupling element,
• FIG. 7 the blades off FIG. 5 with a further coupling element and
• FIGS. 8 to 10 two further blades with a cylindrical coupling element in each case in a partially cutaway view from above, from the side and from the front.

1, FIG. 2 and FIG. 3 each show a schematic representation of a section of a blade ring of a blade row of a control stage of a steam turbine. Shown are two identical blades 2, which are supported by a centrifugally urged radially outward coupling element 4 in operation together. FIG. 1 shows the rotor blades 2 in a sectional view in the axial direction 8 of the rotor of the steam turbine, FIG. 2 in the tangential direction 6 and FIG. 3 in a partially sectioned view from radially outside.

Blades 2 each include a blade root 10, an airfoil 2a, and a top plate 12 which are integrally connected together by a blade 14 for generating rotation of the blade row.

The cover plates 12 each have a cylinder-segment-shaped formation 16 radially outward, in the tangential direction 6 on both sides an inwardly tapering, bag-shaped recess 18 is introduced in the form of a cone. Alternatively, cylindrical recesses are conceivable. Two mutually facing recesses 18 each form a cavity 18 a, in which a coupling element 4 is inserted. In this way, between all the blades 2 of the Blade ring each used a coupling element 4, so that all the blades 2 of the blade ring are supported against each other. The support takes place during operation by means of the centrifugal force to the outside pressed coupling element 4, which is pressed tangentially to each other when moving the cover plates 12 to radially inward. This is achieved in that the opposing recesses 18 in common interaction form an inner wedge tapering in the radial direction, by the pushing together of which the coupling element 4 is pressed radially inward. Conversely, the coupling element 4, when urged by the centrifugal force to the outside, acts like a wedge, which presses apart the two cover plates 12 by the wedge effect of the tangential positive connection. As a result, the entire blade ring can be stabilized in itself.

An impressions of the coupling element 4 in the recesses 18 is as far as possible until the coupling element 4 annularly abuts the edges of the recesses 18, as in FIG. 2 is shown. This position can take it out of operation of the blades 2, in which they experience no thermal expansion and with the cover plates 12 - spaced by the coupling element 4 - firmly abut each other.

The coupling element 4 in the recesses 18 is enlarged in FIG. 4 shown. It is tapered on both sides as a double cone formed with two frustoconical, designed as contact surfaces 20 lateral surfaces which are angled in the tangential direction at an angle of 30 ° to each other. This angle is a sharper, ie larger cone angle than that of the contact surfaces 22 of the recesses 18, which are angled tangentially to each other at 25 °. In this way, each of the two contact surfaces 20 abut circularly on an outer edge 24 of the recesses 18. The coupling element 4 is with a slight bias between the blades 2 used so that the blades 2 in the resting state slightly press on the coupling element 4, which holds the blades 2 by a gap 26 between facing surfaces 28 of the cover plates 12 spaced. An axis of symmetry of the coupling element 4 is aligned in the tangential direction 6, neglecting a rhomboid angle 30 between the axial direction 8 and a gap longitudinal direction 32 of the gap 26.

To facilitate assembly of the blade roots 10 in the radial direction 34 into a blade holder 36 of the rotor of the steam turbine, the blade roots 10 are provided with fingers 38 which are held by bolts 40 in the blade holder 36.

During operation of the steam turbine, the rotor blades 2 rotate about an axis of rotation 8 aligned axis of rotation. Due to an uneven influx of the blades 14 with superheated steam, a force which is uneven in magnitude and rhythmic in time engages in the axial direction 8 and tangential direction 6 on the blades 14, which are thereby excited to vibrate. Due to the coupling elements 4 between the cover plates 12, these vibration movements transmitted to the cover plates 12 are largely synchronized in the tangential direction 6 and also in the axial direction 8, so that a shock on a blade 14 is partially distributed to the neighboring blades. For this purpose, the cover plates 12 are free of play against the pressed out to the outside or completely clamped coupling elements 4, so that the cover plates 12 can be supported without play together. It is thereby a stiffening of all cover plates 12 together, mainly in Tangentialrichtung 6 but also reached in the axial direction 8.

In a linear arrangement of the coupling element 4 on the two adjacent cover plates 12, the coupling element 4 can be pressed a little way into the recesses 18, whereby a cushioning of a hard impact on a blade 2 is made possible. The impressions in a recess 18 is connected to an elastic deformation of the cover plate 12 in the region of the recess 18 and the coupling element 4 in the region of the contact point of the cover plate 12, so that in this way the cushioning is achieved. In addition, the outer edge 24 of the cover plate 12 rubs over the contact surface 20 of the coupling element 4, so that a damping of the impact movement takes place by friction.

An alternative coupling element 42 in the same cover plates 12 of blades 2 is in FIG. 5 shown. The following descriptions are essentially limited to the differences from previous embodiments. With regard to features and functions that remain the same, reference is made to the preceding exemplary embodiments. Substantially identical components are basically numbered with the same reference numerals.

The coupling element 42 is designed in the form of an ellipsoid of revolution and has in the direction of the interior of the recesses 18 convexly curved contact surfaces 44 for engagement with the contact surfaces 22 of the recesses 18, which merge between the cover plates 12 into one another. The contact surfaces 22 serve as support surfaces or contact surfaces, which are inclined by about 15 ° to a support direction or pressure direction pointing in the tangential direction 6. At the points where the contact surfaces 44 the Touch contact surfaces 22, the contact surfaces 44 are angled at 30 ° to each other.

At a pressure of a cover plate 12 in the tangential direction 6 on the coupling element 42 this is pressed at thermally elongated blades 2, first under friction radially inward and finally in a circular contact deeper into the recess 18 and the contact surface 22 is pressed obliquely outwards under elastic deformation of Cover plate 12 in the region of the recess 18. This is a cushioning of shocks and energy dissipation by friction possible. By the contact surfaces 44 in the interior of the recess 18 at the contact surface 22, however, the risk of undesirable formation of a heel in the contact surfaces 44 or the contact surfaces 22 is largely eliminated. In addition, by the shape of the ellipsoid of revolution, the location of the circular contact point between the coupling element and the cover plate 12 can be adjusted specifically in the tangential direction 6. The further the contact point is placed in the interior of the recesses 18, the greater the freedom of movement of adjacent cover plates 18 in the axial direction 8 and the radial direction 34 to one another. Through a gap 46 between the coupling element 42 and the outer edge 24 of the recess 18, the coupling element 42 can tumble about the tangential direction 6, wherein the wobble deflection depends on the size of the gap 46 and can be adjusted by a corresponding shaping of the recess 18. Outside the wobble deflection, the coupling element 42 acts as a substantially rigid reinforcement in the axial direction 8 and radial direction 34.

The FIGS. 6 and 7 show cover plates 48 with bilateral spherical recesses 50 into which a spherical coupling element 52 (FIG. FIG. 6 ) or a flattened spherical one Coupling element 54 ( FIG. 7 ) is used. At the points where contact surfaces 58 of the coupling element 52 contact the contact surfaces 56 of the cover plates 12, the contact surfaces 58 are angled by about 20 ° to each other. In the coupling element 54, it is about 15 °.

The spherical coupling element 52 acts as the coupling element 4, but with a different spring action. Due to the similar orientation of contact surfaces 56 of the recess 50 in the region of the outer edge 24 as the spherical cap-shaped contact surfaces 58 of the coupling element 52 at the location of the outer edge 24, the coupling element 52 at an annular abutment against the cover plates 12 initially with only a small force in the recess 50th be pressed under elastic deformation of the cover plate 48. With further impressions, however, the counterforce increases very strongly, so that a strong nonlinearity in the spring force can be achieved in dependence on the Eindrückstrecke. As a result, suitable vibration parameters for avoiding vibrations of the rotor blades 60 can be set. At the in FIG. 7 illustrated embodiment, this advantage is associated with the prevention of the formation of paragraphs in the coupling element 54 by the coupling element abuts the surface of the contact surface 56 at this.

FIGS. 8 to 10 show, analogously to FIGS. 1 to 3, alternative rotor blades 62 with a cylindrical coupling element 64 which is mounted in cover grooves 68 in a groove-shaped recess 66. Each of the recesses 66 is closed on one longitudinal side by a web-like limiting element 70 and designed to be open on the opposite longitudinal side, so that the coupling element 64 by two opposing boundary elements 70 in the recess 66 in a Longitudinal direction 72 of the coupling element 64 and the recess 66 is held. The longitudinal direction 72 is oriented in the gap longitudinal direction and along mutually facing side surfaces 74 of the cover plates 68 and tilted by the rhomboid angle 30 to the axial direction 8.

Due to the elongated shape of the coupling element 64, this always lies with a linear contact form-fitting only radially outside, or in the case of firm clamping radially inwards and outwards against the recess 66. In this case, the locations of the cylindrical contact surfaces of the coupling element 64, which respectively contact the recesses 66 of the cover plates 68 in a line-shaped manner, are angled tangentially by about 60 ° to one another.

Due to the distribution of the force acting on it over the length of the coupling element 64, this can be made small in cross-section. On a radial formation 16 on the cover plates 68 as in the embodiment FIG. 2 can therefore be dispensed with, so that a radial outer surface 76 of the cover plates 68 can be carried out elevation and in particular cylindrical. As a result, an installation of sealing tips for a labyrinth seal for sealing the cover plates 68 against a turbine housing on the outer surfaces 76 is particularly easy because the installation is disturbed by any surveys.

LIST OF REFERENCE NUMBERS

2

turbine blade

2a

airfoil

4

coupling element

6

tangential

8th

axially

10

blade

12

cover plate

14

shovel

16

formation

18

recess

18a

cavity

20

contact area

22

palm

24

outer edge

26

gap

28

area

30

rhomboid

32

Slit longitudinally

34

radial direction

36

blade retainers

38

finger

40

bolt

42

coupling element

44

contact area

46

gap

48

cover plate

50

recess

52

coupling element

54

coupling element

56

palm

58

contact area

60

turbine blade

62

turbine blade

64

coupling element

66

recess

68

cover plate

70

limiting element

72

longitudinal direction

74

side surface

76

outer surface

Claims (50)

Blade (2) having a cover plate (12, 48, 68) at an upper end of an airfoil (2a) and a coupling element (4, 42, 52, 54, 64), which cover plate (12, 48, 68) is formed in that it forms a circumferentially extending ring with cover plates of substantially identically formed blades (2) after attachment to a rotor, a gap (26) being provided between each cover plate (12, 48, 68), wherein the cover plates (12, 48, 68) each have a recess (18, 50) on the sides facing the adjacent cover plates (12, 48, 68) which together with a recess (18, 50, 66) of the adjacent cover plate (12 , 48, 68) forms a cavity (18a), which cavity (18a) is designed to receive the coupling element (4, 42, 52, 54, 64). Blade (2) according to claim 1,
characterized in that the coupling element (4, 42, 52, 54, 64) and the recess (18, 50) are formed such that the coupling element (4, 42, 52, 54, 64) with play in the cavity (18 a ) is fitted. Blade (2) according to claim 2,
characterized in that the coupling element (4, 42, 52, 54, 64) and the recess (18, 50) have the shape of a rotational body. Blade (2) according to claim 3,
characterized in that the coupling element (4, 42, 52, 54, 64) and the recess (18, 50) have an elliptical cross section. Blade (2) according to claim 3,
characterized in that the coupling element (4, 42, 52, 54, 64) and the recess (18, 50) have a round or oval cross section. Blade (2) according to one of claims 3 - 5,
characterized in that the cross section tapers outwardly from the axial center with respect to the rotational symmetry of the coupling element (4, 42, 52, 54, 64). Blade (2) according to one of claims 3 - 5,
characterized in that the cross-section widens outwardly from the axial center with respect to the rotational symmetry of the coupling element (4, 42, 52, 54, 64). Blade (2) according to one of claims 3 - 7,
characterized in that the axis of rotational symmetry of the coupling element (4, 42, 52, 54, 64) is substantially parallel to the gap (26) between the two cover plates, which with their recesses (18, 50) the cavity (18 a) form, extends. Blade (2) according to claim 2,
characterized in that the coupling element (4, 42, 52, 54, 64) has a quadrangular cross section. Blade (2) according to claim 9,
characterized in that the coupling element (4, 42, 52, 54, 64) has a rhombus-shaped cross section. Blade (2) according to claim 9,
characterized in that the coupling element (4, 42, 52, 54, 64) has a trapezoidal cross section. Blade (2) according to any one of claims 9-11,
characterized in that the coupling element (4, 42, 52, 54, 64) has a longitudinal axis along which it extends with the cross-section and which longitudinal axis is substantially parallel to the gap (26) between the two cover plates which coincide with their recesses (18, 50) form the cavity (18 a) for receiving the coupling element extends. Blade (2) according to claim 1,
characterized in that the recess (18, 50) at the axial end faces of the cover plate (12, 48, 68) has an opening extending beyond the gap (26). Blade (2) according to claim 1,
characterized in that the recesses (18, 50) are bag-shaped. Blade (2) according to claim 1 or 2,
characterized in that the recesses (18, 50, 66) each have an obliquely oriented to the tangential direction of contact surface (22, 56) for the mutual interaction on both sides simultaneous contact with the coupling element (4, 42, 52, 54, 64). Blade (2) according to one of the preceding claims,
characterized in that the two recesses (18, 50, 66) in the joint interaction form a radially tapering inner wedge. Blade (2) according to one of the preceding claims,
characterized in that the recesses (18, 50, 66) are designed to taper inwards. Blade (2) according to one of the preceding claims,
characterized in that the coupling element (4, 42, 52, 54) in the tangential direction (6) is tapered on both sides. Blade (2) according to claim 6,
characterized in that the coupling element (4) in the tangential direction (6) is conically shaped on both sides. Blade (2) according to claim 7,
characterized in that the recesses (18) are conical with an inner cone angle and an outer cone angle of the coupling element (4) is greater than the inner cone angle. Blade (2) according to one of the preceding claims,
characterized in that the coupling element (42, 52, 54) has a convexly curved in the direction of the recess inner contact surface (44, 58) for contact with a contact surface (22, 56) of a recess (18, 50, 66). Blade (2) according to one of the preceding claims,
characterized in that the coupling element (4, 42, 52, 54, 64) linearly in at least one of the recesses (18, 50, 66) rests. Blade (2) according to claim 10,
characterized in that the line shape leads annularly around the coupling element (4, 42, 52, 54). Blade (2) according to one of the preceding claims,
characterized in that one of the recesses (18, 50, 66) has an outer edge (24) spaced from the coupling element (42, 54, 64) by a gap (46). Blade (2) according to one of the preceding claims,
characterized in that the coupling element (64) has a longitudinal direction (72) which is oriented in a gap longitudinal direction (32). Blade (2) according to one of the preceding claims,
characterized in that the coupling element (64) is cylindrical. Blade (2) according to one of the preceding claims,
characterized in that the recess (66) is a groove. Blade (2) according to claim 15,
characterized in that the groove is closed at one end by a limiting element (70) and open at the other end. Blade (2) according to one of the preceding claims,
characterized in that the cover plate (68) has an elevation-free radial outer surface (76). Blade (2) according to one of the preceding claims,
characterized by two blade roots (10) of the blades (2) having a connection means for radial insertion into a blade holder (36) of a rotor. Blade ring for a turbomachine with a bandage of moving blades (2) (2), in which respectively adjacent moving blades (2) according to one of the preceding claims are formed. Device for coupling two rotor blades (2), comprising two cover plates (12, 48, 68) of the rotor blades (2) which are spaced apart by a gap (26) and each have a recess (18, 50, 66) into which a gap (26) bridging coupling element (4, 42, 52, 54, 64) is inserted,
characterized in that the coupling element (4, 42, 52, 54, 64) bears against contact surfaces (20, 22, 44, 56, 58) which are angled in the tangential direction against the cover plates (12, 48, 68) and the cover plates (12 , 48, 68) is tangentially supported against each other. Device according to claim 32,
characterized in that the recesses (18, 50) are bag-shaped. Device according to claim 32 or 33,
characterized in that the recesses (18, 50, 66) each have an obliquely oriented to the tangential direction of contact surface (22, 56) for the mutual interaction on both sides simultaneous contact with the coupling element (4, 42, 52, 54, 64). Device according to one of the preceding claims 32-34,
characterized in that the two recesses (18, 50, 66) in the joint interaction form a radially tapering inner wedge. Device according to one of the preceding claims 32-35,
characterized in that the recesses (18, 50, 66) are designed to taper inwards. Device according to one of the preceding claims 32-36,
characterized in that the coupling element (4, 42, 52, 54) in the tangential direction (6) is tapered on both sides. Device according to claim 37,
characterized in that the coupling element (4) in the tangential direction (6) is conically shaped on both sides. Device according to claim 38,
characterized in that the recesses (18) are conical with an inner cone angle and an outer cone angle of the coupling element (4) is greater than the inner cone angle. Device according to one of the preceding claims 32-39,
characterized in that the coupling element (42, 52, 54) has a convexly curved in the direction of the recess inner contact surface (44, 58) for contact with a contact surface (22, 56) of a recess (18, 50, 66). Device according to one of the preceding claims 32-40,
characterized in that the coupling element (4, 42, 52, 54, 64) linearly in at least one of the recesses (18, 50, 66) rests. Device according to claim 41,
characterized in that the line shape leads annularly around the coupling element (4, 42, 52, 54). Device according to one of the preceding claims 32-42,
characterized in that one of the recesses (18, 50, 66) has an outer edge (24) spaced from the coupling element (42, 54, 64) by a gap (46). Device according to one of the preceding claims 32-43,
characterized in that the coupling element (64) has a longitudinal direction (72) which is oriented in a gap longitudinal direction (32). Device according to one of the preceding claims 32-44,
characterized in that the coupling element (64) is cylindrical. Device according to one of the preceding claims 32-45,
characterized in that the recess (66) is a groove. Device according to claim 46,
characterized in that the groove is closed at one end by a limiting element (70) and open at the other end. Device according to one of the preceding claims 32-47,
characterized in that the cover plate (68) has a bump-free radial outer surface (76). Device according to one of the preceding claims 32-48,
characterized by two blade roots (10) of the blades (2) having a connection means for radial insertion into a blade holder (36) of a rotor. Blade rim for a turbomachine with a bandage of moving blades (2), in which respective adjacent cover plates (12, 48, 68) of the moving blades (2) are tangentially supported against each other during operation by a device according to one of the preceding claims 32-49.

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