EP1306522A1 - Locking device for axial turbomachine blades - Google Patents

Abstract

The security device has a security body (22) with a coupling region (30) between its opposing axial ends (26,26'; 28), fitting into a gap between the foot (12) of a turbine blade and the base (15) of a radial channel in a turbine blade carrier (16). The first axial end of the security device is shaped to act against the turbine blade foot and the, the second axial end rotated through a given angle into a security position, for acting against the opposite side of the blade foot.

Description

Technical field

The invention relates to an axial securing device for blades axially flowed turbomachinery according to the preamble of the claim 1.

On the blades of axially flowed turbomachinery act on the bottom the rotation centrifugal forces. These forces are usually or dovetail-shaped design of radially arranged, form-fitting Tongue and groove connection caught between the rotor blade and the blade carrier. The occurring through the axial flow direction of the flow medium axial forces, however, must be by means of a separate securing device to be caught.

State of the art

Such a safety device is known for example from GB-643,914. A fir tree-shaped blade root is opposite in an axially extending one trained radial groove of a blade carrier arranged. Between a gap is provided in the radial groove bottom and the blade root end, in which A securing body of the securing device for axially securing the moving blade is introduced. The fuse body has one at one end radially inwardly protruding nose on which one end face of the blade carrier engages positively. One approximately in the middle of the fuse body arranged, radially projecting second nose engages in a cross to Radial groove in the blade root. The second end portion of the fuse body protrudes over the end faces of the blade root and blade carrier outwards and at the end of the assembly, it moves radially inwards until it stops bent against the end face of the blade carrier. For a better hold a radially extending recess is provided in the end face of the blade carrier, which the bent end portion of the fuse body at least Takes part.

Another example of such a safety device is from US-A-2,928,651 known. To secure the rotor blade in the axial direction, one piece is used formed fuse body made of sheet metal is used, the length of which is greater than the axial extension of the fir tree-shaped blade root or the opposite trained radial groove of the blade carrier. To accommodate the axial Forces serve, among other things, the end areas acting as securing elements of the plate, which is axially over the end faces of the blade root or the blade carrier protrude and are bent for holding purposes in the radial direction. At the downstream end of the sheet the protruding, first end area is in assembled state so that it has a downstream end face of the blade carrier reaches behind. The upstream second end of the sheet is divided into two along the central longitudinal axis of the sheet. The two tabs thus formed from the end area are so in for holding purposes opposite radial directions that bent over a first tab upstream end face of the blade carrier engages behind, while the second tab engages behind the upstream face of the blade root. A thorn-like in the middle of the sheet, upstream from the sheet level protruding projection engages in a wedge-shaped recess in the blade root. To accommodate the smaller, axially against the flow direction of the acting The first end area and the second serve forces acting on the medium Tab, to accommodate the larger ones acting in the direction of flow Forces the first tab and the one that engages in the recess of the blade root Projection are provided.

Common to both safety devices is that at least one end region the fuse body is bent radially in the manner of a hammer plate. The means that the material has to be chosen in such a way that it meets the required requirements Form can be bent and on the other hand the occurring Can absorb forces. Such a fuse body can be limited to the possible shear and shear forces are designed, with the bending a additional material weakening is introduced. The end areas must continue The fuse body can be bent to the blades in their high precision to fix the axial position exactly. The proposed safety devices also contain grooves in the blade root or in the blade carrier, which are very complex and are expensive to manufacture because modern high-performance materials such as. Nickel based alloys or titanium alloys that are used today come, such grooves can only be made by grinding or eroding can.

Presentation of the invention

It is therefore an object of the invention to provide a safety device which allows simple and economical manufacture and assembly, and the occurring Can better absorb shear and shear forces.

This problem is solved by an axial securing device according to the features of Claim 1.

The securing device ensures axial securing of rotor blades axially flow through turbomachines, the radial and circumferential direction by means of a a radial groove of a blade carrier inserted blade root secured are. The securing device has a securing body with a first, axial end region and a second, axial end region, which by means of a Connection area of the fuse body are connected to each other. The The connection area is in an assembled state in between the blade root end and radial groove bottom formed gap. The second end area and the Connection areas are designed such that the second end area from a Mounting position rotatable by a certain angle into a securing position is. In the securing position, the first end region engages radially on the outside first end face of the blade root and radially inside a first end face of the Blade carrier. In the assembly position, the second end area stands radially outwards from the connection area and engages behind only one of the first end faces oppositely aligned, second end face of the blade root. In the secured position the second end region engages radially outside both the second Face of the blade root and a second face of the blade carrier. This configuration of the fuse body allows easy assembly by the safety body in assembly position simply together with the blade root second end area ahead - inserted into the radial groove of the blade carrier becomes. Then the fuse body from the mounting position by the angle in the securing position is twisted so that the second end region not only the Blade root end face but also engages behind the blade carrier end face. Thereby that in the securing position, the second end area of both the blade root end as the blade carrier end face also engages behind, there is no need for one provide radial projection in the connection area of the fuse body. Also a groove in the blade root or in the blade carrier, in which the projection intervention is superfluous. This simplifies assembly and manufacture of blade root, fuse body and blade carrier, which significantly increases the cost lowers. Since it is also not necessary to bend an end region of the securing body there is no need to compromise in the choice of materials between bendability and resistance to shear and shear forces. On Bending the end area can be counteracted with such a material become. This ensures that the blades are held precisely in their axial position guaranteed.

The second end area is the simplest to manufacture radially outward protruding so far that he is the second in the securing position Bucket root end engages behind the radially innermost wave teeth one fir-tree-shaped blade root or the radially innermost wave prongs of one dovetail-shaped blade root protrudes so that it radially outside also engages behind the second end face of the blade carrier. But of course he could End region also in its radially projecting end projections in the circumferential direction have, so that one of these projections when turning the Securing body engages behind the front of the blade carrier.

The specific angle between the securing position and is advantageously the mounting position in the range between approximately ± 5 ° and ± 50 °, preferably in the range from ± 10 ° to ± 30 °. This depends on the design of the blade root, its radially innermost wave spikes and the design of the connection area (see above) and the second end area.

The easiest and safest way is to design the second end area in such a way that it is due to plastic deformation in the transition area between the end area and connection area, caused by torsion, from the mounting position is rotatable into the securing position. The plastic deformation due to torsion represents a completely different load on the material than the plastic deformation by bending in the radial direction. The material impairment caused by the Torsional deformation affects a subsequent load axial shear and shear forces are much less than material weakening otherwise usual deformation due to bending. This means that despite the material load due to plastic deformation, in contrast to the prior art, none There is a risk that the second end area may be damaged by those that occur during operation Forces are bent up and the blade loses its secure axial hold could.

Another possibility is to design the connection area and the gap in this way train that the fuse body as a whole in the gap from the assembly position is rotatable into the securing position, and this is best against one Resistance. One way to achieve this is to design the connection area with a square or rectangular cross section, preferably with rounded or beveled corners, so that in the securing position the chamfered or rounded corners as friction surfaces with the blade root end or the radial groove bottom cooperate. The fuse body is so in the Secured position clamped. For this, the gap must have a somewhat larger radial Have expansion as the connection area so that twisting is possible is. Another possibility is the connection area with a circular Equip cross section, the connection area then without play must be stored in the gap to prevent jamming in the securing position - however also in any other position - to ensure. The fuse body can in this embodiment by further securing elements, such as e.g. a split pin be secured in the securing position.

It has proven to be advantageous with regard to the thrust and shear forces that occur proven that the first end portion is the upstream, first end face of the blade carrier and the blade root, and the second end region in the securing position the downstream end faces of the Bucket foot and the blade carrier engages behind.

In a particularly preferred embodiment, the first end region is in shape a T-shaped double nose, the radially inner nose of the blade carrier end face and the radially outer nose engages behind the front of the blade root. The design as a double nose requires the least material with the best Resistance to shear and shear forces. An easy manufacture is through this Shaping also possible.

The first end area is particularly easy to produce as a double nose by means of a Material thickening, preferably in one piece with the connection area is formed.

For a precise hold in the axial position, it is particularly advantageous to use the first one Design the end area so that the end area is the end faces of Bucket foot and bucket carrier reach behind in a form-fitting manner. This configuration too is very easy to manufacture if the end area is designed as a double nose is.

The second end region can be very easily radially outward from the connecting element produce a protruding protrusion, and most simply as one piece material thickening formed with the connection area of the securing body. For precise posture in the axial position, it is also advantageous here if the second end area is the end faces of the blade carrier and blade root engages positively.

Further advantageous embodiments of the invention are the subject of further dependent claims.

Brief description of the drawings

Fig. 1

einen Teil einer an einem Schaufelträger befestigten Schaufel sowie einen Teil des Schaufelträgers mit einer ersten Ausführungsform der erfindungsgemässen Sicherungsvorrichtung im axialen Schnitt entlang eines Radialnutbodens des Schaufelträgers;

Fig. 2

einen Schnitt durch Schaufel und Schaufelträger aus Fig. 1 entlang der Linie II-II mit dem zweiten Endbereich des Sicherungskörpers der Sicherungsvorrichtung in Montageposition;

Fig.3

die Ausführungsform aus Fig. 1 in einer Seitenansicht aus Richtung B der Fig. 1 mit dem zweiten Endbereich des Sicherungskörpers in Montageposition;

Fig. 4

die Ausführungsform aus Fig. 1 in einer Seitenansicht aus Richtung B der Fig. 1 mit dem zweiten Endbereich des Sicherungskörpers in Sicherungsposition;

Fig.5

in analoger Darstellung zu derjenigen in Fig. 4 eine zweit Ausführungsform mit dem zweiten Endbereich der Sicherungsvorrichtung in Sicherungsposition; und

Fig. 6

in analoger Darstellung zu derjenigen in den Fig. 3 eine dritte Ausführungsform der erfindungsgemässen Sicherungsvorrichtung mit dem zweiten Endbereich einmal in Montageposition und einmal in Sicherungsposition (gestrichelte Darstellung).

The subject matter of the invention is explained in more detail below on the basis of two preferred exemplary embodiments which are illustrated in the accompanying drawings. It shows purely schematically:

Fig. 1

a part of a blade attached to a blade carrier and a part of the blade carrier with a first embodiment of the securing device according to the invention in axial section along a radial groove bottom of the blade carrier;

Fig. 2

a section through the blade and blade carrier of Figure 1 along the line II-II with the second end portion of the fuse body of the safety device in the mounting position.

Figure 3

the embodiment of Figure 1 in a side view from direction B of Figure 1 with the second end portion of the fuse body in the mounting position.

Fig. 4

the embodiment of Figure 1 in a side view from direction B of Figure 1 with the second end portion of the fuse body in the securing position.

Figure 5

in a representation analogous to that in FIG. 4, a second embodiment with the second end region of the securing device in the securing position; and

Fig. 6

in a representation analogous to that in FIG. 3, a third embodiment of the securing device according to the invention with the second end region once in the assembly position and once in the securing position (dashed representation).

The reference symbols used in the drawings and their meaning are in the list of reference symbols is summarized. Basically are in the figures Identical parts with the same reference numerals.

Ways of Carrying Out the Invention

Figures 1 to 4 show a first embodiment of the inventive axial securing device 20. Each part of a moving blade is shown 10 with a fir tree-shaped blade root 12, which is in an opposite Radial groove 14 of a blade carrier 16 designed in the manner of a fir tree is held. In a gap 18 between the end 13 of the blade root 12 and a radial groove bottom 15 of the radial groove 14 is a securing body 22 of the invention Securing device 20 arranged. The flow direction of the The working medium acting on the blades 10 is marked with an arrow in FIG. 1 A marked. Against this flow A there are other opposite ones Forces in axial direction B on the blades 10. Compared to both forces A, B ensures the safety device 20 according to the invention a precise Hold the blades 10 in their axial position.

The fuse body 22, which is preferably made of a nickel-based alloy, such as Nimonic 90 is formed, has two end regions 26, 26 'and 28 with which he the axial extension of the radial groove 14 of the blade carrier 16 and the of the blade root 12 protrudes. The first end region 26, 26 'of the fuse body 22 is designed in the form of a double nose. The radially outer nose 26 'engages behind in this example form-fitting, an upstream blade root face 44, the radially inner nose 26 also engages positively behind one upstream blade carrier end face 36. spaced in the axial direction a second end region 28 is arranged from the first end region 26, 26 ′, that in an assembly position, as shown in Figures 1 to 3, only one engages downstream end face 42 of the blade root 12, namely also positive in this example. The two end regions 26, 26 'and 28 are axially spaced apart from one another by a connecting region 30. The second End region 28 stands radially outward from this connection region in the assembly position 30 from. The connection area 30 has a square cross section with approximately constant dimensions over its entire axial length. This enables a very simple manufacture of the fuse body 22 and one simple machining of the blade carrier 16 and the blade root 12.

4, the securing device 20 from FIGS. 1 to 3 is in a securing position shown, i.e. the second end region 28 is approximately + 45 ° with respect to that Mounting position rotated, the area between the second end and the connection area 30 is plastically deformed by torsion. Can just as well the second end region 28 of course also in the other direction, i.e. by about - 45 ° be turned into a securing position. In the square shown here The configuration of the cross section of the connection area 30 is in the gap 18 without play between the radial groove bottom 15 and blade root end 13 and cannot therefore be rotated together with the second end region 28. The second end region 28 projects in the securing position over the radially innermost wave prongs 32 of the fir tree-shaped blade root 12 and engages behind in this position not only the downstream blade end face 42 but also the downstream aligned part adjoining the shaft teeth 32 the blade carrier end face 38. In this way, the blade 10 is both Downstream and upstream precisely secured in their axial position.

5 shows a second embodiment of the safety device according to the invention 20 shown. In this embodiment, the connection area 30 of the Fuse body 22 is also provided with a square cross section. The Corners of the square cross section or the edges of the square Connection area 30 are, in the example shown here, but phased 34 formed at an angle of about 45 °. The connection area 30 is here with play stored in the gap 18 to twist the fuse body 22 about his To enable central longitudinal axis. 5 shows is in the securing position Fuse body 22 as a whole by about + 40 ° to 45 ° compared to the mounting position twisted, the connection region 30 with the chamfered edges 34 between the blade root end 13 and the radial groove bottom 15 is clamped. Again, the fuse body 22 can also be in the other direction, i.e. at about - Turned 40 ° into a locking position. Due to the storage of the connection area 30 with play, the securing body 22 can approximately about its central longitudinal axis by about 40 ° to 45 ° from the mounting position to the securing position be twisted in which the fuse body by the frictional resistance between the chamfered edges 34 of the connection area 30 and the Blade root end 13 or the radial groove base 15 is clamped.

The embodiment in FIG. 6 differs from the previous one in that that the blade root 12 'and the radial groove 14' dovetail-shaped are formed and the second end region 28 extends in the circumferential direction Has projections 35. One of the overhangs protrudes in the securing position 35 of the second end region 28 the radially innermost wave prongs 32 of the dovetail-shaped blade root 12 'and engages behind in this position the downstream blade root face 42 and the downstream Blade carrier end face 38. With the help of the projections 35, smaller ones are possible Realize angle between the mounting position and the securing position. A keel-shaped cross section of the connection area 30 which is supported without play it is allowed to twist the fuse body against resistance. A backup of the fuse body can be in the securing position here as in the in Fig. 5 shown, for example, in addition to the clamping action in the gap e.g. by means of a Locking pin (not shown).

No matter what the detailed design of the securing device 20 looks like, assembly and disassembly are always quick and easy: the assembly is made using the Blade root 12 of the blade 10 protrudes radially outwards between the two End regions 26, 28 on the connection region 30 of the fuse body 22 placed. The blade 10 and the fuse body 22 then become common - With the second end region 28 of the fuse body 22 ahead - in the Radial groove 18 of the blade carrier 16 inserted until the first end region 26, 26 ' with its radially inner nose 26 'with the first end face of the blade carrier 16 in Brought stop. Then, to axially secure the rotor blade 10 the fuse body 22 in the circumferential direction by an angle that depends is twisted by the design of the participating components. In this way engages behind the second end region 28 - the radially innermost wave prongs 32 of the Blade root 12 protruding - both the second end face of the blade root 12 as well as the second end face of the blade carrier 16. The securing body is used for disassembly 22 simply from its securing position to the mounting position turned back and the fuse body 22 together with the blade 10 the radial gap 18 pulled out. In the examples shown here, the first end region 26, 26 'with its radially inward and outward extending Lugs 26, 26 'each have the upstream end faces 36, 44, while the second end region 28 has the downstream end faces 38, 42 engages behind. But blade 10 and fuse body 22 can of course also design so that the assembly is from the other side and the first End region 26, 26 'engages behind the downstream end faces. and the second end region 28 the upstream end faces.

LIST OF REFERENCE NUMBERS

A

Direction axially downstream

B

Force upstream

10

blade

12

blade root

13

Blade root end

14

radial groove

15

Radialnutboden

16

blade carrier

18

radial gap

20

safety device

22

fuse body

26, 26 '

first end area

28

second end area

30

connecting portion

32

radially innermost wave spikes (fir tree)

34

beveled edge

35

projection

36

upstream blade carrier end face

38

downstream blade end face

42

downstream blade root face

44

upstream blade root face

Claims (11)

Axial securing device for rotor blades (10) of turbomachines with axial flow, in which the rotor blades (10) are secured radially and in the circumferential direction by means of a blade root (12) pushed into a radial groove (14) of a blade carrier (16), the securing device (20) comprises a securing body (22) with a first, axial end region (26, 26 ') and a second, axial end region (28) which are connected to one another by means of a connecting region (30) of the securing body (22), the connecting region in the assembled state (30) is arranged in a gap (18) formed between the blade root end (12) and the radial groove base (15) and the first end region (26, 26 ') is designed such that it radially outwards a first end face of the blade root (12) and radially the inside engages behind a first end face of the blade carrier (16), characterized in that the second end region (28) is designed such that it consists of a Day position can be rotated by a certain angle into a securing position, whereby in the assembly position it protrudes radially outward from the connecting region (30) and only engages behind a second end face of the blade root (12) which is oriented opposite the first end face, while it is radial in the securing position on the outside both the second end face (42) of the blade root (12) and an equally oriented second end face (38) of the blade carrier (16) engage behind. Securing device according to claim 1, characterized in that the second end region (28) of the securing body (22) is designed such that in the securing position it engages behind the second end of the blade root over the radially innermost corrugated teeth (32) of a fir-tree-shaped blade root (12) or one dovetail-shaped blade root (12 ') protrudes and engages behind the second end face of the blade carrier (16). Safety device according to claim 1 or 2, characterized in that the specific angle between the securing position and the mounting position is in the range of approximately ± 5 °, up to approximately ± 50 °, preferably in the range of ± 10 ° to ± 25 °. Securing device according to one of Claims 1 to 3, characterized in that the second end region (28) can be rotated from the assembly position into the securing position by torsional deformation against the connecting region (30) of the securing body (22). Safety device according to one of claims 1 to 4, characterized in that the first end faces of the blade carrier (16) and the blade root (12) which the first end region (26, 26 ') engages behind, the upstream aligned end faces (36) and (44) of the blade carrier (16) and the blade root (12), and that the second end faces of the blade carrier (16) and the blade root (12), which the second end region (28) engages behind in the securing position, are the downstream end faces (38) and (42 ) of blade carrier (16) and blade root (12). Safety device according to one of claims 1 to 5, characterized in that the first end region (26, 26 ') is designed in the form of a double nose, the radially inner nose (26) the first blade carrier end face and the radially outer nose (26') reach behind the first blade root end face, and preferably engage behind with a positive fit. Safety device according to claim 6, characterized in that the double nose (26, 26 ') is formed by means of a material thickening, preferably in one piece with the connecting region (30). Safety device according to one of the preceding claims, characterized in that the second end region (28) is designed as a projection projecting radially outward from the connecting element (30), and engages behind the second end faces of the blade carrier (16) and blade root (12), preferably in a form-fitting manner. Safety device according to one of the preceding claims, characterized in that the second end region (28) is designed in the form of a material thickening, preferably in one piece with the connecting region (30) of the safety body (22). Safety device according to one of the preceding claims, characterized in that the connecting region (30) has a rectangular or square cross section. Safety device according to one of the preceding claims, characterized in that the entire safety body (22) is formed in one piece, preferably from a nickel-based alloy.

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