EP1135578B1 - Support devices for the vanes of power units - Google Patents

Description

The invention relates to a device for supporting blades of axial flow machines, especially of turbo air jet engines.

Axial flow machines are machines that are axially driven by a fluid, for example a gas such as air. Such machines have at least a rotor equipped with blades, which either over the blades Releases energy to the fluid and thus as a compressor (compressor) or pump acts, or on the blades of which the fluid does work, then it is around a turbine. Both compressors (compressors) and turbines are in the Usually structured in several stages. Each stage of such multi-stage axial flow machines is formed by a variety of rotor blades, which usually are arranged projecting radially outward around a central shaft. A Such an arrangement of rotor blades is called a playpen. A multi-stage Compressors or a multi-stage turbine have several playpens. Both between the individual grids of a compressor or a turbine as in front of the first playpen and behind the last playpen are also common Baffle provided, each of a plurality of radially extending, however, fixed guide vanes are formed.

Turbo air jet engines, such as those used to power aircraft, usually have both a multi-stage compressor and a multi-stage Turbine on. Air enters the jet engine from the compressor or compressor sucked in and compressed. It flows through the compressor in the essentially in the axial direction and gets into one or in the compressed state several combustion chambers. There the compressed air is mixed with fuel and the fuel burned. This leads to a further pressure increase in the Combustion chamber. The gases flow out of the combustion chamber into a turbine in which they relax and release their energy to the rotor blades of the playpen. The Turbine playpens are connected to a turbine shaft and drive this on. The turbine shaft transfers its energy to the shaft of the compressor and furthermore, if necessary, to an air screw, a blower or a other consumers of mechanical energy. Also the turbine of a turbo air jet engine is flowed through essentially axially and parallel to the turbine shaft.

Between the radially free ends of the stationary guide vanes of a compressor or a turbine and the rotating rotor on the one hand and between the radially free ends of the moving rotor blades and the respective Standing housing surrounding the playpen on the other hand, gaps are provided, so that the fixed guide vanes are not moving parts and the rotating rotor blades have no fixed parts of the compressor or the Touch the turbine. The dimension of this column is a decisive criterion for the operating behavior and the overall efficiency of the turbine or the compressor. Large gap dimensions or different gap dimensions for the individual blades of the guide grille or the playpen have a negative effect. at a conventional arrangement with a central rotor must point inwards free ends of the guide vanes and the outward-pointing free ends of the Rotor blades can be finely machined after assembly of the blades. Since the Buckets are typically attached to the housing or rotor in a manner are, which allows a slight mobility of the blades, they must for the Finishing can be brought into a stable position after assembly. The Finishing consists in that the assembled blades are fixed and ground become. In order to achieve a functional blade position, the individual blades during the final grinding.

Since the distances between the respective engine stages are very small and there is a demand for a vibration-free grinding process, it is known and usual, the air guide vanes one-piece compressor housings of jet engines to cast using a hardening wax, thereby fixing and then edit. The time spent waxing and removing of the wax amounts to more than 30 hours for five stages one Housing. With housings with more stages, the effort is correspondingly greater.

DE 34 02 066 also discloses a device for fixing rotor blades known, which is characterized in that the blades of a playpen can be biased by means of a printing medium and those of the printing medium generated biasing force is assigned to each blade of the playpen. Such one Uniform distribution of the pretensioning force generated by the pressure medium is given by achieves the known uniform distribution of the hydrostatic pressure in a fluid. The use of compressed air as a fluid is described. It has been shown that the fluid undesirably tends to vibrate when grinding to be transferred from one blade to the other blades. The device thus does not meet the requirement for vibration-free grinding the blade ends. Even worse is that an uncontrollable - itself lighter - pressure drop leads to grinding errors and an unusable one Result of work with the corresponding high costs.

The aim of the present invention is to provide a device for supporting blades Specify in particular a jet engine that is as cheap as possible Fixing engine blades to be machined enables and the disadvantages of Avoid prior art as far as possible.

This aim is achieved according to the invention with a device of the type mentioned at the beginning Type achieved by at least one pair axially opposite each other and mutually adjustable support rings for mounting between Guide or rotor blades of adjacent compressor or turbine stages.

In the assembled state, one of these support rings lies, for example, on the end edges all blades of a guide or moving grille of a turbine or a compressor while the other support ring on the nose edges of all blades one Guide or moving grids of the adjacent stage of the turbine or the compressor is applied. The Laufoder located between the neighboring guide or play grids The guide grill has been removed. The two support rings are supported in axial direction against each other with adjustable force and clamp on this Way the blades of the neighboring guide or playpen with adjustable force in front.

The support rings are preferably segmented in the circumferential direction. In this way the support rings can be dismantled and can be used in particular in one-piece compressor housings can be easily assembled.

The support rings are preferably supported by several over the circumference of the Support rings of distributed support elements adjustable against each other. Any support element For this purpose preferably comprises at least one clamping bolt each two clamping pieces, the distance between them adjustable by means of the clamping bolt is. The clamping pieces preferably each have two at an angle to one another running, flat bevels on and the support rings preferably each laterally limited counter slopes, against which the tension slopes are supported. The clamping elements can then be arranged so that the clamping pieces approach when tightening the bolt connecting them and at the same time over their Spread the two opposite support rings using the Tension bevels of the tension pieces on the corresponding counter bevels of the Slide the support rings along and push the support rings apart. Through the levels Tension bevels with parallel, also flat counter bevels The support rings will have a large area for transferring the tension pieces pressure forces transmitted to the support rings guaranteed. Moreover the clamping pieces cannot twist. Finally, by parallelism of clamping and counter bevels ensures a uniform clamping and a Tilting of the support ring segments excluded.

Preferably, at least some segments of a support ring are on its The blades facing the side are provided with an elastic coating that Damage to the blades is prevented and tolerances are compensated if necessary.

Preferably two opposing segments of a pair of support rings loosely connected to one another by connecting elements. The fasteners are preferably round bolts, the holes in the opposite Segments are included. Prevent the fasteners a falling apart of the opposite segments and thus facilitate the Assembling the support rings.

Particularly good results can be achieved with a processing method the free ends of guide or rotor blades of axial flow machines Help of the support devices according to the invention, according to which the blades together of a housing or rotor carrying it is inserted into a receiving device and the support rings between the guide vanes or rotor blades are adjacent Compressor or turbine stages and before their first stage and their last Mount the stage so that those caused by the support devices Supporting forces are absorbed by the receiving device. Preferably the housing to be machined or the rotor to be machined vertical central axis inserted into the receiving device. In the last-mentioned method variant, the receiving device and Support device preferably preassembled and after preassembly of all support rings first the lowest support ring and then continuing upwards all other support rings set to a desired support force.

The method is particularly in its preferred embodiment variants Particularly suitable for fast and precise support for everyone to ensure machining blades.

Fig. 1

eine Stützvorrichtung in der Seitenansicht;

Fig. 2

den mit A-A gekennzeichneten Schnitt durch die Stützvorrichtung in Fig. 1;

Fig. 3

den mit B-B gekennzeichneten Schnitt durch die Stützvorrichtung aus Fig. 1;

Fig. 4

die Einzelheit X aus Fig. 1 in vergrößerter Darstellung;

Fig. 5

eine ausschnittsweise schematische perspektivische Darstellung der Stützvorrichtung aus Fig. 1 während der Montage zwischen benachbarten Statorgittern einer Turbomaschine;

Fig. 6

eine der Fig. 1 ähnliche Seitenansicht der Stützvorrichtung mit eingeschraubten Handgriffen;

Fig. 7

in vergrößertem Maßstab einen der Handgriffe der Fig.6; und

Fig. 8

einen der Figur 3 ähnlichen Schnitt einer abgewandelten Ausführungsform.

The invention will now be explained in more detail using an exemplary embodiment with the aid of the figures. From the figures shows:

Fig. 1

a support device in side view;

Fig. 2

the section marked AA through the support device in Fig. 1;

Fig. 3

the section marked BB through the support device of Fig. 1;

Fig. 4

the detail X of Figure 1 in an enlarged view.

Fig. 5

a fragmentary schematic perspective view of the support device of Figure 1 during assembly between adjacent stator grids of a turbomachine.

Fig. 6

one of Figure 1 similar side view of the support device with screwed handles.

Fig. 7

on an enlarged scale one of the handles of Figure 6; and

Fig. 8

a section similar to Figure 3 of a modified embodiment.

The support device 10 shown in FIG. 1 includes two support rings 12 and 14, of which the second support ring 14 from the first support ring 12 in the drawing is essentially hidden and can only be seen in the area of detail X. is because the first support ring 12 is shown there cut in the drawing. Both support rings 12 and 14 have the same dimensions and are mirror images built up to each other. Both support rings 12 and 14 each consist of three Segments 82, 84, 86, recognizable by the dividing lines 16 between the segments.

Between the two support rings 12 and 14 are a plurality - described in Embodiment exactly 27 - arranged by clamping elements 20. Because this Clamping elements are located between the two clamping rings 12 and 14 and therefore are covered by the first clamping ring 12 in the drawing, are the clamping elements 20 shown in dashed lines except in the area of detail X. In detail X shows the first clamping ring 12 in section and therefore gives the view on the tensioning element 20 located there. Like in particular the section B-B (Figure 3) can be seen, each clamping element 20 comprises two clamping pieces 22nd and 24, with each other via a screw bolt 26 serving as a clamping bolt are connected. The externally threaded shaft 28 of the bolt 26 engages in an internal thread in the clamping piece 22. A countersunk head 30 at the end of the screw bolt 26 opposite the shaft 28 a correspondingly shaped opening of the second clamping piece 24 freely rotatable held. The countersunk head 30 is with an engagement for a hex key Turn the bolt 26 provided. By the screw 26 by means of External thread in its shaft 28 further screwed into the first clamping piece 22 , the distance between the two clamping pieces 22 and 24 from each other be reduced. The internal thread in the clamping piece 22 is one self-locking threaded insert 31 is formed. This prevents the bolt 26 can loosen automatically.

Both clamping pieces 22 and 24 are each with two clamping slopes 32, 34, 36 and 38 provided. These bevels 32, 34, 36 and 38 are each planar Surfaces executed and are based on appropriately inclined counter-slopes 40, 42, 44 and 46 on the support rings 12 and 14. If the bolt 26 tightened a clamping element 20, the two clamping pieces 22 and 24 of this tensioning element 20. The tension slopes 32, 34, 36 and 38 slide here the clamping pieces 22 and 24 on the corresponding counter slopes 40, 42, 44 and 46 of the two support rings 12 and 14 along and simultaneously press the two support rings 12 and 14 due to the corresponding inclination of the clamping and the opposite surfaces apart. Here is the level training of the clamping and Counter slopes are particularly advantageous compared to, for example, a conical one Execution because the flat surfaces contribute significantly to the spreading apart the support rings as far as possible when tightening the bolts runs in parallel and beyond that no measures to prevent rotation the clamping pieces 24 are required.

Those intended to be supported on guide or rotor blades of a turbomachine Outer surfaces 50 and 52 of the support rings 12 and 14 are each with a provided elastic coating 54 and 56. This elastic coating is said to Avoid damage to the blades and compensate for manufacturing inaccuracies.

2 shows the manner in which opposing segments 82, 82 ' of the two support rings 12 and 14 are loosely connected to one another so that they are in the Montage do not fall apart, but still their for adjustment by means of Retain clamping elements 20 necessary relative mobility. Both tension rings 12 and 14 have through bores through which a connecting bolt 60 protrudes. The connecting bolt 60 ends on both sides in corresponding recesses 62 and 64 of the support rings 12 and 14. Two snap rings 66 and 68 - One at each end of the connecting bolt 60 - prevent the Ends of the connecting bolt 60 through the through holes in the support rings 12 and 14 slip out of the recesses 62 and 64 can. Otherwise, the connecting pin 60 is in the through holes in the support rings 12 and 14 freely movable, so that the support rings 12 and 14 through the connecting bolts 60 are not prevented from getting anywhere. When the connecting bolt 60 is mounted, the support rings 12 and 14 can be but do not fall apart entirely.

Fig. 5 shows how the support device 10 between projecting radially inwards Guide vanes 80 of the guide grids of two adjacent stages of a compressor is assembled. The two support rings 12 and 14 shown only partially lie with their respective levels provided with the elastic coating 54 and 56 Outer surfaces on the leading or trailing edges of the guide vanes 80. In In this position, they are clamped with the help of the clamping elements 20. To do this the two clamping pieces 22 and 24 of a clamping element 20 positioned so that their bevels 32, 34, 36 and 38 on the corresponding counter bevels 40, 42, 44 and 46 of the support rings 12 and 14 rest. 5 shows that the counter bevels 40, 42, 44 and 46 are not circumferential but for each Clamping element 20 are limited laterally, so that the position of each clamping element 20 is precisely specified. In this way it becomes even Distribution of the clamping elements 20 over the circumference of the support rings 12 and 14 ensured. 5 is in the manner of a Exploded view shown. Therefore, the two clamping pieces 22 and 24 and the screw bolt 26 shown individually. In addition, the thread is in to recognize the clamping piece 22 forming threaded insert 31. This thread insert 31 is self-locking.

Should the free ends of the guide vanes of a one-piece compressor housing are machined radially inwardly projecting guide vanes, the compressor housing inserted with a vertical central axis in a receiving device and fastened in this. A first support device is then formed of a pair of support rings 12 and 14 between the bottom of the cradle and the bottom playpen of the compressor and the bolts 26 of these first two support rings slightly tightened so that the support device the guide vanes of this moving grille against the bottom of the receiving device supported. In the otherwise of the guide vanes of the rotor of the compressor gaps taken between the guide vanes of the compressor additional pairs of support rings are used from bottom to top and the clamping elements 20 slightly biased. Also on the top guide grill put a pair of support rings. This uppermost pair of support rings is supported upwards against an end ring of the receiving device, which after insertion of the compressor housing is mounted in the receiving device. The end ring of the receiving device runs plane-parallel to the bottom of the receiving device. In this way, the support forces generated by the support devices at the inlet and outlet of the compressor from the cradle be included.

After the pre-assembly of all support devices and the support device, the support devices by further and defined tightening of the bolts of their clamping elements to a target tension brought. It starts with the lowest support device and with the continue above until the top support device is tensioned. In this way, an even pre-tensioning of all to be machined Buckets guaranteed.

The top and bottom support rings have the blades to be machined facing away from the bottom or the end ring of the receiving device no elastic coating on the facing side, since there is no damage are to be feared.

In Fig. 7, a handle 70 is shown, the a ball 72 to touch by Hand, a shaft 74 and a threaded portion at the free end of this shaft 76 has. Shaft 74 and ball 72 are not shown firmly connected.

5 that in the preferred embodiment a segment 82 ' of the support ring 14 is provided with bores 78, 79 which have a radial course have with respect to the support ring and in which the gain section 76 each one Handle 70 is screwed.

When using the support devices, they are usually so in the machining compressor housings used that they lie in horizontal planes. For these cases, it is preferably provided that the bores 78, 79 are in one Segment of the respective lower support ring of a support device; in the illustrated 5 would be the support ring 14.

Fig. 6 shows the two screwed into the segment 82 'of the support ring 14 Handles 70, 70 '. They protrude radially inwards into the support device 10, namely in the plane of the support ring 14. Since the blades of the Compressor or the turbine in the view of Figures 1 and 6 above or lie below the visible support ring and the shafts 74 of the handles 70, 70 'have a sufficient length, the support ring can be held on the ball 72, 72' and be positioned in the housing. The fact that the handles on a segment of the bottom support ring 14 are attached to Consequence that the complementary support ring 12 of the support device 10 due to Gravity from the support ring 14 and thus from the two handles 70, 70 ' is carried without the mutual distance between the two support rings could enlarge.

With reference to Fig. 2, it is explained above that opposed Segments 82, 82 'of the support rings by means of one or two connecting bolts 60 are connected to each other in such a way that the segments and thus the support rings moved within certain limits relative to each other and perpendicular to their planes can be. Fig. 6 shows the position of the through holes already mentioned 88, 90, 92, which are provided in each of the superimposed segments in FIG. 6 are. It can be seen that there are two through holes nearby the dividing lines 16 are provided and there is a third through hole is located approximately in the middle of each support element. All of these holes run perpendicular to the paper plane of FIG. 6 and thus perpendicular to the plane of the support rings 12.14.

Another preferred variant is shown in FIG. 8. A can be seen again Pair of clamping pieces 22, 24 together with bolts 26. The shaft 28 of the Bolt 26 is from its free end with a central threaded bore 100, into which an Allen screw 102 with countersunk head 104 is screwed in. In contrast to the exemplary embodiment according to FIG. 3, this protrudes 8 free end of the shaft 28 in the embodiment according to FIG Surface of the clamping piece 22 to a certain extent. Countersunk 104 has a larger diameter than the shaft 28. If you imagine that the screw bolt 26 (to the right in Fig. 8) unscrewed from the clamping pieces one recognizes that after a certain way of the bolt 28 the outer edge of the countersunk head 104 of the screw 102 into a depression 106 of the clamping piece 24 moves in and finds a stop there. The consequence of this construction is that the two clamping pieces when loosening the Bolt 26 can only be moved apart to a certain extent and do not fall out during assembly and disassembly of the support device can.

Claims (15)

1. Arrangement for supporting blades of axial-flow machines, in particular turbojet propulsion units, characterised by at least one pair of mutually oppositely disposed support rings (12, 14) which are supported adjustably relative to each other for assembly between guide or rotor blades of adjacent compressor or turbine stages.
2. An arrangement as set forth in claim 1 characterised in that the support rings are segmented in the peripheral direction.
3. An arrangement as set forth in claim 1 or claim 2 characterised in that the support rings (12, 14) are supported adjustably relative to each other by means of a plurality of support elements (20) which are distributed over the periphery of the support rings (12, 14).
4. An arrangement as set forth in claim 3 characterised in that the support elements (20) each have at least one clamping bolt (26) and two clamping portions (22, 24) whose spacing from each other is adjustable by means of the clamping bolt (26).
5. An arrangement as set forth in claim 4 characterised in that the clamping portions (22, 24) each have two clamping bevels (32, 34, 36, 38) which are formed by flat surfaces and which extend at an angle relative to each other.
6. An arrangement as set forth in claim 5 and one of the preceding claims characterised in that the support rings (12, 14) each have laterally delimited, flat cooperating bevels (40, 42, 44, 46) which, when the clamping portions (22, 24) are inserted, extend parallel to their clamping bevels (32, 34, 36, 38), and which approach each other with a decreasing distance from the center point of the support rings (12, 14).
7. An arrangement as set forth in one of the preceding claims characterised by an elastic covering (54, 56) on the side, which is intended to bear against the blades, of at least one support ring segment.
8. An arrangement as set forth in one of the preceding claims characterised by connecting elements (60) which loosely interconnect two mutually opposite segments of a pair of support rings.
9. An arrangement as set forth in claim 8 characterised in that the connecting elements are round pins (60) and the mutually opposite segments of a pair of support rings have bores for receiving the connecting elements.
10. An arrangement as set forth in one of the preceding claims characterized in that at least one of the segments (82, 84, 86) of at least one of the two support rings (12, 14) of the support arrangement (10) is provided with a handle (70, 70'), which handle allows to manually grip the support arrangement from its central area.
11. An arrangement as set forth in claim 10, characterized in that said handle (70, 70') comprises two parts and is adapted to be screwed into at least one of said support rings (14) from the radially inner side of said support arrangement (10).
12. An arrangement as set forth in one of the preceding claims 1- 11, characterized in that the free end of the shaft (28) of each bolt projects out of threaded clamping portion (22), the bolt being a clamping bolt (26) and each of the clamping bolts being adapted to connect a pair of clamping portions (22, 24); further characterized in that a central thread (100) is provided within the free end of said shaft (28) with a screw (102) being threaded into said thread, the head (104) or a washer or the like held by said screw having a larger diameter than said shaft (28); and further characterized that upon unscrewing said clamping bolt the part of the head or of the washer or the like radially extending beyond said shaft abuts said clamping portion (24) from the outside thereby preventing a separation of the two clamping portions (22, 24).
13. A method of machining the free ends of guide or rotor blades of axial-flow machines by means of support arrangements as set forth in one of claims 1 through 9, characterised in that the blades together with a housing or rotor carrying same are fixed in a receiving apparatus and the support rings are so assembled between the guide or rotor blades of adjacent compressor or turbine stages and upstream of the first stage thereof and downstream of the last stage thereof, that the support forces produced by the support arrangements are received by the receiving apparatus.
14. A method as set forth in claim 13 characterised in that the housing which is to be machined or the rotor which is to be machined is inserted with its center line vertically disposed into the receiving apparatus.
15. A method as set forth in claim 14 characterised in that the receiving apparatus and the support arrangement are initially preassembled and slightly prestressed and after pre-assembly of all support rings firstly all clamping elements of the lowermost support ring and then sequentially progressively upwardly the clamping elements of each further support ring are set to a desired support force.

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