EP2002085B1 - Guide blade segment of a thermal turbomachine, associated production method and thermal turbomachine - Google Patents

Abstract

The blade segment (2) has a set of profiled blades (6) arranged on a platform (8). A set of securing units (14) securing the guide blade segment to an associated guide blade support are arranged on a side of the platform, which is oriented away from the blades. A section of one of the securing units is a separately produced component, which is rigidly connected to the platform or to an additional section of the securing unit. An independent claim is also included for a method for manufacturing of a guide blade segment.

Description

Guide vane segment of a thermal turbomachine, associated production method and thermal turbomachine

The invention relates to a vane segment of a thermal turbomachine, in particular a gas turbine, with at least one profiled airfoil arranged on a platform, wherein a number of fastening elements for fastening the vane segment to an associated vane support is arranged on the substantially flat side of the platform facing away from the airfoil ,

Gas turbines are used in many areas to drive generators or work machines. In this case, the energy content of a fuel is used to generate a rotational movement of a turbine shaft. For this purpose, the fuel is burned in a combustion chamber, compressed air being supplied by an air compressor. The working medium produced in the combustion chamber by the combustion of the fuel, under high pressure and at high temperature, is guided via a turbine unit connected downstream of the combustion chambers, where it relaxes in a work-performing manner.

In order to generate the rotational movement of the turbine shaft, a number of rotor blades, which are usually combined into groups of blades or rows of blades, are arranged thereon and drive the turbine shaft via a momentum transfer from the flow medium. To guide the flow medium in the turbine unit also commonly associated guide blade rows are arranged between adjacent blade rows with the turbine housing. The turbine blades, in particular the guide vanes, usually have a profiled airfoil extending along a blade axis for suitable guidance of the working medium, at the end for attachment of the turbine blade to the respective one Carrier body is formed transversely to the blade axis extending platform. The top of the platform facing the airfoil forms an outer boundary surface for the hot gas flow channel of the gas turbine.

For simple and secure mounting and fixing to a guide vane carrier connected to the turbine housing, the platform of the respective vane usually has a number of hook-like fastening elements on its underside or rear side facing away from the vane blade. A similar hook fastening of the axial gap of two vanes of adjacent turbine stages bridging guide ring is for example from the EP 1 505 259 A1 known, which is considered as the state of the art. For assembly, the guide vane is inserted with its fastening elements or fastening hooks into corresponding receiving grooves of a Leitechaufelträgern, aligned and then fixed in a suitable manner, eg with the help of Stemmblechen. In the case of the aforementioned guide ring is according to the EP 1 505 259 A1 nor provided an additional fastener, by means of which the hook of the guide ring in the vane support can be further tightened.

Moreover, from the US 2,942,844 the attachment of a guide vane of the first turbine stage known. The vane includes an inner platform to which a transversely extending flange is welded. To fasten the guide vane, the flange provided with a bore is fastened non-positively to a support structure by means of a screw extending through the bore.

In order to reduce the manufacturing or assembly costs, a plurality of guide vane blades, which are adjacent to one another in the circumferential direction of the gas turbine, of a row of guide vanes may also be arranged on a common platform, so that the complete, hereinafter referred to as, vane segment designated blade unit by means of the platform-side mounting hook axially or circumferentially in the associated vane carrier is inserted. To simplify the manner of speaking, the term "vane segment" in the following, and in particular in the claims, always include the case of a single vane with only one blade, unless this is expressly excluded.

Typically, the vane or the entire vane segment is made by a casting process so that the platform and platform-side fasteners are integral, co-molded components of the vane or vane segment. For this purpose, in a first step, a so-called wax model of the blade or the blade segment is manufactured, which is then provided by repeated immersion in a ceramic material with a ceramic coating. Once this has a sufficient thickness, the model provided with the ceramic coating wax is burned out, whereby the ceramic solidifies and the liquefied or evaporated wax is removed. The ceramic negative mold obtained in this way is finally filled with the metallic blade material. After the solidification of the melt and the removal of the shell-like outer casting mold, ceramic core elements still remaining in the blade body, which were previously introduced to form cavities or cooling channels integrated in the blade body, are removed by leaching with caustic soda or the like.

The hook-like protruding from the platform fasteners cause in the manufacturing process in several respects difficulties. Already the production of the wax model is relatively cumbersome because the formation of the fastening hook comparatively complex wax tools with a variety of so-called mask elements or slide are required. Also in terms of casting technology, the attachment hooks are problem areas, since the undercuts in the construction of the shell mold can be sanded poorly and in the subsequent casting process due to their exposed position always to form Lunkerfeldern, d. H. tend to material defects caused by heat shrinkage in the cooling component.

In addition, it is often difficult to comply with the tolerances required for a snug fit of the mounting hook in the associated receiving groove, especially in embodiments with relatively small radii of curvature. Thus, sealing problems can occur at this point in the later operation of the turbine. Finally, it has been found that the fastening hooks often also represent weaknesses of the turbine blades with respect to their wear behavior under operational load and with regard to the permissible maximum load absorption.

The invention is therefore an object of the invention to provide a vane segment of the type mentioned above, which is designed for simple and cost-effective production while avoiding casting problem zones for a particularly reliable and secure attachment to an associated vane carrier. Furthermore, a method suitable for the production of the vane segment should be specified.

With regard to the vane segment, the object is achieved in that at least one section of at least one of the fastening elements is a separately manufactured component connected fixedly to the side of the platform facing away from the airfoil.

The invention is based on the consideration that the casting material for the vane segment should usually be optimized for a high high-temperature strength, so as to achieve a high operational safety and structural stability and the longest possible life of the directly exposed to the hot working medium sections, in particular the to ensure the flow channel of the gas turbine in the projecting blades and the flow channel facing the top of the platform. However, such an interpretation is, as has now been found, may not be optimal for the functionally and structurally decoupled from the rest of the blade segment fasteners including the hook, which are exposed on the one hand by the upstream platform only comparatively low thermal stress, however On the other hand, relatively high mechanical loads and bearing or holding forces must absorb. In order to avoid the disadvantages existing up to now, it is proposed according to the concept presented here to separately produce the fastening elements that are functionally decoupled from the remainder of the stator blade segment, ie the fastening hook (s), using a material which has been consistently adapted to the respective technical function and only then with the aid of a suitable joining method with the rest of the fastener or with the platform of the example produced in the proven casting technique, ie integrally running, to connect the remaining vane segment.

For permanent connection to the platform of the guide vane or the vane segment, the respective fastening element comprises a connecting element provided with a bearing surface. For a particularly uniform distribution of support or connecting forces and for precise alignment of the fastener relative to the platform, the connecting element is expediently designed in the manner of a flat connecting plate with a flat bearing surface. To realize a low installation height, the connecting element or the connecting plate is sunk in a corresponding recess of the platform, in particular by this a simple to produce Leitschaufelsegment can be specified, since the difficult to access the Gußherstellung geometry of the Leitschaufelsegmenthaken has been eliminated.

In this at least two-component design of the vane segment, not only the material selection for the fasteners with regard to the requirements of the "hooked" attachment to the vane support can be optimized, for example in terms of load bearing, wear and / or seal; In addition, for example, eliminates the difficulties described in the preparation of the wax model or during the casting process. Despite the With the joining process associated additional manufacturing step, the production of the vane segment is thus much easier.

In a particularly advantageous embodiment, the respective fastening element comprises a protruding from the platform, angularly bent fastening hook, which is adapted in its shape and contour to the associated receiving groove of a vane carrier. A possible alternative to this is a substantially straight profile piece, which is insertable into a polygonal receptacle in the turbine housing.

Advantageously, the connecting element is positively fixed in a matched to the shape of the connecting element depression or groove of the platform. Such a positive connection, for example, given by the fact that the platform in the edge region of the recess or the groove has a number of projections which engage around the connecting element in each case on its side facing away from the support surface. For mounting the fastening element to the platform then, for example, the connecting element is laterally inserted into the recess or the receiving groove of the platform and then fixed in a suitable manner, for example, positive, non-positive and / or cohesive against lateral slipping. Because the connection forces are essentially by the projections positively embracing the connecting element are received, the additional fixation must be designed only for relatively low loads.

Instead of the positive connection between the connecting element and the platform or in addition thereto, a cohesive connection, preferably by soldering or welding, may be provided.

Preferably, the respective fastener for a high mechanical strength is made integrally from a one-component workpiece. In this case, for example, the attachment hook can be milled or extruded as a straight profile piece and bent in a second operation in the required radius. The fastening element is preferably produced from a material which is less resistant to high temperatures but tougher than the rest of the stator blade segment.

Conveniently, the guide vane or vane segment has a plurality of fasteners for secure attachment to the vane support, and preferably each of the fastener elements is a separately fabricated and configured component as described above.

Typically, a gas turbine includes a plurality of turbine stages, each of the turbine stages including a plurality of stator vanes circumferentially disposed around the flow passage on the turbine housing, which in their entirety form a row of vanes. In this case, as already mentioned, in each case a plurality of adjacent guide vanes can be combined to form a vane segment or a "multiple". Each of the guide vanes or each vane segment expediently has a platform with hook-like fastening elements, wherein the specifications for the hooking profile in terms of bending angle and / or bending radius usually vary with the mounting position, ie in particular depend on the turbine stage or the guide vane row. Particularly advantageous in this context is a standardized or standardized design of the connecting elements and the corresponding platform-side receptacles or depressions, by means of which the fastening elements are connected to the respective platform. Also, the respective profile piece, from which arises by bending the fastening hooks, can look the same in the original "raw state" for all fasteners. One and the same fastener can thus be used in principle for all turbine stages of a turbine; only the bending radius and / or the bending angle of the fastening hook must be adapted to the respective place of use or to the respective intended use. Conveniently, the bending of the profile piece takes place before the connection of the connecting element with the platform of the vane segment, because this facilitates the handling and the implementation of the bending process. In principle, however, it is also possible to bend the fastening hook into the desired or required shape only after the connection of the fastening element and the platform.

• Die Werkstoffauswahl für das Befestigungselement kann auf die Verhakungsanforderungen hin optimiert werden, insbesondere in Bezug auf Lastaufnahme, Verschleiß und/oder Dichtung.
• Die Fertigung der Leitschaufel oder des Leitschaufelsegmentes wird insgesamt wesentlich einfacher.
• Toleranzen können einfacher eingestellt bzw. eingehalten werden.
• Ein Verhakungsprofil kann als Standard für weitgehend alle Turbinenstufen/Leistungsklassen verwandt und durch unterschiedliche Biegeradien an den jeweiligen Verwendungszweck angepasst werden.
• Im Gussteil werden gießtechnische Problemzonen vermieden.
• Die Wachswerkzeuge für die Leitschaufeln werden einfacher, haben weniger Einsätze oder Schieber.

The advantages achieved by the invention are in particular in the following points:

• The material selection for the fastener can be optimized to the Verhakungsanforderungen out, especially in terms of load bearing, wear and / or seal.
• The manufacture of the vane or the vane segment is much easier overall.
• Tolerances can be set or adhered to more easily.
• A hooking profile can be used as a standard for almost all turbine stages / performance classes and adapted to the respective intended use by different bending radii.
• Casting problem areas are avoided in the casting.
• The wax tools for the vanes are simpler, have fewer inserts or slides.

The advantages weigh even more in a vane segment with multiple blades on a common platform than a single blade.

FIG 1

eine Leitschaufel mit einem Befestigungselement ge- mäß einer ersten Ausführungsform,

FIG 2

eine Leitschaufel mit einem Befestigungselement ge- mäß einer zweiten Ausführungsform, und

FIG 3

eine Leitschaufel mit einem zur Erfindung alternativen Befestigungselement.

An embodiment of the invention will be explained in more detail with reference to a drawing. Show:

FIG. 1

a guide vane with a fastening element according to a first embodiment,

FIG. 2

a guide blade with a fastening element according to a second embodiment, and

FIG. 3

a vane with an alternative to the invention fastener.

Identical parts are provided with the same reference numerals in all figures.

In the FIG. 1 In a schematic side view partially and partially cut shown vane 2 comprises a extending in the direction of the blade axis 4 profiled airfoil 6, to which in the region of the blade root a substantially transverse to the blade axis 4 oriented platform 8 is formed. In the installed state of the guide blade 2, the "upper side 10" of the platform 8, which is oriented toward the blade leaf 6, forms an outer boundary of a hot gas-carrying flow channel in a gas turbine (not shown). At the side facing away from the airfoil 6, substantially flat "bottom" 12 or back of the platform 8 is a number of hook-like fasteners 14, by means of which the guide vane 2 in an associated vane support (not shown) mounted on the turbine housing / is attached. in the shown here is only one of the fasteners 14 visible, which is mounted with respect to the axial direction 16 near the trailing edge of the airfoil 6; another fastener is disposed in the vicinity of the leading edge not shown here.

The fastener 14 is specifically adapted to the associated with the entanglement in the vane support mechanical loads in simple and inexpensive held. For this purpose, the fastening element 14 is designed as a separate, independent of the remaining guide blade 2 and only subsequently connected to her component, wherein the material used for the fastener 14 is less resistant to high temperatures, but is more tough than the material from which the blade 6 and the Platform 8 are made.

The fastening element 14 comprises in addition to a projecting from the back 12 of the platform 8, approximately at right angles angled mounting hook 18 thereon a molded connection plate 20 with a rectangular base. The connecting plate 20 is positively fixed in an associated recess 21 of the platform 8. With its flat bearing surface 22, the connecting plate 20 is flat on the base of the recess 21. The depth of the recess 21 corresponds to the thickness of the connecting plate 20, so that there is an offset-free transition in the edge region to the platform surface.

To realize the positive connection are in the embodiment according to FIG. 1 two opposite longitudinal edges 24 of the connecting plate 20 are chamfered such that they are encompassed or surrounded by complementary thereto, parallel to the longitudinal edges 24 extending projections 26 at the edge of the platform-side recess 21. The projections 26 thus form a perpendicular to the plane extending guide and mounting rail into which the connecting plate 20 for mounting the fastener 14th is inserted. In order to prevent unwanted slipping or shifting in this direction, additional fixing means, not shown here may be provided. A shift in the other two spatial directions, so on the one hand parallel to the blade axis 4 and the other in the axial direction 16 is excluded by the positive attachment. Corresponding bearing and holding forces are absorbed primarily by the bevelled longitudinal edges 24 of the connecting plate 20 and the corresponding platform-side projections 26. With a correspondingly large selected edge length of the connecting plate 20, the forces acting per length section are relatively small and thus easy to control. It goes without saying that the person skilled in the art can change numerous details of the connection between the fastening element 14 and the platform 20, without departing from that in FIG FIG. 1 deviate shown principle of positive engagement.

This in FIG. 2 shown fastener 14 is analogous to the fastener 14 after FIG. 1 arranged with its connecting plate 20 sunk in an associated recess 21 of the platform 8, but not fixed in contrast to this form fit. Rather, the connecting plate 20 is connected by a number of solder pads or solder joints 28 between the bearing surfaces 22 cohesively with the platform 8. For the required Hochtemperaturlötung a large number of solders / heat treatments are commercially available, the geometry of the solder joints should be carried out expediently full-scale. The selection of the soldering process is essentially influenced by the operating conditions at the soldering, the material pairing and the compatibility with other heat treatment requirements.

Finally shows FIG. 3 an alternative to the invention variant in which only an outer portion 30 of the fastener 14 is a separately manufactured component, the rest of the part, however, integrally molded to the platform 8 and is cast together with her. The effectively as an "adapter" effective outer section 30 has Similar to a closure cap for a bottle or tube, a skirt 32 enclosing the platform-side component of the fastener 14 at its outer end. The dimensions are chosen such that prior to the introduction of a joining agent results in a loose, play-afflicted seat, which can be adapted to the present on the respective site geometric requirements and thereby compensates for manufacturing tolerances and fluctuations. After such a positional adjustment, the two components of the fastening element 14 are connected to one another by a soldering compound 36 introduced into the intermediate space 34 and subsequently solidified.

Claims (10)

1. Stator blade segment (2) for a thermal turbomachine,
   with at least one profiled blade airfoil (6) which is arranged on a platform (8),
   wherein a number of fastening elements (14) for fastening the stator blade segment (2) on an associated stator blade carrier are provided on the essentially flat side of the platform (8) which faces away from the blade airfoil (6),
   wherein at least one of the fastening elements (14) is a separately produced component which is connected in a fixed manner to the side of the platform (8) which faces away from the blade airfoil (6),
   characterized in that
   the respective fastening element (14) comprises a fastening hook (18) which projects from the platform (8), and a connecting element which by a bearing surface (22) is recessed in the platform (8).
2. Stator blade segment (2) according to Claim 1,
   in which the respective fastening element (14) is produced integrally from a single-component workpiece.
3. Stator blade segment (2) according to either of Claims 1 or 2,
   in which the respective fastening element (14) is produced from a material which is tougher in comparison to the platform (8) and/or to the blade airfoil (6).
4. Stator blade segment (2) according to one of Claims 1 to 3,
   in which the connecting element is a connecting plate (20).
5. Stator blade segment (2) according to one of Claims 1 to 4,
   in which the connecting element is fixed in a positive-locking manner in a recess (21) or slot of the platform (8) which is matched to the shape of the connecting element.
6. Stator blade segment (2) according to Claim 5,
   in which the platform (8) in the edge region of the recess (21) or of the slot has a number of projections (26) which grip round the connecting element in each case on its side which faces away from the bearing surface (22).
7. Stator blade segment (2) according to one of Claims 1 to 6,
   in which the respective fastening element (14) is connected in a materially-bonding manner, preferably by soldering, to the platform (8) or to the remaining part of the fastening element (14).
8. Stator blade segment (2) according to one of Claims 1 to 7, with a multiplicity of blade airfoils (6) on a common platform (8).
9. Thermal turbomachine,
   especially a gas turbine,
   with at least one stator blade segment (2) according to one of Claims 1 to 8.
10. Method for producing a stator blade segment (2) according to one of Claims 1 to 8,
    in which a fastening element (14) with a fastening hook (18) is produced from a workpiece which comprises a longish profiled section,
    by the profiled section being deformed by bending to form the fastening hook (18), and wherein the fastening element (14) is then connected by a bearing surface (22) in a non-positive-locking and/or materially-bonding manner, being recessed in the platform (8).

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