EP3176388B1 - Guide blade segment with radial securing - Google Patents

Description

The present invention relates to a stator segment for a gas turbine, in particular an aircraft gas turbine, comprising at least one radially outer shroud and a radially inner shroud, which extend along a respective arc and together form a ring portion, wherein in the radial direction between the outer shroud and the inner shroud a plurality of stator blades are arranged side by side in the circumferential direction, which are materially connected to the inner shroud and the outer shroud, in particular integrally connected, wherein the outer shroud in an axial longitudinal direction comprises an axially forward end wall element and an axially rear end wall element, such that the outer shroud and the two end walls in longitudinal section form a trough-like profile, wherein at least one radial securing element is provided on the axially rear end wall, which is adapted to the guide vane segment in the radial direction re To secure to a surrounding housing, wherein the radial securing element is formed as a projection having a support portion which is adapted to be supported on a corresponding counterpart on the housing.

In the present application directional information such as "axial" or "axial", "radial" or "radial" and "circumferential" basically to refer to the machine axis of the gas turbine to understand, unless the context explicitly or implicitly something else results.

US2015 / 0125289 A1 shows a vane segment with a trough-like outer shroud, on the rear end wall of radial securing elements are arranged. The radial securing elements have bearing portions with bearing surfaces which lie on a cylindrical peripheral surface. To make this curved surface must be milled from the full, resulting in significant overhead and higher cost of the component. Similar vane segments are off EP 2 811 118 A1 and EP 1 431 517 A2 known.

In DE 60 2004 003 757 T2 It is proposed to remove mass from a shroud of a vane segment by reducing the thickness. For this purpose it is proposed known industrial processes such as manual or high-speed CNC machining, automatic or manual grinding, electro-erosion or water-jet machining.

In EP 2 878 769 A1 will suggest the flanks of grooves, which are provided between two sealing ribs of a blade shroud, perform linearly in the circumferential direction. These surfaces are not bearing surfaces.

For improved and simplified assembly of vane segments, which may also be referred to as vane clusters, in a gas turbine engine, it has been found that the provision of radial securing elements is an apt alternative to heretofore known hook fuses.

In the radial securing of vane segments, which are usually combined in a gas turbine to form a vane ring, it is particularly important to secure the vane segments within the turbine housing in the radial direction against falling out. In operation of the gas turbine, the stator vane segment is generally acted upon by the flow to which the vane (s) is exposed, typically a moment which is such that the axially rearward end wall member is forced radially outward, whereas the axially forward one End wall element is pulled radially inward. This moment is taken up by the axially rear end wall element, that the radially outer edge of the same is supported on the housing. However, if the turbomachine is out of operation, the flow acting on the vanes in the gas duct is missing. Especially for this case, the radial fail safe or the radial securing element described here is used. In this way, it is prevented that the guide blade segment can fall out, for example due to gravity, when the turbomachine is at a standstill.

In the radial direction, lower forces are to be supported during operation of the gas turbine. A support of forces acting in the radial direction can usually be optimally carried out when a support surface has a normal vector having only vector components in the radial direction and / or axial direction. However, it has been found that such bearing surfaces are rather expensive to manufacture if the bearing surface should be curved in the circumferential direction in accordance with the radius related to the machine axis, or if the bearing surface lies in a tangential plane to the circumference in the region of the outer shroud.

The object of the invention is to provide a vane segment, the radial securing element enables a simplified manufacturing.

To solve this problem, it is proposed that the support section has a bearing surface which lies in a first plane whose normal vector has vector components in the circumferential direction and in the axial direction (AR) and / or in the radial direction (RR). In other words, the first plane is in space so as to intersect a tangential plane to the circumferential direction in a plane defined by the radial direction and the circumferential direction. If the normal vector has a vector component in the circumferential direction and in the radial direction (or in the axial and radial directions), the first plane has no curvature in the circumferential direction and can be made simpler by this simplified geometry or shaping.

In a further development, it is proposed that the vane segment in the circumferential direction (UR) on the outer shroud has two shroud side surfaces arranged at a distance from one another, which are designed such that they can come into contact with a shroud side surface of an adjacent guide blade segment, wherein the radial securing element is flush with at least one shroud side surface is trained.

In this case, the guide vane segment in the circumferential direction to each other at a distance arranged comprise two radial securing elements, so that the guide vane segment is supported defined at two points and can not slip out of the intended position, in particular can not rotate about a radially extending axis.

For this purpose, it is proposed that the one radial securing element is formed flush with the one side of the shroud, and that the other radial securing element is arranged at a distance to the other shroud side surface.

It is preferred that the distance measured in the circumferential direction of the two radial securing element is smaller than the distance measured in the circumferential direction of the two shroud side surfaces.

It is further proposed that the radial securing element is produced by linear grinding. Linear grinding enables the movement of a corresponding grinding tool along a main direction of the grinding, and along a feed direction orthogonal thereto. Due to the tool geometry and the linear movement process (grinding main direction), a bearing surface whose normal vector has the abovementioned features can be formed in a simple manner by the linear grinding.

It is further proposed that the support section has a second surface which lies in a second plane whose normal vector has vector components in the circumferential direction and in the radial direction (RR), in particular also in the axial direction (AR).

In this case, it is preferable that the second surface and the support surface are inclined to each other, wherein the angle formed by the first and the second plane in a sectional plane which is spanned by the radial direction (RR) and the axial direction (AR), in an area between 70 ° and 90 °, preferably 75 ° to 85 °.

The vane segment may further comprise a circumferential securing element in the circumferential direction in a central region of the rear end wall.

• Bereitstellen eines Roh-Leitschaufelsegments (10a) mit wenigstens einem radial äußeren Deckband (14) und einem radial inneren Deckband (12), die sich entlang eines jeweiligen Kreisbogens erstrecken und gemeinsam einen Ringabschnitt bilden, wobei in radialer Richtung (RR) zwischen dem äußeren Deckband (14) und dem inneren Deckband (12) mehrere Leitschaufeln (16) in Umfangsrichtung (UR) nebeneinander angeordnet sind, die mit dem inneren Deckband (12) und dem äußeren Deckband (14) materialschlüssig verbunden, insbesondere einstückig verbunden sind, wobei das äußere Deckband (14) in einer axialen Längsrichtung (AR) ein axial vorderes Stirnwandelement (22) und ein axial hinteres Stirnwandelement (24) umfasst, derart dass das äußere Deckband (14) und die beiden Stirnwände (22, 24) im Längsschnitt ein wannenartiges Profil bilden, und mit wenigstens einem Roh-Radialsicherungselement;
• Ausrichten des Roh-Leitschaufelsegments relativ zu einer Linearschleifvorrichtung, derart dass mittels der Linearschleifvorrichtung Material des Roh-Radialsicherungselements abgetragen werden kann;
• Abschleifen des Roh-Radialsicherungselements mittels der Linearschleifvorrichtung bis das Roh-Radialsicherungselement die Form eines Radialsicherungselements mit einem Auflageabschnitt angenommen hat, der eine Auflagefläche aufweist, die in einer ersten Ebene liegt, deren Normalenvektor Vektorkomponenten in Umfangrichtung und in Radialrichtung (RR), insbesondere auch in Axialrichtung (AR), aufweist.

The object underlying the invention is also achieved by a method for producing a guide blade segment for a gas turbine, in particular an aircraft gas turbine, comprising the following steps:

• Providing a raw vane segment (10a) having at least one radially outer shroud (14) and a radially inner shroud (12) extending along a respective arc and forming together a ring portion, in the radial direction (RR) between the outer shroud (14) and the inner shroud (12) a plurality of guide vanes (16) in the circumferential direction (UR) are arranged side by side, which are materially connected to the inner shroud (12) and the outer shroud (14), in particular integrally connected, wherein the outer Shroud (14) in an axial longitudinal direction (AR) an axially front end wall element (22) and an axially rear end wall element (24), such that the outer shroud (14) and the two end walls (22, 24) in longitudinal section form a trough-like profile, and at least one raw radial fuse element;
• Aligning the raw Leitschaufelsegments relative to a linear grinding device, such that by means of the linear grinding material of the Rohunialicherungselements can be removed;
• Grinding the raw radial securing element by means of the linear grinding device until the raw radial securing element has taken the form of a radial securing element with a support section having a support surface lying in a first plane, the normal vector vector components in the circumferential direction and in the radial direction (RR), in particular also in FIG Axial direction (AR).

Incidentally, the step of aligning the blank vane segment and the step of abrading may be performed once for each raw radial-securing member when two or more raw radial securing members are provided on the blank vane segment.

Further, it is proposed that the step of aligning the blank vane segment relative to the linear sander is performed such that the linear sander can be moved or spaced apart from other components of the blank vane segment as the raw radial securing element is abraded, in particular at a distance to a circumferentially provided in a central region on the rear end wall circumferential securing element or a corresponding raw circumferential securing element.

The linear grinding of the radial securing elements can be adapted for different guide blade segments of different turbine stages or different gas turbines, so that the bearing surface of the radial securing element can be produced by appropriate relative orientation of the guide blade segment and the linear grinding tool and can the linear grinding device not be in contact with other components or components, in particular projections and reinforcing ribs of the vane segment comes into contact.

Finally, the invention also relates to a gas turbine, in particular an aircraft gas turbine comprising at least one turbine stage with a plurality of vane segments arranged side by side in the circumferential direction, so that they form a turbine blade vane ring, wherein the vane segments have at least one of the features described above.

The vane segment according to the invention is defined in claim 1. The inventive method for producing a vane segment is defined in claim 12. The gas turbine according to the invention is defined in claim 15.

• Fig. 1 zeigt in einer vereinfachten perspektivischen Darstellung ein Leitschaufelsegment.
• Fig. 2 zeigt eine stark vereinfachte Längsschnittdarstellung eines Übergangsbereichs zwischen Leitschaufelsegment und Turbinengehäuse.
• Fig. 3 zeigt eine Vergrößerung des in Figur 2 gestrichelt umrandeten Bereichs III mit einem Radialsicherungselement und einem gehäuseseitigen Gegenstück.
• Fig. 4 zeigt in einer vereinfachten perspektivischen Darstellung ein Roh-Leitschaufelsegment.
• Fig. 5 zeigt in einer vereinfachten perspektivischen Prinzipdarstellung eine Linearschleifvorrichtung in relativer Positionierung zum Leitschaufelsegment.
• Fig. 6 zeigt in einer anderen vereinfachten perspektivischen Prinzipdarstellung die Linearschleifvorrichtung in relativer Positionierung zum Leitschaufelsegment.
• Fig. 7 zeigt eine vergrößerte Teilschnittdarstellung etwa entlang der Schnittlinie VII-VII der Fig. 6.
• Fig. 8 zeigt in den Teilfiguren A) und B) in schematischen und vereinfachten Prinzipdarstellungen die Neigung einer Auflagefläche eines Radialsicherungselements.

The invention will be described below by way of example and not limitation with reference to the attached figures.

• Fig. 1 shows in a simplified perspective view of a vane segment.
• Fig. 2 shows a highly simplified longitudinal sectional view of a transition region between the vane segment and turbine housing.
• Fig. 3 shows an enlargement of the in FIG. 2 dashed rimmed area III with a radial securing element and a housing-side counterpart.
• Fig. 4 shows in a simplified perspective view of a raw vane segment.
• Fig. 5 shows in a simplified perspective schematic representation of a linear grinding device in relative positioning to the vane segment.
• Fig. 6 shows in another simplified perspective schematic representation of the linear grinding device in relative positioning to the vane segment.
• Fig. 7 shows an enlarged partial sectional view approximately along the section line VII-VII of Fig. 6 ,
• Fig. 8 shows in the sub-figures A) and B) in schematic and simplified schematic diagrams of the inclination of a bearing surface of a radial securing element.

Fig. 1 shows in a simplified perspective view of a vane segment 10 with a radially inner shroud 12 and a radially outer shroud 14 in the radial direction RR extending between the inner shroud 12 and the outer shroud 14 vanes 16, wherein the number of three vanes 16 shown here for a vane segment 10 is purely exemplary; it is also possible for two, four, five or more vanes to be provided in a vane segment 10.

The vane segment 10 of Fig. 1 is shown so that the view of the suction sides 18 and the trailing edges 20 of the guide vanes 16 is released. The radially outer shroud 14 comprises an axially front end wall 22 and an axially rear end wall 24. The two end walls 22, 24 are designed inclined to the shroud 14 so that there is a trough-like profile in a longitudinal section. In the Fig. 1 Furthermore, a radial securing element 26 can be seen, which is formed on the rear end wall 24 and protrudes therefrom against the axial direction AR or against the main flow direction in the turbomachine.
Fig. 2 shows a simplified longitudinal sectional view through the outer shroud 14 and a portion of a turbine housing connected to the nozzle segment 10 turbine housing 28. Also can be seen from the Fig. 2 the front end wall 22 and the rear end wall 24, which together with the shroud 14 form the trough-like profile in the sectional view. At the rear end wall 24, the radial securing element 26 can be seen, which is designed as a projection and projecting against the axial direction AR of the rear end wall 24. The radial securing element 26 has an essentially S-shaped support section 27 with a convex and a concave arc, against which straight pieces or surfaces adjoin. On the housing 28 a complementary to the radial securing element 26 formed counterpart 30 is formed so that between the radial securing element 26 and the counterpart 30 a system is made possible for radial securing of the vane segment 26 on the housing 30th

Fig. 3 shows the in Fig. 2 dashed rimmed area III, so that from this the radial securing element 26 with its support portion 27 and the counterpart 30 of the turbine housing 28 are better visible. The radial securing element 26 comprises at its support portion 27 a support surface 32 and a second surface 34. The counterpart 30 has a contact surface 36 which faces the support surface 32 of the radial securing element 26 lies. As seen from the sectional view, the support surface 32 and the second surface 34 are formed inclined to each other, and in the plane of the drawing (plane, which is spanned by the axial direction AR and the radial direction RR) include an angle β, preferably about 70 ° 90 °, in particular about 75 ° to 85 °. The contact surface 36 on the counterpart 30 of the housing 28 has substantially the same inclination, as the support surface 32. The interaction between the contact surface 32 and the abutment surface 36 allows the securing of the vane segment 10 in the radial direction RR.

Fig. 4 Figure 3 is a simplified perspective view of a blank vane segment 10a after casting such a workpiece. The above-mentioned components can be seen: outer shroud 14, front end wall 22, rear end wall 24, and the guide vanes 16. At the rear end wall 24, two raw radial securing elements 26a and 26b can be seen, which act as a kind of thickened projection against the axial direction AR protrude from the rear end wall 24. In an area of the rear end wall 24 that is central in the circumferential direction UR, a circumferential securing element 40 formed from two ribs can be seen, which is also still in its raw form after casting.

To form the finished molded radial securing elements 26 from the raw radial securing elements 26a and 26b as described with reference to FIGS Fig. 1 to 3 heretofore described, material is removed from the raw radial securing elements 26a, 26b, this being done by linear grinding. To show the FIGS. 5 and 6 For example, the (raw) vane segment 10 (10a) and a simplified and schematically illustrated linear grinding device 42 in different perspectives and relative arrangements to each other. The linear grinder 42 and the vane segment 10 are aligned with each other so that the linear grinder 42 with its grinding surfaces 44 comes into contact with one of the raw radial securing elements 26a, 26b. The linear grinding process is carried out until the radial securing element 26 or its support section 27 has reached its final shape, in particular the support surface 32 and the second surface 34 are formed. Starting from the raw vane segment 10a of Fig. 4 show the Fig. 5 a view in which the linear grinding device 42, the raw radial securing elements 26 b processed, and in Fig. 6 a representation in which the linear grinding device 42, the raw radial securing element 26 a processed. From each other Raw radial securing element 26a or 26b, which may already be present as a finished radial securing element 26, is in Fig. 5 respectively. Fig. 6 only one upper section visible.

As from the synopsis of 4 to 6 it can be seen, the guide vane segment 10 in the region of the outer shroud 14 respective shroud side surfaces 46 which are adapted to that adjacent vane segments 10 may abut each other in the mounted state in the gas turbine. The vane segment 10 in each case has two shroud side surfaces 46, wherein each shroud side surface 46 may be assigned a radial securing element 26. In this case, the respective radial securing element 26 may be flush with the shroud side surface 46, as exemplified by the Fig. 5 or even the Fig. 1 is apparent. Alternatively, the radial securing element 26 may be disposed to the shroud side surface 46 at a distance AB, as best shown in FIG Fig. 4 is apparent, but also in the Fig. 6 is indicated in the in the Fig. 6 left radial securing element 26 (26 a), which is shown in contact with the linear grinding device 42.

Like from the FIGS. 5 and 6 it can be seen, the linear grinding device in the contact region with the radial securing element 26 is not guided tangentially to the curvature formed in this contact region (along the circumferential direction UR) of the shroud 14 or the rear end wall 24. Rather, an angle γ is formed between a longitudinal axis LAS representing the grinding direction of the linear grinding device 42 and the tangential direction TR in the region of the radial securing element 26. As a result, the support surface 32 or / and the surface 34 formed by means of the linear grinding device 42 have normal vectors which, in addition to at least one vector component in the axial direction AR and / or radial direction RR, also have a vector component in the circumferential direction UR. Such relative positioning of linear grinder 42 and vane segment 10 relative to one another enables material to be removed from the radial securing elements 26 without the linear grinding device coming into contact with other components of the vane segment 10, particularly with the circumferential securing element 40 also along the circumferential direction UR is provided on the rear end wall 24 and protrudes counter to the axial direction AR thereof.

Fig. 7 shows a simplified schematic sectional view approximately along the section line VII-VII of Fig. 6 , From this representation, it can be seen that the linear grinding device 42 is designed in the region of its grinding surfaces 44 in such a way that it has a contour complementary to the radial securing element 26 or its bearing section 27. By means of this complementary grinding contour, it is possible that, by means of linear relative movement of the linear grinding device 42 along the longitudinal axis LAS of the linear grinding device, a successive material removal on a raw radial securing element 26a, 26b (FIG. Fig. 4 ) takes place until the finished radial securing element 26 is formed. Thus, a rather complex milling of the radial securing element (s) 26 can be dispensed with compared to the linear grinding.

Fig. 8 shows in the sub-figures A) and B) two highly simplified schematic sectional views of the support surface 32 of the radial securing element 26 to illustrate the vector components of the normal vector. Fig. 8A ) is a longitudinal section, as he also from the Fig. 1 it can be seen, wherein only the support surface 32 is shown as a line with the normal vector NV, and the vector components VRR and VAR in the radial or axial direction. Fig. 8B ) is a section corresponding to the line VIII-VIII of Fig. 3 , wherein the bearing surface 32 is shown hatched as a line and a portion of the cut radial securing element 26. Also in Fig. 8B ), the normal vector NV with the vector components VRR and VUR in the radial direction or circumferential direction, which are shown in this illustration, is shown for the bearing surface 32.

If the bearing surface 32 of the radial securing element 26 is inclined in the manner described, with its normal vector having a vector component VUR in the circumferential direction, this can lead to the bearing surface 32 not coming into contact with the abutment surface 36 of the counterpart 30, but only one There is contact between these two bearing surfaces 32, 36 along a line. However, not a full-surface system of radial securing element 26 and counterpart 30 is not considered disadvantageous, because no large forces are to support on the radial securing elements 26 at standstill of a gas turbine, in the operation of the same usually no forces on the radial securing elements 26 are supported. The radial securing elements should therefore be able to be produced inexpensively, which makes possible by means of linear grinding is, and provide a safeguard against falling out in the radial direction, in particular in the assembly / disassembly of stator segments of a turbine stage of a gas turbine.

LIST OF REFERENCE NUMBERS

10

vane segment

10a

Raw vane segment

12

inner shroud

14

outer shroud

16

vane

18

suction

20

trailing edge

22

front end wall

24

rear end wall

26

Radial fuse element

26a

Crude radial securing element

26b

Crude radial securing element

27

bearing section

28

casing

30

counterpart

32

bearing surface

34

area

36

contact surface

40

Perimeter security element

42

Linear grinding device

44

grinding surface

46

Shroud side face

FROM

distance

AR

axial direction

READ

Longitudinal axis (linear grinding device 42)

NV

normal vector

RR

radial direction

TR

tangential

UR

circumferentially

VAR

Vector component in the axial direction

VRR

Vector component in the radial direction

VUR

Vector component in the circumferential direction

Claims (15)

1. Guide vane segment (10) for a gas turbine, in particular an aircraft gas turbine, comprising
   at least one radially outer shroud (14) and one radially inner shroud (12), which extend along a particular circular arc and together form a ring portion,
   a plurality of guide vanes (16) being arranged, in the radial direction (RR) between the outer shroud (14) and the inner shroud (12), side by side in the circumferential direction (UR), which guide vanes are integrally joined, in particular as one part, with the inner shroud (12) and the outer shroud (14),
   the outer shroud (14) comprising an axially front end-wall element (22) and an axially rear end-wall element (24) in an axial longitudinal direction (AR) such that the outer shroud (14) and the two end walls (22, 24) form a trough-like profile in longitudinal cross section,
   at least one radial securing element (26) being provided on the axially rear end wall (24), which securing element is designed to secure the guide vane segment (10) in the radial direction (RR) relative to a surrounding housing (28, 30),
   the radial securing element (26) being in the form of a projection comprising a support portion (27) which is designed to be supported on a corresponding counter member (30) on the housing (28),
   characterized in that
   the support portion (27) has a support surface (32) which lies in a plane of which the normal vector has a vector component (VUR) in the circumferential direction (UR) and in the radial direction (RR).
2. Guide vane segment according to claim 1, characterized in that the support portion (27) has a support surface (32) which lies in a plane of which the normal vector has a vector component (VAR) in the axial direction (AR).
3. Guide vane segment according to either claim 1 or claim 2, characterized in that it has, in the circumferential direction (UR) on the outer shroud (14), two shroud side surfaces (46) which are arranged at a distance from each other and are designed to be able to come into contact with a shroud side surface of an adjacent guide vane segment, the radial securing element (26) being flush with at least one shroud side surface (46).
4. Guide vane segment according to claim 3, characterized in that it comprises two radial securing elements (26) arranged at a distance from each other in the circumferential direction.
5. Guide vane segment according to claim 4, characterized in that one radial securing element (26) is flush with one of the shroud side surfaces (46) and in that the other radial securing element (26) is arranged at a distance (AB) from the other shroud side surface (46).
6. Guide vane segment according to either claim 4 or claim 5, characterized in that the distance, measured in the circumferential direction, between the two radial securing elements (26) is smaller than the distance, measured in the circumferential direction, between the two shroud side surfaces (46).
7. Guide vane segment according to any of the preceding claims, characterized in that the radial securing element (26) is produced by linear grinding.
8. Guide vane segment according to any of the preceding claims, characterized in that the support portion (27) has a second surface (34) which lies in a second plane of which the normal vector has vector components in the circumferential direction and in the radial direction (RR).
9. Guide vane segment according to claim 8, characterized in that the normal vector of the second plane has vector components in the axial direction (AR).
10. Guide vane segment according to either claim 8 or claim 9, characterized in that the second surface (34) and the support surface (32) are inclined towards each other, the angle (β) formed by the first and the second plane, in a cutting plane which is spanned by the radial direction (RR) and the axial direction (AR), being in a range of between 70° and 90°, preferably 75° and 85°.
11. Guide vane segment according to any of the preceding claims, characterized in that it comprises a circumferential securing element (40) in the circumferential direction (UR) in a central region of the rear end wall (24).
12. Method for producing a guide vane segment (10) for a gas turbine, in particular an aircraft gas turbine, comprising the following steps:

    providing a blank guide vane segment (10a) comprising at least one radially outer shroud (14) and one radially inner shroud (12), which extend along a particular circular arc and together form a ring portion, a plurality of guide vanes (16) being arranged, in the radial direction (RR) between the outer shroud (14) and the inner shroud (12), side by side in the circumferential direction (UR), which guide vanes are integrally joined, in particular as one part, with the inner shroud (12) and the outer shroud (14), the outer shroud (14) comprising an axially front end-wall element (22) and an axially rear end-wall element (24) in an axial longitudinal direction (AR) such that the outer shroud (14) and the two end walls (22, 24) form a trough-like profile in longitudinal cross section, and comprising at least one blank radial securing element (26a, 26b);

    orienting the blank guide vane segment relative to a linear grinding apparatus (42) such that material of the blank radial securing element (26a, 26b) can be removed by means of the linear grinding apparatus (42);

    grinding off the blank radial securing element (26a, 26b) by means of the linear grinding apparatus (42) until the blank radial securing element (26a, 26b) has assumed the shape of a radial securing element (26) comprising a support portion (27) having a support surface (32) which lies in a first plane of which the normal vector has vector components in the circumferential direction and in the radial direction (RR), in particular also in the axial direction (AR).
13. Method according to claim 12, wherein the step of orienting the blank guide vane segment (26a, 26b) and the step of grinding off are carried out once per blank radial securing element (26a, 26b) if two or more blank radial securing elements (26a, 26b) are provided on the blank guide vane segment (10a).
14. Method according to either claim 12 or claim 13, wherein the step of orienting the blank guide vane segment (10a) relative to the linear grinding apparatus (42) is carried out such that the linear grinding apparatus (42) can be guided or moved, during the grinding of the blank radial securing element (26a, 26b), at a distance from the other components of the blank guide vane segment (10a), in particular at a distance from a circumferential securing element (40) provided on the rear end wall (24) in a central region in the circumferential direction (UR) or at a distance from a corresponding blank circumferential securing element.
15. Gas turbine, in particular aircraft gas turbine, comprising at least one turbine stage having a plurality of guide vane segments (10) according to any of claims 1 to 11, which vane segments are arranged side by side in the circumferential direction such that they form a guide vane ring of the turbine stage.

Images