Steam turbine rotor, steam turbine, and method for fixing moving blades

Abstract

To restrain motor blades with keys easily without fail.SOLUTION: A rotor of a steam turbine includes: a shaft core part; disc parts; multiple rotor blades respectively attached to the disc parts; and keys which restrict movement of the rotor blades in an axial direction. The disc part has a blade embedded groove and a circumferential groove. The rotor blade has a blade root embedded in the blade embedded groove, a platform, and a blade body. The multiple rotor blades include first rotor blades and second rotor blades each of which is located adjacent to the first rotor blade at one side in a circumferential direction. The platform of the first rotor blade has an access groove which is recessed so as to be open in the axial direction and the circumferential direction and communicates with the circumferential groove. The platform of the second rotor blade has: a second surface facing a first surface in the circumferential direction; and a key housing groove communicating with the access groove in the circumferential direction. The key is disposed in the circumferential groove and the key housing groove.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a rotor for a steam turbine, a steam turbine, and a method for securing a rotor blade. [Background technology]

[0002] A steam turbine includes a rotor that rotates about an axis and a casing that covers the rotor. The rotor includes a rotor shaft that extends axially about the axis and multiple rows of moving blade rows that are fixed to the outer periphery of the rotor shaft and aligned axially. The steam turbine includes a stator blade row that is fixed to the inner periphery of the casing and is arranged upstream of each of the multiple rows of moving blade rows. Each row of moving blade rows includes multiple moving blades arranged in the circumferential direction of a rotor disk. The moving blades protrude radially from the outer periphery of the rotor disk.

[0003] The rotor blades are fixed to the rotor disk by inserting their blade roots into a plurality of blade grooves formed at circumferential intervals on the outer peripheral surface of the rotor disk. The blade grooves penetrate the rotor disk in the axial direction. The rotor blade roots are attached to the rotor disk by inserting them axially into the blade grooves of the rotor disk.

[0004] During operation of a steam turbine, steam is sent into the casing and flows through the casing from the first side to the second side in the axial direction. As a result, a force is exerted on the rotor blades by the fluid pressure of the steam, pushing them from the first side to the second side in the axial direction. It is necessary to prevent the rotor blades from shifting axially relative to the blade grooves due to this pushing force from the steam.

[0005] In response to this, for example, Patent Document 1 describes a structure that uses a key (fixing member) to axially restrain the rotor blade relative to the blade groove of the rotor disk. In this structure, the key is inserted into a second notch formed in the rotor disk through a first notch formed through the platform of the rotor blade. A portion of the outer periphery of the key is covered by the platform, and the key is plastically deformed so that it can support the thrust force of the rotor blade. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-185367 Summary of the Invention [Problem to be solved by the invention]

[0007] However, with the configuration described in Patent Document 1, the key must be plastically deformed after being inserted into the second notch through the first notch, which makes key installation time-consuming. Also, if the plastic deformation of the key is incomplete, the key may not be fixed properly.

[0008] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a steam turbine rotor, a steam turbine, and a method for fixing a moving blade that can easily and reliably restrain the moving blade with a key. [Means for solving the problem]

[0009] In order to solve the above problems, a steam turbine rotor according to the present disclosure has an axial core portion formed in a cylindrical shape centered on an axis, a disk portion extending radially outward relative to the axial core portion with the axis as a reference, a plurality of moving blades attached to the disk portion, and keys for restricting movement of the moving blades relative to the disk portion in the axial direction along which the axis extends, the disk portion having a plurality of blade embedding grooves recessed radially inward from an outer circumferential surface thereof and extending in the axial direction, the plurality of blade embedding grooves being formed at intervals in a circumferential direction centered on the axis, and a circumferential groove recessed radially inward from the outer circumferential surface thereof and extending in the circumferential direction, the moving blades having blade roots embedded in the blade embedding grooves, platforms disposed radially outward relative to the disk portion and projecting on both sides in the circumferential direction relative to the blade roots, and and a blade body extending radially outward, wherein the plurality of blades include a first blade and a second blade adjacent to the first blade on one side in the circumferential direction, the platform of the first blade having, in the circumferential direction, a first side surface facing the platform of the second blade, a first end surface facing the axial direction, and an access groove recessed to open in the axial direction and the circumferential direction at a corner formed by the first side surface and the first end surface and communicating with the circumferential groove, the platform of the second blade having, in the circumferential direction, a second side surface opposing the first side surface, and a key groove recessed in the circumferential direction from the second side surface and communicating with the circumferential groove in the radial direction and also communicating with the access groove in the circumferential direction, the key being disposed in the circumferential groove and the key groove. The access groove has an access groove side surface facing the second side surface in the circumferential direction, and further includes a restraining member disposed in the access groove between the key and the access groove side surface in the circumferential direction and restraining movement of the key approaching the access groove side surface in the circumferential direction, and the disk portion has a punching portion on a disk surface facing the axial direction so as to be perpendicular to the outer circumferential surface and recessed from the disk surface so as to deform the outer circumferential surface facing the access groove when viewed from the axial direction, and movement of the restraining member in the circumferential direction is restrained by the punching portion. .

[0010] A steam turbine according to the present disclosure includes a rotor of the steam turbine as described above.

[0011] A method for fixing a blade according to the present disclosure is a method for fixing the blade in a rotor of a steam turbine as described above, and includes the steps of attaching the second blade to the disk portion, inserting the key into the circumferential groove, moving the key in the circumferential groove in the circumferential direction and inserting it into the key receiving groove, and attaching the first blade to the disk portion. [Effects of the Invention]

[0012] According to the steam turbine rotor, the steam turbine, and the method for fixing the moving blades of the present disclosure, the moving blades can be easily and reliably restrained by the keys. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view of a steam turbine in accordance with an embodiment of the present disclosure. [Figure 2] 1 is a view showing a part of a rotor blade of a steam turbine according to a first embodiment of the present disclosure, viewed from the downstream side in the axial direction. FIG. [Figure 3] 2. FIG. 3 is a cross-sectional view taken along the arrow II in FIG. 2, schematically showing the fixing structure of the rotor blade according to the first embodiment of the present disclosure, as viewed from the circumferential direction. [Figure 4] 2 is a cross-sectional view taken along the line II-II in FIG. 3, schematically illustrating the fixing structure of the rotor blade according to the first embodiment of the present disclosure, as viewed from the axial direction. FIG. [Figure 5] 3 is a cross-sectional view taken along the line III-III in FIG. 2, schematically illustrating the fixing structure of the rotor blade according to the first embodiment of the present disclosure, as viewed from the radial direction. FIG. [Figure 6] 3 is a flowchart showing the flow of a blade fixing method according to the first embodiment of the present disclosure. [Figure 7] FIG. 4 is a diagram showing a step of inserting a key into a circumferential groove in the blade fixing method according to the first embodiment of the present disclosure. [Figure 8] FIG. 4 is a view showing a step of inserting a key into a key receiving groove in the blade fixing method according to the first embodiment of the present disclosure. [Figure 9]3A to 3C are diagrams showing a step of attaching a first blade and a step of arranging a restraining member in a blade fixing method according to a first embodiment of the present disclosure. [Figure 10] FIG. 4 is a diagram schematically illustrating a fixing structure of a rotor blade according to a modified example of the first embodiment of the present disclosure. [Figure 11] FIG. 4 is a cross-sectional view, viewed from the axial direction, schematically illustrating a fixing structure for a rotor blade according to a second embodiment of the present disclosure. [Figure 12] FIG. 10 is a cross-sectional view seen from the radial direction, schematically illustrating a fixing structure for a rotor blade according to a second embodiment of the present disclosure. [Figure 13] FIG. 10 is a perspective view showing the configuration of a key of a fixing structure for a rotor blade according to a second embodiment of the present disclosure. [Figure 14] 10 is a flowchart showing the flow of a blade fixing method according to a second embodiment of the present disclosure. [Figure 15] 10A and 10B are views showing a step of inserting a key into a circumferential groove and a step of inserting a key into a key receiving groove in a method of fixing a rotor blade according to a second embodiment of the present disclosure. [Figure 16] FIG. 10 is a cross-sectional view, viewed from the axial direction, schematically illustrating a fixing structure for a rotor blade according to a third embodiment of the present disclosure. [Figure 17] FIG. 10 is a cross-sectional view seen from the radial direction, schematically illustrating a fixing structure for a rotor blade according to a third embodiment of the present disclosure. [Figure 18] FIG. 10 is a perspective view showing the configuration of a key of a rotor blade fixing structure according to a third embodiment of the present disclosure. [Figure 19] 10 is a flowchart showing the flow of a blade fixing method according to a third embodiment of the present disclosure. [Figure 20] FIG. 11 is a cross-sectional view seen from the radial direction showing a step of inserting a key into a circumferential groove in a method for fixing a rotor blade according to a third embodiment of the present disclosure. [Figure 21] FIG. 11 is a cross-sectional view seen from the axial direction showing a step of inserting a key into a circumferential groove in a method for fixing a rotor blade according to a third embodiment of the present disclosure. [Figure 22] FIG. 11 is a cross-sectional view seen from the axial direction showing a step of inserting a key into a key receiving groove in a blade fixing method according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments for carrying out a steam turbine rotor, a steam turbine, and a method for fixing a moving blade according to the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure is not limited to these embodiments.

[0015] First Embodiment (Overall configuration of steam turbine) As shown in FIG. 1, the steam turbine 1 of this embodiment includes a rotor 20 that rotates about an axis Ar, and a casing 10 that covers the rotor 20 so that the rotor 20 is rotatable.

[0016] For the sake of convenience in the following description, the direction in which the axis Ar extends will be referred to as the axial direction Da. The first side of the axial direction Da will be referred to as the upstream side Dau, and the second side of the axial direction Da will be referred to as the downstream side Dad. The radial direction of the rotor 20 based on the axis Ar will simply be referred to as the radial direction Dr. The side of the radial direction Dr that approaches the axis Ar will be referred to as the inner side Dri of the radial direction Dr, and the side of the radial direction Dr opposite the inner side Dri of the radial direction Dr will be referred to as the outer side Dro of the radial direction Dr. The circumferential direction of the rotor 20 centered on the axis Ar will simply be referred to as the circumferential direction Dc.

[0017] The rotor 20 has a rotor shaft 21, a row of rotor blades 31, a key 50A (see FIG. 2), and a restraining member 60 (see FIG. 2). The rotor shaft 21 extends in the axial direction Da with the axis Ar as its center. The rotor shaft 21 has a core portion 22 and a plurality of disk portions 23. The core portion 22 is formed in a cylindrical shape extending in the axial direction Da. The plurality of disk portions 23 extend from the core portion 22 to the outside Dro in the radial direction Dr. The plurality of disk portions 23 are arranged at intervals from one another in the axial direction Da. The disk portions 23 are arranged to correspond to each of the plurality of row of rotor blades 31.

[0018] The casing 10 is formed with a nozzle chamber 11 into which steam S flows from the outside, a main flow path chamber 12 through which the steam S flows from the nozzle chamber 11, and an exhaust chamber 13 through which the steam S that has flowed from the main flow path chamber 12 is exhausted. The nozzle chamber 11, the main flow path chamber 12, and the exhaust chamber 13 form a main steam flow path 15 within the casing 10 through which high-pressure steam S flows.

[0019] High-pressure steam S flows through the main steam flow passage 15 from the upstream side Dau to the downstream side Dad, in the order of the nozzle chamber 11, the main flow passage chamber 12, and the exhaust chamber 13, with the pressure gradually decreasing. In other words, the flow direction of the steam S in this embodiment is from the upstream side Dau to the downstream side Dad in the axial direction Da. The main steam flow passage 15 is formed in an annular shape around the rotor shaft 21. The main steam flow passage 15 extends in the axial direction Da across multiple rotor blade rows 31 and stator blade rows 41.

[0020] 1 and 2, the rotor blade rows 31 are attached to the outer periphery of the disk portion 23, which is the outer periphery of the rotor shaft 21. A plurality of rows of the rotor blade rows 31 are arranged at intervals in the axial direction Da of the rotor shaft 21. In the present embodiment, seven rotor blade rows 31 are provided. Therefore, in the present embodiment, first to seventh stages of the rotor blade rows 31 are provided.

[0021] Each rotor blade row 31 has a plurality of rotor blades 32 arranged in the circumferential direction Dc. The plurality of rotor blades 32 are each attached to the disk portion 23. Each rotor blade 32 has a blade root 36 (see FIG. 2), a platform 35, a shroud 34, and a blade body 33.

[0022] As shown in FIG. 2, the blade root 36 is embedded in a blade embedding groove 28 (described later) formed in the disk portion 23. The blade root 36 is formed to extend from a platform inner peripheral surface 35f of the platform 35 (described later) to the inner side Dri in the radial direction Dr. The blade root 36 has engaging protrusions 36t that protrude toward both sides in the circumferential direction Dc. The engaging protrusions 36t are provided at multiple locations spaced apart in the radial direction Dr. The multiple engaging protrusions 36t are formed so that the protrusion dimension in the circumferential direction Dc gradually decreases toward the inner side Dri in the radial direction Dr. This gives the blade root 36 a so-called Christmas tree shape.

[0023] The disk portion 23 is formed with blade embedding grooves 28 into which the blade roots 36 are embedded. A plurality of blade embedding grooves 28 are formed at intervals in the circumferential direction Dc. The blade embedding grooves 28 are recessed from the outer circumferential surface of the disk portion 23 toward the inner side Dri in the radial direction Dr. The blade embedding grooves 28 extend in the axial direction Da and are formed so as to penetrate through the disk portion 23 in the axial direction Da. The blade embedding grooves 28 are formed to correspond to the outer circumferential shape of the blade root 36. The blade embedding grooves 28 have engaging recesses 28a with which the engaging protrusions 36t engage. The engaging recesses 28a are formed in the blade embedding grooves 28 at multiple locations spaced apart in the radial direction Dr, recessed toward both sides in the circumferential direction Dc. The disk portion 23 also has an outer circumferential surface 23f facing the outer side Dro in the radial direction Dr, and a disk surface 23d facing the downstream side Dad in the axial direction Da. The disk surface 23d is a surface that is perpendicular to the outer peripheral surface 23f. The outer peripheral surface 23f is a surface of the disk portion 23 that is located on the outermost side Dro in the radial direction Dr.

[0024] The platform 35 is disposed on the outer side Dro in the radial direction Dr relative to the disk portion 23. The platform 35 extends in the circumferential direction Dc. The platform 35 protrudes on both sides in the circumferential direction Dc relative to the blade root 36. When viewed from the outer side Dro in the radial direction Dr, the platform 35 has a rectangular shape that is longer in the axial direction Da than in the circumferential direction Dc (see FIG. 5). The platforms 35 of the multiple rotor blades 32 are aligned in the circumferential direction Dc to form a cylindrical shape centered on the axis Ar as a whole. The platform 35 has a platform inner peripheral surface 35f facing the inner side Dri in the radial direction Dr and a platform outer peripheral surface 35g facing the outer side Dro in the radial direction Dr. Furthermore, the platform 35 has a first side surface 35s facing the circumferential direction Dc and a second side surface 35t facing the opposite side from the first side surface 35s in the circumferential direction Dc. Furthermore, the platform 35 has a first end surface 35d facing the downstream side Dad in the axial direction Da.

[0025] The blade body 33 extends from the platform outer peripheral surface 35g to the outside Dro in the radial direction Dr. In other words, in the radial direction Dr, the blade body 33 is disposed on the opposite side of the platform 35 from the blade root 36. The blade body 33 is formed integrally with the shroud 34. The blade body 33 is disposed in the main steam flow path 15. The blade body 33 has an airfoil cross section when viewed from the outside in the radial direction Dr.

[0026] The shroud 34 is connected to an end portion of the blade body 33 on the outer side Dro in the radial direction Dr. In other words, in the radial direction Dr, the shroud 34 is disposed on the opposite side of the blade body 33 from the platform 35. The shroud 34 extends in the circumferential direction Dc. The shrouds 34 of the multiple rotor blades 32 are aligned in the circumferential direction Dc to form a cylindrical shape as a whole.

[0027] The space surrounded by the blade bodies 33 adjacent to each other in the circumferential direction Dc and the shrouds 34 and platforms 35 opposing each other in the radial direction Dr is an inter-blade flow passage 15w through which the steam S flows. A plurality of rotor blades 32 are arranged in the circumferential direction Dc inside the casing 10, thereby forming a plurality of such inter-blade flow passages 15w in the circumferential direction Dc. The plurality of inter-blade flow passages 15w aligned in the circumferential direction Dc form a part of the main steam flow passage 15 through which the steam S flows.

[0028] As shown in Fig. 1, the steam turbine 1 is provided with a plurality of stator blade rows 41 fixed to the inner peripheral surface of the casing 10 and arranged at intervals in the axial direction Da. In the present embodiment, the number of stator blade rows 41 is seven, the same as the number of rotor blade rows 31. Therefore, in the present embodiment, first to seventh stages of stator blade rows 41 are provided. The plurality of stator blade rows 41 are arranged adjacent to the respective rotor blade rows 31 on the upstream side Dau.

[0029] The stator vane row 41 has a plurality of stator vanes 42, an outer ring 43, and an inner ring 46. The plurality of stator vanes 42 are arranged at intervals in the circumferential direction Dc. The outer ring 43 is formed in an annular shape and is arranged on the outer side Dro of the plurality of stator vanes 42 in the radial direction Dr. The inner ring 46 is formed in annular shape and is arranged on the inner side Dri of the plurality of stator vanes 42 in the radial direction Dr. That is, the plurality of stator vanes 42 are arranged between the outer ring 43 and the inner ring 46. The stator vanes 42 are fixed to the outer ring 43 and the inner ring 46. The annular space between the outer ring 43 and the inner ring 46 forms a part of the main steam flow path 15 through which the steam S flows.

[0030] In this steam turbine 1, steam S is sent from the upstream side Dau of the casing 10 through the nozzle chamber 11. This steam S passes through the main flow passage chamber 12 and flows into the exhaust chamber 13 on the downstream side Dad. As a result, the rotor shaft 21 rotates about the axis Ar, and each rotor blade 32 rotates around the axis Ar together with the disk portion 23. At this time, in each rotor blade 32, steam S flows through the inter-blade flow passages 15w between the blade bodies 33 adjacent to each other in the circumferential direction Dc.

[0031] (Rotor blade fixing structure) 2 to 5, in the steam turbine 1, a key 50A restricts each rotor blade 32 from moving in the axial direction Da relative to the disk portion 23. The key 50A is disposed inside a circumferential groove 25 formed in the disk portion 23 and a key receiving groove 355 formed in the platform 35.

[0032] As shown in FIG. 3 , the circumferential groove 25 is formed on the outer peripheral surface 23f of the disk portion 23 downstream Dad of the intermediate portion in the axial direction Da. The circumferential groove 25 is formed to have a size that allows the key 50A to be inserted therein. The circumferential groove 25 is formed to be recessed from the outer peripheral surface 23f of the disk portion 23 toward the inner side Dri in the radial direction Dr. The circumferential groove 25 is formed at a position shifted upstream Dau with respect to the disk surface 23d in the axial direction Da so as not to connect with the disk surface 23d. As shown in FIGS. 4 and 5 , the circumferential groove 25 extends in the circumferential direction Dc. In this embodiment, the circumferential groove 25 is formed between the blade-embedded grooves 28 so as to connect the blade-embedded grooves 28 adjacent to each other in the circumferential direction Dc. In other words, the circumferential groove 25 is formed to overlap with the platforms 35 of the rotor blades 32 adjacent to each other in the circumferential direction Dc. The circumferential groove 25 may be formed only in the portion in the circumferential direction Dc where the key 50A is inserted.

[0033] The key groove 355 is formed in the platform 35 at an end portion on the other side Dc2 in the circumferential direction Dc. The key groove 355 is formed with a size that allows the key 50A to be inserted therein. The key groove 355 is formed at a position that overlaps with the circumferential groove 25 in the axial direction Da and the circumferential direction Dc when the blade root 36 is embedded in the blade embedding groove 28. The key groove 355 is formed in the platform 35, recessed from the second side surface 35t facing the other side Dc2 in the circumferential direction Dc to one side Dc1 in the circumferential direction Dc. The key groove 355 is recessed from the platform inner circumferential surface 35f to the outer side Dro in the radial direction Dr. The key groove 355 is formed at a position away from the first end face 35d in the axial direction Da. In other words, the key groove 355 is formed so as to be open only at the second side surface 35t and the platform inner circumferential surface 35f. The key groove 355 communicates with the circumferential groove 25 in the radial direction Dr. The key receiving groove 355 communicates with an access groove 357, which will be described later, in the circumferential direction Dc.

[0034] The platform 35 has an access groove 357. The access groove 357 is formed at a position overlapping the key receiving groove 355 when viewed from the circumferential direction Dc. The access groove 357 is formed to have a size that allows the key 50A to be inserted therein. The access groove 357 is formed at an end of one side Dc1 of the platform 35 in the circumferential direction Dc. The access groove 357 is recessed from a first side surface 35s facing the one side Dc1 in the circumferential direction Dc to the other side Dc2 in the circumferential direction Dc in the platform 35. The access groove 357 is recessed from a first end surface 35d facing the downstream side Dad in the axial direction Da to an upstream side Dau in the axial direction Da in the platform 35. In other words, the access groove 357 is formed at a corner 35c formed by the first side surface 35s and the first end surface 35d so as to open to the downstream side Dad in the axial direction Da and the one side Dc1 in the circumferential direction Dc. The access groove 357 has a depth (length) in the circumferential direction Dc that is deeper than the key groove 355 and the key 50A. The access groove 357 is formed at a position that overlaps with the key groove 355 when viewed in the circumferential direction Dc. The access groove 357 communicates with the circumferential groove 25 in the radial direction Dr. The access groove 357 of this embodiment has an access groove side surface 357s that faces one side Dc1 in the circumferential direction Dc, and an access groove end surface 357d that faces the downstream side Dad in the axial direction Da.

[0035] Of the multiple rotor blades 32, one of a pair of rotor blades 32 adjacent in the circumferential direction Dc is referred to as the first rotor blade 32A, and the rotor blade 32 arranged on one side Dc1 in the circumferential direction Dc of the first rotor blade 32A is referred to as the second rotor blade 32B. A first side surface 35s of the first rotor blade 32A and a second side surface 35t of the second rotor blade 32B face each other in the circumferential direction Dc. Therefore, an access groove 357 formed in the platform 35 of the first rotor blade 32A and a key groove 355 formed in the platform 35 of the second rotor blade 32B communicate with each other in the circumferential direction Dc. When viewed from the radial direction Dr, the circumferential groove 25 is formed to span from a position overlapping with the platform 35 of the second rotor blade 32B to a position overlapping with the platform 35 of the first rotor blade 32A. Therefore, the circumferential groove 25 communicates with the access groove 357 of the first rotor blade 32A and the key receiving groove 355 of the second rotor blade 32B.

[0036] The key 50A restricts movement of the rotor blade 32 (second rotor blade 32B) in the axial direction Da relative to the disk portion 23. The key 50A is inserted into the key groove 355 and the circumferential groove 25. The key 50A in this embodiment has, for example, a rectangular parallelepiped block shape. The key 50A is shaped to be movable in the circumferential groove 25 in the circumferential direction Dc. The key 50A is movable between the key groove 355 and the access groove 357 by moving in the circumferential groove 25 in the circumferential direction Dc. The length of the key 50A in the axial direction Da is the same as that of the circumferential groove 25 and the key groove 355 so that the key 50A is in sliding contact with the circumferential groove 25 and the key groove 355. As shown in FIGS. 3 and 4 , an inner region Dri of the key 50A in the radial direction Dr is accommodated in the circumferential groove 25. An outer region Dro of the key 50A in the radial direction Dr is inserted into the key groove 355.

[0037] As shown in Fig. 4, a portion of the key 50A, including the end 51e on the other side Dc2 in the circumferential direction Dc, protrudes from the second side surface 35t of the platform 35 toward the other side Dc2 in the circumferential direction Dc when the key 50A is housed in the circumferential groove 25 and the key groove 355. As shown in Fig. 5, even when the key 50A is housed in the circumferential groove 25 and the key groove 355, the region including the end 51e is in contact with the access groove end face 357d. Furthermore, the key 50A is formed to a size that does not protrude into the key groove 355 when housed in the circumferential groove 25 and the access groove 357.

[0038] A restraining member 60 is disposed within the access groove 357 of the first embodiment. The restraining member 60 restrains the movement of the key 50A toward the access groove side surface 357s in the circumferential direction Dc. The restraining member 60 is disposed between the key 50A accommodated in the circumferential groove 25 and the key accommodating groove 355 and the access groove side surface 357s in the circumferential direction Dc. In other words, the restraining member 60 restricts the movement of the key 50A accommodated in the circumferential groove 25 and the key accommodating groove 355 toward the access groove side surface 357s.

[0039] The restraining member 60 of this embodiment is formed in the shape of a rectangular parallelepiped block that is larger than the key 50A. The restraining member 60 is shaped to be movable in the axial direction Da within the access groove 357. By moving the restraining member 60 in the axial direction Da within the access groove 357, the restraining member 60 can be inserted into the access groove 357 with the key 50A accommodated in the key accommodating groove 355. The restraining member 60 is formed so that an end 60d on the downstream side Dad of the restraining member 60 in the axial direction Da does not protrude from the disk surface 23d. In this embodiment, the end 60d of the restraining member 60 is located at the same position in the axial direction Da as the disk surface 23d.

[0040] As shown in FIG. 2, the restraint member 60 is restrained from moving in the axial direction Da while housed in the access groove 357 by a punching portion 100P formed on the disk surface 23d. The punching portion 100P is a region that is plastically deformed by punching the disk surface 23d. When viewed from the axial direction Da, the punching portion 100P is recessed from the disk surface 23d so as to deform the outer circumferential surface 23f facing the access groove 357. When viewed from the axial direction Da, the punching portion 100P is formed at a position that overlaps with the circumferential groove 25. When viewed from the axial direction Da, the punching portion 100P is formed on the inner side Dri in the radial direction Dr of the access groove 357.

[0041] Note that the punching portions 100P restrain the movement of the restraint members 60 in the axial direction Da and the circumferential direction Dc, but do not restrain the movement of the rotor blades 32 in the axial direction Da, which are subjected to the pressure of the steam flow S flowing inside the casing 10. Therefore, no large pressure acts on the punching portions 100P, and peeling of the punching portions 100P is suppressed. Furthermore, as long as the punching portions 100P are formed in positions that allow them to restrain the movement of the restraint members 60 in the circumferential direction Dc, it is not necessary for them to restrain the movement of the restraint members 60 in the axial direction Da.

[0042] In this way, by disposing the key 50A in the circumferential groove 25 and the key accommodating groove 355, the second rotor blade 32B is restrained from moving in the axial direction Da relative to the disk portion 23. Furthermore, by inserting the restraining member 60 between the key 50A and the access groove side surface 357s, the key 50A disposed in the circumferential groove 25 and the key accommodating groove 355 cannot move to the other side Dc2 in the circumferential direction Dc. As a result, the key 50A is prevented from coming out of the circumferential groove 25 and the key accommodating groove 355.

[0043] (Procedure for fixing rotor blades) Next, a blade fixing method S10 for fixing the above-described blade 32 to the disk portion 23 with the key 50A will be described. As shown in Fig. 6, the blade fixing method S10 according to the first embodiment includes the steps of attaching the second blade 32B, inserting the key 50A into the circumferential groove 25, inserting the key 50A into the key receiving groove 355, attaching the first blade 32A, arranging the restraining member 60, and fixing the restraining member 60.

[0044] In step S11 of attaching the second rotor blade 32B, one rotor blade 32 is attached to the disk portion 23 as the second rotor blade 32B. Specifically, as shown in FIG. 2, the blade root 36 is embedded in the blade embedding groove 28 of the disk portion 23. The blade root 36 is inserted into the blade embedding groove 28, for example, by moving it from the upstream side Dau in the axial direction Da to the downstream side Dad in the axial direction Da. As shown in FIG. 7, the second rotor blade 32B is moved until the first end face 35d is in the same position as the disk surface 23d in the axial direction Da.

[0045] In step S12 of inserting the key 50A into the circumferential groove 25, the key 50A is inserted into the circumferential groove 25. In step S12 of this embodiment, one key 50A is attached to the disk portion 23 to which the second rotor blade 32B is attached. When viewed from the radial direction Dr, the key 50A is inserted into the circumferential groove 25 at a position shifted in the circumferential direction Dc from the position where the second rotor blade 32B is disposed. Specifically, the key 50A is disposed in the circumferential groove 25 at a position away from the second side surface 35t of the second rotor blade 32B in the circumferential direction Dc2 (in this embodiment, the position where the first rotor blade 32A will be disposed later) so as not to overlap with the second rotor blade 32B. The key 50A is moved from the outer side Dro to the inner side Dri in the radial direction Dr, so that a region of the key 50A on the inner side Dri in the radial direction Dr is disposed in the circumferential groove 25.

[0046] In step S13 of inserting the key 50A into the key groove 355, as shown in FIG. 8 , the key 50A is moved in the circumferential groove 25 in the circumferential direction Dc and inserted into the key groove 355. Specifically, the key 50A is moved to one side Dc1 in the circumferential direction Dc within the circumferential groove 25. As a result, the key 50A is inserted into the key groove 355 that opens at the second side surface 35t of the second rotor blade 32B from a position that is offset in the circumferential direction Dc from the position where the second rotor blade 32B is disposed. In other words, the key 50A is moved so that it overlaps with the position where the second rotor blade 32B is disposed when viewed from the radial direction Dr. By inserting the key 50A into the key groove 355, the key 50A is inserted into the key groove 355 and the circumferential groove 25 at a position where it overlaps with the second rotor blade 32B. Furthermore, when the key 50A is accommodated in the key groove 355, the end 51e of the key 50A is disposed at a position protruding from the second side surface 35t to the other side Dc2 in the circumferential direction Dc. In this state, an area of ​​the key 50A on the inner side Dri in the radial direction Dr is accommodated in the circumferential groove 25, and an area of ​​the key 50A on the outer side Dro in the radial direction Dr is inserted into the key groove 355. As a result, movement of the second rotor blade 32B in the axial direction Da relative to the disk portion 23 is restricted by the key 50A.

[0047] In step S14 of attaching the first rotor blade 32A, as shown in FIG. 9, one rotor blade 32 is attached to the disk portion 23 as the first rotor blade 32A. Specifically, the first rotor blade 32A is attached to a position adjacent to the second rotor blade 32B on the other side Dc2 in the circumferential direction Dc. At this time, similar to step S11, the blade root 36 is embedded in the blade embedding groove 28. When the blade root 36 is embedded in the blade embedding groove 28, the end 51e of the key 50A protrudes from the second side surface 35t of the second rotor blade 32B to the other side Dc2 in the circumferential direction Dc. Therefore, when the blade root 36 of the first rotor blade 32A is moved toward the downstream side Dad in the axial direction Da, the access groove end face 357d of the access groove 357 of the first rotor blade 32A abuts against the end 51e. As a result, during the process of attaching the first rotor blade 32A, movement of the first rotor blade 32A to the downstream side Dad in the axial direction Da is restricted.

[0048] Step S15 of disposing the restraining member 60 is performed after the first rotor blade 32A and the second rotor blade 32B are attached to the disk portion 23 and the key 50A is inserted into the key receiving groove 355. In step S15 of disposing the restraining member 60, the restraining member 60 is disposed in the access groove 357 of the first rotor blade 32A. Specifically, the restraining member 60 is inserted into the access groove 357 from the downstream side Dad in the axial direction Da. The restraining member 60 is inserted to a position where it contacts the access groove end face 357d. As a result, the restraining member 60 is inserted between the key 50A and the access groove side surface 357s. This restricts movement of the key 50A toward the access groove side surface 357s in the circumferential direction Dc.

[0049] In step S16 of fixing the restraining member 60, the restraining member 60 disposed within the access groove 357 is fixed. In this embodiment, the position of the restraining member 60 is fixed by restraining movement of the restraining member 60 disposed within the access groove 357 in the axial direction Da and the circumferential direction Dc. Specifically, as shown in FIG. 2 , a punching process is performed on the disk surface 23d to form a punching portion 100P. The punching portion 100P is recessed from the disk surface 23d when viewed from the axial direction Da so as to deform the outer peripheral surface 23f facing the access groove 357. The punching portion 100P plastically deforms the outer peripheral surface 23f facing the access groove 357 so that it protrudes slightly outward in the radial direction Dr when viewed from the axial direction Da. As a result, the protruding portion of the punching portion 100P abuts against the restraining member 60. This restrains movement of the restraining member 60 in the axial direction Da. In this manner, the attachment of the first rotor blade 32A and the second rotor blade 32B to the disk portion 23 is completed.

[0050] Thereafter, the rotor blade 32 attached to the disk portion 23 as the first rotor blade 32A is treated as a new second rotor blade 32B, and step S12 and subsequent steps for inserting the above-described key 50A into the circumferential groove 25 are performed. In step S12, the new key 50A is inserted into the circumferential groove 25 for the second side surface 35t of the new second rotor blade 32B. Thereafter, steps S13 to S16 are sequentially performed as described above. In this manner, by sequentially attaching the first rotor blade 32A adjacent to the second rotor blade 32B in the circumferential direction Dc, all of the rotor blades 32 of one rotor blade row 31 are attached to the disk portion 23. By performing this process at positions of the other rotor blade rows 31, the rotor 20 of the steam turbine 1 is manufactured.

[0051] (Action and effect) In the fixing method S10 for the rotor 20 of the steam turbine 1, the steam turbine 1, and the blade 32 configured as described above, the blade 32 (second blade 32B) is fixed by the key 50A disposed in the circumferential groove 25 and the key receiving groove 355 in a state in which the blade 32 cannot move in the axial direction Da relative to the disk portion 23. This key 50A is moved to one side Dc1 in the circumferential direction Dc within the circumferential groove 25 with respect to the second blade 32B, whose blade root 36 is inserted in the blade embedding groove 28, and is thereby inserted into the key receiving groove 355 as well. As a result, the key 50A is disposed in the circumferential groove 25 and the key receiving groove 355 of the second blade 32B from a position offset with respect to the second blade 32B. As a result, the second blade 32B cannot move in the axial direction Da relative to the key 50A disposed in the circumferential groove 25. Therefore, simply by moving the key 50A within the circumferential groove 25 and arranging it within the circumferential groove 25 and the key receiving groove 355, the second rotor blade 32B can be reliably fixed in an immovable state relative to the disk portion 23. In this way, the rotor blade 32 can be easily and reliably restrained by the key 50A.

[0052] Furthermore, the circumferential groove 25 extends in the circumferential direction Dc from a position overlapping with the platform 35 of the second rotor blade 32B to a position overlapping with the platform 35 of the first rotor blade 32A. This allows the key 50A to be inserted into the circumferential groove 25 at a position where the first rotor blade 32A is positioned offset in the circumferential direction Dc relative to the second rotor blade 32B, even after the blade root 36 of the second rotor blade 32B is embedded in the blade embedding groove 28. Thereafter, by simply moving the key 50A to one side Dc1 in the circumferential direction Dc within the circumferential groove 25, the key 50A can be inserted into the key receiving groove 355 of the second rotor blade 32B without interfering with the second rotor blade 32B. Therefore, the second rotor blade 32B can be fixed to the disk portion 23 by the key 50A regardless of the order in which the second rotor blade 32B and the key 50A are attached.

[0053] A restraining member 60 is disposed in the access groove 357 to restrain the movement of the key 50A approaching the access groove side surface 357s in the circumferential direction Dc. By inserting the restraining member 60 between the key 50A and the access groove side surface 357s, the key 50A disposed in the circumferential groove 25 and the key accommodating groove 355 is restrained from moving toward the other side Dc2 in the circumferential direction Dc. This prevents the key 50A from slipping out of the circumferential groove 25 and the key accommodating groove 355. This prevents the key 50A from coming out of the circumferential groove 25, stably maintaining a state in which the movement of the second rotor blade 32B in the axial direction Da is restrained. The restraining member 60 is disposed in the access groove 357 between the key 50A and the access groove side surface 357s. Therefore, even when the multiple rotor blades 32 (first rotor blade 32A and second rotor blade 32B) and key 50A are attached to the disk portion 23, the restraining member 60 can be accessed through the access groove 357. In other words, even when the first rotor blade 32A and the second rotor blade 32B are fixed to the disk portion 23, the restraining member 60 can be attached and detached. Therefore, by attaching and detaching the restraining member 60 from the access groove 357, the fixation of the second rotor blade 32B by the key 50A can be easily released.

[0054] Furthermore, the punching portion 100P deforms the outer peripheral surface 23f, changing the shape of the circumferential groove 25, thereby restricting movement of the restraint member 60 in the axial direction Da and the circumferential direction Dc. This prevents the restraint member 60 from spontaneously falling out of the access groove 357 due to vibrations during operation of the steam turbine 1, etc. Therefore, the state in which the key 50A restricts movement of the second rotor blade 32B in the axial direction Da can be more stably maintained.

[0055] Furthermore, the end 51e of the key 50A protrudes toward the other side Dc2 in the circumferential direction Dc relative to the second rotor blade 32B. Therefore, when the blade root 36 of the first rotor blade 32A is moved toward the downstream side Dad in the axial direction Da, the access groove end surface 357d of the first rotor blade 32A abuts against the end 51e. This restricts movement of the first rotor blade 32A toward the downstream side Dad in the axial direction Da during the installation process of the first rotor blade 32A. Therefore, when installing the first rotor blade 32A, it is possible to prevent the first rotor blade 32A from moving too far toward the downstream side Da in the axial direction Da relative to the disk portion 23. This makes it possible to easily and accurately position the first rotor blade 32A in the axial direction Da relative to the disk portion 23.

[0056] Furthermore, by using the key 50A to fix the rotor blade 32 to the disk portion 23, it becomes possible to easily and reliably restrain the rotor blade 32 with the key 50A when assembling the steam turbine 1 or performing maintenance on the rotor 20. Furthermore, the rotor blade 32 can be easily removed from the disk portion 23 simply by moving the key 50A.

[0057] (Modification of the first embodiment) The structure of the restraining member 60 is not limited to that of the first embodiment. The restraining member 60 may have any structure as long as it can restrain the movement of the key 50A. As a modified example of the restraining member 60, for example, the following configurations are also possible.

[0058] As shown in FIG. 10 , the restraining member 60B is inserted between the key 50A and the access groove side surface 357s, similar to the restraining member 60 in the first embodiment. When viewed in the radial direction Dr, the restraining member 60B protrudes from the access groove 357 downstream in the axial direction Dad beyond the key 50A. The restraining member 60B has an insertion portion 601 and a protrusion (rotation restricting portion) 602. The insertion portion 601 is disposed between the key 50A and the access groove side surface 357s in the axial direction Da. The protrusion 602 restricts rotation of the insertion portion 601 within the access groove 357 when viewed in the radial direction Dr. Specifically, the protrusion 602 is disposed closer to the first end face 35d in the axial direction Da than the insertion portion 601. The protrusion 602 is formed integrally with the insertion portion 601. When viewed in the radial direction Dr, the protrusion 602 protrudes to one side Dc1 in the circumferential direction Dc at a position offset toward the downstream side Dad in the axial direction Da relative to the key 50A. The protrusion 602 protrudes in the circumferential direction Dc so as to overlap with the key 50A. The protrusion 602 is positioned within the access groove 357 at a position facing the key end face 505 of the key 50A. The key end face 505 is a flat surface of the key 50A that faces the downstream side Dad in the axial direction Da.

[0059] In the modified restraining member 60B, the protrusion 602 abuts against the key end face 505. Therefore, when viewed from the radial direction Dr within the access groove 357, the restraining member 60B is prevented from rotating about an imaginary axis extending in the radial direction Dr. This makes it possible to more stably maintain the state in which the insertion portion 601 restrains the key 50A from moving toward the other side Dc2 in the circumferential direction Dc.

[0060] Second Embodiment Next, a second embodiment of the steam turbine rotor, the steam turbine, and the method for fixing the rotor blades according to the present disclosure will be described. In the second embodiment described below, components common to the first embodiment will be denoted by the same reference numerals in the drawings, and their description will be omitted. The second embodiment differs from the first embodiment in that it does not include a restraining member 60 and in that it uses a key 50B.

[0061] 11 and 12, in the rotor 20B of the steam turbine 1 of this embodiment, each moving blade 32 is constrained by a key 50B from moving in the axial direction Da relative to the disk portion 23. The key 50B is disposed inside the circumferential groove 25 and the key accommodating groove 355. As shown in FIGS. 11 to 13, the key 50B of the second embodiment integrally includes a key main body portion 53 and a key extension portion 54.

[0062] The key body 53 is inserted into the key accommodating groove 355, the circumferential groove 25, and the access groove 357. The key body 53 is formed, for example, in the shape of a rectangular parallelepiped block. The key body 53 is shaped to be movable in the circumferential groove 25 in the circumferential direction Dc. The key body 53 is movable between the key accommodating groove 355 and the access groove 357 by moving in the circumferential groove 25 in the circumferential direction Dc. The length of the key body 53 in the axial direction Da is the same as that of the circumferential groove 25 and the key accommodating groove 355 so as to be in sliding contact with the circumferential groove 25 and the key accommodating groove 355. A region of the key body 53, including an end 53e on the other side Dc2 in the circumferential direction Dc, protrudes from the second side surface 35t to the other side Dc2 in the circumferential direction Dc when the key body 53 is accommodated in the circumferential groove 25 and the key accommodating groove 355. Even when the key body 53 is housed in the circumferential groove 25 and the key housing groove 355, a portion of the key body 53 including the end 53e is disposed within the access groove 357.

[0063] The key extension 54 extends from the end 53e of the key body 53 to the downstream side Dad in the axial direction Da. When viewed from the axial direction Da, with the key body 53 accommodated in the circumferential groove 25 and the key accommodating groove 355, the key extension 54 is disposed on the outer side Dro in the radial direction Dr with respect to the circumferential groove 25. When viewed from the axial direction Da, the key extension 54 is disposed within the access groove 357. An end 54d of the key extension 54 on the downstream side Da in the axial direction Da extends to the same position as the disk surface 23d in the axial direction Da. A punching portion 100Q is formed on the disk surface 23d, on the inner side Dri in the radial direction Dr with respect to the end 54d of the key extension 54. By forming the punching portion 100Q, the inner portion Dri of the end portion 54d in the radial direction Dr on the disk surface 23d is plastically deformed, and movement of the key extension portion 54 in the axial direction Da and the circumferential direction Dc is restricted.

[0064] In addition, the punching portion 100Q of the second embodiment does not necessarily have to restrict movement of the key 50B in the axial direction Da, as long as it is formed in a position that allows it to restrict movement of the key 50B in the circumferential direction Dc.

[0065] (Procedure for fixing rotor blades) Next, a blade fixing method S20 according to a second embodiment will be described, in which the blade 32 described above is fixed to the disk portion 23 by the key 50B. Unlike the blade fixing method S10 according to the first embodiment, the blade fixing method S20 according to the second embodiment does not include step S15 of arranging the restraining member 60 and step S16 of fixing the restraining member 60, but includes step S24 of fixing the key 50B. Specifically, as shown in FIG. 14 , the blade fixing method S20 according to the second embodiment includes step S11 of attaching the second blade 32B, step S22 of inserting the key 50B into the circumferential groove 25, step S23 of inserting the key 50B into the key receiving groove 355, step S24 of fixing the key 50B, and step S15 of attaching the first blade 32A.

[0066] Step S11 of attaching the second rotor blade 32B is performed in the same manner as in the first embodiment. Thereafter, in step S22 of inserting the key 50B into the circumferential groove 25, the key body 53 of the key 50B is inserted into the circumferential groove 25, as shown in FIG. 15 . In step S22 of this embodiment, one key 50B is attached to the disk portion 23 to which the second rotor blade 32B is attached. When viewed from the radial direction Dr, the key body 53 is inserted into the circumferential groove 25 at a position that is shifted in the circumferential direction Dc from the position where the second rotor blade 32B is disposed. The key body 53 is moved from the outer side Dro toward the inner side Dri in the radial direction Dr, so that the region of the key body 53 on the inner side Dri in the radial direction Dr is disposed in the circumferential groove 25.

[0067] In step S23 of inserting the key 50B into the key groove 355, the key 50B is moved in the circumferential direction Dc within the circumferential groove 25, and the key body 53 is inserted into the key groove 355. The key body 53 is inserted into the key groove 355, which opens at the second side surface 35t of the second rotor blade 32B, from a position offset in the circumferential direction Dc from the position where the second rotor blade 32B is disposed. As shown in FIG. 12 , when the key body 53 is housed in the key groove 355, the end 53e of the key body 53 is positioned at a position protruding from the second side surface 35t toward the other side Dc2 in the circumferential direction Dc. Furthermore, the key extension 54 extending from the end 53e is positioned within the access groove 357. In this state, the region of the key body 53 on the inner side Dri in the radial direction Dr is accommodated in the circumferential groove 25, and the region of the key body 53 on the outer side Dro in the radial direction Dr is inserted into the key accommodating groove 355. As a result, the second rotor blade 32B is restricted by the key body 53 from moving in the axial direction Da relative to the disk portion 23.

[0068] Thereafter, step S14 of attaching the first rotor blade 32A is performed in the same manner as in the first embodiment. As the blade root 36 of the first rotor blade 32A is moved toward the downstream side Dad in the axial direction Da, the access groove end surface 357d of the access groove 357 of the first rotor blade 32A abuts against the end 53e. This restricts movement of the first rotor blade 32A toward the downstream side Dad in the axial direction Da during the attachment process. Furthermore, with the key body 53 housed in the key receiving groove 355, the key extension 54 extends from the end 53e of the key body 53 within the access groove 357 toward the downstream side Dad in the axial direction Da.

[0069] In step S25 of fixing the key 50B, the key 50B is fixed after the key body 53 is accommodated in the key receiving groove 355. In this embodiment, the position of the key 50B is fixed by restricting the movement of the key extension 54 arranged in the access groove 357 in the axial direction Da and the circumferential direction Dc. Specifically, a punching process is performed on the disk surface 23d at the inner side Dri of the key extension 54 in the radial direction Dr. This forms a punching portion 100Q. When viewed from the axial direction Da, the punching portion 100Q is recessed from the disk surface 23d so as to deform the outer peripheral surface 23f facing the access groove 357. The punching portion 100Q plastically deforms the outer peripheral surface 23f close to the key extension 54 so that it bulges outward in the radial direction Dr. As a result, the protruding portion of the punching portion 100P abuts against the key extension 54. This restricts movement of the key 50B in the axial direction Da and the circumferential direction Dc. As a result, the attachment of the first rotor blade 32A and the second rotor blade 32B to the disk portion 23 is completed.

[0070] Thereafter, similarly to the first embodiment, each step is repeatedly performed to attach all the rotor blades 32 of one rotor blade row 31 to the disk portion 23.

[0071] Note that step S23 of inserting the key 50B into the key receiving groove 355 may be performed after step S14 of attaching the first rotor blade 32A. In that case, the key body 53 is inserted into the key receiving groove 355 by moving the key extension portion 54.

[0072] (Action and effect) In the second embodiment, the second rotor blade 32B is fixed so as to be immovable in the axial direction Da relative to the disk portion 23 by the key body 53 arranged in the circumferential groove 25 and the key receiving groove 355. This key body 53 is moved to one side Dc1 in the circumferential direction Dc within the circumferential groove 25 with respect to the second rotor blade 32B, whose blade root 36 is inserted into the blade embedding groove 28, and is thereby inserted into the key receiving groove 355 as well. This makes it possible to easily and reliably restrain the rotor blade 32 by the key 50B.

[0073] Furthermore, the punching portion 100Q deforms the outer peripheral surface 23f, changing the shape of the circumferential groove 25, thereby restricting movement of the key extension portion 54 extending from the key main body portion 53 in the axial direction Da and the circumferential direction Dc. Therefore, movement of the key main body portion 53 in the axial direction Da and the circumferential direction Dc is also restricted. This prevents the key main body portion 53 from moving out of the key receiving groove 355 to the other side Dc2 in the circumferential direction Dc due to vibrations during operation of the steam turbine 1, etc. This makes it possible to more stably maintain the state in which movement of the second rotor blade 32B in the axial direction Da is restricted by the key 50B, without using a separate member such as the restricting member 60 other than the key 50B.

[0074] Furthermore, the key extension 54 extends in the axial direction Da from the key body 53 within the access groove 357. Therefore, the key body 53 within the circumferential groove 25 can be easily moved in the circumferential direction Dc via the key extension 54 within the access groove 357. In other words, even if the first rotor blade 32A and the second rotor blade 32B are fixed to the disk portion 23, the key body 53 can be inserted into or removed from the key accommodating groove 355. Therefore, by moving the key extension 54, the fixation of the second rotor blade 32B by the key 50B can be easily released.

[0075] Third Embodiment Next, a third embodiment of the steam turbine rotor, the steam turbine, and the method for fixing the rotor blades according to the present disclosure will be described. In the third embodiment described below, components common to the first and second embodiments will be denoted by the same reference numerals in the drawings, and description thereof will be omitted. The third embodiment differs from the first embodiment in that it does not have a restraining member 60 and in that it uses a key 50C.

[0076] 16 to 18, in the rotor 20C of the steam turbine 1 of this embodiment, each moving blade 32 is constrained by a key 50C from moving in the axial direction Da relative to the disk portion 23. The key 50C of the third embodiment integrally includes a key main portion 57 and a key stopper portion 58.

[0077] The key main portion 57 is inserted into the circumferential groove 25 and the key receiving groove 355. The key main portion 57 is formed, for example, in a semicircular shape when viewed in the axial direction Da. The key main portion 57 is rotatable within the circumferential groove 25 and the key receiving groove 355 about a central axis 57c extending in the axial direction Da. The key main portion 57 is movable between the key receiving groove 355 and the access groove 357 by rotating within the circumferential groove 25. The length of the key main portion 57 in the axial direction Da is the same as that of the circumferential groove 25 and the key receiving groove 355 so that the key main portion 57 slides against the circumferential groove 25 and the key receiving groove 355. Preferably, the outer periphery of the key main portion 57 is chamfered or curved. The key main portion 57 may also be circular when viewed in the axial direction Da.

[0078] The key stopper portion 58 restricts movement of the key main portion 57 toward the access groove side surface 357s in the circumferential direction Dc. The key stopper portion 58 extends from the key main portion 57 toward the downstream side Dad in the axial direction Da. The key stopper portion 58 is formed, for example, in a columnar shape having a cross section of a quarter circle (quadrant) when viewed in the axial direction Da. The key stopper portion 58 is formed integrally with the key main portion 57 so as to be attached to a flat portion that forms the diameter of the semicircular plate-shaped key main portion 57 when viewed in the axial direction Da.

[0079] An axial groove 29 for accommodating the key stopper portion 58 is formed in the disk portion 23. The axial groove 29 is recessed from the outer peripheral surface 23f toward the inner side Dri in the radial direction Dr and extends in the axial direction Da. The axial groove 29 is formed to open at the disk surface 23d. The axial groove 29 communicates with the circumferential groove 25 in the axial direction Da. The axial groove 29 is formed at a position that allows communication with the access groove 357 in the radial direction Dr.

[0080] The key stopper portion 58 is disposed in the axial groove 29 with the key main portion 57 housed in the circumferential groove 25 and the key accommodating groove 355. With the key main portion 57 housed in the circumferential groove 25 and the key accommodating groove 355, an end portion 58d on the downstream side Dad in the axial direction Da of the key stopper portion 58 is disposed at the same position in the axial direction Da as the disk surface 23d.

[0081] In the third embodiment, it is not essential to form a punching portion that restricts movement of the key 50C on the disk surface 23d. If a punching portion is to be formed, it may be formed on the disk surface 23d at a position adjacent to the end 58d of the key stopper portion 58 in the circumferential direction Dc.

[0082] (Procedure for fixing rotor blades) Next, a blade fixing method S30 according to a third embodiment will be described, in which the blade 32 described above is fixed to the disk portion 23 by the key 50C. The blade fixing method S30 according to the third embodiment differs from the second embodiment in the arrangement and fixing method of the key 50C. As shown in Fig. 19, the blade fixing method S30 according to the embodiment of the present disclosure includes a step S11 of attaching the second blade 32B, a step S32 of inserting the key 50C into the circumferential groove 25, a step S33 of inserting the key 50C into the key receiving groove 355, and a step S14 of attaching the first blade 32A.

[0083] Step S11 of attaching the second rotor blade 32B is performed in the same manner as in the first embodiment. Subsequently, in step S32 of inserting the key 50C into the circumferential groove 25, the key main portion 57 of the key 50C is inserted into the circumferential groove 25, as shown in FIGS. 20 and 21 . In step S32 of this embodiment, one key 50C is attached to the disk portion 23 to which the second rotor blade 32B is attached. When viewed from the radial direction Dr, the key main portion 57 is inserted into the circumferential groove 25 at a position shifted in the circumferential direction Dc from the position where the second rotor blade 32B is disposed. At this time, the semicircular key main portion 57, as viewed from the axial direction Da, is positioned so as to fit within the circumferential groove 25. Meanwhile, the key stopper portion 58 is positioned on the outer side Dro in the radial direction Dr of the outer circumferential surface 23f of the disk portion 23. In other words, when viewed from the axial direction Da, the key stopper portion 58 is positioned in a state of protruding from the outer circumferential surface 23f of the disk portion 23.

[0084] In step S33 of inserting the key 50C into the key groove 355, the key 50C is moved in the circumferential direction Dc within the circumferential groove 25, and the key main portion 57 is inserted into the key groove 355. The key main portion 57 is moved from a position offset in the circumferential direction Dc from the position where the second rotor blade 32B is disposed to the position where the second rotor blade 32B is disposed. Thereafter, as shown in FIG. 22 , the key stopper portion 58 is rotated 90° about the central axis 57c. This causes the key main portion 57 to also rotate 90°, changing the orientation of the key main portion 57 so that it is longer in the radial direction Dr. In other words, when viewed from the axial direction Da, the orientation of the flat portion forming the diameter of the key main portion 57 changes from a state in which it faces the radial direction Dr to a state in which it faces the circumferential direction Dc. As a result, a portion of the key main portion 57 is inserted into the key groove 355. As a result, the key main portion 57 is inserted into the key groove 355 and the circumferential groove 25 of the second rotor blade 32B. As a result, the key main portion 57 restricts movement of the second rotor blade 32B in the axial direction Da relative to the disk portion 23. Furthermore, with the key main portion 57 inserted into the key groove 355 and the circumferential groove 25, the key stopper portion 58 enters the axial groove 29. As a result, the key stopper portion 58 is unable to move in the circumferential direction Dc within the axial groove 29. Therefore, movement of the key main portion 57 approaching the access groove side surface 357s in the circumferential direction Dc is restricted. This restricts movement of the key 50C in the circumferential direction Dc. As a result, the attachment of the first rotor blade 32A and the second rotor blade 32B to the disk portion 23 is completed. Thereafter, as in the first embodiment, each process is repeated until all of the rotor blades 32 of one rotor blade row 31 are attached to the disk portion 23.

[0085] (Action and effect) In the third embodiment, the second rotor blade 32B is fixed immovably in the axial direction Da relative to the disk portion 23 by the key main portion 57 arranged in the circumferential groove 25 and the key receiving groove 355. This key main portion 57 is inserted into the key receiving groove 355 by rotating within the circumferential groove 25 for the second rotor blade 32B whose blade root 36 is inserted into the blade embedding groove 28. This makes it possible to easily and reliably restrain the rotor blade 32 by the key 50C.

[0086] Furthermore, as the key main portion 57 rotates and is inserted into the key groove 355, the key stopper portion 58 is inserted into the axial groove 29. The key stopper portion 58 is unable to move in the circumferential direction Dc within the axial groove 29. Therefore, when the key stopper portion 58 is housed in the axial groove 29, movement of the key 50C in the circumferential direction Dc is constrained. In other words, movement of the key 50C in the circumferential direction Dc can be constrained without using a structure that causes plastic deformation, such as a punching portion. This prevents the key main portion 57 from moving out of the key groove 355 to the other side Dc2 in the circumferential direction Dc due to vibrations during operation of the steam turbine 1, etc. This makes it possible to stably and more stably maintain the state in which the movement of the second rotor blade 32B in the axial direction Da is constrained by the key 50C.

[0087] (Modifications of other embodiments) In the above embodiment and its modified example, the procedure of the method for fixing the rotor blade has been described, but the procedure can be changed as appropriate.

[0088] For example, in the above embodiment, the second rotor blade 32B is constrained by the keys 50A-50C, and then the first rotor blade 32A is installed on the other side of the second rotor blade 32B in the circumferential direction Dc. However, the assembly order is not limited to this. For example, the keys 50A-50C may be pre-installed in the circumferential groove 25 on the disk portion 23 before the second rotor blade 32B. Also, for example, after all the keys 50A-50C are installed on the disk portion 23, all the rotor blades 32 may be attached over the entire circumference in the circumferential direction Dc. In this case, the keys 50A-50C may be moved and the constraining members 60 and 60B may be installed through the access grooves 357 formed in the installed rotor blades 32. In this case, a jig may be used that is inserted into the access grooves 357 to support the movement of the keys 50A-50C.

[0089] Furthermore, the shapes of the keys 50A-50C and the restraining members 60, 60B are not limited to those in the above embodiment. The shapes of the keys 50A-50C may be any shape that can restrict movement of the rotor blade 32 relative to the disk portion 23. In this case, the shapes of the circumferential groove 25 and the key accommodating groove 355 are changed as appropriate to correspond to the shapes of the keys 50A-50C. The restraining members 60, 60B may be any shape that can restrict movement of the key 50A. In this case, the shape of the access groove 357 is changed as appropriate to correspond to the shapes of the restraining members 60, 60B.

[0090] <Additional Notes> The method S10 for fixing the rotors 20 to 20C of the steam turbine 1, the steam turbine 1, and the rotor blades 32 described in each embodiment can be understood, for example, as follows.

[0091] (1) A rotor 20 to 20C of a steam turbine 1 according to a first aspect includes an axial core portion 22 formed in a cylindrical shape centered on an axis Ar, a disk portion 23 extending from the axial core portion 22 to an outer side Dro in a radial direction Dr based on the axis Ar, a plurality of moving blades 32 attached to the disk portion 23, and keys 50A to 50C that restrict movement of the moving blades 32 relative to the disk portion 23 in an axial direction Da in which the axis Ar extends. The disk portion 23 is recessed from an outer peripheral surface 23f to an inner side Dri in the radial direction Dr. and a plurality of blade embedded grooves 28 extending in the axial direction Da and spaced apart in a circumferential direction Dc about the axis Ar, and a circumferential groove 25 recessed from the outer peripheral surface 23f toward the inner side Dri in the radial direction Dr and extending in the circumferential direction Dc, and the rotor blade 32 has a blade root 36 embedded in the blade embedded groove 28, a platform 35 disposed on the outer side Dro in the radial direction Dr with respect to the disk portion 23 and protruding on both sides in the circumferential direction Dc from the platform 35, The plurality of rotor blades 32 include a first rotor blade 32A and a second rotor blade 32B adjacent to the first rotor blade 32A on one side Dc1 of the circumferential direction Dc, and the platform 35 of the first rotor blade 32A has, in the circumferential direction Dc, a first side surface 35s facing the platform 35 of the second rotor blade 32B, a first end surface 35d facing the axial direction Da, and a corner 35c formed by the first side surface 35s and the first end surface 35d that opens in the axial direction Da and the circumferential direction Dc. The platform 35 of the second rotor blade 32B has a second side surface 35t facing the first side surface 35s in the circumferential direction Dc, and a key accommodating groove 355 recessed from the second side surface 35t in the circumferential direction Dc, communicating with the circumferential groove 25 in the radial direction Dr and communicating with the access groove 357 in the circumferential direction Dc, and the keys 50A to 50C are disposed in the circumferential groove 25 and the key accommodating groove 355.

[0092] In the rotors 20 to 20C of this steam turbine 1, the keys 50A to 50C arranged in the circumferential grooves 25 and the key grooves 355 fix the rotors 20 to 20C immovably in the axial direction Da relative to the disk portion 23. The keys 50A to 50C are moved in the circumferential direction Dc within the circumferential grooves 25 relative to the second rotor blade 32B, whose blade root 36 is inserted in the blade embedding groove 28, and are thereby inserted into the key grooves 355. As a result, the second rotor blade 32B cannot move in the axial direction Da relative to the keys 50A to 50C accommodated in the circumferential grooves 25. Therefore, simply by moving the keys 50A to 50C within the circumferential grooves 25 and arranging them in the circumferential grooves 25 and the key grooves 355, the second rotor blade 32B can be reliably fixed immovably relative to the disk portion 23. In this way, the rotor blade 32 can be easily and reliably restrained by the keys 50A.

[0093] (2) The rotor 20 to 20C of the steam turbine 1 according to the second aspect is the rotor 20 to 20C of the steam turbine 1 of (1), and the circumferential groove 25, when viewed from the radial direction Dr, extends in the circumferential direction Dc from a position overlapping with the platform 35 of the second rotor blade 32B to a position overlapping with the platform 35 of the first rotor blade 32A, and is connected to the access groove 357 in the radial direction Dr.

[0094] As a result, even after the blade root 36 of the second rotor blade 32B has been embedded in the blade embedding groove 28, the key 50A can be inserted into the circumferential groove 25 at a position where the first rotor blade 32A is positioned, offset in the circumferential direction Dc with respect to the second rotor blade 32B. Thereafter, by simply moving the key 50A in the circumferential groove 25 in the circumferential direction Dc, it can be inserted into the key receiving groove 355 of the second rotor blade 32B without interfering with the second rotor blade 32B. Therefore, the second rotor blade 32B can be fixed to the disk portion 23 by the key 50A, regardless of the order in which the second rotor blade 32B and the key 50A are attached.

[0095] (3) The rotor 20 of the steam turbine 1 according to the third aspect is the rotor 20 of the steam turbine 1 of (1) or (2), wherein the access groove 357 has an access groove side surface 357s facing the second side surface 35t in the circumferential direction Dc, and further includes a restraining member 60 arranged within the access groove 357 between the key 50A and the access groove side surface 357s in the circumferential direction Dc, and restraining the movement of the key 50A approaching the access groove side surface 357s in the circumferential direction Dc.

[0096] As a result, by inserting the restraining member 60 between the key 50A and the access groove side surface 357s, the key 50A disposed in the circumferential groove 25 and the key accommodating groove 355 is restrained from moving in the circumferential direction Dc. Therefore, the key 50A can be prevented from slipping out of the circumferential groove 25 and the key accommodating groove 355. This prevents the key 50A from coming out of the circumferential groove 25, stably maintaining a state in which the movement of the second rotor blade 32B in the axial direction Da is restrained. Furthermore, the restraining member 60 is disposed in the access groove 357 between the key 50A and the access groove side surface 357s. Therefore, even when multiple rotor blades 32 (the first rotor blade 32A and the second rotor blade 32B) and the key 50A are attached to the disk portion 23, the restraining member 60 can be accessed via the access groove 357. That is, the restraining member 60 can be attached and detached even when the first rotor blade 32A and the second rotor blade 32B are fixed to the disk portion 23. Therefore, by attaching and detaching the restraining member 60 from the access groove 357, the fixation of the second rotor blade 32B by the key 50A can be easily released.

[0097] (4) The rotor 20 of the steam turbine 1 according to the fourth aspect is the rotor 20 of the steam turbine 1 of (3), wherein the restraining member 60B comprises an insertion portion 601 arranged between the key 50A and the access groove side surface 357s in the axial direction Da, and a rotation regulating portion 602 formed integrally with the insertion portion 601 at a position close to the first end face 35d in the axial direction Da relative to the insertion portion 601, and regulating the rotation of the insertion portion 601 when viewed from the radial direction Dr within the access groove 357.

[0098] This prevents the restraint member 60B from rotating about an imaginary axis extending in the radial direction Dr when viewed from the radial direction Dr within the access groove 357. This makes it possible to more stably maintain the state in which the insertion portion 601 restrains the key 50A from moving to the other side Dc2 in the circumferential direction Dc.

[0099] (5) The rotor 20B of the steam turbine 1 according to the fifth aspect is the rotor 20B of the steam turbine 1 of (3) or (4), wherein the disk portion 23 has a punching portion 100P on a disk surface 23d facing the axial direction Da so as to be perpendicular to the outer peripheral surface 23f, the punching portion 100P being recessed from the disk surface 23d so as to deform the outer peripheral surface 23f facing the access groove 357 when viewed from the axial direction Da, and the movement of the restraining member 60 in the circumferential direction Dc is restrained by the punching portion 100P.

[0100] As a result, the punching portion 100P deforms the outer circumferential surface 23f, changing the shape of the circumferential groove 25, thereby restricting the movement of the restraint member 60. This prevents the restraint member 60 from spontaneously falling off the access groove 357 due to vibrations during operation of the steam turbine 1, etc. Therefore, the state in which the key 50A restricts the movement of the second rotor blade 32B in the axial direction Da can be more stably maintained.

[0101] (6) A rotor 20B of a steam turbine 1 according to a sixth aspect is the rotor 20B of the steam turbine 1 of (1) or (2), wherein the access groove 357 has an access groove side surface 357s facing the second side surface 35t in the circumferential direction Dc, and the key 50B includes the circumferential groove 25, the key accommodating groove 355, and a key body portion 53 inserted into the access groove 357, and a key extension portion extending from the key body portion 53 in the axial direction Da within the access groove 357. The disk portion 23 has, integrally with the key extension portion 54, a punching portion 100Q recessed from the disk surface 23d that faces the axial direction Da so as to deform the outer peripheral surface 23f facing the access groove 357 when viewed from the axial direction Da, on the disk surface 23d that faces the axial direction Da so as to deform the outer peripheral surface 23f that faces the access groove 357s, and the movement of the key extension portion 54 toward the access groove side surface 357s in the circumferential direction Dc is restricted by the punching portion 100Q.

[0102] As a result, the punching portion 100Q deforms the outer peripheral surface 23f, changing the shape of the circumferential groove 25, thereby restricting the movement of the key extension portion 54 extending from the key main body portion 53. Therefore, the movement of the key main body portion 53 is also restricted. This prevents the key main body portion 53 from moving out of the key receiving groove 355 in the circumferential direction Dc due to vibrations during operation of the steam turbine 1, etc. This makes it possible to more stably maintain the state in which the movement of the second rotor blade 32B in the axial direction Da is restricted by the key 50B without using any additional member other than the key 50B. Furthermore, the key extension portion 54 extends from the key main body portion 53 in the axial direction Da within the access groove 357. Therefore, the key main body 53 within the circumferential groove 25 can be easily moved in the circumferential direction Dc via the key extension portion 54 within the access groove 357. That is, even if the first rotor blade 32A and the second rotor blade 32B are fixed to the disk portion 23, the key body portion 53 can be inserted into or removed from the key accommodating groove 355. Therefore, by moving the key extension portion 54, the fixation of the second rotor blade 32B by the key 50B can be easily released.

[0103] (7) A rotor 20C of a steam turbine 1 according to a seventh aspect is the rotor 20C of the steam turbine 1 of (1) or (2), wherein the access groove 357 has an access groove side surface 357s facing the second side surface 35t in the circumferential direction Dc, the disk portion 23 further has an axial groove 29 recessed from the outer peripheral surface 23f toward an inner side Dri in the radial direction Dr and extending in the axial direction Da, the axial groove 29 communicating with the circumferential groove 25 and the access groove 357, and the key 50C integrally has a key main portion 57 inserted into the circumferential groove 25 and the key accommodating groove 355, and a key stopper portion 58 extending from the key main portion 57 in the axial direction Da, disposed in the axial groove 29, and restricting movement of the key main portion 57 approaching the access groove side surface 357s in the circumferential direction Dc.

[0104] As a result, the key stopper portion 58 is unable to move in the circumferential direction Dc within the axial groove 29. Therefore, when the key stopper portion 58 is housed in the axial groove 29, movement of the key 50C in the circumferential direction Dc is constrained. In other words, movement of the key 50C in the circumferential direction Dc can be constrained without using a structure that causes plastic deformation, such as a punching portion. This prevents the key main portion 57 from moving out of the key receiving groove 355 to the other side Dc2 in the circumferential direction Dc due to vibrations during operation of the steam turbine 1, etc. This makes it possible to stably and more stably maintain a state in which movement of the second rotor blade 32B in the axial direction Da is constrained by the key 50C.

[0105] (8) The steam turbine 1 according to an eighth aspect includes the rotor 20 to 20C of any one of the steam turbines 1 according to (1) to (7).

[0106] As a result, by providing the steam turbine 1 with rollers as described above, it becomes possible to easily and reliably restrain the rotor blades 32 with the keys 50A to 50C when assembling the steam turbine 1, during maintenance of the rotors 20 to 20C, etc.

[0107] (9) A method S10 for fixing a rotor blade 32 according to a ninth aspect is a method S10, S20, S30 for fixing the rotor blade 32 in a rotor 20 to 20C of a steam turbine 1 of any one of (1) to (7), and includes steps S11, S21, S31 for attaching the second rotor blade 32B to the disk portion 23, steps S12, S22, S32 for inserting the keys 50A to 50C into the circumferential groove 25, steps S13, S23, S33 for moving the keys 50A to 50C in the circumferential groove 25 in the circumferential direction Dc and inserting them into the key accommodating groove 355, and steps S14, S25, S35 for attaching the first rotor blade 32A to the disk portion 23.

[0108] As a result, the keys 50A-50C disposed in the circumferential groove 25 and the key groove 355 fix the second rotor blade 32B, whose blade root 36 is inserted in the blade embedding groove 28, in a state where they cannot move in the axial direction Da relative to the disk portion 23. These keys 50A-50C are moved in the circumferential groove 25 in the circumferential direction Dc, and are inserted into the key groove 355 as well. As a result, the second rotor blade 32B cannot move in the axial direction Da relative to the keys 50A-50C disposed in the circumferential groove 25. Therefore, simply by moving the keys 50A-50C in the circumferential groove 25 and disposing them in the circumferential groove 25 and the key groove 355, the second rotor blade 32B can be reliably fixed in a state where it cannot move relative to the disk portion 23. In this way, the rotor blade 32 can be easily and reliably restrained by the key 50A. [Explanation of symbols]

[0109] 1. Steam turbine 10...Casing 11...Nozzle chamber 12...Main flow chamber 13...Exhaust chamber 15...Main steam passage 15w…Blade flow path 20, 20B, 20C...Rotor 21...Rotor shaft 22...Axis core part 23...Disc section 23d...Disc surface 23f…Outer surface 25…Circumferential groove 28...Wing embedding groove 28a...engagement recess 29...Axial groove 31...Rotating blade row 32... Moving blade 32A...First moving blade 32B...Second moving wing 33...Wing body 34...Shroud 35...Platform 35c…corner 35d...first end surface 35f...Inner surface of platform 35g...Platform outer periphery 35s…first side 35t…Second side 36...wing root 36t...Engagement convex part 41...Stator blade row 42...Stationary blade 43...Outer ring 46...Inner ring 50A~50C...Key 51e...end 53...Key body 53e...end 54...Key extension 54d...end 57...Key main part 58...Key stopper part 58d...end 60, 60B...Restraining member 60d...end 601...insertion part 602...Protrusion (rotation restriction part) 100P, 100Q...Punching section 355...Key receiving groove 357...Access groove 357d...Access groove end face 357s...Access groove side 505...Key end face Ar…Axis line Da...Axial direction Dad…downstream Dau…upstream Dc…Circumferential direction Dc1...one side Dc2: other side Dr…Radial direction Dri…inside Dro...outside S...Steam S10, S20, S30...Rotor blade fixing method S11: Step of installing the second rotor blade S12, S22, S32...Steps for inserting the key into the circumferential groove S13, S23, S33...Steps for inserting the key into the key receiving groove S14: Step of installing the first rotor blade S15: A process of placing a restraining member S16: A process of fixing the restraining member S24: Key fixing process

Claims

1. a cylindrical shaft portion formed around an axis line; a disk portion extending radially outward relative to the axial core portion, the disk portion being based on the axis line; a plurality of rotor blades attached to the disk portion; a key that restricts movement of the rotor blade relative to the disk portion in the axial direction along which the axis extends, the disk portion has a plurality of blade-embedded grooves recessed radially inward from an outer peripheral surface, extending in the axial direction, and formed at intervals in a circumferential direction centered on the axis line, and a circumferential groove recessed radially inward from the outer peripheral surface and extending in the circumferential direction, The rotor blade comprises: a blade root embedded in the blade embedding groove; a platform disposed radially outward from the disk portion and projecting on both sides in the circumferential direction from the blade root; an airfoil body extending radially outward from the platform; the plurality of rotor blades include a first rotor blade and a second rotor blade adjacent to the first rotor blade on one side in the circumferential direction, The platform of the first blade includes: a first side surface of the second blade facing the platform in the circumferential direction; a first end surface facing the axial direction; an access groove recessed at a corner formed by the first side surface and the first end surface so as to open in the axial direction and the circumferential direction, and communicating with the circumferential groove; The platform of the second blade includes: a second side surface facing the first side surface in the circumferential direction; a key accommodating groove recessed from the second side surface in the circumferential direction, communicating with the circumferential groove in the radial direction and communicating with the access groove in the circumferential direction; the key is disposed in the circumferential groove and the key receiving groove; the access groove has an access groove side surface facing the second side surface in the circumferential direction; a restraining member disposed in the access groove between the key and a side surface of the access groove in the circumferential direction, the restraining member restraining movement of the key toward the side surface of the access groove in the circumferential direction; the disk portion has a punching portion on a disk surface facing the axial direction so as to be perpendicular to the outer peripheral surface, the punching portion being recessed from the disk surface so as to deform the outer peripheral surface facing the access groove when viewed from the axial direction; The restraining member is a rotor of a steam turbine whose movement in the circumferential direction is restrained by the punching portion.

2. The restraining member is an insert portion disposed between the key and the access groove side surface in the axial direction; 2. The steam turbine rotor according to claim 1, further comprising: a rotation restricting portion formed integrally with the insertion portion at a position near the first end face in the axial direction relative to the insertion portion, and restricting rotation of the insertion portion when viewed from the radial direction within the access groove.

3. A cylindrically shaped shaft core portion centered on an axis; a disk portion extending radially outward relative to the axial core portion, the disk portion being based on the axis line; a plurality of rotor blades attached to the disk portion; a key that restricts movement of the rotor blade relative to the disk portion in the axial direction along which the axis extends, the disk portion has a plurality of blade-embedded grooves recessed radially inward from an outer peripheral surface, extending in the axial direction, and formed at intervals in a circumferential direction centered on the axis line, and a circumferential groove recessed radially inward from the outer peripheral surface and extending in the circumferential direction, The rotor blade comprises: a blade root embedded in the blade embedding groove; a platform disposed radially outward from the disk portion and projecting on both sides in the circumferential direction from the blade root; an airfoil body extending radially outward from the platform; the plurality of rotor blades include a first rotor blade and a second rotor blade adjacent to the first rotor blade on one side in the circumferential direction, The platform of the first blade includes: a first side surface of the second blade facing the platform in the circumferential direction; a first end surface facing the axial direction; an access groove recessed at a corner formed by the first side surface and the first end surface so as to open in the axial direction and the circumferential direction, and communicating with the circumferential groove; The platform of the second blade includes: a second side surface facing the first side surface in the circumferential direction; a key accommodating groove recessed from the second side surface in the circumferential direction, communicating with the circumferential groove in the radial direction and communicating with the access groove in the circumferential direction; the key is disposed in the circumferential groove and the key receiving groove; the access groove has an access groove side surface facing the second side surface in the circumferential direction; The key is a key body inserted into the circumferential groove, the key receiving groove, and the access groove; a key extension portion extending from the key body portion in the axial direction within the access groove, the disk portion has a punching portion on a disk surface facing the axial direction so as to be perpendicular to the outer peripheral surface, the punching portion being recessed from the disk surface so as to deform the outer peripheral surface facing the access groove when viewed from the axial direction; A steam turbine rotor in which the key extension portion is restrained by the punching portion from moving toward the side surface of the access groove in the circumferential direction.

4. A cylindrically shaped shaft core portion centered on an axis; a disk portion extending radially outward relative to the axial core portion, the disk portion being based on the axis line; a plurality of rotor blades attached to the disk portion; a key that restricts movement of the rotor blade relative to the disk portion in the axial direction along which the axis extends, the disk portion has a plurality of blade-embedded grooves recessed radially inward from an outer peripheral surface, extending in the axial direction, and formed at intervals in a circumferential direction centered on the axis line, and a circumferential groove recessed radially inward from the outer peripheral surface and extending in the circumferential direction, The rotor blade comprises: a blade root embedded in the blade embedding groove; a platform disposed radially outward from the disk portion and projecting on both sides in the circumferential direction from the blade root; an airfoil body extending radially outward from the platform; the plurality of rotor blades include a first rotor blade and a second rotor blade adjacent to the first rotor blade on one side in the circumferential direction, The platform of the first blade includes: a first side surface of the second blade facing the platform in the circumferential direction; a first end surface facing the axial direction; an access groove recessed at a corner formed by the first side surface and the first end surface so as to open in the axial direction and the circumferential direction, and communicating with the circumferential groove; The platform of the second blade includes: a second side surface facing the first side surface in the circumferential direction; a key accommodating groove recessed from the second side surface in the circumferential direction, communicating with the circumferential groove in the radial direction and communicating with the access groove in the circumferential direction; the key is disposed in the circumferential groove and the key receiving groove; the access groove has an access groove side surface facing the second side surface in the circumferential direction; the disk portion further includes an axial groove recessed radially inward from the outer circumferential surface, extending in the axial direction, and communicating with the circumferential groove and the access groove; The key is a key main portion inserted into the circumferential groove and the key receiving groove; a key stopper portion extending from the key main portion in the axial direction, disposed in the axial groove, and configured to restrict movement of the key main portion toward a side surface of the access groove in the circumferential direction.

5. 5. The steam turbine rotor according to claim 1, wherein the circumferential groove extends in the circumferential direction so as to straddle a position overlapping with the platform of the second blade and a position overlapping with the platform of the first blade when viewed from the radial direction, and is in communication with the access groove in the radial direction.

6. A steam turbine comprising a rotor according to any one of claims 1 to 5.

7. 6. A method for fixing the rotor blades in a rotor of a steam turbine according to claim 1, comprising: attaching the second blade to the disk portion; inserting the key into the circumferential groove; moving the key in the circumferential groove in the circumferential direction and inserting the key into the key receiving groove; and attaching the first blade to the disk portion. How to fix the rotor blades.

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