Rotor of steam turbine, steam turbine, and method for fixing rotor blade

A rotor of a steam turbine includes a plurality of rotor blades attached to a disk portion and a key configured to restrict movement of each of the plurality of rotor blades in an axial direction. The disk portion includes a blade embedding groove and a circumferential groove. 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 a circumferential direction. A platform of the first rotor blade includes an access groove communicating with the circumferential groove, and a platform of the second rotor blade includes a second side surface facing a first side surface in the circumferential direction and a key accommodating groove communicating with the access groove in the circumferential direction. A key is arranged in the circumferential groove and the key accommodating groove.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a rotor of a steam turbine, a steam turbine, and a method for fixing a rotor blade.

Priority is claimed on Japanese Patent Application No. 2021-205124, filed on Dec. 17, 2021, the content of which is incorporated herein by reference.

Description of Related Art

A steam turbine includes a rotor that rotates about an axis and a casing that covers the rotor. The rotor has a rotor shaft extending in an axial direction about the axis, and a plurality of rotor blade rows fixed to an outer periphery of the rotor shaft and arranged in the axial direction. The steam turbine has a stator vane row fixed to an inner periphery of the casing and arranged upstream side of each row of the plurality of rotor blade rows. The rotor blade row of each row includes a plurality of rotor blades in a circumferential direction of a rotor disk. The rotor blade protrudes radially from an outer peripheral surface of the rotor disk.

The rotor blades are fixed to the rotor disk by inserting blade roots of the rotor blades into a plurality of blade grooves formed on the outer peripheral surface of the rotor disk at intervals in the circumferential direction. The blade groove penetrates the rotor disk in the axial direction. The blade root of the rotor blade is inserted into the blade groove of the rotor disk in the axial direction, and thus, attached to the rotor disk.

When the steam turbine operates, steam sent into the casing flows in the casing from a first side toward a second side in the axial direction. Therefore, a force that presses from the first side to the second side in the axial direction acts on the rotor blade due to a fluid pressure of the steam. It is necessary to prevent the rotor blade from shifting in the axial direction with respect to the blade groove due to the force pressed by this steam.

Meanwhile, for example, Patent Document 1 describes a structure in which a key (fixing member) is used to restrain a rotor blade in the axial direction with respect to a blade groove of a rotor disk. In the structure of Patent Document 1, the key is inserted into the second notch portion formed in the rotor disk through a first notch portion formed to penetrate a platform of the rotor blade. Then, a part of an outer peripheral side of the key is covered with the platform, and the key is plastically deformed so that a thrust force of the rotor blade can be supported.

SUMMARY OF THE INVENTION

However, in the configuration described in Patent Document 1, after the key is inserted into the second notch portion through the first notch portion, the key should be plastically deformed, which is troublesome to attach the key. Further, when the plastic deformation of the key is incomplete, the key may not be sufficiently fixed.

The present disclosure provides a rotor of a steam turbine, a steam turbine, and a method for fixing a rotor blade, which can easily and reliably restrain the rotor blade by a key.

According to an aspect of the present disclosure, there is provided a rotor of a steam turbine, the rotor including: a shaft core portion formed in a columnar shape about an axis; a disk portion extending to an outer side in a radial direction with respect to the shaft core portion, in which the radial direction is based on the axis; a plurality of rotor blades attached to the disk portion; and a key configured to restrict movement of each of the plurality of rotor blades with respect to the disk portion in an axial direction in which the axis extends, in which the disk portion includes a plurality of blade embedding grooves recessed to an inner side in the radial direction from an outer peripheral surface of the disk portion, extending in the axial direction, and formed at intervals in a circumferential direction about the axis, and a circumferential groove recessed to the inner side in the radial direction from the outer peripheral surface and extending in the circumferential direction, each of the plurality of rotor blades includes a blade root embedded in each of the blade embedding grooves, a platform arranged on the outer side in the radial direction with respect to the disk portion and protruding to both sides in the circumferential direction with respect to the blade root, and a blade body extending to the outer side in the radial direction 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 rotor blade includes a first side surface of the second rotor blade facing a platform of the second rotor blade in the circumferential direction, 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 portion formed by the first side surface and the first end surface and communicating with the circumferential groove, the platform of the second rotor blade includes a second side surface facing the first side surface in the circumferential direction, and a key accommodating groove recessed in the circumferential direction from the second side surface, communicating with the circumferential groove in the radial direction, and communicating with the access groove in the circumferential direction, and the key is arranged in the circumferential groove and the key accommodating groove.

According to another aspect of the present disclosure, there is provided a steam turbine including the rotor of a steam turbine described above.

According to still another aspect of the present disclosure, there is provided a method for fixing the rotor blade in the rotor of a steam turbine described above, the method including: a step of attaching the second rotor blade to the disk portion; a step of inserting the key into the circumferential groove; a step of moving the key in the circumferential direction in the circumferential groove and inserting the key into the key accommodating groove; and a step of attaching the first rotor blade to the disk portion.

According to the rotor of a steam turbine, the steam turbine, and the method for fixing a rotor blade of the present disclosure, the rotor blade can be easily and reliably restrained by the key.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments for implementing a rotor of a steam turbine, a steam turbine, and a method for fixing a rotor blade according to the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure is not limited to embodiments.

First Embodiment

(Overall Configuration of Steam Turbine)

As shown inFIG.1, a steam turbine1of the present embodiment includes a rotor20that rotates about an axis Ar and a casing10that rotatably covers the rotor20.

For the convenience of the following description, a direction in which the axis Ar extends is referred to as an axial direction Da. Further, a first side in the axial direction Da is referred to as an upstream side Dau, and a second side in the axial direction Da is referred to as a downstream side Dad. Further, a radial direction in the rotor20with respect to the axis Ar is simply referred to as a radial direction Dr. Further, a side that approaches the axis Ar in the radial direction Dr is referred to as an inner side Dri in the radial direction Dr, and a side in the radial direction Dr that is opposite to the inner side Dri in the radial direction Dr is referred to as an outer side Dro in the radial direction Dr. Further, a circumferential direction of the rotor20about the axis Ar is simply referred to as a circumferential direction Dc.

The rotor20has a rotor shaft21, a rotor blade row31, a key50A (refer toFIG.2), and a restraining member60(refer toFIG.2). The rotor shaft21extends in the axial direction Da about the axis Ar. The rotor shaft21has a shaft core portion22and a plurality of disk portions23. The shaft core portion22is formed in a columnar shape extending in the axial direction Da. The plurality of disk portions23extend from the shaft core portion22to the outer side Dro in the radial direction Dr. The plurality of disk portions23are arranged at intervals in the axial direction Da. The disk portion23is arranged to correspond to each of the plurality of rotor blade rows31.

A nozzle chamber11into which steam S flows in from the outside, a main flow path chamber12in which steam S from the nozzle chamber11flows, and an exhaust chamber13in which steam S flowing from the main flow path chamber12is discharged are formed in the casing10. The nozzle chamber11, the main flow path chamber12, and the exhaust chamber13constitute a steam main flow path15through which high-pressure steam S flows in the casing10.

The high-pressure steam S flows through the steam main flow path15from the upstream side Dau toward the downstream side Dad in the order of the nozzle chamber11, the main flow path chamber12, and the exhaust chamber13while the pressure gradually decreases. That is, a flow direction of the steam S in the present embodiment is a direction from the upstream side Dau toward the downstream side Dad in the axial direction Da. The steam main flow path15is formed in an annular shape around the rotor shaft21. The steam main flow path15extends in the axial direction Da across a plurality of rotor blade rows31and a plurality of stator vane rows41.

As shown inFIGS.1and2, the rotor blade row31is attached to an outer periphery of the disk portion23, which is an outer peripheral portion of the rotor shaft21. A plurality of rotor blade rows31are arranged at intervals in the axial direction Da of the rotor shaft21. In the case of the present embodiment, the number of rotor blade rows31is seven. Therefore, in the case of the present embodiment, the rotor blade rows31of a first stage to a seventh stage are provided.

Each rotor blade row31has a plurality of rotor blades32arranged in the circumferential direction Dc. The plurality of rotor blades32is attached to the disk portion23. Each rotor blade32has a blade root36(refer toFIG.2), a platform35, a shroud34, and a blade body33.

As shown inFIG.2, the blade root36is embedded in a blade embedding groove28, which will be described later, formed in the disk portion23. The blade root36is formed to extend from a platform inner peripheral surface35fof the platform35described later to the inner side Dri in the radial direction Dr. The blade root36has an engaging convex portion36tprotruding toward both sides in the circumferential direction Dc. The engaging convex portions36tare provided at a plurality of locations formed at intervals in the radial direction Dr. The plurality of engaging convex portions36tare formed so that a protrusion dimension in the circumferential direction Dc gradually decreases toward the inner side Dri in the radial direction Dr. As a result, the blade root36has a so-called Christmas tree shape.

The disk portion23is formed with the blade embedding groove28in which the blade root36is embedded. The plurality of blade embedding grooves28are formed at intervals in the circumferential direction Dc. The blade embedding groove28is recessed from the outer peripheral surface of the disk portion23to the inner side Dri in the radial direction Dr. The blade embedding groove28extends in the axial direction Da and is formed to penetrate the disk portion23in the axial direction Da. The blade embedding groove28is formed to correspond to the outer peripheral shape of the blade root36. The blade embedding groove28has an engaging concave portion28ato which the engaging convex portion36tis engaged. The engaging concave portions28aare formed in the blade embedding groove28at a plurality of locations formed at intervals in the radial direction Dr to be recessed toward both sides in the circumferential direction Dc. Further, the disk portion23has an outer peripheral surface23ffacing the outer side Dro in the radial direction Dr and a disk surface23dfacing the downstream side Dad in the axial direction Da. The disk surface23dis a surface orthogonal to the outer peripheral surface23fThe outer peripheral surface23fis a surface of the disk portion23located on the outermost Dro in the radial direction Dr.

The platform35is arranged on the outer side Dro in the radial direction Dr with respect to the disk portion23. The platform35extends in the circumferential direction Dc. The platform35protrudes to both sides of the circumferential direction Dc with respect to the blade root36. The platform35has a rectangular shape that is longer in the axial direction Da than the circumferential direction Dc when viewed from the outer side Dro in the radial direction Dr (refer toFIG.5). The platforms35of the plurality of rotor blades32are arranged in the circumferential direction Dc to form a cylindrical shape about the axis Ar as a whole. The platform35has a platform inner peripheral surface35ffacing the inner side Dri in the radial direction Dr and a platform outer peripheral surface35gfacing the outer side Dro in the radial direction Dr. Further, the platform35has a first side surface35sfacing the circumferential direction Dc and a second side surface35tfacing the side opposite to the first side surface35sin the circumferential direction Dc. Further, the platform35has a first end surface35dfacing the downstream side Dad in the axial direction Da.

The blade body33extends from the platform outer peripheral surface35gto the outer side Dro in the radial direction Dr. That is, the blade body33is arranged on the side opposite to the blade root36with the platform35interposed therebetween in the radial direction Dr. The blade body33is integrally formed with the shroud34. The blade body33is arranged in the steam main flow path15. The blade body33has an airfoil cross section when viewed from the outer side in the radial direction Dr.

The shroud34is connected to an end portion of the outer side Dro in the radial direction Dr with respect to the blade body33. That is, the shroud34is arranged on the side opposite to the platform35with the blade body33interposed therebetween in the radial direction Dr. The shroud34extends in the circumferential direction Dc. The shrouds34of the plurality of rotor blades32have a cylindrical shape as a whole by arranging in the circumferential direction Dc.

A space surrounded by the blade bodies33adjacent to each other in the circumferential direction Dc and the shrouds34and the platform35facing each other in the radial direction Dr is an inter-blade flow path15wthrough which the steam S flows. By arranging the plurality of rotor blades32in the circumferential direction Dc in the casing10, a plurality of inter-blade flow paths15ware formed in the circumferential direction Dc. The plurality of inter-blade flow paths15warranged in the circumferential direction Dc form a part of the steam main flow path15through which the steam S flows.

As shown inFIG.1, the steam turbine1includes a plurality of stator vane rows41fixed to the inner peripheral surface of the casing10and arranged at intervals in the axial direction Da. In the case of the present embodiment, the number of the stator vane rows41is seven, which is the same as the number of the rotor blade rows31. Therefore, in the case of the present embodiment, the stator vane rows41from a first stage to a seventh stage are provided. The plurality of stator vane rows41are arranged adjacent to the upstream side Dau with respect to each rotor blade row31.

The stator vane row41has a plurality of stator vanes42, an outer ring43, and an inner ring46. The plurality of stator vanes42are arranged at intervals in the circumferential direction Dc. The outer ring43is formed in an annular shape and is arranged on the outer side Dro in the radial direction Dr with respect to the plurality of stator vanes42. The inner ring46is formed in an annular shape and is arranged on the inner side Dri in the radial direction Dr with respect to the plurality of stator vanes42. That is, the plurality of stator vanes42are arranged between the outer ring43and the inner ring46. The stator vane42is fixed to the outer ring43and the inner ring46. A space between the outer ring43and the inner ring46and having an annular shape forms a part of the steam main flow path15through which the steam S flows.

In such a steam turbine1, the steam S is sent from the upstream side Dau of the casing10through the nozzle chamber11. This steam S passes through the main flow path chamber12and flows to the exhaust chamber13of the downstream side Dad. As a result, the rotor shaft21rotates around the axis Ar, and the rotor blades32rotate about the axis Ar together with the disk portion23. In this case, in each rotor blade32, the steam S flows in the inter-blade flow path15wbetween the blade bodies33adjacent to each other in the circumferential direction Dc.

(Fixed Structure of Rotor Blade)

As shown inFIGS.2to5, in the steam turbine1, each rotor blade32is restricted from moving in the axial direction Da with respect to the disk portion23by the key50A. The key50A is arranged inside a circumferential groove25formed in the disk portion23and a key accommodating groove355formed in the platform35.

As shown inFIG.3, the circumferential groove25is formed on the outer peripheral surface23fof the disk portion23on the downstream side Dad from an intermediate portion in the axial direction Da. The circumferential groove25is formed in a size that allows the key50A to be inserted. The circumferential groove25is formed to be recessed from the outer peripheral surface23fof the disk portion23to the inner side Dri in the radial direction Dr. The circumferential groove25is formed at a position shifted to the upstream side Dau with respect to the disk surface23din the axial direction Da so as not to be connected to the disk surface23d. As shown inFIGS.4and5, the circumferential groove25extends in the circumferential direction Dc. In the present embodiment, the circumferential groove25is formed between the blade embedding grooves28to connect the adjacent blade embedding grooves28in the circumferential direction Dc. That is, the circumferential groove25is formed to overlap the platform35of the adjacent rotor blades32in the circumferential direction Dc. The circumferential groove25may be formed only in a portion where the key50A is inserted in the circumferential direction Dc.

The key accommodating groove355is formed in the platform35at an end portion of the other side Dc2in the circumferential direction Dc. The key accommodating groove355is formed in a size that allows the key50A to be inserted. The key accommodating groove355is formed at a position overlapping the circumferential groove25in the axial direction Da and the circumferential direction Dc in a state where the blade root36is embedded in the blade embedding groove28. The key accommodating groove355is formed in the platform35to be recessed from the second side surface35tfacing the other side Dc2in the circumferential direction Dc to the one side Dc1in the circumferential direction Dc. The key accommodating groove355is recessed from the platform inner peripheral surface35fto the outer side Dro in the radial direction Dr. The key accommodating groove355is formed at a position distant from the first end surface35din the axial direction Da. That is, the key accommodating groove355is formed to open only at the second side surface35tand the platform inner peripheral surface35fThe key accommodating groove355communicates with the circumferential groove25in the radial direction Dr. The key accommodating groove355communicates with an access groove357described later in the circumferential direction Dc.

The platform35has the access groove357. The access groove357is formed at a position overlapping the key accommodating groove355when viewed from the circumferential direction Dc. The access groove357is formed in a size that allows the key50A to be inserted. The access groove357is formed at an end portion on one side Dc1in the circumferential direction Dc of the platform35. The access groove357is formed in the platform35by being recessed from the first side surface35sfacing the one side Dc1in the circumferential direction Dc to the other side Dc2in the circumferential direction Dc. The access groove357is recessed in the platform35from the first end surface35dfacing the downstream side Dad in the axial direction Da to the upstream side Dau in the axial direction Da. That is, the access groove357is formed to open to the downstream side Dad in the axial direction Da and the one side Dc1in the circumferential direction Dc at a corner portion35cformed by the first side surface35sand the first end surface35d. A depth (length) of the access groove357in the circumferential direction Dc is formed deeper than that of the key accommodating groove355and the key50A. The access groove357is formed at a position overlapping the key accommodating groove355when viewed from the circumferential direction Dc. The access groove357communicates with the circumferential groove25in the radial direction Dr. The access groove357of the present embodiment has an access groove side surface357sfacing the one side Dc1in the circumferential direction Dc, and an access groove end surface357dfacing the downstream side Dad in the axial direction Da.

In the plurality of rotor blades32, one of a pair of rotor blades32adjacent to each other in the circumferential direction Dc is referred to as a first rotor blade32A, and the rotor blade32arranged on one side Dc1in the circumferential direction Dc with respect to the first rotor blade32A is referred to as a second rotor blade32B. The first side surface35sof the first rotor blade32A and the second side surface35tof the second rotor blade32B face each other in the circumferential direction Dc. Therefore, the access groove357formed in the platform35of the first rotor blade32A and the key accommodating groove355formed in the platform35of the second rotor blade32B communicate with each other in the circumferential direction Dc. The circumferential groove25is formed from the position overlapping the platform35of the second rotor blade32B to the position overlapping the platform35of the first rotor blade32A when viewed from the radial direction Dr. Therefore, the circumferential groove25communicates with the access groove357of the first rotor blade32A and the key accommodating groove355of the second rotor blade32B.

The key50A restrains the movement of the rotor blade32(second rotor blade32B) in the axial direction Da with respect to the disk portion23. The key50A is inserted into the key accommodating groove355and the circumferential groove25. The key50A of the present embodiment has, for example, a rectangular parallelepiped block shape. The key50A has a shape that allows movement in the circumferential groove25in the circumferential direction Dc. The key50A can move between the key accommodating groove355and the access groove357by moving in the circumferential direction Dc in the circumferential groove25. The key50A has the same length in the axial direction Da as the circumferential groove25and the key accommodating groove355to be in sliding contact with the circumferential groove25and the key accommodating groove355. As shown inFIGS.3and4, a region on the inner side Dri in the radial direction Dr in the key50A is accommodated in the circumferential groove25. The region of the outer side Dro in the radial direction Dr in the key50A is inserted into the key accommodating groove355.

As shown inFIG.4, a region including an end portion51eof the other side Dc2in the circumferential direction Dc, which is a part of the key50A, protrudes from the second side surface35tof the platform35to the other side Dc2in the circumferential direction Dc in a state where the key50A is accommodated in the circumferential groove25and the key accommodating groove355. As shown inFIG.5, even when the key50A is accommodated in the circumferential groove25and the key accommodating groove355, the region including the end portion51eis in contact with the access groove end surface357d. Further, the key50A is formed in such a size that the key50A does not protrude into the key accommodating groove355when the key50A is accommodated in the circumferential groove25and the access groove357.

The restraining member60is arranged in the access groove357of the first embodiment. The restraining member60restrains the movement of the key50A approaching the access groove side surface357sin the circumferential direction Dc. The restraining member60is arranged between the key50A accommodated in the circumferential groove25and the key accommodating groove355and the access groove side surface357sin the circumferential direction Dc. That is, the restraining member60restricts the approaching movement of the key50A accommodated in the circumferential groove25and the key accommodating groove355toward the access groove side surface357s.

The restraining member60of the present embodiment is formed in a rectangular parallelepiped block shape larger than the key50A. The restraining member60has a shape that allows movement in the access groove357in the axial direction Da. By moving the restraining member60in the access groove357in the axial direction Da, the restraining member60can be inserted into the access groove357in a state where the key50A is accommodated in the key accommodating groove355. The restraining member60is formed so that the end portion60don the downstream side Dad in the axial direction Da of the restraining member60does not protrude from the disk surface23d. In the present embodiment, the end portion60dof the restraining member60is arranged at the same position as the disk surface23din the axial direction Da.

Further, as shown inFIG.2, the restraining member60is restrained from moving in the axial direction Da in a state where the restraining member60is accommodated in the access groove357by a punching portion100P formed on the disk surface23d. The punching portion100P is a region that is plastically deformed by being subjected to punching on the disk surface23d. The punching portion100P is recessed from the disk surface23dto deform the outer peripheral surface23fadjacent the access groove357when viewed from the axial direction Da. The punching portion100P is formed at a position overlapping the circumferential groove25when viewed from the axial direction Da. The punching portion100P is formed on the inner side Dri in the radial direction Dr with respect to the access groove357when viewed from the axial direction Da.

The punching portion100P restrains the movement of the restraining member60in the axial direction Da and the circumferential direction Dc, and does not restrain the movement in the axial direction Da of the rotor blade32on which the flow pressure of the steam S flowing in the casing10acts. Therefore, a large pressure does not act on the punching portion100P, and it is suppressed that the punching portion100P is peeled off. Further, as long as the punching portion100P is formed at a position where the movement of the restraining member60in the circumferential direction Dc can be restrained, the movement of the restraining member60in the axial direction Da may not be restrained.

By arranging the key50A in the circumferential groove25and the key accommodating groove355in this way, the second rotor blade32B is restrained from moving in the axial direction Da with respect to the disk portion23. Further, by inserting the restraining member60between the key50A and the access groove side surface357s, the key50A arranged in the circumferential groove25and the key accommodating groove355cannot move to the other side Dc2in the circumferential direction Dc. As a result, the key50A is prevented from coming out of the circumferential groove25and the key accommodating groove355.

(Procedure in Method for Fixing Rotor Blade)

Next, a method S10for fixing a rotor blade fixing the above-described rotor blade32to the disk portion23by the key50A will be described. As shown inFIG.6, the method S10for fixing the rotor blade32according to the first embodiment includes a step S11of attaching the second rotor blade32B, a step S12of inserting the key50A into the circumferential groove25, a step S13of inserting the key50A into the key accommodating groove355, a step S14of attaching the first rotor blade32A, a step S15of arranging the restraining member60, and a step S16of fixing the restraining member60.

In the step S11of attaching the second rotor blade32B, one rotor blade32is attached to the disk portion23as the second rotor blade32B. Specifically, as shown inFIG.2, the blade root36is embedded in the blade embedding groove28of the disk portion23. The blade root36is inserted into the blade embedding groove28, for example, by moving the blade root36from the upstream side Dau in the axial direction Da to the downstream side Dad in the axial direction Da. As shown inFIG.7, the second rotor blade32B is moved until the first end surface35dis located at the same position as the disk surface23din the axial direction Da.

In the step S12of inserting the key50A into the circumferential groove25, the key50A is inserted into the circumferential groove25. In the step S12of the present embodiment, one key50A is attached to the disk portion23to which the second rotor blade32B is attached. The key50A is inserted into the circumferential groove25at a position shifted in the circumferential direction Dc with respect to the position where the second rotor blade32B is arranged when viewed from the radial direction Dr. Specifically, the key50A is arranged in the circumferential groove25at a position (in the present embodiment, a position where the first rotor blade32A is arranged later) distant from the other side Dc2in the circumferential direction Dc with respect to the second side surface35tof the second rotor blade32B so as not to overlap the second rotor blade32B. By moving the key50A from the outer side Dro toward the inner side Dri in the radial direction Dr, the region of the inner side Dri in the radial direction Dr in the key50A is arranged in the circumferential groove25.

In the step S13of inserting the key50A into the key accommodating groove355, as shown inFIG.8, the key50A is moved in the circumferential direction Dc in the circumferential groove25and inserted into the key accommodating groove355. Specifically, the key50A is moved to one side Dc1in the circumferential direction Dc in the circumferential groove25. As a result, the key50A is inserted into the key accommodating groove355opened at the second side surface35tof the second rotor blade32B from the position shifted in the circumferential direction Dc with respect to the position where the second rotor blade32B is arranged. That is, the key50A is moved to overlap the position where the second rotor blade32B is arranged when viewed from the radial direction Dr. When the key50A is inserted into the key accommodating groove355, the key50A is inserted into the key accommodating groove355and the circumferential groove25at the position overlapping the second rotor blade32B. Further, in a state where the key50A is accommodated in the key accommodating groove355, the end portion51eof the key50A is arranged at a position protruding from the second side surface35tto the other side Dc2in the circumferential direction Dc. In this state, the region on the inner side Dr in the radial direction Dr in the key50A is accommodated in the circumferential groove25, and the region of the outer side Dro in the radial direction Dr in the key50A is inserted in the key accommodating groove355. As a result, the second rotor blade32B is restrained from moving in the axial direction Da with respect to the disk portion23by the key50A.

In the step S14of attaching the first rotor blade32A, as shown inFIG.9, one rotor blade32is attached to the disk portion23as the first rotor blade32A. Specifically, the first rotor blade32A is attached at a position adjacent to the second rotor blade32B on the other side Dc2in the circumferential direction Dc. In this case, the blade root36is embedded in the blade embedding groove28as in the step S11. When the blade root36is embedded in the blade embedding groove28, the end portion51eof the key50A protrudes from the second side surface35tof the second rotor blade32B to the other side Dc2in the circumferential direction Dc. Therefore, when the blade root36of the first rotor blade32A is moved toward the downstream side Dad in the axial direction Da, the access groove end surface357dof the access groove357of the first rotor blade32A abuts on the end portion51e. As a result, in the process of attaching the first rotor blade32A, the movement of the first rotor blade32A to the downstream side Dad in the axial direction Da is restrained.

The step S15of arranging the restraining member60is performed after the first rotor blade32A and the second rotor blade32B are attached to the disk portion23and the key50A is inserted into the key accommodating groove355. In the step S15of arranging the restraining member60, the restraining member60is arranged in the access groove357of the first rotor blade32A. Specifically, the restraining member60is inserted into the access groove357from the downstream side Dad in the axial direction Da. The restraining member60is inserted to a position where the restraining member60comes into contact with the access groove end surface357d. As a result, the restraining member60is inserted between the key50A and the access groove side surface357s. As a result, the movement of the key50A approaching the access groove side surface357sin the circumferential direction Dc is restrained.

In the step S16of fixing the restraining member60, the restraining member60arranged in the access groove357is fixed. In the present embodiment, the movement of the restraining member60arranged in the access groove357in the axial direction Da and the circumferential direction Dc is restrained, and thus, the position of the restraining member60is fixed. Specifically, as shown inFIG.2, the punching portion100P is formed by punching the disk surface23d. The punching portion100P is recessed from the disk surface23dto deform the outer peripheral surface23fadjacent the access groove357when viewed from the axial direction Da. Due to the punching portion100P, the outer peripheral surface23ffacing the access groove357is plastically deformed to slightly protrude to the outer side Dro in the radial direction Dr when viewed from the axial direction Da. As a result, the protruding portion of the punching portion100P abuts on the restraining member60. As a result, the movement of the restraining member60in the axial direction Da is restrained. In this way, the attachment to the disk portion23of the first rotor blade32A and the second rotor blade32B is completed.

After that, the rotor blade32attached to the disk portion23as the first rotor blade32A is handled as a new second rotor blade32B, and the step S12and subsequent steps of inserting the above-mentioned key50A into the circumferential groove25are performed. In the step S12, a new key50A is inserted into the circumferential groove25with respect to the second side surface35tof the new second rotor blade32B. After that, the steps S13to S16are sequentially executed in the same manner as described above. In this way, by sequentially attaching the first rotor blades32A adjacent to the second rotor blades32B in the circumferential direction Dc, all the rotor blades32of one rotor blade row31are attached to the disk portion23. By performing this at the positions of the other rotor blade rows31, the rotor20of the steam turbine1is manufactured.

In the rotor20of the steam turbine1having the above configuration, the steam turbine1, and the method S10for fixing the rotor blade32, the rotor blade32(second rotor blade32B) is fixed in a state of being immovable in the axial direction Da with respect to the disk portion23by the key50A arranged in the circumferential groove25and the key accommodating groove355. The key50A is moved to one side Dc1in the circumferential direction Dc in the circumferential groove25with respect to the second rotor blade32B in which the blade root36is inserted into the blade embedding groove28, and thus, the key50A is also inserted into the key accommodating groove355. Accordingly, the key50A is arranged in the circumferential groove25and the key accommodating groove355of the second rotor blade32B from the position shifted with respect to the second rotor blade32B. As a result, the second rotor blade32B cannot move in the axial direction Da with respect to the key50A accommodated in the circumferential groove25. Therefore, simply by moving the key50A in the circumferential groove25and arranging the key50A in the circumferential groove25and the key accommodating groove355, the second rotor blade32B can be reliably fixed in a state of being immovable with respect to the disk portion23. In this way, the rotor blade32can be easily and reliably restrained by the key50A.

Further, the circumferential groove25extends in the circumferential direction Dc from the position overlapping the platform35of the second rotor blade32B to the position overlapping the platform35of the first rotor blade32A. As a result, even after the blade root36of the second rotor blade32B is embedded in the blade embedding groove28, the key50A can be inserted into the circumferential groove25at the position where the first rotor blade32A shifted in the circumferential direction Dc with respect to the second rotor blade32B is arranged. After that, the key50A is simply moved in the circumferential groove25to one side Dc1of the circumferential direction Dc, and is inserted into the key accommodating groove355of the second rotor blade32B without interfering with the second rotor blade32B. Therefore, the second rotor blade32B can be fixed to the disk portion23by the key50A regardless of the order in which the second rotor blade32B and the key50A are attached.

Further, the restraining member60for restraining the movement of the key50A approaching the access groove side surface357sin the circumferential direction Dc is arranged in the access groove357. As a result, by inserting the restraining member60between the key50A and the access groove side surface357s, the key50A arranged in the circumferential groove25and the key accommodating groove355is restrained from moving to the other side Dc2in the circumferential direction Dc. Therefore, it is possible to prevent the key50A from coming out of the circumferential groove25and the key accommodating groove355. As a result, the key50A can be prevented from coming off from the circumferential groove25, and the state where the movement of the second rotor blade32B in the axial direction Da can be restrained can be stably maintained. Further, the restraining member60is arranged between the key50A and the access groove side surface357sin the access groove357. Therefore, even when the plurality of rotor blades32(first rotor blade32A and second rotor blade32B) and the key50A is attached to the disk portion23, the restraining member60can be accessed through the access groove357. That is, even when the first rotor blade32A and the second rotor blade32B are fixed to the disk portion23, the restraining member60can be attached or detached. Therefore, by attaching/detaching the restraining member60to/from the access groove357, the fixing of the second rotor blade32B by the key50A can be easily released.

Further, the outer peripheral surface23fis deformed by the punching portion100P and the shape of the circumferential groove25is changed, so that the movement of the restraining member60in the axial direction Da and the circumferential direction Dc is restrained. As a result, it is possible to prevent the restraining member60from naturally falling out of the access groove357due to vibration or the like during operation of the steam turbine1. Therefore, the state where the movement of the second rotor blade32B in the axial direction Da by the key50A is restrained can be maintained more stably.

Further, with respect to the second rotor blade32B, the end portion51eof the key50A protrudes to the other side Dc2in the circumferential direction Dc. Therefore, when the blade root36of the first rotor blade32A is moved toward the downstream side Dad in the axial direction side Da, the access groove end surface357dof the first rotor blade32A abuts on the end portion51e. As a result, in the process of attaching the first rotor blade32A, the movement of the first rotor blade32A to the downstream side Dad in the axial direction Da is restrained. Therefore, when the first rotor blade32A is attached, it is possible to prevent the disk portion23from going too far to the downstream side Dad in the axial direction Da. Therefore, positioning of the first rotor blade32A in the axial direction Da with respect to the disk portion23can be easily and accurately performed.

Further, by fixing the rotor blade32to the disk portion23using the key50A, the rotor blade32can be easily and reliably restrained by the key50A at the time of assembling the steam turbine1, the maintenance of the rotor20, and the like. Further, the rotor blade32can be easily detached from the disk portion23simply by moving the key50A.

Modification Example of First Embodiment

The structure of the restraining member60is not limited to the structure of the first embodiment. The restraining member60may have a structure capable of restraining the movement of the key50A. As a modification example of the restraining member60, for example, the following configuration is also possible.

As shown inFIG.10, a restraining member60B is inserted between the key50A and the access groove side surface357s, similarly to the restraining member60in the first embodiment. When viewed from the radial direction Dr, the restraining member60B protrudes from the key50A to the downstream side Dad in the axial direction Da in the access groove357. The restraining member60B has an insertion portion601and a protrusion portion (rotation restriction portion)602. The insertion portion601is arranged between the key50A and the access groove side surface357sin the axial direction Da. The protrusion portion602restricts the rotation of the insertion portion601when viewed from the radial direction Dr in the access groove357. Specifically, the protrusion portion602is arranged at a position close to the first end surface35din the axial direction Da with respect to the insertion portion601. The protrusion portion602is integrally formed with the insertion portion601. The protrusion portion602protrudes to one side Dc1in the circumferential direction Dc at a position shifted to the downstream side Dad in the axial direction Da with respect to the key50A when viewed from the radial direction Dr. The protrusion portion602protrudes to overlap when the key50A is arranged in the circumferential direction Dc. The protrusion portion602is arranged in the access groove357at a position facing a key end surface505of the key50A. The key end surface505is a plane facing the downstream side Dad in the axial direction Da in the key50A.

In the restraining member60B of the modification example, the protrusion portion602abuts on the key end surface505. Therefore, the restraining member60B is prevented from rotating about a virtual axis extending in the radial direction Dr when viewed from the radial direction Dr in the access groove357. As a result, it is possible to more stably maintain the state where the key50A by the insertion portion601is restrained from moving to the other side Dc2in the circumferential direction Dc.

Second Embodiment

Next, a second embodiment of a rotor of a steam turbine, a steam turbine, and a method for fixing a rotor blade according to the present disclosure will be described. In the second embodiment described below, the same reference numerals are given in the drawings to the configurations common to the first embodiment, and descriptions thereof will be omitted. The second embodiment is different from the first embodiment in that the restraining member60is not provided and a key50B is used.

As shown inFIGS.11and12, in a rotor20B of the steam turbine1of the present embodiment, the rotor blades32are restrained from moving in the axial direction Da with respect to the disk portion23by the key50B. The key50B is arranged inside the circumferential groove25and the key accommodating groove355. As shown inFIGS.11to13, the key50B of the second embodiment integrally has a key body portion53and a key extension portion54.

The key body portion53is inserted into the key accommodating groove355, the circumferential groove25, and the access groove357. The key body portion53is formed, for example, in the shape of a rectangular parallelepiped block shape. The key body portion53has a shape that allows movement in the circumferential groove25in the circumferential direction Dc. The key body portion53can move between the key accommodating groove355and the access groove357by moving in the circumferential groove25in the circumferential direction Dc. The key body portion53has the same length in the axial direction Da as the circumferential groove25and the key accommodating groove355to be in sliding contact with the circumferential groove25and the key accommodating groove355. The region including the end portion53eon the other side Dc2in the circumferential direction Dc, which is a part of the key body portion53, protrudes from the second side surface35tto the other side Dc2in the circumferential direction Dc in a state where the key body portion53is accommodated in the circumferential groove25and the key accommodating groove355. Even when the key body portion53is accommodated in the circumferential groove25and the key accommodating groove355, a part of the region including the end portion53eis arranged in the access groove357.

The key extension portion54extends from the end portion53eof the key body portion53to the downstream side Dad in the axial direction Da. When viewed from the axial direction Da, the key extension portion54is arranged at a position on the outer side Dro in the radial direction Dr with respect to the circumferential groove25, in a state where the key body portion53is accommodated in the circumferential groove25and the key accommodating groove355. The key extension portion54is arranged in the access groove357when viewed from the axial direction Da. In the key extension portion54, the end portion54dof the downstream side Dad in the axial direction Da extends to the same position as the disk surface23din the axial direction Da. A punching portion100Q is formed in the disk surface23don the inner side Dri in the radial direction Dr with respect to the end portion54dof the key extension portion54. By forming the punching portion100Q, the portion of the inner side Dri in the radial direction Dr of the end portion54dis plastically deformed in the disk surface23d, and the movement of the key extension portion54in the axial direction Da and the circumferential direction Dc is restrained.

As long as the punching portion100Q of the second embodiment is formed at a position where the movement of the key50B in the circumferential direction Dc can be restrained, the movement of the key50B in the axial direction Da may not be restrained.

(Procedure in Method for Fixing Rotor Blade)

Next, a method S20for fixing a rotor blade according to a second embodiment for fixing the above-described rotor blade32to the disk portion23by the key50B will be described. The method S20for fixing the rotor blade32according to the second embodiment is different from the method S10for fixing the rotor blade32according to the first embodiment, does not include the step S15of arranging the restraining member60and the step S16of fixing the restraining member60, and includes a step S24of fixing the key50B. Specifically, as shown inFIG.14, the method S20for fixing the rotor blade32according to the second embodiment includes the step S11of attaching the second rotor blade32B, a step S22of inserting the key50B into the circumferential groove25, a step S23of inserting the key50B into the key accommodating groove355, the step S24of fixing the key50B, and the step S15of attaching the first rotor blade32A.

The step S11of attaching the second rotor blade32B is performed in the same manner as in the first embodiment. After that, in the step S22of inserting the key50B into the circumferential groove25, as shown inFIG.15, the key body portion53of the key50B is inserted into the circumferential groove25. In the step S22of the present embodiment, one key50B is attached to the disk portion23to which the second rotor blade32B is attached. The key body portion53is inserted into the circumferential groove25at a position shifted from the position where the second rotor blade32B is arranged in the circumferential direction Dc when viewed from the radial direction Dr. By moving the key body portion53from the outer side Dro toward the inner side Dri in the radial direction Dr, the region on the inner side Dri in the radial direction Dr in the key body portion53is arranged in the circumferential groove25.

In the step S23of inserting the key50B into the key accommodating groove355, the key50B is moved in the circumferential direction Dc in the circumferential groove25, and the key body portion53is inserted into the key accommodating groove355. The key body portion53is inserted into the key accommodating groove355opened at the second side surface35tof the second rotor blade32B from a position shifted in the circumferential direction Dc with respect to the position where the second rotor blade32B is arranged. Further, as shown inFIG.12, in a state where the key body portion53is accommodated in the key accommodating groove355, the end portion53eof the key body portion53is arranged at a position protruding from the second side surface35tto the other side Dc2in the circumferential direction Dc. Further, the key extension portion54extending from the end portion53eis arranged in the access groove357. In this state, the region on the inner side Dri in the radial direction Dr in the key body portion53is accommodated in the circumferential groove25, and the region of the outer side Dro in the radial direction Dr in the key body portion53is inserted into the key accommodating groove355. As a result, the second rotor blade32B is restrained from moving in the axial direction Da with respect to the disk portion23by the key body portion53.

After that, the step S14of attaching the first rotor blade32A is performed in the same manner as in the first embodiment. When the blade root36of the first rotor blade32A is moved toward the downstream side Dad in the axial direction Da, the access groove end surface357dof the access groove357of the first rotor blade32A abuts on the end portion53e. As a result, in the process of attaching the first rotor blade32A, the movement of the first rotor blade32A to the downstream side Dad in the axial direction Da is restrained. Further, in a state where the key body portion53is accommodated in the key accommodating groove355, the key extension portion54extends from the end portion53eof the key body portion53to the downstream side Dad in the axial direction Da in the access groove357.

In the step S25of fixing the key50B, the moved key50B in which the key body portion53is accommodated is fixed in the key accommodating groove355. In the present embodiment, the position of the key50B is fixed by restraining the movement of the axial direction Da and the circumferential direction Dc of the key extension portion54arranged in the access groove357. Specifically, in the disk surface23d, punching is performed on the portion on the inner side Dri in the radial direction Dr of the key extension portion54. As a result, the punching portion100Q is formed. The punching portion100Q is recessed from the disk surface23dto deform the outer peripheral surface23fadjacent the access groove357when viewed from the axial direction Da. Due to the punching portion100Q, the outer peripheral surface23fclose to the key extension portion54is plastically deformed to protrude to the outer side Dro in the radial direction Dr. As a result, the protruding portion of the punching portion100Q abuts on the key extension portion54. Accordingly, the movement of the key50B in the axial direction Da and the circumferential direction Dc is restrained. As a result, the attachment of the first rotor blade32A and the second rotor blade32B to the disk portion23is completed.

After that, as in the first embodiment, each step is repeatedly performed, and thus, all the rotor blades32of one rotor blade row31are attached to the disk portion23.

The step S23of inserting the key50B into the key accommodating groove355may be performed after the step S14of attaching the first rotor blade32A. In that case, by moving the key extension portion54, the key body portion53is inserted into the key accommodating groove355.

In the second embodiment, the second rotor blade32B is fixed in a state of being immovable in the axial direction Da with respect to the disk portion23by the key body portion53arranged in the circumferential groove25and the key accommodating groove355. The key body portion53is moved to one side Dc1in the circumferential direction Dc in the circumferential groove25with respect to the second rotor blade32B in which the blade root36is inserted into the blade embedding groove28, and thus, the key body portion53is also inserted into the key accommodating groove355. Thereby, the rotor blade32can be easily and reliably restrained by the key50B.

Further, the outer peripheral surface23fis deformed by the punching portion100Q and the shape of the circumferential groove25is changed, so that the movement of the key extension portion54extending from the key body portion53in the axial direction Da and the circumferential direction Dc is restrained. Therefore, the movement of the key body portion53in the axial direction Da and the circumferential direction Dc is also restrained. As a result, it is possible to prevent the key body portion53from moving to come out from the inside of the key accommodating groove355to the other side Dc2in the circumferential direction Dc due to vibration or the like during the operation of the steam turbine1. As a result, the state where the movement of the second rotor blade32B in the axial direction Da is restrained by the key50B can be maintained more stably without using a member other than the key50B such as the restraining member60.

Further, the key extension portion54extends from the key body portion53in the access groove357in the axial direction Da. Therefore, the key body portion53in the circumferential groove25can be easily moved to the circumferential direction Dc through the key extension portion54in the access groove357. That is, even when the first rotor blade32A and the second rotor blade32B are fixed to the disk portion23, the key body portion53can be inserted or removed from the key accommodating groove355. Therefore, by moving the key extension portion54, the fixing of the second rotor blade32B by the key50B can be easily released.

Third Embodiment

Next, a third embodiment of a rotor of a steam turbine, a steam turbine, and a method for fixing a rotor blade according to the present disclosure will be described. In the third embodiment described below, the same reference numerals are given in the drawings to the configurations common to the first embodiment and the second embodiment, and descriptions thereof will be omitted. The third embodiment is different from the first embodiment in that the restraining member60is not provided and a key50C is used.

As shown inFIGS.16to18, in a rotor20C of the steam turbine1of the present embodiment, the rotor blades32are restrained from moving in the axial direction Da with respect to the disk portion23by the key50C. The key50C of the third embodiment integrally has a key main portion57and a key stopper portion58.

The key main portion57is inserted into the circumferential groove25and the key accommodating groove355. The key main portion57is formed in a semicircular shape, for example, when viewed from the axial direction Da. The key main portion57is rotatable around a central axis57cextending in the axial direction Da in the circumferential groove25and the key accommodating groove355. The key main portion57is movable between the key accommodating groove355and the access groove357by rotating in the circumferential groove25. The key main portion57has the same length in the axial direction Da as the circumferential groove25and the key accommodating groove355to be in sliding contact with the circumferential groove25and the key accommodating groove355. Further, it is preferable that an outer peripheral portion of the key main portion57is chamfered or has a curved surface shape. The key main portion57may have a circular shape when viewed from the axial direction Da.

The key stopper portion58restrains the movement of the key main portion57approaching the access groove side surface357sin the circumferential direction Dc. The key stopper portion58extends from the key main portion57to the downstream side Dad in the axial direction Da. The key stopper portion58is formed in a columnar shape having a ¼ circular (quarter circle) cross-sectional shape when viewed from the axial direction Da, for example. The key stopper portion58is integrally formed with the key main portion57to be attached to a plane portion forming a diameter of the key main portion57having a semicircular plate shape when viewed from the axial direction Da.

The disk portion23is formed with an axial groove29in which the key stopper portion58is accommodated. The axial groove29is recessed from the outer peripheral surface23fto the inner side Dri in the radial direction Dr and extends in the axial direction Da. The axial groove29is formed to open at the disk surface23d. The axial groove29communicates with the circumferential groove25in the axial direction Da. The axial groove29is formed at a position where the axial groove29can communicate with the access groove357in the radial direction Dr.

The key stopper portion58is arranged in the axial groove29in a state where the key main portion57is accommodated in the circumferential groove25and the key accommodating groove355. In the state where the key main portion57is accommodated in the circumferential groove25and the key accommodating groove355, an end portion58don the downstream side Dad in the axial direction Da of the key stopper portion58is arranged at the same position as that of the disk surface23din the axial direction Da.

In the third embodiment, it is not essential to form the punching portion for restraining the movement of the key50C in the disk surface23d. When the punching portion is formed, the punching portion may be formed on the end portion58dof the key stopper portion58and the disk surface23dat a position adjacent to each other in the circumferential direction Dc.

(Procedure in Method for Fixing Rotor Blade)

Next, a method S30for fixing a rotor blade according to a third embodiment for fixing the above-described rotor blade32to the disk portion23by the key50C will be described. The method S30for fixing the rotor blade32according to the third embodiment is different from that of the second embodiment in the arrangement and fixing method of the key50C. As shown inFIG.19, the method S30for fixing the rotor blade32according to the embodiment of the present disclosure includes the step S11of attaching the second rotor blade32B, a step S32of inserting the key50C into the circumferential groove25, a step S33of inserting the key50C into the key accommodating groove355, and the step S14of attaching the first rotor blade32A.

The step S11of attaching the second rotor blade32B is performed in the same manner as in the first embodiment. After that, in the step S32of inserting the key50C into the circumferential groove25, as shown inFIGS.20and21, the key main portion57of the key50C is inserted into the circumferential groove25. In the step S32of the present embodiment, one key50C is attached to the disk portion23to which the second rotor blade32B is attached. The key main portion57is inserted into the circumferential groove25at a position shifted from the position where the second rotor blade32B is arranged in the circumferential direction Dc when viewed from the radial direction Dr. At that time, the key main portion57formed in a semicircular shape when viewed from the axial direction Da is arranged to fit in the circumferential groove25. Meanwhile, the key stopper portion58is arranged on the outer side Dro in the radial direction Dr from the outer peripheral surface23fof the disk portion23. That is, when viewed from the axial direction Da, the key stopper portion58is arranged in a state where the key stopper portion58protrudes from the outer peripheral surface23fof the disk portion23.

In the step S33of inserting the key50C into the key accommodating groove355, the key50C is moved to the circumferential direction Dc in the circumferential groove25, and the key main portion57is inserted into the key accommodating groove355. The key main portion57is moved from a position shifted in the circumferential direction Dc with respect to the position where the second rotor blade32B is arranged to a position where the second rotor blade32B is arranged. After that, as shown inFIG.22, the key stopper portion58is rotated by 90° about the central axis57c. As a result, the key main portion57also rotates by 90°, and the posture of the key main portion57changes to become longer in the radial direction Dr. That is, when viewed from the axial direction Da, the posture changes from a state where a plane portion forming the diameter of the key main portion57faces the radial direction Dr to a state where the plane portion faces the circumferential direction Dc. As a result, a part of the key main portion57is inserted into the key accommodating groove355. Therefore, the key main portion57is in a state of being inserted into the key accommodating groove355and the circumferential groove25of the second rotor blade32B. As a result, the second rotor blade32B is restrained from moving in the axial direction Da with respect to the disk portion23by the key main portion57. Further, in a state where the key main portion57is inserted into the key accommodating groove355and the circumferential groove25, the key stopper portion58enters the axial groove29. As a result, the key stopper portion58becomes immovable in the circumferential direction Dc in the axial groove29. Therefore, the movement of the key main portion57approaching the access groove side surface357sin the circumferential direction Dc is restrained. Accordingly, the movement of the key50C in the circumferential direction Dc is restrained. As a result, the attachment of the first rotor blade32A and the second rotor blade32B to the disk portion23is completed. After that, as in the first embodiment, each step is repeatedly performed, and thus, all the rotor blades32of one rotor blade row31are attached to the disk portion23.

In the third embodiment, the second rotor blade32B is fixed in a state where the second rotor blade32B is immovable in the axial direction Da with respect to the disk portion23by the key main portion57arranged in the circumferential groove25and the key accommodating groove355. The key main portion57is rotated in the circumferential groove25with respect to the second rotor blade32B in which the blade root36is inserted into the blade embedding groove28, and thus, inserted into the key accommodating groove355. Thereby, the rotor blade32can be easily and reliably restrained by the key50C.

Further, the key main portion57is rotated and inserted into the key accommodating groove355, so that the key stopper portion58is inserted into the axial groove29. The key stopper portion58is in a state of being immovable in the circumferential direction Dc in the axial groove29. Therefore, the movement of the key50C in the circumferential direction Dc is restrained in a state where the key stopper portion58is accommodated in the axial groove29. That is, the movement of the key50C in the circumferential direction Dc can be restrained without using a structure that is plastically deformed like the punching portion. As a result, it is possible to prevent the key main portion57from moving to come out from the inside of the key accommodating groove355to the other side Dc2in the circumferential direction Dc due to vibration or the like during the operation of the steam turbine1. As a result, the state where the movement of the second rotor blade32B in the axial direction Da is restrained by the key50C can be stably and more stably maintained.

Modification Examples of Other Embodiments

In the above-described embodiments and the modification examples thereof, the procedure in the method for fixing the rotor blade has been described, but the procedure can be changed as appropriate.

For example, in the above embodiments, after the second rotor blade32B is restrained by the keys50A to50C, the first rotor blade32A is installed on the other side in the circumferential direction Dc with respect to the second rotor blade32B. However, the present disclosure is not limited to being assembled in this order. For example, the keys50A to50C may be arranged in the circumferential groove25in advance on the disk portion23before the second rotor blade32B. Further, for example, after all the keys50A to50C are arranged on the disk portion23, all the rotor blades32may be attached over the entire circumference in the circumferential direction Dc. In this case, the keys50A to50C may be moved and the restraining members60and60B may be installed through the access groove357formed in the arranged rotor blades32. At that time, a jig that is inserted into the access groove357to assist the movements of the keys50A to50C may be used.

Further, the shapes of the keys50A to50C and the restraining members60and60B are not limited to the shapes of the above-described embodiments. The shapes of the keys50A to50C may be any shape that can restrict the movement of the rotor blade32with respect to the disk portion23. At that time, the shapes of the circumferential groove25and the key accommodating groove355are appropriately changed according to the shapes of the keys50A to50C. The restraining members60and60B may have a shape that can restrain the movement of the key50A. At that time, the shape of the access groove357is appropriately changed according to the shapes of the restraining members60and60B.

The rotors20to20C of the steam turbine1, the steam turbine1, and the method S10for fixing the rotor blade32according to each embodiment are grasped as follows, for example.

(1) According to a first aspect, there are provided rotors20to20C of a steam turbine1, the rotors20to20C include a shaft core portion22formed in a columnar shape about an axis Ar; a disk portion23extending to an outer side Dro in a radial direction Dr with respect to the shaft core portion22, in which the radial direction Dr is based on the axis Ar; a plurality of rotor blades32attached to the disk portion23; and keys50A to50C configured to restrict movement of each of the plurality of rotor blades32with respect to the disk portion23in an axial direction Da in which the axis Ar extends, in which the disk portion23includes a plurality of blade embedding grooves28recessed to an inner side Dri in the radial direction Dr from an outer peripheral surface23fof the disk portion23, extending in the axial direction Da, and formed at intervals in a circumferential direction Dc about the axis Ar, and a circumferential groove25recessed to the inner side Dri in the radial direction Dr from the outer peripheral surface23fand extending in the circumferential direction Dc, each of the plurality of rotor blades32includes a blade root36embedded in each of the blade embedding grooves28, a platform35arranged on the outer side Dro in the radial direction Dr with respect to the disk portion23and protruding to both sides in the circumferential direction Dc with respect to the blade root36, and a blade body33extending to the outer side Dro in the radial direction Dr from the platform35, the plurality of rotor blades32include a first rotor blade32A and a second rotor blade32B adjacent to the first rotor blade32A on one side Dc1in the circumferential direction Dc, the platform35of the first rotor blade32A includes a first side surface35sof the second rotor blade32B facing the platform35of the second rotor blade32B in the circumferential direction Dc, a first end surface35dfacing the axial direction Da, and an access groove357recessed to open in the axial direction Da and the circumferential direction Dc at a corner portion35cformed by the first side surface35sand the first end surface35dand communicating with the circumferential groove25, the platform35of the second rotor blade32B includes a second side surface35tfacing the first side surface35sin the circumferential direction Dc, and a key accommodating groove355recessed in the circumferential direction Dc from the second side surface35t, communicating with the circumferential groove25in the radial direction Dr, and communicating with the access groove357in the circumferential direction Dc, and the keys50A to50C are arranged in the circumferential groove25and the key accommodating groove355.

In the rotors20to20C of the steam turbine1, the rotor blade is fixed in a state where the rotor blade is immovable in the axial direction Da with respect to the disk portion23by the keys50A to50C arranged in the circumferential groove25and the key accommodating groove355. The keys50A to50C are moved in the circumferential direction Dc in the circumferential groove25with respect to the second rotor blade32B in which the blade root36is inserted into the blade embedding groove28, and thus, the keys50A to50C are also inserted into the key accommodating groove355. As a result, the second rotor blade32B cannot move in the axial direction Da with respect to the keys50A to50C accommodated in the circumferential groove25. Therefore, simply by moving the keys50A to50C in the circumferential groove25and arranging the keys50A to50C in the circumferential groove25and the key accommodating groove355, the second rotor blade32B can be reliably fixed in a state of being immovable with respect to the disk portion23. In this way, the rotor blade32can be easily and reliably restrained by the key50A.

(2) In the rotors20to20C of a steam turbine1according to a second aspect, in the rotors20to20C of a steam turbine1of (1), when viewed from the radial direction Dr, the circumferential groove25extends in the circumferential direction Dc from a position overlapping the platform35of the second rotor blade32B to a position overlapping the platform35of the first rotor blade32A and communicates with the access groove357in the radial direction Dr.

As a result, even after the blade root36of the second rotor blade32B is embedded in the blade embedding groove28, the key50A can be inserted into the circumferential groove25at the position where the first rotor blade32A shifted in the circumferential direction Dc with respect to the second rotor blade32B is arranged. After that, by simply moving the key50A in the circumferential direction Dc in the circumferential groove25, and the key50A can be inserted into the key accommodating groove355of the second rotor blade32B without interfering with the second rotor blade32B. Therefore, the second rotor blade32B can be fixed to the disk portion23by the key50A regardless of the order in which the second rotor blade32B and the key50A are attached.

(3) In the rotor20of a steam turbine1according to a third aspect, in the rotor20of a steam turbine1of (1) or (2), the access groove357has an access groove side surface357sfacing the second side surface35tin the circumferential direction Dc, and the rotor further includes a restraining member60arranged between the key50A and the access groove side surface357sin the circumferential direction Dc in the access groove357and restraining movement of the key50A approaching the access groove side surface357sin the circumferential direction Dc.

As a result, by inserting the restraining member60between the key50A and the access groove side surface357s, the key50A arranged in the circumferential groove25and the key accommodating groove355is restrained from moving in the circumferential direction Dc. Therefore, it is possible to prevent the key50A from coming out of the circumferential groove25and the key accommodating groove355. As a result, the key50A can be prevented from coming off from the circumferential groove25, and the state where the movement of the second rotor blade32B in the axial direction Da can be restrained can be stably maintained. Further, the restraining member60is arranged between the key50A and the access groove side surface357sin the access groove357. Therefore, even when the plurality of rotor blades32(first rotor blade32A and second rotor blade32B) and the key50A is attached to the disk portion23, the restraining member60can be accessed through the access groove357. That is, even when the first rotor blade32A and the second rotor blade32B are fixed to the disk portion23, the restraining member60can be attached or detached. Therefore, by attaching/detaching the restraining member60to/from the access groove357, the fixing of the second rotor blade32B by the key50A can be easily released.

(4) In the rotor20of a steam turbine1according to a fourth aspect, in the rotor20of a steam turbine1of (3), the restraining member60B includes an insertion portion601arranged between the key50A and the access groove side surface357sin the axial direction Da, and a rotation restriction portion602integrally formed with the insertion portion601at a position close to the first end surface35din the axial direction Da with respect to the insertion portion601and restricting rotation of the insertion portion601in the access groove357when viewed from the radial direction Dr.

Therefore, the restraining member60B is prevented from rotating about a virtual axis extending in the radial direction Dr when viewed from the radial direction Dr in the access groove357. As a result, it is possible to more stably maintain the state where the key50A by the insertion portion601is restrained from moving to the other side Dc2in the circumferential direction Dc.

(5) In the rotor20B of a steam turbine1according to a fifth aspect, in the rotor20B of a steam turbine1of (3) or (4), the disk portion23includes a punching portion100P formed on a disk surface23dfacing the axial direction Da to be orthogonal to the outer peripheral surface23fand recessed from the disk surface23dto deform the outer peripheral surface23fadjacent the access groove357when viewed from the axial direction Da, and the restraining member60is restrained from moving in the circumferential direction Dc by the punching portion100P.

As a result, the outer peripheral surface23fis deformed by the punching portion100P and the shape of the circumferential groove25is changed, so that the movement of the restraining member60is restrained. As a result, it is possible to prevent the restraining member60from naturally falling out of the access groove357due to vibration or the like during operation of the steam turbine1. Therefore, the state where the movement of the second rotor blade32B in the axial direction Da by the key50A is restrained can be maintained more stably.

(6) In the rotor20B of a steam turbine1according to a sixth aspect, in the rotor20B of a steam turbine1of (1) or (2), the access groove357has an access groove side surface357sfacing the second side surface35tin the circumferential direction Dc, the key50B integrally includes a key body portion53inserted into the circumferential groove25, the key accommodating groove355, and the access groove357, and a key extension portion54extending in the axial direction Da from the key body portion53in the access groove357, the disk portion23includes a punching portion100Q formed on a disk surface23dfacing the axial direction Da to be orthogonal to the outer peripheral surface23fand recessed from the disk surface23dto deform the outer peripheral surface23fadjacent the access groove357when viewed from the axial direction Da, and the key extension portion54is restrained from moving toward the access groove side surface357sin the circumferential direction Dc by the punching portion100Q.

As a result, the outer peripheral surface23fis deformed by the punching portion100Q and the shape of the circumferential groove25is changed, so that the movement of the key extension portion54extending from the key body portion53is restrained. Therefore, the movement of the key body portion53is also restrained. Accordingly, it is possible to prevent the key body portion53from moving to come out in the circumferential direction Dc from the inside of the key accommodating groove355due to vibration or the like during the operation of the steam turbine1. As a result, the state where the movement of the second rotor blade32B in the axial direction Da is restrained by the key50B can be maintained more stably without using a member other than the key50B. Further, the key extension portion54extends from the key body portion53in the access groove357in the axial direction Da. Therefore, the key body portion53in the circumferential groove25can be easily moved to the circumferential direction Dc through the key extension portion54in the access groove357. That is, even when the first rotor blade32A and the second rotor blade32B are fixed to the disk portion23, the key body portion53can be inserted or removed from the key accommodating groove355. Therefore, by moving the key extension portion54, the fixing of the second rotor blade32B by the key50B can be easily released.

(7) In the rotor20C of a steam turbine1according to a seventh aspect, in the rotor20C of a steam turbine1of (1) or (2), the access groove357has an access groove side surface357sfacing the second side surface35tin the circumferential direction Dc, the disk portion23further includes an axial groove29extending in the axial direction Da to be recessed to the inner side Dri in the radial direction Dr from the outer peripheral surface23fand communicating with the circumferential groove25and the access groove357, and the key50C integrally includes a key main portion57inserted into the circumferential groove25and the key accommodating groove355, and a key stopper portion58extending in the axial direction Da from the key main portion57, arranged in the axial groove29, and restraining movement of the key main portion57approaching the access groove side surface357sin the circumferential direction Dc.

As a result, the key stopper portion58is in a state of being immovable in the circumferential direction Dc in the axial groove29. Therefore, the movement of the key50C in the circumferential direction Dc is restrained in a state where the key stopper portion58is accommodated in the axial groove29. That is, the movement of the key50C in the circumferential direction Dc can be restrained without using a structure that is plastically deformed like the punching portion. As a result, it is possible to prevent the key main portion57from moving to come out from the inside of the key accommodating groove355to the other side Dc2in the circumferential direction Dc due to vibration or the like during the operation of the steam turbine1. As a result, the state where the movement of the second rotor blade32B in the axial direction Da is restrained by the key50C can be stably and more stably maintained.

(8) According to an eighth aspect, there is provided a steam turbine1including the rotors20to20C of a steam turbine1according to any one of (1) to (7).

As a result, by providing the rotors of the steam turbine1described above, the rotor blade32can be easily and reliably restrained by the keys50A to50C at the time of assembling the steam turbine1, maintenance of the rotors20to20C, and the like.

(9) According to a ninth aspect, there are provided methods S10, S20, and S30for fixing the rotor blade32in the rotors20to20C of a steam turbine1according to any one of (1) to (7), the methods including steps S11, S21, and S31of attaching the second rotor blade32B to the disk portion23; steps S12, S22, and S32of inserting the keys50A to50C into the circumferential groove25; steps S13, S23, and S33of moving the keys50A to50C in the circumferential direction Dc in the circumferential groove25and inserting the keys50A to50C into the key accommodating groove355; and steps S14, S25, and S35of attaching the first rotor blade32A to the disk portion23.

As a result, the rotor blade is fixed in an immovable state in the axial direction Da with respect to the disk portion23by the keys50A to50C arranged in the circumferential groove25and the key accommodating groove355. The keys50A to50C are moved in the circumferential direction Dc in the circumferential groove25with respect to the second rotor blade32B in which the blade root36is inserted into the blade embedding groove28, and thus, the keys50A to50C are also inserted into the key accommodating groove355. As a result, the second rotor blade32B cannot move in the axial direction Da with respect to the keys50A to50C accommodated in the circumferential groove25. Therefore, simply by moving the keys50A to50C in the circumferential groove25and arranging the keys50A to50C in the circumferential groove25and the key accommodating groove355, the second rotor blade32B can be reliably fixed in a state of being immovable with respect to the disk portion23. In this way, the rotor blade32can be easily and reliably restrained by the key50A.

EXPLANATION OF REFERENCES