Patent Grant
10633977
The present invention relates to a blade, a gas turbine equipped with this blade, and a blade manufacturing method.
This application claims priority based on JP 2015-207873 filed in Japan on Oct. 22, 2015, of which the contents are incorporated herein by reference.
The gas turbine includes a rotor that rotates around an axial line, and a casing that covers the rotor. The rotor includes a rotor shaft and a plurality of blades that are attached to the rotor shaft. Furthermore, a plurality of vanes are attached to the inner circumferential side of the casing. The blade includes a blade body with an airfoil shape, a platform that extends in essentially a perpendicular direction with respect to the blade height direction from an end portion in the blade height direction of the blade body, and a shaft attachment portion that extends from the platform to the opposite side as the blade body.
The blades and vanes of the gas turbine are exposed to high temperature combustion gas. Therefore, the blades and vanes are generally cooled by air or the like.
For example, various types of cooling channels through which cooling airflow are formed in the rotating blade described in the following Patent Document 1. Specifically, blade channels where cooling air flows, with an interior that extends in the blade height direction are formed in the blade body, platform, and shaft attachment part. A gas path surface facing in the blade height direction and that contacts the combustion gas, a reverse gas path surface with a back matching relationship to the gas path surface, and an end surface along an edge of the gas path surface are formed in the platform. Furthermore, a platform channel where cooling gas flows is formed in the platform. The platform channel is a serpentine channel. The serpentine channel has a plurality of channels extending in a specific direction and arranged in a perpendicular direction to the specific direction. The serpentine channel forms a channel where ends of a plurality of channels are mutually connected to form an overall zigzag channel.
Patent Document 1: JP3073404 B
The rotating blade according to Patent Document 1 is generally manufactured by the following procedure.
(1) A mold is formed with an internal space that matches the external shape of the rotating blade.
(2) A channel core with an external shape that matches the shape of the platform channel and a skirt core that supports the channel core in the mold are formed.
(3) The channel core and the skirt core are placed in the mold, and molten metal is injected into the mold.
(4) After the molten metal hardens, the channel core and the skirt core are dissolved.
In addition to the platform channel where cooling air flows, a skirt hole is formed in a portion where the skirt core that was placed in the mold in the manufacturing step existed in the platform which is the end plate of the rotating blade manufactured by the above procedure.
The skirt hole of the platform which is the end plate is formed because of manufacturing requirements. However, a large stress is generated in the rotating blade because this skirt hole is formed in the rotating blade.
Accordingly, an object of the present invention is to provide a blade that can suppress the occurrence of high stress even though a plurality of channels are formed in the end plate, as well as a gas turbine having the blade, and a method of manufacturing the blade.
The blade of the first embodiment of the invention for achieving the aforementioned objective includes:
a blade body with an airfoil shape, disposed in a combustion gas channel where combustion gas flows; and
an end plate formed on an end portion in the blade height direction of the blade body;
the end plate including:
a gas path surface facing a side of the combustion gas channel;
a reverse gas path surface facing a side opposing the gas path surface;
an end surface along an edge of the gas path surface;
a plurality of channels that extend in a direction along the gas path surface, disposed between the gas path surface and the reverse gas path surface; and
a skirt hole opened in a partial end surface that is a portion of the end surface;
wherein the plurality of channels are aligned in a perspective direction with respect to the partial end surface; and
of the plurality of channels, the skirt hole communicates with an inside channel that is farther from the partial end surface than an outside channel that is near the partial end surface.
With this blade, a skirt hole is open in the partial end surface of the end plate. Therefore, stress occurs near the partial end surface where the skirt hole opening is formed in the blade. However, the outer circumferential side portion of the end plate is essentially a free end, so the stress that occurs in the side end portion including the partial end surface of the end plate is extremely small. Therefore, this blade can suppress damage near the opening of the skirt hole.
Furthermore, with this blade, cooling air that flows through the inside channel can pass through the skirt hole and be discharged from the partial end surface of the end plate. in other words, with this blade, the skirt hole can be used as an air channel for the cooling air to pass through. The cooling air that has been discharged from the partial end surface of the end plate cools the partial end surface.
The blade according to embodiment 2 of the present invention for achieving the aforementioned object is the blade according to the first embodiment, wherein the skirt hole partially overlaps the outside channel as seen from the blade height direction, and the position in the blade height direction of a portion of the skirt holes differs from the position in the blade height direction of the outside channel.
The blade according to embodiment 2 of the present invention for achieving the aforementioned object is the blade according to the first embodiment, wherein the skirt hole partially overlaps the outside channel as seen from the blade height direction, and the position in the blade height direction of a portion of the skirt holes differs from the position in the blade height direction of the outside channel.
With this blade, the plurality of channels passed through closer to the gas path surface side than the skirt hole. Therefore, with this blade, the gas path surface of the end plate can be effectively cooled by the cooling air that passes through the plurality of channels.
The blade according to the fourth embodiment of the present invention for achieving the aforementioned object is the blade according to the third embodiment,
wherein the skirt hole includes a first extending part that extends from the inside channel to the reverse gas path surface side, and a second extending part that extends from the end portion on the reverse gas path surface side toward the partial end surface, in the first extending part.
The blade according to the fifth embodiment of the present invention for achieving the aforementioned object is the blade according to the third embodiment,
wherein the skirt hole includes a tilted hole part that gradually, approaches the reverse gas path surface side when approaching the partial end surface from the inside channel.
The inside channel of the blade may be inspected by inserting a borescope inside. With this blade, the borescope can easily be inserted into the inside channel from the skirt hole. Therefore, with this blade, inspection of the inside channel can easily be performed.
The blade according to the sixth embodiment of the present invention for achieving the aforementioned object is the blade according to any one of the third through fifth embodiments, wherein the inside channel has an expanded part that expands closer to the reverse gas path surface side than the outside channel, and the skirt hole communicates with the expanded part of the inside channel.
With this blade as well, the borescope can easily be inserted into the inside channel from the skirt hole. Therefore, with this blade as well, inspection of the inside channel can easily be performed.
The blade according to the seventh embodiment of the present invention for achieving the aforementioned object is the blade according to any one of the first through sixth embodiments, having a plug that blocks the opening of the skirt hole in the partial end surface.
If cooling of the partially end surface by cooling air from the skirt hole is not necessary, the opening of the skirt hole in the partially end surface may be blocked by the plug. With this rotating blade, the centrifugal force toward the outer side in the radial direction acts on the plug when the gas turbine rotor rotates. With this rotating blades, the plug is received by the inner surface of the skirt hole even if there is an attempt to move the plug in the outward radial direction by the centrifugal force, and therefore removal from the skirt hole is difficult. Therefore, the rotating blade can suppress damage to the end plate.
The blade according to the eighth embodiment of the present invention for achieving the aforementioned object is the blade according to any one of the seventh embodiment, wherein the plug has a through hole that discharges the cooling air in the skirt hole to the outside.
With this blade, the flow of cooling air discharged from the partial end surface can be appropriately adjusted by appropriately adjusting the inner diameter of the through hole. Therefore, with this blade, the amount of cooling air that is used can be controlled while appropriately cooling the partial end surface.
The blade according to the ninth embodiment of the present invention for achieving the aforementioned object is the blade according into any one of the first through eighth embodiments, wherein each of the plurality of channels extends in the direction along the partial end surface and communicates with a channel that is adjacent in the perspective direction, at an end in the direction along the partial end surface, and thereby the plurality of channels mutually communicate and form one serpentine channel.
The gas turbine according to the 10th embodiment of the present invention for achieving the aforementioned object, includes: a plurality of the blades according to any one of the first through ninth embodiments; a rotor shaft to which a plurality of blades are attached;
a casing that covers the plurality of blades and the rotor shaft; and a combustor that transfers combustion gas to a region where the plurality of blades are disposed in the casing.
With the manufacturing method for a blade according to the 11th embodiment of the present invention for achieving the aforementioned objective, the blade has a blade body with an airfoil shape, disposed in the combustion gas channel where the combustion gas flows, and an end plate that extends from the end portion in the blade height direction of the blade body in a direction having a perpendicular component with respect to the blade height direction; the end plate has a gas path surface facing the combustion gas channel side, a reverse gas path surface facing the side opposing the gas path surface, and an air space where the cooling air flows; and
the method includes: a mold forming step of forming a mold that forms an internal space that matches the external shape of the blade; a core forming step of forming a core with an external shape that matches the shape of the air space in the end plate; a casting step where molten metal flows into the mold with the core provided in the mold; and a core dissolving step of dissolving the core after hardening the molten metal;
in the core forming step, the core is formed by: a channel core disposed between the gas bath surface and the reverse gas path surface at the end plate, extending in a direction along the gas path surface, and forming each of the plurality of channels aligned in the perspective direction with respect to the partial end surface which is a portion of the end surface; and
a skirt core that forms a skirt hole that opens in the partial end surface and communicates with an inside channel farther from the partial end surface than the outside channel that is close to the partial end surface, of the plurality of channels.
The manufacturing method for a blade according to the 12th embodiment of the invention for achieving the aforementioned objective is the manufacturing method for a blade according to the 11th embodiment, wherein a sealing step that blocks the opening of the skirt hole in the partial end surface using a plug, after the core dissolving step.
According to one aspect of the present invention, the high stress that occurs in the blade can be suppressed.
The following describes in detail the embodiments and various variant examples of the present invention, with reference to the drawings.
A gas turbine 10 as the first embodiment of the present invention includes a compressor 20 that compresses air A, a combustor 30 that generates a combustion gas G by burning a fuel F in the air A compressed by the compressor 20, and a turbine 40 driven by the combustion gas G, as illustrated in
The compressor 20 includes a compressor rotor 21 that rotates around an axial line Ar, a compressor casing 25 that covers the compressor rotor 21, and a plurality of vane rows 26. The turbine 40 includes a turbine rotor 41 that rotates around the rotational axial line Ar, a turbine casing 45 that covers the turbine rotor 41, and a plurality of vane rows 46.
The compressor rotor 21 and the turbine rotor 41 are positioned on the same axial line Ar and connected with each other to form the gas turbine rotor 11. A rotor of a generator GEN is connected to this gas turbine rotor 11, for example. The gas turbine 10 also includes an intermediate casing 14 provided between the compressor casing 25 and the turbine casing 45. The combustor 30 is attached to the intermediate casing 14. The compressor casing 25, intermediate casing 14, and the turbine casing 45 are connected with each other to form a gas turbine casing 15. Note that in the following, the direction that the axial line Ar stands is the axial direction Da, a circumferential direction around this axial line Ar is simply referred to as a circumferential direction Dc, and a direction orthogonal to the axial line Ar is referred to as a radial direction Dr. Furthermore, the compressor 20 side of the turbine 40 in the axial direction Da is referred to as the “upstream side Dau”, and the side opposite to this side as the “downstream side Dad”. Furthermore, the side closer to the axial line Ar in the radial direction Dr is referred to as the “radial direction inward side Dri”, and the opposite side is the “radial direction outward side Dro”.
The turbine rotor 41 includes a rotor shaft 42 that is centered around the axial line Ar and extends in the axial direction Da, and a plurality of rotor blade rows 43 attached to this rotor shaft 42. The plurality of rotor blade rows 43 are arranged in the axial direction Da. Each of the rotor blade rows 43 includes a plurality of rotor blades 50 arranged in the circumferential direction Dc. The vane rows 46 are respectively disposed on the upstream side Dau of each of the plurality of rotor blade rows 43. Each of the vane rows 46 is provided on an inner side of the turbine casing 45. Each of the vane rows 46 includes a plurality of vanes 46a arranged in the circumferential direction Dc.
A combustion gas flow channel 49 through which combustion gas G from the combustor 30 flows is formed in an annular space between an outer peripheral side of the rotor shaft 42 and an inner peripheral side of the turbine casing 45 in a region where the vane 46a and the rotor blade rows 50 are disposed in the axial direction Da. The combustion gas channel 49 forms a ring around the axial line Ar, extending in the axial direction Da.
As illustrated in
The blade body 51 is provided in the combustion gas channel 49. The blade body 51 is configured of a back side surface (negative pressure surface) 54 which is a convex surface and a front side surface (positive pressure surface) 55 which is a concave surface. The back side surface 54 and the front side surface 55 are connected by the leading edge 52 and the trailing edge 53 of the blade body 51. With the rotating blade 50 attached to the rotor shall 42, the leading edge 52 is located on the upstream side Dau of the axial direction Da with respect to the trailing edge 53. Furthermore, under this condition, the back side surface 54 and the front side surface 55 face any direction having a component of the circumferential direction Dc.
The platform 60 is a plate shaped member that extends from the end portion of the blade height direction Dwh in the blade body 51 in a direction having a perpendicular component with respect to the blade height direction Dwh. In other words, the platform 60 is an end plate of the blade body 51. A gas path surface 61 facing in the combustion gas channel 49 side, a reverse gas path surface 62 with a back matching relationship to the gas path surface 61, and end surfaces 63, 64 along an edge of the gas path surface 61 are formed in the platform 60. As illustrated in
The gas path surface 61 of the platform 60 is a surface that extends in a direction having a perpendicular component with respect to the blade height direction Dwh. The pair of side end surfaces 63 both extend in the direction having a perpendicular component to the width direction Dwp, and connect to the gas path surface 61. Furthermore, the pair of front and back end surfaces 64 both extend in the direction having a perpendicular component to the blade chord direction Dwc, and connect to the gas path surface 61. Of the pair of side end surfaces 63, a first side end surface 63 forms a back side end surface 63n, and the second side end surface 63 forms a front side end surface 63p. The back side end surface 63n exists on the back side Dpn with respect to the front side end surface 63p. Furthermore, of the pair of front and back end surfaces 64, one of the front and back end surfaces 64 forms the front end surface 64f, and the other front and back end surface 64 forms the back end surface 64b. The front end surface 64f exists on the front side Dcf with respect to the back end surface 64b. The back side end surface 63n and the front side end surface 63p are parallel. Furthermore, the front end surface 64f and the back end surface 64b are parallel. Therefore, as illustrated in
As illustrated in
As illustrated in
The rotating blade 50 of the present embodiment has, for example, three blade channels 71 formed therein. Of these three blade channels 71, the blade channel 71 on the foremost side Dwf is the first blade channel 71a, the blade channel 71 adjacent to the first blade channel 71a on the back side Dwb is the second blade channel 71b, and the blade channel 71 that is adjacent to the second blade channel 71b on the back side Dwb is the third blade channel 71c. The third blade channel 71c is opened at the end of the reverse gas path side Dha in the blade height direction Dwh of the blade base 92. The second blade channel 71b and the third blade channel 71c communicate at a portion on the gas path side Dwhp in the blade height direction Dwh. Furthermore, the second blade channel 71b and the first blade channel 71a communicate at a portion on the reverse gas path side Dwha in the blade height direction Dwh. A plurality of blades surface discharge channels 72 that open to the outer surface of the blade body 51 are formed in the blade channel 71. For example, a plurality of blade surface discharge channels 72 that extend from the third blade channel 71c to the back side Dwb and that open to the outer surface of the blade body 51 are formed in the third blade channel 71c. Furthermore, a plurality of blade surface discharge channels 72 that extend from the first blade channel 71a to the front side Dwf and that open to the outer surface of the blade body 51 are formed in the first blade channel 71a.
The blade body 51 is convection cooled by a process where the cooling air Ac flows through the blade channel 71. Furthermore, the cooling air Ac that flows into the blade channel 71 flows into the blade surface discharge channel 72 and flows out from the blade surface discharge channel 72 into the combustion gas channel 49. Therefore, the leading edge 52 and the trailing edge 53 and the like of the blade body 51 are cooled by a process where the cooling air Ac flows through the blade surface discharge channel 72. Furthermore, a portion of the cooling air Ac that flows from the blade surface discharge channel 72 into the combustion gas channel 49 plays a role of partially covering the surface of the blade body 51 as film air.
A platform channel 81 that extends in the platform 60 in the direction along the gas path surface 61 is formed in the platform 60. As illustrated in
The back side platform channel 81n has an intake channel 82n, a side end channel 83n, a serpentine first channel 84n, and a serpentine second channel 85n.
The intake channel 82n extends from the inner surface of the back side Dpn of the inner surface of the first blade channel 71a to a position of the back side end surface 63n on the back side Dpn. The side end channel 83n extends from the end of the back side Dpn of the intake channel 82n to the back side Dwb along the back side end surface 63n. The serpentine first channel 84n extends from the end on the back side Dwb of the side end channel 83n to the front side Dpp. The serpentine second channel 85n extends from the end of the front side Dpp of the serpentine first channel 84n to the back side Dpn. The serpentine second channel 85n opens on the back side end surface 63n of the platform 60. The serpentine first channel 84n and the serpentine second channel 85n both extend in the direction along the back end surface 64b. The serpentine first channel 84n and the serpentine second channel 85n both extend in the direction along the back end surface 64b. Note that in the present application, the phrase “two channels are aligned in the perspective direction with respect to the end surface” indicates that the distance from the end surfaces of the two channels are mutually different and a portion of the two channels are overlapping as seen from the perspective direction with respect to the end surface. The serpentine second channel 85n is located on the side closer to the back end surface 64b than the serpentine first channel 84n, and forms the outside channel. Furthermore, the serpentine first channel 84n is located on the side closer to the back end surface 64b than the serpentine second channel 85n, and forms the inside channel. The serpentine first channel 84n and the serpentine second channel 85n mutually communicate at the front side Dpp. Therefore, one serpentine channel that zigzags in a direction along the back end surface 64b is formed by the serpentine first channel 84n and the serpentine second channel 85n. Note, the back end surface 64b of the platform that is the end plate forms a partial end surface with respect to the serpentine first channel 84n and the serpentine second channel 85n.
The front side platform channel 81p has an intake channel 82p, a serpentine first channel 83p, a serpentine second channel 84p, and a serpentine third channel 85p.
The intake channel 82p extends from the inner surface on the front side Dpp of the inner surface of the first blade channel 71a to the front side Dpp. The serpentine first channel 83p extends from the end of the front side Dpp of the intake channel 82p toward the back side Dwb. The serpentine second channel 84p extends from the end of the back side Dwb of the serpentine first channel 83p to the front side Dwf. The serpentine third channel 85p extends from the end of the front side Dwf of the serpentine second channel 84p to the back side Dwb. The serpentine third channel 85p opens on the back end surface 64b of the platform. The serpentine first channel 83p, the serpentine second channel 84p, and the serpentine third channel 85p all extend in the direction along the front side end surface 63p. The serpentine first channel 83p, the serpentine second channel 84p, and the serpentine third channel 85p are aligned in the perspective direction with respect to the front side end surface 63p. The serpentine third channel 85p is located on the side closer to the front side end surface 63p than the serpentine first channel 83p and the second serpentine channel, and forms the outside channel. Furthermore, the serpentine second channel 84p is located closer to the far side with respect to the front side end surface 63p than the serpentine third channel 85p, and forms the inside channel. The serpentine first channel 83p is located closer to the far side with respect to the front side end surface 63p than the serpentine second channel 84p, and forms the inside channel. The serpentine first channel 83p and the serpentine second channel 84p mutually communicate on the back side Dwb. Furthermore, the serpentine second channel 84p and the serpentine third channel 85p mutually communicate on each of the front side Dwf ends. Therefore, one serpentine channel that zigzags in a direction along the front side end surface 63b is formed by the serpentine first channel 83p, the serpentine second channel 84p, and the serpentine third channel 85p, Note, the front side end surface 63p of the platform 60 that is the end plate forms a partial end surface with respect to the serpentine first channel 83p, the serpentine second channel 84p, and the serpentine third channel 85p.
Furthermore, a side end skirt hole 75n, hack side first skirt hole 76n, hack side second skirt hole 77n, front side first skirt hole 75p, front side second skirt hole 76p, and front side third skirt hole 77p are formed in the platform 60,
The side end skirt hole 75n communicates with the side end channel 83n in the platform channel 81. The side end skirt hole 75n extends from the side end channel 83n to the reverse gas path side Dwha, and opens at the reverse gas path surface 62 of the platform 60. The back side first skirt hole 76n communicates with the serpentine first channel 84n in the back side platform channel 81n. The back side first skirt hole 76n extends from the serpentine first channel 84n to the back side Dwb, and opens on the back end surface 64b of the platform 60. The back side second skirt hole 77n communicates with the serpentine second channel 85n in the back side platform channel 81n. The back side second skirt hole 77n extends from the serpentine second channel 85n to the back side Dwb, and opens on the back end surface 64b of the platform 60. The front side first skirt hole 75p communicates with the serpentine first channel 83p in the front side platform channel 81p. The front side first skirt hole 75p extends from the serpentine first channel 83p to the front side Dpp, and opens on the front side end surface 63p of the platform 60. The front side second skirt hole 76p communicates with the serpentine second channel 84p in the front side platform channel 81p. The front side second skirt hole 76p extends from the serpentine second channel 84p to the front side Dpp, and opens on the front side end surface 63p of the platform 60. The front side third skirt hole 77p communicates with the serpentine third channel 85p in the front side platform channel 81p. The front side third skirt hole 77p extends from the serpentine third channel 85p to the reverse gas path side Dwha, and opens at the reverse gas path surface 62 of the platform 60. The openings of the skirt holes in the platform 60 are blocked by plugs 78.
Note that the side end skirt hole 75n opens at the reverse gas path surface 62 of the platform 60. The side end skirt hole 75n extends from the side end channel 83n to the back side Dpn, and opens at the back side end surface 63n of the platform 60. Furthermore, herein, the front side third skirt hole 77p opens at the reverse gas path surface 62 of the platform 60. However, the front side third skirt hole 77p extends from the serpentine third channel 85p in the front side platform channel 81p to the front side Dpp, and opens on the front side end surface 63p of the platform 60.
As illustrated in
Although not illustrated in the drawings, similar to the front side first skirt hole 75p, the front side second skirt hole 76p includes a first extending part that extends from the serpentine second channel 84p in the front side platform channel 81p to the reverse gas path side Dwha, and a second extending part that extends from the end portion of the reverse gas path side Dwha in the first extending part to the front side Dpp and opens at the front side end surface 63p. Similar to the second extending part 75pb of the front side first skirt hole 75p, this second extending part also passes through the reverse gas path side Dwha with respect to the serpentine third channel 85p in the front side platform channel 81p. Therefore, as seen from the blade height direction Dwh, as illustrated in
Although not illustrated in the drawings, the hack side first skirt hole 76n includes a first extending part that extends from the serpentine first channel 84n in the hack side platform channel 81n to the reverse gas path side Dwha, and a second extending part that extends from the end portion of the reverse gas path side Dwha in the first extending part to the back side Dwb and opens at the hack end surface 64b. The second extending part passes through the reverse gas path side Dwha with respect to the serpentine second channel 85n in the back side platform channel 81n. Therefore, as seen from the blade height direction Dwh, as illustrated in
Next, the manufacturing method of the rotating blade 50 described above is described by the following the flowchart shown in
First, an intermediate product of the rotating blade 50 is formed by casting (S1: intermediate product forming step). In the intermediate product forming step (S1), a mold forming step (S2), core forming step (S3), casting step (S4), and core dissolving step (S5) are performed.
In the mold forming step (S2), a mold is formed with an internal space that matches the external shape of the rotating blade 50. In the mold forming step (S2), the mold is formed by a lost wax method, for example. In the lost wax method, first a wax model that reproduces the outer shape of the rotating blade 50 is formed. Next, the wax model is placed in a slurry containing refractory powder or the like, and then the slurry is dried. Furthermore, the wax model is removed from the slurry after drying to form a mold.
In the core forming step (S3), the blade channel core with an outer shape that matches the shape of the blade channel 71, a platform channel core with an outer shape that matches the shape of the platform channel 81, and a skirt core with an outer shape that matches the shape of the skirt holes are formed. The platform channel core includes a front side platform channel core with an outer shape that matches the shape of the front side platform channel 81p and a back side platform channel core with an outer shade that matches the back side platform channel 81n.
The skirt core includes a side end skirt core with an outer shape that matches the shape of the side end skirt hole 75n, a back side first skirt core that matches the shape of the back side first skirt hole 76n, and a back side second skirt core with an outer shape that matches the shape of the back side second skirt hole 77n. These skirt cores are integrally formed with the back side platform channel core. Furthermore, the skirt core includes a front side first skirt core with an outer shape that matches the shape of the front side first skirt hole 75p, a front side second skirt core with an outer shape that matches the shape of the front side second skirt hole 76p, and a front side third skirt core with an outer shape that matches the shape of the front side third skirt hole 77p.
These skirt cores are integrally formed with the front side platform channel core. The cores are all formed of a ceramic such as alumina, and the like. The core forming step (S3) can be performed in parallel with the mold forming step (S2), and can be performed before or after the mold forming step (S2).
In the casting step (S4), as illustrated in
The molten metal is a melted material of a nickel based alloy or the like with high heat resistance, for example. A core holding hole 95a where the end portion of the skirt core 98 is inserted is formed in the mold 95, with a recess on the outer surface side from the inner surface. The end portion of the skirt core 98 is inserted into the core holding hole 95a. Therefore, the skirt core 98 is held in the mold 95. The platform channel core 97 is integrated with the skirt core 98 as described above. Therefore, the platform channel core 97 is held in the mold 95 through the skirt core 98. In other words, the skirt core 98 determines the position of the platform channel core 97 in the mold 95, and plays a role in holding this position.
The core dissolving step (S5) is performed after the molten metal that was injected into the mold 95 hardens. In the core dissolving step (S5), the ceramic cores are dissolved by an alkaline aqueous solution. At this time, the skirt holes formed by each of the skirt cores guide the alkaline aqueous solution to the platform channel formed by the platform channel core, and also play a role in discharging the alkaline aqueous solution to the outside.
This completes the intermediate product forming step (S1), and an intermediate product of the rotating blade 50 is achieved.
Next, the openings of the core holes in the end surface of the platform 60 are blocked by plugs 78 (S6: sealing step). In the sealing step (S6), a lower hole is formed by a mechanical process or the like in an attachment portion for the plug 78 in the platform 60, and a plug 78 is inserted into the lower hole. Furthermore, the plug 78 is joined by welding or the like to the platform 60. Note that the inner diameter of the lower hole is normally formed to be larger than the inner diameter of the core hole.
Note that if the blade channel 71 and the platform channel 81 that are formed in the intermediate product are not communicating by a communication hole that allows communication between the blade channel 71 and the platform channel 81 is formed by an electrolytic process or an electric discharge process or the like before or after the sealing step (S6).
Next, a finishing staff is performed on the intermediate product that has completed the sealing step (S6) to complete the rotating blade 50 (S7: finishing step). During the finishing step (S7), the outer surface of the intermediate product is polished. Furthermore, if necessary, a heat resistant coating is applied to the outer surface of the intermediate product.
Next, the effect of the rotating blade 50 of the present embodiment will be described. First, a rotating blade 50z of a comparative example is described.
As illustrated in
Similar to the serpentine first channel 83p of the present embodiment illustrated in
The tip end of the blade body 51 of the moving blade 50 is a free end, and the blade body 51 is subjected to centrifugal force as well as force from the combustion gas. On the other hand, the shaft attachment part 90 of the rotating blade 50 is attached to the rotor shaft 42 (refer to
Furthermore, the stress is easily concentrated near the opening. In addition, if an opening for the skirt hole 75z is formed in the curved surface, a portion is formed where the angle α formed between this curved surface and the inner circumferential surface of the skirt hole 75z is an acute angle, and even higher stress will occur in this portion.
Therefore, with the rotating blade 50z of the comparative example, the region proximal to the opening of the skirt hole 75z is easily damaged.
On the other hand, with the present embodiment, as illustrated in
Furthermore, with the present embodiment, the cooling air that flows through the serpentine first channel 83p passes through the front side first skirt hole 75p and the through hole 79 of the plug 78, and is discharged from the front side end surface 63p of the platform 60. In other words, with the present embodiment, the front side first skirt hole 75p is used as an air channel through which the cooling air Ac passes. The cooling air Ac discharged from the front side end surface 63p of the platform 60 cools the front side end surface 63p and also cools the back side end surface 63n of the other vanes that are adjacent to the front side Dpp of the vanes. Therefore, with the present embodiment, the front side end surface 63p of the platform 60 cooled more than with the comparative example. Furthermore, with the present embodiment, the flow of cooling air Ac discharged from the front side end surface 63p can be appropriately adjusted by appropriately adjusting the inner diameter of the through hole 79 of the plug 78. Therefore, with this embodiment, the amount of cooling air that is used can be controlled while appropriately cooling the front side end surface 63p.
Furthermore, similar to the front side first skirt hole 75p, the front side second skirt hole 76p of the present embodiment opens at the front side end surface 63p of the platform 60. Therefore, damage near the opening of the front side second skirt hole 76p can be suppressed, and the front side end surface 63p of the platform 60 can be cooled. Furthermore, the back side first skirt hole 76n of the present embodiment opens at the back end surface 64b of the platform 60. Therefore, damage near the opening of the back side first skirt hole 76n can be suppressed, and the back end surface 64b of the platform 60 can be cooled.
As described above, with the present embodiment, the damage to the rotating blade 50 can be suppressed in conjunction with formation of the skirt holes. Furthermore, with the present embodiment, a portion of the end surface of the platform 60 can be cooled.
Note that with the present embodiment, the back side platform channel 81n has a serpentine channel. However, the back side platform channel 81n does not necessity form a serpentine channel. Furthermore, with the present embodiment, the back side Dwb portion of the back side platform channel 81n forms a serpentine channel. However, it is also acceptable for the front side Dwf portion of the back side platform channel 81n as well, or for only the front side Dwf portion of the back side platform channel 81n to form a serpentine channel. The serpentine channel of the back side platform channel 81n may zigzag in a direction along the back side end surface 63n and the front end surface 64f of the platform 60. In this case, the sheet hole that communicates with the inside channel which is a portion of the serpentine channel is open at the back side end surface 63n or the front end surface 64f. Furthermore, the serpentine channel in the front side platform channel 81p of the present embodiment zigzags in a direction along the front side end surface 63p. However, the serpentine channel of the front side platform channel 81p may zigzag in a direction along the back end surface 64b and the front end surface 64f of the platform 60. In this case, the sheet hole that communicates with the inside channel which is a portion of the serpentine channel is open at the front end surface 64f or the back end surface 64b.
First Variation of the Rotating Blade
A first variation of the rotating blade according to the embodiment described above will be described by referring to
With the rotating blade 50a of the present variation, the opening of the sheet hole 75p in the partial end surface (front side end surface) 63p of the platform 60 is not blocked by a plug 78. Therefore, with the present variation, the partial end surface 63p of the platform 60 can be better cooled.
Note that if the partial end surface 63p of the platform 60 does not need to be cooled by the cooling air Ac discharged from the partial end surface 63p, the opening of the skirt hole 75p in the partial end surface 63p can be blocked by a plug where a through hole 79 is not formed.
Second Variation of the Rotating Blade
A second variation of the rotating blade according to the aforementioned embodiment is described while referring to
As illustrated in
The skirt hole 75pc in the rotating blade 50b of the present variation has an tilted hole part 75pd that gradually extends linearly from the inside channel 83p in the serpentine channel to the side near the side of the reverse gas path surface 62 when approaching the partial end side 63p. The tilted hole part 75pd opens at the partial end surface 63p.
The air channel formed in the rotating blade may be inspected by inserting a borescope inside.
With this variation, the borescope can easily be inserted into the inside channel 83p from the skirt hole 75pc. Therefore, with this variation, inspection of the inside channel 83p can easily be performed.
Note that with the present variation, similar to the first variation, the opening of the skirt hole 75pc in the partial end surface 63p is not required to be plugged by the plug. Furthermore, with the present variation, a through hole 79 is not necessarily formed in the plug 78.
Third Variation of the Rotating Blade
A third variation of the rotating blade according to the embodiment described above will be described while referencing
Similar to the skirt hole 75pc of the second variation, the skirt hole 75pe in the rotating blade 50c of the present variation is a hole that extends linearly from the inside channel 83p in the serpentine channel toward the partial end surface 63p of the platform 60. However, unlike the skirt hole 75pc of the second variation, the skirt hole 75pe of the present variation is a hole that extends linearly from the inside channel 83p in the serpentine channel toward the partial end surface 63p of the platform 60 essentially parallel to the gas path surface 61.
With the present variation, the skirt hole 75pe is essentially parallel to the gas path surface 61, and therefore the inside channel 83p in the serpentine channel has an expanded part 83pe that is expanded toward the reverse gas path side Dwha. The skirt hole 75pe of the present variation is a hole that extends linearly from the inside surface of the partial end surface 63p of the inner surface of the expanded part 83pe toward the partial end surface 63p of the platform 60, essentially parallel to the gas path surface 61.
With this variation, similar to the second variation, a borescope can easily be inserted into the inside channel 83p from the skirt hole 75pe. Therefore, with this variation, inspection of the inside channel 83p can easily be performed.
Note that with the present variation as well, similar to the first variation, the opening of the skirt hole 75pe in the partial end surface 63p is not required to be plugged by the plug. Furthermore, with the present variation, a through hole 79 is not necessarily formed in the plug 78.
Furthermore, the inside channel 83p of the aforementioned embodiment and the aforementioned second variation may have the expanded part 83pe of the present variation. If the inside channel 83p of the aforementioned embodiment has an expanded portion 83pe, the first extended part 75pc of the skirt hole 75p extends from the expanded part 83pe to the reverse gas path side Dwha. If the inside channel 83p of the aforementioned second variation has an expanded portion 83pe, the tilted hole part 75pd of the skirt hole 75pc extends from the expanded part 83pe.
Fourth Variation of the Rotating Blade
A fourth variation of the rotating blade according to the embodiment described above will be described while referring to
The platform 60 in the rotating blade 50d of the present variation has a first front side platform channel 81pa and a second front side platform channel 81pb as the front side platform channel. The first front side platform channel 81pa has an intake channel 82pa, side end channel 83pa, and a discharge channel 84pa. The second front side platform channel 81pb has an intake channel 82pb, side end channel 83pb, and a discharge channel 84pb.
The intake channel 82pa of the first front side platform channel 81pa extends from the inner surface of the front side Dpp of the inner surface of the first blade channel 71a to a position near the front side end surface 63p on the front side Dpp. The side end channel 83pa of the first front side platform channel 81pa extends from the end on the front side Dpp of the intake channel 82pa to the back side Dwb along the front side end surface 63p. The intake channel 84pa of the first front side platform channel 81pa extends from the end on the back side Dwb of the side end channel 83pa to the back side Dpp, and communicates with the third blade channel 71c. The intake channel 82pb of the first front side platform channel 81pb extends from the inner surface of the front side Dpp of the inner surface of the second blade channel 71b to the front side Dpp. The side end channel 83pb of the second front side platform channel 81pb extends from the end on the front side Dpp of the intake channel 82pb to the back side Dwb along the front side end surface 63p. The intake channel 84pb of the second front side platform channel 81pb extends from the end on the back side Dwb of the side end channel 83pb to the back side Dpp, and communicates with the third blade channel 71c. The side end channel 83pb of the second front side platform channel 81pb and the side end channel 83pa of the first front side platform channel 81pa both extend in the direction along the front side end surface 63p, as described above. Furthermore, the side end channel 83pb of the second front side platform channel 81pb and the side end channel 83pa of the first front side platform channel 81pa are aligned in a perspective direction with respect to the front side end surface 63p. The side end channel 83pa of the first front side platform channel 81pa is positioned on the side closer to the front side end surface 63p than the side end channel 83pb of the second front side platform channel 81pb, and forms the outside channel. Furthermore, the side end channel 83pb of the second front side platform channel 81pb is positioned on the side farther to the side end channel 83pa of the first front side platform channel 81pa than the front side end surface 63p, and forms the inside channel. Note that the front side end channel 63p of the platform 60 which is the end plate forms the partial end surface for the side end channel 83pa of the first front side platform channel 81pa and the side end channel 83pb of the second front side platform channel 81pb.
Furthermore, a side end skirt hole 76p and a front side skirt hole 77p are formed in the platform 60.
The side end skirt hole 77p communicates with the side end channel 83pa in the first front side platform channel 81pa. The side end skirt hole 77p extends from the side end channel 83pa to the reverse gas path side Dwha, and opens at the reverse gas path surface 62 of the platform 60. The front side skirt hole 76p communicates with the side end channel 83pb in the second front side platform channel 81pb. The front side skirt hole 76p extends from the side end channel 83pb of the second front side platform channel 81pb to the front side Dpp, passes through the reverse gas path side Dwha to the side end channel 83pa of the first front side platform channel 81pa, and opens at the front side end surface 63p of the platform 60. Therefore, as seen from the blade height direction Dwh, the front side skirt hole 76p appears to intersect with the side end channel 83pa of the first front side platform channel 81pa. The openings of the skirt holes 76p, 77p are locked by plugs 78.
As described above, if two channels are aligned in the perspective direction with respect to the end surface, the two channels do not necessarily form one serpentine channel, and the skirt holes may be formed to extend from the inside channel of the two channels toward the end surface.
Note that the present variation is an example where the front side platform channel 81p of the first embodiment was changed, but the back side platform channel 81n in the first embodiment may be changed similar to the variation described above. Furthermore, with the present variation, similar to the first variation, the opening of the skirt hole is not required to be plugged by the plug 78. Furthermore, with the present variation, the form of the skirt hole can be the form of the second variation or the third variation.
A second embodiment of the rotating blade will be described with reference to
As illustrated in
As illustrated in
Although not illustrated in the drawings, similar to the rotating blade 50 of the first embodiment, the platform channel and the skirt holes are formed in the platform 160.
The tip shroud 110 has a plate shaped shroud body 120 that extends from the end portion of the blade height direction Dwh in a direction with a perpendicular component to the blade height direction Dwh, a first tip fin 111 provided in the shroud body 120, and a second tip fin 112.
A gas path surface 121 facing the combustion gas channel 49 side, a reverse gas path surface 122 with a back matching relationship to the gas path surface 121, and end surfaces 123, 124 are formed in the shroud body 120. The gas path surface 121 of the shroud body 120 is a surface that extends in a direction having a perpendicular component with respect to the blade height direction Dwh. Herein, in the shroud body 120, the side where the gas path surface 121 exists with respect to the reverse gas path surface 122 in the blade height direction Dwh is the gas path side Dwhp, and the opposite side is the reverse gas path side Dwha. However, in a condition where the rotating blade 100 is attached to the rotor shaft, the gas path side Dwhp in the platform 160 is the radial direction outer side Dro, and the reverse gas path side Dwha is the radial direction inward side Dri, but the gas path side Dwhp in the shroud body 120 is the radial direction inward side Dri, and the reverse gas path side Dwha is the radial direction outward side Dro.
The first tip fin 111 and the second tip fin 112 both protrude from the reverse gas path surface 122 of the shroud body 120 to the reverse gas path side Dwha. The first tip fin 111 and the second tip fin 112 both extend in the circumferential direction Dc as illustrated in
The end surfaces 123, 124 of the shroud body 120 include a pair of front and back end surfaces 124 that face mutually opposing sides in the blade chord direction Dwc, and a pair of side end surfaces 123 facing mutually opposing sides in the width direction Dwp having a component perpendicular to the blade height direction Dwh and the blade chord direction Dwc. The pair of front and back end surfaces 124 both extend in the direction having a perpendicular component to the blade chord direction Dwc, and connect to the gas path surface 121. Of the pair of front and back end surfaces 124, one of the front and back end surfaces 124 forms the front end surface 124f, and the other front and back end surface 124 forms the back end surface 124b. The front end surface 124f exists on the front side Dwf with respect to the back end surface 124b. The pair of front and back end surfaces 124 extends in the circumferential direction Dc in a condition where the rotating blade 100 is attached to the rotor shaft.
Of the pair of side end surfaces 123, a first side end surface 123 forms a back side end surface 123n, and the second side end surface 123 forms a front side end surface 123p. The back side end surface 123n exists on the back side Dpn with respect to the front side end surface 123p. The back side end surface 123n has a back side first end surface 123na, a back side second end surface 123nb, and a back side third end surface 123nc. Furthermore, the front side end surface 123p has a front side first end surface 123pa, a front side second end surface 123pb, and a front side third end surface 123pc. The back side first end surface 123na and the front side first end surface 123pa are mutually parallel. The back side second end surface 123nb and the front side second end surface 123pb are mutually parallel. The back side third end surface 123nc and the front side third end surface 123pc are mutually parallel. The back side first end surface 123na and the front side first end surface 123pa both extend essentially in the blade chord direction Dwc. The back side second end surface 123nb extends from the end on the back side Dwh of the back side first end surface 123na to essentially the back side Dpn. The back side second end surface 123pb extends from the end on the back side Dwh of the front side first end surface 123pa to essentially the front side Dpn. The back side third end surface 123nc extends from the end on the back side Dpn of the back side second end surface 123nb to essentially the blade chord direction Dwc. The back side third end surface 123pc extends from the end on the back side Dpn of the front side second end surface 123pb to essentially the blade chord direction Dwc. Note that the phrase “extending essentially in the blade chord direction Dwc” refers to a condition where of the blade chord direction Dwc component, blade height direction Dwh component, and the width direction Dwp component, the blade chord direction Dwc component is the largest.
As illustrated in
The shroud channel 181 includes a first back side shroud channel 182n, a second back side shroud channel 183n, a first front side shroud channel 182p, and a second front side shroud channel 186p.
The first back side shroud channel 182n communicates with the second of the second blade channels 171b of the four blade channels 171 from the front side Dwf. The first back side shroud channel 182n extends linearly from the second blade channel 171b toward the back side first end surface 123na, and opens at the back side first end surface 123na.
The second back side shroud channel 183n has a serpentine first channel 184n and a serpentine second channel 185n.
The serpentine first channel 184n and the serpentine second channel 185n both extend in the direction along the back end surface 124b. The serpentine first channel 184n and the serpentine second channel 185n both extend in the direction along the back end surface 124b. The serpentine second channel 185n is located on the side closer to the hack end surface 124b than the serpentine first channel 184n, and forms the outside channel. Furthermore, the serpentine first channel 184n is located on the side closer to the hack end surface 124b than the serpentine second channel 185n, and forms the inside channel. The serpentine first channel 184n and the serpentine second channel 185n mutually communicate at the back side Dpn. Therefore, one serpentine channel that zigzags in a direction along the back end surface 124b is formed by the serpentine first channel 184n and the serpentine second channel 185n. The serpentine second channel 185n opens at the back end surface 124b of the shroud body 120. Note, the back end surface 124b of the tip shroud 110 that is the end plate forms a partial end surface with respect to the serpentine first channel 184n and the serpentine second channel 185n. The end of the front side Dpp in the serpentine first channel 184n communicates with the fourth blade channel 171d on the back most side Dwb of the four blade channels 171.
The first front side shroud channel 182p has a serpentine first channel 183p, a serpentine second channel 184p, and a serpentine third channel 185p.
The serpentine first channel 183p, the serpentine second channel 184p, and the serpentine third channel 185p all extend in the direction along the front end surface 124f. The serpentine first channel 183p, the serpentine second channel 184p, and the serpentine third channel 185p are aligned in the perspective direction with respect to the front surface 124f. The serpentine first channel 183p is located on the side closer to the front end surface 124f than the serpentine second channel 184p and the serpentine third channel 185p, and forms the outside channel. Furthermore, the serpentine second channel 184p is located closer to the far side with respect to the front end surface 124f than the serpentine first channel 183p, and forms the inside channel. The serpentine third channel 185p is located to the far side with respect to the front end surface 124f than the serpentine second channel 184p, and forms the inside channel. The end of the back side Dpn in the serpentine first channel 183p communicates with the first blade channel 171a on the back most side Dwf of the four blade channels 171. The serpentine first channel 183p and the serpentine second channel 184p communicate with the corresponding end of the front side Dpp. Furthermore, the serpentine second channel 184p and the serpentine third channel 185p mutually communicate on each of the back side Dpn ends. Therefore, one serpentine channel that zigzags in a direction along the front side end surface 124f is formed by the serpentine first channel 183p, the serpentine second channel 184p, and the serpentine third channel 185p. The serpentine third channel 185p opens at the front side first end surface 123pa of the shroud body 120. Note, the front end surface 124f of the tip shroud 110 that is the end plate forms a partial end surface with respect to the serpentine first channel 183p, serpentine second channel 184p, and the serpentine third channel 185p.
The second front side shroud channel 186p communicates with the third of the third blade channels 171c of the four blade channels 171 from the front side Dwf. The second front side shroud channel 186p extends linearly from the third blade channel 171c toward the front side second end surface 123pb, and opens at the front side second end surface 123pb.
The skirt hole 175 has a back side first skirt hole 176n, a back side second skirt hole 177n, a front side first skirt hole 176p, a front side second skirt hole 177p, and front side third skirt hole 178p.
The back side first skirt hole 176n communicates with the serpentine first channel 184n in the second back side shroud channel 183n. The back side first skirt hole 176n extends from the serpentine first channel 184n to the back side Dwh, and opens on the back end surface 124b of the shroud body 120. The back side first skirt hole 176n passes to the reverse gas path side Dwha of the serpentine second channel 185n in the second back side shroud channel 183n. Therefore, as seen from the blade height direction Dwh, the back side first skirt hole 176n appears to intersect with the serpentine second channel 185n in the second back side shroud channel 183n.
The back side second skirt hole 177n communicates with the serpentine second channel 185n in the second back side shroud channel 183n. The back side first skirt hole 177n extends from the serpentine second channel 185n to the back side Dwh, and opens on the back end surface 124b of the shroud body 120.
The front side first skirt hole 176p communicates with the serpentine first channel 183p in the first front side shroud channel 182p. The front side first skirt hole 176p extends from the serpentine first channel 183p to the front side Dwf, and opens on the front end surface 124f of the shroud body 120.
The front side second skirt hole 177p communicates with the serpentine second channel 184p in the first front side shroud channel 182p. The front side second skirt hole 177p extends from the serpentine second channel 184p to the front side Dwf, and opens on the front end surface 124f of the shroud body 120. The front side second skirt hole 177p passes to the reverse gas path side Dwha of the serpentine first channel 183p in the first front side shroud channel 182p. Therefore, as seen from the blade height direction Dwh, the front side second skirt hole 177p appears to intersect with the serpentine first channel 183p in the first front side shroud channel 182p.
The front side third skirt hole 178p communicates with the serpentine third channel 185p in the first front side shroud channel 182p. The front side third skirt hole 178p extends from the serpentine third channel 185p to the front side Dwf, and opens on the front end surface 124f of the shroud body 120. The front side third skirt hole 178p passes to the reverse gas path side Dwha of the serpentine first channel 183p and the serpentine second channel 184p in the first front side shroud channel 182p. Therefore, as seen from the blade height direction Dwh, the front side third skirt hole 178p appears to intersect with the serpentine first channel 183p and the serpentine second channel 184p in the first front side shroud channel 182p.
The opening of the shroud holds 175 are plugged by plugs 178 where a through hole (not illustrated in the drawings) is formed.
Herein, even if the shroud hole 175 that is formed in the shroud body 120 is open at the reverse gas path surface 122 of the shroud body 120, the opening is plugged by the plug. The reverse gas path surface 122 of the shroud body 120 faces the radial direction outer side in a condition where the rotating blade 100 is attached to the rotor shaft. The centrifugal force toward the outer side in the radial direction acts on the plug when the gas turbine rotor rotates. Furthermore, a plug that plugs the opening in the reverse gas path surface 122 is easily removed to the outer side in the radial direction by the centrifugal force.
On the other hand, with the present embodiment, the shroud hole 175 that is formed in the shroud body 120 is open at the partial end surface 124 of the shroud body 120. Therefore, when the gas turbine rotates and the centrifugal force acts toward the outer side in the radial direction with respect to the plug 178 to move the plug 178 to the outer side in the radial direction, the plug 178 is received by the inner surface of the shroud hole 175 and therefore removing the plug from the shroud hole 175 is difficult. Therefore, with the present embodiment, damage to the tip shroud 110 can be suppressed.
Furthermore, with the present embodiment, the partial end surface 124 can be cooled by the cooling air discharged from the partial end surface 124 of the shroud body 120.
Note, similar to the opening of the shroud hole of the platform 60 in the first variation, the opening of the shroud hole 175 of the shroud body 120 in the present embodiment is not necessarily plugged by the plug.
Furthermore, similar to the shroud hole of the platform 60 in the first embodiment, the skirt hole 175 of the shroud body 120 of the present embodiment may include the first extended part that extends from the inside channel in the serpentine channel to the reverse gas path side Dwha and the second extended part that extends from the in part of the reverse gas path side Dwha in the first extending part toward the partial end surface 124 side and opens at the partially end surface 124. Furthermore, similar to the skirt hole of the platform 60 in the second variation, the skirt hole 175 of the shroud body 120 in the present embodiment may have an tilted hole part that gradually linearly extends to the side near the side of the reverse gas path surface 122 when moving from the inside channel in the serpentine channel toward the partial end surface 124. Furthermore, similar to the third variation, with the present embodiment, the inside channel in the serpentine channel can have an extended part that extends to the reverse gas path side Dwha, and the skirt hole can extend linearly from the inner surface of the partial end surface 124 side of the inner surface in the extended part toward the partially end surface 124 of the shroud body 120 essentially parallel to the gas path surface 121.
Furthermore, the aforementioned embodiments and variations all apply the present invention to a rotating blade. However, the present invention can be applied to a vane. In other words, similar to the aforementioned embodiments and variations, an inside channel, outside channel, and skirt hole can be formed in the outside shroud (end plate) or the inside shroud (end plate) of the vane.
According to one aspect of the present invention, the high stress that occurs in the blade can be suppressed.
| Number | Date | Country | Kind |
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| Filing Document | Filing Date | Country | Kind |
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| PCT/JP2016/080939 | 10/19/2016 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/069145 | 4/27/2017 | WO | A |
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