Method and structure for fixing rotor blades

Abstract

To exactly fix a rotor blade to a turbine rotor, to improve vibration resistance and attenuation performance, and to easily improve the reliability of the rotor blade.SOLUTION: A rotor blade fixing method of the present embodiment has a shim insertion step and a shim joining step, and fixes a rotor blade to a turbine rotor in which a blade implanting groove is formed so as to progress along an axial direction. In the shim insertion step, a shim is inserted into a clearance interposed between a blade implanting part and the blade implanting groove in the blade implanting groove into which the blade implanting part of the rotor blade is inserted. In the shim joining step, the shim inserted into the clearance is joined to the blade implanting part. Here, the shim includes a shim insertion part inserted into the clearance in the shim insertion step, and a shim joining part extending in a second extension direction orthogonal to a first extension direction in which the shim insertion part extends, and joined to the blade implanting part in the shim joining step.SELECTED DRAWING: Figure 3A

Description

Technical Field

[0001] Embodiments of the present invention relate to a method for fixing moving blades and a moving blade fixing structure.

Background Art

[0002] In the assembly of a turbine, when installing moving blades on a turbine rotor, for example, the blade insertion part of the moving blade is inserted into the blade insertion groove of the turbine rotor. The insertion type of the blade insertion part into the blade insertion groove includes a circumferential insertion type in which the blade insertion part is inserted in the circumferential direction of the turbine rotor, a radial insertion type in which the blade insertion part is inserted in the radial direction of the turbine rotor, and an axial insertion type in which the blade insertion part is inserted in the axial direction of the turbine rotor. The above insertion types are applied, for example, when installing the moving blades constituting the final stage turbine stage in the low-pressure part of a steam turbine on the turbine rotor to obtain sufficient strength and vibration resistance.

[0003] For moving blades with a long effective length, such as the moving blades constituting the final stage turbine stage in the low-pressure part of a steam turbine, improvement in vibration resistance and damping is required. For this reason, it has been proposed to configure the moving blades with a stitching structure in which the adjacent moving blades in the circumferential direction of the turbine rotor are in a connected state.

[0004] For example, it has been proposed to provide a tip connecting member such as a cover on the tip side of the moving blade. Also, it has been proposed to provide an intermediate connecting member such as an intermediate snubber or a lug between the blade insertion part and the tip part of the moving blade. The lug, which is an intermediate connecting member, is a protrusion, and a connecting structure is configured by interposing a sleeve between the lugs of adjacent moving blades in the circumferential direction of the turbine rotor.

[0005] By employing a connecting structure, for example, it is possible to prevent the rotor blades from resonating during rated operation of a turbine, thereby improving vibration resistance and damping. The connecting structure is, for example, a full-circumference group connecting structure in which all of the multiple rotor blades arranged in the direction of rotation are connected, and the rotation of the turbine rotor generates an untwist force on the rotor blades, causing connecting members such as covers to come into contact and connect. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 4886735 [Patent Document 2] Japanese Patent Application Publication No. 4-214902 [Patent Document 3] Japanese Utility Model Publication No. 4-119392 [Patent Document 4] Japanese Patent Publication No. 2018-159232 [Overview of the project] [Problems that the invention aims to solve]

[0007] Of the implantation types described above, the axial insertion type, for example, is an axial entry type, and has a larger effective area for supporting the centrifugal force acting on the rotor blades than other implantation types. For this reason, in the axial insertion type, the stress applied to the portion of the turbine rotor where the rotor blades are implanted is relatively small.

[0008] However, in axial insertion type turbines, in order to smoothly insert the blade mounting portion of the rotor blade into the blade mounting groove formed in the turbine rotor, the blade mounting portion must be slightly smaller than the blade mounting groove. As a result, when the blade mounting portion is inserted into the blade mounting groove, a gap exists between the surface of the blade mounting groove and the surface of the blade mounting portion. Consequently, this gap can lead to insufficient fixing of the rotor blade, making it difficult to ensure adequate vibration resistance and damping.

[0009] Furthermore, the gap between the surface of the blade mounting groove and the surface of the blade mounting area can cause the rotor blades to tilt. For this reason, when a connecting structure is used to link adjacent rotor blades in the circumferential direction of the turbine rotor, it can be difficult to accurately confirm whether the connecting structure between the rotor blades is in the state designed.

[0010] Due to the circumstances described above, the rotor blades may not be sufficiently secured, making it difficult to effectively achieve vibration resistance and damping, and thus making it difficult to improve the reliability of the rotor blades.

[0011] Therefore, the problem that the present invention aims to solve is to provide a method and structure for fixing rotor blades that can accurately fix rotor blades to a turbine rotor, improve vibration resistance and damping, and easily improve the reliability of the rotor blades. [Means for solving the problem]

[0012] The blade fixing method of the embodiment comprises a shim insertion step and a shim joining step, and fixes the blade to a turbine rotor having blade mounting grooves formed along the axial direction. In the shim insertion step, a shim is inserted into the gap between the blade mounting portion and the blade mounting groove in the blade mounting groove into which the blade mounting portion of the blade is inserted. In the shim joining step, the shim inserted into the gap is joined to the blade mounting portion. Here, the shim includes a shim insertion portion that is inserted into the gap in the shim insertion step, and a shim joining portion that extends in a second extending direction perpendicular to the first extending direction in which the shim insertion portion extends, and is joined to the blade mounting portion in the shim joining step. The wing mounting section has a Christmas tree shape, including multiple hooks that protrude convexly from the ventral and dorsal sides of the control surface, and is configured to fit into the wing mounting groove. In the shim insertion process, the shim insertion section is inserted into the gaps located radially inward among the multiple hooks. . [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic cross-sectional view showing the overall configuration of the steam turbine in the first embodiment. [Figure 2] Figure 2 is a schematic perspective view showing an example of the structure of the portion of the steam turbine 1 of the first embodiment in which the rotor blades 50 are installed on the turbine rotor 30. [Figure 3A]FIG. 3A is an enlarged side view showing the blade fixing structure of the portion where the moving blade 50 is implanted in the rotor disk 31 of the turbine rotor 30 in the steam turbine 1 of the first embodiment. [Figure 3B] FIG. 3B is a cross-sectional view schematically showing the shim 80 in the steam turbine 1 of the first embodiment. [Figure 4A] FIG. 4A is a view showing the blade fixing structure of the portion where the moving blade 50 is implanted in the rotor disk 31 of the turbine rotor 30 in the steam turbine 1 of the second embodiment. [Figure 4B] FIG. 4B is a view showing the blade fixing structure of the portion where the moving blade 50 is implanted in the rotor disk 31 of the turbine rotor 30 in the steam turbine 1 of the second embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0014] <First Embodiment> [A] Steam Turbine 1 FIG. 1 is a cross-sectional view schematically showing the overall configuration of the steam turbine in the first embodiment. In FIG. 1, the vertical direction is the vertical direction z, the horizontal direction is the first horizontal direction x, the direction perpendicular to the paper surface is the second horizontal direction y orthogonal to the first horizontal direction x, and in FIG. 1, a longitudinal section (xz plane) along the vertical direction z and the first horizontal direction x is shown.

[0015] In the present embodiment, the steam turbine 1 is exemplified as a double-flow low-pressure turbine in which steam that has performed work in a high-pressure turbine (not shown) and an intermediate-pressure turbine (not shown) is supplied as a working medium.

[0016] The steam turbine 1 of the present embodiment has an external compartment 10, an internal compartment 20, and a turbine rotor 30.

[0017] In the present embodiment, the external compartment 10 of the steam turbine 1 houses the internal compartment 20 therein, and the internal compartment 20 houses the turbine rotor 30 therein. The turbine rotor 30 is rotatably supported by a bearing 301 such that the axis center line AX is along the first horizontal direction x.

[0018] The steam turbine 1 is a multi-stage axial-flow turbine, and a plurality of turbine stages 60 including stationary blades 40 and moving blades 50 are provided axially along the axial center line AX inside the inner chamber 20.

[0019] In the turbine stage 60, there are a plurality of stationary blades 40, and the plurality of stationary blades 40 are arranged in the rotational direction of the turbine rotor 30 between the diaphragm inner ring 41 and the diaphragm outer ring 43 to form the nozzle diaphragm 45.

[0020] In the turbine stage 60, there are a plurality of moving blades 50, and the plurality of moving blades 50 are arranged along the rotational direction of the turbine rotor 30. The moving blades 50 are implanted in a rotor disk 31 formed to protrude radially from the outer peripheral surface in the turbine rotor 30.

[0021] A steam supply pipe 70 is connected to the inner chamber 20 of the steam turbine 1, and steam is supplied as a working fluid from the outside of the outer chamber 10 to the steam supply pipe 70. The steam supplied to the steam supply pipe 70 sequentially flows through the plurality of turbine stages 60 inside the inner chamber 20. That is, the working fluid flows from the first-stage turbine stage 60 toward the last-stage turbine stage 60, expands in each turbine stage 60, and performs work. As a result, the turbine rotor 30 rotates with the axial center line AX as the rotation axis, and a generator (not shown) connected to the turbine rotor 30 generates electricity. The blade lengths (radial lengths) of the stationary blades 40 and the moving blades 50 are configured to gradually increase from the first-stage turbine stage 60 toward the last-stage turbine stage 60.

[0022] In the steam turbine 1, the steam that has passed through the last-stage turbine stage 60 is discharged from the lower end of the outer chamber 10 via the cone portion 12. The steam discharged from the outer chamber 10 is supplied to a condenser (not shown) connected to the steam turbine 1, and is condensed in the condenser to generate condensate.

[0023] [B] Moving blade 50 Figure 2 is a schematic perspective view showing an example of the structure of the portion of the steam turbine 1 of the first embodiment in which the rotor blades 50 are installed on the turbine rotor 30. In Figure 2, for example, a portion of the rotor blade row that comprises the rotor blades 50 constituting the final stage turbine stage 60 is shown.

[0024] As shown in Figure 2, multiple rotor blades 50 are installed on the rotor disk 31 of the turbine rotor 30 so as to be aligned in the rotational direction R.

[0025] Specifically, multiple blade stud grooves T30 extending along the axial direction (first horizontal direction x) are formed on the outer circumferential surface of the rotor disk 31. The multiple blade stud grooves T30 are formed spaced apart in the rotational direction R of the rotor disk 31.

[0026] In this embodiment, each of the multiple rotor blades 50 has a blade body portion 51, a blade mounting portion 52, a cover 61, and an intermediate snubber 62.

[0027] [B-1] Wing body part 51 The blade body 51 is, for example, a twisted blade that is twisted from the blade root to the blade tip, and is configured to generate an untwisted force when the turbine rotor 30 rotates.

[0028] [B-2] Wing implantation part 52 The wing mounting section 52 is provided at the root of the wing in the wing body section 51. The wing mounting section 52 is, for example, shaped like a Christmas tree and is inserted and fitted into the wing mounting groove T30 formed in the rotor disc 31 along the axial direction (first horizontal direction x). In other words, in this embodiment, the mounting method for embedding the rotor blade 50 into the rotor disc 31 is an axial insertion type.

[0029] [B-3] Cover 61 The cover 61 is provided at the wingtip of the wing body 51.

[0030] The cover 61 includes a leading-edge cover portion 611 and a trailing-edge cover portion 612. The leading-edge cover portion 611 protrudes axially from the dorsal surface S511 on the leading edge side of the wing body portion 51. In contrast, the trailing-edge cover portion 612 protrudes axially from the ventral surface S512 on the trailing edge side of the wing body portion 51.

[0031] Multiple rotor blades 50, aligned in the rotational direction R, are connected by the contact between the leading edge cover portion 611 and the trailing edge cover portion 612 due to the untwist force generated on the blade body portion 51.

[0032] [B-4] Intermediate Snubber 62 The intermediate snubber 62 is provided in the wing body 51 between the wing root and the wingtip. The intermediate snubber 62 includes a leading-edge intermediate snubber section 621 and a trailing-edge intermediate snubber section 622.

[0033] The leading-edge intermediate snubber portion 621 protrudes axially from the dorsal surface S511 on the leading edge side of the wing body portion 51. In contrast, the trailing-edge intermediate snubber portion 622 protrudes axially from the ventral surface S512 on the trailing edge side of the wing body portion 51.

[0034] Multiple rotor blades 50, aligned in the rotational direction R, are connected by the contact between the leading-edge intermediate snubber section 621 and the trailing-edge intermediate snubber section 622 due to the untwist force generated on the blade body 51.

[0035] [C] Fixed rotor blade structure Figure 3A is an enlarged side view of the blade fixing structure in the steam turbine 1 of the first embodiment, specifically the portion where the blades 50 are embedded in the rotor disk 31 of the turbine rotor 30. In Figure 3A, for example, the blade fixing structure for the blades 50 constituting the final stage turbine stage 60 is shown, illustrating the side view (yz plane) perpendicular to the axis centerline AX of the turbine rotor 30 (see Figure 1). In other words, in Figure 3A, the direction perpendicular to the plane of the paper is the axial direction along the axis centerline AX of the turbine rotor 30 (the first horizontal direction x in Figure 3A). Note that hatching is used in Figure 3A to identify each part.

[0036] As shown in Figure 3A, in the rotor blade fixing structure of this embodiment, the blade mounting portion 52 of the rotor blade 50 is inserted into a blade mounting groove T30 formed in the rotor disk 31 so as to extend along the axial direction. In this embodiment, the rotor blade 50 is fixed to the rotor disk 31 using shims 80.

[0037] Here, shims 80 are provided for each of the multiple hooks that protrude convexly on the ventral side (left side in Figure 3A) and dorsal side (right side in Figure 3A) of the wing implantation section 52.

[0038] Figure 3B is a schematic cross-sectional view showing a shim 80 in the steam turbine 1 of the first embodiment. Figure 3B shows an enlarged view of the portion of the turbine rotor 30 (see Figure 1) in which the shim 80 is installed. In Figure 3B, the lateral direction corresponds to the axial direction along the axis centerline AX of the turbine rotor 30 (see Figure 1).

[0039] As shown in Figure 3B, the shim 80 comprises a shim insertion portion 81 and a shim joining portion 82. The shim 80 is formed, for example, by bending a plate-like body of metal material to create the shim insertion portion 81 and the shim joining portion 82.

[0040] Of the shim 80, the shim insertion portion 81 is interposed between the blade mounting portion 52 of the rotor blade 50 and the blade mounting groove T30 when the blade mounting portion 52 of the rotor blade 50 is inserted into the blade mounting groove T30 of the rotor disk 31, and is inserted into a gap G that extends in the axial direction. Here, the gap G into which the shim insertion portion 81 is inserted is located, for example, on the radially inner side (lower side in Figures 3A and 3B) of the hook (see Figure 3A) of the blade mounting portion 52. The thickness of the shim insertion portion 81 is preferably slightly thinner than the thickness of the gap G.

[0041] In the shim 80, the shim joint 82 extends in a direction perpendicular to the direction in which the shim insertion portion 81 extends (first extension direction, transverse direction in Figure 3B) (second extension direction, longitudinal direction in Figure 3B). The shim joint 82 faces a surface along the radial direction (corresponding to the longitudinal direction in Figure 3B) in the wing implantation portion 52 and is joined to the wing implantation portion 52. Here, the shim joint 82 and the wing implantation portion 52 are joined via a welded joint 90.

[0042] [D] Moving blade fixing method The procedure for fixing the rotor blades 50 to the turbine rotor 30 (see Figure 1) will be explained below.

[0043] First, the blade mounting portion 52 of the rotor blade 50 is inserted axially into the blade mounting groove T30 that extends axially in the rotor disc 31 (see Figure 3A).

[0044] Next, in the blade mounting groove T30 into which the blade mounting portion 52 of the rotor blade 50 is inserted, a shim 80 is inserted into the gap G between the blade mounting portion 52 and the blade mounting groove T30 (shim insertion step). Here, as shown in Figure 3B, the shim insertion portion 81 that constitutes the shim 80 is inserted into the gap G.

[0045] Next, the shim 80 inserted into the gap G is joined to the wing implantation section 52 (shim joining process). Here, as shown in Figure 3B, the shim joint 82 constituting the shim 80 is joined to the wing implantation section 52. For example, by spot welding at multiple locations between the shim joint 82 and the wing implantation section 52, the shim joint 82 and the wing implantation section 52 are joined via welded joints 90. The number of welded joints 90 can be arbitrarily set according to the welding method and welding strength, and may be just one.

[0046] [E] Summary As described above, in the axial insertion type implantation method of this embodiment, the shim insertion portion 81 constituting the shim 80 is inserted into the gap G interposed between the wing implantation portion 52 and the wing implantation groove T30. Then, the shim joint portion 82 constituting the shim 80 is joined to the wing implantation portion 52.

[0047] Therefore, in this embodiment, the advantage of easy assembly is obtained by the axial insertion type implantation method, and since the blade implantation part 52 is sufficiently fixed in the blade implantation groove T30 by the shim 80, vibration resistance and damping can be effectively obtained. In addition, in this embodiment, the rotor blades 50 are less likely to fall over, so when a connecting structure (cover 61, etc.) is adopted to connect adjacent rotor blades 50 in the circumferential direction of the turbine rotor 30 (forward and rearward sides of the rotation direction R), it is possible to accurately confirm whether the connecting structure between the rotor blades 50 is in the state as designed. Furthermore, since the shim joint part 82 that constitutes the shim 80 is joined to the blade implantation part 52, it is possible to prevent the shim 80 from coming out of the gap during turbine operation.

[0048] Therefore, in this embodiment, vibration resistance and damping can be effectively obtained, and the reliability of the rotor blade 50 can be easily improved.

[0049] [F] Variation In the above embodiment, a case was described in which shims 80 are provided in each of the gaps G between the multiple hooks constituting the wing mounting section 52 and the wing mounting groove T30, but this is not limited to this. Shims 80 may be provided in only a portion of the gaps G. For example, shims 80 may be provided in the gap G corresponding to the hook that is radially the outermost of the multiple hooks constituting the wing mounting section 52, and shims 80 may not be provided in the gaps G corresponding to the other hooks.

[0050] Furthermore, the above embodiment describes a case in which a cover is provided on the tip side of the rotor blade and an intermediate snubber is provided between the blade mounting portion and the tip portion of the rotor blade, so that a connecting structure is formed between adjacent rotor blades in the circumferential direction of the turbine rotor. However, the embodiment is not limited to this. Other connecting structures besides those shown in the above embodiment are also acceptable.

[0051] <Second Embodiment> [A] Moving blade fixed structure Figures 4A and 4B show the blade fixing structure in the portion of the blade 50 embedded in the rotor disk 31 of the turbine rotor 30 in the steam turbine 1 of the second embodiment.

[0052] In Figure 4A, similar to Figure 3A, for example, the side view (yz plane) of the turbine rotor 30 (see Figure 1) where the axis centerline AX is perpendicular to the blade fixing structure for the blades 50 that constitute the final stage turbine stage 60 is shown.

[0053] Furthermore, Figure 4B, similar to Figure 3B, shows a magnified view of the portion of the turbine rotor 30 (see Figure 1) where the shim 80 is installed. The lateral direction in Figure 4B corresponds to the axial direction along the axis centerline AX of the turbine rotor 30 (see Figure 1).

[0054] As shown in Figures 4A and 4B, in this embodiment, the configuration of the joint between the rotor blade 50 and the shim 80 differs from that of the first embodiment (see Figures 3A and 3B). Except for this point and related points, this embodiment is the same as that of the first embodiment. Therefore, explanations of overlapping matters will be omitted as appropriate.

[0055] As shown in Figures 4A and 4B, in the rotor blade fixing structure of this embodiment, the rotor blade 50 is fixed to the rotor disk 31 using a shim 80. As shown in Figure 4B, in this embodiment as well, the shim 80 includes a shim insertion portion 81 and a shim joining portion 82. The shim insertion portion 81 is inserted into the gap G interposed between the surface of the blade implantation portion 52 of the rotor blade 50 and the surface of the blade implantation groove T30 formed in the rotor disk 31 of the turbine rotor 30 (see Figure 1).

[0056] However, in this embodiment, unlike in the first embodiment, the shim joint 82 and the wing implantation 52 are joined by an adhesive layer 91. The adhesive layer 91 is formed using an adhesive.

[0057] The process of joining the shim joint 82 and the wing mounting portion 52 (shim joining process) is performed, for example, by applying adhesive to the surface of the wing mounting portion 52 that faces the shim joint 82, and then pressing the shim joint 82 tightly against the wing mounting portion 52.

[0058] Here, the adhesive is, for example, an adhesive that hardens when a base agent and an activator are mixed, and preferably contains, for example, an epoxy resin component and a metal component (iron, aluminum, etc.) (e.g., Belometal®).

[0059] [B] Summary As described above, in the axial insertion type implantation method of this embodiment, similar to the first embodiment, the shim insertion portion 81 constituting the shim 80 is inserted into the gap G interposed between the wing implantation portion 52 and the wing implantation groove T30. Then, the shim joint portion 82 constituting the shim 80 is joined to the wing implantation portion 52.

[0060] Therefore, in this embodiment, as in the first embodiment, vibration resistance and damping properties can be effectively obtained, and the reliability of the rotor blade 50 can be easily improved.

[0061] <Other> While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0062] 1: Steam turbine, 10: Outer casing, 12: Cone section, 20: Inner casing, 30: Turbine rotor, 31: Rotor disc, 40: Stator blades, 41: Diaphragm inner ring 43: Diaphragm outer ring, 45: Nozzle diaphragm, 50: Rotary blade, 51: Blade body, 52: Blade mounting section, 60: Turbine stage, 61: Cover, 62: Intermediate snubber, 70: Steam supply pipe, 80: Shim, 81: Shim insertion section, 82: Shim joint, 90: Welded section, 91: Adhesive layer, 301: Bearing, 611: Leading edge cover section, 612: Trailing edge cover section, 621: Leading edge intermediate snubber section, 622: Trailing edge intermediate snubber section, AX: Axis centerline, G: Gap, R: Rotation direction, S511: Dorsal surface, S512: Ventral surface, T30: Blade mounting groove

Claims

1. A method for fixing rotor blades to a turbine rotor having blade mounting grooves formed along the axial direction, A shim insertion step is performed in which a shim is inserted into the gap between the blade mounting portion and the blade mounting groove in the blade mounting groove into which the blade mounting portion of the rotor blade is inserted. A shim joining step involves joining the shim inserted into the gap to the wing implantation portion. It has, The aforementioned shim is, The shim insertion portion inserted into the gap in the shim insertion step, The shim insertion portion extends in a second extending direction perpendicular to the first extending direction in which it extends, and the shim joining portion that is joined to the wing implantation portion in the shim joining process Includes, The wing mounting portion has a Christmas tree shape, including a plurality of hooks that protrude convexly from the ventral and dorsal sides of the control surface, and is configured to fit into the wing mounting groove. In the shim insertion step, the shim insertion portion is inserted into the gap located radially inward in the plurality of hooks. How to fix moving blades.

2. In the shim joining process, the shim is welded to the wing implantation portion. The method for fixing a rotor blade according to claim 1.

3. In the shim joining process, the shim is bonded to the wing implantation portion. The method for fixing a rotor blade according to claim 1.

4. A turbine rotor having blade mounting grooves formed along the axial direction, A rotor blade into which the wing implantation portion is inserted into the wing implantation groove and A rotor blade fixing structure comprising, wherein the rotor blade is fixed to the turbine rotor by a shim inserted in the gap between the blade mounting portion and the blade mounting groove, The aforementioned shim is, A shim insertion portion is inserted into the aforementioned gap, The shim insertion portion extends in a second extending direction perpendicular to the first extending direction in which it extends, and the shim joint portion is joined to the wing implantation portion. Includes, The wing mounting portion has a Christmas tree shape, including a plurality of hooks that protrude convexly from the ventral and dorsal sides of the control surface, and is configured to fit into the wing mounting groove. The shim insertion portion is inserted into the gap located radially inward in the plurality of hooks. Fixed rotor blade structure.

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