JP5579112B2 - Turbine blade fixed structure and blade root spring removal method - Google Patents

Description

  The present invention relates to a turbine blade fixing structure that urges and fixes a blade root to a blade groove to which a blade root of a turbine blade is fitted, and a blade root spring that urges and presses the blade root against the blade groove. Relates to the method of desorption.

  A turbine blade of a steam turbine or a gas turbine, which is a rotating machine, is fixed to the rotor by fitting the blade root of the turbine blade into the blade groove of the rotor. In this fitting structure, there is a gap due to manufacturing tolerance or the like between the blade groove and the blade root. Even if there is such a gap, when the rotor is rotating at high speed, the turbine blade is not vibrated because the turbine blade is fixed to the rotor by the centrifugal force acting on the turbine blade. However, when the rotor is rotated at low speed or stopped when the centrifugal force is reduced, the turbine rotor blades may vibrate in the radial direction, which may damage the blade roots or the surfaces of the blade grooves. In addition, this vibration may be transmitted through a shroud attached to the tip of the turbine blade and damage adjacent turbine blades. And when these damages are remarkable, replacement | exchange of a turbine rotor blade or a rotor may be needed.

Therefore, for example, Patent Document 1 discloses a blade root spring having a plurality of curved portions for the purpose of preventing vibration of the turbine rotor blade. FIG. 9 is a view showing a state in which the blade root spring is installed in a gap (hereinafter referred to as a groove gap) between the blade groove side tip surface of the blade root part and the bottom surface of the blade groove.
As shown in FIG. 9, the blade root spring 31 includes an intermediate portion 33 and end portions 32 </ b> A and 32 </ b> B. The intermediate portion 33 is provided so as to be in close contact with the blade root portion 21. Then, by using the strong pressing force of the blade root spring 31 to press the blade root portion 21 against the blade groove 11, the turbine rotor blade 20 is fixed to the turbine rotor 10 to prevent vibration.

Although not intended to prevent vibration of the turbine rotor blade, Patent Document 2 discloses that when measuring the natural frequency of the turbine rotor blade when the turbine is stationary, variation in the fixed state of the turbine rotor blade is reduced. For this purpose, it is disclosed that a turbine blade is pushed up and fixed by a push-up spring. This push-up spring is made of a coil spring made of a shape memory alloy and has a property that its length is shortened at a high temperature (40 ° C. to 50 ° C.) and returns to its original state at a normal temperature.
When the push-up spring is inserted into the groove gap, first, the push-up spring is shortened to a high temperature state. Subsequently, the push-up spring in a short state is inserted into the groove gap and installed at a predetermined position. Thereafter, when the temperature of the push-up spring decreases to normal temperature, the push-up spring returns to its original state, that is, becomes longer, and pushes and fixes the turbine rotor blade. In this way, by pushing up and fixing the turbine blade by the push-up spring, the variation in the fixed state of the turbine blade is reduced, so that the stationary frequency of the stationary turbine blade can be accurately measured.

JP 2005-273646 A JP-A-1-237304

However, the blade root spring described in Patent Document 1 may be appropriately replaced at the time of periodic inspection of the turbine because the pressing force may decrease due to sag due to repeated loads or deformation due to aging.
In the replacement work, a rod-shaped jig is inserted into the groove gap and brought into contact with the end face of the blade root spring, and the jig is pushed in the longitudinal direction of the groove gap to remove the blade root spring from the groove gap. Pushing out. However, since the pressing force of the blade root spring is strong, a very large force is required to push out the blade root spring with a jig, and sometimes the blade root spring is struck with a hammer or pushed out with a hydraulic jack. The spring may be pushed out of the groove gap.
Also, when a new blade root spring is installed in the groove gap after inspection, the pressing force of the blade root spring acts, so that a jig is brought into contact with the end surface of the blade root spring to remove it. The blade root spring may be inserted into the groove gap while hitting the tool with a hammer or pushing with a hydraulic jack.
Therefore, since the work for removing and attaching the blade root spring is time-consuming and difficult, a long work time is required.
Further, if an impact is applied to the blade root spring with a hammer or a strong load is applied with a hydraulic jack, the blade root portion or blade groove in contact with the blade root spring may be damaged.

  The push-up spring described in Patent Document 2 is originally intended to measure the fixed frequency when the turbine is stationary, and is mounted only when the turbine is stationary. It is not a so-called blade root spring to prevent.

  Accordingly, the present invention provides a turbine rotor blade fixing structure and a blade root spring attaching / detaching method capable of replacing the blade root spring in a short time without damaging the blade root of the turbine rotor blade and the blade groove of the rotor. It is the purpose.

A turbine rotor blade fixing structure according to the present invention that solves the above-described problem is a turbine rotor blade fixing structure that fits and fixes a blade root portion of a turbine rotor blade into a blade groove,
It is formed by winding a linear member in a coil shape, and includes a blade root spring provided in a gap between the blade root portion and the blade groove,
The blade root spring is disposed along the longitudinal direction of the gap so that the outer peripheral surface contacts the tip surface of the blade root portion and the bottom surface of the blade groove,
The radial length of the blade root spring is longer than the gap between the blade root and the blade groove.
According to the turbine rotor blade fixing structure, since the blade root spring in which the linear member is wound in a coil shape is provided in the gap, the blade root spring is contracted by pulling the blade root spring in the longitudinal direction. After the diameter is made shorter than the length of the gap, the turbine rotor blade and blade root spring are detached from the blade groove, so that the blade root spring can be easily and quickly removed without damaging the blade root or blade groove. Desorption work can be carried out.
In the present specification, the radial natural length of the blade root spring means the outer diameter of the blade root spring when no load is applied.

In addition, the central portion in the longitudinal direction of the blade root spring and the both end portions located at both ends of the central portion are such that the natural length in the radial direction of the both end portions is smaller than the natural length in the radial direction of the central portion. It may be configured.
According to the blade root spring, since the natural length in the radial direction at both ends is smaller than the natural length in the radial direction at the central portion, the length of the natural length in the radial direction is uniform over the entire length in the longitudinal direction. As a result, the end portion can be easily taken out of the gap, and the operation of pulling the blade root spring can be easily performed.
Further, according to the blade root spring, since the natural length in the radial direction at both ends is smaller than the natural length in the radial direction at the central portion, the length of the natural length in the radial direction is uniform over the entire length in the longitudinal direction. It can be inserted into the gap more easily than when a root spring is used.

The linear member may be formed by twisting a plurality of linear bodies.
According to the linear member, since the linear member is formed from a plurality of linear members, the linear member is separated by loosening the twist of the linear member, and the coil shape of the blade root spring is deformed to restore the blade root spring. By eliminating the force, the blade root part and the blade groove are not damaged when the blade root spring is pulled out from the gap.

The blade root spring attaching / detaching method according to the present invention is provided in a gap formed between a blade root portion of a turbine blade and a blade groove into which the blade root portion is fitted, and biases the blade root portion. A method of removing and attaching the blade root spring pressed against the blade groove,
A diameter reducing step of reducing the length of the blade root spring in a direction orthogonal to the longitudinal direction by applying a tensile load to the blade root spring along the longitudinal direction of the gap;
A turbine rotor blade attaching / detaching step of attaching / detaching the turbine rotor blade to / from the blade groove with the blade root spring having a reduced diameter;
A blade root spring detaching step of detaching the blade root spring with respect to the blade groove in a state where the turbine rotor blade is removed;
It is characterized by providing.
According to the above-described method for attaching and detaching the blade root spring, the blade root spring provided in the gap is pulled in the longitudinal direction of the gap, thereby reducing the length of the blade root spring in the direction perpendicular to the longitudinal direction of the gap. Since the turbine blade and blade root spring are detached from the blade groove after making it shorter than the gap length, the blade root spring can be easily detached in a short time without damaging the blade root or blade groove. Can perform work.

The tensile load acting on the reduced diameter blade root spring may be released after the turbine rotor blade is detached from the blade groove.
When the tensile load is released after detaching the turbine blade from the blade groove, the blade root spring expands, and the blade root portion of the turbine blade can be urged and pressed against the blade groove.

The blade root spring attaching / detaching method according to the present invention is provided in a gap formed between a blade root portion of a turbine blade and a blade groove into which the blade root portion is fitted, and biases the blade root portion. A method of removing and attaching the blade root spring pressed against the blade groove,
A second diameter reducing step of reducing the length of the blade root spring in a direction orthogonal to the longitudinal direction by applying a tensile load to the blade root spring along the longitudinal direction of the gap;
A second blade root spring detaching step of detaching the reduced diameter blade root spring with respect to the gap in a state where the turbine rotor blade is attached to the blade groove;
It is characterized by providing.
According to the above-described method for attaching and detaching the blade root spring, the blade root spring provided in the gap is pulled in the longitudinal direction of the gap, thereby reducing the length of the blade root spring in the direction perpendicular to the longitudinal direction of the gap. Since the blade root spring is detached from the gap after the gap is made shorter than the length of the gap, the blade root spring can be easily attached and detached in a short time without damaging the blade root part or the blade groove.

  According to the present invention, the blade root spring can be detached in a short time without damaging the blade root portion or blade groove of the turbine rotor blade.

It is a perspective view which shows the state which connected the turbine rotor blade which concerns on embodiment of this invention to the turbine rotor. It is a side view of a blade root spring. FIG. 3 is a view as seen from an arrow A in FIG. 2. FIG. 6 is an enlarged cross-sectional view showing a state in which a blade root spring is provided in a groove gap between the blade groove tip end surface of the blade root portion and the bottom surface of the blade groove. It is BB sectional drawing of FIG. It is the schematic which shows the state which has removed the blade root spring from the inside of a groove gap. It is CC sectional drawing of FIG. It is the schematic which shows the state which has attached the blade root spring in the groove clearance. It is sectional drawing which shows the state which provided the conventional blade root spring in the groove clearance of the blade groove | channel of a turbine rotor, and the blade root part of a turbine rotor blade.

Hereinafter, embodiments of a blade root spring of a rotating machine according to the present invention will be described in detail with reference to the drawings. In the following description, the case where the blade root spring is applied to a gas turbine will be described. However, the present invention is not limited to this and can be applied to a turbine such as a steam turbine or a jet engine. In addition, it can be applied to an air compressor of a gas turbine or a jet engine.
Further, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the following examples are not intended to limit the scope of the present invention unless otherwise specified, and are merely explanations. It is just an example.

FIG. 1 is a perspective view showing a state in which a turbine rotor blade according to an embodiment of the present invention is connected to a turbine rotor.
As shown in FIG. 1, the turbine rotor blade 20 of the gas turbine 1 is fixed to the turbine rotor 10 by fitting a blade root portion 21 into a blade groove 11 formed in the turbine rotor 10.
A plurality of blade grooves 11 are provided on the outer peripheral portion of the turbine rotor 10 at predetermined intervals in the circumferential direction. Each blade groove 11 is opened along the axial direction of the turbine rotor 10. In addition, a plurality of convex portions 12 and concave portions 13 are alternately provided in each blade groove 11 along the radial direction of the turbine rotor 10. Further, the blade root portion 21 of the turbine rotor blade 20 is provided with a plurality of convex portions 22 that engage with the concave portions 13 and a plurality of concave portions 23 that engage with the convex portions 12.
Then, the concave portion 23 of the blade root portion 21 is fitted to the convex portion 12 of the blade groove 11, and the convex portion 22 of the blade root portion 21 is fitted to the concave portion 13 of the blade groove 11, so that the turbine rotor blade 20 is attached to the turbine rotor 10. Connected.
Further, a blade root spring is provided in the groove gap between the blade groove side tip surface 24 of the blade root 21 and the bottom surface 14 of the blade groove 11, and the blade root 21 is pressed against the blade groove 11 by this blade root spring. It has been.

FIG. 2 is a side view of the blade root spring. FIG. 3 is a view taken in the direction of arrow A in FIG.
As shown in FIGS. 2 and 3, the blade root spring 3 is formed by winding a linear member in a coil shape (spiral shape), and has a main body portion 15 and end portions 16A and 16B.
The main body 15 is formed so that its natural length D _{0 in the} radial direction is larger than the height of the groove gap between the blade groove side tip surface 24 of the blade root 21 and the bottom surface 14 of the blade groove 11.
The end portions 16 </ b> A and 16 </ b> B are provided so as to extend on both sides of the main body portion 15. The end portions 16A, 16B is shorter than the natural length D ₀ of the main body portion 15 is a natural length M ₀ in the radial direction, and is formed to be shorter than the height of the groove gap.
The linear member of the blade root spring 3 is not particularly limited as long as it is a material having wear resistance and heat resistance. For example, a steel wire, a copper wire, a titanium wire, or the like can be used.
When one end 34 of the blade root spring 3 is fixed and the other end 35 is pulled, the blade root spring 3 has a property of extending in the longitudinal direction and reducing the length in the radial direction.

FIG. 4 is an enlarged cross-sectional view showing a state in which the blade root spring 3 is provided in the groove gap between the blade groove side tip surface 24 of the blade root portion 21 and the bottom surface 14 of the blade groove 11. FIG. 5 is a sectional view taken along line BB in FIG.
As shown in FIGS. 4 and 5, the blade root spring 3 is provided along the longitudinal direction in the groove gap 2.
Since the natural length D _{0 in} the radial direction of the main body portion 15 is longer than the height H of the groove gap, the main body portion 15 is in close contact with the blade groove side tip surface 24 of the blade root portion 21 and the bottom surface 14 of the blade groove 11. Further, since the natural length M _{0 in} the radial direction of the end portions 16A and 16B is shorter than the height H of the groove gap, there is a gap between the end portions 16A and 16B and the blade groove side tip surface 24 of the blade root portion 21. Is formed. At this time, the blade root 21 is urged radially outward of the turbine rotor 10 by the pressing force of the main body 15 of the blade root spring 3 and is pressed against the blade groove 11.
Caps 4A and 4B are provided at both ends of the groove gap 2 to prevent the blade root spring 3 from coming out.

  Next, a method for removing the blade root spring 3 from the blade groove 11 will be described.

FIG. 6 is a schematic view showing a state in which the blade root spring 3 is removed from the blade groove 11. FIG. 7 is a cross-sectional view taken along the line CC of FIG.
As shown in FIGS. 6 and 7, first, caps 4A and 4B provided at both ends of the groove gap 2 are removed.
Next, the jig 5 is put on both ends 34 and 35 of the blade root spring 3 provided in the groove gap 2, and the both ends 34 and 35 are pulled in the pulling direction (arrow direction in FIG. 6). Pulling the ends 34 and 35, the end portion 16A, 16B is the length M ₁ of the radial diameter while extending the pulling direction, followed by, in the radial direction while the main body portion 15 is extended in length D ₁ is reduced in diameter. At this time, to a length D ₁ of the radial direction of the main body portion 15 is shorter than the height H of the groove gap, i.e., both ends of the blade root spring 3 until the blade root spring 3 is separated from the blade groove side distal end surface 24 Pull 34 and 35.
Then, with the diameter of the blade root spring 3 being reduced, the blade root portion 21 of the turbine rotor blade 20 is moved in the longitudinal direction of the groove gap 2 and pulled out.
Even if the blade root portion 21 is moved, the radial length D ₁ of the main body portion 15 of the blade root spring 3 is shorter than the height H of the groove gap 2, so that it does not contact the blade root spring 3.
Thereafter, the blade root spring 3 is removed from the blade groove 11 from which the blade root portion 21 has been removed, while the diameter of the blade root spring 3 is reduced. The blade root spring 3 may be removed from the blade groove 11 after the tensile load of the blade root spring 3 is released to return the length of the blade root spring 3 to its original state.
Thereby, the blade root spring 3 can be easily removed without damaging the blade root portion 21 and the blade groove 11.

  Next, a method for mounting the blade root spring 3 in the blade groove 11 will be described.

FIG. 8 is a schematic view showing a state in which the blade root spring 3 is attached in the groove gap 2.
As shown in FIG. 8, first, the jig 5 is hung on both ends 34, 35 of the blade root spring 3, and both ends 34, 35 are pulled in the pulling direction to reduce the diameter of the blade root spring 3. In this case, the radial length D ₁ of the main body portion 15 until shorter than the height H of the groove gap, pull the two ends 34, 35.
Next, the main body portion 15 of the blade root spring 3 in a reduced diameter state is provided in the blade groove 11. Further, both ends 34 and 35 are arranged outside the blade groove 11 and are held so that the length of the blade root spring 3 between the both ends 34 and 35 does not change. Since there is no blade root portion 21 of the turbine rotor blade 20 in the blade groove 11, the blade root spring 3 can be easily mounted in the blade groove 11.
Next, the blade root portion 21 of the turbine blade 20 is inserted into the blade groove 11 and fitted. Even when the blade root portion 21 is inserted into the blade groove 11, the radial length D ₁ of the blade root spring 3 is shorter than the height H of the groove gap 2, so that it does not contact the blade root spring 3.
Thereafter, the tensile force of the blade root spring 3 is gradually released, and the length of the blade root spring 3 in the longitudinal direction is contracted. When the blade root spring 3 is contracted gradually it becomes longer radial length D ₁ of the blade root spring 3 biases the blade groove side leading end surface 24 of the blade root portion 21 radially outward of the turbine rotor 10 and blades Press against the groove 11 and fix.
Finally, caps 4A and 4B are attached to both ends of the groove gap 2.
Therefore, the blade root spring 3 can be attached in a short time without damaging the blade root portion 21 and the blade groove 11.

  As described above, according to the method for attaching and detaching the blade root spring 3 in the present embodiment, the blade root spring 3 is reduced in diameter by pulling the blade root spring 3 provided in the groove gap 2 in the longitudinal direction. Since the turbine rotor blade 20 and the blade root spring 3 are respectively detached from the blade groove 11 after being made shorter than the height H of the groove gap 2, the blade root portion 21 and the blade groove 11 are not damaged. The detachment operation of the blade root spring 3 can be easily performed in time.

  In addition, since gaps are formed between the end portions 16A, 16B and the blade groove side tip surface 24 of the blade root portion 21, the end portions 16A, 16B can be easily taken out of the groove gap 2, respectively, and the blade root spring The operation | work which pulls 3 can be implemented easily.

In the present embodiment, the case where the blade root spring 3 in a state of being reduced in diameter with respect to the blade groove 11 not fitted with the turbine rotor blade 20 is described, but is not limited thereto. The blade root spring 3 in a state of being reduced in diameter relative to the groove gap 2 of the blade groove 11 into which the turbine rotor blade 20 is fitted may be detached. State Specifically, reduced in diameter in the radial direction of the length D ₁ pulling direction tensile blade root spring 3 provided in the groove gap 2, the turbine blades 20 is fitted in the blade groove 11 The blade root spring 3 may be pulled out from the groove gap 2 as it is, or the blade root spring 3 may be inserted into the groove gap 2. According to such a case, the radial length D end 16A than the _first body portion 15 of the blade root spring 3, the radial length M ₁ of the 16B is short, the blade root spring 3 in the groove gap 2 Can be easily inserted into.

In addition, although the case where what wound the one linear member in the coil shape was used as the blade root spring 3 was demonstrated, it is not limited to this, A linear member is twisted by several linear bodies. You may form together. A metal wire having wear resistance and heat resistance is preferably used as the linear body, and for example, a steel wire, a copper wire, a titanium wire, or the like is used. When one end of a blade root spring formed from a plurality of linear bodies is fixed and the other end is pulled, the blade root spring expands in the longitudinal direction and the lengths D ₁ and M ₁ in the radial direction contract. Therefore, it can be detached into the blade groove 11 by the same removal method as the blade root spring 3 described above.
In particular, when a blade root spring composed of a plurality of linear bodies is removed from the blade groove 11, the linear members are separated by loosening the twist of the linear body, and the coil shape of the blade root spring is deformed to deform the blade root. By eliminating the restoring force of the spring, the blade root spring can be removed from the blade groove 11.

DESCRIPTION OF SYMBOLS 1 Gas turbine 2 Groove clearance 3 Blade root spring 4A, 4B Cap 5 Jig 10 Turbine rotor 11 Blade groove 12 Convex part 13 Concave part 14 Bottom face 15 Main part 16A End part 16B End part 20 Turbine rotor blade 21 Blade root part 22 Convex part 23 Recess 24 Blade groove tip surface 31 Blade root spring 32A End portion 32B End portion 33 Intermediate portion 34 One end 35 Other end H Groove gap height D ₀ Radial length of main body portion D ₁ Radial length of main body portion M ₀ Natural length in the radial direction of the end M ₁ Radial length in the radial direction of the end ₁

Claims (6)

A turbine rotor blade fixing structure for fitting and fixing a blade root portion of a turbine rotor blade into a blade groove,
It is formed by winding a linear member in a coil shape, and includes a blade root spring provided in a gap between the blade root portion and the blade groove,
The blade root spring is disposed along the longitudinal direction of the gap so that the outer peripheral surface contacts the tip surface of the blade root portion and the bottom surface of the blade groove,
The turbine blade fixing structure, wherein a natural length in a radial direction of the blade root spring is longer than a gap between the blade root portion and the blade groove.   The central portion in the longitudinal direction of the blade root spring and both end portions located at both ends of the central portion are configured such that the natural length in the radial direction of the both end portions is smaller than the natural length in the radial direction of the central portion. The turbine rotor blade fixing structure according to claim 1, wherein the turbine rotor blade fixing structure is provided.   2. The turbine rotor blade fixing structure according to claim 1, wherein the linear member is formed by twisting a plurality of linear bodies. 3. A blade root spring detaching method is provided in a gap formed between a blade root portion of a turbine rotor blade and a blade groove in which the blade root portion is fitted, and urges the blade root portion to press it against the blade groove. And
A first diameter reduction step of reducing the length of the blade root spring in a direction perpendicular to the longitudinal direction by applying a tensile load to the blade root spring along the longitudinal direction of the gap;
A turbine rotor blade attaching / detaching step of attaching / detaching the turbine rotor blade to / from the blade groove with the blade root spring having a reduced diameter;
A first blade root spring detaching step of detaching the blade root spring with respect to the blade groove with the turbine rotor blade removed;
A method for attaching and detaching a blade root spring.   5. The blade root spring according to claim 4, wherein after the turbine rotor blade is attached to and detached from the blade groove, the tensile load acting on the reduced diameter blade root spring is released. Desorption method. A blade root spring detaching method is provided in a gap formed between a blade root portion of a turbine rotor blade and a blade groove in which the blade root portion is fitted, and urges the blade root portion to press it against the blade groove. And
A second diameter reducing step of reducing the length of the blade root spring in a direction orthogonal to the longitudinal direction by applying a tensile load to the blade root spring along the longitudinal direction of the gap;
A second blade root spring detaching step of detaching the reduced diameter blade root spring with respect to the gap in a state where the turbine rotor blade is attached to the blade groove;
A method for attaching and detaching a blade root spring.

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