Fin tip position measurement method, fin tip position measurement system, and fin tip position measurement fixture

Abstract

The method for measuring the position of the front end of a fin includes: a fixture installation step, in which a fixture having a flat measuring surface extending in the circumferential direction and the axial direction is installed at the front end of at least one of a plurality of sealing fins that protrude radially relative to an axis, extend circumferentially, and are arranged along the direction in which the axis extends; a first measuring step, in which the distance from the axis to the measuring surface is measured by scanning the measuring surface with a laser; and a first calculation step, in which the distance from the axis to the front end of the sealing fin is calculated by adding the radial dimension of the fixture to the distance to the measuring surface.

Description

Technical Field

[0001] The invention relates to a method for measuring the front end position of a fin, a system for measuring the front end position of a fin, and a fixture for measuring the front end position of a fin.

[0002] This application claims priority based on Japanese Patent Application No. 2020-065281 filed in Japan on March 31, 2020, the contents of which are incorporated herein by reference. Background Art

[0003] For example, in a steam turbine, sealing fins are installed between the rotor (rotating body) and the nozzle ring (stationary body) to prevent steam leakage. The sealing fins sometimes wear out or fall over over years of use. As a result, the gap between the tip of the sealing fin and the rotor or blade ring changes, potentially affecting the performance of the steam turbine. Therefore, the condition of the sealing fins needs to be checked regularly. Furthermore, even unused sealing fins sometimes require clearance adjustment during turbine assembly. As a method for evaluating the clearance of such sealing fins, the technology described in the following Patent Document 1 is known.

[0004] In the evaluation method described in Patent Document 1, with the vehicle body disassembled, reflectors that reflect laser light are attached to the circumferential ends of the sealing fins, and the laser light is irradiated onto the reflectors. This allows the vertical and horizontal gaps between the sealing fins to be measured.

[0005] Previous technical literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2019-120167 Summary of the Invention

[0008] Technical issues to be solved by the invention

[0009] However, reflectors like these are difficult to stably attach to the sharp tips of sealing fins. This can compromise measurement accuracy. Furthermore, the need to reposition multiple reflectors each time and perform multiple measurements across the entire measurement area can increase the time required.

[0010] The present invention has been made to solve the above-mentioned problems, and its object is to provide a fin tip position measuring method, a fin tip position measuring system, and a fin tip position measuring jig that can easily and accurately measure the fin tip position.

[0011] Means for solving technical problems

[0012] In order to solve the above-mentioned problems, the method for measuring the position of the front end of the fin involved in the present invention includes: a fixture installation process, in which a fixture having a flat measuring surface extending in the circumferential direction and the axial direction is installed at the front end of at least one of a plurality of sealing fins that protrude radially relative to the axis, extend along the circumferential direction, and are arranged along the direction in which the axis extends; a first measuring process, in which the distance from the axis to the measuring surface is measured by scanning the measuring surface with a laser; and a first calculation process, in which the distance from the axis to the front end of the sealing fin is calculated by adding the radial dimension of the fixture to the distance to the measuring surface.

[0013] The system for measuring the position of the tip of a fin involved in the present invention comprises: a fixture, which is mounted on the tip of at least one of a plurality of sealing fins that protrude radially relative to an axis, extend circumferentially, and are arranged in the direction in which the axis extends, and has a flat measuring surface extending in the circumferential direction and the axial direction; a measuring unit, which measures the distance from the axis to the measuring surface by scanning the measuring surface with a laser; and a calculation unit, which calculates the distance from the axis to the tip of the sealing fin by adding the radial dimension of the fixture to the distance to the measuring surface.

[0014] The fixture for measuring the position of the front end of the fin involved in the present invention comprises: a holding portion that clamps the front end of the sealing fin that protrudes radially relative to the axis and extends along the circumferential direction from both sides in the axial direction; and a main body that is arranged on the radial inner side of the holding portion and forms a flat measuring surface that extends in the circumferential direction and the axial direction.

[0015] Effects of the Invention

[0016] According to the fin tip position measurement method, fin tip position measurement system, and fin tip position measurement jig of the present invention, the fin tip position can be measured easily and with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a diagram showing the configuration of a fin tip position measurement system according to an embodiment of the present invention.

[0018] Figure 2 It is a side view showing the structure of a jig for measuring the position of the tip of a fin according to an embodiment of the present invention.

[0019] Figure 3 It is a plan view showing the structure of a jig for measuring the position of the tip of a fin according to an embodiment of the present invention.

[0020] Figure 4 It is along Figure 3 Cross-sectional view taken along line IV-IV.

[0021] Figure 5 It is an explanatory diagram showing a state where a jig for measuring the fin tip position according to an embodiment of the present invention is attached to a sealing fin.

[0022] Figure 6 It is an explanatory diagram showing a measurement situation when a jig for measuring the fin tip position according to an embodiment of the present invention is attached to a sealing fin in an inclined state.

[0023] Figure 7 This is a flowchart showing a method for measuring the position of the tip of a fin according to an embodiment of the present invention.

[0024] Figure 8 It is a side view showing a modified example of the jig for measuring the fin tip position according to the embodiment of the present invention.

[0025] Figure 9 This is a side view showing still another modified example of the jig for measuring the fin tip position according to the embodiment of the present invention. DETAILED DESCRIPTION

[0026] (Structure of the Fin Tip Position Measurement System)

[0027] Below, reference Figures 1 to 4 , a fin tip position measurement system 100 (hereinafter referred to as “measurement system 100”) according to an embodiment of the present invention will be described. Figure 1 As shown, the measuring system 100 is a device for measuring the position of the front end 90t of the sealing fin 90 of the steam turbine. The sealing fin 90 is provided to seal the leakage of steam between the carriage (inner circumferential surface of the nozzle ring) and the outer circumferential surface of the rotor, not shown. The sealing fin 90 protrudes radially inward relative to the axis O and extends along the circumferential direction. In addition, a plurality of sealing fins 90 are arranged in the direction of the axis O. The sealing fin 90 has a triangular cross-sectional shape as the dimension in the direction of the axis O gradually decreases from the carriage side toward the front end 90t side. In addition, the measuring system 100 described later can also be applied to the sealing fins (i.e., the fins on the rotating blade side) provided on the outer circumferential surface of the rotor.

[0028] The measuring system 100 includes a jig 1 (measuring jig), a measuring unit 2, and a computing unit 3. The jig 1 is attached to the tip 90t of the sealing fin 90. The measuring unit 2 measures the distance from the axis O to a measuring surface 12S (described later) of the jig 1 by irradiating (scanning) the jig 1 with laser light.

[0029] More specifically, the measuring unit 2 is composed of a laser tracker disposed near the open vehicle compartment and a line scanner that can be moved to any position.

[0030] The laser tracker has previously grasped the position coordinates of the virtual axis in the entire coordinate system (the coordinates of the aforementioned axis O). The laser tracker can detect the position coordinates of the line scanner at any position.

[0031] The line scanner can detect the position coordinates (range image) of the jig 1 in a coordinate system based on the line scanner.

[0032] The laser tracker then processes the distance image data based on the position coordinates of the line scanner in the entire coordinate system and the position coordinates of the fixture 1 in the coordinate system based on the line scanner, thereby obtaining the distance from the virtual axis to the fixture 1. More specifically, the point group corresponding to the detection unit D (described later) of the fixture 1 is extracted from the point group measured by the line scanner, primarily based on brightness information. The center of gravity of each coordinate of this point group is calculated, and the position coordinates of the fixture 1 are calculated from these points.

[0033] The calculation unit 3 calculates the distance from the axis O to the front end 90 t of the sealing fin 90 by adding the radial dimension of the jig 1 to the value of the distance.

[0034] (Structure of the fixture)

[0035] like Figure 2 As shown, the clamp 1 has a holding portion 10, a main body portion 12, and a bayonet portion 13. In the holding portion 10, a recessed groove 10A is formed radially inwardly so as to sandwich the front end 90t of the sealing fin 90 from both sides in the direction of the axis O. Figure 4 As shown, the groove 10A gradually decreases in size in the axis O direction from the bottom toward the top of the clamp 1 in the height direction (radial direction when attached to the sealing fin 90). The clamp 1 is attached so that the bottom of the groove 10A coincides with the front end 90t of the sealing fin 90.

[0036] like Figure 2 As shown, the main body 12 is in the shape of a plate formed integrally with the retaining portion 10. The surface of the main body 12 facing the side opposite to the retaining portion 10 is set as a measuring surface 12S irradiated by the laser. The measuring surface 12S is flat, and the height direction of the sealing fin 90 is set as the normal. A plurality of (three) recesses (detection portions D) are formed at equal intervals on the measuring surface 12S. The detection portion D is polished to have a surface roughness lower than that of the measuring surface 12S. As a result, the laser irradiated to the detection portion D shows a reflection mode different from that of the measuring surface 12S (i.e., a reflection mode with a smaller interference component). In addition, as another example, it is also possible to use the detection portion D by attaching a mirror-like sticker to the measuring surface 12S without forming the above-mentioned recess.

[0037] And, as Figure 3As shown, the central portion 12C of the main body 12 in the longitudinal direction (the circumferential direction when attached to the sealing fin 90) is smaller in the width direction (the direction of the axis O when attached to the sealing fin 90) than the end portions 12t in the longitudinal direction. In other words, a "tapered portion" is formed in the central portion 12C.

[0038] like Figure 2 As shown, the bayonet portion 13 is a plate-shaped portion that protrudes downward from the lower surface of the main body 12 (the surface facing the side opposite to the measuring surface 12S). The bayonet portion 13 elastically clamps the sealing fin 90 from both sides along the axis O. A pair of bayonet portions 13 are provided at intervals in the circumferential direction.

[0039] (Method for measuring the fin tip position)

[0040] Next, refer to Figures 5 to 7 , the method for measuring the fin tip position using the above-mentioned measuring system 100 is described. Figure 7 As shown, the measuring method includes a fixture installation step S1, a first measuring step S2, a first calculating step S3, a second measuring step S4 and a second calculating step S5.

[0041] In the fixture installation process S1, as Figure 5 As shown, the fixture 1 is mounted on the front end 90t of the sealing fin 90. Specifically, the sealing fin 90 is clamped from both sides in the direction of the axis O by the bayonet portion 13. At this time, the bottom of the groove 10A is in contact with the front end 90t. Next, in the first measurement step S2, the laser L is irradiated from the measuring portion 2 to the fixture 1. In this way, the distance Lx from the axis O, which is the virtual center line of the rotor not shown, to the detection portion D can be measured. In addition, Figure 5 The dashed line H in the figure schematically represents the height position of the axis O. In this first measurement step S2, it is preferred that the distances from the axis O are measured for each of the three detection portions D, and the average of these three measured values is obtained as the distance Lx. Specifically, as will be described later, the outer shape of the jig 1 differs between the central portion 12C and the end portions 12t. Therefore, when the laser is scanned to obtain measurement results (reflected images), the position of the detection portion D located in the central portion 12C of the three detection portions D is determined based on the measurement results, and the positions of the other two detection portions D are also determined based on this measurement result. The average value is calculated based on these three measurement results.

[0042] In the first calculation step S3, the calculation unit 3 adds the previously obtained radial dimension La of the jig 1 to the distance Lx. Dimension La refers to the distance from the bottom surface of the detection portion D to the bottom of the groove 10A. As described above, the bottom of the groove 10A abuts the tip 90t of the sealing fin 90. Therefore, by adding the distance Lx to dimension La, the distance from the axis O to the tip 90t is obtained.

[0043] In the second measurement step S4, the distance Ly from the axis O to the bottom surface 90b is further measured by scanning the bottom surfaces 90b between the plurality of sealing fins 90 with a laser. The laser is directed toward the bottom surface 90b from the side of the central portion 12C of the main body 12. As described above, the central portion 12C tapers in the middle, allowing the laser to reach the bottom surface 90b without obstructing the laser's path. More specifically, the presence of this tapered portion reduces the likelihood of the bottom surface 90b forming a blind spot within the fixture 1, even when the spacing between the sealing fins 90 is relatively small, for example, when the fixture 1 is mounted tilted relative to the axis O or when the line scanner is not directly opposite the fixture 1, resulting in the laser beam irradiating the measurement surface 12S at an angle.

[0044] In the second calculation step S5, the distance Lx + La to the tip 90t of the sealing fin 90 is subtracted from the distance Ly from the axis O to the bottom surface 90b. This calculates the radial dimension of the sealing fin 90. By comparing this dimension with, for example, the design value of the sealing fin 90, the wear amount of the sealing fin 90 can be determined.

[0045] In addition, if Figure 6 As shown, consider the case where the jig 1 is installed tilted relative to the radial direction. In this case, in the first measurement step S2, the tilt angle θ is measured by comparing the measurement results of the three detection units D. Next, in the first calculation step S3, the calculation unit 3 calculates the cosine value of the radial dimension La of the jig 1 relative to the tilt angle θ (Lc = cosθ). The calculation unit 3 then adds the distance Lx to the value of Lc to calculate a value that corrects for the effect of the jig 1's tilt.

[0046] The above steps are repeated multiple times at any position in the circumferential direction of the sealing fin 90. Thus, the position of the tip 90t is measured over the entire sealing fin 90. Here, if multiple jigs 1 are prepared and these jigs 1 are set up and measured simultaneously, the number of measurements can be reduced.

[0047] (Effect)

[0048] According to the above method and structure, the measuring surface 12S of the jig 1 is scanned with a laser beam in a direction roughly aligned with the normal to the measuring surface 12S of the jig 1. The distance Lx from the axis O, the centerline of the rotor, to the measuring surface 12S (detection portion D) is first measured. Next, the distance from the axis O to the tip 90t of the sealing fin 90 is calculated by adding the radial dimension La of the jig 1 to the distance to the detection portion D. Without using a jig 1 having the aforementioned measuring surface 12S (detection portion D), it is difficult to accurately illuminate the sharp tip 90t of the sealing fin 90 with a laser beam, making it difficult to measure the tip 90t. While illumination is possible by attaching a reflector to the tip 90t of the sealing fin 90, it is particularly difficult to configure the reflector so that the relative position of the sharp tip 90t of the sealing fin 90 to be measured and the position actually measured with the laser beam can be accurately determined, making it difficult to ensure accuracy. However, according to the above method, by irradiating (scanning) the laser light onto the measuring surface 12S having a constant area and having the height direction of the sealing fin 90 as the normal line from the direction of the approximate normal line of the measuring surface 12S, in addition to preventing the laser light from being blocked by the vehicle body structure such as bolts, there is no need to consider the irradiation position of the laser light too much, and the position of the front end 90t of the sealing fin 90 can be reliably grasped, and the deviation between the position to be measured and the actual measurement position can be easily and accurately corrected. Moreover, in the above method, as long as the reflectivity of the detection part D and the accuracy of the dimension La are managed, even if the manufacturing accuracy of other parts of the fixture 1 is relatively rough, it is possible to perform measurements with sufficiently high accuracy. In other words, compared with conventional reflectors, the size to be managed is small, and the manufacturing cost can be suppressed to a low level. Therefore, it is easy to prepare multiple fixtures 1 in advance. As a result, multiple fixtures 1 can be used for measurement at a time, which can reduce the number of measurements (i.e., shorten the measurement time).

[0049] Furthermore, according to the above method and structure, the distance from the axis O to the bottom surface 90b of each sealing fin 90 is measured by laser scanning. By subtracting the distance (Lx + La) between the tip 90t of the sealing fin 90 and the axis O from this distance, the radial dimension of the sealing fin 90 can be calculated. By comparing this dimension with, for example, the design value of the sealing fin 90, the wear amount of the sealing fin 90 can be determined.

[0050] Furthermore, according to the above method and structure, even if the fixture 1 is attached in an inclined state and the normal direction of the measuring surface 12S does not exactly coincide with the height direction of the sealing fin 90, the actual measured value of the distance from the axis O to the measuring surface 12S (detection portion D) can be corrected based on the angle θ of the inclination. In other words, when the fixture 1 is attached to the sealing fin, measurement can be easily performed without excessive consideration of the posture or angle.

[0051] Furthermore, according to the jig 1, the detection portion D is formed, which reflects laser light differently from other portions. Therefore, the position of the detection portion D can be detected more easily and accurately using laser light. Furthermore, since multiple detection portions D are formed, the position of the tip of the sealing fin 90 can be measured with even higher accuracy by averaging the multiple detection results.

[0052] Furthermore, according to the jig 1 described above, the central portion 12C of the main body 12 is smaller than the end portions 12t. Therefore, during laser scanning, the position of the central portion 12C of the main body 12 (i.e., the central portion of the plurality of detection portions D) can be determined. For example, even if some of the plurality of detection portions D cannot detect, it is still possible to identify which of the remaining detection portions D can detect. As a result, even if there are some adverse conditions in the measurement environment, measurement results can be obtained, and the reliability of the data can be assessed.

[0053] (Other embodiments)

[0054] The embodiment of the present invention is described in detail with reference to the accompanying drawings. However, the specific structure is not limited to the embodiment, and also includes design changes within the scope of the present invention. For example, as a modification of the clamp 1, it is also possible to adopt Figure 8 The structure shown. Figure 8 In the example of the embodiment, in the clamp 1b, the shape of the holding portion 14 is different from that of the above embodiment. In addition, the clamp 1b does not have the above-mentioned bayonet portion 13. The end of the holding portion 14 is bent according to the curved shape of the front end 90t of the sealing fin 90. Figure 8 In the example of FIG. 1 , the retaining portion 14 has a downwardly convex curved shape so as to correspond to the sealing fin 90 provided on the inner peripheral side of the vehicle body. On the other hand, in the case of applying to the sealing fin provided on the outer peripheral surface of the rotor, as shown in FIG. Figure 9 As shown in FIG. 1 , it is desirable that the holding portion 14 has a curved shape that is convex upward. According to this structure, the clamp 1 b can be further simplified, and thus the manufacturing cost of the clamp 1 b can be reduced.

[0055] [Note]

[0056] The fin tip position measurement method, the fin tip position measurement system 100 , and the fin tip position measurement jig described in each embodiment are understood as follows, for example.

[0057] (1) The method for measuring the position of the front end of the fin involved in the first embodiment includes: a fixture installation process S1, installing a fixture 1 having a flat measuring surface 12S extending in the circumferential direction and the direction of the axis O on at least one front end 90t of a plurality of sealing fins 90 that protrude radially relative to the axis O, extend along the circumferential direction, and are arranged along the direction in which the axis O extends; a first measuring process S2, measuring the distance Lx from the axis O to the measuring surface 12S by scanning the measuring surface 12S with a laser; and a first calculation process S3, calculating the distance from the axis O to the front end 90t of the sealing fin 90 by adding the radial dimension La of the fixture 1 to the distance Lx to the measuring surface 12S.

[0058] According to the above method, by irradiating (scanning) the measurement surface 12S having a constant area with laser light, the tip position of the sealing fin 90 can be easily obtained without excessive consideration of the laser light irradiation position.

[0059] (2) The method for measuring the position of the front end of the fin involved in the second embodiment may further include: a second measuring step S4, measuring the distance Ly from the axis O to the bottom surface 90b by using a laser to scan the bottom surfaces 90b between the sealing fins 90; and a second calculating step S5, calculating the radial dimension of the sealing fin 90 by subtracting the distance Lx+La to the front end 90t of the sealing fin 90 from the distance Ly to the bottom surface 90b.

[0060] According to the above method, the distance Ly from the axis O to the bottom surface 90b of the sealing fins 90 is measured by laser scanning. The radial dimension of the sealing fin 90 can be calculated by subtracting the distance Lx+La between the tip 90t of the sealing fin 90 and the axis O from the distance Ly.

[0061] (3) In the method for measuring the tip position of the fin according to the third embodiment, the tilt angle θ of the fixture 1 relative to the radial direction may be further measured in the first measuring step S2, and the distance from the axis O to the measuring surface 12S may be corrected based on the tilt angle θ.

[0062] According to the above method, even when the jig 1 is attached in a tilted state, the actually measured value of the distance from the axis O to the measuring surface 12S can be corrected based on the tilt angle θ.

[0063] (4) The fin tip position measurement system 100 according to the fourth embodiment comprises: a fixture 1, which is mounted on at least one tip 90t of a plurality of sealing fins 90 that protrude radially relative to an axis O and extend circumferentially and are arranged along the direction in which the axis O extends, and has a flat measuring surface 12S extending in the circumferential direction and in the direction of the axis O; a measuring unit 2, which measures the distance Lx from the axis O to the measuring surface 12S by scanning the measuring surface 12S with a laser; and a calculation unit 3, which calculates the distance from the axis O to the tip 90t of the sealing fin 90 by adding the radial dimension La of the fixture 1 to the distance Lx to the measuring surface 12S.

[0064] According to the above configuration, by irradiating (scanning) the measurement surface 12S having a constant area with laser light, the tip position of the sealing fin 90 can be easily obtained without excessive consideration of the laser light irradiation position.

[0065] (5) In the fin tip position measurement system 100 according to the fifth embodiment, the measuring unit 2 may further measure the distance Ly from the axis O to the bottom surface 90 b by scanning the bottom surfaces 90 b between the sealing fins 90 using a laser, and the calculation unit 3 may further calculate the radial dimension of the sealing fin 90 by subtracting the distance Lx+La to the tip 90 t of the sealing fin 90 from the distance Ly to the bottom surface 90 b.

[0066] With the above configuration, the measuring unit 2 measures the distance Ly from the axis O to the bottom surface 90b of each sealing fin 90 by laser scanning the bottom surface 90b between the sealing fins 90. The calculating unit 3 calculates the radial dimension of the sealing fin 90 by subtracting the distance Lx+La between the tip 90t of the sealing fin 90 and the axis O from the distance Ly.

[0067] (6) In the fin tip position measurement system 100 according to the sixth embodiment, the measuring unit 2 may further measure an inclination angle θ of the fixture 1 relative to the radial direction, and correct the distance from the axis O to the measurement surface 12S based on the inclination angle θ.

[0068] According to the above configuration, even when the jig 1 is attached in an inclined state, the actually measured value of the distance from the axis O to the measuring surface 12S can be corrected based on the angle θ of the inclination.

[0069] (7) The measuring fixture (fixture 1) for the front end position of the fin involved in the seventh embodiment comprises: a retaining portion 10, which clamps the front end 90t of the sealing fin 90 protruding radially relative to the axis O and extending along the circumferential direction from both sides in the direction of the axis O; and a main body portion 12, which is arranged on the radial inner side of the retaining portion 10 and is formed with a flat measuring surface 12S extending in the circumferential direction and the direction of the axis O.

[0070] According to the above configuration, by arranging the retaining portion 10 so that the tip 90t of the sealing fin 90 is clamped, the jig 1 can be easily and stably retained at the tip 90t. Furthermore, a flat measurement surface 12S having a constant area is formed on the main body 12. This allows the position of the tip of the sealing fin 90 to be measured more easily and accurately without excessive concern for laser irradiation accuracy.

[0071] (8) In the fin tip position measurement jig (jig 1) according to the eighth aspect, a plurality of detection portions D may be formed on the measurement surface 12S, each reflecting laser light in a manner different from that of other portions.

[0072] According to the above configuration, the detection portion D is formed so as to reflect the laser light differently from other portions. Therefore, the position of the detection portion D can be detected more easily and accurately using the laser light. Furthermore, since a plurality of such detection portions D are formed, the position of the tip of the sealing fin 90 can be measured with even higher accuracy by averaging the plurality of detection results.

[0073] (9) In the fin tip position measuring jig (jig 1) according to the ninth aspect, the circumferential center portion 12C of the main body portion 12 may have a smaller dimension in the axis O direction than the circumferential end portions 12t.

[0074] According to the above configuration, the center portion 12C of the main body 12 is smaller than the end portions 12t. Therefore, when scanning with laser light, the position of the center portion 12C (i.e., the central portion of the plurality of detection portions D) can be determined. Furthermore, the laser light path is not obstructed, and the laser light can reach the bottom surface 90b.

[0075] Industrial applicability

[0076] According to the fin tip position measurement method, fin tip position measurement system, and fin tip position measurement jig of the present invention, the fin tip position can be measured easily and with high accuracy.

[0077] Explanation of symbols

[0078] 100-Measuring system, 1, 1b-Clamp, 2-Measuring part, 3-Calculation part, 10, 14-Holding part, 10A-Slot, 12-Main part, 12C-Center part, 12S-Measuring surface, 12t-End part, 13-Locking part, 90-Sealing fin, 90b-Bottom surface, 90t-Front end, D-Detection part.

Claims

1. A method for measuring the front end position of a fin, comprising: A jig installation step includes installing a jig having a main body and a retaining portion on a front end of at least one of a plurality of sealing fins that protrude radially relative to the axis, extend circumferentially, and are arranged along the direction in which the axis extends, the main body having a flat measuring surface extending in the circumferential direction and the axial direction, and the retaining portion being integrally formed with the main body and having a groove curved to conform to the curved shape of the front end; a first measuring step of obtaining a distance from the axis to the measuring surface by scanning the measuring surface with a laser; and The first calculation step calculates the distance from the axis to the front end of the sealing fin by adding the radial dimension of the jig to the distance to the measuring surface.

2. The method for measuring the front end position of a fin according to claim 1, further comprising: a second measuring step of obtaining a distance from the axis to the bottom surface by scanning the bottom surfaces of the sealing fins with a laser; and The second calculation step calculates the radial dimension of the sealing fin by subtracting the distance to the front end of the sealing fin from the distance to the bottom surface.

3. The method for measuring the position of the front end of a fin according to claim 1 or 2, wherein: In the first measurement step, an inclination angle of the jig relative to a radial direction is further measured, and the distance from the axis to the measurement surface is corrected based on the inclination angle.

4. A fin tip position measurement system comprising: a fixture mounted on at least one of the front ends of a plurality of sealing fins that protrude radially relative to the axis and extend circumferentially and are arranged along the direction in which the axis extends, and comprising a main body portion and a retaining portion, the main body portion having a flat measuring surface extending in the circumferential direction and the axial direction, the retaining portion being integrally formed with the main body portion and having a groove curved to conform to the curved shape of the front ends; a measuring unit that obtains a distance from the axis to the measuring surface by scanning the measuring surface with a laser; and The calculation unit calculates the distance from the axis to the front end of the sealing fin by adding the radial dimension of the jig to the distance to the measuring surface.

5. The fin tip position measurement system according to claim 4, wherein: The measuring unit further obtains the distance from the axis to the bottom surface by scanning the bottom surfaces between the sealing fins using a laser. The calculation unit further calculates the radial dimension of the sealing fin by subtracting the distance to the front end of the sealing fin from the distance to the bottom surface.

6. The fin tip position measurement system according to claim 4 or 5, wherein: The measuring portion further measures an inclination angle of the jig with respect to a radial direction, and corrects a distance from the axis to the measuring surface according to the inclination angle.

7. A fixture for measuring the position of a fin tip, comprising: a retaining portion that sandwiches a front end of a sealing fin that protrudes radially relative to the axis and extends in the circumferential direction from both sides in the axial direction and is formed with a groove that curves according to the curved shape of the front end; and The main body is formed integrally with the holding portion, is provided radially inward of the holding portion, and is formed with a flat measuring surface extending in the circumferential direction and the axial direction.

8. The jig for measuring the fin tip position according to claim 7, wherein: A plurality of detection portions are formed on the measurement surface, each reflecting laser light in a manner different from that of other portions.

9. The jig for measuring the fin tip position according to claim 7 or 8, wherein: The main body portion has a central portion in the circumferential direction whose dimension in the axial direction is smaller than that of both end portions in the circumferential direction.

Images