Nondestructive flaw detection device applied to groove bottom of sunken area of shroud of guide vane

Abstract

The invention relates to the technical field of optics, in particular to a nondestructive flaw detection device applied to a groove bottom of a sunken area of a vane crown of a guide vane, which comprises a loading support, a clamp for clamping the guide vane to be detected is arranged on the loading support, and the clamp is used for keeping the guide vane to be detected horizontally and transversely; the to-be-detected guide vane is provided with a vane crown, and the sunken part of the vane crown points to the front; the inner wall of the light absorption cylinder is provided with a black frosted surface; the outer contour of the light absorption cylinder is matched with the inner contour of the sunken part of the blade crown, and the light absorption cylinder is inserted into the sunken part; the groove bottom of the sunken part of the blade crown is exposed from an opening in the bottom of the light absorption cylinder; a laser interferometer is arranged on the front side of the loading support. A measuring light beam and a reference light beam of the laser interferometer are projected to the surface of the groove bottom of the blade crown sunken part without hindrance, the light absorption cylinder eliminates light interference caused by secondary reflection, clearer interference imaging is obtained, and the groove bottom of the blade crown sunken part is measured completely and accurately.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, and in particular to a non-destructive flaw detection device applied to the groove bottom of the recessed area of the guide vane crown. BACKGROUND

[0002] An aero-engine is a highly complex and precise thermodynamic machine that generates thrust or power through thermodynamic conversion to provide flight power for an aircraft. The guide vane (guide vane) of the aero-engine is a key component in the turbine part, which functions to adjust the airflow direction and efficiently transfer energy.

[0003] In order to facilitate the assembly of the guide vane, the guide vane is connected to the crown and the root at both ends, the crown is connected to the casing, and the root is connected to the wheel disc. In order to reduce the possibility of high-temperature and high-pressure gas leaking from the guide vane crown part under high-speed rotation, the crown is usually designed as a labyrinth structure. This design effectively reduces the leakage and improves the sealing performance of the aero-engine by increasing the path length and complexity of gas or air flow.

[0004] After the crown is manufactured, if there are defects (such as pores, burrs, cracks, inclusions), under extreme working conditions (high temperature, high pressure, high speed), it may cause serious engine failure, so it needs to be precisely detected by non-destructive flaw detection. Non-destructive flaw detection equipment often uses a three-coordinate measuring machine or a blue light scanner.

[0005] However, the labyrinth crown has recessed parts, and when using a three-coordinate measuring machine to detect the non-destructive flaws of the groove bottom of the recessed part of the crown, the measuring rod is inserted into it, which is easy to collide with the inclined wall surface, resulting in measurement error and affecting the measurement accuracy.

[0006] When using a blue light scanner to detect the non-destructive flaws of the groove bottom of the recessed part of the crown, the blue stripes projected by the blue light scanner are blocked by the edge of the recessed area, and cannot irradiate the blocked groove bottom part of the recessed area, resulting in data loss, which requires repeated angle scanning and replacement, which takes a long time and affects the measurement efficiency.

[0007] Even if the blue stripes can successfully irradiate the groove bottom part of the recessed area through complex angle adjustment, because the guide vane crown is recessed deep, there is inevitable optical pollution interference of multiple reflections, which is difficult to achieve high-precision measurement effect. SUMMARY

[0008] The purpose of the present application is to provide a non-destructive flaw detection device applied to the groove bottom of the recessed area of the guide vane crown to solve at least one of the above technical problems.

[0009] The technical problem solved by the present application can be realized by using the following technical scheme:

[0010] A non-destructive testing device for the bottom of the groove in the concave area of ​​the guide vane crown includes a loading support, wherein the loading support is provided with a clamp for holding the guide vane to be tested, and the clamp is a clamp that keeps the guide vane to be tested horizontally.

[0011] The guide vane to be tested has a leaf crown, and the concave part of the leaf crown points forward;

[0012] It also includes a hollow light-absorbing tube with openings at both ends, the inner wall of which is made of black frosted material;

[0013] The outer contour of the light-absorbing tube is adapted to the inner contour of the recessed part of the leaf crown, and the light-absorbing tube is inserted into the recessed part;

[0014] The bottom of the groove in the concave part of the leaf crown is exposed through the opening at the bottom of the light-absorbing tube;

[0015] A laser interferometer is installed on the front side of the loading support;

[0016] The laser interferometer is equipped with a beam splitter, which divides the incident beam into a measurement beam and a reference beam.

[0017] The angle between the measuring beam and the reference beam in the vertical direction is between 3 and 12 degrees;

[0018] The measuring beam and the reference beam are projected onto the bottom of the groove in the concave part of the leaf crown to form a measuring spot and a reference spot, and are reflected by the bottom of the groove in the concave part of the leaf crown to form two reflected beams;

[0019] The laser interferometer also includes two light-shielding channels, which are parallel to the pointing directions of the measurement beam and the reference beam, respectively.

[0020] The light-shielding channel uses a straight circular tube with a graphite frosted coating.

[0021] The laser interferometer also includes two optical components for adjusting the angle of the light beam, which are located behind the two light-shielding channels respectively.

[0022] The two optical components adjust the return beams transmitted from the two light-blocking channels to perform interference imaging.

[0023] The laser interferometer is mounted on a gimbal, and a vertically lifting hydraulic lifting device is installed below the gimbal.

[0024] The rotation center of the gimbal coincides with the arc center of the concave part.

[0025] In the above design, the recessed part of the guide vane to be tested is relatively deep and has a smooth surface. The light-absorbing tube is inserted into the recessed part of the vane, blocking the inclined wall of the recessed part. The bottom of the recessed part is exposed through the opening, so that the measurement beam and reference beam of the laser interferometer can be projected onto the bottom surface of the recessed part of the vane without obstruction. By setting the light-absorbing tube, the light interference caused by secondary reflection is eliminated, and a clearer interference image is obtained. After one clamping and positioning, the bottom of the recessed part of the vane can be completely and accurately measured without repeatedly changing the detection angle of the laser interferometer.

[0026] Traditional laser interferometers are high-precision measuring instruments based on the principle of interference. During the scanning process, it is unavoidable that there will be relative displacement and relative angle changes between the laser interferometer and the bottom of the groove in the concave part of the leaf crown, at least at the micrometer level. This causes irregular jumps in the interference fringes, making it impossible to scan the true defect area.

[0027] This patent application eliminates the fixed reference mirror in traditional laser interferometers, using the bottom surface of the groove in the leaf crown recess as the reflecting surface of the measurement beam and the reference beam. Since the two beams scan synchronously, any common displacement or angular change has a synchronous and equal effect on the two optical paths. Therefore, the optical path difference between the measurement beam and the reference beam changes synchronously and is almost unaffected by slight changes in the position between the laser interferometer and the bottom surface of the groove in the leaf crown recess. This avoids the problem of irregular jumps in interference imaging during the scanning process, making it easier to accurately scan the location of tiny damages. Theoretically, the scanning accuracy can be at the level of several micrometers or even nanometers.

[0028] The measuring beam and the reference beam have a small included angle of 3 to 12 degrees in the vertical direction, indicating that when the measuring beam and the reference beam are projected onto the arc-shaped surface of the bottom of the blade canopy groove, they will form a measuring spot and a reference spot that are spatially separated and have a fixed small spacing. This is to facilitate sampling of two adjacent but different points on the bottom surface of the groove. The laser interferometer performs dynamic scanning under the drive of the gimbal and hydraulic lifting load to acquire a series of continuous interference images on the bottom surface of the entire blade canopy recess, and these series of continuous interference images are compared.

[0029] When scanning a defect-free, smooth curved surface, the optical path changes of the measuring beam and the reference beam are synchronous and coordinated. Therefore, the relative optical path difference between the two beams remains stable throughout the scanning process and does not exceed the set threshold, without producing drastic or abnormal stripe jumps.

[0030] When scanning large-area defects (wide corrosion pits or extended scratches), the surface contour of a large-area defect is a localized change compared to a smooth, intact curved surface. This also indicates that the surface flatness of the area is different from the surrounding normal area. When both the measuring spot and the reference spot enter the large-area defect area, although they both fall within the defect area, the microscopic or macroscopic contour undulations of the defect area itself (it cannot be absolutely smooth) will immediately manifest as chaotic, distorted interference fringes and abrupt changes in spacing, which can be quickly identified.

[0031] Alternatively, by selecting a larger angle between the measuring beam and the reference beam, so that neither the measuring beam nor the reference beam falls within the range of the defect, the problem of defects that are too large to detect can be solved.

[0032] By setting up a light-shielding channel with a graphite frosted coating, only reflected light rays that are nearly parallel to the direction of the light-shielding channel can pass through. Light rays with excessively large phase angles are absorbed by the graphite frosted coating, reducing the impact of stray light on interference imaging.

[0033] Because the orientation of the two light-shielding channels is fixed, an optical component is set to adjust the angle of the light. The optical component system is formed by combining optical fiber and converging lens. The light outlet of the light-shielding channel is directly opposite the light inlet of the optical fiber. The converging lens is located behind the light outlet of the optical fiber. The reflected light from the light-shielding channel enters the optical fiber through the light inlet and exits through the light outlet of the optical fiber. After passing through the converging lens, it is projected onto the grating.

[0034] Since the bottom of the groove in the concave part of the leaf crown is an arc-shaped surface, the rotation center of the gimbal is set to overlap with the arc center of the concave part to avoid significant changes in the optical path difference between the measurement beam and the reference beam during the scanning process.

[0035] Preferably, for qualified recessed areas, no significant change in optical path difference occurs during the scanning process of the measuring beam and the reference beam. When the change in optical path difference shown in the interference image is greater than the set amplitude, it is considered that a defect has been detected.

[0036] Preferably, a vertical plate-shaped bracket is mounted on the loading support, and the light-absorbing tube is fixed on the plate-shaped bracket. The plate-shaped bracket supports the light-absorbing tube, ensuring that the light-absorbing tube remains stable during the flaw detection process.

[0037] Preferably, the wall thickness of the light-absorbing tube is between 0.1 and 0.5 cm.

[0038] Preferably, the laser interferometer has a measurement beam exit port for transmitting the measurement beam and a reference beam exit port for transmitting the reference beam.

[0039] Preferably, the area of ​​the measuring spot and the reference spot is not less than 0.1 square millimeters and not more than 1 square millimeter.

[0040] Preferably, the length of the light-shielding channel is 3 to 7 cm and the diameter is 1 to 2 cm.

[0041] Preferably, the optical path of the measuring beam is provided with an optical path difference fine-tuning component;

[0042] The optical path difference fine-tuning component includes a hollow, closed glass container with flat, transparent ends, the end faces of which are perpendicular to the measuring beam. A gas supply pipe connects the inside and outside of the glass container. The component also includes a gas compressor, connected to the gas supply pipe, which in turn is connected to a gas source containing a mixture of 30% trifluoroiodomethane and 70% nitrogen. The gas compressor injects or extracts the mixture into the glass container via the supply pipe, adjusting the gas pressure inside. Trifluoroiodomethane has a much higher refractive index than nitrogen. Mixing it with nitrogen significantly increases the refractive index-pressure coefficient of the gas mixture, meaning that the same pressure change can cause a larger optical path change, making fine-tuning more sensitive and effective.

[0043] Preferably, the cross-sectional area of ​​the inner cavity of the glass container is between 5 and 10 square centimeters; and the length of the glass container is between 5 and 15 centimeters.

[0044] In summary, the present invention has the following beneficial effects:

[0045] 1. The recessed part of the guide vane to be tested is relatively deep and has a smooth surface. The light-absorbing tube is inserted into the recessed part of the vane, blocking the inclined wall of the recessed part. The bottom of the recessed part of the vane is exposed through the opening, so that the measurement beam and reference beam of the laser interferometer can be projected onto the bottom surface of the recessed part of the vane without obstruction. By setting the light-absorbing tube to eliminate the light interference caused by secondary reflection, a clearer interference image is obtained. After one clamping and positioning, the bottom of the recessed part of the vane can be completely and accurately measured without repeatedly changing the detection angle of the laser interferometer.

[0046] 2. This patent application eliminates the fixed reference mirror in traditional laser interferometers and uses the bottom surface of the groove in the concave part of the leaf crown as the reflecting surface of the measuring beam and the reference beam. Since the two beams scan synchronously, any common displacement or angular change has a synchronous and equal effect on the two optical paths. Therefore, the optical path difference between the measuring beam and the reference beam changes synchronously and is almost unaffected by slight changes in the position between the laser interferometer and the bottom surface of the groove in the concave part of the leaf crown. This avoids the problem of irregular jumps in interference imaging during the scanning process, so as to accurately scan the location of tiny damage. Theoretically, the scanning accuracy can be at the level of several micrometers or even nanometers. Attached Figure Description

[0047] Figure 1This is a schematic diagram of the overall structure of the non-destructive testing device for the groove bottom of the concave area of ​​the guide vane crown according to the present invention.

[0048] Figure 2 This is a schematic diagram of the overall rear view of the non-destructive testing device of the present invention, which is applied to the bottom of the groove in the concave area of ​​the guide vane crown.

[0049] Figure 3 The present invention relates to a non-destructive testing device for the bottom of the groove in the concave area of ​​the guide vane crown. Figure 2 Enlarged structural diagram at point A in the middle;

[0050] Figure 4 The present invention relates to a non-destructive testing device for the bottom of the groove in the concave area of ​​the guide vane crown. Figure 2 Enlarged structural diagram at point B;

[0051] Figure 5 This is a schematic diagram illustrating the structure of the non-destructive testing device for the groove bottom of the concave area of ​​the guide vane crown, as described in this invention.

[0052] Figure 6 This is a schematic diagram illustrating the structure of the non-destructive testing device for the bottom of the groove in the concave area of ​​the guide vane crown, as described in this invention, which is used to demonstrate the optical fiber.

[0053] Figure 7 This is a schematic diagram illustrating the structure of the reflector in the non-destructive testing device of the present invention, which is applied to the bottom of the groove in the concave area of ​​the guide vane crown.

[0054] In the figure, 1. Loading support; 2. Guide vane to be tested; 3. Leaf crown; 4. Fixture; 5. Light-absorbing tube; 6. Laser interferometer; 7. Gimbal; 8. Hydraulic lifting device; 9. Plate-shaped support; 10. Glass container; 11. Light-shielding channel; 12. Optical fiber; 13. Converging lens; 14. Reflector. Detailed Implementation

[0055] To make the technical means, creative features, objectives and effects of the invention easier to understand, the invention will be further explained below with reference to specific illustrations.

[0056] refer to Figures 1 to 7 A non-destructive testing device for the bottom of the groove in the concave area of ​​the guide vane crown includes a loading support 1, on which a clamp 4 is provided to hold the guide vane 2 to be tested. The clamp 4 is a clamp that keeps the guide vane 2 to be tested horizontally.

[0057] The guide vane 2 to be tested has a crown 3, and the concave part of the crown 3 points forward;

[0058] It also includes a hollow light-absorbing tube 5 with openings at both ends, the inner wall of which is made of black frosted surface;

[0059] The outer contour of the light-absorbing tube 5 is adapted to the inner contour of the recessed part of the leaf crown 3, and the light-absorbing tube 5 is inserted into the recessed part;

[0060] The bottom of the groove in the concave part of the leaf crown 3 is exposed through the opening at the bottom of the light-absorbing tube 5;

[0061] A laser interferometer 6 is installed on the front side of the loading support 1;

[0062] The laser interferometer 6 is equipped with a beam splitter, which splits the incident beam into a measurement beam and a reference beam.

[0063] The angle between the measuring beam and the reference beam in the vertical direction is between 3 and 12 degrees;

[0064] The measuring beam and the reference beam are projected onto the bottom of the groove in the concave part of the leaf crown 3, forming the measuring spot and the reference spot, and are reflected by the bottom of the groove in the concave part of the leaf crown 3 to form two reflected beams;

[0065] The laser interferometer 6 also includes two light-shielding channels 11, which are parallel to the pointing directions of the measurement beam and the reference beam, respectively.

[0066] The light-shielding channel 11 adopts a straight circular tube inner wall, and the straight circular tube inner wall is coated with a graphite frosted coating;

[0067] The laser interferometer 6 also includes two optical components for adjusting the angle of light, which are respectively located behind the two light-shielding channels 11;

[0068] The two optical components adjust the return beams transmitted by the two light-blocking channels 11 to perform interference imaging.

[0069] The laser interferometer 6 is mounted on a gimbal 7, and a vertically lifting hydraulic lifting device 8 is installed below the gimbal 7.

[0070] The rotation center of the gimbal 7 coincides with the arc center of the recessed part.

[0071] In the above design, the recessed part of the crown 3 of the guide vane 2 to be tested is relatively deep and has a smooth surface. The light-absorbing tube 5 is inserted into the recessed part of the crown 3, blocking the inclined wall surface of the recessed part of the crown 3. The bottom of the groove of the recessed part of the crown 3 is exposed through the opening, so that the measurement beam and reference beam of the laser interferometer 6 can be projected onto the bottom surface of the groove of the recessed part of the crown 3 without obstruction. By setting the light-absorbing tube 5 to eliminate the light interference caused by secondary reflection, a clearer interference image is obtained. After one clamping and positioning, the bottom of the groove of the recessed part of the crown 3 can be completely and accurately measured without repeatedly changing the detection angle of the laser interferometer 6.

[0072] Traditional laser interferometer 6 is a high-precision measuring instrument based on the principle of interference. During the scanning process, it is unavoidable that there will be relative displacement and relative angle changes between the laser interferometer 6 and the bottom of the groove in the recessed part of the leaf crown 3, at least at the micrometer level. This will cause irregular jumps in the interference fringes, making it impossible to scan the real defect area.

[0073] This patent application eliminates the fixed reference mirror in the traditional laser interferometer 6, and uses the bottom surface of the groove in the concave part of the leaf crown 3 as the reflecting surface of the measuring beam and the reference beam. Since the two beams are scanned synchronously, any common displacement or angular change has a synchronous and equal effect on the two optical paths. Therefore, the optical path difference between the measuring beam and the reference beam changes synchronously and is almost unaffected by the slight positional changes between the laser interferometer 6 and the bottom surface of the groove in the concave part of the leaf crown 3. This avoids the problem of irregular jumps in interference imaging during the scanning process, so as to accurately scan the location of tiny damage. Theoretically, the scanning accuracy can be at the level of several micrometers or even nanometers.

[0074] The reference beam and the measurement beam form light spots reflected at the bottom of the groove in the concave part of the leaf crown 3, which serve as a reference for each other. By comparing and verifying the bottom of the groove in the concave part of the leaf crown 3 at different positions, a self-reference measurement system is formed. This system can accurately and reliably identify interference fringe anomalies caused by minor defects, so as to intuitively and quickly detect damage to the surface of the groove bottom in the concave part of the leaf crown 3.

[0075] By setting up a light-shielding channel 11 with a graphite frosted coating, only reflected light rays that are nearly parallel to the direction of the light-shielding channel 11 can pass through. Light rays with a large angle difference will be absorbed by the graphite frosted coating, reducing the influence of stray light on interference imaging.

[0076] Because the orientation of the two light-shielding channels 11 is fixed, an optical component is set to adjust the angle of the light. The optical component system is formed by combining an optical fiber 12 and a converging lens 13. The light outlet of the light-shielding channel 11 is directly opposite the light inlet of the optical fiber 12. The converging lens 13 is located behind the light outlet of the optical fiber 12. The reflected light from the light-shielding channel 11 enters the optical fiber 12 through the light inlet and exits through the light outlet of the optical fiber 12. After passing through the converging lens 13, it is projected onto the grating. The optical component system can also be formed by combining a reflector and a converging lens 13. The reflector is located behind the light-shielding channel 11. The reflected light from the light-shielding channel 11 is reflected by the reflector to form a beam. The converging lens 13 is located on the optical path of the beam. The beam of light passing through the converging lens 13 is projected onto the grating.

[0077] For qualified recessed areas, no significant change in optical path difference occurs during the scanning process of the measuring beam and the reference beam. When the change in optical path difference shown in the interference image is greater than the set amplitude, it is considered that a defect has been detected.

[0078] ReferenceFigures 1 to 3 A vertical plate-shaped bracket 9 is mounted on the loading support 1, and the light-absorbing tube 5 is fixed on the plate-shaped bracket 9. The plate-shaped bracket 9 supports the light-absorbing tube 5, so that the light-absorbing tube 5 remains stable during the flaw detection process.

[0079] The wall thickness of the light-absorbing tube 5 is between 0.1 and 0.5 cm.

[0080] The laser interferometer 6 has a measurement beam exit port for transmitting the measurement beam and a reference beam exit port for transmitting the reference beam.

[0081] The area of ​​the measuring spot and the reference spot shall be no less than 0.1 square millimeters and no more than 1 square millimeter.

[0082] The length of the light-shielding channel 11 is 3 to 7 cm, and the diameter is 1 to 2 cm.

[0083] An optical path difference fine-tuning component is provided in the optical path of the measuring beam. This component includes a hollow, closed glass container 10 with flat, transparent ends, and the end faces of the container perpendicular to the measuring beam. A gas supply pipe connects the inside and outside of the glass container 10. The component also includes a gas compressor, connected to the gas supply pipe, which in turn is connected to a gas source containing a mixture of 30% trifluoroiodomethane and 70% nitrogen. The gas compressor injects or extracts the mixture into or from the glass container 10 via the gas supply pipe, adjusting the gas pressure within the container. Trifluoroiodomethane is a gas with a much higher refractive index than nitrogen. Mixing it with nitrogen significantly increases the refractive index-pressure coefficient of the gas mixture, meaning that the same pressure change can cause a larger change in optical path, making fine-tuning more sensitive and effective.

[0084] The cross-sectional area of ​​the inner cavity of the glass container 10 is between 5 and 10 square centimeters; the length of the glass container 10 is between 5 and 15 centimeters.

[0085] In use, the guide vane 2 to be tested is fixed to the loading support 1 by the clamp 4. The guide vane 2 to be tested is placed horizontally, and the concave part of the crown 3 points forward. The light-absorbing tube 5 fixed on the plate-shaped bracket is inserted into the concave part of the crown 3 to block the inclined wall of the concave part of the crown 3. The bottom of the groove of the concave part of the crown 3 is exposed through the opening.

[0086] The measurement beam and reference beam of the laser interferometer 6 are projected onto the bottom surface of the groove in the concave part of the leaf crown 3 without obstruction. The bottom surface of the groove in the concave part of the leaf crown 3 serves as the reflecting surface of the measurement beam and the reference beam to perform interference imaging. The light-absorbing tube 5 eliminates the light interference caused by secondary reflection.

[0087] The pressure of the gas source, which is a mixture of 30% trifluoroiodomethane and 70% nitrogen, inside the glass container 10 is adjusted to correct the optical path difference and obtain a standard and clear interference image.

[0088] The gimbal 7 and the hydraulic lifting device 8 work together, and the laser interferometer 6 rotates and scans to obtain multiple sets of interference images. For qualified recessed parts, no obvious change in optical path difference occurs during the scanning process of the measuring beam and the reference beam. When the change in optical path difference shown in the interference image is greater than the set amplitude, it is considered that a defect has been detected.

[0089] The foregoing has shown and described the basic principles, main features, and advantages of the invention. Those skilled in the art should understand that the invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection of the invention is defined by the appended claims and their equivalents.

Claims

1. A non-destructive testing device for the bottom of the groove in the concave area of ​​a guide vane crown, comprising a loading support (1), wherein the loading support (1) is provided with a clamp (4) for holding the guide vane (2) to be tested, characterized in that: The clamp (4) is a clamp (4) that holds the guide vane (2) to be tested horizontally. The guide vane (2) to be tested has a leaf crown (3); It also includes a hollow light-absorbing tube (5) with openings at both ends, the inner wall of which is made of black frosted surface; The outer contour of the light-absorbing tube (5) is adapted to the inner contour of the recessed part of the leaf crown (3), and the light-absorbing tube (5) is inserted into the recessed part; The bottom of the groove in the concave part of the leaf crown (3) is exposed through the opening at the bottom of the light-absorbing tube (5); A laser interferometer (6) is provided on the front side of the loading support (1); The recessed portion of the leaf crown (3) faces the laser interferometer (6); The laser interferometer (6) is equipped with a beam splitter, which splits the incident beam into a measurement beam and a reference beam; The angle between the measuring beam and the reference beam in the vertical direction is between 3 and 12 degrees; The measuring beam and the reference beam are projected onto the bottom of the groove in the concave part of the leaf crown (3) to form a measuring spot and a reference spot, and are reflected by the bottom of the groove in the concave part of the leaf crown (3) to form two reflected beams; The laser interferometer (6) also includes two light-shielding channels (11), which are parallel to the pointing directions of the measurement beam and the reference beam, respectively. The light-shielding channel (11) adopts a straight circular tube inner wall, and the straight circular tube inner wall adopts a graphite frosted coating; The laser interferometer (6) also includes two optical components for adjusting the angle of light, which are respectively located behind the two light-shielding channels (11); The two optical components adjust the return beams transmitted by the two light-blocking channels (11) respectively, and then perform interference imaging; The laser interferometer (6) is mounted on a gimbal (7), and a vertically lifting hydraulic lifting device (8) is mounted below the gimbal (7); The rotation center of the gimbal (7) overlaps with the arc center of the concave part.

2. The non-destructive testing device for the groove bottom of the concave area of ​​the guide vane crown as described in claim 1, characterized in that: For qualified recessed areas, no significant change in optical path difference occurs during the scanning process of the measuring beam and the reference beam. When the change in optical path difference shown in the interference image is greater than the set amplitude, it is considered that a defect has been detected.

3. The non-destructive testing device for the groove bottom of the concave area of ​​the guide vane crown as described in claim 1, characterized in that: A vertical plate-shaped bracket (9) is mounted on the loading support (1), and the light-absorbing tube (5) is fixed on the plate-shaped bracket (9).

4. The non-destructive testing device for the groove bottom of the concave area of ​​the guide vane crown as described in claim 1, characterized in that: The wall thickness of the light-absorbing tube (5) is between 0.1 and 0.5 cm.

5. The non-destructive testing device for the groove bottom of the concave area of ​​the guide vane crown according to claim 1, characterized in that: The laser interferometer (6) has a measurement beam exit port that transmits the measurement beam and a reference beam exit port that transmits the reference beam.

6. The non-destructive testing device for the groove bottom of the concave area of ​​the guide vane crown according to claim 1, characterized in that: The area of ​​the measuring spot and the reference spot is not less than 0.1 square millimeters and not more than 1 square millimeter.

7. The non-destructive testing device for the groove bottom of the concave area of ​​the guide vane crown according to claim 1, characterized in that: The length of the light-shielding channel (11) is 3 to 7 cm and the diameter is 1 to 2 cm.

8. The non-destructive testing device for the groove bottom of the concave area of ​​the guide vane crown according to claim 1, characterized in that: The optical path of the measurement beam is equipped with an optical path difference fine adjustment component; The optical path difference fine adjustment component includes a hollow glass container (10) with closed ends. The glass container (10) has flat and transparent ends, and the end faces of the glass container (10) are perpendicular to the measuring beam. The glass container (10) is provided with a gas supply pipe that connects the inside and outside of the glass container (10); The optical path difference fine-tuning component also includes a gas compressor, with a gas supply pipe connected to the gas compressor, which is connected to a gas source containing a mixture of 30% trifluoroiodomethane and 70% nitrogen.

9. The non-destructive testing device for the bottom of the groove in the concave area of ​​the guide vane crown according to claim 8, characterized in that: The cross-sectional area of ​​the inner cavity of the glass container (10) is between 5 and 10 square centimeters; the length of the glass container (10) is between 5 and 15 centimeters.

Images