High-precision non-contact measurement method for measuring size of large-scale part of steam turbine and measurement system for realizing high-precision non-contact measurement method

Abstract

The invention discloses a high-precision non-contact measurement method for the size of a large part of a steam turbine and a measurement system for implementing the method, and belongs to the technical field of size measurement of the large part of the steam turbine. The method solves the technical problems that an existing method for measuring the size of a large part of a steam turbine is relatively traditional, depends on manpower to a large extent, and cannot meet the requirements for high precision and digital automation of measurement at present. Comprising the following steps: arranging a measurement system; laser scanning measurement equipment is arranged at one axial end of the to-be-measured large part; laser emitted by the laser scanning measurement equipment is reflected by the plane mirror by using a movement mechanism and then can irradiate a surface to be measured; determining the spatial position of the plane mirror in the current attitude; obtaining mirror point cloud data; converting and calculating the mirror point cloud data into entity point cloud data; and calculating to obtain the size of the to-be-measured steam turbine large part. And the accessibility of laser measurement is improved. The method is used for measuring the sizes of the large parts of the steam turbine.

Description

Technical Field

[0001] This invention relates to a high-precision non-contact measurement method for the dimensions of large steam turbine components and a measurement system for implementing the method, belonging to the field of measurement technology for the dimensions of large steam turbine components. Background Technology

[0002] Currently, the company mainly relies on traditional measuring tools or laser trackers for measuring large turbine components. Conventional measuring tools are used during the machining of large components, but due to their large size, these tools have poor accuracy and require highly experienced and skilled personnel. Furthermore, they cannot measure spatial dimensions. During the assembly of large components, laser trackers are used to measure flow dimensions. This method requires manual placement of the target ball at the measurement location using tooling, followed by the laser tracker's placement on a guide rail. This process is cumbersome, requires high stability from manual target ball installation, and involves working at heights in some areas due to the large size of the components, posing safety risks. Additionally, the laser tracker needs to be constantly moved along the guide rail, requiring a relocation each time, which affects measurement accuracy and efficiency.

[0003] In summary, existing methods for measuring the dimensions of large turbine components are relatively traditional, rely heavily on manual labor, and cannot meet the current technical requirements for high-precision and digital automation in measurement. Summary of the Invention

[0004] This invention addresses the technical problem that existing methods for measuring the dimensions of large steam turbine components are relatively traditional, heavily reliant on manual labor, and unable to meet current demands for high precision and digital automation. Therefore, it proposes a high-precision non-contact measurement method for the dimensions of large steam turbine components, comprising the following steps:

[0005] S1. Arrange a measurement system, the measurement system including a laser scanning measurement device, a plane mirror for changing the optical path, and a motion mechanism for adjusting the spatial position and attitude of the plane mirror;

[0006] S2. Set the laser scanning measurement equipment at one end of the axial direction of the large component to be measured;

[0007] S3. Using the motion mechanism, the plane mirror is moved and rotated to a predetermined position and angle, so that the laser emitted by the laser scanning measurement device can illuminate the surface to be measured after being reflected by the plane mirror.

[0008] S4. Determine the spatial position of the plane mirror in the current attitude;

[0009] S5. The laser scanning measurement equipment measures the surface to be measured through a plane mirror to obtain mirror point cloud data;

[0010] S6. Based on the spatial position of the planar mirror determined in S4 under the current attitude, convert the mirror point cloud data into solid point cloud data.

[0011] S7. Based on the entity point cloud data, the dimensions of large turbine components are calculated.

[0012] As another improvement to the present invention, the determination of the spatial position of the plane mirror in the current attitude described in S4 adopts a direct measurement method, specifically including:

[0013] S411. Use the laser scanning measurement device to scan the non-reflective area of ​​the plane mirror to obtain a scanned point cloud;

[0014] S412. Perform plane fitting on the scanned point cloud, and the fitted plane is the spatial position of the determined plane mirror in the current attitude.

[0015] As another improvement of the present invention, the least squares method is used when performing plane fitting on the scanned point cloud.

[0016] As another improvement to the present invention, the determination of the spatial position of the plane mirror in the current attitude described in S4 employs a first indirect measurement method, specifically including:

[0017] S421. Place a standard steel ball within the reflected field of view of the plane mirror.

[0018] S422. Use a laser scanning measuring device to directly measure the standard steel ball to obtain the coordinates of the center of the solid ball;

[0019] S423. Use a laser scanning measuring device to measure the standard steel ball through a plane mirror to obtain the coordinates of the mirrored sphere's center.

[0020] S424. Calculate the line connecting the center of the solid sphere and the center of the mirror sphere in step S423, and find the first vertical bisecting plane of the line. The first vertical bisecting plane is the spatial position of the determined plane mirror in the current posture.

[0021] As another improvement to the present invention, the determination of the spatial position of the plane mirror in the current attitude described in S4 employs a second indirect measurement method, specifically including:

[0022] S431. A plane mirror and at least three standard steel balls are fixedly connected to a rigid support to form a measuring assembly;

[0023] S432. Use a laser scanning measuring device to directly measure the at least three standard steel balls to obtain the coordinates of the solid centers of the at least three standard steel balls;

[0024] S433. Use a laser scanning measuring device to measure the at least three standard steel balls through a plane mirror to obtain the mirror center coordinates of the at least three standard steel balls;

[0025] S434. Calculate the line connecting the center of each solid sphere to the center of its corresponding mirror sphere in step S433, and find the second vertical bisecting plane of each line.

[0026] S435. The midpoint is averaged to obtain the calculated third vertical midpoint, which is the spatial position of the determined plane mirror in the current attitude.

[0027] As another improvement of the present invention, the motion mechanism is one of a guide rail, a robotic arm, or a three-axis CNC platform.

[0028] As another improvement of the present invention, the planar reflector is a planar metal-coated reflector.

[0029] As another improvement to the present invention, the size of the planar metal-coated reflector is not less than... The global accuracy of the entire mirror surface of the planar metal-coated reflector is less than 0.5μm.

[0030] The present invention also provides a measurement system comprising:

[0031] Laser scanning measurement equipment is used to emit a measurement laser and receive the return signal to generate point cloud data;

[0032] A plane mirror is used to change the optical path of the measuring laser.

[0033] The motion mechanism is used to adjust the movement and rotation of the plane mirror in space;

[0034] The control system, electrically connected to the laser scanning measurement equipment and the motion mechanism, is configured as follows:

[0035] Control the motion mechanism to adjust the plane mirror to the predetermined posture;

[0036] Perform calibration calculations for the spatial position of the plane mirror;

[0037] The laser scanning measurement equipment is controlled to measure via a plane mirror;

[0038] Receive mirror point cloud data and convert it into entity point cloud data;

[0039] The dimensions of large components of the steam turbine under test are calculated based on entity point cloud data.

[0040] As another improvement of the present invention, the measuring component includes a rigid bracket, a plane mirror fixed on the rigid bracket, and at least three standard steel balls fixed on the rigid bracket.

[0041] The beneficial effects of this invention are:

[0042] This patent provides a high-precision non-contact measurement method that overcomes the shortcomings of traditional measuring tools and contact-based measurements used in the dimensional measurement of large turbine components. It boasts strong versatility, and with auxiliary tooling such as reflectors, significantly improves the accessibility of laser measurement. It can be adapted to the dimensional measurement of large components of different specifications and types, ensuring the accuracy and stability of the measurement results. Furthermore, this patented method can be further equipped with related automated hardware and software to form an automated measurement system, realizing the automated measurement of the dimensions of large turbine components.

[0043] A movable and rotatable high-precision planar reflector is introduced as an optical path steering device, which enables a fixed lidar to measure hidden, complex, or high-altitude areas that were originally inaccessible by the direct optical path through the "extension" of the reflector, fundamentally solving the accessibility problem of measuring large components. Attached Figure Description

[0044] Figure 1 This is a measurement diagram of a motion mechanism using a guide rail structure. Detailed Implementation

[0045] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the positional relationships indicated by terms such as "upper," "lower," "left," "right," "first," and "second" are only based on the positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention, and are not intended to indicate or imply that the referred components have a specific orientation, or are constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0046] Specific implementation method one: Combining Figure 1 This embodiment describes a high-precision non-contact measurement method for the dimensions of large steam turbine components, comprising the following steps:

[0047] S1. Arrange a measurement system, the measurement system including a laser scanning measurement device, a plane mirror for changing the optical path, and a motion mechanism for adjusting the spatial position and attitude of the plane mirror;

[0048] S2. Set the laser scanning measurement equipment at one end of the axial direction of the large component to be measured;

[0049] S3. Using the motion mechanism, the plane mirror is moved and rotated to a predetermined position and angle, so that the laser emitted by the laser scanning measurement device can illuminate the surface to be measured after being reflected by the plane mirror.

[0050] S4. Determine the spatial position of the plane mirror in the current attitude;

[0051] S5. The laser scanning measurement equipment measures the surface to be measured through a plane mirror to obtain mirror point cloud data;

[0052] S6. Based on the spatial position of the planar mirror determined in S4 under the current attitude, convert the mirror point cloud data into solid point cloud data.

[0053] S7. Based on the entity point cloud data, calculate the dimensions of the large components of the turbine to be tested.

[0054] This method is used to measure the diameter of the inner bore of a steam turbine high-pressure cylinder. Step 1: Place the laser scanner (LiDAR) at the adjustment end of the high-pressure cylinder, with the laser path exit near the axis. Step 2: Set up a guide rail and a movable base. The reflector is mounted on the movable base, which can move along the guide rail and rotate 360 ​​degrees. The reflector uses an outer ring polished structure. Step 3: Adjust the reflector to a 45° angle (slanted upwards) with the ground horizontal, and move it to the position of the inner bore to be measured. Step 4: Use the laser scanner (LiDAR) to scan the polished outer surface of the reflector. Use the least squares method to fit a plane, which is the spatial position of the reflector. Step 5: Use the laser scanner (LiDAR) to measure and collect point cloud data of the surface above the inner bore through the reflector. Step 6: Calculate the solid point cloud data of the surface above the inner bore from the obtained mirrored point cloud data using the spatial position of the reflector. Step 7: Repeat steps 3 to 6, pointing the reflector at 45° to the left, right, and down respectively, and measure the solid point cloud data of the left, right, and bottom surfaces of the inner hole to be measured. Fit all the point cloud data of the inner hole to be measured into a cylinder using the least squares method. The diameter of this cylinder is the diameter of the inner hole to be measured.

[0055] Specific Implementation Method Two: Combining Figure 1 This embodiment differs from specific embodiment one in that, in step S4, determining the spatial position of the plane mirror in the current attitude uses a direct measurement method, specifically including:

[0056] S411. Use the laser scanning measurement device to scan the non-reflective area of ​​the plane mirror to obtain a scanned point cloud;

[0057] S412. Perform plane fitting on the scanned point cloud, and the fitted plane is the spatial position of the determined plane mirror in the current attitude.

[0058] Specific implementation method three: Combining Figure 1 This embodiment differs from Specific Embodiment 1 in that it uses the least squares method when performing plane fitting on the scanned point cloud.

[0059] Specific implementation method four: Combination Figure 1 This embodiment differs from specific embodiment one in that, in step S4, determining the spatial position of the plane mirror in the current attitude employs a first indirect measurement method, specifically including:

[0060] S421. Place a standard steel ball within the reflected field of view of the plane mirror.

[0061] S422. Use a laser scanning measuring device to directly measure the standard steel ball to obtain the coordinates of the center of the solid ball;

[0062] S423. Use a laser scanning measuring device to measure the standard steel ball through a plane mirror to obtain the coordinates of the mirrored sphere's center.

[0063] S424. Calculate the line connecting the center of the solid sphere and the center of the mirror sphere in step S423, and find the first vertical bisecting plane of the line. The first vertical bisecting plane is the spatial position of the determined plane mirror in the current posture.

[0064] Specific Implementation Method Five: Combining Figure 1 This embodiment differs from specific embodiment one in that, in step S4, determining the spatial position of the plane mirror in the current attitude employs a second indirect measurement method, specifically including:

[0065] S431. A plane mirror and at least three standard steel balls are fixedly connected to a rigid support to form a measuring assembly;

[0066] S432. Use a laser scanning measuring device to directly measure the at least three standard steel balls to obtain the coordinates of the solid centers of the at least three standard steel balls;

[0067] S433. Use a laser scanning measuring device to measure the at least three standard steel balls through a plane mirror to obtain the mirror center coordinates of the at least three standard steel balls;

[0068] S434. Calculate the line connecting the center of each solid sphere to the center of its corresponding mirror sphere in step S433, and find the second vertical bisecting plane of each line.

[0069] S435. The midpoint is averaged to obtain the calculated third vertical midpoint, which is the spatial position of the determined plane mirror in the current attitude.

[0070] Since the reflector and the standard steel ball are fixed on the same rigid support, their physical relative positions remain unchanged, and the device functions as a single unit. Therefore, the center of the standard steel ball can be measured using laser scanning (LiDAR), thereby obtaining the spatial position of the reflector.

[0071] Specific Implementation Method Six: Combination Figure 1 This embodiment differs from Specific Embodiment 1 in that the motion mechanism is one of a guide rail, a robotic arm, or a three-axis CNC platform. This design satisfies various design requirements and operating environments.

[0072] Specific implementation method seven: Combination Figure 1 This embodiment differs from specific embodiment one in that the plane mirror is a plane metal-coated mirror. This design is intended to improve measurement accuracy.

[0073] Specific implementation method eight: Combination Figure 1 This embodiment differs from specific embodiment one in that the size of the planar metal-coated reflector is not less than [a certain value]. The global accuracy of the planar metal-coated mirror is less than 0.5 μm. This design aims to improve measurement accuracy.

[0074] Specific Implementation Method Nine: Combining Figure 1 This embodiment describes a measurement system that includes:

[0075] A laser scanning measurement device is used to emit a measurement laser and receive the return signal to generate point cloud data; the laser scanning measurement device adopts the MV430 model.

[0076] A plane mirror is used to change the optical path of the measuring laser.

[0077] The motion mechanism is used to adjust the movement and rotation of the plane mirror in space. Depending on the type and structure of the components, a suitable support and motion mechanism is selected, such as a guide rail / robotic arm / three-axis CNC platform + movable base, etc., to place the mirror. The motion mechanism can move the mirror in space and rotate the mirror 360° to change the measurement laser path so that it can illuminate the desired measurement position for measurement.

[0078] The control system, electrically connected to the laser scanning measurement equipment and the motion mechanism, is configured as follows:

[0079] Control the motion mechanism to adjust the plane mirror to the predetermined posture;

[0080] Perform calibration calculations for the spatial position of the plane mirror;

[0081] The laser scanning measurement equipment is controlled to measure via a plane mirror;

[0082] Receive mirror point cloud data and convert the received mirror point cloud data into entity point cloud data;

[0083] The dimensions of large components of the steam turbine under test are calculated based on entity point cloud data.

[0084] The basic measuring equipment employs laser scanning (LiDAR), utilizing non-contact, precise laser measurement technology to overcome the limitations of traditional large and portable metrology systems. It directly illuminates the surface being measured with a laser, acquiring the three-dimensional coordinates of the illuminated point without the need for auxiliary tooling such as target balls or probes. For highly reflective surfaces such as finished metal surfaces, no surface treatment (such as powder coating to reduce reflectivity) is required, allowing for direct measurement. It features both single-point measurement and area scanning capabilities.

[0085] Based on existing experience in measuring the dimensions of large steam turbine components, non-contact laser measurement technology, coupled with auxiliary tooling such as reflectors and guide rails, is employed to improve the accessibility of laser measurement. A universal measurement method is developed for large components of different specifications and types, enabling high-precision dimensional measurement and ensuring the accuracy and stability of the results. Furthermore, the measurement method is convenient and efficient, and can be further developed into an automated measurement system with relevant automated hardware and software to achieve automated measurement of the dimensions of large steam turbine components.

[0086] Specific Implementation Method Ten: Combining Figure 1 This embodiment differs from specific embodiment nine in that it further includes a measuring component. The measuring component comprises a rigid support, a plane mirror fixed to the rigid support, and at least three standard steel balls fixed to the rigid support. The rigid support is fabricated, the mirror is fixed in the middle of the support, and at least three standard steel balls (with micrometer-level precision) are fixedly installed on the outer ring of the support. The solid center and mirror center of each standard steel ball are measured using indirect measurement method 2, and the vertical bisecting plane of the line connecting the centers is calculated. The planes are then averaged to obtain the final vertical bisecting plane, which is the plane of the mirror. This allows the determination of the geometric relationship between the center of the standard steel ball on the support and the plane of the mirror.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-precision non-contact measurement method for the dimensions of large components in steam turbines, characterized in that, Includes the following steps: S1. Arrange a measurement system, the measurement system including a laser scanning measurement device, a plane mirror for changing the optical path, and a motion mechanism for adjusting the spatial position and attitude of the plane mirror; S2. Set the laser scanning measurement equipment at one end of the axial direction of the large component to be measured; S3. Using the motion mechanism, the plane mirror is moved and rotated to a predetermined position and angle, so that the laser emitted by the laser scanning measurement device can illuminate the surface to be measured after being reflected by the plane mirror. S4. Determine the spatial position of the plane mirror in the current attitude; S5. The laser scanning measurement equipment measures the surface to be measured through a plane mirror to obtain mirror point cloud data; S6. Based on the spatial position of the planar mirror determined in S4 under the current attitude, convert the mirror point cloud data into solid point cloud data. S7. Based on the entity point cloud data, calculate the dimensions of the large components of the turbine to be tested.

2. The high-precision non-contact measurement method for the dimensions of large steam turbine components according to claim 1, characterized in that, The method described in S4 for determining the spatial position of the plane mirror in its current orientation uses a direct measurement method, specifically including: S411. Use the laser scanning measurement device to scan the non-reflective area of ​​the plane mirror to obtain a scanned point cloud; S412. Perform plane fitting on the scanned point cloud, and the fitted plane is the spatial position of the determined plane mirror in the current attitude.

3. The high-precision non-contact measurement method for the dimensions of large steam turbine components according to claim 2, characterized in that, The least squares method is used when performing plane fitting on the scanned point cloud.

4. The high-precision non-contact measurement method for the dimensions of large steam turbine components according to claim 1, characterized in that, The determination of the spatial position of the plane mirror in the current attitude, as described in S4, employs a first indirect measurement method, specifically including: S421. Place a standard steel ball within the reflected field of view of the plane mirror. S422. Use a laser scanning measuring device to directly measure the standard steel ball to obtain the coordinates of the center of the solid ball; S423. Use a laser scanning measuring device to measure the standard steel ball through a plane mirror to obtain the coordinates of the mirrored sphere's center. S424. Calculate the line connecting the center of the solid sphere and the center of the mirror sphere in step S423, and find the first vertical bisecting plane of the line. The first vertical bisecting plane is the spatial position of the determined plane mirror in the current posture.

5. A high-precision non-contact measurement method for the dimensions of large steam turbine components according to claim 1, characterized in that, The determination of the spatial position of the plane mirror in the current attitude, as described in S4, employs a second indirect measurement method, specifically including: S431. A plane mirror and at least three standard steel balls are fixedly connected to a rigid support to form a measuring assembly; S432. Use a laser scanning measuring device to directly measure the at least three standard steel balls to obtain the coordinates of the solid centers of the at least three standard steel balls; S433. Use a laser scanning measuring device to measure the at least three standard steel balls through a plane mirror to obtain the mirror center coordinates of the at least three standard steel balls; S434. Calculate the line connecting the center of each solid sphere to the center of its corresponding mirror sphere in step S433, and find the second vertical bisecting plane of each line. S435. The midpoint is averaged to obtain the calculated third vertical midpoint, which is the spatial position of the determined plane mirror in the current attitude.

6. A high-precision non-contact measurement method for the dimensions of large turbine components according to any one of claims 1 to 5, wherein the motion mechanism is one of a guide rail, a robotic arm, or a three-axis CNC platform.

7. A high-precision non-contact measurement method for the dimensions of large components of steam turbines according to any one of claims 1 to 5, wherein the plane reflector is a plane metal-coated reflector.

8. The high-precision non-contact measurement method for the dimensions of large turbine components according to claim 7, wherein the size of the planar metal-coated reflector is not less than... The global accuracy of the entire mirror surface of the planar metal-coated reflector is less than 0.5μm.

9. A measurement system, said measurement system being used to implement the high-precision non-contact measurement method for the dimensions of large steam turbine components as described in claim 1, characterized in that... It includes: Laser scanning measurement equipment is used to emit a measurement laser and receive the return signal to generate point cloud data; A plane mirror is used to change the optical path of the measuring laser. The motion mechanism is used to adjust the movement and rotation of the plane mirror in space; The control system, electrically connected to the laser scanning measurement equipment and the motion mechanism, is configured as follows: Control the motion mechanism to adjust the plane mirror to the predetermined posture; Perform calibration calculations for the spatial position of the plane mirror; The laser scanning measurement equipment is controlled to measure via a plane mirror; Receive mirror point cloud data and convert the received mirror point cloud data into entity point cloud data; The dimensions of large components of the steam turbine under test are calculated based on entity point cloud data.

10. A measurement system according to claim 9, characterized in that... It also includes a measuring component comprising a rigid support, a plane mirror fixed to the rigid support, and at least three standard steel balls fixed to the rigid support.

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