Method for measuring sealing surface of three-eccentric center butterfly valve

Abstract

The invention discloses a method for measuring a sealing surface of a three-eccentric center butterfly valve, and relates to the technical field of high-precision industrial measurement, and the method comprises the steps: constructing a virtual reference ring surface which is completely consistent with the design, and precisely mapping the point cloud data of the sealing surface of a valve plate obtained through actual scanning to a coordinate system of the reference ring surface through coordinate transformation, thereby achieving the measurement of the sealing surface of the three-eccentric center butterfly valve. The theoretical matching relation between the valve plate and the valve seat is accurately reproduced, a gap distribution data set is generated by calculating the normal distance of each actual data point relative to a virtual reference ring surface, at the moment, a negative value area in a gap field represents a theoretical interference contact area, and through analysis of the gap field, the theoretical interference contact area is calculated. According to the method, the potential contact state of the valve plate and the valve seat can be quantified in advance in a computer without physical dynamic assembly and pressure testing, and the dynamic wedge caulking process in the physical world is converted into static clearance calculation in a digital space, so that priori and non-destructive prediction of the sealing performance is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-precision industrial measurement, in particular to a kind of three eccentric butterfly valve sealing surface measurement method. BACKGROUND

[0002] Three eccentric butterfly valve as the core component in modern fluid control field, its core technical advantage is through the unique geometric design of axial, radial and conical angle eccentric, realize the zero friction separation of valve plate and valve seat in the process of opening and closing, and in the closed final state through wedge tight effect form metal to metal forced sealing, this design shows excellent sealing performance and long life in harsh conditions such as high temperature and high pressure, however, it is this complex spatial geometric relationship, the machining precision and matching quality of its valve plate and valve body sealing surface, become the most key factor to determine the performance and reliability of valve.

[0003] In the prior art, the measurement of the sealing surface of the three eccentric butterfly valve mainly relies on three coordinate measuring machines or special templates to detect the size and geometric tolerance of discrete points. These methods measure the valve plate or valve body separately in a static state, and cannot simulate and reflect the dynamic sealing state of the valve plate in the real closing process along its complex spatial trajectory and finally wedging with the valve seat. Moreover, they cannot accurately capture and quantify the micro-gap distribution on the entire sealing ring. It is these micro-gaps that determine the effectiveness of the seal, ultimately making the correspondence between the test results and the final performance ambiguous.

[0004] Therefore, developing a comprehensive measurement method that can accurately represent the actual contact state of the sealing surface of the three eccentric butterfly valve under simulated conditions and quantify it into intuitive and reliable performance indicators is of great significance for realizing quality control, process optimization and reliability guarantee of such valve manufacturing. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide a three eccentric butterfly valve sealing surface measurement method. It can construct a virtual reference ring surface that is identical to the design, and accurately map the point cloud data of the valve plate sealing surface obtained by actual scanning to the coordinate system of the reference ring surface using coordinate transformation. It can accurately reproduce the theoretical matching relationship between the valve plate and the valve seat. It can generate a gap distribution dataset by calculating the normal distance of each actual data point relative to the virtual reference ring surface. The negative value area in this gap field represents the theoretical interference contact area. Through analysis of the gap field, the present application can pre-quantify the potential state of valve plate and valve seat contact in the computer without physical dynamic assembly and pressure test. It can convert the dynamic wedging process in the physical world into static gap calculation based on accurate geometric model in digital space, thereby realizing the prior and non-destructive prediction of sealing performance.

[0006] The application provides the following technical solutions to solve the above technical problems: a kind of three eccentric butterfly valve sealing surface measurement method, the specific steps of this method are as follows: S100, according to the design parameters of three eccentric butterfly valve, a virtual reference torus conforming to the theoretical valve plate sealing surface is constructed in computer as the reference for subsequent data comparison; S200, the actual valve plate sealing surface is scanned using a non-contact three-dimensional measuring device, and a point cloud data set representing its three-dimensional topography is obtained; S300, the point cloud data set is mapped to the coordinate system of the virtual reference torus through coordinate transformation algorithm, and the normal distance of each data point to the reference torus is calculated , the set of normal distances is used as the gap distribution data set; S400, based on the preset effective sealing threshold , all data points with normal distance are selected from the sealing gap distribution data set, and the three-dimensional space region represented by these data points is fitted as an actual contact sealing ring belt; S500, based on the fitted actual contact sealing ring belt, the quantitative parameters for evaluating its sealing performance are calculated, including the continuity of the actual contact sealing ring belt and the maximum local gap value.

[0007] Further, in S100, the design parameters include the axial eccentricity, the radial eccentricity, the angular eccentricity, the nominal diameter of the sealing surface and the sealing ring belt width of the three eccentric butterfly valve; The geometric parameters of the virtual reference torus correspond one by one to the design parameters.

[0008] Further, the specific steps of obtaining the point cloud data set in S200 include: Scan planning and system calibration: according to the size of the valve plate and the spatial pose of the sealing surface, the moving path of the three-dimensional scanner is planned to ensure that the entire sealing surface area can be covered without collision and dead angle, and the three-dimensional scanner is calibrated using standard blocks to ensure that its measurement error within the calibration period is less than the allowable tolerance; Control the three-dimensional scanner to scan the valve plate sealing surface along the planned path, multiple views to fully cover the sealing surface, emit measurement beams and receive reflected signals, directly obtain the three-dimensional coordinates on the sealing surface, form multi-view point clouds; By identifying the positioning target points common in different view point clouds, the coordinate transformation matrix is calculated, and all multi-view point clouds are aligned and merged into a point cloud data set in a unified coordinate system; Filter the point cloud data set to identify and remove abnormal noise points caused by measurement noise.

[0009] Further, in S300, the coordinate transformation algorithm includes rigid transformation and eccentricity compensation transformation: Rigid transformations are used to translate and rotate the coordinate system of a point cloud dataset to align it with the coordinate system of a virtual reference toroidal surface. Eccentricity compensation transformation is used to correct spatial position deviations caused by triple eccentricity structures. A transformation matrix is ​​established based on the axial eccentricity, radial eccentricity, and angular eccentricity angle in the design parameters, and the point cloud data after rigid transformation is calibrated a second time.

[0010] Furthermore, in S300, the calculation process for the normal distance is as follows: S301. In a computer, the virtual reference torus is represented as a parametric surface: ,in For parameters on the surface The three-dimensional coordinate vector of the point. The circumferential parameter of the toroidal surface characterizes the position of the sealing surface along the circumferential direction. The radial parameter of the toroidal surface characterizes the radial position of the sealing surface. , , Points The X, Y, and Z coordinates in a three-dimensional coordinate system; S302. For any point in the point cloud dataset To find its position on the virtual reference toroidal surface Projection point on The parameters corresponding to this projection point are Minimize the point through numerical optimization algorithm To the surface Square distance to any point on Solving for the parameters that minimize the squared distance yields the solution. This parameter corresponds to the projection point. ; S303, Calculate the virtual reference torus at the projection point Normal vector at point ,in: along Tangent vector in parameter direction , indicating that the surface is Tangential direction along the circumferential direction; along Tangent vector in parameter direction , indicating that the surface is Tangential direction along the radial direction; normal vector It is calculated by the cross product of the two tangent vectors, that is: Its direction is perpendicular to the virtual reference toroidal surface. The tangent plane at that point, for Normalization is performed to obtain the unit normal vector. ; S304, point to the virtual reference ring surface , by pointing to the vector at the projection point , the dot product operation is obtained: , the distance is a scalar, and its positive or negative indicates that the point is located on the positive side or the negative side of the normal vector; S305, traverse all points in the point cloud data set, repeat S302 to S304, get the normal distance of each point, form the gap distribution data set.

[0011] Further, in S400, the specific process of fitting the actual contact sealing ring band from the gap distribution data set includes: traverse the gap distribution data set, compare the normal distance of each data point with , if , mark the point as an effective sealing point, if , mark it as a non-sealing point; perform three-dimensional spatial clustering analysis on all effective sealing points obtained, merge the effective sealing points densely distributed in space into the same cluster, and each cluster represents an effective sealing area; In the multiple clusters obtained by clustering, select the cluster containing the most data points as the main sealing ring band candidate cluster; For all effective sealing points in the selected main sealing ring band candidate cluster, use the moving least squares method to fit a continuous spatial surface, which is the actual contact sealing ring band.

[0012] Further, in S500, the continuity of the actual contact sealing ring band is quantified by the ring-wise continuity rate , along the ring-wise direction of the virtual reference ring surface, the sealing surface is equally divided into 360 sampling segments, each sampling segment corresponds to a 1° central angle, and the effective coverage length of the actual contact sealing ring band in each sampling segment is counted, the effective coverage length is the continuous arc length of the normal distance in the sampling segment, and the ring-wise continuity rate is calculated: , wherein is the total length of the virtual reference ring surface in the ring-wise direction.

[0013] Further, in S500, the maximum local gap value of the actual contact sealing ring band is represented by the maximum local gap, from the gap distribution data set corresponding to the actual contact sealing ring band, extract the absolute value of all normal distances, and use the 3 The criterion eliminates abnormal values, calculates the average value mu and the standard deviation sigma of all The data points are eliminated The maximum value in the remaining data points is the maximum local gap value .

[0014] Compared with the prior art, the three-eccentric butterfly valve sealing surface measurement method has the following beneficial effects: The present application accurately maps the point cloud data of the valve plate sealing surface obtained by actual scanning to the coordinate system of the virtual reference ring surface by constructing a virtual reference ring surface consistent with the design, accurately reproduces the theoretical cooperation relationship between the valve plate and the valve seat, generates a gap distribution data set by calculating the normal distance of each actual data point relative to the virtual reference ring surface, and the negative value area in the gap field represents the theoretical interference contact area. Through the analysis of the gap field, the present application can quantify the potential state of the valve plate and the valve seat contact in the computer without physical dynamic assembly and pressure test, convert the dynamic wedging process in the physical world into static gap calculation based on the accurate geometric model in the digital space, and thus realize the prior and non-destructive prediction of the sealing performance.

[0015] Other advantages, objects, and features of the present application will be in part apparent and in part pointed out hereinafter in the specification, and will be learned from a reading of the following specification and by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0017] Figure 1 A flowchart of a three-eccentric butterfly valve sealing surface measurement method; Figure 2 A step block diagram of a three-eccentric butterfly valve sealing surface measurement method. DETAILED DESCRIPTION

[0018] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined application purpose, the specific embodiments, structures, features and effects according to the present application will be described in detail below with reference to the drawings and preferred embodiments.

[0019] Embodiment one: the embodiment provides a kind of three eccentric butterfly valve sealing surface measurement method, as shown in Figure 2 The steps of S100, S200, S300, S400 and S500 are shown in the figure, which realize the accurate characterization of the contact state of the sealing surface of the three eccentric butterfly valve and the quantitative evaluation of the sealing performance, the method does not need physical dynamic assembly and pressure test, converts the dynamic wedge process into static gap calculation in digital space, can predict the sealing performance in advance, is non-destructive, solves the problem that the prior art cannot reflect the dynamic sealing state and quantize the micro gap distribution, provides reliable technical support for valve manufacturing quality control and process optimization.

[0020] Virtual reference ring surface construction stage (S100) Before measuring the sealing surface of the three eccentric butterfly valve, a virtual reference ring surface completely conforming to the theoretical valve plate sealing surface is established as a reference standard for subsequent actual measurement data comparison, this process is based on the design parameters of the three eccentric butterfly valve, and the geometric shape of the theoretical sealing surface is accurately reproduced in the computer three-dimensional modeling environment, the design parameters of the three eccentric butterfly valve are the key basis for constructing the virtual reference ring surface, which specifically includes axial eccentricity, radial eccentricity, angular eccentricity, sealing surface nominal diameter and sealing ring width, wherein the axial eccentricity refers to the deviation distance of the valve plate rotation axis and the valve body center line in the axial direction, the radial eccentricity is the deviation distance of the valve plate rotation axis and the valve body center line in the radial direction, and the angular eccentricity is the angle between the valve plate sealing surface conical generatrix and the valve plate rotation axis. These three eccentric parameters together constitute the core structural characteristics of the three eccentric butterfly valve, determine the spatial motion trajectory of the valve plate during opening and closing, the sealing surface nominal diameter limits the overall size range of the sealing surface, and the sealing ring width clearly defines the effective area width of the sealing action. The geometric parameters of the virtual reference ring surface correspond one by one to the above design parameters, and when the ring surface is constructed in the computer, a virtual reference ring surface completely consistent with the theoretical valve plate sealing surface is generated by three-dimensional modeling, laying a precise geometric reference foundation for the comparison of subsequent actual measurement data.

[0021] Actual valve plate sealing surface point cloud data acquisition stage (S200) After completing the construction of the virtual reference ring surface, a non-contact three-dimensional measurement device is used to scan the actual valve plate sealing surface to obtain a point cloud data set that can represent its three-dimensional topography. This process needs to go through four key steps of scanning planning and system calibration, multi-view scanning, point cloud alignment and merging, and filtering processing to ensure the integrity, accuracy and effectiveness of the point cloud data, wherein: According to the size of the actual valve plate and the space posture of the sealing surface, the moving path of the three-dimensional scanner is planned.

[0022] After the scanning plan is completed, the three-dimensional scanner is controlled to scan the valve plate sealing surface along the preset planned path. During the scanning process, the scanner emits a measurement light beam, the light beam is reflected after irradiating the sealing surface, the scanner receives the reflected signal, and the three-dimensional coordinates of each point on the sealing surface are calculated according to the propagation time, phase change and other information of the light beam. Each scanning of each view angle generates corresponding point cloud data, that is, multi-view point cloud.

[0023] In order to integrate the point cloud data obtained from multiple views into a unified coordinate system, it is necessary to align the point clouds by identifying common positioning target points in different view point clouds. By extracting the three-dimensional coordinates of the positioning target points in different view point clouds, a coordinate transformation matrix is calculated, which can convert each view point cloud into the same coordinate system. The point cloud data of each view is transformed according to the corresponding coordinate transformation matrix, so that all point cloud data is in a unified coordinate system. Then, the transformed multi-view point cloud is merged to form a complete point cloud data set that covers the entire sealing surface.

[0024] According to the spatial distribution characteristics and the distance between adjacent points of the point cloud data, abnormal noise points with large differences from normal point cloud data are identified and removed, and finally pure and effective point cloud data sets are obtained, providing a reliable data basis for subsequent coordinate transformation and gap calculation.

[0025] Coordinate transformation and gap calculation stage (S300) After obtaining a valid point cloud dataset, it is mapped to the coordinate system of a virtual reference toroidal surface using a coordinate transformation algorithm, ensuring both are in the same spatial reference system. The normal distance from each data point to the reference toroidal surface is then calculated, forming a gap distribution dataset. The coordinate transformation algorithm includes rigid transformation and eccentricity compensation transformation, which work together to achieve precise alignment between the point cloud dataset and the virtual reference toroidal surface coordinate system. Rigid transformation involves translating and rotating the coordinate system of the point cloud dataset to align with the coordinate system of the virtual reference toroidal surface. Since the point cloud data is acquired in the actual measurement coordinate system, while the virtual reference toroidal surface exists in a pre-defined computer coordinate system, their origins and coordinate axis directions may differ. Through rigid transformation, based on the positional relationship between the two coordinate systems, the translation vector and rotation matrix are calculated. The point cloud data is then translated along the translation vector to align the origin of the point cloud dataset's coordinate system with the coordinate system of the virtual reference toroidal surface. The origins are aligned, and then the point cloud data is rotated according to the rotation matrix to align the coordinate axes of the point cloud dataset with those of the virtual reference toroidal surface, thus initially aligning their coordinate systems. Eccentricity compensation transformation is necessary because the triple-eccentric butterfly valve has axial, radial, and angular eccentricity. Rigid transformation alone cannot completely eliminate the spatial positional deviation between the actual point cloud data and the virtual reference toroidal surface caused by the eccentric structure. Therefore, a specialized transformation matrix is ​​established based on the axial eccentricity, radial eccentricity, and angular eccentricity angle in the design parameters. This matrix is ​​used to perform secondary calibration on the rigidly transformed point cloud data. This transformation matrix can simulate the influence of the triple eccentric structure on the spatial position of the valve plate sealing surface. By adjusting the coordinates of the rigidly transformed point cloud data accordingly, the positional deviation caused by the eccentric structure is accurately compensated, achieving a high degree of spatial matching between the point cloud data and the virtual reference toroidal surface. This lays the foundation for accurate calculation of the subsequent normal distance. After completing the coordinate transformation, the normal distance from each point in the point cloud dataset to the virtual reference toroidal surface is calculated. The specific process is as follows: Parametric representation of virtual datum torus (S301): In the computer, the virtual datum torus is represented as a parametric surface: ,in For parameters on the surface The three-dimensional coordinate vector of the point. The circumferential parameter of the toroidal surface characterizes the position of the sealing surface along the circumferential direction. The radial parameter of the toroidal surface characterizes the radial position of the sealing surface. , , Points The X, Y, and Z coordinates in a three-dimensional coordinate system; Find the projection point (S302): For any point in the point cloud dataset It is necessary to find its position on the virtual reference toroidal surface. Projection point on The projection point is the foot of the perpendicular from point P to the normal direction of the virtual reference torus. To determine the projection point... Corresponding parameters A numerical optimization algorithm is used to calculate the distance from point P to the surface. Square distance to any point on As the objective function, the parameters are continuously adjusted through iterative calculations. and The value of that minimizes the objective function is found in the corresponding parameter. That is, the projection point The parameters on the virtual reference toroidal surface can then be determined according to... The expression yields the projection point. The three-dimensional coordinates.

[0026] Calculate the normal vector (S303): To calculate the normal distance from point P to the virtual reference torus, it is necessary to first determine the virtual reference torus at the projection point. The normal vector at the location is first calculated along... Tangent vector in parameter direction The tangent vector represents the surface in The tangent direction along the circumference reflects the circumferential trend of the torus; then calculate along... Tangent vector in parameter direction The tangent vector represents the surface in The tangential direction along the radial direction reflects the radial variation trend of the torus; the virtual reference torus is in The normal vector N at point N is calculated by the cross product of the two tangent vectors, i.e. Its direction is perpendicular to the virtual reference toroidal surface. For the tangent plane at the given location, the normal vector N needs to be normalized to obtain the unit normal vector for easier subsequent calculations. The unit normal vector has a magnitude of 1 and only indicates direction.

[0027] Calculate the normal distance (S304): the normal distance from point P to the virtual reference torus. The vector from projection point S0 to point P The dot product of the vector and the unit normal vector n at the projection point is obtained by the following formula: The distance d is a scalar, and its sign has a specific physical meaning. If d is positive, it means that point P is located on the positive side of the unit normal vector n; if d is negative, it means that point P is located on the negative side of the unit normal vector n. The negative value region usually corresponds to the theoretical interference contact region.

[0028] Data aggregation (S305): Following the steps above, traverse all points in the point cloud dataset, repeat the operations from S302 to S304, calculate the normal distance of each point, and aggregate all normal distances to form a gap distribution dataset.

[0029] Actual contact sealing ring fitting stage (S400) Based on the preset effective sealing threshold Data points meeting effective sealing conditions are selected from the gap distribution dataset. Through cluster analysis and surface fitting, the actual contact sealing ring is obtained. This ring can truly reflect the actual contact area of ​​the valve plate sealing surface under theoretical fit conditions. The normal distance from the point cloud data point to the virtual reference ring surface is... When, theoretically, this point can participate in the sealing effect and is marked as an effective sealing point; when When a point fails to meet the sealing requirements, it is marked as a non-sealed point. This is achieved by traversing the gap distribution dataset and calculating the normal distance to each data point. By comparing and classifying effective sealing points from non-sealing points, data points with sealing potential are initially screened out. However, due to potential local defects and processing errors on the valve plate sealing surface during actual manufacturing, the selected effective sealing points may not be a continuous whole in spatial distribution, but rather appear as scattered areas. Therefore, a three-dimensional spatial cluster analysis is performed on all effective sealing points. Based on characteristics such as spatial distance and distribution density, densely distributed and adjacent effective sealing points are grouped into the same cluster. Each cluster represents a potential effective sealing area. Through cluster analysis, different sealing areas can be clearly distinguished, eliminating the interference of isolated and scattered ineffective sealing points on subsequent analysis. The number of effective sealing points contained in different clusters is also considered. There are differences, and the cluster containing the most data points is usually the main sealing area of ​​the sealing surface, playing a dominant role in the overall sealing performance of the valve. Therefore, the cluster containing the most data points is selected as the candidate cluster of the main sealing ring. This candidate cluster can reflect the main sealing characteristics of the sealing surface. For all effective sealing points in the selected candidate cluster of the main sealing ring, the moving least squares method is used for surface fitting. The moving least squares method establishes a local approximation function around each data point and performs fitting calculations on the data points in the local area according to the weight of the data points. It can effectively handle the discreteness and local fluctuations of the data points and obtain a continuous and smooth spatial surface. This surface is the actual contact sealing ring, which accurately reflects the actual contact area shape of the valve plate sealing surface under the theoretical fit state.

[0030] Quantitative evaluation phase of sealing performance (S500) Based on the fitted actual contact sealing ring belt, quantitative parameters for evaluating the sealing performance thereof are calculated, mainly including continuity of the actual contact sealing ring belt and maximum local gap value, and through the two parameters, the sealing performance of the sealing surface can be intuitively and accurately judged, wherein the continuity of the sealing ring belt is quantified by calculating a ring-wise continuity rate C, the sealing surface is equally divided into 360 sampling segments along a ring-wise direction of the virtual reference ring surface, each sampling segment corresponds to a 1° central angle, so as to ensure that the circumferential range of the sealing surface can be fully covered, for each sampling segment, the effective coverage length of the actual contact sealing ring belt in the sampling segment is counted , the effective coverage length is a continuous arc length with a normal distance in the sampling segment, if the sampling segment is not covered by the actual contact sealing ring belt, then =0. According to a formula , a ring-wise continuity rate C is calculated, wherein is a total ring-wise length of the virtual reference ring surface, i.e. the development length of the virtual reference ring surface along the circumference, the larger the value of the ring-wise continuity rate C is, the better the continuity of the actual contact sealing ring belt in the circumferential direction is, and the more stable the sealing performance is; on the contrary, the smaller C is, the more discontinuous regions exist in the sealing ring belt, and the sealing performance has hidden dangers; for the maximum local gap value, it directly reflects the gap size of the local region in the actual contact sealing ring belt, if the local gap is too large, it may lead to leakage of the medium through the gap, and affect the sealing effect, from the gap distribution data set corresponding to the actual contact sealing ring belt, the absolute value of the normal distance of all effective sealing points is extracted , since there may exist abnormal values in the data set due to measurement errors and other factors, these abnormal values will affect the accuracy of the calculation of the maximum local gap value, therefore, the 3σ rule is adopted to eliminate the abnormal values, first, the average value μ and the standard deviation σ of all are calculated, the average value μ reflects the average level of the absolute value of the normal distance of all effective sealing points, and the standard deviation σ reflects the dispersion degree of the data, according to the 3σ rule, the data points with > μ+3σ are eliminated, these data points are considered as abnormal values, and do not participate in the subsequent calculation of the maximum local gap value, in the remaining data points, the maximum value of the absolute value of the normal distance is selected, i.e. the maximum local gap value , the smaller the maximum local gap value G is, the smaller the local gap in the actual contact sealing ring belt is, and the better the sealing performance is; if G exceeds the allowable gap range, it indicates that there is a risk of local sealing failure of the sealing surface.

[0031] In summary, through the complete process of S100 to S500, the embodiment realizes the precise measurement and sealing performance evaluation of the sealing surface of the triple-eccentric butterfly valve. The entire method does not require physical dynamic assembly and pressure testing, converts the dynamic sealing process of the triple-eccentric butterfly valve into static calculation in the digital space, can predict the sealing performance a priori and non-destructively, effectively solves the deficiencies of the prior art, and provides a feasible technical solution for manufacturing quality control, process optimization and reliability guarantee of the triple-eccentric butterfly valve.

[0032] Embodiment Two: Based on Embodiment One, the embodiment provides a specific step of a measuring method for a sealing surface of a triple-eccentric butterfly valve, as shown in Figure 1 The specific step is: (1) Construct a virtual reference torus Obtain the design parameters of the triple-eccentric butterfly valve, including the axial eccentricity, the radial eccentricity, the angular eccentricity, the nominal diameter of the sealing surface, and the sealing ring width; Construct a virtual reference torus in the computer based on the above parameters, which is completely consistent with the theoretical valve plate sealing surface; Take the virtual reference torus as the reference model for subsequent data comparison and analysis.

[0033] (2) Obtain the point cloud data set of the actual valve plate sealing surface According to the size of the valve plate and the spatial posture of the sealing surface, plan the scanning path of the three-dimensional scanner; Calibrate the accuracy of the three-dimensional scanner using standard blocks; Control the scanner to scan the valve plate sealing surface from multiple angles along the planned path; Obtain point cloud data from multiple angles, and align and merge the coordinates through the positioning target points; Filter the merged point cloud data set to remove abnormal noise points.

[0034] (3) Calculate the normal distance from the point cloud to the virtual reference torus Preliminarily align the point cloud data set with the virtual reference torus coordinate system through rigid transformation; Perform eccentricity compensation transformation based on the triple-eccentric parameters to further calibrate the position of the point cloud; For each point in the point cloud, find its nearest projection point on the virtual reference torus; Calculate the distance of each point to the normal direction of the projection point to form a gap distribution data set; Record the normal distance value and its positive and negative direction of each point.

[0035] (4) Fit the actual contact sealing ring Set an effective sealing threshold; Traverse the gap distribution dataset and filter out all points with normal distance less than or equal to the threshold value; Perform three-dimensional spatial clustering analysis on the filtered points to identify the main sealing area; Select the cluster with the most data points as the main sealing ring belt; Use the moving least squares method to fit the main sealing ring belt into a continuous spatial surface.

[0036] (5) Calculate the sealing performance quantification parameter Continuity analysis: Divide the sealing ring belt into 360 sampling segments in the circumferential direction; Statistical analysis of the arc length of the effective sealing area in each sampling segment; Calculate the ring-wise continuity rate to evaluate the completeness of the sealing ring belt.

[0037] Maximum local gap analysis: Extract the absolute value of the normal distance from the actual contact sealing ring belt corresponding to the gap data; Use the 3σ criterion to remove outliers; Determine the maximum value in the remaining data as the maximum local gap value.

[0038] The above is only the preferred embodiment of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed as above with the preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present application. Any modification, equivalent change and modification of the above embodiments made in accordance with the technical essence of the present application, without departing from the technical solution of the present application, are still within the scope of the present application.

Claims

1. A method of measuring a sealing surface of a triple offset butterfly valve, characterized in that, The specific steps of the method are: S100, according to the design parameters of the triple eccentric butterfly valve, a virtual reference torus conforming to the theoretical valve plate sealing surface is constructed in the computer as a reference for subsequent data comparison; S200, using a non-contact three-dimensional measurement device to scan the actual valve plate sealing surface to obtain a point cloud data set representing its three-dimensional topography; S300, mapping the point cloud dataset to the coordinate system of the virtual reference annulus by a coordinate transformation algorithm, calculating the normal distance of each data point to the reference annulus , the set of normal distances as a gap distribution dataset; S400, based on a preset effective sealing threshold The normal distance is selected from the sealing gap distribution dataset. All data points are used to fit the three-dimensional spatial region represented by these data points into the actual contact sealing ring. S500, based on the fitted actual contact sealing ring, the quantitative parameters for evaluating its sealing performance are calculated, including the continuity and maximum local gap value of the actual contact sealing ring.

2. The method of measuring a seal face of a triple offset butterfly valve of claim 1, wherein, In S100, the design parameters include the axial eccentricity, radial eccentricity, angular eccentricity, nominal diameter of the sealing surface and sealing ring width of the triple eccentric butterfly valve. The geometric parameters of the virtual reference torus correspond one-to-one to the design parameters.

3. The method of claim 1, wherein the method further comprises: The specific steps of obtaining the point cloud data set in S200 include: Scan planning and system calibration: according to the size of the valve plate and the spatial pose of the sealing surface, the moving path of the three-dimensional scanner is planned; Control the three-dimensional scanner to scan the valve plate sealing surface along the planned path, multiple views to fully cover the sealing surface, emit measurement light beams and receive reflected signals, directly obtain the three-dimensional coordinates on the sealing surface, form multi-view point clouds; By identifying the common positioning target points in different view point clouds, the coordinate transformation matrix is calculated, and all multi-view point clouds are aligned and merged into a point cloud data set in a unified coordinate system; Filter the point cloud data set to identify and remove abnormal noise points caused by measurement noise.

4. The method of claim 1, wherein the method further comprises: In S300, the coordinate transformation algorithm includes rigid transformation and eccentric compensation transformation: The rigid transformation is used to align the coordinate system of the point cloud data set with the coordinate system of the virtual reference torus through translation and rotation; The eccentric compensation transformation is used to correct the spatial position deviation caused by the triple eccentric structure, and the transformation matrix is established based on the axial eccentricity, radial eccentricity and angular eccentricity in the design parameters to perform secondary calibration on the point cloud data after rigid transformation.

5. The method of measuring a seal face of a triple offset butterfly valve of claim 1, wherein, In S300, the calculation process of the normal distance is: S301、In the computer, the virtual reference torus is expressed as a parameter surface form: wherein is a three-dimensional coordinate vector of a point on the surface with parameters , is a circumferential parameter of the torus, representing the position of the sealing surface along the circumference, is a radial parameter of the torus, representing the position of the sealing surface along the radial direction, , , are X, Y, Z axis coordinates of the point in the three-dimensional coordinate system, respectively. S302. For any point in the point cloud dataset To find its position on the virtual reference toroidal surface Projection point on The parameters corresponding to this projection point are Minimize the point using a numerical optimization algorithm To the surface Square distance from any point on Solving for the parameters that minimize the squared distance yields the solution. This parameter corresponds to the projection point. ; S303、Calculate the normal vector of the virtual reference ring surface at the projection point wherein:​ along a tangent vector of the parameter direction , represents the tangent direction of the surface at along the ring direction; along a tangent vector of the parameter direction , indicating the tangent direction of the surface at radial direction; Normal vector The normal vector is calculated by the cross product of two tangent vectors, i.e. The direction of the normal vector is perpendicular to the tangent plane of the virtual reference annulus at The unit normal vector is obtained by unitizing ; S304, point normal distance to the virtual reference torus , by vector pointing to P unit normal vector at the projection point dot product operation gives: ; S305, traverse all points in the point cloud data set, repeat S302 to S304, get the normal distance of each point, form the gap distribution data set.

6. The method of measuring a seal face of a triple offset butterfly valve of claim 1, wherein, In S400, the specific process of fitting the actual contact sealing ring from the gap distribution data set includes: traversing the gap distribution dataset, the normal distance of each data point is compared to the maximum normal distance of the dataset with when the point is marked as a valid seal point, when it is marked as a non-seal point; Perform three-dimensional spatial clustering analysis on all valid sealing points obtained, merge the valid sealing points densely distributed in space into the same cluster, and each cluster represents an effective sealing area; Among the multiple clusters obtained by clustering, select the cluster containing the most data points as the main sealing ring candidate cluster; For all valid sealing points in the selected main sealing ring candidate cluster, use the moving least squares method to fit a continuous spatial surface, which is the actual contact sealing ring.

7. The method of measuring a seal face of a triple offset butterfly valve of claim 1, wherein, The continuity of the actual contact sealing ring belt in the S500 is quantified by the ring continuity rate The sealing surface is equally divided into 360 sampling segments along the ring direction of the virtual reference ring surface, each sampling segment corresponds to a 1° central angle, and the effective coverage length of the actual contact sealing ring belt in each sampling segment is counted The effective coverage length is the continuous arc length of the normal distance The ring continuity rate is calculated as follows: Wherein, The total length of the ring surface of the virtual reference ring surface.

8. The method of measuring a seal face of a triple offset butterfly valve of claim 1, wherein, In the S500, the maximum local gap value of the actual contact sealing ring belt is represented by the maximum local gap, and the absolute value of all normal distances is extracted from the gap distribution data set corresponding to the actual contact sealing ring belt , and the abnormal values are removed by adopting three criteria, the average value and the standard deviation of all are calculated, the data points of are removed, and the maximum value in the remaining data points is the maximum local gap value .

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