Dynamic measurement method for mechanical seal end face gap

Abstract

The invention relates to the field of mechanical seal, in particular to a dynamic measurement method for a mechanical seal end face gap, which comprises the following steps of: S1, arranging periodic grating structures on non-sealing surfaces of a moving ring and a static ring of a mechanical seal; s2, in the operation process of the mechanical seal, collecting a dynamic image sequence of the periodic grating structure; s3, processing the obtained dynamic image sequence, extracting phase information of the periodic grating structure, and obtaining phase change data; s4, the relative displacement and the relative rotation angle between the sealing end faces of the movable ring and the static ring are calculated based on the phase change data; and S5, monitoring, early warning and evaluating the state of the mechanical seal. The invention provides a dynamic measurement method for a mechanical seal end face gap. According to the invention, non-stop and non-contact on-line detection of the mechanical seal end surface gap can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of mechanical seal, in particular to a dynamic measurement method for mechanical seal end face gap. BACKGROUND

[0002] Mechanical seal is a key component for preventing medium leakage in rotating equipment, widely used in petroleum chemical industry, electric power, pharmaceutical, aerospace and other fields. Its basic structure usually includes dynamic ring, static ring, spring, sealing ring and other components, mainly relying on the close adhesion of the end face of dynamic ring and static ring to form a sealing interface to prevent fluid leakage. In theory, the sealing end face should maintain uniform and stable adhesion or maintain the designed gap, however, in actual operation process, the sealing end face is easily affected by various factors and deformed or relatively displaced, resulting in the decline of sealing performance, and even causing leakage, wear and tear and other failures.

[0003] Therefore, it is crucial to monitor the gap and deformation of the sealing device, however, the current measurement methods for mechanical seal end face gap mainly include contact displacement sensor measurement, capacitance method, eddy current method and the like. However, these methods generally have the following problems: first, it is difficult to adapt to high-speed rotating conditions, and the sensor installation is limited; second, the measurement accuracy is limited, and it is difficult to capture micron-level or even sub-micron-level gap changes; third, it is easily affected by environmental factors such as temperature and electromagnetic interference, and the stability and reliability are insufficient; fourth, most of the methods are point measurement, and cannot realize full-field and visual monitoring. Especially, the above-mentioned measurement methods cannot realize non-contact monitoring of mechanical seal in rotating state without stopping, therefore, how to realize online monitoring of the small distance change between dynamic ring and static ring in working state without contact has become a technical problem to be solved. SUMMARY

[0004] In order to avoid and overcome the technical problems existing in the prior art, the present application provides a dynamic measurement method for mechanical seal end face gap. The present application can realize non-stop and non-contact online detection of mechanical seal end face gap.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme: A dynamic measurement method for mechanical seal end face gap, comprising the following steps: S1: periodic grating structure is arranged on the non-sealing surface of the dynamic ring and the static ring of the mechanical seal; S2: during the operation of the mechanical seal, a dynamic image sequence of the periodic grating structure is collected; S3: the acquired dynamic image sequence is processed, the phase information of the periodic grating structure is extracted, and phase change data is obtained; S4: based on the phase change data, the relative displacement and relative angle between the sealing end faces of the dynamic ring and the static ring are calculated. S5: monitoring, early warning and evaluation of the state of the mechanical seal.

[0006] As a further scheme of the present application, in S3: S31, pre-processing the collected image; S32, orthogonal decomposition of the grating pattern, two perpendicular grating orthogonal decompositions are obtained, and two independent one-way gratings are obtained, one of which is parallel to the axis of the dynamic ring and the static ring; S33, downsampling the two independent one-way gratings after separation; S34: using an interpolation method to process the discontinuous pixel sequence after downsampling to generate a continuous moire fringe image, and performing phase calculation on the moire fringe image.

[0007] As a further scheme of the present application, in S33, the sampling interval of downsampling is T , T the nearest integer of the grating pitch; When downsampling, starting from the first pixel block on one side of the grating, every T pixel block is sampled to obtain a first discontinuous pixel block sequence with a period of T ; Starting from the second pixel block, every T pixel block is sampled to obtain a second discontinuous pixel block sequence with a period of T ; Repeat the above operation to obtain T discontinuous pixel block sequences.

[0008] As a further scheme of the present application, in S34, the intensity difference of the missing part of each discontinuous pixel block sequence is calculated to make it a continuous and smooth moire sequence, and the moire phase is obtained after discrete Fourier transform of the moire sequence.

[0009] As a further scheme of the present application, before the mechanical seal is deformed x the direction of the moire phase is :

[0010]

[0011] After the mechanical seal is deformed x the direction of the moire phase is :

[0012]

[0013] wherein, Intensity of Moiré fringe image before deformation of mechanical seal x Intensity of Moiré fringe image before deformation of mechanical seal Intensity of Moiré fringe image after deformation of mechanical seal x Intensity of Moiré fringe image after deformation of mechanical seal T Sampling interval of down-sampling k Moiré order number of down-sampling Amplitude of grating intensity p x Grating pitch before deformation of mechanical seal x Grating pitch before deformation of mechanical seal Grating pitch after deformation of mechanical seal x Grating pitch after deformation of mechanical seal Background intensity Phase difference of Moiré fringe along direction of edge of mechanical seal before and after deformation x Phase difference of Moiré fringe along direction of edge of mechanical seal before and after deformation

[0014] .

[0015] As a further scheme of the present application, in S4: S41, the direction of the axis of the plain ring and the static ring is x Direction, the relative displacement of the grating along x Direction is

[0016] Wherein, Phase difference of grating along direction of edge of mechanical seal before and after deformation x Phase difference of grating along direction of edge of mechanical seal before and after deformation p x Grating pitch before deformation of mechanical seal x Grating pitch before deformation of mechanical seal Grating phase can be obtained from Moiré phase :

[0017] Wherein Phase of unidirectional grating along direction after deformation of mechanical seal x Phase of unidirectional grating along direction after deformation of mechanical seal Phase of unidirectional grating along direction after deformation of mechanical seal​​​x grating pitch in the direction of the main direction of the mechanical seal; representing the one-way grating after deformation of the mechanical seal in the direction of the main direction of the mechanical seal; y grating pitch in the direction of the main direction of the mechanical seal; x representing the coordinate value of the grating in the direction of the main direction of the mechanical seal; x representing the coordinate value of the grating in the direction of the main direction of the mechanical seal; y y representing the coordinate value of the grating in the direction of the main direction of the mechanical seal;

[0018] the deflection angle of the grating in the direction of the main direction of the mechanical seal is x : :

[0019] since the initial moment x the rotation angle of the main direction grating in the direction of the main direction of the mechanical seal is 90°, the angle change amount x x : S42, calculating the relative displacement of the sealing end face in the direction of the main direction of the mechanical seal and the deflection angle in the direction of the main direction of the mechanical seal with the calculation step in S41.

[0020] y y

[0021] As a further scheme of the present application: within the threshold range of -n , n ) is enveloped by (-π, π), and after differential correction:

[0022] wherein, representing the grating phase difference before and after deformation of the mechanical seal at the coordinate point; representing the grating phase difference before and after deformation of the mechanical seal at the coordinate point.

[0023] As a further scheme of the present application: by capturing the respective displacements of the dynamic ring and the static ring from the image during the operation of the mechanical seal, the gap change amount d , the relative rotation angle change amount :

[0024]

[0025] wherein,​​​​ The grating displacement pasted on the static ring; The grating displacement pasted on the dynamic ring; The grating angle change amount pasted on the static ring; The grating angle change amount pasted on the dynamic ring.

[0026] An electronic device, characterized by comprising a processor, an input device, an output device and a memory, the processor, the input device, the output device and the memory are sequentially connected, the memory is used for storing a computer program, the computer program comprises program instructions, the processor is configured to call the program instructions, and the mechanical seal end face gap dynamic measurement method is executed.

[0027] A readable storage medium, characterized by storing a computer program, the computer program comprises program instructions, and the program instructions make the processor execute the mechanical seal end face gap dynamic measurement method when the processor executes.

[0028] Compared with the prior art, the beneficial effects of the present application are: 1、The present application sets the grating structure on the surface of the dynamic ring and the static ring without damaging the sealing structure and affecting the running state of the sealing structure, and has little influence on the overall operation of the sealing structure, and on this basis, the mechanical seal can be monitored in real time, non-stop and non-contact on-line by image acquisition and processing of the grating under high-speed rotation; the working state of the sealing end face can be comprehensively reflected by judging the relative displacement of the sealing end face along the axis direction and the relative rotation angle around the shaft.

[0029] 2、The present application separates the two-dimensional grating deformation into two independent one-dimensional directions through orthogonal decomposition, so that the displacement and the rotation angle can be calculated independently, avoiding mutual interference; the high-frequency grating signal is converted into a low-frequency cloud stripe signal by generating a cloud stripe, the small deformation information is amplified, the measurement is more sensitive and reliable; the cloud stripe signal extraction accuracy and consistency are ensured by sampling at an integer multiple of the grating pitch, and after generating the T-bar discontinuous sequence, it is equivalent to observing the cloud stripe from different starting points, providing sufficient data basis for subsequent generation of continuous and complete full-field phase diagram.

[0030] 3、The present application changes the discrete pixel sequence into a continuous cloud stripe image through interpolation, so as to calculate the phase information of the whole observation area, and adopts discrete Fourier transform for phase extraction, so as to extract accurate and continuous phase values from the cloud stripe, and provides reliable input for subsequent calculation.

[0031] 4、The application greatly reduces the measurement cost of the sealing end face gap, does not need expensive sensors, only needs a high-speed camera to collect images of the surface grating of the measured object, and assists with an algorithm to obtain the motion displacement condition, and has very good anti-interference effect. BRIEF DESCRIPTION OF DRAWINGS

[0032] Fig. 1 It is a structural schematic diagram of the application.

[0033] Fig. 2 It is a schematic diagram of the setting mode of the grating pattern in the application.

[0034] Fig. 3 It is a process schematic diagram of phase analysis in the application. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0036] Please refer to Figs. 1-3 In the embodiments of the application, a dynamic measurement method of a mechanical sealing end face gap comprises the following steps. S1: periodic grating structures are arranged on the non-sealing surfaces of the dynamic ring and the static ring of the mechanical seal. The grating pattern is not limited in specific shape, and can be a quadrature grid, a one-dimensional grating line, a dot matrix pattern, a digital / letter array, a periodic pattern with a ±45° or other arbitrary angle. In the embodiment, the quadrature grid is selected as the grating pattern, and the grating pitch is set to 2 mm.

[0037] The preparation mode of the grating is not limited by the process means, and can adopt laser marking, nano-imprinting, plasma etching, mask photolithography, maskless photolithography, grating pasting and the like. The grating period can be flexibly adjusted according to the measurement accuracy requirement, and the smaller the period is, the higher the measurement resolution is. When setting, the grating should be closely attached to the surface of the measured part, and the quality thereof should be much smaller than that of the locking object, so as to avoid introducing additional inertia or eccentricity. In the embodiment, the laser marking technology or the high-adhesion grating transfer pasting scheme is adopted. The ultraviolet laser marking machine is used to directly etch the periodic grating on the surface of the sealing ring, so as to ensure that the line is clear and uniform. When the grating transfer pasting is used, the high-temperature-resistant adhesive film grating is selected, and is attached to the surface through the pressing and pasting mode, so as to avoid falling off in rotation. After the grating is prepared, the pattern integrity and contrast thereof need to be checked, so as to ensure the image collection quality in the subsequent step.

[0038] The mechanical seal can be replaced by any one of a dry gas seal, a liquid film seal, a gas film seal, a magnetic seal, a floating ring seal, a spiral seal, a labyrinth seal, a combined seal, an intelligent seal, a self-repairing seal, a nano seal, and a bionic seal; and the mechanical seal can be applied to a pump, a compressor, a reaction kettle, a centrifuge, a turbine, an engine, a transmission, a speed reducer, a mixer, a stirrer, a fan, a vacuum device, a hydraulic device, a pneumatic device, and related machinery.

[0039] S2: collecting a dynamic image sequence of the periodic grating structure during operation of the mechanical seal; First, a detection system is built, and the static ring and the dynamic ring assembled with the grating are installed in a rotating device, the static ring is fixed, and the dynamic ring rotates with the main shaft.

[0040] A high-speed camera with a frame rate not less than 2000 fps is used, and a telecentric lens is equipped to reduce perspective error. The camera is fixed on a vibration-proof platform, and the lens is directed at the grating area of the seal ring to ensure that the grating is always located at the center of the field of view. A uniform LED cold light source is used to obliquely irradiate the grating surface at a certain angle to enhance the image contrast. The high-speed camera can also be replaced by a CCD, a CMOS, a microscope, an endoscope, a fiber imaging system, an infrared imaging system, and an X-ray imaging system.

[0041] After starting the rotating device, the rotating speed of the dynamic ring is set to 100 rpm. During rotation, a grating image under zero load in the initial state is first collected as a reference. The high-speed camera continuously collects dynamic grating images through the observation window, and the collection time covers multiple rotation periods to ensure that the complete motion process is captured. During the collection process, the camera focal length, position, and lighting conditions remain constant to avoid external interference. Under the action of centrifugal force, friction force, and fluid pressure in the working condition, the gap between the dynamic ring and the static ring will change slightly. As a displacement carrier, the periodic stripes of the grating will deform with the change of the gap. The high-speed camera collects real-time motion images of the grating on the surface of the dynamic ring and the static ring during the whole process and transmits them to the data processing and analysis module.

[0042] To ensure measurement stability, the high-speed camera and the light source are fixed through a vibration-proof support, and an external transparent protective cover is provided to isolate the lubricating liquid and dust from affecting the imaging quality of the grating. The grating material is selected to be a composite film that is resistant to high temperature and wear to ensure that the grating stripes are not damaged in a long-term rotating and friction environment.

[0043] S3: processing the obtained dynamic image sequence, extracting phase information of the periodic grating structure, and obtaining phase change data; S31, pre-processing the collected images; The collected images are first pre-processed by cropping and rotating, and then grayscaled to obtain grayscale images.

[0044] S32. Perform orthogonal decomposition on the grating pattern, orthogonally decomposing the gratings in two perpendicular directions to obtain two independent unidirectional gratings. The two perpendicular gratings are decomposed into two independent unidirectional gratings, and each directional grating is used for phase analysis and displacement calculation in its respective direction. When using orthogonal gratings, a two-dimensional Fourier filter or low-pass filter is used to separate the gratings. x and y Single-frequency grating component in the direction.

[0045] One of the unidirectional gratings is parallel to the axes of the moving ring and the stationary ring; The grating phase processing methods are the same in both directions, so only the phase analysis process in one direction will be described. Assume that the extracted... x The grating of the direction is defined as follows: p x , Before the mechanical seal deforms, x The light intensity of the directional grating is : ; After the mechanical seal deforms, x The light intensity of the directional grating is : ; Caused by deformation of mechanical seal x The phase difference corresponding to the change in the directional grating is :

[0046] in, This represents the grating intensity amplitude. x express x The coordinates of the orientation grating; Indicates background intensity; p x Indicates the mechanical seal before deformation x grating pitch in the direction; Indicates the deformation of the mechanical seal x grating pitch in the direction; Indicates the mechanical seal before deformation x The grating phase in the direction; Indicates the deformation of the mechanical seal x The grating phase in the direction.

[0047] S33. Downsample the two independent unidirectional gratings after separation; The sampling interval of down-sampling is T , T is the nearest integer of the grating pitch; When down-sampling, starting from the first pixel block on one side of the grating, every T pixel block is sampled to obtain a first sequence of discontinuous pixel blocks with a period of T ; Then starting from the second pixel block, every T pixel block is sampled to obtain a second sequence of discontinuous pixel blocks with a period of T ; The above operation is repeated to obtain T sequences of discontinuous pixel blocks with different gray scales.

[0048] S34: The sequences of discontinuous pixels after down-sampling are processed by an interpolation method to generate a continuous moire fringe image, and phase calculation is performed on the moire fringe image.

[0049] The missing parts of each sequence of discontinuous pixel blocks are made continuous and smooth by intensity difference, and the moire phase is obtained after discrete Fourier transform of the moire sequence.

[0050] The interpolation method is Makima interpolation, and the intensity of the moire fringe image after interpolation is :

[0051] After discrete Fourier transform, the moire phase in the x direction before deformation of the mechanical seal is :

[0052]

[0053] The moire phase in the x direction after deformation of the mechanical seal is :

[0054]

[0055] wherein, represents the intensity of the moire fringe image in the x direction before deformation of the mechanical seal; represents the intensity of the moire fringe image in the x direction after deformation of the mechanical seal; T represents the sampling interval of down-sampling; k This indicates the sequence number of the moiré pattern obtained from downsampling. ; This represents the grating intensity amplitude. p x Indicates the mechanical seal before deformation x grating pitch in the direction; Indicates the deformation of the mechanical seal x grating pitch in the direction; Indicates background intensity.

[0056] The phase difference of the cloud pattern is for:

[0057] The moiré phase difference calculated here refers to x Phase difference of moiré patterns in the direction, y The phase difference of the moiré pattern in the direction is calculated in the same way as above.

[0058] Moiré phase difference and grating fringe phase difference The following relationship exists: ; S4: Based on phase change data, calculate the relative displacement and relative rotation angle between the sealing end faces of the rotating ring and the stationary ring; exist( -n , n Within the threshold range of ), it is enveloped by (-π, π), and after partial derivative correction:

[0059] in, Indicates the location at coordinates The grating phase difference before and after deformation of the mechanical seal at the point; Indicates the location at coordinates The grating phase difference before and after deformation of the mechanical seal at the point.

[0060] Phase boundary discontinuities can be eliminated by using a phase unwrapping algorithm.

[0061] S41, with the axial directions of the moving and stationary rings as... x Direction, along the grating x The relative displacement in the direction is ;

[0062] grating and x The deflection angle of the direction is :

[0063] wherein, represents the phase of the one-way grating in the x direction after the mechanical seal is deformed; represents the grating pitch of the one-way grating in the x direction after the mechanical seal is deformed; represents the grating pitch of the one-way grating in the y direction after the mechanical seal is deformed; x represents the coordinate value of the grating in the x direction; y represents the coordinate value of the grating in the y direction.

[0064] Since the angle change amount x is the rotation angle between the main direction grating and the x direction at the initial moment, the angle change amount x :

[0065] S42, the relative displacement of the sealing end face in the y direction and the deflection angle in the y direction are calculated by the calculation step in S41.

[0066] The displacement of the dynamic ring and the static ring is captured during the operation of the mechanical seal, and the gap change amount d and the relative rotation angle change amount are obtained:

[0067]

[0068] wherein is the grating displacement on the static ring; is the grating displacement on the dynamic ring; is the grating angle change amount on the static ring; is the grating angle change amount on the dynamic ring.

[0069] S5: monitoring, early warning and evaluation of the state of the mechanical seal.

[0070] Since the number of images captured by the high-speed camera is large, the displacement value of the specific point can be selected to draw a displacement curve in the order of the captured images, and the change rule is found.

[0071] In the measurement process, gratings can be attached to the static ring and the dynamic ring respectively, and the gratings can be made in different styles to distinguish them, or different marks can be added beside the gratings to distinguish them. According to the above derivation process, for the specific performance of the seal, the displacement of the grating attached to the static ring can be defined as u x0 The grating attached to the dynamic ring maintains horizontal with the grating of the static ring. In order to more easily show the displacement change and the shaft center offset, two gratings can be attached to the dynamic ring along the horizontal direction, the displacement of the grating close to the static ring is defined as u x1 The displacement of the grating far from the static ring is defined as u x2 For the gap change, the difference between the displacements of the dynamic ring and the static ring caused by factors such as vibration can reflect the change of the gap between the dynamic ring and the static ring. The process images collected by the high-speed camera are analyzed according to the above process, and each image has its displacement field distribution relative to the first image. The displacement of the grating area of the dynamic ring and the static ring represents the displacement of the dynamic ring and the static ring in the running process, and the displacement difference between the dynamic ring and the static ring can represent the gap change value. x For the gap change in the direction, it can be observed by - It can also be observed by -u x0 - The relationship between - The relationship between the two values can be used as further verification of the change of the shaft center angle. If the shaft center is offset, the two values are not synchronous, and the existence of the v-shaped eccentricity can be judged accordingly.

[0072] Another embodiment of the present application is an electronic device.

[0073] The electronic device can be a mobile device itself, or a single device independent of the mobile device. The single device can communicate with the mobile device to receive the collected input signals therefrom and send the selected target decision behavior thereto.

[0074] The electronic device includes one or more processors and a memory.

[0075] The processor can be a central processing unit (CPU) or other forms of processing units with data processing capability and / or instruction execution capability, and can control other components in the electronic device to perform desired functions.

[0076] ​The memory can include one or more computer program products that can include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory, for example, can include random access memory (RAM), and / or a cache, and / or the like. The non-volatile memory, for example, can include read-only memory (ROM), hard disk, flash memory, and / or the like. The computer-readable storage media can store one or more computer program instructions executable by the processor to implement the method of dynamically measuring a mechanical seal end face gap according to various embodiments of the present application described above.

[0077] In one example, the electronic device can further include an input device and an output device, which are interconnected through a bus system and / or other forms of connection mechanisms. For example, the input device can include various devices such as an on-board diagnostic system (OBD), a camera, an industrial camera, and / or the like. The input device can also include a keyboard, a mouse, and / or the like. The output device can include a display, a speaker, a printer, a communication network and a remote output device connected thereto, and / or the like.

[0078] In addition, the electronic device can further include any other appropriate components according to specific application cases.

[0079] Another embodiment of the present application is a computer program product that can also be a computer-readable storage medium including computer program instructions that, when executed by a processor, cause the processor to perform the computing steps described in the method of dynamically measuring a mechanical seal end face gap according to various embodiments of the present application described above.

[0080] The computer program product can be written in any combination of one or more programming languages, including an object-oriented programming language such as Java, C++, and / or the like, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device or entirely on the remote computing device or server.

[0081] In addition, the embodiments of the present application can also be a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, cause the processor to perform the method of dynamically measuring a mechanical seal end face gap described in the specification.

[0082] The computer readable storage medium can be embodied as one or more combinations of a readable medium and a computer readable communication medium. The computer readable storage medium can be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium can include, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium include the following: an electrical connection having one or more wires, a portable disc, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0083] The above generally describes the basic principles of the application in conjunction with specific embodiments, but it should be noted that the advantages, benefits, effects and the like mentioned in the application are only examples and are not limiting, and these advantages, benefits, effects and the like cannot be considered as necessary for each embodiment of the application. In addition, the above specific details are only for the purpose of example and understanding, and are not limiting, and the above details do not limit the application to the above specific details.

[0084] The block diagrams of the devices, apparatuses, equipment, systems involved in the application are only illustrative examples and are not intended to require or imply the connection, arrangement, configuration shown in the block diagram. As those skilled in the art will recognize, these devices, apparatuses, equipment, systems can be connected, arranged, configured in any manner. Words such as "include", "contain", "have" and the like are open-ended words, which mean "including but not limited to", and can be used interchangeably. The words "or" and "and" used herein mean the word "and / or", and can be used interchangeably unless the context clearly indicates otherwise. The word "such as" used herein means the phrase "such as but not limited to", and can be used interchangeably.

Claims

1. A method for dynamically measuring the clearance of a mechanical seal end face, characterized in that, Includes the following steps: S1: A periodic grating structure is set on the non-sealing surface of the dynamic ring and stationary ring of the mechanical seal; S2: During the operation of the mechanical seal, a dynamic image sequence of the periodic grating structure is acquired; S3: Process the acquired dynamic image sequence, extract the phase information of the periodic grating structure, and obtain phase change data; S4: Based on phase change data, calculate the relative displacement and relative rotation angle between the sealing end faces of the rotating ring and the stationary ring; S5: Monitor, provide early warnings, and assess the condition of mechanical seals.

2. The method for dynamically measuring the end face clearance of a mechanical seal according to claim 1, characterized in that, In S3: S31. Preprocess the acquired images; S32. Perform orthogonal decomposition on the grating pattern, orthogonally decompose the two perpendicular gratings to obtain two independent unidirectional gratings, one of which is parallel to the axis of the moving ring and the stationary ring. S33. Downsample the two independent unidirectional gratings after separation; S34: The downsampled discontinuous pixel sequence is processed using an interpolation method to generate a continuous cloud-patterned stripe image, and the phase of the cloud-patterned stripe image is calculated.

3. The method for dynamically measuring the end face clearance of a mechanical seal according to claim 2, characterized in that, In S33, the downsampling sampling interval is T , T It is the nearest integer of the grating pitch; During downsampling, starting from the first pixel block on one side of the raster, every... T Sampling is performed on 10 pixel blocks to obtain a period of 1000 pixels. T The first discontinuous pixel block sequence; Starting from the second pixel block, every... T Sampling is performed on 10 pixel blocks to obtain a period of 1000 pixels. T The second discontinuous pixel block sequence; Repeat the above operations to obtain T A sequence of discontinuous pixel blocks.

4. The method for dynamically measuring the end face clearance of a mechanical seal according to claim 3, characterized in that, In S34, intensity difference is applied to the missing parts of each discontinuous pixel block sequence to transform it into a continuous and smooth cloud pattern sequence. The cloud pattern phase is obtained after discrete Fourier transform of the cloud pattern sequence.

5. The method for dynamically measuring the end face clearance of a mechanical seal according to claim 4, characterized in that, Before mechanical seal deformation x The phase of the moiré pattern in the direction is : Mechanical seal deformation x The phase of the moiré pattern in the direction is : in, Indicates the mechanical seal before deformation x The intensity of the directional cloud-like stripe image; Indicates the deformation of the mechanical seal x The intensity of the directional cloud-like stripe image; T Indicates the sampling interval for downsampling; k This indicates the sequence number of the moiré pattern obtained from downsampling. ; This represents the grating intensity amplitude. p x Indicates the mechanical seal before deformation x grating pitch in the direction; Indicates the deformation of the mechanical seal x grating pitch in the direction; Indicates background intensity; Mechanical seal deformation front and rear edges x The phase difference of the moiré pattern in the direction is 。 6. A method for dynamically measuring the end face clearance of a mechanical seal according to any one of claims 1 to 5, characterized in that, In S4: S41, with the axial directions of the moving and stationary rings as... x Direction, along the grating x The relative displacement in the direction is ; in, Indicates the front and rear edges of the mechanical seal deformation x directional grating phase difference, ； p x Indicates the mechanical seal before deformation x grating pitch in the direction; The grating phase can be obtained from the moiré phase. : in This indicates that the unidirectional grating is in place after the mechanical seal deforms. x Phase of direction; This indicates that the unidirectional grating is in place after the mechanical seal deforms. x grating pitch in the direction; This indicates that the unidirectional grating is in place after the mechanical seal deforms. y grating pitch in the direction; x express x The coordinates of the orientation grating; y express y The coordinates of the orientation grating; grating and x The deflection angle of the direction is : Due to the initial time x Main direction grating and x If the direction of rotation is 90°, then the change in angle is... x for: S42. Calculate the sealing end face along the calculation steps in S41. y Relative displacement in direction and along y The deflection angle of the direction.

7. The method for dynamically measuring the end face clearance of a mechanical seal according to claim 6, characterized in that, exist( -n , n Within the threshold range of ), it is enveloped by (-π, π), and after partial derivative correction: in, Indicates the location at coordinates The grating phase difference before and after deformation of the mechanical seal at the point; Indicates the location at coordinates The grating phase difference before and after deformation of the mechanical seal at the point.

8. The method for dynamically measuring the end face clearance of a mechanical seal according to claim 6, characterized in that, The change in clearance can be obtained by capturing images of the displacement of the moving and stationary rings during the operation of the mechanical seal. d Relative angle change : in, The displacement of the grating attached to the stationary ring; The displacement of the grating attached to the moving ring; This represents the change in the angle of the grating attached to the stationary ring. This represents the change in the angle of the grating attached to the moving ring.

9. An electronic device, characterized in that, The device includes a processor, an input device, an output device, and a memory, which are connected in sequence. The memory is used to store a computer program, which includes program instructions. The processor is configured to call the program instructions to execute a dynamic measurement method for the end face clearance of a mechanical seal as described in any one of claims 1 to 4.

10. A readable storage medium, characterized in that, The storage medium stores a computer program, which includes program instructions that, when executed by a processor, cause the processor to perform a dynamic measurement method for the mechanical seal end face clearance as described in any one of claims 1 to 4.

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