Air tightness detection system and method suitable for PE pipe fittings and valves with various calibers

Abstract

The invention discloses an air tightness detection system and method suitable for PE pipe fittings and valves with various calibers, the system adopts an end connecting piece with multi-stage stepped grooves at two ends to adapt to different pipe diameters, and a self-reset switch is used for automatically identifying the step level of the pipe valve and activating a corresponding inflatable sealing ring group. During detection, the controller coordinates the inflation device to work in two ways, the sealing gas way conducts grading inflation sealing on the annular inflation sealing ring of the selected layer, the detection gas way pressurizes the closed cavity, and the pressure transmitter monitors pressure attenuation to judge the airtightness. By combining a water immersion test and a machine vision technology, bubble trajectory tracking is realized through dynamic background modeling, ROI (Region of Interest) extraction and morphological processing, and the position of a leakage point is accurately mapped. The system is provided with a sealing ring redundancy design mechanism, when leakage is detected, a standby sealing ring can be intelligently switched for reinspection verification, and the system is especially suitable for quality detection of a PE pipe fitting and a valve welding seam.

Description

Technical Field

[0001] The present application relates to the technical field of pipe airtightness detection, and discloses an airtightness detection system and method applicable to PE pipe fittings and valves of various calibers. Background Art

[0002] The airtightness detection of PE pipe fittings and valves is an important link to ensure the sealing performance of pipe fittings and valves and prevent leakage.

[0003] For example, a Chinese patent, publication number: CN220104398U, publication date: November 28, 2023, discloses an airtightness detection device for PE pipes, including a water tank. Four corners of the top of the water tank are fixedly installed with the same support frame, and both sides of the top of the support frame are fixedly installed with hydraulic cylinders. The piston ends of the hydraulic cylinders are fixedly installed with the same lifting frame. Activity grooves are opened at both ends of the bottom of the lifting frame, and movable sleeve plates are movably arranged on the inner walls of the activity grooves. An extension assembly is arranged between the movable sleeve plates, and clamping assemblies are arranged at the bottoms of the movable sleeve plates. In this utility model, the PE pipe is placed into the water in the water tank, and whether bubbles appear on the liquid surface is observed, so as to judge whether the PE pipe body is leaking air.

[0004] The disadvantages of the above technical solution are as follows: It is designed for single-specification PE pipe fittings and valves, and it is necessary to manually replace connection ports of different sizes to adapt to PE pipe fittings and valves of different calibers. The operation is cumbersome and time-consuming, especially inefficient in the scenario of mixed detection of multi-specification pipes. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the purpose of the present application is to provide an airtightness detection system and method applicable to PE pipe fittings and valves of various calibers, which can automatically adapt to PE pipe fittings and valves of various caliber specifications without manual replacement of hardware, thereby improving the detection efficiency.

[0006] To achieve the above purpose, the present application adopts the following technical solutions: The present application provides an airtightness detection system applicable to PE pipe fittings and valves of multiple calibers. The airtightness detection system includes: two end connectors, which are respectively installed at both ends of the PE pipe fitting and the valve. Each end connector is provided with a multi-stage stepped groove, and the multi-stage stepped groove is used to adapt to PE pipe fittings and valves of multiple caliber specifications. After the two end connectors are installed at both ends of the PE pipe fitting and the valve, a closed detection cavity is formed between the two end connectors and the PE pipe fitting and the valve. The detection cavity is communicated with the inside of the PE pipe fitting and the valve, and at least one end connector is provided with an air inlet communicated with the detection cavity; several groups of inflatable seals, each group of inflatable seals is respectively installed on the inner peripheral wall of each stage of the stepped groove, and each group of inflatable seals includes several inflatable seals arranged along the depth direction of the stepped groove; an inflation device; a detection air path, the inflation device is connected to the detection air path and then connected to the air inlet, and the detection air path is provided with a first solenoid valve and a pressure transmitter; a sealing air path, the inflation device is connected to the sealing air path and then connected to several groups of inflatable seals, and the sealing air path includes several branch pipelines corresponding to each inflatable seal, and each branch pipeline is respectively provided with a second solenoid valve; a controller, and the controller is respectively connected to the first solenoid valve, the pressure transmitter and each second solenoid valve.

[0007] As a preferred technical solution, the airtightness detection system further includes: a self-resetting switch, and a group of self-resetting switches are respectively arranged at the bottom of each stage of the stepped groove. The self-resetting switch is used to detect whether the bottom of each stage of the stepped groove is subjected to the pressure of the PE pipe fitting and the valve. Each group of self-resetting switches is respectively connected to the controller, and the controller identifies the stage of the stepped groove where the PE pipe fitting and the valve are placed based on the pressure signal of the self-resetting switch and shields the remaining self-resetting switches.

[0008] As a preferred technical solution, the airtightness detection system further includes: a camera module, immersing the two end connectors, the PE pipe fitting and the valve in water together, and the camera module is used to take images of bubbles and air leakage points.

[0009] As a preferred technical solution, the airtightness detection system further includes: an image preprocessing module, which is used to perform denoising, dynamic background modeling and ROI extraction on the images taken by the camera module; a bubble detection module, which is used to perform dynamic threshold segmentation, morphological filtering and contour detection and screening on the ROI images extracted by the image preprocessing module; a leakage position judgment module, which is used to calculate the left side of the bubble center, map it to a preset area and judge the leakage position for the image contours screened by the bubble detection module.

[0010] The present application also provides an airtightness detection method applicable to PE pipe fittings and valves of multiple calibers. The airtightness detection method includes: S1, respectively installing the two end connectors at both ends of the PE pipe fitting and the valve; S2. A group of self - reset switches is pressured by the PE pipe fittings and valves. The controller identifies the level of the stepped groove where the PE pipe fittings and valves are placed based on the pressure signals of the self - reset switches and shields the remaining self - reset switches. S3. The solenoid valve two connected to the inflatable seal ring corresponding to this level of stepped groove is opened. The inflating device inflates the inflatable seal ring corresponding to this level of stepped groove through the sealing air path, and the inflatable seal ring seals the two end connectors with the PE pipe fittings and valves. S4. The solenoid valve one is opened, and the inflating device inflates the detection cavity through the detection air path. S5. The pressure transmitter detects the air pressure in the detection cavity, converts the pressure signal into an electrical signal and sends it to the controller. The controller compares with the standard pressure curve to judge whether the detection cavity leaks air, and further judges the airtightness of the PE pipe fittings and valves.

[0011] As a preferred technical solution, the airtightness detection method further includes: S6. If the detection cavity does not leak air, it is judged that the airtightness of the PE pipe fittings and valves is good. If the detection cavity leaks air, the following steps are executed: S7. Immerse the two end connectors, the PE pipe fittings and the valves in water together, and the camera module takes pictures of the bubbles and the leakage points. S8. Perform denoising, dynamic background modeling and ROI extraction on the images taken by the camera module. S9. Perform dynamic threshold segmentation, morphological filtering, and contour detection and screening on the extracted ROI images. S10. Perform calculations on the center coordinates of the bubbles, map them to a preset area, and judge the leakage position for the screened image contours. S11. If the leakage position is at the welding point of the PE pipe fittings and valves, it is judged that the welding quality does not meet the standard.

[0012] As a preferred technical solution, the airtightness detection method further includes: S12. Define the numbers of each inflatable seal ring as: Lij or Rij, where L represents the inflatable seal ring on the left end connector, R represents the inflatable seal ring on the right end connector, i represents the i - th level of stepped groove, and j represents the j - th inflatable seal ring at this level of stepped groove. S13. Set j to 0. S14. If the leakage position is on the left, increment j by 1 in Lij; if the leakage position is on the right, increment j by 1 in Rij. S15. If j > 2 in Lij or j > 2 in Rij, output the leakage position; otherwise, start the Lij and Rij - numbered inflatable seal rings, jump to step S4 and continue to execute the subsequent steps.

[0013] Compared with the prior art, the beneficial effects of the present application are as follows: Through the multi-stage stepped groove design of the end connector, the present application can be compatible with PE pipe fittings and valves of different caliber specifications, solving the limitation of traditional detection devices only targeting a single pipe diameter. In addition, by integrating the solenoid valve and the pressure transmitter in the controller, the present application realizes the full-process automation of inflation, pressure maintenance, and detection of PE pipe fittings and valves. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic structural diagram of an airtightness detection system for PE pipe fittings and valves of multiple calibers according to the present application; Figure 2 is a flowchart of a method for detecting the airtightness of PE pipe fittings and valves of multiple calibers according to the present application; Figure 3 is a flowchart of the steps of image processing of the camera module; Wherein: 1. End connector; 2. Support base; 3. Gas tank; 4. Air compressor; 5. Controller; 6. Detection gas path; 7. Sealing gas path; 8. Solenoid valve II; 9. Solenoid valve I; 10. Pressure transmitter; 11. Connecting sleeve; 12. Steel pipe; 13. PE pipe; 14. L11 inflation seal ring; 15. L12 inflation seal ring; 16. L21 inflation seal ring; 17. R11 inflation seal ring; 18. Self-resetting switch. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the specific embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application.

[0016] As Figure 1 shown, the present application provides an airtightness detection system for PE pipe fittings and valves of multiple calibers.

[0017] In the present application, the PE pipe fittings and valves include: a PE pipe 13, a steel pipe 12, and a connecting sleeve 11. The PE pipe 13 and the steel pipe 12 are coaxially arranged, and the connecting sleeve 11 is sleeved on the outer periphery of the relatively close ends of the PE pipe 13 and the steel pipe 12 and fixedly connects the PE pipe 13 and the steel pipe 12.

[0018] The PE pipe fittings and valves are fixedly installed on the support base 2 so that the PE pipe fittings and valves are stably supported and do not shake during the airtightness detection.

[0019] The airtightness detection system includes: two end connectors 1, several groups of inflation seal rings, an inflation device, a detection gas path 6, a sealing gas path 7, and a controller 5.

[0020] Two end connectors 1 are respectively installed at both ends of the PE pipe fitting and the valve. The end connector 1 is used to seal the opposite ends of the PE pipe fitting and the valve. Each end connector 1 is provided with a multi-stage stepped groove, and the multi-stage stepped groove is used to adapt to PE pipe fittings and valves of various caliber specifications. When the PE pipe fitting and the valve are inserted into the end connector 1, due to different caliber specifications, the insertion depths of the PE pipe fitting and the valve and the number of stepped grooves in contact are different.

[0021] In this application, the end connector 1 adopts a cylindrical sleeve structure, and three-stage stepped grooves are arranged inside, corresponding to the caliber specifications of PE pipe fittings and valve orifices of DN20 (inner diameter 20 mm), DN50 (inner diameter 50 mm), and DN110 (inner diameter 110 mm) respectively. The depth of the stepped groove is 10 mm.

[0022] After the two end connectors 1 are installed at both ends of the PE pipe fitting and the valve, a closed detection cavity is formed by the two end connectors 1, the PE pipe fitting and the valve. The detection cavity is communicated with the inside of the PE pipe fitting and the valve, and at least one end connector 1 is provided with an air inlet communicated with the detection cavity.

[0023] Each group of inflatable seals are respectively installed on the inner peripheral walls of each stage of stepped grooves. Each group of inflatable seals includes a plurality of inflatable seals arranged along the depth direction of the stepped groove. After the inflatable seals are inflated, they abut against the outer peripheral surfaces of the PE pipe fitting and the valve to seal the end connector 1, the PE pipe fitting and the valve.

[0024] Define the numbers of each inflatable seal as: Lij or Rij, where L represents the inflatable seal on the left end connector 1, R represents the inflatable seal on the right end connector 1, i represents the i-th stage of stepped groove, and j represents the j-th inflatable seal at this stage of stepped groove. It should be noted that the smaller i and j are, the closer they are to the PE pipe fitting and the valve.

[0025] In this application, 3 inflatable seals are respectively arranged at each stage of stepped groove. Exemplarily, Figure 1 among them: the L11 inflatable seal 14, the L12 inflatable seal 15, the L21 inflatable seal 16, and the R11 inflatable seal 17.

[0026] In this application, the inflatable seals are made of nitrile rubber material. A plurality of independent inflatable cavities are circumferentially and evenly arranged inside the inflatable seals, and the radial expansion amount of the inflatable seals after inflation is 2 - 5 mm.

[0027] In this application, the inflating device includes an air tank 3 and an air compressor 4.

[0028] The inflation device is connected to the intake port after being connected to the detection air circuit 6. A first electromagnetic valve 9 and a pressure transmitter 10 are provided on the detection air circuit 6. The inflation device sends air into the detection cavity through the detection air circuit 6. The pressure transmitter 10 converts the gas pressure into an electrical signal and transmits the electrical signal to the controller 5.

[0029] The inflation device is connected to a plurality of groups of inflation seals after being connected to the sealing air circuit 7. The sealing air circuit 7 includes a plurality of branch pipelines corresponding to the respective inflation seals. A second electromagnetic valve 8 is provided on each branch pipeline. The inflation device sends air into the inflation seals through the sealing air circuit 7 so that the inflation seals expand, thereby sealing the end connectors 1, the PE pipe fittings and the valves.

[0030] The controller 5 is respectively connected to the first electromagnetic valve 9, the pressure transmitter 10 and each second electromagnetic valve 8.

[0031] As a preferred technical solution, the airtightness detection system further includes: a self-resetting switch 18. A group of self-resetting switches 18 are provided at the bottom of each step groove. The self-resetting switch 18 is used to detect whether the bottom of each step groove is subjected to the pressure of the PE pipe fittings and the valves. Each group of self-resetting switches 18 is respectively connected to the controller 5. The controller 5 identifies the level of the step groove where the PE pipe fittings and the valves are placed based on the pressure signals of the self-resetting switches 18 and shields the remaining self-resetting switches 18.

[0032] In this application, the self-resetting switch 18 adopts a pressure sensor or the like. The model of the pressure sensor is Futek PFS-350, and the measuring range is 0-50N. The surface of the pressure sensor is flush with the bottom surface of the step groove and is used to detect the contact pressure when the PE pipe fittings and the valves are inserted.

[0033] As a preferred technical solution, the airtightness detection system further includes: a camera module. The two end connectors 1, the PE pipe fittings and the valves are immersed in water together. The camera module is used to capture images of bubbles and air leakage points.

[0034] In this application, the camera module includes two cameras. The two end connectors 1, the PE pipe fittings and the valves are immersed in a water tank together. The two cameras are respectively arranged on both sides of the water tank. The optical axes of the cameras are perpendicular to the axis of the PE pipe fittings and the valves and cover the entire submerged area of the PE pipe fittings and the valves and the two end connectors 1 (about 500mm×300mm), and can clearly capture the movement trajectories of minute bubbles.

[0035] For air leakage point positioning, a high-precision coordinate grid is pasted at the bottom of the water tank, and the two cameras are stereoscopically calibrated using the checkerboard calibration method, the internal and external parameters are calculated, and a three-dimensional coordinate system is established.

[0036] According to the specification parameters of PE pipe fittings and valves, three-dimensional models of the outer surfaces of PE pipe fittings and valves are pre-stored in the main control system. The initial position of the bubble is mapped to the cylindrical surfaces of the PE pipe fittings and valves through coordinate transformation, and converted into circumferential angle and axial position to map the outer surfaces of the PE pipe fittings and valves.

[0037] At the position of 45° above the two cameras, a set of near-infrared light sources are installed respectively, and a milky white diffuser plate is installed in front of the near-infrared light sources. The diffuser plate converts the direct light into uniform scattered light, illuminating the water body in the water tank, making the brightness contrast between the bubbles and the surrounding water obvious, which is convenient for subsequent image recognition.

[0038] As a preferred technical solution, the airtightness detection system further includes: an image preprocessing module, a bubble detection module, and a leakage position judgment module. The image preprocessing module is used to perform denoising, dynamic background modeling, and ROI extraction on the images captured by the camera module. The bubble detection module is used to perform dynamic threshold segmentation, morphological filtering, and contour detection and screening on the ROI images extracted by the image preprocessing module. The leakage position judgment module is used to calculate the bubble center position, map it to a preset area, and judge the leakage position for the image contours screened by the bubble detection module.

[0039] As Figure 2 shown, the present application also provides an airtightness detection method applicable to PE pipe fittings and valves of multiple calibers. The airtightness detection method includes: S1. Install two end connectors 1 at both ends of the PE pipe fitting and the valve respectively; S2. A certain group of self-resetting switches 18 are subjected to the pressure of the PE pipe fitting and the valve, and the controller 5 identifies the step groove in which the PE pipe fitting and the valve are placed based on the pressure signal of the self-resetting switch 18 and shields the remaining self-resetting switches 18; S3. The solenoid valve II 8 connected to the inflatable seal ring corresponding to this step groove is opened, and the inflating device inflates the inflatable seal ring corresponding to this step groove through the sealing air path 7, and the inflatable seal ring seals the two end connectors 1 and the PE pipe fitting and the valve; S4. The solenoid valve I 9 is opened, and the inflating device inflates the detection cavity through the detection air path 6; S5. The pressure transmitter 10 detects the air pressure in the detection cavity and converts the pressure signal into an electrical signal and sends it to the controller 5. The controller 5 compares the standard pressure curve to judge whether the detection cavity leaks air, and further judges the airtightness of the PE pipe fitting and the valve; S6. If the detection cavity does not leak air, it is judged that the airtightness of the PE pipe fitting and the valve is good. If the detection cavity leaks air, the following steps are performed: S7. Immerse the two end connectors 1 and the PE pipe fitting and the valve together in water, and the camera module takes images of the bubbles and the air leakage points; AsFigure 3 As shown S8 performs noise reduction, dynamic background modeling, and ROI extraction on the images captured by the camera module; Noise reduction: The captured grayscale image is "denoised" through Gaussian filtering to remove random noise generated by light fluctuations or tiny impurities in the water, making the image smoother for subsequent bubble detection.

[0040] Dynamic background modeling: Before detection, 50 images without bubbles are captured first. The average value of these images is calculated through dynamic background modeling as the background model. Subsequently, the images captured in real time will be compared with this background model, and the stable background will be automatically subtracted, only retaining the dynamically changing part.

[0041] ROI (Region of Interest) extraction: ROI refers to the region of interest, which is a specific object or target within a specified region in image processing, including features such as the contour, edge, and texture of the object.

[0042] S9 performs dynamic threshold segmentation, morphological filtering, and contour detection and screening on the extracted ROI images; Dynamic threshold segmentation: According to the brightness distribution of the real-time image, the brightness threshold is automatically calculated, and the pixels in the image are divided into two parts: "possibly a bubble" and "not a bubble", generating a binary black-and-white image, where white represents bubbles and black represents the background.

[0043] Morphological filtering: The binary image is preprocessed. First, the broken bubble edges are connected, and then isolated small noise points are removed, finally retaining the complete bubble contour.

[0044] S10 calculates the bubble center coordinates, maps them to a preset area, and determines the leakage location for the screened image contours; If a bubble is detected, the bubble center coordinates are calculated and mapped to the position area of the preset multi-parameter airtightness detection system to determine the leakage location.

[0045] Bubble positioning and leakage area determination include center coordinate calculation and three-dimensional coordinate conversion and area division.

[0046] Through center coordinate calculation, the geometric center position of the bubble area in the image is calculated for each detected bubble, and the geometric center position of the bubble area is used as the pixel coordinates of the bubble in the image.

[0047] 3D coordinate transformation and area division: Using the calibrated camera parameters, the pixel coordinates in the image are converted into the actual 3D coordinates (X, Y, Z) inside the water tank. According to the structure of the PE pipe fittings and valves, three leakage areas and the actual coordinates where bubbles initially appear are preset, and it is determined which area they belong to: if it is within the welding point area, it is marked in red; if it is within the seal area, it is marked in blue; other areas are marked in yellow and are displayed in real time on the human-machine interface.

[0048] The three leakage areas include the welding point area, the seal area, and other areas. The welding point area is within 50 mm on both sides of the end of the connecting sleeve 11 (along the length direction of the PE pipe fittings and valves); the end connector 1 area is within 30 mm of the ends of the PE pipe fittings and valves (along the length direction of the PE pipe fittings and valves); other areas are the non-above-mentioned areas of the main body of the PE pipe fittings and valves.

[0049] S11, if the leakage position is at the welding point of the PE pipe fittings and valves, it is determined that the welding quality does not meet the standard; S12, define the numbers of each inflatable seal ring as: Lij or Rij, where L represents the inflatable seal ring on the left end connector 1, R represents the inflatable seal ring on the right end connector 1, i represents the i-th stepped groove, and j represents the j-th inflatable seal ring at this stepped groove; S13, set j to 0; S14, if the leakage position is on the left, then j + 1 in Lij; if the leakage position is on the right, then j + 1 in Rij; S15, if j > 2 in Lij or j > 2 in Rij, then output the leakage position; otherwise, activate the Lij and Rij numbered inflatable seal rings, jump to step S4 and continue to execute the subsequent steps.

[0050] It should be noted that the "first", "second" and similar words used in the specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "a" or "one" do not indicate a quantity limitation, but indicate that there is at least one. "Multiple" or "several" means at least two. Unless otherwise specified, words such as "front", "rear", "left", "right", "lower" and / or "upper" are only for convenience of description and are not limited to one position or a spatial orientation. "Including" or "comprising" and similar words mean that the elements or objects appearing before "including" or "comprising" cover the elements or objects listed after "including" or "comprising" and their equivalents, and do not exclude other elements or objects. "Connect" or "be connected" and similar words are not limited to physical or mechanical connections, and may include electrical connections, whether direct or indirect.

[0051] As used in the specification of this application and the appended claims, the singular forms "a", "the" and "said" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0052] It should be understood that those of ordinary skill in the art can make improvements or modifications based on the above description, and all such improvements and modifications shall fall within the scope of protection of the appended claims of this application.

Claims

1. An airtightness detection system applicable to PE pipe fittings and valves of multiple calibers, characterized in that The airtightness detection system includes: Two end connectors, which are respectively installed at both ends of the PE pipe fitting and the valve. Each end connector is provided with multi-level stepped grooves, and the multi-level stepped grooves are used to adapt to PE pipe fittings and valves of various caliber specifications. After the two end connectors are installed at both ends of the PE pipe fitting and the valve, the two end connectors and the PE pipe fitting and the valve enclose a closed detection cavity, and the detection cavity is communicated with the inside of the PE pipe fitting and the valve. At least one end connector is provided with an air inlet communicated with the detection cavity; Several groups of inflatable seals, each group of inflatable seals are respectively installed on the inner peripheral walls of each level of stepped grooves, and each group of inflatable seals includes several inflatable seals arranged along the depth direction of the stepped grooves; An inflation device; A detection gas path, the inflation device is connected to the detection gas path and then connected to the air inlet, and a solenoid valve I and a pressure transmitter are arranged on the detection gas path; A sealing gas path, the inflation device is connected to the sealing gas path and then connected to the several groups of inflatable seals. The sealing gas path includes several branch pipelines corresponding to each inflatable seal, and a solenoid valve II is respectively arranged on each branch pipeline; A controller, which is respectively connected to the solenoid valve I, the pressure transmitter and each solenoid valve II.

2. The airtightness detection system applicable to PE pipe fittings and valves of multiple calibers according to claim 1, characterized in that, The airtightness detection system further includes: A self-resetting switch, a group of the self-resetting switches are respectively arranged at the bottom of each level of stepped grooves. The self-resetting switch is used to detect whether the bottom of each level of stepped grooves is subjected to the pressure of the PE pipe fitting and the valve. Each group of self-resetting switches are respectively connected to the controller, and the controller identifies the level of stepped groove where the PE pipe fitting and the valve are placed based on the pressure signal of the self-resetting switch and shields the remaining self-resetting switches.

3. The airtightness detection system applicable to PE pipe fittings and valves of multiple calibers according to claim 1, characterized in that The airtightness detection system further includes: A camera module, immersing the two end connectors, the PE pipe fitting and the valve in water together. The camera module is used to take images of bubbles and leakage points.

4. The airtightness detection system applicable to PE pipe fittings and valves of multiple calibers according to claim 3, characterized in that, The airtightness detection system further includes: An image preprocessing module, which is used to perform denoising, dynamic background modeling and ROI extraction on the images taken by the camera module; A bubble detection module, which is used to perform dynamic threshold segmentation, morphological filtering and contour detection and screening on the ROI images extracted by the image preprocessing module; A leakage position judgment module, which is used to calculate the left side of the bubble center, map it to a preset area and judge the leakage position for the image contours screened by the bubble detection module.

5. A method for airtightness detection applicable to PE pipe fittings and valves of multiple calibers, characterized in that, The airtightness detection method includes: S1, installing the two end connectors at both ends of the PE pipe fitting and the valve respectively; S2, when a certain group of self-resetting switches is subjected to the pressure of the PE pipe fitting and the valve, the controller identifies the level of stepped groove where the PE pipe fitting and the valve are placed based on the pressure signal of the self-resetting switch and shields the remaining self-resetting switches; S3, opening the solenoid valve II connected to the inflatable seal corresponding to this level of stepped groove, and the inflation device inflates the inflatable seal corresponding to this level of stepped groove through the sealing gas path, and the inflatable seal blocks the two end connectors and the PE pipe fitting and the valve; S4. Once the solenoid valve is opened, the inflation device inflates the detection cavity through the detection air circuit. S5. The pressure transmitter detects the air pressure in the detection cavity, converts the pressure signal into an electrical signal and sends it to the controller. The controller compares the standard pressure curve to determine whether the detection cavity leaks air, and further determines the airtightness of the PE pipe fitting and the valve.

6. The airtightness detection method applicable to PE pipe fittings and valves of multiple calibers according to claim 5, characterized in that, The airtightness detection method further includes: S6. If the detection cavity does not leak air, it is determined that the airtightness of the PE pipe fitting and the valve is good. If the detection cavity leaks air, the following steps are executed: S7. Immerse the two end connectors, the PE pipe fitting and the valve in water together, and the camera module takes images of the bubbles and the air leakage points. S8. Perform desoiling, dynamic background modeling and ROI extraction on the images taken by the camera module. S9. Perform dynamic threshold segmentation, morphological filtering, and contour detection and screening on the extracted ROI images. S10. Perform calculations on the screened image contours to obtain the bubble center coordinates, map them to a preset area, and determine the leakage position. S11. If the leakage position is at the welding point of the PE pipe fitting and the valve, it is determined that the welding quality does not meet the standard.

7. The airtightness detection method applicable to PE pipe fittings and valves of multiple calibers according to claim 6, characterized in that, The airtightness detection method further includes: S12. Define the numbers of each inflation sealing ring as: Lij or Rij, where L represents the inflation sealing ring on the left end connector, R represents the inflation sealing ring on the right end connector, i represents the i-th stepped groove, and j represents the j-th inflation sealing ring at this stepped groove. S13. Set j to 0. S14. If the leakage position is on the left side, increment j by 1 in Lij; if the leakage position is on the right side, increment j by 1 in Rij. S15. If j > 2 in Lij or j > 2 in Rij, output the leakage position; otherwise, activate the Lij and Rij numbered inflation sealing rings, jump to step S4 and continue to execute the subsequent steps.

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