CN118816775A - An automatic detection device for gas cylinder plastic liner, three-dimensional reconstruction algorithm and analysis method - Google Patents

Abstract

The present invention discloses an automatic detection device for the plastic liner of a gas cylinder, a three-dimensional reconstruction algorithm and an analysis method. The present invention realizes a full-circle scanning of the plastic liner by arranging a first phased array probe and a second phased array probe to respectively collect ultrasonic monitoring information data of the plastic liner cylinder and the head end; by designing a three-dimensional reconstruction algorithm, combining the position data of a rotation angle acquisition mechanism and an axial position acquisition mechanism, the data are correlated and reconstructed into the three-dimensional data of the entire plastic liner; by using an analysis method, the outer diameter, cylinder length, roundness, straightness, wall thickness, internal defects and other information of the plastic liner are analyzed and evaluated, the scanning process is fully automatic, the degree of automation is high, the precision is high, the labor intensity is low, and the detection of the plastic liner is convenient.

Description

An automatic detection device for the plastic liner of a gas cylinder, a three-dimensional reconstruction algorithm and an analysis method

Technical Field

The present invention relates to the technical field of vehicle-mounted high-pressure hydrogen storage cylinders, in particular to the technical field of automatic detection devices for plastic inner liners of cylinders, three-dimensional reconstruction algorithms and analysis methods.

Background Art

On-board high-pressure hydrogen storage cylinders are key equipment in the hydrogen energy industry. The mainstream cylinders include carbon fiber fully wrapped cylinders with aluminum liners and plastic liners. Plastic liners with carbon fiber fully wrapped cylinders have the advantages of small size, light weight and low cost. The plastic liner is often formed by a split welding process, and the injection-molded heads at both ends and the extruded cylinder are hot plated or laser welded. In the split welding process, the plastic liner and the metal valve seat of the head are formed at one time, but there are multiple welds on the plastic liner. The dimensional accuracy and positional accuracy of the head and the cylinder affect the amount of weld misalignment, and the heating temperature, heating time, and welding pressure affect the mechanical properties of the weld, increasing the possibility of fatigue damage and buckling failure. Therefore, it is necessary to perform off-line testing on the weld and the entire plastic liner.

The outer surface inspection and water pressure test of the plastic liner can determine the overall condition, and the phased array ultrasonic testing technology can detect the welding quality of the plastic liner weld. However, the processes of outer surface inspection and phased array ultrasonic testing technology are not yet mature, which affects the efficiency of plastic liner molding inspection. Therefore, the off-line inspection of plastic liner molding faces the following technical difficulties: 1. The outer surface inspection includes appearance contour, roundness, straightness, and barrel length. The inspection requires many instruments and the process is complicated; 2. The automation level of plastic liner inspection supporting phased array ultrasonic testing technology is low, and the coupling effect of handheld phased array probes in detecting welds is discontinuous; 3. The integration level of the outer surface inspection data and phased array ultrasonic testing data obtained by the inspection is low, and they are not displayed digitally.

Summary of the invention

The purpose of the present invention is to solve the problems in the prior art and to propose an automatic detection device for the plastic liner of a gas cylinder, a three-dimensional reconstruction algorithm and an analysis method, which can automatically detect the plastic liner, solve multiple detection needs at one time, and effectively improve the detection efficiency.

To achieve the above-mentioned purpose, the present invention proposes an automatic detection device for the plastic liner of a gas cylinder, comprising a plastic liner fixing mechanism, a rotation driving mechanism for cooperating with the plastic liner fixing mechanism to drive the plastic liner fixed on the plastic liner fixing mechanism to rotate around its axis, and a detection water tank cooperating with the plastic liner fixing mechanism, wherein the plastic liner fixing mechanism fixes the plastic liner on the upper side of the detection water tank, wherein a cylinder detection device arranged toward the plastic liner section and two end section detection devices arranged toward the two ends of the plastic liner are arranged in the detection water tank, wherein the lower ends of the cylinder detection device and the end section detection device are both provided with a moving mechanism for driving them to move axially along the plastic liner; the cylinder detection device comprises a first phased array probe arranged toward the cylinder section of the plastic liner, and the end section detection device comprises a second phased array probe arranged toward the end section of the plastic liner, wherein the second phased array probe is arc-shaped and matches the end section of the plastic liner;

It also includes a rotation angle acquisition mechanism for cooperating with the rotation drive mechanism to monitor the rotation angle of the plastic liner, and an axial position acquisition mechanism for cooperating with the lower moving mechanism of the cylinder detection device to monitor the position of the moving mechanism, and also includes a control system. The control system is connected to the first phased array probe, the second phased array probe, the rotation angle acquisition mechanism, and the axial position acquisition mechanism for data communication. The control system obtains the ultrasonic detection data of the first phased array probe and the second phased array probe and combines the position data of the rotation angle acquisition mechanism and the axial position acquisition mechanism, and associates the data to reconstruct the three-dimensional data of the entire plastic liner.

Preferably, the plastic liner fixing mechanism comprises a first centering component adapted to a head at one end of the plastic liner and a second centering component adapted to a head at the other end of the plastic liner, the first centering component and the second centering component are respectively arranged on a fixed support and a movable support, the movable support is provided with a moving component for controlling the support and/or the centering component arranged on the support to move closer to or away from the plastic liner, and the rotation drive mechanism is a rotating motor arranged on the fixed support for driving the first centering component or the second centering component to rotate around its axis.

Preferably, the moving component comprises an electric push rod, which is arranged on the moving support and is used to drive the second centering component to move closer to or away from the plastic liner.

Preferably, the movable component also includes a support guide rail arranged on the lower side of the movable support, and the movable support can be slidably arranged on the support guide rail; the movable support is also provided with a slide seat and an auxiliary adjustment support arranged on the slide seat, the first centering component or the second centering component is arranged on the auxiliary adjustment support, and a handle connected to the slide seat control is provided at one end of the slide seat.

Preferably, a roller frame assembly for supporting the plastic liner is provided in the detection water tank, and the roller frame assembly includes a first wheel frame and a second wheel frame arranged relatively to each other, and the top of the first wheel frame and the second wheel frame are both provided with wheels for cooperating with the plastic liner, and a roller spacing adjustment device is provided between the first wheel frame and the second wheel frame, and the roller spacing adjustment device includes a bidirectional screw rod laterally arranged between the first wheel frame and the second wheel frame, and a roller motor for driving the bidirectional screw rod to rotate, the bidirectional screw rod has opposite threads from the center to both ends, and the first wheel frame and the second wheel frame are respectively connected to the threads at both ends of the bidirectional screw rod through a first nut and a second nut.

Preferably, the moving mechanism includes a detection trolley, a trolley guide rail is provided in the detection water tank, the detection trolley is slidably arranged on the trolley guide rail, the detection trolley is provided with a first probe holder corresponding to the first phased array probe or a second probe holder corresponding to the second phased array probe, the detection trolley is provided with a plurality of vertically arranged guide rods, an intermediate lifting plate is transversely provided between the guide rods, the intermediate lifting plate is axially slidably arranged on the guide rods, the first probe holder or the second probe holder is arranged on the intermediate lifting plate, the detection trolley includes a translation base plate provided on the lower side of the intermediate lifting plate, a lifting mechanism is provided between the translation base plate and the intermediate lifting plate, the lifting mechanism includes a lifting screw and a lifting nut respectively provided on the translation base plate and the intermediate lifting plate, and a longitudinal servo motor for driving the lifting screw to rotate is provided at one end of the lifting screw.

Preferably, a probe mounting plate is further provided on the upper side of the intermediate lifting plate, the first probe bracket or the second probe bracket is fixedly provided on the probe mounting plate, the probe mounting plate is axially slidable on the guide rod, and a plurality of vertically arranged elastic support members are provided between the probe mounting plate and the intermediate lifting plate.

Preferably, the trolley guide rail of the lower moving mechanism of the barrel detection device is provided with a rack arranged along its length direction, and the corresponding detection trolley is provided with a gear meshing with the rack and a trolley motor for driving the gear to rotate, the axial position acquisition mechanism is an axial encoder, and the trolley motor is provided with an axial encoder synchronously connected to its rotating shaft.

Another object of the present invention is to propose a three-dimensional reconstruction algorithm for automatic detection of the plastic liner of a gas cylinder, comprising the following steps: Step 1: Three-dimensional reconstruction of the plastic liner cylinder segment, establishing an image coordinate system {A}, the center coordinates of the first group of excitation apertures of the first phased array probe are the origin of the image coordinate system {A} , the array arrangement direction is taken as the x-axis of the image coordinate system {A}, and the depth direction is taken as the z-axis of the image coordinate system {A}. Then the position of a point P in the image after imaging in {A} is expressed as ;

Step 2: Establish the rotating coordinate system {B} of the plastic liner, and set the position of the mouth of the plastic liner as the origin of the rotating coordinate system {B} , and the central axis of the plastic liner is the x-axis of the coordinate system {B}, and the cross section of the plastic liner cylinder is the yz plane. Since the axes of the rotating coordinate system {B} are parallel to the axes of the coordinate system {A}, the origin of the image coordinate system {A} The coordinates in the rotating coordinate system {B} can be expressed as the translation vector ;

During the first inspection, move the first phased array probe to the position directly above the center axis of the plastic liner. =0, According to the first phased array probe position data collected by the axial position acquisition mechanism, It is obtained by measuring the vertical distance difference between the first centering component and the surface of the first phased array probe; then the position of any point P in the image in the coordinate system {B} ;

Step 3: Rotate and scan the image coordinate transformation. The position of any point P in the nth rotated image in the coordinate system {B} is , the nth rotated image is Axis rotation angle, is the angle between two adjacent ultrasound images. This rotation angle is opposite to the rotation angle of the plastic liner. In this embodiment, the scanned image rotates counterclockwise, and the coordinate transformation matrix R is ; Step 4: Three-dimensional reconstruction of the plastic liner head section, establish the coordinate system {A'} of the ultrasonic detection image, the center coordinates of the first group of excitation apertures of the second phased array probe are taken as the origin O, the array arrangement direction is taken as the x-axis, and the depth direction is taken as the z-axis. The position of a point P' in {A'} can be expressed as ; Step 5: Establish the auxiliary coordinate system {B'}, and the center of the plastic liner's head sphere is used as the origin of the auxiliary coordinate system {B'} , the central axis of the plastic liner is used as the x-axis of the auxiliary coordinate system {B'}, and the z-axis of the auxiliary coordinate system {B'} is parallel to the coordinate system {A'};

The relationship between the auxiliary coordinate system {B'} and the origin of the coordinate system {A'} is expressed by the translation vector Indicates that the position of point P' in the auxiliary coordinate system {B'} in , , is the position of the second phased array probe in the auxiliary coordinate system {B'}, r is the radius of the spherical head, h is the distance between the second phased array probe and the water layer on the outer surface of the head, The angle between the line connecting the origins of the probe coordinate system {A'} and {B'} and the x-axis of the auxiliary coordinate system {B'};

Step 6: Convert each coordinate in the auxiliary coordinate system {B'} into the rotating coordinate system {B} used by the cylinder section, and the translation vector of the head on the same side , the translation vector of the side head ,by The rotation angle about the axis is , Point P' on the rotated image is in the rotated coordinate system {B} , where l is the axial length of the barrel section;

Step 7: Integrate the model, match the ultrasonic test results with the actual cylinder test parts, and obtain a three-dimensional reconstructed model of the entire plastic liner.

Another object of the present invention is to provide an analysis method for automatic detection of the plastic liner of a gas cylinder, comprising the following steps: Step S1, external surface inspection, the external surface inspection is carried out by rotating the coordinate system {B} Axis and The n value of the rotation angle is used as the position description, Decomposed into m and p, representing the mth group of excitation apertures, p is the array element spacing of the phased array probe; under the nth rotating image and the mth group of excitation apertures, the outer radius of the plastic liner is in, The thickness of the water layer is obtained by calculating the echo time of the interface between water and the plastic liner in the A-scan signal of the phased array ultrasonic detection data;

Drive the plastic liner to rotate 180°, and the detection process ensures the detection position of the phased array probe unchanged; and collect and record the position detection data, the outer diameter of the plastic liner is Where N is the number of images detected when the plastic liner rotates one circle;

At a certain axial position m, the average outer diameter of the entire circumference of the plastic liner is ; At a certain circumferential position n, the average outer diameter of the entire axial direction of the plastic liner is ;

M is the number of excitation apertures distributed along the length of the cylinder, ; is the starting excitation aperture number of the first phased array probe, is the end excitation aperture number of the first phased array probe; the excitation aperture numbers at the start and end are the connection positions of the plastic liner barrel section and the head section, which are obtained by comparing whether the average outer diameter of each axial position on the boundary increases continuously; the length of the plastic liner barrel is ;

At a certain axial position m, the maximum circumferential outer wall radius is , the minimum outer wall radius is , the roundness of the cross section at this axial position is ;

At each axial position of the plastic liner cylinder section, the maximum outer wall radius is , the minimum outer wall radius is The cylindricality of the plastic liner section is ; At a certain circumferential position n, the maximum axial outer wall radius is , the minimum outer wall radius is , the straightness of the plastic liner cylinder section is ;

Under the nth rotating image and mth set of excitation apertures, the wall thickness of the plastic liner is in, It is obtained by calculating the echo time of the inner wall of the plastic liner in the A-scan signal of the phased array ultrasonic detection data and the sound speed in water. is the speed of sound in water, is the speed of sound in the plastic liner; exist Position uses color scale to draw thickness cloud map, if it exists Draw the location with a special color, It is the standard thickness of plastic liner;

Step S2, internal defect analysis, when there are other reflection signals on the outer wall and inner wall of the plastic liner in the phased array ultrasonic detection data, defect analysis and statistics are performed; in the rotating coordinate system {B}, the defect position is expressed as Among them, x, x', y, y', z, z' are the three-dimensional boundaries of the defect in the coordinate system {B}, which are obtained by combining the adjacent phased array ultrasonic testing data; the defect size is expressed as Count the number, size and distribution of defects through lists to prepare for subsequent defect assessment

The beneficial effects of the automatic detection device, three-dimensional reconstruction algorithm and analysis method of the plastic liner of a gas cylinder of the present invention are as follows: the present invention arranges a first phased array probe and a second phased array probe to respectively collect ultrasonic monitoring information data of the plastic liner cylinder and the head end and combines the position data of the rotation angle collection mechanism and the axial position collection mechanism, and associates the data to reconstruct the three-dimensional data of the entire plastic liner, so as to realize a full circumferential scan of the plastic liner and reconstruct the three-dimensional data of the entire plastic liner. The scanning process is fully automatic, with a high degree of automation and low manual labor intensity, and is convenient for detecting the plastic liner.

The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the three-dimensional structure of an automatic detection device for a plastic liner of a gas cylinder according to the present invention.

FIG. 2 is a schematic diagram of the side structure of the roller frame assembly.

FIG. 3 is a schematic diagram of a partial top view of the roller frame assembly.

FIG. 4 is a schematic diagram of the main structure of the detection vehicle and the first phased array probe.

FIG. 5 is a schematic diagram of the side view structure of the detection vehicle and the first phased array probe.

FIG. 6 is a schematic diagram of the main structure of the detection vehicle and the second phased array probe.

FIG. 7 is a schematic diagram of a three-dimensional reconstruction of a plastic liner cylinder segment.

FIG8 is a schematic diagram of a three-dimensional reconstruction of the side view of the plastic liner cylinder section of the present invention.

FIG. 9 is a schematic diagram of a three-dimensional reconstruction of the plastic liner head section in the present invention.

FIG. 10 is a schematic diagram of phased array detection results in the present invention.

FIG. 11 is a schematic diagram showing the scanning condition of the plastic liner cylinder section in the present invention.

FIG. 12 is a schematic diagram of a thickness cloud diagram in the present invention.

In the figure: 1-handle, 2-slide seat, 4-adjustment support, 5-electric push rod, 7-elastic retaining ring for inner ring shaft, 8-sleeve, 9-bearing, 10-elastic retaining ring for outer ring shaft, 11-centering sleeve, 12-first centering assembly, 15-rotating motor, 16-circumferential encoder, 17-fixed support, 19-roller frame assembly, 21-detection trolley, 22-detection water tank, 23-second centering assembly, 24-rotating shaft, 25-sleeve, 26-support guide rail, 27-movable support, 28-first nut, 31-second nut, 32-bidirectional screw, 34 -roller motor, 35-roller spacing adjustment device, 38-first probe bracket, 39-first phased array probe, 40-probe mounting plate, 41-longitudinal servo motor, 42-middle lifting plate, 43-lifting nut, 44-guide rod, 46-trolley guide rail, 47-curved acoustic lens, 48-guide shaft, 49-spring, 50-lifting screw, 52-translation base plate, 53-axial encoder, 54-trolley motor, 55-gear, 56-rack, 60-second phased array probe, 62-second probe bracket, 191-first wheel frame, 192-second wheel frame.

DETAILED DESCRIPTION

In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below through the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

In the description of the present invention, it should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or indirectly connected to the other element.

In the description of the present invention, it should be noted that the terms "center", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the invention product is usually placed when in use, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions, and cannot be understood as indicating or implying relative importance. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. "Several" means one or more, unless otherwise clearly and specifically defined.

In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Embodiment 1:

Referring to Figures 1 to 6, the present invention provides an automatic detection device for the plastic liner of a gas cylinder, including a plastic liner fixing mechanism, a rotating motor 15 used to cooperate with the plastic liner fixing mechanism to drive the plastic liner fixed on the plastic liner fixing mechanism to rotate around its axis, the plastic liner fixing mechanism includes a first centering component 12 adapted to the end cap of the plastic liner and a second centering component 23 adapted to the end cap of the other end of the plastic liner, the first centering component 12 and the second centering component 23 are respectively arranged on a fixed support 17 and a movable support 27, wherein the movable support 27 is provided with an electric push rod 5 for driving the second centering component 23 to move toward or away from the first centering component 12; the second centering component 23 is driven forward and backward by the electric push rod 5 to cooperate with the plastic liner, and the plastic liner is clamped and fixed between the first centering component 12 and the second centering component 23.

Referring to Figure 1, it also includes a detection water tank 22 that cooperates with the plastic liner fixing mechanism. The plastic liner fixing mechanism fixes the plastic liner on the upper side of the detection water tank 22. The liquid level inside the water tank 22 immerses the plastic liner at a certain position. The detection water tank 22 is provided with a cylinder detection device arranged toward the cylinder section of the plastic liner and two head section detection devices respectively arranged toward the head section of the plastic liner. The lower ends of the cylinder detection device and the head section detection device are both provided with a moving mechanism for driving them to move axially along the plastic liner; the cylinder detection device includes a first phased array probe 39 arranged toward the cylinder section of the plastic liner, and the first phased array probe 39 is consistent with the axial position of the plastic liner during detection, and the head section detection device includes a second phased array probe arranged toward the head of the plastic liner. 60, the second phased array probe 60 is arc-shaped and adapted to the plastic liner head, and also includes a rotation angle acquisition mechanism for cooperating with the rotation drive mechanism to monitor the rotation angle of the plastic liner, and an axial position acquisition mechanism for cooperating with the lower moving mechanism of the cylinder detection device to monitor the position of the moving mechanism, and also includes a control system, the control system is connected to the first phased array probe 39, the second phased array probe 60, the rotation angle acquisition mechanism, and the axial position acquisition mechanism for data communication, the control system obtains the ultrasonic monitoring information data of the first phased array probe 39 and the second phased array probe 60 and combines the position data of the rotation angle acquisition mechanism and the axial position acquisition mechanism, and associates the data to reconstruct the three-dimensional data of the entire plastic liner. In this embodiment, a first phased array probe 39 is set to scan the cylindrical barrel position in the middle section of the plastic liner, and a second phased array probe 60 is set, and the second phased array probe 60 is set to an arc shape suitable for the plastic liner head, which can be used to scan the head section of the plastic liner head. The first phased array probe 39 and the second phased array probe 60 can be combined to scan the entire plastic liner. Moving mechanisms are set to drive the moving mechanisms to move along the axial direction of the plastic liner, and cooperate with the rotating drive mechanism to realize full circumferential scanning of the plastic liner and reconstruct the three-dimensional data of the entire plastic liner. The scanning process is fully automatic, with a high degree of automation, high precision, and low labor intensity, which is convenient for detecting the plastic liner.

Preferably, the first centering component 12 is a three-jaw pneumatic chuck for directly clamping the end cap of the plastic liner.

Referring to FIG1 , the second centering assembly 23 includes an elastic retaining ring 7 for the inner shaft, a shaft sleeve 8, a bearing 9, an elastic retaining ring 10 for the outer shaft, a centering sleeve 11, a rotating shaft 24, and a sleeve 25; the centering sleeve 11 is fixedly connected to the rotating shaft 24, and the inner hole of the centering sleeve 11 is a bell mouth to connect to the bottle mouth position of one side of the plastic liner. One end of the sleeve 25 is fixedly connected to the electric push rod 5, and one end of the centering sleeve 11 is rotatably connected to the sleeve 25 through the rotating shaft 24 and the bearing 9, so as to facilitate the rotation of the plastic liner during the inspection process. The centering sleeve 11 is convenient to cooperate with the bottle mouth of the plastic liner to achieve the fixing and positioning function.

Referring to Fig. 1, a support rail 26 is provided at the lower side of the movable support 27, and the support can be slidably arranged on the support rail 26; a slide 2 and a secondary adjustment support 4 arranged on the slide of the slide 2 are also provided on the movable support 27, and the second centering component 23 is arranged on the secondary adjustment support 4, and a handle 1 connected to the control of the slide 2 is provided at one end of the slide 2. The spacing between the first centering component 12 and the second centering component 23 can be adjusted according to the different sizes of the plastic liner, the slide 2 is used for fine adjustment, and the support rail 26 is used for coarse adjustment. When the length of the inner liner to be detected does not change much, the position of the second centering component 23 can be adjusted by controlling the slide 2 through the handle 1; when the length of the inner liner to be detected changes greatly, the movable support 27 can be moved along the rail 26 to achieve position adjustment.

Referring to Figures 2 and 3, two groups of roller frame assemblies 19 for supporting the plastic liner are provided in the detection water tank 22, and the roller frame assembly 19 includes a first wheel frame 191 and a second wheel frame 192 which are arranged opposite to each other. The tops of the first wheel frame 191 and the second wheel frame 192 are both provided with wheels for cooperating with the plastic liner. A roller spacing adjustment device 35 is provided between the first wheel frame 191 and the second wheel frame 192. The roller spacing adjustment device 35 includes a bidirectional screw rod 32 which is transversely arranged between the first wheel frame 191 and the second wheel frame 192, and a roller motor 34 for driving the bidirectional screw rod 32 to rotate. The threads of the bidirectional screw rod 32 are opposite from the center to the two ends. The first wheel frame 191 and the second wheel frame 192 are respectively connected to the threads of the two ends of the bidirectional screw rod 32 through the first nut 28 and the second nut 31. When the roller motor 34 drives the bidirectional screw rod 32 to rotate, it can drive the first nut 28 and the second nut 31 at both ends of the bidirectional screw rod 32 to move closer to or away from each other, thereby adjusting the distance between the first wheel frame 191 and the second wheel frame 192 to meet various usage requirements and adapt to plastic liners of various sizes.

Referring to FIGS. 4, 5 and 6, the mobile mechanism includes a detection trolley 21, a trolley guide rail 46 is provided in the detection water tank 22, the detection trolley 21 is slidably arranged on the trolley guide rail 46, the detection trolley 21 is provided with a first probe bracket 38 corresponding to the first phased array probe 39 or a second probe bracket 62 corresponding to the second phased array probe 60, a plurality of vertically arranged guide rods 44 are provided on the detection trolley 21, and an intermediate lifting plate 42 is horizontally provided between the guide rods 44, and the intermediate lifting plate 42 can be axially The first probe bracket 38 and the second probe bracket 62 are arranged on the intermediate lifting plate 42, and the detection trolley 21 includes a translation bottom plate 52 arranged on the lower side of the intermediate lifting plate 42. A lifting mechanism is arranged between the translation bottom plate 52 and the intermediate lifting plate 42. The lifting mechanism includes a lifting screw 50 and a lifting nut 43 respectively arranged on the translation bottom plate 52 and the intermediate lifting plate 42. One end of the lifting screw 50 is provided with a longitudinal servo motor 41 for driving the rotation thereof. When the longitudinal servo motor 41 drives the lifting screw 50 to rotate, it can cooperate with the lifting nut 43, thereby driving the intermediate lifting plate 42 to rise or fall, adjusting the height of the intermediate lifting plate 42 and the phased array probe on its upper end, adapting to various scanning and detection requirements, and adapting to various sizes of plastic liners.

Referring to FIG. 4 , during the inspection, the first phased array probe 39 automatically inspects the cylinder section along the axial direction of the plastic liner. The first phased array probe 39 is provided with a rack 56 arranged along the length direction of the trolley guide rail 46 of the inspection trolley 21. The inspection trolley 21 is provided with a gear 55 meshing with the rack 56 and a trolley motor 54 for driving the gear 55 to rotate. The trolley motor 54 drives the gear 55 to rotate, thereby driving the inspection trolley 21 to reciprocate along the trolley guide rail 46, adjusting the position of the inspection trolley 21 and the phased array probe on the upper side, and scanning various positions of the plastic liner.

Referring to FIG. 4 , in order to collect the position information of the first phased array probe 39 , an axial position collection mechanism is provided on the lower movable part of the first phased array probe 39 . The axial position collection mechanism is an axial encoder 53 . The trolley motor 54 is provided with an axial encoder 53 synchronously connected to its rotating shaft. The axial position information of the detection trolley 21 is recorded by the axial encoder 53 and output to the computer.

6 , the second phased array probe 60 cooperates with the end cap of the plastic liner for detection. A fixing device is provided on the lower side of the detection trolley 21 of the second phased array probe 60 , and the second probe bracket 62 of the detection trolley 21 is an arc-shaped structure consistent with the end cap of the plastic liner.

Referring to Fig. 4 and Fig. 5, a probe mounting plate 40 is further provided on the upper side of the intermediate lifting plate 42, the probe bracket 38 is fixedly provided on the probe mounting plate 40, the probe mounting plate 40 is axially slidably provided on the guide rod 44, and a plurality of vertically arranged elastic support members are provided between the probe mounting plate 40 and the intermediate lifting plate 42, the elastic support members comprising a vertically arranged guide shaft 48 and a spring 49 sleeved on the guide shaft 48. The intermediate lifting plate 42 and the probe mounting plate 40 are supported by the spring 49, providing a certain buffer between the intermediate lifting plate 42 and the probe mounting plate 40, avoiding hard collision with the phased array probe to cause damage to the phased array probe, and improving the service life of the phased array probe.

1 , the rotation angle acquisition mechanism is a circumferential encoder 16. A circumferential encoder 16 is provided on a fixed support 17 and is synchronously connected to the rotation shaft of a rotating motor 15. The circumferential encoder 16 records the rotation position of the plastic liner.

4 and 5 , a curved acoustic lens 47 bonded to the surface of the first phased array probe 39 is provided.

Preferably, the first phased array probe 39 is a probe group with 512 elements arranged linearly, consisting of 4 128-element probes. The first phased array probe 39 can achieve bidirectional focusing, with electronic line scanning focusing in the array direction and side focusing through the curved acoustic lens 47 in the element width direction; the electronic line scanning of the first phased array probe 39 sets multiple starting elements to start scanning at the same time to reduce scanning time and improve detection efficiency.

Embodiment 2:

Referring to Figures 7, 8 and 9, based on the first embodiment, this embodiment proposes a three-dimensional reconstruction algorithm for the above embodiment, including the following steps: Step 1: Three-dimensional reconstruction of the plastic liner cylinder segment, establishing an image coordinate system {A}, the center coordinates of the first group of excitation apertures of the first phased array probe 39 are the origin of the image coordinate system {A} , the array arrangement direction is taken as the x-axis of the image coordinate system {A}, and the depth direction is taken as the z-axis of the image coordinate system {A}. Then the position of a point P in the image after imaging in {A} is expressed as ;

Step 2: Establish the rotating coordinate system {B} of the plastic liner, and set the position of the mouth of the plastic liner as the origin of the rotating coordinate system {B} , and the central axis of the plastic liner is the x-axis of the coordinate system {B}, and the cross section of the plastic liner cylinder is the yz plane. Since the axes of the rotating coordinate system {B} are parallel to the axes of the coordinate system {A}, the origin of the image coordinate system {A} The coordinates in the rotating coordinate system {B} can be expressed by the translation vector Indicates; during the first inspection, the first phased array probe 39 is moved to the position just above the central axis of the plastic liner. =0, The horizontal position of the first phased array probe 39 is obtained according to the feedback of the axial encoder 53. The vertical distance difference between the first centering component 12 and the surface of the first phased array probe 39 is measured; then the position of any point P in the image in the coordinate system {B} ;

Step 3: Rotate and scan the image to obtain the coordinate transformation The position of any point P in the rotated image in the coordinate system {B} is , Rotate the image to Axis rotation angle, is the angle between two adjacent ultrasound images. This rotation angle is opposite to the rotation angle of the plastic liner. In this embodiment, the scanned image rotates counterclockwise, and the coordinate transformation matrix R is ;

Step 4: Three-dimensional reconstruction of the plastic liner head section, establish the coordinate system {A'} of the ultrasonic detection image, the center coordinates of the first group of excitation apertures of the second phased array probe 60 are taken as the origin O, the array arrangement direction is taken as the x-axis, and the depth direction is taken as the z-axis. The position of a point P' in {A'} can be expressed as ;

Step 5: Establish the auxiliary coordinate system {B'}, and the center of the plastic liner's head sphere is used as the origin of the auxiliary coordinate system {B'} , the central axis of the plastic liner is used as the x-axis of the auxiliary coordinate system {B'}, and the z-axis of the auxiliary coordinate system {B'} is parallel to the coordinate system {A'};

The relationship between the auxiliary coordinate system {B'} and the origin of the coordinate system {A'} is expressed by the translation vector Indicates that the position of point P' in the auxiliary coordinate system {B'} in , , is the position of the second phased array probe (60) in the auxiliary coordinate system {B'}, r is the radius of the spherical head, h is the distance between the second phased array probe (60) and the water layer on the outer surface of the head, The angle between the line connecting the origins of the probe coordinate system {A'} and {B'} and the x-axis of the auxiliary coordinate system {B'};

Step 6: Convert each coordinate in the auxiliary coordinate system {B'} into the rotating coordinate system {B} used by the cylinder section, and the translation vector of the head on the same side , the translation vector of the side head ,by The rotation angle about the axis is , Point P' on the rotated image is in the rotated coordinate system {B} , where l is the axial length of the barrel section;

Step 7: Integrate the model, match the ultrasonic test results with the actual cylinder test parts, and obtain a 3D reconstruction model of the entire plastic liner. The 3D reconstruction algorithm in this embodiment can be coordinated with the device structure of the first embodiment, and a 3D model of the plastic liner is established in the computer by acquiring various data. The 3D reconstruction process is fully automatic, with a high degree of automation, and the data of the 3D model is more accurate, which is convenient for subsequent analysis.

Embodiment three:

Referring to FIG. 10, FIG. 11, and FIG. 12, based on the second embodiment, this embodiment proposes an analysis method for the above embodiment, comprising the following steps: Step S1, outer surface inspection, the outer surface inspection is carried out by rotating the coordinate system {B} Axis and The n value of the rotation angle is used as the position description, Decomposed into mp, which represents the mth group of excitation apertures, and p is the array element spacing of the phased array probe; under the nth rotating image and the mth group of excitation apertures, the outer radius of the plastic liner is in, The thickness of the water layer is obtained by calculating the echo time of the interface between water and the plastic liner in the A-scan signal of the phased array ultrasonic detection data;

Drive the plastic liner to rotate until it rotates 180°, and the detection process ensures the detection position of the phased array probe unchanged; and collect and record the position detection data, the outer diameter of the plastic liner is Where N is the number of images detected when the plastic liner rotates one circle;

At a certain axial position m, the average outer diameter of the entire circumference of the plastic liner is ; At a certain circumferential position n, the average outer diameter of the entire axial direction of the plastic liner is ;

M is the number of excitation apertures distributed along the length of the cylinder, ; is the starting excitation aperture number of the first phased array probe 39, is the ending excitation aperture number of the first phased array probe 39; the excitation aperture numbers at the starting and ending ends are the connection positions of the plastic liner barrel section and the head section, which are obtained by comparing whether the average outer diameter of each axial position on the boundary increases continuously; the length of the plastic liner barrel is ;

At a certain axial position m, the maximum circumferential outer wall radius is , the minimum outer wall radius is , the roundness of the cross section at this axial position is ;

At each axial position of the plastic liner cylinder section, the maximum outer wall radius is , the minimum outer wall radius is The cylindricality of the plastic liner section is ;

At a certain circumferential position n, the maximum axial outer wall radius is , the minimum outer wall radius is , the straightness of the plastic liner cylinder section is ;

Under the nth rotating image and mth set of excitation apertures, the wall thickness of the plastic liner is in, It is obtained by calculating the echo time of the inner wall of the plastic liner in the A-scan signal of the phased array ultrasonic detection data and the sound speed in water. is the speed of sound in water, is the speed of sound in the plastic liner; exist Position uses color scale to draw thickness cloud map, if it exists Draw the location with a special color, It is the standard thickness of plastic liner;

Step S2, internal defect analysis, when there are other reflection signals on the outer wall and inner wall of the plastic liner in the phased array ultrasonic detection data, defect analysis and statistics are performed; in the rotating coordinate system {B}, the defect position is expressed as Among them, x, x', y, y', z, z' are the three-dimensional boundaries of the defect in the coordinate system {B}, which are obtained by combining the adjacent phased array ultrasonic testing data; the defect size is expressed as By counting the number, size and distribution of defects in a list, preparation is made for subsequent defect assessment. The analysis method of this embodiment can be combined with the three-dimensional reconstruction model constructed in Example 2 to analyze the three-dimensional reconstruction model, thereby summarizing the number, size and distribution of defects in the plastic liner, making the analysis more convenient, the analysis process fully automatic, more intelligent, more efficient and more accurate.

Working process of the present invention:

During the working process of the present invention, the plastic liner is placed on the roller frame assembly 19 before the detection begins, and the first centering assembly 12 and the second centering assembly 23 fix the plastic liner; the detection trolley 21 on the lower side of the first phased array probe 39 moves to one end of the plastic liner cylinder, and the position of the first phased array probe 39 is adjusted according to the diameter of the plastic liner, so that the curved acoustic lens 47 fits the plastic liner; the detection trolley 21 on the lower side of the second phased array probe 60 moves to just below the ends on both sides of the plastic liner, and the position of the second phased array probe 60 is adjusted so that the arc-shaped water wedge block 63 fits the ends on both sides of the plastic liner; water is poured into the detection water tank 22, and the first phased array probe 39 and the second phased array probe 60 are water-coupled; the rotating motor 15 is turned on to drive the plastic liner to rotate, and the plastic liner is rotated. The plastic liner is rotated at equal angles at intervals. After the first phased array probe 39 and the second phased array probe 60 complete scanning at any position of the plastic liner, the plastic liner is rotated again. Angle, thereby realizing circumferential scanning; turning on the trolley motor, the detection trolley 21 moves at equal intervals of δ, and after the first phased array probe 39 completes scanning at any plastic liner position, the detection trolley 21 moves axially by a spacing of δ, thereby realizing axial scanning of the detection trolley 21; the computer records and organizes the ultrasonic detection information of the ultrasonic phased array detector and the position data of the axial encoder 53 and the circumferential encoder 16, reconstructs the three-dimensional results, and analyzes and evaluates the outer diameter, cylinder length, roundness, straightness, wall thickness, internal defects and other information of the plastic liner.

The standard parts used in this application document can all be purchased from the market, and the specific connection methods of each part adopt mature conventional means such as bolts, rivets, welding, etc. in the prior art. The electric slide rail slide, cylinder, welding machine, electric telescopic rod and internal components of the controller all adopt conventional models in the prior art, and their internal structures belong to the prior art structure. Workers can complete normal operation of them according to the existing technical manual. In addition, the circuit connection adopts the conventional connection method in the prior art, and no specific description is given here.

It should be noted that, although the above embodiments have been described in this article, the scope of patent protection of the present invention is not limited thereby. Therefore, based on the innovative concept of the present invention, changes and modifications made to the embodiments described herein, or equivalent structures or equivalent process changes made using the contents of the present specification and drawings, directly or indirectly applying the above technical solutions to other related technical fields are all included in the scope of protection of the patent of the present invention.

Claims (10)

1. An automatic detection device for a plastic liner of a gas cylinder, comprising a plastic liner fixing mechanism, characterized in that: a rotation drive mechanism is provided for cooperating with the plastic liner fixing mechanism to drive the plastic liner fixed on the plastic liner fixing mechanism to rotate around its axis, and a detection water tank (22) is provided for cooperating with the plastic liner fixing mechanism, the plastic liner fixing mechanism fixes the plastic liner on the upper side of the detection water tank (22), a cylinder detection device arranged toward the cylinder section of the plastic liner and two end section detection devices arranged toward the end section of the plastic liner respectively, and a moving mechanism is provided at the lower end of each of the cylinder detection device and the end section detection device for moving them along the axial direction of the plastic liner; The cylinder detection device comprises a first phased array probe (39) arranged toward the plastic liner cylinder section, and the end section detection device comprises a second phased array probe (60) arranged toward the plastic liner end, the second phased array probe (60) being arc-shaped and adapted to the plastic liner end; It also includes a rotation angle acquisition mechanism for cooperating with the rotation drive mechanism to monitor the rotation angle of the plastic liner, and an axial position acquisition mechanism for cooperating with the lower moving mechanism of the cylinder detection device to monitor the position of the moving mechanism, and also includes a control system, the control system is connected to the first phased array probe (39), the second phased array probe (60), the rotation angle acquisition mechanism, and the axial position acquisition mechanism for data communication, the control system obtains the ultrasonic monitoring information data of the first phased array probe (39) and the second phased array probe (60) and combines the position data of the rotation angle acquisition mechanism and the axial position acquisition mechanism, and associates the data to reconstruct the three-dimensional data of the entire plastic liner. 2. An automatic detection device for a plastic liner of a gas cylinder according to claim 1, characterized in that: the plastic liner fixing mechanism comprises a first centering component (12) adapted to a head at one end of the plastic liner and a second centering component (23) adapted to a head at the other end of the plastic liner, the first centering component (12) and the second centering component (23) being respectively arranged on a fixed support (17) and a movable support (27), the movable support (27) being provided with a moving component for controlling the support and/or the centering component arranged on the support to move closer to or away from the plastic liner, and the rotation drive mechanism being a rotating motor (15) arranged on the fixed support (17) for driving the first centering component (12) to rotate around its axis. 3. An automatic detection device for the plastic liner of a gas cylinder according to claim 2, characterized in that: the moving component comprises an electric push rod (5), the electric push rod (5) is arranged on the moving support (27) and is used to drive the second centering component (23) to move closer to or away from the plastic liner. 4. An automatic detection device for the plastic liner of a gas cylinder as described in claim 2, characterized in that: the moving component also includes a support rail (26) arranged on the lower side of the moving support (27), and the moving support (27) is slidably arranged on the support rail (26); the moving support (27) is also provided with a slide seat (2) and an auxiliary adjustment support (4) arranged on the slide seat (2), the first centering component (12) or the second centering component (23) is arranged on the auxiliary adjustment support (4), and one end of the slide seat (2) is provided with a handle (1) connected to the slide seat (2) for control. 5. An automatic detection device for a plastic liner of a gas cylinder according to claim 1, characterized in that: a roller frame assembly (19) for supporting the plastic liner is provided in the detection water tank (22), the roller frame assembly (19) comprising a first wheel frame (191) and a second wheel frame (192) arranged opposite to each other, the first wheel frame (191) and the second wheel frame (192) are provided with wheels for cooperating with the plastic liner at the top, a roller spacing adjustment device (35) is provided between the first wheel frame (191) and the second wheel frame (192), the roller spacing adjustment device (35) comprises a bidirectional screw rod (32) transversely arranged between the first wheel frame (191) and the second wheel frame (192), and a roller motor (34) for driving the bidirectional screw rod (32) to rotate, the bidirectional screw rod (32) has opposite threads from the center to the two ends, and the first wheel frame (191) and the second wheel frame (192) are respectively connected to the two ends of the bidirectional screw rod (32) by threads through a first nut (28) and a second nut (31). 6. An automatic detection device for the plastic liner of a gas cylinder according to claim 1, characterized in that: the moving mechanism comprises a detection trolley (21), a trolley guide rail (46) is provided in the detection water tank (22), the detection trolley (21) is slidably arranged on the trolley guide rail (46), the detection trolley (21) is provided with a first probe bracket (38) corresponding to the first phased array probe (39) or a second probe bracket (62) corresponding to the second phased array probe (60), the detection trolley (21) is provided with a plurality of vertically arranged guide rods (44), an intermediate lifting plate (42) is horizontally arranged between the guide rods (44), and the The intermediate lifting plate (42) is axially slidably arranged on the guide rod (44), the first probe bracket (38) or the second probe bracket (62) is arranged on the intermediate lifting plate (42), the detection trolley (21) includes a translation base plate (52) arranged on the lower side of the intermediate lifting plate (42), a lifting mechanism is arranged between the translation base plate (52) and the intermediate lifting plate (42), the lifting mechanism includes a lifting screw (50) and a lifting nut (43) respectively arranged on the translation base plate (52) and the intermediate lifting plate (42), and one end of the lifting screw (50) is provided with a longitudinal servo motor (41) for driving the lifting screw (50) to rotate. 7. An automatic detection device for the plastic liner of a gas cylinder as described in claim 6, characterized in that: a probe mounting plate (40) is also provided on the upper side of the intermediate lifting plate (42), the first probe bracket (38) or the second probe bracket (62) is fixedly arranged on the probe mounting plate (40), the probe mounting plate (40) is axially slidable on the guide rod (44), and a plurality of vertically arranged elastic support members are provided between the probe mounting plate (40) and the intermediate lifting plate (42). 8. An automatic detection device for the plastic liner of a gas cylinder as claimed in claim 6, characterized in that: a rack (56) is arranged along its length direction on the trolley guide rail (46) of the lower moving mechanism of the cylinder detection device, a gear (55) meshing with the rack (56) and a trolley motor (54) for driving the gear (55) to rotate are arranged on the corresponding detection trolley (21), the axial position acquisition mechanism is an axial encoder (53), and the trolley motor (54) is provided with an axial encoder (53) synchronously connected to its rotating shaft. 9. A three-dimensional reconstruction algorithm for the automatic detection device of the plastic liner of a gas cylinder according to any one of claims 1 to 8, characterized in that it comprises the following steps: Step 1: Three-dimensional reconstruction of the plastic liner cylinder segment, establishing an image coordinate system {A}, the center coordinates of the first group of excitation apertures of the first phased array probe (39) are the origin of the image coordinate system {A} , the array arrangement direction is taken as the x-axis of the image coordinate system {A}, and the depth direction is taken as the z-axis of the image coordinate system {A}. Then the position of a point P in the image after imaging in {A} is expressed as ; Step 2: Establish the rotating coordinate system {B} of the plastic liner, and set the position of the mouth of the plastic liner as the origin of the rotating coordinate system {B} , and the central axis of the plastic liner is the x-axis of the coordinate system {B}, and the cross section of the plastic liner cylinder is the yz plane. Since the axes of the rotating coordinate system {B} are parallel to the axes of the coordinate system {A}, the origin of the image coordinate system {A} The coordinates in the rotating coordinate system {B} can be expressed by the translation vector express; During the first inspection, the first phased array probe (39) is moved to the position directly above the central axis of the plastic liner. =0, According to the position data of the first phased array probe (39) collected by the axial position collection mechanism, The vertical distance difference between the first centering component (12) and the surface of the first phased array probe (39) is measured; then the position of any point P in the image in the coordinate system {B} ; Step 3: Rotate and scan the image to obtain the coordinate transformation The position of any point P in the rotated image in the coordinate system {B} is , Rotate the image to Axis rotation angle, is the angle between two adjacent ultrasonic images, and the rotation angle is opposite to the rotation angle of the plastic liner; Step 4: Three-dimensional reconstruction of the plastic liner head section, establishing the coordinate system {A'} of the ultrasonic detection image, and the center coordinates of the first group of excitation apertures of the second phased array probe (60) are used as the origin , the array arrangement direction is taken as the x-axis, the depth direction is taken as the z-axis, and the position of a point P' in {A'} can be expressed as ; Step 5: Establish the auxiliary coordinate system {B'}, and the center of the plastic liner's head sphere is used as the origin of the auxiliary coordinate system {B'} , the central axis of the plastic liner is used as the x-axis of the auxiliary coordinate system {B'}, and the z-axis of the auxiliary coordinate system {B'} is parallel to the coordinate system {A'}; The relationship between the auxiliary coordinate system {B'} and the origin of the coordinate system {A'} is expressed by the translation vector Indicates that the position of point P' in the auxiliary coordinate system {B'} in , , is the position of the second phased array probe (60) in the auxiliary coordinate system {B'}, r is the radius of the spherical head, h is the distance between the second phased array probe (60) and the water layer on the outer surface of the head, The angle between the line connecting the origins of the probe coordinate system {A'} and {B'} and the x-axis of the auxiliary coordinate system {B'}; Step 6: The coordinates in the auxiliary coordinate system {B'} are converted into the rotating coordinate system {B} used by the cylinder section, and the translation vector of the head on the same side , the translation vector of the side head ,by The rotation angle about the axis is , Point P' on the rotated image is in the rotated coordinate system {B} , where l is the axial length of the barrel section; Step 7: Integrate the model, match the ultrasonic test results with the actual cylinder test parts, and obtain a three-dimensional reconstructed model of the entire plastic liner. 10. An analysis method for automatic detection of the plastic liner of a gas cylinder as claimed in claim 9, characterized in that it comprises the following steps: Step S1, external surface inspection, the external surface inspection is carried out with a rotating coordinate system {B} Axis and The n value of the rotation angle is used as the position description, Decomposed into m and p, representing the mth group of excitation apertures, p is the array element spacing of the phased array probe; under the nth rotating image and the mth group of excitation apertures, the outer radius of the plastic liner is in, The thickness of the water layer is obtained by calculating the echo time of the interface between water and the plastic liner in the A-scan signal of the phased array ultrasonic detection data; Drive the plastic liner to rotate 180°, and the detection process ensures the detection position of the phased array probe unchanged; and collect and record the position detection data, the outer diameter of the plastic liner is Where N is the number of images detected when the plastic liner rotates one circle; At a certain axial position m, the average outer diameter of the entire circumference of the plastic liner is ; At a certain circumferential position n, the average outer diameter of the entire axial direction of the plastic liner is ; M is the number of excitation apertures distributed along the length of the cylinder, ; is the starting excitation aperture number of the first phased array probe (39), is the ending excitation aperture serial number of the first phased array probe (39); the excitation aperture serial numbers of the starting end and the ending end are the connection positions of the plastic liner barrel section and the head section, and are obtained by comparing whether the average outer diameter of each axial position on the boundary increases continuously; the length of the plastic liner barrel is ; At a certain axial position m, the maximum circumferential outer wall radius is , the minimum outer wall radius is , the roundness of the cross section at this axial position is ; At each axial position of the plastic liner cylinder section, the maximum outer wall radius is , the minimum outer wall radius is The cylindricality of the plastic liner section is ; At a certain circumferential position n, the maximum axial outer wall radius is , the minimum outer wall radius is , the straightness of the plastic liner cylinder section is ; Under the nth rotating image and mth set of excitation apertures, the wall thickness of the plastic liner is in, It is obtained by calculating the echo time of the inner wall of the plastic liner in the A-scan signal of the phased array ultrasonic detection data and the sound speed in water. is the speed of sound in water, is the speed of sound in the plastic liner; exist Position uses color scale to draw thickness cloud map, if it exists Draw the location with a special color, It is the standard thickness of plastic liner; Step S2, internal defect analysis, when there are other reflection signals on the outer wall and inner wall of the plastic liner in the phased array ultrasonic detection data, defect analysis and statistics are performed; in the rotating coordinate system {B}, the defect position is expressed as Among them, x, x', y, y', z, z' are the three-dimensional boundaries of the defect in the coordinate system {B}, which are obtained by combining the adjacent phased array ultrasonic testing data; the defect size is expressed as The number, size and distribution of defects are counted by tabulation to prepare for subsequent defect assessment.