Ultrasonic phased array detection probe and detection method for defects of inner wall of metal pipe

Abstract

The invention relates to the technical field of ultrasonic phased array nondestructive testing, and discloses a metal pipe inner wall defect ultrasonic phased array detection probe and a metal pipe inner wall defect ultrasonic phased array detection method, the probe comprises an array transducer and a wedge block, the array transducer is connected with the wedge block through a connector, and the curvature radius of the end face of the bottom of the wedge block is the same as that of a metal pipe. The curvature of the end part of the probe provided by the invention is the same as that of the outer diameter of the pipe, so that good acoustic coupling can be realized, an oblique incidence sound beam forming a certain angle with the radial direction of a detected object can be formed, and ultrasonic waves can obliquely enter the side surface of a defect; the full-focus algorithm is adopted for imaging in the axial direction of the pipe, the detection sensitivity of inner wall shallow surface defects can be effectively improved, and the detection efficiency and reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic phased array nondestructive testing, and more particularly to an ultrasonic phased array detection probe and detection method device for defects in the inner wall of metal pipes. Background Technology

[0002] Ultrasonic testing of the inner wall of metal pipes requires placing the probe on the outer wall, which presents challenges such as coupling difficulties, large wall thickness, and low sensitivity. Traditional ultrasonic testing generally uses the modified transverse wave oblique incidence method, employing a water immersion focusing probe incident on the outer wall of the pipe at an angle less than the first critical angle. The excited longitudinal wave undergoes waveform conversion at the water / steel interface, forming refracted longitudinal waves and refracted transverse waves. The refracted transverse waves cannot propagate to the inner wall of the pipe, while the refracted longitudinal waves undergo another waveform conversion upon incident on the outer wall. The resulting reflected transverse waves are then used to detect the inner wall. Existing methods produce complex detection signals and are prone to misinterpretation. Summary of the Invention

[0003] To address the limitations of existing ultrasonic testing techniques in detecting shallow surface defects on the inner walls of metal pipes, including difficulties in coupling due to curved surfaces, significant sound energy attenuation due to thick walls, and insufficient sensitivity for shallow surface defects, this invention aims to provide an ultrasonic phased array probe and method for detecting inner surface defects in metal pipes. The probe's end has the same curvature as the outer diameter of the pipe, and the two are coupled via an oil film, achieving good acoustic coupling. Furthermore, it can form an obliquely incident sound beam at a certain angle to the radial direction, incident obliquely onto the side of the defect. By employing a full-focusing algorithm to image along the pipe's axial direction, the detection sensitivity, efficiency, and reliability of shallow surface defects on the inner wall can be effectively improved, which has significant engineering implications for increasing the detection rate of shallow surface defects on the inner walls of metal pipes.

[0004] This invention provides the following technical solution:

[0005] An ultrasonic phased array detection probe for defects in the inner wall of a metal pipe includes an array transducer, a connector, and a wedge. The bottom surface of the array transducer is coupled to the top surface of the wedge through an oil film. The connector includes a first connector and a second connector. The first connector and the second connector are clamped on both sides of the coupled array transducer and the wedge and are fixed by fasteners. The bottom end face of the wedge has the same radius of curvature as the outer wall of the metal pipe being inspected.

[0006] According to some possible implementations, the top end face of the wedge is a plane with the same size as the transmitting and receiving surface of the array transducer, the bottom surface of the wedge is a curved surface, the angle between the plane normal of the wedge and the center normal of the curved surface of the wedge is θ1, and the center thickness of the curved surface is less than 3 mm.

[0007] According to some possible implementations, the center frequency of the array transducer is 7.5 MHz to 12.5 MHz, and the number of array elements is at least 64.

[0008] On the other hand, the present invention also provides a detection method for the ultrasonic phased array detection probe for defects in the inner wall of the above-mentioned metal pipe, which includes the following steps:

[0009] S1. Based on the radius of curvature of the outer wall of the object being tested, a customized wedge with a radius of curvature is installed at the front end of the array transducer. The wedge is connected to the array transducer via the connector. The wedge is in contact with the outer wall of the metal pipe to be tested. Each element of the array transducer emits ultrasonic waves obliquely incident on the inner wall defect along the wafer length direction. The formula for calculating the angle θ1 between the normal of the wedge plane and the normal of the center of the wedge surface is:

[0010] (1)

[0011] In the formula: C1 is the sound velocity of the plexiglass wedge; C2 is the sound velocity of the metal pipe; T is the wall thickness of the metal pipe; d is the pulse width;

[0012] S2. The ultrasonic phased array detection probe for defects in the inner wall of the metal pipe is installed on the outer wall of the pipe. The array elements of the array transducer are arranged along the axial direction, and the wedge is coupled to the outer wall of the metal pipe through an oil film.

[0013] S3. The individual array elements of the array transducer are excited sequentially, and the reflected echoes are received by all array elements. The signal is saved as a three-dimensional full matrix signal dataset containing the transmission and reception sequences. Full-focus imaging is performed based on the three-dimensional full matrix signal to obtain a full-focus detection image of the inner wall defect.

[0014] S4. In the fully focused detection image, if a reflection image with a signal-to-noise ratio higher than 5 is found at a depth greater than T, it can be determined as the corner reflection image of the defect.

[0015] S5. Move the ultrasonic phased array detection probe for defects in the inner wall of the metal pipe along the circumferential and axial directions until the defect display amplitude is at its highest, and the defect image is located at the center of the horizontal axis of the fully focused image.

[0016] S6. In the axial direction of the metal pipe, the defect is located directly below the center of the probe's electronic scanning direction; in the circumferential direction of the pipe, the normal to the center of the wedge surface extends downwards and intersects the inner wall at a point. The location of the defect is determined by moving an arc length l clockwise along the circumferential direction from that point, as shown in the following formula:

[0017] (2)

[0018] (3)

[0019] In the formula: R is the outer diameter of the metal pipe; T is the thickness of the metal pipe; θ2 is the angle between the normal of the center of the wedge surface and the normal of the inner wall defect; θ1 is the angle between the normal of the plane of the wedge and the normal of the center of the wedge surface; C1 is the sound velocity of the plexiglass wedge; C2 is the sound velocity of the metal pipe.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) High sensitivity and signal-to-noise ratio

[0022] A full-focusing algorithm is employed in the array arrangement direction to image the sound field data by amplitude after time-delay superposition. Compared to the sector and line scans of traditional phased arrays, full-focusing achieves focusing at each pixel, enabling the detection of even smaller defects. In the embodiment, the signal-to-noise ratio (SNR) of a groove with a depth of 0.1 mm, a length of 5 mm, and a width of 0.5 mm is 15.33; the SNR of a flat-bottomed hole with a depth of 0.3 mm and a diameter of 0.5 mm is 13.39, significantly improving the detection capability of minute defects.

[0023] 2) Less energy loss

[0024] The wedge is made of plexiglass with a center thickness of 2 mm and a radius of curvature identical to that of the object being inspected. The two are coupled via an oil film. Compared to water coupling, there is less energy loss in the first layer of medium and higher energy transmittance at the interface. The refracted longitudinal wave signal is extracted using the fully focused LL mode, which has stronger penetrating power and less energy attenuation due to the thick wall compared to refracted transverse waves.

[0025] 3) High detection efficiency

[0026] Once the probe is deployed, a 64 mm wide circumferential scan can be completed by moving it around the outer wall once, which can be used for in-service pipe inspection. This eliminates the costs of disassembly, transportation, and reassembly, avoids potential accidental damage during offline testing, and effectively improves testing efficiency.

[0027] 4) High resolution

[0028] Phased array probes can form obliquely incident sound beams at a certain angle to the radial direction, incident obliquely on the side of the defect, and extract the end-angle reflection signal as the characteristic signal of the defect. It can effectively distinguish the reflection signal of shallow inner wall defects from the inner wall reflection signal, significantly improving the resolution of shallow inner wall defects. Attached Figure Description

[0029] Figure 1 This is a probe assembly diagram provided for an embodiment of the present invention.

[0030] Figure 2 An exploded view of the probe provided in an embodiment of the present invention.

[0031] Figure 3The diagram shows the structural parameters of the wedge block from different perspectives, as provided in the embodiments of the present invention.

[0032] Figure 4 The diagram shows the structural parameters of the probe from different perspectives provided in the embodiments of the present invention.

[0033] Figure 5 The diagram shows the structural parameters of the first connector from different perspectives, as provided in the embodiments of the present invention.

[0034] Figure 6 The diagram shows the structural parameters of the second connector from different perspectives in the embodiments of the present invention.

[0035] Figure 7 These are structural diagrams of the test block provided in embodiments of the present invention from different perspectives.

[0036] Figure 8 Diagrams showing the arrangement of the probe from different perspectives in embodiments of the present invention.

[0037] Figure 9 A fully focused image of a groove with a depth of 0.1 mm, a length of 5 mm, and a width of 0.5 mm, provided for an embodiment of the present invention.

[0038] Figure 10 The A-scan signal image of a groove with a depth of 0.1 mm, a length of 5 mm, and a width of 0.5 mm is provided for an embodiment of the present invention.

[0039] Figure 11 The image shows a fully focused image of a flat-bottomed hole with a depth of 0.3 mm and a diameter of 0.5 mm, provided for an embodiment of the present invention.

[0040] Figure 12 The image shows the A-scan signal of a flat-bottomed hole with a depth of 0.3 mm and a diameter of 0.5 mm, provided for an embodiment of the present invention.

[0041] In the picture:

[0042] First connector 1; array transducer 2; second connector 3; wedge 4; screw 5; nut 6. Detailed Implementation

[0043] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0044] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "front," and "rear," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0045] The present invention will be further described below with reference to the accompanying drawings.

[0046] Example 1

[0047] like Figure 1 The ultrasonic phased array probe for defects in the inner wall of metal pipes in this embodiment, hereinafter referred to as the probe, includes an array transducer 2, a first connector 1, a second connector 3, a wedge 4, a screw 5, and a nut 6. The wedge 4 is made of plexiglass, with the array transducer 2 mounted on top and connected to it via the first and second connectors. The fasteners are φ6 mm screws 5 and nuts 6. The wedge 4 and array transducer 2 are coupled via an oil film. The bottom of the wedge 4 has the same radius of curvature as the metal pipe sample. The probe assembly diagram is shown below. Figure 1 As shown, the exploded view is as follows Figure 2 As shown.

[0048] In this embodiment, the center frequency of the array transducer 2 is between 7.5 MHz and 12.5 MHz, such as 10 MHz, with 64 array elements, an element length of 7 mm, and an element spacing of 1 mm. If a low frequency (such as 5 MHz) is used, the lower the frequency, the larger the pulse width, and the lower the resolution between the defect and the inner wall will be. If a high frequency (such as 15 MHz) is used, the higher the frequency, the greater the energy attenuation due to the thick wall, and the weaker the received defect reflection signal energy will be. The larger the number of array elements, the better the full-focus imaging resolution along the pipe axis. It can be greater than 64 array elements, and the number of array elements should be at least 64. The top end face of the wedge 4 has the same size as the transmitting and receiving surface of the array transducer 1. Its top is flat, and its bottom is curved. The angle between the normal of the plane of the wedge 4 and the normal of the center of the curved surface of the wedge 4 is θ1. The center thickness of the curved surface is less than 3 mm. The structural parameter diagram of the wedge 4, the array transducer 2, and the first and second connectors is shown in the figure. Figures 3-6 As shown, all dimensions in the figure are in mm. Figure 3 (a) is the front view of wedge block 4. Figure 3 (b) is the left view of wedge block 4. Figure 3 (c) is a top view of wedge block 4; Figure 4 (a) is a front view of array transducer 2. Figure 4 (b) is a left view of array transducer 2. Figure 4 (c) is a top view of array transducer 2; Figure 5 (a) is the front view of the first connector 3. Figure 5 (b) is a left view of the first connector component 3. Figure 5 (c) is a top view of the first connector 3; Figure 6 (a) is the front view of the second connector 1. Figure 6 (b) is the left view of the second connector 1. Figure 6 (c) is a top view of the second connector 1.

[0049] The detection method for defects in the inner wall of metal pipes using an ultrasonic phased array probe includes the following steps:

[0050] (1) Based on the outer wall curvature radius of the object being tested, wedges 4 with different curvature radii are installed at the front end of the array transducer. The wedges 4 are connected to the array transducer 2 through the first and second connectors. The bottom surface of the wedges 4 is in contact with the outer wall of the metal pipe to be tested. Each element of the array transducer 2 emits ultrasonic waves obliquely incident on the inner wall defect along the wafer length direction. Figure 8 The formula for calculating the angle θ1 between the plane normal of wedge 4 and the center normal of the curved surface of wedge 4 is:

[0051] (1)

[0052] In the formula: C1 is the sound velocity of the plexiglass wedge; C2 is the sound velocity of the metal pipe; T is the wall thickness of the metal pipe; d is the pulse width;

[0053] (2) The probe is installed on the outer wall of the pipe, the array elements of the array transducer 2 are arranged along the axial direction, and the bottom surface of the wedge 4 is coupled to the outer wall of the metal pipe through an oil film.

[0054] (3) The individual array elements of array transducer 2 are excited in sequence, and the reflected echoes are received by all array elements. The signal is saved as a three-dimensional full matrix signal dataset containing the transmission and reception sequences. Full-focus imaging is performed based on the three-dimensional full matrix signal to obtain a full-focus detection image of the inner wall defect.

[0055] (4) In the fully focused detection image, if a reflection image with a signal-to-noise ratio higher than 3 is found at a depth T, it can be determined as the corner reflection image of the defect.

[0056] (5) Move the probe along the circumferential and axial directions until the defect display amplitude is the highest and the defect image is located at the center of the horizontal axis of the fully focused image;

[0057] (6) In the axial direction of the pipe, the defect is located directly below the center of the probe's electronic scanning direction. In the circumferential direction of the pipe, the normal to the center of the wedge 4 surface extends downwards and intersects the inner wall at a point. Moving clockwise along the circumferential direction from this point by an arc length l will reveal the defect location. The arc length l can be expressed as:

[0058] (2)

[0059] (3)

[0060] In the formula: R is the outer diameter of the metal pipe; T is the thickness of the metal pipe; θ2 is the angle between the normal of the center of the wedge surface and the normal of the inner wall defect; θ1 is the angle between the normal of the plane of the wedge and the normal of the center of the wedge surface; C1 is the sound velocity of the plexiglass wedge; C2 is the sound velocity of the metal pipe.

[0061] The ultrasonic phased array detector and method for detecting defects in the inner wall of metal pipes in this embodiment were used to inspect a non-destructive testing block of a metal steel pipe and extract the defect detection signal. The testing block was a quarter-section (90° arc angle) of a steel pipe with an inner diameter of 155 mm, an outer diameter of 275 mm, and a length of 200 mm, with a longitudinal wave velocity of 5930 m / s. Two artificial defects were machined perpendicular to the inner wall: a groove with a depth of 0.1 mm, a length of 5 mm, and a width of 0.5 mm, and a flat-bottomed hole with a depth of 0.3 mm and a diameter of 0.5 mm. The axial spacing of the artificial defects was 50 mm, located at a quarter-section (22.5°) of the arc surface. The parameters of the test block are as follows. Figure 7 As shown. Figure 7 (a) is the front view of the test block. Figure 7 (b) is a cross-sectional view of test block AA. Figure 7 (c) is a cross-sectional view of test block BB.

[0062] During the detection process, the probe is pressed Figure 8 Arranged in this way, Figure 8 (a) is a front view of the probe layout. Figure 8 (b) Left view of probe setup Figure 8 (c) is a top view of the probe arrangement. When the metal pipe is made of steel, the sound velocity C2 of the pipe is 5930 m / s, the outer diameter of the pipe is 137.5 mm, the thickness is 60 mm, the sound velocity C1 of the plexiglass wedge is 2730 m / s, the thickness is 2 mm, the pulse width d is 0.64 mm, and θ1 in equation (1) is 6.53°. The measured detection signal depths of the two artificial defects are 62.75 mm and 62.43 mm, respectively, both greater than the depth of the reflection image of the inner wall of the pipe (60 mm), and the signal-to-noise ratio is greater than 5. Therefore, this image is the reflection image of the end corner of the defect.

[0063] Full-focus imaging of a groove with a depth of 0.1 mm, a length of 5 mm, and a width of 0.5 mm, and defect detection signals are shown below. Figure 9 and Figure 10 As shown; the full-focus image and defect detection signal of the flat-bottomed hole with a depth of 0.3 mm and a diameter of 0.5 mm were extracted. Figure 11 and Figure 12 As shown. The signal-to-noise ratio (SNR) is defined as follows:

[0064] (4)

[0065] In the formula, A S A represents the amplitude of the reflected wave from the defect. N This represents the noise amplitude.

[0066] Substituting into equation (4) and analyzing the three sets of detection signals, we obtained the following: the signal-to-noise ratio of the groove with a depth of 0.1 mm, a length of 5 mm, and a width of 0.5 mm is 15.33; the signal-to-noise ratio of the flat-bottomed hole with a depth of 0.3 mm and a diameter of 0.5 mm is 13.39.

[0067] Substituting into equation (3), we know that the angle θ2 between the center normal of the wedge surface and the normal at the defect on the inner wall is 11.70°. Substituting into equation (2), we know that the arc length l is 15.83 mm. In the circumferential direction of the pipe, the angle between the normal at the defect on the inner wall and the center normal of the wedge surface is 11.70°. The normal of the wedge surface extends downward and intersects the inner wall at a point. Moving clockwise 15.83 mm from that point, we find the location of the defect. In the axial direction of the pipe, the defect is located directly below the center of the probe's electronic scanning direction.

[0068] Overall, the ultrasonic phased array detection probe and method for defects in the inner wall of metal pipes can extract high signal-to-noise ratio end-angle reflection signals of shallow surface defects in the inner wall, and can be used to detect shallow surface defects in the inner wall of metal pipes.

[0069] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A metal pipe inner wall defect ultrasonic phased array detection probe, characterized in that: The array transducer, the connector and the wedge are included, the bottom surface of the array transducer is coupled with the top surface of the wedge through an oil film, the connector includes a first connector and a second connector, the first connector and the second connector are clamped on both sides of the array transducer and the wedge after coupling, and are fixed through a fastener, and the end surface of the bottom of the wedge is the same as the curvature radius of the outer wall of the metal pipe to be detected.

2. The probe for ultrasonic phased array testing of inner wall defects of metal pipes according to claim 1, characterized in that: The end surface of the top of the wedge is a plane, the size of which is the same as the emission and receiving surface of the array transducer, the bottom surface of the wedge is a curved surface, the included angle between the normal line of the plane of the wedge and the central normal line of the curved surface of the wedge is θ1, and the central thickness of the curved surface is less than 3 mm.

3. The probe of claim 1, wherein: The central frequency of the array transducer is 7.5 MHz-12.5 MHz, and the number of array elements is at least 64.

4. The method according to any one of claims 1 to 3, wherein the method is characterized by, The method comprises the following steps: S1, a wedge with a customized curvature radius is installed at the front end of the array transducer according to the curvature radius of the outer wall of the detection object, the wedge is connected with the array transducer through the connector, the wedge is attached to the outer wall of the metal pipe to be detected, the array transducer emits ultrasonic waves obliquely to the inner wall defect in the wafer length direction of each array element, and the calculation formula of the included angle θ1 between the normal line of the plane of the wedge and the central normal line of the curved surface of the wedge is as follows: (1) In the formula, C1 is the sound velocity of the plexiglass wedge, C2 is the sound velocity of the metal pipe, T is the wall thickness of the metal pipe, and d is the pulse width. S2, the metal pipe inner wall defect ultrasonic phased array detection probe is installed on the outer wall of the pipe, the array element arrangement direction of the array transducer is along the axial direction, and the wedge is coupled with the outer wall of the metal pipe through an oil film; S3, a single array element of the array transducer is sequentially excited, and reflected echoes are received by all array elements, and signals are saved as a three-dimensional full matrix signal data set containing a transmission and reception sequence; Full focus imaging is performed based on the three-dimensional full matrix signal to obtain a full focus detection image of the inner wall defect; S4, in the full focus detection image, if a reflection image with a signal-to-noise ratio higher than 5 is found at a depth greater than T, it is determined to be an end angle reflection image of a defect; S5, the metal pipe inner wall defect ultrasonic phased array detection probe is moved along the circumferential direction and the axial direction until the defect shows the highest amplitude, and meanwhile, the defect image is located at the center of the horizontal axis of the full focus image; S6, in the axial direction of the metal pipe, the defect is located directly below the center of the electronic scanning direction of the probe; in the circumferential direction of the pipe, the central normal line of the curved surface of the wedge extends downward and intersects with the inner wall at a point, and the defect position is an arc length l clockwise moved along the circumferential direction from the point, as shown in the following formula: (2) (3) In the formula, R is the outer diameter of the metal pipe, T is the thickness of the metal pipe, θ2 is the included angle between the central normal line of the curved surface of the wedge and the normal line at the defect of the inner wall, θ1 is the included angle between the normal line of the plane of the wedge and the central normal line of the curved surface of the wedge, C1 is the sound velocity of the plexiglass wedge, and C2 is the sound velocity of the metal pipe.

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