A dual-crystal phased array detection device and method for converging acoustic beams using a curved surface

Abstract

The present invention is applicable to the technical field of ultrasonic testing for butt welds of small-diameter nozzles, and discloses a dual-crystal phased array detection device and method using a curved surface to converge sound beams. The detection device includes a probe and wedge integrated device, a mechanical scanning device, an ultrasonic phased array detector, a stepper motor controller, and a water spraying device. Based on the detection method of this detection device, the sound beam divergence angle covers the weld thickness through the curved surface of the small-diameter nozzle to converge the sound beam, the sound beam covers the weld width through the electronic fan scanning technology, the dual-crystal phased array probe reduces the detection blind area through the one-transmit-one-receive mode, and the transverse crack detection is solved through the tip diffraction technology. The present invention realizes the detection, defect location, and quantification of butt welds of small-diameter nozzles, and improves the reliability of transverse crack detection.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic testing for butt welds of small-diameter nozzles, and particularly to a dual-crystal phased array testing device and method using a curved surface to converge acoustic beams.

Background Art

[0002] The heads and nozzles of important thick-walled pressure-bearing equipment such as high-pressure hydrogen storage containers often adopt an embedded structure. This structure bears welding stress, structural stress, shear force, and thermal stress generated by high-temperature fluctuations, and is prone to defects, leading to equipment failure. Due to the high pressure borne by thick-walled pressure-bearing equipment, the inner diameter of the nozzle is usually small, the wall thickness is large, and the weld width between the nozzle and the thick-walled head is large. Conventional non-destructive testing techniques are difficult to effectively detect surface and buried defects. For example, the butt weld between the nozzle of a fully multi-layer high-pressure hydrogen storage container and a double-layer hemispherical head has a special structure, and existing radiographic testing, magnetic particle testing, penetrant testing, and corresponding testing equipment are all difficult to effectively detect defects generated during the manufacturing process and use process. Currently, there are few reports on successfully detecting such welds at home and abroad. When conventional external inspections cannot obtain effective results, internal inspection has become a research direction for detecting the nozzle welds of such containers. However, the inner diameter of the nozzle at the top of the head of a fully multi-layer high-pressure hydrogen storage container is narrow, and conventional testing equipment cannot enter it.

[0003] Ultrasonic testing has the advantages of convenient operation, high resolution, low cost, wide adaptability, and high sensitivity to area-type defects in thick-walled containers. For the internal inspection of such small-diameter nozzles, the inventor has invented a testing device for the butt weld of the head of a fully multi-layer high-pressure hydrogen storage container based on ultrasonic phased array and multiple wedges, which avoids the echo covering the detection area at the interface between the nozzle and the wedge through multiple wedges. Although the above method achieves focusing in the axial direction and a certain degree of convergence in the circumferential direction of the acoustic beam, due to the use of a single probe for self-emanation and self-reception, the acoustic beam width is large in the axial direction, and there are many forest echoes generated by the coarse grains of austenitic welds; in addition, the self-emanation and self-reception detection method causes the echo at the interface between the nozzle and the wedge to interfere with the detection to a certain extent, especially the reliability of detecting transverse cracks in the weld is low. Currently, relevant standards and textbooks usually use oblique parallel scanning or parallel scanning after grinding the weld reinforcement flat for ultrasonic testing of transverse cracks in welds. However, for the detection of transverse cracks in the butt weld between a small-diameter nozzle and a thick-walled head, the above detection methods have the following problems: 1) Due to the thick wall thickness and small diameter of the nozzle, the oblique parallel scanning along the weld or the parallel scanning after grinding the weld reinforcement flat deviates from the circular weld when the acoustic beam reaches a certain acoustic path; 2) The fillet weld height is large, and it is difficult to grind the reinforcement flat. Therefore, existing detection standards and processes are difficult to effectively perform ultrasonic testing on transverse cracks in the butt weld between a small-diameter nozzle and a head.

Summary of the Invention

[0004] The object of the present invention is to overcome the deficiencies of the above-mentioned prior art, and to provide a dual-crystal phased array detection device and method for converging sound beams using a curved surface.

[0005] To achieve the above object, the present invention provides a dual-crystal phased array detection device for converging sound beams using a curved surface, which includes a probe and wedge integrated device, a mechanical scanning device, an ultrasonic phased array detector, a stepping motor controller, and a water spraying device; the probe and wedge integrated device is installed in the mechanical scanning device and extends into the inner hole of the nozzle together; the probe and wedge integrated device includes a dual-crystal phased array probe and a wedge, and the dual-crystal phased array probe is installed above the wedge; the dual-crystal phased array probe includes a transmitting wafer group and a receiving wafer group that are symmetrically arranged.

[0006] Preferably, it can be used to detect the butt weld formed by the double-layer hemispherical head and the embedded nozzle of a high-pressure hydrogen storage container, and the inner diameter of the nozzle is 39.5 mm.

[0007] Preferably, a rubber gasket is provided between the dual-crystal phased array probe and the inner wall of the nozzle.

[0008] Preferably, the surface of the wedge where the dual-crystal phased array probe is installed above is two symmetrically concave planes, the lower part of the wedge is an outer convex curved surface that matches the inner wall of the nozzle, and a sound insulation layer is provided in the middle of the wedge.

[0009] Preferably, the wedge is provided with a water injection hole on the side close to the mechanical scanning device, a water diversion hole extending radially to the nozzle connecting the water injection hole, and a coupling water tank connecting the water diversion hole and the inner wall of the nozzle.

[0010] Preferably, the mechanical scanning device includes an in-pipe support shaft, a fixed sleeve, a bearing, an encoder, and a stepping motor; one end of the in-pipe support shaft installs the probe and wedge integrated device, and the other end of the in-pipe support shaft is connected to the stepping motor; the bearing is sleeved in the middle of the in-pipe support shaft, and the bearing is installed in the fixed sleeve through an outer bearing housing; the encoder is sleeved at the end of the in-pipe support shaft.

[0011] Preferably, the fixed sleeve is installed outside the nozzle, the encoder is installed on the fixed sleeve through an encoder bracket, and the stepping motor is installed on the other side of the encoder.

[0012] Preferably, the support shaft is provided with an axial limit step, a shaft sleeve and a shaft circlip are installed along the axis, and a bearing end cover is fixed at the end of the outer bearing housing.

[0013] Preferably, the ultrasonic phased array detector is connected to the dual-crystal phased array probe and the encoder through a data interface. The stepper motor controller controls the stepper motor through a motor data line. The water spraying device injects the water in the water spraying tank into the wedge through a water pipe.

[0014] To achieve the above object, the present invention proposes a detection method for a dual-crystal phased array using a curved surface to converge sound beams, which uses the above detection device and includes the following steps:

[0015] S1: Clear the debris in the inspection area of the inner hole of the nozzle, and control the mechanical scanning device to extend the probe and wedge integrated device into the detection position of the inner hole of the nozzle;

[0016] S2: Open the water spraying tank to inject water into the coupling water tank of the wedge for coupling;

[0017] S3: Start the ultrasonic phased array detector, adjust the detection parameters, so that the dual-crystal phased array probe uses the electronic fan scanning focusing technology in the axial direction of the nozzle, and the scanning area covers the thickness of the butt weld;

[0018] Through the dual-crystal phased array probe with the designed wafer angle and position, the receiving wafer group receives the sound beam emitted by the transmitting wafer group in the circumferential direction of the nozzle, so that the semi-diffusion angle covers the width of the butt weld; the signals received by the receiving wafer group form a phased array imaging result and an end diffraction imaging result. The phased array imaging result includes S, B, C, and D scanning patterns generated in different projection directions. The end diffraction imaging result is formed by replacing the axial scan of the conventional end diffraction probe with an encoder by the scanning technology in the active aperture direction;

[0019] The deflection angle, position, and active aperture length of the wafer group in the dual-crystal phased array probe are determined by the following formula:

[0020]

[0021] In the formula: λ is the wavelength of the ultrasonic wave, b is half of the wafer width, β2 is the refraction angle of the outer diffusion sound field boundary on the workpiece to be inspected, γ2 is the angle between the outer diffusion sound field boundary and the weld, α2 is the incident angle of the outer diffusion sound field boundary on the wedge, is the radius of the inner surface of the nozzle, l1 is the distance between the upper boundary of the heat-affected zone and the detection surface, l2 is the total length of the heat-affected zone of the butt weld, C L1 is the longitudinal wave sound velocity of the wedge, C L2 is the longitudinal wave sound velocity of the workpiece to be inspected, x o1 is the position of the transmitting wafer on the x-axis, y o1 is the position of the transmitting wafer on the y-axis, k is the distance between the inner boundary of the wafer and the vertical center line, is the position of the incident point of the outer diffusion sound field boundary of the transmitting wafer on the x-axis. is the position of the incident point of the outer diffusion sound field boundary of the transmitting wafer on the y-axis, N 矩形 is the near-field length of the phased array probe, k 矩形 is the near-field correction coefficient of the near-field length of the phased array probe, and F is the focal length of the phased array probe;

[0022] S4: Start the stepping motor, and rotate the probe and wedge integrated device through the mechanical scanning device so that it performs a 450° circumferential scan within the inner hole of the nozzle; after the 450° circumferential scan is completed, the scanning program stops, and the stepping motor immediately rotates in the reverse direction by 90° to drive the probe and wedge integrated device and the mechanical scanning device to return to the initial detection position.

[0023] Compared with the prior art, the beneficial effects of a dual-crystal phased array detection device and method using a curved surface to converge sound beams provided by the present invention are as follows:

[0024] 1. The present invention uses the inner hole curved surface of a small-diameter nozzle to converge sound beams, and the curved surface cooperates with a wedge having a certain height and angle to deflect the sound beams, realizing that the sound beam divergence angle covers the weld thickness within a small detection space, and the sound beam divergence angle is small, which can concentrate the sound beam energy, effectively reduce the influence of severe scattering of coarse-grained materials on detection, and improve detection sensitivity.

[0025] 2. The present invention adopts a dual-crystal phased array probe, and through the one-transmitting and one-receiving mode, avoids the inherent wave signals of the wedge and the interface, and obtains defect signals with a higher signal-to-noise ratio.

[0026] 3. The present invention adopts a longitudinal wave wedge. Longitudinal waves have better penetration ability than transverse waves, and the wedge and the probe are customized separately, which is convenient for replacing the wedge after wear.

[0027] 4. In the present invention, the ultrasonic phased array technology adopts an electronic fan scanning technology in the active aperture direction, which can realize that the entire weld width can be covered by the scanning sound beam; in different projection directions, various patterns such as S, B, C, and D can be generated to detect longitudinal cracks, lack of penetration, lack of fusion, and volumetric defects such as pores and slag inclusions.

[0028] 5. In the present invention, the tip diffraction technology solves the detection problem of transverse cracks in fillet welds, and combines with the array of the phased array probe to realize the automatic scanning of the tip diffraction technology in the axial direction of the nozzle.

[0029] 6. The present invention combines ultrasonic phased array technology, tip diffraction technology and the encoder of the mechanical scanning device to achieve precise defect positioning and quantification. Through the phased array focusing rule, the sound beam is strongly focused in the active aperture direction to achieve defect positioning and defect height quantification in the weld width direction; through tip diffraction, defect positioning and defect length quantification in the weld thickness direction are achieved; through the rotary encoder, the defect conditions in the circumferential direction are dynamically analyzed to achieve defect positioning and defect width quantification in the circumferential direction.

[0030] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings.

Description of the Drawings

[0031] Figure 1 Overall structural block diagram of the detection automatic scanning device.

[0032] Figure 2 Schematic structural diagram of the probe and wedge integrated device.

[0033] Figure 3 Front view structural diagram of the wedge.

[0034] Figure 4 Right view structural diagram of the wedge.

[0035] Figure 5 Schematic structural diagram of the mechanical scanning device.

[0036] Figure 6 Dual-crystal sound field coverage diagram.

[0037] Figure 7 Diagram for calculating the deflection angle of the wafer.

[0038] Figure 8 Partial enlarged view of the deflection angle of the wafer.

[0039] Figure 9 Diagram for calculating the position of the wafer.

[0040] Figure 10 Schematic diagram of the principle of defect detection by tip diffraction technology.

[0041] Figure 11 Schematic diagram of the phased array focusing rule and electronic sector scanning.

[0042] Figure 12 Schematic diagram of the phased array focusing rule and electronic sector scanning imaging.

[0043] In the figure: 1. Double-layer hemispherical head; 2. Butt weld; 3. Water spray tank; 4. Water spray pipe; 5. Detector power supply; 6. Ultrasonic phased array detector; 7. Encoder data cable; 8. Ultrasonic data cable; 9. Inner hole of nozzle; 10. Nozzle; 11. Integrated device of probe and wedge; 12. Mechanical scanning device; 13. Controller power supply; 14. Motor data cable; 15. Control panel; 16. Stepper motor controller; 17. Dual-crystal phased array probe; 18. Transmitting chip group; 19. Receiving chip group; 20. Rubber gasket; 21. Inner support shaft of pipe; 22. Coupling water tank; 23. Wedge; 24. Sound insulation layer; 25. Screw; 26. Screw hole; 27. Water injection hole; 28. Water diversion hole; 29. Fixed sleeve; 30. Outer bearing housing; 31. Bearing end cover; 32. Encoder bracket; 33. Encoder; 34. Stepper motor; 35. First bearing; 36. Sleeve; 37. Second bearing; 38. Shaft circlip for shaft.

Detailed implementation manners

[0044] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to 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 descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0045] 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 can 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 can be directly connected to the other element or indirectly connected to the other element.

[0046] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use. It is 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 should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "a plurality" is two or more, unless otherwise specifically defined. The meaning of "several" is one or more, unless otherwise specifically defined.

[0047] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connection" 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 directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] Referring to Figure 1 and Figure 2 , an embodiment of the present invention provides a dual-crystal phased array detection device using a curved surface to converge sound beams, including a probe and wedge integrated device 11, a mechanical scanning device 12, an ultrasonic phased array detector 6, a stepper motor controller 16, and a water spraying device. The probe and wedge integrated device 11 is installed in the mechanical scanning device 12 and together extends into the inner hole 9 of a small-diameter nozzle to detect the butt weld 2 and its heat-affected zone where the double-layer hemispherical head 1 and the single-layer nozzle 10 are connected. The probe and wedge integrated device 11 includes a dual-crystal phased array probe 17 and a wedge 23. The dual-crystal phased array probe 17 is installed above the wedge 23. The dual-crystal phased array probe 17 includes a transmitting wafer group 18 and a receiving wafer group 19 that are symmetrically arranged with each other to achieve dual-crystal detection.

[0049] A rubber gasket 20 is provided between the dual-crystal phased array probe 17 and the inner wall of the nozzle 10, achieving an interference fit with the inner hole 9 of the nozzle, serving to press the dual-crystal phased array probe 17 and meeting the requirements of ultrasonic coupling. Above the wedge block 23 are two symmetrically concave planes for mounting the dual-crystal phased array probe 17; below the wedge block 23 is a convex curved surface for mating with the curved surface of the inner hole 9 of the nozzle; a sound insulation layer 24 is provided in the middle of the wedge block 23 to prevent the sound beam emitted by the transmitting wafer group 18 from being directly received by the receiving wafer group 19 after reflection at the interface.

[0050] The ultrasonic phased array detector 6 is connected to the dual-crystal phased array probe 17 through an ultrasonic data cable 8 to control the emission and reception of ultrasonic waves; the ultrasonic phased array detector 6 is connected to the hollow shaft rotary encoder 33 on the front shaft of the stepper motor 34 through an encoder data cable 7 to determine the detection position. The detector power supply 5 supplies power to the ultrasonic phased array detector 6.

[0051] The stepper motor controller 16 is connected to the stepper motor 34 through a motor data cable 14 to control the movement of the mechanical scanning device 12; the stepper motor controller 16 conducts human-machine interaction through the control panel 15. The controller power supply 13 supplies power to the stepper motor controller 16.

[0052] Refer to Figure 1 and Figure 5 In an optional embodiment, referring to

[0053] and

[0054] the mechanical scanning device 12 includes an in-pipe support shaft 21, a fixed sleeve 29, a first bearing 35, a second bearing 37, an encoder 33, and a stepper motor 34. One end of the in-pipe support shaft 21 is installed with a probe and wedge block integrated device 11, and the other end of the in-pipe support shaft 21 is connected to the stepper motor 34 to transfer the movement from the stepper motor 34 to the probe and wedge block integrated device 11, realizing circumferential automatic scanning. The first bearing 35 and the second bearing 37 are sleeved on the middle part of the in-pipe support shaft 21, and the outer sides are installed in the fixed sleeve 29 through an outer bearing housing 30 to support the in-pipe support shaft 21 and reduce friction. The encoder 33 is sleeved on the end part of the in-pipe support shaft 21, and the outer side is installed on the fixed sleeve 29 through an encoder bracket 32 to play a role in positioning the rotation angle of the in-pipe support shaft 21. The fixed sleeve 29 is installed on the outside of the nozzle 10, and the stepper motor 34 is installed on the encoder 33 to realize the overall fixation of the mechanical scanning device 12. Figure 1 and Figure 3 The support shaft 21 is provided with an axial limit step, a shaft sleeve 36 and a shaft circlip 38 are installed along the axis, and a bearing end cover 31 is installed at the end of the outer bearing housing 30 to realize the axial positioning of the first bearing 35 and the second bearing 37. Figure 4, in an optional embodiment, the wedge 23 is provided with a water injection hole 27 near the opening side of the nozzle 10, a water diversion hole 28 that radially extends from the water injection hole 27 to both sides of the detection surface of the wedge 23, and an axially extending coupling water tank 22 that connects the water diversion hole 28 and the inner wall of the nozzle 10. The water spray tank 3 transfers water to the water injection hole 27 through the water spray pipe 4. The water flow goes into the interior of the wedge 23 along the water injection hole 27, is diverted along the water diversion hole 28 to the coupling water tanks 22 on both sides of the wedge 23, and the water in the coupling water tanks 22 is coupled with the detection surface of the inner hole 9 of the nozzle.

[0055] Several screw holes 26 are drilled on the side surface of the wedge 23 ( Figure 3 4 on each side), and it is installed on the inner support shaft 21 of the pipe through screws 25 to fix the connection between the probe and wedge integrated device 11 and the mechanical scanning device 12.

[0056] In an optional embodiment, this device mainly targets small-diameter nozzles 10 with an inner diameter of 39.5 mm and the material being austenitic stainless steel.

[0057] In an optional embodiment, the butt weld 2 and its heat-affected zone are at a relatively far distance from the detection surface of the inner hole 9 of the nozzle, and the width of the butt weld 2 is relatively wide. When selecting appropriate probe frequencies, wafer widths, wedge materials, etc., the detection method using the above detection device includes the following steps:

[0058] S1: Remove debris in the scanning area of the inner hole 9 of the nozzle, and control the mechanical scanning device 12 to extend the probe and wedge integrated device 11 into the detection position of the inner hole 9 of the nozzle.

[0059] S2: Turn on the water spray tank 3 to inject water into the coupling water tank 22 of the wedge 23, and couple the wedge 23 and the detection surface of the inner hole 9 of the nozzle.

[0060] S3: Start the ultrasonic phased array detector 6, adjust the detection parameters, so that the dual-crystal phased array probe 17 uses the electronic fan scanning focusing technology in the axial direction of the nozzle 10, and the scanning area covers the thickness of the butt weld 2. Through the dual-crystal phased array probe 17 with the wafer angle and position designed, the receiving wafer group 19 in the circumferential direction of the nozzle 10 receives the sound beam emitted by the transmitting wafer group 18, and the semi-divergence angle covers the width of the butt weld 2. The signals received by the receiving wafer group 19 form the phased array imaging result and the tip diffraction imaging result. The phased array imaging result includes S, B, C, D scanning patterns generated in different projection directions, and the tip diffraction imaging result is formed by replacing the axial scanning of the conventional tip diffraction probe with an encoder by the scanning technology in the active aperture direction.

[0061] The deflection angle, position, and active aperture length of the wafer group in the dual-crystal phased array probe 17 are determined by the following method.

[0062] Refer to Figure 6and Figure 7 , calculation of the wafer diffusion angle: For the butt weld 2, the heat affected zone is in the diffusion zone of the transmitting wafer group 18, and the diffusion angle is 2θ. The outer diffusion sound field boundary intersects at F2, just covering the bottom surface S2 of the heat affected zone; the inner diffusion sound field boundary intersects at F1, slightly higher than the top surface S1 of the heat affected zone. The half-diffusion angle of the wafer in the wedge 23 is calculated according to the following formula:

[0063]

[0064] In the formula, θ is the diffusion angle, λ is the wavelength of the ultrasonic wave, and b is half of the wafer width.

[0065] Refer to Figure 7 and Figure 8 , calculation of the wafer deflection angle: The outer diffusion sound field boundary covers the bottom surface S2 of the heat affected zone. According to the sine law, the angle where the normal O1P 11 is located can be known; the angle where the outer diffusion sound field boundary is located is calculated through the normal angle and the incident angle; the wafer deflection angle δ is obtained by subtracting the half-diffusion angle from the angle of the boundary. The wafer deflection angle δ can be calculated according to the following formula:

[0066]

[0067] In the formula: β2 is the refraction angle of the outer diffusion sound field boundary on the workpiece to be inspected; γ2 is the included angle between the outer diffusion sound field boundary and the weld; α2 is the incident angle of the outer diffusion sound field boundary on the wedge; r is the radius of the inner surface of the nozzle; l1 is the distance between the upper boundary of the heat affected zone and the detection surface; l2 is the total length of the heat affected zone of the butt weld 2; C L1 is the longitudinal wave sound velocity of the wedge; C L2 is the longitudinal wave sound velocity of the workpiece to be inspected.

[0068] Refer to Figure 8 and Figure 9 , calculation of the wafer position: In the setting of the wafer position, if the wafer position is too high, the wafer boundary may exceed the vertical center line, and the reserved space for the probe is too small; if the wafer position is too low, the focus F1 of the inner diffusion sound field boundary is too high, resulting in non-concentrated energy. According to the wafer boundary limitation, the wafer position is calculated according to the following formula.

[0069]

[0070] In the formula: x o1 is the position of the transmitting wafer on the x-axis; y o1 is the position of the transmitting wafer on the y-axis; k is the distance between the inner boundary of the wafer and the vertical center line, generally greater than 0.5 mm; is the position of the incident point of the outer diffusion sound field boundary of the transmitting wafer on the x-axis; It is the position of the incident point of the external diffusion sound field boundary of the transmitting wafer on the y-axis.

[0071] Calculation of the active aperture length of the probe: To achieve the focusing effect, the focal length F of the phased array probe generally needs to be less than the length of the near field region. According to the near field length limitation of the phased array probe, the length L of the active aperture of the probe is calculated according to the following formula:

[0072]

[0073] In the formula: N 矩形 is the length of the near field region of the phased array probe; k 矩形 is the near field correction coefficient of the length of the near field region of the phased array probe; F is the focal length of the phased array probe, and in the alternative embodiment, F is 120 mm.

[0074] Applying the above calculation method to the position and angle calculation of the dual crystal phased array probe 17 can make the diffused sound beam cover the weld width and improve the detection sensitivity. If there are defects such as transverse cracks in the width direction of the butt weld 2, diffracted waves are generated at both ends of the crack and received by another probe; if there are longitudinal cracks or volumetric defects such as pores and slag inclusions, reflected waves are formed and received by another probe.

[0075] S4: Start the stepping motor 34, and through the mechanical scanning device 12, the probe and the wedge integrated device 11 are scanned circumferentially by 450° in the inner hole 9 of the nozzle. After the 450° circumferential scan is completed, the scan program stops, and the stepping motor 34 immediately rotates automatically in the reverse direction by 90° to drive the probe and the wedge integrated device 11 and the mechanical scanning device 12 to return to the initial detection position.

[0076] The detection method is specifically introduced through different drawings, such as Figure 10 As shown, through the designed wafer angle and position, the sound beam coverage in the width direction of the weld is achieved, and defects such as transverse cracks are detected and imaged according to the principle of tip diffraction. Since the inner wall of the nozzle 10 is concave and the near surface area is far from the heat affected zone, the outer surface and the near outer surface do not need to be covered by the sound beam, and there is no direct wave, so there is no detection blind area on the outer surface; since it is the base material of the head 1 in the width direction of the weld and there is no reflected wave on the inner surface, there is no detection blind area on the inner surface. In the tip diffraction technology of the present invention, the focusing scanning technology in the active aperture direction is equivalent to the axial movement of the probe, replacing the mechanical scanning of the conventional tip diffraction probe with an encoder.

[0077] Such as Figure 11 and Figure 12As shown, through the phased array focusing technology, the full coverage of the acoustic beam in the thickness direction of the butt weld 2 is achieved, and the volume defects such as longitudinal cracks or pores and slag inclusions are detected and imaged according to the phased array principle. In the active aperture direction, the receiving chip group 19 and the transmitting chip group 18 use the same focusing technology and are symmetrically arranged at the same angle as the transmission. The fan scanning focusing technology deflects the acoustic beam to both sides on a smaller detection surface so that the acoustic beam covers the entire width of the butt weld 2. The receiving chip group 19 performs ultrasonic imaging on the obtained detection signal according to the phased array principle to form phased array S scan, B scan, C scan, D scan and other scanning result images.

[0078] The present invention adopts a combination of mechanical scanning and electronic scanning. The circumferential scanning adopts the mechanical scanning of the encoder 33, and the axial scanning adopts the electronic scanning of the array of the dual-crystal phased array probe 17. By scanning the image through the phased array and the end point diffraction, the defects in different circumferential directions are dynamically analyzed, and all internal defects of the butt weld 2 can be detected. It not only effectively overcomes the problem of missed detection of area defects, but also can accurately quantify and locate defects, thereby judging the safety condition of the weld. Through the phased array focusing law, the sound beam is strongly focused in the active aperture direction to achieve defect location and defect height quantification in the weld thickness direction; through end point diffraction, defect location and defect length quantification in the weld width direction are achieved; through the encoder 33, the defects in the circumferential direction are dynamically analyzed to achieve defect location and defect width quantification in the circumferential direction.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A detection method for a double-crystal phased array detection device using a curved surface to converge sound beams, which uses a detection device. The detection device includes a probe and wedge integrated device, a mechanical scanning device, an ultrasonic phased array detector, a stepper motor controller, and a water spraying device; the probe and wedge integrated device is installed in the mechanical scanning device and extends into the inner hole of the nozzle together; the probe and wedge integrated device includes a double-crystal phased array probe and a wedge, and the double-crystal phased array probe is installed above the wedge; the double-crystal phased array probe includes a transmitting wafer group and a receiving wafer group that are symmetrically arranged; it can be used to detect the butt weld formed by the double-layer hemispherical head and the embedded nozzle of a high-pressure hydrogen storage container, and the inner diameter of the nozzle is 39.5 mm; a rubber gasket is provided between the double-crystal phased array probe and the inner wall of the nozzle; the surface of the wedge where the double-crystal phased array probe is installed above is two symmetrically concave planes, and the lower part of the wedge is an outwardly convex curved surface that matches the inner wall of the nozzle, and a sound insulation layer is provided in the middle of the wedge; the wedge is provided with a water injection hole on the side close to the mechanical scanning device, a water diversion hole extending radially from the water injection hole to the inner wall of the nozzle, and a coupling water tank connecting the water diversion hole and the nozzle; the mechanical scanning device includes an in-pipe support shaft, a fixed sleeve, a bearing, an encoder, and a stepper motor; one end of the in-pipe support shaft installs the probe and wedge integrated device, and the other end of the in-pipe support shaft is connected to the stepper motor; the bearing is sleeved in the middle of the in-pipe support shaft, and the bearing is installed in the fixed sleeve through an outer bearing housing; the encoder is sleeved at the end of the in-pipe support shaft; the fixed sleeve is installed outside the nozzle, the encoder is installed on the fixed sleeve through an encoder bracket, and the stepper motor is installed on the other side of the encoder; the support shaft is provided with an axial limit step, a shaft sleeve and a shaft retaining snap ring are installed along the shaft, and a bearing end cover is fixed at the end of the outer bearing housing; the ultrasonic phased array detector is connected to the double-crystal phased array probe and the encoder through a data interface; the stepper motor controller controls the stepper motor through a motor data cable; the water spraying device injects the water in the water spraying tank into the wedge through a water pipe; The method includes the following steps: S1: Remove the debris in the scanning area of the inner hole of the nozzle, and control the mechanical scanning device to extend the probe and wedge integrated device into the detection position of the inner hole of the nozzle; S2: Open the water spraying tank to inject water into the coupling water tank of the wedge for coupling; S3: Start the ultrasonic phased array detector, adjust the detection parameters, so that the dual-crystal phased array probe adopts the electronic fan scanning focusing technology in the axial direction of the nozzle, and cover the thickness of the butt weld with the scanning area; through the dual-crystal phased array probe with the wafer angle and position designed, make the receiving wafer group receive the sound beam emitted by the transmitting wafer group in the circumferential direction of the nozzle, so that the semi-divergence angle covers the width of the butt weld; the signals received by the receiving wafer group form the phased array imaging result and the tip diffraction imaging result, the phased array imaging result includes the S, B, C, D scanning patterns generated in different projection directions, and the tip diffraction imaging result is formed by replacing the axial scan of the conventional tip diffraction probe with an encoder with the scanning technology in the active aperture direction; The deflection angle, position and active aperture length of the wafer group in the dual-crystal phased array probe are determined by the following formula: Where: θ is the diffusion angle, δ is the wafer deflection angle, λ is the wavelength of the ultrasonic wave, b is half of the wafer width, β2 is the refraction angle of the outer diffusion sound field boundary on the workpiece to be inspected, γ2 is the angle between the outer diffusion sound field boundary and the weld, α2 is the incident angle of the outer diffusion sound field boundary on the wedge, r is the radius of the inner surface of the pipe, l1 is the distance between the upper boundary of the heat affected zone and the detection surface, l2 is the total length of the heat affected zone of the butt weld, C L1 is the longitudinal wave sound velocity of the wedge, C L2 is the longitudinal wave sound velocity of the workpiece to be inspected, x o1 is the position of the transmitting wafer on the x-axis, y o1 is the position of the transmitting wafer on the y-axis, k is the distance between the inner boundary of the wafer and the vertical center line, is the position of the incident point of the outer diffusion sound field boundary of the transmitting wafer on the x-axis, is the position of the incident point of the outer diffusion sound field boundary of the transmitting wafer on the y-axis, N 矩形 is the near-field zone length of the phased array probe, k 矩形 is the near-field correction coefficient of the near-field zone length of the phased array probe, F is the focal length of the phased array probe; S4: Start the stepping motor, rotate the probe and wedge integrated device through the mechanical scanning device in the inner hole of the nozzle for 450° circumferential scanning; after the 450° circumferential scanning is completed, the scanning program stops, and the stepping motor immediately rotates automatically in the reverse direction by 90° to drive the probe and wedge integrated device and the mechanical scanning device to return to the initial detection position.

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