Device and method for detecting laser ultrasonic defects of thermal-state metal component

Abstract

The invention discloses a laser ultrasonic defect detection device and method for a thermal-state metal component. The detection device comprises a high-temperature heating module, a laser excitation module, a laser detection module, a mobile scanning automatic focusing module and a signal acquisition and control module, the laser excitation module and the laser detection module excite laser, the excitation laser and the detection laser are emitted to different positions of a metal component to be detected through the mobile scanning automatic focusing module, and the reflected detection laser is transmitted to the signal acquisition and control analysis module through the optical probe and the interferometer to be processed and imaged. The detection device disclosed by the invention has the functions of metal component high-temperature heating simulation, detection laser automatic focusing, rapid mobile scanning and defect automatic imaging, can efficiently realize accurate detection and imaging of surface and internal defects of a thermal-state metal component, and is suitable for dynamic defect detection simulation in a high-temperature extreme environment; and the defect that non-contact high-temperature nondestructive detection is difficult to realize by a conventional ultrasonic detection method is overcome.

Description

Technical Field

[0001] This invention relates to the field of laser ultrasonic testing technology, and specifically to a laser ultrasonic defect detection device and method for hot metal components based on synthetic aperture focusing imaging. Background Technology

[0002] As high-end equipment manufacturing fields such as aerospace, marine equipment, and rail transportation develop towards higher precision and performance, the demand for rapid non-destructive testing of defects in core and critical metal components is increasing. Rapid detection of microstructural defects in hot metal components during high-temperature manufacturing processes is beneficial for identifying, repairing, and suppressing defects in the early stages of manufacturing, and for promptly addressing components with defects exceeding acceptable limits. This reduces potential safety risks while avoiding waste of materials and energy.

[0003] Currently, non-destructive testing (NDT) methods capable of detecting defects in high-temperature environments mainly include machine vision, magnetic particle and penetrant testing, eddy current testing, X-ray testing, and ultrasonic testing. Machine vision, magnetic particle and penetrant testing, eddy current testing, and X-ray testing have certain limitations and cannot solve the problem of internal defect detection. Air-coupled ultrasonic testing is suitable for components with similar acoustic impedances, while electromagnetic ultrasonic testing has low efficiency and a large blind zone. Laser ultrasonic testing technology has been a research hotspot both domestically and internationally, possessing characteristics such as non-contact operation, high sensitivity, and applicability to non-destructive testing of complex-shaped components, showing great potential for rapid non-destructive testing of defects in hot-state metal components.

[0004] Furthermore, while existing technologies utilize laser ultrasonic technology for defect detection, the moving scanning mechanism and laser spot focusing mechanism used in high-temperature environments suffer from structural complexity, limited scanning range, and high cost, as well as low defect imaging accuracy. Therefore, to improve defect detection accuracy in high-temperature environments, it is necessary to provide a laser ultrasonic defect detection device and method for hot-state metal components. Summary of the Invention

[0005] The purpose of this invention is to provide a laser ultrasonic defect detection device and method for hot metal components, so as to overcome the problems mentioned in the background art.

[0006] To achieve the above objectives, this invention provides a laser ultrasonic defect detection device for hot metal components, comprising a high-temperature heating module, a laser detection module, a laser excitation module, a moving scanning autofocus module, and a signal acquisition and control module. The high-temperature heating module includes a high-temperature furnace with a support base inside, and a detection hole is formed on the side wall of the furnace. The laser detection module includes a dual-wavelength mixer interferometer and an optical probe, with the dual-wavelength mixer interferometer connected to the optical probe. The laser excitation module includes a laser, a beam expander, a reflector, a plano-convex mirror, and a dichroic mirror. The beam expander and the reflector are sequentially positioned in front of the laser's optical path, and the plano-convex mirror is positioned in the light-emitting direction of the reflector. A dichroic mirror is positioned in the light-emitting direction of the plano-convex mirror and the optical probe. The dichroic light from the dichroic mirror passes through the detection hole to detect the metal component to be tested, which is placed on the support base. The moving scanning autofocus module includes two parallel guide rails, each with a sensor at one end. Each guide rail has a slider and a lead screw mechanism. The two sliders are connected to a support plate, and the support plate has a moving platform and a moving platform drive mechanism. The signal acquisition and control module includes a display screen and a signal acquisition and control analysis system. The signal acquisition and control analysis system is connected to the laser, the dual-wavelength mixer interferometer, the sensor, the lead screw mechanism, and the moving platform drive mechanism, respectively. In this structural design, the reflector can adjust the relative positions of the excitation incident laser spot and the detection laser spot on the surface of the metal component being tested, making it suitable for different laser ultrasonic testing methods; the slider, moving platform, and combined signal acquisition and control analysis system can easily and quickly realize the automatic focusing function of the detection laser, suitable for optical probes with different focal lengths, and the set screw can prevent the slider from moving back and forth after reaching the specified focal length position, thus improving the sensitivity of the detection laser.

[0007] Furthermore, the aperture of the detection hole is 30mm~50mm, and the detection hole is fitted with high-transmittance sapphire heat-resistant glass. The two ends of the sapphire heat-resistant glass are coated with anti-reflective coatings, which is beneficial for the excitation laser and the detection laser to be incident on the surface of the metal component to be tested.

[0008] Furthermore, the laser, the beam expander, the reflector, the plano-convex mirror, the dichroic mirror, and the optical probe are fixed to the moving platform by bolts, and the input end of the optical probe is connected to a cooling box.

[0009] Furthermore, the lead screw mechanism includes a lead screw and a first servo motor, and the slider can slide along the lead screw in the forward and backward direction under the drive of the motor; the moving platform driving mechanism includes a second servo motor for driving the moving platform to move in the left and right direction and a third servo motor for driving the moving platform to move up and down.

[0010] Furthermore, the moving direction of the slider and the detection direction of the optical probe are both perpendicular to the sidewall plane where the detection hole is located; the moving plane of the moving platform is parallel to the sidewall plane where the detection hole is located.

[0011] Furthermore, the stroke of the slider is 300mm~500mm; the stroke of the moving platform in the left and right direction is 80mm~120mm; and the lifting height of the moving platform is 0~120mm.

[0012] Furthermore, after the two sliders reach the designated focal length position, the set screws on the side of the sliders are tightened to fix the set screws to the guide rail, thus preventing the device from moving relative to each other under external disturbances.

[0013] This invention also provides a method for laser ultrasonic defect detection of hot metal components, using the aforementioned laser ultrasonic defect detection device for hot metal components. The detection method includes the following steps:

[0014] S1. Start the signal acquisition and control analysis system, and control the moving slider to move away from the high-temperature heating furnace according to the focal length of the optical probe; open the furnace door of the high-temperature heating furnace, and fix the metal component to be tested on the support base in the high-temperature heating furnace using a clamp;

[0015] S2. Close the furnace door of the high-temperature heating furnace, move the slider through the signal acquisition and control analysis system, observe the detection laser receiving signal through the display screen, and adjust the position of the slider to obtain the best detection laser sensitivity;

[0016] S3. Next, the high-temperature heating furnace is started, and the high-temperature heating furnace heats the metal component to be tested according to the set program;

[0017] S4. Set various control parameters for the laser, dual-wave mixer interferometer, and moving platform;

[0018] S5. Activate the laser, the dual-wave mixing interferometer, the moving platform, and the optical probe to obtain the laser ultrasonic scanning signal of the metal component under test;

[0019] S6. The ultrasonic scanning signal is processed based on the synthetic aperture focusing imaging algorithm to finally obtain the surface and internal defect images of the metal component under test.

[0020] Furthermore, the moving step size of the mobile platform ranges from 0.01mm to 10mm, and the scanning range of the metal component under test is 0mm. 2 ~25mm 2 .

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) A laser ultrasonic defect detection device for hot metal components according to the present invention includes a high-temperature heating module, a laser excitation module, a laser detection module, a moving scanning autofocus module, and a signal acquisition and control analysis module. The laser excitation module and the laser detection module excite lasers, and the moving scanning autofocus module directs the excitation laser and the detection laser to different positions of the metal component under test in the high-temperature heating module. The reflected detection laser is transmitted to the signal acquisition and control analysis module for processing and imaging via an optical probe and an interferometer. The device of the present invention has a simple structure and is easy to operate. It has the functions of simulating high-temperature heating of metal components, automatic focusing of detection lasers, rapid moving scanning, and automatic defect imaging. It can efficiently realize accurate detection and imaging of surface and internal defects of hot metal components. It is suitable for dynamic defect detection simulation in extreme high-temperature environments and makes up for the shortcomings of conventional ultrasonic testing methods in achieving non-contact high-temperature non-destructive testing.

[0023] (2) The present invention provides a laser ultrasonic defect detection method for hot metal components. The laser ultrasonic defect detection test of the metal components under test is realized by a detection device based on synthetic aperture focusing imaging. This method solves the problems of low defect detection efficiency and poor defect imaging effect under high temperature conditions and shows great application potential in high temperature in-situ defect detection in the industrial and defense fields.

[0024] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0026] Figure 1 This invention provides a laser ultrasonic defect detection device for hot metal components based on synthetic aperture focusing imaging;

[0027] Figure 2 A scanning schematic diagram of laser excitation and reception for surface defect detection provided in this embodiment of the invention;

[0028] Figure 3 A scanning schematic diagram of laser excitation and reception for internal defect detection in an embodiment of the present invention;

[0029] Figure 4 A schematic diagram illustrating the imaging principle of surface defects in an embodiment of the present invention;

[0030] Figure 5 A schematic diagram illustrating the imaging principle of internal defects in an embodiment of the present invention;

[0031] Figure 6 A schematic flowchart of a laser ultrasonic defect detection method for hot metal components provided by the present invention;

[0032] In the diagram: 1. Laser; 2. Guide rail; 3. Beam expander; 4. Support plate; 5. Lead screw mechanism; 6. Reflector; 7. Plano-convex mirror; 8. Dichroic mirror; 9. Moving platform; 10. Optical probe; 11. Set screw; 12. Slider; 13. Optical fiber; 14. Two-wave mixing interferometer; 15-1. Display screen; 15-2. Signal acquisition and control analysis system; 16. Metal component under test; 17-1. High-temperature heating furnace; 17-2. Support base; 17-3. Detection hole; 18. Sensor. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent transformations or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0034] Please see Figure 1 This embodiment provides a laser ultrasonic defect detection device for hot metal components, including a high-temperature heating module, a laser detection module, a laser excitation module, a moving scanning autofocus module, and a signal acquisition and control module, with the specific structure as follows:

[0035] The high-temperature heating module includes a high-temperature heating furnace 17-1, inside which is a support base 17-2. The metal component 16 to be tested is fixed to the support base 17-2 by a clamp. A detection hole 17-3 is opened on the side wall of the high-temperature heating furnace 17-1. The diameter of the detection hole 17-3 is 30mm~50mm, which is used to emit and detect laser light incident on the surface of the metal component 16 through the detection hole 17-3. The detection hole 17-3 is equipped with high-transmittance sapphire heat-resistant glass, and its two ends are coated with an anti-reflective coating. The maximum heating temperature of the high-temperature heating furnace 17-1 is 1350℃, which can realize high-temperature heating simulation of various metal components.

[0036] The laser excitation module includes a laser 1, a beam expander 3, a reflector 6, a plano-convex mirror 7, and a dichroic mirror 8. The output laser from the laser 1 passes sequentially through the beam expander 3, the reflector 6, the plano-convex mirror 7, and the dichroic mirror 8 before being incident on the metal component 16 to be tested through the detection hole 17-3. The laser 1, beam expander 3, reflector 6, plano-convex mirror 7, and dichroic mirror 8 are fixed to the moving platform 9 of the moving scanning autofocus module by bolts. The laser 1 is a nanosecond pulse laser with an excitation laser wavelength of 532nm and a pulse width of 8ns. The beam expander 3 increases the beam diameter of the excitation laser and reduces the divergence angle. The reflector 6 adjusts the relative positions of the excitation incident laser spot and the detection laser spot on the surface of the metal component 16 under test. The plano-convex mirror 7 has a focal length of 100mm~300mm. The dichroic mirror 8 has high reflectivity for lasers with a wavelength of 532nm, enabling the excitation laser incident function.

[0037] The laser detection module includes a dual-wave mixing interferometer 14 and an optical probe 10. The optical probe 10 is fixed to the moving platform 9 by bolts, and the input end of the optical probe 10 is connected to the cooling box. The dual-wave mixing interferometer 14 and the optical probe 10 are connected by an optical fiber 13. The detection laser excited by the optical probe 10 is a continuous laser. The focal length of the optical probe 10 is 100mm~300mm. The detection laser excited by the optical probe 10 is incident on the metal component 16 to be tested through a dichroic mirror 8. The detection reflected laser carrying defect information is received by the optical probe 10 and input to the dual-wave mixing interferometer 14 to form interference fringes. The interference fringes are converted into electrical signals by a photodetector to realize the defect detection function.

[0038] The moving scanning autofocus module includes two guide rails 2, sliders 12, lead screw mechanisms 5, support plates 4, sensors 18, set screws 11, and a moving platform 9. The two guide rails 2 are arranged parallel to each other along the Y direction, and a sensor 18 is installed at one end of each guide rail 2. The sensor 18 is used to determine the relative position of the moving platform 9. Each guide rail 2 is equipped with a slider 12 and a lead screw mechanism 5. The base of the moving platform 9 is fixed to the support plate 4 by bolts, and the support plate 4 is connected to the sliders 12 on the two guide rails 2 by bolts. Set screws 11 are designed on the side of the sliders 12 to fix the sliders 12 and prevent vibration during detection. In this structural configuration, the lead screw mechanism 5 includes a lead screw and a first servo motor. The slider 12 can slide along the lead screw in the forward and backward direction under the drive of the first servo motor. The moving platform drive mechanism includes a second servo motor for driving the moving platform 9 to move in the left and right direction (X direction) and a third servo motor for driving the moving platform 9 to move in the up and down direction (Z direction). That is, the moving platform 9 can move in the left and right direction under the drive of the second servo motor and move up and down under the drive of the third servo motor. The moving direction of the slider 12 and the detection direction of the optical probe 10 are both perpendicular to the side wall plane where the detection hole 17-3 is located. The moving plane (XZ plane) of the moving platform 9 is parallel to the side wall plane where the detection hole 17-3 is located. The moving platform 9, slider 12, set screw 11 and sensor 18 can realize the functions of high-temperature rapid moving scanning and detection laser automatic focusing. Specifically, the stroke of the slider 12 is 300mm~500mm; the left and right stroke of the moving platform 9 is 80mm~120mm; and the lifting height (up and down direction) of the moving platform 9 is 0~120mm.

[0039] The signal acquisition and control module includes a display screen 15-1 and a signal acquisition and control analysis system 15-2. The signal acquisition and control analysis system includes a high-speed acquisition card and a high-performance processor. The signal acquisition and control analysis system 15-2 is connected to the laser 1, the dual-wave mixing interferometer 14, the sensor 18, the lead screw mechanism 5, and the moving platform drive mechanism, respectively. The acquisition card and the processor control the moving platform 9 to move in the left-right direction (X direction) and the up-down direction (Z direction), and to acquire and process laser excitation of different energies and ultrasonic signals. The analysis system realizes the detection and imaging functions of surface and internal defects of the metal component 16 under test.

[0040] This invention also provides a method for laser ultrasonic defect detection of hot metal components, using the aforementioned laser ultrasonic defect detection device for hot metal components. The method includes the following steps:

[0041] S1. Start the signal acquisition and control analysis system 15-2. According to the focal length of the optical probe 10, control the moving slider 12 to move away from the high temperature heating furnace 17-1. Open the furnace door of the high temperature heating furnace 17-1 and fix the metal component 16 to be tested on the support seat 17-2 in the high temperature heating furnace 17-1 by the clamp.

[0042] S2. Close the furnace door of the high-temperature heating furnace 17-1. Move the slider 12 through the signal acquisition and control analysis system 15-2, and observe the detection laser receiving signal through the display screen 15-1. Adjust the position of the slider 12 to obtain the optimal detection laser sensitivity, and realize the automatic focusing function of the high-temperature detection laser. If the surface defects of the metal component 16 to be tested are to be detected, adjust the reflector 6 to separate the excitation laser spot and the detection laser spot. Figure 2 As shown; if internal defects in the metal component 16 to be tested are to be detected, the reflector 6 is adjusted to make the excitation laser spot coincide with the detection laser spot, as shown. Figure 3 As shown.

[0043] S3. Next, start the high-temperature heating furnace 17-1. The high-temperature heating furnace 17-1 heats the metal component 16 to be tested according to the set program. The heating range of the high-temperature heating furnace 17-1 is 0℃~1350℃.

[0044] S4. Set the control parameters for laser 1, dual-wavelength mixer interferometer 14, and moving platform 9; the excitation laser wavelength of laser 1 is 532nm; the detection laser wavelength is 1064nm; set the moving step size and total number of moves of moving platform 9 according to the appearance size and accuracy requirements of the metal component 16 to be tested. The moving step size ranges from 0.01mm to 10mm, and the scanning range of the metal component to be tested is 0mm. 2 ~25mm 2 .

[0045] S5, activate laser 1, dual-wavelength mixer interferometer 14, moving platform 9, and optical probe 10. Moving platform 9, according to... Figure 2 and Figure 3 The scanning path shown is moved, the laser 1 excites the laser beam to generate ultrasonic waves on the surface of the metal component 16 to be tested, the optical probe 10 excites the detection laser and receives the reflected laser input to the dual-wave mixing interferometer 14, the dual-wave mixing interferometer 14 obtains the laser ultrasonic scanning signal of the metal component 16 to be tested and transmits it to the acquisition card and processor.

[0046] S6. Based on the synthetic aperture focusing imaging algorithm, the ultrasonic scanning signal is processed to obtain the surface and internal defect images of the metal component 16 under test; the signal acquisition and control analysis system 15-2, according to... Figure 4The detection principle shown is analyzed and imaged; if the internal defects of the metal component 16 to be tested are detected and synthetic aperture focusing imaging is performed, the signal acquisition and control analysis system 15-2 is based on the following... Figure 5 The detection principle shown is analyzed and imaged through the emission propagation path. and reflection path After obtaining the total propagation time, the amplitude of each scan signal is obtained for imaging, and an image of the surface and internal defects of the metal component 16 under test is obtained and displayed on the display screen 15-1.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A laser ultrasonic apparatus for the detection of defects in a hot metal component, characterised in that, The utility model provides a kind of high-temperature heating module, laser detection module, laser excitation module, mobile scanning automatic focusing module and signal acquisition and control module including, the high-temperature heating module includes high-temperature heating furnace (17-1), support seat (17-2) is equipped in the high-temperature heating furnace, detection hole (17-3) is set on the lateral wall of high-temperature heating furnace (17-1);The laser detection module includes double-wave mixing interferometer (14) and optical probe (10), and the double-wave mixing interferometer (14) is connected with the optical probe (10);The laser excitation module includes laser (1), beam expander (3), reflector (6), plano-convex mirror (7) and dichroic mirror (8), and the beam expander (3) and the reflector (6) are sequentially arranged in the light path front of laser (1), and the plano-convex mirror (7) is arranged in the light direction of reflector (6), and the dichroic mirror (8) is arranged in the light direction of plano-convex mirror (7) and optical probe (10), and the dichroic light of dichroic mirror (8) is opposite to the detection hole (17-3) and is detected to the metal component (16) on support seat (17-2);The mobile scanning automatic focusing module includes two parallelly arranged guide rails (2), and one end of the two guide rails (2) is respectively provided with sensor (18), and the two guide rails (2) are all provided with sliding block (12) and screw rod mechanism (5), and the two sliding blocks (12) are respectively connected support plate (4), and the support plate (4) is provided with mobile platform (9) and mobile platform drive mechanism;The signal acquisition and control module includes display screen (15-1) and signal acquisition and control analysis system (15-2), and the signal acquisition and control analysis system (15-2) is connected with laser (1), double-wave mixing interferometer (14), sensor (18), screw rod mechanism (5) and mobile platform drive mechanism respectively.

2. The apparatus of claim 1, wherein, The aperture of the detection hole (17-3) is 30mm~50mm, the detection hole (17-3) is provided with sapphire heat-resistant glass with high light transmittance, and the both ends of the sapphire heat-resistant glass are coated with an anti-reflection coating.

3. The apparatus of claim 1, wherein, The laser (1), the beam expander (3), the reflector (6), the plano-convex mirror (7), the dichroic mirror (8) and the optical probe (10) are fixed on the mobile platform (9) by bolts, and the input end of the optical probe (10) is connected to a cooling box.

4. The apparatus of claim 1, wherein, The screw rod mechanism (5) includes a lead screw and a first servo motor, and the sliding block (12) can slide along the lead screw in the front and back directions under the drive of the motor.

5. The apparatus of claim 4, wherein, The mobile platform drive mechanism includes a second servo motor for driving the mobile platform (9) to move in the left and right directions and a third servo motor for driving the mobile platform (9) to move up and down. The moving direction of the sliding block (12) and the detection direction of the optical probe (10) are both perpendicular to the side wall plane where the detection hole (17-3) is located, and the moving plane of the mobile platform (9) is parallel to the side wall plane where the detection hole (17-3) is located.

6. The apparatus of claim 4, wherein, The stroke of the slider (12) is 300mm-500mm; the stroke of the moving platform (9) in the left-right direction is 80mm-120mm, and the lifting height of the moving platform (9) is 0-120mm.

7. The apparatus of claim 1, wherein, After the two sliders (12) reach the specified focal length position, the clamping screw (11) is fixed with the guide rail (2) by tightening the clamping screw (11) on the side of the slider (12).

8. A method of laser ultrasonic defect detection of a hot metal component, characterized in that The laser ultrasonic defect detection device for hot metal components comprises a laser ultrasonic signal acquisition and control analysis system (15-2), a high-temperature heating furnace (17-1), a moving slider (12), a moving platform (9), a double-wave mixing interferometer (14), a laser (1), and an optical probe (10). S1, start the signal acquisition and control analysis system (15-2), control the moving slider (12) to move away from the high-temperature heating furnace (17-1) according to the focal length of the optical probe (10); open the door of the high-temperature heating furnace (17-1), and fix the to-be-detected metal component (16) on the support seat (17-2) in the high-temperature heating furnace (17-1) by a clamp; S2, close the door of the high-temperature heating furnace (17-1), move the slider (12) by the signal acquisition and control analysis system (15-2), and observe the detection laser receiving signal through the display screen (15-1) to adjust the position of the slider (12) to obtain the best detection laser sensitivity; S3, then, start the high-temperature heating furnace (17-1), and the high-temperature heating furnace (17-1) heats the to-be-detected metal component (16) according to a set program; S4, set various control parameters of the laser (1), the double-wave mixing interferometer (14), and the moving platform (9); S5, start the laser (1), the double-wave mixing interferometer (14), the moving platform (9), and the optical probe (10) to obtain the laser ultrasonic scanning signal of the to-be-detected metal component (16); S6, process the ultrasonic scanning signal based on a synthetic aperture focusing imaging algorithm to finally obtain the imaging diagram of the surface and internal defects of the to-be-detected metal component (16).

9. The method of laser ultrasonic defect detection of a hot metal component according to claim 8, characterized in that, The moving step length of the moving platform (9) ranges from 0.01 mm to 10 mm, and the scanning range of the metal component (16) to be measured ranges from 0 mm 2 ~25 mm 2 .

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