Ultrasonic detection brake disc flaw detection device and method

Abstract

The flaw detection device comprises a rotary objective table, a detection cavity is in sealed butt joint with the rotary objective table, and a high-pressure gas medium with acoustic impedance higher than that of air can be injected into the detection cavity; a magnetic suspension acoustic lens dynamic focusing array module is mounted at the top of the detection chamber, a sound wave radiation surface of the magnetic suspension acoustic lens dynamic focusing array module is vertically downward and directly faces the rotary objective table, and a physical emission aperture of the magnetic suspension acoustic lens dynamic focusing array module has dynamic reconstruction capability; the magnetic suspension acoustic lens dynamic focusing array module is electrically connected with a multi-channel coherent excitation and data acquisition module, and a global optical interference measurement and position feedback module is mounted on the side wall of the magnetic suspension acoustic lens dynamic focusing array module. The invention solves the problems of low detection efficiency and low precision due to the adoption of probe mechanical point-by-point scanning in the conventional brake disc ultrasonic flaw detection.

Description

Technical Field

[0001] This invention relates to the field of brake disc flaw detection technology, and in particular to an ultrasonic brake disc flaw detection device and method. Background Technology

[0002] Brake discs are a core component of automotive and rail transit braking systems, and their quality directly determines operational safety. Brake discs are prone to latent defects such as cracks and porosity during casting, machining, and service. These defects can continue to expand under load, leading to fracture failure. Therefore, comprehensive inspection through non-destructive testing is necessary. Ultrasonic testing has become the mainstream method due to its deep detection and high sensitivity. Currently, it mainly relies on mechanical point-by-point scanning technology, where a mechanical mechanism drives the probe to move along a preset trajectory. Defect signals are captured by ultrasonic wave reflection, and the detection is completed with a coupling device and data unit. Water immersion is commonly used to fill the gap between the probe and the workpiece to reduce ultrasonic energy loss.

[0003] While this technology is widely used, it struggles to adapt to the complex structure of brake discs and the demands for high-precision inspection, exhibiting numerous bottlenecks. In terms of efficiency, the probe's physical movement speed is limited, and the trajectory must be adjusted to avoid ventilation holes and heat dissipation slots, failing to meet the needs of mass production. Regarding accuracy, the probe's focusing parameters and aperture are fixed, and long-term operation of the mechanical mechanism can easily lead to positioning deviations, resulting in missed detection of minute defects and insufficient quantitative accuracy. In terms of stability, the water immersion method is prone to workpiece corrosion and equipment jamming, while the dry scanning method suffers from signal attenuation due to the air medium, and single-track scanning struggles to capture the three-dimensional features of defects, resulting in weak qualitative capabilities and highly dependent on the operator's skill level.

[0004] In summary, existing mechanical point-by-point scanning technology with probes has limitations in efficiency, accuracy, stability, and defect identification, and cannot meet the high-efficiency and high-precision requirements of modern brake disc production and maintenance. Therefore, we propose an ultrasonic testing device and method for brake disc flaw detection. Summary of the Invention

[0005] To address the issues of low efficiency and low accuracy in existing ultrasonic testing of brake discs, which uses mechanical point-by-point scanning with probes, the present invention aims to provide an ultrasonic testing device and method for brake discs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an ultrasonic testing device for brake disc flaw detection, comprising a rotating stage, a testing chamber sealed and connected to the rotating stage, the chamber of which can be injected with a high-pressure gas medium with an acoustic impedance higher than that of air; a magnetically levitated acoustic lens dynamic focusing array module is installed on the top of the testing chamber, its acoustic radiation surface is vertically downward facing the rotating stage, and the physical emission aperture of the magnetically levitated acoustic lens dynamic focusing array module has dynamic reconstruction capability; the magnetically levitated acoustic lens dynamic focusing array module is electrically connected to a multi-channel coherent excitation and data acquisition module, a global optical interferometry and position feedback module is installed on the side wall of the magnetically levitated acoustic lens dynamic focusing array module, the magnetically levitated acoustic lens dynamic focusing array module includes several magnetically levitated focusing units arranged in an array, a spherical levitation body is set in the magnetically levitated focusing unit, and an optical mark for optical tracking is formed on the surface of the spherical levitation body; The global optical interferometry and position feedback module includes several CMOS cameras. The optical axes of these CMOS cameras converge in the detection area below the magnetically levitated acoustic lens dynamic focusing array module to capture images of the optical markers. It also includes a central control and imaging processing system, which is electrically connected to the rotating stage, the magnetically levitated acoustic lens dynamic focusing array module, the multi-channel coherent excitation and data acquisition module, and the global optical interferometry and position feedback module.

[0007] Preferably, the rotating stage includes a support base, a fixed plate is fixedly connected to the top of the support base, a motor is fixedly installed at the bottom of the fixed plate, the output shaft of the motor rotates vertically upward through the top surface of the fixed plate, and the top of the output shaft is fixedly connected to the bottom of the rotating stage.

[0008] Preferably, a control valve communicating with the interior of the detection chamber is installed on the side wall of the detection chamber, and the control valve is connected to an air injection pump for injecting a high-pressure gas medium with an acoustic impedance higher than that of air; a pressure sensor is fixedly and sealed through the side wall of the detection chamber, and its monitoring end is located inside the detection chamber; a linear motor that drives in the vertical direction is fixedly installed on the top surface of the fixed plate, and the side wall of the linear motor drive table is fixedly connected to the outer wall of the detection chamber.

[0009] Preferably, the magnetic levitation acoustic lens dynamic focusing array module includes a housing with an opening at the bottom, a fixing plate fixedly connected to the inner wall of the housing, and the bottom port of the housing being fixedly connected to the top port of the detection chamber. The magnetic levitation focusing unit includes a cylindrical body with a flexible impact membrane fixedly sealed at the bottom port. Two gradient coils, spaced vertically, are fixedly sleeved on the outer wall of the cylindrical body. A square shell is fixedly inserted through the outer wall of the two gradient coils on the cylindrical body. Four saddle-shaped coils arranged in a ring array are fixedly installed in the square shell. The openings of the four saddle-shaped coils are perpendicular to the axis of the cylindrical body, and the openings are opposite each other in pairs. The two pairs of coils are orthogonally arranged. A transparent cap is fixedly sealed and connected to the top of the cylindrical body. A spherical levitation body is movably disposed inside the cylindrical body. A square hole is opened on the fixed plate, and the inner wall of the square hole is fixedly connected to the outer wall of the square shell. The inside of the cylindrical body is evacuated.

[0010] Preferably, the spherical suspension has a multi-layered spherical structure from the inside out: The innermost layer is a spherical samarium cobalt permanent magnet, which is radially hexapole magnetized; the middle layer is a high-density uniform coating of tungsten carbide; the outermost layer is a gold reflective film prepared sequentially and a micron-scale grating coding pattern etched by laser, which together constitute an optical mark.

[0011] Preferably, the CMOS camera is sealed and fixedly embedded in the inner wall of the housing. The optical axis of the CMOS camera is tilted and observes the spherical levitation body and its surface optical marks without obstruction through the transparent cap. The global optical interferometry and position feedback module calculates and outputs the three-dimensional spatial coordinates and vibration phase of each spherical levitation body in real time through image processing.

[0012] Preferably, two gradient coils form an axial gradient coil pair, which generates a vertical magnetic field gradient in the cylindrical axial region when a reverse current is applied, to provide the Z-axis levitation force and excitation force of the spherical suspension body; four saddle-shaped coils form two sets of orthogonal radial gradient coil pairs, which can generate a transverse magnetic field gradient by independently controlling the current, to provide the X and Y-axis positioning force and electrostatic force of the spherical suspension body.

[0013] Preferably, the aperture dynamic reconfiguration capability of the magnetic levitation acoustic lens dynamic focusing array module is specifically implemented as follows: The central control and imaging processing system outputs a controllable static bias current to the saddle-shaped coil; The static bias current generates a stable transverse static magnetic field gradient in its corresponding saddle coil pair, thereby applying a continuous horizontal electrostatic force to the spherical suspension. Driven by the horizontal electrostatic force, the spherical levitation body is displaced in the horizontal plane and is precisely moved and locked at the preset target horizontal coordinates through real-time monitoring and closed-loop control of the global optical interferometry and position feedback module. By independently controlling the above process of each magnetic levitation focusing unit in the array, the dynamic reconstruction of the physical aperture distribution of the entire array can be achieved.

[0014] Preferably, the aperture dynamic reconfiguration is specifically used to switch the array between two operating modes: Large-area scanning mode: By controlling the spherical levitation bodies of the outer array units to move outward, the physical aperture of the array is expanded to obtain high spatial resolution for rapid surveying; Local fine-focusing mode: By controlling the spherical levitation bodies of relevant units to converge towards the center, the physical aperture of the array is reduced and moved above the suspicious area to obtain a long depth of field and a high local signal-to-noise ratio for fine re-inspection.

[0015] A flaw detection method for an ultrasonic brake disc flaw detection device includes the following steps: S1. Loading and Initialization: Place the brake disc on the rotating platform and control the descent and docking of the testing chamber; fill the testing chamber with high-pressure gas to the set pressure. ; Activate all magnetic levitation focusing units to stably levitate each spherical levitation body at its initial zero position; Activate the global optical interferometry and position feedback module to calibrate the initial pose matrix of each spherical levitation body. ;in, For the index of the magnetic levitation focusing unit, , The total number of units; , They represent the first The initial three-dimensional spatial coordinates of a spherical suspended body These represent its initial rotation angles around the X, Y, and Z axes, respectively; S2. Dynamic Phase Compensation Model: At any time The system acquires the first [data] through a CMOS camera. Real-time pose of a spherical suspended body ; Calculate its offset relative to the position of the ideal sound source model. ,in , , Similarly; the attitude angle deviation is ; Calculate the real-time dynamic phase compensation required for this unit. Its model is: in, The center frequency of the ultrasonic emission. To detect the velocity of sound in the high-pressure gas medium within the chamber under the current temperature and pressure conditions, The azimuth angle of the current electron scanning focal point in the horizontal plane is taken as the reference of the X-axis of the array plane coordinate system; The acoustic path coupling coefficient is the coefficient between horizontal and axial displacements. This represents the phase disturbance coefficient caused by attitude angle deviation. The magnitude of the attitude angle deviation vector; S3. Aperture Reconstruction Control Model: When it is necessary to switch the array physical aperture from mode A to mode B, for each cell that needs to be moved... , For the subset of indexes of the units that need to be moved: Determine the horizontal target coordinates based on the target aperture distribution. ; Calculate the required level of power The force and the target displacement vector Proportional and introduces a damping term, For unit The current horizontal coordinates of the spherical suspended body; the specific model is as follows: ,in This is a proportionality coefficient matrix. The differential coefficient matrix, The first derivative of the displacement vector with respect to time is the velocity. Based on the force-current conversion model The static bias current vector to be applied to the corresponding radial gradient coil pair - saddle coil 317 is calculated. ;in, The force constant matrix is ​​determined by the coil's geometric parameters and the magnetic moment of the levitation body. These are the current vectors of two orthogonal radial coils; Iterative adjustments are made based on feedback loop from the CMOS camera. until the spherical suspension stabilizes. Permissible error range Inside; S4. Coherent Synthesis Focusing and Scanning: For each focus on the scan path , The coordinates of the focus in the detection coordinate system: Calculate the first Unit to focus Geometric path length: Thus, the theoretical propagation time is obtained. ; Generate the first Total excitation phase command for each unit: ,in For all units to focus The minimum value in the theoretical propagation time; The multi-channel coherent excitation and data acquisition module is based on Generate synchronous excitation pulses to drive all magnetic levitation focusing units to emit ultrasonic waves; Simultaneous acquisition of echo signals from all units acting as receivers ,in For the transmitting unit index ( ), For the receiving unit index ( This forms a full matrix data slice under that focus; S5. Full-focus imaging and defect inversion model: For the complete full-matrix dataset acquired, apply the full focusing algorithm to calculate the value of each voxel in the imaging region. Synthetic amplitude : ;in, and These are the first steps after dynamic compensation via step S2. The first transmitting unit and the first The position data of each receiving unit is used to calculate the distance from the transmitting unit to the voxel. Then from voxels The precise two-way propagation time to the receiving unit; Three-dimensional complex image data volume Input a pre-trained deep learning defect recognition network; this network employs an encoder-decoder structure, where the encoder's first... Feature mapping of layers The calculation is as follows: ,in , For the first The weight tensor and bias vector of a 3D convolutional kernel. This indicates a batch normalization operation. This represents a 3D convolution operation. It is a linear rectified activation function. These are the input features for the previous layer; The network's output layer produces two results in parallel: a defect probability map. ,in It is the Sigmoid activation function. , For the output layer weights and biases; and the defect attribute tensor , It includes the defect type classification label, equivalent size, and detection confidence level for each spatial location; S6. Adaptive Detection Decision and Report Generation: Based on the preliminary results of the first round of global scanning imaging, the system uses the defect probability map... The probability value exceeds the threshold Extract a set of suspicious areas from the given region. , Indexing suspicious areas; For each The system automatically makes a decision, calling the S3 aperture reconfiguration control model to switch the array to the desired configuration. Optimized local fine-focus mode; Under the reconstructed new aperture, A second round of high-resolution scanning was performed, and local fine images were generated using the S5 imaging and inversion model; By integrating global and local scan data, a comprehensive inspection report is generated, which includes the three-dimensional location, quantification, and classification results of defects.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: 1. This invention utilizes a magnetically levitated acoustic lens dynamic focusing array module and its electronic scanning and aperture dynamic reconstruction capabilities, combined with the single-axis precision rotation of the rotating stage, to achieve a collaborative scanning strategy that prioritizes electronic scanning and supplements mechanical motion. Furthermore, through an adaptive detection process that first performs rapid general surveys with large apertures and then performs detailed local surveys with small apertures, this invention completely breaks through the efficiency bottleneck of traditional probe mechanical point-by-point scanning, greatly improving detection efficiency and equipment utilization.

[0017] 2. This invention integrates a global optical interferometry and position feedback system to perform real-time nanoscale six-degree-of-freedom pose monitoring on each spherical suspension body. Based on this data, dynamic phase compensation is performed on the multi-channel coherent excitation signal, ensuring stable and accurate coherent synthesis and focusing of non-contact air-coupled ultrasound in the air. This improves the detection resolution to the subwavelength level and can effectively detect extremely small microcracks in the near-surface blind zone. At the same time, it completely eliminates the signal fluctuations caused by contact coupling, making the reliability and repeatability of the detection results extremely high.

[0018] 3. This invention deeply integrates reconfigurable physical aperture, real-time feedback-based closed-loop control, full-matrix data acquisition, and intelligent analysis, enabling the device to possess self-sensing, decision-making, and optimization capabilities. It achieves a paradigm shift from pre-programmed scanning to intelligent adaptive detection, allowing a single device to flexibly adapt to brake discs of different specifications and testing requirements. Furthermore, it can automatically complete defect identification, classification, three-dimensional quantification, and report generation, significantly reducing reliance on operator experience. This provides a revolutionary solution for online full inspection, high-reliability quality assurance, and predictive maintenance of core industrial components. Attached Figure Description

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 This is a cross-sectional structural schematic diagram of the present invention; Figure 2 This is a cross-sectional structural schematic diagram of the magnetic levitation focusing unit of the present invention; Figure 3 This is a schematic diagram of the saddle-shaped coil arrangement of the present invention.

[0020] In the diagram: 1. Rotating stage; 101. Support base; 102. Fixed disk; 103. Motor; 2. Detection chamber; 201. Control valve; 202. Linear motor; 3. Magnetic levitation acoustic lens dynamic focusing array module; 31. Magnetic levitation focusing unit; 311. Spherical levitation body; 313. Cylinder; 314. Flexible impact diaphragm; 315. Gradient coil; 316. Square shell; 317. Saddle-shaped coil; 318. Transparent cap; 32. Outer shell; 33. Fixing plate; 501. CMOS camera. Detailed Implementation

[0021] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0022] Please see Figures 1 to 3 It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0023] This invention provides a technical solution: an ultrasonic testing device for brake disc flaw detection, mainly comprising a rotating stage 1, a testing chamber 2, a magnetically levitated acoustic lens dynamic focusing array module 3, a multi-channel coherent excitation and data acquisition module, a global optical interferometry and position feedback module, and a central control and imaging processing system.

[0024] During testing, the brake disc under test is fixed on the rotating stage 1, and the testing chamber 2 descends and seals with the rotating stage 1, forming a sealed space. High-pressure gas is then introduced into the testing chamber 2. A magnetically levitated acoustic lens dynamic focusing array module 3, located at the top of the chamber, acts as an intelligent sound source, emitting ultrasonic waves downwards. This module possesses dynamic reconstruction capabilities for the physical emission aperture, allowing it to adaptively change the testing mode. Through the module's own electronic scanning focusing and the precise rotation of the rotating stage 1, combined with nanometer-level real-time pose feedback provided by the global optical interferometry and position feedback module, high-speed, full-range, and high-precision non-contact ultrasonic scanning of the brake disc is achieved. The central control and imaging processing system coordinates the entire process, completing the entire workflow from signal excitation and data acquisition to 3D imaging and intelligent recognition.

[0025] The rotating stage 1 includes a support base 101, a fixed disk 102, and a motor 103. The support base 101 is a rigid base, and the fixed disk 102 is fixed to the top of the support base 101 by bolts. The motor 103 is preferably a high-precision servo motor, which is installed upside down at the bottom of the fixed disk 102. The output shaft of the motor 103 is vertically upward, passes through a pre-set hole on the top surface of the fixed disk 102 equipped with a rotary sealed bearing, and is fixedly connected to the bottom of the rotating stage 1, thereby driving the disk to rotate while ensuring a seal.

[0026] The detection chamber 2 is a sealed cover with an open bottom. The top surface of the fixed plate 102 is machined with an annular sealing groove and fitted with a sealing ring. The base of a linear motor 202 is fixed to the fixed plate 102, and the sliding table of the linear motor 202 is rigidly connected to the outer wall of the detection chamber 2 via a connecting plate. During operation, the linear motor 202 drives the detection chamber 2 to descend, causing its bottom open end face to press against the sealing ring of the fixed plate 102, forming a high-pressure sealed connection. A control valve 201 and a pressure sensor are installed on the side wall of the detection chamber 2. The control valve 201 is connected to an external air injection pump for filling the chamber with high-pressure gas media such as helium or sulfur hexafluoride.

[0027] The magnetic levitation acoustic lens dynamic focusing array module 3 includes a housing 32 and a mounting plate 33. The bottom of the housing 32 is open and is fixedly connected to the top of the detection chamber 2 via a flange. The mounting plate 33 is fixed inside the housing 32 as a mounting base.

[0028] Multiple magnetic levitation focusing units 31 are mounted in an array on a fixed plate 33. The core component of each magnetic levitation focusing unit 31 is: Cylinder 313: An alumina ceramic cylinder, with a flexible impact diaphragm 314 brazed to its bottom by active metal. The flexible impact diaphragm 314 is made of beryllium copper alloy and has a thickness of approximately 20-50 micrometers. The interior of cylinder 313 is evacuated to a high vacuum and sealed. When the detection chamber 2 is filled with high-pressure gas, the gas pressure acting on the outside of the flexible impact diaphragm 314 increases. Because the inside of the diaphragm is under vacuum, the external pressure causes the flexible impact diaphragm 314 to undergo a small, controllable elastic deformation and stabilize at a new mechanical equilibrium position. This design ensures that the flexible impact diaphragm 314 maintains structural stability under high pressure without affecting its high-frequency vibration characteristics.

[0029] Spherical levitation body 311: Located at the center of the vacuum cavity inside the cylinder 313. It is a multi-layered composite sphere: the core is a radially hexagonally magnetized samarium cobalt permanent magnet sphere; the middle layer is a high-density tungsten carbide coating deposited by chemical vapor deposition; and the outer layer is an optical marking layer coated with a gold reflective film and etched with a micron-level grating coding pattern.

[0030] Three-dimensional dynamic electromagnetic coil assembly: sleeved on the outside of the cylinder 313. It includes a pair of gradient coils 315 spaced vertically and coaxially surrounding each other, and a square shell 316. Four saddle-shaped coils 317 are fixed in a ring array inside the square shell 316, with the openings of the four saddle-shaped coils 317 facing each other in pairs and the two sets being orthogonal.

[0031] Transparent cap 318: Made of sapphire or optical glass, it is sealed to the top of the cylinder 313 with vacuum adhesive to form an optical observation window.

[0032] The square housing 316 passes through the corresponding square hole on the fixing plate 33 and is fixed thereto, thereby realizing the installation of the magnetic levitation focusing unit 31. The lower surfaces of the flexible impact diaphragm 314 of all magnetic levitation focusing units 31 are coplanar, forming a flat sound wave radiation surface.

[0033] The CMOS camera 501 of the global optical interferometry and position feedback module is directly and sealed within the inner wall of the housing 32 of the magnetic levitation acoustic lens dynamic focusing array module 3. The optical axis of the CMOS camera 501 is tilted downwards, aligned with the transparent cap 318. The optical axis passes through the transparent cap 318, allowing unobstructed observation of the optical marks on the surface of the spherical suspended body 311 inside the cylinder 313. The system processes the captured images, calculates and outputs the precise three-dimensional spatial coordinates and vibration phase of each spherical suspended body 311 in real time, and feeds the data back to the central control and imaging processing system in real time.

[0034] The aperture dynamic reconfiguration capability of the magnetic levitation acoustic lens dynamic focusing array module 3 is achieved as follows: Two gradient coils 315 form an axial gradient coil pair, used to provide levitation and driving force in the vertical Z direction. Four saddle-shaped coils 317 form two sets of orthogonal radial gradient coil pairs, used to provide control force in the horizontal X and Y directions.

[0035] When the physical aperture of the array needs to be changed, the central control and imaging processing system outputs a static bias current to the radial gradient coil pair of the designated magnetic levitation focusing unit 31, namely a specific pair of saddle-shaped coils 317. This current generates a stable transverse static magnetic field gradient, thereby applying a continuous horizontal electrostatic force to the spherical levitation body 311. Driven by this electrostatic force, the spherical levitation body 311 moves in the horizontal plane. The CMOS camera 501 monitors its position in real time, and the central control and imaging processing system performs closed-loop control based on feedback until the spherical levitation body 311 is precisely locked at the preset new coordinates.

[0036] By independently controlling the aforementioned processes of multiple units in the array, the static horizontal positions of all spherical levitation bodies 311 can be redistributed according to instructions, thereby achieving dynamic switching of the physical aperture shape of the entire array. For example, when switching to a wide-range scanning mode, the spherical levitation bodies 311 of the peripheral units move outward to expand the aperture and improve scanning resolution; when switching to a local fine focusing mode, the spherical levitation bodies 311 of the relevant units converge towards the center and move above the suspicious area, reducing the aperture to obtain a longer depth of focus and a higher local signal-to-noise ratio.

[0037] With a defined physical aperture, the device performs dynamic focusing scanning: For each preset scanning focus coordinate, the central control and imaging processing system calculates the ideal time delay of sound wave emission from each unit based on these coordinates and the precise position of each spherical levitation body 311 as fed back in real time by the global optical interferometry and position feedback module. Simultaneously, the system calculates the sound path error caused by the slight deviation between the actual position of the spherical levitation body 311 and the ideal model, and performs real-time phase compensation for this error.

[0038] The multi-channel coherent excitation and data acquisition module outputs synchronized high-frequency current pulses to the gradient coils 315 of each magnetic levitation focusing unit 31 based on the final excitation signal generated by the central system, which already includes compensation. This current drives the spherical levitation body 311 to accelerate vertically with precise timing, impacting the flexible impact membrane 314 and exciting ultrasonic waves. The sound waves excited by all units achieve coherent synthesis in the air at the preset focal point, resulting in enhanced energy. Inertial-free electronic scanning can be achieved by rapidly changing the focal point coordinates electronically.

[0039] This electronic scanning, in conjunction with the precise indexing rotation of the rotating stage 1, ultimately completes a full-coverage inspection of the entire three-dimensional volume of the brake disc.

[0040] To further explain, the multi-channel coherent excitation and data acquisition module is configured to output independent, synchronous, and precisely phase-adjustable high-voltage excitation signals to each magnetic levitation focusing unit 31 in the magnetic levitation acoustic lens dynamic focusing array module 3 under the command of the central control and imaging processing system. This drives all spherical levitation bodies 311 to work together to complete dynamic focusing emission or aperture reconstruction displacement. At the same time, the system is configured to acquire the ultrasonic echo signals sensed by all magnetic levitation focusing units 31 as receivers in parallel after each excitation event, using a strictly synchronized clock reference. This completes the acquisition and buffering of the entire matrix data and uploads it in real time through a high-speed data interface. The system has a complete transmit / receive isolation mechanism to ensure that high-power transmission and weak signal acquisition do not interfere with each other.

[0041] To further explain, the global optical interferometry and position feedback module is configured to perform non-contact, high-bandwidth real-time visual monitoring of each spherical levitation body 311 in the magnetic levitation acoustic lens dynamic focusing array module 3. The system synchronously captures images of optical marks on the surface of each spherical levitation body 311 through its integrated multiple CMOS cameras 501, and uses image processing algorithms to calculate the six-degree-of-freedom pose data of each spherical levitation body 311 in real time, including three-dimensional spatial coordinates and three-dimensional attitude angles. The system is further configured to continuously feed back these high-precision real-time pose data to the central control and imaging processing system, thereby providing the displacement information required for the dynamic focusing function to achieve real-time acoustic wave emission phase compensation, and providing the position feedback required for the aperture reconstruction function to achieve closed-loop control of the horizontal position of the spherical levitation body 311.

[0042] A flaw detection method for an ultrasonic brake disc flaw detection device includes the following steps: S1. Loading and Initialization: Place the brake disc on the rotating platform 1 and control the detection chamber 2 to descend and dock; fill the detection chamber 2 with high-pressure gas to the set pressure. ; Activate all magnetic levitation focusing units 31 to stably levitate each spherical levitation body 311 at its initial zero position; Activate the global optical interferometry and position feedback module to calibrate the initial pose matrix of each spherical levitation body 311. ;in, For the index of the magnetic levitation focusing unit, , The total number of units; , They represent the first The initial three-dimensional spatial coordinates of a spherical suspended body These represent its initial rotation angles around the X, Y, and Z axes, respectively; S2. Dynamic Phase Compensation Model: At any time The system acquires the first image through the CMOS camera 501. Real-time pose of the spherical levitation body 311 ; Calculate its offset relative to the position of the ideal sound source model. ,in , , Similarly; the attitude angle deviation is ; Calculate the real-time dynamic phase compensation required for this unit. Its model is: in, The center frequency of the ultrasonic emission. To detect the velocity of sound in the high-pressure gas medium inside chamber (2) under the current temperature and pressure, The azimuth angle of the current electron scanning focal point in the horizontal plane is taken as the reference of the X-axis of the array plane coordinate system; The acoustic path coupling coefficient is the coefficient between horizontal and axial displacements. This represents the phase disturbance coefficient caused by attitude angle deviation. The magnitude of the attitude angle deviation vector; S3. Aperture Reconstruction Control Model: When it is necessary to switch the array physical aperture from mode A to mode B, for each cell that needs to be moved... , For the subset of indexes of the units that need to be moved: Determine the horizontal target coordinates based on the target aperture distribution. ; Calculate the required level of power The force and the target displacement vector Proportional and introduces a damping term, For unit The current horizontal coordinates of the spherical suspended body; the specific model is as follows: ,in This is a proportionality coefficient matrix. The differential coefficient matrix, The first derivative of the displacement vector with respect to time is the velocity. Based on the force-current conversion model The static bias current vector to be applied to the corresponding radial gradient coil pair - saddle coil 317 is calculated. ;in, The force constant matrix is ​​determined by the coil's geometric parameters and the magnetic moment of the levitation body. These are the current vectors of two orthogonal radial coils; Iterative adjustments are made using a closed-loop feedback mechanism via the CMOS camera 501. Until the spherical levitation body 311 stabilizes Permissible error range Inside; S4. Coherent Synthesis Focusing and Scanning: For each focus on the scan path , The coordinates of the focus in the detection coordinate system: Calculate the first Unit to focus Geometric path length: Thus, the theoretical propagation time is obtained. ; Generate the first Total excitation phase command for each unit: ,in For all units to focus The minimum value in the theoretical propagation time; The multi-channel coherent excitation and data acquisition module is based on Generate synchronous excitation pulses to drive all magnetic levitation focusing units (31) to emit ultrasonic waves; Simultaneous acquisition of echo signals from all units acting as receivers ,in For the transmitting unit index ( ), For the receiving unit index ( This forms a full matrix data slice under that focus; S5. Full-focus imaging and defect inversion model: For the complete full-matrix dataset acquired, apply the full focusing algorithm to calculate the value of each voxel in the imaging region. Synthetic amplitude : ;in, and These are the first steps after dynamic compensation via step S2. The first transmitting unit and the first The position data of each receiving unit is used to calculate the distance from the transmitting unit to the voxel. Then from voxels The precise two-way propagation time to the receiving unit; Three-dimensional complex image data volume Input a pre-trained deep learning defect recognition network; this network employs an encoder-decoder structure, where the encoder's first... Feature mapping of layers The calculation is as follows: ,in , For the first The weight tensor and bias vector of a 3D convolutional kernel. This indicates a batch normalization operation. This represents a 3D convolution operation. It is a linear rectified activation function. These are the input features for the previous layer; The network's output layer produces two results in parallel: a defect probability map. ,in It is the Sigmoid activation function. , For the output layer weights and biases; and the defect attribute tensor , It includes the defect type classification label, equivalent size, and detection confidence level for each spatial location; S6. Adaptive Detection Decision and Report Generation: Based on the preliminary results of the first round of global scanning imaging, the system uses the defect probability map... The probability value exceeds the threshold Extract a set of suspicious areas from the given region. , Indexing suspicious areas; For each The system automatically makes a decision, calling the S3 aperture reconfiguration control model to switch the array to the desired configuration. Optimized local fine-focus mode; Under the reconstructed new aperture, A second round of high-resolution scanning was performed, and local fine images were generated using the S5 imaging and inversion model; By integrating global and local scan data, a comprehensive inspection report is generated, which includes the three-dimensional location, quantification, and classification results of defects.

[0043] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An ultrasonic testing device for brake disc flaw detection, comprising a rotating stage (1), characterized in that: The rotating stage (1) is sealed with a detection chamber (2), which can be filled with a high-pressure gas medium with an acoustic impedance higher than that of air; the top of the detection chamber (2) is equipped with a magnetic levitation acoustic lens dynamic focusing array module (3), whose acoustic radiation surface is vertically downward and facing the rotating stage (1), and the physical emission aperture of the magnetic levitation acoustic lens dynamic focusing array module (3) has dynamic reconstruction capability; the magnetic levitation acoustic lens dynamic focusing array module (3) is electrically connected to a multi-channel coherent excitation and data acquisition module, and a global optical interferometry and position feedback module is installed on the side wall of the magnetic levitation acoustic lens dynamic focusing array module (3); the magnetic levitation acoustic lens dynamic focusing array module (3) includes several magnetic levitation focusing units (31) arranged in an array, and a spherical levitation body (311) is provided in the magnetic levitation focusing unit (31), and an optical mark for optical tracking is formed on the surface of the spherical levitation body (311); The global optical interferometry and position feedback module includes several CMOS cameras (501), and the optical axes of the several CMOS cameras (501) converge in the detection area below the magnetic levitation acoustic lens dynamic focusing array module (3) to capture the image of the optical mark; It also includes a central control and imaging processing system, which is electrically connected to the rotating stage (1), the magnetic levitation acoustic lens dynamic focusing array module (3), the multi-channel coherent excitation and data acquisition module, and the global optical interferometry and position feedback module.

2. The ultrasonic testing device for brake disc flaw detection according to claim 1, characterized in that: The rotating platform (1) includes a support base (101), a fixed plate (102) is fixedly connected to the top of the support base (101), and a motor (103) is fixedly installed at the bottom of the fixed plate (102). The output shaft of the motor (103) rotates vertically upward through the top surface of the fixed plate (102), and the top of the output shaft is fixedly connected to the bottom of the rotating platform (1).

3. The ultrasonic testing device for brake disc flaw detection according to claim 2, characterized in that: The side wall of the detection chamber (2) is equipped with a control valve (201) that communicates with its interior, and the control valve (201) is connected to an air injection pump for injecting a high-pressure gas medium with an acoustic impedance higher than that of air; the side wall of the detection chamber (2) is fixedly and sealed with a pressure sensor, and its monitoring end is located inside the detection chamber (2); the top surface of the fixed plate (102) is fixedly installed with a linear motor (202) that drives in the vertical direction, and the side wall of the linear motor (202) transmission table is fixedly connected to the outer wall of the detection chamber (2).

4. The ultrasonic testing device for brake discs according to claim 1, characterized in that: The magnetic levitation acoustic lens dynamic focusing array module (3) includes a shell (32) with an opening at the bottom. A fixing plate (33) is fixedly connected to the inner wall of the shell (32). The bottom port of the shell (32) is fixedly connected to the top port of the detection chamber (2). The magnetic levitation focusing unit (31) includes a cylindrical body (313), the bottom port of which is fixedly sealed with a flexible impact membrane (314). Two gradient coils (315) spaced vertically are fixedly sleeved on the outer wall of the cylindrical body (313). A square shell (316) is fixedly inserted through the outer wall of the cylindrical body (313) between the two gradient coils (315). Four saddle-shaped coils (317) arranged in a ring array are fixedly installed in the square shell (316). The opening direction of the saddle-shaped coil (317) is perpendicular to the axis of the cylinder (313), and the opening directions are opposite to each other, and the two pairs of coils are orthogonally arranged; the top of the cylinder (313) is fixedly sealed with a transparent cap (318), and the spherical suspension body (311) is movably arranged inside the cylinder (313); a square hole is opened on the fixing plate (33), and the inner wall of the square hole is fixedly connected to the outer wall of the square shell (316); the inside of the cylinder (313) is set to be vacuumed.

5. The ultrasonic testing device for brake discs according to claim 1, characterized in that: The spherical suspension (311) has a multi-layered spherical structure from the inside out: The innermost layer is a spherical samarium cobalt permanent magnet, which is radially hexagonally magnetized; the middle layer is a high-density uniform coating of tungsten carbide; the outermost layer is a gold reflective film prepared sequentially and a micron-level grating coding pattern etched by laser, which together constitute the optical mark.

6. The ultrasonic testing device for brake discs according to claim 4, characterized in that: The CMOS camera (501) is sealed and fixedly embedded in the inner wall of the outer shell (32). The optical axis of the CMOS camera (501) is tilted and observes the spherical levitation body (311) and the optical marks on its surface without obstruction through the transparent cap (318). The global optical interferometry and position feedback module calculates and outputs the three-dimensional spatial coordinates and vibration phase of each spherical levitation body (311) in real time through image processing.

7. The ultrasonic testing device for brake disc flaw detection according to claim 4, characterized in that: The two gradient coils (315) form an axial gradient coil pair, which generate a vertical magnetic field gradient in the axial region of the cylinder (313) when a reverse current is applied, which is used to provide the Z-direction levitation force and excitation force of the spherical suspension body (311); The four saddle-shaped coils (317) form two sets of orthogonal radial gradient coil pairs, which can generate a transverse magnetic field gradient by independently controlling the current, to provide the X and Y orientation forces and electrostatic forces of the spherical levitation body (311).

8. The ultrasonic testing device for brake discs according to claim 7, characterized in that: The aperture dynamic reconstruction capability of the magnetic levitation acoustic lens dynamic focusing array module (3) is specifically implemented as follows: The central control and imaging processing system outputs a controllable static bias current to the saddle coil (317); The static bias current generates a stable transverse static magnetic field gradient in its corresponding saddle coil (317) pair, thereby applying a continuous horizontal electrostatic force to the spherical levitation body (311). Driven by the horizontal electrostatic force, the spherical levitation body (311) generates displacement in the horizontal plane, and is precisely moved and locked at the preset target horizontal coordinate through the real-time monitoring and closed-loop control of the global optical interferometry and position feedback module. By independently controlling the above process of each magnetic levitation focusing unit (31) in the array, the dynamic reconstruction of the physical aperture distribution of the entire array is achieved.

9. The ultrasonic testing device for brake disc flaw detection according to claim 8, characterized in that: The aperture dynamic reconstruction is specifically used to switch the array between two operating modes: Large-area scanning mode: By controlling the spherical levitation body (311) of the outer array unit to move outward, the physical aperture of the array is expanded to obtain high spatial resolution for rapid surveying; Local fine focus mode: By controlling the spherical levitation bodies (311) of the relevant units to converge towards the center, the physical aperture of the array is reduced and moved above the suspicious area to obtain a long depth of field and a high local signal-to-noise ratio for fine re-examination.

10. A flaw detection method for an ultrasonic brake disc flaw detection device, characterized in that, The ultrasonic testing device for brake discs according to any one of claims 1-9 comprises the following steps: S1. Loading and Initialization: Place the brake disc on the rotating platform (1) and control the detection chamber (2) to descend and dock; fill the detection chamber (2) with high-pressure gas to the set pressure. ; Activate all magnetic levitation focusing units (31) to make each spherical levitation body (311) stably levitate at the initial zero position; Activate the global optical interferometry and position feedback module to calibrate the initial pose matrix of each spherical levitation body (311). ;in, For the index of the magnetic levitation focusing unit, , The total number of units; , They represent the first The initial three-dimensional spatial coordinates of a spherical suspended body These represent its initial rotation angles around the X, Y, and Z axes, respectively; S2. Dynamic Phase Compensation Model: At any time The system acquires the first image through the CMOS camera (501). Real-time pose of the spherical levitation body (311) ; Calculate its offset relative to the position of the ideal sound source model. ,in , , Similarly; the attitude angle deviation is ; Calculate the real-time dynamic phase compensation required for this unit. Its model is: in, The center frequency of the ultrasonic emission. To detect the velocity of sound in the high-pressure gas medium inside chamber (2) under the current temperature and pressure, The azimuth angle of the current electron scanning focal point in the horizontal plane is taken as the reference of the X-axis of the array plane coordinate system; The acoustic path coupling coefficient is the coefficient between horizontal and axial displacements. This represents the phase disturbance coefficient caused by attitude angle deviation. The magnitude of the attitude angle deviation vector; S3. Aperture Reconstruction Control Model: When it is necessary to switch the array physical aperture from mode A to mode B, for each cell that needs to be moved... , For the subset of indexes of the units that need to be moved: Determine the horizontal target coordinates based on the target aperture distribution. ; Calculate the required level of power The force and the target displacement vector Proportional and introduces a damping term, For unit The current horizontal coordinates of the spherical suspended body; the specific model is as follows: ,in This is a proportionality coefficient matrix. The differential coefficient matrix, The first derivative of the displacement vector with respect to time is the velocity. Based on the force-current conversion model The static bias current vector to be applied to the corresponding radial gradient coil pair - saddle coil 317 is calculated. ;in, The force constant matrix is ​​determined by the coil's geometric parameters and the magnetic moment of the levitation body. These are the current vectors of two orthogonal radial coils; Iterative adjustments are made using a feedback loop from the CMOS camera (501). until the spherical suspension (311) stabilizes. Permissible error range Inside; S4. Coherent Synthesis Focusing and Scanning: For each focus on the scan path , The coordinates of the focus in the detection coordinate system: Calculate the first Unit to focus Geometric path length: Thus, the theoretical propagation time is obtained. ; Generate the first Total excitation phase command for each unit: ,in For all units to focus The minimum value in the theoretical propagation time; The multi-channel coherent excitation and data acquisition module is based on Generate synchronous excitation pulses to drive all magnetic levitation focusing units (31) to emit ultrasonic waves; Simultaneous acquisition of echo signals from all units acting as receivers ,in For the transmitting unit index ( ), For the receiving unit index ( This forms a full matrix data slice under that focus; S5. Full-focus imaging and defect inversion model: For the complete full-matrix dataset acquired, apply the full focusing algorithm to calculate the value of each voxel in the imaging region. Synthetic amplitude : ;in, and These are the first steps after dynamic compensation via step S2. The first transmitting unit and the first The position data of each receiving unit is used to calculate the distance from the transmitting unit to the voxel. Then from voxels The precise two-way propagation time to the receiving unit; Three-dimensional complex image data volume Input a pre-trained deep learning defect recognition network; this network employs an encoder-decoder structure, where the encoder's first... Feature mapping of layers The calculation is as follows: ,in , For the first The weight tensor and bias vector of a 3D convolutional kernel. This indicates a batch normalization operation. This represents a 3D convolution operation. It is a linear rectified activation function. These are the input features for the previous layer; The network's output layer produces two results in parallel: a defect probability map. ,in It is the Sigmoid activation function. , For the output layer weights and biases; and the defect attribute tensor , It includes the defect type classification label, equivalent size, and detection confidence level for each spatial location; S6. Adaptive Detection Decision and Report Generation: Based on the preliminary results of the first round of global scanning imaging, the system uses the defect probability map... The probability value exceeds the threshold Extract a set of suspicious areas from the given region. , Indexing suspicious areas; For each The system automatically makes a decision, calling the S3 aperture reconfiguration control model to switch the array to the desired configuration. Optimized local fine-focus mode; Under the reconstructed new aperture, A second round of high-resolution scanning was performed, and local fine images were generated using the S5 imaging and inversion model; By integrating global and local scan data, a comprehensive inspection report is generated, which includes the three-dimensional location, quantification, and classification results of defects.

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