A device, system and identification method for multi-angle ultrasonic monitoring of solid defects

Abstract

The present invention relates to the technical field of ultrasonic detection, and aims to provide a device for multi-angle ultrasonic monitoring of solid defects. The present invention comprises a rotating block B immersed in oil on a mounting base, and a rotating block A immersed in oil inside the rotating block B. A first stepper motor is arranged on the mounting base, and an output shaft of the first stepper motor is connected to the rotating block B. A second stepper motor is arranged on the rotating block B, and an output shaft of the second stepper motor is connected to the rotating block A. A piezoelectric transducer is also arranged on the rotating block A, and also comprises a control unit and a wireless communication module. The control unit is respectively connected to the first stepper motor, the second stepper motor and the piezoelectric transducer, and the control unit is connected to a user end through the wireless communication module. The present invention has reasonable structure, strong practicality and is suitable for popularization.

Description

Technical Field

[0001] The invention relates to the field of ultrasonic monitoring, and in particular to a device, a system and an identification method for multi-angle ultrasonic monitoring of solid defects. Background Art

[0002] Large steel parts in service are subject to long-term tension, compression and shear forces, and there are repeated changes in stress inside the structural parts. If they are in service for a long time, a series of defects (mainly cracks) will be generated inside the structural parts. These cracks are of great importance to safe production and operation, and seriously threaten the safety of life and property. Traditional defect detection methods are mainly manual operations, using non-destructive testing methods such as eddy current, ultrasound, and X-ray. These methods are relatively simple, and most of them are high-altitude operations. The working conditions are harsh, the on-site preparation work is complicated, and the operation requirements are high. They cannot realize automatic real-time monitoring of key parts, and there is no long-term reliable data for analysis. Even in many large-scale parts monitoring fields, there is no effective and reliable defect monitoring system.

[0003] CN106568841A, a method for monitoring crack defects of heavy-loaded vehicle beams, discloses a method for monitoring crack defects of heavy-loaded vehicle beams, wherein the method selects electromagnetic ultrasonic surface wave probes that meet the sensitivity requirements, and arranges them in a relative or parallel manner at the arc-shaped part of the web of the vehicle beam located at the column shoulder beam; connects the probe cable connector to the electromagnetic ultrasonic data acquisition instrument, performs on-site echo data acquisition, and observes the echo changes, so that the angle position of the probe sound beam where the arc surface structure echo of the web of the vehicle beam just disappears is used as the position of the fixed probe; after the probe is fixed, the waveform data of each probe is regularly collected and saved and compared, and when an obvious abnormal echo is found, a reliable method is adopted to confirm the nature of the echo; for the abnormal echo determined as a crack defect, its expansion status is determined by regularly collecting echo data to determine whether the vehicle beam is cracked. The method overcomes the defects of traditional detection methods, and timely discovers safety hazards through monitoring and forecasting, thereby avoiding huge losses caused by accidents.

[0004] Therefore, a device and detection method are needed that can automatically monitor cracks in key parts of large steel parts in real time, is easy to install, can quickly locate defects, and achieve 360-degree all-round automatic detection. Summary of the invention

[0005] The present invention aims to solve the problems of small scanning range, non-fixed point detection, low automation, inability to perform three-dimensional imaging, and poor working environment in the current crack defect monitoring of key parts of large steel parts. A device and method for three-dimensional scanning ultrasonic monitoring of crack defects of large steel parts are proposed.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a device for multi-angle ultrasonic monitoring of solid defects, comprising a rotating block B immersed in oil on a mounting base, and a rotating block A immersed in oil inside the rotating block B, a first stepper motor is arranged on the mounting base, and the output shaft of the first stepper motor is connected to the rotating block B, a second stepper motor is arranged on the rotating block B, and the output shaft of the second stepper motor is connected to the rotating block A, a piezoelectric transducer is also arranged on the rotating block A, and also comprises a control unit and a wireless communication module, the control unit is respectively connected to the first stepper motor, the second stepper motor and the piezoelectric transducer, and the control unit is connected to the user end through the wireless communication module.

[0007] Preferably, the rotating block A, the rotating block B and the mounting base are all made of the same solid material, wherein lubricating oil is filled between the rotating block A, the rotating block B and the mounting base.

[0008] Preferably, a gear groove is provided on the edge of the rotating block B, and a transmission gear is provided on the output shaft of the first stepper motor, and the transmission gear is meshed with the gear groove.

[0009] Preferably, the first stepper motor is provided with a first angle encoder, and the second stepper motor is provided with a second angle encoder, the first angle encoder obtains the rotation angle data of the rotating block B, and the second angle encoder obtains the rotation angle data of the rotating block A, the first angle encoder and the second angle encoder are both connected to the control unit, the control unit includes a single-chip microcomputer connected to the excitation circuit and the acquisition circuit respectively, the excitation circuit and the acquisition circuit are both connected to the piezoelectric transducer, the acquisition circuit includes an amplifier circuit and an AD acquisition circuit, the single-chip microcomputer is connected to the amplifier circuit through the AD acquisition circuit, and the amplifier circuit is connected to the piezoelectric transducer.

[0010] Preferably, an annular magnet is provided on the mounting base, and the mounting base is connected to the solid to be detected via the annular magnet.

[0011] Preferably, the mounting base is connected to the solid to be monitored by adhering epoxy resin glue.

[0012] A multi-angle ultrasonic monitoring system for solid defects, comprising a rotating mechanism, a connecting module and a user processing end;

[0013] The rotating mechanism includes a piezoelectric ultrasonic transducer, a stepping motor and an angle encoder, the connecting module includes an excitation source circuit, a stepping drive circuit, a wireless communication module and a signal acquisition circuit, and the user processing end includes a wireless receiving module and an ultrasonic data analysis system;

[0014] The user inputs instructions at the user processing end, and the stepper motor on the rotating mechanism is driven to work through the excitation source circuit in the connection module and the stepper drive circuit. The piezoelectric ultrasonic transducer performs ultrasonic scanning on the solid to be monitored, and sends the scanned ultrasonic data to the user processing end via the connection module, and obtains the position information of the crack defects on the solid to be monitored through the ultrasonic data analysis system.

[0015] A method for multi-angle ultrasonic monitoring of solid defects, comprising the following steps:

[0016] Step 1: A rotating mechanism is placed on the solid to be monitored, and the user inputs a start signal on the user processing terminal, and the user processing terminal sends a command to the single-chip microcomputer through a wireless module;

[0017] Step 2: The single chip microcomputer controls the rotation of the rotating mechanism, and the excitation source circuit on the single chip microcomputer drives the piezoelectric ultrasonic transducer to work. The piezoelectric ultrasonic transducer on the rotating mechanism transmits ultrasonic waves and collects ultrasonic echoes while rotating;

[0018] Step 3: The signal acquisition circuit on the single-chip microcomputer receives the ultrasonic echo signal and sends it to the user processing end through the wireless communication module. The user processing end processes the ultrasonic analysis system, realizes three-dimensional restoration of the defect by the ultrasonic echo signal, obtains the size and position data of the defect through the three-dimensional restoration image, and starts the defect warning system.

[0019] Preferably, according to step 2, the single-chip microcomputer is also connected to an angle signal reading circuit, a stepper motor driving circuit and a temperature acquisition circuit, an angle encoder is provided on the output end of the stepper motor on the rotating mechanism, the angle encoder is connected to the angle signal reading circuit, the stepper motor driving circuit is connected to the stepper motor and drives the stepper motor to work, the temperature acquisition circuit collects the temperature value on the piezoelectric ultrasonic transducer, and the single-chip microcomputer is wirelessly connected to the user processing end by connecting to the wireless communication module.

[0020] Preferably, in step 2, the rotating mechanism includes an X-axis rotating mechanism and a Z-axis rotating mechanism, the X-axis rotating mechanism rotates with the X-axis as the rotation center, the Z-axis rotating mechanism rotates with the Z-axis as the rotation center, the piezoelectric ultrasonic transducer is located on the X-axis rotating mechanism, and the piezoelectric ultrasonic transducer forms a hemispherical scanning interval on the solid to be monitored through the rotating mechanism.

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

[0022] 1. Small size and easy installation. One-time fixed-point installation can realize long-term online monitoring of crack development, which is convenient for production management;

[0023] 2. 3D ultrasonic scanning of crack defects, the scanning 3D graphics are intuitive and convenient for fault diagnosis, the scanning range is wide and the depth is deep, the crack size and location can be intelligently identified, real-time monitoring is automatic, and wireless data transmission is performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a method for multi-angle ultrasonic monitoring of solid defects according to the present invention;

[0025] Figure 2 is a schematic diagram of a piezoelectric transducer transmitting ultrasonic waves in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of a crack echo at a position depth of 5 mm in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of a crack echo at a position depth of 40 mm in an embodiment of the present invention;

[0028] Figure 5 A front view of a device in an embodiment of the present invention;

[0029] Figure 6 is a cross-sectional view of a device in an embodiment of the present invention;

[0030] Figure 7 is a top view of a device in an embodiment of the present invention;

[0031] Figure 8 It is a front view of the device in an embodiment of the present invention;.

[0032] Fig. 9 Schematic diagram of the ultrasonic emission route in an embodiment of the present invention.

[0033] Explanation of the accompanying drawings: 1. Mounting base; 2. Rotating block A; 3. Rotating block B; 4. First stepper motor; 5. Second stepper motor; 6. Second angle encoder; 7. Magnet; 8. Gear slot; 9. Transmission gear; 10. Piezoelectric transducer. DETAILED DESCRIPTION

[0034] Below in conjunction with the appended Figures 1 to 9 , clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by ordinary technicians in this field without creative work.

[0035] In the description of the present invention, it should be understood that the terms "counterclockwise", "clockwise", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0036] Embodiment 1:

[0037] A device for multi-angle ultrasonic monitoring of solid defects, comprising a rotating block B3 immersed in oil on a mounting base 1, and a rotating block A2 immersed in oil inside the rotating block B3, wherein a first stepper motor 4 is arranged on the mounting base 1, and an output shaft of the first stepper motor 4 is connected to the rotating block B3, a second stepper motor is arranged on the rotating block B3, and an output shaft of the second stepper motor 5 is connected to the rotating block A2, a piezoelectric transducer 10 is also arranged on the rotating block A2, and a control unit and a wireless communication module are also included, wherein the control unit is respectively connected to the first stepper motor 4, the second stepper motor 5 and the piezoelectric transducer 10, and the control unit is connected to a user end via the wireless communication module.

[0038] It is worth mentioning that please refer to Figure 5 The rotating block A2, the rotating block B3 and the mounting base 1 are all made of the same solid material, wherein lubricating oil is filled between the rotating block A2, the rotating block B3 and the mounting base 1.

[0039] It is worth mentioning that please refer to Figure 6 The edge of the rotating block B3 is provided with a gear groove 8, and the output shaft of the first stepper motor 4 is provided with a transmission gear 9, and the transmission gear 9 is meshed with the gear groove 8, please refer to Figure 7 .

[0040] It is worth noting that the first stepper motor 4 is provided with a first angle encoder, and the second stepper motor 5 is provided with a second angle encoder 6. The first angle encoder obtains the rotation angle data of the rotating block B3, and the second angle encoder 6 obtains the rotation angle data of the rotating block A2. The first angle encoder and the second angle encoder 6 are both connected to the control unit. The control unit includes a single-chip microcomputer connected to the excitation circuit and the acquisition circuit respectively. The excitation circuit and the acquisition circuit are both connected to the piezoelectric transducer 10. The acquisition circuit includes an amplifier circuit and an AD acquisition circuit. The single-chip microcomputer is connected to the amplifier circuit through the AD acquisition circuit, and the amplifier circuit is connected to the piezoelectric transducer 10.

[0041] It is worth mentioning that please refer to Figure 7 The mounting base is provided with an annular magnet, and the mounting base is connected to the solid to be detected through the annular magnet.

[0042] It is worth mentioning that please refer to Figure 8 The mounting base is connected to the solid to be monitored by adhering epoxy resin glue.

[0043] It is worth mentioning that the installation position is simply processed to make it relatively flat and rust-free, and epoxy resin is evenly applied to the bottom of the sensor, and the fork-type magnet adsorption mechanism is used to firmly attract the surface of the measured object. After power-on, the scanning range is input and the lower computer and the upper computer communicate and shake hands. The single-chip microcomputer controls the rotation of the first stepper motor and the second stepper motor, and reads the angle signals α and β at the same time. The single-chip microcomputer controls the excitation source to emit excitation and starts to collect signals at the same time. Each pair of angles α and β corresponds to a set of ultrasonic echo data. The signal is band-pass filtered (the center frequency is consistent with the ultrasonic frequency, such as 2.5MHz) and program-controlled amplified, and read to the single-chip microcomputer by the AD sampling circuit, and the sampling frequency is 25MHz. The read temperature signal is used to correct the sound speed. After the above-mentioned data is pre-processed, it is temporarily stored in the memory, followed by the next scan. After all the scans are completed, all the data are uploaded to the computer using the wireless communication module. The computer saves the data to the database, and then the waveform analysis software retrieves the data and calculates the parameters to establish a scanning model, and finally identifies the size and position of the crack. The computer can draw a monitoring curve and analyze the development of the crack.

[0044] Embodiment 2:

[0045] A multi-angle ultrasonic monitoring system for solid defects, comprising a rotating mechanism, a connecting module and a user processing end;

[0046] The rotating mechanism includes a piezoelectric ultrasonic transducer, a stepping motor and an angle encoder, the connecting module includes an excitation source circuit, a stepping drive circuit, a wireless communication module and a signal acquisition circuit, and the user processing end includes a wireless receiving module and an ultrasonic data analysis system;

[0047] The user inputs instructions at the user processing end, and the stepper motor on the rotating mechanism is driven to work through the excitation source circuit in the connection module and the stepper drive circuit. The piezoelectric ultrasonic transducer performs ultrasonic scanning on the solid to be monitored, and sends the scanned ultrasonic data to the user processing end via the connection module, and obtains the position information of the crack defects on the solid to be monitored through the ultrasonic data analysis system.

[0048] Embodiment 3:

[0049] A method for multi-angle ultrasonic monitoring of solid defects, comprising the following steps:

[0050] Step 1: A rotating mechanism is placed on the solid to be monitored, and the user inputs a start signal on the user processing terminal, and the user processing terminal sends a command to the single-chip microcomputer through a wireless module;

[0051] Step 2: The single chip microcomputer controls the rotation of the rotating mechanism, and the excitation source circuit on the single chip microcomputer drives the piezoelectric ultrasonic transducer to work. The piezoelectric ultrasonic transducer on the rotating mechanism transmits ultrasonic waves and collects ultrasonic echoes while rotating;

[0052] Step 3: The signal acquisition circuit on the single-chip microcomputer receives the ultrasonic echo signal and sends it to the user processing end through the wireless communication module. The user processing end processes the ultrasonic analysis system, realizes three-dimensional restoration of the defect by the ultrasonic echo signal, obtains the size and position data of the defect through the three-dimensional restoration image, and starts the defect warning system.

[0053] It is worth noting that according to step 2, the single-chip microcomputer is also connected to an angle signal reading circuit, a stepper motor driving circuit and a temperature acquisition circuit, an angle encoder is provided on the output end of the stepper motor on the rotating mechanism, the angle encoder is connected to the angle signal reading circuit, the stepper motor driving circuit is connected to the stepper motor and drives the stepper motor to work, the temperature acquisition circuit collects the temperature value on the piezoelectric ultrasonic transducer, and the single-chip microcomputer is wirelessly connected to the user processing end by connecting to the wireless communication module.

[0054] It is worth mentioning that please refer to Figure 5 In step 2, the rotating mechanism includes an X-axis rotating mechanism and a Z-axis rotating mechanism. The X-axis rotating mechanism rotates with the X-axis as the rotation center, and the Z-axis rotating mechanism rotates with the Z-axis as the rotation center. The piezoelectric ultrasonic transducer is located on the X-axis rotating mechanism. The piezoelectric ultrasonic transducer forms a hemispherical scanning interval on the solid to be monitored through the rotating mechanism. Please refer to Figure 6 .

[0055] It is worth mentioning that please refer to Figure 7, the mounting base, rotating block A, and rotating block B must be made of the same material, and the mounting gaps between rotating block A, rotating block B, and the mounting base are filled with oil. The first stepper motor A drives rotating block A to rotate along the Y axis, driving the piezoelectric transducer on rotating block A to rotate, thereby emitting ultrasonic waves in different angles. The movement angle is read by the angle encoder installed on the stepper motor shaft to achieve precise control of the rotation angle. The rotation angle range is determined by the material sound velocity of rotating block A and the distance h from the center of the piezoelectric transducer to the mounting base (for example: the rotating block is made of plexiglass, the distance from the center of the piezoelectric transducer to the mounting base is 40mm, and the rotation angle is plus or minus 60 degrees). The second stepper motor B drives rotating block B to rotate along the X axis, and the total rotation angle is 360 degrees. The rotational motion is a real-time angle control system. Every time the second stepper motor B increases by an angle (for example, if the increment interval is 2 degrees, it needs to rotate 180 times), the corresponding angle encoder will collect the real-time angle information β of the rotating block B. After the second stepper motor B stops after increasing by an angle, the first stepper motor A rotates once at a certain angle at each angle β corresponding to the second stepper motor B (for example, if the increment interval is 1 degree, from positive 60 degrees to negative 60 degrees, it needs to rotate 120 times), and the corresponding angle encoder will collect the real-time angle information α of the rotating block A. Every time the rotating block A rotates by an increasing interval angle, the microcontroller will send an excitation command to make the piezoelectric transducer generate ultrasonic waves, and the piezoelectric transducer will receive the echo.

[0056] It is worth mentioning that please refer to Fig. 9 , based on the basic principle that reflection and transmission phenomena will occur when ultrasonic waves propagate to the interface between two media. When ultrasonic waves are incident obliquely to the interface, reflection and refraction occur, accompanied by wave type conversion. When ultrasonic waves are incident vertically to the interface of the media, vertical reflection and transmission occur. Suppose that in two adjacent media, the speed of sound in medium 1 is greater than the speed of sound in medium 2. The incident angle when the longitudinal wave is incident obliquely to the interface between the two media is. The reflection angles of the longitudinal wave and the transverse wave reflected in the first medium are and respectively, and the refraction angles of the longitudinal wave and the transverse wave refracted in the second medium are and respectively. The relationship between the incident angle, the reflection angle and the refraction angle satisfies the following formula, namely Snell's law:

[0057]

[0058] In the formula, c L1 is the longitudinal wave speed in medium 1, c S1 is the shear wave speed in medium 1, c L2 is the longitudinal wave speed in medium 2, c S2 is the sound velocity of the transverse wave in medium 2. Based on this basic principle, a two-degree-of-freedom ultrasonic sensor with variable incident angle is designed, such as Figure 1As shown, the ultrasonic transducer can rotate freely in the two degrees of freedom of the X-axis and the Z-axis. The rotating mechanism is composed of organic glass, and the mechanisms are coupled together by oil immersion. Due to the similar sound speed, the ultrasonic wave can be refracted into the measured object in the rotating mechanism according to the angle driven by the stepper motor. With the change of angles α and β, the ultrasonic wave travels through the hemispherical range below the center of the sensor axis, realizing three-dimensional scanning. At the same time, according to the angle signals α and β, the acoustic time t of the defect echo, the acoustic speed of the organic glass and the measured object, the compensation acoustic time λ in the organic glass, the geometric dimensions of the sensor, etc., a three-dimensional scanning diagram is established in polar coordinates to identify the size and position of the defect. Among them, the first stepper motor controls the change of angle α, and the second stepper motor controls the change of angle β. The rotating mechanism is mainly composed of fan-shaped, columnar, base, and box organic glass mechanisms. The gaps are all packaged together by oil immersion. Each section is connected to the micro stepper motor through a coupling, and the stepper motor shaft is connected to the angle encoder to realize the reading of angle data. The sensor base is firmly bonded to the measured object through epoxy resin to play a coupling role, and finally fixed with a magnetic adsorption device. The sound velocity in the organic glass and the test piece is obtained according to the sound velocity temperature table, and the time difference between adjacent echo signals is obtained through processing, and then the travel L of the ultrasonic wave in the test piece is calculated according to the compensation sound time λ in the organic glass. Assume that the sound velocity of the test piece material is V, and the time interval of the crack echo is ΔT, then ΔT:

[0059]

[0060] The three-dimensional model is established by the angles α and β, namely:

[0061]

[0062] Where V1 is the sound velocity of the organic glass, V2 is the sound velocity of the measured object, is the sensor geometric size parameter, and the discretized scanning 3D model in the hemisphere is obtained, namely:

[0063]

[0064] Among them, α0 is determined by the critical angle, and β0 is a rotation of 360°.

[0065] It is worth mentioning that please refer to Figure 6 The sensor is fixed at the key position through a fork magnet adsorption device, and the data is transmitted to the computer wirelessly. The magnet adsorption device is installed using a fork mechanism, has strong suction and high reliability, and is easy to install. The supporting circuit system of the sensor has a high-frequency and high-voltage excitation module, a programmable amplifier circuit and a bandpass filter, a high-speed AD acquisition circuit and an angle encoder data reading circuit, and also has a temperature compensation circuit for correcting the sound velocity and a stepper motor drive circuit. The circuit system is controlled by an arm single-chip microcomputer.

[0066] It is worth noting that if there are defects, the following will occur: Fig. 9 The echo shown in the figure requires recording a large number of echo signals (e.g., 180X120=21600 echo signals) for one such three-dimensional scan. These large number of echo signals constitute the characteristic signals of the internal defect cracks of the tested object within the monitoring range of the sensor. Among them, the time interval of the crack echo is the most important characteristic signal. It represents the interval between the excitation wave and the crack echo. It can be obtained by processing the echo signal by the single-chip microcomputer. Where there is no defect crack, this echo signal will not appear, that is, ΔT=0. Each pair of α and β corresponds to a ΔT (e.g., 180X120=21600 ΔT).

[0067] It is worth noting that we only need to obtain the polar coordinates (r, β, θ) of the quantized point N of the defect, and then draw the spatial surface under the same spherical polar coordinates in the computer to construct the spatial three-dimensional model of the defect (for example, a defect somewhere may be composed of 50 such quantized N points). The calculation steps are as follows:

[0068] First, according to the above Snell's law, we can get Then, based on trigonometric functions and the Pythagorean theorem, the travel distance of the ultrasonic wave in the test piece after it touches the defect is deduced. So we get r in polar coordinates:

[0069]

[0070] At the same time, θ can be calculated:

[0071]

[0072] The above calculation process is automatically calculated and generated by a computer program to draw a three-dimensional image. These large numbers of discrete points N together constitute the defect morphology of the entire monitoring area, so that the area and depth of the defect can be obtained.

[0073] It is worth mentioning that please refer to Figure 1, the single-chip microcomputer sends a pulse signal to control the first stepper motor A and the second stepper motor B, and reads the corresponding angle encoder to rotate the sensor to the initial position. The single-chip microcomputer controls the excitation circuit to transmit the excitation voltage signal (for example, 1000 volts). The ultrasonic transducer converts the electrical signal into a sound wave signal. The ultrasonic wave is emitted and incident obliquely into the test piece. If a defect is encountered, the ultrasonic wave scatters the echo signal, which is received by the ultrasonic transducer and converted into an electrical signal. After amplification, filtering and AD sampling, the single-chip microcomputer calculates the time ΔT between the excitation wave and the echo after receiving the signal, and sends ΔT and the corresponding α and β to the computer through the wireless transmission module. When β remains unchanged, the above-mentioned ultrasonic emission and reception process is executed every time α increases by one value (for example, 1 degree). When α completes a scan, β increases by one value (for example, 2 degrees). After all scans are completed, the end command is sent to the computer. Please refer to Figure 1 .

[0074] It is worth mentioning that please refer to Figure 8 The material of the organic glass oil-immersed three-dimensional rotating mechanism in this application can be other solid materials, but its sound velocity needs to be close to the sound velocity of organic glass (such as the longitudinal wave sound velocity of 2000 to 3500m / s) and less than the sound velocity of the measured object (such as the sound velocity of the measured steel is 5900m / s). The installation base and the rotating block B and the rotating block B and the rotating block A must be immersed in oil to fill the gap of the rotating mechanism. The purpose of this is to minimize the scattering and reflection of ultrasonic waves at the medium interface, increase the transmittance, and make the mechanisms tightly coupled together, so that the ultrasonic waves can be coupled to the bottom surface of the base according to the scanning angle, and then obliquely incident into the measured object. The oil here needs to be a non-volatile clean oil with a sound velocity close to that of the rotating block A material.

[0075] It is worth noting that this long-term monitoring sensor is generally scanned every two days. Each signal and the model established in the computer are stored in the database. Crack warning includes crack area depth warning and crack growth rate warning. The operator can set a warning threshold. When the monitoring data exceeds this value each time, an alarm will be issued to monitor and prevent major accidents. The crack growth rate is to make a difference between the crack area each time and the crack area of ​​the previous time to get ΔS, and then draw a curve of ΔS and time. If the slope of the curve changes significantly (exceeds the threshold), it means that the crack will have a greater possibility of cracking, and an alarm is needed. The warning signal can be displayed on the screen by the computer for the operator to monitor.

[0076] It is worth mentioning that several cracks were machined by EDM in the laboratory and these cracks inside the steel parts were scanned. The crack echo waveforms are as follows: Figure 4 As shown, Figure 3As shown, the crack depth is identified, and the results are shown in Table 1. Table 1 shows the experimental results of cracks of different depths. After the ultrasonic wave detects the crack through scanning, the crack defect echo appears in the scanning range, while the echo signal does not appear in the space without crack defects, indicating that the scanning method can effectively detect crack defects. Through the analysis and modeling of the echo data by computer, the crack depth is accurately identified.

[0077] Table 1

[0078]

[0079] In summary, the implementation principle of the present invention is: it has a piezoelectric ultrasonic transducer, an organic glass oil-immersed two-degree-of-freedom rotation mechanism, a first stepper motor driver and an angle encoder, a second stepper motor driver and an angle encoder, an excitation source and a signal acquisition circuit, a wireless data transmission module, an ultrasonic signal intelligent analysis software, and a fork magnet adsorption installation mechanism. The method for monitoring crack defects of large steel parts is a fully automated real-time monitoring method, characterized in that the sensor is easy to install and can be fixed on large steel parts for a long time for real-time monitoring. The scanning range of the method is a hemispherical range centered on the sensor axis, and can identify crack defects with an effective area greater than 5X5 square millimeters. The system can transmit data wirelessly, save a large amount of data, establish a scanning three-dimensional map and judge the size and position of the crack. The sensor is adsorbed on the tested part through a fork magnet adsorption installation mechanism, and then the suction is increased by an electromagnet. The ultrasonic transducer of the sensor can rotate freely on the two degrees of freedom of the X-axis and the Z-axis. The rotating mechanism is composed of organic glass, and the mechanisms are coupled together by oil immersion. Due to the similar sound speed, the ultrasonic wave can be refracted into the object to be tested at the angle driven by the stepper motor in the rotating mechanism to detect cracks. As the angles α and β of the piezoelectric ultrasonic transducer in the sensor change, the ultrasonic wave travels through the hemispherical range below the center of the sensor axis, realizing three-dimensional scanning. At the same time, a three-dimensional scanning diagram is established based on the angle signals α and β, the acoustic time t of the defect echo, the acoustic speed of the organic glass and the object to be tested, the compensation acoustic time λ in the organic glass, the geometric dimensions of the sensor, etc., thereby identifying the size and position of the defect. The supporting circuit system of the sensor has a high-frequency (frequency close to the frequency of the piezoelectric ultrasonic transducer) high-voltage excitation signal, a program-controlled amplifier circuit and a bandpass filter, a high-speed AD acquisition circuit and an angle encoder data reading circuit, and a temperature compensation circuit for correcting the sound speed and a micro-stepping motor with a reduction gear and a stepping motor drive circuit. The circuit system is controlled by an ARM single chip microcomputer and communicates with a computer through a wireless transmission module. The monitoring time interval and the monitoring range can be wirelessly controlled by sending instructions from the computer. The invention has a reasonable structure and an ingenious design and is suitable for promotion.

Claims

1. A device for multi-angle ultrasonic monitoring of solid defects, characterized in that: It includes a rotating block B immersed in oil on a mounting base, and a rotating block A immersed in oil inside the rotating block B. A first stepper motor is arranged on the mounting base, and the output shaft of the first stepper motor is connected to the rotating block B. A second stepper motor is arranged on the rotating block B, and the output shaft of the second stepper motor is connected to the rotating block A. A piezoelectric transducer is also arranged on the rotating block A. It also includes a control unit and a wireless communication module. The control unit is respectively connected to the first stepper motor, the second stepper motor and the piezoelectric transducer, and the control unit is connected to the user end through the wireless communication module. The mounting base is provided with an annular magnet, and the mounting base is connected to the solid to be detected through the annular magnet. The mounting base is connected to the solid to be monitored by adhering epoxy resin glue.

2. The device for multi-angle ultrasonic monitoring of solid defects according to claim 1 is characterized in that The rotating block A, the rotating block B and the mounting base are all made of the same solid material, wherein lubricating oil is filled between the rotating block A, the rotating block B and the mounting base.

3. The device for multi-angle ultrasonic monitoring of solid defects according to claim 2, characterized in that: A gear groove is arranged at the edge of the rotating block B, and a transmission gear is arranged on the output shaft of the first stepper motor, and the transmission gear is meshed with the gear groove.

4. The device for multi-angle ultrasonic monitoring of solid defects according to claim 3 is characterized in that: The first stepper motor is provided with a first angle encoder, and the second stepper motor is provided with a second angle encoder. The first angle encoder obtains the rotation angle data of the rotating block B, and the second angle encoder obtains the rotation angle data of the rotating block A. The first angle encoder and the second angle encoder are both connected to the control unit. The control unit includes a single-chip microcomputer connected to the excitation circuit and the acquisition circuit respectively. The excitation circuit and the acquisition circuit are both connected to the piezoelectric transducer. The acquisition circuit includes an amplifier circuit and an AD acquisition circuit. The single-chip microcomputer is connected to the amplifier circuit through the AD acquisition circuit, and the amplifier circuit is connected to the piezoelectric transducer.

5. A method for multi-angle ultrasonic monitoring of solid defects, characterized in that: The device for multi-angle ultrasonic monitoring of solid defects as described in claim 1 is characterized by comprising the following steps: Step 1: A rotating mechanism is placed on the solid to be monitored, and the user inputs a start signal on the user processing terminal, and the user processing terminal sends a command to the single-chip microcomputer through a wireless module; Step 2: The single chip microcomputer controls the rotation of the rotating mechanism, and the excitation source circuit on the single chip microcomputer drives the piezoelectric ultrasonic transducer to work. The piezoelectric ultrasonic transducer on the rotating mechanism transmits ultrasonic waves and collects ultrasonic echoes while rotating; Step 3: The signal acquisition circuit on the single chip receives the ultrasonic echo signal and sends it to the user processing end through the wireless communication module. The user processing end processes the ultrasonic analysis system, realizes three-dimensional restoration of the defect by the ultrasonic echo signal, obtains the size and position data of the defect through the three-dimensional restoration diagram, and starts the defect early warning system; In step 2, the rotating mechanism includes an X-axis rotating mechanism and a Z-axis rotating mechanism, the X-axis rotating mechanism rotates with the X-axis as the rotation center, the Z-axis rotating mechanism rotates with the Z-axis as the rotation center, the piezoelectric ultrasonic transducer is located on the X-axis rotating mechanism, and the piezoelectric ultrasonic transducer forms a hemispherical scanning interval on the solid to be monitored through the rotating mechanism.

6. The method for multi-angle ultrasonic monitoring of solid defects according to claim 5, characterized in that: According to step 2, the single-chip microcomputer is also connected to an angle signal reading circuit, a stepper motor driving circuit and a temperature acquisition circuit, an angle encoder is provided on the output end of the stepper motor on the rotating mechanism, the angle encoder is connected to the angle signal reading circuit, the stepper motor driving circuit is connected to the stepper motor and drives the stepper motor to work, the temperature acquisition circuit collects the temperature value on the piezoelectric ultrasonic transducer, and the single-chip microcomputer is wirelessly connected to the user processing end by connecting to the wireless communication module.

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