CN101706476B - Electromagnetic ultrasonic automatic flaw detection method for plates and device thereof - Google Patents

Abstract

The invention relates to ultrasonic detection technology, in particular to an electromagnetic ultrasonic plate automatic flaw detection method and a device thereof. The invention adopts vertically incident body waves for flaw detection, and can detect plates with relatively large thickness. The electromagnetic ultrasonic flaw detection probe adopted in the present invention adopts a pulse electromagnet to provide a magnetic field, which has the characteristics of a short duration of the magnetic field, and can efficiently detect both ferromagnetic and non-ferromagnetic plates. The invention combines the bottom surface and the echo of the defect, reduces the detection blind area, not only has high sensitivity to the defect, but also can accurately locate the defect. The present invention takes the electromagnetic ultrasonic technology as the core, no acoustic coupling agent is needed during detection, and no pretreatment on the surface of the test piece is required, so the plate can be detected online under various harsh environments (such as high temperature and high speed), and the environmental adaptability is strong , the detection efficiency is higher.

Description

Electromagnetic ultrasonic plate automatic flaw detection method and device

(1) Technical field

The invention relates to ultrasonic detection technology, in particular to an electromagnetic ultrasonic plate automatic flaw detection method and a device thereof.

(2) Background technology

With the smooth development and maturity of manned spaceflight, lunar exploration project, domestic large aircraft, aircraft carrier, high-speed railway and other projects, the demand for sheet metal in my country has increased rapidly. However, due to the limitation of processing technology, defects such as delamination, slag inclusion, crack and oxide film inevitably exist in the production process of sheet metal. As a necessary part of product quality control, non-destructive testing technology must be used in production to eliminate defective products that exceed the standard in time. Among many non-destructive testing technologies, ultrasonic testing has been widely used due to its advantages such as low cost, wide detection range, and relatively high detection accuracy.

At present, the traditional piezoelectric ultrasonic technology is mainly used at home and abroad to complete the non-destructive testing of metal sheets. When using this technology to detect, in order to ensure the smooth transmission of ultrasonic energy from the transducer to the metal plate, the surface usually needs to be cleaned, polished and other pretreatments, and the transducer and the plate must be filled with pure couplant (such as oil, water, etc.). Such devices require surface pretreatment and rely on couplants, making them labor-intensive and detection inefficient.

Electromagnetic ultrasonic technology emerged in the 1960s and 1970s, and has gradually been widely used abroad. In recent years, some domestic invention patents have also begun to use electromagnetic ultrasonic technology to detect flaws in metal sheets. For example, the Chinese patent CN1051086A "Electromagnetic Ultrasonic Automatic Flaw Detection Technology" uses Lamb waves to detect flaws on steel plates below 18mm. Because it is difficult to excite Lamb waves in thick-walled steel plates, this flaw detection technology can only detect flaws in medium and thin plates, and cannot meet the requirements for flaw detection of plates with higher wall thickness. In addition, Lamb waves have dispersion characteristics, and there may be multiple modes at any given excitation frequency, and the sound waves of the same mode will also disperse when they pass through the end face or defect, resulting in multiple modes of ultrasonic waves, so the Lamb wave detection become more complex, and the utility of the device is limited. Chinese patent CN1063848C "Online Automatic Electromagnetic Ultrasonic Flaw Detection System for Hot Steel Plates" uses an electromagnet with an iron core to provide a magnetic field for the flaw detection coil, forming two flaw detection areas, and conducts online detection of steel plates below 40mm. Due to the existence of the iron core, the magnetic field provided by the electromagnet lasts for a long time, which affects the efficiency of flaw detection. The presence of two flaw detection areas per probe is also not conducive to the localization of defects.

(3) Contents of the invention

The purpose of the present invention is to provide an electromagnetic ultrasonic plate automatic flaw detection method and its device for comprehensive and rapid detection of metal plates with a thickness of less than 100 mm and accurate detection of various types of defects.

The object of the present invention is achieved in this way: the electromagnetic ultrasonic plate automatic flaw detection device is composed of a transmitter, a scanning system, a receiver, a data acquisition system and an echo signal processing system, and the transmitter is connected to the scanning system The scanning system is connected to the receiver, the receiver is connected to the data acquisition system, the data acquisition system is connected to the echo signal processing system, and the echo signal processing system is respectively connected to the scanning system and the data acquisition system.

The present invention also has the following technical characteristics:

(1) The transmitter includes a launch controller, a drive circuit, a boost circuit and a power amplifier circuit, the launch controller is connected to the drive circuit and the boost circuit respectively, and the power amplifier circuit is connected to the boost circuit and the drive circuit respectively.

(2) The scanner includes a positioning system, a microcontroller, a stepping motor, a steering gear, a car body, a fixture and an electromagnetic ultrasonic probe, the positioning system is connected to a microcontroller, and the microcontroller is connected to the stepping motor and the The steering gear, the stepping motor, and the steering gear are connected to the vehicle body, the vehicle body is connected to the fixing device, and the fixing device is connected to the electromagnetic ultrasonic probe.

(3) The electromagnetic ultrasonic probe includes a pulsed electromagnet, a double helix coil and a protective layer, the pulsed electromagnet is connected to the double helical coil, and the double helical coil is connected to the protective layer, the electromagnetic ultrasonic probe is a transceiver integrated probe, and the pulsed electromagnet does not include iron core.

(4) The receiver includes a receiving analog switch, an analog filter, a high-gain low-noise amplifier and a level conversion circuit, the receiving analog switch is connected to an analog filter, and the analog filter is connected to a high-gain low-noise amplifier, and the high-gain low-noise The amplifier is connected to a level conversion circuit.

(5) The echo signal processing system includes an echo signal processing module, a microcontroller, a storage unit and a liquid crystal, the echo signal processing module is connected to the microcontroller, and the microcontroller is connected to the storage unit and the liquid crystal respectively, and the echo signal The processing module is realized by FPGA.

The present invention is an electromagnetic ultrasonic plate automatic flaw detection method, the working steps are as follows:

Step 1: System power-on initialization;

Step 2: The pulse electromagnet inside the transceiver integrated electromagnetic ultrasonic probe generates a strong magnetic field with a duration of 200μs; the receiving analog switch is turned off;

Step 3: The high-power ultrasonic driving signal generated by the transmitter is applied to the double-helix flaw detection coil, and the vertical incident body wave is excited in the plate to be tested, and the emission repetition period is 10ms;

Step 4: Ultrasonic waves propagate in the plate to be tested, and reflections and scattering will occur when encountering defects. Turn on the receiving analog switch, and the transceiver integrated probe receives the defects and the reflected wave signals from the bottom surface;

Step 5: The high-speed AD of the data acquisition system collects the conditioned reflected wave signal into the FPGA;

Step 6: The digital signal processing module inside the FPGA comprehensively judges the existence and size of the defect by using the defect and the reflected wave of the bottom surface. If the judgment result is "yes", go to step 7, and if the judgment result is "no", go to step 8;

Step 7: The microcontroller stores the size and position of the defect into the storage unit and displays it on the LCD;

Step 8: The scanning device moves forward at a uniform speed on the plate to be tested;

Step 9: When the scanning device runs to the edge of the plate to be tested, move 2cm laterally, and repeat steps 2 to 8;

Step 10: After the scanning device detects the plate to be tested, the liquid crystal displays the distribution of defects on the entire plate.

The electromagnetic ultrasonic plate automatic flaw detection method and its device of the present invention take electromagnetic ultrasonic technology as the core, no acoustic coupling agent is needed during detection, and no pretreatment is required on the surface of the test piece, so it can be tested under various harsh environments (such as high temperature and high speed). The plate is detected online, with strong environmental adaptability and high detection efficiency. The vertical incident body wave is used for flaw detection, which can detect plates with large thickness. The electromagnetic ultrasonic flaw detection probe adopted in the present invention adopts a pulse electromagnet to provide a magnetic field, which has the characteristics of a short duration of the magnetic field, and can efficiently detect both ferromagnetic and non-ferromagnetic plates. The invention combines the bottom surface and the echo of the defect, reduces the detection blind area, not only has high sensitivity to the defect, but also can accurately locate the defect, so the detection result has a high degree of confidence. The FPGA-based digital signal processing module is used to process the received signal online, which has high detection accuracy and real-time performance. The wall thickness of the detection plate is wide, up to 100mm, which meets the requirements of thick-walled plate detection.

(4) Description of drawings

Fig. 1 is a general structural block diagram of the present invention;

Fig. 2 is a structural block diagram of the transmitter of the present invention;

Fig. 3 is a structural block diagram of the scanner of the present invention;

Fig. 4 is a structural block diagram of the transceiver integrated electromagnetic ultrasonic probe of the present invention;

Fig. 5 is a structural block diagram of the receiver of the present invention;

Fig. 6 is a functional block diagram of the echo signal processing system of the present invention;

Fig. 7 is the detection principle block diagram of the present invention;

Fig. 8 is a schematic diagram of the scanning path of the present invention.

(5) Specific implementation methods

The present invention will be further described below with examples in conjunction with the accompanying drawings.

Embodiment 1, in conjunction with Fig. 1 to Fig. 6, the present invention is an electromagnetic ultrasonic plate automatic flaw detection device, it is made up of transmitter (1), scanning system (2), receiver (3), data acquisition system (4) Composed of an echo signal processing system (5), the transmitter (1) is connected to the scanning system (2), the scanning system (2) is connected to the receiver (3), and the receiver (3) is connected to the data acquisition system (4) , the data acquisition system (4) is connected to the echo signal processing system (5), and the echo signal processing system (5) is respectively connected to the scanning system (2) and the data acquisition system (4).

The present invention also has the following technical characteristics:

The transmitter (1) includes a launch controller (6), a drive circuit (7), a boost circuit (8) and a power amplifier circuit (9), and the launch controller (6) is respectively connected to the drive circuit (7) and The boost circuit (8) and the power amplifying circuit (9) are respectively connected to the boost circuit (8) and the drive circuit (7).

The scanner (2) includes a positioning system (10), a microcontroller (11), a stepping motor (12), a steering gear (13), a car body (14), a fixing device (15) and an electromagnetic ultrasonic The probe (16), the positioning system (10) are connected to the microcontroller (11), and the microcontroller (11) is respectively connected to the stepping motor (12) and the steering gear (13), and the stepping motor (12), the steering gear (13 ) is connected to the car body (14), the car body (14) is connected to the fixing device (15), and the fixing device (15) is connected to the electromagnetic ultrasonic probe (16).

Described electromagnetic ultrasonic probe (16) comprises pulse electromagnet (17), double helix coil (18) and protective layer (19), pulse electromagnet (17) connects double helix coil (18), double helix coil (18) The protective layer (19) is connected, the electromagnetic ultrasonic probe (16) is a transceiver integrated probe, and the pulse electromagnet (17) does not include an iron core.

Described receiver (3) comprises receiving analog switch (20), analog filter (21), high-gain low-noise amplifier (22) and level conversion circuit (23), and receiving analog switch (20) connects analog filter (21), the analog filter (21) is connected to the high-gain low-noise amplifier (22), and the high-gain low-noise amplifier (22) is connected to the level conversion circuit (23).

The echo signal processing system (5) comprises an echo signal processing module (24), a microcontroller (25), a storage unit (26) and a liquid crystal (27), and the echo signal processing module (24) is connected to the microcontroller The device (25), the microcontroller (25) are respectively connected to the storage unit (26) and the liquid crystal (27), and the echo signal processing module is realized by FPGA.

The present invention is an electromagnetic ultrasonic plate automatic flaw detection method, the working steps are as follows:

Step 1: System power-on initialization;

Step 2: The pulse electromagnet inside the transceiver integrated electromagnetic ultrasonic probe generates a strong magnetic field with a duration of 200μs; the receiving analog switch is turned off;

Step 3: The high-power ultrasonic driving signal generated by the transmitter is applied to the double-helix flaw detection coil, and the vertical incident body wave is excited in the plate to be tested, and the emission repetition period is 10ms;

Step 4: Ultrasonic waves propagate in the plate to be tested, and reflections and scattering will occur when encountering defects. Turn on the receiving analog switch, and the transceiver integrated probe receives the defects and the reflected wave signals from the bottom surface;

Step 5: The high-speed AD of the data acquisition system collects the conditioned reflected wave signal into the FPGA;

Step 6: The digital signal processing module inside the FPGA comprehensively judges the existence and size of the defect by using the defect and the reflected wave of the bottom surface. If the judgment result is "yes", go to step 7, and if the judgment result is "no", go to step 8;

Step 7: The microcontroller stores the size and position of the defect into the storage unit and displays it on the LCD;

Step 8: The scanning device moves forward at a uniform speed on the plate to be tested;

Step 9: When the scanning device runs to the edge of the plate to be tested, move 2cm laterally, and repeat steps 2 to 8;

Step 10: After the scanning device detects the plate to be tested, the liquid crystal displays the distribution of defects on the entire plate.

Embodiment 2, with reference to FIG. 7 , the electromagnetic ultrasonic plate automatic flaw detection method and its device of the present invention use vertically incident body waves to detect the plate. When there is no defect, there is only the echo of the bottom surface; when there is a defect, there are both the echo of the bottom surface and the echo of the defect. When detecting shallow defects, the defect echo will be submerged by the main impact, and the bottom echo will be greatly attenuated at this time, so the existence of shallow defects can be judged by the bottom echo. Since the electromagnetic ultrasonic technology does not require acoustic coupling agent and pretreatment of the test piece during detection, the vertical incident body wave generated by it can be used for real-time on-line or in-service detection of plates in various harsh environments.

Embodiment 3, with reference to FIG. 8 , the electromagnetic ultrasonic plate automatic flaw detection method and its device of the present invention, the overall detection process of the plate to be tested (28): the scanning device is placed on the edge of one side of the plate to be tested (28), and the system is powered on After initialization, it starts to move along the edge at a constant speed. At the same time, the pulse electromagnet inside the transceiver integrated electromagnetic ultrasonic probe starts to work, generating a strong magnetic field with a duration of 200μs, and the receiving analog switch is turned off. The high-power ultrasonic drive signal generated by the transmitter is applied to the double-helix flaw detection coil to excite vertically incident body waves in the plate (28) to be tested, and the emission repetition period is 10 ms. Next, turn on the receive simulation switch. Ultrasonic wave propagates in the plate to be tested (28), and will reflect, scatter, etc. when encountering defects and the bottom surface, and the transceiver integrated probe receives the reflected wave signals of defects and the bottom surface. The high-speed AD of the data acquisition system collects the conditioned reflected wave signal into the FPGA. The digital signal processing module inside the FPGA uses the defect and the reflected wave of the bottom surface to comprehensively judge the existence and size of the defect. The liquid crystal displays the waveform of the echo signal in real time, and if a defect is found, the position of the defect will be recorded. When the scanner runs to the edge of the board, move 2cm laterally, repeat the above steps, and scan the entire board (28) to be tested line by line. After the scanner detects the board, the liquid crystal displays the distribution of defects on the whole board.

Claims (2)

1. An electromagnetic ultrasonic plate automatic flaw detection device, which is composed of a transmitter (1), a scanning system (2), a receiver (3), a data acquisition system (4) and an echo signal processing system (5) , characterized in that: the transmitter (1) is connected to the scanning system (2), the scanning system (2) is connected to the receiver (3), the receiver (3) is connected to the data acquisition system (4), and the data acquisition system (4) Connect the echo signal processing system (5), the echo signal processing system (5) connects the scanning system (2) and the data acquisition system (4) respectively; Described transmitter (1) comprises emission controller (6), The driving circuit (7), the boosting circuit (8) and the power amplifying circuit (9), the transmitting controller (6) are respectively connected to the driving circuit (7) and the boosting circuit (8), and the power amplifying circuit (9) is connected to the boosting circuit (9) respectively. Pressure circuit (8) and drive circuit (7); Described scanning system (2) comprises positioning system (10), microcontroller (11), stepper motor (12), steering gear (13), car body (14), fixture (15) and electromagnetic ultrasonic probe (16), positioning system (10) connects microcontroller (11), and microcontroller (11) connects stepper motor (12) and steering gear (13) respectively , the stepper motor (12) and the steering gear (13) are connected to the car body (14), the car body (14) is connected to the fixing device (15), and the fixing device (15) is connected to the electromagnetic ultrasonic probe (16); the electromagnetic ultrasonic Probe (16) comprises pulse electromagnet (17), double helical coil (18) and protective layer (19), and pulse electromagnet (17) connects double helical coil (18), and double helical coil (18) connects protective layer (19) ), the electromagnetic ultrasonic probe (16) is a transceiver integrated probe, and the pulse electromagnet (17) does not include an iron core; the receiver (3) includes a receiving analog switch (20), an analog filter (21), a high gain Low noise amplifier (22) and level conversion circuit (23), receiving analog switch (20) connects analog filter (21), and analog filter (21) connects high-gain low-noise amplifier (22), high-gain low-noise amplifier (22) connect level conversion circuit (23); described echo signal processing system (5) comprises echo signal processing module (24), microcontroller (25), storage unit (26) and liquid crystal (27) , the echo signal processing module (24) is connected to the microcontroller (25), and the microcontroller (25) is respectively connected to the storage unit (26) and the liquid crystal (27), and the echo signal processing module is realized by FPGA. 2. An automatic flaw detection method for a plate using the electromagnetic ultrasonic plate automatic flaw detection device according to claim 1, the working steps are as follows: Step 1: System power-on initialization; Step 2: The pulse electromagnet inside the transceiver integrated electromagnetic ultrasonic probe generates a strong magnetic field with a duration of 200μs; the receiving analog switch is turned off; Step 3: The high-power ultrasonic driving signal generated by the transmitter is applied to the double-helix flaw detection coil, and the vertical incident body wave is excited in the plate to be tested, and the emission repetition period is 10ms; Step 4: The ultrasonic wave propagates in the plate to be tested, and it will reflect and scatter when it encounters a defect, turn on the receiving analog switch, and the transceiver integrated probe receives the defect and the reflected wave signal from the bottom surface; Step 5: The high-speed AD of the data acquisition system collects the conditioned reflected wave signal into the FPGA; Step 6: The digital signal processing module inside the FPGA comprehensively judges the existence and size of the defect by using the defect and the reflected wave of the bottom surface. If the judgment result is "yes", go to step 7, and if the judgment result is "no", go to step 8; Step 7: The microcontroller stores the size and position of the defect into the storage unit and displays it on the LCD; Step 8: The scanning system moves forward at a uniform speed on the plate to be tested; Step 9: When the scanning system runs to the edge of the plate to be tested, move 2cm laterally, and repeat steps 2 to 8; Step 10: After the scanning system detects the plate to be tested, the liquid crystal displays the distribution of defects on the entire plate.

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