High temperature casting and forging coil-only electromagnetic ultrasonic phased array detection device and method

Abstract

The invention discloses a coil-only electromagnetic ultrasonic phased array detection device and method for high-temperature castings and forgings, wherein the device includes a coil-only electromagnetic ultrasonic probe and a multi-channel coil-only electromagnetic ultrasonic detection circuit; the coil-only electromagnetic ultrasonic probe includes a probe housing, a corundum sheet, an interface and a plurality of coils, the corundum sheet is arranged at the bottom of the probe housing, a plurality of coils are arranged in an array above the corundum sheet, and the plurality of coils are electrically connected to the interface; the multi-channel coil-only electromagnetic ultrasonic detection circuit is connected to the interface, and is used to continuously pass a quasi-DC current to the plurality of coils while sequentially passing a strong pulse current into each coil in a preset order, and to detect the echo signal received by each coil. It does not have a permanent magnet, has a small size, and has a high energy conversion efficiency. It can be detected in a small space, and will not be weakened or dissipated in a high-temperature environment because the residual magnetic induction intensity of the permanent magnet is affected by the Curie temperature, and can perform imaging detection on the internal defects of high-temperature castings and forgings.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic detection technology, and in particular to a coil-only electromagnetic ultrasonic fully focused phased array detection device and method for high-temperature castings and forgings. Background Art

[0002] Due to the limitation of processing technology, metal castings and forgings may have various defects during the manufacturing process, such as cracks, inclusions, shrinkage cavities, shrinkage and folding, etc. As an important part of quality control, non-destructive testing can monitor whether there are defects in the workpieces in the production process, and timely remove defective defective products to prevent them from entering the next processing link and causing waste of materials and manpower, which is conducive to improving the product yield and the economic benefits of production and manufacturing.

[0003] Traditional piezoelectric ultrasonic detection methods are often used for internal defects of metal materials. They are mainly used to detect workpieces at room temperature. Usually, a coupling agent (water, glycerin, etc.) is required to achieve good coupling with the test piece. When the temperature of the test piece is high, the coupling agent is easy to evaporate, resulting in poor coupling effect and affecting the test results. Commonly used high-temperature coupling agents include engine oil. Since the ignition point of engine oil is around 200°C, it is only suitable for use in high-temperature environments below 200°C. The maximum temperature of the Nanhu brand high-temperature ultrasonic coupling agent GW-III currently sold on the market is below 550°C, and it is not suitable for ultra-high temperature detection environments above 1200°C. In addition, these coupling agents are only suitable for short-term detection at high temperatures and cannot achieve long-term non-destructive testing and monitoring.

[0004] Air-coupled ultrasonic probes can detect defects in test blocks without contact and do not require coupling agents. However, the acoustic impedance of air is about 400 Rayl, the acoustic impedance of aluminum is about 1.7 MRayl, and the acoustic impedance of iron is about 4.5 MRayl. The acoustic impedance of air and the object being tested is very different, and the acoustic impedance is seriously mismatched, resulting in very low acoustic transmittance. In addition, ultrasonic waves are severely attenuated when propagating in the air, and their attenuation rate is related to the frequency. The higher the frequency, the more severe the attenuation. Therefore, air-coupled ultrasound often uses low-frequency probes to reduce the attenuation of ultrasonic waves when propagating in the air.

[0005] Laser ultrasound is also a non-contact ultrasonic testing method that does not require a coupling agent. Laser-excited ultrasound is mainly based on the thermoelastic effect and the ablation effect. The thermoelastic effect has a low energy conversion efficiency, and the ablation effect will cause slight damage to the surface of the specimen. The instrument is also bulky, has poor portability, and is expensive.

[0006] Due to the need for coupling agents, it is difficult for traditional piezoelectric ultrasound to detect metal workpieces at high temperatures. In some cases, such as the casting line of a steel plant and the high-temperature and high-pressure steam main pipeline of a power plant boiler, it is required to be in operation all the time. Waiting for cooling after shutdown before performing nondestructive testing will result in huge economic losses. Therefore, high-temperature online nondestructive testing and monitoring technology is very important.

[0007] Electromagnetic ultrasonic probes are mainly based on the Lorentz force and magnetostrictive effect. They can directly stimulate ultrasonic waves on metal materials. They have the characteristics of non-contact and no need for coupling agents, and are suitable for non-destructive testing in high-temperature environments. At present, the patents related to electromagnetic ultrasonic phased array testing are as follows:

[0008] Invention patent application number: CN202010343129.8 discloses an electromagnetic ultrasonic phased array and an electromagnetic ultrasonic detection method. The array element used is a centrosymmetric runway coil, each coil has a separate permanent magnet above it, and the magnetic polarity direction of the magnetic unit is perpendicular to the phased array transducer unit.

[0009] Invention patent application number: CN201811623474.6 discloses an electromagnetic ultrasonic phased array transducer with adjustable focal length, which uses a cylindrical permanent magnet to provide a bias magnetic field. A plurality of independent concentric coils of different diameters are placed on the bottom surface of the cylindrical permanent magnet. The excitation current in the inner ring coil and the outer ring coil has an adjustable relative delay time. The purpose of electrically adjusting the focal length of the probe is achieved by changing the relative delay of the current between each coil.

[0010] Invention patent application number: CN201910447618.5 discloses an electromagnetic ultrasonic phased array detection system, including a field programmable gate array FPGA, a high-voltage pulse excitation module, an ADC analog-to-digital converter, an eight-element ultrasonic sensor, and a signal acquisition and display module. The permanent magnet provides a bias magnetic field, and the delayed excitation in the coil controls the deflection direction of the ultrasonic beam excited.

[0011] The permanent magnet in the traditional electromagnetic ultrasonic phased array detection will absorb ferromagnetic particles in the working environment, reduce the transducer efficiency of the ultrasonic wave, and even cause the probe to fail permanently. It is inconvenient to move the probe when testing ferromagnetic specimens. The traditional electromagnetic ultrasound provides a magnetic field with a permanent magnet. Due to the existence of the Curie temperature point, when the temperature of the permanent magnet is higher than the Curie temperature point, the residual magnetic induction intensity of the permanent magnet will weaken or permanently disappear. Therefore, the traditional electromagnetic ultrasonic probe with a permanent magnet requires a water cooling circulation system to cool the permanent magnet in a high temperature environment to keep the temperature below the Curie point. The water cooling circulation system and permanent magnet in the traditional electromagnetic ultrasonic high temperature probe will make the probe bulky. The electromagnet in the electromagnetic EMAT probe is usually composed of a yoke and a coil around the yoke. Due to the need for a yoke, the volume of the probe cannot be miniaturized, and the high temperature tolerance of the excitation coil is also limited. Both permanent magnet and pulsed electromagnetic EMAT are suitable for detection in narrow environments. Summary of the invention

[0012] The present invention provides a coil-only electromagnetic ultrasonic phased array detection device and method for high-temperature castings and forgings, so as to solve the problem that the existing electromagnetic ultrasonic phased array detection technology cannot realize continuous detection under ultra-high temperature.

[0013] In a first aspect, a coil-only electromagnetic ultrasonic phased array detection device for high-temperature castings and forgings is provided, including a coil-only electromagnetic ultrasonic probe and a multi-channel coil-only electromagnetic ultrasonic detection circuit;

[0014] The coil-only electromagnetic ultrasound probe comprises a probe housing, a corundum sheet, an interface and a plurality of coils, wherein the corundum sheet is disposed at the bottom of the probe housing, the plurality of coils are located in the probe housing and are arranged in an array above the corundum sheet, and the plurality of coils are electrically connected to the interface;

[0015] The multi-channel coil-only electromagnetic ultrasonic detection circuit is connected to the interface, and is used to continuously pass a quasi-DC current into the multiple coils while passing a strong pulse current into each coil in sequence according to a preset order, and to detect the echo signal received by each coil.

[0016] Furthermore, the multi-channel coil-only electromagnetic ultrasonic detection circuit includes multiple coil-only electromagnetic ultrasonic detection circuits respectively connected to the multiple coils through interfaces, and each coil-only electromagnetic ultrasonic detection circuit includes a high-voltage strong pulse excitation module, a low-voltage DC excitation module, and an echo detection module connected to the corresponding coil through an interface.

[0017] Furthermore, the coil-only electromagnetic ultrasonic detection circuit also includes a current sampling module, and the current sampling module is connected to the corresponding coil through an interface.

[0018] Furthermore, the plurality of coils are arranged in a line array or a surface array.

[0019] Furthermore, the plurality of coils are racetrack coils or spiral coils.

[0020] Furthermore, the probe housing is filled with high temperature resistant ceramic glue.

[0021] Furthermore, it also includes an FPGA control module with AD sampling connected to the multi-channel coil-only electromagnetic ultrasonic detection circuit, and the FPGA control module with AD sampling is used to control the on and off of the high-voltage strong pulse excitation module and the low-voltage DC excitation module, and to perform analog-to-digital conversion on the detection signal of the multi-channel coil-only electromagnetic ultrasonic detection circuit.

[0022] Furthermore, it also includes a wireless communication module connected to the FPGA control module with AD sampling, which is used to send the detection echo signal after analog-to-digital conversion to a host computer.

[0023] Furthermore, it also includes a host computer connected to the FPGA control module with AD sampling by wire or wirelessly, and the host computer is also used to perform full-focus imaging according to the received echo signal.

[0024] In a second aspect, a method for detecting high-temperature castings and forgings using only coil-type electromagnetic ultrasonic phased array is provided, which is implemented based on the high-temperature castings and forgings using only coil-type electromagnetic ultrasonic phased array detection device as described above, and the steps include:

[0025] Controlling the multi-channel coil-only electromagnetic ultrasonic detection circuit to pass quasi-DC current to all coils;

[0026] When the quasi-DC current is stable, the multi-channel coil-only electromagnetic ultrasonic detection circuit sequentially passes a strong pulse current into each coil in a preset order to excite ultrasonic waves, and when each coil excites ultrasonic waves, all coils receive their echo signals;

[0027] The multi-channel coil-only electromagnetic ultrasonic detection circuit detects the echo signals received by all coils each time ultrasonic waves are excited.

[0028] Furthermore, it also includes:

[0029] Obtain all detected echo signals;

[0030] The high-temperature castings and forgings to be tested are differentiated into several discrete points, and the echo signal amplitude of each discrete point is expressed as follows:

[0031]

[0032] Among them, I A Represents the amplitude of the echo signal at discrete point A; S ij (t A) indicates that when the i-th coil is excited, the j-th coil is excited to generate t A The echo signal received at time t A represents the time taken for the ultrasonic wave to propagate from the i-th coil to the discrete point A and then to the j-th coil, and N is the total number of coils;

[0033] After calculating the echo signal amplitude of each discrete point, different depths of color are used according to the size of the echo signal amplitude to achieve full-focus imaging.

[0034] Furthermore, it also includes:

[0035] Acquire all detected echo signals, perform full-focus imaging, and form an ultrasonic imaging map;

[0036] Input the ultrasonic imaging spectrum into the pre-trained casting and forging defect recognition model to obtain the casting and forging defect type;

[0037] Among them, the casting and forging defect recognition model is obtained by training the neural network model based on historical ultrasonic imaging maps and corresponding defect types.

[0038] Beneficial Effects

[0039] The present invention proposes a coil-only electromagnetic ultrasonic phased array detection device and method for high-temperature castings and forgings. The coil-only structure does not require a water cooling cycle and a permanent magnet. Each coil can realize the excitation and reception of ultrasonic waves, and can also be used to provide a bias magnetic field. The device is smaller in size and can be detected in a narrow environment. The transducer efficiency is high, and the defect detection sensitivity and detection resolution are higher than those of a general electromagnetic ultrasonic probe. The coil-only structure does not require a permanent magnet to provide a bias magnetic field required for excitation and reception of ultrasonic waves. Instead, a quasi-direct current is passed through the coil to generate a bias magnetic field. The residual magnetic induction intensity of the permanent magnet will not be weakened or dissipated in a high-temperature environment due to the influence of the Curie temperature, and the internal defects of the high-temperature castings and forgings can be imaged and detected. The device uses a high-melting-point wire and an external ceramic material as an isolated coil, and has a strong high-temperature continuous tolerance, and can continuously perform online non-destructive testing and monitoring in an ultra-high temperature environment above 1200°C. The bias magnetic field is generated by passing a quasi-direct current through the coil. By increasing the amplitude of the quasi-direct current in the coil, the magnetic field can be greatly enhanced, thereby improving the transducer efficiency of the electromagnetic ultrasonic probe. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 1 is a schematic diagram of the structure of a coil-only electromagnetic ultrasonic probe with 1×8 array elements provided by an embodiment of the present invention, wherein (a) is a cross-sectional schematic diagram and (b) is a top view;

[0042] Figure 2 Schematic diagram of the structure of a coil-only electromagnetic ultrasonic probe with 8×8 array elements provided by an embodiment of the present invention, wherein (a) is a cross-sectional schematic diagram and (b) is a top view;

[0043] Figure 3 It is a schematic diagram of the structure of a coil-only electromagnetic ultrasonic detection circuit provided by an embodiment of the present invention;

[0044] Figure 4 2 is a schematic diagram of the principle of a coil-only electromagnetic ultrasonic phased array detection device for high-temperature castings and forgings provided by an embodiment of the present invention;

[0045] Figure 5 is a schematic diagram of a transduction mechanism provided by an embodiment of the present invention;

[0046] Figure 6 is a schematic diagram of a full-focus imaging algorithm provided by an embodiment of the present invention;

[0047] Figure 7 It is a turn-on timing diagram of the IGBT and the MOS tube provided by the embodiment of the present invention;

[0048] Figure 8 It is a waveform diagram of the sampling resistor when only the quasi-DC current is turned on provided by an embodiment of the present invention;

[0049] Fig. 9 It is a waveform diagram of the sampling resistor when only the strong pulse current is turned on provided by the embodiment of the present invention;

[0050] Fig.10 It is a waveform diagram of the sampling resistor when the turn-on type direct current and the strong pulse current are turned on together provided by the embodiment of the present invention;

[0051] Fig.11 It is an A-scan image of a single array element of the coil-type electromagnetic ultrasonic detection device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0052] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0053] In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "center", "longitudinal", "lateral", "vertical", "horizontal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. When an element is referred to as being "fixed to" another element, it may be directly on the other element or there may also be a centered element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a centered element at the same time.

[0054] In order to solve the problem that the existing electromagnetic ultrasonic phased array detection technology cannot achieve continuous detection under ultra-high temperature, the present invention proposes a coil-only electromagnetic ultrasonic phased array detection device and method for high-temperature castings and forgings, which adopts a coil-only electromagnetic ultrasonic phased array probe structure and a permanent magnet-free solution. The bias magnetic field is provided by a quasi-DC current in the coil, and multiple array elements are excited in sequence, and all array elements receive signals each time they are excited. The probe is specially designed for detection in high-temperature environments, and has a high-temperature resistant coil and a high-temperature resistant probe housing. Its supporting circuit can output a high-amplitude quasi-DC current for providing a bias magnetic field, and a strong pulse current for exciting ultrasonic waves. The collected data is sent to the host computer for full-focus processing to achieve virtual full-focus imaging detection of high-temperature castings and forgings.

[0055] Example 1

[0056] like Figures 1 to 3 As shown, this embodiment provides a coil-only electromagnetic ultrasonic phased array detection device for high-temperature castings and forgings, including a coil-only electromagnetic ultrasonic probe and a multi-channel coil-only electromagnetic ultrasonic detection circuit;

[0057] The coil-only electromagnetic ultrasound probe comprises a probe housing 3, a corundum sheet 2, an interface 5 and a plurality of coils 1, wherein the corundum sheet 2 is disposed at the bottom of the probe housing 3, the plurality of coils 1 are located in the probe housing 3 and are arranged in an array above the corundum sheet 2, and the plurality of coils 1 are electrically connected to the interface 5;

[0058] The multi-channel coil-only electromagnetic ultrasonic detection circuit is connected to the interface 5, and is used to continuously pass a quasi-DC current into the multiple coils 1 while passing a strong pulse current into each coil 1 in sequence according to a preset order, and to detect the echo signal received by each coil 1.

[0059] In specific implementation, the multi-channel coil-only electromagnetic ultrasonic detection circuit first continuously passes a quasi-DC current to all coils 1, and provides the bias magnetic field required for exciting / receiving signals according to the electromagnetic induction theorem. After the quasi-DC current is stable (the quasi-DC current amplitude rises to a peak value), the multi-channel coil-only electromagnetic ultrasonic detection circuit sequentially passes a strong pulse current to each coil 1 in a preset order to excite ultrasonic waves on the surface of the high-temperature castings and forgings being tested. At the same time, after each ultrasonic wave is excited, all coils 1 participate in receiving the echo signal, and then the multi-channel coil-only electromagnetic ultrasonic detection circuit detects the echo signal received by each coil for uploading.

[0060] Specifically, the multi-channel coil-only electromagnetic ultrasonic detection circuit includes a plurality of coil-only electromagnetic ultrasonic detection circuits respectively connected to the plurality of coils 1 through the interface 5, that is, each coil is matched with a coil-only electromagnetic ultrasonic detection circuit. Figure 3 As shown, each coil-only electromagnetic ultrasonic detection circuit includes a high-voltage strong pulse excitation module, a low-voltage DC excitation module, and an echo detection module connected to the corresponding coil 1 through an interface 5. The high-voltage strong pulse excitation module generates an alternating strong pulse current in the coil by discharging the capacitor C1. Due to the principle of electromagnetic induction, the surface of the metal conductor under test will generate induced eddy currents. The on and off of the high-voltage strong pulse excitation module is controlled by the MOS tube and the MOS tube driver chip. The pulse width sent by the FPGA control module to the MOS tube driver chip determines the on and off time of the MOS tube. The low-voltage quasi-DC excitation module generates a continuous, relatively smooth quasi-DC current in the coil by discharging capacitor C2. At this time, a bias magnetic field is generated near the coil. The induced eddy current on the surface of the high-end castings and forgings under test generates ultrasonic waves in this bias magnetic field under the action of the Lorentz force. The quasi-DC current is continuously passed until the ultrasonic echo (defect echo, end face echo) returns to the surface of the sample, providing a bias magnetic field to make the ultrasonic vibration on the surface of the castings and forgings under test generate source current and dynamic magnetic field, thereby generating an induced electromotive force in the coil; the on and off of the low-voltage quasi-DC excitation module is controlled by IGBT and IGBT driver chip, and the pulse width sent by the FPGA control module to the IGBT driver chip determines the on and off time of the IGBT. The echo detection module includes an impedance matching unit and an echo detection unit. The impedance matching unit composed of inductor L2 and capacitor C3 can maximize the transfer of the energy of the induced electromotive force generated in the coil to the echo detection unit, thereby enhancing the amplitude and signal-to-noise ratio of the echo signal. A clear ultrasonic signal can be obtained after filtering by capacitor C4 in the echo detection unit. The echo detection module can pick up the echo signal and filter and amplify it.

[0061] It should be noted that the capacitance of capacitor C1 that excites high-voltage strong pulse current is relatively small, so that it can be discharged quickly to achieve the purpose of enhancing the amplitude of the pulse current. The capacitance of capacitor C2 that provides quasi-DC current needs to be relatively large, so that the quasi-DC current can be maintained for a long time and can still provide a strong bias magnetic field when receiving echoes.

[0062] Preferably, the coil-only electromagnetic ultrasonic detection circuit further comprises a current sampling module, which is connected to the corresponding coil via an interface. The sampling current module observes the discharge current through the sampling resistor R5 to determine the working state of the coil-only electromagnetic ultrasonic circuit and the magnitude of the discharge current.

[0063] Considering the different actual usage scenarios, the plurality of coils 1 can be arranged in a linear array or a planar array. The linear array is arranged in a 1*N manner, and the planar array is arranged in an M*N manner, where M and N are both positive integers. Figure 1 As shown, a 1*8 line array arrangement embodiment is provided. Figure 2 As shown, an 8*8 surface array arrangement embodiment is provided.

[0064] Among them, the multiple coils 1 are runway coils or spiral coils. The coil 1 is wound with enameled wire, and high-melting-point silver wire, gold wire, platinum wire, tungsten wire, etc. are selected as the conductor. High-temperature resistant ceramic glue with quartz and inorganic ceramic materials as the main components is selected as the insulating material between the coil conductors. Such a coil can be continuously tested in a high-temperature environment. Taking the spiral coil as an example, the wire diameter can be selected as 0.1-0.5mm, and the outer diameter of the coil can be selected as 5-25mm.

[0065] Preferably, the probe housing 3 is filled with high temperature resistant ceramic glue 4, which can protect the solder joints of the coil and the interface firmly and reliably, and fix the coil in the probe. The thickness of the corundum sheet 2 is 0.1-0.5 mm. The corundum sheet 2 can reduce the heat radiation generated by the high-end castings and forgings to be measured, and play an insulating role between the coil 1 and the high-end castings and forgings to be measured. At the same time, the corundum sheet 2 has the characteristics of friction resistance similar to ceramics, and together with the brass probe housing 3, it plays a role in protecting the coil 1. The interface 5 uses a LEMO interface, such as Figure 1 As shown, the coil-only electromagnetic ultrasound probe only includes a 16-core LEMO interface. Figure 2 As shown, the coil-only electromagnetic ultrasonic probe includes eight 16-core LEMO interfaces. Copper pulleys 6 with shafts are symmetrically arranged on both sides of the probe housing 3. The copper pulleys 6 with shafts can be fine-tuned and lifted off to protect the corundum sheet 2 at the bottom of the probe from being damaged when detecting high-temperature castings and forgings, and are convenient to move.

[0066] Example 2

[0067] like Figure 4As shown, this embodiment provides a high-temperature casting and forging coil-only electromagnetic ultrasonic phased array detection device, which differs from Embodiment 1 in that it also includes an FPGA control module with AD sampling connected to the multi-channel coil-only electromagnetic ultrasonic detection circuit, and a communication module connected to the FPGA control module with AD sampling, the FPGA control module with AD sampling controls the on and off of the high-voltage strong pulse excitation module and the low-voltage DC excitation module by sending a pulse signal, and performs analog-to-digital conversion on the detection signal of the multi-channel coil-only electromagnetic ultrasonic detection circuit, the detection signal includes an echo signal and a current value collected by the current sampling module; the communication module is used to send the detection signal after analog-to-digital conversion to the host computer.

[0068] It should be noted that the communication module can be a wired communication module, that is, connected to the host computer through a communication wire. In this embodiment, the preferred communication module is a wireless communication module, including but not limited to a WIFI wireless communication module, a 4G / 5G wireless communication module, a ZigBee wireless communication module, etc. Figure 4 As shown, an embodiment using a WIFI wireless communication module is shown.

[0069] Preferably, the detection signal of the multi-channel coil-only electromagnetic ultrasonic detection circuit is first amplified by a preamplifier and then transmitted to an FPGA control module with AD sampling. The FPGA control module with AD sampling integrates an FPGA chip and an AD conversion chip. The FPGA chip controls the AD conversion chip to collect the detection signal. The AD conversion chip can be selected from AD9280, and the maximum sampling rate of AD9280 is 32MSPS, and the sampling bit width is 8bit. After the FPGA chip reads the sampling data of AD9280, a TCP connection is established in the same local wireless network through the WIFI wireless communication module and the host computer. The WIFI wireless communication module selects the ESP8266 module. The ESP8266 module uses the STA mode as the client, and the host computer is used as the server. The host computer as the server can communicate with multiple ESP8266 modules of the client at the same time, and multiple groups of the device can be connected to the same local area network to communicate with the host computer at the same time. The use of Internet of Things technology can help realize the automation of detection and reduce detection costs. The Internet of Things technology is also of great help in the processing of detection data. It can classify, count and analyze the detection data. By analyzing common product defects, targeted improvements can be made to the manufacturing process, accelerating the construction of intelligent detection systems.

[0070] After the host computer receives the echo signal transmitted by the FPGA control module with AD sampling, it uses the full-focus imaging algorithm in the LabVIEW software platform to perform virtual focusing calculations based on full-matrix data to achieve full-focus imaging.

[0071] The working process of the coil-only electromagnetic ultrasonic phased array detection device for high-temperature castings and forgings provided in this embodiment is as follows: a quasi-DC current of 100-2000A is passed through each coil to provide a bias magnetic field. When the quasi-DC current is stable, a sinusoidal strong pulse current of 100-2000A for one cycle is applied to each coil in turn. Figure 5 As shown in the figure, the strong pulse current induces pulsed eddy current on the surface of the high-temperature casting and forging under test, and generates Lorentz force under the action of the bias magnetic field excited by the quasi-DC current, thereby generating ultrasonic waves. The ultrasonic wave propagates downward in the high-temperature casting and forging under test, and is reflected after encountering defects or the bottom surface. The reflected wave returns to the surface of the high-temperature casting and forging under test and causes the surface to vibrate. According to the inverse Lorentz force effect, the surface vibration of the high-temperature casting and forging under test causes the magnetic field around it to change, thereby inducing a voltage signal in each coil. After filtering and amplification, the ultrasonic echo signal received by the coil is sampled by the AD conversion chip and input into the FPGA chip. The FPGA chip transmits these data to the host computer through the WIFI wireless communication module. Using the LabVIEW software development platform, the collected ultrasonic signal is subjected to a virtual focusing post-processing algorithm based on full matrix data to achieve full focusing imaging.

[0072] It should also be noted that when the quasi-DC current in the coil is stable and its amplitude rises to the highest value (that is, when the magnetic field excited by the DC current is the strongest), a high-voltage strong pulse current is passed through the coil to achieve the maximum amplitude of the excited ultrasonic wave, thereby improving the transduction efficiency of the electromagnetic ultrasonic probe.

[0073] Example 3

[0074] This embodiment provides a coil-only electromagnetic ultrasonic phased array detection method for high-temperature castings and forgings, which is implemented based on the coil-only electromagnetic ultrasonic phased array detection device for high-temperature castings and forgings provided in the above embodiment, and the steps include:

[0075] S1: Control the multi-channel coil-only electromagnetic ultrasonic detection circuit to pass quasi-DC current to all coils;

[0076] S2: When the quasi-DC current is stable, the multi-channel coil-only electromagnetic ultrasonic detection circuit sequentially passes a strong pulse current into each coil in a preset order to excite ultrasonic waves, and when each coil excites ultrasonic waves, all coils receive their echo signals;

[0077] S3: The multi-channel coil-only electromagnetic ultrasonic detection circuit detects the echo signals received by all coils each time the ultrasonic wave is excited.

[0078] In this embodiment, it also includes:

[0079] S4: Acquire all detected echo signals;

[0080] S5: Perform full focus imaging using a full focus imaging algorithm, such as Figure 6 As shown, it specifically includes: differentiating the high-temperature casting and forging to be tested into a number of discrete points, and the amplitude of the echo signal at each discrete point is expressed as follows:

[0081]

[0082] Among them, I A Represents the amplitude of the echo signal at discrete point A; S ij (t A ) indicates that when the i-th coil is excited, the j-th coil is excited to generate t A The echo signal received at time t A It represents the time taken for the ultrasonic wave to propagate from the i-th coil to the discrete point A and then to the j-th coil, where N is the total number of coils. After calculating the amplitude of the echo signal at each discrete point, different depths of color are used according to the amplitude of the echo signal to achieve full-focus imaging.

[0083] Example 4

[0084] This embodiment provides a coil-only electromagnetic ultrasonic phased array detection method for high-temperature castings and forgings, which, based on Embodiment 3, further includes:

[0085] Acquire full-focus imaging to form an ultrasonic imaging map;

[0086] Input the ultrasonic imaging spectrum into the pre-trained casting and forging defect recognition model to obtain the casting and forging defect type;

[0087] Among them, the casting and forging defect recognition model is obtained by training the neural network model based on historical ultrasonic imaging maps and corresponding defect types.

[0088] Specifically, several historical ultrasonic imaging atlases and corresponding defect types are collected, and the historical ultrasonic imaging atlases are labeled to construct training sets and test sets. It should be noted that the sample types in the training set and the test set include normal samples and samples of various defect types. A multi-classification model is built based on a neural network model, with historical ultrasonic imaging atlases as input and corresponding labels as output. The built multi-classification model is trained using the training set and the test set, and finally a casting and forging defect recognition model is obtained. Then, the casting and forging defect recognition model can be used to realize intelligent recognition and judgment of defects. During implementation, the neural network model can be selected from RCNN, Fast-RCNN, Faster-RCNN, R-FCN, Mask-RCNN, YOLO, SSD, etc.

[0089] Figure 7The diagram shows the conduction timing of IGBT and MOS tube. IGBT is turned on first (waveform of channel 1 in the figure), and a quasi-DC current is generated in the coil to provide a magnetic field. When the quasi-DC current reaches a peak value, the MOS tube is turned on (waveform of channel 2 in the figure) to generate a high-voltage strong pulse current to excite the ultrasonic wave. This is to achieve the purpose of exciting the ultrasonic wave when the bias magnetic field is the largest and the highest energy conversion efficiency.

[0090] Figure 8 The waveform diagram of the sampling resistor when only the quasi-DC current is turned on, channel 1 is the conduction timing of the quasi-DC current turn-on switch IGBT, and channel 3 is the voltage value on the sampling resistor. The resistance of the sampling resistor is 10mΩ. The current flowing through the sampling resistor can be calculated by I=U / R. The maximum voltage across the sampling resistor is about 1.2V, that is, the current flowing through is about 120A. The sampling resistor and the coil are in series, and the current in the resistor is equal to the current in the coil. A current of 120A also flows through the coil. The magnetic field excited by this current around the EMAT probe is a bias magnetic field for providing excitation and receiving ultrasonic echoes. It can be explained that the low-voltage quasi-DC excitation module can provide the function of providing a bias magnetic field when working alone.

[0091] Fig. 9 The waveform of the sampling resistor when only the high-voltage strong pulse current is turned on. Channel 2 is the conduction timing of the strong pulse current turning on the switch MOS tube, and channel 3 is the voltage value on the sampling resistor. The resistance of the sampling resistor is 10mΩ. Similarly, it shows that the high-voltage strong pulse excitation module can provide the strong pulse current required to excite ultrasound when working alone.

[0092] Fig.10 This is the waveform of the sampling resistor when the quasi-DC current and high-voltage strong pulse are turned on together. Channel 1 is the turn-on timing of the quasi-DC current turning on the switch IGBT, channel 2 is the turn-on timing of the strong pulse current turning on the switch MOS, and channel 3 is the voltage value on the sampling resistor. The resistance of the sampling resistor is 10mΩ. Fig.10 It can be explained that when the high-voltage strong pulse excitation module and the low-voltage quasi-DC excitation module work together, their expectations can be achieved: the strong pulse current excites the ultrasonic wave, and the quasi-DC current provides the bias magnetic field function.

[0093] Fig.11 This is an A-scan image of a single array element of a coil-type electromagnetic ultrasonic testing device. The quasi-DC excitation current is excited at time 0, the strong pulse current excites the ultrasonic wave at 40μs, the echo amplification factor is 40dB, the test block material is aluminum, the thickness is 150mm, the excited longitudinal wave speed is about 6000m / s, the first echo is located at 90μs, and the second echo is located at 140μs.

[0094] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0095] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A coil-only electromagnetic ultrasonic phased array detection method for high-temperature castings and forgings, characterized in that: Based on the high-temperature casting and forging coil-only electromagnetic ultrasonic phased array detection device, the high-temperature casting and forging coil-only electromagnetic ultrasonic phased array detection device includes a coil-only electromagnetic ultrasonic probe and a multi-channel coil-only electromagnetic ultrasonic detection circuit; The coil-only electromagnetic ultrasound probe comprises a probe housing, a corundum sheet, an interface and a plurality of coils, wherein the corundum sheet is disposed at the bottom of the probe housing, the plurality of coils are located in the probe housing and are arranged in an array above the corundum sheet, and the plurality of coils are electrically connected to the interface; The multi-channel coil-only electromagnetic ultrasonic detection circuit is connected to the interface, and is used to continuously pass a quasi-DC current into the multiple coils while passing a strong pulse current into each coil in sequence according to a preset order, and to detect the echo signal received by each coil; The detection method steps include: Controlling a multi-channel coil-only electromagnetic ultrasonic detection circuit to pass a quasi-DC current to all coils; When the quasi-DC current is stable, the multi-channel coil-only electromagnetic ultrasonic detection circuit sequentially passes a strong pulse current into each coil in a preset order to excite ultrasonic waves, and when each coil excites ultrasonic waves, all coils receive their echo signals; The multi-channel coil-only electromagnetic ultrasonic detection circuit detects the echo signals received by all coils each time the ultrasonic wave is excited; Acquire all detected echo signals, perform full-focus imaging, and form an ultrasonic imaging map; Input the ultrasonic imaging spectrum into the pre-trained casting and forging defect recognition model to obtain the casting and forging defect type; Among them, the casting and forging defect recognition model is obtained by training the neural network model based on historical ultrasonic imaging maps and corresponding defect types.

2. The coil-only electromagnetic ultrasonic phased array detection method for high-temperature castings and forgings according to claim 1 is characterized in that: The multi-channel coil-only electromagnetic ultrasonic detection circuit includes multiple coil-only electromagnetic ultrasonic detection circuits respectively connected to the multiple coils through interfaces, and each coil-only electromagnetic ultrasonic detection circuit includes a high-voltage strong pulse excitation module, a low-voltage DC excitation module, and an echo detection module connected to the corresponding coil through an interface.

3. The coil-only electromagnetic ultrasonic phased array detection method for high-temperature castings and forgings according to claim 2 is characterized in that: The coil-only electromagnetic ultrasonic detection circuit also includes a current sampling module, and the current sampling module is connected to the corresponding coil through an interface.

4. The coil-only electromagnetic ultrasonic phased array detection method for high-temperature castings and forgings according to claim 1 is characterized in that: The plurality of coils are arranged in a linear array or a planar array, and the plurality of coils are racetrack coils or spiral coils.

5. The coil-only electromagnetic ultrasonic phased array detection method for high-temperature castings and forgings according to claim 1 is characterized in that: The probe shell is filled with high temperature resistant ceramic glue.

6. The coil-only electromagnetic ultrasonic phased array detection method for high-temperature castings and forgings according to claim 2 is characterized in that: It also includes an FPGA control module with AD sampling connected to the multi-channel coil-only electromagnetic ultrasonic detection circuit. The FPGA control module with AD sampling is used to control the on and off of the high-voltage strong pulse excitation module and the low-voltage DC excitation module, and to perform analog-to-digital conversion on the detection signal of the multi-channel coil-only electromagnetic ultrasonic detection circuit.

7. The coil-only electromagnetic ultrasonic phased array detection method for high-temperature castings and forgings according to claim 6 is characterized in that: It also includes a wireless communication module connected to the FPGA control module with AD sampling, which is used to send the detection signal after analog-to-digital conversion to a host computer.

8. The coil-only electromagnetic ultrasonic phased array detection method for high-temperature castings and forgings according to claim 1 is characterized in that: Also includes: Obtain all detected echo signals; The high-temperature castings and forgings to be tested are differentiated into several discrete points, and the echo signal amplitude of each discrete point is expressed as follows: Among them, I A Represents the amplitude of the echo signal at discrete point A; S ij (t A ) indicates that when the i-th coil is excited, the j-th coil is excited to generate t A The echo signal received at time t A represents the time taken for the ultrasonic wave to propagate from the i-th coil to the discrete point A and then to the j-th coil, and N is the total number of coils; After calculating the echo signal amplitude of each discrete point, different depths of color are used according to the size of the echo signal amplitude to achieve full-focus imaging.

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