Handheld multi-frequency detection ultrasonic probe and method thereof

Abstract

The invention discloses a handheld multi-frequency detection ultrasonic probe which is used for detecting the interior of a sleeve by utilizing ultrasonic longitudinal waves with different frequencies, and detecting deep defects and surface cracks at the same time by combining the penetration depth and resolution of the multi-frequency ultrasonic longitudinal waves. Ultrasonic wafers of the probe are transversely arranged, and ultrasonic longitudinal wave signals with different frequencies are generated through the piezoelectric effect. During detection, firstly, depth detection is carried out through low-frequency ultrasonic longitudinal waves, after a detection area is determined, scanning detection is carried out layer by layer through multiple frequencies, detection signals of different frequencies and corresponding depths are generated, all frequency results are combined into a two-dimensional image, and detection data are displayed and recorded in real time, so that comprehensive evaluation of the internal defects of the casing pipe is realized.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic detection, and in particular to a handheld multi-frequency detection ultrasonic probe and a method thereof. Background Art

[0002] High-voltage dry-type bushings, key components for passing the high-voltage current-carrying conductors of ultra-high voltage transformers through the grounded casing, perform both electrical insulation and mechanical support, making them crucial core components in power systems. However, their harsh operating environment, requiring them to withstand high voltages, high currents, and significant mechanical stress, can lead to cracks in the internal insulation layer of dry-type bushings over long periods of operation, posing a significant challenge to the stable operation of power systems.

[0003] Traditional detection methods, such as partial discharge testing, dielectric loss capacitance testing, and visual inspection, all have numerous shortcomings. For example, they struggle to detect low-level partial discharge signals, limiting their detection capabilities and scope. Dry-type bushings, in particular, can harbor defects such as microbubbles and latent microcracks due to manufacturing process issues, or develop microcracks from long-term combined electrical, thermal, and mechanical stress. These defects are often difficult to detect effectively using traditional methods.

[0004] Ultrasonic nondestructive testing (UT), an emerging inspection technology, has attracted considerable attention in recent years due to its wide range of applications, large inspection depth, accurate defect location, high sensitivity, low cost, ease of use, rapid inspection speed, harmlessness to humans, and ease of on-site use. However, traditional ultrasonic testing technology primarily relies on a single-frequency ultrasonic longitudinal wave, which has limitations in inspection depth and resolution, making it difficult to simultaneously detect large defects deep within the surface and small cracks.

[0005] Therefore, it is particularly important in this field to have a handheld multi-frequency detection ultrasonic probe that can efficiently and comprehensively detect internal defects of high-voltage bushings. Summary of the Invention

[0006] To address the aforementioned technical issues, the present invention aims to provide a handheld multi-frequency ultrasonic probe that accurately inspects the interior of casing using ultrasonic longitudinal waves of varying frequencies. Combining the advantages of both low- and high-frequency longitudinal ultrasonic waves, this probe enables a comprehensive assessment of internal casing defects. During the inspection process, the probe automatically matches the optimal ultrasonic frequency for different depths. By sweeping across multiple frequencies, it generates precise two-dimensional images, helping inspectors analyze defect location and size.

[0007] In order to achieve the above-mentioned object, the present invention adopts the following scheme.

[0008] A handheld multi-frequency detection ultrasonic probe, comprising:

[0009] The bottom wave detection module is used to detect the bottom wave by using low-frequency ultrasonic longitudinal waves to obtain the depth information of the casing under test before the multi-frequency sweep is formally carried out.

[0010] An optimization module is used to generate a depth-frequency optimization function to automatically match the optimal detection frequency at different depths according to the maximum depth;

[0011] The multi-frequency detection module uses a handheld multi-frequency detection ultrasonic probe to perform multi-level detection through ultrasonic longitudinal waves of multiple frequencies;

[0012] The data processing module is used to process the multi-frequency detection signals in real time to generate a two-dimensional image.

[0013] Optionally, in the optimization module, the depth-frequency optimization function automatically matches the corresponding optimal detection frequency according to different detection depths.

[0014] Optionally, the data processing module can combine detection signals at multiple frequencies into a two-dimensional image, and display and record detection results at different depths in real time.

[0015] Optionally, the probe has a handheld and portable design, is suitable for on-site detection, and is suitable for detecting casings with complex geometric structures.

[0016] Optionally, the ultrasonic probe includes a plurality of ultrasonic chips, which generate ultrasonic longitudinal wave signals of different frequencies through the piezoelectric effect of the ultrasonic chips, and the ultrasonic longitudinal wave signals are used to perform layered detection on the interior of the casing under test.

[0017] A handheld multi-frequency ultrasonic probe detection method comprises the following steps:

[0018] Step 1: Start the handheld multi-frequency ultrasonic probe to detect the bottom wave and obtain the depth information of the casing to be inspected;

[0019] Step 2: Generate a depth-frequency correspondence function based on the depth information;

[0020] Step 3: Perform multi-frequency sweeping and refined detection;

[0021] Step 4: Real-time display and data recording.

[0022] Optionally, step 2 includes:

[0023] Step 2.1: Based on the depth information and casing diameter of the casing to be inspected obtained by bottom wave detection, the data processing module collects and processes the relevant data and obtains the material correction coefficients α and β;

[0024] Step 2.2: Based on the processed data, the handheld multi-frequency detection ultrasonic probe automatically generates a depth-frequency correspondence function.

[0025] Optionally, in step 3, the ultrasonic probe first uses low-frequency ultrasonic longitudinal waves to detect deep defects, and then switches to high-frequency ultrasonic longitudinal waves according to the depth-frequency optimization function to detect shallow small defects.

[0026] Optionally, step 3 includes:

[0027] Step 3.1: First, use low-frequency ultrasonic longitudinal waves to conduct deep detection to preliminarily find defects inside the casing;

[0028] Step 3.2: According to the indication of the depth-frequency correspondence function, switch to a higher frequency for layer-by-layer inspection. Scan the casing layer by layer according to the depth-frequency correspondence function until the entire inspection area is scanned. The specific type of defect is determined by the inspector based on the inspection results.

[0029] Optionally, step 4 includes:

[0030] Step 4.1: During the inspection process, the ultrasonic probe displays the inspection results in real time. The inspector can see the location and size of defects at different depths through the display screen of the ultrasonic probe, so as to make timely judgments and adjustments.

[0031] Step 4.2: All test data will be recorded in real time and stored in the probe's local storage device, and can be subsequently viewed, analyzed, and archived through supporting software or equipment.

[0032] Compared with the prior art, the present invention has the following beneficial technical effects:

[0033] (1) High efficiency of multi-frequency detection: By combining the advantages of low-frequency and high-frequency ultrasonic longitudinal waves, the present invention can simultaneously detect deep and shallow defects in a single test, improving detection efficiency and comprehensiveness. Specifically, low-frequency ultrasonic longitudinal waves can penetrate deeper materials and detect larger defects, while high-frequency ultrasonic longitudinal waves have higher resolution and can detect small cracks or bubbles in shallow layers. The combination of the two ensures comprehensive detection of defects of different depths.

[0034] (2) Accuracy of depth-frequency optimization matching: Through the depth-frequency optimization function, the probe can automatically match the optimal detection frequency, ensuring that the detection signal at each depth is in the best state and maximizing detection accuracy. Specifically, the frequency is automatically adjusted according to the detection depth, so that the detection signal at each depth can be fully utilized, thereby improving the reliability and accuracy of the overall detection.

[0035] (3) Real-time display and recording function: The probe has real-time display and data recording functions. It can display the test results in real time during the test process and store the data for subsequent analysis and archiving. Specifically, the real-time display function can intuitively show the test progress and results to the test personnel, while the data recording function ensures the complete archiving of the test results, which is convenient for later review and data analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings illustrate exemplary embodiments of the present invention and together with the description serve to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification.

[0037] Figure 1 This is a diagram of a handheld multi-frequency detection ultrasonic probe structure and its detection principle in one embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of multi-frequency signal detection and imaging of a handheld multi-frequency detection ultrasound probe in one embodiment of the present invention;

[0039] Figure 3 is a flow chart of a detection method using a handheld multi-frequency ultrasonic probe in one embodiment of the present invention;

[0040] Figure 4 is an example diagram of a low-frequency ultrasonic signal according to an embodiment of the present invention;

[0041] Figure 5 This is an example diagram of the detection results of a certain point in one embodiment of the present invention;

[0042] Figure 6 This is an example diagram of a two-dimensional image in one embodiment of the present invention. DETAILED DESCRIPTION

[0043] The following is combined with Figures 1 to 6 The present invention will be further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the relevant content and are not intended to limit the present invention. It should also be noted that for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0044] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0045] Unless otherwise stated, the exemplary embodiments / examples shown are to be understood as providing exemplary features of various details of some ways in which the technical concept of the present invention can be implemented in practice. Therefore, unless otherwise stated, the features of the various embodiments / examples may be further combined, separated, interchanged, and / or rearranged without departing from the technical concept of the present invention.

[0046] The use of cross hatching and / or shading in the accompanying drawings is generally used to make the boundaries between adjacent components clear. As such, unless otherwise indicated, the presence or absence of cross hatching or shading does not convey or indicate any preference or requirement for the specific materials, material properties, dimensions, proportions, commonalities between the components shown, and / or any other characteristics, attributes, properties, etc. of the components. In addition, in the accompanying drawings, the sizes and relative sizes of the components may be exaggerated for clarity and / or descriptive purposes. When the exemplary embodiments can be implemented differently, the specific process sequence can be performed in a different order than described. For example, two successively described processes can be performed substantially simultaneously or in an order opposite to the order described. In addition, the same figure numbers represent the same components.

[0047] When a component is referred to as being “on,” “over,” “connected to,” or “coupled to” another component, the component may be directly on, directly connected to, or directly coupled to the other component, or intervening components may be present. However, when a component is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another component, there are no intervening components present. For this purpose, the term “connected” may refer to a physical connection, an electrical connection, etc., with or without intervening components.

[0048] For descriptive purposes, the present disclosure may use spatially relative terms such as "below," "beneath," "under," "down," "above," "upper," "above," "higher," and "side (e.g., as in "sidewall")," to describe the relationship of one component to another (other) component as shown in the accompanying drawings. The spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in addition to the orientation depicted in the accompanying drawings. For example, if the device in the drawings is turned over, a component described as "below" or "beneath" another component or feature would then be oriented "above" the other component or feature. Thus, the exemplary term "below" can encompass both the "above" and "below" orientations. Furthermore, the device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0049] The terms used herein are for the purpose of describing specific embodiments and are not intended to be restrictive. As used herein, unless the context clearly indicates otherwise, the singular forms "one (kind, person)" and "said (the)" are also intended to include plural forms. In addition, when the terms "comprise" and / or "include" and their variations are used in this specification, the features, integral bodies, steps, operations, parts, assemblies and / or their groups stated are explained, but the presence or addition of one or more other features, integral bodies, steps, operations, parts, assemblies and / or their groups is not excluded. It should also be noted that, as used herein, the terms "substantially", "approximately" and other similar terms are used as approximate terms and not as degree terms, so that they are used to explain the inherent deviations of the measured values, calculated values and / or the values provided that will be recognized by those of ordinary skill in the art.

[0050] In one embodiment, the present invention provides a handheld multi-frequency detection ultrasonic probe, the ultrasonic probe comprising:

[0051] The bottom wave detection module is used to detect the bottom wave by using low-frequency ultrasonic longitudinal waves to obtain the depth information of the casing under test before the multi-frequency sweep is formally carried out.

[0052] An optimization module is used to generate a depth-frequency optimization function to automatically match the optimal detection frequency at different depths according to the maximum depth;

[0053] The multi-frequency detection module uses a handheld multi-frequency detection ultrasonic probe to perform multi-level detection through ultrasonic longitudinal waves of multiple frequencies;

[0054] The data processing module is used to process the multi-frequency detection signals in real time to generate a two-dimensional image.

[0055] Optionally, in the optimization module, the depth-frequency optimization function automatically matches the corresponding optimal detection frequency according to different detection depths.

[0056] Optionally, the data processing module can combine detection signals at multiple frequencies into a two-dimensional image, and display and record detection results at different depths in real time.

[0057] Optionally, the probe has a handheld and portable design, is suitable for on-site detection, and is suitable for detecting casings with complex geometric structures.

[0058] Optionally, the ultrasonic probe includes a plurality of ultrasonic chips, which generate ultrasonic longitudinal wave signals of different frequencies through the piezoelectric effect of the ultrasonic chips, and the ultrasonic longitudinal wave signals are used to perform layered detection on the interior of the casing under test.

[0059] In one embodiment, referring to Figure 1The present invention provides a handheld multi-frequency ultrasonic probe. The probe comprises multiple ultrasonic chips, each of which generates ultrasonic longitudinal wave signals of varying frequencies through the piezoelectric effect. These signals are used to perform layered inspection of the casing interior. Each chip generates ultrasonic longitudinal waves of varying wavelengths at varying frequencies, adapting to the needs of defect detection at varying depths.

[0060] Multiple ultrasonic chips are arranged laterally so that each chip can cover a larger surface area. At the same time, multiple ultrasonic chips work synchronously to achieve more efficient detection.

[0061] In one embodiment, the present invention provides a handheld multi-frequency detection ultrasonic probe, comprising:

[0062] 1. Bottom wave detection module: before formally performing multi-frequency scanning, the handheld multi-frequency detection ultrasonic probe first performs bottom wave detection through low-frequency ultrasonic longitudinal waves to obtain depth information of the tested casing.

[0063] Specifically, the ultrasonic probe transmits low-frequency ultrasonic longitudinal waves and receives reflected signals to calculate the internal depth d of the bushing insulation. max On this basis, the depth information is generated, that is, the maximum depth dmax obtained, and provides a reference for the subsequent depth-frequency optimization function. Bottom wave detection can not only determine the depth range of detection (0~d max ), and can also obtain defect information that can be detected by low-frequency ultrasonic longitudinal waves.

[0064] 2. Optimization module, which is used to generate a depth-frequency optimization function to automatically match the optimal detection frequency at different depths.

[0065] The depth-frequency optimization function automatically selects the most appropriate frequency for inspection based on the thickness and acoustic properties of the material being tested. For example, it uses low-frequency longitudinal ultrasonic waves for penetration inspection at deeper depths, while high-frequency longitudinal ultrasonic waves provide high-resolution scanning at shallower depths. This optimization function automatically adjusts the frequency to ensure efficient inspection at the optimal frequency at every depth.

[0066] The depth-frequency optimization function takes the signal-to-noise ratio (SNR) as the optimization target and selects the optimal ultrasonic detection frequency f that maximizes the signal-to-noise ratio (SNR) for different depths d to achieve efficient and comprehensive detection. The signal-to-noise ratio (SNR) is determined by the following formula:

[0067]

[0068] Where P is the power of the reflected signal and P0 is the background noise power. It is assumed here that in a steady state, the background noise power inside the casing is equal everywhere and is a constant value.

[0069] The reflected signal power P is determined by the following formula:

[0070]

[0071] Where A is the amplitude of the reflected signal, f is the frequency of the reflected signal, the frequency of ultrasound propagation in the medium is generally constant, and Z is the acoustic impedance of the insulating medium.

[0072] The reflected signal amplitude A is related to the initial transmitted signal amplitude A0, the detection frequency f, and the reflection depth d. Here, the frequency attenuation correction factor is defined , reflection depth attenuation correction factor ,but

[0073]

[0074] Where α and β are correction coefficients related to the material, which are obtained by fitting a single variable orthogonal experiment.

[0075] The correction coefficient is obtained by fitting a single variable orthogonal experiment. For example, by detecting reflection signals of different frequencies at a fixed depth, α can be calculated, and by detecting reflection signals of different depths at a fixed frequency, β can be calculated. In general, the process of obtaining α and β is the same.

[0076] Here is an example of obtaining α. If there is a material at a depth of d, it is swept with signals of frequency f and 2f, and the intensity is obtained respectively. and Reflected signal, then:

[0077]

[0078] but

[0079]

[0080] Right now

[0081]

[0082] The probe can complete the above calculations, d is set to half of the maximum depth, the frequency f divides the range between the maximum detection frequency and the minimum detection frequency into five equal parts, and scans frequency by frequency. In fact, there is no limit to the form.

[0083] The acoustic impedance Z of the insulating medium is a fixed property of the insulating medium and is expressed by the following formula:

[0084]

[0085] Where ρ is the density of the medium, v is the ultrasonic longitudinal propagation velocity, and when the ultrasonic longitudinal wave propagates in an infinite isotropic medium, the longitudinal wave speed can be expressed as , E is the Young's modulus of the medium, and σ is the Poisson's ratio of the medium.

[0086] Combining the above formulas and substituting them into the signal-to-noise ratio (SNR) formula, we can get:

[0087]

[0088] Taking the signal-to-noise ratio (SNR) as the optimization target, the optimal ultrasonic detection frequency f that maximizes the signal-to-noise ratio (SNR) is selected for different depths d (0~dmax) to achieve efficient and comprehensive detection.

[0089] 3. Multi-frequency detection module uses a handheld multi-frequency detection ultrasonic probe to perform multi-level detection through ultrasonic longitudinal waves of multiple frequencies.

[0090] Reference Figure 2 The probe adjusts its frequency to perform multi-frequency sweeps. Low-frequency longitudinal ultrasonic waves are used to detect deep defects, such as large cracks and voids, while high-frequency longitudinal ultrasonic waves are used to detect shallow, fine cracks or bubbles. The probe can cover defects from deep to shallow in a single inspection, providing richer inspection information.

[0091] After determining the depth, the probe uses ultrasonic longitudinal waves at multiple frequencies to scan layer by layer, linearly combining the detection results at each frequency into a two-dimensional image. Specifically, the probe first uses low-frequency ultrasonic longitudinal waves to detect deep defects, then switches to high-frequency ultrasonic longitudinal waves based on a depth-frequency optimization function to detect shallow, small defects.

[0092] 4. The data processing module processes multi-frequency inspection signals in real time to generate a two-dimensional image. The probe's built-in data processing module analyzes signals collected at different frequencies, optimizes signal quality, and combines depth information to generate a clear two-dimensional image, which is displayed in real time on the user interface. This image clearly shows the specific location and size of defects, facilitating quick identification by inspectors.

[0093] In one embodiment, the present invention provides a handheld multi-frequency ultrasonic probe detection method, comprising the following steps:

[0094] Step 1: Start the handheld multi-frequency ultrasonic probe to detect the bottom wave and obtain the depth information of the casing to be inspected;

[0095] Step 2: Generate a depth-frequency correspondence function based on the depth information;

[0096] Step 3: Perform multi-frequency sweeping and refined detection;

[0097] Step 4: Real-time display and data recording.

[0098] Optionally, step 2 includes:

[0099] Step 2.1: Based on the depth information and casing diameter of the casing to be inspected obtained by bottom wave detection, the data processing module collects and processes the relevant data and obtains the material correction coefficients α and β;

[0100] Step 2.2: Based on the processed data, the handheld multi-frequency detection ultrasonic probe automatically generates a depth-frequency correspondence function.

[0101] Optionally, in step 3, the ultrasonic probe first uses low-frequency ultrasonic longitudinal waves to detect deep defects, and then switches to high-frequency ultrasonic longitudinal waves according to the depth-frequency optimization function to detect shallow small defects.

[0102] Optionally, step 3 includes:

[0103] Step 3.1: First, use low-frequency ultrasonic longitudinal waves to conduct deep detection to preliminarily find defects inside the casing;

[0104] Step 3.2: According to the indication of the depth-frequency correspondence function, switch to a higher frequency for layer-by-layer inspection. Scan the casing layer by layer according to the depth-frequency correspondence function until the entire inspection area is scanned. The specific type of defect is determined by the inspector based on the inspection results.

[0105] Optionally, step 4 includes:

[0106] Step 4.1: During the inspection process, the ultrasonic probe displays the inspection results in real time. The inspector can see the location and size of defects at different depths through the display screen of the ultrasonic probe, so as to make timely judgments and adjustments.

[0107] Step 4.2: All test data will be recorded in real time and stored in the probe's local storage device, and can be subsequently viewed, analyzed, and archived through supporting software or equipment.

[0108] In one embodiment, taking a bushing of a certain voltage level as an example, the present invention provides a detection method using a handheld multi-frequency ultrasonic probe, comprising the following steps:

[0109] Step 1: Start the handheld multi-frequency ultrasonic probe to detect the bottom wave and obtain the depth information of the casing to be inspected;

[0110] Step 1.1: First, connect the handheld multi-frequency detection ultrasonic probe to the power supply or ensure that it is fully charged, and press the start button to put the probe into working state.

[0111] Step 1.2: Set the parameters of the low-frequency ultrasonic signal using the control panel or accompanying software of the handheld multi-frequency ultrasonic probe based on the type and size of the casing to be inspected and the expected defect types. These expected defect types include, on the one hand, bubbles caused by incomplete degassing during the casing production process, microcracks caused by excessive residual stress, and, on the other hand, microcracks caused by stress fluctuations or vibrations during operation due to thermal cycling. For example, an initial low-frequency ultrasonic signal (e.g., 1 MHz) is manually set based on the specific conditions of the casing to be inspected. In this example, a ±800 kV valve-side dry-type casing made of a certain epoxy-impregnated paper material with a diameter of 640 mm is inspected for bubbles and microcracks.

[0112] Step 1.3: The handheld multi-frequency detection ultrasonic probe transmits a low-frequency ultrasonic signal with set parameters, such as a sinusoidal signal modulated by a Hanning window, such as Figure 4 The signal penetrates the insulation layer of the casing and reflects back to the probe. By calculating the time delay of the reflected wave (i.e., the time difference between signal transmission and reception), the depth information inside the casing to be inspected is obtained, providing a depth reference for subsequent multi-frequency sweeps.

[0113] Step 2: Generate depth-frequency correspondence function;

[0114] Step 2.1: Based on the depth information of the casing to be inspected and the diameter obtained by bottom wave detection, the data processing module inside the probe collects and processes relevant data to obtain the material correction coefficients α and β;

[0115] Step 2.2: Based on the processed data, the handheld multi-frequency ultrasonic probe automatically generates a depth-frequency function. This function matches different inspection depths with the optimal ultrasonic longitudinal wave frequency to ensure the best inspection effect at each depth.

[0116] Step 3: Perform multi-frequency sweeping and refined detection;

[0117] Step 3.1: First, use low-frequency ultrasonic longitudinal waves (such as 1 MHz) to conduct in-depth detection to preliminarily find defects inside the casing, such as cracks or voids.

[0118] Step 3.2: Based on the depth-frequency correspondence function, switch to a higher frequency (such as 2 MHz, 3 MHz, or higher) for layer-by-layer inspection. Due to the piezoelectric effect, by inputting electrical signals of varying frequencies into the wafer, the wafer outputs mechanical wave signals of varying frequencies. In this embodiment, the frequency range is 1 MHz to 5 MHz, depending on the wafer. High-frequency longitudinal ultrasonic waves offer higher resolution, enabling the detection of shallow, fine cracks or microbubbles. The probe scans the casing layer by layer according to the depth-frequency correspondence function until the entire inspection area is completely scanned. The inspector determines the defect type based on the test results.

[0119] Step 4: Real-time display and data recording;

[0120] Step 4.1: During the inspection process, the probe will display the inspection results in real time. The inspector can clearly see the location and size of defects at different depths through the probe display, allowing timely judgment and adjustment.

[0121] Step 4.2: All test data is recorded in real time and stored in the probe's local storage device. This data includes the test signal at each frequency, the reflected signal intensity corresponding to different depth-width relationships, and the generated 2D image. This data can then be reviewed, analyzed, and archived using supporting software or equipment. Figure 5 An example of the detection result of a point with or without a reflected signal is given. The probe is placed at the center of the material surface in the two-dimensional simulation model (5, 0). The depth of the point from the probe is d = 5μs * 2600 / 2 = 6.5cm, so the coordinates of the point are (5, -6.5). The propagation speed of ultrasound in epoxy is constant at 2600m / s. The depth of the reflection area can be calculated based on the reflection time. The left side of the figure shows no reflection signal, and the right side shows a reflection signal at a depth of 6.5cm. The waveform corresponding to the beginning of the time axis in both figures is the initial wave, that is, the incident wave, and the waveform corresponding to the end of the time axis is the bottom wave. The reflection signals of multiple points can form a two-dimensional image, such as Figure 6 As shown, it is composed of one-dimensional images, which can integrate the accuracy of high-frequency signals and the depth of low-frequency signals. The color bars in the figure represent the signal reflection intensity. The darker the color, the stronger the reflection signal, including small gaps with a depth of 20mm and large gaps with a depth of 160.

[0122] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0123] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0124] It should be understood by those skilled in the art that the above embodiments are merely for the purpose of illustrating the present invention clearly, and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and these changes or modifications are still within the scope of the present invention.

Claims

1. A handheld multi-frequency detection ultrasonic probe, characterized in that: The ultrasonic probe comprises: The bottom wave detection module is used to detect the bottom wave by using low-frequency ultrasonic longitudinal waves to obtain the depth information of the casing under test before the multi-frequency sweep is formally carried out. An optimization module is used to generate a depth-frequency optimization function to automatically match the optimal detection frequency at different depths according to the maximum depth; The multi-frequency detection module uses a handheld multi-frequency detection ultrasonic probe to perform multi-level detection through ultrasonic longitudinal waves of multiple frequencies; The data processing module is used to process the multi-frequency detection signals in real time to generate a two-dimensional image.

2. The ultrasonic probe according to claim 1, wherein: Preferably, in the optimization module, the depth-frequency optimization function automatically matches the corresponding optimal detection frequency according to different detection depths.

3. The ultrasonic probe according to claim 1, wherein: The data processing module can combine detection signals at multiple frequencies into a two-dimensional image, and display and record detection results at different depths in real time.

4. The ultrasonic probe according to any one of claims 1 to 3, wherein: The probe has a handheld and portable design, is suitable for on-site detection, and is suitable for detecting casings with complex geometric structures.

5. The ultrasonic probe according to claim 1, wherein: The ultrasonic probe includes a plurality of ultrasonic chips, which generate ultrasonic longitudinal wave signals of different frequencies through the piezoelectric effect of the ultrasonic chips. The ultrasonic longitudinal wave signals are used to perform layered detection on the inside of the casing under test.

6. A handheld multi-frequency ultrasonic probe detection method, characterized in that: The following steps are involved: Step 1: Start the handheld multi-frequency ultrasonic probe to detect the bottom wave and obtain the depth information of the casing to be inspected; Step 2: Generate a depth-frequency correspondence function based on the depth information; Step 3: Perform multi-frequency sweeping and refined detection; Step 4: Real-time display and data recording.

7. The ultrasonic probe according to claim 6, wherein: Step 2 includes: Step 2.1: Based on the depth information and casing diameter of the casing to be detected obtained by bottom wave detection, the data processing module collects and processes the relevant data and obtains the correction coefficient of the material α 、 β ; Step 2.2: Based on the processed data, the handheld multi-frequency detection ultrasonic probe automatically generates a depth-frequency correspondence function.

8. The ultrasonic probe according to claim 7, wherein: In step 3, the ultrasonic probe first uses low-frequency ultrasonic longitudinal waves to detect deep defects, and then switches to high-frequency ultrasonic longitudinal waves according to the depth-frequency optimization function to detect shallow small defects.

9. The ultrasonic probe according to claim 8, wherein: Step 3 includes: Step 3.1: First, use low-frequency ultrasonic longitudinal waves to conduct deep detection to preliminarily find defects inside the casing; Step 3.2: According to the indication of the depth-frequency correspondence function, switch to a higher frequency for layer-by-layer inspection. Scan the casing layer by layer according to the depth-frequency correspondence function until the entire inspection area is scanned. The specific type of defect is determined by the inspector based on the inspection results.

10. The ultrasonic probe according to claim 9, wherein: Step 4 includes: Step 4.1: During the inspection process, the ultrasonic probe displays the inspection results in real time. The inspector can see the location and size of defects at different depths through the display screen of the ultrasonic probe, so as to make timely judgments and adjustments; Step 4.2: All detection data will be recorded in real time and stored in the local storage device of the probe.

Images