Paint film flatness detection method, device, equipment and storage medium

Abstract

The application provides a paint film flatness detection method, device, equipment and storage medium, which can be used in the technical field of paint film detection. In the scheme, first, based on an ultrasonic detection device, a first ultrasonic signal emitted to a detection position of a part to be detected and a second ultrasonic signal received after transmitting the detection position are obtained. Then, according to the first ultrasonic signal and the second ultrasonic signal, the attenuation coefficient and the delay of the acoustic transmission signal are calculated. Finally, according to the attenuation coefficient, the delay, and the average attenuation coefficient and the average delay of the acoustic transmission signal of the normal flat paint film obtained in advance, the paint film flatness of the detection position is determined. The paint film flatness detection method of the application can break away from the dependence on the light environment and detect the paint film flatness of the part at any time and anywhere, thereby improving the continuity and timeliness of the paint film flatness detection.

Description

Technical Field

[0001] This application relates to the field of paint film testing technology, and in particular to a method, apparatus, equipment and storage medium for testing the smoothness of paint film. Background Technology

[0002] Paint surface quality inspection refers to the inspection of the paint film applied to the surface of parts to determine whether the paint film meets the requirements. Among them, the smoothness of the paint film surface is an important appearance inspection feature.

[0003] Conventional paint film inspection solutions mainly include four categories: manual inspection, microscopic inspection, illumination box inspection, and machine vision inspection. Manual inspection primarily involves visually observing or touching the paint film surface to determine if defects such as foreign objects, scratches, or pitting are present. Microscopic inspection uses a microscope to magnify and observe the paint film surface, detecting minute defects such as burrs. Illumination box inspection involves observing and inspecting the paint film under specific light sources to simulate different lighting conditions, helping to better determine the uniformity of the paint film's surface quality. Machine vision inspection uses microscopes, illumination boxes, or high-resolution cameras to acquire image data, and then uses machine learning to infer and determine whether there are any anomalies on the paint film surface.

[0004] However, the conventional paint film inspection solutions mentioned above mainly rely on optical inspection, which places high demands on the ambient light intensity and the resolution of the optical equipment. Summary of the Invention

[0005] This application provides a method, apparatus, equipment, and storage medium for testing the smoothness of paint film, in order to solve the technical problem that the testing of paint film smoothness in the prior art relies too much on the light environment.

[0006] In a first aspect, this application provides a method for testing the smoothness of a paint film, comprising:

[0007] The ultrasonic testing device acquires a first ultrasonic signal emitted from the detection position of the part under test and a second ultrasonic signal received after passing through the detection position.

[0008] Based on the first ultrasonic signal and the second ultrasonic signal, calculate the attenuation coefficient and delay of the acoustic transmission signal;

[0009] The smoothness of the paint film at the detection location is determined based on the attenuation coefficient, the delay, and the average attenuation coefficient and average delay of the acoustic transmission signal of a normally smooth paint film obtained in advance.

[0010] In one possible design of the first aspect, determining the smoothness of the paint film at the detection location based on the attenuation coefficient, the delay, and the average attenuation coefficient and average delay of the acoustic transmission signal of a pre-acquired normal smooth paint film includes:

[0011] If the attenuation coefficient is less than a first preset fluctuation range of the average attenuation coefficient, and the delay is within a second preset fluctuation range of the average delay, then it is determined that the paint film surface at the detection location is smooth and contains air bubbles.

[0012] If the attenuation coefficient is less than the first preset floating range of the average attenuation coefficient, and the delay is less than the second preset floating range of the average delay, then it is determined that there is a protrusion on the surface of the paint film at the detection position and that there are air bubbles inside.

[0013] If the attenuation coefficient is less than the first preset floating range of the average attenuation coefficient, and the delay is greater than the second preset floating range of the average delay, then it is determined that there is a depression on the surface of the paint film at the detection position and that there are air bubbles inside.

[0014] If the attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient, and the delay is greater than the second preset fluctuation range of the average delay, then it is determined that there is a depression on the surface of the paint film at the detection position, and there are no air bubbles inside.

[0015] If the attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient, and the delay is less than the second preset fluctuation range of the average delay, then it is determined that there is a protrusion on the surface of the paint film at the detection position, and there are no air bubbles inside.

[0016] If the attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient and the delay is within the second preset fluctuation range of the average delay, then the paint film surface at the detection position is determined to be smooth and uniform inside.

[0017] In one possible design of the first aspect, the method further includes:

[0018] If the delay is less than the second preset floating range of the average delay, and the difference between the delay and the minimum value of the second preset floating range is greater than the first preset difference, then it is determined that the paint film thickness at the detection position is uneven.

[0019] If the difference between the attenuation coefficient and the upper or lower limit of the first preset floating range of the average attenuation coefficient is greater than the second preset difference, and the difference between the delay and the upper or lower limit of the second preset floating range is greater than the third preset difference, then it is determined that the paint film surface at the detection position is uneven and contains solid impurities.

[0020] In one possible design of the first aspect, calculating the attenuation coefficient and delay of the acoustic transmission signal based on the first ultrasonic signal and the second ultrasonic signal includes:

[0021] The first ultrasonic signal is subjected to Fourier transform to obtain the first amplitude and first phase at a preset frequency;

[0022] The second ultrasonic signal is subjected to Fourier transform to obtain the second amplitude and the second phase at the preset frequency;

[0023] The attenuation coefficient is calculated based on the first amplitude and the second amplitude, and the delay is calculated based on the first phase and the second phase.

[0024] In one possible design of the first aspect, calculating the attenuation coefficient based on the first amplitude and the second amplitude includes:

[0025] The ratio of the second amplitude to the first amplitude is calculated and used as the attenuation coefficient.

[0026] In one possible design of the first aspect, calculating the delay based on the first phase and the second phase includes:

[0027] The difference between the second phase and the first phase is calculated as the delay.

[0028] In one possible design of the first aspect, acquiring a first ultrasonic signal emitted from a detection location of the part to be tested and a second ultrasonic signal received after passing through the detection location via an ultrasonic testing device includes:

[0029] The acoustic air-coupled transmitting probe of the ultrasonic detection device is controlled to transmit the first ultrasonic signal toward the detection position;

[0030] The second ultrasonic signal transmitted from the detection position is received by the acoustic air-coupled receiving probe of the ultrasonic testing device.

[0031] Secondly, this application provides a paint film smoothness testing device, comprising:

[0032] The acquisition module is used to acquire, through the ultrasonic testing device, a first ultrasonic signal emitted at the detection position of the part to be tested and a second ultrasonic signal received after passing through the detection position;

[0033] The processing module is used to calculate the attenuation coefficient and delay of the acoustic transmission signal based on the first ultrasonic signal and the second ultrasonic signal;

[0034] The processing module is also used to determine the smoothness of the paint film at the detection location based on the attenuation coefficient, the delay, and the average attenuation coefficient and average delay of the acoustic transmission signal of a normally smooth paint film obtained in advance.

[0035] Thirdly, this application provides an electronic device, including: a processor, and a memory communicatively connected to the processor;

[0036] The memory stores computer-executed instructions;

[0037] The processor executes computer execution instructions stored in the memory to implement the paint film smoothness detection method as described in any of the first aspects.

[0038] Fourthly, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the paint film smoothness detection method as described in any of the first aspects.

[0039] Fifthly, this application provides a computer program product, the computer program product including a computer program, which, when executed by a processor, is used to implement the paint film smoothness detection method according to any one of the first aspects.

[0040] This application provides a method, apparatus, equipment, and storage medium for detecting the smoothness of a paint film. The method is applied in the field of paint film inspection. First, after activation, the ultrasonic testing device emits a first ultrasonic signal at the detection location of the part to be tested. After successfully transmitting through the detection location, a second ultrasonic signal is generated. Then, based on the first and second ultrasonic signals, the attenuation coefficient and delay of the transmitted sound signal are calculated. Finally, the calculated attenuation coefficient and delay are compared with the average attenuation coefficient and delay of the transmitted sound signal of a normally smooth paint film obtained beforehand to determine the smoothness of the detection location of the part to be tested. By comparing the average attenuation coefficient and delay of the transmitted sound signal of a normal paint film with the corresponding attenuation coefficient and delay of the paint film to be tested, in addition to judging the surface smoothness of the paint film, it can also detect the uniformity of the paint film on the part and the presence of impurities and bubbles in the paint film, thus broadening the detection range. Furthermore, the transmission and reception of ultrasonic signals are less affected by the environment, allowing for the detection of the smoothness of the paint film on parts anytime and anywhere, thereby eliminating the strong dependence of existing detection methods on ambient light and improving detection efficiency. Attached Figure Description

[0041] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0042] Figure 1 A schematic diagram illustrating the application scenario of the paint film smoothness testing method provided in this application;

[0043] Figure 2 This is a flowchart illustrating Example 1 of the paint film smoothness testing method provided in this application;

[0044] Figure 3 This is a schematic diagram of the acoustic testing principle for the paint film surface provided in this application;

[0045] Figure 4 This is a schematic flowchart of Example 2 of the paint film smoothness testing method provided in this application;

[0046] Figure 5 This is a flowchart illustrating Example 3 of the paint film smoothness testing method provided in this application;

[0047] Figure 6 This is a schematic flowchart of Example 4 of the paint film smoothness testing method provided in this application;

[0048] Figure 7 This is a flowchart illustrating Example 5 of the paint film smoothness testing method provided in this application;

[0049] Figure 8 This is a schematic flowchart of Example 6 of the paint film smoothness testing method provided in this application;

[0050] Figure 9 This is a flowchart illustrating Example 7 of the paint film smoothness testing method provided in this application.

[0051] Figure 10 This is a schematic diagram of the structure of Embodiment 1 of the paint film smoothness testing device provided in this application;

[0052] Figure 11 This is a schematic diagram of the electronic device for detecting the smoothness of the paint film provided in this application.

[0053] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0054] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0055] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of the relevant data must comply with relevant laws, regulations and standards, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0056] Figure 1 This is a schematic diagram illustrating an application scenario for the paint film smoothness testing method provided in this application. For example... Figure 1 As shown, the application scenario of the solution provided in this application includes a paint film detection data processing device 100, an ultrasonic detection device 101, and a part to be tested 102.

[0057] The ultrasonic testing device 101 is mainly used to inspect the surface of the paint film on parts to determine whether there are defects such as foreign objects, scratches, and burrs on the surface of the paint film. Although Figure 1 Only one ultrasonic testing device 101 is shown, but it should be understood that two or more ultrasonic testing devices 101 may exist. The ultrasonic testing device 101 is connected to the paint film inspection data processing device 100 via a wired connection and to the part under test 102 via a wireless connection.

[0058] The paint film inspection data processing device 100 is mainly used to receive paint film inspection data transmitted from the ultrasonic inspection device 101, and to analyze and process the paint film inspection data through a preset algorithm to obtain the surface inspection results of the paint film on the parts. Although Figure 1 Only one paint film inspection data processing device 100 is shown, but it should be understood that two or more paint film inspection data processing devices 100 may exist. The paint film inspection data processing device 100 is connected to the ultrasonic inspection device 101 via a wired connection.

[0059] The part under test 102 is mainly used to receive and reflect the detection signals sent by the ultrasonic testing device 101, providing data support to the paint film detection data processing device 100. The parts under test have paint films of different areas, and the coating positions of the paint films on the surface of the parts also vary. For example, the coating areas and positions of paint films on the surfaces of various furniture, vehicles, and industrial equipment differ. Although... Figure 1 Only one part under test 102 is shown, but it should be understood that there may be two or more parts under test 102. The part under test 102 is connected to the ultrasonic testing device 101 wirelessly.

[0060] After the ultrasonic testing device 101 is successfully started, it sends a testing signal to the part under test 102. Upon receiving the testing signal from the ultrasonic testing device 102, the part under test 102 sends a corresponding testing result signal back to the ultrasonic testing device 102. When the ultrasonic testing device 101 receives the testing result signal returned by the part under test 102, it sends testing data related to the testing signal and the testing result signal to the paint film testing data processing device 100. Upon receiving the testing data, the paint film testing data processing device 100 analyzes and calculates the testing data according to a preset algorithm to obtain the paint film testing result of the part under test.

[0061] However, with economic development and the improvement of people's living standards, the quality of various parts has received considerable attention. Among these, paint film inspection results are an important criterion for judging the quality of parts. Therefore, paint film inspection methods urgently need improvement, and the accuracy of paint film inspection results needs to be further enhanced.

[0062] To address this situation, the most common approach is optical inspection. For example, during paint film inspection, manual methods involve visually observing or touching the paint film surface to determine for defects such as foreign objects, scratches, and pitting. Microscopic inspection magnifies the paint film surface to detect defects. Illumination box inspection observes and inspects the paint film under specific light sources to simulate different lighting conditions, helping to better determine the uniformity of the paint film surface quality. Machine vision inspection uses microscopes, illumination boxes, or high-resolution cameras to acquire paint film image data, and then uses machine learning to infer and determine whether there are any anomalies on the paint film surface.

[0063] However, the above-mentioned solutions have the following problems: They are highly dependent on the lighting environment during paint film inspection. In poor lighting conditions, the inspection process cannot proceed, easily affecting efficiency. Furthermore, when dealing with minor surface imperfections, commonly used paint film inspection methods place high demands on optical equipment; otherwise, accurate results cannot be obtained. Additionally, existing paint film inspection methods only provide surface-level results and cannot determine the uniformity of the paint film's interior. Therefore, commonly used paint film inspection methods cannot perform surface inspections in all weather conditions, resulting in poor timeliness.

[0064] To address the aforementioned issues, the inventors, during their research on the low timeliness of paint film inspection due to excessive reliance on lighting conditions, discovered that optimal lighting is required during the paint film inspection process. Furthermore, high-resolution optical equipment is necessary to detect minor surface imperfections. This process relies on the quality of the lighting environment as the standard for initiating inspection, easily leading to reduced timeliness. Therefore, the inventors considered whether paint film inspection could be conducted without dependence on lighting conditions, enabling all-weather surface inspection. This involves utilizing the principle that ultrasound is highly sensitive to changes in the physical properties of the medium it penetrates. Changes in material density, thickness, and other physical quantities will affect the propagation time, attenuation, and harmonic waveform of ultrasound waves, thus detecting anomalies such as unevenness and non-uniformity on the paint film surface of parts. Specifically, an acoustic air-coupled transmitting probe emits ultrasonic signals towards the paint film side of the part under test, while an acoustic air-coupled receiving probe receives the ultrasonic signals projected through the "air-paint film-part-air" medium on the other side of the part. The emitted and received ultrasonic signals are processed and analyzed to determine whether the area near the corresponding paint film is normal. This method for detecting the surface smoothness of a part's paint film based on acoustic projection can be used for all-weather inspection, eliminating dependence on ambient light conditions during paint film inspection. Furthermore, this method can utilize ultrasonic waves of different frequencies to detect defects and anomalies at different scales on the paint film surface, thus overcoming the limitation of requiring high resolution optical equipment.

[0065] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0066] Figure 2 This is a schematic flowchart of Example 1 of the paint film smoothness testing method provided in this application. Figure 2 As shown, the procedure for this paint film smoothness testing method may include:

[0067] S201: Using an ultrasonic testing device, acquire the first ultrasonic signal emitted at the detection position of the part to be tested and the second ultrasonic signal received after passing through the detection position.

[0068] In this step, the ultrasonic testing device is mainly used to transmit ultrasonic signals at the testing position of the part to be tested and to receive ultrasonic signals after they are projected at the testing position.

[0069] After the part to be tested is positioned, the ultrasonic testing device will emit a first ultrasonic signal toward the paint film side of the part. This first ultrasonic signal can be specifically represented as... Where p0 represents the ultrasonic amplitude, j represents the ultrasonic phase, ω0 represents the ultrasonic frequency, and t represents the moment when the ultrasonic wave emits the first ultrasonic signal.

[0070] The ultrasonic testing device receives a second ultrasonic signal transmitted through the medium of "air-paint film-part-air" on the other side of the testing location of the part to be tested. This second ultrasonic signal can be specifically represented as... Where α represents the attenuation coefficient. Indicates time delay.

[0071] Based on the transmitted first ultrasonic signal and the received second ultrasonic signal, the attenuation coefficient and delay of the acoustic transmission signal will be calculated next.

[0072] Figure 3 This is a schematic diagram illustrating the principle of acoustic testing of the paint film surface provided in this application. Figure 3 As shown, the ultrasonic testing device includes an acoustic air-coupled transmitting probe and multiple acoustic air-coupled receiving probes. The acoustic air-coupled transmitting probe emits a first ultrasonic signal towards the testing location of the part under test. After passing through the air-coating-part-air medium, the multiple acoustic air-coupled transmitting probes receive a second ultrasonic signal on the other side of the testing location. Subsequently, based on the obtained first and second ultrasonic signals, it is determined whether there are abnormalities such as protrusions, bubbles, or dents at the testing location of the part under test.

[0073] S202: Calculate the attenuation coefficient and delay of the acoustic transmission signal based on the first and second ultrasonic signals.

[0074] In this step, the transmitted and received signals obtained in step S201 are used as the first and second ultrasonic signals, respectively. The attenuation coefficient and delay of the acoustic transmission signal are calculated using the Fourier transform method. The Fourier transform is an important signal analysis method that can convert a signal in the time domain to the frequency domain to obtain the signal's frequency information.

[0075] For example, the first ultrasonic signal emitted by the ultrasonic testing device is represented as: The second ultrasonic signal received by the ultrasonic testing device after the testing position of the part under test is represented as: Next, the first ultrasound signal Second ultrasound signal Perform a Fourier transform operation to obtain the signal amplitude P at the ultrasonic frequency ω0. T and P R Ultrasonic phase and Finally, the attenuation coefficient α of the acoustic transmission signal is P R With P T The ratio of the acoustic transmission signal to the delay of the signal.

[0076] S203: Determine the smoothness of the paint film at the detection location based on the attenuation coefficient, delay, and the average attenuation coefficient and average delay of the acoustic transmission signal of a normally smooth paint film obtained in advance.

[0077] In this step, based on step S202, the attenuation coefficient and delay of the detection position of the part under test are obtained. The next operation is to compare and analyze the obtained attenuation coefficient and delay with the average attenuation coefficient and delay of the acoustic transmission signal of a normal smooth paint film obtained in advance, and determine the smoothness of the paint film at the detection position of the part under test based on the comparison results.

[0078] The method for pre-obtaining the average attenuation coefficient and average delay of the acoustic transmission signal of a normal paint film involves using an ultrasonic testing device to repeatedly test parts covered by a normal paint film, obtaining multiple attenuation coefficient and delay values. Specifically, the ultrasonic testing device emits a first ultrasonic signal to the part covered by the normal paint film and receives a second ultrasonic signal on the other side of the part. Fourier transforms are performed on the first and second ultrasonic signals respectively to obtain the amplitude and phase of the two signals at their corresponding ultrasonic frequencies. The attenuation coefficient value corresponding to this test is determined based on the ratio of the amplitude of the second ultrasonic signal to that of the first ultrasonic signal. The delay value is determined based on the phase difference between the second and first ultrasonic signals.

[0079] To enhance robustness, the lengths of the transmitted and received signals from the ultrasonic testing device were varied multiple times, and the attenuation coefficient and delay values ​​for parts with normal paint film coverage were obtained repeatedly. Based on the obtained multiple attenuation coefficient and delay values, their mean and standard deviation were calculated respectively, and finally, the mean attenuation coefficient of the acoustic transmission signal of the normal paint film was obtained. and mean delay Where, δ α and These represent the fluctuation range of the attenuation coefficient and the delay, respectively.

[0080] The paint film smoothness detection method provided in this embodiment mainly involves determining the paint film smoothness at the detection location of the part under test based on the first ultrasonic signal emitted and the second ultrasonic signal received by the ultrasonic testing device. Specifically, by utilizing acoustic methods, the smoothness of the paint film surface and the uniformity of the paint film interior can be detected in all weather conditions, eliminating the influence of environmental factors on paint film smoothness detection and increasing the flexibility of the detection time. Simultaneously, by comparing and analyzing the dynamic values ​​of the attenuation coefficient and delay of sound transmission of a normal paint film with the corresponding attenuation coefficient and delay of the paint film under test, the efficiency and accuracy of paint film smoothness detection are improved.

[0081] Figure 4 This is a schematic flowchart of Example 2 of the paint film smoothness testing method provided in this application. Figure 4 As shown, the smoothness of the paint film at the detection location is determined based on the attenuation coefficient, delay, and the average attenuation coefficient and average delay of the acoustic transmission signal of a normally smooth paint film obtained in advance. This paint film smoothness detection method also includes the following steps:

[0082] S401: If the attenuation coefficient is less than the first preset floating range of the average attenuation coefficient and the delay is within the second preset floating range of the average delay, then it is determined that the paint film surface at the detection position is smooth and contains air bubbles.

[0083] In this step, based on the obtained attenuation coefficient and delay value, during the comparison and analysis with the average attenuation coefficient and average delay value of the acoustic transmission signal of a normal smooth paint film obtained in advance, if the calculated attenuation coefficient is less than the first preset floating range of the average attenuation coefficient and the delay is within the second preset floating range of the average delay value, it can be determined that the paint film surface at the detection position of the part under test is smooth and contains air bubbles.

[0084] The first preset fluctuation range of the average attenuation coefficient is determined based on the attenuation coefficient results after multiple tests of a normal, smooth paint film by an ultrasonic testing device. The first preset fluctuation range is a range of numerical variation set based on the average attenuation coefficient. For example, if the average attenuation coefficient is A and the fluctuation range is a, then the first preset fluctuation range of the average attenuation coefficient is A±a, that is, the first preset fluctuation range of the average attenuation coefficient is greater than or equal to Aa and less than or equal to A+a.

[0085] The second preset fluctuation range of the average delay is determined based on the delay results of multiple tests conducted by the ultrasonic testing device on a normal, smooth paint film. The second preset fluctuation range is a range of values ​​that can be adjusted based on the average delay. For example, if the average delay is B and the fluctuation range is b, then the second preset fluctuation range of the average delay is B±b, meaning that the second preset fluctuation range of the average delay is greater than or equal to Bb and less than or equal to B+b.

[0086] If the measured attenuation coefficient is less than the first preset fluctuation range of the average attenuation coefficient, it indicates that the first ultrasonic signal underwent scattering during its passage through the detection location of the part under test. Some ultrasonic signals changed their propagation path, and their intensity weakened upon reaching the other side of the detection location, meaning that air bubbles exist inside the detection location of the part under test. Simultaneously, if the measured delay value is within the second preset fluctuation range of the average delay, it indicates that there are no abnormal protrusions or depressions at the detection location of the part under test, thus confirming that the detection location is smooth. In summary, it can be determined that the paint film surface at the detection location of the part under test is smooth, but air bubbles are present inside.

[0087] S402: If the attenuation coefficient is less than the first preset floating range of the average attenuation coefficient and the delay is less than the second preset floating range of the average delay, then it is determined that there is a protrusion on the surface of the paint film at the detection position and there are bubbles inside.

[0088] In this step, based on the obtained attenuation coefficient and delay value, during the comparison and analysis with the average attenuation coefficient and average delay value of the acoustic transmission signal of a normal smooth paint film obtained in advance, if the calculated attenuation coefficient is less than the first preset fluctuation range of the average attenuation coefficient and the delay is less than the second preset fluctuation range of the average delay value, it can be determined that there is a protrusion on the surface of the paint film at the detection position and that there are air bubbles inside.

[0089] The explanation of the first preset floating range of the average attenuation coefficient and the second preset floating range of the average delay can be found in step S401, and will not be repeated here.

[0090] If there is a protrusion at the detection location of the part under test, the propagation path of the first ultrasonic signal emitted by the ultrasonic testing device in the air will be reduced, while the propagation path inside the part under test will be increased, i.e., the propagation path in the solid will be increased. Based on the principle that sound travels faster in solids than in air, the time it takes for the signal to reach the other side of the detection location after transmission will be shortened.

[0091] If the measured attenuation coefficient is less than the first preset fluctuation range of the average attenuation coefficient, it indicates that the first ultrasonic signal underwent scattering during its passage through the detection location of the part under test. Some ultrasonic signals changed their propagation path, and after transmission, their intensity weakened on the other side of the detection location, meaning that air bubbles exist inside the detection location of the part under test. Simultaneously, if the measured delay is less than the second preset fluctuation range of the average delay, it confirms that there is a protrusion on the paint film surface at the detection location. In summary, it can be determined that there is a protrusion on the paint film surface at the detection location of the part under test, and that air bubbles are present inside.

[0092] S403: If the attenuation coefficient is less than the first preset floating range of the average attenuation coefficient and the delay is greater than the second preset floating range of the average delay, then it is determined that there is a depression on the surface of the paint film at the detection position and that there are bubbles inside.

[0093] In this step, based on the obtained attenuation coefficient and delay value, during the comparison and analysis with the average attenuation coefficient and average delay value of the acoustic transmission signal of a normal smooth paint film obtained in advance, if the calculated attenuation coefficient is less than the first preset floating range of the average attenuation coefficient and the delay is greater than the second preset floating range of the average delay value, it can be determined that there is a depression on the surface of the paint film at the detection position and that there are air bubbles inside.

[0094] The explanation of the first preset floating range of the average attenuation coefficient and the second preset floating range of the average delay can be found in step S401, and will not be repeated here.

[0095] If there is a depression at the detection location of the part under test, the propagation path of the first ultrasonic signal emitted by the ultrasonic testing device increases in the air and decreases inside the part under test, i.e., the propagation path in the solid is reduced. Based on the principle that sound travels faster in solids than in air, the time it takes for the transmitted signal to reach the other side of the detection location on the part under test will be longer.

[0096] If the measured attenuation coefficient is less than the first preset fluctuation range of the average attenuation coefficient, it indicates that the first ultrasonic signal underwent scattering during its passage through the detection location of the part under test. Some ultrasonic signals changed their propagation path, and after transmission, their intensity weakened on the other side of the detection location, meaning that air bubbles exist inside the detection location of the part under test. Simultaneously, if the measured delay is greater than the second preset fluctuation range of the average delay, it confirms that there is a depression on the paint film surface at the detection location. In summary, it can be determined that there is a depression on the paint film surface at the detection location of the part under test, and that air bubbles are present inside.

[0097] S404: If the attenuation coefficient is within the first preset floating range of the average attenuation coefficient and the delay is greater than the second preset floating range of the average delay, then it is determined that there is a depression on the surface of the paint film at the detection position and no air bubbles inside.

[0098] In this step, based on the obtained attenuation coefficient and delay value, during the comparison and analysis with the average attenuation coefficient and average delay value of the acoustic transmission signal of a normal smooth paint film obtained in advance, if the calculated attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient and the delay is greater than the second preset fluctuation range of the average delay value, it can be determined that there is a depression on the surface of the paint film at the detection position and no air bubbles inside.

[0099] The explanation of the first preset floating range of the average attenuation coefficient and the second preset floating range of the average delay can be found in step S401, and will not be repeated here.

[0100] If air bubbles are present inside the detection location of the part under test, the first ultrasonic signal emitted by the ultrasonic testing device will be scattered when it encounters the air bubble. Some of the ultrasonic waves will change their propagation path, and the intensity of the ultrasonic waves reaching the other side of the detection location will be weakened after transmission. Therefore, the presence of air bubbles at the detection location of the part under test can be determined by comparing the obtained attenuation coefficient with the first fluctuation range of the pre-acquired average attenuation coefficient.

[0101] If the attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient, and the delay is greater than the second preset fluctuation range of the average delay, then it is determined that there is a depression on the surface of the paint film at the detection location, and there are no bubbles inside.

[0102] If the measured attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient, it indicates that the first ultrasonic signal did not undergo scattering during its passage through the detection location of the part under test, and the intensity remained almost unchanged after transmission to the other side of the detection location, meaning there are no air bubbles inside the detection location of the part under test. Simultaneously, if the measured delay is greater than the second preset fluctuation range of the average delay, it confirms that there is a depression on the paint film surface at the detection location. In summary, it can be determined that there is a depression on the paint film surface at the detection location of the part under test, and that there are no air bubbles inside.

[0103] S405: If the attenuation coefficient is within the first preset floating range of the average attenuation coefficient and the delay is less than the second preset floating range of the average delay, then it is determined that there is a protrusion on the surface of the paint film at the detection position and there are no bubbles inside.

[0104] In this step, based on the obtained attenuation coefficient and delay value, during the comparison and analysis with the average attenuation coefficient and average delay value of the acoustic transmission signal of a normal smooth paint film obtained in advance, if the calculated attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient and the delay is less than the second preset fluctuation range of the average delay value, it can be determined that there is a protrusion on the surface of the paint film at the detection position and no air bubbles inside.

[0105] The explanation of the first preset floating range of the average attenuation coefficient and the second preset floating range of the average delay can be found in step S401, and will not be repeated here.

[0106] If air bubbles are present inside the detection location of the part under test, the first ultrasonic signal emitted by the ultrasonic testing device will be scattered when it encounters the air bubble. Some of the ultrasonic waves will change their propagation path, and the intensity of the ultrasonic waves reaching the other side of the detection location will be weakened after transmission. Therefore, the presence of air bubbles at the detection location of the part under test can be determined by comparing the obtained attenuation coefficient with the first fluctuation range of the pre-acquired average attenuation coefficient.

[0107] If a protrusion exists at the detection location of the part under test, the propagation path of the first ultrasonic signal emitted by the ultrasonic testing device decreases in the air and increases inside the part, i.e., the propagation path increases in the solid. Based on the principle that sound travels faster in solids than in air, the time it takes for the transmitted signal to reach the other side of the detection location will be shortened. Therefore, the presence of a protrusion at the detection location can be determined by comparing the obtained delay value with a pre-acquired average delay within a second fluctuation range.

[0108] If the measured attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient, it indicates that the first ultrasonic signal did not undergo scattering during its passage through the detection location of the part under test, and the intensity remained almost unchanged after transmission to the other side of the detection location, meaning there are no air bubbles inside the detection location of the part under test. Simultaneously, if the measured delay is less than the second preset fluctuation range of the average delay, it confirms that there is a protrusion on the paint film surface at the detection location. In summary, it can be determined that there is a protrusion on the paint film surface at the detection location of the part under test, and there are no air bubbles inside.

[0109] S406: If the attenuation coefficient is within the first preset floating range of the average attenuation coefficient and the delay is within the second preset floating range of the average delay, then the surface of the paint film at the detection position is determined to be smooth and the interior is uniform.

[0110] In this step, based on the obtained attenuation coefficient and delay value, during the comparison and analysis with the average attenuation coefficient and average delay value of the acoustic transmission signal of a normal smooth paint film obtained in advance, if the calculated attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient and the delay is within the second preset fluctuation range of the average delay value, it can be determined that the paint film surface at the detection position is smooth and the interior is uniform.

[0111] The explanation of the first preset floating range of the average attenuation coefficient and the second preset floating range of the average delay can be found in step S401, and will not be repeated here.

[0112] If air bubbles are present inside the detection location of the part under test, the intensity of the ultrasonic waves reaching the other side of the detection location after transmission will be weakened. If there is a protrusion at the detection location of the part under test, the time it takes for the first ultrasonic signal emitted by the ultrasonic testing device to reach the other side of the detection location will be shortened. If there is a depression at the detection location of the part under test, the time it takes for the first ultrasonic signal emitted by the ultrasonic testing device to reach the other side of the detection location will be prolonged.

[0113] If the measured attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient, it indicates that there are no air bubbles inside the detection location of the part under test. Simultaneously, if the measured delay is within the second preset fluctuation range of the average delay, it confirms that there are no depressions or protrusions on the paint film surface at the detection location of the part under test. In summary, it can be determined that the paint film surface at the detection location of the part under test is smooth and uniform internally.

[0114] The paint film smoothness detection method provided in this embodiment mainly involves determining whether the paint film at the detection location is smooth based on the attenuation coefficient, delay, and the average attenuation coefficient and average delay of the acoustic transmission signal of a normally smooth paint film obtained in advance. This paint film smoothness detection method judges whether there are protrusions or depressions at the detection location of the part under test based on the change in delay value, and judges whether there are air bubbles inside the detection location of the part under test based on the change in attenuation coefficient value. The judgment principle used is simple, and it can apply acoustic detection to a small range of paint film detection, improving the efficiency and accuracy of paint film detection, thereby effectively solving the problem of light influence in existing paint film detection solutions.

[0115] Figure 5 This is a schematic flowchart of Example 3 of the paint film smoothness testing method provided in this application. Figure 5 As shown, based on any of the above embodiments, the paint film smoothness testing method further includes the following steps:

[0116] S501: If the delay is less than the second preset floating range of the average delay, and the difference between the delay and the minimum value of the second preset floating range is greater than the first preset difference, then it is determined that the paint film thickness at the detection position is uneven.

[0117] In this step, based on the obtained attenuation coefficient and delay value, a comparison analysis is performed with the average attenuation coefficient and average delay value of the acoustic transmission signal of a normally smooth paint film. If the calculated delay value is less than the second preset fluctuation range of the average delay value, it can be determined that there is a protrusion in the paint film at the detection location. If the calculated attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient, it can be determined that there are no air bubbles inside the paint film at the detection location. If the difference between the obtained delay value and the minimum value of the second preset fluctuation range is greater than the first preset difference, it can be further determined that the paint film thickness at the detection location is uneven.

[0118] The minimum value of the second preset floating range refers to the lower limit of the average delay value's floating range. The first preset difference is customized based on different parts to be tested, and its value is generally set to 1-2 times the second preset floating range. For example, if the second preset floating range of the average delay value is determined based on the delay results of multiple tests on a normal, smooth paint film using an ultrasonic testing device, and the average delay value is 2, and the second preset floating range is 0.5, then the second preset floating range of the average delay value is 2 ± 0.5, that is, the second preset floating range of the average delay value is greater than or equal to 1.5 and less than or equal to 2.5. Therefore, the minimum value of the second preset floating range is 1.5. The first preset difference can be set to 1-2 times the second preset floating range of 0.5, for example, set to 2 times the second preset floating range of 0.5, i.e., 1.

[0119] If the measured delay at the detection position of the part under test is 0.4, this value differs from the lower limit of the second preset fluctuation range of 1.5 by 1.1, which is 2.2 times the second preset fluctuation range of 0.5. Therefore, the difference of 1.1 between the delay of 0.4 at the detection position of the part under test and the lower limit of the second preset fluctuation range of 1.5 for the average delay is greater than the second preset difference of 1, indicating that the surface thickness of the paint film near the detection position of the part under test is significantly increased, that is, the paint film under test is thicker than the normal paint film. The propagation path of the ultrasonic wave in the air is reduced, while the propagation path in the solid is increased, and the delay is shortened, thus indicating that the paint film thickness near the detection position of the part under test is uneven.

[0120] Similarly, if the delay is greater than the second preset fluctuation range of the average delay, and the difference between the delay and the maximum value of the second preset fluctuation range is greater than the first preset difference, it can also be determined that the paint film thickness at the detection location is uneven. If the measured delay at the detection location of the part under test is 3.6, this value differs from the upper limit of the second preset fluctuation range of the average delay (2.5) by 1.1, which is 2.2 times the second preset fluctuation range of 0.5. Therefore, the difference of 1.1 between the delay of 3.6 at the detection location of the part under test and the upper limit of the second preset fluctuation range of the average delay (2.5) is greater than the second preset difference of 1, indicating that the surface thickness of the paint film near the detection location of the part under test is significantly reduced, that is, the paint film under test is thinner than the normal paint film, the ultrasonic wave propagation path in the air is increased, and the delay is longer, thus indicating that the paint film thickness near the detection location of the part under test is uneven.

[0121] S502: If the difference between the attenuation coefficient and the upper or lower limit of the first preset floating range of the attenuation coefficient is greater than the second preset difference, and the difference between the delay and the upper or lower limit of the second preset floating range is greater than the third preset difference, then it is determined that the paint film surface at the detection position is uneven and contains solid impurities.

[0122] In this step, based on the obtained attenuation coefficient and delay value, during the comparison and analysis with the average attenuation coefficient and average delay value of the acoustic transmission signal of a normal smooth paint film obtained in advance, if the difference between the upper or lower limit of the first preset floating range of the attenuation coefficient and the average attenuation coefficient is greater than the second preset difference, and the difference between the delay and the upper or lower limit of the second preset floating range is greater than the third preset difference, it can be determined that the paint film surface at the detection position of the part under test is uneven and contains solid impurities.

[0123] The upper and lower limits of the first preset floating range are determined based on the measurement of the paint film on normal parts. The second preset difference is customized based on different parts to be tested, and its value is generally set to 3-5 times the first preset floating range. For example, based on multiple tests of the paint film on normal parts, the average attenuation coefficient corresponding to the paint film on normal parts is 20, and the first preset floating range is 5. Then, the value range for subsequent comparison with the attenuation coefficient corresponding to the test position on the part to be tested is 20±5, that is, greater than or equal to 15 and less than or equal to 25. The upper limit of the first preset floating range is 25, and the lower limit of the first preset floating range is 15. The second preset difference is 3-5 times the first preset floating range of 5, for example, set to 15.

[0124] If the measured attenuation coefficient at the detection position of the part under test is 50, this value differs from the upper limit of the first preset floating range of 25 by 25. This difference is 5 times the first preset floating range of 5 and 10 greater than the second preset difference of 15. Therefore, the difference of 25 between the attenuation coefficient 50 at the detection position of the part under test and the upper limit of the first preset floating range of 25 by 25 is greater than the second preset difference of 15.

[0125] The upper or lower limit of the second preset floating range is determined based on the measurement of the paint film on normal parts. The third preset difference is customized based on different parts to be tested, and its value is generally set to 3-5 times the second preset floating range. For example, based on multiple tests of the paint film on normal parts, the average delay corresponding to the paint film on normal parts is 0.3, and the second preset floating range is 0.1. Then, the value range for comparison with the delay corresponding to the detection position of the part to be tested is 0.3 ± 0.1, that is, greater than or equal to 0.2 and less than or equal to 0.4. The upper limit of the second preset floating range is 0.4, and the lower limit of the second preset floating range is 0.2. The third preset difference is 3-5 times the second preset floating range of 0.1, for example, set to 0.5.

[0126] If the measured delay at the detection position of the part under test is 1, this value differs from the upper limit of the first preset floating range of 0.4 by 0.6. This difference is 6 times the first preset floating range of 0.1 and 0.1 greater than the third preset difference of 0.5. Therefore, the difference of 0.6 between the delay of 1 at the detection position of the part under test and the upper limit of the second preset floating range of 0.4 is greater than the third preset difference of 0.5.

[0127] The paint film smoothness detection method provided in this embodiment mainly addresses situations where the attenuation coefficient and delay values ​​differ significantly from the first and second preset floating ranges. Based on the first and second preset floating ranges, it can accurately determine whether there are protrusions, depressions, or internal air bubbles at the detection location of the part under test. Furthermore, by comparing the differences between the obtained delay and attenuation coefficient values ​​and the first and second preset floating ranges, it can further determine whether there are uneven paint films or solid impurities within the paint film near the detection location of the part under test. This paint film smoothness detection method, during all-weather detection of paint film surface smoothness, can also further detect the uniformity of the paint film at the detection location of the part under test and the presence of internal impurities and other abnormalities, resulting in a wider detection range and more detailed detection locations, thereby improving the accuracy of paint film detection.

[0128] Figure 6 This is a schematic flowchart of Example 4 of the paint film smoothness testing method provided in this application. Figure 6As shown, based on the first and second ultrasonic signals, the attenuation coefficient and delay of the acoustic transmission signal are calculated. This method for detecting the smoothness of the paint film also includes the following steps:

[0129] S601: Perform Fourier transform on the first ultrasonic signal to obtain the first amplitude and first phase at a preset frequency.

[0130] In this step, based on the obtained first ultrasonic signal, a Fourier transform operation is performed on the first ultrasonic signal to obtain the first amplitude and the first phase at a preset frequency.

[0131] The first ultrasonic signal is emitted by the ultrasonic testing device towards the testing position of the part to be tested, and the first ultrasonic signal can be represented as follows: The Fourier transform is a method for converting a time-domain signal into a frequency-domain signal. In the frequency domain, a signal can be represented as amplitude and phase. Amplitude represents the magnitude of the signal's amplitude at different frequencies, and phase represents the phase difference of the signal at different frequencies.

[0132] According to the Fourier transform operation, the first ultrasonic signal The first amplitude at the preset frequency ω0 is P. T and the first phase is Among them, the first amplitude P T and the first phase This serves as the data source for subsequent calculations of attenuation coefficients and delays.

[0133] S602: Perform Fourier transform on the second ultrasonic signal to obtain the second amplitude and second phase at a preset frequency.

[0134] In this step, based on the obtained second ultrasonic signal, a Fourier transform operation is performed on the second ultrasonic signal to obtain the second amplitude and the second phase at a preset frequency.

[0135] The second ultrasonic signal is received by the ultrasonic testing device on the other side of the testing position of the part under test. This second ultrasonic signal is obtained through media such as air, paint film, the part, and air. The second ultrasonic signal can be represented as follows:

[0136] According to the Fourier transform operation, the second ultrasonic signal The second amplitude at the preset frequency ω0 is P. R The second phase is Among them, the second amplitude P R Second phase This serves as the data source for subsequent calculations of attenuation coefficients and delays.

[0137] S603: Calculate the attenuation coefficient based on the first amplitude and the second amplitude, and calculate the delay based on the first phase and the second phase.

[0138] In this step, the attenuation coefficient is calculated based on the first and second amplitudes obtained in steps S601 and S602. Specifically, the attenuation coefficient is calculated by dividing the second amplitude by the first amplitude; that is, the attenuation coefficient equals the second amplitude divided by the second amplitude. Based on the first ultrasonic signal... Second ultrasound signal The first magnitude P obtained after the Fourier transform operation T Second amplitude P R The attenuation coefficient α is P R / P T .

[0139] Based on the first and second phases obtained in steps S601 and S602, the delay is calculated. Specifically, the delay is calculated by subtracting the first phase from the second phase; that is, the delay equals the second phase minus the first phase. Based on the first ultrasound signal... Second ultrasound signal The first phase obtained after Fourier transform operation Second phase Delay

[0140] The paint film smoothness detection method provided in this embodiment mainly involves the process of obtaining attenuation coefficients and delay values ​​based on a first ultrasonic signal and a second ultrasonic signal. According to the Fourier transform operation, both the first and second ultrasonic signals can be transformed to obtain a first amplitude, a first phase, a second amplitude, and a second phase. The attenuation coefficient can be obtained based on the ratio between the second amplitude and the first amplitude, and the delay can be obtained based on the difference between the second phase and the first phase. Based on the obtained attenuation coefficients and delays, they are compared with the attenuation coefficients and delays obtained from pre-measured normal paint films, thereby accurately determining the smoothness of the paint film surface at the detection location of the part under test and effectively improving the detection rate.

[0141] Figure 7 This is a schematic flowchart of Example 5 of the paint film smoothness testing method provided in this application. Figure 7 As shown, based on any of the above embodiments, and calculating the attenuation coefficient according to the first amplitude and the second amplitude, the paint film smoothness detection method further includes the following steps:

[0142] S701: Calculate the ratio of the second amplitude to the first amplitude, and use it as the attenuation coefficient.

[0143] This step mainly involves calculating the attenuation coefficient. Based on the Fourier transform operation, the first and second ultrasonic signals can be transformed to obtain corresponding first and second amplitudes. The attenuation coefficient is obtained by comparing the second amplitude with the first amplitude.

[0144] The damping coefficient refers to the ratio of the amplitudes of two adjacent oscillations in the same direction during damped oscillation. The damping coefficient is an indicator of stability. If the damping coefficient is less than 1:1, the oscillation is diffuse, and the system is unstable. To ensure sufficient stability margin, a damping coefficient of 4:1 to 10:1 is preferable.

[0145] If the paint film surface at the test location of the part is smooth but contains air bubbles, the ultrasonic signal will be scattered when it encounters the air bubbles. Some ultrasonic waves will change their original propagation path, and the intensity reaching the other side of the test location after transmission will be weakened. Therefore, based on the obtained attenuation coefficient, it can be compared and analyzed with the attenuation coefficient represented by a normal paint film to determine whether there are abnormalities such as air bubbles inside the test location of the part.

[0146] The paint film smoothness detection method provided in this embodiment mainly illustrates the calculation steps of the attenuation coefficient. A first ultrasonic signal and a second ultrasonic signal are acquired using an ultrasonic testing device. Then, a first amplitude and a second amplitude are obtained based on a Fourier transform operation. Finally, the second amplitude and the first amplitude are compared to obtain the attenuation coefficient corresponding to the detection position of the part under test. This attenuation coefficient calculation method is relatively simple and can be obtained in a short time, thereby effectively improving the detection efficiency of paint film smoothness.

[0147] Figure 8 This is a schematic flowchart of Example 6 of the paint film smoothness testing method provided in this application. Figure 8 As shown, based on any of the above embodiments, and calculating the delay according to the first phase and the second phase, the paint film smoothness detection method further includes the following steps:

[0148] S801: Calculate the difference between the second phase and the first phase as a delay.

[0149] This step mainly involves calculating the delay. Based on the Fourier transform operation, the first and second ultrasound signals can be transformed to obtain the corresponding first and second phases. Subtracting the first and second phases from the second phase yields the corresponding delay value.

[0150] In this context, delay refers to the time it takes for an ultrasonic signal to travel from the detection position of the part under test to the other side of that position; in other words, it's the delay the ultrasonic signal experiences during transmission. The unit of delay is typically seconds, milliseconds, or microseconds. Phase refers to the relative offset angle of the ultrasonic signal. In a sine wave, phase refers to the position of the waveform within its period, usually expressed in angles or radians, with the unit typically being radians or degrees. Delay is a linear function of phase; that is, an increase in delay will lead to a change in phase.

[0151] For example, if the paint film surface at the test location of the part has depressions but no internal abnormalities such as bubbles, the propagation path of the ultrasonic signal in the air increases, while the propagation path in the solid part is reduced. Based on the principle that sound travels slower in air than in solids, the time it takes for the first ultrasonic signal to travel from the test location to the other side will be longer. Conversely, if the paint film surface at the test location has protrusions but no internal abnormalities such as bubbles, the propagation path of the ultrasonic signal in the air decreases, while the propagation path in the solid part is increased. Based on the principle that sound travels faster in solids than in air, the time it takes for the first ultrasonic signal to travel from the test location to the other side will be shorter.

[0152] Therefore, based on the obtained delay value, it can be compared and analyzed with the delay value represented by the normal paint film obtained in advance, so as to determine whether there are abnormal phenomena such as dents or protrusions at the detection position of the part under test.

[0153] The paint film smoothness detection method provided in this embodiment mainly illustrates the calculation steps of the delay. A first ultrasonic signal and a second ultrasonic signal are acquired using an ultrasonic testing device. Then, a first phase and a second phase are obtained based on a Fourier transform operation. Finally, the second phase and the first phase are subtracted to obtain the delay corresponding to the detection position of the part under test. The data source for this delay calculation is relatively easy to obtain, and the calculation method is simple and easy to understand, which can improve the efficiency of paint film smoothness detection.

[0154] Figure 9 This is a schematic flowchart of Example 7 of the paint film smoothness testing method provided in this application. Figure 9 As shown, based on any of the above embodiments, the method for detecting the smoothness of a paint film further includes the following steps: A first ultrasonic signal emitted from the detection position of the part under test and a second ultrasonic signal received after transmission through the detection position are acquired using an ultrasonic testing device.

[0155] S901: Controls the acoustic air-coupled transmitting probe of the ultrasonic testing device to transmit the first ultrasonic signal to the testing position.

[0156] This step primarily describes the source of the device emitting the first ultrasonic signal. The ultrasonic testing device includes an acoustic air-coupled transmitting probe. The acoustic air-coupled transmitting probe is mainly used to emit the first ultrasonic signal at the detection location of the part under test.

[0157] Before starting the paint film smoothness inspection, the area of ​​the inspection location on the part to be tested must first be determined. If the inspection location area is small, simply determine the location of the part, and the ultrasonic testing device will activate the acoustic air-coupled transmitter probe, pointing it at the inspection location and emitting the first ultrasonic signal. If the inspection location area is large, the ultrasonic testing device will first divide the inspection location into a grid according to the specific area size. The grid division can be performed according to the principle of equidistant spacing. Then, the ultrasonic testing device will activate the acoustic air-coupled transmitter probe, pointing it at the inspection location belonging to one of the grid divisions on the part to be tested. After the inspection of that inspection location is completed, the ultrasonic testing device will move to the next grid area and inspect the inspection locations in that grid area until all inspection locations within all grids have been inspected.

[0158] For example, if the part to be tested is a nut, the testing location is one side of the nut. Because the area to be tested is small, the acoustic air-coupled transmitting probe of the ultrasonic testing device only needs to point to one side of the nut and then emit the first ultrasonic signal to the testing location. If the part to be tested is a car door, the testing location is the side of the door covered with paint. Because the area to be tested is large, before starting the paint film smoothness test, the area to be tested on the car door is first divided, for example, into 3 areas, numbered 1, 2, and 3. After the division, the acoustic air-coupled transmitting probe of the ultrasonic testing device first points to the testing area numbered 1 and emits the first ultrasonic signal. After the testing in the testing area numbered 1 is completed, the acoustic air-coupled transmitting probe of the ultrasonic testing device automatically moves to the testing area numbered 2 and continues to emit the first ultrasonic signal there. After the testing in the testing area numbered 2 is completed, the acoustic air-coupled transmitting probe of the ultrasonic testing device automatically moves from the testing area numbered 2 to the testing area numbered 3 and emits the first ultrasonic signal there.

[0159] S902: The acoustic air-coupled receiving probe of the ultrasonic testing device receives the second ultrasonic signal penetrating from the testing position.

[0160] In this step, based on the first ultrasonic signal emitted by the acoustic air-coupled transmitting probe of the ultrasonic testing device in step S901 toward the detection position of the part under test, the acoustic air-coupled receiving probe of the ultrasonic testing device receives the second ultrasonic signal that has penetrated through to the other side of the detection position of the part under test, thereby being used for subsequent calculation of delay and attenuation coefficient.

[0161] After the acoustic air-coupled transmitting probe emits a first ultrasonic signal toward the detection location of the part under test, this first ultrasonic signal, due to its short wavelength and higher frequency than the particle motion frequency of most solids and gases, can penetrate solids and gases without being absorbed by them. Therefore, the acoustic air-coupled receiving probe of the ultrasonic testing device can receive the second ultrasonic signal that penetrates from the detection location.

[0162] Before starting the paint film smoothness test, the ultrasonic testing device needs to pre-set the position of the acoustic hollow-coupler receiving probe. The position of the acoustic hollow-coupler receiving probe is determined based on the size of the area of ​​the part under test. If the area of ​​the part under test is small, the ultrasonic testing device can set the position of the acoustic hollow-coupler receiving probe opposite the position of the acoustic hollow-coupler transmitting probe. If the area of ​​the part under test is large, the ultrasonic testing device will set the position of the acoustic hollow-coupler receiving probe in each grid, ensuring that each time the acoustic hollow-coupler transmitting probe emits the first ultrasonic signal in the divided area, it can receive the transmitted second ultrasonic signal on the other side of that area.

[0163] For example, if the part to be tested is a nut, the detection location is one side of the nut. Because the area of ​​the detection location is small, the acoustic air-coupled transmitting probe of the ultrasonic testing device points to one side of the nut and then emits a first ultrasonic signal to the detection location. The acoustic air-coupled receiving probe can be installed opposite the acoustic air-coupled transmitting probe to receive the transmitted second ultrasonic signal, which is used for subsequent calculation of attenuation coefficient and delay. If the part to be tested is a car door, the detection location is the side of the door covered with paint. Because the area of ​​the detection location is large, the area to be tested on the car door is first divided, for example, into 3 areas, numbered 1, 2, and 3. After the division, the acoustic air-coupled transmitting probe of the ultrasonic testing device emits the first ultrasonic signal sequentially in the detection areas numbered 1, 2, and 3, while the acoustic air-coupled receiving probe of the ultrasonic testing device is placed on the opposite side of the detection areas numbered 1, 2, and 3.

[0164] The paint film smoothness detection method provided in this embodiment mainly involves the function of the acoustic air-coupled transmitting probe and the acoustic air-coupled receiving probe included in the ultrasonic testing device. Depending on the specific area of ​​the part to be tested, the acoustic air-coupled transmitting probe of the ultrasonic testing device emits a first ultrasonic signal at a pre-set detection position, and the acoustic air-coupled receiving probe receives the transmitted second ultrasonic signal on the other side of the detection position. Using the acoustic air-coupled probe eliminates the need for a coupling agent, allowing for both transmission and reception of acoustic signals. Furthermore, the first ultrasonic signal emitted by the acoustic air-coupled transmitting probe and the second ultrasonic signal received by the acoustic air-coupled receiving probe are less affected by environmental factors, providing data for subsequent calculations of attenuation coefficients and delay values, thereby effectively determining whether there are any abnormalities or other problems at the detection position of the part to be tested.

[0165] Figure 10 This is a schematic diagram of the structure of Embodiment 1 of the paint film smoothness testing device provided in this application. Figure 10 As shown, the paint film smoothness testing device 1000 includes:

[0166] The acquisition module 1001 is used to acquire, through the ultrasonic testing device, a first ultrasonic signal emitted at the detection position of the part to be tested and a second ultrasonic signal received after passing through the detection position.

[0167] The processing module 1002 is used to calculate the attenuation coefficient and delay of the acoustic transmission signal based on the first ultrasonic signal and the second ultrasonic signal.

[0168] The processing module 1002 is also used to determine the smoothness of the paint film at the detection position based on the attenuation coefficient, the delay, and the average attenuation coefficient and the average delay of the acoustic transmission signal of a normal smooth paint film obtained in advance.

[0169] Optionally, the processing module 1002 is also used for:

[0170] If the attenuation coefficient is less than the first preset floating range of the average attenuation coefficient and the delay is within the second preset floating range of the average delay, then it is determined that the paint film surface at the detection position is smooth and contains air bubbles.

[0171] If the attenuation coefficient is less than the first preset floating range of the average attenuation coefficient and the delay is less than the second preset floating range of the average delay, then it is determined that there is a protrusion on the surface of the paint film at the detection position and that there are air bubbles inside.

[0172] If the attenuation coefficient is less than the first preset floating range of the average attenuation coefficient and the delay is greater than the second preset floating range of the average delay, then it is determined that there is a depression on the surface of the paint film at the detection location and that there are air bubbles inside.

[0173] If the attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient and the delay is greater than the second preset fluctuation range of the average delay, then it is determined that there is a depression on the surface of the paint film at the detection location and no air bubbles inside.

[0174] If the attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient and the delay is less than the second preset fluctuation range of the average delay, then it is determined that there is a protrusion on the surface of the paint film at the detection position and no air bubbles inside.

[0175] If the attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient and the delay is within the second preset fluctuation range of the average delay, then the surface of the paint film at the detection location is determined to be smooth and the interior is uniform.

[0176] If the delay is less than the second preset floating range of the average delay, and the difference between the delay and the minimum value of the second preset floating range is greater than the first preset difference, then it is determined that the paint film thickness at the detection position is uneven.

[0177] If the difference between the attenuation coefficient and the upper or lower limit of the first preset floating range of the attenuation coefficient is greater than the second preset difference, and the difference between the delay and the upper or lower limit of the second preset floating range is greater than the third preset difference, then it is determined that the paint film surface at the detection position is uneven and contains solid impurities.

[0178] Optionally, the processing module 1002 is also used for:

[0179] If the delay is less than the second preset floating range of the average delay, and the difference between the delay and the minimum value of the second preset floating range is greater than the first preset difference, then it is determined that the paint film thickness at the detection position is uneven.

[0180] If the difference between the attenuation coefficient and the upper or lower limit of the first preset floating range of the attenuation coefficient is greater than the second preset difference, and the difference between the delay and the upper or lower limit of the second preset floating range is greater than the third preset difference, then it is determined that the paint film surface at the detection position is uneven and contains solid impurities.

[0181] Optionally, the processing module 1002 is also used for:

[0182] The first ultrasonic signal is subjected to Fourier transform to obtain the first amplitude and first phase at a preset frequency;

[0183] The second ultrasonic signal is subjected to Fourier transform to obtain the second amplitude and the second phase at the preset frequency;

[0184] The attenuation coefficient is calculated based on the first amplitude and the second amplitude, and the delay is calculated based on the first phase and the second phase.

[0185] Optionally, the processing module 1002 is also used for:

[0186] Calculate the ratio of the second amplitude to the first amplitude, and use it as the attenuation coefficient.

[0187] Optionally, the processing module 1002 is also used for:

[0188] Calculate the difference between the second phase and the first phase as the delay.

[0189] Optionally, the processing module 1002 is also used for:

[0190] The acoustic air-coupled transmitting probe of the ultrasonic testing device is controlled to transmit the first ultrasonic signal to the detection position.

[0191] Optionally, the acquisition module 1001 is also used for:

[0192] The acoustic air-coupled receiving probe of the ultrasonic testing device receives a second ultrasonic signal that penetrates from the testing position.

[0193] The paint film smoothness detection device provided in the foregoing embodiments can be used to perform the paint film smoothness detection method in any of the foregoing method embodiments. The implementation principle and technical effect are similar. The paint film smoothness detection device can detect the detection position of the part to be tested in all weather conditions, with a wide range of applicable time and high detection efficiency.

[0194] Figure 11 This is a schematic diagram of the electronic device for detecting the smoothness of the paint film provided in this application. Figure 11 As shown, the electronic device may specifically include a receiver 1100, a transmitter 1101, a processor 1102, and a memory 1103. The receiver 1100 and transmitter 1101 are used to realize data transmission between the electronic device and the application client. The memory 1103 stores computer execution instructions. The processor 1102 executes the computer execution instructions stored in the memory 1103 to implement the paint film smoothness detection method in the above embodiment.

[0195] This embodiment provides a computer-readable storage medium storing computer-executable instructions. When executed by a processor, these instructions are used to implement the paint film smoothness detection method described in the above embodiment.

[0196] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the paint film smoothness detection method provided in any of the above embodiments.

[0197] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily essential to this application.

[0198] It should be further noted that although the steps in the flowchart are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowchart may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.

[0199] It should be understood that the above-described device embodiments are merely illustrative, and the device of this application can also be implemented in other ways. For example, the division of units / modules in the above embodiments is only a logical functional division, and there may be other division methods in actual implementation. For example, multiple units, modules, or components may be combined, or integrated into another system, or some features may be ignored or not executed.

[0200] Furthermore, unless otherwise specified, the functional units / modules in the various embodiments of this application can be integrated into one unit / module, or each unit / module can exist physically separately, or two or more units / modules can be integrated together. The integrated units / modules described above can be implemented in hardware or as software program modules.

[0201] When integrated units / modules are implemented in hardware, the hardware can be digital circuits, analog circuits, etc. The physical implementation of the hardware structure includes, but is not limited to, transistors, memristors, etc. Unless otherwise specified, the processor can be any suitable hardware processor, such as a CPU, GPU, FPGA, DSP, and ASIC, etc. Unless otherwise specified, the storage unit can be any suitable magnetic or magneto-optical storage medium, such as Resistive Random Access Memory (RRAM), Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), Enhanced Dynamic Random Access Memory (EDRAM), High-Bandwidth Memory (HBM), Hybrid Memory Cube (HMC), etc.

[0202] If the integrated unit / module is implemented as a software program module and sold or used as an independent product, it can be stored in a computer-readable storage device (CMD). Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned memory includes various media capable of storing program code, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard drive, magnetic disk, or optical disk.

[0203] In the above embodiments, the descriptions of each embodiment have their own emphasis. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments. The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0204] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0205] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for detecting the smoothness of a paint film, characterized in that, include: The ultrasonic testing device acquires a first ultrasonic signal emitted from the detection position of the part under test and a second ultrasonic signal received after passing through the detection position. Based on the first ultrasonic signal and the second ultrasonic signal, calculate the attenuation coefficient and delay of the acoustic transmission signal; If the attenuation coefficient is less than a first preset fluctuation range of the average attenuation coefficient, and the delay is within a second preset fluctuation range of the average delay, then it is determined that the paint film surface at the detection location is smooth and contains air bubbles. If the attenuation coefficient is less than the first preset floating range of the average attenuation coefficient, and the delay is less than the second preset floating range of the average delay, then it is determined that there is a protrusion on the surface of the paint film at the detection position and that there are air bubbles inside. If the attenuation coefficient is less than the first preset floating range of the average attenuation coefficient, and the delay is greater than the second preset floating range of the average delay, then it is determined that there is a depression on the surface of the paint film at the detection position and that there are air bubbles inside. If the attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient, and the delay is greater than the second preset fluctuation range of the average delay, then it is determined that there is a depression on the surface of the paint film at the detection position, and there are no air bubbles inside. If the attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient, and the delay is less than the second preset fluctuation range of the average delay, then it is determined that there is a protrusion on the surface of the paint film at the detection position, and there are no air bubbles inside. If the attenuation coefficient is within the first preset fluctuation range of the average attenuation coefficient and the delay is within the second preset fluctuation range of the average delay, then the paint film surface at the detection position is determined to be smooth and uniform inside.

2. The method according to claim 1, characterized in that, The method further includes: If the delay is less than the second preset floating range of the average delay, and the difference between the delay and the minimum value of the second preset floating range is greater than the first preset difference, then it is determined that the paint film thickness at the detection position is uneven. If the difference between the attenuation coefficient and the upper or lower limit of the first preset floating range of the average attenuation coefficient is greater than the second preset difference, and the difference between the delay and the upper or lower limit of the second preset floating range is greater than the third preset difference, then it is determined that the paint film surface at the detection position is uneven and contains solid impurities.

3. The method according to claim 1 or 2, characterized in that, The step of calculating the attenuation coefficient and delay of the acoustic transmission signal based on the first ultrasonic signal and the second ultrasonic signal includes: The first ultrasonic signal is subjected to Fourier transform to obtain the first amplitude and first phase at a preset frequency; The second ultrasonic signal is subjected to Fourier transform to obtain the second amplitude and the second phase at the preset frequency; The attenuation coefficient is calculated based on the first amplitude and the second amplitude, and the delay is calculated based on the first phase and the second phase.

4. The method according to claim 3, characterized in that, The calculation of the attenuation coefficient based on the first amplitude and the second amplitude includes: The ratio of the second amplitude to the first amplitude is calculated and used as the attenuation coefficient.

5. The method according to claim 3, characterized in that, The calculation of the delay based on the first phase and the second phase includes: The difference between the second phase and the first phase is calculated as the delay.

6. The method according to claim 1 or 2, characterized in that, The process of acquiring a first ultrasonic signal emitted from the detection location of the part under test and a second ultrasonic signal received after passing through the detection location via an ultrasonic testing device includes: The acoustic air-coupled transmitting probe of the ultrasonic detection device is controlled to transmit the first ultrasonic signal toward the detection position; The second ultrasonic signal, which penetrates from the detection position, is received by the acoustic air-coupled receiving probe of the ultrasonic testing device.

7. A paint film smoothness testing device, used to implement the paint film smoothness testing method as described in any one of claims 1-6, characterized in that, include: The acquisition module is used to acquire, through the ultrasonic testing device, a first ultrasonic signal emitted at the detection position of the part to be tested and a second ultrasonic signal received after passing through the detection position; The processing module is used to calculate the attenuation coefficient and delay of the acoustic transmission signal based on the first ultrasonic signal and the second ultrasonic signal; The processing module is also used to determine the smoothness of the paint film at the detection location based on the attenuation coefficient, the delay, and the average attenuation coefficient and average delay of the acoustic transmission signal of a normally smooth paint film obtained in advance.

8. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the method as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1 to 6.

10. A computer program product, characterized in that, Includes a computer program, which, when executed by a processor, is used to implement the method as described in any one of claims 1 to 6.

Images