A nondestructive testing method and device for magnetic permeability of flaky metal magnetic powder

Abstract

The present invention relates to the technical field of magnetic variable measurement, and particularly to a method and device for nondestructive testing of the magnetic permeability of flaky metal magnetic powder. The method comprises obtaining an initial sensitivity obtained by a detection coil in an initial state when detecting the flaky metal magnetic powder to be tested. If the initial sensitivity is less than a preset sensitivity threshold, the initial number of turns is adjusted according to a minimum coil turn increase value to obtain an adjusted number of turns until the corrected sensitivity obtained by the detection coil in the latest state is greater than or equal to the preset sensitivity threshold, thereby improving the inductive sensitivity of the detection coil to the inductance value of a small-sized sample such as the flaky metal magnetic powder, and thereby improving the accuracy of the magnetic permeability testing of the flaky metal magnetic powder. The method also comprises obtaining a damage probability of the flaky metal magnetic powder to be tested obtained during the detection process when the detection coil is in the latest state, and adjusting the initial excitation current based on the damage probability to reduce the damage probability of the flaky metal magnetic powder to be tested during the detection process.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic variable measurement, and in particular to a method and device for non-destructive detection of magnetic permeability of flaky metal magnetic powder. Background Art

[0002] Flake metal magnetic powder is a special type of metal powder with only one dimension at the submicron or nanometer level, and the other two dimensions at the micron level, resulting in a unique planar structure. Flake metal magnetic powder can be used in the research, development, and preparation of magnetic materials. Testing its magnetic permeability can accurately predict the magnetic permeability of the final product, allowing for rapid screening of substandard magnetic materials, saving R&D costs and improving the efficiency of technological improvement and innovation. However, due to the complexity of its shape and physical properties, traditional testing methods are prone to sample damage and produce inaccurate results. Therefore, a magnetic permeability testing method capable of non-destructive testing of flaky metal magnetic powder is needed.

[0003] The existing magnetic permeability testing method (inductance method) places a sample of sheet metal magnetic powder in a detection coil. By measuring the change in inductance in the detection coil and establishing a relationship between the inductance value and the sample's magnetic permeability, the sample's magnetic permeability can be deduced. This enables contactless testing of the sample, significantly reducing the probability of sample damage. However, during the magnetic permeability test, the inductance method typically increases the number of turns of the inductor coil to improve the sensitivity of the detection coil for small samples. In other words, a higher-turn inductor coil is directly selected as the adjusted detection coil. Coils with too many turns typically have higher magnetic field strengths. When performing magnetic permeability tests on samples, excessively high magnetic field strengths can cause damage to the sample, such as local overheating or magnetic saturation. Summary of the Invention

[0004] In order to solve the technical problem that the existing detection coil turn number adjustment method is prone to damage to flaky metal magnetic powder, the purpose of the present invention is to provide a method and device for non-destructive testing of the magnetic permeability of flaky metal magnetic powder. The technical solution adopted is as follows:

[0005] In a first aspect of the present invention, a method for nondestructive testing of magnetic permeability of flaky metal magnetic powder is provided, comprising:

[0006] Obtaining an initial sensitivity of the detection coil when detecting the sheet metal magnetic powder to be tested in an initial state, wherein the initial state includes an initial number of turns and an initial excitation current;

[0007] If the initial sensitivity is less than the preset sensitivity threshold, the initial number of turns is adjusted according to the minimum coil turn increase value to obtain an adjusted number of turns until the corrected sensitivity obtained by the detection coil in the latest state is greater than or equal to the preset sensitivity threshold; the latest state is the latest obtained adjusted number of turns and the initial excitation current;

[0008] Obtaining a damage probability of the sheet metal magnetic powder to be tested obtained during the detection of the sheet metal magnetic powder to be tested by the detection coil in the latest state;

[0009] The initial excitation current is adjusted based on the damage probability.

[0010] Preferably, obtaining the initial sensitivity of the detection coil when detecting the sheet-shaped metal magnetic powder to be detected in the initial state includes:

[0011] Obtaining the initial inductance change amplitude of the detection coil in the initial state of the detection coil before and after the sheet metal magnetic powder to be tested is placed in the detection coil;

[0012] The initial sensitivity is obtained according to the initial inductance variation amplitude.

[0013] Preferably, obtaining the initial inductance change amplitude of the detection coil in the initial state of the detection coil before and after the detection coil is placed includes:

[0014] Obtain the no-load inductance sequence of the detection coil when the detection coil is in the initial state and no sheet metal magnetic powder to be tested is placed in it;

[0015] Obtaining the actual inductance sequence and actual excitation current sequence of the detection coil in the initial state during the detection of the sheet metal magnetic powder to be tested;

[0016] Obtain the inductance difference between each corresponding position in the no-load inductance sequence and the actual inductance sequence;

[0017] The initial inductance variation is obtained using the following formula:

[0018] ;

[0019] in, represents the initial inductance change amplitude, T represents the number of data in the sequence, t represents the t-th position in the sequence, represents the actual excitation current at the tth position in the actual excitation current sequence, represents the inductance difference at the t-th position.

[0020] Preferably, the process of obtaining the minimum coil turns improvement value includes:

[0021] Obtaining a difference between the initial inductance variation range and a preset inductance variation range; the preset inductance variation range is an inductance variation range corresponding to the preset sensitivity threshold;

[0022] The minimum coil turns increase value is obtained according to the difference between the initial inductance change amplitude and the preset inductance change amplitude and the relationship between the number of turns of the detection coil and the inductance.

[0023] Preferably, the calculation formula of the minimum coil turns improvement value is as follows:

[0024] ;

[0025] in, is the minimum coil turns increase value, is the initial number of turns, is the initial inductance variation, is the difference between the initial inductance variation and the preset inductance variation, is a preset constant.

[0026] Preferably, the initial number of turns is adjusted according to the minimum coil turns increase value to obtain an adjusted number of turns until the corrected sensitivity of the detection coil in the latest state is greater than or equal to the preset sensitivity threshold, including:

[0027] Performing a first adjustment on the initial number of turns according to the minimum coil turn increase value to obtain a first adjusted number of turns;

[0028] Obtaining a first corrected sensitivity of the detection coil obtained by detecting the sheet metal magnetic powder to be tested in a first adjustment state, wherein the first adjustment state includes the first adjustment number of turns and the initial excitation current;

[0029] If the first correction sensitivity is less than the preset sensitivity threshold, the first adjustment turns are adjusted for a second time according to the first adjustment minimum coil turns increase value corresponding to the first adjustment state to obtain a second adjustment turns; if the first correction sensitivity is greater than or equal to the preset sensitivity threshold, the latest state is the first adjustment state;

[0030] Obtaining a second corrected sensitivity of the detection coil obtained by detecting the sheet metal magnetic powder to be tested in a second adjustment state, wherein the second adjustment state includes the second adjustment number of turns and the initial excitation current;

[0031] If the second correction sensitivity is less than the preset sensitivity threshold, the second adjustment number of turns is adjusted for a third time according to the second adjustment minimum coil turn increase value corresponding to the second adjustment state to obtain a third adjustment number of turns; if the second correction sensitivity is greater than or equal to the preset sensitivity threshold, the latest state is the second adjustment state;

[0032] And so on, the latest state of the detection coil is obtained.

[0033] Preferably, obtaining the damage probability of the sheet metal magnetic powder to be tested obtained during the detection of the sheet metal magnetic powder to be tested by the detection coil in the latest state includes:

[0034] obtaining a degree of temperature non-uniformity of the sheet metal magnetic powder to be tested during the process of the detection coil detecting the sheet metal magnetic powder to be tested in the latest state;

[0035] Obtaining respectively the actual inductance sequence of the detection coil in the latest state and the adjacent state during the detection process of the sheet metal magnetic powder to be tested, and then calculating the latest inductance difference between the actual inductance sequence of the latest state and the adjacent state; the adjacent state is the state before the latest state;

[0036] The damage probability is obtained according to the temperature non-uniformity and the latest inductance difference; the damage probability is proportional to the temperature non-uniformity and inversely proportional to the latest inductance difference.

[0037] Preferably, the magnetic permeability nondestructive testing method further includes:

[0038] If the damage probability is less than a first damage probability threshold and greater than a second damage probability threshold, the initial excitation current is adjusted based on the damage probability; the first damage probability threshold is greater than the second damage probability threshold.

[0039] Preferably, adjusting the initial excitation current based on the damage probability includes:

[0040] Obtaining an excitation current reduction coefficient based on the damage probability and the inductance turns correlation; the inductance turns correlation is obtained by the latest turns difference and the latest inductance difference, where the latest turns difference is the turns difference between the latest state and the adjacent state;

[0041] An adjusted excitation current is obtained according to the excitation current reduction coefficient and the initial excitation current.

[0042] In a second aspect of the present invention, a device for nondestructive testing the magnetic permeability of flaky metal magnetic powder is provided, comprising: a memory and a processor; the memory being connected to the processor; the memory being configured to store program instructions; and the processor being configured to implement the above-mentioned method for nondestructive testing the magnetic permeability of flaky metal magnetic powder when the program instructions are executed.

[0043] The present invention has the following beneficial effects: first, the initial sensitivity of the detection coil obtained when detecting the sheet metal magnetic powder to be tested in the initial state is obtained, and then the number of turns of the detection coil is continuously adjusted according to the size relationship between the sensitivity and the preset sensitivity threshold, so that the sensitivity is greater than or equal to the preset sensitivity threshold, thereby improving the inductive sensitivity of the detection coil to the inductance value of the sheet metal magnetic powder, which is a small-sized sample, and thus improving the accuracy of the magnetic permeability detection of the sheet metal magnetic powder; at the same time, after adjusting the number of turns of the detection coil, the damage probability of the sheet metal magnetic powder to be tested obtained during the detection process of the sheet metal magnetic powder to be tested by the detection coil in the latest state is obtained, and the excitation current is adjusted based on the damage probability to reduce the damage probability of the sheet metal magnetic powder to be tested during the detection process. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is an overall flow chart of a nondestructive testing method for magnetic permeability of flaky metal magnetic powder provided in this embodiment;

[0045] Figure 2 This is a logic block diagram of a nondestructive testing method for magnetic permeability of flaky metal magnetic powder provided in this embodiment;

[0046] Figure 3 It is a flow chart of the process of obtaining initial sensitivity;

[0047] Figure 4 It is a flow chart of the process of obtaining the minimum coil turns improvement value;

[0048] Figure 5 It is a flow chart of the process of obtaining the damage probability;

[0049] Figure 6 It is a flow chart of the adjustment process of the initial excitation current. DETAILED DESCRIPTION

[0050] To further illustrate the technical means and effects employed by the present invention to achieve its intended objectives, the following detailed description of the specific embodiments, structures, features, and effects of the present invention is provided in conjunction with the accompanying drawings and preferred embodiments. In the following description, references to "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0051] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0052] The inductance method for testing the magnetic permeability of flake metal powder primarily utilizes the inductance characteristics of a detection coil to measure the permeability of the powder. However, due to the typically small size of flake metal powder samples, the resulting inductance change can be small, resulting in insufficient sensitivity when testing with a detection coil with a smaller number of turns. To improve the sensitivity of the detection coil in permeability testing of flake metal powder, the number of turns is often increased, thereby amplifying the sample's inductance change and, consequently, increasing the sensitivity of the detection coil. However, if the excitation parameters remain unchanged after increasing the number of turns, the magnetic field strength generated by the detection coil will also increase, making it more likely that the flake metal powder sample will experience magnetic saturation. Furthermore, if the magnetic field is too strong, greater eddy currents may form within the flake metal powder (especially in conductive materials), leading to localized overheating and damage to the flake metal powder.

[0053] This embodiment provides a method for nondestructive testing the magnetic permeability of flaky metal magnetic powder. The method aims to monitor the state of the flaky metal magnetic powder in real time during the magnetic permeability test and adjust the excitation parameters of the detection coil to reduce the probability of local overheating or over-magnetization caused by increasing the number of coil turns. This method improves the coil sensitivity while reducing the probability of damage to the flaky metal magnetic powder during the test.

[0054] In an exemplary embodiment, after obtaining the flaky metal magnetic powder, the flaky metal magnetic powder is pre-processed to ensure accuracy and reliability during subsequent testing. The specific steps are as follows: First, the flaky metal magnetic powder is cleaned to remove oil, dust, and other impurities to avoid interference with the testing process; then, the flaky metal magnetic powder is evenly filled into a container, with the filling height generally not exceeding one-third of the height of the container's inner cavity. After filling the container, the flaky metal magnetic powder to be tested is obtained, and the flaky metal magnetic powder to be tested serves as the flaky metal magnetic powder sample. The container filled with the flaky metal magnetic powder is stably placed in the magnetic core cavity of the detection coil.

[0055] After pre-processing the flaky metal powder to be tested, the relevant testing equipment is installed as follows: First, prepare the equipment required for the test process, including a signal generator, excitation coil, detection coil, and data acquisition module. The signal generator is used to provide stable high-frequency electromagnetic excitation; the excitation coil is used to generate an alternating magnetic field, and its shape and structural design should ensure magnetic field uniformity; the detection coil is an inductive coil surrounding the flaky metal powder to be tested, used to detect the magnetic field response of the flaky metal powder to be tested; the data acquisition module includes a temperature sensor, and other modules such as an oscilloscope can be set up as needed to collect various data during the test process.

[0056] The data acquisition module's sampling frequency is then set. The temperature sensor, used to obtain surface temperature data for the flaky metal magnetic powder under test, is sampled at a frequency of 1 time per second. An oscilloscope is connected to the circuit to monitor the input signal and the sample's response waveform (magnetic induction signal, voltage, or current waveform, depending on the subsequent need for detecting the corresponding signal waveform). The sampling frequency is set at 10 times per second. The collected data is then arranged in chronological order to create a corresponding time series data sequence.

[0057] Place the flaky metal powder to be tested into the detection coil. During the permeability test, the number of turns in the detection coil is correlated with the size and physical characteristics of the powder. Smaller flaky metal powders require a stronger magnetic field, while weaker magnetic fields are generally less sensitive. When the coil has the appropriate number of turns, it responds significantly to changes in the parameters of the powder. By analyzing changes in the parameters of the powder and the coil parameters, the appropriate number of turns in the detection coil can be determined.

[0058] Figure 1 This is an overall flow chart of a nondestructive testing method for magnetic permeability of flaky metal magnetic powder provided in this embodiment. Figure 2 This is a logic block diagram of a nondestructive testing method for the magnetic permeability of flaky metal magnetic powder provided in this embodiment.

[0059] like Figure 1 As shown, the nondestructive testing method for the magnetic permeability of flaky metal magnetic powder includes the following steps:

[0060] Step 1: Obtain the initial sensitivity of the detection coil when detecting the sheet metal magnetic powder to be tested in the initial state.

[0061] Initially, the detection coil is set to an initial state, which includes an initial number of turns and an initial excitation current. That is, the detection coil is in the initial state, has an initial number of turns, and has an initial excitation current. It should be understood that the initial number of turns and initial excitation current are set by the implementer based on actual conditions.

[0062] When the number of turns of the detection coil is the initial number of turns and the excitation current is the initial excitation current, the sheet metal magnetic powder to be measured is detected to obtain the initial sensitivity of the detection coil to the sheet metal magnetic powder to be measured.

[0063] In an exemplary embodiment, Figure 3 As shown, the process of obtaining the initial sensitivity is as follows:

[0064] Step 1-1: Obtain the initial inductance change amplitude of the detection coil in its initial state before and after the sheet metal magnetic powder to be tested is placed in the detection coil.

[0065] First, the no-load inductance sequence of the detection coil is obtained when the detection coil is in its initial state and no flaky metal powder is placed in it. It should be understood that when the detection coil is in its initial state and the test is initiated, the no-load inductance of the detection coil is measured. Multiple no-load inductance values are acquired over a certain period of time at a sampling frequency to form a no-load inductance sequence. Therefore, the first inductance value of the no-load inductance sequence is the inductance value measured at the start of the test, and the no-load inductance sequence is a sequence of multiple inductance values.

[0066] Next, the sheet metal magnetic powder to be tested is placed into the detection coil, and testing is initiated. During the initial testing phase, the actual inductance sequence of the detection coil and the actual excitation current sequence are acquired during the initial testing phase. Similarly, during the initial testing phase, the actual inductance of the detection coil is measured, and multiple actual inductances are acquired over the same period of time at the same sampling frequency as during no-load operation to form an actual inductance sequence. Therefore, the first inductance value of the actual inductance sequence is the inductance value measured during the initial testing phase, and the actual inductance sequence is a sequence consisting of multiple inductance values. The actual excitation current sequence is acquired similarly to the actual inductance sequence. Also during the initial testing phase, the actual excitation current is measured, and multiple actual excitation currents are acquired over the same period of time at the same sampling frequency as during no-load operation to form an actual excitation current sequence. Therefore, the first inductance value of the actual excitation current sequence is the actual excitation current measured during the initial testing phase, and the actual excitation current sequence is a sequence consisting of multiple actual excitation currents.

[0067] It should be understood that the no-load inductance sequence, the actual inductance sequence and the actual excitation current sequence contain the same amount of data, and there is a corresponding relationship between the data at the same position in the no-load inductance sequence, the actual inductance sequence and the actual excitation current sequence.

[0068] Then, the inductance difference of each corresponding position in the no-load inductance sequence and the actual inductance sequence is obtained. In this embodiment, the inductance difference is specifically the absolute value of the difference in inductance values, and the calculation formula is as follows:

[0069] ;

[0070] Where t represents the tth position in the sequence, represents the inductance difference at the t-th position, is the actual inductance value of the tth position in the actual inductance sequence, is the no-load inductance value at the tth position in the no-load inductance sequence.

[0071] Finally, the initial inductance change is calculated using the following formula:

[0072] ;

[0073] in, represents the initial inductance change amplitude, T represents the number of data in the sequence, Represents the actual excitation current at the tth position in the actual excitation current sequence.

[0074] It should be noted that when the excitation current is larger, the magnetic field strength of the detection coil should be larger, so the difference in inductance change should be more obvious. Therefore, a larger weight is set for a larger excitation current.

[0075] Step 1-2: Obtain the initial sensitivity based on the initial inductance change amplitude.

[0076] The larger the initial inductance change amplitude, the greater the detection coil's sensitivity to the flaky metal powder being tested. Therefore, the initial sensitivity is obtained based on the initial inductance change amplitude, and the initial sensitivity is proportional to the initial inductance change amplitude. In an exemplary embodiment, the initial inductance change amplitude is normalized, and the normalized result is used as the initial sensitivity. The normalization in this embodiment can be performed using the following general method: . Among them, z is the data that needs to be normalized, It is an exponential function with the natural constant e as its base.

[0077] Step 2: If the initial sensitivity is less than the preset sensitivity threshold, the initial number of turns is adjusted according to the minimum coil turn increase value to obtain the adjusted number of turns until the corrected sensitivity obtained by the detection coil in the latest state is greater than or equal to the preset sensitivity threshold.

[0078] A sensitivity threshold is preset, and the value of the preset sensitivity threshold is set according to actual needs. In this embodiment, it is set to 0.4.

[0079] The preset sensitivity threshold is compared with the initial sensitivity. If the initial sensitivity is less than the preset sensitivity threshold, that is, there is a certain gap between the initial sensitivity and the preset sensitivity threshold, it means that the initial sensitivity does not meet the detection requirements and the initial number of turns of the detection coil needs to be adjusted to improve the sensitivity. It should be understood that if the initial sensitivity is greater than or equal to the preset sensitivity threshold, it means that the initial number of turns of the detection coil is sufficient to detect the magnetic permeability of the flaky metal magnetic powder to be tested, and the subsequent steps will not be executed. This situation will not be described in detail. The following is a detailed description of the situation where the initial sensitivity is less than the preset sensitivity threshold.

[0080] In order to adjust the initial number of turns, it is necessary to first obtain the minimum coil turn increase value corresponding to the initial number of turns, such as Figure 4 As shown, the acquisition process includes:

[0081] Step 2-1: Obtain the difference between the initial inductance change amplitude and the preset inductance change amplitude.

[0082] The initial inductance variation amplitude is obtained through the above steps, and then the inductance variation amplitude corresponding to the preset sensitivity threshold is obtained, which is defined as the preset inductance variation amplitude. It should be understood that since the preset sensitivity threshold is a preset, known threshold, the preset inductance variation amplitude is also a preset, known threshold. In an exemplary embodiment, the preset inductance variation amplitude can be obtained as follows: Using the process of step 1, the number of turns of the detection coil is continuously adjusted to obtain the inductance variation amplitude and sensitivity corresponding to each number of turns. The inductance variation amplitude corresponding to the sensitivity having the same value as the preset sensitivity threshold is then found as the preset inductance variation amplitude.

[0083] The difference between the initial inductance variation range and the preset inductance variation range is obtained, specifically, the absolute value of the difference between the initial inductance variation range and the preset inductance variation range. The difference between the initial inductance variation range and the preset inductance variation range is the theoretical improvement value of the initial inductance variation range.

[0084] Step 2-2: Based on the difference between the initial inductance change amplitude and the preset inductance change amplitude, combined with the relationship between the number of turns of the detection coil and the inductance, the minimum coil turns increase value is obtained.

[0085] It should be understood that the basic relationship between inductance and number of coil turns is:

[0086] ;

[0087] Where L represents inductance, represents magnetic permeability; Indicates the number of turns of the detection coil; represents the cross-sectional area of the detection coil; Indicates the length of the detection coil.

[0088] Then, the relationship between the initial number of turns of the detection coil and the inductance is:

[0089] ;

[0090] in, represents magnetic permeability; Indicates the initial number of turns of the detection coil.

[0091] Range of change The improved theoretical model is:

[0092] ;

[0093] in, is the difference between the initial inductance change and the preset inductance change, Indicates the minimum coil turns increase value of the detection coil.

[0094] Since the flaky metal powder to be tested has not changed and the cross-sectional area and length of the detection coil are not adjusted, the magnetic permeability of the flaky metal powder to be tested is No change, calculate the minimum coil turns increase value , the calculation formula is as follows:

[0095] ;

[0096] Where, It represents a preset constant, which can be taken as 0.01 by experience. It is used to avoid the possibility of the denominator of the fraction being zero.

[0097] Then, the initial number of turns is adjusted according to the obtained minimum coil turn increase value, including the following adjustment process:

[0098] First, the initial number of turns is adjusted for the first time according to the minimum coil turns increase value to obtain the first adjusted number of turns. Specifically, the initial number of turns is added to the minimum coil turns increase value to obtain the first adjusted number of turns.

[0099] The first adjustment state is set to the first adjustment number of turns and the initial excitation current, that is, when the detection coil is in the first adjustment state, the number of turns of the detection coil is the first adjustment number of turns, and the excitation current of the detection coil is the initial excitation current.

[0100] Obtain a first corrected sensitivity obtained by detecting the flaky metal magnetic powder to be tested in the first adjustment state of the detection coil. It should be understood that according to the process of steps 1 and 2, with the initial state replaced by the first adjustment state, the magnitude of the change in inductance of the detection coil in the first adjustment state, before and after the detection coil is placed, is obtained, which is defined as the first adjusted inductance change magnitude. Then, based on the first adjusted inductance change magnitude, the first corrected sensitivity corresponding to the first adjustment state is obtained.

[0101] The first corrected sensitivity is then compared with the preset sensitivity threshold. If the first corrected sensitivity is still less than the preset sensitivity threshold, the minimum coil turn increase value corresponding to the first adjustment state is obtained, defined as the first adjusted minimum coil turn increase value. It should be understood that the first adjusted minimum coil turn increase value is obtained according to the process of steps 2-1 and 2-2, wherein the difference in the inductance change amplitude involved in the acquisition process is the difference between the first adjusted inductance change amplitude and the preset inductance change amplitude. The first adjusted minimum coil turn increase value is then obtained based on this difference. The first adjusted turns are adjusted a second time based on the obtained first adjusted minimum coil turn increase value to obtain a second adjusted turns number. Specifically, the first adjusted minimum coil turn increase value is added to the first adjusted turns number to obtain the second adjusted turns number. It should be understood that if the first corrected sensitivity is greater than or equal to the preset sensitivity threshold, it indicates that after one adjustment, the detection coil turns have met the requirements, and the subsequent cycle process is no longer performed. The first adjusted state is determined as the latest state.

[0102] The second adjustment state is set to the second adjustment number of turns and the initial excitation current, that is, when the detection coil is in the second adjustment state, the number of turns of the detection coil is the second adjustment number of turns, and the excitation current of the detection coil is the initial excitation current.

[0103] Obtain a second corrected sensitivity when the detection coil is in the second adjusted state and testing the flaky metal magnetic powder to be tested. Similar to the first adjustment process described above, follow steps 1 and 2, replacing the initial state with the second adjusted state. Then, obtain the magnitude of the change in inductance of the detection coil in the second adjusted state, before and after the flaky metal magnetic powder to be tested is placed in the detection coil. This magnitude is defined as the second adjusted inductance change magnitude. Then, based on the second adjusted inductance change magnitude, obtain the second corrected sensitivity corresponding to the second adjusted state.

[0104] The second corrected sensitivity is then compared with a preset sensitivity threshold. If the second corrected sensitivity is less than the preset sensitivity threshold, the minimum coil turn increase value corresponding to the second adjustment state is obtained, defined as the second adjusted minimum coil turn increase value. It should be understood that the second adjusted minimum coil turn increase value is obtained according to the process of steps 2-1 and 2-2, wherein the difference in the inductance change amplitude involved in the acquisition process is the difference between the second adjusted inductance change amplitude and the preset inductance change amplitude. The second adjusted minimum coil turn increase value is then obtained based on this difference. The second adjusted turns are adjusted a third time based on the obtained second adjusted minimum coil turn increase value to obtain a third adjusted turns number, i.e., the second adjusted minimum coil turn increase value is added to the second adjusted turns number to obtain the third adjusted turns number. It should be understood that if the second corrected sensitivity is greater than or equal to the preset sensitivity threshold, it indicates that after two adjustments, the detection coil turns have met the requirements, and the subsequent cycle process is no longer performed, and the second adjustment state is determined as the latest state.

[0105] The third adjustment state is set to the third adjustment number of turns and the initial excitation current, that is, when the detection coil is in the third adjustment state, the number of turns of the detection coil is the third adjustment number of turns, and the excitation current of the detection coil is the initial excitation current.

[0106] Obtain a third corrected sensitivity when the detection coil is in the third adjusted state and testing the flaky metal magnetic powder to be tested. Similar to the first adjustment process described above, follow steps 1 and 2, replacing the initial state with the third adjusted state. Then, obtain the magnitude of the change in inductance of the detection coil in the third adjusted state, before and after the flaky metal magnetic powder to be tested is placed in the detection coil. This magnitude is defined as the third adjusted inductance change magnitude. The third corrected sensitivity corresponding to the third adjusted state is then obtained based on the third adjusted inductance change magnitude.

[0107] The third corrected sensitivity is then compared with a preset sensitivity threshold. If the third corrected sensitivity is less than the preset sensitivity threshold, the minimum coil turn increase value corresponding to the third adjustment state is obtained, defined as the third adjusted minimum coil turn increase value. It should be understood that the third adjusted minimum coil turn increase value is obtained according to the process of steps 2-1 and 2-2, wherein the difference in the inductance variation involved in the acquisition process is the difference between the third adjusted inductance variation and the preset inductance variation. The third adjusted minimum coil turn increase value is then obtained based on this difference. The third adjusted turns are adjusted a third time based on the obtained third adjusted minimum coil turn increase value to obtain a fourth adjusted turns number. Specifically, the third adjusted minimum coil turn increase value is added to the third adjusted turns number to obtain the fourth adjusted turns number. It should be understood that if the third corrected sensitivity is greater than or equal to the preset sensitivity threshold, it indicates that after three adjustments, the detection coil turns have met the requirements, and the subsequent cycle process is no longer performed. The third adjusted state is determined as the latest state.

[0108] The above cycle process is repeated until the corrected sensitivity corresponding to the latest adjusted number of turns is greater than or equal to the preset sensitivity threshold, and the latest state of the detection coil is obtained. The latest state is the latest adjusted number of turns and initial excitation current.

[0109] It should be understood that the specific calculation method involved in each of the above-mentioned cycles is the same as the corresponding calculation method in step 2. The difference is that the specific parameters involved in the calculation need to be adjusted accordingly.

[0110] It should be understood that in order to facilitate the adjustment of the number of turns, the detection coil may be an inductor coil with an adjustable number of turns.

[0111] Step 3: Obtain the damage probability of the sheet metal magnetic powder to be tested obtained during the detection of the sheet metal magnetic powder to be tested by the detection coil in the latest state.

[0112] According to the latest adjusted number of turns, the detection coil is operated to adjust the number of turns to the latest obtained number of turns, and then the sheet metal magnetic powder to be tested is tested based on the initial excitation current to obtain the damage probability of the sheet metal magnetic powder to be tested.

[0113] In an exemplary embodiment, Figure 5 As shown, the specific process of obtaining the damage probability is given as follows, including:

[0114] Step 3-1: Obtain the temperature non-uniformity of the sheet metal magnetic powder to be tested during the detection of the sheet metal magnetic powder to be tested by the detection coil in the latest state.

[0115] In one exemplary embodiment, multiple temperature sensors are provided, each used to detect the temperature at a different location on the flaky metal magnetic powder to be tested, forming a temperature value set. The number of temperature sensors is determined based on actual needs. To ensure accurate temperature detection, a larger number of temperature sensors may be provided, and the temperature sensors may be non-contact infrared temperature sensors. It should be understood that, during the latest state of testing the flaky metal magnetic powder to be tested, obtaining the temperature detected by each temperature sensor at a specific moment during the testing process can ensure that the temperature at each location on the flaky metal magnetic powder to be tested has reached a certain level and is relatively stable.

[0116] Then, the degree of temperature non-uniformity is obtained based on the temperature value set. In an exemplary embodiment, a specific method for calculating the degree of temperature non-uniformity is given as follows:

[0117] ;

[0118] in, is the degree of temperature non-uniformity, is the maximum temperature value in the temperature value set, is the minimum temperature value in the temperature value set, Indicates the temperature extreme difference. The greater the temperature extreme difference, the greater the temperature unevenness. is the variance of the temperature value set. A larger variance indicates a greater degree of temperature nonuniformity. norm represents a linear normalization function. The degree of temperature nonuniformity is obtained by combining the range and variance.

[0119] When the temperature of the flaky metal magnetic powder to be tested is non-uniform and the temperature difference is large, that is, the greater the temperature non-uniformity, the greater the probability that the flaky metal magnetic powder to be tested will be damaged, and the damage probability is proportional to the temperature non-uniformity.

[0120] Step 3-2: Obtain the actual inductance sequence of the detection coil in the latest state and the adjacent state during the detection process of the sheet metal magnetic powder to be tested, and then calculate the latest inductance difference between the actual inductance sequence in the latest state and the adjacent state.

[0121] The adjacent state is set as the state before the latest state. For example, if the third adjustment state is determined to be the latest state, the second adjustment state is determined to be the state before the latest state, that is, the adjacent state.

[0122] The actual inductance sequence obtained by the detection coil in the latest state when detecting the sheet metal magnetic powder to be measured is obtained, which is defined as the latest actual inductance sequence. The actual inductance sequence obtained by the detection coil in the adjacent state when detecting the sheet metal magnetic powder to be measured is obtained, which is defined as the adjacent actual inductance sequence.

[0123] The inductance difference between the latest actual inductance sequence and the adjacent actual inductance sequence is then calculated, defined as the latest inductance difference. In an exemplary embodiment, the latest actual inductance sequence and the adjacent actual inductance sequence are obtained using the method for obtaining the actual inductance sequence of the detection coil in the initial state described above. Therefore, the latest actual inductance sequence and the adjacent actual inductance sequence contain the same amount of data, and there is a corresponding relationship between the data at the same position in the latest actual inductance sequence and the adjacent actual inductance sequence. The latest inductance difference is then calculated using the following formula:

[0124] ;

[0125] in, Indicates the latest inductance difference, Indicates the absolute value of the inductance difference between the latest actual inductance sequence at the t-th position and the adjacent actual inductance sequence.

[0126] The smaller the latest inductance difference is, the more likely it is that the sheet metal powder to be tested is about to reach or has reached magnetic saturation or has exceeded magnetic saturation. The greater the probability that the sheet metal powder to be tested is damaged, and the damage probability is inversely proportional to the latest inductance difference.

[0127] Step 3-3: Calculate the damage probability based on the temperature non-uniformity and the difference in the latest inductance.

[0128] In an exemplary embodiment, the latest inductance difference is normalized by negative correlation, and then the temperature non-uniformity and the latest inductance difference after negative correlation normalization are multiplied, and the resulting product is used as the damage probability. The negative correlation normalization in this embodiment can be performed in the following general manner: .

[0129] A greater damage probability indicates a more serious problem encountered by the flaky metal magnetic powder being tested. In an exemplary embodiment, the magnetic permeability nondestructive testing method further includes presetting a first damage probability threshold and a second damage probability threshold, wherein the first damage probability threshold is greater than the second damage probability threshold. Both thresholds are values between 0 and 1, and the specific values are set based on actual needs. For example, the first damage probability threshold is 0.6, and the second damage probability threshold is 0.3.

[0130] The damage probability is compared with the first damage probability threshold and the second damage probability threshold. If the damage probability is less than the first damage probability threshold and greater than the second damage probability threshold, indicating that the damage probability is at an intermediate level, the initial excitation current is adjusted based on the damage probability.

[0131] There is no specific limitation on other situations. In an exemplary embodiment, if the damage probability is greater than or equal to the first damage probability threshold, it means that the damage probability is very high. In order to ensure that the sheet metal magnetic powder to be tested is not damaged, an alarm signal can be output so that the staff can take relevant measures as soon as possible, such as stopping the test; if the damage probability is less than or equal to the second damage probability threshold, it means that the damage probability is at a low level, and no other operations can be performed and the test can continue.

[0132] Step 4: Adjust the initial excitation current based on the probability of damage.

[0133] The greater the probability of damage, the greater the reduction in the initial excitation current. In an exemplary embodiment, Figure 6 As shown in Figure 2, the adjustment process of the initial excitation current is as follows:

[0134] Step 4-1: Obtain the excitation current reduction coefficient based on the damage probability and the correlation with the number of inductor turns.

[0135] The difference between the number of turns of the detection coil corresponding to the latest state and the number of turns of the detection coil corresponding to the adjacent state, specifically the absolute value of the difference in the number of turns, is obtained as the latest turn difference.

[0136] The inductor turns correlation is obtained based on the latest turns difference and the latest inductance difference. In one exemplary embodiment, the latest turns difference is normalized and the normalized latest turns difference is multiplied by the negatively correlated normalized latest inductance difference. The resulting product is the inductor turns correlation. The inductor turns correlation indicates the inductance difference caused by an increase in turns. A greater inductor turns correlation indicates a smaller inductance difference caused by an increase in turns, indicating a closer approach to magnetic saturation, and therefore a greater reduction in the excitation current should be achieved.

[0137] Then, the product of the inductance turns correlation and the damage probability is calculated, and the excitation current reduction coefficient is obtained according to the product. In an exemplary embodiment, the product of the inductance turns correlation and the damage probability is used as the excitation current reduction coefficient.

[0138] Step 4-2: Obtain an adjusted excitation current according to the excitation current reduction coefficient and the initial excitation current.

[0139] According to the excitation current reduction coefficient and the initial excitation current, an adjusted excitation current is obtained, wherein the larger the excitation current reduction coefficient is, the greater the reduction amplitude of the initial excitation current is. In an exemplary embodiment, the calculation formula is given as follows:

[0140] ;

[0141] in, is the adjusted excitation current, is the initial excitation current, is the excitation current reduction factor.

[0142] Subsequently, the flaky metal powder to be tested is retested using the newly determined number of turns of the detection coil and the adjusted excitation current, and the magnetic permeability is derived from the resulting inductance. It should be understood that subsequent flaky metal powder can still be tested using the adjusted number of turns and excitation current, ensuring detection accuracy while reducing the risk of damage to the flaky metal powder.

[0143] After the test is complete, damage can be determined for each individual piece of metal powder to determine its damage, obtain the weight of intact and damaged pieces, and calculate the damage ratio. Furthermore, damage characteristics can be used to assess structural safety and reliability, and determine whether to repair or replace the damaged pieces.

[0144] This embodiment further provides a device for nondestructive testing of the magnetic permeability of flaky metal magnetic powder, comprising: a memory and a processor; the memory is connected to the processor, the memory being used to store program instructions; and the processor being used to implement the steps of the above-mentioned embodiment of the method for nondestructive testing of the magnetic permeability of flaky metal magnetic powder when the program instructions are executed.

[0145] In an exemplary embodiment, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for non-destructive testing of magnetic permeability of flaky metal magnetic powder.

[0146] It should be noted that the order in which the embodiments of the present invention are described above is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0147] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

Claims

1. A nondestructive testing method for the magnetic permeability of flaky metal magnetic powder, characterized in that: include: Obtaining an initial sensitivity of the detection coil when detecting the sheet metal magnetic powder to be tested in an initial state, wherein the initial state includes an initial number of turns and an initial excitation current; If the initial sensitivity is less than the preset sensitivity threshold, the initial number of turns is adjusted according to the minimum coil turn increase value to obtain an adjusted number of turns until the corrected sensitivity obtained by the detection coil in the latest state is greater than or equal to the preset sensitivity threshold; the latest state is the latest obtained adjusted number of turns and the initial excitation current; Obtaining a damage probability of the sheet metal magnetic powder to be tested obtained during the detection of the sheet metal magnetic powder to be tested by the detection coil in the latest state; adjusting the initial excitation current based on the damage probability; Obtaining a damage probability of the sheet metal magnetic powder to be tested obtained during the detection of the sheet metal magnetic powder to be tested by the detection coil in the latest state includes: obtaining a degree of temperature non-uniformity of the sheet metal magnetic powder to be tested during the process of the detection coil detecting the sheet metal magnetic powder to be tested in the latest state; Obtaining respectively the actual inductance sequence of the detection coil during the detection of the sheet metal magnetic powder to be tested in the latest state and the adjacent state, and then calculating the latest inductance difference between the actual inductance sequence of the latest state and the adjacent state; the adjacent state being the state preceding the latest state; Obtaining the damage probability according to the temperature non-uniformity and the latest inductance difference; the damage probability is proportional to the temperature non-uniformity and inversely proportional to the latest inductance difference; Adjusting the initial excitation current based on the damage probability includes: Obtaining an excitation current reduction coefficient based on the damage probability and the inductance turns correlation; the inductance turns correlation is obtained by the latest turns difference and the latest inductance difference, where the latest turns difference is the turns difference between the latest state and the adjacent state; An adjusted excitation current is obtained according to the excitation current reduction coefficient and the initial excitation current.

2. The nondestructive testing method for magnetic permeability of flaky metal magnetic powder according to claim 1, wherein: Obtain the initial sensitivity of the detection coil when detecting the sheet metal magnetic powder to be tested in the initial state, including: Obtaining the initial inductance change amplitude of the detection coil in the initial state of the detection coil before and after the sheet metal magnetic powder to be tested is placed in the detection coil; The initial sensitivity is obtained according to the initial inductance variation amplitude.

3. The nondestructive testing method for magnetic permeability of flaky metal magnetic powder according to claim 2, wherein: Obtain the initial inductance change amplitude of the detection coil in its initial state before and after the sheet metal magnetic powder to be tested is placed in the detection coil, including: Obtain the no-load inductance sequence of the detection coil when the detection coil is in the initial state and no sheet metal magnetic powder to be tested is placed in it; Obtaining the actual inductance sequence and actual excitation current sequence of the detection coil in the initial state during the detection of the sheet metal magnetic powder to be tested; Obtain the inductance difference between each corresponding position in the no-load inductance sequence and the actual inductance sequence; The initial inductance variation is obtained using the following formula: ； in, represents the initial inductance change amplitude, T represents the number of data in the sequence, t represents the t-th position in the sequence, represents the actual excitation current at the tth position in the actual excitation current sequence, represents the inductance difference at the t-th position.

4. The method for nondestructive testing of magnetic permeability of flaky metal magnetic powder according to claim 2, wherein: The process of obtaining the minimum coil turns improvement value includes: Obtaining a difference between the initial inductance variation range and a preset inductance variation range; the preset inductance variation range is an inductance variation range corresponding to the preset sensitivity threshold; The minimum coil turns increase value is obtained according to the difference between the initial inductance change amplitude and the preset inductance change amplitude and the relationship between the number of turns of the detection coil and the inductance.

5. The method for nondestructive testing of magnetic permeability of flaky metal magnetic powder according to claim 4, wherein: The calculation formula of the minimum coil turns improvement value is as follows: ； in, is the minimum coil turns increase value, is the initial number of turns, is the initial inductance variation, is the difference between the initial inductance variation and the preset inductance variation, is a preset constant.

6. The nondestructive testing method for magnetic permeability of flaky metal magnetic powder according to claim 1, wherein: The initial number of turns is adjusted according to the minimum coil turn increase value to obtain an adjusted number of turns until the corrected sensitivity of the detection coil in the latest state is greater than or equal to the preset sensitivity threshold, including: Performing a first adjustment on the initial number of turns according to the minimum coil turn increase value to obtain a first adjusted number of turns; Obtaining a first corrected sensitivity of the detection coil obtained by detecting the sheet metal magnetic powder to be tested in a first adjustment state, wherein the first adjustment state includes the first adjustment number of turns and the initial excitation current; If the first correction sensitivity is less than the preset sensitivity threshold, the first adjustment turns are adjusted for a second time according to the first adjustment minimum coil turns increase value corresponding to the first adjustment state to obtain a second adjustment turns; if the first correction sensitivity is greater than or equal to the preset sensitivity threshold, the latest state is the first adjustment state; Obtaining a second corrected sensitivity of the detection coil obtained by detecting the sheet metal magnetic powder to be tested in a second adjustment state, wherein the second adjustment state includes the second adjustment number of turns and the initial excitation current; If the second correction sensitivity is less than the preset sensitivity threshold, the second adjustment number of turns is adjusted for a third time according to the second adjustment minimum coil turn increase value corresponding to the second adjustment state to obtain a third adjustment number of turns; if the second correction sensitivity is greater than or equal to the preset sensitivity threshold, the latest state is the second adjustment state; And so on, the latest state of the detection coil is obtained.

7. The method for nondestructive testing of magnetic permeability of flaky metal magnetic powder according to claim 1, wherein: The magnetic permeability nondestructive testing method further includes: If the damage probability is less than a first damage probability threshold and greater than a second damage probability threshold, the initial excitation current is adjusted based on the damage probability; the first damage probability threshold is greater than the second damage probability threshold.

8. A nondestructive testing device for the magnetic permeability of flaky metal magnetic powder, comprising: Memory and processor; The memory is connected to the processor; The memory is used to store program instructions; The processor is configured to implement the non-destructive testing method for magnetic permeability of flaky metal magnetic powder according to any one of claims 1 to 7 when the program instructions are executed.

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