Nondestructive testing method and device for magnetic conductivity of flaky metal magnetic powder

Abstract

The invention relates to the technical field of magnetic variable measurement, in particular to a nondestructive testing method and device for magnetic conductivity of flaky metal magnetic powder, and the method comprises the following steps: acquiring initial sensitivity obtained by detecting the flaky metal magnetic powder to be detected by a detection coil in an initial state, and if the initial sensitivity is less than a preset sensitivity threshold value, determining that the flaky metal magnetic powder to be detected is detected; if not, adjusting the initial number of turns according to the minimum coil number of turns increase value to obtain an adjusted number of turns until the correction sensitivity of the detection coil in the latest state is greater than or equal to a preset sensitivity threshold value, so as to improve the induction sensitivity of the detection coil to the inductance value of a small-size sample of flaky metal magnetic powder. Further, the accuracy degree of magnetic conductivity detection of the flaky metal magnetic powder is improved; and obtaining the damage probability of the to-be-detected flaky metal magnetic powder obtained in the process that the detection coil detects the to-be-detected flaky metal magnetic powder in the latest state, and adjusting the initial excitation current based on the damage probability to reduce the damage probability of the to-be-detected flaky metal magnetic powder in the detection process.

Description

Technical Field

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

[0002] Sheet-shaped metal magnetic powder is a special metal powder, in which only one dimension is in the sub-micron or nano scale in three-dimensional dimensions, and the other two dimensions are in the micron scale, having a special planar structure. Sheet-shaped metal magnetic powder can be used in the research and development and preparation stages of magnetic materials. By detecting its magnetic permeability, the magnetic permeability of the final product of production activities can be predicted more accurately, unqualified magnetic materials can be quickly screened out, the research and development cost can be saved, and the efficiency of technical improvement and innovation can be improved. However, due to its shape characteristics and the complexity of physical properties, traditional detection methods are likely to damage samples, and the results are not accurate enough. Therefore, a magnetic permeability detection method capable of non-destructive detection of sheet-shaped metal magnetic powder is needed.

[0003] The existing magnetic permeability test method (inductance method) is to place a sample of sheet-shaped metal magnetic powder in a detection coil, and by measuring the change in inductance in the detection coil and establishing the relationship between the inductance value and the magnetic permeability of the sample, the magnetic permeability of the sample is deduced, which can realize non-contact testing of the sample and greatly reduce the probability of sample damage. However, during the magnetic permeability test using the inductance method, in order to improve the sensitivity of the detection coil to small-size samples, the number of turns of the inductance coil is usually directly increased, that is, a higher-turn inductance coil is directly selected as the adjusted detection coil. However, a coil with too high a number of turns usually has a higher magnetic field strength. When testing the magnetic permeability of a sample, the too high magnetic field strength will damage the sample, such as local overheating or magnetic saturation. Summary of the Invention

[0004] In order to solve the technical problem that the existing method for adjusting the number of turns of the detection coil is likely to damage sheet-shaped metal magnetic powder, the purpose of the present invention is to provide a method and device for non-destructive detection of the magnetic permeability of sheet-shaped metal magnetic powder, and the specific technical solutions adopted are as follows: In the first aspect of the present invention, a method for non-destructive detection of the magnetic permeability of sheet-shaped metal magnetic powder is provided, including: Obtaining the initial sensitivity obtained by detecting the sheet-shaped metal magnetic powder to be measured in the initial state of the detection coil, where the initial state is the initial number of turns and the initial excitation current; If the initial sensitivity is less than a 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; Obtain the damage probability of the to-be-detected sheet metal magnetic powder obtained during the detection of the to-be-detected sheet metal magnetic powder by the detection coil in the latest state; Adjust the initial excitation current based on the damage probability.

[0005] Preferably, obtaining the initial sensitivity of the detection coil for detecting the to-be-detected sheet metal magnetic powder in the initial state includes: Obtain the initial inductance change amplitude of the detection coil before and after placing the to-be-detected sheet metal magnetic powder in the detection coil in the initial state; Obtain the initial sensitivity according to the initial inductance change amplitude.

[0006] Preferably, obtaining the initial inductance change amplitude of the detection coil before and after placing the to-be-detected sheet metal magnetic powder in the detection coil in the initial state includes: Obtain the no-load inductance sequence of the detection coil in the initial state and when the to-be-detected sheet metal magnetic powder is not placed; Obtain the actual inductance sequence and the actual excitation current sequence of the detection coil during the detection of the to-be-detected sheet metal magnetic powder in the initial state; Obtain the inductance difference at each corresponding position in the no-load inductance sequence and the actual inductance sequence; Use the following calculation formula to obtain the initial inductance change amplitude: ; where, 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 t-th position in the actual excitation current sequence, represents the inductance difference at the t-th position.

[0007] Preferably, the process of obtaining the minimum coil turn number increase value includes: Obtain the difference between the initial inductance change amplitude and the preset inductance change amplitude; the preset inductance change amplitude is the inductance change amplitude corresponding to the preset sensitivity threshold; According to the difference between the initial inductance change amplitude and the preset inductance change amplitude, and combining the relationship between the number of turns of the detection coil and the inductance, obtain the minimum coil turn number increase value.

[0008] Preferably, the calculation formula for the minimum coil turn number increase value is as follows: ; where, is the minimum coil turn number increase value, is the initial number of turns, is the initial inductance change amplitude, is the difference between the initial inductance change amplitude and the preset inductance change amplitude, is a preset constant.

[0009] Preferably, adjusting the initial number of turns according to the minimum coil turn number 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, includes: Performing a first adjustment on the initial number of turns according to the minimum coil turn number increase value to obtain a first adjusted number of turns; Obtaining a first corrected sensitivity obtained by the detection coil when detecting the to-be-detected sheet-shaped metal magnetic powder in the first adjustment state, where the first adjustment state is the first adjusted number of turns and the initial excitation current; If the first corrected sensitivity is less than the preset sensitivity threshold, then performing a second adjustment on the first adjusted number of turns according to the first adjustment minimum coil turn number increase value corresponding to the first adjustment state to obtain a second adjusted number of turns; if the first corrected sensitivity is greater than or equal to the preset sensitivity threshold, then the latest state is the first adjustment state; Obtaining a second corrected sensitivity obtained by the detection coil when detecting the to-be-detected sheet-shaped metal magnetic powder in the second adjustment state, where the second adjustment state is the second adjusted number of turns and the initial excitation current; If the second corrected sensitivity is less than the preset sensitivity threshold, then performing a third adjustment on the second adjusted number of turns according to the second adjustment minimum coil turn number increase value corresponding to the second adjustment state to obtain a third adjusted number of turns; if the second corrected sensitivity is greater than or equal to the preset sensitivity threshold, then the latest state is the second adjustment state; And so on, to obtain the latest state of the detection coil.

[0010] Preferably, obtaining the damage probability of the to-be-detected sheet-shaped metal magnetic powder obtained during the detection of the to-be-detected sheet-shaped metal magnetic powder by the detection coil in the latest state, includes: Obtaining the temperature non-uniformity degree of the to-be-detected sheet-shaped metal magnetic powder during the detection of the to-be-detected sheet-shaped metal magnetic powder by the detection coil in the latest state; Respectively obtaining the actual inductance sequences during the detection of the to-be-detected sheet-shaped metal magnetic powder by the detection coil in the latest state and the adjacent state, and then calculating the latest inductance difference between the actual inductance sequences of the latest state and the adjacent state; the adjacent state is the previous state of the latest state; Based on the temperature non-uniformity degree and the latest inductance difference, obtain the damage probability; the damage probability is directly proportional to the temperature non-uniformity degree and inversely proportional to the latest inductance difference.

[0011] Preferably, the magnetic permeability non-destructive testing method further includes: If the damage probability is less than the first damage probability threshold and greater than the second damage probability threshold, then adjust the initial excitation current based on the damage probability; the first damage probability threshold is greater than the second damage probability threshold.

[0012] Preferably, adjusting the initial excitation current based on the damage probability includes: According to the damage probability and the inductance turn number correlation, obtain an excitation current reduction coefficient; the inductance turn number correlation is obtained from the latest turn number difference and the latest inductance difference, and the latest turn number difference is the turn number difference between the latest state and the adjacent state; According to the excitation current reduction coefficient and the initial excitation current, obtain the adjusted excitation current.

[0013] In a second aspect of the present invention, there is provided a magnetic permeability non-destructive testing device for sheet metal magnetic powder, including: a memory and a processor; the memory is connected to the processor; the memory is used to store program instructions; the processor is used to implement the above-mentioned magnetic permeability non-destructive testing method for sheet metal magnetic powder when the program instructions are executed.

[0014] The present invention has the following beneficial effects: First, obtain the initial sensitivity obtained by detecting the sheet metal magnetic powder to be measured by the detection coil in the initial state, and then continuously adjust the number of turns of the detection coil according to the magnitude relationship between the sensitivity and the preset sensitivity threshold, so that the sensitivity is greater than or equal to the preset sensitivity threshold, improving the inductance value induction sensitivity of the detection coil to the small-size sample of sheet metal magnetic powder, and further improving the accuracy of the magnetic permeability detection of sheet metal magnetic powder; at the same time, after adjusting the number of turns of the detection coil, obtain the damage probability of the sheet metal magnetic powder to be measured obtained during the detection of the sheet metal magnetic powder to be measured by the detection coil in the latest state, and then adjust the excitation current based on the damage probability to reduce the damage probability of the sheet metal magnetic powder to be measured during the detection process. Description of the Drawings

[0015] Figure 1 is the overall flowchart of a magnetic permeability non-destructive testing method for sheet metal magnetic powder provided in this embodiment; Figure 2 is the logic block diagram of a magnetic permeability non-destructive testing method for sheet metal magnetic powder provided in this embodiment; Figure 3 is the flowchart of the acquisition process of the initial sensitivity; Figure 4 It is a flowchart of the process for obtaining the minimum number of turns increase value of the coil. Figure 5 It is a flowchart of the process for obtaining the damage probability. Figure 6 It is a flowchart of the process for adjusting the initial excitation current. Detailed implementation manners

[0016] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation manners, structures, features and their effects of the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

[0018] The inductance method for testing the magnetic permeability of sheet metal magnetic powder mainly measures the magnetic permeability of sheet metal magnetic powder by utilizing the inductance characteristics of the detection coil. However, since the size of the sheet metal magnetic powder sample is usually small, the amplitude of the inductance change it can cause may be small. Therefore, when testing, the detection coil with a small number of turns may have insufficient sensitivity. In order to improve the sensitivity of the detection coil in the magnetic permeability test of sheet metal magnetic powder, usually the number of turns of the detection coil is increased to amplify the amplitude of the inductance change of the sample, thereby improving the sensitivity of the detection coil. However, after increasing the number of turns of the detection coil, if the excitation parameters do not change, the magnetic field intensity generated by the detection coil will increase synchronously, which is more likely to cause magnetic saturation of the sheet metal magnetic powder sample. At the same time, if the magnetic field is too strong, a larger eddy current effect (especially for conductive materials) may occur in the sheet metal magnetic powder, resulting in local overheating and causing damage to the sheet metal magnetic powder.

[0019] This embodiment provides a non-destructive testing method for the magnetic permeability of sheet metal magnetic powder, aiming to monitor the state of the sheet metal magnetic powder to be tested in real time during the magnetic permeability test process and adjust the excitation parameters of the detection coil, so as to reduce the probability of local overheating or over-magnetization caused by the increase in the number of turns of the coil, and achieve the reduction of the damage probability of the sheet metal magnetic powder during the test while improving the sensitivity of the coil.

[0020] In an exemplary embodiment, after obtaining the flaky metal magnetic powder, preprocessing is performed on the flaky metal magnetic powder 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 during the testing process. Subsequently, the flaky metal magnetic powder is evenly filled into a container, and the filling height generally does not exceed one-third of the inner cavity height of the container. After filling into the container, the to-be-tested flaky metal magnetic powder is obtained, and the to-be-tested flaky metal magnetic powder serves as a sample of the flaky metal magnetic powder. The container filled with the flaky metal magnetic powder is stably placed into the magnetic core cavity of the detection coil.

[0021] After completing the preprocessing of the to-be-tested flaky metal magnetic powder, relevant detection equipment is configured as follows: First, prepare the equipment required for the testing process, including a signal generator, an excitation coil, a detection coil, and a data acquisition module. Among them, the signal generator is used to provide a stable high-frequency electromagnetic excitation; the excitation coil is used to generate an alternating magnetic field, and its shape and structure design should ensure magnetic field uniformity; the detection coil, as an induction inductance coil surrounding the to-be-tested flaky metal magnetic powder, is used to detect the magnetic field response of the to-be-tested flaky metal magnetic powder; the data acquisition module includes a temperature sensor, and other modules can also be set according to actual needs, such as an oscilloscope, etc., for collecting various data during the testing process.

[0022] Subsequently, set the data sampling frequency of the data acquisition module. Among them: The temperature sensor is mainly used to obtain the surface temperature data of the to-be-tested flaky metal magnetic powder, and the data sampling frequency is set to 1 time per second; the oscilloscope is connected to the circuit to monitor the input signal and the response waveform of the sample (such as the magnetic induction signal, voltage or current waveform, etc., corresponding to the waveform of the signal to be detected according to subsequent actual needs), and the data sampling frequency is set to 10 times per second. Arrange the various collected data in chronological order to obtain the corresponding chronological data sequence.

[0023] Place the to-be-tested flaky metal magnetic powder into the detection coil. During the process of detecting the magnetic permeability of the to-be-tested flaky metal magnetic powder, there is a certain relationship between the number of turns of the detection coil and the size and physical characteristics of the to-be-tested flaky metal magnetic powder. For the to-be-tested flaky metal magnetic powder with a smaller size, a stronger magnetic field is required for detection, and the sensitivity of a weaker magnetic field during detection is usually insufficient. When the number of turns of the coil is appropriate, the coil has a larger response amplitude to the parameter changes of the to-be-tested flaky metal magnetic powder. By analyzing the changes in the parameters of the to-be-tested flaky metal magnetic powder and the changes in the coil parameters, it is judged whether the current number of turns of the detection coil is appropriate.

[0024] Figure 1 is the overall flowchart of a method for non-destructively detecting the magnetic permeability of flaky metal magnetic powder provided in this embodiment, Figure 2 is the logical block diagram of a method for non-destructively detecting the magnetic permeability of flaky metal magnetic powder provided in this embodiment.

[0025] As shown in Figure 1 , the method for non-destructive testing of the magnetic permeability of the sheet-shaped metal magnetic powder includes the following steps: Step 1: Obtain the initial sensitivity obtained by detecting the sheet-shaped metal magnetic powder to be tested when the detection coil is in the initial state.

[0026] At the beginning, set the detection coil in the initial state, and the initial state is the initial number of turns and the initial excitation current. That is, when the detection coil is in the initial state, the number of turns of the detection coil is the initial number of turns, and the excitation current is the initial excitation current. It should be understood that the initial number of turns and the initial excitation current are specifically set by the implementer according to the actual situation.

[0027] When the number of turns of the detection coil is the initial number of turns and the excitation current is the initial excitation current, detect the sheet-shaped metal magnetic powder to be tested, and obtain the initial sensitivity of the detection coil to the sheet-shaped metal magnetic powder to be tested.

[0028] In an exemplary embodiment, as shown in Figure 3 , the process of obtaining the initial sensitivity is as follows: Step 1-1: Obtain the initial inductance change amplitude of the detection coil before and after placing the sheet-shaped metal magnetic powder to be tested when the detection coil is in the initial state.

[0029] First, obtain the no-load inductance sequence of the detection coil when the detection coil is in the initial state and the sheet-shaped metal magnetic powder to be tested is not placed. It should be understood that when the detection coil is in the initial state, the detection is started. When the detection is started, the no-load inductance of the detection coil is measured, and a plurality of no-load inductances within a certain time are obtained according to the 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 when the detection is started, and the no-load inductance sequence is a sequence composed of a plurality of inductance values.

[0030] Next, place the sheet metal magnetic powder to be measured into the detection coil and start the detection. When starting the detection, obtain the actual inductance sequence of the detection coil and the actual excitation current sequence during the detection of the sheet metal magnetic powder to be measured in the initial state. Similarly, when starting the detection, start measuring the actual inductance of the detection coil, and at the same sampling frequency as in the no-load state, obtain multiple actual inductances within the same time to form the actual inductance sequence. Therefore, the first inductance value of the actual inductance sequence is the inductance value measured at the start of the detection, and the actual inductance sequence is a sequence composed of multiple inductance values. The acquisition process of the actual excitation current sequence is the same as that of the actual inductance sequence. That is, when starting the detection, start measuring the actual excitation current, and at the same sampling frequency as in the no-load state, obtain multiple actual excitation currents within the same time to form the actual excitation current sequence. Therefore, the first inductance value of the actual excitation current sequence is the actual excitation current measured at the start of the detection, and the actual excitation current sequence is a sequence composed of multiple actual excitation currents.

[0031] It should be understood that the number of data contained in the no-load inductance sequence, the actual inductance sequence, and the actual excitation current sequence is the same, and there is a corresponding relationship between the data at the same positions in the no-load inductance sequence, the actual inductance sequence, and the actual excitation current sequence.

[0032] Then, obtain the inductance difference at each corresponding position between the no-load inductance sequence and the actual inductance sequence. In this embodiment, the inductance difference is specifically the absolute value of the difference in inductance values, and the calculation formula is as follows: ; where t represents the t-th position in the sequence, represents the inductance difference at the t-th position, is the actual inductance value at the t-th position in the actual inductance sequence, is the no-load inductance value at the t-th position in the no-load inductance sequence.

[0033] Finally, use the following calculation formula to obtain the initial inductance change amplitude: ; where, represents the initial inductance change amplitude, T represents the number of data in the sequence, represents the actual excitation current at the t-th position in the actual excitation current sequence.

[0034] It should be noted that when the excitation current is larger, the magnetic field strength of the detection coil should be larger, so the inductance change difference should be more obvious. Therefore, a larger weight is set for a larger excitation current.

[0035] Step 1-2: Obtain the initial sensitivity according to the initial inductance change amplitude.

[0036] The greater the initial inductance change amplitude, the stronger the sensitivity of the detection coil to the sheet metal magnetic powder to be measured. Therefore, according to the initial inductance change amplitude, the initial sensitivity is obtained, 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 carried out in the following general manner: . Where z is the data to be normalized, is the exponential function with the natural constant e as the base.

[0037] Step 2: If the initial sensitivity is less than the preset sensitivity threshold, adjust the initial number of turns 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.

[0038] Preset a sensitivity threshold, and the value of this preset sensitivity threshold is set according to actual needs. In this embodiment, it is set to 0.4.

[0039] Compare the preset sensitivity threshold 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 sheet metal magnetic powder to be measured, and the subsequent steps will not be executed, and this situation will not be described in detail. The following specifically describes the situation where the initial sensitivity is less than the preset sensitivity threshold.

[0040] 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. As Figure 4 shown, the obtaining process includes: Step 2-1: Obtain the difference between the initial inductance change amplitude and the preset inductance change amplitude.

[0041] The initial inductance change amplitude is obtained through the above steps, and then the inductance change amplitude corresponding to the preset sensitivity threshold is obtained, which is defined as the preset inductance change amplitude. It should be understood that since the preset sensitivity threshold is a preset and known threshold, the preset inductance change amplitude is also a preset and known threshold. In an exemplary embodiment, the preset inductance change amplitude can be obtained in the following manner: By using the process of Step 1 and continuously adjusting the number of turns of the detection coil, the inductance change amplitude and sensitivity corresponding to each number of turns can be obtained. Then, find the inductance change amplitude corresponding to the sensitivity with the same value as the preset sensitivity threshold as the preset inductance change amplitude.

[0042] Obtain the difference between the initial inductance change amplitude and the preset inductance change amplitude, specifically the absolute value of the difference between the initial inductance change amplitude and the preset inductance change amplitude. This difference between the initial inductance change amplitude and the preset inductance change amplitude is the theoretical improvement value of the initial inductance change amplitude.

[0043] Step 2-2: According to the difference between the initial inductance change amplitude and the preset inductance change amplitude, and in combination with the relationship between the number of turns of the detection coil and the inductance, obtain the minimum number of turns increase value of the coil.

[0044] It should be understood that the basic relationship between inductance and the number of turns of the coil is: ; where L represents inductance, represents magnetic permeability; represents the number of turns of the detection coil; represents the cross-sectional area of the detection coil; represents the length of the detection coil.

[0045] Then, the relationship between the initial number of turns of the detection coil and the inductance is: ; where represents magnetic permeability; represents the initial number of turns of the detection coil.

[0046] Change amplitude The theoretical model after improvement is: ; where is the difference between the initial inductance change amplitude and the preset inductance change amplitude, represents the minimum number of turns increase value of the detection coil.

[0047] Since the sheet metal magnetic powder to be measured does not change and does not adjust the cross-sectional area, length, etc. of the detection coil, the magnetic permeability of the sheet metal magnetic powder to be measured does not change, and calculate the minimum number of turns increase value , and the calculation formula is as follows: ; In the formula, represents a preset constant, and an empirical value of 0.01 can be taken, which is used to avoid the possibility of the denominator of the fraction being zero.

[0048] Then, adjust the initial number of turns according to the obtained minimum number of turns increase value, including the following adjustment process: First, perform the first adjustment on the initial number of turns according to the minimum coil turn number increase value to obtain the first adjusted number of turns. Specifically, add the initial number of turns to the minimum coil turn number increase value to obtain the first adjusted number of turns.

[0049] Set the first adjustment state as the first adjusted 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 adjusted number of turns, and the excitation current of the detection coil is the initial excitation current.

[0050] Obtain the first corrected sensitivity obtained by detecting the to-be-detected sheet metal magnetic powder when the detection coil is in the first adjustment state. It should be understood that according to the processes of Step 1 and Step 2, where the initial state is replaced by the first adjustment state, then, when the detection coil is in the first adjustment state, the change amplitude of the inductance of the detection coil before and after placing the to-be-detected sheet metal magnetic powder is defined as the first adjustment inductance change amplitude, and then according to the first adjustment inductance change amplitude, the first corrected sensitivity corresponding to the first adjustment state is obtained.

[0051] Then, compare the size relationship between the first corrected sensitivity and the preset sensitivity threshold. If the first corrected sensitivity is still less than the preset sensitivity threshold, obtain the minimum coil turn number increase value corresponding to the first adjustment state, defined as the first adjustment minimum coil turn number increase value. It should be understood that the first adjustment minimum coil turn number increase value is obtained according to the processes of Step 2-1 and Step 2-2, where the difference in the inductance change amplitude involved in the obtaining process is the difference between the first adjustment inductance change amplitude and the preset inductance change amplitude, and then the first adjustment minimum coil turn number increase value is obtained according to this difference. Perform the second adjustment on the first adjusted number of turns according to the obtained first adjustment minimum coil turn number increase value to obtain the second adjusted number of turns, that is, add the first adjustment minimum coil turn number increase value to the first adjusted number of turns to obtain the second adjusted number of turns. It should be understood that if the first corrected sensitivity is greater than or equal to the preset sensitivity threshold, it means that after one adjustment, the number of turns of the detection coil already meets the requirements, and no subsequent loop process is performed, and the first adjustment state is determined as the latest state.

[0052] Set the second adjustment state as the second adjusted 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 adjusted number of turns, and the excitation current of the detection coil is the initial excitation current.

[0053] Obtain the second corrected sensitivity obtained by detecting the to-be-detected sheet-shaped metal magnetic powder when the detection coil is in the second adjustment state. Similarly to the above first adjustment process, follow the processes of step 1 and step 2, where the initial state is replaced by the second adjustment state. Then, obtain the inductance change amplitude of the detection coil before and after placing the to-be-detected sheet-shaped metal magnetic powder when the detection coil is in the second adjustment state, which is defined as the second adjustment inductance change amplitude. Then, based on the second adjustment inductance change amplitude, obtain the second corrected sensitivity corresponding to the second adjustment state.

[0054] Then compare the magnitude relationship between the second corrected sensitivity and the preset sensitivity threshold. If the second corrected sensitivity is less than the preset sensitivity threshold, obtain the minimum coil turn number increase value corresponding to the second adjustment state, which is defined as the second adjustment minimum coil turn number increase value. It should be understood that the second adjustment minimum coil turn number increase value is obtained according to the processes of step 2-1 and step 2-2, where the difference in the inductance change amplitude involved in the obtaining process is the difference between the second adjustment inductance change amplitude and the preset inductance change amplitude. Then, based on this difference, obtain the second adjustment minimum coil turn number increase value. Perform a third adjustment on the second adjustment turn number according to the obtained second adjustment minimum coil turn number increase value to obtain the third adjustment turn number, that is, add the second adjustment minimum coil turn number increase value to the second adjustment turn number to obtain the third adjustment turn number. It should be understood that if the second corrected sensitivity is greater than or equal to the preset sensitivity threshold, it means that after two adjustments, the turn number of the detection coil already meets the requirements, and no subsequent loop process is performed, and the second adjustment state is determined as the latest state.

[0055] Set the third adjustment state as the third adjustment turn number and the initial excitation current, that is, when the detection coil is in the third adjustment state, the turn number of the detection coil is the third adjustment turn number, and the excitation current of the detection coil is the initial excitation current.

[0056] Obtain the third corrected sensitivity obtained by detecting the to-be-detected sheet-shaped metal magnetic powder when the detection coil is in the third adjustment state. Similarly to the above first adjustment process, follow the processes of step 1 and step 2, where the initial state is replaced by the third adjustment state. Then, obtain the inductance change amplitude of the detection coil before and after placing the to-be-detected sheet-shaped metal magnetic powder when the detection coil is in the third adjustment state, which is defined as the third adjustment inductance change amplitude. Then, based on the third adjustment inductance change amplitude, obtain the third corrected sensitivity corresponding to the third adjustment state.

[0057] Then compare the magnitude relationship between the third corrected sensitivity and the preset sensitivity threshold. If the third corrected sensitivity is less than the preset sensitivity threshold, obtain the minimum coil turn increment value corresponding to the third adjustment state, which is defined as the third adjustment minimum coil turn increment value. It should be understood that the third adjustment minimum coil turn increment value is obtained according to the processes of Step 2-1 and Step 2-2. Among them, the difference in the inductance change range involved in the obtaining process is the difference between the third adjustment inductance change range and the preset inductance change range. Then, based on this difference, the third adjustment minimum coil turn increment value is obtained. Perform a third adjustment on the third adjusted number of turns according to the obtained third adjustment minimum coil turn increment value to obtain the fourth adjusted number of turns, that is, add the third adjustment minimum coil turn increment value to the third adjusted number of turns to obtain the fourth adjusted number of turns. It should be understood that if the third corrected sensitivity is greater than or equal to the preset sensitivity threshold, it means that after three adjustments, the number of turns of the detection coil has met the requirements, and no subsequent loop process is performed. The third adjustment state is determined as the latest state.

[0058] Perform the above loop process sequentially until the corrected sensitivity corresponding to the latest adjusted number of turns is greater than or equal to the preset sensitivity threshold, then obtain the latest state of the detection coil. The latest state is the latest obtained adjusted number of turns and the initial excitation current.

[0059] It should be understood that the specific calculation methods involved in the above loop processes are the same as the corresponding calculation methods in Step 2. The difference is that the specific parameters involved in the calculation need to be adjusted correspondingly.

[0060] It should be understood that for the convenience of turn adjustment, the detection coil can be an inductive coil with adjustable turns.

[0061] Step 3: Obtain the damage probability of the to-be-detected sheet-shaped metal magnetic powder during the detection process of the detection coil in the latest state.

[0062] According to the latest adjusted number of turns, operate on the detection coil, adjust its number of turns to the latest obtained number of turns, and then based on the initial excitation current, detect the to-be-detected sheet-shaped metal magnetic powder to obtain the damage probability of the to-be-detected sheet-shaped metal magnetic powder.

[0063] In an exemplary embodiment, as Figure 5 shown, the following gives the specific obtaining process of the damage probability, including: Step 3-1: Obtain the temperature non-uniformity degree of the to-be-detected sheet-shaped metal magnetic powder during the detection process of the detection coil in the latest state.

[0064] In an exemplary embodiment, a plurality of temperature sensors are provided. Each temperature sensor is used to detect the temperature values at different positions of the sheet-shaped metal magnetic powder to be measured, forming a set of temperature values. Among them, the number of temperature sensors is set according to actual needs. To ensure the accuracy of temperature detection, more temperature sensors can be set, and the temperature sensors can be non-contact infrared temperature sensors. It should be understood that during the detection process of the sheet-shaped metal magnetic powder to be measured in the latest state, obtaining the temperatures detected by each temperature sensor at a certain moment during the detection process can ensure that the temperatures at various positions of the sheet-shaped metal magnetic powder to be measured have reached a certain level and the temperature values are relatively stable.

[0065] Then, the temperature non-uniformity degree is obtained according to this set of temperature values. In an exemplary embodiment, a specific calculation method of the temperature non-uniformity degree is given as follows: ; Wherein, is the temperature non-uniformity degree, is the maximum temperature value in the set of temperature values, is the minimum temperature value in the set of temperature values, represents the temperature range. The larger the temperature range, the greater the temperature non-uniformity degree; is the variance of the set of temperature values. The larger the variance, the greater the temperature non-uniformity degree, and norm represents the linear normalization function. The temperature non-uniformity degree is obtained jointly from two aspects of the range and the variance.

[0066] When the temperature of the sheet-shaped metal magnetic powder to be measured is non-uniform and the temperature difference is large, that is, the greater the temperature non-uniformity degree, the greater the probability of damage to the sheet-shaped metal magnetic powder to be measured, and the damage probability is proportional to the temperature non-uniformity degree.

[0067] Step 3-2: Respectively obtain the actual inductance sequences during the detection process of the sheet-shaped metal magnetic powder to be measured by the detection coil in the latest state and the adjacent state, and then calculate the latest inductance difference between the actual inductance sequences in the latest state and the adjacent state.

[0068] Set the adjacent state as the previous state of the latest state. For example: If the third adjustment state is determined as the latest state, then the second adjustment state is determined as the previous state of the latest state, that is, the adjacent state.

[0069] Obtain the actual inductance sequence obtained by the detection coil during the detection of the sheet-shaped metal magnetic powder to be measured in the latest state, which is defined as the latest actual inductance sequence, and obtain the actual inductance sequence obtained by the detection coil during the detection of the sheet-shaped metal magnetic powder to be measured in the adjacent state, which is defined as the adjacent actual inductance sequence.

[0070] Then, calculate the inductance difference between the latest actual inductance sequence and the adjacent actual inductance sequence, which is defined as the latest inductance difference. In an exemplary embodiment, the latest actual inductance sequence and the adjacent actual inductance sequence are obtained by using the method for obtaining the actual inductance sequence of the detection coil in the initial state described above. Then, the number of data contained in the latest actual inductance sequence and the adjacent actual inductance sequence is the same, 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. Furthermore, use the following calculation formula to calculate the latest inductance difference: ; Wherein, represents the latest inductance difference, represents the absolute value of the inductance difference between the latest actual inductance sequence and the adjacent actual inductance sequence at the t-th position.

[0071] When the latest inductance difference is smaller, it indicates that the to-be-detected sheet-shaped metal magnetic powder is about to reach or has reached magnetic saturation or exceeded magnetic saturation, and the probability of damage to the to-be-detected sheet-shaped metal magnetic powder is greater. The damage probability is inversely proportional to the latest inductance difference.

[0072] Step 3-3: Obtain the damage probability according to the temperature non-uniformity degree and the latest inductance difference.

[0073] In an exemplary embodiment, perform negative correlation normalization on the latest inductance difference, and then multiply the temperature non-uniformity degree by the negatively correlated normalized latest inductance difference, and use the obtained product as the damage probability. The negative correlation normalization in this embodiment can adopt the following general method: .

[0074] The greater the damage probability, the more serious the problem encountered by the to-be-detected sheet-shaped metal magnetic powder. In an exemplary embodiment, the permeability non-destructive testing method further includes: presetting a first damage probability threshold and a second damage probability threshold, where the first damage probability threshold is greater than the second damage probability threshold, and both of these thresholds are values between 0 and 1. The specific values are set according to actual judgment needs. For example, the first damage probability threshold is 0.6 and the second damage probability threshold is 0.3.

[0075] Compare the size relationship between the damage probability and 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, then adjust the initial excitation current based on the damage probability.

[0076] For other cases, no specific limitations are required. In an exemplary embodiment, if the damage probability is greater than or equal to the first damage probability threshold, it indicates that the damage probability is very high. 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 detection. If the damage probability is less than or equal to the second damage probability threshold, it indicates that the damage probability is at a relatively low level, and no other operations need to be performed, and the detection can continue.

[0077] Step 4: Adjust the initial excitation current based on the damage probability.

[0078] The greater the damage probability, the greater the reduction amplitude of the initial excitation current. In an exemplary embodiment, as Figure 6 shown, the adjustment process of the initial excitation current is as follows: Step 4-1: Obtain the excitation current reduction coefficient according to the damage probability and the inductance-turn correlation.

[0079] Obtain 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, as the latest turn difference.

[0080] Obtain the inductance-turn correlation according to the latest turn difference and the latest inductance difference. In an exemplary embodiment, normalize the latest turn difference, and multiply the normalized latest turn difference by the negatively correlated normalized latest inductance difference. The obtained product is the inductance-turn correlation. The inductance-turn correlation represents the inductance difference caused by the increase in the number of turns. The greater the inductance-turn correlation, the smaller the inductance difference caused by the increase in the number of turns, indicating that it is closer to magnetic saturation, and the greater the reduction amplitude of the excitation current should be.

[0081] Then calculate the product of the inductance-turn correlation and the damage probability, and obtain the excitation current reduction coefficient according to this product. In an exemplary embodiment, use the product of the inductance-turn correlation and the damage probability as the excitation current reduction coefficient.

[0082] Step 4-2: Obtain the adjusted excitation current according to the excitation current reduction coefficient and the initial excitation current.

[0083] Obtain the adjusted excitation current according to the excitation current reduction coefficient and the initial excitation current. Among them, the greater the excitation current reduction coefficient, the higher the reduction amplitude of the initial excitation current. In an exemplary embodiment, the following calculation formula is given: ; Among them, is the adjusted excitation current, is the initial excitation current, is the excitation current reduction coefficient.

[0084] In the following, according to the latest number of turns of the detection coil and the adjusted excitation current, the sheet-shaped metal magnetic powder to be measured is re-detected, and the magnetic permeability is obtained based on the obtained inductance value. It should be understood that the adjusted number of turns and excitation current can still be used to detect the subsequent sheet-shaped metal magnetic powder, and on the basis of ensuring the detection accuracy, the damage probability of the sheet-shaped metal magnetic powder is reduced.

[0085] In the following, after the test, it is also possible to judge the damage of each sheet-shaped metal magnetic powder in the sheet-shaped metal magnetic powder to be measured, obtain the weights of the non-damaged and damaged ones, and calculate the damage ratio. At the same time, it is also possible to evaluate the structural safety and reliability, make repair or replacement decisions, etc. for the damage characteristics of the damaged ones.

[0086] This embodiment also provides a non-destructive detection device for the magnetic permeability of sheet-shaped metal magnetic powder, including: a memory and a processor; the memory is connected to the processor, and the memory is used to store program instructions; the processor is used to implement the steps in the above-mentioned non-destructive detection method embodiment of the magnetic permeability of sheet-shaped metal magnetic powder when the program instructions are executed.

[0087] In an exemplary embodiment, the present invention provides a computer-readable storage medium storing a computer program, which implements the steps in the above-mentioned non-destructive detection method embodiment of the magnetic permeability of sheet-shaped metal magnetic powder when executed by a processor.

[0088] It should be noted that: the above-mentioned sequence of embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0089] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the 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 the initial sensitivity of the detection coil when detecting the sheet metal magnetic powder to be detected in the initial state, wherein the initial state is the initial number of turns and the 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 turns 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; the latest state is the latest 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 process of detecting the sheet metal magnetic powder to be tested by the detection coil in the latest state; The initial excitation current is adjusted based on the damage probability.

2. The nondestructive testing method for magnetic permeability of flaky metal magnetic powder according to claim 1, characterized in that: The initial sensitivity of the detection coil when detecting the sheet metal magnetic powder to be detected is obtained 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, characterized in that: Obtain the initial inductance change amplitude of the detection coil in the initial state, before and after the detection coil is placed, of the sheet metal magnetic powder to be tested. This includes: Obtaining the no-load inductance sequence of the detection coil when the detection coil is in an initial state and no sheet metal magnetic powder to be tested is placed in it; Obtaining the actual inductance sequence and the actual excitation current sequence of the detection coil when the detection coil is in the initial state and during the detection of the sheet metal magnetic powder to be detected; Obtaining the inductance difference between each corresponding position in the no-load inductance sequence and the actual inductance sequence; The initial inductance variation amplitude is obtained by the following calculation 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 tth position.

4. The nondestructive testing method for magnetic permeability of flaky metal magnetic powder according to claim 2, characterized in that: 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 turns of the detection coil and the inductance.

5. The nondestructive testing method for magnetic permeability of flaky metal magnetic powder according to claim 4, characterized in that: The calculation formula for 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 range and the preset inductance variation range, is a preset constant.

6. The nondestructive testing method for magnetic permeability of flaky metal magnetic powder according to claim 1, characterized in that: 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 when detecting the sheet metal magnetic powder to be detected in a first adjustment state, wherein the first adjustment state is 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 the 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 when detecting the sheet metal magnetic powder to be detected in a second adjustment state, wherein the second adjustment state is 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 turns are adjusted for a third time according to the second adjustment minimum coil turns increase value corresponding to the second adjustment state to obtain the third adjustment 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 nondestructive testing method for magnetic permeability of flaky metal magnetic powder according to claim 1, characterized in that: Obtaining the damage probability of the sheet metal magnetic powder to be tested obtained during the process of the detection coil detecting the sheet metal magnetic powder to be tested in the latest state, includes: Obtaining the 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; The actual inductance sequence of the detection coil in the latest state and the adjacent state during the detection of the sheet metal magnetic powder to be detected is obtained respectively, and then the latest inductance difference between the actual inductance sequence of the latest state and the adjacent state is calculated; the adjacent state is the state before the latest state; 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.

8. The nondestructive testing method for magnetic permeability of flaky metal magnetic powder according to claim 1, characterized in that: The magnetic permeability nondestructive testing method further comprises: 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.

9. The nondestructive testing method for magnetic permeability of flaky metal magnetic powder according to claim 7, characterized in that: Adjusting the initial excitation current based on the damage probability includes: According to the damage probability and the inductance turns correlation, an excitation current reduction coefficient is obtained; the inductance turns correlation is obtained by the latest turns difference and the latest inductance difference, and 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.

10. A nondestructive testing device for 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 used to implement the non-destructive testing method for magnetic permeability of flaky metal magnetic powder according to any one of claims 1 to 9 when the program instructions are executed.

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