A method and system for distinguishing between electrical eddy current signal anomalies

Abstract

The application discloses a kind of measurement method and system for distinguishing eddy current signal anomaly, belong to eddy current signal anomaly measurement field.Preset at least three sequentially reduced scanning time, after selecting a scanning time each time, probe is vertically scanned according to the selected scanning time respectively on the surface of sample with defect and the surface of sample with internal resistance uneven, the amplitude of the eddy current waveform of two kinds of samples is recorded respectively, the change of amplitude with the decrease of scanning time is judged, i.e.The source of eddy current anomaly signal can be determined.The application distinguishes whether the eddy current anomaly signal is caused by resistance uneven or internal defect of matrix by controlling the scanning speed of probe, and the measurement method is more simple.

Description

Technical Field

[0001] This invention relates to the field of eddy current signal anomaly measurement, and in particular to a measurement method and system for distinguishing eddy current signal anomalies. Background Technology

[0002] Eddy current testing is a common non-destructive testing method for defects. When defects exist within a material, they cause abrupt changes in local electromagnetic properties, leading to alterations in the eddy current electric field within the material. Electromagnetic induction causes changes in the magnetic field, which are ultimately reflected in changes in the current within the signal receiving coil. Based on this principle, eddy currents can be used to detect defects inside or on the surface of materials. However, when measuring metallic conductors, because metallic structural materials often undergo heat treatment, uneven temperature and cooling rates after high-temperature heat treatment can easily lead to uneven electromagnetic properties, resulting in abnormal eddy current signals during eddy current testing and interfering with defect detection.

[0003] Eddy current signals caused by defects are usually abrupt. Abnormal signals formed when a sample moves from a normal region across a defect and returns to the normal region usually form loop signals (e.g., ...). Figure 1 As shown in part (a)). The eddy current anomaly signal generated by changes in the electromagnetic signal of the material is continuously changing, while the eddy current anomaly signal caused by changes in its electromagnetic properties has no fixed shape (e.g., ...). Figure 1 (as shown in part (b) of the diagram). Therefore, the two signals can be distinguished by their signal shapes. Figure 1 In this context, "Phase" represents phase and "Amplitude" represents amplitude.

[0004] Current methods for identifying the source of eddy current signal anomalies are problematic in actual production. Uneven sample surfaces or probe tilting / lifting during operation can cause the eddy current signal to deviate from the screen center. This necessitates recalibrating the signal back to the center, a process repeated repeatedly during testing, resulting in significant time waste. In large-scale testing, to improve efficiency, high-pass filters are typically used. While filtering high-frequency interference signals, the test signal automatically returns to the screen center at short intervals. Although this improves efficiency, the automatic zeroing process can lead to… Figure 1 In part (b) of the diagram, the signal also presents a closed loop, making it impossible to distinguish the source of the eddy current signal anomaly. In other words, existing methods cannot simultaneously achieve both efficiency and accuracy. Summary of the Invention

[0005] The purpose of this invention is to provide a measurement method and system for distinguishing abnormal eddy current signals, thereby identifying the source of abnormal eddy current signals through a simple measurement method.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A measurement method for distinguishing eddy current signal anomalies, comprising:

[0008] Predefining at least three scanning times that decrease in turn;

[0009] Selecting one scanning time at a time in descending order of scanning time;

[0010] After selecting one scanning time at a time, vertically scanning the surface of a sample with defects and the surface of a sample with internal resistance unevenness with the probe according to the selected scanning time, and recording the amplitude of the eddy current waveform, and vertically scanning the surface of the sample with internal resistance unevenness with the probe according to the same scanning time, and recording the amplitude of the eddy current waveform;

[0011] Respectively determining the change of the amplitude recorded by the sample with defects and the sample with internal resistance unevenness with the decrease of the scanning time, and determining the source of the eddy current anomaly signal according to the change of the amplitude.

[0012] A measurement system for distinguishing eddy current signal anomalies, comprising: an eddy current detection device and a determination module;

[0013] The eddy current detection device is used to vertically scan the surface of a sample with defects and the surface of a sample with internal resistance unevenness with the probe according to the selected scanning time after selecting one scanning time at a time, and record the amplitude of the eddy current waveform, and vertically scan the surface of the sample with internal resistance unevenness with the probe according to the same scanning time, and record the amplitude of the eddy current waveform; wherein at least three scanning times that decrease in turn are predefined, and one scanning time is selected at a time in descending order of scanning time;

[0014] The determination module is used to determine the change of the amplitude of the sample with defects and the sample with internal resistance unevenness with the decrease of the scanning time, and determine the source of the eddy current anomaly signal according to the change of the amplitude.

[0015] According to the specific embodiments provided by the present application, the following technical effects are disclosed:

[0016] The present application discloses a measurement method and system for distinguishing eddy current signal anomalies, at least three scanning times that decrease in turn are predefined, one scanning time is selected at a time, and then the probe is vertically scanned on the surface of a sample with defects and the surface of a sample with internal resistance unevenness according to the selected scanning time, the amplitude of the eddy current waveform of the two kinds of samples is recorded respectively, the change of the amplitude with the decrease of the scanning time is determined, and the source of the eddy current anomaly signal can be determined. The present application distinguishes whether the eddy current anomaly signal is caused by resistance unevenness or internal defects of the substrate by controlling the scanning speed of the probe, and the measurement method is more simple and convenient. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0018] Figure 1 An existing eddy current anomaly signal schematic diagram;

[0019] Figure 2 A flow chart of a measurement method for distinguishing eddy current signal anomalies provided by the embodiment of the present application;

[0020] Figure 3 A principle diagram of a measurement method for distinguishing eddy current signal anomalies provided by the embodiment of the present application;

[0021] Figure 4 A blade local diagram of eddy current signal anomalies caused by internal resistance unevenness provided by the embodiment of the present application;

[0022] Figure 5 A sample diagram with a man-made defect in the middle of a smooth surface provided by the embodiment of the present application. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments only constitute some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0024] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0025] The present application distinguishes whether the eddy current anomaly signal is caused by resistance unevenness or internal defects of the base body by controlling the probe scanning speed.

[0026] As shown in Figure 2 The embodiment of the present application provides a measurement method for distinguishing eddy current signal anomalies, which comprises:

[0027] Step 1: preset at least three scanning times in descending order.

[0028] Step 2: select a scanning time each time in the order of scanning time from large to small.

[0029] Step 3: After selecting a scanning time, the probe is vertically scanned over the surface of the sample with defects according to the selected scanning time, and the amplitude of the eddy current waveform is recorded. The probe is vertically scanned over the surface of the sample with internal resistance unevenness according to the same scanning time, and the amplitude of the eddy current waveform is recorded.

[0030] Step 4: The change of the amplitude recorded by the sample with defects and the sample with internal resistance unevenness with the decrease of the scanning time is determined respectively, and the source of the eddy current abnormal signal is determined according to the change of the amplitude.

[0031] The source of the eddy current abnormal signal is determined according to the change of the amplitude, and specifically includes:

[0032] If the amplitude increases with the decrease of the scanning time, it is determined that the source of the eddy current abnormal signal is the change of the electromagnetic properties of the material caused by the internal resistance unevenness. If the amplitude does not change with the decrease of the scanning time, it is determined that the source of the eddy current abnormal signal is the defect.

[0033] Reference Figure 3 The measurement method of the application is illustrated in detail by taking a sample with defects, which has a smooth surface with a man-made defect in the middle, and a sample with internal resistance unevenness, which is a blade with abnormal eddy current signal caused by internal resistance unevenness, as examples.

[0034] Step 1: Start the high-pass filter of the eddy current detection, vertically scan the probe over the surface of the sample with a smooth surface with a man-made defect in the middle (such as shown in FIG. 1), record the scanning time of the sample as T1 (i.e. the period T of the vertical scanning of the probe over the surface of the sample), and the amplitude of the Y-axis of the eddy current waveform graph as A1. Then, scan the probe over the blade with abnormal eddy current signal caused by internal resistance unevenness (such as shown in FIG. 2) at the same time, and record the amplitude A11 of the Y-axis. Figure 5 Figure 4

[0035] Step 2: Shorten the scanning time of the sample in step 1 to one half of the original time, denoted as T2 (i.e. ), at this time the amplitude of the Y-axis of the eddy current waveform graph is A2. Scan the blade with the abnormal eddy current signal with the time T2, and record the amplitude A21 of the Y-axis of the measured blade eddy current signal.

[0036] Step 3: Shorten the scanning time of the sample in step 1 to one fourth of the original time, denoted as T3 (i.e. ), at this time the amplitude of the Y-axis of the eddy current waveform graph is A3. Scan the blade with the time T3, and record the amplitude A31 of the Y-axis.

[0037] Step 4: Change the scanning rate at least 3 times, record and compare the change of the Y-axis amplitude of the eddy current abnormal signal after changing the scanning rate, and determine the cause of the abnormal eddy current signal.

[0038] ​​The recorded results of the eddy current anomaly Y-axis amplitude of the sample and the blade are shown in Table 1 and Table 2 respectively.

[0039] Table 1: Eddy current amplitude obtained by three measurements of the sample

[0040]

[0041] Table 2: Eddy current amplitude obtained by three measurements of the blade

[0042]

[0043] It can be seen from the measurement results that the eddy current signal anomaly caused by the defect does not change with the change of the scanning speed, while the eddy current anomaly caused by the change of the electromagnetic properties of the material becomes larger as the scanning speed increases. This is because the defect size is extremely small and the time for the probe to pass through the defect is extremely short, which is much smaller than the time for the device to automatically reset after opening the high-pass filter. The defect signal is always recorded completely. The eddy current anomaly caused by the change of the material properties is continuous, and the signal is always changing as the probe moves across the surface of the sample. When the probe moves at a slower speed, the eddy current signal change on the entire sample has not been completely recorded before the signal is automatically reset, resulting in a decrease in the amplitude of the eddy current anomaly.

[0044] In summary, the eddy current signal amplitude of the defect obtained by measuring at different speeds is significantly different from the amplitude of the eddy current signal anomaly caused by the resistance unevenness of the material itself. The signal anomaly caused by the resistance of the material changes with the measurement speed, while the defect does not change with the change of the measurement speed.

[0045] The present application is simple to measure, easy to observe, easy to distinguish the source of the eddy current signal anomaly, short test time and high reliability.

[0046] Eddy current: According to the principle of Faraday electromagnetic induction, when a block-shaped metal conductor is placed in a changing magnetic field or moves in a magnetic field (irrespective of whether the metal is block-shaped or not, and irrespective of whether the magnetic field is changing or not), an induced current in the form of a vortex will be generated in the conductor. This current is called eddy current.

[0047] Eddy current testing: The high-frequency oscillating current in the preamplifier flows into the probe coil through the extension cable, generating an alternating magnetic field in the coil at the head of the probe. When the metal body to be measured approaches this magnetic field, an induced current is generated on the surface of the metal. At the same time, the eddy current field also generates an alternating magnetic field in the opposite direction to the head coil. Due to the reaction, the amplitude and phase of the high-frequency current in the head coil are changed (the effective impedance of the coil). Through the processing of the electronic circuit in the preamplifier, the change in the impedance of the coil is converted into a change in voltage or current. The size of the output signal changes with the distance between the probe and the surface of the measured body. The eddy current sensor measures the displacement, vibration and other parameters of the metal object based on this principle.

[0048] Eddy current signal anomaly: the measured eddy current signal forms a loop due to the defects existing in the measured substrate.

[0049] High-pass filter: high-pass filter is a filtering method, the rule is that high-frequency signals can pass normally, and low-frequency signals below the set threshold are blocked or weakened. However, the amplitude of blocking or weakening will change according to different frequencies and different filtering programs (purposes).

[0050] Blade: refers to the high-pressure turbine blade, which is an important component of the turbine section in the gas turbine engine. The high-speed rotating blade is responsible for sucking the high-temperature and high-pressure airflow into the combustor to maintain the operation of the engine.

[0051] In order to perform the measurement method of the above embodiment to achieve the corresponding functions and technical effects, a measurement system for distinguishing eddy current signal anomalies is provided below, including: an eddy current detection device and a determination module.

[0052] The eddy current detection device is used to vertically scan the surface of the defect-containing sample with the probe according to the selected scan time after selecting one scan time each time, record the amplitude of the eddy current waveform, and vertically scan the surface of the internal resistance uneven sample with the probe according to the same scan time, record the amplitude of the eddy current waveform; wherein, by presetting at least three sequentially decreasing scan times, selecting one scan time each time in the order of decreasing scan time. The determination module is used to determine the change of the amplitude of the defect-containing sample and the internal resistance uneven sample with the decrease of the scan time, and determine the source of the eddy current anomaly signal according to the amplitude change.

[0053] The specific structure of the eddy current detection device can refer to the explanation of the term "eddy current signal anomaly" above.

[0054] Among them, determining the source of the eddy current anomaly signal according to the amplitude change specifically includes:

[0055] If the amplitude increases with the decrease of the scan time, it is determined that the source of the eddy current anomaly signal is the change of the material electromagnetic properties caused by the internal resistance unevenness;

[0056] If the amplitude does not change with the decrease of the scan time, it is determined that the source of the eddy current anomaly signal is the defect.

[0057] If three sequentially decreasing scan times are preset, the three scan times are T, and

[0058] Preferably, the defective sample is a sample with a smooth surface and a man-made defect in the middle. The internal resistance uneven sample is a blade with abnormal eddy current signal caused by internal resistance uneven.

[0059] The present application aims to distinguish whether the abnormal eddy current signal is caused by the defect of the measured object or the resistance change of the material itself, and to distinguish such abnormal eddy current signal by a more convenient measurement method.

[0060] The various embodiments are described in a progressive manner in the specification, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0061] The principles and implementation manners of the present application are described by using specific examples in the specification. The above description of the embodiments is only used to help understand the method of the present application and its core idea. Meanwhile, for those skilled in the art, the specific implementation manners and application ranges can be changed according to the idea of the present application. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A measurement method for distinguishing an eddy current signal anomaly, characterized by, The method comprises the following steps: presetting at least three scanning times which are sequentially reduced; selecting one scanning time at a time in the order of the scanning times from large to small; after selecting one scanning time at a time, vertically scanning the surface of a defect sample with the probe according to the selected scanning time, recording the amplitude of the eddy current waveform, and vertically scanning the surface of an internal resistance uneven sample with the probe according to the same scanning time, recording the amplitude of the eddy current waveform; determining the change of the amplitude recorded by the defect sample and the internal resistance uneven sample with the reduction of the scanning time respectively, and determining the source of the eddy current abnormal signal according to the change of the amplitude; determining the source of the eddy current abnormal signal according to the change of the amplitude, specifically comprising: if the amplitude increases with the reduction of the scanning time, it is determined that the source of the eddy current abnormal signal is the change of the electromagnetic property of the material caused by the internal resistance unevenness; if the amplitude remains unchanged with the reduction of the scanning time, it is determined that the source of the eddy current abnormal signal is the defect.

2. The method of claim 1, wherein the method is a method of differentiating measurement of an eddy current signal anomaly, characterized by, If three preset scanning times are sequentially reduced, the three scanning times are T, and wherein T is the period of the probe vertically scanning the surface of the sample.

3. The method of claim 1, wherein the method is a method of differentiating an eddy current signal anomaly. The defect sample is a sample with a smooth surface and an artificial defect in the middle; The internal resistance uneven sample is a blade with abnormal eddy current signal caused by internal resistance unevenness.

4. A measurement system that discriminates between eddy current signal anomalies, characterized by, The method comprises the following steps: an eddy current detection device and a determination module; The eddy current detection device is used to vertically scan the surface of a defect sample with the probe according to the selected scanning time after selecting one scanning time at a time, record the amplitude of the eddy current waveform, and vertically scan the surface of an internal resistance uneven sample with the probe according to the same scanning time, record the amplitude of the eddy current waveform; wherein at least three scanning times which are sequentially reduced are preset, and one scanning time is selected at a time in the order of the scanning times from large to small; The determination module is used to determine the change of the amplitude of the defect sample and the internal resistance uneven sample with the reduction of the scanning time, and determine the source of the eddy current abnormal signal according to the change of the amplitude; determining the source of the eddy current abnormal signal according to the change of the amplitude, specifically comprising: if the amplitude increases with the reduction of the scanning time, it is determined that the source of the eddy current abnormal signal is the change of the electromagnetic property of the material caused by the internal resistance unevenness; if the amplitude remains unchanged with the reduction of the scanning time, it is determined that the source of the eddy current abnormal signal is the defect.

5. The measurement system to differentiate electrovortex signal anomalies of claim 4, wherein, If three preset scanning times are sequentially reduced, the three scanning times are T, and wherein T is the period of the probe vertically scanning the surface of the sample.

6. The measurement system to differentiate electrovortex signal anomalies of claim 4, wherein, The defect sample is a sample with a smooth surface and an artificial defect in the middle; The internal resistance uneven sample is a blade with abnormal eddy current signal caused by internal resistance unevenness.

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