A non-magnetic metal classification device and method based on eddy current effect

Abstract

The present invention relates to non-magnetic metal classification technology, specifically a non-magnetic metal classification device and method based on eddy current effect. The present invention solves the problem of low classification accuracy of existing non-magnetic metal classification technology under the influence of the geometric characteristics of non-magnetic metal samples. A non-magnetic metal classification device based on eddy current effect includes a central tube, a double-coil electromagnetic sensor, an analog switch chip, a power amplifier, a signal generator, a signal collector, and a host computer; wherein the central tube is vertically arranged; the double-coil electromagnetic sensor includes an excitation coil and a receiving coil; the excitation coil is fixedly sleeved at the lower end of the outer side surface of the central tube; the receiving coil is fixedly sleeved at the middle and upper part of the outer side surface of the central tube; the excitation coil and the receiving coil together constitute a coil pair; the signal generator is electrically connected to the excitation coil through the power amplifier and the analog switch chip in turn. The present invention is suitable for the classification of non-magnetic metals.

Description

Technical Field

[0001] The invention relates to a non-magnetic metal classification technology, in particular to a non-magnetic metal classification device and method based on eddy current effect. Background Art

[0002] The replacement of old metal products with new ones is inevitable. Due to damage, aging, corrosion, etc., a large amount of scrap metal is generated every year. If these scrap metals are disposed of at will, it will not only waste limited metal resources, but also cause irreversible pollution to the natural environment. Therefore, it is very necessary to recycle scrap metals. Among all the recycled scrap metals, magnetic metals (such as steel, etc.) account for a large proportion, while non-magnetic metals (such as aluminum alloys, copper alloys, etc.) account for a smaller proportion but have a higher recycling value.

[0003] At present, in the process of recycling non-magnetic metals, eddy current sorting is generally used to classify non-magnetic metals. However, in practical applications, the classification results of this method are greatly affected by the geometric characteristics of non-magnetic metal samples, so it has the problem of low classification accuracy. Based on this, it is necessary to invent a non-magnetic metal classification device and method based on eddy current effect to solve the problem of low classification accuracy of existing non-magnetic metal classification technology under the influence of the geometric characteristics of non-magnetic metal samples. Summary of the invention

[0004] In order to solve the problem of low classification accuracy of existing non-magnetic metal classification technology under the influence of geometric characteristics of non-magnetic metal samples, the present invention provides a non-magnetic metal classification device and method based on eddy current effect.

[0005] The present invention is achieved by adopting the following technical solutions:

[0006] A non-magnetic metal classification device based on eddy current effect, comprising a central tube, a double-coil electromagnetic sensor, an analog switch chip, a power amplifier, a signal generator, a signal collector, and a host computer;

[0007] Among them, the central tube is arranged vertically; the double-coil electromagnetic sensor includes an excitation coil and a receiving coil; the excitation coil is fixedly sleeved on the lower end of the outer side surface of the central tube; the receiving coil is fixedly sleeved on the middle and upper part of the outer side surface of the central tube; the excitation coil and the receiving coil together constitute a coil pair; the signal generator is electrically connected to the excitation coil through a power amplifier and an analog switch chip in sequence; the receiving coil is electrically connected to a host computer through an analog switch chip and a signal collector in sequence; and the host computer is electrically connected to the signal generator.

[0008] A non-magnetic metal classification method based on eddy current effect (the method is implemented based on a non-magnetic metal classification device based on eddy current effect described in the present invention), the method is implemented by the following steps:

[0009] Step 1: Measure the impedance Z of the coil pair without sample at an excitation frequency of 400kHz a1 The impedance Z of the coil pair without a sample when the excitation frequency is 40kHz a2 ; The specific measurement steps are as follows:

[0010] Firstly, when there is no non-magnetic metal sample under the dual-coil electromagnetic sensor, the signal generator outputs a sinusoidal excitation signal with a frequency of 400kHz; the sinusoidal excitation signal is first amplified by the power amplifier and then transmitted to the excitation coil through the analog switch chip, thereby inducing a mutual inductance signal in the receiving coil; the mutual inductance signal induced in the receiving coil is transmitted to the host computer through the analog switch chip and the signal collector in turn, and then demodulated by the host computer, thereby obtaining the impedance Z of the coil pair in the absence of a sample when the excitation frequency is 400kHz a1 ;

[0011] Then, the signal generator outputs a sinusoidal excitation signal with a frequency of 40kHz; the sinusoidal excitation signal is first amplified by the power amplifier, and then transmitted to the excitation coil through the analog switch chip, thereby inducing a mutual inductance signal in the receiving coil; the mutual inductance signal induced in the receiving coil is transmitted to the host computer through the analog switch chip and the signal collector in turn, and then demodulated by the host computer, thereby obtaining the impedance Z of the coil pair in the non-sample state when the excitation frequency is 40kHz a2 ;

[0012] Step 2: Measure the impedance Z of the coil pair with samples when the excitation frequency is 400kHz s1 The impedance Z of the coil pair in the sample state when the excitation frequency is 40kHz s2 ; The specific measurement steps are as follows:

[0013] Firstly, the non-magnetic metal sample to be classified is placed under the double-coil electromagnetic sensor; the signal generator outputs a sinusoidal excitation signal with a frequency of 400kHz; the sinusoidal excitation signal is first amplified by a power amplifier, and then transmitted to the excitation coil through an analog switch chip, thereby inducing a mutual inductance signal in the receiving coil; the mutual inductance signal induced in the receiving coil is transmitted to the host computer through the analog switch chip and the signal collector in turn, and then demodulated by the host computer, thereby obtaining the impedance Z of the coil pair in the sample state when the excitation frequency is 400kHz s1 ;

[0014] Then, the signal generator outputs a sinusoidal excitation signal with a frequency of 40kHz; the sinusoidal excitation signal is first amplified by the power amplifier, and then transmitted to the excitation coil through the analog switch chip, thereby inducing a mutual inductance signal in the receiving coil; the mutual inductance signal induced in the receiving coil is transmitted to the host computer through the analog switch chip and the signal collector in turn, and then demodulated by the host computer, thereby obtaining the impedance Z of the coil pair in the sample state when the excitation frequency is 40kHz s2 ;

[0015] Step 3: Based on the impedance Z of the coil pair in the absence of a sample when the excitation frequency is 400kHz a1 The impedance Z of the coil pair in the sample state when the excitation frequency is 400kHz s1 , calculate the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz; the specific calculation formula is as follows:

[0016] ΔZ1=Z s1 -Z a1 ;

[0017] Step 4: First, calculate the amplitude A of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz; then, calculate the diameter d of the non-magnetic metal sample based on the amplitude A of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz; the specific calculation formula is as follows:

[0018]

[0019]

[0020] Where: Im(ΔZ1) represents the imaginary part of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz; Re(ΔZ1) represents the real part of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz;

[0021] Step 5: Substitute the diameter d of the non-magnetic metal sample into the first characteristic formula, the second characteristic formula, the third characteristic formula, and the fourth characteristic formula, thereby calculating the first phase angle θ1, the second phase angle θ2, the third phase angle θ3, and the fourth phase angle θ4 respectively;

[0022] The first characteristic formula is:

[0023] The second characteristic formula is:

[0024] The third characteristic formula is:

[0025] The fourth characteristic formula is:

[0026] Step 6: Based on the impedance Z of the coil pair in the absence of a sample when the excitation frequency is 40kHz a2 The impedance Z of the coil pair in the sample state when the excitation frequency is 40kHz s2 , calculate the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz; the specific calculation formula is as follows:

[0027] ΔZ2=Z s2 -Z a2 ;

[0028] Step 7: Calculate the phase angle θ of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz; the specific calculation formula is as follows:

[0029]

[0030] Where: Im(ΔZ2) represents the imaginary part of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz; Re(ΔZ2) represents the real part of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz;

[0031] Step 8: According to the phase angle θ, the first phase angle θ1, the second phase angle θ2, the third phase angle θ3, and the fourth phase angle θ4 of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz, the first difference Δθ1, the second difference Δθ2, the third difference Δθ3, and the fourth difference Δθ4 are calculated respectively; the specific calculation formula is as follows:

[0032] Δθ1=|θ-θ1|;

[0033] Δθ2=|θ-θ2|;

[0034] Δθ3=|θ-θ3|;

[0035] Δθ4=|θ-θ4|;

[0036] Step 9: First, determine the minimum difference from the first difference Δθ1, the second difference Δθ2, the third difference Δθ3, and the fourth difference Δθ4; then, determine the material of the non-magnetic metal sample according to the minimum difference, thereby classifying the non-magnetic metal sample; the specific determination rules are as follows:

[0037] When the first difference Δθ1 is the minimum difference, the material of the non-magnetic metal sample is determined to be 1065 aluminum alloy;

[0038] When the second difference Δθ2 is the minimum difference, the material of the non-magnetic metal sample is determined to be 6061 aluminum alloy;

[0039] When the third difference Δθ3 is the minimum difference, the material of the non-magnetic metal sample is determined to be a brass alloy;

[0040] When the fourth difference Δθ4 is the minimum difference, the material of the non-magnetic metal sample is determined to be a copper alloy.

[0041] In the steps 1 and 2, the amplitude and phase of the sinusoidal excitation signal can be adjusted by the host computer.

[0042] Compared with the existing non-magnetic metal classification technology, the non-magnetic metal classification device and method based on eddy current effect described in the present invention, on the one hand, uses the phase angle of the impedance change of the dual-coil electromagnetic sensor as the classification basis, and on the other hand, utilizes the skin characteristics of eddy current under high-frequency excitation to decouple the structural frequency response of the dual-coil electromagnetic sensor from the geometric characteristics of the non-magnetic metal sample, thereby effectively eliminating the influence of the geometric characteristics of the non-magnetic metal sample on the classification result, thereby greatly improving the classification accuracy.

[0043] The invention effectively solves the problem of low classification accuracy of existing non-magnetic metal classification technology under the influence of the geometric characteristics of non-magnetic metal samples, and is suitable for the classification of non-magnetic metals. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a partial structural schematic diagram of the device described in the present invention.

[0045] Figure 2 It is another partial structural schematic diagram of the device of the present invention.

[0046] Figure 3 It is a schematic diagram of the process of the method of the present invention.

[0047] In the figure: 1-central tube, 201-excitation coil, 202-receiving coil, 3-analog switch chip, 4-power amplifier, 5-signal generator, 6-signal collector, 7-host computer, 8-non-magnetic metal sample. DETAILED DESCRIPTION

[0048] A non-magnetic metal classification device based on eddy current effect, comprising a central tube 1, a double-coil electromagnetic sensor, an analog switch chip 3, a power amplifier 4, a signal generator 5, a signal collector 6, and a host computer 7;

[0049] Among them, the central tube 1 is arranged vertically; the double-coil electromagnetic sensor includes an excitation coil 201 and a receiving coil 202; the excitation coil 201 is fixedly sleeved on the lower end of the outer side surface of the central tube 1; the receiving coil 202 is fixedly sleeved on the middle and upper part of the outer side surface of the central tube 1; the excitation coil 201 and the receiving coil 202 together constitute a coil pair; the signal generator 5 is electrically connected to the excitation coil 201 through the power amplifier 4 and the analog switch chip 3 in sequence; the receiving coil 202 is electrically connected to the host computer 7 through the analog switch chip 3 and the signal collector 6 in sequence; the host computer 7 is electrically connected to the signal generator 5.

[0050] A non-magnetic metal classification method based on eddy current effect (the method is implemented based on a non-magnetic metal classification device based on eddy current effect described in the present invention), the method is implemented by the following steps:

[0051] Step 1: Measure the impedance Z of the coil pair without sample at an excitation frequency of 400kHz a1 The impedance Z of the coil pair without a sample when the excitation frequency is 40kHz a2 ; The specific measurement steps are as follows:

[0052] First, in the case where there is no non-magnetic metal sample 8 under the dual-coil electromagnetic sensor, the signal generator 5 outputs a sinusoidal excitation signal with a frequency of 400kHz; the sinusoidal excitation signal is first amplified by the power amplifier 4, and then transmitted to the excitation coil 201 through the analog switch chip 3, thereby inducing a mutual inductance signal in the receiving coil 202; the mutual inductance signal induced in the receiving coil 202 is successively transmitted to the host computer 7 through the analog switch chip 3 and the signal collector 6, and then demodulated by the host computer 7, thereby obtaining the impedance Z of the coil pair in the sample-free state when the excitation frequency is 400kHz a1 ;

[0053] Then, the signal generator 5 outputs a sinusoidal excitation signal with a frequency of 40kHz; the sinusoidal excitation signal is first amplified by the power amplifier 4, and then transmitted to the excitation coil 201 through the analog switch chip 3, thereby inducing a mutual inductance signal in the receiving coil 202; the mutual inductance signal induced in the receiving coil 202 is successively transmitted to the host computer 7 through the analog switch chip 3 and the signal collector 6, and then demodulated by the host computer 7, thereby obtaining the impedance Z of the coil pair in the non-sample state when the excitation frequency is 40kHz a2 ;

[0054] Step 2: Measure the impedance Z of the coil pair with samples when the excitation frequency is 400kHz s1 The impedance Z of the coil pair in the sample state when the excitation frequency is 40kHz s2 ; The specific measurement steps are as follows:

[0055] First, a non-magnetic metal sample 8 to be classified is placed under the double-coil electromagnetic sensor; the signal generator 5 outputs a sinusoidal excitation signal with a frequency of 400kHz; the sinusoidal excitation signal is first amplified by the power amplifier 4, and then transmitted to the excitation coil 201 through the analog switch chip 3, thereby inducing a mutual inductance signal in the receiving coil 202; the mutual inductance signal induced in the receiving coil 202 is transmitted to the host computer 7 through the analog switch chip 3 and the signal collector 6 in turn, and then demodulated by the host computer 7, thereby obtaining the impedance Z of the coil pair in the sample state when the excitation frequency is 400kHz s1 ;

[0056] Then, the signal generator 5 outputs a sinusoidal excitation signal with a frequency of 40kHz; the sinusoidal excitation signal is first amplified by the power amplifier 4, and then transmitted to the excitation coil 201 through the analog switch chip 3, thereby inducing a mutual inductance signal in the receiving coil 202; the mutual inductance signal induced in the receiving coil 202 is successively transmitted to the host computer 7 through the analog switch chip 3 and the signal collector 6, and then demodulated by the host computer 7, thereby obtaining the impedance Z of the coil pair in the sample state when the excitation frequency is 40kHz s2 ;

[0057] Step 3: Based on the impedance Z of the coil pair in the absence of a sample when the excitation frequency is 400kHz a1 The impedance Z of the coil pair in the sample state when the excitation frequency is 400kHz s1 , calculate the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz; the specific calculation formula is as follows:

[0058] ΔZ1=Z s1 -Z a1 ;

[0059] Step 4: First, calculate the amplitude A of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz; then, calculate the diameter d of the non-magnetic metal sample 8 according to the amplitude A of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz; the specific calculation formula is as follows:

[0060]

[0061]

[0062] Where: Im(ΔZ1) represents the imaginary part of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz; Re(ΔZ1) represents the real part of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz;

[0063] Step 5: Substitute the diameter d of the non-magnetic metal sample 8 into the first characteristic formula, the second characteristic formula, the third characteristic formula, and the fourth characteristic formula, thereby respectively calculating the first phase angle θ1, the second phase angle θ2, the third phase angle θ3, and the fourth phase angle θ4;

[0064] The first characteristic formula is:

[0065] The second characteristic formula is:

[0066] The third characteristic formula is:

[0067] The fourth characteristic formula is:

[0068] Step 6: Based on the impedance Z of the coil pair in the absence of a sample when the excitation frequency is 40kHz a2 The impedance Z of the coil pair in the sample state when the excitation frequency is 40kHz s2 , calculate the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz; the specific calculation formula is as follows:

[0069] ΔZ2=Z s2 -Z a2 ;

[0070] Step 7: Calculate the phase angle θ of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz; the specific calculation formula is as follows:

[0071]

[0072] Where: Im(ΔZ2) represents the imaginary part of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz; Re(ΔZ2) represents the real part of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz;

[0073] Step 8: According to the phase angle θ, the first phase angle θ1, the second phase angle θ2, the third phase angle θ3, and the fourth phase angle θ4 of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz, the first difference Δθ1, the second difference Δθ2, the third difference Δθ3, and the fourth difference Δθ4 are calculated respectively; the specific calculation formula is as follows:

[0074] Δθ1=|θ-θ1|;

[0075] Δθ2=|θ-θ2|;

[0076] Δθ3=|θ-θ3|;

[0077] Δθ4=|θ-θ4|;

[0078] Step 9: First, determine the minimum difference from the first difference Δθ1, the second difference Δθ2, the third difference Δθ3, and the fourth difference Δθ4; then, determine the material of the non-magnetic metal sample 8 according to the minimum difference, thereby classifying the non-magnetic metal sample 8; the specific determination rules are as follows:

[0079] When the first difference Δθ1 is the minimum difference, the material of the non-magnetic metal sample 8 is determined to be 1065 aluminum alloy;

[0080] When the second difference Δθ2 is the minimum difference, the material of the non-magnetic metal sample 8 is determined to be 6061 aluminum alloy;

[0081] When the third difference Δθ3 is the minimum difference, the material of the non-magnetic metal sample 8 is determined to be a brass alloy;

[0082] When the fourth difference Δθ4 is the minimum difference, the material of the non-magnetic metal sample 8 is determined to be a copper alloy.

[0083] In the steps 1 and 2, the amplitude and phase of the sinusoidal excitation signal can be adjusted by the host computer 7 .

[0084] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A non-magnetic metal classification method based on eddy current effect, characterized in that: The method is implemented based on a non-magnetic metal classification device based on eddy current effect, the device comprising a central tube (1), a double-coil electromagnetic sensor, an analog switch chip (3), a power amplifier (4), a signal generator (5), a signal collector (6), and a host computer (7); The central tube (1) is arranged vertically; the double-coil electromagnetic sensor comprises an excitation coil (201) and a receiving coil (202); the excitation coil (201) is fixedly sleeved on the lower end of the outer side surface of the central tube (1); the receiving coil (202) is fixedly sleeved on the middle and upper part of the outer side surface of the central tube (1); the excitation coil (201) and the receiving coil (202) together constitute a coil pair; the signal generator (5) is electrically connected to the excitation coil (201) in sequence through a power amplifier (4) and an analog switch chip (3); the receiving coil (202) is electrically connected to a host computer (7) in sequence through an analog switch chip (3) and a signal collector (6); and the host computer (7) is electrically connected to the signal generator (5); This method is implemented by the following steps: Step 1: Measure the impedance Z of the coil pair without sample at an excitation frequency of 400kHz a1 The impedance Z of the coil pair without a sample when the excitation frequency is 40kHz a2 ; The specific measurement steps are as follows: First, in the absence of a non-magnetic metal sample (8) below the dual-coil electromagnetic sensor, the signal generator (5) outputs a sinusoidal excitation signal with a frequency of 400 kHz; the sinusoidal excitation signal is first amplified by a power amplifier (4), and then transmitted to the excitation coil (201) via an analog switch chip (3), thereby inducing a mutual inductance signal in the receiving coil (202); the mutual inductance signal induced in the receiving coil (202) is sequentially transmitted to a host computer (7) via the analog switch chip (3) and a signal collector (6), and then demodulated by the host computer (7), thereby obtaining an impedance Z of the coil pair in a state without a sample when the excitation frequency is 400 kHz. a1 ; Then, the signal generator (5) outputs a sinusoidal excitation signal with a frequency of 40 kHz; the sinusoidal excitation signal is first amplified by the power amplifier (4), and then transmitted to the excitation coil (201) via the analog switch chip (3), thereby inducing a mutual inductance signal in the receiving coil (202); the mutual inductance signal induced in the receiving coil (202) is sequentially transmitted to the host computer (7) via the analog switch chip (3) and the signal collector (6), and then demodulated by the host computer (7), thereby obtaining the impedance Z of the coil pair in a sample-free state when the excitation frequency is 40 kHz a2 ; Step 2: Measure the impedance Z of the coil pair with samples when the excitation frequency is 400kHz s1 The impedance Z of the coil pair in the sample state when the excitation frequency is 40kHz s2 ; The specific measurement steps are as follows: First, a non-magnetic metal sample (8) to be classified is placed under a double-coil electromagnetic sensor; a signal generator (5) outputs a sinusoidal excitation signal with a frequency of 400 kHz; the sinusoidal excitation signal is first amplified by a power amplifier (4), and then transmitted to the excitation coil (201) via an analog switch chip (3), thereby inducing a mutual inductance signal in the receiving coil (202); the mutual inductance signal induced in the receiving coil (202) is sequentially transmitted to a host computer (7) via the analog switch chip (3) and a signal collector (6), and then demodulated by the host computer (7), thereby obtaining an impedance Z of the coil pair in a sample state when the excitation frequency is 400 kHz. s1 ; Then, the signal generator (5) outputs a sinusoidal excitation signal with a frequency of 40 kHz; the sinusoidal excitation signal is first amplified by the power amplifier (4), and then transmitted to the excitation coil (201) via the analog switch chip (3), thereby inducing a mutual inductance signal in the receiving coil (202); the mutual inductance signal induced in the receiving coil (202) is transmitted to the host computer (7) in sequence via the analog switch chip (3) and the signal collector (6), and then demodulated by the host computer (7), thereby obtaining the impedance Z of the coil pair in the sample state when the excitation frequency is 40 kHz s2 ; Step 3: Based on the impedance Z of the coil pair in the absence of a sample when the excitation frequency is 400kHz a1 The impedance Z of the coil pair in the sample state when the excitation frequency is 400kHz s1 , calculate the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz; the specific calculation formula is as follows: ΔZ1=Z s1 -Z a1 ; Step 4: First, calculate the amplitude A of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400 kHz; then, calculate the diameter d of the non-magnetic metal sample (8) based on the amplitude A of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400 kHz; the specific calculation formula is as follows: Where: Im(ΔZ1) represents the imaginary part of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz; Re(ΔZ1) represents the real part of the impedance change ΔZ1 of the coil pair when the excitation frequency is 400kHz; Step 5: Substitute the diameter d of the non-magnetic metal sample (8) into the first characteristic formula, the second characteristic formula, the third characteristic formula, and the fourth characteristic formula, thereby respectively calculating the first phase angle θ1, the second phase angle θ2, the third phase angle θ3, and the fourth phase angle θ4; The first characteristic formula is: The second characteristic formula is: The third characteristic formula is: The fourth characteristic formula is: Step 6: Based on the impedance Z of the coil pair in the absence of a sample when the excitation frequency is 40kHz a2 The impedance Z of the coil pair in the sample state when the excitation frequency is 40kHz s2 , calculate the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz; the specific calculation formula is as follows: ΔZ2=Z s2 -WITH a2 ; Step 7: Calculate the phase angle θ of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz; the specific calculation formula is as follows: Where: Im(ΔZ2) represents the imaginary part of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz; Re(ΔZ2) represents the real part of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz; Step 8: According to the phase angle θ, the first phase angle θ1, the second phase angle θ2, the third phase angle θ3, and the fourth phase angle θ4 of the impedance change ΔZ2 of the coil pair when the excitation frequency is 40kHz, the first difference Δθ1, the second difference Δθ2, the third difference Δθ3, and the fourth difference Δθ4 are calculated respectively; the specific calculation formula is as follows: Δθ1=|θ-θ1|; Δθ2=|θ-θ2|; Δθ3=|θ-θ3|; Δθ4=|θ-θ4|; Step 9: First, determine the minimum difference from the first difference Δθ1, the second difference Δθ2, the third difference Δθ3, and the fourth difference Δθ4; then, determine the material of the non-magnetic metal sample (8) according to the minimum difference, thereby classifying the non-magnetic metal sample (8); the specific determination rules are as follows: When the first difference Δθ1 is the minimum difference, the material of the non-magnetic metal sample (8) is determined to be 1065 aluminum alloy; When the second difference Δθ2 is the minimum difference, the material of the non-magnetic metal sample (8) is determined to be 6061 aluminum alloy; When the third difference Δθ3 is the minimum difference, the material of the non-magnetic metal sample (8) is determined to be a brass alloy; When the fourth difference Δθ4 is the minimum difference, the material of the non-magnetic metal sample (8) is determined to be a copper alloy.

2. The non-magnetic metal classification method based on eddy current effect according to claim 1, characterized in that: In the steps 1 and 2, the amplitude and phase of the sinusoidal excitation signal can be adjusted by the host computer (7).

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