Device and method for measuring metal conductivity of torsion balance

Abstract

The invention belongs to the technical field of metal characteristic measurement, and provides a metal conductivity measuring device and method for a torsion balance, and the device comprises a magnetic field generation device, a torsion balance structure, an angle deflection detection device and a terminal, and the magnetic field generation device comprises two uniform magnetic field coils and two gradient magnetic field coils which are horizontally arranged. The torsion balance structure comprises an insulated balance rod, a torsion wire and a supporting frame, one end of the torsion wire is fixedly connected with the supporting frame, the other end of the torsion wire is rotationally connected with the center position of the balance rod, one end of the balance rod is connected with the balancing block, the other end of the balance rod is connected with a sample, and the sample is located between the two uniform magnetic field coils and the two gradient magnetic field coils. The angle deflection detection device is located in the center of the balance rod. The terminal is in communication connection with the angle deflection detection device. The method has no requirement on the surface property of the metal sample, and the conductivity of the sample can be calculated only through the rotation angle of the balance rod.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal property measurement, and provides a torsion balance type metal conductivity measuring device and method. BACKGROUND

[0002] The accurate measurement of metal conductivity is irreplaceable in the fields of material science, industrial manufacturing and quality control. As a core parameter representing the conductivity of materials, conductivity is directly related to key performance indicators such as purity, organizational structure, heat treatment state, etc. of metals. For example, in the field of aerospace, conductivity measurement is used to evaluate the discharge capacity of aluminum alloys to ensure their reliability in withstanding lightning strikes; in the power system, copper bar conductivity detection is a key link to ensure the efficiency of power transmission; and in the electronics industry, the conductivity monitoring of high-purity copper materials is a fundamental guarantee for the performance of printed circuit boards (PCB). Therefore, conductivity measurement is not only a necessary means for material research and development, but also a core technology for realizing quality traceability and process optimization in industrial production.

[0003] The metal conductivity measuring device adopts a contact type measuring device based on Ohm's law and a non-contact device based on electromagnetic induction. However, the contact type measuring device based on Ohm's law requires that the contact surface of the metal sample to be measured must be smooth, without concave-convex, and without contamination. The measurement result depends on the surface properties of the sample. The non-contact device based on electromagnetic induction generates an electromotive force through an external excitation alternating magnetic field, and then generates eddy currents, which in turn generate a measured alternating magnetic field. The higher the conductivity of the metal and the higher the excitation magnetic field frequency, the greater the effect of the measured alternating magnetic field. In order to ensure the accuracy of conductivity measurement, the excitation magnetic field frequency needs to reach a certain limit, and the required excitation magnetic field frequency is above 100 Hz. Under this high-frequency excitation condition, due to the skin effect, eddy currents are mainly concentrated on the surface of the sample. Surface scratches, contamination, oxidation and other surface factors can cause measurement deviation.

[0004] It can be seen that the above two devices have very high requirements for the smoothness of the surface of the metal sample to be measured, resulting in that the accuracy of conductivity measurement depends on the surface properties of the metal sample. In actual applications, the ideal surface properties required by the two methods are difficult to meet. SUMMARY

[0005] To solve the above technical problems, the application provides a torsion balance type metal conductivity measuring device and method, which does not require the surface properties of the metal sample, and the conductivity of the sample can be calculated by the rotation angle of the balance bar caused by the electromagnetic force acting on the sample.

[0006] The technical scheme of the application comprises: The magnetic field generating device comprises two horizontal uniform magnetic field coils and two gradient magnetic field coils, the two uniform magnetic field coils are used for providing a uniform magnetic field, the two gradient magnetic field coils are used for providing a uniform gradient magnetic field, and the magnetic field directions of the uniform magnetic field and the uniform gradient magnetic field are both horizontal directions.

[0007] The torsion balance structure comprises an insulating balance bar, a torsion wire and a support frame, one end of the torsion wire is fixedly connected with the support frame, the other end is rotationally connected with the center position of the balance bar, one end of the balance bar is connected with a counterbalance block, and the other end is connected with a sample, and the sample is located between the two uniform magnetic field coils and between the two gradient magnetic field coils.

[0008] The angle deflection detection device is located at the center position of the balance bar and is used for detecting the rotation angle θ of the balance bar.

[0009] The terminal is in communication connection with the angle deflection detection device, and the terminal calculates the electrical conductivity of the sample according to the rotation angle of the balance bar and the arm length of the balance bar.

[0010] Further, the uniform magnetic field coil is a Helmholtz coil, the wire diameter of the uniform magnetic field coil is between 1.5 mm and 2.5 mm, the number of turns is between 450 turns and 500 turns, and the outer diameter is between 1.6 times and 2 times the length of the sample; the gradient magnetic field coil is a Maxwell coil, the wire diameter of the gradient magnetic field coil is between 1.5 mm and 2.5 mm, the number of turns is between 240 turns and 280 turns, and the outer diameter is between 2 times and 2.5 times the length of the sample.

[0011] Further, the distance between the two uniform magnetic field coils is equal to the outer diameter of the uniform magnetic field coil; the distance between the two gradient magnetic field coils is equal to the outer diameter of the gradient magnetic field coil × .

[0012] Further, the angle deflection detection device comprises a mirror and a light reading component, the mirror is fixed at the center position of the balance bar and is arranged in parallel with the balance bar, the light reading component is located at one side of the mirror and is used for emitting light to the mirror and reading the change of the light path of the light, so that the voltage output of the light reading component changes, and then the rotation angle θ of the balance bar is measured.

[0013] Further, the formula for calculating the electrical conductivity is: Wherein, σ is the electrical conductivity of the sample, is a torsion balance parameter function, B A is the uniform magnetic field strength, is the uniform gradient field strength, is the frequency of the uniform magnetic field, is the frequency of the gradient uniform magnetic field, and L is the arm length of the balance bar. The test magnetic field configuration and sample related constant function, and V is the volume of the sample.

[0014] Further, the rotation angle of the balance bar measured by the light reading is removed from noise by the least square method.

[0015] Further, the magnetic field directions of the uniform magnetic field and the uniform gradient magnetic field are the same.

[0016] The application also provides a metal conductivity measuring method of the torsion balance, comprising the following steps: The uniform magnetic field coil and the gradient magnetic field coil are powered, the uniform magnetic field coil generates a uniform magnetic field with a frequency of , and the gradient magnetic field coil generates a uniform gradient magnetic field with a frequency of .

[0017] The sample generates eddy current under the action of the uniform magnetic field, and the eddy current makes the sample receive electromagnetic force under the action of the uniform gradient magnetic field, so that the balance bar is deflected.

[0018] The rotation angle of the balance bar is detected by the angle deflection detection device.

[0019] Finally, the conductivity of the sample is calculated by the intensity B A of the uniform magnetic field, the intensity of the uniform gradient field, the frequency of the uniform magnetic field coil, the frequency of the uniform gradient magnetic field, the rotation angle of the balance bar and the arm length L of the balance bar, and the formula is: Wherein, sigma is the conductivity of the sample, is the torsion balance parameter function, B A is the intensity of the uniform magnetic field, is the intensity of the uniform gradient field, is the frequency of the uniform magnetic field, is the frequency of the gradient uniform magnetic field, L is the arm length of the balance bar, is the test magnetic field configuration and sample related constant function, and V is the volume of the sample.

[0020] Compared with the prior art, the technical scheme provided by the application has the following advantages: The uniform magnetic field coil and the gradient magnetic field coil are powered, the uniform magnetic field coil generates a uniform magnetic field with a frequency of , and the gradient magnetic field coil generates a uniform gradient magnetic field with a frequency of uniform magnetic field; the sample generates vortex current under the action of the uniform magnetic field, the vortex current makes the sample suffer electromagnetic force under the action of the uniform gradient magnetic field, so that the balance rod is deflected; the rotation angle of the balance rod is detected by the angle deflection detection device; finally the conductivity of the sample is calculated by the frequency of the uniform magnetic field coil , the frequency of the uniform gradient magnetic field , the rotation angle of the balance rod and the arm length of the balance rod Compared with the prior art, the present application does not require the surface properties of the metal sample, and the rotation angle of the balance rod caused by the electromagnetic force suffered by the sample can be used to calculate the conductivity of the sample.

[0021] Other advantages, objects and features of the present application will be apparent from the following description, and will be understood by those skilled in the art through a consideration of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0023] Figure 1 The structure of the metal conductivity measuring device of the embodiment of the present application is shown in the figure.

[0024] Figure 2 The working principle diagram of the metal conductivity measuring device of the embodiment of the present application is shown in the figure.

[0025] Figure 3 The measurement result diagram of copper and aluminum materials of the embodiment of the present application is shown in the figure.

[0026] Reference signs: 1, uniform magnetic field coil; 2, gradient magnetic field coil; 3, sample; 4, balance rod; 5, mirror; 6, balancing block; 7, suspension point; 8, optical reading component; 9, torsion wire; 10, support frame. DETAILED DESCRIPTION

[0027] A specific embodiment of the present application will be described in detail below with reference to the drawings, but it should be understood that the protection scope of the present application is not limited by the specific embodiment.

[0028] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the technical solutions of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0029] In the description of the embodiments of the present application, "a plurality of" means two or more, unless otherwise specified.

[0030] As shown in Figure 1 and Figure 2 The present application provides a torsion balance metal conductivity measuring device and method, comprising: A magnetic field generating device, comprising two horizontal uniform magnetic field coils 1 and two gradient magnetic field coils 2, the two uniform magnetic field coils 1 are used to provide a uniform magnetic field, the two gradient magnetic field coils 2 are used to provide a uniform gradient magnetic field, and the magnetic field directions of the uniform magnetic field and the uniform gradient magnetic field are both horizontal directions.

[0031] A torsion balance structure, comprising an insulating balance rod 4, a torsion wire 9 and a support frame 10, one end of the torsion wire 9 is fixedly connected with the support frame 10, the other end is rotationally connected with a suspension point 7 at the center position of the balance rod 4, one end of the balance rod 4 is connected with a balancing block 6, the other end is connected with a sample 3, and the sample 3 is located between the two uniform magnetic field coils 1 and the two gradient magnetic field coils 2.

[0032] An angle deflection detection device, located at the center position of the balance rod 4, used to detect the rotation angle θ of the balance rod 4.

[0033] A terminal, in communication connection with the angle deflection detection device, the terminal calculates the conductivity of the sample 3 according to the rotation angle of the balance rod 4 and the arm length of the balance rod 4.

[0034] In the device, the sample 3 is located in the double magnetic field overlapping area, which can stably drive the balance rod 4 to deflect under the electromagnetic force; the insulating balance rod 4 can avoid self-interference magnetic field or eddy current, and the balancing block 6 guarantees the initial balance of the torsion balance, providing a stable foundation for subsequent angle detection. The terminal calculates the conductivity by the deflection angle and the arm length, realizing the direct conversion from physical quantity to parameter, meeting the precise measurement demand of non-ideal sample 3 on the surface in the fields of aerospace, power system and the like.

[0035] In the embodiments provided by the present application, the uniform magnetic field coil (1) is a Helmholtz coil, the wire diameter of the uniform magnetic field coil (1) is between 1.5 mm and 2.5 mm, the number of turns is between 450 turns and 500 turns, and the outer diameter is between 1.6 times and 2 times the length of the sample (3); the gradient magnetic field coil (2) is a Maxwell coil, the wire diameter of the gradient magnetic field coil (2) is between 1.5 mm and 2.5 mm, the number of turns is between 240 turns and 280 turns, and the outer diameter is between 2 times and 2.5 times the length of the sample (3).

[0036] For example, the maximum length of the sample is 9.5 cm, the number of turns of the selected uniform magnetic field coil (1) is 480 turns, and the outer diameter is 15 cm, which is obtained by winding turns of copper enameled wire with a diameter of 2 mm. The selected gradient magnetic field coil (2) has 260 turns, and the outer diameter is 30 cm, which is obtained by winding turns of copper enameled wire with a diameter of 2 mm.

[0037] Advantages: Advantage 1: The uniform magnetic field coil (1) can generate a uniform magnetic field at the sample, and the gradient magnetic field coil (2) can generate a uniform gradient magnetic field at the sample. In this configuration, the sample is always in a uniform magnetic field and a uniform gradient field (uniformity of 95% or more) during testing, reducing the positioning accuracy requirements of the sample during testing, i.e., the function G(.) in the measurement formula is independent of the position. This makes testing simple. Advantage 2: It can generate a uniform magnetic field and a uniform magnetic field gradient that is strong enough to achieve sufficient accuracy in testing. Note that the number of turns and the outer diameter are not specific. If the sample size increases, the outer diameter of the uniform magnetic field coil (1) and the gradient magnetic field coil (2) also increases accordingly, and the number of turns also increases. Specifically:

[0038] Ensure magnetic field stability and strength: The wire diameter is limited to 1.5-2.5 mm, and the number of turns is controlled at 450-500 turns (uniform magnetic field coil) and 240-280 turns (gradient magnetic field coil), respectively. This can avoid excessive heating and instability of the magnetic field caused by too thin wires, and also avoid redundancy of the device caused by too thick wires or too many turns, so that a stable magnetic field that meets the measurement requirements can be generated.

[0039] Maximize magnetic field uniformity: The Helmholtz coil is a standard structure for generating a uniform magnetic field, and the Maxwell coil is a standard structure for generating a uniform gradient magnetic field. Combined with the setting of "the outer diameter is proportional to the sample length" (1.6-2 times for the uniform magnetic field coil and 2-2.5 times for the gradient magnetic field coil), the sample can be completely in the uniform magnetic field area, reducing the force deviation of the sample caused by non-uniform magnetic field, and providing a stable magnetic field basis for subsequent angle detection and conductivity calculation.

[0040] Improve sample adaptability: The parameter design of the outer diameter in relation to the sample length allows the coil size to be adjusted according to different sizes of the sample, avoiding the problem of incomplete magnetic field coverage caused by mismatch between the coil size and the sample, and expanding the application range of the device.

[0041] In the embodiments provided by the present application, the interval of the two uniform magnetic field coils (1) is equal to the outer diameter of the uniform magnetic field coil (1); the interval of the two gradient magnetic field coils (2) is equal to the outer diameter of the gradient magnetic field coil (2) x .

[0042] For example, the interval of the uniform magnetic field coil (1) is 15 cm, and the interval of the gradient magnetic field coil (2) is 52 cm, which is related to the sample size. The larger the sample size, the larger the interval must be. This is because, in order to keep the sample in the uniform zone during the test, the size of the coil outer diameter needs to be proportional to the sample size.

[0043] The interval of the uniform magnetic field coil is equal to the outer diameter, which is the classic configuration of the Helmholtz coil to generate a "highest uniformity magnetic field", which can make the magnetic field uniformity of the coil center area (sample placement area) reach more than 95%, avoid the influence of the difference of the magnetic field intensity on different parts of the sample, and ensure the consistency of the vortex current.

[0044] The interval of the gradient magnetic field coil is equal to the outer diameter x is the optimal parameter of the Maxwell coil to generate a "highest uniformity gradient magnetic field", which can make the gradient magnetic field distribution of the sample area stable, avoid the force fluctuation of the sample caused by the gradient, and ensure the authenticity of the deflection angle of the balance rod.

[0045] Because the uniform magnetic field area is fully covered, there is no need to accurately adjust the position of the sample in the magnetic field to meet the measurement requirements, which simplifies the operation process and reduces the influence of human positioning error on the measurement results.

[0046] In the embodiments provided by the present application, the magnetic field intensity of the uniform magnetic field coil (1) is between 100 μT and 500 μT, and the frequency is between 0.01 Hz and 10 Hz; the magnetic field intensity of the gradient magnetic field coil (2) is between 200 μT / m and 1000 μT / m, and the frequency is between 0.01 Hz and 10 Hz. The skin effect can be avoided, and the measurement accuracy and practicability can be balanced, as follows:

[0047] Avoid the influence of the skin effect: the frequency is limited to 0.01-10 Hz (much lower than 100 Hz or more in the prior art), which can make the vortex current distribute inside the sample instead of only concentrating on the surface, completely solving the problem of "surface scratches, oxidation, and pollution leading to measurement deviation" in the prior art, and meeting the core advantage of the application "no requirement for the sample surface".

[0048] Balancing magnetic field strength and practicality: the magnetic field strength range (uniform 100-500 μT, gradient 200-1000 μT / m) can produce strong enough electromagnetic force to drive the balance rod to produce a detectable deflection angle (to avoid detection errors caused by too small angle), and will not cause high device energy consumption and additional magnetic interference to the sample due to too strong magnetic field, and both measurement accuracy and actual use cost are considered.

[0049] Ensure signal stability: the narrow frequency range and low frequency setting can reduce the influence of external high-frequency electromagnetic interference on the magnetic field signal, stabilize the magnetic field frequency (fa, fb), and ensure the clarity of the electromagnetic force signal under the beat frequency (fa-fb), reduce the difficulty of subsequent angle denoising, and improve the accuracy of conductivity calculation.

[0050] In the embodiments provided by the present application, the angle deflection detection device includes a mirror 5 and a light reading component 8, the mirror 5 is fixed at the center position of the balance rod 4 and is arranged in parallel with the balance rod 4, and the light reading component 8 is located on one side of the mirror 5 and is used to emit light to the mirror 5 and read the change of the light path, so that the voltage change of the output of the light reading component 8 is changed, and then the rotation angle θ of the balance rod 4 is measured. How to use the light reading component 8 to measure the torsion balance deflection angle θ has been relatively mature, and this application will not be described.

[0051] The mirror 5 and the balance rod 4 are deflected synchronously, the light path change can directly reflect the small deflection amount, and compared with other detection methods, the torsion balance fine rotation is easier to capture; the light reading component 8 converts the light path change into voltage change, the signal conversion is intuitive and easy to quantify, and the possible error of mechanical detection is avoided. The accurate rotation angle θ provides reliable data support for the terminal conductivity calculation, reduces the conductivity calculation deviation caused by inaccurate angle detection, and guarantees the overall measurement accuracy.

[0052] In the embodiments provided by the present application, the formula for calculating the conductivity is: Wherein, σ is the sample conductivity, is the torsion balance parameter function, B A is the uniform magnetic field strength, is the uniform gradient field strength, is the frequency of the uniform magnetic field, is the frequency of the gradient uniform magnetic field, L is the balance rod arm length, is the test magnetic field configuration, sample related constant function, V is the volume of the sample.

[0053] The parameters in the formula are all quantities that can be directly obtained or determined in advance by the device (such as fa / fb is the coil setting value, θ is the detection value, and L is the fixed arm length), which avoids subjective estimation error; through the function and The formula is suitable for torsion balance and sample of different specifications and has strong versatility. Meanwhile, the formula establishes a clear logical relationship between the electromagnetic force, the deflection angle and the conductivity, so that the calculation result is traceable and verifiable, and the measurement reliability is improved.

[0054] In the embodiments provided in the application, the rotation angle θ of the balance lever measured by light reading is removed from noise by the least square method. The least square method can effectively separate the deflection signal at the "fa-fb frequency" in θ from irrelevant noise, and accurately extract the real deflection angle reflecting the force of the sample. After removing the noise, the θ value substituted into the conductivity formula is more accurate, avoiding the calculation deviation caused by noise, especially in the industrial complex environment, the stability of the θ data of multiple measurements can be ensured, and the repeatability and accuracy of the conductivity measurement are improved, so that the result is more consistent with the real conductivity of the sample.

[0055] In the embodiments provided in the application, the magnetic field directions of the uniform magnetic field and the uniform gradient magnetic field are the same. The same magnetic field direction can make the eddy current generated by the sample 3 in the uniform magnetic field have a clear force direction and stable size in the gradient magnetic field, and will not cause the force to be offset or disordered due to the opposite magnetic field directions. Stable force can make the deflection direction of the balance lever 4 fixed and the angle size predictable, which is convenient for the angle detection device to accurately capture; at the same time, the deflection angle is avoided to be too small or fluctuate due to the conflict of the magnetic field directions, and the consistency of the interaction of the double magnetic fields in each measurement is ensured, which provides a stable force basis for the conductivity calculation and improves the measurement reliability.

[0056] The application further provides a metal conductivity measurement method of a torsion balance, comprising the following steps: The uniform magnetic field coil and the gradient magnetic field coil are powered, the uniform magnetic field coil generates a uniform magnetic field with a frequency of The gradient magnetic field coil generates a uniform gradient magnetic field with a frequency of

[0057] The sample generates eddy current under the action of the uniform magnetic field, and the eddy current makes the sample receive electromagnetic force under the action of the uniform gradient magnetic field, so that the balance lever is deflected.

[0058] The rotation angle θ of the balance lever is detected by the angle deflection detection device.

[0059] Finally, the conductivity of the sample is calculated by the strength B A of the uniform magnetic field, the strength of the uniform gradient field, the frequency of the uniform magnetic field coil, the frequency of the uniform gradient magnetic field, the rotation angle θ of the balance lever and the arm length L of the balance lever, and the formula is: ​σ is the sample conductivity, B is the uniform magnetic field strength, A B is the uniform magnetic field strength, B is the uniform magnetic field strength, B is the uniform magnetic field strength, B is the uniform magnetic field strength, B is the uniform magnetic field strength,

[0060] Embodiment: First step: after the uniform magnetic field coil and the gradient magnetic field coil are powered on, a uniform magnetic field with a frequency of fa is generated at the sample, and a uniform gradient magnetic field with a frequency of fb is generated; the directions of the two magnetic fields are both horizontal and the same. Under the action of the uniform magnetic field, the sample will generate a vortex current with a frequency of fa, and under the action of the uniform gradient magnetic field, the sample will be subjected to an electromagnetic force F=σG(fa), wherein σ is the metal conductivity, and G(fa) is a constant related to the geometry of the sample size and the magnetic field configuration. Due to the beat frequency, the frequency of the electromagnetic force F is fa-fb.

[0061] Second step: the sample and the counterweight are connected through the balance rod, and the center point of the balance rod is the suspension point. When the sample is subjected to the electromagnetic force F, the sample will be displaced.

[0062] Third step: after the sample is displaced, the balance rod is deflected, and the emitting mirror fixed on the balance rod is also deflected. The light path of the light reading component is deflected along with the deflection of the emitting mirror, so the voltage output by the light reading component device will change along with the deflection of the balance rod, and the deflection angle θ of the torsion balance structure is measured.

[0063] Fourth step: due to the combined action of the uniform magnetic field coil and the gradient magnetic field coil on the sample, the sample will be displaced X, and the torsion balance deflection angle data θ contains the deflection angle at the frequency of fa-fb, and also contains noise. The least square method is used to denoise the torsion balance deflection angle data θ.

[0064] Further, wherein B is the torsion balance parameter function, that is, the torsion balance system function, which is related to the torsion balance structure (moment of inertia, torsion spring elastic coefficient), and L is the arm length of the balance rod.

[0065] Fifth step: the conductivity formula is obtained through formula conversion: σ is the sample conductivity, B is the uniform magnetic field strength, A B is the uniform magnetic field strength, ​​​for the uniform gradient field strength, for the frequency of the uniform magnetic field, for the frequency of the uniform gradient magnetic field, L is the length of the balance lever arm, for the test magnetic field configuration, sample-related constant function, V is the volume of the sample.

[0066] Further, to ensure the accuracy of the combing, different frequencies can be configured for the uniform magnetic field, and the uniform gradient magnetic field to calculate a number of conductivities σ, and thus the average value.

[0067] In the embodiments provided by the present application, a series of different electromagnetic forces F of the sample can also be obtained by configuring different frequencies for the uniform magnetic field, and the uniform gradient magnetic field. According to the relationship F=σG( ), the conductivity σ can be measured by linear fitting of the two sets of data F and frequency G( ). As shown in Figure 3 , the measurement results of copper and aluminum materials are shown, in which the slope of the straight line is the conductivity value.

[0068] As can be clearly seen from Figure 3 , the electromagnetic force response of copper and aluminum materials at different frequencies presents a clear linear relationship. This linear relationship verifies the theoretical basis of the present application, that is, there is a certain functional relationship between the electromagnetic force and the conductivity of the metal. Through the linear fitting method, we can accurately obtain the conductivity values of copper and aluminum, and the measurement results are highly consistent with the standard values, fully proving the reliability of the measuring device and method.

[0069] In practical applications, the measuring device exhibits significant advantages. Since the surface of the metal sample does not need to be specially treated, the measurement process is greatly simplified, and the measurement efficiency is improved. At the same time, the method has high measurement accuracy and repeatability, and can meet the needs of rapid and accurate measurement of the conductivity of metal materials in industrial production. In addition, the device has a compact structure and is easy to operate, and is easy to integrate into existing production lines, providing strong technical support for quality control of metal materials.

[0070] It should be noted that the parts not disclosed or specially stated in the present application are all prior art or conventional settings, and the specific structure and working principle thereof will not be described herein. In this text, the term "including", "containing" or any other variant thereof is intended to cover non-exclusive containing, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0071] Although the embodiments of the present application have been disclosed as above, it is not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present application. Additional modifications can be easily made by those skilled in the art. Therefore, the present application is not limited to specific details and figures shown and described herein without departing from the general concept defined by the claims and their equivalent scope.

Claims

1. A torsion balance metal conductivity measuring device, characterized by, The application relates to a torsion balance metal conductivity measuring device, which comprises the following parts: a magnetic field generating device, which comprises two horizontally arranged uniform magnetic field coils (1) and two gradient magnetic field coils (2), the two uniform magnetic field coils (1) are used for providing a uniform magnetic field, the two gradient magnetic field coils (2) are used for providing a uniform gradient magnetic field, and the magnetic field directions of the uniform magnetic field and the uniform gradient magnetic field are both horizontal directions; a torsion balance structure, which comprises an insulating balance rod (4), a torsion wire (9) and a support frame (10), one end of the torsion wire (9) is fixedly connected with the support frame (10), the other end is rotationally connected with the central position of the balance rod (4), one end of the balance rod (4) is connected with a balancing block (6), the other end is connected with a sample (3), and the sample (3) is located between the two uniform magnetic field coils (1) and between the two gradient magnetic field coils (2); an angle deflection detection device, which is located at the central position of the balance rod (4) and is used for detecting the rotation angle theta of the balance rod (4); a terminal, which is in communication connection with the angle deflection detection device, and the terminal calculates the conductivity of the sample (3) according to the rotation angle of the balance rod (4) and the arm length of the balance rod (4).

2. A torsion balance metal conductivity measuring device as claimed in claim 1, wherein, The uniform magnetic field coil (1) is a Helmholtz coil, the wire diameter of the uniform magnetic field coil (1) is between 1.5 mm and 2.5 mm, the number of turns is between 450 turns and 500 turns, and the outer diameter is between 1.6 times and 2 times the length of the sample (3). The gradient magnetic field coil (2) is a Maxwell coil, the wire diameter of the gradient magnetic field coil (2) is between 1.5 mm and 2.5 mm, the number of turns is between 240 turns and 280 turns, and the outer diameter is between 2 times and 2.5 times the length of the sample (3).

3. A torsion balance metal conductivity measuring device as claimed in claim 2, wherein, The distance between the two uniform magnetic field coils (1) is equal to the outer diameter of the uniform magnetic field coil (1). The distance between the two gradient magnetic field coils (2) is equal to the outer diameter of the gradient magnetic field coils (2) x .

4. A torsion balance metal conductivity measuring device as defined in claim 1, wherein, The angle deflection detection device comprises a reflecting mirror (5) and a light reading component (8). The reflecting mirror (5) is fixed at the central position of the balance rod (4) and is arranged in parallel with the balance rod (4). The light reading component (8) is located on one side of the reflecting mirror (5) and is used for emitting light to the reflecting mirror (5) and reading the light path change of the light, so that the voltage change of the output of the light reading component (8) is caused, and then the rotation angle theta of the balance rod (4) is measured.

5. The torsion balance metal conductivity measuring device according to claim 1, wherein: the magnetic field strength of the uniform magnetic field coil (1) is between 100 muT and 500 muT, and the frequency is between 0.01 Hz and 10 Hz; the magnetic field strength of the gradient magnetic field coil (2) is between 200 muT / m and 1000 muT / m, and the frequency is between 0.01 Hz and 10 Hz.

6. A torsion balance metal conductivity measuring device as defined in claim 1, wherein, The magnetic field directions of the uniform magnetic field and the uniform gradient magnetic field are the same.

7. A method of measuring metal conductivity using a torsion balance metal conductivity measuring device as claimed in any one of claims 1 to 6, characterized by, The application further discloses a method for measuring the conductivity of a metal sample, which comprises the following steps: A uniform magnetic field coil (1) and a gradient magnetic field coil (2) are energized, the uniform magnetic field coil (1) generates a uniform magnetic field with a frequency of , and a strength of B A , the gradient magnetic field coil (2) generates a uniform gradient magnetic field with a frequency of , and a strength of ; the sample (3) generates eddy current under the action of the uniform magnetic field, the eddy current makes the sample (3) suffer from electromagnetic force under the action of the uniform gradient magnetic field, so that the balance rod (4) is deflected; the rotation angle theta of the balance rod (4) is detected by the angle deflection detection device. Finally, the conductivity of the sample (3) is calculated from the frequency of the uniform magnetic field coil (1), the frequency of the uniform gradient magnetic field, the rotation angle θ of the balance bar (4), and the arm length L of the balance bar (4), and the formula is: where σ is the sample conductivity, B is the torsion balance parameter function, A B is the uniform magnetic field strength, B is the uniform gradient field strength, B is the frequency of the uniform magnetic field, B is the frequency of the gradient uniform magnetic field, L is the balance arm length, B is the test magnetic field configuration, sample dependent constant function, V is the volume of the sample.

8. A torsion balance metal conductivity measuring device as claimed in claim 7, wherein, Before calculating the conductivity, the rotation angle θ of the balance bar (4) measured by the angle deflection detection device is removed from noise by the least square method.

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