CN211123228U - Device for measuring magnetic moment of magnet and metal conductivity - Google Patents

Abstract

The utility model belongs to the field of electromagnetism. In order to solve the difficult problem of calculation and measurement of magnetic moment caused by different sizes and shapes of magnets, the utility model discloses a device for measuring the magnetic moment of magnets and the electrical conductivity of metals. The magnetic field lines of the cutting magnet generate induced electromotive force and induced current, and the secondary magnetic field generated by the induced current hinders the change of the magnetic field in the metal tube, that is, hinders the falling of the magnet. The force increases accordingly. When the reaction force acting on the magnet is large enough to balance with gravity, the magnet will fall in a straight line at a uniform speed. The Hall element and the light-emitting diode are fixed at the same distance, and the Hall effect occurs through the Hall element, that is, a low potential is given to the diode, and the diode emits light. Obtain the magnetic moment of the magnet and the electrical conductivity of the metal tube.

Description

A device for measuring magnet magnetic moment and metal conductivity

technical field

The utility model relates to a device for measuring the magnetic moment of an unknown magnet, which belongs to the fields of detection technology, automation and electromagnetism.

Background technique

Magnetic moment measurement and magnetic declination measurement equipment can be traced back to the 1990s. The "Vector Magnetic Moment Test System" produced by the American LDJ Company (merged by Laboratorio Elettrofisico) and the products of the German Brockhaus Company, 2010 The more outstanding ones are the new magnetic declination test system designed by the German matesy company using the magnetoresistive matrix, and the domestic enterprises still use the traditional coil method to measure.

The declination measurement equipment is designed with a fluxmeter and a three-dimensional Helmholtz coil, with a simple principle and strong traceability. However, due to the high requirements for the fluxmeter and the test coil, the requirements for the fluxmeter control drift, the measurement of the Helmholtz coil calibration and the coil orthogonal installation are high. At the same time, due to the low non-spindle component magnetic moment, the The resolution of the fluxmeter is relatively high, and these are the problems that need to be solved for the traditional magnetic declination test equipment. At the same time, the requirements for the test environment are also very high (the environmental magnetic field cannot fluctuate).

The German matesy company uses the magnetoresistive matrix test principle to solve the control problem of the fluxmeter drift, and is not sensitive to the subtle fluctuations of the environmental magnetic field, so that the test repeatability can be greatly improved. If the rotation method is used for measurement, the positioning deviation of the geometric structure can be well solved, and the test magnetic moment M and the magnetic declination angle θz of the main shaft will be perfectly solved, which is worthy of vigorous promotion and application. At present, there is no relevant verification standard for magnetic declination testing equipment in China.

Magnetic moment is an important physical quantity in electromagnetic theory, and it is also an important data in magnet engineering technology. Each magnet has a definite magnetic moment. And the magnetic field formed by any magnet is uniquely (except for the spatial position) determined by the magnetic moment. In other words, as long as the magnetic moment of the magnet is known, the spatial position is determined, and the magnetic field is determined. At present, there are a large number of magnets in magnet engineering and the market. Due to the different sizes and shapes, and the shapes may also be irregular, the calculation and measurement of the magnetic moment become more difficult.

Utility model content

In order to solve the difficult problem of calculation and measurement of magnetic moment caused by different sizes and shapes of magnets, the technical scheme of the present utility model is as follows:

A device for measuring the magnetic moment of a magnet, comprising: a non-ferromagnetic hollow metal tube, several measuring units, a DC power supply, a voltage divider resistance, an STM32 minimum system, a tripod fixing bracket; the inner tube wall and the outer tube wall of the non-ferromagnetic hollow metal tube They are all cylindrical surfaces; several measuring units are evenly distributed along the axis of the non-ferromagnetic hollow metal tube; the measuring units are composed of Hall elements and LED light-emitting diodes; several measuring units are connected in parallel with each other and then connected to DC The power supply and the voltage dividing resistor are connected in series to form a loop; both ends of the voltage dividing resistor are connected to the STM32 minimum system through wires; the STM32 minimum system is used to record the time when the magnet to be measured passes through several measurement units in sequence; the non-ferromagnetic The hollow metal tube is vertically fixed on the tripod mounting bracket.

Preferably, a level and a level adjustment screw are arranged on the tripod fixing bracket. The three supporting feet of the tripod are provided with horizontal adjustment screws, and the non-ferromagnetic hollow metal tube is in a vertical state through adjustment by a spirit level.

Preferably, a vacuuming device is also included, and the non-ferromagnetic hollow metal tube is placed in the vacuuming device. Putting it in a vacuum environment can reduce the resistance of the air and further improve the measurement accuracy.

The above scheme works as follows:

其中

μ₀＝4π×10^-7T·m/A,v_T是磁体下落的终结速度，m是落磁体质量，m_B是磁体的磁矩，σ为非铁磁性空心金属管的电导率，a、b分别为非铁磁性空心金属管的内、外半径。First of all, when there is no magnetic field around the Hall element, its No. 1 pin outputs a high level, and the light-emitting diode is not turned on. At this time, the power in the unit is very small, which can also be understood as a small current; when the magnet passes through At the moment of the device, that is, there is a magnetic field around the Hall element, the No. 1 pin outputs a low level, the light-emitting diode is turned on, and the power in the unit increases, that is, the current increases. At this time, the sampling resistor used by this device converts the current signal into a voltage signal, and then collects the voltage signal and sends it to the STM32 minimum system to convert the analog signal into a digital signal that can be processed; when the magnet to be measured passes through the corresponding measurement unit, When the magnet to be measured passes through the corresponding measurement unit, the Hall element in the corresponding measurement unit senses the magnetic field, the signal output terminal of the Hall element outputs a low level, and the diode emits light; when the voltage across the signal divider resistor is the largest, the minimum system recording time of STM32 information. The magnetic moment of the magnet is related to the final speed, and the final speed is close to the final average speed, and its calculation formula is:

in

μ ₀ =4π×10 ^-7 T·m/A, v _T is the final velocity of the falling magnet, m is the mass of the falling magnet, m _B is the magnetic moment of the magnet, σ is the electrical conductivity of the non-ferromagnetic hollow metal tube, a , b are the inner and outer radii of the non-ferromagnetic hollow metal tube, respectively.

A device for measuring the electrical conductivity of a non-ferromagnetic metal tube, comprising: a magnet with a known magnetic moment, a clamping device, a non-ferromagnetic hollow metal tube to be measured, several measuring units, a DC power supply, a voltage divider, and an STM32 minimum system , Tripod fixing bracket for fixing non-ferromagnetic hollow metal tube;

The inner and outer walls of the non-ferromagnetic hollow metal tube are cylindrical surfaces;

Several measuring units are evenly distributed along the axis of the non-ferromagnetic hollow metal tube;

The measuring unit is composed of a Hall element connected with an LED light-emitting diode;

Several measurement units are connected in parallel with each other and then connected in series with the DC power supply and the voltage dividing resistor to form a loop; both ends of the voltage dividing resistor are connected to the STM32 minimum system through wires;

The STM32 minimum system is used to record the time when the magnet to be measured passes through several measurement units in sequence;

The clamping device is arranged above the non-ferromagnetic hollow metal tube to be tested; the clamping device is used for clamping a magnet with a known magnetic moment.

The above-mentioned device connects the device for measuring the magnetic moment of the magnet in this case when measuring the conductivity of the non-ferromagnetic metal tube;

2) After releasing the clamping device, release the magnet with known magnetic moment; and perform sampling to collect data.

其中

求得该磁体的磁矩。3) Use the formula: magnet magnetic moment

in

Find the magnetic moment of the magnet.

The above technical solution, contrary to the qualitative research on the falling magnet by the traditional electromagnetic induction experiment, combined with the Hall effect, realizes the quantitative determination of the unknown permanent magnet and the electrical conductivity.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that are required to be used in the description of the embodiments or the prior art.

1 is a schematic circuit diagram of a measurement unit branch disclosed in this embodiment;

Among them: 1. Hall element; 2. Light-emitting diode.

FIG. 2 is a schematic diagram of the measuring device disclosed in this embodiment;

Fig. 3 is a schematic diagram of the uniform distribution of several measuring units along the axis of the non-ferromagnetic hollow metal tube;

4 is a schematic diagram of a circuit layout;

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

Example 1

The utility model provides a device for measuring the magnetic moment of a magnet, as shown in Figures 1 to 3, a device for measuring the magnetic moment of a magnet, a non-ferromagnetic hollow metal tube, a number of measuring units, a DC power supply, a voltage divider resistor , STM32 minimum system, tripod fixing bracket; the inner and outer walls of the non-ferromagnetic hollow metal tube are cylindrical surfaces; several measurement units are evenly distributed along the axis of the non-ferromagnetic hollow metal tube; the measurement unit is composed of Hall element 1 is connected with LED light-emitting diode 2; several measurement units are connected in parallel with each other and then connected in series with a DC power supply and a voltage divider resistor to form a loop; both ends of the voltage divider resistor are connected to the STM32 minimum system through wires; the STM32 The minimum system is used to record the time when the magnet to be measured passes through several measuring units in sequence; the non-ferromagnetic hollow metal tube is vertically fixed and placed on the tripod fixing bracket.

Figure 4 shows a design example of nine groups of measurement units, DC power supply, voltage divider resistors, and a minimal system of STM32.

其中

磁体直径略小于铜管直径。本申请用三脚架支起一根非铁磁性金属管，在金属管的表面粘连一块PCB电路板，上面焊接27组相互并联的霍尔元件和LED发光二极管，再串联一个电位器，整个装置连接STM32最小系统用于采样；霍尔元件和LED发光二极管串联，使霍尔元件的信号端连接LED发光二极管，当有磁体通过时，收到信号则LED发光二极管发光；每组串联的霍尔元件和LED发光二极管与下一组之间是等间距的；电位器用于调节串联电阻的电压；STM32最小系统中已烧录记录磁体通过相邻两组LED发光二极管时的时间的程序。The Hall element detects the passing state of the magnet as a sensor, and uses the STM32 minimum system to measure the passing time. The magnetic moment of the magnet is related to the final speed, and the final speed is close to the final average speed. The calculation formula is: The magnetic moment of the magnet is:

in

The magnet diameter is slightly smaller than the copper tube diameter. In this application, a tripod is used to support a non-ferromagnetic metal tube, a PCB circuit board is attached to the surface of the metal tube, 27 groups of Hall elements and LED light-emitting diodes are welded in parallel with each other, and then a potentiometer is connected in series, and the whole device is connected to STM32 The minimum system is used for sampling; the Hall element and the LED light-emitting diode are connected in series, so that the signal end of the Hall element is connected to the LED light-emitting diode. When a magnet passes through, the LED light-emitting diode emits light when the signal is received; The LED light-emitting diodes and the next group are equally spaced; the potentiometer is used to adjust the voltage of the series resistance; the program to record the time when the magnet passes through the adjacent two groups of LED light-emitting diodes has been programmed in the STM32 minimum system.

Better solution: Adhere a circuit board on the surface of the metal tube, solder 27 groups of Hall elements and LED light-emitting diodes in parallel with each other, and then connect a potentiometer in series, the whole device is connected to the STM32 minimum system for sampling, and the STM32 minimum system is connected to a piece HMI screen; the Hall element and the diode are connected in series, so that the signal end of the Hall element is connected to the LED light-emitting diode, and when a magnet passes through, the LED light-emitting diode will receive a signal; each group of the series-connected Hall element and the LED emits light The diodes and the next group are equally spaced; the potentiometer is used to adjust the voltage of the series resistance; the program to record the time when the magnet passes through the adjacent two groups of LED light-emitting diodes has been programmed in the STM32 minimum system; the The HMI screen is used to observe the acquired data. In one embodiment, the model of the single-chip microcomputer in the STM32 minimum system is F103C8T6, and the non-ferromagnetic hollow metal tube uses a copper tube.

The steps for measuring the magnetic moment of the magnet using the above-mentioned device for measuring the magnetic moment of the magnet are:

1) the overall connection of the device for measuring the magnetic moment of the magnet described in the first embodiment;

2) Drop a magnet at an appropriate distance above the non-ferromagnetic hollow metal tube, and conduct sampling to collect data;

其中

求得该磁体的磁矩。3) Use the formula: magnet magnetic moment

in

Find the magnetic moment of the magnet.

The experimental and theoretical calculation process of the magnetic moment measurement of this magnet is as follows:

Through the movement of the magnet in a device, the speed v of the magnet is measured through the Hall element and the embedded system, and the magnetic moment m of the magnet can be calculated through the formula of the speed change of the magnet and other related formulas and important parameters.

The relationship between magnet speed and time is

where τ is the time constant, which can be determined by

where k satisfies the following formula

where μ ₀ =4π×10 ^-7 T·m/A, v _T is the final velocity of the magnet, m is the mass of the falling magnet, m _B is the magnetic moment of the falling magnet, σ is the electrical conductivity of the metal tube, a, b are the inner and outer radii of the metal tube, respectively. By calculating the final velocity of the falling magnet as

In the experiment, the value of k can be calculated according to the formula (4) by measuring the end speed v _T of the magnet and the mass m of the magnet. The magnetic moment m _B can be calculated by formula (3), in which the electrical conductivity σ of the metal tube can be found, and the inner and outer radii a and b of the metal tube can be measured.

actual data:

A specific example: the distance between each group of Hall elements is 5cm, the mass m of a magnet is 3.44g, the outer diameter a of the metal tube is 30.06mm, and the inner diameter b is 19.50mm. The data obtained from one experiment is as follows Shown: Unit: (ms)

It can be seen from the table data that from the time when the magnet falls to the 11th Hall element, the time to pass a certain distance is about 151ms, and this state continues until the end. It can be judged that when the magnet reaches the 11th Hall element, it has been Begin to do a uniform linear motion.

σ=5.7×10 ⁷ S/m

Obtain m _B =3.89×10 ^-5 A·m ²

Embodiment 2

A device for measuring the electrical conductivity of a non-ferromagnetic metal tube, comprising: a magnet with a known magnetic moment, a clamping device, a non-ferromagnetic hollow metal tube to be measured, several measuring units, a DC power supply, a voltage divider, and an STM32 minimum system , Tripod fixing bracket for fixing non-ferromagnetic hollow metal tube; the inner and outer tube walls of the non-ferromagnetic hollow metal tube are cylindrical surfaces;

Several measuring units are evenly distributed along the axis of the non-ferromagnetic hollow metal tube; the measuring units are composed of Hall elements and LED light-emitting diodes; connected in series to form a loop; both ends of the voltage divider are connected to the STM32 minimum system through wires; the STM32 minimum system is used to record the time when the magnet to be measured passes through several measurement units in sequence; Above a ferromagnetic hollow metal tube; the clamping device is used to clamp a magnet of known magnetic moment.

The steps for measuring the conductivity of a non-ferromagnetic metal tube using the above device are:

1) the overall connection of the device for measuring the magnetic moment of the magnet described in the first embodiment;

2) Drop a magnet with a known magnetic moment m _B at an appropriate distance above the non-ferromagnetic hollow metal tube; and perform sampling to collect data;

其中ρ是非铁磁性空心金属管的电阻率，m是落磁体质量，m_B是落磁体磁矩，v_T是落磁体终结速度，求得该磁体的电导率。3) Apply the formula: the conductivity of the non-ferromagnetic hollow metal tube

where ρ is the resistivity of the non-ferromagnetic hollow metal tube, m is the mass of the falling magnet, m _B is the magnetic moment of the falling magnet, v _T is the final velocity of the falling magnet, and the electrical conductivity of the magnet is obtained.

In the technical solution of the present utility model, the magnet falls in the metal tube, the magnetic field lines of the metal tube cutting the magnet generate an induced electromotive force, thereby generating an induced current, and the secondary magnetic field generated by the induced current hinders the change of the magnetic field in the metal tube, that is, prevents the magnet from falling , so that the falling acceleration of the magnet gradually becomes smaller; with the acceleration of the falling speed of the magnet, the induced current increases, and the ampere force that hinders the falling of the magnet increases, and its reaction force acts on the magnet; When the reaction force is large enough to balance with gravity, the magnet will fall in a straight line at a constant speed. A group of Hall elements and light-emitting diodes are fixed at the same distance, and the Hall effect occurs through the Hall elements, that is, a low potential is given to the diode, and the diode emits light. At the same time, the STM32 minimum system performs ADC sampling to obtain the time taken for that distance, namely The speed through this distance can be obtained, and the magnetic moment of the magnet can be obtained by using the formula.

The technical scheme of the utility model is not limited to the measurement of electrical conductivity and magnetic moment, and other measurement functions can be expanded on the basis of indirect measurement. The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

Claims (5)

1. An apparatus for measuring a magnetic moment of a magnet, comprising: the device comprises a non-ferromagnetic hollow metal pipe, a plurality of measuring units, a direct-current power supply, a voltage-dividing resistor, an STM32 minimum system and a tripod fixing support for fixing the non-ferromagnetic hollow metal pipe;

the inner pipe wall and the outer pipe wall of the non-ferromagnetic hollow metal pipe are both cylindrical surfaces;

the plurality of measuring units are uniformly distributed along the axial direction of the non-ferromagnetic hollow metal pipe;

the measuring unit is formed by connecting a Hall element with L ED light-emitting diodes;

a plurality of measuring units are connected in parallel and then connected in series with a direct current power supply and a divider resistor to form a loop; two ends of the divider resistor are connected into the STM32 minimum system through leads;

the STM32 minimum system is used for recording the time when the magnet to be measured sequentially passes through the plurality of measuring units;

the non-ferromagnetic hollow metal pipe is vertically and fixedly placed on the tripod fixing support.

2. The apparatus of claim 1, wherein when a magnet to be measured passes through the corresponding measuring unit, the hall element in the corresponding measuring unit senses a magnetic field, the signal output terminal of the hall element outputs a low level, and the diode emits light; STM32 minimum system recording time information when the voltage across the signal divider resistor is maximum.

3. The apparatus of claim 1, wherein a level and leveling screw are provided on the tripod mounting bracket.

4. An apparatus for measuring the magnetic moment of a magnet according to claim 1, further comprising a vacuum means, wherein said non-ferromagnetic hollow metal tube is placed in said vacuum means.

5. An apparatus for measuring the conductivity of a non-ferromagnetic metal tube, comprising: the device comprises a magnet with known magnetic moment, a clamping device, a non-ferromagnetic hollow metal pipe to be measured, a plurality of measuring units, a direct-current power supply, a voltage-dividing resistor, an STM32 minimum system and a tripod fixing support for fixing the non-ferromagnetic hollow metal pipe;

the inner pipe wall and the outer pipe wall of the non-ferromagnetic hollow metal pipe are both cylindrical surfaces;

the plurality of measuring units are uniformly distributed along the axial direction of the non-ferromagnetic hollow metal pipe;

the measuring unit is formed by connecting a Hall element with L ED light-emitting diodes;

a plurality of measuring units are connected in parallel and then connected in series with a direct current power supply and a divider resistor to form a loop; two ends of the divider resistor are connected into the STM32 minimum system through leads;

the STM32 minimum system is used for recording the time when the magnet to be measured sequentially passes through the plurality of measuring units;

the clamping device is arranged above the non-ferromagnetic hollow metal pipe to be detected; the clamping device is used for clamping a magnet with known magnetic moment.

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