CN115458273B - Double-layer cylindrical permanent magnet anti-magnetic suspension device and preparation and application methods thereof - Google Patents

Abstract

The invention discloses a double-layer cylindrical permanent magnet anti-magnetic levitation device and a preparation and application method thereof. A double-layer cylindrical permanent magnet anti-magnetic levitation device. The permanent magnet is made of strong magnets, including sintered NdFeB magnets or sintered SmCo magnets; There is a through hole in the center of the upper and lower cylinders, the upper magnetic pole through hole is used to accommodate and suspend diamagnetic objects, and the lower hole is used to place optical fibers or micro detectors; the magnetization direction of the upper and lower cylinders On the contrary, the magnetization direction of the upper cylinder is radially inward or outward, and the magnetization direction of the lower cylinder is radially outward or inward. Simulations show that the confinement ability of the magnetic potential well produced by the present invention is stronger than that of the conventional multi-pole splicing magnetic potential well, which can solve the problem of the difficulty in aligning and aligning various components during the assembly process of conventional multi-magnetic pole magnets, resulting in uneven distribution of the magnetic potential well, etc. technical problem.

Description

A double-layer cylindrical permanent magnet anti-magnetic suspension device and its preparation and application method

Technical Field

The invention relates to the field of permanent magnet device design in anti-magnetic suspension, and relates to a double-layer cylindrical permanent magnet anti-magnetic suspension device and a preparation and application method thereof.

Background Art

Antimagnetic suspension mechanical oscillator is an important tool for precision measurement and is often used to prepare high-precision sensors, including displacement meters, accelerometers, magnetometers and dynamometers. The principle of antimagnetic suspension sensor is: using a pre-designed permanent magnet with a specific configuration to provide a magnetic potential well, the magnetic force on the antimagnetic object in the magnetic field can balance the object's own gravity, so that it is suspended in the magnetic potential well. Because the suspended mechanical oscillator can be well isolated from the external environment, the interference of external environmental noise is greatly reduced, so it can be used as a precision measurement sensor. Thanks to the fact that the suspended mechanical oscillator can be well isolated from the surrounding environment, the suspended mechanical oscillator has a higher quality factor than the conventional sensing mechanical oscillator. Common suspension mechanisms include: electric suspension, optical suspension, superconducting magnetic suspension and antimagnetic suspension. Among them, superconducting suspension can only be applied to low-temperature systems. Compared with other suspension mechanisms, antimagnetic suspension uses a passive suspension mechanism, so it does not need to inject more energy to suspend objects with larger masses, so it has more application value in suspending larger devices.

For anti-magnetic suspension systems, permanent magnets provide magnetic fields, and the design of the permanent magnet configuration directly determines the suspension ability and suspension quality of the magnetic field. At present, the permanent magnet configuration used to provide the suspension magnetic field is composed of multiple magnetic poles assembled together. For example, several magnetic blocks are magnetized and then assembled together with structural parts or glued together. This will cause many problems: First, the magnetic blocks repel each other, and it is difficult for the operator to splice the magnetic blocks together; second, even if the operator splices the magnetic blocks together according to the configuration requirements, it is difficult to align the magnetic blocks as required, which will cause the magnetic potential wells to be uneven and affect the suspension quality; third, the gaps between the magnetic blocks are glued with glue, which may cause charge accumulation and affect the suspension of the device.

Summary of the invention

In view of the shortcomings of the prior art, the present invention proposes a double-layer cylindrical permanent magnet anti-magnetic suspension device and its preparation and application method, which does not require splicing or packaging, and relies on self-generated magnetic force to naturally attract the double-layer magnets together, providing a stable, uniform, and high-strength magnetic potential well.

The objective of the present invention is achieved through the following technical solutions:

A double-layer cylindrical permanent magnet anti-magnetic suspension device,

The permanent magnet material is selected from strong magnets, including sintered NdFeB magnets or sintered SmCo magnets;

The permanent magnet has a two-layer structure, the upper and lower layers are coaxial cylinders with equal diameters and unequal heights;

A through hole is left in the center of the upper and lower cylinders. The through hole of the upper magnetic pole is used to accommodate and suspend the antimagnetic object, and the hole of the lower layer is used to place the optical fiber, micro lens or micro detector;

The magnetization directions of the upper and lower cylinders are opposite, the magnetization direction of the upper cylinder is radially inward or outward, and the magnetization direction of the lower cylinder is radially outward or inward.

The double-layer cylindrical permanent magnet antimagnetic suspension device, the processing flow of the permanent magnet is as follows:

Step 1: Prepare materials, choose raw materials such as NdFeB magnets or SmCo magnets according to your needs;

Step 2: Powdering, putting the raw materials prepared in step 1 into a smelting furnace for smelting, forming an alloy after smelting and cooling, and crushing and grinding the alloy into magnetic powder;

Step 3: Pressing, the magnetic powder prepared in step 2 is loaded into a pre-designed mold, the magnetic powder is oriented to be consistent with the subsequent magnetization direction, and a pressed embryo is formed after pressing;

Step 4: sintering;

Step 5: Processing: Cut, drill, grind and roll the formed magnets according to the size and shape requirements. When cutting, the orientation of the magnets should be consistent with the magnetization direction.

Step 6: Plating, choose whether to plate according to the working environment requirements;

Step 7: Magnetization.

The permanent magnet has a two-layer structure, and its geometric parameter characteristics are:

The diameters of the upper and lower cylinders are equal, ranging from 10 mm to 40 mm. The size is selected according to the requirements. This parameter has little effect on the suspension ability of the magnetic potential well.

The height of the upper cylinder is 1mm to 5mm, and the height of the lower cylinder is 4 to 15mm. Select the size according to your requirements;

The diameters of the central holes of the upper and lower layers of cylinders are characterized by geometric parameters:

The diameter of the central through hole of the upper cylinder is 1 mm to 4 mm;

The diameter of the central through hole of the lower cylinder is 1 mm to 3 mm.

The through hole,

The upper magnetic pole penetration holes are used to accommodate and suspend antimagnetic objects, and the lower holes are used to place optical fibers, micro lenses or micro detectors;

By placing optical fibers and micro lenses, a magneto-optical potential well can be prepared, which can combine the advantages of a magnetic potential well for suspending large particles and an optical potential well for high resonant frequency.

Placing a micro-detector makes it easier to detect the movement of the suspended oscillator;

The size of the through hole has a great influence on the suspension ability. The smaller the through hole, the stronger the suspension ability, but the size of the suspended object will also become smaller. The specific size depends on the size and magnetic susceptibility of the suspended object.

A method for preparing the double-layer cylindrical permanent magnet anti-magnetic suspension device according to the invention comprises the following steps:

Step 1: Prepare the corresponding mold, and sinter to produce two cylindrical permanent magnets with through holes of different heights and radiation magnetization;

Step 2: Use a magnetizer to perform radiation magnetization on the two cylinders respectively, with the magnetization direction of the upper cylinder being radially inward or outward, and the magnetization direction of the lower cylinder being radially outward or inward accordingly;

Step 3: The two cylindrical permanent magnets are attracted together through their own magnetic bottom surfaces to form an overall cylindrical magnetic potential well device.

The processing flow of the permanent magnet is as follows:

Step 1: Prepare materials, choose raw materials such as NdFeB magnets or SmCo magnets according to your needs;

Step 2: Powdering, putting the raw materials prepared in step 1 into a smelting furnace for smelting, forming an alloy after smelting and cooling, and crushing and grinding the alloy into magnetic powder;

Step 3: Pressing, the magnetic powder prepared in step 2 is loaded into a pre-designed mold, the magnetic powder is oriented to be consistent with the subsequent magnetization direction, and a pressed embryo is formed after pressing;

Step 4: sintering;

Step 5: Processing: Cut, drill, grind and roll the formed magnets according to the size and shape requirements. When cutting, the orientation of the magnets should be consistent with the magnetization direction.

Step 6: Plating, choose whether to plate according to the working environment requirements;

Step 7: Magnetization.

An application method of the double-layer cylindrical permanent magnet anti-magnetic suspension device is used to suspend a high-sensitivity mechanical vibrator, and the steps are as follows:

Step 1: Prepare the anti-magnetic levitation potential well device;

Step 2: Prepare the object to be suspended, the material must be diamagnetic;

Step 3: Place the object to be suspended in the antimagnetic levitation potential well. The magnetic force is balanced with the gravity, satisfying the following relationship:

Where B is the magnetic field intensity, χ is the diamagnetic susceptibility of the suspended object, μ0 is _the vacuum magnetic permeability, ρ is the density of the diamagnetic object, and z is the suspension position;

Step 4: Apply the signal to be tested to the suspended oscillator;

Step 5: Observe the suspension motion of the suspended object, irradiate the suspended object with laser, the laser scattered by the suspended object interferes with the reference laser prepared in advance, and read the motion signal of the suspended object according to the change of the interference laser intensity.

In the step 2, the antimagnetic material includes polymethyl methacrylate (PMMA), diamond, silicon dioxide, pyrolytic graphite, and bismuth. The shape depends on the specific requirements, including spheres, blocks, and cylinders. The size of the object to be suspended is smaller than the diameter of the through hole of the upper magnet of the double-layer cylindrical magnetic potential well. The specific material and size are determined according to the suspension capacity of the magnetic potential well.

The step 4: the signals to be measured can be various, including: vibration acceleration signals, gravitational signals, electrical signals, magnetic signals and some novel force signals at the forefront of science.

The step five:

First, prepare a laser light source, and use BS to split the laser beam into two beams, one as reference light, and the other as detection light, which is projected onto the suspended object. Use a lens to collect the reference light and the detection light to interfere with each other, and use a four-quadrant photodetector to detect the light power after interference. Analyze the change in the detection voltage of the photodetector caused by the change in the detection laser power to obtain the movement of the suspended object:

ΔX = ζΔV

In the above formula, V is the detection voltage, the change of the detection voltage is ΔV, the displacement of the suspended object is ΔX, and ζ is the volt-meter coefficient, whose value can be obtained through thermal noise calibration. After the displacement of the suspended oscillator is obtained, the applied signal to be measured is obtained by demodulation.

The beneficial effects of the present invention are:

1. Since the double-layer cylindrical device is formed in one process, it is naturally adsorbed together without the need for glue bonding, and there is no problem of gap charge accumulation interfering with the suspension mechanical device;

2. It solves the problem that it is difficult for operators to splice and assemble magnets, greatly improving the convenience of operation and improving the operating efficiency;

3. It solves the problem of difficult alignment of traditional assembled magnets, ensures the uniformity of magnetic potential well distribution, and facilitates the acquisition of higher quality magnetic potential wells;

4. The double-layer cylindrical permanent magnet anti-magnetic levitation potential well has stronger levitation ability than the spliced assembled magnet potential well, and the suspended object can select objects with a larger mass range.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a structural diagram of a double-layer cylindrical permanent magnet anti-magnetic suspension device disclosed in the present invention.

FIG2 is a cross-sectional view of the magnetic field intensity distribution of a double-layer cylindrical permanent magnet anti-magnetic suspension device disclosed in the present invention.

FIG. 3 is a potential energy density curve in the z direction of a double-layer cylindrical permanent magnet anti-magnetic suspension device disclosed in the present invention.

FIG. 4 is a potential energy density curve in the x direction of a double-layer cylindrical permanent magnet anti-magnetic suspension device disclosed in the present invention.

FIG. 5 is a light path diagram of a double-layer cylindrical permanent magnet anti-magnetic suspension device for detecting the motion of a suspended object disclosed in the present invention.

In the figure: an upper cylindrical magnet with a through hole 1; a lower cylindrical magnet with a through hole 2; the upper cylindrical magnet through hole is the suspended particle binding area 3; the lower cylindrical magnet through hole 4.

DETAILED DESCRIPTION

The present invention is further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, a double-layer cylindrical permanent magnet anti-magnetic suspension device,

The permanent magnet material is selected from strong magnets, including sintered NdFeB magnets or sintered SmCo magnets;

The permanent magnet has a two-layer structure, the upper and lower layers are coaxial cylinders with equal diameters and unequal heights;

A through hole is left in the center of the upper and lower cylinders. The upper magnetic pole through hole is used to accommodate and suspend the antimagnetic object, and the lower hole is used to place the optical fiber micro lens or micro detector.

The magnetization directions of the upper and lower cylinders are opposite, the magnetization direction of the upper cylinder is radially inward or outward, and the magnetization direction of the lower cylinder is radially outward or inward.

The double-layer cylindrical permanent magnet antimagnetic suspension device, the processing flow of the permanent magnet is as follows:

Step 1: Prepare materials, choose raw materials such as NdFeB magnets or SmCo magnets according to your needs;

Step 2: Powdering, putting the raw materials prepared in step 1 into a smelting furnace for smelting, forming an alloy after smelting and cooling, and crushing and grinding the alloy into magnetic powder;

Step 3: Pressing, the magnetic powder prepared in step 2 is loaded into a pre-designed mold, the magnetic powder is oriented to be consistent with the subsequent magnetization direction, and a pressed embryo is formed after pressing;

Step 4: sintering;

Step 5: Processing: Cut, drill, grind and roll the formed magnets according to the size and shape requirements. When cutting, the orientation of the magnets should be consistent with the magnetization direction.

Step 6: Plating, choose whether to plate according to the working environment requirements;

Step 7: Magnetization.

The permanent magnet has a two-layer structure, and its geometric parameter characteristics are:

The diameters of the upper and lower cylinders are equal, ranging from 10 mm to 40 mm. The size is selected according to the requirements. This parameter has little effect on the suspension ability of the magnetic potential well.

The height of the upper cylinder is 1mm to 5mm, and the height of the lower cylinder is 4 to 15mm. Select the size according to your requirements;

The diameters of the central holes of the upper and lower layers of cylinders are characterized by geometric parameters:

The diameter of the central through hole of the upper cylinder is 1 mm to 4 mm;

The diameter of the central through hole of the lower cylinder is 1 mm to 3 mm.

The through hole,

The upper magnetic pole penetration holes are used to accommodate and suspend antimagnetic objects, and the lower holes are used to place optical fibers, micro lenses or micro detectors;

By placing optical fibers and micro lenses, a magneto-optical potential well can be prepared, which can combine the advantages of a magnetic potential well for suspending large particles and an optical potential well for high resonant frequency.

Placing a micro-detector makes it easier to detect the movement of the suspended oscillator;

The size of the through hole has a great influence on the suspension ability. The smaller the through hole, the stronger the suspension ability, but the size of the suspended object will also become smaller. The specific size depends on the size and magnetic susceptibility of the suspended object.

A method for preparing the double-layer cylindrical permanent magnet anti-magnetic suspension device according to the invention comprises the following steps:

Step 1: Prepare the corresponding mold, and sinter to produce two cylindrical permanent magnets with through holes of different heights and radiation magnetization;

Step 2: Use a magnetizer to perform radiation magnetization on the two cylinders respectively, with the magnetization direction of the upper cylinder being radially inward or outward, and the magnetization direction of the lower cylinder being radially outward or inward accordingly;

Step 3: The two cylindrical permanent magnets are attracted together through their own magnetic bottom surfaces to form an overall cylindrical magnetic potential well device.

The processing flow of the permanent magnet is as follows:

Step 1: Prepare materials, choose raw materials such as NdFeB magnets or SmCo magnets according to your needs;

Step 2: Powdering, putting the raw materials prepared in step 1 into a smelting furnace for smelting, forming an alloy after smelting and cooling, and crushing and grinding the alloy into magnetic powder;

Step 3: Pressing, the magnetic powder prepared in step 2 is loaded into a pre-designed mold, the magnetic powder is oriented to be consistent with the subsequent magnetization direction, and a pressed embryo is formed after pressing;

Step 4: sintering;

Step 5: Processing: Cut, drill, grind and roll the formed magnets according to the size and shape requirements. When cutting, the orientation of the magnets should be consistent with the magnetization direction.

Step 6: Plating, choose whether to plate according to the working environment requirements;

Step 7: Magnetization.

Application Examples

Step 1: Theoretical calculation of anti-magnetic levitation and simulation of magnetic potential well are now explained in conjunction with Figures 1 to 4.

The basic principle of diamagnetic levitation is that diamagnetic materials will be repelled by the magnetic field. When the repulsive force and gravity are balanced and there is restoring force in all directions, the diamagnetic levitation potential well is formed. The magnetic potential energy of an object in the magnetic potential well is:

Where μ = μ ₀ (1 + χ ) is the magnetic permeability of the material, χ is the magnetic susceptibility of the material. For antimagnetic materials, the magnetic susceptibility χ < 0, V is the volume of the object, and B is the magnetic induction intensity distribution at the location of the object. The magnetic force on the object is the negative gradient of the magnetic potential energy, satisfying:

。

.

When the magnetic field force is balanced with the gravity, it can levitate. However, if a stable balance is required, it must always be a parabola with the opening upwards in all directions:

Where W = W _m + mgz , k is the elastic coefficient of the magnetic potential well.

On this theoretical basis, COMSOL finite element simulation is used to simulate the magnet structure that can meet this condition. The magnetic energy density of magnet structures with different configurations can be obtained through finite element simulation calculation. By judging whether the magnetic gravity potential energy density curve in different directions satisfies the parabola with an opening upward, it can be determined whether this magnet structure can suspend antimagnetic materials and the range of antimagnetic materials with magnetic susceptibility that can be suspended. After continuously changing the magnet structure and magnetization direction, a double-layer cylindrical magnetic pole structure as shown in Figure 1 is obtained. It is composed of two layers of cylindrical structures with through holes, including an upper cylindrical magnet 1 with through holes, a lower cylindrical magnet 2 with through holes, an upper cylindrical magnet through hole, i.e., a suspended particle confinement zone 3, and a lower cylindrical magnet through hole 4.

，密度

的PMMA小球在此势阱中的磁重 力势能密度函数，其函数曲线满足开口向上的抛物线型，故能悬浮，且悬浮位置在抛物线最 底部。其x方向（y方向）的磁势能密度如图4所示，也为开口向上的抛物线型，由此说明所述 磁体结构能满足三维空间稳定悬浮。 In order to demonstrate the suspension effect of the magnetic potential well of the structure, an example is given here. It is particularly noted that the following various parameters are an example of the present invention and should not be regarded as the whole of the present invention, or as a definition or restriction of the present invention. The upper magnetic pole has an outer diameter of 20mm, an inner diameter of 1.4mm, a height of 2mm, and magnetization radially outward; the lower magnetic pole has an outer diameter of 20mm, an inner diameter of 1mm, a height of 6mm, and magnetization radially inward as a special case. After the magnet structure is sucked together by the self-generated magnetic attraction, its magnetic field distribution is shown in Figure 2, where the green box is the confinement area of the magnet structure, and antimagnetic materials can be suspended in this area. Figure 3 shows a magnetic susceptibility

,density

The magnetic gravitational potential energy density function of the PMMA ball in this potential well has a function curve that satisfies a parabola with an opening upward, so it can be suspended, and the suspension position is at the bottom of the parabola. The magnetic potential energy density in the x direction (y direction) is shown in FIG4 , which is also a parabola with an opening upward, which shows that the magnetic structure can satisfy the requirement of stable suspension in three-dimensional space.

Step 2: Processing of double-layer cylindrical permanent magnet device:

The double-layer cylindrical permanent magnet anti-magnetic levitation potential well is cylindrical as a whole. There is a through hole in the middle of the upper and lower layers of permanent magnet cylinders. The through hole is convenient for radiation magnetization. The upper through hole is used to accommodate and suspend anti-magnetic objects and is the location of the binding area. The lower through hole can be used to place detection optical fibers, micro lenses, micro detectors and other objects; the upper and lower layers of cylindrical permanent magnets have opposite magnetization directions, the upper magnetization direction is radially inward, and the lower magnetization direction is radially outward, or the upper magnetization direction is radially outward and the lower magnetization direction is radially inward; the outer diameter of the upper cylindrical magnet is 10mm to 40mm, the inner diameter (through hole diameter) is 1mm to 4mm, and the height is 1mm to 5mm. The outer diameter of the lower cylindrical magnet is the same as that of the upper layer, the inner diameter (through hole diameter) is 1mm to 3mm, and the height is 4mm to 15mm.

The specific implementation steps are as follows:

Step 1: Processing the mold: preparing a cylindrical magnet mold according to a standardized process. This mold is required to be able to process the cylindrical magnet with through holes and to achieve radiation magnetization.

Step 2: Prepare materials. Choose the raw materials of magnets according to your needs. NdFeB magnets and SmCo magnets have their own advantages. NdFeB magnets are more magnetic and cheaper. SmCo magnets have the advantage of high temperature resistance and can be used in environments of 350℃ and below. Choose raw materials according to the requirements of the use environment and relevant standards.

Step 3: Powdering: Put the raw materials prepared in step 2 into a smelting furnace for smelting. After smelting and cooling, an alloy is formed. The alloy is crushed and ground into magnetic powder.

Step 4: Pressing. Put the magnetic powder prepared in step 3 into the mold made in step 1. Since the magnetic powder is anisotropic, the orientation of the magnetic powder should be consistent with the direction of subsequent magnetization, otherwise the magnetism of the magnet will be greatly reduced. Therefore, an external magnetic field should be applied before pressing to process the orientation of the magnetic powder to ensure that its orientation is consistent with the direction of subsequent magnetization. Through the external magnetic field, the orientation of the magnetic powder is radial along the radial direction, so as to facilitate the subsequent radiation magnetization. The embryo is pressed under the action of the external radial magnetic field.

Step 5: Sintering. In order to make the magnet obtain high permanent magnetic properties, the magnet pressed embryo prepared in step 4 needs to be heat treated, that is, sintered. Note that the sintering temperature must be lower than the melting point of the magnetic powder. After sintering for a period of time, the pressed embryo will change from magnetic powder to a bulk magnet, that is, the magnet is formed.

Step 6: Processing: Cut, drill, grind and roll the formed magnets according to the size and shape requirements. Note that the cutting must ensure that the orientation of the magnets is consistent with the magnetization direction.

Step 7: Coating. NdFeB magnets are prone to oxidation and corrosion in air environments due to their high iron content, so they need to be plated on the surface. The plating is generally done by electroplating. The plating materials can be zinc, tin, copper, or gold. Smco magnets have strong oxidation resistance, so you can choose whether to plate them according to the working environment requirements.

Step 8: Magnetization. For high coercive force magnets, pulse magnetization is generally adopted. The principle is to use high-voltage capacitor discharge to generate a short and extremely large current in the coil wire, so as to obtain an instantaneous strong magnetic field inside the coil. The magnet is magnetized by the strong magnetic field to achieve the purpose of magnetization. The processed upper and lower layers of magnets are radiated and magnetized respectively. The magnetization directions are opposite. The upper layer is magnetized radially inward and the lower layer is magnetized radially outward. It can also be radially outward for the upper layer and radially inward for the lower layer.

Step 9: Attract two cylindrical permanent magnets together through their own magnetic bottom surfaces to form an overall cylindrical magnetic potential well.

Step 3: An application method of a double-layer cylindrical permanent magnet anti-magnetic suspension potential well, the steps are as follows:

Step 1: Prepare an anti-magnetic levitation potential well, which is provided by the double-layer cylindrical permanent magnet prepared in the second step.

Step 2: Prepare the object to be suspended. The material of the suspended object has antimagnetic properties. According to actual needs, organic materials such as polymethyl methacrylate (PMMA), diamond, silicon dioxide, pyrolytic graphite, bismuth, etc. can be selected. The shape depends on specific requirements. It can be in the shape of a sphere, block, cylinder, etc. The object size must be smaller than the diameter of the through hole of the upper magnet of the double-layer cylindrical magnetic potential well. The specific material and size should also be determined according to the suspension capacity of the magnetic potential well.

Step 3: Place the object to be suspended in the potential well of the diamagnetic suspension device. The principle is that the magnetic force and gravity exerted on the diamagnetic object in the magnetic potential well are balanced, satisfying the following relationship:

Where B is the magnetic field intensity, χ is the diamagnetic susceptibility of the suspended object, μ0 is _the vacuum magnetic permeability, ρ is the density of the diamagnetic object, and z is the suspension position.

Step 4: Apply the signal to be tested to the suspended oscillator. The signal to be tested can be varied, including: vibration acceleration signal, gravitational signal, electrical signal, magnetic signal and some novel force signals at the forefront of science.

Step 5: Observe the suspension motion of the suspended object. The detection light path is shown in Figure 5. The laser is incident on the suspended object. The laser scattered by the suspended object interferes with the reference laser prepared in advance. The motion signal of the suspended object is read according to the change in the intensity of the interfering laser. The specific operation method is: first prepare a laser light source, divide the laser beam into two beams with BS, one beam is used as the reference light, and the other beam is hit on the suspended object as the detection light; use a lens to collect the reference light and the detection light to interfere with each other, and use a four-quadrant photodetector to detect the light power after interference, as shown in Figure 5. Analyze the change in the detection voltage of the photodetector caused by the change in the detection laser power to obtain the motion of the suspended object:

ΔX = ζΔV

In the above formula, V is the detection voltage, the change of the detection voltage is ΔV, the displacement of the suspended object is ΔX, and ζ is the volt-meter coefficient, whose value can be obtained through thermal noise calibration. After the displacement of the suspended oscillator is obtained, the applied signal to be measured is obtained by demodulation.

The technical features of the above-described embodiments can be further combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims (8)

1. A double-layer cylindrical permanent magnet anti-magnetic suspension device is characterized in that:

the permanent magnet material is selected from strong magnets, including sintered neodymium-iron-boron magnets or sintered samarium-cobalt magnets;

the permanent magnet is provided with an upper layer and a lower layer which are coaxial cylinders with equal diameters and unequal heights;

the centers of the upper layer cylinder and the lower layer cylinder are respectively provided with a through hole, the through holes of the centers of the upper layer cylinder are used for accommodating and suspending the antimagnetic objects, and the through holes of the centers of the lower layer cylinder are used for placing optical fibers, micro lenses or micro detectors;

the magnetization directions of the upper and lower cylinders are opposite, the magnetization direction of the upper cylinder is inward or outward along the radial direction, and the magnetization direction of the lower cylinder is outward or inward along the radial direction;

the permanent magnet processing flow of the device is as follows:

step one: preparing materials, namely selecting raw materials of neodymium-iron-boron magnets or samarium-cobalt magnets according to requirements;

step two: pulverizing, namely putting the raw materials prepared in the first step into a smelting furnace to smelt, forming an alloy after smelting and cooling, and grinding the alloy into magnetic powder;

step three: pressing, namely filling the magnetic powder prepared in the second step into a mould designed in advance, carrying out orientation treatment on the magnetic powder to be consistent with the subsequent radiation magnetizing direction, and forming a pressing blank after pressing;

step four: sintering;

step five: processing, namely cutting, drilling, grinding and barreling the formed magnet according to the size and shape requirements, wherein the orientation of the magnet is consistent with the radiation magnetizing direction during cutting;

step six: a plating layer, wherein whether the plating layer is selected according to the requirement of the working environment;

step seven: radiation magnetizing.

2. The double-layer cylindrical permanent magnet anti-magnetic levitation device according to claim 1, characterized in that: the permanent magnet of the device is provided with an upper layer structure and a lower layer structure, and the geometric parameter characteristics are as follows:

the diameters of the upper layer of cylinder and the lower layer of cylinder are equal and are 10mm to 40mm, the size is selected according to the requirement, and the influence of the parameter on the suspension capacity of the device is small;

the height of the upper layer cylinder is 1mm to 5mm, the height of the lower layer cylinder is 4mm to 15mm, and the size is selected according to the requirement;

the diameters of the central holes of the upper layer cylinder and the lower layer cylinder are characterized in that:

the diameter of the central through hole of the upper cylinder is 1mm to 4mm;

the diameter of the central through hole of the lower cylinder is 1mm to 3mm.

3. A method for preparing the double-layer cylindrical permanent magnet anti-magnetic suspension device according to claim 1, which is characterized in that: the method comprises the following steps:

step one: preparing corresponding molds, and sintering to process two cylindrical permanent magnets which are not provided with through holes in height and are provided with radiation magnetization;

step two: the two cylinders are respectively subjected to radiation magnetization by using a magnetizer, the magnetization direction of the upper cylinder is inward or outward along the radial direction, and the magnetization direction of the lower cylinder is outward or inward along the radial direction correspondingly;

step three: two cylindrical permanent magnets are attracted together through the bottom surface of the magnetic force of the two cylindrical permanent magnets to form the integral cylindrical magnetic suspension device.

4. A method of manufacture according to claim 3, characterized in that: the processing flow of the permanent magnet is as follows:

step one: preparing materials, namely selecting raw materials of neodymium-iron-boron magnets or samarium-cobalt magnets according to requirements;

step two: pulverizing, namely putting the raw materials prepared in the first step into a smelting furnace to smelt, forming an alloy after smelting and cooling, and grinding the alloy into magnetic powder;

step three: pressing, namely filling the magnetic powder prepared in the second step into a die designed in advance, carrying out orientation treatment on the magnetic powder to be consistent with the subsequent magnetizing direction, and forming a pressing blank after pressing;

step four: sintering;

step five: processing, namely cutting, drilling, grinding and barreling the formed magnet according to the size and shape requirements, wherein the orientation of the magnet is consistent with the magnetizing direction during cutting;

step six: a plating layer, wherein whether the plating layer is selected according to the requirement of the working environment;

step seven: magnetizing.

5. An application method of the double-layer cylindrical permanent magnet anti-magnetic levitation device according to claim 1, which is used for levitation of high-sensitivity levitation objects, and comprises the following steps:

step one: preparing an anti-magnetic suspension device;

preparing an object to be suspended, wherein the material has diamagnetism;

step three: placing an object to be suspended in an antimagnetic suspension potential well, and balancing the received magnetic force and gravity, wherein the following relation is satisfied:

wherein B is the intensity of the magnetic field,χin order to levitate the object for anti-magnetization,μ ₀ is the magnetic permeability of the vacuum and is equal to the magnetic permeability of the vacuum,ρfor the density of the diamagnetic object,zis a floating position;

step four: applying a signal to be measured to a suspended object;

step five: observing the suspension movement of the suspension object, incidence laser to the suspension object, interference between the laser scattered by the suspension object and the reference laser prepared in advance, reading the movement signal of the suspension object according to the intensity change of the interference laser, and demodulating the signal to be detected.

6. The method according to claim 5, wherein in the second step, the antimagnetic material comprises polymethyl methacrylate (PMMA), diamond, silicon dioxide, pyrolytic graphite, bismuth, and the shape is determined according to specific requirements, and the antimagnetic material comprises spheres and cylinders, and the size of the object to be suspended is smaller than the diameter of the central through hole of the upper cylinder of the double-layer cylinder type magnetic suspension device, and the specific material and size are determined according to the suspending capability of the magnetic potential well.

7. The method of claim 5, wherein the step four: the signal to be measured includes: vibration acceleration signals, gravitational signals, electrical signals, magnetic signals.

8. The method of claim 5, wherein the step five:

firstly, preparing a laser light source, dividing a laser beam into two beams by using a BS, wherein one beam is used as reference light, and the other beam is used as detection light when being beaten on a suspended object; collecting reference light and detection light by using a lens to interfere the reference light and the detection light, and detecting the optical power after interference by using a four-quadrant photoelectric detector; analyzing the change of detection voltage of the photoelectric detector caused by the change of detection laser power to obtain the motion of a suspended object:

ΔX= ζΔV

in the above formula, V is a detection voltage, the change of the detection voltage is DeltaV, the displacement of the suspended object is DeltaX, zeta is a volt meter coefficient, the value of the DeltaV is obtained through thermal noise calibration, and an applied signal to be detected is obtained through demodulation after the displacement of the suspended object is obtained.

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