Electromagnetic seismic pull testing machine and seismic method

Abstract

The application discloses an electromagnetic anti-vibration drawing testing machine and an anti-vibration method. The drawing testing machine comprises a machine table, an oil cylinder, a sliding table, an upper clamping jaw, a lower clamping jaw, a first coil, a second coil and a reverse current control module. A permanent magnet is arranged in the piston rod of the oil cylinder. When the steel bar is pulled off, the piston rod is impacted and vibrates, and the piston rod moves axially in the second coil. The second coil cuts the magnetic induction lines and generates induced current. The induced current can be used as an indirect index of the impact force. The first coil is electrified to generate corresponding reverse amperes, so that the anti-vibration can be achieved instantaneously, and the piston rod will not vibrate reversely due to excessive reverse force. The reverse current control module can monitor the current value in the second coil in real time, and change the reverse current required by the first coil according to the latest detected instantaneous maximum current value, so as to form a closed loop of "vibration detection-force feedback-dynamic adjustment".

Description

Technical Field

[0001] This application relates to the technical field of anti-vibration systems for drawing machines, and in particular to an electromagnetic anti-vibration drawing test machine and an anti-vibration method. Background Technology

[0002] In fields such as construction and metal processing, pull-out testing machines are commonly used to test the performance of workpieces such as reinforcing bars by pulling them out. When a pull-out testing machine pulls out a reinforcing bar, it generates a huge instantaneous impact force, causing the entire machine to vibrate violently.

[0003] Current technologies primarily rely on springs for shock absorption. Springs depend on the deformation of their elastic structure to dissipate impact force. However, as the spring gradually attenuates vibrational energy through continuous deformation, the equipment remains in a state of vibration with decreasing amplitude for an extended period, requiring considerable time to stabilize. Furthermore, the elastic vibration characteristics of springs can easily induce resonance in the equipment, further aggravating the vibration amplitude and prolonging the duration of vibration, thus affecting equipment accuracy, shortening its lifespan, and even posing safety hazards. In addition, single-spring shock-absorbing structures absorb energy solely through mechanical deformation and cannot actively counteract impact force, especially under high-frequency or high-load impacts, resulting in insufficient shock-absorbing efficiency. Summary of the Invention

[0004] The purpose of this application is to overcome the shortcomings of the existing technology and provide an electromagnetic anti-vibration pull-out testing machine and an anti-vibration method.

[0005] This application provides an electromagnetic shock pull-out testing machine, comprising: a machine base; a hydraulic cylinder fixedly mounted on the machine base, the piston rod of the hydraulic cylinder housing a permanent magnet; a slide table connected to the piston rod of the hydraulic cylinder; an upper clamping jaw disposed on the slide table; a lower clamping jaw disposed on the machine base, located below the upper clamping jaw and opposite to it, the upper and lower clamping jaws capable of clamping a reinforcing bar; a first coil and a second coil, both wound around the outside of the hydraulic cylinder, and the first and second coils being vertically spaced apart; during operation, the upper and lower clamping jaws clamp the reinforcing bar, and the hydraulic cylinder drives the slide table to rise to pull out the reinforcing bar; when the reinforcing bar is broken, the piston rod of the hydraulic cylinder vibrates under impact force, and the piston rod... The second coil moves axially, cutting magnetic field lines and generating induced current. The electromagnetic shock pull-out tester also includes a reverse current control module. The reverse current control module is used to detect the instantaneous maximum current generated by the piston rod vibration of the second coil when the steel bar is pulled out, and supplies reverse current to the first coil, so that the first coil generates a reverse Ampere force to counteract the vibration of the piston rod. Under the action of the reverse Ampere force, the amplitude and speed of the piston rod decrease, and the instantaneous maximum current value in the second coil decreases. The reverse current control module can also dynamically adjust the reverse current value according to the subsequently detected instantaneous maximum current value to match the continuously decaying impact force.

[0006] Furthermore, the piston rod of the hydraulic cylinder includes: a magnetic core shaft made of a soft magnetic alloy; a composite magnetic ring composed of alternating neodymium iron boron magnetic rings and soft magnetic rings along the axial direction, with the magnetic core shaft and the inner hole of the composite magnetic rings interference-fitted to form a closed magnetic circuit; and an alloy sleeve in which the composite magnetic rings are interference-fitted.

[0007] Furthermore, the neodymium iron boron magnetic rings are radially magnetized, and the radial magnetization directions of any two adjacent neodymium iron boron magnetic rings are opposite, which makes the intensity of the axial magnetic field fluctuate periodically. A soft magnetic ring is provided between any two adjacent neodymium iron boron magnetic rings. The soft magnetic ring can guide the radial magnetic field lines to the axial direction, so that the magnetic fields of adjacent neodymium iron boron magnetic rings are superimposed in the axial direction, thereby enhancing the magnetic field gradient.

[0008] Furthermore, a high-permeability potting compound is used between the NdFeB magnetic ring and the soft magnetic ring to avoid the presence of an air gap that would increase magnetic reluctance; and / or, the NdFeB magnetic ring is magnetized at a 45° angle, in conjunction with a magnetic core shaft, so that the angle between the radial magnetic field component and the axial magnetic field of the first coil is close to 90°, thereby maximizing the reverse Ampere force; and / or, the coaxiality error between the NdFeB magnetic ring and the soft magnetic ring is ≤0.02mm to prevent magnetic field eccentricity from causing fluctuations in the induced current.

[0009] Furthermore, the first coil and / or the second coil are wound around the cylinder body of the hydraulic cylinder; the cylinder body is made of non-magnetic material; the outer wall of the cylinder body is provided with a soft magnetic shielding layer, which can reduce magnetic resistance and enhance the penetration efficiency of the magnetic field; the radial inner side of the first coil and the second coil is no more than 5 cm away from the piston rod of the hydraulic cylinder.

[0010] Furthermore, the hydraulic fluid in the cylinder is a phenyl silicone oil-based hydraulic oil, which also contains nano-silica sol and graphene nanosheets. The content of nano-silica sol is 0.5-1%. When the piston rod of the cylinder is subjected to impact vibration, the particles of nano-silica sol can instantly form a chain structure, increasing the viscosity of the oil and generating damping force to suppress vibration. The content of graphene nanosheets is 1-2%. The addition of graphene nanosheets can improve the thermal conductivity of the oil.

[0011] Furthermore, the reverse current control module includes: a control system; a current detection circuit, in which a second coil is located, and the current detection circuit also includes a current transformer, a signal conditioning module for filtering, amplification, and peak detection, and an analog-to-digital converter. The signal conditioning module can capture the current generated in the second coil in real time and feed it back to the control system to achieve peak identification; a power drive circuit, in which a first coil is located, and the power drive circuit also includes a power supply, a power bridge drive module, and a Hall current sensor. After the control system calculates the reverse current value, it supplies reverse current to the first coil through the power supply and the power bridge drive module, causing the first coil to generate a reverse Ampere force matching the impact force. The Hall current sensor can monitor the current in the first coil in real time, forming a closed-loop control. When the rebar is pulled out, the signal conditioning module captures the instantaneous maximum current generated in the second coil. The control system can calculate the required reverse current value based on the instantaneous maximum current value. The power bridge drive module outputs reverse current to the first coil. Under the action of the reverse Ampere force, the amplitude of the piston rod of the hydraulic cylinder is attenuated. The reverse current control module can adjust the output reverse current in real time until the vibration stops.

[0012] Furthermore, the current detection circuit is also equipped with an energy storage capacitor, which is used to store the current generated by the second coil; the reverse current control module also includes a DC-DC conversion circuit, which can convert the current stored in the energy storage capacitor into the voltage required for the first coil to work, thereby enabling the second coil to supply power to the first coil; when the power generation of the second coil is insufficient, the control system can switch the power supply mode and supply power to the first coil from the power supply.

[0013] Furthermore, the electromagnetic anti-vibration pull-out testing machine also includes a third coil, which is located above the slide table; an extension rod is provided on the slide table; when the steel bar is pulled out, the piston rod of the hydraulic cylinder is subjected to an impact force and jumps upward first, the second coil generates an induced current, the extension rod is inserted into the third coil, and the reverse current control module supplies a reverse current to the third coil, so that the third coil generates a downward Ampere force, thereby hindering the upward movement of the extension rod.

[0014] This application also provides a seismic resistance method, implemented using the aforementioned electromagnetic seismic pull-out testing machine, comprising the following steps: At the instant the rebar is pulled out, the second coil generates an induced current; the reverse current control module supplies a reverse current to the third coil based on the first instantaneous maximum current value generated by the second coil, thereby suppressing the upward movement of the piston rod of the hydraulic cylinder through the third coil; as the piston rod falls back, the second coil generates an induced current in the opposite direction; the reverse current control module supplies a reverse current to the first coil based on the second instantaneous maximum current value generated by the second coil, thereby slowing down the falling speed of the piston rod through the first coil; as the falling speed of the piston rod slows down and the amplitude decreases, the instantaneous maximum current value measured again decreases, and the required reverse current value supplied decreases accordingly; the vibration of the piston rod continuously decays until it returns to calm.

[0015] This application provides an electromagnetic shock pull-out testing machine, including a machine base, a hydraulic cylinder, a slide table, an upper gripper, a lower gripper, a first coil, a second coil, and a reverse current control module. The piston rod of the hydraulic cylinder has a built-in permanent magnet. When the steel bar is pulled out, the piston rod vibrates under the impact force, and the piston rod moves axially within the second coil. The second coil cuts the magnetic field lines and generates an induced current. The induced current can be used as an indirect indicator of the impact force. By energizing the first coil, a corresponding reverse Ampere force is generated, which can provide instantaneous shock resistance without causing the piston rod to vibrate in the opposite direction due to excessive reverse force. The reverse current control module can monitor the current value in the second coil in real time, and then change the required reverse current of the first coil according to the latest detected instantaneous maximum current value, forming a closed loop of "vibration detection - force feedback - dynamic adjustment". The electromagnetic seismic pull-out testing machine provided in this application effectively solves the core problem of traditional spring-based seismic resistance by dynamically controlling electromagnetic induction and reverse Ampere force. Compared to the shortcomings of springs, which rely on elastic deformation to passively absorb energy and cause prolonged equipment vibration, this structure generates an induced current through the second coil when the rebar is pulled out, triggering the first coil to generate a reverse Ampere force, actively counteracting the vibration of the piston rod. This effectively shortens the amplitude decay time and accelerates the stabilization speed of the entire machine. Addressing the issue of spring elastic vibration easily causing resonance and exacerbating vibration amplitude, electromagnetic seismic resistance dynamically adjusts the reverse current value in real time, ensuring precise matching between the reverse Ampere force and the impact force, avoiding resonance, effectively reducing vibration amplitude, and ensuring the testing accuracy of the equipment. Furthermore, through closed-loop control, the reverse force is continuously and dynamically adjusted according to the instantaneous maximum current value, effectively suppressing vibration under different impact loads, reducing component loosening caused by long-term vibration, and extending the service life of the equipment. The electromagnetic seismic pull-out testing machine provided in this application overcomes the shortcomings of traditional springs in actively counteracting high-frequency or high-load impacts, and solves the problems of high energy consumption and poor adaptability of traditional seismic structures.

[0016] This application also provides a seismic resistance method, implemented using the aforementioned electromagnetic seismic pull-out testing machine. The reverse current control module dynamically adjusts the reverse current by sampling the current value in real time, forming a closed-loop control chain of "vibration detection - reverse force generation - energy dissipation". Electromagnetic seismic resistance can match the reverse Ampere force to the actual impact force and continuously adjust the reverse Ampere force according to the changes in the impact force, accurately resisting impact vibration, thereby improving the attenuation rate, reducing the amplitude of machine vibration, shortening the seismic resistance time, and improving the stability of the testing machine equipment. Attached Figure Description

[0017] Figure 1 This application provides a structural schematic diagram of an electromagnetic shock pull-out testing machine. Figure 2 for Figure 1 The diagram shown is a structural schematic of the electromagnetic shock pull-out testing machine with the machine base shell omitted. Figure 3 for Figure 2 The diagram shows a structural schematic of the electromagnetic shock pull-out tester from another angle. Detailed Implementation

[0018] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0019] This application provides an electromagnetic shock pull-out testing machine, including: a machine base 1; a hydraulic cylinder 2, fixedly mounted on the machine base 1, with a permanent magnet built into the piston rod of the hydraulic cylinder 2; a slide table 3, connected to the piston rod of the hydraulic cylinder 2; an upper clamping jaw 4a, mounted on the slide table 3; and a lower clamping jaw 4b, mounted on the machine base 1, located below the upper clamping jaw 4a and opposite to it, wherein the upper clamping jaw 4a and the lower clamping jaw 4b can cooperate to clamp the reinforcing bar.

[0020] For details, please refer to Figure 1 In the illustrated embodiment, the machine base 1 is frame-shaped and serves as a horizontal support base. The machine base 1 is typically made of cast iron or steel, with a smooth surface and sufficient rigidity. The machine base 1 is fixed to the ground or a work platform, serving as the foundation support for the entire machine. The machine base 1 is hollow inside, with the cylinder body of the hydraulic cylinder 2 and the lower gripper 4b housed within it. The machine base 1 also serves to conceal and protect components.

[0021] The hydraulic cylinder 2 consists of a cylinder body and a piston rod, with a permanent magnet installed inside the piston rod. The top of the piston rod is rigidly connected to the slide table 3. During operation, the piston rod is driven by hydraulic oil, which in turn moves the slide table 3 up and down. Figure 1 In the embodiment shown, the machine base 1 is equipped with two sets of hydraulic cylinders 2. The two sets of hydraulic cylinders 2 work together with the top support slide 3 to ensure load capacity and stability.

[0022] To ensure the accuracy of the lifting and lowering of the slide table 3, a guide rod 6 is also provided on the machine base 1. The guide rod 6 extends vertically, and the slide table 3 is fitted on the guide rod 6 and can slide along the guide rod 6. Figure 1 In the embodiment shown, the machine base 1 is provided with four sets of guide rods 6. The four sets of guide rods 6 are distributed along the four corners of the rectangle and can cooperate with the limiting slide 3 to ensure the accuracy, reliability and balance of the slide 3 movement.

[0023] The upper jaw 4a and lower jaw 4b are toothed clamping components. The upper jaw 4a is fixed to the slide table 3, and the lower jaw 4b is fixed to the machine base 1. The upper and lower jaws are arranged opposite each other and are coaxially aligned in the vertical direction. The distance between them can change with the movement of the slide table 3. During operation, the upper and lower jaws can cooperate to clamp the steel bar to be pulled by hydraulic or mechanical clamping drive, fixing the steel bar between them to form a pulling station.

[0024] In one embodiment, during the test, the reinforcing bar is placed vertically between the upper jaw 4a and the lower jaw 4b, which clamp and fix the reinforcing bar. The hydraulic system in the cylinder 2 is activated, pushing the piston rod upward, which in turn causes the slide 3 and the upper jaw 4a to rise synchronously, applying a continuous pull-out force to the reinforcing bar. When the pull-out force exceeds the tensile strength of the reinforcing bar, the reinforcing bar is broken, and the test ends. By simulating the tensile load under actual working conditions, the tensile strength, yield strength, and other mechanical properties of the reinforcing bar can be tested, providing data support for the quality assessment of building materials.

[0025] As is easily understood, the moment the steel bar is pulled out, the tension on the piston rod of cylinder 2 decreases sharply. The thrust and inertial force of the hydraulic system create an instantaneous impact, causing the piston rod to drive the slide 3 to bounce violently. At the same time, the elastic deformation caused by the broken steel bar releases energy, further aggravating the vibration of the entire machine, ultimately forming a damped oscillation dominated by the axial movement of the piston rod.

[0026] Traditional drawing machines mostly use spring-based anti-vibration structures, relying on the elastic deformation of springs to absorb vibration energy. However, springs have long vibration periods, and the equipment needs to vibrate continuously for a long time to stabilize. At the same time, the natural frequency of the spring is easily coupled with the impact frequency, causing resonance and increasing the vibration amplitude. In addition, a single mechanical structure cannot actively suppress the impact, especially in high-frequency or high-load tests, where the vibration attenuation efficiency is low. This not only affects the accuracy of subsequent tests but also causes equipment parts to loosen and shorten their lifespan due to long-term vibration.

[0027] To improve the seismic resistance, the electromagnetic seismic pull-out tester provided in this application also includes a first coil 11 and a second coil 12, both of which are wound around the outside of the oil cylinder 2, and the first coil 11 and the second coil 12 are arranged vertically at intervals.

[0028] During operation, the upper jaw 4a and lower jaw 4b clamp the reinforcing bar, and the hydraulic cylinder 2 drives the slide table 3 to rise to pull the reinforcing bar. When the reinforcing bar is pulled out, the piston rod of the hydraulic cylinder 2 vibrates due to the impact force, and the piston rod moves axially within the second coil 12. The second coil 12 cuts the magnetic field lines and generates an induced current. The electromagnetic anti-vibration pull-out tester also includes a reverse current control module. The reverse current control module is used to detect the instantaneous maximum current generated by the piston rod vibration in the second coil 12 when the reinforcing bar is pulled out, and supplies a reverse current to the first coil 11, so that the first coil 11 generates a reverse Ampere force to counteract the vibration of the piston rod. Under the action of the reverse Ampere force, the amplitude and speed of the piston rod decrease, and the instantaneous maximum current value in the second coil 12 decreases. The reverse current control module can also dynamically adjust the reverse current value according to the subsequently detected instantaneous maximum current value to match the continuously decaying impact force.

[0029] For details, please refer to Figures 1 to 3 In the illustrated embodiment, both the first coil 11 and the second coil 12 are made of enameled copper wire. The first coil 11 is wound around the outside of the cylinder of the oil cylinder 2, and the second coil 12 is wound around the piston rod protruding from the outside of the cylinder (in other embodiments, the first coil 11 can be wound around the outside of the piston rod, and the second coil 12 can be wound around the outside of the cylinder, as long as the coils can cooperate with the piston rod to work). The two are spaced apart to prevent the magnetic fields from interfering with each other.

[0030] Specifically, the first coil 11 has more turns (e.g., 600-900 turns) and a thicker wire diameter (AWG16); the second coil 12 has fewer turns (e.g., 200-300 turns) and a thinner wire diameter (AWG18); the two sets of coils are arranged vertically at intervals, with the first coil 11 located above the second coil 12, the axial distance between them is 10-20mm, and the radial inner gap between the first coil 11 and the piston rod is ≤5cm.

[0031] More specifically, the cylinder body of the hydraulic cylinder 2 is made of non-magnetic material (such as aluminum alloy), and the outer wall is covered with a soft magnetic shielding layer (such as silicon steel sheet); the piston rod has a built-in permanent magnet, which can move up and down along the axis of the hydraulic cylinder 2, and the range of motion of the piston rod covers the axial area of ​​the second coil 12 and the first coil 11.

[0032] More specifically, the reverse current control module includes a DSP controller, a current detection circuit, a power drive circuit, etc., and is integrated into the control cabinet of machine 1. The reverse current control module is connected to the first coil 11 and the second coil 12 via cables, and can receive current signals and output control commands in real time.

[0033] In one embodiment, the hydraulic cylinder 2 drives the slide 3 to rise, and the upper and lower grippers pull the reinforcing bar. When the reinforcing bar breaks, the piston rod vibrates due to the impact, causing the built-in permanent magnet to move axially within the second coil 12. The radial magnetic field of the permanent magnet cuts the wires of the second coil 12. According to the law of electromagnetic induction, the second coil 12 generates an induced electromotive force and current, the magnitude of which is proportional to the vibration speed. The reverse current control module detects the instantaneous maximum current of the second coil 12, calculates the reverse current value, and energizes the first coil 11. The first coil 11 generates an axial magnetic field, which, according to the Ampere force principle, generates an Ampere force opposite to the vibration direction, thereby suppressing the piston rod vibration.

[0034] It needs to be explained that when the piston rod moves and the magnetic field lines are cut, the induced electromotive force E generated by the second coil 12 is E=N2·B·L2·v, where N2 is the number of turns of the second coil 12 (a fixed value), B is the magnetic field strength of the permanent magnet inside the piston rod (a fixed value), L2 is the effective length of the second coil 12 (when the piston rod moves in the second coil 12, the effective length L of the second coil 12 that generates the induced current refers to the length of the conductor that is perpendicular to the direction of the magnetic field and cuts the magnetic field lines. Specifically, in the structure of the cylindrical piston rod and the coil, L is the coverage length of the coil in the axial direction of the piston rod, that is, the vertical direction, and L is also a fixed value), and v is the speed of the piston rod.

[0035] The induced current I2 = R2 / E, where R2 is the resistance (fixed value) of the second coil 12. I2 can be detected by the reverse current control module, allowing for the calculation of v.

[0036] According to the momentum theorem F·Δt=m·Δv, the impact force F is directly proportional to the rate of change of the piston rod velocity. Therefore, when the impact force is large, v increases, leading to an increase in I2. Thus, I2 can be used as an indirect indicator of the impact force.

[0037] Impact force F of the piston rod 冲击 =B·I2·L2·N2.

[0038] The first coil 11 is energized to generate a magnetic field, which in turn applies a force to the piston rod that is opposite to the direction of vibration.

[0039] F 反 =B1·I1·L1·N1=F 冲击 Where B1 is the magnetic field strength of the first coil 11, L1 is the effective length of the first coil 11, and N1 is the number of turns of the first coil 11. For the first coil 11, its magnetic field strength B1 is proportional to its ampere-turns (B1=μ·N1·(L1 / I1), where μ is the permeability), and the ratio can be calibrated in advance through testing. Therefore, in actual use, B1 can be simplified to a value that is in a fixed proportional relationship with I1, and the calculated F 冲击Then, I1 can be calculated by reverse calculation. I1 is the reverse current value required by the first coil 11.

[0040] By energizing the first coil 11, a corresponding reverse Ampere force is generated, which can provide instantaneous shock resistance without causing the piston rod to vibrate in the opposite direction due to excessive reverse force. After one shock resistance, the vibration of the piston rod attenuates, the amplitude decreases, and the vibration velocity slows down. At this time, the induced current generated by the second coil 12 will decrease. The reverse current control module can monitor the current value in the second coil 12 in real time, and then change the required reverse current of the first coil 11 according to the latest detected instantaneous maximum current value, forming a closed loop of "vibration detection - force feedback - dynamic adjustment".

[0041] The electromagnetic seismic pull-out testing machine provided in this application effectively solves the core problem of traditional spring-based seismic resistance by dynamically controlling electromagnetic induction and reverse Ampere force. Compared to the shortcomings of springs, which rely on elastic deformation to passively absorb energy and cause prolonged equipment vibration, this structure generates an induced current through the second coil 12 when the steel bar is pulled out, triggering the first coil 11 to generate a reverse Ampere force, actively counteracting the vibration of the piston rod. This effectively shortens the amplitude decay time and accelerates the stabilization speed of the entire machine. Addressing the issue of spring elastic vibration easily causing resonance and exacerbating vibration amplitude, electromagnetic seismic resistance dynamically adjusts the reverse current value in real time, ensuring precise matching between the reverse Ampere force and the impact force, avoiding resonance, effectively reducing vibration amplitude, and ensuring the testing accuracy of the equipment. Furthermore, through closed-loop control, the reverse force is continuously and dynamically adjusted according to the instantaneous maximum current value, effectively suppressing vibration under different impact loads, reducing component loosening caused by long-term vibration, and extending the service life of the equipment. The electromagnetic seismic pull-out testing machine provided in this application overcomes the shortcomings of traditional springs in actively counteracting high-frequency or high-load impacts, and solves the problems of high energy consumption and poor adaptability of traditional seismic structures.

[0042] In one specific embodiment, the piston rod of the hydraulic cylinder 2 includes: a magnetic core shaft made of a soft magnetic alloy; a composite magnetic ring composed of neodymium iron boron magnetic rings and soft magnetic rings arranged alternately along the axial direction, with the magnetic core shaft and the inner hole of the composite magnetic rings interference-fitted to form a closed magnetic circuit to reduce magnetic field leakage; and an alloy outer sleeve made of alloy structural steel, with the composite magnetic rings interference-fitted into the alloy outer sleeve.

[0043] The magnetic core is made of soft magnetic alloy. Soft magnetic alloy has high permeability, which can effectively guide magnetic lines of force.

[0044] Neodymium iron boron (NdFeB) magnetic rings generate strong magnetic fields as permanent magnets; soft magnetic rings are located between adjacent NdFeB magnetic rings and can guide radial magnetic lines of force to the axial direction, so that the magnetic fields of adjacent NdFeB magnetic rings are superimposed in the axial direction, thereby enhancing the magnetic field gradient.

[0045] The magnetic core shaft and the inner hole of the composite magnetic ring are connected by an interference fit, forming a closed magnetic circuit. The closed magnetic circuit formed by the interference fit can reduce magnetic field leakage and concentrate magnetic field energy. This not only helps to improve the efficiency of generating induced current when the second coil 12 cuts magnetic field lines, but also increases the reverse Ampere force generated by the first coil 11 under the action of the magnetic field, thus more effectively resisting piston rod vibration.

[0046] The alloy jacket is made of alloy structural steel, possessing high strength and rigidity. The composite magnetic ring consists of alternating neodymium iron boron magnetic rings and soft magnetic rings arranged axially, and is integrally interference-fitted into the alloy jacket. The alloy jacket provides mechanical support and protection for the composite magnetic ring. The interference fit, which secures the composite magnetic ring, also ensures structural stability and prevents deformation of the piston rod when subjected to the impact force of pulling out reinforcing bars.

[0047] In one specific embodiment, the magnetic core shaft is made of 1J50 soft magnetic alloy (permeability μ≥8000, saturation magnetic induction B_s≥1.5T), with a density of 7.6 g / cm³. The magnetic core shaft has a diameter of 40 mm, a length of 300 mm, a cylindricity error ≤0.01 mm, and a surface roughness Ra≤0.8 μm. During manufacturing, the formed magnetic core shaft undergoes vacuum annealing at 850℃ (holding for 2 hours) to eliminate processing stress and improve permeability. The surface of the magnetic core shaft is electroplated with nickel-phosphorus alloy (thickness 10-15 μm) to enhance corrosion resistance and reduce the coefficient of friction with the inner hole of the composite magnetic ring. The interference fit between the outer diameter of the magnetic core shaft and the inner hole of the composite magnetic ring is 0.03-0.05 mm, and assembly is performed using a thermal fitting method (the composite magnetic ring is heated to 200℃, and the magnetic core shaft is cooled to -40℃, utilizing the gap generated by thermal expansion and contraction for assembly). In addition, an axial positioning groove (5mm wide and 2mm deep) is machined on the outer surface of the magnetic core shaft, and a positioning boss is machined on the inner wall of the inner hole of the composite magnetic ring. The positioning boss corresponds one-to-one with the axial positioning groove to ensure that the axial position accuracy of the neodymium iron boron magnetic ring and the soft magnetic ring is ≤0.1mm.

[0048] In one specific embodiment, the NdFeB magnetic ring is made of N52 NdFeB (remanence Br=1.43T, coercivity Hc=1080kA / m), with dimensions of 60mm×25mm×25mm (outer diameter×inner diameter×axial length). The NdFeB magnetic ring is radially magnetized, with adjacent NdFeB magnetic rings having opposite magnetization directions (N pole facing outward, S pole facing outward alternately). The NdFeB magnetic ring is cut with diamond wire (0.3mm wire diameter), with a dimensional tolerance of ±0.02mm and a surface roughness Ra≤1.6μm. A pulse magnetization device (magnetic field strength 2.5T) is used for radial magnetization to ensure that the magnetization direction consistency error is ≤1°.

[0049] The soft magnetic ring is made of DT4C electrical pure iron (magnetic permeability μ≥3000) and has dimensions of 60mm×40.1mm×10mm (outer diameter×inner diameter×axial length). In this configuration, the NdFeB magnetic ring and the soft magnetic ring are arranged in a 25mm+10mm periodic pattern along the axial direction of the composite magnetic ring. During manufacturing, the formed soft magnetic ring undergoes annealing at 650℃ (holding for 1 hour) to eliminate work hardening and restore its soft magnetic properties. The surface of the soft magnetic ring is plated with copper (5μm thickness) to prevent oxidation and improve adhesion to the potting compound.

[0050] In this embodiment, the axial arrangement of the composite magnetic rings is alternating between "neodymium iron boron magnetic ring → soft magnetic ring → neodymium iron boron magnetic ring → soft magnetic ring", with a total of 8 groups and a total length of 35mm × 8 = 280mm.

[0051] Optionally, a high-permeability potting compound (iron-silicon-aluminum powder + epoxy resin, magnetic permeability μ≥100) is filled between the neodymium iron boron magnetic ring and the soft magnetic ring. The two are vacuum potted (vacuum degree ≤10Pa) and cured at 80℃ for 2 hours to eliminate air gaps and reduce magnetic resistance.

[0052] In one specific embodiment, the alloy jacket is made of 42CrMo alloy structural steel (tensile strength σ_b≥1080MPa, yield strength σ_s≥930MPa), with a density of 7.85g / cm³. The alloy jacket has an inner diameter of 60mm, an outer diameter of 80mm, a length of 300mm, a wall thickness of 10mm, and a straightness error ≤0.02mm / m. During manufacturing, the alloy jacket undergoes quenching and tempering treatment (860℃ quenching + 520℃ tempering) to achieve a hardness of 28-32HRC and improve overall mechanical properties; the alloy jacket surface is chrome-plated (20μm thick) to enhance wear resistance, and the surface roughness Ra≤0.4μm. During assembly, the alloy jacket is heated to 150℃, and the composite magnetic ring is press-fitted at room temperature (press-fitting force controlled at 5-8kN), with molybdenum disulfide lubricant applied to the mating surfaces to prevent scratches. In addition, the alloy jacket is machined with axial positioning rings (10mm wide and 2mm deep) at both ends, which are fixed to the end caps (45# steel) by bolts to prevent the composite magnetic ring from moving axially.

[0053] The coaxiality error of the magnetic core shaft, composite magnetic ring, and alloy jacket is ≤0.02mm; the perpendicularity error between the connecting surfaces at both ends and the axis is ≤0.01mm. Through material selection, precision manufacturing, and interference fit design, the synergistic optimization of magnetic circuit closure and mechanical strength is achieved, meeting the dual requirements of electromagnetic vibration resistance and pull-out testing.

[0054] Optionally, the neodymium iron boron magnetic rings are radially magnetized, and the radial magnetization directions of any two adjacent neodymium iron boron magnetic rings are opposite, so that the intensity of the axial magnetic field is periodically fluctuating; a soft magnetic ring is provided between any two adjacent neodymium iron boron magnetic rings, which can guide the radial magnetic field lines to the axial direction, so that the magnetic fields of adjacent neodymium iron boron magnetic rings are superimposed in the axial direction, thereby enhancing the magnetic field gradient.

[0055] Specifically, neodymium iron boron (NdFeB) magnetic rings and soft magnetic rings are arranged alternately along the piston rod axis, with adjacent NdFeB magnetic rings having opposite radial magnetization directions (e.g., the N pole of the previous NdFeB magnetic ring faces outwards, and the S pole of the next NdFeB magnetic ring faces outwards), forming a periodic magnetic pole distribution. The soft magnetic ring is sandwiched between the two NdFeB magnetic rings and is in close contact with them.

[0056] This allows adjacent NdFeB magnetic rings to be radially magnetized in opposite directions, creating alternating N and S poles in the axial direction. This results in a periodic fluctuation of "strong-weak-strong-weak" in the axial magnetic field strength. The soft magnetic ring (made of a high-permeability material) guides the outward-spreading radial magnetic lines of force from the NdFeB rings to the axial direction, causing the magnetic fields of adjacent NdFeB rings to superimpose in the axial direction, thus enhancing the gradient of magnetic field strength (i.e., the difference in magnetic field strength per unit length). With this increased magnetic field gradient, the rate of change of magnetic flux (ΔΦ / Δt) generated by the second coil 12 cutting the magnetic field lines during piston rod vibration increases. According to the law of electromagnetic induction, the intensity of the induced current generated in the coil increases accordingly, thereby improving the efficiency of the induced current and allowing for more accurate reflection of the impact force. Furthermore, under the enhanced magnetic field gradient, the current intensity of the first coil 11 can generate a larger reverse Ampere force, which is beneficial for power supply safety. In addition, the periodic fluctuation of the magnetic field gradient has a higher degree of matching with the vibration frequency, effectively suppressing vibrations at different amplitudes and reducing the risk of equipment resonance.

[0057] Optionally, the outer diameter of the composite magnetic ring and the inner diameter of the alloy jacket are designed with an interference of 0.03-0.08mm. The outer diameter of the composite magnetic ring is slightly larger than the inner diameter of the alloy jacket. The composite magnetic ring is pressed into the alloy jacket by a heat fitting method, and then the thermal expansion and contraction characteristics of the material are used to form a tight fit.

[0058] Optionally, the interference fit between the NdFeB magnetic ring and the soft magnetic ring is set to 0.02-0.03 mm (this interference fit refers to the fit tolerance between the outer diameter of the NdFeB magnetic ring and the inner diameter of the soft magnetic ring, i.e., the outer diameter of the NdFeB magnetic ring is 0.02-0.03 mm larger than the inner diameter of the soft magnetic ring). In this way, when assembling the NdFeB magnetic ring (a hard magnetic material, highly brittle) and the soft magnetic ring (a soft magnetic alloy or pure iron, with good toughness), the smaller interference fit can prevent the NdFeB magnetic ring from breaking due to stress concentration during press fitting. The interference fit ensures tight contact between the magnetic ring and the soft magnetic ring. Combined with high-permeability potting compound filling the microscopic gaps, it can also eliminate air gaps and prevent an increase in magnetic reluctance. This design ensures that the composite magnetic ring is axially stable and does not loosen within the alloy jacket, preventing magnetic ring displacement caused by vibration from affecting the magnetic field distribution. At the same time, reducing the air gap in the magnetic circuit lowers magnetic reluctance and also enhances the magnetic field strength.

[0059] Optionally, the composite magnetic ring is composed of alternating neodymium iron boron (NdFeB) magnetic rings and soft magnetic rings, with at least two magnetic groups consisting of NdFeB and soft magnetic rings. The thickness of the NdFeB magnetic rings is controlled at 20-30 mm, and the thickness of the soft magnetic rings is 10-15 mm. This arrangement allows the radially magnetized NdFeB magnetic rings to form alternating magnetic poles in the axial direction, and the soft magnetic rings then guide the radial magnetic lines of force to the axial direction to achieve magnetic field superposition, forming a periodically undulating axial magnetic field gradient.

[0060] Optionally, the soft magnetic material of the soft magnetic ring accounts for 30%-40% of the axial proportion. By interfering with the neodymium iron boron magnetic ring and filling it with high-permeability potting compound, the continuity of the magnetic circuit in the axial direction can be ensured. This proportion can effectively guide the radial magnetic lines of force of the neodymium iron boron magnetic ring to the axial direction, enhancing the magnetic field superposition effect, while avoiding the weakening of the magnetic field strength of the neodymium iron boron magnetic ring due to an excessively high proportion of soft magnetic material. This optimizes the axial magnetic field gradient while ensuring low magnetic reluctance and high energy utilization of the magnetic circuit, thereby improving the response speed and damping effect of the electromagnetic anti-vibration system.

[0061] Optionally, the neodymium iron boron magnetic ring and the soft magnetic ring are interference-fitted and filled with high-permeability potting compound to avoid the presence of air gaps that would increase magnetic resistance.

[0062] It should be explained that high-permeability magnetic potting compound is a composite material made by using a polymer matrix (such as epoxy resin, silicone rubber, etc.) as a filler and filling it with high-permeability powder (such as iron-silicon-aluminum, carbonyl iron powder, ferrite, etc.). High-permeability magnetic potting compound has good magnetic permeability and potting processability. It is mainly used to fill gaps in magnetic circuit systems, which can reduce the magnetic resistance generated by air gaps and improve the efficiency of magnetic field energy transfer.

[0063] In one specific embodiment, a low-viscosity epoxy resin (such as E-51) is selected as the matrix resin, with a post-curing shrinkage rate ≤0.1%, which helps ensure no cracking after potting. Simultaneously, the shear strength ≥15MPa facilitates reliable adhesion to the magnetic ring surface. Iron-silicon-aluminum powder with an average particle size of 5-10μm (magnetic permeability μ≥800) is added to the matrix resin, with the filler accounting for 60%-70% by weight. This filler is uniformly dispersed through ball milling to avoid agglomeration that would lead to uneven magnetic permeability. The filler also incorporates a silane coupling agent (such as KH-550) at a dosage of 1%-2% of the filler weight, which helps improve the compatibility between the filler and the resin and reduce interfacial magnetic resistance.

[0064] During potting, the surfaces of the NdFeB magnetic ring and the soft magnetic ring are first ultrasonically cleaned with anhydrous ethanol for 10 minutes to remove oil and oxides and improve the adhesion of the potting compound. Then, vacuum potting is performed by placing the composite magnetic ring into a vacuum chamber (vacuum degree ≤10Pa), injecting the prepared potting compound, maintaining the vacuum state for 30 minutes, and expelling air from the gaps to prevent air bubbles from forming air gaps. Finally, curing is performed using a stepped curing process, first holding at 60℃ for 2 hours, then raising the temperature to 80℃ for 4 hours. During the curing process, a pressure of 0.1MPa is applied to ensure that the potting compound fully fills the micro gaps.

[0065] After eliminating the air gap by using high-permeability potting compound, the magnetic circuit reluctance can be reduced by 40%-60%, which can effectively improve the magnetic field strength of the piston rod and make the peak current of the second coil 12 of the induction coil more linear with the impact force. At the same time, the hysteresis loss can be reduced by 15%-20%, avoiding magnetic field distortion caused by air gap magnetic saturation and ensuring the stability of the reverse Ampere force.

[0066] Furthermore, the potting compound, after curing, achieves a Shore D hardness of 70-80, providing rigid support for the magnetic ring and preventing displacement due to vibration. Simultaneously, the potting compound exhibits excellent temperature resistance, suitable for operating environments ranging from -40℃ to 120℃, and shows no cracking or peeling even after long-term use, effectively ensuring the reliability of the magnetic circuit structure.

[0067] Optionally, the neodymium iron boron magnetic ring is magnetized at a 45° angle, and in conjunction with the magnetic core shaft, the angle between the radial magnetic field component and the axial magnetic field of the first coil 11 is close to 90°, thereby maximizing the reverse Ampere force.

[0068] The formula for the reverse Ampere force is F=BILsinθ (θ is the angle between the magnetic field direction and the current direction). When θ=90°, sinθ=1, and the Ampere force is at its maximum. By tilting the neodymium iron boron magnetic ring at 45° for magnetization, the angle between its radial magnetic field component and the axial magnetic field of the first coil 11 is close to 90°, which can maximize the output of the Ampere force, thereby effectively counteracting piston rod vibration and improving seismic resistance.

[0069] To achieve 45° tilt magnetization, a custom-made V-shaped magnetization fixture is required. The fixture's tilt angle is machined to 45° ± 0.5° and made of industrial pure iron (DT4C) with a magnetic permeability μ ≥ 3000, effectively reducing magnetic reluctance loss during magnetization. The fit clearance between the fixture's inner groove and the NdFeB magnetic ring is ≤ 0.02 mm, ensuring that the magnetic ring's tilt angle deviation during magnetization is ≤ 1°. A pulse magnetizer (maximum magnetic field strength 2.5T) is used, with 2000 turns of the magnetization coil, and a 10kA pulse current (duration 5ms) is applied to generate a 45° tilt magnetization magnetic field. Before magnetization, a gaussmeter (accuracy ± 1%) is used to measure the magnetic field angle on the fixture surface, and the tilt angle of the magnetization coil is adjusted in real time to ensure that the magnetic ring's magnetization direction deviates from the design value by ≤ 2°.

[0070] A 45° tilt magnetization increases the coupling coefficient between the magnetic field and the coil, improving the energy utilization of the first coil 11 and generating a larger reverse force under the same current, thus effectively reducing energy consumption. Furthermore, tilt magnetization makes the magnetic field distribution more uniform; when the piston rod experiences radial displacement (≤0.5mm), the Ampere force fluctuation is ≤5%, which helps improve the stability of the seismic system.

[0071] Optionally, the coaxiality error between the neodymium iron boron magnetic ring and the soft magnetic ring is ≤0.02mm to prevent induced current fluctuations caused by magnetic field eccentricity.

[0072] It should be explained that the coaxiality deviation between the neodymium iron boron magnetic ring and the soft magnetic ring will cause the magnetic field to be eccentric, resulting in uneven distribution of the magnetic field lines cut by the second coil 12. This will cause the induced current to fluctuate periodically, which in turn will cause the reverse current control module to misjudge the magnitude of the impact force. Ultimately, the reverse Ampere force output by the first coil 11 will not match the actual requirements, affecting the seismic resistance.

[0073] If the coaxiality error exceeds 0.02mm, the magnetic field eccentricity will cause nonlinear distortion of the induced current in the second coil 12 when the piston rod vibrates, and the reverse Ampere force will be "overshoot" or "insufficient", which may aggravate the vibration of the piston rod or prolong the vibration decay time.

[0074] To achieve a coaxiality error ≤0.02mm, NdFeB magnetic rings and soft magnetic rings are machined using CNC grinding machines to ensure a coaxiality error between the inner and outer diameters ≤0.01mm and a surface roughness Ra ≤0.4μm. The interference fit tolerance between the inner hole of the soft magnetic ring and the magnetic core shaft is controlled within 0.02-0.03mm to ensure coaxiality transfer after assembly. The magnetic core shaft is precision ground using an external cylindrical grinding machine, with a cylindricity error ≤0.01mm / m and a coaxiality reference error between the outer diameter and the inner hole of the composite magnetic ring ≤0.01mm.

[0075] During assembly, a dedicated coaxiality positioning fixture is used, with the magnetic core shaft as the reference, and a three-jaw chuck (positioning accuracy ≤0.01mm) is used to fix the composite magnetic ring, ensuring that the coaxiality deviation between the inner hole of the composite magnetic ring and the magnetic core shaft is ≤0.01mm. A hydraulic press-fitting machine (pressure control accuracy ±0.5kN) is then used to press-fit the magnetic ring at a uniform speed along the axial direction (speed ≤0.1mm / s). The pressing force curve is monitored in real time to avoid localized stress concentration caused by eccentricity. After assembly, a laser coaxiality tester (accuracy 0.001mm) is used to select five sections evenly along the axial direction of the magnetic ring to check the coaxiality of the inner and outer diameters. Products exceeding the tolerance are reassembled or scrapped.

[0076] By controlling the coaxiality, the fluctuation amplitude of the induced current in the second coil 12 can be reduced, improving the linearity between the current peak and the impact force, thereby optimizing the judgment error of the reverse current control module. After coaxiality control, the deviation of the reverse Ampere force generated by the first coil 11 is reduced, which helps to improve the consistency of piston rod vibration decay, and the amplitude decay time fluctuation is smaller under the same test conditions. Even if the piston rod produces radial displacement during vibration, the uniform magnetic field distribution results in a small change in the induced current, ensuring that the anti-vibration system can still guarantee test accuracy and stable operation under complex working conditions.

[0077] In one embodiment, the first coil 11 and / or the second coil 12 are wound around the cylinder body of the hydraulic cylinder 2; the cylinder body is made of a non-magnetic material; a soft magnetic shielding layer is provided on the outer wall of the cylinder body, which can reduce magnetic resistance and enhance the penetration efficiency of the magnetic field.

[0078] For example, aluminum alloy can be used to manufacture cylinder blocks. The total density is 2.7 g / cm³, the magnetic permeability is close to that of a vacuum (μ≈1.0002), and the tensile strength is ≥260 MPa, making it suitable for machining cylinder block structures.

[0079] For example, the cylinder block can be made of stainless steel (such as 304). Stainless steel has a magnetic permeability μ≤1.05, strong corrosion resistance, and tensile strength ≥520MPa, making it suitable for humid or corrosive environments.

[0080] For example, the cylinder block can be made of engineering plastics (such as PEEK). Engineering plastics are non-magnetic and insulating, with a density of 1.3 g / cm³ and a temperature resistance of 260°C, but they have low mechanical strength (tensile strength ≈ 90 MPa) and need to be used in conjunction with a metal frame.

[0081] Traditional magnetic materials (such as cast iron) attract magnetic field lines, causing the magnetic field to concentrate in the cylinder body and fail to effectively penetrate to the coil area, thus weakening the induced current and reverse Ampere force. Using non-magnetic materials to construct the cylinder body can avoid magnetic field distortion.

[0082] Magnetic materials generate eddy current losses in alternating magnetic fields, while non-magnetic materials can reduce these losses, thereby reducing coil heating.

[0083] The soft magnetic shielding layer is a thin layer made of high magnetic permeability materials (such as silicon steel sheets or permalloy), with a thickness of 0.1-0.5 mm, used to guide magnetic lines of force and reduce magnetic resistance. For example, a soft magnetic shielding layer is made by stacking 3% silicon steel sheets (μ≈5000), with the stacking direction aligned with the magnetic field direction. The silicon steel sheets are cut to the outline shape of the outer wall of the cylinder 2, and are bonded to the outer wall of the cylinder using high magnetic permeability adhesive (such as iron-silicon-aluminum filled epoxy resin adhesive), with staggered stacking between layers (overlap rate ≥30%) to eliminate air gaps. The soft magnetic shielding layer is closed around the circumference of the cylinder 2, and the two ends are welded together using soft magnetic connectors (such as iron-nickel alloy) to form a complete magnetic circuit and prevent magnetic line leakage.

[0084] Adding a soft magnetic shielding layer can reduce magnetic resistance, improve magnetic field penetration efficiency, and increase the coupling coefficient between the first coil 11 and the piston rod magnetic field. The soft magnetic shielding layer can also guide the uniform distribution of magnetic field lines, reduce the radial magnetic field strength deviation of the coil, and ensure the stability of the induced current.

[0085] Optionally, the radial inner sides of the first coil 11 and the second coil 12 are no more than 5 cm apart from the piston rod of the oil cylinder 2.

[0086] According to the Biot-Savart law, the magnetic field strength is inversely proportional to the square of the distance. An excessively large gap (e.g., >5cm) will cause the magnetic field strength to attenuate, thus weakening the induced current and the reverse Ampere force. The smaller the gap, the shorter the delay in the transmission of magnetic field changes to the coil (a 5cm gap results in a delay of ≈0.17μs, meeting the response requirement of ≤1ms).

[0087] This ensures that the gap between the radial inner side of the coil and the piston rod is ≤5cm, the magnetic field strength attenuation in the coil area is ≤20%, and the peak value of the induced current can be maintained at over 90% of the design value. Furthermore, a reasonable interval can shorten the magnetic field transmission delay, resulting in a shorter response time for the reverse Ampere force, thus effectively suppressing the impact vibration of the piston rod.

[0088] Optionally, the oil in cylinder 2 is phenyl silicone oil-based hydraulic oil, and nano-silica sol and graphene nanosheets are also added to the oil; the content of nano-silica sol is 0.5-1%, and when the piston rod of cylinder 2 is subjected to impact vibration, the particles of nano-silica sol can instantly form a chain structure, increasing the viscosity of the oil and generating damping force to suppress vibration; the content of graphene nanosheets is 1-2%, and the addition of graphene nanosheets can improve the thermal conductivity of the oil.

[0089] Phenyl silicone oil has a viscosity index ≥300 (compared to approximately 150 for ordinary mineral oil). Within a temperature range of -50℃ to 200℃, its viscosity change rate is ≤50%, meaning it exhibits excellent viscosity-temperature characteristics and can withstand temperature fluctuations caused by piston rod vibration during pull-out tests. The vapor pressure of phenyl silicone oil is ≤10. -3Pa (25℃), does not easily evaporate at high temperatures, has a service life far exceeding that of ordinary mineral oil, and can reduce the maintenance cost of oil changes.

[0090] When the piston rod vibrates at high speed, the oil viscosity remains stable, which helps to stabilize the thrust fluctuation of cylinder 2 and avoid pull-out force errors caused by changes in oil viscosity. Phenyl silicone oil has a stable molecular chain structure and strong shear resistance. Under high-frequency shearing (such as vibration frequency of 50-100Hz), the viscosity decreases only slightly, which can effectively maintain the stability of the hydraulic system.

[0091] By adding nano-silica sol to the oil, the nano-silica sol (particle size 5-20nm) is uniformly dispersed in the oil under static conditions. When the piston rod is subjected to impact vibration (acceleration ≥5g), the particles instantaneously form a chain structure through hydrogen bonding (response time ≤1ms), causing the oil viscosity to surge from 50cSt to over 200cSt, generating a shear thickening effect that can form a damping force to suppress vibration. After the vibration decays, the chain structure automatically dissociates, the oil viscosity recovers, and it can repeatedly participate in the next vibration damping, avoiding the irreversible loss of traditional damping materials.

[0092] The reason for limiting the content of nano-silica sol to 0.5-1% is that when the concentration is insufficient (<0.5%), the number of particles is small, and the chain structure is not fully formed, resulting in insufficient viscosity increase and weak damping force, failing to produce the required vibration suppression effect. Conversely, when the concentration is too high (>1%), the probability of particle agglomeration increases, and the oil viscosity will abnormally increase when static, leading to increased resistance during normal operation of cylinder 2, easily causing pull-out force errors, and easily clogging the hydraulic oil circuit. At a content of 0.5-1%, the kinematic viscosity of the oil is maintained at 50-60 cSt, providing a certain degree of vibration damping effect without affecting the normal operation of the hydraulic system.

[0093] Adding graphene nanosheets (1-10 nm thick, 5-10 μm diameter) to the oil can form a thermally conductive network, increasing the thermal conductivity from 0.15 W / (m·K) of pure phenyl silicone oil to 0.3-0.4 W / (m·K). This helps to accelerate the dissipation of heat generated by piston rod vibration and friction, thus improving thermal conductivity and slowing down the rate of oil temperature rise. Furthermore, the graphene sheets can adhere to metal surfaces to form a lubricating film, thereby reducing the coefficient of friction between the piston rod and the oil / cylinder, decreasing wear on the piston rod and the inner wall of the cylinder, and extending the service life of the equipment.

[0094] The reason for limiting the graphene nanosheet content to 1-2% is that when the content is insufficient (<1%), the thermally conductive network is discontinuous, the improvement in thermal conductivity is insufficient, the oil temperature control effect is poor, and long-term operation can easily lead to oil oxidation and deterioration. On the other hand, when the content is too high (>2%), the graphene sheets stack and agglomerate, which will increase the oil viscosity, increase the energy consumption of the hydraulic system, and reduce the dispersion stability. The 1-2% content setting can effectively improve thermal conductivity, reduce the coefficient of friction, and reduce the increase in oil viscosity, thus balancing thermal conductivity and lubrication performance.

[0095] In one embodiment, the reverse current control module includes: a control system; a current detection circuit, in which a second coil 12 is disposed, and the current detection circuit also includes a current transformer, a signal conditioning module for filtering, amplification, and peak detection, and an analog-to-digital converter. The signal conditioning module can capture the current generated in the second coil 12 in real time and feed it back to the control system to achieve peak identification; and a power drive circuit, in which a first coil 11 is disposed, and the power drive circuit also includes a power supply, a power bridge drive module, and a Hall current sensor. After the control system calculates the reverse current value, it uses the power supply... The power bridge drive module supplies reverse current to the first coil 11, causing the first coil 11 to generate a reverse Ampere force that matches the impact force. The Hall current sensor can monitor the current in the first coil 11 in real time, forming a closed-loop control. When the steel bar is pulled out, the signal conditioning module captures the instantaneous maximum current generated in the second coil 12. The control system can calculate the required reverse current value based on the instantaneous maximum current value. The power bridge drive module outputs reverse current to the first coil 11. Under the action of the reverse Ampere force, the amplitude of the piston rod of the hydraulic cylinder 2 is attenuated. The reverse current control module can adjust the output reverse current in real time until the vibration stops.

[0096] Specifically, the second coil 12 is connected in series to the current detection circuit. When the piston rod vibrates and cuts the magnetic field lines, an induced current is generated in the second coil 12. The current transformer, based on the principle of electromagnetic induction, can convert a large current into a small current signal (conversion ratio 1000:1). After being filtered and amplified by the signal conditioning module (including an RC filter circuit, operational amplifier, and peak detection circuit), it is converted into a digital signal by an analog-to-digital converter (ADC, 12-bit resolution) for real-time feedback to the control system. The signal conditioning module can eliminate high-frequency noise through low-pass filtering (cutoff frequency 1kHz), ensuring that the peak detection circuit captures the instantaneous maximum current, thereby guaranteeing the accuracy of the impact force signal.

[0097] The control system (such as the DSP chip TMS320F28335) can receive digital current signals, calculate the required reverse current value through preset algorithms (such as peak identification algorithm and PID control algorithm), generate PWM control signals (frequency 20kHz), and send them to the power bridge drive module (such as IGBT full bridge circuit).

[0098] The power supply (such as a DC48V switching power supply) outputs reverse current to the first coil 11 through the power bridge drive module. The Hall current sensor (accuracy ±0.5%) monitors the current in the power drive circuit in real time and feeds it back to the control system, forming a closed-loop control link of "detection-calculation-drive-feedback".

[0099] The closed-loop control of the reverse current control module enables dynamic adjustment of the reverse current as vibration decays. By improving response speed and control accuracy, the delay from rebar breakage to reverse current output can be ≤5ms, and the current control accuracy can reach ±1%, while the matching error between reverse Ampere force and impact force can be ≤3%, thereby effectively shortening the amplitude decay time of the piston rod and improving seismic efficiency.

[0100] In one specific embodiment, the signal conditioning module includes a filtering module, an amplification module, and a peak detection circuit. The filtering module includes an RC low-pass filter (1kΩ resistor + 0.159μF capacitor) with a cutoff frequency of 1kHz, and a parallel TVS diode (12V breakdown voltage) to suppress surges. The filtering module can attenuate high-frequency noise (such as harmonics above 2kHz) generated by mechanical vibration and improve the signal-to-noise ratio, thereby ensuring the purity of the current signal. The amplification module uses an OPA2277 operational amplifier (10MHz bandwidth, 1.1nV / √Hz noise density), with a non-inverting amplification circuit and an input impedance ≥10MΩ. The amplification module can convert the weak current signal (0-0.5A) of the second coil 12 into a 0-5V voltage signal, meeting the ADC sampling range, with a signal distortion ≤0.1%. The peak detection circuit includes a precision rectifier bridge (AD8276) and a 0.1μF holding capacitor (leakage current ≤1nA), paired with a switching transistor (MOSFET IRF540) to achieve peak reset; the peak detection circuit can accurately capture the instantaneous maximum current, with a response time <1ms and a holding time ≥50ms, which can ensure that the control system accurately reads each impact peak with an error ≤0.5%.

[0101] In one specific embodiment, the analog-to-digital converter (ADC) employs a 16-bit ADC chip, ADS1115, with differential input mode, a sampling rate of 1kHz, a reference voltage of 4.096V, and a resolution of 0.122mV (corresponding to a current resolution of 0.061A). A 100Ω resistor and a 0.1μF capacitor are connected in series at the ADC front end to form a second-order filter, which suppresses sampling noise. The high-precision ADC sampling unit improves the reverse current control accuracy, ensuring a current quantization error ≤0.1A; for example, when the induced current decays from 10A to 1A, it can still accurately match a current change of 0.1A. Furthermore, the ADC supports current detection from -20A to +20A (via a polarity determination circuit), meeting the current sampling requirements of bidirectional vibration.

[0102] In one specific embodiment, the power bridge drive module adopts an IGBT full-bridge circuit (4 FF300R12ME4, withstand voltage 1200V, maximum current 300A), paired with a driver chip 2SC0435T, with a dead time set to 5μs to prevent shoot-through; the PWM frequency is 20kHz, the duty cycle is adjustable from 0-100%, and it supports fast switching of current direction (switching time ≤10μs).

[0103] Optionally, the power drive circuit also includes a comparator and a latch. When the Hall current sensor detects a current greater than a preset value, the latch triggers the power bridge drive module to shut down, with a response time of <1μs. This prevents the first coil 11 from burning out due to overcurrent (such as when the piston rod is stuck). The protection threshold can be finely adjusted using a potentiometer.

[0104] Optionally, the power supply drive circuit includes a temperature sensor and a fan. When the temperature sensor detects that the temperature of the first coil 11 is greater than a preset value, forced air cooling is activated.

[0105] Optionally, the power bridge drive module uses an aluminum heat sink and is equipped with an axial fan. When the temperature of the first coil 11 exceeds a preset value, the axial fan is activated. With the help of the 3mm thick aluminum heat sink, the junction temperature of the power bridge drive module can be controlled below 125℃ (safe operating range), thereby reducing the temperature of the coil and the power bridge drive module.

[0106] Optionally, the electromagnetic shock pull-out tester also includes a display screen for real-time display of the induced current waveform, reverse current value, and vibration attenuation curve.

[0107] Optionally, the electromagnetic vibration pull-out testing machine also includes status indicator lights. When the status indicator light is green, it indicates normal operation; when it is yellow, it indicates a warning; and when it is red, it indicates a fault.

[0108] Optionally, the electromagnetic shock pull-out tester also includes a buzzer for fault alarm.

[0109] With visual monitoring, operators can intuitively view the seismic resistance process, and it also supports historical data storage for easy analysis of vibration attenuation efficiency. During operation, when the vibration attenuation time exceeds the set value (e.g., >300ms), the system automatically issues an early warning, prompting equipment maintenance and effectively reducing downtime.

[0110] Optionally, the current detection circuit is also equipped with an energy storage capacitor, which is used to store the current generated by the second coil 12; the reverse current control module also includes a DC-DC conversion circuit, which can convert the current stored in the energy storage capacitor into the working voltage required for the first coil 11 to work, so that the second coil 12 can supply power to the first coil 11; when the power generation of the second coil 12 is insufficient, the control system can switch the power supply mode and supply power to the first coil 11 from the power supply.

[0111] The second coil 12 is connected in parallel with the energy storage capacitor via a rectifier bridge (such as GBPC3510). When the piston rod vibrates, the alternating current generated by the second coil 12 is rectified and can charge the energy storage capacitor, which (such as a 450V / 10mF electrolytic capacitor) can store electrical energy. According to the law of electromagnetic induction, the induced current generated by the second coil 12 is essentially the mechanical energy of the piston rod vibration converted into electrical energy. The energy storage capacitor stores this electrical energy as electric field energy, realizing the conversion chain of "vibration energy → electrical energy → magnetic field energy" to reduce the energy consumption of the external power supply.

[0112] The DC voltage output from the energy storage capacitor is connected to a DC-DC conversion circuit (such as the LM5175 chip), where it is converted into the operating voltage (such as 48V) required by the first coil 11. The power bridge driver module then supplies power to the first coil 11. The DC-DC conversion circuit adopts a synchronous rectification Buck-Boost topology. When the voltage of the energy storage capacitor (range 20-50V) is lower than the operating voltage, the circuit operates in Boost mode, boosting the voltage to the operating voltage; when the voltage is higher than the operating voltage, the circuit operates in Buck mode, stabilizing the output voltage.

[0113] The control system can monitor the voltage of the energy storage capacitor in real time. When the voltage is lower than the set threshold, it triggers the relay to switch to the external power supply to ensure that the first coil 11 continues to receive a stable power supply.

[0114] The dual power supply mode can avoid the interruption of reverse ampere force due to insufficient energy storage capacitor. For example, when performing continuous rapid pull-out tests (interval ≤ 1 minute), the automatic intervention of the external power supply can ensure that the shock resistance effect is consistent in each test cycle.

[0115] Optionally, several ferrite beads (100Ω / 100MHzD) are connected in series on the signal lines of the current detection circuit and / or power drive circuit, and ceramic capacitors (0.1μF) are connected in parallel across the two ends of the ferrite beads to form an LC filter network.

[0116] The ferrite bead has an impedance of ≥100Ω at 100MHz, which can effectively attenuate the switching noise generated by the power bridge drive module; the parallel capacitor can further reduce low-frequency noise (<1MHz), forming a wide-band anti-interference effect, thereby improving the signal-to-noise ratio of the current detection signal, reducing the detection error of the Hall current sensor, and avoiding reverse current false output caused by noise.

[0117] Optionally, a unidirectional TVS diode (15V) is connected in parallel across the positive and negative terminals of the energy storage capacitor. The clamping voltage of the TVS is ≤23V and the response time is ≤1ns.

[0118] When the voltage of the energy storage capacitor surges due to severe piston rod vibration (such as accidental overload), the TVS diode can quickly break down and conduct, clamping the voltage within a safe range and preventing damage to the input stage of the DC-DC converter due to overvoltage. The 1ns-level response time also suppresses high-frequency surges. Combined with the current-limiting characteristics of the energy storage capacitor, this forms dual protection, ensuring the reverse current control module can operate stably even in harsh power grid environments.

[0119] Optionally, the reverse current control module also includes LED indicators for real-time display of the device's vibration status; the energy storage capacitor can also power the LED indicators.

[0120] In one specific embodiment, the LED indicator uses a 5mm high-brightness red-green dual-color LED, connected in parallel across the energy storage capacitor via a current-limiting resistor (100Ω). The LED power consumption is no more than 0.1W, exhibiting low power consumption. The energy storage capacitor provides a stable DC power supply, eliminating the need for an external power source. When the piston rod vibrates, the voltage of the energy storage capacitor changes with the induced current. The LED indicator provides real-time feedback on the device's vibration status through different on / off states or colors (e.g., solid green indicates normal operation, flashing red indicates increased vibration).

[0121] Operators can quickly judge the vibration resistance of the equipment by the LED status. For example, when the steel bar is pulled out, the LED turns from green to red and flashes at a high frequency, indicating that the amplitude of the piston rod exceeds the threshold and the test parameters need to be adjusted.

[0122] Optionally, the reverse current control module also includes a buzzer for issuing an alarm in the event of an impact overload; the energy storage capacitor can also power the buzzer.

[0123] When the pulling impact exceeds the equipment's shock resistance (such as when the diameter of the steel bar exceeds the specification), the buzzer can sound an alarm to prevent damage to the piston rod or coil due to continuous and severe vibration.

[0124] In one specific embodiment, the buzzer is a 5V active buzzer, connected to an energy storage capacitor via a switching transistor. When the inrush current of the current detection circuit exceeds a threshold, the transistor is triggered to conduct, and the buzzer emits an alarm sound. The energy storage capacitor can maintain the buzzer alarm even when the power supply is interrupted, ensuring that an alarm can still be sounded when the equipment malfunctions, thus improving safety.

[0125] In one embodiment, the electromagnetic anti-vibration pull-out testing machine provided in this application further includes a third coil 13, which is disposed above the slide table 3; an extension rod 5 is on the slide table 3; when the reinforcing bar is pulled out, the piston rod of the oil cylinder 2 is subjected to an impact force and jumps upward first, the second coil 12 generates an induced current, the extension rod 5 is inserted into the third coil 13, and the reverse current control module supplies a reverse current to the third coil 13, so that the third coil 13 generates a downward Ampere force, thereby hindering the upward movement of the extension rod 5.

[0126] It should be explained that at the moment the steel bar is pulled out, the piston rod experiences a tremendous impact force, resulting in violent axial vibration. In one specific embodiment, refer to... Figures 1 to 3 The piston rod will first jump upwards rapidly (the initial amplitude can reach 5-10mm), and then fall back due to inertia. Under the action of the anti-seismic structure, it forms a reciprocating damped vibration.

[0127] By setting the third coil 13, when the piston rod jumps upward, the built-in permanent magnet moves axially within the second coil 12, cutting magnetic field lines to generate an induced current. The magnitude of the current is proportional to the vibration speed. This current can be stored by the energy storage capacitor and also fed back as a vibration signal to the reverse current control module. When the piston rod moves upward, the extension rod 5 on the slide 3 inserts into the third coil 13. The reverse current control module outputs a reverse current to the third coil 13 based on the instantaneous maximum current value of the second coil 12 (the method of obtaining the reverse current value and the method of supplying the reverse current are similar to those of the first coil 11, see above for details), causing it to generate a downward Ampere force, directly hindering the upward movement of the extension rod 5 and weakening the initial jumping amplitude of the piston rod.

[0128] When the piston rod falls back, the permanent magnet moves in the opposite direction within the second coil 12, generating an induced current in the opposite direction. The reverse current control module supplies a reverse current to the first coil 11 based on this current value, generating an upward reverse Ampere force, which slows down the falling speed of the piston rod, forming a closed-loop damping control of "upward jump suppression - downward fall buffer".

[0129] It should be added that, for the third coil 13, after suppressing the initial jump of the piston rod, it is not necessary to supply a reverse current value based on the amplitude decay (keeping the first reverse current value unchanged), or the reverse current value can be supplied based on the amplitude decay (changing synchronously with the first coil 11). Since the electromagnetic anti-vibration structure provided in this application can generate a reverse Ampere force adapted to the impact force through the first coil 11, during actual vibration reduction, if the reverse Ampere force is not greater than the impact force, the piston rod will not jump upwards again, but will gradually slow down its descent. Therefore, after suppressing the initial jump of the piston rod, the third coil 13 can be directly de-energized, further saving energy.

[0130] In summary, the third coil 13 can specifically suppress the initial amplitude impact, the first coil 11 can continuously attenuate subsequent vibrations, and the remaining energy can be dissipated through hydraulic oil damping. The combination of the three can effectively avoid the response lag caused by overload of a single coil.

[0131] This application also provides a seismic resistance method, implemented using the aforementioned electromagnetic seismic pull-out testing machine, characterized by comprising the following steps: At the moment the steel bar is pulled out, the second coil 12 generates an induced current. The reverse current control module supplies a reverse current to the third coil 13 based on the first instantaneous maximum current value generated by the second coil 12, and the third coil 13 inhibits the piston rod of the hydraulic cylinder 2 from moving upward. As the piston rod falls back, the second coil 12 generates an induced current in the opposite direction. The reverse current control module supplies a reverse current to the first coil 11 based on the second instantaneous maximum current value generated by the second coil 12, thereby slowing down the falling speed of the piston rod through the first coil 11. As the piston rod's falling speed decreases and its amplitude diminishes, the instantaneous maximum current value measured again decreases, and the required reverse current value decreases accordingly. The vibration of the piston rod gradually decreased until it returned to calm.

[0132] Specifically, when the reinforcing bar is broken, the piston rod of the hydraulic cylinder 2 jumps violently upward due to the impact force. The built-in permanent magnet moves axially within the second coil 12, cutting magnetic field lines and generating an induced current. The reverse current control module captures the first instantaneous maximum value of the induced current in real time and outputs a corresponding reverse current to the third coil 13, causing the third coil 13 to generate a downward Ampere force, which hinders the upward movement of the extension rod 5 on the slide table 3, thereby suppressing the initial upward jump of the piston rod.

[0133] After the piston rod jumps to its peak (rising speed is 0) and falls back, the permanent magnet passes through the second coil 12 in the opposite direction, generating an induced current in the opposite direction. The reverse current control module outputs a corresponding reverse current to the first coil 11 based on the peak value of this induced current, causing it to generate an upward Ampere force, which slows down the falling speed of the piston rod. The reverse Ampere force matches the damped vibration energy, preventing the piston rod from "bounced" due to overdamping.

[0134] After the first coil 11 completes the first shock absorption, the piston rod slows down, the induced current generated in the second coil 12 decreases, and the reverse current control module sends a second reverse current to the first coil 11 based on the peak value of the reduced induced current, further slowing down the falling speed of the piston rod.

[0135] By analogy, through reverse current vibration damping, the amplitude of the piston rod gradually decreases and the vibration speed becomes slower and slower. The peak value of the induced current of the second coil 12 decays synchronously. The reverse current control module can change the reverse current value of the input first coil 11 according to the change of the peak value of the induced current until the vibration energy is exhausted and the piston rod returns to calm.

[0136] The reverse current control module dynamically adjusts the reverse current by sampling the current value in real time, forming a closed-loop control chain of "vibration detection - reverse force generation - energy dissipation". Electromagnetic vibration damping can match the reverse Ampere force to the actual impact force and continuously adjust the reverse Ampere force according to the changes in the impact force, accurately resisting impact vibration, thereby improving the attenuation rate, reducing the amplitude of machine vibration, shortening the vibration damping time, and improving the stability of the testing equipment.

[0137] In one specific embodiment, a pull-out test was performed on a Φ20mm steel bar.

[0138] At the moment of disconnection (t=0ms), the piston rod is violently thrown upwards by the impact force, with an initial velocity of V1=0.6m / s and a jumping amplitude of A1=8mm.

[0139] The second coil 12 cuts the magnetic field lines of the permanent magnet, generating a positive induced current within the second coil 12, with an instantaneous maximum value I. a =10A.

[0140] Reverse current control module according to I a Output reverse current I to the third coil 13 3a =10A, generating a downward Ampere force F. 3a =60N, hindering the upward movement of extension rod 5.

[0141] The piston rod's upward jump amplitude was suppressed to A1'=5mm (a reduction of 37.5% compared to when it was not suppressed), and the upward jump speed was reduced to V1'=0.3m / s.

[0142] After the piston rod reaches the top of the jump, it falls back (t=50ms), with a falling speed of V2=0.4m / s and a falling amplitude of A2=5mm.

[0143] The second coil 12 cuts the magnetic field lines of the permanent magnet, generating a reverse induced current within the second coil 12, with an instantaneous maximum value I. b =6A.

[0144] Reverse current control module according to I b Output reverse current I to the first coil 11 1a =4.8A, generating an upward Ampere force F. 1a =30N, slowing down the rate of decline.

[0145] The piston rod's return speed decreased to V2'=0.2m / s, and the return amplitude decreased to A2'=3mm.

[0146] Peak induced current I in the second coil 12 c =3A.

[0147] Reverse current control module according to I c Output reverse current I to the first coil 11 1b =2.4A, Ampere force F 1b =15N, the drop amplitude further decreased to A3'=1.5mm.

[0148] The vibration amplitude of the piston rod continued to decrease, and the peak value of the induced current in the second coil 12 dropped to I. n <1A, the current output by the reverse current control module synchronously decreases to I<1A, and the ampere force is less than 10N.

[0149] Finally, at t=250ms, the piston rod amplitude decayed to A<0.5mm, which was considered as returning to calm.

[0150] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An electromagnetic shock pull-out testing machine, characterized in that, include: Machine (1); The oil cylinder (2) is fixedly installed on the machine base (1), and the piston rod of the oil cylinder (2) has a permanent magnet built in it; The slide (3) is connected to the piston rod of the oil cylinder (2); The upper gripper (4a) is disposed on the slide (3); The lower jaw (4b) is located on the machine base (1), below the upper jaw (4a) and opposite to the upper jaw (4a). The upper jaw (4a) and the lower jaw (4b) can cooperate to clamp the steel bar. The first coil (11) and the second coil (12) are both wound around the outside of the oil cylinder (2), and the first coil (11) and the second coil (12) are arranged at vertical intervals; During operation, the upper jaw (4a) and the lower jaw (4b) clamp the reinforcing bar, and the hydraulic cylinder (2) drives the slide (3) to rise to pull out the reinforcing bar; When the steel bar is pulled out, the piston rod of the oil cylinder (2) vibrates due to the impact force. The piston rod moves axially within the second coil (12), and the second coil (12) cuts the magnetic field lines and generates an induced current. The electromagnetic anti-seismic pull-out tester also includes a reverse current control module. The reverse current control module is used to detect the instantaneous maximum current generated by the piston rod vibration of the second coil (12) when the steel bar is pulled out, and to supply reverse current to the first coil (11) so that the first coil (11) generates a reverse Ampere force to counteract the vibration of the piston rod. Under the action of the reverse Ampere force, the amplitude of the piston rod decreases and the vibration speed slows down. The instantaneous maximum current value in the second coil (12) decreases. The reverse current control module can also dynamically adjust the reverse current value according to the subsequently detected instantaneous maximum current value to match the continuously decaying impact force.

2. The electromagnetic seismic pull-out testing machine according to claim 1, characterized in that, The piston rod of the hydraulic cylinder (2) includes: The magnetic core shaft is made of soft magnetic alloy; The composite magnetic ring is composed of alternating neodymium iron boron magnetic rings and soft magnetic rings along the axial direction. The magnetic core shaft is interference-fitted with the inner hole of the composite magnetic ring to form a closed magnetic circuit. The composite magnetic ring is interference-fitted into the alloy jacket.

3. The electromagnetic seismic pull-out testing machine according to claim 2, characterized in that, The neodymium iron boron magnetic ring is radially magnetized, and the radial magnetization directions of any two adjacent neodymium iron boron magnetic rings are opposite, so that the intensity of the axial magnetic field fluctuates periodically. A soft magnetic ring is provided between any two adjacent neodymium iron boron magnetic rings. The soft magnetic ring can guide the radial magnetic lines of force to the axial direction, so that the magnetic fields of the adjacent neodymium iron boron magnetic rings are superimposed in the axial direction, thereby enhancing the magnetic field gradient.

4. The electromagnetic seismic pull-out testing machine according to claim 2, characterized in that, The neodymium iron boron magnetic ring and the soft magnetic ring are interference-fitted and filled with high magnetic permeability potting compound to avoid the presence of air gaps that would increase magnetic resistance. And / or, the neodymium iron boron magnetic ring is magnetized at a 45° angle, in conjunction with the magnetic core shaft, so that the radial magnetic field component and the circumferential current of the first coil (11) are close to 90°, thereby maximizing the reverse Ampere force; And / or, the coaxiality error between the neodymium iron boron magnetic ring and the soft magnetic ring is ≤0.02mm, to prevent magnetic field eccentricity from causing fluctuations in induced current.

5. The electromagnetic shock pull-out testing machine according to claim 1, characterized in that, The first coil (11) and / or the second coil (12) are wound around the cylinder body of the oil cylinder (2); The cylinder body is made of non-magnetic material; The outer wall of the cylinder is provided with a soft magnetic shielding layer, which can reduce magnetic resistance and enhance the penetration efficiency of the magnetic field. The radial inner sides of the first coil (11) and the second coil (12) are no more than 5 cm apart from the piston rod of the oil cylinder (2).

6. The electromagnetic seismic pull-out testing machine according to claim 1, characterized in that, The oil in the cylinder (2) is phenyl silicone oil-based hydraulic oil, and nano silica sol and graphene nanosheets are also added to the oil. The content of the nano silica sol is 0.5-1%. When the piston rod of the oil cylinder (2) is subjected to impact vibration, the particles of the nano silica sol can instantly form a chain structure, increasing the viscosity of the oil and generating damping force to suppress vibration. The graphene nanosheets contain 1-2% of the material, and adding the graphene nanosheets can improve the thermal conductivity of the oil.

7. The electromagnetic seismic pull-out testing machine according to claim 1, characterized in that, The reverse current control module includes: Control system; The current detection circuit includes a second coil (12) located in the current detection circuit. The current detection circuit also includes a current transformer, a signal conditioning module for filtering, amplification and peak detection, and an analog-to-digital converter. The signal conditioning module can capture the current generated in the second coil (12) in real time and feed it back to the control system to achieve peak identification. The power drive circuit includes a first coil (11) located in the power drive circuit. The power drive circuit also includes a power supply, a power bridge drive module, and a Hall current sensor. After the control system calculates the reverse current value, it supplies reverse current to the first coil (11) through the power supply and the power bridge drive module, so that the first coil (11) generates a reverse Ampere force that matches the impact force. The Hall current sensor can monitor the current in the first coil (11) in real time to form a closed-loop control. When the steel bar is pulled out, the signal conditioning module captures the instantaneous maximum current generated in the second coil (12). The control system can calculate the required reverse current value based on the instantaneous maximum current value. The power bridge drive module outputs reverse current to the first coil (11). Under the action of the reverse Ampere force, the amplitude of the piston rod of the oil cylinder (2) is reduced. The reverse current control module can adjust the output reverse current in real time until the vibration stops.

8. The electromagnetic seismic pull-out testing machine according to claim 7, characterized in that, The current detection circuit is also provided with an energy storage capacitor, which is used to store the current generated by the second coil (12); The reverse current control module also includes a DC-DC conversion circuit, which can convert the current stored in the energy storage capacitor into the voltage required for the first coil (11) to work, thereby enabling the second coil (12) to supply power to the first coil (11); When the power generation of the second coil (12) is insufficient, the control system can switch the power supply mode and supply power to the first coil (11) from the power supply.

9. The electromagnetic seismic pull-out testing machine according to any one of claims 1-8, characterized in that, It also includes a third coil (13), which is located above the slide (3); The slide (3) is provided with an extension rod (5); When the steel bar is pulled out, the piston rod of the oil cylinder (2) is subjected to an impact force and jumps upward first. The second coil (12) generates an induced current. The extension rod (5) is inserted into the third coil (13). The reverse current control module supplies a reverse current to the third coil (13), causing the third coil (13) to generate a downward Ampere force, thereby hindering the extension rod (5) from moving upward.

10. A seismic resistance method, implemented using the electromagnetic seismic pull-out testing machine as described in claim 9, characterized in that, Includes the following steps: At the moment the steel bar is pulled out, the second coil (12) generates an induced current. The reverse current control module supplies a reverse current to the third coil (13) according to the first instantaneous maximum current value generated by the second coil (12), so that the third coil (13) generates a downward reverse Ampere force, which inhibits the piston rod of the oil cylinder (2) from moving upward through the third coil (13). When the piston rod falls back, the second coil (12) generates an induced current in the opposite direction. The reverse current control module supplies a reverse current to the first coil (11) according to the second instantaneous maximum current value generated by the second coil (12), so that the first coil (11) generates an upward reverse Ampere force, which slows down the falling speed of the piston rod through the first coil (11). The piston rod's falling speed slows down and its amplitude decreases, resulting in a decrease in the instantaneous maximum current value measured again, and consequently, a decrease in the required reverse current value. The vibration of the piston rod gradually decreased until it returned to normal.

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