Electromagnetic anti-seismic drawing test machine and anti-seismic method

Abstract

The invention discloses an electromagnetic anti-seismic drawing test machine and an anti-seismic method. The drawing test 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, and a permanent magnet is arranged in a piston rod of the oil cylinder; when the reinforcing steel bar is pulled off, the piston rod vibrates due to impact force, the piston rod axially moves in the second coil, the second coil cuts magnetic induction lines, and induced current is generated; the induced current can be used as an indirect index of impact force; the first coil is electrified to generate corresponding reverse Ampere force, so that instant shock resistance can be realized, and reverse shock of the piston rod caused by overlarge reverse force is avoided; the reverse current control module can monitor the current value in the second coil in real time and then correspondingly change the reverse current required by the first coil according to the latest detected instantaneous maximum current value to form a closed loop of vibration detection, force feedback and dynamic adjustment.

Description

Technical Field

[0001] The present application relates to the technical field of anti-seismic systems for drawing machines, and in particular to an electromagnetic anti-seismic drawing test machine and an anti-seismic method. Background Art

[0002] In fields like construction and metalworking, pull-out testing machines are commonly used to break workpieces like rebar and test their performance. When breaking rebar, these machines generate a tremendous instantaneous impact force, causing the entire machine to vibrate violently.

[0003] Existing technologies mainly achieve shock absorption and anti-vibration by installing springs. The spring relies on the deformation of its own elastic structure to dissipate the impact force. However, as the spring gradually attenuates the vibration energy through continuous deformation, the equipment will be in a state of vibration with amplitude decreasing from large to small for a long time, and it will take a long time to stabilize. The elastic vibration characteristics of the spring can also easily cause the equipment to resonate, further increasing the vibration amplitude and prolonging the duration of the vibration, thereby affecting the accuracy of the equipment, shortening the service life of the equipment, and even causing safety hazards. In addition, a single spring anti-vibration structure only absorbs energy through mechanical deformation and cannot actively resist the impact force. In particular, when facing high-frequency or high-load shocks, the anti-vibration efficiency will be insufficient. Summary of the Invention

[0004] The purpose of this application is to overcome the deficiencies in the prior art and to provide an electromagnetic anti-seismic pull-out testing machine and an anti-seismic method.

[0005] The present application provides an electromagnetic anti-seismic pull-out testing machine, comprising: a machine platform; an oil cylinder fixedly arranged on the machine platform, a piston rod of the oil cylinder having a built-in permanent magnet; a slide connected to the piston rod of the oil cylinder; an upper clamping jaw arranged on the slide; a lower clamping jaw arranged on the machine platform, located below the upper clamping jaw and arranged opposite to the upper clamping jaw, the upper clamping jaw and the lower clamping jaw being able to cooperate in clamping steel bars; a first coil and a second coil both wound outside the oil cylinder, and the first coil and the second coil being arranged at intervals along the vertical direction; when working, the upper clamping jaw and the lower clamping jaw clamp the steel bars, and the oil cylinder drives the slide to rise to pull the steel bars; when the steel bars are pulled off, the piston rod of the oil cylinder is subjected to the impact force and vibrates, and the piston rod is The second coil moves axially, cutting the magnetic lines of force and generating an induced current. The electromagnetic anti-seismic pull-out testing machine also includes a reverse current control module, which is used to detect the instantaneous maximum current generated by the second coil due to the vibration of the piston rod when the steel bar is pulled out, and supply 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 of the piston rod decreases, the vibration speed slows down, 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 instantaneous maximum current value detected subsequently to match the continuously decaying impact force.

[0006] Furthermore, the piston rod of the oil cylinder includes: a magnetic core shaft made of a soft magnetic alloy; a composite magnetic ring composed of NdFeB magnetic rings and soft magnetic rings arranged alternately along the axial direction, the magnetic core shaft and the inner hole of the composite magnetic ring are interference fit to form a closed magnetic circuit; an alloy outer sleeve, the composite magnetic ring is interference installed in the alloy outer sleeve.

[0007] Furthermore, the NdFeB magnetic rings are radially magnetized, and the radial magnetization directions of any two adjacent NdFeB 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 NdFeB magnetic rings, and the soft magnetic ring can guide the 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.

[0008] Furthermore, a high-permeability potting glue is used between the NdFeB magnetic ring and the soft magnetic ring to avoid an increase in magnetic resistance due to the presence of an air gap; and / or, the NdFeB magnetic ring is magnetized at a 45° angle and, in conjunction with the magnetic core shaft, makes the angle between the radial magnetic field component and the axial magnetic field of the first coil 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 induced current fluctuations caused by magnetic field eccentricity.

[0009] Furthermore, the first coil and / or the second coil are wound outside the cylinder body; 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 cylinder piston rod.

[0010] Furthermore, the oil in the cylinder is phenyl silicone-based hydraulic oil, to which nano-silica sol and graphene nanosheets are added; the content of nano-silica sol is 0.5-1%, and when the piston rod of the cylinder is impacted and vibrated, 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.

[0011] Furthermore, the reverse current control module includes: a control system; a current detection circuit, wherein the second coil is disposed in the current detection circuit, and the current detection circuit is further provided with 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 recognition; a power drive circuit, wherein the first coil is disposed in the power drive circuit, and the power drive circuit is further provided with a power supply, a power bridge drive module, and a Hall current sensor. After the control system calculates the reverse current value, it transmits the 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 to form a closed-loop control. When the steel bar is pulled off, 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 the reverse current to the first coil. Under the action of the reverse Ampere force, the amplitude of the piston rod of the oil 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 provided 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 operation of the first coil, thereby enabling the second coil to power 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 seismic pull-out testing machine also includes a third coil, which is arranged above the slide; an extension rod is provided on the slide; when the steel bar is pulled off, the piston rod of the oil cylinder is subjected to 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 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] The present application also provides an earthquake-resistant method, which is implemented using the above-mentioned electromagnetic earthquake-resistant pull-out testing machine, and includes the following steps: at the moment the steel bar is pulled off, the second coil generates an induced current, and the reverse current control module supplies a reverse current to the third coil according to the first instantaneous maximum current value generated by the second coil, and the upward movement of the piston rod of the oil cylinder is suppressed by the third coil; when the piston rod falls back, the second coil generates an induced current in the opposite direction, and the reverse current control module supplies a reverse current to the first coil according to the second instantaneous maximum current value generated by the second coil, and the falling speed of the piston rod is slowed down through the first coil; the falling speed of the piston rod slows down and the amplitude decreases, the instantaneous maximum current value measured again decreases, and the reverse current value required to be supplied decreases accordingly; the vibration of the piston rod continues to decay until it returns to calm.

[0015] The present application provides an electromagnetic anti-seismic pull-out testing machine, comprising a machine platform, an oil cylinder, a slide, an upper clamping jaw, a lower clamping jaw, a first coil, a second coil and a reverse current control module. A permanent magnet is built into the piston rod of the oil cylinder. When the steel bar is pulled off, the piston rod is subjected to the impact force and vibrates, and the piston rod moves axially in the second coil. The second coil cuts the magnetic flux lines and generates an induced current. The induced current can be used as an indirect indicator of the impact force. The first coil is energized to generate a corresponding reverse Ampere force, which can both instantly resist seismic and prevent the piston rod from vibrating 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 reverse current required by 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 anti-seismic pull-out testing machine provided by the present application effectively solves the core problem of traditional spring anti-seismic through the dynamic regulation of electromagnetic induction and reverse Ampere force. Compared with the defect that springs rely on elastic deformation to passively absorb energy, which causes the equipment to vibrate for a long time, this structure generates an induced current through the second coil when the steel bar is pulled out, triggering the first coil to generate reverse Ampere force, actively counteracting the vibration of the piston rod, which can effectively shorten the amplitude decay time and accelerate the stabilization speed of the whole machine. In order to solve the problem that spring elastic vibration is prone to resonance and aggravate the vibration amplitude, electromagnetic anti-seismic adjusts the reverse current value in real time to accurately match the reverse Ampere force with the impact force, avoiding resonance, effectively reducing the vibration amplitude and ensuring the testing accuracy of the equipment. In addition, through closed-loop control, the reverse force is continuously and dynamically adjusted according to the instantaneous maximum current value, which can effectively suppress vibration in the face of different impact loads, reduce the loosening of equipment components caused by long-term vibration, and extend the service life. The electromagnetic anti-seismic pull-out testing machine provided by the present application overcomes the deficiency that traditional springs cannot actively resist high-frequency or large-load impacts, and solves the problems of high energy consumption and poor adaptability of traditional anti-seismic structures.

[0016] This application also provides a seismic resistance method implemented using the aforementioned electromagnetic seismic resistance pull-out tester. 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 change the reverse Ampere force based on the impact force, accurately resisting impact vibration, thereby increasing the attenuation rate, reducing the vibration amplitude of the machine, shortening the seismic resistance time, and improving the stability of the tester equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of an electromagnetic seismic pull-out testing machine provided in this application; Figure 2 for Figure 1 The structure diagram of the electromagnetic anti-seismic pull-out testing machine shown is omitting the machine housing; Figure 3 for Figure 2 The schematic diagram of the structure of the electromagnetic anti-vibration pulling test machine from another angle is shown. DETAILED DESCRIPTION

[0018] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0019] The present application provides an electromagnetic seismic pull-out testing machine, comprising: a machine platform 1; a cylinder 2, fixedly arranged on the machine platform 1, the piston rod of the cylinder 2 having a built-in permanent magnet; a slide 3, connected to the piston rod of the cylinder 2; an upper clamping jaw 4a, arranged on the slide 3; a lower clamping jaw 4b, arranged on the machine platform 1, located below the upper clamping jaw 4a and arranged opposite to the upper clamping jaw 4a, and the upper clamping jaw 4a and the lower clamping jaw 4b can cooperate to clamp steel bars.

[0020] For details, please refer to Figure 1 In the illustrated embodiment, the machine platform 1 is arranged in a square frame, serving as a horizontal support base. The platform 1 is typically constructed of cast iron or steel, with a flat surface and sufficient rigidity. The platform 1 is fixed to the ground or work platform, serving as the foundational support for the entire machine. The interior of the platform 1 is hollow, with the cylinder body of the oil cylinder 2 and the lower clamping jaw 4b housed within it, also concealing and protecting the components.

[0021] The oil cylinder 2 is composed of a cylinder body and a piston rod, and a permanent magnet is set inside the piston rod. The top of the piston rod is rigidly connected to the slide 3. When working, the piston rod is driven by hydraulic oil to move, which can drive the slide 3 to move up and down. Figure 1 In the embodiment shown, two groups of oil cylinders 2 are provided on the machine 1. The two groups of oil cylinders 2 cooperate with the supporting slide 3 to ensure load capacity and stability.

[0022] In order to ensure the accuracy of the lifting of the slide 3, a guide rod 6 is further provided on the machine 1. The guide rod 6 extends in the vertical direction. The slide 3 is sleeved on the guide rod 6 and can slide along the guide rod 6. Figure 1 In the embodiment shown, four groups of guide rods 6 are provided on the machine 1 . The four groups 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 movement of the slide 3 .

[0023] The upper and lower jaws 4a and 4b are toothed clamping components. The upper jaw 4a is fixed to the slide 3, while the lower jaw 4b is fixed to the machine platform 1. The upper and lower jaws are positioned opposite each other, vertically coaxially aligned, with the spacing between them varying with the movement of the slide 3. During operation, the upper and lower jaws, driven by hydraulic or mechanical clamping, cooperate to clamp the rebar to be pulled, securing it between them and forming a pulling station.

[0024] In one embodiment, during testing, a rebar is placed vertically between the upper and lower jaws 4a, 4b, which cooperate to clamp and secure the rebar. The hydraulic system within cylinder 2 is activated, pushing the piston rod upward, driving the slide 3 and upper jaw 4a synchronously upward, exerting a continuous pullout force on the rebar. When the pullout force exceeds the tensile strength of the rebar, the rebar breaks, and the test concludes. By simulating the tensile loads under actual working conditions, mechanical properties such as tensile strength and yield strength of the rebar can be tested, providing data support for quality assessment of building materials.

[0025] It's easy to understand that the moment the rebar breaks, the tension on the piston rod of cylinder 2 suddenly decreases. The hydraulic system's thrust and inertia create an instantaneous impact, causing the piston rod and slide 3 to jerk violently. Simultaneously, the elastic deformation caused by the broken rebar releases energy, further exacerbating the vibration of the entire machine, ultimately forming a damped oscillation dominated by the axial motion of the piston rod.

[0026] Traditional drawing machines mostly use spring anti-seismic structures, relying on the elastic deformation of the spring to absorb vibration energy. However, the spring vibration cycle is long, and the equipment needs to vibrate continuously for a long time before it can 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 impact, especially in high-frequency or high-load tests. The vibration attenuation efficiency is low, which not only affects the accuracy of subsequent tests, but also causes equipment components to loosen and shorten their lifespan due to long-term vibration.

[0027] In order to improve the anti-seismic effect, the electromagnetic anti-seismic pulling tester provided in the present application further includes a first coil 11 and a second coil 12, both of which are wound outside the oil cylinder 2, and the first coil 11 and the second coil 12 are arranged vertically spaced apart.

[0028] During operation, the upper clamping jaw 4a and the lower clamping jaw 4b clamp the steel bar, and the oil cylinder 2 drives the slide 3 to rise to pull the steel bar; when the steel bar is pulled off, the piston rod of the oil cylinder 2 is subjected to the impact force and vibrates, and the piston rod moves axially in the second coil 12, and the second coil 12 cuts the magnetic flux lines and generates an induced current; the electromagnetic seismic pull-out testing machine also includes a reverse current control module, which is used to detect the instantaneous maximum current generated by the vibration of the piston rod in the second coil 12 when the steel bar is pulled off, and supplies 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, the vibration speed slows down, 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 instantaneous maximum current value detected subsequently to match the continuously attenuating impact force.

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

[0030] Specifically, the first coil 11 has a large number of turns (e.g., 600-900 turns) and a thicker wire diameter (AWG16); the second coil 12 has a small number of turns (e.g., 200-300 turns) and a thinner wire diameter (AWG18); the two groups of coils are arranged in a vertically spaced manner, with the first coil 11 located above the second coil 12, with an axial spacing of 10-20 mm and a radial inner gap of ≤5 cm from the piston rod.

[0031] More specifically, the cylinder body of the oil 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 and can move up and down along the axis of the oil cylinder 2. The movement range 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 the machine 1. The reverse current control module is connected to the first coil 11 and the second coil 12 via a cable, and can receive current signals in real time and output control instructions.

[0033] In one embodiment, the oil cylinder 2 drives the slide 3 upward, causing the upper and lower clamps to pull the rebar. When the rebar breaks, the piston rod is impacted and vibrates, driving the built-in permanent magnet to move axially within the second coil 12. The radial magnetic field of the permanent magnet cuts the conductor 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. According to the Ampere force principle, this generates an Ampere force in the opposite direction of the vibration, thereby suppressing the vibration of the piston rod.

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

[0035] The induced current I2 = R2 / E, where R2 is the resistance (fixed value) of the second coil 12. The reverse current control module can detect I2 and thus calculate v.

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

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

[0038] The first coil 11 is energized to generate a magnetic field, thereby exerting a force on the piston rod in the opposite direction to the vibration direction.

[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), μ is the magnetic permeability). The ratio can be calibrated in advance through testing. Therefore, in actual use, B1 can be simplified to a value with a fixed proportional relationship with I1, and F is calculated. 冲击After that, I1 can be calculated in reverse, and I1 is the reverse current value required by the first coil 11.

[0040] By energizing the first coil 11 and generating a corresponding reverse Ampere force, the system provides instantaneous shock absorption without causing reverse vibration of the piston rod due to excessive reverse force. After a single shock absorption event, the piston rod's vibration dampens, its amplitude decreases, and its velocity slows. This reduces the induced current generated by the second coil 12. The reverse current control module monitors the current in the second coil 12 in real time and adjusts the reverse current required by the first coil 11 based on the latest detected instantaneous maximum current value, forming a closed loop of "vibration detection-force feedback-dynamic adjustment."

[0041] The electromagnetic anti-seismic pull-out testing machine provided by the present application effectively solves the core problem of traditional spring anti-seismic through the dynamic regulation of electromagnetic induction and reverse Ampere force. Compared with the defect that springs rely on elastic deformation to passively absorb energy, which causes the equipment to vibrate for a long time, 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, which can effectively shorten the amplitude decay time and accelerate the stabilization speed of the whole machine. In order to solve the problem that spring elastic vibration is prone to resonance and aggravate the vibration amplitude, electromagnetic anti-seismic adjusts the reverse current value in real time to accurately match the reverse Ampere force with the impact force, avoiding resonance, effectively reducing the vibration amplitude and ensuring the test accuracy of the equipment. In addition, through closed-loop control, the reverse force is continuously and dynamically adjusted according to the instantaneous maximum current value, which can effectively suppress vibration in the face of different impact loads, reduce the loosening of equipment components caused by long-term vibration, and extend the service life. The electromagnetic anti-seismic pull-out testing machine provided by the present application overcomes the deficiency that traditional springs cannot actively resist high-frequency or large-load impacts, and solves the problems of high energy consumption and poor adaptability of traditional anti-seismic structures.

[0042] In a specific embodiment, the piston rod of the oil 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, and the magnetic core shaft and the inner hole of the composite magnetic ring are interference fit to form a closed magnetic circuit to reduce magnetic field leakage; an alloy outer sleeve made of alloy structural steel, and the composite magnetic ring is interference installed in the alloy outer sleeve.

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

[0044] NdFeB magnetic rings act as permanent magnets to generate a strong magnetic field; the soft magnetic rings are located between adjacent NdFeB magnetic rings, which can guide the 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 close magnetic circuit. This closed magnetic circuit formed by the interference fit reduces magnetic field leakage and concentrates magnetic field energy. This not only helps to improve the efficiency of the induced current generated when the second coil 12 cuts the magnetic flux lines, but also increases the reverse Ampere force generated by the first coil 11 under the action of the magnetic field, thereby more effectively counteracting piston rod vibration.

[0046] The alloy outer sleeve is constructed of structural alloy steel, offering high strength and rigidity. The composite magnetic ring, composed of NdFeB and soft magnetic rings arranged alternately along the axial direction, is interference-fitted within the alloy outer sleeve. The alloy outer sleeve provides mechanical support and protection for the composite magnetic ring. The interference fit secures the composite magnetic ring and ensures structural stability and resists deformation when the piston rod withstands the impact of pulling the rebar.

[0047] In one specific embodiment, the magnetic core shaft is made of 1J50 soft magnetic alloy (magnetic permeability μ ≥ 8000, saturation magnetic induction intensity B_s ≥ 1.5T) with a density of 7.6 g / cm³. The core shaft has a diameter of 40 mm and a length of 300 mm, with a cylindricity error of ≤ 0.01 mm and a surface roughness Ra ≤ 0.8 μm. During manufacturing, the formed core shaft undergoes vacuum annealing at 850°C (holding temperature for 2 hours) to eliminate machining stress and improve magnetic permeability. The core shaft is electroplated with a nickel-phosphorus alloy (10-15 μm thick) to enhance corrosion resistance and reduce friction with the inner bore of the composite magnetic ring. The outer diameter of the core shaft has an interference fit of 0.03-0.05 mm with the inner bore of the composite magnetic ring. Assembly is performed using a shrink-fit method (heating the composite magnetic ring to 200°C and cooling the core shaft to -40°C, utilizing the clearance created by thermal expansion and contraction). In addition, the outer surface of the magnetic core shaft is processed with an axial positioning groove (5mm wide and 2mm deep), and the inner wall surface of the inner hole of the composite magnetic ring is processed with a positioning boss. The positioning boss corresponds to the axial positioning groove one by one to ensure that the axial position accuracy of the NdFeB magnetic ring and the soft magnetic ring is ≤0.1mm.

[0048] In one specific embodiment, the NdFeB rings utilize N52 NdFeB (remanence Br = 1.43T, coercivity Hc = 1080kA / m), with dimensions of 60mm × 25mm × 25mm (outer diameter × inner diameter × axial length). The NdFeB magnets are radially magnetized, with adjacent NdFeB rings facing opposite directions (alternating between north and south poles facing outward). The NdFeB rings are cut using diamond wire cutting (wire diameter 0.3mm), with a dimensional tolerance of ±0.02mm and a surface roughness of Ra ≤ 1.6μm. Radially magnetizing is performed using a pulsed magnetization device (magnetic field strength 2.5T) to ensure magnetization consistency within 1°.

[0049] The soft magnetic ring is made of DT4C electrical pure iron (magnetic permeability μ≥3000) and measures 60mm × 40.1mm × 10mm (outer diameter × inner diameter × axial length). The NdFeB ring and the soft magnetic ring are arranged in a 25mm + 10mm periodic pattern in the axial direction of the composite magnetic ring. During manufacturing, the formed soft magnetic ring is annealed at 650°C (holding temperature for 1 hour) to eliminate work hardening and restore soft magnetic properties. The soft magnetic ring is copper-plated (5μm thick) to prevent oxidation and improve bonding with the potting compound.

[0050] In this embodiment, the composite magnetic rings are arranged alternately in the axial direction according to "NdFeB magnetic ring → soft magnetic ring → NdFeB magnetic ring → soft magnetic ring", with a total number of 8 groups and a total length of 35mm×8=280mm.

[0051] Optionally, a high-permeability potting compound (send-silicon-aluminum powder + epoxy resin, with a magnetic permeability μ ≥ 100) is filled between the NdFeB magnetic ring and the soft magnetic ring. The two are vacuum potted (vacuum degree ≤ 10Pa) and the curing conditions are 80°C for 2 hours to eliminate air gaps and reduce magnetic resistance.

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

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

[0054] Optionally, the NdFeB magnetic rings are radially magnetized, and the radial magnetization directions of any two adjacent NdFeB 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 NdFeB magnetic rings, and the soft magnetic ring can guide the 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.

[0055] Specifically, NdFeB magnets and soft magnetic rings are arranged alternately along the piston rod's axial direction. The radial magnetization directions of two adjacent NdFeB magnets are opposite (e.g., the N pole of the preceding NdFeB magnet faces outward, while the S pole of the following NdFeB magnet faces outward), forming a periodic magnetic pole distribution. The soft magnetic ring is sandwiched between the two NdFeB magnets and fits tightly against them.

[0056] Adjacent NdFeB rings are magnetized radially in opposite directions, forming alternating north and south poles in the axial direction, resulting in a periodic fluctuation of "strong-weak-strong-weak" in axial magnetic field strength. The soft magnetic ring (a high-permeability material) guides the radial magnetic lines of force emanating from the NdFeB rings axially, causing the magnetic fields of adjacent NdFeB rings to overlap axially, thereby enhancing the gradient of magnetic field strength (i.e., the difference in magnetic field strength per unit length). This increased magnetic field gradient increases the rate of change (ΔΦ / Δt) of magnetic flux generated by the second coil 12 cutting through the magnetic flux lines during piston rod vibration. According to the law of electromagnetic induction, the induced current intensity within the coil increases, thereby improving induced current efficiency and enabling accurate reflection of impact force. Furthermore, the enhanced magnetic field gradient in the first coil 11 generates a greater reverse Ampere force, contributing to power supply safety. Furthermore, the periodic fluctuation of the magnetic field gradient is more closely aligned with the vibration frequency, effectively suppressing vibrations at varying 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 sleeve are designed to have an interference fit of 0.03-0.08mm. The outer diameter of the composite magnetic ring is slightly larger than the inner diameter of the alloy sleeve. The composite magnetic ring is pressed into the alloy sleeve by a heat-fitting method, and then the thermal expansion and contraction characteristics of the material are utilized to form a tight fit.

[0058] Optionally, the interference fit between the NdFeB ring and the soft magnetic ring is set to 0.02-0.03mm (this interference fit refers to the tolerance between the NdFeB ring's outer diameter and the soft magnetic ring's inner diameter, meaning the NdFeB ring's outer diameter is 0.02-0.03mm larger than the soft magnetic ring's inner diameter). This minimizes the interference fit when assembling the NdFeB ring (a hard, brittle material) with the soft magnetic ring (a soft magnetic alloy or pure iron, with excellent toughness). This minimizes stress concentration and fracture during press-fitting, ensuring close contact between the NdFeB ring and the soft magnetic ring. Combined with a high-permeability potting compound to fill microscopic gaps, it eliminates air gaps and prevents increased magnetic resistance. This design ensures that the composite ring is securely aligned axially within the alloy housing, preventing vibration-induced shifting that could affect magnetic field distribution. Furthermore, reducing air gaps in the magnetic circuit, lowering magnetic resistance, and enhancing magnetic field strength are all factors contributing to this reduction.

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

[0060] Optionally, the soft magnetic material of the soft magnetic ring can account for 30%-40% of the axial portion. This ratio, through an interference fit with the NdFeB ring and filling with a high-permeability potting compound, ensures axial continuity of the magnetic circuit. This ratio effectively guides the NdFeB ring's radial magnetic lines of force to the axial direction, enhancing the magnetic field superposition effect, while also preventing an excessively high proportion of soft magnetic material from weakening the NdFeB ring's magnetic field strength. This optimizes the axial magnetic field gradient while ensuring low magnetic resistance and high energy utilization in the magnetic circuit, improving the response speed and damping effect of the electromagnetic anti-vibration system.

[0061] Optionally, the NdFeB magnetic ring and the soft magnetic ring are interference-fitted and filled with a high-permeability potting glue to avoid an increase in magnetic resistance due to the presence of an air gap.

[0062] It's important to explain that high-permeability potting compound is a composite material made with a polymer matrix (such as epoxy resin or silicone rubber) filled with high-permeability powders (such as sendust, carbonyl iron powder, and ferrite). High-permeability potting compound offers excellent magnetic conductivity and potting processability. It's primarily used to fill gaps in magnetic circuit systems, reducing the magnetic resistance created by air gaps and improving the efficiency of magnetic field energy transfer.

[0063] In one specific embodiment, the matrix resin is a low-viscosity epoxy resin (such as E-51) with a post-curing shrinkage of ≤0.1%, which helps ensure crack-free encapsulation. Furthermore, the shear strength is ≥15 MPa, which facilitates reliable adhesion to the surface of the magnetic ring. Sendust powder (magnetic permeability μ ≥ 800) with an average particle size of 5-10 μm is added to the matrix resin, with the filler accounting for 60%-70% by weight. The filler is evenly dispersed through a ball milling process to prevent agglomeration and uneven magnetic permeability. A silane coupling agent (such as KH-550) is also added to the filler at a dosage of 1%-2% by weight to improve the compatibility between the filler and the resin and reduce interfacial magnetic resistance.

[0064] During potting, first use anhydrous ethanol to ultrasonically clean the surface of the NdFeB magnetic ring and the soft magnetic ring for 10 minutes to remove oil and oxides to improve the adhesion of the potting compound; then perform vacuum potting, place the composite magnetic ring into a vacuum tank (vacuum degree ≤ 10Pa), inject the prepared potting compound, maintain the vacuum state for 30 minutes, and expel the air in the gap to avoid bubbles from remaining and forming air gaps; finally, perform curing, using a step-by-step curing process, first keep warm at 60°C for 2 hours, then heat to 80°C for curing for 4 hours, and apply 0.1MPa pressure during the curing process to ensure that the potting compound fully fills the micro gaps.

[0065] After eliminating the air gap with high-permeability potting glue, 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 linearity of the induced current peak and impact force of the second inductive coil 12 better; at the same time, the hysteresis loss can be reduced by 15%-20%, avoiding the magnetic field distortion caused by air gap magnetic saturation and ensuring the stability of the reverse Ampere force.

[0066] Furthermore, the potting compound achieves a hardness of Shore D70-80 after curing, providing rigid support for the magnetic ring and preventing displacement caused by vibration. Furthermore, the potting compound exhibits excellent temperature resistance, suitable for operating environments ranging from -40°C to 120°C, and will not crack or fall off over long periods of use, effectively ensuring the reliability of the magnetic circuit structure.

[0067] Optionally, the NdFeB magnetic ring is magnetized at a 45° tilt, and cooperates with the magnetic core shaft so that 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 and the current). When θ = 90°, sinθ = 1, and the Ampere force is maximum. Magnetizing the NdFeB ring at a 45° angle creates a near 90° angle between its radial magnetic field component and the axial magnetic field of first coil 11, maximizing Ampere force output and effectively counteracting piston rod vibration and improving seismic efficiency.

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

[0070] The 45° tilted magnetization improves the coupling coefficient between the magnetic field and the coil, increasing the energy utilization of the first coil 11. This generates a greater reverse force at the same current, effectively reducing energy consumption. Furthermore, tilted magnetization makes the magnetic field more uniform. When the piston rod experiences radial deflection (≤0.5mm), the fluctuation amplitude of the Ampere force is ≤5%, which helps improve the stability of the anti-seismic system.

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

[0072] It needs to be explained that the coaxial deviation between the NdFeB magnetic ring and the soft magnetic ring will cause the magnetic field to be eccentric, resulting in uneven distribution of the magnetic flux lines cut by the second coil 12, which will cause periodic fluctuations in the induced current, and then cause the reverse current control module to misjudge the magnitude of the impact force, and ultimately make the reverse Ampere force output by the first coil 11 mismatch with actual needs, affecting the anti-seismic effect.

[0073] If the coaxiality error exceeds 0.02 mm, the eccentric magnetic field 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 attenuation time.

[0074] To achieve a coaxiality error of ≤0.02mm, the NdFeB magnetic ring and the soft magnetic ring are machined using a CNC grinder, ensuring a coaxiality error of ≤0.01mm between the inner hole and the outer diameter, and a surface roughness Ra of ≤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 transmission after assembly. The magnetic core shaft is precision ground using a cylindrical grinder to a cylindricity error of ≤0.01mm / m, and the coaxiality reference error between the outer diameter and the inner hole of the composite magnetic ring is ≤0.01mm.

[0075] During assembly, a dedicated coaxial positioning fixture is used to secure the composite magnetic ring using a three-jaw chuck (positioning accuracy ≤ 0.01mm) with the magnetic core shaft as the reference. This ensures that the coaxial deviation between the composite magnetic ring inner hole and the magnetic core shaft is ≤ 0.01mm. A hydraulic press (pressure control accuracy ±0.5kN) is then used to press the ring at a uniform speed (≤ 0.1mm / s) along the axial direction. Real-time monitoring of the press force curve is used to avoid localized stress concentration caused by eccentricity. After assembly, a laser coaxiality tester (accuracy 0.001mm) is used to evenly select five cross-sections along the axial direction of the magnetic ring to test the coaxiality of the inner and outer diameters. Products that exceed this tolerance are reassembled or scrapped.

[0076] Coaxiality control reduces the fluctuation amplitude of the induced current in the second coil 12, improving the linearity between the current peak and the impact force, thereby optimizing the judgment error of the reverse current control module. Coaxiality control reduces the deviation of the reverse Ampere force generated by the first coil 11, helping to improve the consistency of piston rod vibration attenuation and reducing the fluctuation of the amplitude decay time under the same test conditions. Even if the piston rod undergoes radial displacement during vibration, the uniform magnetic field distribution keeps the induced current variation small, ensuring that the seismic protection system maintains test accuracy and stable operation under complex operating conditions.

[0077] In one embodiment, the first coil 11 and / or the second coil 12 are wound outside the cylinder body of the oil cylinder 2; the cylinder body is made of non-magnetic material; and 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 is used to make the cylinder body. The total density is 2.7g / cm³, the magnetic permeability is close to vacuum (μ≈1.0002), and the tensile strength is ≥260MPa, which is suitable for processing the cylinder body structure.

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

[0080] Another example is the use of engineering plastics (such as PEEK) to make the cylinder body. Engineering plastics are non-magnetic and insulating, with a density of 1.3g / cm³ and a temperature resistance of 260°C. However, they have low mechanical strength (tensile strength ≈ 90MPa) and require a metal frame.

[0081] Traditional magnetic materials (such as cast iron) attract magnetic lines of force, concentrating the magnetic field in the cylinder and preventing it from effectively penetrating the coil area, weakening the induced current and the reverse Ampere force. Using non-magnetic materials to make the cylinder can avoid magnetic field distortion.

[0082] Magnetic conductive materials will produce eddy current losses in an alternating magnetic field. Non-magnetic conductive materials can reduce such losses, thereby reducing coil heating.

[0083] The soft magnetic shielding layer is a thin layer made of high-permeability materials (such as silicon steel sheets and Permalloy), with a thickness of 0.1-0.5mm. It is used to guide magnetic field lines and reduce magnetic resistance. For example, the soft magnetic shielding layer is made by laminating 3% silicon steel sheets (μ≈5000), with the lamination direction aligned with the magnetic field. The silicon steel sheets are cut to the contour of the outer wall of the cylinder 2 and adhered to the outer wall of the cylinder using a high-permeability adhesive (such as sendust-filled epoxy adhesive). The layers are staggered and laminated (overlap ratio ≥30%) to eliminate air gaps. The soft magnetic shielding layer is closed along the circumference of the cylinder 2 and welded at both ends with soft magnetic connectors (such as iron-nickel alloy) to form a complete magnetic circuit and prevent magnetic field leakage.

[0084] Adding a soft magnetic shielding layer can reduce magnetic resistance, improve magnetic field penetration efficiency, and enhance the coupling coefficient between the first coil 11 and the piston rod magnetic field. The soft magnetic shielding layer also guides the magnetic field lines to be evenly distributed, reducing the radial magnetic field strength deviation of the coil and ensuring the stability of the induced current.

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

[0086] According to the Biot-Savart law, magnetic field strength is inversely proportional to the square of the distance. Excessive gaps (e.g., >5 cm) cause the magnetic field strength to attenuate, thereby weakening the induced current and the reverse Ampere force. The smaller the gap, the shorter the delay in transmitting the magnetic field change to the coil (for a gap of 5 cm, the delay is ≈0.17 μs, meeting the response requirement of ≤1 ms).

[0087] The radial gap between the coil and the piston rod is kept ≤5cm, the magnetic field intensity in the coil region is attenuated ≤20%, and the peak induced current is maintained above 90% of the design value. Furthermore, this reasonable spacing reduces magnetic field transmission delay, shortening the response time of the reverse Ampere force and effectively suppressing the impact vibration of the piston rod.

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

[0089] The viscosity index of phenyl silicone oil is ≥300 (the viscosity index of ordinary mineral oil is about 150). In the temperature range of -50℃-200℃, the viscosity change rate of phenyl silicone oil is ≤50%. In other words, phenyl silicone oil has excellent viscosity-temperature characteristics and can adapt to the temperature fluctuations caused by the vibration of the piston rod in the pull-out test. The vapor pressure of phenyl silicone oil is ≤10 -3Pa (25°C), it is not easy to volatilize at high temperatures, and its service life is much longer than that of ordinary mineral oil, which can reduce the maintenance cost of oil changes.

[0090] When the piston rod vibrates at high speeds, the oil viscosity remains stable, helping to stabilize thrust fluctuations in cylinder 2 and avoid pull-out force errors caused by viscosity fluctuations. Phenyl silicone oil has a stable molecular chain structure and strong shear resistance. Under high-frequency shear (e.g., vibration frequencies of 50-100Hz), the viscosity decreases minimally, effectively maintaining the stability of the hydraulic system.

[0091] Nano-silica sol (particle size 5-20nm) is evenly dispersed in the oil at rest. When the piston rod is subjected to impact vibration (acceleration ≥ 5g), hydrogen bonding instantly forms a chain structure between the particles (response time ≤ 1ms), causing the oil viscosity to increase sharply from 50cSt to over 200cSt. This creates a shear thickening effect, generating a damping force to suppress vibration. After the vibration decays, the chain structure automatically dissociates, and the oil viscosity recovers, allowing it to repeatedly participate in the next vibration damping, avoiding the irreversible loss of traditional damping materials.

[0092] The nano-silica sol content is limited to 0.5-1% because if 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, which cannot produce the desired vibration suppression effect. If the concentration is too high (>1%), the probability of particle agglomeration increases, and the static oil viscosity increases abnormally. This increases the resistance of cylinder 2 during normal operation, which can easily cause pull-out force errors and block the hydraulic oil line. At a content of 0.5-1%, the oil kinematic viscosity is maintained at 50-60 cSt, which provides a certain degree of anti-vibration damping effect without affecting the normal operation of the hydraulic system.

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

[0094] The graphene nanosheet content is limited to 1-2% because insufficient content (<1%) results in a discontinuous thermal network, insufficient improvement in thermal conductivity, poor oil temperature control, and the tendency for oil oxidation and deterioration over long periods of operation. Excessive content (>2%) causes the graphene sheets to aggregate, increasing oil viscosity, increasing hydraulic system energy consumption, and reducing dispersion stability. A 1-2% content effectively improves thermal conductivity, reduces friction, and minimizes oil viscosity increase, achieving a balanced balance between thermal conductivity and lubrication performance.

[0095] In one embodiment, the reverse current control module includes: a control system; a current detection circuit, the second coil 12 is provided in the current detection circuit, the current detection circuit is further provided with 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 recognition; a power drive circuit, the first coil 11 is provided in the power drive circuit, the power drive circuit is further provided with a power supply, a power bridge drive module and a Hall current sensor, after the control system calculates the reverse current value, through the power supply The power bridge drive module transmits a reverse current to the first coil 11, causing the first coil 11 to generate a reverse Ampere force matching 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 broken, 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 a reverse current to the first coil 11. Under the action of the reverse Ampere force, the amplitude of the piston rod of the 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 with the current detection circuit. When the piston rod vibrates and cuts the magnetic flux lines, an induced current is generated in the second coil 12. Based on the principle of electromagnetic induction, the current transformer converts the high current into a low current signal (with a conversion ratio of 1000:1). After filtering and amplification by the signal conditioning module (including an RC filter circuit, an operational amplifier, and a peak detection circuit), the signal is converted into a digital signal by an analog-to-digital converter (ADC, with 12-bit resolution) for real-time feedback to the control system. The signal conditioning module eliminates high-frequency noise through low-pass filtering (cutoff frequency 1kHz), ensuring that the peak detection circuit captures the instantaneous maximum current, thereby ensuring the accuracy of the impact force signal.

[0097] The control system (such as the DSP chip TMS320F28335) can receive the digital current signal, calculate the required reverse current value through a preset algorithm (such as the peak recognition algorithm and the PID control algorithm), generate a PWM control signal (frequency 20kHz), and send it to the power bridge driver module (such as the IGBT full-bridge circuit).

[0098] The power supply (such as a DC48V switching power supply) outputs a reverse current to the first coil 11 through the power bridge driver module. The Hall current sensor (with an accuracy of ±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 reduced to ≤5ms, while current control accuracy can be improved to ±1%, and the matching error between the reverse Ampere force and the impact force can be reduced to ≤3%. This effectively shortens the piston rod's amplitude decay time and improves seismic resistance.

[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 (breakdown voltage of 12V) to suppress surges. The filtering module attenuates high-frequency noise generated by mechanical vibration (such as harmonics above 2kHz) and improves the signal-to-noise ratio, thereby ensuring a pure 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 of ≥10MΩ. The amplification module converts the weak current signal (0-0.5A) from the second coil 12 into a 0-5V voltage signal, meeting the ADC sampling range and with a signal distortion of ≤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 tube (MOSFETIRF540) to achieve peak reset; the peak detection circuit can accurately capture the instantaneous maximum current, with a response time of <1ms and a hold time of ≥50ms, ensuring that the control system accurately reads each impact peak with an error of ≤0.5%.

[0101] In one specific embodiment, the analog-to-digital converter (ADC) uses the 16-bit ADS1115 ADC chip, operating in differential input mode, with a 1kHz sampling rate, a 4.096V reference voltage, 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, suppressing sampling noise. The high-precision ADC sampling unit improves reverse current control accuracy, maintaining a current quantization error of ≤0.1A. For example, when the sensed current decays from 10A to 1A, it can still accurately match a 0.1A current change. Furthermore, the ADC supports current detection from -20A to +20A (via a polarity detection circuit), meeting the current sampling requirements of bidirectional vibration.

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

[0103] Optionally, the power driver circuit also includes a comparator and latch. When the Hall current sensor detects a current exceeding a preset value, the latch triggers the power bridge driver module to shut down, with a response time of less than 1μs. This prevents burnout of the first coil 11 due to overcurrent (e.g., when the piston rod is stuck). The protection threshold can be fine-tuned using a potentiometer.

[0104] Optionally, a temperature sensor and a fan are provided in the power drive circuit. When the temperature sensor detects that the temperature of the first coil 11 is greater than a preset value, air cooling is forced to start.

[0105] Optionally, the power bridge driver module uses an aluminum heat sink and is equipped with an axial-flow fan. When the temperature of the first coil 11 exceeds a preset value, the axial-flow fan is activated. Combined with the 3mm-thick aluminum heat sink, this controls the junction temperature of the power bridge driver module to below 125°C (the safe operating zone), thereby reducing the temperature of the coil and the power bridge driver module.

[0106] Optionally, the electromagnetic anti-vibration pull-out testing machine further includes a display screen for displaying the induced current waveform, reverse current value, and vibration attenuation curve in real time.

[0107] Optionally, the electromagnetic anti-seismic pulling tester further includes a status indicator light, which indicates normal operation when it is green, a warning when it is yellow, and a fault when it is red.

[0108] Optionally, the electromagnetic anti-vibration pulling tester further includes a buzzer for fault alarm.

[0109] Through visual monitoring, operators can directly observe the earthquake resistance process and also support historical data storage to facilitate analysis of vibration attenuation efficiency. During operation, if the vibration attenuation time exceeds the set value (e.g., >300ms), the system automatically issues an alert, prompting equipment maintenance, effectively reducing downtime.

[0110] Optionally, the current detection circuit is further 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 working voltage required for the operation of the first coil 11, 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.

[0111] The second coil 12 is connected in parallel to the energy storage capacitor via a rectifier bridge (such as the GBPC3510). When the piston rod vibrates, the alternating current generated by the second coil 12 is rectified and charges the energy storage capacitor, which then stores electrical energy (such as a 450V / 10mF electrolytic capacitor). 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's vibration converted into electrical energy. The energy storage capacitor stores this electrical energy as electric field energy, completing the "vibration energy → electrical energy → magnetic field energy" conversion chain, thereby reducing external power consumption.

[0112] The DC voltage output by the energy storage capacitor is connected to a DC-DC converter circuit (such as the LM5175 chip), where it is converted to the operating voltage required by the first coil 11 (e.g., 48V). This voltage is then supplied to the first coil 11 via the power bridge driver module. The DC-DC converter circuit uses a synchronous rectification Buck-Boost topology. When the energy storage capacitor voltage (range: 20-50V) is lower than the operating voltage, the circuit operates in Boost mode, raising 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, the relay is triggered to switch to the external power supply to ensure that the first coil 11 continues to receive stable power supply.

[0114] The dual power supply mode avoids interruptions in the reverse Ampere force caused by insufficient charge in the energy storage capacitor. For example, when performing continuous rapid pull-out tests (interval ≤ 1 minute), the automatic intervention of the external power supply ensures consistent seismic performance in each test cycle.

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

[0116] The impedance of the ferrite bead at a frequency of 100MHz is ≥100Ω, which can effectively attenuate the switching noise generated by the power bridge driver 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 the false output of reverse current due to noise.

[0117] Optionally, a unidirectional TVS diode (15V) is connected in parallel to 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 energy storage capacitor's voltage suddenly rises due to severe piston rod vibration (e.g., accidental overload), the TVS diode quickly breaks down and conducts, clamping the voltage to a safe range and preventing overvoltage damage to the DC-DC converter's input stage. Its 1ns response time also suppresses high-frequency surges. Combined with the energy storage capacitor's current-limiting properties, this provides dual protection, ensuring stable operation of the reverse current control module even in harsh power grid environments.

[0119] Optionally, the reverse current control module further includes an LED indicator light for displaying the vibration status of the device in real time; the energy storage capacitor can also provide power for the LED indicator light.

[0120] In one specific embodiment, the LED indicator uses a 5mm high-brightness red and green LED connected in parallel across an energy storage capacitor via a current-limiting resistor (100Ω). The LED consumes no more than 0.1W, maintaining low power consumption. The energy storage capacitor provides a stable DC power supply, eliminating the need for an external power supply. 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 for normal operation, flashing red for increased vibration).

[0121] Operators can quickly determine the equipment's seismic resistance by looking at the LED status. For example, at the moment a steel bar breaks, the LED turns from green to red and flashes at a high frequency, indicating that the piston rod's amplitude exceeds the threshold and the test parameters need to be adjusted.

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

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

[0124] In one specific embodiment, the buzzer uses a 5V active buzzer, connected to a storage capacitor via a switching transistor. When the inrush current of the current detection circuit exceeds the threshold, the transistor is triggered to conduct, causing the buzzer to sound an alarm. The storage capacitor maintains the buzzer's alarm even when the power supply is disconnected, ensuring that the device still sounds an alarm in the event of an abnormality, enhancing safety.

[0125] In one embodiment, the electromagnetic seismic pull-out testing machine provided by the present application also includes a third coil 13, which is arranged above the slide 3; an extension rod 5 is on the slide 3; when the steel bar is pulled off, the piston rod of the oil cylinder 2 is subjected to 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 reverse current to the third coil 13, so that the third coil 13 generates a downward Ampere force, thereby hindering the extension rod 5 from moving upward.

[0126] It should be explained that when the steel bar is pulled out, the piston rod will produce violent axial vibration due to the huge impact force. Figures 1 to 3 The piston rod will first jump upward quickly (the initial amplitude can reach 5-10mm), and then fall back due to inertia, forming a reciprocating attenuated vibration under the action of the seismic structure.

[0127] By setting up the third coil 13, when the piston rod jumps upward, the built-in permanent magnet moves axially in the second coil 12, cutting the magnetic flux lines to generate an induced current, the magnitude of which is proportional to the vibration speed. On the one hand, this current can be stored in the energy storage capacitor, and on the other hand, it can be fed back to the reverse current control module as a vibration signal. When the piston rod moves upward, the extension rod 5 on the slide 3 is inserted 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. Based on this current value, the reverse current control module supplies a reverse current to the first coil 11, generating an upward reverse Ampere force, slowing the piston rod's descent and forming a closed-loop damping control system that combines upward bounce suppression with downward fall buffering.

[0129] It should be noted that, for the third coil 13, after suppressing the initial bouncing of the piston rod, the reverse current value passed therein may not need to be adjusted based on the amplitude attenuation (maintaining the initial reverse current value unchanged), or the reverse current value passed therein may be adjusted based on the amplitude attenuation (the reverse current value may be changed synchronously with the first coil 11). Because the electromagnetic anti-seismic structure provided in this application can generate a reverse Ampere force compatible with the impact force through the first coil 11, during the actual shock absorption process, if the reverse Ampere force is no greater than the impact force, the piston rod will not jump upward again, but will instead gradually slow its falling speed. Therefore, after suppressing the initial bouncing of the piston rod, the third coil 13 can be directly de-energized to further save 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 also 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] The present application also provides a seismic resistance method, which is implemented using the above-mentioned electromagnetic seismic resistance pull-out testing machine and is 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 according to the first instantaneous maximum current value generated by the second coil 12, thereby suppressing the upward movement of the piston rod of the oil cylinder 2 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, thereby slowing down the falling speed of the piston rod through the first coil 11. The falling speed of the piston rod slows down and the amplitude decreases, the instantaneous maximum current value measured again decreases, and the reverse current value required to be supplied also decreases; The vibration of the piston rod gradually decays until it returns to calm.

[0132] Specifically, when the rebar is severed, the piston rod of cylinder 2 jumps violently upward due to the impact force. The internal permanent magnet moves axially within second coil 12, cutting the magnetic flux 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 third coil 13, causing it to generate a downward Ampere force, hindering the upward movement of extension rod 5 on slide 3 and thus suppressing the initial upward jump of the piston rod.

[0133] After the piston rod reaches its apex (with an upward velocity of zero) and then falls back, the permanent magnet flows in the opposite direction through the second coil 12, generating an induced current in the opposite direction. Based on the peak value of this induced current, the reverse current control module outputs a corresponding reverse current to the first coil 11, generating an upward Ampere force that slows the piston rod's descent. This reverse Ampere force matches the attenuated vibration energy, preventing piston rod "bounce" caused by overdamping.

[0134] After the first coil 11 completes the first anti-vibration, the movement speed of the piston rod slows down, and the induced current generated in the second coil 12 becomes smaller. The reverse current control module transmits a second reverse current to the first coil 11 according to 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 resistance, the amplitude of the piston rod gradually decreases and the vibration speed becomes slower and slower, and 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 input to the first coil 11 according to the change of the induced current peak value 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 anti-vibration technology matches the reverse Ampere force to the actual impact force and continuously changes the reverse Ampere force based on the impact force, precisely resisting shock vibration. This improves attenuation speed, reduces machine vibration amplitude, shortens the anti-vibration time, and improves the stability of the test equipment.

[0137] In a specific embodiment, a pull-out test is performed on a Φ20 mm steel bar.

[0138] At the moment of pulling out (t=0ms), the piston rod jumps upward violently due to the impact force, with an initial speed of V1=0.6m / s and a jumping amplitude of A1=8mm.

[0139] The second coil 12 cuts the magnetic flux lines of the permanent magnet, and a positive induced current is generated in the second coil 12, with an instantaneous maximum value I a =10A.

[0140] The reverse current control module is based on I a Output reverse current I to the third coil 13 3a =10A, generating a downward Ampere force F 3a =60N, preventing the extension rod 5 from moving upward.

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

[0142] After reaching the top of the jump, the piston rod 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 flux lines of the permanent magnet, and a reverse induced current is generated in the second coil 12, with an instantaneous maximum value I b =6A.

[0144] The reverse current control module is based on I b Output reverse current I to the first coil 11 1a =4.8A, generating an upward Ampere force F 1a =30N, slow down the falling speed.

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

[0146] The peak value of the induced current I in the second coil 12 c =3A.

[0147] The reverse current control module is based on I c Output reverse current I to the first coil 11 1b =2.4A, ampere force F 1b =15N, the fallback amplitude is further reduced to A3'=1.5mm.

[0148] The vibration amplitude of the piston rod continues to decrease, and the peak value of the induced current of the second coil 12 drops to I n <1A, the current output by the reverse current control module synchronously decays 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, and was considered to have returned to calm.

[0150] The above embodiments merely illustrate several implementation methods of the present application. 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 a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. An electromagnetic anti-vibration pull-out testing machine, characterized in that: include: Machine (1); An oil cylinder (2) is fixedly mounted on the machine platform (1), and a piston rod of the oil cylinder (2) is provided with a built-in permanent magnet; A slide (3) connected to the piston rod of the oil cylinder (2); An upper clamping jaw (4a) is provided on the slide (3); A lower clamping jaw (4b) is provided on the machine platform (1), is located below the upper clamping jaw (4a), and is arranged opposite to the upper clamping jaw (4a), and the upper clamping jaw (4a) and the lower clamping jaw (4b) can cooperate to clamp steel bars; A first coil (11) and a second coil (12) are both wound outside the oil cylinder (2), and the first coil (11) and the second coil (12) are arranged vertically spaced apart; During operation, the upper clamping jaw (4a) and the lower clamping jaw (4b) clamp the steel bar, and the oil cylinder (2) drives the slide (3) to rise to pull the steel bar; When the steel bar is pulled off, the piston rod of the oil cylinder (2) is subjected to the impact force and vibrates, and the piston rod moves axially in the second coil (12), and the second coil (12) cuts the magnetic flux lines and generates an induced current; The electromagnetic anti-seismic pull-out testing machine further includes a reverse current control module, which is used to detect the instantaneous maximum current generated by the second coil (12) due to the vibration of the piston rod when the steel bar is pulled out, and 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, the vibration speed slows down, 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 instantaneous maximum current value detected subsequently to match the continuously attenuated impact force.

2. The electromagnetic anti-vibration pull-out testing machine according to claim 1, characterized in that: The piston rod of the oil cylinder (2) comprises: The magnetic core shaft is made of soft magnetic alloy; The composite magnetic ring is formed by alternating NdFeB 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 outer shell.

3. The electromagnetic anti-vibration pull-out testing machine according to claim 2, characterized in that: The NdFeB magnetic rings are radially magnetized, and the radial magnetization directions of any two adjacent NdFeB 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 NdFeB magnetic rings. The soft magnetic ring 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.

4. The electromagnetic anti-vibration pull-out testing machine according to claim 2, characterized in that: The NdFeB magnetic ring and the soft magnetic ring are interference-fitted and filled with high-permeability potting glue to avoid the increase of magnetic resistance caused by the presence of air gap; And / or, the NdFeB magnetic ring is magnetized at a 45° tilt, and cooperates with the magnetic core shaft so that 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; And / or, the coaxiality error between the NdFeB magnetic ring and the soft magnetic ring is ≤0.02 mm to prevent induced current fluctuation caused by magnetic field eccentricity.

5. The electromagnetic anti-vibration pull-out testing machine according to claim 1, characterized in that: The first coil (11) and / or the second coil (12) are wound outside 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 spaced no more than 5 cm from the piston rod of the oil cylinder (2).

6. The electromagnetic anti-vibration pull-out testing machine according to claim 1, characterized in that: The oil in the oil cylinder (2) is a 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, increase the viscosity of the oil, and generate a damping force to suppress the vibration. The content of the graphene nanosheets is 1-2%. Adding the graphene nanosheets can improve the thermal conductivity of the oil.

7. The electromagnetic anti-vibration pull-out testing machine according to claim 1, characterized in that: The reverse current control module includes: control systems; A current detection circuit, wherein the second coil (12) is provided in the current detection circuit, and the current detection circuit is further provided with a current transformer, a signal conditioning module for filtering, amplifying and peak detection, and an analog-to-digital converter, wherein the signal conditioning module is capable of capturing the current generated in the second coil (12) in real time and feeding it back to the control system to achieve peak recognition; A power drive circuit, wherein the first coil (11) is provided in the power drive circuit, and the power drive circuit is further provided with a power supply, a power bridge drive module and a Hall current sensor. After the control system calculates the reverse current value, the reverse current is transmitted 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 matching 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 the reverse current to the first coil (11), and under the action of the reverse Ampere force, the amplitude of the piston rod of the oil cylinder (2) is attenuated, and the reverse current control module can adjust the output reverse current in real time until the vibration stops.

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

9. The electromagnetic anti-vibration pull-out testing machine according to any one of claims 1 to 8, characterized in that: It also includes a third coil (13), and the third coil (13) is arranged above the slide (3); An extension rod (5) is provided on the slide (3); When the steel bar is pulled out, the piston rod of the oil cylinder (2) is subjected to the 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 extension rod (5) from moving upward.

10. A seismic resistance method, implemented using the electromagnetic seismic resistance pulling tester according to claim 9, characterized in that: The following steps are involved: At the moment the steel bar is pulled off, the second coil (12) generates an induced current, and 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), thereby suppressing the upward movement of the piston rod of the oil cylinder (2) through the third coil (13); The piston rod falls back, and 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), thereby slowing down the falling speed of the piston rod through the first coil (11); The falling speed of the piston rod slows down and the amplitude decreases, the instantaneous maximum current value measured again decreases, and the reverse current value required to be supplied decreases accordingly; The vibration of the piston rod is continuously attenuated until it returns to calm.

Images