High load gear forming grinding device based on ultrasonic-assisted liquid gallium phase transformation strengthening

Abstract

The application provides a high-load gear forming grinding device based on ultrasonic-assisted liquid gallium phase transformation strengthening, which comprises a control module, an ultrasonic atomization module, a circulating liquid supply module, a temperature control module, a processing module and a recycling module. The control module is integrated with temperature, current and pressure controllers and dynamically adjusts ultrasonic frequency, liquid gallium flow and nitrogen pressure. The ultrasonic atomization module is composed of a high-porous high-pressure nozzle and an ultrasonic oscillation device and utilizes high-speed airflow to push liquid gallium droplets into a grinding area. The circulating liquid supply module composed of sectional spiral high-frequency electromagnetic coils ensures the stable circulation of liquid gallium supply and recycling. The temperature control module monitors the temperature distribution of the workpiece surface under high dynamic load of the grinding wheel through an infrared temperature sensor and controls the cooling rate and cooling area in a closed loop according to the actual grinding process changes in the processing process. The recycling module is used for recycling liquid gallium and realizing the reuse of liquid gallium.

Description

Technical Field

[0001] This invention relates to the field of high dynamic load gear precision grinding and metal phase transformation strengthening technology, specifically to a high dynamic load gear forming grinding device based on the ultrasonic rapid cooling assisted liquid gallium local phase transformation strengthening effect, and particularly to a dynamic closed-loop temperature-controlled grinding method that uses ultrasonic atomized liquid gallium to penetrate the grinding wheel gas barrier, induces the β phase of titanium alloy to be oriented to transform into the α′ metastable phase, and synergistically generates a gallium titanate (GaTi3) strengthening layer. Background Technology

[0002] Grinding, as a core process in precision manufacturing, is widely used in the final forming of high-dynamic-load gears in aerospace applications due to its advantages such as high machining accuracy and low surface roughness. However, high-dynamic-load gears in aerospace, precision instruments, and other fields require high strength, high corrosion resistance, and lightweight characteristics. These gears have extremely high requirements for tooth surface accuracy (such as titanium alloy TC4 gears) and are subjected to alternating impact loads during service; the stability of their surface microstructure directly determines their fatigue life. The higher the proportion of the α phase in the titanium alloy, the better the gear strength and corrosion resistance; while when the β phase proportion exceeds 70%, the fatigue life decreases by 25%-30%.

[0003] Titanium alloys have low thermal conductivity, leading to excessively high instantaneous temperatures in the grinding zone. This causes the surface α-phase to transform into the β-phase, reducing gear fatigue life. Traditional emulsion or liquid nitrogen cooling methods, due to their large droplet size and low kinetic energy, struggle to penetrate the gas barrier layer created by the high-speed rotation of the grinding wheel, resulting in a low proportion of the effective cooling area covering the grinding contact surface. While existing cooling technologies can reduce the average temperature, they cannot create a gradient cooling rate, leading to a random distribution of the β-phase and difficulty in the directional formation of the metastable α′ phase. Conventional coolants only serve a heat dissipation function and cannot undergo a controllable reaction with the titanium alloy to form a reinforcing layer, resulting in insufficient corrosion resistance of the gears.

[0004] Liquid gallium (GaN) is liquid at room temperature and possesses ultra-high thermal conductivity, low viscosity, and high surface activity. After ultrasonic atomization, GaN forms micron-sized droplets. Driven by high-pressure nitrogen, these droplets gain increased kinetic energy, effectively penetrating the gas barrier layer generated by the high-speed rotation of the grinding wheel and reaching the grinding interface. The GaN droplets evaporate and absorb heat in the grinding zone. Combined with its high thermal conductivity, this achieves a gradient cooling rate far exceeding that of traditional emulsion cooling. Titanium alloys, under rapid cooling conditions, follow a non-diffusion-type martensitic phase transformation: ultra-high-speed cooling creates a steep temperature gradient on the surface of the titanium alloy, forcing β-phase atoms to transform into the α′ phase before they can diffuse and recombine. The α′ phase has a high lattice distortion density, hindering dislocation movement and significantly improving the material's hardness and fatigue resistance. Liquid gallium penetrates to the surface of the titanium alloy and bonds with titanium atoms to form the metastable GaTi3 phase. The GaTi3 phase layer possesses both high hardness and corrosion resistance, compensating for the performance loss caused by the reduction of the β-phase and achieving a dual benefit of "phase transformation-strengthening."

[0005] The invention patent with publication number "CN107405753A" and invention title "A Gas-Liquid Two-Phase Jet Cooling Device" discloses a gas-liquid two-phase jet cooling device. Its principle is to spray the liquid at high speed into the machining area through a specially designed nozzle. The high-speed airflow atomizes the liquid into tiny droplets, increasing its surface area and thus improving cooling efficiency. Simultaneously, the impact of the airflow helps remove chips, prevents secondary cutting, and improves machining quality. However, this technical solution still has the following problems: while gas-liquid two-phase jets can improve cooling efficiency, the cooling effect may still be insufficient under high-temperature, high-speed cutting conditions, making it difficult to effectively control the temperature of the tool and workpiece, leading to thermal damage; under certain special machining conditions, its cooling and lubrication effects may be unsatisfactory, limiting its application range. Summary of the Invention

[0006] This invention addresses three major challenges in grinding titanium alloy gears under high dynamic loads in aerospace applications: air barriers hindering the penetration of cooling media, grinding heat-induced α→β phase transformation degradation, and lack of surface strengthening layers. It provides a high-dynamic gear grinding device based on ultrasonic rapid cooling-assisted liquid gallium phase transformation strengthening. Its core principle is as follows: ultrasonically atomized liquid gallium penetrates the air barrier of the grinding wheel, achieving ultra-high-speed cooling at the grinding interface. This induces the directional transformation of the titanium alloy's β phase into a high-strength metastable α′ phase. Simultaneously, gallium reacts with titanium to form a gallium titanate (GaTi3) strengthening layer. Combined with a closed-loop temperature control system that dynamically adapts to the grinding load, it achieves synergistic optimization of "cooling-phase transformation-strengthening".

[0007] This invention discloses a high-dynamic gear grinding device with ultrasonic rapid cooling assisted liquid gallium phase change enhancement. The high-dynamic gear grinding device includes an ultrasonic atomization module, a circulating liquid supply module, a temperature control module, and a processing module.

[0008] The ultrasonic atomization module includes: an ultrasonic source, an ultrasonic atomizer reservoir, and an ultrasonic atomizer; wherein, the ultrasonic atomizer 17 includes an atomizing nozzle and an ultrasonic transducer; the ultrasonic transducer includes a piezoelectric ceramic, which is used to provide ultrasonic oscillation for the liquid gallium in the ultrasonic atomizer reservoir so that it forms tiny atomized droplets through the atomizing nozzle, and the ultrasonic source and the piezoelectric ceramic control the number of atomized droplets by controlling the ultrasonic vibration frequency.

[0009] The circulating liquid supply module includes: a constant temperature liquid storage tank, a heat-resistant polymer pipe, a segmented spiral low-frequency electromagnetic coil, and a segmented spiral high-frequency electromagnetic coil; the constant temperature liquid storage tank is used to store the recovered gallium metal and the hydraulic power source to provide the liquid gallium required for cooling; the segmented spiral low-frequency electromagnetic coil and the segmented spiral high-frequency electromagnetic coil are alternately wound on the heat-resistant polymer pipe to ensure the delivery of liquid gallium to the ultrasonic atomization module;

[0010] The temperature control module includes: a temperature controller and a deflection electrode; the temperature controller monitors the temperature field of the grinding zone in real time and dynamically adjusts the voltage of the deflection electrode to make the droplet cluster directionally cover the high-temperature area;

[0011] The processing module includes: a grinding wheel, a workpiece, and a workpiece fixing plate; the workpiece fixing plate is fixedly placed on the grinding machine worktable; the workpiece is fixedly placed on the workpiece fixing plate; the grinding wheel is located above the workpiece and fixed on the rotating spindle of the grinding machine.

[0012] Furthermore, the ultrasonic atomization module continuously heats the liquid gallium within the atomization chamber using a heating element, ensuring its stable flow. Combined with piezoelectric ceramics and an ultrasonic transducer, it generates strong resonant oscillations. Employing a PLL algorithm, it monitors the feedback impedance characteristics of the ultrasonic transducer's resonant point and adjusts the output frequency of the drive signal in real time, achieving efficient excitation of the liquid gallium. Under the influence of factors such as temperature fluctuations, load changes, and variations in gallium flow rate, the resonant frequency may drift slightly. The PLL detects the current impedance phase difference Δθ and feeds it back to the frequency modulator, ensuring the output frequency f... out Continuously and automatically approximate the actual resonant frequency f r This enables dynamic closed-loop regulation.

[0013] Furthermore, the excitation of liquid gallium is as follows:

[0014]

[0015] Where, Δθ(t)=θ measured (t)-θ target (0)≈tan -1 (X / R), Δθ(t) represents the phase difference at time t, indicating the deviation between the currently measured phase and the target phase, used for PLL feedback adjustment calculations; θ measured (t) represents the actual operating phase angle calculated at time t by detecting the transducer voltage and current signals; θ target (0) represents the target phase angle set by the system, taken as 0°; X represents the imaginary part of the transducer's equivalent impedance, used to characterize the degree to which the system deviates from the resonant point; R represents the real part of the transducer's equivalent impedance, used to characterize the energy loss in the resonant state; t represents the current discrete time step, used for iterative calculation and real-time control; n represents the historical sampling sequence number in the integral operation, all accumulated data points from the initial time n = 0 to the current time n = t; K p K i For the proportional and integral gain coefficients of the PLL controller;

[0016] By combining the pressure, heat flow, and impact feedback among the grinding wheel, liquid gallium, and workpiece, a coupled feedback control equation of "grinding load-impedance feedback" is designed, and a composite load factor L is established.dyn :

[0017] L dyn =α·F g +β·Q t +γ·ΔT

[0018] Among them, F g Q is the normal force during grinding; t denoted as transient heat flux density; ΔT is the temperature difference between liquid gallium and the grinding zone; α, β, γ are coupling coefficients obtained through modeling or experimental fitting.

[0019] Then introduce it into the frequency control formula:

[0020]

[0021] Among them, f opt f0 is the current optimal operating frequency, which serves as the reference input value for the PLL controller; k is the current operating frequency; k is the adjustment gain. This indicates the sensitivity of the frequency response to load coupling; the system can automatically adjust the excitation frequency according to the real-time changes in grinding load to ensure optimal efficiency of liquid gallium excitation and avoid oscillation or overload.

[0022] Furthermore, the droplets formed by the liquid gallium in the temperature control module after being charged by the atomizing electrode will be deflected in the electrostatic field formed between the deflection electrodes (27), and their trajectory follows the simplified form of the Lorentz force equation:

[0023] F = qE = ma

[0024] F is the Lorentz force, E is the electric field strength, m is the droplet mass, q is the charge, and a is the acceleration of the droplet under the influence of the electrostatic field.

[0025] The deflection angle θ of the droplet is related to the applied electric field strength E, the droplet mass m, the charge q, and the flight time t as follows:

[0026]

[0027] Where L is the jet length, and t can be calculated from the flight path and initial velocity;

[0028] Real-time temperature distribution maps of the workpiece surface are obtained using thermal imaging or a thermocouple matrix. Hot spots appear in the x, y plane coordinates (x, y). h y h If the origin is (0,0) at the center nozzle, then the target deflection angle is:

[0029]

[0030] Where d is the distance from the nozzle to the workpiece surface;

[0031] Based on the target deflection angle and the characteristics of the droplets, the deflection voltage can be deduced:

[0032]

[0033] Where, d e It is the deflection electrode spacing, and the final high voltage U applied to the system. x and U y Control the deflection electrode to achieve precise control of targeted spraying.

[0034] Furthermore, the ultrasonic rapid cooling assisted liquid gallium phase change enhanced high-dynamic gear grinding device also includes a recycling module; the recycling module includes: a coarse vibrating filter membrane, a fine vibrating filter membrane, an electromagnet block, a recycling box, and an external magnetic field; the coarse vibrating filter membrane is above the fine vibrating filter membrane, and below the fine vibrating filter membrane are the electromagnet block, the recycling box, and the external magnetic field in sequence; the outer side of the electromagnet block is a smooth inclined flow channel, and the direction of the pulsed magnetic field is perpendicular to the direction of the magnetic field of the electromagnet block, which promotes particle shedding through Lorentz force;

[0035] When the electromagnet block is energized and becomes magnetic, the nanoparticles are adsorbed onto the flow channel wall. When the power is turned off, the nanoparticles can be successfully detached under the influence of the external magnetic field.

[0036] The recycling box is equipped with an automatic switch to control the opening and closing of the box lid; the automatic switch is connected to the electromagnet block mentioned above, and it is closed when the electromagnet is powered on and opened when the power is cut off.

[0037] Furthermore, the ultrasonic atomization module includes a nitrogen source and a nitrogen pipe;

[0038] The nitrogen source provides a high-speed nitrogen flow of 0.5–0.8 MPa through the nitrogen pipe, which is sprayed out synchronously with the droplets through the atomizing nozzle, breaking through the air barrier on the outside of the grinding wheel, so that the atomized liquid gallium droplets are enveloped by nitrogen gas, reducing the oxidation of gallium.

[0039] The beneficial effects achieved by this invention are:

[0040] Micron-sized liquid gallium droplets are generated through ultrasonic atomization. Combined with high-speed nitrogen injection and electric field deflection, these droplets rapidly penetrate the grinding wheel's gas barrier and are directed to the center of the grinding zone, achieving an ultra-high-speed cooling rate (>10). 4 (℃ / s). This cooling rate induces the β phase in the titanium alloy to transform into α′ martensite (metastable phase), forming a material layer with high hardness, high corrosion resistance, and fatigue resistance. To optimize the temperature field in real time, infrared temperature monitoring and deflection electrodes are used to control the droplet jet direction. The temperature is dynamically adjusted based on a feedback system, and thermal deformation is suppressed. Grinding thermal regulation and machining force feedback logic work together to precisely control the temperature and reduce grinding force fluctuations caused by thermal stress.

[0041] Through a precisely designed atomizing nozzle and nitrogen-driven pressure control, the resulting jet kinetic energy effectively breaks down the air barrier layer on the outside of the grinding wheel (a centrifugal air barrier generated by the high-speed rotation of the grinding wheel), allowing micron-sized droplets to effectively penetrate into the grinding zone. The combination of liquid gallium's ultra-high thermal conductivity and the high-speed atomization evaporation heat absorption mechanism significantly improves cooling efficiency, making it five times more efficient than traditional coolants. A dual-stage vibration filtration and electromagnetic recovery technology ensures efficient recovery and reuse of liquid gallium, while the recovery process is carried out in a low-oxygen environment, effectively reducing gallium loss and waste liquid discharge.

[0042] By integrating a multi-parameter closed-loop control system that incorporates current, temperature, pressure, and magnetic field, the system automatically adapts to load fluctuations and heat input under different working conditions, achieving a high degree of self-adaptation in the grinding process, optimizing grinding results, and reducing manual intervention. Attached Figure Description

[0043] Figure 1 : A schematic diagram of a high dynamic load gear forming and grinding device based on the enhanced effect of local phase transition of liquid gallium assisted by ultrasonic rapid cooling.

[0044] Figure 2 : Schematic diagram of cross-section of atomizing device.

[0045] Figure 3 Schematic diagram of a spiral electromagnetic coil conveying pipeline.

[0046] In the diagram, 1. Main controller, 2. Current controller, 3. Pressure controller, 4. Atomizing nozzle, 5. Piezoelectric ceramic, 6. Ultrasonic transducer, 7. Ultrasonic source, 8. Vibration damping pad, 9. Heating wire, 10. Charging electrode, 11. High-voltage power supply, 12. Power converter, 13. Nitrogen source, 14. Nitrogen pipe, 15. Pressure detector, 16. Ultrasonic atomizer reservoir, 17. Ultrasonic atomizer, 18. Constant temperature reservoir, 19. 20. Segmented spiral low-frequency electromagnetic coil; 21. Segmented spiral high-frequency electromagnetic coil; 22. Overflow valve; 23. Check valve; 24. Pressure reducing valve; 25. Temperature controller; 26. Infrared sensor; 27. Deflection electrode; 28. Coarse vibrating filter membrane; 29. ​​Fine vibrating filter membrane; 30. Electromagnetic block; 31. Recycling box; 32. External magnetic field; 33. Grinding wheel; 34. Workpiece; 35. Workpiece fixing plate. Detailed Implementation

[0047] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0048] An ultrasonic rapid cooling-assisted liquid gallium phase transformation strengthening high-dynamic gear grinding device essentially achieves ultra-high-speed cooling and directional transformation of the β→α′ phase of titanium alloy at the grinding interface by ultrasonically atomizing liquid gallium through the air barrier of the grinding wheel, while generating a gallium titanate (GaTi3) strengthening layer. Combined with a closed-loop temperature control system to dynamically adjust the cooling parameters, it solves the problems of insufficient cooling penetration, uncontrollable phase transformation and surface performance degradation in traditional grinding.

[0049] This device includes: a control module, an ultrasonic atomization module, a circulating liquid supply module, a temperature control module, a recovery module, and a processing module.

[0050] The control module includes: main control unit 1, current controller 2, and pressure controller 3;

[0051] The ultrasonic atomization module includes: an ultrasonic source 7, a charging electrode 10, a high-voltage power supply 11, a power converter 12, a nitrogen source 13, a nitrogen pipe 14, a pressure detector 15, an ultrasonic atomizer reservoir 16, and an ultrasonic atomizer 17; wherein, the ultrasonic atomizer 17 includes an atomizing nozzle 4, an ultrasonic transducer 6, a shock-absorbing pad 8, and a heating wire 9; the ultrasonic transducer 6 includes a piezoelectric ceramic 5.

[0052] The circulating liquid supply module includes: a constant temperature liquid storage tank 18, a heat-resistant polymer pipeline 19, a segmented spiral low-frequency electromagnetic coil 20, a segmented spiral high-frequency electromagnetic coil 21, an overflow valve 22, a one-way valve 23, and a pressure reducing valve 24.

[0053] The temperature control module includes: a temperature controller 25, an infrared sensor 26, and a deflection electrode 27;

[0054] The recycling module includes: a coarse vibrating filter membrane 28, a fine vibrating filter membrane 29, an electromagnet block 30, a recycling box 31, and an external magnetic field 32;

[0055] The processing module includes: grinding wheel 33, workpiece 34, and workpiece fixing plate 35.

[0056] The connection methods of each module are as follows Figure 1 As shown.

[0057] The control module consists of a main controller 1, a CAN bus, a grinding wheel spindle drive motor and a workpiece feed servo system, as well as a current controller 2, a temperature controller 25, and a pressure controller 3. The main controller 1 is connected to the grinding wheel spindle drive motor and the feed servo system via the CAN bus to achieve overall motion synchronization. The current controller 2 is connected to the ultrasonic source 7, high and low frequency electromagnetic coils 20 / 21, and electromagnet block 30 via shielded twisted-pair cables, adjusting their output power (200–500W), excitation current (5–10A), and magnetic field strength (0.8–1.2T), respectively. The temperature controller 25 is connected to the infrared sensor 26 via a thermocouple interface and controls the heating wire 9 (100–500W) and the heater (25–35℃) of the constant temperature storage tank 18 via a solid-state relay. The pressure controller 3 drives the electromagnetic pressure regulating valve before the nitrogen source 13 using a PID algorithm to maintain a supply pressure of 0.5–0.8MPa. This module continuously coordinates the various subsystems during processing to achieve closed-loop control of energy and fluid parameters throughout the entire process.

[0058] like Figure 2 The ultrasonic atomizing module shown is fixed to the side base of the machine tool table. To ensure stability, a damping pad 8 with a damping coefficient ≥0.7 is installed outside the transducer to reduce the vibration amplitude transmitted to the machine tool base. The piezoelectric ceramic 5 generates high-frequency vibration of 20–40kHz under the drive of the ultrasonic source 7. This vibration is transmitted to the ultrasonic transducer 6 and forms an axial vibration field in the nozzle cavity, thereby atomizing the liquid gallium liquid into micron-sized droplets and spraying them out through the atomizing nozzle 4. At the same time, a heating wire 9 surrounds the outer wall of the nozzle, and the cavity temperature is maintained at 30–40℃ through a threaded interface to prevent the gallium liquid from solidifying. The above components together constitute the ultrasonic atomizer 17 and are connected to the ultrasonic atomizer storage chamber 16 to realize the continuous supply of atomized liquid. The peripheral components include a nitrogen source 13, a nitrogen pipe 14, and a pressure detector 15, which provide and monitor a high-speed airflow of 0.5–0.8 MPa to carry the droplets to the grinding zone and break through the air barrier of the grinding wheel. At the same time, the power converter 12 and the high-voltage power supply 11 provide a 5–10 kV electric field to the charging electrode 10, so that the droplets are charged during the spraying process and can be deflected by ±3° under the action of the deflection electrode, thereby achieving precise coverage of the grinding wheel-workpiece contact interface by the droplets.

[0059] By introducing a heating element into the atomization chamber to continuously heat the liquid gallium, its stable flow state is ensured. Combined with a high-frequency piezoelectric ceramic transducer system to generate strong resonant oscillations, and an integrated frequency tracking module employing a PLL (Phase Locked Loop) algorithm, the output frequency of the drive signal is adjusted in real time by monitoring the feedback impedance characteristics of the ultrasonic transducer's resonant point, achieving efficient excitation of the liquid gallium. Under the influence of factors such as temperature fluctuations, load changes, and changes in gallium flow rate, the resonant frequency will drift slightly. The PLL detects the current impedance phase difference Δθ and feeds it back to the frequency modulator to adjust the output frequency f.out Continuously and automatically approximate the actual resonant frequency f r This achieves dynamic closed-loop regulation. The mathematical essence of the regulation mechanism is:

[0060]

[0061] Where, Δθ(t)=θ measured (t)-θ target (0)≈tan -1 (X / R), while the target phase is 0 degrees (pure resistive state), K p K i These are the proportional and integral gain coefficients of the PLL controller.

[0062] Δθ(t) represents the phase difference at time t, which is the deviation between the currently measured phase and the target phase, and is used for PLL feedback adjustment calculation;

[0063] θ measured (t) represents the actual operating phase angle calculated at time t by detecting the voltage and current signals of the transducer;

[0064] θ target (0) represents the target phase angle set by the system, which is 0° (i.e., the voltage and current are in phase under pure resistance).

[0065] X represents the imaginary part (reactance) of the transducer's equivalent impedance, used to characterize the degree to which the system deviates from its resonant point (unit: ohms).

[0066] R represents the real part (resistance) of the transducer's equivalent impedance, used to characterize the energy loss in the resonant state (unit: ohms);

[0067] t represents the current discrete-time step, used for iterative calculation and real-time control;

[0068] The historical sampling sequence number in the n-integral operation refers to all the cumulative data points from the initial time n=0 to the current time n=t.

[0069] By combining the pressure, heat flow, and impact feedback among the grinding wheel, liquid gallium, and workpiece, a coupled feedback control equation of "grinding load-impedance feedback" is designed, and a composite load factor L is established. dyn :

[0070] L dyn =α·F g +β·Q t +γ·ΔT

[0071] Among them, F g Grinding normal force;

[0072] Q tTransient heat flux density;

[0073] ΔT: Temperature difference between liquid gallium and the grinding zone;

[0074] α, β, γ: Coupling coefficients obtained through modeling or experimental fitting.

[0075] Then introduce it into the frequency control formula:

[0076]

[0077] Where f0: current operating frequency;

[0078] k: Adjust the gain;

[0079] This indicates the sensitivity of the frequency response to load coupling.

[0080] f opt The current optimal operating frequency is used as the reference input value for the PLL controller.

[0081] The system can automatically adjust the excitation frequency according to the real-time changes in grinding load to ensure optimal excitation efficiency of liquid gallium and avoid idling or overload; nitrogen-encased spraying further enhances droplet delivery capacity and effectively prevents oxidation.

[0082] The circulating liquid supply module is connected to the upstream and downstream pipelines of the atomizing module and the constant temperature liquid storage tank 18 via flanges and quick-connect fittings. Figure 3 The conveying device shown consists of a heat-resistant polymer pipe 19, on which low-frequency coils 20 (1–5kHz) and high-frequency coils 21 (50–100kHz) are evenly and alternately wound. Both ends are connected to the pipe interface via clamps. An adjustable overflow valve 22 is installed in the middle section of the pipe. During operation, liquid gallium flows into the storage tank 18 through the pipe. The low / high-frequency coils generate a magnetic field of 0.1–0.5T under the drive of alternating current, which propels the gallium along the pipe in a directional manner (10–20mL / min) through the magnetostrictive effect. The boron nitride coating on the inner wall is fixed to the inner wall of the pipe after high-temperature curing (temperature resistance >200℃) to reduce frictional resistance. The overflow valve 22 releases pressure in real time, stabilizing the system pressure at 0.3–0.6MPa to prevent overload and ensure stable supply.

[0083] The temperature control module consists of an infrared sensor 26, a temperature controller 25, a deflection electrode 27, a pressure detector 15, and a pressure controller 3, all interconnected via signal and control cables. The infrared sensor 26 is fixed above the droplet injection nozzle by a bracket and connected to the temperature input terminal of the controller 25. The deflection output terminal of the controller 25 is connected to the deflection electrode 27 via a high-voltage cable. The pressure detector 15 is connected in series in the nitrogen pipeline and feeds back the pressure signal to the pressure controller 3 via an analog interface. During operation, the infrared sensor 26 samples the temperature of the grinding zone at ≥100Hz. The controller 25 reconstructs the heat distribution based on a PID algorithm and outputs a 5–10kV signal to the deflection electrode 27 to guide the droplets for directional cooling. Simultaneously, the pressure detector 15 monitors the nitrogen pressure and feeds the information back to the pressure controller 3, which adjusts the pressure regulating valve to maintain a pressure of 0.5–0.8MPa, thus ensuring stable temperature (±2℃) and injection kinetic energy through a dual closed-loop system.

[0084] During the grinding process, the control system applies high-voltage electrical signals (100–3000V DC) of different polarities between different electrodes, generating a spatially directional electric field distribution and forming a "potential gradient path". As the charged droplets are subjected to Coulomb force in the electric field, their trajectory is controllably deflected, and the deflection angle can be precisely controlled within the range of 1°–20°, thereby achieving high-precision control of the droplet spray direction.

[0085] The injection of liquid gallium droplets directly acts on the gear surface, achieving not only efficient cooling but also significantly improving surface quality through a local phase transition enhancement effect.

[0086] To achieve intelligent response, the main controller pre-establishes a thermal field model and an electric field control function library, and communicates with a 26-array infrared temperature sensor. The sensors collect temperature distribution data of the grinding contact area every second and upload it to the main control system. Liquid gallium droplets, after being charged by the atomizing electrodes, will deflect in the electrostatic field between the deflecting electrodes; their trajectory can be approximated as obeying a simplified form of the Lorentz force equation:

[0087] F = qE = ma

[0088] F is the Lorentz force, E is the electric field strength, m is the droplet mass, q is the charge, and a is the acceleration of the droplet under the influence of the electrostatic field.

[0089] The deflection angle θ of the droplet is related to the applied electric field strength E, the droplet mass m, the charge q, and the flight time t as follows:

[0090]

[0091] Where L is the jet length, and t can be calculated from the flight path and initial velocity. This model provides a basis for deflection voltage design. Real-time temperature distribution maps of the workpiece surface are obtained through thermal imaging or a thermocouple matrix. It is assumed that the hotspot appears in the x, y plane with coordinates (x...). h y h If the origin is (0,0) at the center nozzle, then the target deflection angle is:

[0092]

[0093] Where d is the distance from the nozzle to the workpiece surface.

[0094] Based on the target deflection angle, and considering the droplet characteristics (mass m, initial velocity v, and charge q), the deflection voltage can be derived:

[0095]

[0096] Among them, E x E represents the electric field strength in the x-direction. y d represents the electric field intensity in the y-direction. e It is the deflection electrode spacing, and the final high voltage U applied to the system. x U y Control the deflection electrode to achieve precise control of targeted spraying.

[0097] The recovery module is mounted on the other side of the workbench and is connected to the waste liquid collection pipe of the grinding area via a flange pipe. The main body includes a coarse vibrating filter membrane 28, a fine vibrating filter membrane 29, an electromagnet block 30, and a recovery box 31. The waste liquid passes through the vibrating filter units 28 (pore size 1μm, amplitude 50–100μm) and 29 (pore size 100nm, amplitude 10–20μm) on the fixed support, and large particles and ultrafine debris are intercepted in sequence. The end of the pipe is connected to the annular electromagnet block 30, which is fastened to the flange seat on the outer wall of the pipe by threads and connected to the magnetic field output terminal of the current controller 2. When energized, the electromagnet block 30 generates a static magnetic field of ≥0.8T, which adsorbs gallium-containing particles onto the inner wall of the inclined flow channel; after de-energization, the same or parallel coil switches to a 0.2–0.4T, 1–10Hz pulse mode. The rapidly changing magnetic field generates a Lorentz force that causes the gallium particles to desorb and fall into the recovery box 31 through the bottom outlet. The entire recovery process is completed in a nitrogen-filled sealed chamber (oxygen content <0.1%), ensuring a recovery rate of ≥95%.

[0098] The machining module consists of a CBN grinding wheel 33, a workpiece fixing plate 35, and a vacuum adsorption system. It is connected to the machine tool spindle via a flange base, and the vacuum pipeline is directly connected to the vacuum pump via a quick-connect interface at the bottom of the workpiece fixing plate. During machining, the CBN grinding wheel rotates at a linear velocity of 80–120 m / s, and the workpiece is fed at 0.3 mm / rev under vacuum adsorption (positioning accuracy <2 μm). Directional cooling of liquid gallium droplets ensures a cooling rate >104℃ / s, resulting in a Ti alloy β-phase conversion rate ≥90% and the formation of a 50–100 μm thick GaTi3 reinforcement layer (HV≥800). After machining, the tooth surface Ra <0.4 μm, the tooth profile error <5 μm, and no corrosion after >1500h of salt spray testing, with a 30%–35% improvement in fatigue life.

[0099] Key parameters for implementation: Liquid gallium is produced using high-purity materials with a purity ≥ 99.99%, and the droplets are ultrasonically atomized to form D... 50 The surface roughness is approximately 5–8 μm; the nitrogen injection pressure is constant at 0.6 MPa; the closed-loop temperature control system maintains the temperature control accuracy of the grinding zone within ±2℃; grinding is performed using 80–120 mesh ceramic bonded CBN grinding wheels, with a linear speed of 80–120 m / s (100 m / s recommended) and a workpiece feed rate of 0.3 mm / rev; the workpiece is precisely positioned by a vacuum adsorption fixing plate with an adsorption force of ≥200 N (accuracy <2 μm). After machining, the tooth surface roughness Ra <0.4 μm (automatic stop threshold Ra ≥0.35 μm), tooth profile error <5 μm, a 50–100 μm thick GaTi3 reinforcement layer (hardness HV ≥800) is generated, salt spray corrosion resistance >1500 h, fatigue life is increased by 30%–35%, and grinding force fluctuation is controlled within ±6%.

[0100] Operating Procedure: Start the constant temperature storage tank 18 to preheat the liquid gallium to 30℃; pressurize the nitrogen source 13 to 0.6MPa; the grinding wheel 33 rotates at a linear velocity of 100m / s, and the workpiece 34 feeds at a rate of 0.3mm / rev; atomization spraying: the ultrasonic source 7 outputs a 30kHz frequency to generate droplets that penetrate the air barrier; the infrared sensor 26 monitors the temperature in real time, and the deflection electrode 27 tracks and cools the high-temperature zone; the waste liquid is filtered by vibration and electromagnetic adsorption. Shutdown Conditions: Automatic shutdown occurs when the tooth surface roughness Ra reaches 0.35μm or the grinding force exceeds the threshold ±8%.

[0101] The above are merely specific steps of the present invention and do not constitute any limitation on the scope of protection of the present invention; all technical solutions formed by equivalent transformation or equivalent substitution fall within the scope of protection of the present invention; the parts of the present invention not described in detail are common knowledge to those skilled in the art.

Claims

1. A high dynamic gear grinding device with ultrasonic rapid cooling assisted liquid gallium phase transformation strengthening, characterized in that, The high-dynamic gear grinding device includes an ultrasonic atomization module, a circulating liquid supply module, a temperature control module, and a processing module; The ultrasonic atomization module includes: an ultrasonic source (7), an ultrasonic atomizer reservoir (16), and an ultrasonic atomizer (17); wherein, the ultrasonic atomizer (17) includes an atomizing nozzle (4) and an ultrasonic transducer (6); the ultrasonic transducer (6) includes a piezoelectric ceramic (5), which is used to provide ultrasonic oscillation for the liquid gallium in the ultrasonic atomizer reservoir (16) so that it forms tiny atomized droplets through the atomizing nozzle (4); the ultrasonic source (7) and the piezoelectric ceramic (5) control the number of atomized droplets by controlling the ultrasonic vibration frequency. The circulating liquid supply module includes: a constant temperature storage tank (18), a heat-resistant polymer pipe (19), a segmented spiral low-frequency electromagnetic coil (20), and a segmented spiral high-frequency electromagnetic coil (21); the constant temperature storage tank (18) is used to store the recovered gallium metal and hydraulic oil to provide the liquid gallium required for cooling; the segmented spiral low-frequency electromagnetic coil (20) and the segmented spiral high-frequency electromagnetic coil (21) are alternately wound on the heat-resistant polymer pipe (19) to ensure the delivery of liquid gallium to the ultrasonic atomization module; The temperature control module includes: a temperature controller (25) and a deflection electrode (27); the temperature controller (25) monitors the temperature field of the grinding zone in real time and adjusts the voltage of the deflection electrode (27) to make the droplet group cover the high temperature area in a directional manner. The processing module includes: a grinding wheel (33), a workpiece (34), and a workpiece fixing plate (35); the workpiece fixing plate (35) is fixedly placed on the worktable of the grinding machine; the workpiece (34) is fixedly placed on the workpiece fixing plate (35); the grinding wheel (33) is located above the workpiece (34) and fixed on the rotating spindle of the grinding machine; The ultrasonic rapid cooling assisted liquid gallium phase change enhanced high dynamic gear grinding device also includes a recycling module; the recycling module includes: a coarse vibration filter membrane (28), a fine vibration filter membrane (29), an electromagnet block (30), a recycling box (31), and an external magnetic field (32); the coarse vibration filter membrane (28) is above the fine vibration filter membrane (29), and below the fine vibration filter membrane (29) are the electromagnet block (30), the recycling box (31), and the external magnetic field (32); the outer side of the electromagnet block (30) is a smooth inclined flow channel, and the direction of the pulse magnetic field is perpendicular to the direction of the magnetic field of the electromagnet block (30), which causes the particles to fall off through the Lorentz force; After the electromagnet block (30) is energized and becomes magnetic, the nanoparticles are adsorbed onto the flow channel wall. When the power is turned off, the nanoparticles can be successfully detached under the influence of the external magnetic field (32). The recycling box (31) is equipped with an automatic switch to control the opening and closing of the box lid; the automatic switch is connected to the electromagnet block (30) mentioned above, and it is closed when it is powered on and opened when it is powered off. The ultrasonic atomization module also includes a nitrogen source (13) and a nitrogen pipe (14). The nitrogen source (13) provides a high-speed nitrogen flow of 0.5~0.8MPa through the nitrogen pipe (14), which is sprayed out synchronously with the droplets through the atomizing nozzle (4), breaking through the air barrier outside the grinding wheel (33), so that the atomized liquid gallium droplets are wrapped by nitrogen, reducing the oxidation of gallium.

2. The high dynamic gear grinding device with liquid gallium phase transformation strengthening assisted by ultrasonic rapid cooling according to claim 1, characterized in that, The ultrasonic atomization module continuously heats the liquid gallium by introducing a heating element in the atomization cavity to ensure that it remains in a stable flow state; the piezoelectric ceramic (5) and the ultrasonic transducer (6) produce strong resonance oscillation, the output frequency of the driving signal is adjusted in real time by using the PLL algorithm and monitoring the feedback impedance characteristics of the resonance point of the ultrasonic transducer (6), and the liquid gallium is efficiently excited; under the influence of factors such as temperature fluctuation, load change, and gallium flow change, the resonance frequency will slightly drift, the current impedance phase difference is detected by using the PLL algorithm and the frequency of the feedback frequency modulator is adjusted, so that the output frequency continuously and automatically approaches the actual resonance frequency , and dynamic closed-loop regulation is achieved.

3. The high dynamic gear grinding device with liquid gallium phase transformation strengthening assisted by ultrasonic rapid cooling according to claim 2, characterized in that, The excitation for liquid gallium is: ； in, , It represents the phase difference at time t, and indicates the deviation between the currently measured phase and the target phase; This represents the actual operating phase angle calculated at time t by detecting the transducer voltage and current signals; This represents the target phase angle set by the system, which is 0°. The imaginary part of the transducer's equivalent impedance is used to characterize the degree to which the system deviates from its resonant point. The real part of the equivalent impedance of the transducer is used to characterize the energy loss in the resonant state. This represents the current discrete-time step count, used for iterative calculations and real-time control. This represents the historical sampling sequence number in the integration operation, representing all accumulated data points from the initial time n=0 to the current time n=t; This refers to the proportional gain coefficient of the controller using the PLL algorithm. The integral gain coefficient of the controller using the PLL algorithm; And combined with the pressure, heat flow, impact feedback between the grinding wheel-liquid gallium-workpiece, design "grinding load-impedance feedback" coupling feedback control equation, establish the composite load factor : ； wherein, is the grinding normal force; is the transient heat flux; is the temperature difference between liquid gallium and the grinding zone; a, b, g are coupling coefficients obtained by modeling or experimental fitting; Then introduce it into the frequency control formula: ； wherein, is the current best operating frequency, as a reference input value for the controller employing the PLL algorithm; is the current operating frequency; is the adjustment gain; represents the sensitivity of the frequency response to the load coupling; the system can automatically adjust the excitation frequency in real time according to the change of the grinding load, ensure the optimal excitation efficiency of liquid gallium, and avoid air vibration or overload.

4. The high dynamic gear grinding apparatus with liquid gallium phase transformation strengthening assisted by ultrasonic rapid cooling according to claim 1, characterized in that, In the temperature control module, the liquid gallium droplets formed after being charged by the atomizing electrode will deflect in the electrostatic field formed between the deflecting electrodes (27), and their trajectory will obey the simplified form of the Lorentz force equation: ； is the Lorentz force, E is the electric field strength, m is the droplet mass, q is the charge, is the acceleration of the droplet under the influence of the electrostatic field; The deflection angle θ of the droplet is related to the applied electric field strength E, the droplet mass m, the charge q, and the flight time t as follows: ； Where L is the jet length, and t can be calculated from the flight path and initial velocity; Real-time temperature distribution maps of the workpiece surface are obtained through thermal imaging or thermocouple matrix. Hot spots appear at coordinates (xy-plane coordinates). , If the origin is (0,0) at the center nozzle, then the target deflection angle is: ， ； Where d is the distance from the nozzle to the workpiece surface; Based on the target deflection angle and the characteristics of the droplets, the deflection voltage can be deduced: ， ； ， ； wherein, is the deflection electrode pitch, the high voltage applied by the final system and the deflection electrodes are controlled to enable precise control of the targeted jet.

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